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fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.3 TSC Assistance Container determination by TSCTSF | The TSCTSF constructs TSC Assistance Container (defined in Table 5.27.2-2) based on information provided (directly or via NEF) by the AF for IP or Ethernet type PDU Sessions, or by the DetNet controller for IP type PDU Sessions.
In the case of an AF request, the AF may provide Flow Direction, Burst Arrival Time (optional) at the UE/DS-TT (uplink) or UPF/NW-TT (downlink), Maximum Burst Size, Periodicity, Survival Time (optional) and a Time Domain (optional) to the TSCTSF. If the AF is able to adjust the burst sending time, the AF may in addition provide a BAT Window or the Capability for BAT adaptation to the TSCTSF. Addtionally if the AF is able to adjust the periodicity, the AF may also provide the Periodicity Range along with the Periodicity to the TSCTSF. Based on these parameters, the TSCTSF constructs a TSC Assistance Container and provides it to PCF. If the AF provides to the TSCTSF a Burst Arrival Time or Periodicity without corresponding Time Domain, the TSCTSF sets the Time Domain = "5GS" in the TSC Assistance Container.
If the AF is able to adjust the transmission time and periodicity then in addition to above parameters, it may provide a BAT Window (optional) or the capability for BAT adaptation (optional), or Periodicity Range (optional), to the TSCTSF.
NOTE: The Maximum Burst Size is signalled separately, i.e. it is not part of the TSC Assistance Container.
The AF provides these parameters to the NEF and the NEF forwards these parameters to the TSCTSF. The AF trusted by the operator provides these parameters to the TSCTSF directly.
In the case of Deterministic Networking, the TSCTSF constructs the TSC Assistance Container based on information provided by the DetNet controller as defined in clause 6.1.3.23b of TS 23.503 [45].
The TSCTSF sends the TSC Assistance Container to the PCF as follows:
- The TSCTSF uses the UE IP address/DS-TT port MAC address to identify the PCF and N5 association related to the PDU Session of a UE/DS-TT. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.4 TSCAI determination based on TSC Assistance Container | The SMF determines the TSCAI (defined in Table 5.27.2-1) for the QoS Flow based on the TSC Assistance Container of the PCC rule bound to the QoS Flow. This clause is applicable irrespective of whether the TSC Assistance Container is determined by the TSN AF or by the TSCTSF.
The Burst Arrival Time and Periodicity component of the TSCAI that the SMF sends to the 5G-AN are specified with respect to the 5G clock. The SMF is responsible for mapping the Burst Arrival Time and Periodicity in the TSC Assistance Container from an external clock to the 5G clock based on the time offset and cumulative rateRatio (when available) between external time and 5GS time as measured and reported by the UPF. The SMF may correct the TSCAI based on the UPF report for time offset and cumulative rateRatio between external PTP time and 5GS time as measured and reported by the UPF.
The TSCAI parameter determination in SMF is done as follows:
- For traffic in downlink direction, the SMF corrects the Burst Arrival Time in the TSC Assistance Container based on the latest received time offset measurement from the UPF and sets the TSCAI Burst Arrival Time as the sum of the corrected value and the static value for the CN PDB (as defined in clause 5.7.3.4), representing the latest possible time when the first packet of the data burst arrives at the AN.
- For traffic in uplink direction, the SMF corrects the Burst Arrival Time in the TSC Assistance Container based on the latest received time offset measurement from the UPF and sets the TSCAI Burst Arrival Time as the sum of the corrected value and UE-DS-TT Residence Time, representing the latest possible time when the first packet of the data burst arrives at the egress of the UE. How the SMF corrects the Burst Arrival Time if the UE-DS-TT Residence Time has not been provided by the UE is up to SMF implementation.
- The SMF corrects the Periodicity in the TSC Assistance Container using the cumulative rateRatio if the cumulative rateRatio was previously received from the UPF and sets the TSCAI Periodicity as the corrected value. Otherwise, the SMF sets the received Periodicity in the TSCAI without any correction.
- The SMF sets the TSCAI Flow Direction as the Flow Direction in the TSC Assistance Container.
- If Survival Time is provided in terms of maximum number of messages, the SMF converts maximum number of messages into time units by multiplying its value by the TSCAI Periodicity and sets the TSCAI Survival Time to the calculated value. If Survival Time is provided in time units, the SMF corrects the Survival Time using the cumulative rateRatio if the cumulative rateRatio was previously received from the UPF and sets the TSCAI Survival Time to the corrected value. Otherwise, SMF sets the TSCAI Survival Time without correction.
- If the TSC Assistance Container contains a BAT Window, the SMF sets and corrects the indicated earliest and latest possible arrival time of the first packet in the same way it is described for the correction of the Burst Arrival Time above.
- If the TSC Assistance Container contains a Capability for BAT adaptation, the SMF sets the Capability for BAT adaptation in the TSCAI. When the SMF determines that the TSCAI contains the Capability for BAT adaptation without a BAT, the SMF enables notification control for the QoS Flow in order to receive the BAT offset along with the "GFBR can no longer be guaranteed" notification described in clause 5.7.2.4.
- If the TSC Assistance Container contains a Periodicity Range, the SMF sets and corrects the Periodicity Range in the same way it is described for the correction of the Periodicity above.
If a dynamic value for the CN PDB is configured in NG-RAN or received from the SMF (as defined in clause 5.7.3.4), the NG-RAN shall adjust the Burst Arrival Time in the TSCAI for the downlink direction by adding the dynamic value for the CN PDB and deducting the static value for the CN PDB of the corresponding 5QI.
Depending on whether the Time Domain is provided in the TSC Assistance container, SMF may perform the following:
- the SMF provisions the UPF/NW-TT to report the clock drifting between 5G clock and the external GM clock for the (g)PTP time domain number that is configured to the NW-TT.
- the SMF provisions the UPF/NW-TT to report the clock drifting between 5G clock and the external GM clock for the given Time Domain number.
The SMF uses the N4 Association Setup or Update procedures as described in clause 4.4.3 of TS 23.502 [3] to provision the UPF to report the clock drifting.
If the SMF has clock drift information for a Time Domain and if the Time Domain matches with the Time Domain in the TSC Assistance Container (i.e. clock drift between 5G timing and AF supplied Time Domain determined based on UPF reporting), or Time Domain information is not provided in the TSC Assistance Container, then the SMF may adjust the TSCAI information so that it reflects the 5GS Clock as described in clause 5.27.2.1.
If the SMF does not have synchronization information for a requested Time Domain in the TSC Assistance Container, or the Time Domain in the TSC Assistance Container is set to a value = "5GS", then the TSCAI information will be used without adjustment.
In the case of drift between external GM clock and 5G clock, the UPF updates the offset to SMF using the N4 Report Procedure as defined in clause 4.4.3.4 of TS 23.502 [3]. If the cumulative rateRatio is available and in the case of change of cumulative rateRatio between external PTP time and 5G time, the UPF updates the cumulative rateRatio to SMF using the N4 Report Procedure as defined in clause 4.4.3.4 of TS 23.502 [3]. The SMF may then trigger a PDU Session Modification as defined in clause 4.3.3 of TS 23.502 [3] in order to update the TSCAI to the NG-RAN without requiring AN or N1 specific signalling exchange with the UE.
NOTE 4: In order to prevent frequent updates from the UPF, the UPF sends the offset or the cumulative rateRatio only when the difference between the current measurement and the previously reported measurement is larger than a threshold as described in clause 4.4.3.4 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.5 RAN feedback for Burst Arrival Time offset and adjusted Periodicity | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.5.1 Overview | If the NG-RAN receives a TSCAI containing a BAT Window or the Capability for BAT adaptation for a QoS Flow, the NG-RAN can determine a BAT offset in order to align the arrival of the traffic bursts with the next expected transmission opportunity over the air interface in each direction (i.e. DL or UL). The BAT offset can take a positive or a negative values.
If the NG-RAN receives a TSCAI containing a Periodicity Range for a QoS Flow, the NG-RAN can determine an adjusted Periodicity along with above specified BAT offset, in order to align the periodicity of the traffic bursts with the expected time interval between subsequent transmission opportunities over the air interface in each direction (i.e. DL or UL). If the TSCAI contained a value range, the adjusted Periodicity should be any value between the lower bound and upper bound. If the TSCAI contained a list of Periodicity value(s), the adjusted Periodicity should be one of these values.
NG-RAN may support the following feedback mechanisms:
- Proactive RAN feedback for adaptation of Burst Arrival Time and Periodicity: NG-RAN may provide a Burst Arrival Time offset and an adjusted Periodicity as part of QoS flow establishment or modification as illustrated in clause 5.27.2.5.2;
- Reactive RAN feedback for Burst Arrival Time adaptation: NG-RAN may provide a Burst Arrival Time offset after QoS flow establishment as illustrated in clause 5.27.2.5.3. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.5.2 Proactive RAN feedback for adaptation of Burst Arrival Time and Periodicity | If the NG-RAN receives a Burst Arrival Time and Burst Arrival Time Window in the TSCAI for a QoS Flow, the 5GS will perform the following actions:
- The NG-RAN can determine a BAT offset in order to align the expected arrival of the traffic bursts (as indicated in the BAT) with the time when the next transmission over the air interface in each direction (i.e. DL or UL) is expected. The BAT offset shall always be provided by NG-RAN and it shall be within the BAT Window. The BAT offset is calculated with reference to the BAT.
- If the BAT offset is provided from NG-RAN to the SMF in the response to the QoS Flow establishment or modification request, the SMF provides the BAT offset to the PCF and the PCF notifies the AF as described in clause 6.1.3.23a of TS 23.503 [45]. The SMF also updates the BAT value of the locally stored TSCAI based on the received BAT offset.
NOTE 1: SMF updates the locally stored TSCAI so that after a handover SMF provides the updated BAT (adjusted by the BAT offset) to the target NG-RAN node.
- The SMF may adjust the BAT offset received from NG-RAN based on the clock drifting report from UPF as specified in clause 4.4.3.4 of TS 23.502 [3].
NOTE 2: The feedback from RAN implies that the RAN accepts the BAT offset. If the AF requested BAT is acceptable for NG-RAN, the NG-RAN provides a BAT offset of zero.
- If the RAN also receives a Periodicity Range along with the Periodicity in the TSCAI for a QoS flow, the 5GS will further perform the following actions:
- The RAN may determine an adjusted periodicity in order to align the periodicity of the traffic bursts with the expected time interval between subsequent transmission opportunities over the air interface in each direction (i.e. DL or UL). If the RAN determines an adjusted periodicity, the RAN provides it together with a BAT offset mentioned above. The adjusted periodicity shall be within the Periodicity Range and the BAT offset is based on the adjusted periodicity.
- The adjusted periodicity is forwarded to the AF via the SMF and the PCF together with a BAT offset in the same way it is described above. The SMF also updates the periodicity value of the locally stored TSCAI based on the received adjusted periodicity.
NOTE 3: SMF updates the locally stored TSCAI so that after a handover SMF provides the adjusted periodicity to the target NG-RAN node.
- If interworking with a TSN network deployed in the transport network is supported, the SMF/CUC uses the adjusted periodicity (if provided) and BAT offset accepted by the RAN to adjust the related parameters in the Talker/Listener Group and the Talker/Listener Group is as described in Annex M, clause M.1. How the related parameters are adjusted is left to the implementation. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.2.5.3 Reactive RAN feedback for Burst Arrival Time adaptation | If the RAN receives the capability for BAT adaptation without a Burst Arrival Time in the TSCAI and notification control is enabled for this QoS Flow, the 5GS will perform the following actions:
- If NG-RAN determines that the PDB of the QoS flow cannot be fulfilled in DL and UL direction, then if supported, NG-RAN shall determine a BAT offset value which reduces the time between the arrival of the traffic bursts and the time of the next possible transmission over the air interface for DL and UL, respectively. NG-RAN shall not provide a BAT offset with the same value until the PDB of the QoS Flow can be fulfilled again.
NOTE: NG-RAN determines BAT offset value in reference to the current arrival time of the bursts experienced by RAN in DL and by UE in UL. Further details on BAT offset determination for DL and UL are defined in TS 38.331 [28].
- The BAT offset is provided from NG-RAN to the SMF when sending the notification towards the SMF that the "GFBR can no longer be guaranteed" described in clause 5.7.2.4. The SMF provides the BAT offset to the PCF and the PCF provides the BAT offset to the AF as part of notifying the AF as described in clause 6.1.3.23a of TS 23.503 [45] |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.3 Support for TSC QoS Flows | TSC QoS Flows use a Delay-critical GBR resource type and TSC Assistance Information. TSC QoS Flows may use standardized 5QIs, pre-configured 5QIs or dynamically assigned 5QI values (which requires signalling of QoS characteristics as part of the QoS profile) as specified in clause 5.7.2. For each instance of Periodicity, within each Period (defined by periodicity value), TSC QoS Flows are required to transmit only one burst of maximum size MDBV within the 5G-AN PDB. Known QoS Flow traffic characteristics provided in the TSCAI may be used to optimize scheduling in the 5GS.
The following is applicable for the QoS profile defined for TSC QoS Flows:
1. The TSC Burst Size may be used to set the MDBV as follows:
The maximum TSC Burst Size is considered as the largest amount of data within a time period that is equal to the value of 5G-AN PDB of the 5QI. The maximum value of TSC Burst Size should be mapped to a 5QI with MDBV that is equal or higher. When integration with IEEE TSN applies, this 5QI also shall have a PDB value that satisfies the bridge delay capabilities (see clause 5.27.5 for more details) reported for the corresponding traffic class. For TSC QoS Flows, the Maximum Burst Size of the aggregated TSC streams to be allocated to this QoS Flow can be similarly mapped to a 5QI with MDBV value that is equal or higher. If interworking with a TSN network deployed in the transport network is supported, the maximum value of TSC Burst Size should be mapped to a 5QI with MDBV that is equal.
2. The PDB is explicitly divided into 5G-AN PDB and CN PDB as described in clause 5.7.3.4. Separate delay budgets are necessary for calculation of expected packet transmit times on 5G System interfaces. For the TSC QoS Flow, the5G-AN PDB is set to value of 5QI PDB minus the CN PDB as described in clause 5.7.3.4. The CN PDB may be static value or dynamic value and is up to the implementation of 5GS bridge.
3. When integration with IEEE TSN applies, the Maximum Flow Bitrate calculated by the TSN AF as per Annex I.1 may be used to set GBR. In this case, MBR is set equal to GBR.
4. ARP is set to a pre-configured value.
5. 5QI value is derived using QoS mapping tables and TSN QoS information as described in clause 5.28.4 in the case of integration with IEEE TSN network, or using QoS Reference parameters and Requested PDB, Burst Size, Priority parameters as described in clause 4.15.6.6 or clause 4.15.6.6a of TS 23.502 [3] in the case of AF requested Time Sensitive Communication. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.4 Hold and Forward Buffering mechanism | DS-TT ports and NW-TT ports support a hold and forward mechanism to schedule traffic as defined in IEEE Std 802.1Q [98] if 5GS is to participate transparently as a bridge in a TSN network. That is, the hold and forward buffering mechanism in this release of the specification provides externally observable behaviour identical to scheduled traffic with up to eight queues (clause 8.6.8.4 in IEEE Std 802.1Q [98]) and with protected windows (Annex Q.2 in IEEE Std 802.1Q [98]). Frames are only transmitted from a given buffer according to the open time interval of the corresponding transmission gate; otherwise, frames are hold back (which corresponds to a closed transmission gate). The protected windows scheme implies that only a single transmission gate is open at any single time. Thus, the Hold and Forward buffering mechanism allows PDB based 5GS QoS to be used for TSC traffic.
For Ethernet frames that contain a VLAN tag, DS-TT and NW-TT determine the priority based on the PCP value contained in the VLAN tag. For Ethernet frames that do not contain a VLAN tag, DS-TT and NW-TT apply a priority value of 0.
To achieve externally observable behaviour according to the protected windows scheme, 5GS provides AdminControlList, AdminBaseTime, AdminCycleTime and TickGranularity as defined in IEEE Std 802.1Q [98] on a per Ethernet port basis to DS-TT and NW-TT for the hold and forward buffering mechanism as described in clause 5.28.3.
NOTE: The details of how Hold and Forward buffering mechanism is provided by the DS-TT and NW-TT is up to implementation. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.27.5 5G System Bridge delay | This clause applies if 5GS is integrated as a bridge into an IEEE TSN network.
In order for the 5G System to participate as a TSN bridge according to transmission gate schedules specified, the 5GS Bridge is required to provide Bridge Delays as defined in IEEE Std 802.1Q [98] for each port pair and traffic class of the 5GS bridge to an IEEE 802.1 TSN system. In order to determine 5GS Bridge Delays, the following components are needed:
1. UE-DS-TT Residence Time.
2. Per traffic class minimum and maximum delays between the UE and the UPF/NW-TT that terminates the N6 interface (including UPF and NW-TT residence times), independent of frame length that a given 5GS deployment supports. The per-traffic class delays between the UE and the UPF/NW-TT are pre-configured in the TSN AF (see clause 5.28.4).
The TSN AF calculates the 5GS independentDelayMin and independentDelayMax values for each port pair and for each traffic class using the above components. If the UE-DS-TT Residence Time has not been provided by the UE, then the TSN AF uses a locally configured minimum UE-DS-TT Residence Time for the calculation of independentDelayMin and a locally configured maximum UE-DS-TT Residence Time for the calculation of independentDelayMax.
The dependentDelayMin and dependentDelayMax for 5GS Bridge specify the time range for a single octet of an Ethernet frame to transfer from ingress to egress and include the time to receive and store each octet of the frame, which depends on the link speed of the ingress Port as per IEEE Std 802.1Q [98].
NOTE: Further details how TSN AF determines dependentDelayMin and dependentDelayMax are up to implementation.
Since residence times may vary among UEs and per traffic class delay between the UE and the UPF/NW-TT may vary among UPFs, the 5GS Bridge Delay is determined after the PDU Session Establishment for the corresponding UPF and the UE by the TSN AF. The TSN AF deduces the related port pair(s) from the port number of the DS-TT Ethernet port and port number of the NW-TT Ethernet port(s) of the same 5GS Bridge when the TSN AF receives the 5GS Bridge information for a newly established PDU Session and calculates the bridge delays per port pair. Additionally, TSN AF deduces the port pair(s) consisting of two DS-TT ports connecting to the same 5GS bridge and determines the 5GS bridge delay as sum of bridge delays related to PDU Sessions of two DS-TT ports. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28 Support of integration with TSN, Time Sensitive Communications, Time Synchronization and Deterministic Networking | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.0 General | Clause 5.28 defines the 5GS integration in TSN DN as a 5GS bridge.
In this scenario, 5GS is deployed in a TSN DN to provide wireless connectivity. From the perspective of the TSN DN, the 5GS is modelled as a Layer 2 Ethernet Bridge of the TSN DN.
In addition to supporting interoperation with TSN, 5GS also supports Time Sensitive Communication, Time Synchronization and integration with Deterministic Networking. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.1 5GS bridge management for TSN | 5GS acts as a Layer 2 Ethernet Bridge. When integrated with IEEE TSN network, 5GS functions acts as one or more TSN Bridges of the TSN network. The 5GS Bridge is composed of the ports on a single UPF (i.e. PSA) side, the user plane tunnel between the UE and UPF and the ports on the DS-TT side. For each 5GS Bridge of a TSN network, the port on NW-TT support the connectivity to the TSN network, the ports on DS-TT side are associated to the PDU Session providing connectivity to the TSN network.
The granularity of the 5GS TSN bridge is per UPF for each network instance or DNN/S-NSSAI. The bridge ID of the 5GS TSN bridge is bound to the UPF ID of the UPF as identified in TS 23.502 [3]. The TSN AF stores the binding relationship between a port on UE/DS-TT side and a PDU Session during reporting of 5GS TSN bridge information. The TSN AF also stores the information about ports on the UPF/NW-TT side. The UPF/NW-TT forwards traffic to the appropriate egress port based on the traffic forwarding information. From the TSN AF point of view, a 5GS TSN bridge has a single NW-TT entity within UPF and the NW-TT may have multiple ports that are used for traffic forwarding.
NOTE 1: How to realize single NW-TT entity within UPF is up to implementation.
NOTE 2: Ethernet PDU Session type in this release of the specification may be subject to the constraint that it supports a single N6 interface in a UPF associated with the N6 Network Instance.
There is only one PDU Session per DS-TT port for a given UPF. All PDU Sessions which connect to the same TSN network via a specific UPF are grouped into a single 5GS bridge. The capabilities of each port on UE/DS-TT side and UPF/NW-TT side are integrated as part of the configuration of the 5GS Bridge and are notified to TSN AF and delivered to CNC for TSN bridge registration and modification.
NOTE 3: It is assumed that all PDU Sessions which connect to the same TSN network via a specific UPF are handled by the same TSN AF.
Figure 5.28.1-1: Per UPF based 5GS bridge
NOTE 4: If a UE establishes multiple PDU Sessions terminating in different UPFs, then the UE is represented by multiple 5GS TSN bridges.
In order to support IEEE 802.1Q features related to TSN, including TSN scheduled traffic (clause 8.6.8.4 in IEEE Std 802.1Q [98]) over 5GS Bridge, the 5GS supports the following functions:
- Configure the bridge information in 5GS.
- Report the bridge information of 5GS Bridge to TSN network after PDU Session establishment.
- Receiving the configuration from TSN network as defined in clause 5.28.2.
- Map the configuration information obtained from TSN network into 5GS QoS information (e.g. 5QI, TSC Assistance Information) of a QoS Flow in corresponding PDU Session for efficient time-aware scheduling, as defined at clause 5.28.2.
The bridge information of 5GS Bridge is used by the TSN network to make appropriate management configuration for the 5GS Bridge. The bridge information of 5GS Bridge includes at least the following:
- Information for 5GS Bridge:
- Bridge ID
Bridge ID is to distinguish between bridge instances within 5GS. The Bridge ID can be derived from the unique bridge MAC address as described in IEEE Std 802.1Q [98], or set by implementation specific means ensuring that unique values are used within 5GS;
- Number of Ports;
- list of port numbers.
- Capabilities of 5GS Bridge as defined in IEEE Std 802.1Q [98]:
- 5GS Bridge delay per port pair per traffic class, including 5GS Bridge delay (dependent and independent of frame size and their maximum and minimum values: independentDelayMax, independentDelayMin, dependentDelayMax, dependentDelayMin), ingress port number, egress port number and traffic class.
- Propagation delay per port (txPropagationDelay), including transmission propagation delay, egress port number.
- VLAN Configuration Information.
NOTE 5: This Release of the specification does not support the modification of VLAN Configuration Information at the TSN AF.
- Topology related configuration of the 5GS Bridge as defined in IEEE Std 802.1AB [97]:
- LLDP Configuration Information.
- Chassis ID subtype and Chassis ID of the 5GS Bridge.
- Optional TLV types.
- LLDP Discovery Information for each discovered neighbor of each NW-TT port and DS-TT port.
- Traffic classes and their priorities per port as defined in IEEE Std 802.1Q [98].
- Stream Parameters as defined in clause 12.31.1 in IEEE Std 802.1Q [98], in order to support PSFP:
- MaxStreamFilterInstances: The maximum number of Stream Filter instances supported by the bridge;
- MaxStreamGateInstances: The maximum number of Stream Gate instances supported by the bridge;
- MaxFlowMeterInstances: The maximum number of Flow Meter instances supported by the bridge (optional);
- SupportedListMax: The maximum value supported by the bridge of the AdminControlListLength and OperControlListLength parameters.
The following parameters: independentDelayMax and independentDelayMin, how to calculate them is left to implementation and not defined in this specification.
DS-TT and NW-TT report txPropagationDelay to the TSN AF relative to the time base of the TSN GM clock (identified by the TSN time domain number received in PMIC). If the TSN AF has subscribed for notifications on txPropagationDelay and if the difference to the previously reported txPropagationDelay is larger than the txPropagationDelayDeltaThreshold received in PMIC, the corresponding DS-TT or NW-TT informs the TSN AF about the updated txPropagationDelay using PMIC signalling.
NOTE 6: Configuration of TSN time domain number and txPropagationDelayDeltaThreshold via PMIC is optional for NW-TT. NW-TT can instead be pre-configured with the threshold and the single time domain that is used by the CNC for bridge configuration and reporting.
Bridge ID of the 5GS Bridge, port number(s) of the Ethernet port(s) in NW-TT could be preconfigured on the UPF. The UPF is selected for a PDU Session serving TSC as described in clause 6.3.3.3.
This release of the specification requires that each DS-TT port is assigned with a globally unique MAC address.
NOTE 7: The MAC address of the DS-TT port must not be used in user data traffic; it is used for identification of the PDU Session and the associated bridge port within the 3GPP system.
When there are multiple network instances within a UPF, each network instance is considered logically separate. The network instance for the N6 interface (clause 5.6.12) may be indicated by the SMF to the UPF for a given PDU Session during PDU Session establishment. UPF allocates resources based on the Network Instance and S-NSSAI and it is supported according to TS 29.244 [65]. DNN/S-NSSAI may be indicated by the SMF together with the network instance to the UPF for a given PDU Session during PDU Session establishment procedure.
The TSN AF is responsible to receive the bridge information of 5GS Bridge from 5GS, as well as register or update this information to the CNC. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.2 5GS Bridge configuration for TSN | The configuration information of 5GS Bridge as defined in clause 8.6.8.4 of IEEE Std 802.1Q [98], includes the following:
- Bridge ID of 5GS Bridge.
- Configuration information of scheduled traffic on ports of DS-TT and NW-TT:
- Egress ports of 5GS Bridge, e.g. ports on DS-TT and NW-TT;
- Traffic classes and their priorities.
NOTE 1: In this Release of the specification, scheduled traffic (clause 8.6.8.4 in IEEE Std 802.1Q [98]) is only supported with protected windows, (see clause Q.2 in IEEE Std 802.1Q [98]), therefore, it is enough to support AdminControlList, AdminBaseTime, AdminCycleTime and TickGranularity for the configuration of the 5GS.
The configuration information of 5GS Bridge as defined in IEEE Std 802.1Q [98], includes the following:
- Chassis ID of 5GS Bridge;
- Traffic forwarding information as defined in clause 8.8.1 of IEEE Std 802.1Q [98]:
- Destination MAC address and VLAN ID of TSN stream;
- Port number in the Port MAP as defined in clause 8.8.1 of IEEE Std 802.1Q [98].
- Configuration information per stream according to clause 8.6.5.1 of IEEE Std 802.1Q [98] including:
- Stream filters.
- Stream gates.
NOTE 2: In order to support clause 8.6.5.2.1 of IEEE Std 802.1Q [98], it is required to support the Stream Identification function as specified by IEEE Std 802.1CB [83].
The SMF report the MAC address of the DS-TT port of the related PDU Session to TSN AF via PCF. The association between the DS-TT MAC address, 5GS Bridge ID and port number on DS-TT is maintained at TSN AF and further used to assist to bind the TSN traffic with the UE's PDU session.
Two models are supported to configure 5GS QoS for TSN traffic:
- Based on the assumption that PSFP information is always provided by CNC: In this case the QoS Flows are setup based on the PSFP information provided by CNC;
NOTE 3: PSFP information may be provided by CNC if TSN AF has declared PSFP support to CNC. TSN AF indicates the support for PSFP to CNC only if each DS-TT and NW-TT of the 5GS bridge has indicated support of PSFP.
- Without requiring PSFP information provided by the CNC.: In this case, pre-configured QoS Flows are used and configured e.g. during PDU session establishment as described in clause 5.28.4. Additional QoS Flows are setup as necessary based on the PSFP, if available, as described in this clause.
When PSFP information is available, TSN AF identifies the ingress and egress port for the TSN stream as described in Annex I and determines the DS-TT port MAC address(es) identifying the corresponding PDU session(s) carrying the TSN stream. Flow direction of a TSN stream is determined as follows: if the ingress port is a DS-TT port, then the Flow direction is UL; otherwise if the ingress port(s) is (are) NW-TT port, the Flow direction is DL. Flow direction is part of the TSCAI as defined in clause 5.27.2.
The TSN AF uses the stream filter instances of PSFP information to derive the service data flow for TSN streams. The TSN AF uses the Priority values in the stream filter instances in PSFP information (if available) as defined in clause 8.6.5.2.1 of IEEE Std 802.1Q [98], the 5GS bridge delay information (see clause 5.27.5) and may additionally use scheduled traffic information as defined in clause 8.6.8.4 of IEEE Std 802.1Q [98], to derive the TSN QoS information (i.e. priority and delay) for a given TSN stream or flow of aggregated TSN streams as specified in clause 5.28.4.
The TSN AF identifies the egress port(s) for the TSN stream using local configuration or static filtering entry that matches the TSN stream. If the TSN AF determines that the TSN stream is for UE-UE communication (i.e. ingress and egress ports are in DS-TTs), the TSN AF divides the stream into one uplink stream and one or more downlink streams and provides the streams on AF Session basis to the PCF(s). The SMF applies local switching as specified in clause 5.8.2.13 or clause 5.8.2.5.3 in order to enable UPF locally forward uplink stream from one PDU session as downlink stream in another PDU session.
When CNC configures the PSFP information to the TSN AF, TSN AF determines the TSC Assistance Container as described in clause 5.27.2. The TSN AF associates the TSN QoS information and TSC Assistance Container (if available) with the corresponding service data flow description and provides to the PCF and the SMF as defined in clause 6.1.3.23 of TS 23.503 [45].
NOTE 4: When the TSN stream priority information from PSFP is not available (priority value in stream filters is set to wild card), in certain configurations it can be possible to use the scheduled traffic information as defined in clause 8.6.8.4 of IEEE Std 802.1Q [98] to derive the Priority of the TSN stream. For example, when there is a single downlink stream for a given DS-TT port, it can be possible to determine the affected DS-TT port in the downlink and the associated TSN stream priority based on the scheduled traffic information of the affected egress port and to derive an estimated MDBV based on the gate open interval and the assumed ingress port bitrate.
If TSN AF provides PSFP and/or scheduled traffic information to DS-TT and NW-TT then DS-TT and NW-TT execute on this information relative to the time base of the TSN GM clock (identified by the TSN time domain number received in PMIC).
NOTE 5: Configuration of TSN time domain number via PMIC is optional for NW-TT. NW-TT can instead be pre-configured with the single time domain that is used by the CNC for bridge configuration and reporting. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.3 Port and user plane node management information exchange in 5GS | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.3.1 General | Port number for the PDU Session is assigned by the UPF during PDU session establishment. The port number for a PDU Session shall be reported to the SMF from the UPF and further stored at the SMF. The SMF provides the port number via PCF to the TSN AF or TSCTSF. TSN AF or TSCTSF maintains an association between the port number for the PDU Session and the DS-TT port MAC address (with Ethernet type PDU session) or IP address (applicable for TSCTSF only, with IP type PDU Session) of the UE. If a PDU session for which SMF has reported a port number to TSN AF or TSCTSF is released, then SMF informs TSN AF or TSCTSF accordingly. The port number for the PDU Session corresponds to the device side port of the 5GS bridge/router. When the device supports the DS-TT functionality, the port number represents the DS-TT port number corresponding to the given PDU Session.
NOTE 1: Port number can refer either to Ethernet port or PTP port. In Ethernet type PDU Sessions, it is assumed that the PTP port number is the same as the associated Ethernet port number.
When the DS-TT or the NW-TT functions are used, the 5GS shall support transfer of standardized and deployment-specific port management information transparently between TSN AF or TSCTSF and DS-TT or NW-TT, respectively inside a Port Management Information Container. NW-TT may support one or more ports. In this case, each port uses separate Port Management Information Container. 5GS shall also support transfer of standardized and deployment-specific user plane node management information transparently between TSN AF or TSCTSF and NW-TT, respectively inside a User Plane Node Management Information Container. Clause K.1 lists standardized port management information and user plane node management information, respectively.
If TSN AF is deployed, i.e. if 5GS is integrated with an IEEE TSN network, the port and user plane node management information is exchanged between CNC and TSN AF. The port management information is related to ports located in DS-TT or NW-TT. The user plane node management information container is related to 5GS bridge management.
If TSN AF is not deployed, the port and user plane node management information is exchanged between TSCTSF and DS-TT/NW-TT.
NOTE 2: The time synchronization parameters used in Port Management Information Container and User Plane Node Management Information Container are from IEEE Std 1588 [126], Edition 2019 and from IEEE Std 802.1AS [104]. Since the IEEE time synchronization data sets are not exposed, care needs to be taken when interoperating with devices supporting Edition 2008, IEEE Std 1588-2008 [107] (which can be the case when operating under the SMPTE profile, ST 2059-2:2015 [127]) and using a common management.
Exchange of port and user plane node management information between TSN AF or TSCTSF and NW-TT or between TSN AF or TSCTSF and DS-TT allows TSN AF or TSCTSF to:
1) retrieve port management information for a DS-TT or NW-TT port or user plane node management information;
2) send port management information for a DS-TT or NW-TT port or user plane node management information;
3) subscribe to and receive notifications if specific port management information for a DS-TT or NW-TT port changes or user plane node management information changes.
4) delete selected entries in the following data structures:
- "DS-TT port neighbour discovery configuration for DS-TT port" in UMIC using the DS-TT port number to reference the selected entry.
- "Stream Filter Instance Table" in PMIC using the Stream Filter Instance ID to reference the selected entry.
- "Stream Gate Instance Table" in PMIC using the Stream Gate Instance ID to reference the selected entry.
- "Static Filtering Entries table" in UMIC using the (MAC address, VLAN ID) pair to reference the selected entry.
5) delete PTP Instances in a DS-TT port or NW-TT port using the PTP Instance ID to reference the selected entry as described in clause K.2.2.1.
Exchange of port management information between TSN AF or TSCTSF and NW-TT or DS-TT is initiated by DS-TT or NW-TT to:
- notify TSN AF or TSCTSF if port management information has changed that TSN AF or TSCTSF has subscribed for.
Exchange of user plane node management information between TSN AF or TSCTSF and NW-TT is initiated by NW-TT to:
- notify TSN AF or TSCTSF if user plane node management information has changed that TSN AF or TSCTSF has subscribed for.
- notify TSCTSF if time synchronization status information of UPF has changed that the TSCTSF has subscribed for.
Exchange of port management information is initiated by DS-TT to:
- provide port management capabilities, i.e. provide information indicating which standardized and deployment-specific port management information is supported by DS-TT.
TSN AF or TSCTSF indicates inside the Port Management Information Container or user plane node Management Information Container whether it wants to retrieve or send port or user plane node management information or intends to (un-)subscribe for notifications. If the TSN AF or TSCTSF has requested to receive notification of TSC management information and both SMF and UPF support direct reporting, the UPF may directly report TSC management information to the TSN AF or TSCTSF using Nupf_EventExposure_Notify. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.3.2 Transfer of port or user plane node management information | Port management information is transferred transparently via 5GS between TSN AF or TSCTSF and DS-TT or NW-TT, respectively, inside a Port Management Information Container (PMIC). User plane node management information is transferred transparently via 5GS between TSN AF or TSCTSF and NW-TT inside a user plane node Management Information Container (UMIC). The transfer of port or user plane node management information is as follows:
- To convey port management information from DS-TT or NW-TT to TSN AF or TSCTSF:
- DS-TT provides a PMIC and the DS-TT port MAC address (if available) to the UE, which includes the PMIC as an optional Information Element of an N1 SM container and triggers the UE requested PDU Session Establishment procedure or PDU Session Modification procedure to forward the PMIC to the SMF. SMF forwards the PMIC and the port number of the related DS-TT port to TSN AF or TSCTSF as described in clauses 4.3.2.2 and 4.3.3.2 of TS 23.502 [3];
- NW-TT provides PMIC(s) and/or UMIC to the UPF, which may trigger the N4 Session Level Reporting Procedure to forward the PMIC(s) and/or UMIC to SMF. UPF selects an N4 session corresponding to any of the N4 sessions for this NW-TT. SMF in turn forwards the PMIC(s) and the port number(s) of the related NW-TT port(s), or the UMIC, to TSN AF or TSCTSF as described in clause 4.16.5.1 of TS 23.502 [3].
- NW-TT may provide PMIC(s) and/or UMIC to the UPF, which may trigger UPF Event Exposure Notification to forward the PMIC(s) and/or UMIC to TSN AF or TSCTSF. UPF directly reports TSC management information event via Nupf_EventExposure_Notify service operation as described in clause 5.2.26.2 of TS 23.502 [3].
NOTE 1: There has to be at least one established PDU session for DS-TT port before the UPF can report PMIC/UMIC information towards the TSN AF or TSCTSF.
- To convey port management information from TSN AF or TSCTSF to DS-TT:
- TSN AF or TSCTSF provides a PMIC, DS-TT port MAC address or UE IP address (applicable for TSCTSF only) reported for a PDU Session (i.e. MAC address of the DS-TT port or IP address related to the PDU session) and the port number of the DS-TT port to manage to the PCF by using the AF Session level Procedure, which forwards the information to SMF based on the MAC or IP address using the PCF initiated SM Policy Association Modification procedure as described in clause 4.16.5.2 of TS 23.502 [3]. SMF determines that the port number relates to a DS-TT port and based on this forwards the PMIC to DS-TT using the network requested PDU Session Modification procedure as described in clause 4.3.3.2 of TS 23.502 [3].
- To convey port or user plane node management information from TSN AF or TSCTSF to NW-TT:
- TSN AF or TSCTSF selects a PCF-AF session corresponding to any of the DS-TT MAC or IP addresses (applicable for TSCTSF only) for the related PDU sessions of this bridge or router and provides a PMIC(s) and the related NW-TT port number(s) and/or UMIC to the PCF. The PCF uses the PCF initiated SM Policy Association Modification procedure to forward the information received from TSN AF or TSCTSF to SMF as described in clause 4.16.5.2 of TS 23.502 [3]. SMF determines that the included information needs to be delivered to the NW-TT either by determining that the port number(s) relate(s) to a NW-TT port(s) or based on the presence of UMIC and forwards the container(s) and/or related port number(s) to NW-TT using the N4 Session Modification procedure described in clause 4.4.1.3 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.3.3 VLAN Configuration Information for TSN | The CNC obtains the 5GS bridge VLAN configuration from TSN AF according to clause 12.10.1.1 of IEEE Std 802.1Q [98]. The TSN AF and UPF/NW-TT are pre-configured with same 5GS bridge VLAN configuration.
NOTE: In this Release, the VLAN Configuration Information are pre-configured at the TSN AF and the NW-TT and is not exchanged between the TSN AF and the UPF/NW-TT. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.4 QoS mapping tables for TSN | The mapping tables between the traffic class and 5GS QoS Profile is provisioned and further used to find suitable 5GS QoS profile to transfer TSN traffic over the PDU Session. QoS mapping procedures are performed in two phases: (1) QoS capability report phase as described in clause 5.28.1 and (2) QoS configuration phase as in clause 5.28.2
(1) The TSN AF shall be pre-configured (e.g. via OAM) with a mapping table. The mapping table contains TSN traffic classes, pre-configured bridge delays (i.e. the preconfigured delay between UE and UPF/NW-TT) and priority levels. Once the PDU session has been setup and after retrieving the information related to UE-DS-TT residence time, the TSN AF deduces the port pair(s) in the 5GS bridge and determines the bridge delay per port pair per traffic class based on the pre-configured bridge delay and the UE-DS-TT residence time as described in clause 5.27.5. The TSN AF updates bridge delays per port pair and traffic class and reports the bridge delays and other relevant TSN information such as the Traffic Class Table (clause 12.6.3 in IEEE Std 802.1Q [98]) for every port, according to the IEEE Std 802.1Q [98] to the CNC.
(2) CNC may distribute PSFP information and transmission gate scheduling parameters to 5GS Bridge via TSN AF, which can be mapped to TSN QoS requirements by the TSN AF.
The PCF mapping table provides a mapping from TSN QoS information (see clauses 6.2.1.2 and 6.1.3.23 of TS 23.503 [45]) to 5GS QoS profile. Based on trigger from TSN AF, the PCF may trigger PDU session modification procedure to establish a new 5G QoS Flow or use the pre-configured 5QI for 5G QoS Flow for the requested traffic class according to the selected QoS policies and the TSN AF traffic requirements.
Figure 5.28.4-1 illustrates the functional distribution of the mapping tables.
Figure 5.28.4-1: QoS Mapping Function distribution between PCF and TSN AF
The minimum set of TSN QoS-related parameters that are relevant for mapping the TSN QoS requirements are used by the TSN AF: traffic classes and their priorities per port, TSC Burst Size of TSN streams, 5GS bridge delays per port pair and traffic class (independentDelayMax, independentDelayMin, dependentDelayMax, dependentDelayMin), propagation delay per port (txPropagationDelay) and UE-DS-TT residence time.
Once the CNC retrieves the necessary information, it proceeds to calculate scheduling and paths. The configuration information is then set in the bridge as described in clauses 5.28.2 and 5.28.3. The most relevant information received is the PSFP information and the schedule of transmission gates for every traffic class and port of the bridge. At this point, it is possible to retrieve the TSN QoS requirements by identifying the traffic class of the TSN stream. The traffic class to TSN QoS and delay requirement (excluding the UE-DS-TT residence time) mapping can be performed using the QoS mapping table in the TSN AF as specified in TS 23.503 [45]. Subsequently in the PCF, the 5G QoS Flow can be configured by selecting a 5QI as specified in TS 23.503 [45]. This feedback approach uses the reported information to the CNC and the feedback of the configuration information coming from the CNC to perform the mapping and configuration in the 5GS.
If the Maximum Burst Size of the aggregated TSC streams in the traffic class is provided by CNC via TSN AF to PCF, PCF can derive the required MDBV taking the Maximum Burst Size as input. If the default MDBV associated with a standardized 5QI or a pre-configured 5QI in the QoS mapping table cannot satisfy the aggregated TSC Burst Size, the PCF provides the derived MDBV in the PCC rule and then the SMF performs QoS Flow binding as specified in clause 6.1.3.2.4 of TS 23.503 [45].
Maximum Flow Bit Rate is calculated over StreamGateAdminCycleTime as described in Annex I and provided by the TSN AF to the PCF. The PCF sets the GBR and MBR values to the Maximum Flow Bitrate value.
The Maximum Flow Bit Rate is adjusted according to Averaging Window associated with a pre-configured 5QI in the QoS mapping table or another selected 5QI (as specified in TS 23.503 [45]) to obtain GBR of the 5GS QoS profile. GBR is then used by SMF to calculate the GFBR per QoS Flow. QoS mapping table in the PCF between TSN parameters and 5GS parameters should match the delay, aggregated TSC burst size and priority, while preserving the priorities in the 5GS. An operator enabling TSN services via 5GS can choose up to eight traffic classes to be mapped to 5GS QoS profiles.
Once the 5QIs to be used for TSN streams are identified by the PCF as specified in TS 23.503 [45], then it is possible to enumerate as many bridge port traffic classes as the number of selected 5QIs.
When PSFP information is not available to the TSN AF for a given TSN stream (e.g. because of lack of PSFP support in the DS-TTs or the NW-TTs, or exceeding the number of supported table entries for PSFP functions, or because CNC does not provide PSFP information), the 5GS can support the TSN streams using pre-configured mapping from stream priority (i.e. PCP as defined in IEEE Std 802.1Q [98]) to QoS Flows. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.5 Support of integration with IETF Deterministic Networking | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.5.1 General | 5GS acts as a DetNet Router according to the architecture defined in clause 4.4.8.4. When integrated with an IETF Deterministic Network, 5GS acts as one or more routers. A 5GS router is composed of the ports on a single UPF (i.e. PSA) network side, the user plane tunnel between the UE and UPF and the ports on the device side. For each 5GS router of a deterministic network, the ports on the network side and the ports on device side that are associated to the PDU Sessions support connectivity to the deterministic network.
The granularity of the 5GS DetNet node is per UPF for each network instance or DNN/S-NSSAI. The TSCTSF stores the binding relationship between a device side port and a PDU Session identified by the UE address. The TSCTSF also stores information about ports on the UPF/NW-TT side.
The integration with IETF Deterministic Networking assumes the following.
- The existing 3GPP routing mechanisms are re-used for DetNet.
- The existing multicast capabilities can be re-used for DetNet communications.
- The 5GS integration to IETF DetNet is based on DetNet for IP; DetNet for MPLS is not supported.
- IPbased DetNet traffic is carried in IPtype PDU Sessions.
- 5GS functions realize the DetNet forwarding sub-layer. For the IP case, according to clause 1 of IETF RFC 8939 [157], no service sub-layer function needs to be defined. The 5GS DetNet Router acts as a DetNet transit node as defined in IETF RFC 8655 [150].
The interface between the TSCTSF and the DetNet controller uses protocols defined in IETF. The DetNet configuration is carried in the YANG model [154] over Netconf [155] or Restconf [156]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.5.2 5GS DetNet node reporting | The TSCTSF may provide exposure information to the DetNet controller using information collected from the 5GS entities. The exposure information can be used by the DetNet controller to build up the network topology information. The exposure may be based on IETF RFC 8343 [151] and IETF RFC 8344 [152].
The TSCTSF may collect the information from the UPF/NW-TT via parameters in PMIC as defined in clause 5.28.3.1. For the device side ports, the TSCTSF collects information using parameters provided from SMF to TSCTSF via PCF as described in clause 6.1.3.23b of TS 23.503 [45].
When the MTU size for IPv4 or IPv6 is not provided to TSCTSF for a port, the TSCTSF may use a pre-configured default value for IPv4 or IPv6.
In the case of network side ports, the TSCTSF may collect information on the type of the interface (defined in IETF RFC 8343 [151], with values defined in IETF RFC 7224 [153]) associated with the port. In the case of device side ports, which correspond to the PDU Sessions that are reported to the TSCTSF, the default value of "3GPP WWAN" (wwanPP) for the interface type is assumed. The TSCTSF can differentiate network side ports as they are reported from the NW-TT within UMIC/PMIC, while device side ports correspond to the PDU Sessions, reported to the TSCTSF in the associated AF sessions.
For device side ports also information on IP addresses or IP prefixes not directly assigned to the port but reachable via the port may be provided. On the device side ports, these are related to Framed Routes, i.e. a range of IPv4 addresses or IPv6 prefixes reachable over a single PDU Session, as defined in clause 5.6.14, or prefixes delegated by IPv6 prefix delegation as defined in clause 5.8.2.2. This additional information helps both the TSCTSF and the DetNet controller to map flows to the correct UE address as described in clause 5.28.5.3. For the network side ports, the TSCTSF may also collect information on the link layer address and neighbor IP nodes.
The ports are identified by the port number within the 3GPP system. The port number may also be used to generate interface identifiers towards the DetNet controller that are unique within the 5GS node.
NOTE 1: One possibility to generate unique interface identifiers towards the DetNet controller is to use the port number as the if-Index as defined in IETF RFC 8343 [151]. Based on the if-Index, an interface name is generated, e.g. by using the if-Index as a string, possibly adding a substring prefix or postfix based on configuration. The if-Index and the name of the interface contain essentially the same information, but both can be provided, since the name is used as the key in the YANG model, while if-Index is usually considered as the basis for interface management of IP nodes.
The TSCTSF may use the user-plane node ID provided by the UPF to generate an identifier of the 5GS node that is provided to the DetNet controller.
NOTE 2: The 5GS node identification can be realized by providing an identifier of the 5GS node to the DetNet controller, or the TSCTSF can use different termination points (addresses) for the signalling between the DetNet controller and the TSCTSF.
For network side ports, the information is transferred in PMIC between the NW-TT and the TSCTSF. For device side ports, the information is transferred without relying on PMIC, using parameters from the SMF via the PCF to the TSCTSF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.28.5.3 DetNet node configuration mapping in 5GS | The TSCTSF maps the parameters in the DetNet YANG configuration to 5GS parameters as defined in clause 6.1.3.23b of TS 23.503 [45].
The TSCTSF determines the UE address to bind the DetNet configuration as follows:
- When available, the TSCTSF uses the identity of the incoming and outgoing interface to determine the affected UE address and whether the flow is uplink or downlink or UE-to-UE.
- If there is no incoming interface for UL traffic, the TSCTSF may determine the UE address based on the source IP address of the UL traffic in the DetNet configuration, or using local configuration to map the DetNet flow information to the UE address. If there is no incoming interface for traffic with an outgoing interface on the device side, the TSCTSF may determine whether the flow is UE-to-UE based on the source IP address of the traffic in the DetNet configuration, or using local configuration.
NOTE 1: The incoming interface is optional in the DetNet YANG configuration. It is assumed that any IP prefix on the device side is reachable via, at most, a single device side interface. Thus if the flow source IP address is available and belongs to a prefix associated with a device side interface, that interface can be uniquely determined as the incoming interface for the flow.
NOTE 2: If there is no incoming interface for the UL traffic or no incoming interface for traffic with outgoing interface on the device side, the details on how the TSCTSF uses local configuration are not specified.
- When the information on IP addresses or IP prefixes not directly assigned to the port but reachable via the port is available as described in clause 5.28.5.2, the TSCTSF also takes such info into account.
- If the flow is UE-to-UE, two PDU Sessions will be affected for the flow and the TSCTSF breaks up the requirements to individual requirements for the PDU Sessions.
The TSCTSF provides a response to the DetNet controller regarding the success of the configuration setup. When both the TSCTSF and the DetNet controller support 3GPP extensions to the IETF RFC 9633 [154], the TSCTSF may provide 5GS specific status code information on the result of the configuration to the DetNet controller.
NOTE 3: The 3GPP extension to the IETF RFC 9633 [154] is defined in 3GPP as a YANG model which imports IETF RFC 9633 [154] and adds the 3GPP specific parameters. The 3GPP defined YANG model uses the 3GPP namespace as defined in IETF RFC 5279 [158].
If the status of the flow changes later on for any reason, the TSCTSF notifies the DetNet controller. Upon release of a PDU Session that is part of the existing DetNet configuration, the PCF notifies the TSCTSF of the PDU Session release and TSCTSF notifies the DetNet controller on the status of the flow.
The 5GS routing is not modified by the configuration received from the DetNet controller. Still the TSCTSF may verify whether the explicit routing information provided by the DetNet controller is in line with the 5GS mapping of IP addresses and prefixes to PDU sessions. The verification may be based on whether the source or destination IP address in the DetNet flow on the given port corresponds to the IP address or prefix associated with the given PDU Session. Based on operator configuration, the TSCTSF may use other criteria (not routing related) to determine whether to accept or reject a given DetNet configuration.
5GS DetNet Node can forward via its device side interface IP packets destined not only to the UE's IP address or prefix but also to a range of IPv4 addresses or IPv6 IP prefixes according to one or more Framed Routes or prefixes delegated to the UE by IPv6 prefix delegation. To facilitate this, the additional IP addresses used for framed routes and IPv6 prefix delegation are exposed by the SMF to the TSCTSF via the PCF and the TSCTSF may expose them to the DetNet controller, as defined in clause 5.28.5.2.
5.28a Support for TSN enabled Transport Network
5.28a.1 General
When the 5GS supports interworking with IEEE TSN deployed in the transport network, the CUC that is collocated with SMF interworks with the CNC in the transport network (TN CNC) as specified in clause 46.2 of IEEE Std 802.1Q [98]. The SMF/CUC provides the stream requirements on QoS Flow basis (i.e. translated Talker group and Listener group information) via the User/Network-Interface (UNI) to the TN CNC. The TN CNC uses the stream requirements as input to configure respective path(s) and schedules in TN. Based on the results, the TN CNC provides a Status group that contains the end station communication-configuration back to the SMF/CUC.
When interworking with TSN deployed in the transport network is applied, the dynamic value for the CN PDB of a Delay-critical GBR 5QI shall be considered as described in clause 5.7.3.4. When the SMF setups a new QoS Flow, the SMF signals TSCAI for the QoS Flow to NG-RAN on QoS Flow basis as described in clause 5.27.2.
Upon receiving the TSCAI for a QoS Flow from the SMF, if the TSCAI includes a BAT in UL direction and the dynamic value for the CN PDB is configured in the NG-RAN (as described in clause 5.7.3.4), the NG-RAN shall provide the 5G-AN PDB in the response to the QoS Flow request. The SMF/CUC uses 5G-AN-PDB to generate EarliestTransmitOffset as described in Annex M, clause M.1.
The details of providing End Station related information to generate the stream requirements for the QoS Flow by the SMF/CUC are described in Annex M, clause M.1.
If the NG-RAN and UPF support the TSN Talker and Listener functionality (i.e. implement the AN-TL and CN-TL, respectively), the SMF/CUC can communicate with the AN-TL and CN-TL via TL-Container. The TL-Container conveys the data sets defined in IEEE Std 802.1Qdj [146] between the SMF/CUC and AN-TL and CN-TL.
The AN-TL and CN-TL enable the following functions:
a) hold and buffer functionality in a case when the TSCAI contains a BAT in UL and/or DL direction.
b) support of stream transformation functionality with respective information exchange with SMF/CUC.
c) for SMF/CUC to retrieve the InterfaceCapabilities and/or EndStationInterfaces from the AN-TL or CN-TL.
d) topology information exchange functionality via LLDP in the TN as described in clause 5.28a.3.
NOTE 1: How to realize AN-TL in the base station and CN-TL in UPF is up to implementation.
NOTE 2: In this Release of the specification, it is assumed that connected mode mobility is not used in deployments with a TSN enabled TN.
5.28a.2 Transfer of TL-Container between SMF/CUC and AN-TL and CN-TL
If NG-RAN and UPF support AN-TL and CN-TL, the SMF/CUC may use the TL-Container to send a:
1) get-request.
2) set-request: submits the following information elements to the AN-TL or CN-TL:
- InterfaceConfiguration as described in Annex M, clause M.1 (one InterfaceConfiguration is associated with each QFI in the N3 tunnel)
- Interface ID Group.
- TN Stream Identification Information for DataFrameSpecification.
- TN Stream Identification Information for mask-and-match.
- Interval (only provided together with TimeAwareOffset).
- MaxFrameSize (only provided together with TimeAwareOffset).
The AN-TL or CN-TL may use the TL-Container to send a:
1) get-response: indicates the following elements of the Talker or Listener group from the AN-TL or CN-TL:
- EndStationInterfaces: list of InterfaceIDs.
- InterfaceCapabilities.
- Buffer capability: maximum possible buffer duration for a packet of a stream with the maximum size of an Ethernet packet (1522 Bytes) that is supported by the AN-TL / CN-TL when acting as a Talker.
2) set-response: reports the processing results for the corresponding set-request to the SMF/CUC.
Details on the TL-Container information are provided in Table M.2-1 of clause M.2.
The SMF/CUC may request the NG-RAN/UPF to report AN-TL or CN-TL information by including a TL-Container with a get-request to the AN-TL or CN-TL, respectively. The get-request is sent to AN-TL in the N2 SM information and to CN-TL in the N4 Session Establishment as described in clause 4.3.2.2 of TS 23.502 [3].
If the NG-RAN/UPF supports AN-TL/CN-TL, the NG-RAN/AN-TL and UPF/CN-TL responds with a TL-Container including the elements defined for the get-response.
The SMF/CUC may submit TL-Container including a set-request the elements defined for the set-request to NG-RAN/AN-TL and UPF/CN-TL. The set-request is sent to AN-TL in the N2 SM information and to CN-TL in the N4 Session Modification request as described in clause 4.3.3.2 of TS 23.502 [3]. The SMF/CUC shall initiate to the CN-TL/AN-TL the deletion of TN stream configurations as described in 4.3.4.2 of TS 23.502 [3].
The InterfaceConfiguration is associated with the corresponding QFI in the N3 tunnel in the NG-RAN or UPF, respectively. The AN-TL/CN-TL uses the provided configuration for the traffic in the QoS Flow of the given QFI as described in Annex M.
5.28a.3 Topology Information for TSN TN
NG-RAN and UPF may support u-plane LLDP functionality to provide topology information to the TN. When LLDP is supported, AN-TL and CN-TL shall perform the LLDP functionality at the u-plane without the need to interact with the c-plane. Further there is no need for 5GS interaction with TN CNC directly. This is achieved with following measures:
- AN-TL and CN-TL implement the Transmit Only operation mode as defined in clause 9.1 of IEEE Std 802.1AB [97].
- The TSN End Station is pre-configured with parameter set for Transmit Only operating mode as defined in clause 9.2 of IEEE Std 802.1AB [97].
- The System Capabilities TLV may also be set to Station Only as defined in clause 8.5.8 of IEEE Std 802.1AB [97]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.29 Support for 5G LAN-type service | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.29.1 General | The service requirements for 5G LAN-type service are specified in TS 22.261 [2].
A 5G Virtual Network (VN) group consists of a set of UEs using private communication for 5G LAN-type services. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.29.2 5G VN group management | 5G System supports management of 5G VN Group identification and membership (i.e. definition of 5G VN group identifiers and membership) and 5G VN Group data (i.e. definition of 5G VN group data). The 5G VN Group management can be configured by a network administrator or can be managed dynamically by AF.
A 5G VN group is characterized by the following:
- 5G VN group identities: External Group ID and Internal Group ID are used to identify the 5G VN group.
- 5G VN group membership: The 5G VN group members are uniquely identified by GPSI. The group as described in clause 5.2.3.3.1 of TS 23.502 [3] is applicable to 5G LAN-type services.
- 5G VN group data. The 5G VN group data may include the following parameters: PDU session type, DNN, S-NSSAI and Application descriptor, the indication that the 5G VN group is associated with 5G VN group communication, Information related with secondary authentication / authorization (e.g. to enable IP address assignment by the DN-AAA), Maximum Group Data Rate, User Plane Security Policy.
The Information related with secondary authentication / authorization corresponds to the procedures described in clause 5.6.6; it allows e.g. the AF to provide DN-AAA server addressing information and possibly to request the SMF to get the UE IP address from the DN-AAA server.
NOTE 1: See TS 33.501 [29] for further description on User Plane Security Policy for 5G VN groups.
In order to support dynamic management of 5G VN Group identification and membership, the NEF exposes a set of services to manage (e.g. add/delete/modify) 5G VN groups and 5G VN members. The NEF also exposes services to dynamically manage 5G VN group data.
An AF can request provisioning of traffic characteristics, QoS parameters and monitoring of QoS parameters for a 5G VN group as described in clause 6.1.3.28 of TS 23.503 [45].
A 5G VN group is identified by the AF using External Group ID. The NEF provides the External Group ID to UDM. The UDM maps the External Group ID to Internal Group ID. For a newly created 5G VN Group, an Internal Group ID is determined by the UDM based on implementation specific means.
NOTE 2: The Internal Group ID determined by UDM has to comply with the format defined in TS 23.003 [19].
The NEF can retrieve the Internal Group ID from UDM via Nudm_SDM_Get service operation (External Group ID, Group Identifier translation).
An External Group ID for a 5G VN group corresponds to a unique set of 5G VN group data parameters.
The 5G VN group configuration is either provided by OA&M or provided by an AF to the NEF.
When configuration is provided by an AF, the procedures described in clause 4.15.6.2 of TS 23.502 [3] apply for storing the 5G VN group identifiers, group membership information and group data in the UDR, as follows:
- The NEF provides the External Group ID, 5G VN group membership information and 5G VN group data to the UDM.
- The UDM updates the Internal Group ID-list of the corresponding UE's subscription data in UDR, if needed.
- The UDM updates the Group Identifier translation in the Group Subscription data with the Internal Group ID, External Group ID and list of group members, if needed.
- The UDM stores/updates the 5G VN group data (PDU session type, DNN and S-NSSAI, Application descriptor, the indication that the 5G VN group is associated with 5G VN group communication, Information related with secondary authentication / authorization, Maximum Group Data Rate, User Plane Security Policy) in UDR.
The DNN, S-NSSAI, User Plane Security Policy provided within 5G VN group data cannot be modified after the initial provisioning, i.e. the Nudm_ParameterProvision_Update and Nudr_DM_Update service operations do not apply for DNN, S-NSSAI, User Plane Security Policy within 5G VN group data.
NOTE 3: It is assumed that all members of a 5G VN group belong to the same UDM Group ID. The NEF can select a UDM instance supporting the UDM Group ID of any of the member GPSIs of the 5G VN group.
NOTE 4: Shared data mechanisms as defined in TS 29.503 [122] can be used to support large 5G VN groups.
An AF may also configure and update the service area, QoS for the 5G VN group as described in clause 5.20b as well as other parameters (e.g. Expected UE Behaviour parameters, Network Configuration parameters, ECS Address Configuration Information, etc.) for a 5G VN group as described in clause 4.15.6 of TS 23.502 [3].
If a UE is member of a 5G VN Group, UDM retrieves UE subscription data and corresponding 5G VN group data from UDR and provides the AMF and SMF with UE subscription data with 5G VN group data included. If the 5G VN group data contains the indication that the 5G VN group is associated with 5G VN group communication, the SMF may apply the 5G VN group communication as defined in clauses 5.29.3 and 5.29.4 for the PDU Sessions accessing to the 5G VN group.
The PCF generates URSP rules based on 5G VN group data. The PCF retrieves 5G VN group data from UDR. The PCF(s) that have subscribed to modifications of 5G VN group data receive(s) a Nudr_DM_Notify notification of 5G VN group data change from the UDR as defined in TS 29.505 [145]. The PCF receives from the AMF at the UE Policy association establishment the Internal Group ID(s) corresponding to a UE, so that PCF identifies the 5G VN group data that needs to be used to generate URSP rules to the UE. If the PCF is made aware of a change of UE Internal Group Identifier(s) as defined in TS 29.525 [144] or change of 5G VN group membership as defined in TS 29.505 [145], or both, the PCF then may update the URSP rules for the impacted 5G VN group members.
NOTE 5: The proper way to obtain the 5G VN group membership changes of a specific UE, e.g. if the UE is added to a new 5G VN group, is via the notification of change of UE Internal Group Identifier(s) from the AMF as specified in TS 29.525 [144]. The subscription in the UDR is for being notified about changes in the 5G VN group data and in the 5G VN group membership of a specific 5G VN group.
If the PCF receives the Maximum Group Data Rate as part of the 5G VN group data, it performs the group related policy control as described in clauses 6.1.5 and 6.2.1.11 of TS 23.503 [45].
An AF may update the UE Identities of the 5G VN group at any time after the initial provisioning.
An AF may subscribe to notification of the group status changes for the 5G VN group as described in clause 5.20.
In this Release of the specification, the home network of the 5G VN group members is same.
In this Release of the specification, only a 1:1 mapping between (DNN, S-NSSAI) combination and 5G VN group is supported.
The PCF delivers 5G VN group configuration information (DNN, S-NSSAI, PDU session type) to the UE for each GPSI that belongs to a 5G VN group. The 5G VN group configuration information is delivered in the URSP from the PCF to the UE using the UE Configuration Update procedure for transparent UE Policy delivery as described in clause 4.2.4.3 of TS 23.502 [3] and clause 6.1.2.2 of TS 23.503 [45]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.29.3 PDU Session management | Session management as defined for 5GS in clause 5.6 is applicable to 5G-VN-type services with the following clarification and enhancement:
- A UE gets access to 5G LAN-type services via a PDU Session of IP PDU Session type or Ethernet PDU Session type.
- A PDU Session provides access to one and only one 5G VN group. The PDU Sessions accessing to a certain 5G VN group should all anchor at the same network, i.e. the common home network of 5G VN group members.
- A DNN and S-NSSAI is associated with a 5G VN group.
- A dedicated SMF, a dedicated SMF Set or multiple SMF (Sets) can be responsible for all the PDU Sessions for communication of a certain 5G VN group. Multiple SMF (Sets) may apply for a 5G VN group extended over a large area, bigger than the service area of any SMF Set serving the DNN/S-NSSAI of the 5G VN group. SMF selection is described in clause 6.3.2.
NOTE 1: If a dedicated SMF (Set) is used to serve a 5G VN, the network is configured so that the same SMF (Set) is always selected for a certain 5G VN group, e.g. only one SMF, or SMFs in one SMF Set, registers on the NRF with the DNN/S-NSSAI used for a given 5G VN group.
NOTE 2: Having a dedicated SMF serving a 5G VN does not contradict that redundancy solutions can be used to achieve high availability. If SMF Set(s) serve the 5G VN group, high availability is achieved by the set functionality.
- In the case that more than one SMF sets or SMF instances in a SMF Set are responsible for all the PDU Sessions for communication of a certain 5G VN group to enable SMF redundancy for reliability of the 5G VN group communication:
- The associations between one or more SMF Sets and the DNN, S-NSSAI of the associated 5G VN group is registered and discovered in NRF.
- The SMFs that registered to associate with the DNN, S-NSSAI of the 5G VN group should be available in the LADN service area of the 5G VN group.
- The UE provides the DNN and S-NSSAI associated with the 5G VN group to access the 5G LAN-type services for that 5G VN, using the PDU Session Establishment procedure described in clause 4.3.2 of TS 23.502 [3].
- During establishment of the PDU Session, secondary authentication as described in clause 5.6.6 and in clause 4.3.2.3 of TS 23.502 [3], may be performed in order to authenticate and authorize the UE for accessing the DNN and S-NSSAI associated with the 5G VN group. Authentication and authorization for a DNN and S-NSSAI using secondary authentication implies authentication and authorization for the associated 5G VN group. There is no 5G VN group specific authentication or authorization defined.
- The SM level subscription data for a DNN and S-NSSAI available in UDM, as described in clause 5.6.1, applies to the DNN and S-NSSAI associated to a 5G VN group.
- Session management related policy control for a DNN and S-NSSAI as described in TS 23.502 [3], is applicable to the DNN and S-NSSAI associated to a 5G VN group. This includes also usage of URSP, for the UE to determine how to route outgoing traffic to a PDU Session for the DNN and S-NSSAI associated to a 5G VN group.
- Session and service continuity SSC mode 1, SSC mode 2 and SSC mode 3 as described in clause 5.6.9 are applicable to N6-based traffic forwarding of 5G VN communication within the associated 5G VN group.
- A PDU Session provides unicast, broadcast and multicast communication for the DNN and S-NSSAI associated to a 5G VN group. The PSA UPF determines whether the communication is for unicast, broadcast or multicast based on the destination address of the received data and performs unicast, broadcast or multicast communication handling.
- During the PDU Session Establishment procedure, the SMF retrieves SM subscription data related to 5G-VN type service from the UDM as part of the UE subscription data for the DNN and S-NSSAI.
- In order to realize N19 traffic routing in the case that a single SMF (or single SMF Set) is serving the 5G VN, the SMF (or SMF Set) correlates PDU sessions established to the same 5G VN group and uses this to configure the UPF with the group level N4-session including packet detection and forwarding rules for N19 tunnelling forwarding.
NOTE 3: In the case of a SMF Set serving a 5G VN, implementation dependent mechanism can be used between SMF(s) that are part of a SMF Set to control the N19 configuration.
- In order to realize N6/N19 traffic routing between PSA UPFs in case multiple SMF Sets are serving the 5G VN, traffic forwarding between UPFs belonging to different SMF (Set)s can be realized via User Plane tunnels that are configured using OAM between UPFs served by different SMF (Set)s. How to implement the user plane tunnels and traffic forwarding configured between these UPFs is up to network implementation and deployment and is out of scope of this specification. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.29.4 User Plane handling | User Plane management as defined for 5GS in clause 5.8 is applicable to 5G LAN-type services with the following clarifications:
- There are three types of traffic forwarding methods allowed for 5G VN communication:
- N6-based, where the UL/DL traffic for the 5G VN communication is forwarded to/from the DN;
NOTE 1: Optionally a L2TP tunnel can be established over N6 as described in clause 5.8.2.16.
- N19-based, where the UL/DL traffic for the 5G VN group communication is forwarded between PSA UPFs of different PDU sessions via N19. N19 is based on a shared User Plane tunnel connecting PSA UPFs of a single 5G VN group.
- Local switch, where traffic is locally forwarded by a single UPF if this UPF is the common PSA UPF of different PDU Sessions for the same 5G VN group.
- For UPFs served by a single SMF Set, the SMF instance(s) in the SMF set handles the user plane paths of the 5G VN group, including:
- The SMF instance(s) may prefer to select a single PSA UPF for as many PDU sessions (targeting the same 5G VN group) as possible, in order to implement local switch on the UPF.
- (if needed) Establishing N19 tunnels between PSA UPFs served by the same SMF set to support N19-based traffic forwarding.
- If multiple SMF (Set)s are serving a 5G VN, user plane forwarding between UPFs served by different SMF (Set)s can be achieved via the DN (i.e. N6) or via user plane tunnels on N6/N19 as described in clause 5.29.3.
NOTE 2: The above user plane tunnels may be using GTP-U or IETF VPN. For example, for IP-type traffic, the traffic routing can be based on routing protocols or pre-configured IP address ranges/prefixes corresponding different SMF sets; for ethernet-type traffic, the traffic routing can be based on the learned MAC address over the user plane tunnels between UPFs controlled by different SMF sets, etc. How to implement such user plane tunnels configured between these UPFs is up to network implementation and deployment.
- For Ethernet PDU Session, the SMF may instruct the UPF(s) to classify frames based on VLAN tags and to add and remove VLAN tags, on frames received and sent on N6 or N19 or internal interface ("5G VN internal"), as described in clause 5.6.10.2.
NOTE 3: For handling VLAN tags for traffic on N6, TSP ID could also be used as described in clause 6.2.2.6 of TS 23.503 [45].
Further description on User Plane management for 5G VN groups is available in clause 5.8.2.13.
When N6-based traffic forwarding is expected, after creation of a 5G VN group the AF can influence the traffic routing for all the members of the 5G VN group, by providing information identifying the traffic, DNAI(s) suitable for selection and an optional indication of traffic correlation together with a 5G VN External Group ID identifying the 5G VN group in an AF request sent to the PCF, as described in clause 5.6.7. If the optional indication of traffic correlation is provided, it means the PDU sessions of the 5G VN group member UEs should be correlated by a common DNAI in the user plane for the traffic. The PCF transforms the AF request into policies that apply to PDU Sessions of the 5G VN group and sends the policies to the SMF. According to the policies, the SMF (re)selects DNAI(s) for the PDU Sessions and configures their UP paths to route the traffic to the selected DNAI(s). If the policies include the traffic correlation indication, the SMF (re)selects a common DNAI for the PDU Sessions so that the traffic of the 5G VN group is routed to the common DNAI.
NOTE 4: When receiving a new PDU session establishment request for a 5G VN group, to avoid unnecessary N19 tunnels between UPFs, SMF can check previously selected UPFs for the same 5G VN group and decide whether a previously selected UPF could serve the requested PDU session.
NOTE 5: N19 tunnel(s) can be established between a new UPF and other UPF(s) that belongs to a 5G VN group when the new UPF is selected for the 5G VN group during PDU session establishment. The N19 tunnel(s) to a UPF can be released during or after PDU session release when there is no more PDU sessions for a 5G VN group in that UPF. Establishment or release of the N19 tunnels at the UPF is performed within a group-level N4 Session. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30 Support for non-public networks | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.1 General | A Non-Public Network (NPN) is a 5GS deployed for non-public use, see TS 22.261 [2]. An NPN is either:
- a Stand-alone Non-Public Network (SNPN), i.e. operated by an NPN operator and not relying on network functions provided by a PLMN, or
- a Public Network Integrated NPN (PNI-NPN), i.e. a non-public network deployed with the support of a PLMN.
NOTE: An NPN and a PLMN can share NG-RAN as described in clause 5.18.
Stand-alone NPN are described in clause 5.30.2 and Public Network Integrated NPNs are described in clause 5.30.3. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2 Stand-alone Non-Public Networks | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.0 General | SNPN 5GS deployments are based on:
- the architecture depicted in clause 4.2.3;
- the architecture for 5GC with Untrusted non-3GPP access (Figure 4.2.8.2.1-1) for either access to SNPN services via a PLMN (and vice versa) or for direct access to SNPN via non-3GPP access;
- the architecture for 5GC with Trusted non-3GPP access (Figure 4.2.8.2.1-2); and
- the additional functionality covered in clause 5.30.2.
Alternatively, a Credentials Holder (CH) may authenticate and authorize access to an SNPN separate from the Credentials Holder based on the architecture specified in clause 5.30.2.9. Idle and connected mode mobility is supported as defined in clause 5.30.2.11.
Clauses 5.30.2.1 to 5.30.2.11 specify the common SNPN aspects applicable to both 3GPP and non-3GPP access, except where stated differently.
Aspects specific to Untrusted non-3GPP access for SNPN are specified in clause 5.30.2.12.
Aspects specific to Trusted non-3GPP access for SNPN are specified in clause 5.30.2.13.
Aspects specific to N5CW devices accessing SNPN services are specified in clause 5.30.2.15.
Aspects specific to Proximity based Services (ProSe) for SNPN are defined in TS 23.304 [128].
The following 5GS features and functionalities are not supported for SNPNs:
- Interworking with EPS;
- Emergency services when the UE accesses the SNPN over NWu via a PLMN;
- Roaming, e.g. roaming between SNPNs. However, it is possible for a UE to access an SNPN with credentials from a CH as described in clause 5.30.2.9 and to move between equivalent SNPNs;
- Handover between SNPN and PLMN or PNI-NPN;
- CIoT 5GS Optimizations;
- CAG.
A UE with two or more network subscriptions, where one or more network subscriptions may be for a subscribed SNPN, can apply procedures specified for Multi-USIM UEs as described in clause 5.38. The UE shall use a separate PEI for each network subscription when it registers to the network.
NOTE: The number of preconfigured PEIs for a UE is limited. If the number of network subscriptions for a UE is greater than the preconfigured number of PEIs, the number of network subscriptions that can be registered with the network simultaneously is restricted by the number of pre-configured number of PEIs. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.1 Identifiers | The combination of a PLMN ID and a Network identifier (NID) identifies an SNPN.
NOTE 1: The PLMN ID used for SNPNs is not required to be unique. PLMN IDs reserved for use by private networks can be used for non-public networks, e.g. based on mobile country code (MCC) 999 as assigned by ITU [78]). Alternatively, a PLMN operator can use its own PLMN IDs for SNPN(s) along with NID(s), but registration in a PLMN and mobility between a PLMN and an SNPN are not supported using an SNPN subscription given that the SNPNs are not relying on network functions provided by the PLMN.
The NID shall support two assignment models:
- Self-assignment: NIDs are chosen individually by SNPNs at deployment time (and may therefore not be unique) but use a different numbering space than the coordinated assignment NIDs as defined in TS 23.003 [19].
- Coordinated assignment: NIDs are assigned using one of the following two options:
1. The NID is assigned such that it is globally unique independent of the PLMN ID used; or
2. The NID is assigned such that the combination of the NID and the PLMN ID is globally unique.
NOTE 2: Which legal entities manage the number space is beyond the scope of this specification.
NOTE 3: The use of SNPN with self-assignment model NID such that the combination of PLMN ID and NID is not globally unique is not assumed for the architecture described in Figure 5.30.2.9.3-1, Figure 5.30.2.9.2-1 and for SNPN - SNPN Mobility as described in clause 5.30.2.11.
The GIN shall support two assignment models:
- Self-assignment: GINs are chosen individually and may therefore not be unique. It is defined as in TS 23.003 [19]; or
- Coordinated assignment: GIN uses a combination of PLMN ID and NID and is assigned using one of the following two options as defined in TS 23.003 [19]:
1. The GIN is assigned such that the NID is globally unique (e.g. using IANA Private Enterprise Numbers) independent of the PLMN ID used; or
2. The GIN is assigned such that the combination of the NID and the PLMN ID is globally unique.
NOTE 4: Which legal entities manage the number space for GIN is beyond the scope of this specification.
An optional human-readable network name helps to identify an SNPN during manual SNPN selection. The human-readable network name and how it is used for SNPN manual selection is specified in TS 22.261 [2] and TS 23.122 [17]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.2 Broadcast system information | NG-RAN nodes or Trusted non-3GPP access networks which provide access to SNPNs broadcast the following information:
- One or multiple PLMN IDs;
- List of NIDs per PLMN ID identifying the non-public networks NG-RAN provides access to; and
NOTE 1: It is assumed that an NG-RAN node supports broadcasting a total of twelve NIDs. Further details are defined in TS 38.331 [28].
NOTE°2: The presence of a list of NIDs for a PLMN ID indicates that the related PLMN ID and NIDs identify SNPNs.
- Optionally:
- A human-readable network name per SNPN;
NOTE 3: The human-readable network name per SNPN is only used for manual SNPN selection. If the SNPN supports Localized Service, the human-readable network name of the SNPN can be information related to the Localized Service. The mechanism how human-readable network name is provided (i.e. whether it is broadcasted or unicasted) to the UE is specified in TS 38.331 [28].
- Information, as described in TS 38.300 [27], TS 38.331 [28] and in TS 38.304 [50], to prevent UEs not supporting SNPNs from accessing the cell, e.g. if the cell only provides access to non-public networks;
- An indication per SNPN of whether access using credentials from a Credentials Holder is supported;
- List of supported Group IDs for Network Selection (GINs) per SNPN; and
- An indication per SNPN of whether the SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, i.e. UEs that do not have any PLMN ID and NID nor GIN broadcast by the SNPN in the Credentials Holder controlled prioritized lists of preferred SNPNs/GINs.
NOTE 4: Further details (including number of supported GINs per SNPN) are defined in TS 38.331 [28]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.3 UE configuration and subscription aspects | An SNPN-enabled UE is configured with the following information for each subscribed SNPN:
- PLMN ID and NID of the subscribed SNPN;
- Subscription identifier (SUPI) and credentials for the subscribed SNPN;
- Optionally, an N3IWF FQDN and the MCC of the country where the configured N3IWF is located;
- Optionally, if the UE supports access to an SNPN using credentials from a Credentials Holder:
- User controlled prioritized list of preferred SNPNs;
- Credentials Holder controlled prioritized list of preferred SNPNs;
- Credentials Holder controlled prioritized list of GINs;
- Optionally, if the UE supports access to an SNPN using credentials from a Credentials Holder and access to an SNPN providing access for Localized Services:
- User controlled prioritized list of preferred SNPNs;
- Credentials Holder controlled prioritized list of preferred SNPNs for accessing Localized Services, each entry of the list includes:
- an SNPN identifier;
- validity information; and
- optionally, location assistance information;
- Credentials Holder controlled prioritized list of GINs for accessing Localized Services, each entry of the list includes:
- a GIN;
- validity information; and
- optionally, location assistance information;
- Protection scheme for concealing the SUPI as defined in TS 33.501 [29].
NOTE 1: Additionally the UE can be configured with indication to use anonymous SUCI as defined in TS 24.501 [47].
Validity information consists of:
- Time validity information, i.e. time periods (defined by start and end times) when access to the SNPN for accessing Localized Services is allowed; and
- optionally, location validity information containing one or more location information as defined in TS 24.501 [47].
NOTE 2: Usage of the location validity information is further explained in TS 23.122 [17].
Location assistance information consisting of:
- Geolocation information and/or,
- Tracking Area information of serving networks, i.e. lists of TACs per PLMN ID or per PLMN ID and NID.
The UE may use the location assistance information to determine where to search for the SNPNs in the Credentials Holder controlled prioritized list of SNPNs and GINs for accessing Localized Services, i.e. the location assistance information is not used for any area restriction enforcement.
For an SNPN-enabled UE with SNPN subscription, the Credentials Holder controlled prioritized lists of preferred SNPNs and GINs, or Credentials Holder controlled prioritized lists of preferred SNPNs and GINs for accessing Localized Services may be updated by the Credentials Holder using the Steering of Roaming (SoR) procedure as defined in Annex C of TS 23.122 [17]. Updating Credentials Holder controlled prioritized lists of preferred SNPNs and GINs, or Credentials Holder controlled prioritized lists of preferred SNPNs and GINs for accessing Localized Services via the Steering of Roaming (SoR) procedure is not applicable for Credentials Holder with AAA Server.
A subscription of an SNPN is either:
- identified by a SUPI containing a network-specific identifier that takes the form of a Network Access Identifier (NAI) using the NAI RFC 7542 [20] based user identification as defined in clause 28.7.2 of TS 23.003 [19]. The realm part of the NAI may include the NID of the SNPN; or
- identified by a SUPI containing an IMSI.
NOTE 3: As to route network signalling to AUSF and UDM instances serving the SNPN-enabled UE, the UE can be configured with Routing Indicator locally or updated with Routing Indicator using the UE Parameters Update via UDM Control Plane procedure defined in clause 4.20 of TS 23.502 [3]. When the SNPN credential is stored in the USIM, the Routing Indicator is provisioned in the USIM, when the SNPN credential is stored in the ME, the Routing Indicator is provisioned in the ME.
In the case of access to an SNPN using credentials owned by a Credentials Holder as specified in clause 5.30.2.9.2 and clause 5.30.2.9.3, the SUPI shall also contain identification for the Credentials Holder (i.e. the realm in the case of Network Specific Identifier based SUPI or the MCC and MNC in the case of an IMSI based SUPI). In the case of access to an SNPN using credentials owned by a Credentials Holder using AAA-S as specified in clause 5.30.2.9.2, only Network Specific Identifier based SUPI is supported.
NOTE 4: When Credentials Holder is an SNPN and the MCC and MNC of the SNPN is not unique (e.g. MCC =999 is used and MNC is not coordinated amongst the SNPNs), then IMSI based SUPI is not supported as the MCC and MNC need not be globally unique always; instead USIM credentials are supported using Network Specific Identifier based SUPI.
NOTE 5: Network Specific Identifier are not supported for the case the Credentials Holder is provided by a PLMN.
NOTE 6: It is assumed that normally the SNPN and the Credentials Holder use different PLMN ID. If the SNPN and CHs (where CH can be another SNPN or a PLMN) share PLMN ID and IMSI based SUPI is used, then the Routing Indicator can be used for AUSF/UDM discovery and selection as long as the Routing Indicator values are coordinated among the involved SNPN and CHs. When the PLMN ID is not shared between SNPNs and CHs (where CH can be another SNPN or a PLMN) and IMSI based SUPI is used, then PLMN ID is sufficient to be used for AUSF/UDM discovery & selection unless the CHs deploys multiple AUSF/UDM in which case also the Routing Indicator can be used as long as the Routing Indicator values are coordinated within the CH.
An SNPN-enabled UE that supports access to an SNPN using credentials from a Credentials Holder and that is equipped with a PLMN subscription may additionally be configured with the following information for SNPN selection and registration using the PLMN subscription in SNPN access mode:
- User controlled prioritized list of preferred SNPNs;
- Credentials Holder controlled prioritized list of preferred SNPNs;
- Credentials Holder controlled prioritized list of preferred GINs.
- Optionally if the UE supports access to an SNPN providing access for Localized Services:
- Credentials Holder controlled prioritized list of preferred SNPNs for accessing Localized Services, each entry of the list includes:
- an SNPN identifier;
- validity information; and
- optionally, location assistance information;
- Credentials Holder controlled prioritized list of preferred GINs for accessing Localized Services, each entry of the list includes:
- a GIN;
- validity information; and
- optionally, location assistance information.
Validity information consists of:
- Time validity information, i.e. time periods (defined by start and end times) when access to the SNPN for accessing Localized Services is allowed; and
- optionally, location validity information containing one or more location information as defined in TS 24.501 [47].
NOTE 7: Usage of the location validity information is further explained in TS 23.122 [17].
Location assistance information consisting of:
- Geolocation information and/or,
- Tracking Area information of serving networks, i.e. lists of TACs per PLMN ID or per PLMN ID and NID.
The UE may use the location assistance information to determine where to search for the SNPNs in the Credentials Holder controlled prioritized list of SNPNs and GINs for accessing Localized Services, i.e. the location assistance information is not used for any area restriction enforcement.
For an SNPN-enabled UE with PLMN subscription, the Credentials Holder controlled prioritized lists of preferred SNPNs and GINs, or the Credentials Holder controlled prioritized lists of preferred SNPNs and GINs for accessing Localized Services may be updated by the Credentials Holder using the Steering of Roaming (SoR) procedure as defined in Annex C of TS 23.122 [17].
When the Credentials Holder updates a UE with the Credentials Holder controlled prioritized lists of preferred SNPNs and GINs and/or the Credentials Holder controlled prioritized lists of preferred SNPNs and GINs for accessing Localized Services, the UE may perform SNPN selection again, e.g. to potentially select a higher prioritized SNPN or to potentially select an SNPN that provides access for Localized Services. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.4 Network selection in SNPN access mode | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.4.1 General | An SNPN-enabled UE supports the SNPN access mode. When the UE is set to operate in SNPN access mode the UE selects and registers with SNPNs over Uu as described in clause 5.30.2.4. Network selection in SNPN access mode for access to SNPN services via Untrusted non-3GPP access, Trusted non-3GPP access and Wireline access is specified in clause 5.30.2.12, clause 5.30.2.13 and clause 5.30.2.14 respectively. Access network selection in SNPN access mode for 5G NSWO is specified in clause 6.3.12b.
Emergency services are supported in SNPN access mode over Uu as defined in clause 5.16.4.1. Support for Emergency in SNPN access mode via Untrusted non-3GPP access is specified in clause 5.30.2.12.
If a UE is not set to operate in SNPN access mode, even if it is SNPN-enabled, the UE does not select and register with SNPNs. A UE not set to operate in SNPN access mode performs PLMN selection procedures as defined in clause 4.4 of TS 23.122 [17]. For a UE capable of simultaneously connecting to an SNPN and a PLMN, the setting for operation in SNPN access mode is applied to each of the Uu/Yt/NWu interfaces independently. Clause D.4 provides more details.
An SNPN-enabled UE that supports access to an SNPN using credentials from a Credentials Holder and that is equipped with a PLMN subscription needs to first enter SNPN access mode to be able to select SNPNs. Once the UE has entered SNPN access mode, SNPN selection is performed as described in clause 5.30.2.4. Once an SNPN has been selected the UE attempts registration in the SNPN using the PLMN credentials.
NOTE 1: Details of activation and deactivation of SNPN access mode are up to UE implementation.
When a UE is set to operate in SNPN access mode the UE does not perform normal PLMN selection procedures as defined in clause 4.4 of TS 23.122 [17].
UEs operating in SNPN access mode read the information described in clause 5.30.2.2 from the broadcast system information and take them into account during network selection. Furthermore, if the UE supports access to an SNPN providing access for Localized Services and the end user enables to access the Localized Services the UE may select an SNPN providing access for Localized Services.
NOTE 2: Details of how the user enables/disables access to Localized Services are up to UE implementation. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.4.2 Automatic network selection | NOTE 1: If the UE has multiple subscriptions (SNPN and/or PLMN) it is assumed that the subscription to use for automatic selection is determined by implementation specific means prior to network selection.
If the UE supports accessing an SNPN providing access for Localized Services and the end user enables to access Localized Services, for automatic network selection, the UE shall select and attempts registration on available SNPN in the following order:
(a) if the UE supports access to an SNPN using Credentials from a Credentials Holder then the UE continues by selecting and attempting registration on available and allowable SNPNs which broadcasts the indication that access using credentials from a Credentials Holder is supported in the following order:
i the SNPN with the validity information the UE was last registered with (if the validity information is met) or the SNPN's equivalent SNPN(s) (if available and the validity information of the SNPN that the UE was last registered with is met);
NOTE 2: The equivalent SNPN(s) are assumed to provide access to the same Localized Services as the SNPN the UE was last registered with.
ii SNPNs in the Credentials Holder controlled prioritized list of preferred SNPNs for accessing Localized Services (in priority order) if the validity information is met;
iii SNPNs, which additionally broadcast a GIN contained in the Credentials Holder controlled prioritized list of preferred GINs for accessing Localized Services (in priority order) if validity information is met;
(b) the SNPN without validity information the UE was last registered with (if available) or the equivalent SNPN (if available);
(c) the subscribed SNPN, which is identified by the PLMN ID and NID for which the UE has SUPI and credentials;
(d) the available and allowable SNPNs which broadcast the indication that access using credentials from a Credentials Holder is supported in the following order:
i SNPNs in the user controlled prioritized list of preferred SNPNs (in priority order);
ii SNPNs in the Credentials Holder controlled prioritized list of preferred SNPNs (in priority order);
iii SNPNs, which additionally broadcast a GIN contained in the Credentials Holder controlled prioritized list of preferred GINs (in priority order);
iv- SNPNs, which additionally broadcast an indication that the SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, i.e. the broadcasted NID or GIN is not present in the Credentials Holder controlled prioritized lists of preferred SNPNs/GINs, nor in the Credentials Holder controlled prioritized lists of preferred SNPNs/GINs for accessing Localized Services in the UE.
If the location validity information is not available and the time validity information is available, the validity conditions are met when the time validity conditions are met. If both the location validity information and the time validity information are available, the validity conditions are met when both the time validity conditions and the location validity conditions are met.
If the UE supports accessing an SNPN providing access for Localized Services and the end user enables to access Localized Services, the UE shall periodically attempt reselection and registration on a higher priority SNPN 1) based on the order of the above sub-bullets (i) to (iii) of bullet (a), bullet (c), sub-bullets (i) to (iii) of bullet (d) if the UE is not registered to the sub-bullet (i) of bullet (a) or 2) based on the order of the above sub-bullets (ii) to (iii) of bullet (a), bullet (c), sub-bullets (i) to (iii) of bullet (d) if the UE is registered to the sub-bullet (i) of bullet (a) if any of the below conditions is met:
- if there are one or more SNPNs with validity information which is met and the UE is not registered to an SNPN which has highest priority among the one or more SNPNs; or
- if there is no SNPN with validity information which is met and there are one or more GINs with the validity information which is met and the UE is not registered to an SNPN broadcasting a GIN which has highest priority among the one or more GINs; or
- if there is no SNPN with validity information which is met and there is no GIN with validity information which is met and the UE is not registered to the subscribed SNPN
Otherwise, the UE does not trigger periodic reselection and does not attempt registration on a higher priority SNPN.
NOTE 3: Details of network selection (e.g. validity information handling, periodicity determination) specified in TS 23.122 [17].
If the selected SNPN is an SNPN providing access for Localized Services and the validity condition for the selected SNPN changes from met to not met, the UE may attempt selection and registration on an SNPN based on the above bullets (a) to (d).
If the selected SNPN is not an SNPN providing access for Localized Services and a validity condition for an entry in Credentials Holder controlled prioritized list of preferred SNPNs/GINs for accessing Localized Services changes from not met to met, the UE may attempt selection and registration on an SNPN based on the above bullets (a) to (d).
If the UE does not support to access an SNPN providing access for Localized Services or the end user does not enable to access the Localized Services, for automatic network selection the UE shall select and attempts registration on available and allowable SNPNs in the following order:
- the SNPN without validity information the UE was last registered with (if available) or the equivalent SNPN (if available);
- the subscribed SNPN, which is identified by the PLMN ID and NID for which the UE has SUPI and credentials;
- If the UEs supports access to an SNPN using credentials from a Credentials Holder then the UE continues by selecting and attempting registration on available and allowable SNPNs which broadcast the indication that access using credentials from a Credentials Holder is supported in the following order:
- SNPNs in the user controlled prioritized list of preferred SNPNs (in priority order);
- SNPNs in the Credentials Holder controlled prioritized list of preferred SNPNs (in priority order);
- SNPNs, which additionally broadcast a GIN contained in the Credentials Holder controlled prioritized list of preferred GINs (in priority order);
NOTE 4: If multiple SNPNs are available that broadcast the same GIN, the order in which the UE selects and attempts a registration with those SNPNs is implementation specific.
- SNPNs, which additionally broadcast an indication that the SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, i.e. the broadcasted NID or GIN is not present in the Credentials Holder controlled prioritized lists of preferred SNPNs/GINs in the UE.
NOTE 5: If multiple SNPNs are available that broadcast the indication that the SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, the order in which the UE selects and attempts a registration with those SNPNs is implementation specific.
When a UE performs Registration or Service Request to an SNPN, the UE shall indicate the PLMN ID and NID as broadcast by the selected SNPN to NG-RAN. NG-RAN shall inform the AMF of the selected PLMN ID and NID. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.4.3 Manual network selection | For manual network selection UEs operating in SNPN access mode provide to the user the list of SNPNs (each is identified by a PLMN ID and NID) and related human-readable names (if available) of the available SNPNs the UE has respective SUPI and credentials for. If the UEs supports access to an SNPN using credentials from a Credentials Holder, the UE also presents available SNPNs which broadcast the "access using credentials from a Credentials Holder is supported" indication and the human-readable names related to the SNPNs (if available).
NOTE: The details of manual SNPN selection are defined in TS 23.122 [17].
When a UE performs Initial Registration to an SNPN, the UE shall indicate the selected PLMN ID and NID as broadcast by the selected SNPN to NG-RAN. NG-RAN shall inform the AMF of the selected PLMN ID and NID. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.5 Network access control | If a UE performs the registration or service request procedure in an SNPN identified by a PLMN ID and a self-assigned NID and there is no subscription for the UE, then the AMF shall reject the UE with an appropriate cause code to temporarily prevent the UE from automatically selecting and registering with the same SNPN.
If a UE performs the registration or service request procedure in an SNPN identified by a PLMN ID and a coordinated assigned NID and there is no subscription for the UE, then the AMF shall reject the UE with an appropriate cause code to permanently prevent the UE from automatically selecting and registering with the same SNPN.
NOTE: The details of rejection and cause codes is defined in TS 24.501 [47].
If a UE performs the registration in an SNPN using credentials from a Credentials Holder (i.e. the CH is the PLMN/SNPN that owns the UE subscription and controls the access) and the Credentials Holder does not authorize the UE to access that specific SNPN due to access authorization based on subscription data or invalid time for accessing an SNPN that provides access to Localized Services, then the UDM, in the Credentials Holder, can reject the UE which results in AMF rejecting the registration request from the UE with an appropriate cause code to prevent the UE from automatically selecting and registering with the same SNPN using credentials from the Credentials Holder as described in TS 24.501 [47].
In order to prevent access to SNPNs for authorized UE(s) in the case of network congestion/overload, Unified Access Control information is configured per SNPN (i.e. as part of the subscription information that the UE has for a given SNPN) and provided to the UE as described in TS 24.501 [47]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.6 Cell (re-)selection in SNPN access mode | UEs operating in SNPN access mode only select cells and networks broadcasting both PLMN ID and NID of the selected SNPN or its equivalent SNPN.
NOTE: Further details on the NR idle and inactive mode procedures for SNPN cell selection is defined in TS 38.331 [28] and in TS 38.304 [50]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.7 Access to PLMN services via stand-alone non-public networks | To access PLMN services, a UE in SNPN access mode that has successfully registered with an SNPN may perform another registration via the SNPN User Plane with a PLMN (using the credentials of that PLMN) following the same architectural principles as specified in clause 4.2.8 (including the optional support for PDU Session continuity between PLMN and SNPN using the Handover of a PDU Session procedures in clauses 4.9.2.1 and 4.9.2.2 of TS 23.502 [3]) and the SNPN taking the role of "Untrusted non-3GPP access". Annex D, clause D.3 provides additional details.
NOTE: QoS differentiation in the SNPN can be provided on per-IPsec Child Security Association basis by using the UE or network requested PDU Session Modification procedure described in clause 4.3.3.2 of TS 23.502 [3]. In the PLMN, N3IWF determines the IPsec child SAs as defined in clause 4.12 of TS 23.502 [3]. The N3IWF is preconfigured by PLMN to allocate different IPsec child SAs for QoS Flows with different QoS profiles.
To support QoS differentiation in the SNPN with network-initiated QoS, the mapping rules between the SNPN and the PLMN are assumed to be governed by an SLA including: 1) mapping between the DSCP markings for the IPsec child SAs on NWu and the corresponding QoS, which is the QoS requirement of the PLMN and is expected to be provided by the SNPN and 2) N3IWF IP address(es) in the PLMN. The non-alteration of the DSCP field on NWu is also assumed to be governed by an SLA and by transport-level arrangements that are outside of 3GPP scope. The packet detection filters in the SNPN can be based on the N3IWF IP address and the DSCP markings on NWu.
To support QoS differentiation in the SNPN with UE-requested QoS, the UE can request for an IPsec SA the same 5QI from the SNPN as the 5QI provided by the PLMN. It is assumed that UE-requested QoS is used only when the 5QIs used by the PLMN are from the range of standardized 5QIs. The packet filters in the requested QoS rule can be based on the N3IWF IP address and the SPI associated with the IPsec SA.
Refer to clause D.7 for details on how to support QoS differentiation.
When the UE accesses the PLMN over NWu via a SNPN, the AMF in the serving PLMN shall send an indication toward the UE during the Registration procedure to indicate whether an IMS voice over PS session is supported or not. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.8 Access to stand-alone non-public network services via PLMN | To access SNPN services, a UE that has successfully registered with a PLMN over 3GPP access may perform another registration via the PLMN User Plane with an SNPN (using the credentials of that SNPN) following the same architectural principles as specified in clause 4.2.8 (including the optional support for PDU Session continuity between PLMN and SNPN using the Handover of a PDU Session procedures in clauses 4.9.2.1 and 4.9.2.2 of TS 23.502 [3]) and the PLMN taking the role of "Untrusted non-3GPP access" of the SNPN, i.e. using the procedures for Untrusted non-3GPP access in clause 4.12.2 of TS 23.502 [3]. Annex D, clause D.3 provides additional details. The case where UE that has successfully registered with a PLMN over non-3GPP access to access SNPN services is not specified in this Release.
NOTE: QoS differentiation in the PLMN can be provided on per-IPsec Child Security Association basis by using the UE or network requested PDU Session Modification procedure described in clause 4.3.3.2 of TS 23.502 [3]. In the SNPN, N3IWF determines the IPsec child SAs as defined in clause 4.12 of TS 23.502 [3]. The N3IWF is preconfigured by SNPN to allocate different IPsec child SAs for QoS Flows with different QoS profiles.
To support QoS differentiation in the PLMN with network-initiated QoS, the mapping rules between the PLMN and the SNPN are assumed to be governed by an SLA including: 1) mapping between the DSCP markings for the IPsec child SAs on NWu and the corresponding QoS, which is the QoS requirement of the SNPN and is expected to be provided by the PLMN and 2) N3IWF IP address(es) in the SNPN. The non-alteration of the DSCP field on NWu is also assumed to be governed by an SLA and by transport-level arrangements that are outside of 3GPP scope. The packet detection filters in the PLMN can be based on the N3IWF IP address and the DSCP markings on NWu.
To support QoS differentiation in the PLMN with UE-requested QoS, the UE can request for an IPsec SA the same 5QI from the PLMN as the 5QI provided by the SNPN. It is assumed that UE-requested QoS is used only when the 5QIs used by the SNPN are from the range of standardized 5QIs. The packet filters in the requested QoS rule can be based on the N3IWF IP address and the SPI associated with the IPsec SA.
Refer to clause D.7 for details on how to support QoS differentiation.
When the UE accesses the SNPN over NWu via a PLMN, the AMF in the SNPN shall send an indication toward the UE during the Registration procedure to indicate whether an IMS voice over PS session is supported or not. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.9 SNPN connectivity for UEs with credentials owned by Credentials Holder | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.9.1 General | SNPNs may support UE access using credentials owned by a Credentials Holder separate from the SNPN. In this case the Session Management procedures (i.e. PDU Sessions) terminate in an SMF in the SNPN.
When an SNPN supports UE access using credentials assigned by a Credentials Holder separate from the SNPN, it is assumed that is supported homogeneously within the whole SNPN.
Credentials Holder using AAA Server for primary authentication and authorization is described in clause 5.30.2.9.2 and Credentials Holder using AUSF and UDM for primary authentication and authorization is described in clause 5.30.2.9.3. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.9.2 Credentials Holder using AAA Server for primary authentication and authorization | The AUSF and the UDM in SNPN may support primary authentication and authorization of UEs using credentials from a AAA Server in a Credentials Holder (CH).
- Only NSI based SUPI is supported and the SUPI is used to identify the UE during primary authentication and authorization towards the AAA Server. SUPI privacy is achieved according to methods in clause I.5 of TS 33.501 [29].
- The AMF discovers and selects the AUSF as described in clause 6.3.4 using the Home Network Identifier (realm part) and Routing Indicator present in the SUCI provided by a UE configured as described in clause 5.30.2.3.
- The AMF selects the UDM in the same SNPN, based on local configuration (e.g. using the realm part of the SUCI), or using the NRF procedure defined in clause 4.17.4a of TS 23.502 [3].
- If the UDM decides that the primary authentication is performed by AAA Server in CH based on the UE's SUPI and subscription data. The Home Network Identifier, is derived by UDM from the SUCI received from AUSF. If the SUCI was generated using a privacy protection scheme that requires de-concealment, UDM de-conceal the SUCI as defined in TS 33.501 [29]. The UDM then instructs the AUSF that primary authentication by a AAA Server in a CH is required, the AUSF shall discover and select the NSSAAF and then forward EAP messages to the NSSAAF. The NSSAAF selects AAA Server based on the domain name corresponds to the realm part of the SUPI, relays EAP messages between AUSF and AAA Server (or AAA proxy) and performs related protocol conversion. The AAA Server acts as the EAP Server for the purpose of primary authentication.
NOTE 1: The UDM in SNPN, based on SLA between Credentials Holder and SNPN, is pre-configured with information indicating whether the UE needs primary authentication from AAA Server.
NOTE 2: It is assumed that the SNPN is configured on per Home Network Identifier basis to determine whether to perform primary authentication with AUSF/UDM or AAA server.
- The AMF and SMF shall retrieve the UE subscription data from UDM using SUPI.
Figure 5.30.2.9.2-1 depicts the 5G System architecture for SNPN with Credentials Holder using AAA Server for primary authentication and authorization.
NOTE 3: The SNPN in Figure 5.30.2.9.2-1 can be the subscribed SNPN for the UE (i.e. NG-RAN broadcasts SNPN ID of the subscribed SNPN). As a deployment option, the SNPN in Figure 5.30.2.9.2-1 can also be another SNPN than the subscribed SNPN for the UE (i.e. none of the SNPN IDs broadcast by NG-RAN matches the SNPN ID corresponding to the subscribed SNPN). In both cases, the AUSF, UDM and NSSAAF are configured to support the HNI of the UE's SUPI/SUCI, SUPI privacy settings (when using privacy protection scheme other than the 'null-scheme' to generate the SUCI as defined in TS 33.501 [29]), subscription data of the UE and authentication settings to allow UE authentication with AAA-S in CH.
Figure 5.30.2.9.2-1: 5G System architecture with access to SNPN using credentials from Credentials Holder using AAA Server
NOTE 4: The NSSAAF deployed in the SNPN can support primary authentication in the SNPN using credentials from Credentials Holder using a AAA Server (as depicted) and/or the NSSAAF can support Network Slice-Specific Authentication and Authorization with a Network Slice-Specific AAA Server (not depicted). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.9.3 Credentials Holder using AUSF and UDM for primary authentication and authorization | An SNPN may support primary authentication and authorization of UEs that use credentials from a Credentials Holder using AUSF and UDM. The Credentials Holder may be an SNPN or a PLMN. The Credentials Holder UDM provides to SNPN the subscription data.
NOTE 1: A list of functionalities not supported in SNPN is provided in clause 5.30.2.0.
Optionally, an SNPN may support network slicing (including Network Slice-Specific Authentication and Authorization, Network Slice Access Control and subscription-based restrictions to simultaneous registration of network slices) for UEs that use credentials from a Credentials Holder using AUSF and UDM. The SNPN retrieves NSSAA and NSSRG information from the UDM of the Credentials Holder.
Figure 5.30.2.9.3-1 depicts the 5G System architecture for SNPN with Credentials Holder using AUSF and UDM for primary authentication and authorization and network slicing.
NOTE 2: The architecture for SNPN and Credentials Holder using AUSF and UDM is depicted as a non-roaming reference architecture as the UE is not considered to be roaming, even though some of the roaming architecture reference points are also used, e.g. for AMF and SMF in SNPN to register with and retrieve subscription data from UDM of the Credentials Holder.
Figure 5.30.2.9.3-1: 5G System architecture with access to SNPN using credentials from Credentials Holder using AUSF and UDM |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.10 Onboarding of UEs for SNPNs | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.10.1 General | Onboarding of UEs for SNPNs allows the UE to access an Onboarding Network (ONN) for the purpose of provisioning the UE with SNPN credentials for primary authentication and other information to enable access to a desired SNPN, i.e. (re-)select and (re-)register with SNPN.
To provision SNPN credentials in a UE that is configured with Default UE credentials (see clause 5.30.2.10.2.4), the UE selects an SNPN as ONN and establishes a secure connection with that SNPN referred to as Onboarding SNPN (ON-SNPN), see more details in clause 5.30.2.10.2.
NOTE: If the UE is already provisioned with a set of SNPN credentials or credentials owned by a Credentials Holder and needs to be provisioned with an additional set of SNPN credentials, the UE can access an SNPN using the network selection in SNPN access mode as described in clause 5.30.2.4, normal registration (i.e. not registration for onboarding) and normal PDU Session (i.e. not a restricted PDU Session used for onboarding) and then leverage the SNPN's User Plane connection to get access to a PVS. The PVS address can be provided in the same way as when the Onboarding Network is a PLMN.
To provision SNPN credentials in a UE that is equipped with a USIM configured with PLMN credentials, the UE selects a PLMN as ONN and establishes a secure connection with that PLMN, see more details in clause 5.30.2.10.3.
After the secure connection is established, the UE is provisioned with SNPN credentials and possibly other data to enable discovery, (re-)selection and (re-)registration for a desired SNPN, see more details in clause 5.30.2.10.4.
ON-SNPN and SO-SNPN can be roles taken by either an SNPN or different SNPNs. It is possible for the same network to be in both roles with respect to a specific UE. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.10.2 Onboarding Network is an SNPN | 5.30.2.10.2.1 General
A UE configured with Default UE credentials may register with an ON-SNPN for the provisioning of SO-SNPN credentials.
5.30.2.10.2.2 Architecture
Figures 5.30.2.10.2.2-1, 5.30.2.10.2.2-2 and 5.30.2.10.2.2-3 depict the architecture for Onboarding of UEs in an ON-SNPN.
Figure 5.30.2.10.2.2-1: Architecture for UE Onboarding in ON-SNPN when the DCS includes an AUSF and a UDM
Figure 5.30.2.10.2.2-2: Architecture for UE Onboarding in ON-SNPN when the DCS includes a AAA Server used for primary authentication
Figure 5.30.2.10.2.2-3: Architecture for UE Onboarding in ON-SNPN when the DCS is not involved during primary authentication
NOTE 1: AUSF in the ON-SNPN interfaces with the DCS via NSSAAF as shown in Figure 5.30.2.10.2.2-2 owned by an entity that is internal or external to the ON-SNPN.
NOTE 2: The functionality with respect to exchange information between PVS and SO-SNPN to provision SNPN credentials and other data from the SO-SNPN in the UE is out of 3GPP scope.
NOTE 3: The dotted lines in Figure 5.30.2.10.2.2-1, Figure 5.30.2.10.2.2-2 and Figure 5.30.2.10.2.2-3 indicate that whether domains (e.g. DCS domain, PVS domain and SO-SNPN) are separated depends on the deployment scenario.
NOTE 4: See TS 33.501 [29] for the functionality beyond AUSF and other interfaces required for security.
NOTE 5: When secondary authentication is used in the context of the UE onboarding architecture in Figure 5.30.2.10.2.2-3, the same S-NSSAI/DNN or different S-NSSAI/DNNs can be used for the onboarding PDU Sessions of different UEs even though the DN-AAA servers that authenticate the UEs can reside in different administrative domains.
When the DCS is involved during mutual primary authentication during the Onboarding procedure (as in Figure 5.30.10.2.2-1 and Figure 5.30.10.2.2-2), the following applies:
- When the DCS includes an AUSF and a UDM functionality, then the AMF selects AUSF in the DCS domain. The ON-SNPN and DCS domain are connected via N32 and SEPP which are not shown in the Figure 5.30.2.10.2.2-1.
- When the DCS includes a AAA Server functionality, only NSI based SUPI is supported and the AMF selects AUSF in the ON-SNPN. Based on local configuration (e.g. using the realm part of the Onboarding SUCI), the AUSF skips the UDM selection and directly performs primary authentication towards DCS with AAA Server functionality using Default UE credentials for primary authentication. The AUSF uses an NSSAAF (and the NSSAAF may use a AAA-P which is not shown in the figure 5.30.2.10.2.2-2) to relay EAP messages towards the DCS including a AAA Server. The NSSAAF selects AAA Server based on the domain name corresponding to the realm part of the SUPI.
NOTE 5: The AMF in ON-SNPN uses the Home Network Identifier of the Onboarding SUCI to select the DCS. It is assumed that the ON-SNPN is configured on per Home Network Identifier basis to determine whether to perform primary authentication with AUSF/UDM or AAA server.
- Upon establishment of the PDU Session used for User Plane Remote Provisioning the ON-SNPN may trigger secondary authentication procedure, as described in clause 4.3.2.3 of TS 23.502 [3], with a DN-AAA using Default UE credentials for secondary authentication as described in clause I.9.2.4 of TS 33.501 [29].
When the DCS is not involved during primary authentication (as in Figure 5.30.10.2.2-3), the following applies:
- The AMF selects a local AUSF as described in clause 5.30.2.10.2.6 and performs primary authentication towards the local AUSF using Default UE credentials for primary authentication as described in TS 33.501 [29].
- Upon establishment of the PDU Session used for User Plane Remote Provisioning the ON-SNPN may trigger secondary authentication procedure, as described in clause 4.3.2.3 of TS 23.502 [3], with the DCS or with a DN-AAA server using Default UE credentials for secondary authentication, as described in clause I.9.2.4 of TS 33.501 [29]. When secondary authentication is used, the SMF identifies the DCS or the DN-AAA server as defined in clause 4.3.2.3 of TS 23.502 [3].
NOTE 6: If the secondary authentication fails, the SMF rejects the PDU Session used for User Plane Remote Provisioning. Based on local policy the AMF can deregister the UE as described in clause 5.30.2.10.2.7.
NOTE 7: The DCS and PVS can be owned by an administrative entity that can be different from either the ON-SNPN or SO-SNPN. The ownership of DCS and PVS is outside the scope of 3GPP.
5.30.2.10.2.3 Broadcast system information
When the SNPN supports Onboarding of UEs for SNPNs (i.e. the SNPN can be used as ON-SNPN), the NG-RAN node or the Trusted non-3GPP access network providing access to SNPN additionally broadcasts the following information:
- An onboarding enabled indication that indicates whether onboarding is currently enabled for the SNPN. For access to SNPN via NG-RAN the onboarding enabled indication is broadcasted per cell e.g. to allow start of the onboarding procedure only in parts of the SNPN.
NOTE: Onboarding enabled indication per cell does not affect mobility management functions, i.e. once the UE selects the ON-SNPN as described in clause 5.30.2.10.2.5 and successfully registers within ON-SNPN as described in clause 5.30.2.10.2.6, the UE can move to a cell of the ON-SNPN not indicating onboarding support and continue with the remote provisioning as described in clause 5.30.2.10.4.
5.30.2.10.2.4 UE Configuration Aspects
A UE enabled to support UE Onboarding, shall be pre-configured with Default UE credentials and the UE may be pre-configured with ON-SNPN selection information. The Default UE credentials consist of credentials for primary authentication and optionally credentials for secondary authentication, as described in clause I.9 of TS 33.501 [29].
NOTE 1: The content of the ON-SNPN network selection information depends on UE implementation and can include SNPN network identifiers and/or GIN(s).
The UE uses the ON-SNPN selection information for selection of ON-SNPN (see clause 5.30.2.10.2.5).
The UE Configuration Data for UP Remote Provisioning is described in the clause 5.30.2.10.4.2.
NOTE 2: It is assumed that the UE is not pre-configured with a S-NSSAI and DNN for the purpose of UE onboarding in the ON-SNPN.
NOTE 3: The Default UE credentials for primary authentication are used to derive a SUPI. When the UE derives the SUPI from the Default UE credentials for primary authentication, the UE performs specific onboarding procedure as described in clauses 5.30.2.10.2.5, 5.30.2.10.2.6 and 5.30.2.10.2.7.
5.30.2.10.2.5 Network selection
This clause applies only when the UE is in SNPN access mode.
When the UE wants to perform UE onboarding via an SNPN, the UE shall perform ON-SNPN selection as described below. An ON-SNPN is an SNPN providing onboarding access and enabling remote provisioning for a UE registered for onboarding as specified in clause 4.2.2.2.4 of TS 23.502 [3].
NOTE: The trigger for the UE to initiate the UE Onboarding procedure is UE implementation dependent (e.g. the trigger can be a power-on event in the UE, or an input by the user).
For automatic or manual selection, the UE may select and attempt to register to an ON-SNPN which broadcast the Onboarding enabled indication described in clause 5.30.2.10.2.3 and matches the pre-configured ON-SNPN selection information such as SNPN network identifier and/or GIN(s) (if available) described in clause 5.30.2.10.2.4 according to the UE implementation-specific logic. If the registration fails, the UE may select and attempt to register to a different ON-SNPN as defined in clause 4.9.3.1.3 or clause 4.9.3.1.4 of TS 23.122 [17].
5.30.2.10.2.6 Registration for UE onboarding
When the user or UE has selected an ON-SNPN according to clause 5.30.2.10.2.5, the UE establishes an RRC connection towards the NG-RAN node of the ON-SNPN. The UE provides an indication in RRC Connection Establishment that the RRC connection is for onboarding as defined in TS 38.331 [28]. This indication allows the NG-RAN node to select an appropriate AMF that supports the UE onboarding procedures. The UE indicates the ON-SNPN as the selected network and the NG-RAN node shall indicate the selected PLMN ID and NID of the ON-SNPN to the AMF.
NOTE 1: As the configuration information in the UE does not include any S-NSSAI and DNN used for onboarding, the UE does not include S-NSSAI and DNN in RRC when it registers for UE onboarding purposes to the ONN.
The UE shall initiate the NAS registration procedure by sending a NAS Registration Request message with the following characteristics:
- The UE shall set the 5GS Registration Type to the value "SNPN Onboarding" indicating that the registration request is for onboarding.
- The UE shall provide a SUCI derived from a SUPI as specified in TS 23.003 [19] and TS 33.501 [29]. The SUPI shall uniquely identify the UE and shall be derived from the Default UE credentials for primary authentication. The SUPI used for onboarding may contain an IMSI or a network-specific identifier. The ON-SNPN may determine the corresponding DCS identity or address/domain, based on the SUCI (i.e. based on the Home Network Identifier of the SUCI).
The UE does not include a Requested NSSAI in NAS signalling when it registers for UE onboarding purposes to the ON-SNPN.
The AMF supporting UE onboarding is configured with AMF Onboarding Configuration Data that includes e.g.:
- S-NSSAI and DNN to be used for onboarding or a configured SMF for the S-NSSAI and DNN used for onboarding.
- Information to use a local AUSF(s) within the ON-SNPN for onboarding of UEs with a SUCI for a DCS with AAA Server or for onboarding of UEs in the case where the DCS is not involved during primary authentication.
NOTE 2: The S-NSSAI used for onboarding is assumed to be configured in both the AMF (i.e. in the AMF Onboarding Configuration Data) and the NG-RAN nodes for the corresponding Tracking Areas where onboarding is enabled.
When the AMF receives a NAS Registration Request with a 5GS Registration Type set to "SNPN Onboarding", the AMF:
- starts an authentication procedure towards the AUSF, the authentication procedure is specified in TS 33.501 [29]. The AMF may be provided with PVS IP address(es) or PVS FQDN(s) from the DCS during authentication procedure. The AMF selects an appropriate AUSF as described in clause 6.3.4 based on the Home Network Identifier of the SUCI used during onboarding or based on local configuration in the AMF.
- applies the AMF Onboarding Configuration Data e.g. used to restrict UE network usage to only onboarding for User Plane Remote Provisioning of UE as described in clause 5.30.2.10.4.3.
- stores in the UE context in AMF an indication that the UE is registered for SNPN onboarding.
- shall handle the list of equivalent SNPNs as described in TS 24.501 [47].
Upon successful authentication from AUSF, the AMF informs the UE about the result of the registration. If the UE is not successfully authenticated, the AMF shall reject the registration procedure for onboarding and the UE may select a different ON-SNPN to attempt to register.
NOTE 3: The AMF does not interact with the UDM of the ON-SNPN or DCS (i.e. for registration or subscription management purposes) when it receives a NAS Registration Request with a 5GS Registration Type set to "SNPN Onboarding" (see clause 4.2.2.2.4 of TS 23.502 [3]).
5.30.2.10.2.7 Deregistration from the ON-SNPN for onboarding registered UE
Once remote provisioning of SO-SNPN credentials is completed, the UE should initiate deregistration from the ON-SNPN.
Based on ON-SNPN policies, the AMF may start an implementation specific timer once the UE has registered to the ON-SNPN for the purpose of onboarding. Expiry of this timer triggers the AMF to deregister the onboarding registered UE from the ON-SNPN.
The AMF may also deregister the UE when it determines that the PDU Session used for User Plane Remote Provisioning has been released by the SMF.
When AMF re-allocation occurs for a UE registered for SNPN onboarding during mobility registration update procedure as described in TS 23.502 [3] in clause 4.2.2.2.4 or during N2 based handover as described in TS 23.502 [3] clause 4.9.1.3, the new AMF supporting SNPN Onboarding should be selected as described in clause 6.3.5. If the new AMF receives in UE context the indication that the UE is registered for SNPN onboarding, the new AMF may start an implementation specific timer for when to deregister the UE when the new AMF completes the Registration procedure (i.e. sends Registration Accept to the UE) or completes the N2 based handover procedure.
NOTE: This specific timer is used to prevent onboarding registered UEs from staying at the ON-SNPN indefinitely. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.10.3 Onboarding Network is a PLMN | 5.30.2.10.3.1 General
A UE configured with PLMN credentials in USIM for primary authentication may register with a PLMN for the provisioning of SO-SNPN credentials.
5.30.2.10.3.2 Network selection and Registration
This clause applies only when the UE is not in SNPN access mode.
When the UE is using PLMN credentials for accessing a PLMN as the Onboarding Network (ONN), then regular network selection, as per TS 23.122 [17] and regular initial registration procedures apply, as per TS 23.502 [3]. After successfully registering to the ON-PLMN, the UE is provisioned with the SO-SNPN credentials via User Plane as in clause 5.30.2.10.4.4.
NOTE: When Onboarding network is a PLMN and the UE's subscription only allows for Remote Provisioning, then based on PLMN policies, the AMF can start an implementation specific timer once the UE has registered to the PLMN. Expiry of this timer triggers the AMF to deregister the UE from the PLMN. This specific timer is used to prevent registered UEs that are only allowed for Remote Provisioning from staying at the PLMN indefinitely. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.10.4 Remote Provisioning of UEs in Onboarding Network | 5.30.2.10.4.1 General
Remote Provisioning of UEs that registered with an Onboarding Network enables provisioning the UE with SNPN credentials for primary authentication and other information to enable access to the desired SNPN.
Onboarding Services are provided using a PDU Session for DNN and S-NSSAI used for onboarding allowing remote provisioning of UEs via User Plane. The PDU Session may be restricted only to be used for Remote Provisioning of the UE.
5.30.2.10.4.2 Onboarding configuration for the UE
In order to enable UP Remote Provisioning of SNPN credentials for a UE, UE Configuration Data for User Plane Remote Provisioning are either pre-configured on the UE or provided by the ONN. UE Configuration Data for User Plane Remote Provisioning provided by the ONN take precedence over corresponding configuration data stored in the UE.
UE Configuration Data for User Plane Remote Provisioning consist of PVS IP address(es) and/or PVS FQDN(s).
If the UE does not have any PVS IP address or PVS FQDN after the establishment of the PDU Session used for User Plane Remote Provisioning, the UE may construct an FQDN for PVS discovery as defined in TS 23.003 [19].
The UE Configuration Data for User Plane Remote Provisioning may be stored in the ME.
The UE Configuration Data for User Plane Remote Provisioning (i.e. PVS IP address(es) or PVS FQDN(s), or both) may be:
- locally configured in the SMF of ONN; and/or
- provided by the DCS to the AMF of ON-SNPN as part of the authentication procedure as specified in TS 33.501 [29] and sent by the AMF in the Nsmf_PDUSession_CreateSMContext Request message to the SMF
If the SNPN acting as ON-SNPN is not capable to provide access to Localized Services, the PVS IP address(es) and/or PVS FQDN(s) provided by the DCS take precedence over the locally configured PVS IP address(es) and/or PVS FQDN(s) in the ON-SNPN. If the SNPN acting as ON-SNPN is capable to provides access to Localized Services, the SMF should include both DCS provided and the locally configured PVS IP address(es) and/or PVS FQDN(s), in the UE Configuration Data for User Plane Remote Provisioning.
If the PCF is used for User Plane Remote Provisioning, the SMF provides the UE Configuration Data to the PCF as described in clause 5.30.2.10.4.3.
The UE Configuration Data for User Plane Remote Provisioning may be provided to the UE during the establishment of the PDU Session used for User Plane Remote Provisioning as part of Protocol Configuration Options (PCO) in the PDU Session Establishment Response.
NOTE: If there are multiple PVS IP addresses and/or PVS FQDNs in the UE, how the UE selects PVS from this information is up to UE implementation.
5.30.2.10.4.3 User Plane Remote Provisioning of UEs when Onboarding Network is an ON-SNPN
The AMF selects an SMF used for User Plane Remote Provisioning using the SMF discovery and selection functionality as described in clause 6.3.2. The S-NSSAI and DNN of the AMF Onboarding Configuration Data may be used to discover and select an SMF for User Plane Remote Provisioning. Alternatively, for SMF selection, the AMF Onboarding Configuration Data may contain a configured SMF for the S-NSSAI and DNN used for onboarding. The AMF provides Onboarding Indication to SMF via Nsmf_PDUSession_CreateSMContext request message when a PDU Session used for User Plane Remote Provisioning is established. During PDU Session establishment for remote provisioning, the AMF may provide the PVS IP address(es) and/or PVS FQDN(s) to the SMF.
When a UPF is selected for User Plane Remote Provisioning, the UPF selection function described in clause 6.3.3 for normal services is applied considering the S-NSSAI and DNN used for onboarding.
The SMF or the PCF may store S-NSSAI and DNN information used for onboarding. Onboarding Configuration Data available to PCF (for details see TS 23.503 [45]) and/or SMF may include PVS FQDN(s) and/or PVS IP address(es). The SMF and the PCF may use Onboarding Indication and DNN and S-NSSAI used for onboarding to access the Onboarding Configuration Data.
NOTE: The SMF is aware about the PVS IP address(es) and/or PVS FQDN(s) in one of the following ways: either received from the AMF or retrieved locally from the Onboarding Configuration Data.
When the UE registered for Onboarding (i.e. 5GS Registration Type is set to the value "SNPN Onboarding") successfully completes the User Plane Remote Provisioning of SNPN credentials via the Onboarding Network, then the UE should deregister from the Onboarding Network.
Initial QoS parameters used for User Plane Remote Provisioning are configured in the SMF when dynamic PCC is not used.
Dynamic PCC may be used for a PDU Session used for User Plane Remote Provisioning as described in TS 23.503 [45]. If a PCF is used and the AMF provided an Onboarding Indication, the SMF provides Onboarding Indication to the PCF when requesting an SM Policy Association. The SMF may provide the UE Configuration Data (i.e. PVS IP address(es) and/or PVS FQDN(s)) to the PCF when requesting an SM Policy Association.
The QoS Flows of a restricted PDU Session, which is associated with the S-NSSAI/DNN used for Onboarding, shall be dedicated to Onboarding Services. The SMF may configure in the UPF PDR(s) and FAR(s) including PVS and DNS server IP addresses to block any traffic that is not from or to PVS and DNS server addresses.
If the UE is registered for Onboarding (i.e. 5GS Registration Type is set to the value "SNPN Onboarding"), the network should apply S-NSSAI and DNN in the Onboarding Configuration Data for the PDU Session Establishment request from the UE.
5.30.2.10.4.4 User Plane Remote Provisioning of UEs when Onboarding Network is a PLMN
Subscription data of such a UE shall contain the DNN and S-NSSAI used for onboarding.
The AMF selects an SMF used for User Plane Remote Provisioning using the SMF discovery and selection functionality as described in clause 6.3.2, considering the DNN and S-NSSAI used for onboarding provided by the UE or the default DNN and S-NSSAI provided by UDM.
The UPF selection function described in clause 6.3.3 is applied, considering the DNN and S-NSSAI used for onboarding.
The SMF may be configured with one or more PVS FQDN(s) and/or PVS IP address(es) per DNN and S-NSSAI used for onboarding. When the UE requests a PDU Session used for User Plane Remote Provisioning by using DNN and S-NSSAI used for onboarding, the SMF sends the PVS FQDN(s) and/or PVS IP address(es) associated to the DNN and S-NSSAI of the PDU Session to the UE as part of Protocol Configuration Options (PCO) in the PDU Session Establishment Response if the following conditions are met:
- the UE subscription data contains the DNN and S-NSSAI used for onboarding; and
- the SMF has obtained the PVS FQDN(s) and/or PVS IP address(es) associated to the DNN and S-NSSAI of the PDU Session from local configuration; and
- the UE has requested PVS information via PCO in PDU Session Establishment Request.
NOTE 1: Local PCC or dynamic PCC can be used as described for PLMNs in TS 23.503 [45] and based on operator policy, PDR(s) and FAR(s) can be configured to restrict traffic other than provisioning traffic between PVS/DNS server(s) and UE(s).
NOTE 2: If the UE receives multiple PVS IP addresses and/or PVS FQDNs, how the UE uses this information is up to UE implementation. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.11 UE Mobility support for SNPN | If the UE moves its 3GPP access between SNPN and PLMN, the network selection is performed as specified in TS 23.122 [17] and UE performs initial registration as specified in clause 4.2.2.2.2 of TS 23.502 [3].
NOTE 1: When the UE moves its 3GPP access between SNPN and PLMN, it is up to UE implementation to activate/deactivate SNPN access mode.
If the UE moves its 3GPP access between SNPNs, the network selection is performed as specified in TS 23.122 [17], then the UE performs initial or mobility registration as specified in clause 4.2.2.2.2 of TS 23.502 [3].
NOTE 2: When the UE moves its 3GPP access between SNPNs, it is up to UE implementation whether and when to establish again PDU Sessions using existing mechanism.
If the UE and network supports equivalent SNPNs, the AMF may provide list of equivalent SNPNs to the UE and NG-RAN. The UE may move its 3GPP access to the SNPN in the list of equivalent SNPNs without performing network selection. A UE supporting equivalent SNPNs gets a new registered SNPN ID during the Registration procedure if serving SNPN is changed. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.12 Access to SNPN services via Untrusted non-3GPP access | Access to SNPN services via Untrusted non-3GPP access network follows the specification in the previous 5.30.2 clauses with the differences as specified in this clause.
N3IWF selection is supported as follows:
- When UE registers to SNPN with credentials owned by the SNPN, UE uses the same N3IWF selection procedure as specified for access to stand-alone non-public network services via PLMN in clause 6.3.6.2a.
Emergency services are supported as follows:
- UE initiates N3IWF selection for emergency services when the UE detects a user request for emergency session and determines that Untrusted non-3GPP access is to be used for the emergency access. The UE in SNPN access mode the following:
- If the UE determines that it is located in the same country as the configured N3IWF of the subscribed SNPN, the UE uses the configured N3IWF FQDN for N3IWF selection.
- Otherwise, the UE performs a DNS query using the Visited Country Emergency SNPN FQDN, as specified in clause 28.3.2.2.6.3 of TS 23.003 [19] to determine which SNPNs in the visited country support emergency services in untrusted non-3GPP access via N3IWF; and:
- If the DNS response contains one or more records, the UE selects an SNPN that supports emergency services in untrusted non-3GPP access via N3IWF based on UE implementation specific methods. Each record in the DNS response shall contain the identity of an SNPN (i.e. SNPN ID) in the visited country supporting emergency services in untrusted non-3GPP access via N3IWF.
NOTE 1: Self-assigned NIDs are not supported, since a DNS cannot be properly configured for multiple SNPNs using the same self-assigned NID (i.e. in collision scenarios).
- Once the UE has selected an SNPN, the UE selects an N3IWF for Emergency for the selected SNPN, as specified in TS 23.003 [19].
When an N3IWF has been selected, the UE initiates an Emergency Registration. If the Emergency Registration fails, the UE shall select another SNPN supporting emergency services in untrusted non-3GPP access.
If the DNS response of the Visited Country Emergency SNPN FQDN does not contain any record, or if the DNS response contains one or more records but the UE fails to select an SNPN that supports emergency services in untrusted non-3GPP access, or if the Emergency Registration procedure has failed for all SNPNs supporting emergency services in untrusted non-3GPP access, the UE deactivates the SNPN access mode over NWu and attempts emergency services via PLMN untrusted non-3GPP access, by following the N3IWF selection procedure as defined in clause 6.3.6.4.2.
NOTE 2: If the UE determines that it is located in a different country as the configured N3IWF of the subscribed SNPN, the UE can deactivate the SNPN access mode over NWu and attempts emergency services via PLMN untrusted non-3GPP access, by following the N3IWF selection procedure defined in clause 6.3.6.4.2, without performing a DNS query using the Visited Country Emergency SNPN FQDN.
UE onboarding is supported as follows:
- When UE registers to SNPN over Untrusted non-3GPP access for UE Onboarding, if the UE determines that it is located in the country where the configured N3IWF for onboarding is located, the UE may select the N3IWF in the SNPN which supports UE Onboarding by using the configured N3IWF FQDN used for Onboarding.
- If the UE determines that it is located in a country different from the country where the configured N3IWF for onboarding is located (called the visited country), then in order to determine which SNPNs in the visited country support Untrusted non-3GPP access for UE Onboarding via N3IWF performs a DNS query using the Visited Country FQDN for SNPN N3IWF supporting Onboarding, as specified in clause 28.3.2.2.6.2 of TS 23.003 [19]; and:
- If no DNS response is received, the UE shall stop the N3IWF selection.
- If the DNS response contains one or more records, the UE selects an SNPN that supports Untrusted non-3GPP access for UE Onboarding via N3IWF. Each record in the DNS response shall contain the identity of an SNPN in the visited country supporting Untrusted non-3GPP access for UE Onboarding via N3IWF. In this case:
- The UE shall select an SNPN based on its own implementation means.
If the UE cannot select any N3IWF included in the DNS response, then the UE shall stop the N3IWF selection.
- If the DNS response contains no records, then the UE determines that the visited country does not mandate the selection of an N3IWF that supports Untrusted non-3GPP access for UE Onboarding via N3IWF in this country. In this case the UE uses the configured N3IWF for onboarding.
- If the UE has selected an SNPN for onboarding, the UE constructs the Operator Identifier based Onboarding FQDN for SNPN N3IWF as specified in clause 28.3.2.2.7.2 of TS 23.003 [19], based on the SNPN ID of the selected SNPN and performs a DNS query:
- The DNS response contains the identifier of the N3IWF supporting the onboarding in the SNPN identified by the SNPN ID.
- If the PVS is reachable from the local Untrusted non-3GPP access network (e.g. via the Internet) using the local IP connectivity, UE may connect directly (i.e. without being connected to an N3WIF) with a PVS to obtain the SNPN credentials.
- As part of UE registration via Untrusted non-3GPP access, in Figure 4.12.2.2-1, step 5 of TS 23.502 [3], the UE provides an onboarding indication inside the AN-Parameters. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.13 Access to SNPN services via Trusted non-3GPP access | Access to SNPN services via Trusted non-3GPP access network follows the specification in the previous (sub)clauses of clause 5.30.2 with the differences as specified in this clause.
To access SNPN services via a Trusted non-3GPP access network, the UE follows the procedure for accessing a PLMN via a Trusted non-3GPP access network defined in clause 6.3.12.2 with the following clarifications and additions:
- A non-3GPP access network may advertise (e.g. with ANQP), not only the PLMNs with which 5G connectivity is supported (as specified in clause 6.3.12.2), but also the SNPNs with which 5G connectivity is supported and the related parameters and indications defined in clause 5.30.2.2 (i.e. human-readable network name(s), GIN(s), indication whether access using credentials from a Credentials Holder is supported, indication whether SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN, etc.).
- The UE initiates the access network selection procedure specified in clause 6.3.12.2 and constructs a list of available SNPNs. This list contains the SNPNs advertised by all discovered non-3GPP access networks.
- The UE selects an SNPN that is included in the list of available SNPNs following the procedure in clause 5.30.2.4.
- The UE selects a non-3GPP access network that supports 5G connectivity to the selected SNPN and initiates the registration procedure via Trusted non-3GPP access specified in clause 4.12a.2.2 of TS 23.502 [3] in order to register with the selected SNPN via the selected non-3GPP access network. During the EAP authentication procedure the NAI provided by the UE indicates that 5G connectivity to a specific SNPN is required (e.g. NAI = "<username>@nai.5gc.nid<NID>.mnc<MNC>.mcc<MCC>.3gppnetwork.org").
NOTE: In the case of SNPN ID with self-assigned NID, if the UE, when trying to register with an SNPN ID via TNAN X, is rejected by the AMF with a cause code that temporarily prevents the UE from registering with this SNPN ID, the UE does temporarily not attempt to register with the same SNPN ID, even if the same SNPN ID is advertised via another TNAN.
- If there are multiple non-3GPP access networks that support 5G connectivity to the selected SNPN, then the UE places these non-3GPP access networks in a prioritized list and selects the highest priority non-3GPP access network from this list. To determine the priority of a non-3GPP access network, the UE shall apply the WLANSP rules (if provided) and the procedure specified in clause 6.6.1.3 of TS 23.503 [45], "UE procedure for selecting a WLAN access based on WLANSP rules". If the UE is not provided with WLANSP rules, the UE determines the priority of a non-3GPP access network by using implementation means.
UE onboarding via Trusted non-3GPP access is supported as follows:
- The non-3GPP access network advertises (e.g. via ANQP) an Onboarding enabled indication, as specified in clause 5.30.2.10.2.3.
- The UE selects an SNPN advertising the Onboarding enabled indication following the network selection procedure specified in clause 5.30.2.10.2.5.
- As part of UE registration via Trusted non-3GPP access, in Figure 4.12a.2.2-1, step 5 of TS 23.502 [3] the UE provides an onboarding indication inside the AN-Parameters. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.14 Access to SNPN services via wireline access network | Access to SNPN services via a wireline access network is specified in TS 23.316 [84]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.2.15 Access to SNPN services for N5CW devices | Devices that do not support 5GC NAS signalling over WLAN access (referred to as "Non-5G-Capable over WLAN" devices, or N5CW devices for short), may access 5GC in an SNPN via a trusted WLAN access network that supports a TWIF function. To access SNPN services the N5CW device performs the following procedure:
- A WLAN access network may advertise (e.g. with ANQP), not only the PLMNs with which "5G connectivity-without-NAS" is supported (as specified in clause 6.3.12a.1), but also the SNPNs with which "5G connectivity-without-NAS" is supported, as well as the related parameters and indications defined in clause 5.30.2.2 (i.e. human-readable network name(s), GIN(s), indication whether access using credentials from a Credentials Holder is supported, indication whether SNPN allows registration attempts from UEs that are not explicitly configured to select the SNPN).
- The N5CW device initiates the access network selection procedure by sending an ANQP query to each discovered WLAN access network and constructs a list of available SNPNs with which "5G connectivity-without-NAS" is supported. This list contains the SNPNs with which "5G connectivity-without-NAS" is supported as advertised by all the discovered WLAN access networks.
- The N5CW device selects an SNPN that is included in the list of available SNPNs with which "5G connectivity-without-NAS" is supported following the procedure in clause 5.30.2.4.
- The N5CW device selects a WLAN access network (e.g. an SSID) that supports "5G connectivity-without-NAS" to the selected SNPN and initiates the "Initial Registration and PDU Session Establishment" procedure specified in clause 4.12b.2 of TS 23.502 [3]. If there are multiple WLAN access networks that support "5G connectivity-without-NAS" to the selected SNPN, then the N5CW device selects the highest priority WLAN access network from this list. To determine the priority of a WLAN access network, the N5CW device shall apply the WLANSP rules (if provided) and the procedure specified in clause 6.6.1.3 of TS 23.503 [45], "UE procedure for selecting a WLAN access based on WLANSP rules". If the N5CW device is not provided with WLANSP rules, the N5CW device determines the priority of a WLAN access network by using implementation means.
NOTE: How the N5CW device selects credentials to use for SNPN access is implementation specific. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3 Public Network Integrated NPN | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3.1 General | Public Network Integrated NPNs are NPNs made available via PLMNs e.g. by means of dedicated DNNs, or by one (or more) Network Slice instances allocated for the NPN. The existing network slicing functionalities apply as described in clause 5.15. When a PNI-NPN is made available via a PLMN, then the UE shall have a subscription for the PLMN in order to access PNI-NPN.
NOTE 1: Annex D provides additional consideration to consider when supporting Non-Public Network as a Network Slice of a PLMN.
As network slicing does not enable the possibility to prevent UEs from trying to access the network in areas where the UE is not allowed to use the Network Slice allocated for the NPN, Closed Access Groups may optionally be used to apply access control.
A Closed Access Group identifies a group of subscribers who are permitted to access one or more CAG cells associated to the CAG.
CAG is used for the PNI-NPNs to prevent UE(s), which are not allowed to access the NPN via the associated cell(s), from automatically selecting and accessing the associated CAG cell(s).
NOTE 2: CAG is used for access control e.g. authorization at cell selection and configured in the subscription as part of the Mobility Restrictions i.e. independent from any S-NSSAI. CAG is not used as input to AMF selection nor Network Slice selection. If NPN isolation is desired, operator can better support NPN isolation by deploying network slicing for PNI-NPN, configuring dedicated S-NSSAI(s) for the given NPN as specified in Annex D, clause D.2 and restricting NPN's UE subscriptions to these dedicated S-NSSAI(s).
The UE and PNI-NPN may support remote provisioning of credentials for NSSAA or credentials for secondary authentication/authorization to the UE, as specified in clause 5.39.
NOTE 3: After successful provisioning of the credentials to the UE, specific service subscription data (e.g. to enable the use of PNI-NPN) can be activated in the UE Subscription data in the UDR/UDM. This can result in a change of the UE Subscription Data to include new S-NSSAI, DNN or CAG information, which can trigger update of the UE configurations, e.g. described in clause 5.15.5.2.2.
NOTE 4: The UE always has subscription to the HPLMN providing the PNI-NPN and has a USIM that contains primary authentication credentials.
Support for Proximity based Services (ProSe) in conjunction with CAG is specified in TS 23.304 [128]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3.2 Identifiers | The following is required for identification:
- A CAG is identified by a CAG Identifier which is unique within the scope of a PLMN ID;
- A CAG cell broadcasts one or multiple CAG Identifiers per PLMN;
NOTE 1: It is assumed that a cell supports broadcasting a total of twelve CAG Identifiers. Further details are defined in TS 38.331 [28].
- A CAG cell may in addition broadcast a human-readable network name per CAG Identifier:
NOTE 2: The human-readable network name per CAG Identifier is only used for presentation to user when user requests a manual CAG selection. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3.3 UE configuration, subscription aspects and storage | To use CAG, the UE, that supports CAG as indicated as part of the UE 5GMM Core Network Capability, may be pre-configured or (re)configured with the following CAG information, included in the subscription as part of the Mobility Restrictions:
- an Allowed CAG list i.e. a list of CAG Identifiers the UE is allowed to access; and
- each entry of the Allowed CAG list may be associated with time validity information containing one or more time periods; and
- optionally, a CAG-only indication whether the UE is only allowed to access 5GS via CAG cells (see TS 38.304 [50] for how the UE identifies whether a cell is a CAG cell);
The HPLMN may configure or re-configure a UE with the above CAG information using the UE Configuration Update procedure for access and mobility management related parameters described in clause 4.2.4.2 of TS 23.502 [3].
The above CAG information is provided by the HPLMN on a per PLMN basis. In a PLMN the UE shall only consider the CAG information provided for this PLMN. The entries of the Allowed CAG list with time validity information are provided to the UE only if the UE indicates support of CAG with validity information.
NOTE 1: CAG information provisioning by an authorized administrator introduced in clause 5.50.3 and clause 4.15.6.3h of TS 23.502 [3] can be leveraged to provide/update CAG information.
NOTE 2: If the UE supports CAG but not CAG with validity information and there are entries of the Allowed CAG list that are associated with time validity information in the subscription data, the CAG Identifier of the corresponding entry in subscription data can be provided to the UE without time validity information when the validity condition is evaluated as true and removed when the evaluation changes to false. It is up to AMF local policy whether to provide such CAG Identifier to the UE. In case the AMF does not support CAG with validity information e.g. in the case of roaming, the UDM provides CAG information to the AMF without entries including time validity information.
When the subscribed CAG information changes, UDM sets a CAG information Subscription Change Indication and sends it to the AMF. The AMF shall provide the UE with the CAG information when the UDM indicates that the CAG information within the Access and Mobility Subscription data has been changed. When AMF receives the indication from the UDM that the CAG information within the Access and Mobility Subscription has changed, the AMF uses the CAG information received from the UDM to update the UE. Once the AMF updates the UE and obtains an acknowledgment from the UE, the AMF informs the UDM that the update was successful and the UDM clears the CAG information Subscription Change Indication flag.
The AMF may update the UE using either the UE Configuration Update procedure after registration procedure is completed, or by including the new CAG information in the Registration Accept or in the Registration Reject or in the Deregistration Request or in the Service Reject.
When the UE is roaming and the Serving PLMN provides CAG information, the UE shall update only the CAG information provided for the Serving PLMN while the stored CAG information for other PLMNs are not updated. When the UE is not roaming and the HPLMN provides CAG information, the UE shall update the CAG information stored in the UE with the received CAG information for all the PLMNs.
The UE shall store the latest available CAG information for every PLMN for which it is provided and keep it stored when the UE is de-registered or switched off, as described in TS 24.501 [47].
The CAG information is only applicable with 5GS.
NOTE 3: CAG information has no implication on whether and how the UE accesses 5GS over non-3GPP access. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3.4 Network and cell (re-)selection and access control | The following is assumed for network and cell selection and access control:
- The CAG cell shall broadcast information such that only UEs supporting CAG are accessing the cell (see TS 38.300 [27], TS 38.304 [50]);
NOTE 1: The above also implies that cells are either CAG cells or normal PLMN cells. For network sharing scenario between SNPN, PNI-NPN and PLMNs, please see clause 5.18.
- In order to prevent access to NPNs for authorized UE(s) in the case of network congestion/overload, existing mechanisms defined for Control Plane load control, congestion and overload control in clause 5.19 can be used, as well as the access control and barring functionality described in clause 5.2.5, or Unified Access Control using the access categories as defined in TS 24.501 [47] can be used.
- For aspects of automatic and manual network selection in relation to CAG, see TS 23.122 [17];
- For aspects related to cell (re-)selection, see TS 38.304 [50];
- If the UE is accessing a CAG cell and the corresponding entry of the Allowed CAG list configured on the UE is associated with time validity information, the UE may trigger cell reselection and/or network selection procedure if the evaluation of the time validity information changes.
- The Mobility Restrictions shall be able to restrict the UE's mobility according to the Allowed CAG list (if configured in the subscription) and include an indication whether the UE is only allowed to access 5GS via CAG cells (if configured in the subscription) as described in clause 5.30.3.3;
- The AMF shall update the Allowed CAG list in the Mobility Restrictions towards NG-RAN if the evaluation of the time validity information of an entry in the Allowed CAG list changes between true and false, unless the AMF releases the NAS signalling connection to the UE based on operator's policy if the evaluation of the validity condition changes from true to false.
- During transition from CM-IDLE to CM-CONNECTED and during Registration after connected mode mobility from E-UTRAN to NG-RAN as described in clause 4.11.1.2.2 of TS 23.502 [3]:
- The AMF shall verify whether UE access is allowed by Mobility Restrictions:
NOTE 2: It is assumed that the AMF is made aware of the supported CAG Identifier(s) of the CAG cell by the NG-RAN.
- If the UE is accessing the 5GS via a CAG cell and if at least one of the CAG Identifier(s) received from the NG-RAN is part of the UE's Allowed CAG list (for entries with time validity information if any, the evaluation of the condition is true), then the AMF accepts the NAS request;
- If the UE is accessing the 5GS via a CAG cell and if none of the CAG Identifier(s) received from the NG-RAN are part of the UE's Allowed CAG list (for entries with time validity information if any, the evaluation of the condition is true), then the AMF rejects the NAS request and the AMF should include CAG information in the NAS reject message. The AMF shall then release the NAS signalling connection for the UE by triggering the AN release procedure; and
- If the UE is accessing the 5GS via a non-CAG cell and the UE's subscription contains an indication that the UE is only allowed to access CAG cells, then the AMF rejects the NAS request and the AMF should include CAG information in the NAS reject message. The AMF shall then release the NAS signalling connection for the UE by triggering the AN release procedure.
- During transition from RRC_INACTIVE to RRC_CONNECTED state:
- When the UE initiates the RRC Resume procedure for RRC_INACTIVE to RRC_CONNECTED state transition in a CAG cell, NG-RAN shall reject the RRC Resume request from the UE if none of the CAG Identifiers supported by the CAG cell are part of the UE's Allowed CAG list according to the Mobility Restrictions received from the AMF or if no Allowed CAG list has been received from the AMF.
- When the UE initiates the RRC Resume procedure for RRC_INACTIVE to RRC_CONNECTED state transition in a non-CAG cell, NG-RAN shall reject the UE's Resume request if the UE is only allowed to access CAG cells according to the Mobility Restrictions received from the AMF.
- During connected mode mobility procedures within NG-RAN, i.e. handover procedures as described in clause 4.9.1 of TS 23.502 [3]:
- Source NG-RAN shall not handover the UE to a target NG-RAN node if the target is a CAG cell and none of the CAG Identifiers supported by the CAG cell are part of the UE's Allowed CAG list in the Mobility Restriction List or if no Allowed CAG list has been received from the AMF;
- Source NG-RAN shall not handover the UE to a non-CAG cell if the UE is only allowed to access CAG cells based on the Mobility Restriction List;
- If the target cell is a CAG cell, target NG-RAN shall reject the N2 based handover procedure if none of the CAG Identifiers supported by the CAG cell are part of the UE's Allowed CAG list in the Mobility Restriction List or if no Allowed CAG list has been received from the AMF;
- If the target cell is a non-CAG cell, target NG-RAN shall reject the N2 based handover procedure if the UE is only allowed to access CAG cells based on the Mobility Restriction List.
- Update of Mobility Restrictions:
- When the AMF receives the Nudm_SDM_Notification from the UDM and the AMF determines that the Allowed CAG list or the indication whether the UE is only allowed to access CAG cells have changed;
- The AMF shall update the Mobility Restrictions in the UE and NG-RAN accordingly under the conditions as described in clause 4.2.4.2 of TS 23.502 [3].
NOTE 3: When the UE is accessing the network for emergency services the conditions for AMF in clause 5.16.4.3 apply. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.30.3.5 Support of emergency services in CAG cells | Emergency Services are supported in CAG cells, for UEs supporting CAG, whether normally registered or emergency registered as described in clause 5.16.4 and in clause 4.13.4 of TS 23.502 [3].
A UE may camp on an acceptable CAG cell in limited service state as specified in TS 23.122 [17] and TS 38.304 [50], based on operator policy defined in TS 38.300 [27].
NOTE: Support for Emergency services requires each cell with a Cell Identity associated with PLMNs or PNI-NPNs to only be connected to AMFs that supports emergency services.
The UE shall select a PLMN (of a CAG cell or non-CAG cell), as described in TS 23.122 [17] and TS 23.167 [18], when initiating emergency services from limited service state.
During handover to a CAG cell, if the UE is not authorized to access the target CAG cell as described in clause 5.30.3.4 and has emergency services, the target NG-RAN node only accepts the emergency PDU Session and the target AMF releases the non-emergency PDU Sessions that were not accepted by the NG-RAN node. Upon completion of handover the UE behave as emergency registered. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31 Support for Cellular IoT | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.1 General | This clause provides an overview about 5GS optimisations and functionality for support of Cellular Internet-of-Things (Cellular IoT, or CIoT) according to service requirements described in TS 22.261 [2]. Cellular IoT is in earlier 3GPP releases also referred to as Machine Type Communication (MTC) (see clause 4.3.17 of TS 23.401 [26]). The specific functionality is described in the affected procedures and features of this specification, in TS 23.502 [3], TS 23.503 [45] and other specifications.
In this Release Control Plane CIoT 5GS Optimisations (clause 5.31.4) and User Plane CIoT 5GS Optimisations (clause 5.31.18) are only supported over E-UTRA and these CIoT 5GS optimisations are not supported over Non-3GPP RAT type accesses.
CIoT functionality is provided by the visited and home networks when the networks are configured to support CIoT. It applies to both the non-roaming case and the roaming case and some functionality may be dependent upon the existence of appropriate roaming agreements between the operators.
Some of the CIoT functions are controlled by subscriber data. Other CIoT functions are based on indicators sent by the UE to the network. CIoT functionality is performed by UEs that are configured to support different options as described in clause 5.31.2
Though motivated by scenarios and use cases defined in TS 22.261 [2], the functions added to support CIoT have general applicability and are in no way constrained to any specific scenario, use case or UE types, except where explicitly stated.
In the context of CIoT the term AF denotes an SCS/AS as defined TS 23.682 [36]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.2 Preferred and Supported Network Behaviour | At registration, a UE includes its 5G Preferred Network Behaviour indicating the network behaviour the UE can support and what it would prefer to use.
NOTE: If the UE supports S1-mode then the UE will indicate the supported EPS Network Behaviour Information in the S1 UE network capability IE.
The 5G Preferred Network Behaviour signalled by the UE includes the following information in the 5GMM Capability IE:
- Whether Control Plane CIoT 5GS Optimisation is supported.
- Whether User Plane CIoT 5GS Optimisation is supported.
- Whether N3 data transfer is supported.
- Whether header compression for Control Plane CIoT 5GS Optimisation is supported.
And the following 5G Preferred Network Behaviour in other IEs:
- Whether Control Plane CIoT 5GS Optimisation or User Plane CIoT 5GS Optimisation is preferred.
If N3 data transfer is supported is indicated by the UE, the UE supports data transfer that is not subject to CIoT 5GS Optimisations. If the UE indicates support of User Plane CIoT 5GS Optimisation then it shall also indicate support of N3 data transfer.
The AMF indicates the network behaviour the network accepts in the 5G Supported Network Behaviour information. This indication is per Registered Area. The AMF may indicate one or more of the following:
- Whether Control Plane CIoT 5GS Optimisation is supported.
- Whether User Plane CIoT 5GS Optimisation is supported.
- Whether N3 data transfer is supported.
- Whether header compression for Control Plane CIoT 5GS Optimisation is supported.
If the AMF indicates support of User Plane CIoT 5GS Optimisation then it shall also indicate support of N3 data transfer. If the UE and AMF indicate support for User Plane CIoT 5GS Optimisation, the AMF indicates support of User Plane CIoT 5GS Optimisation support for the UE to NG-RAN.
For NB-IoT UEs that only support Control Plane CIoT 5GS Optimisation, the AMF shall include support for Control Plane CIoT 5GS Optimisation in the Registration Accept message.
A UE that supports the NB-IoT shall always indicate support for Control Plane CIoT 5GS Optimisation.
A UE that supports WB-E-UTRA shall always indicate support for N3 data transfer.
The 5G Preferred Network Behaviour indication from the UE may be used to influence policy decisions that can cause rerouting of the Registration Request from an AMF to another AMF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.3 Selection, steering and redirection between EPS and 5GS | The UE selects the core network type (EPC or 5GC) based on the broadcast indications for both EPC and 5GC and the UE's EPC and 5GC Preferred Network Behaviour. Networks that support NB-IoT shall broadcast an indication whether N3 data transfer is supported or not in system information.
When the UE performs the registration procedure it includes its Preferred Network Behaviour (for 5G and EPC) in the Registration Request message and the AMF replies with the 5G Supported Network Behaviour in the Registration Accept message.
If the UE supports any of the CIoT 5GS Optimisations included in 5GC Preferred Network Behaviour, then when the UE performs an Attach or TAU procedure and the UE includes its EPC Preferred Network Behaviour then the UE shall also include its 5GC Preferred Network Behaviour.
In networks that support CIoT features in both EPC and 5GC, the operator may steer UEs from a specific CN type due to operator policy, e.g. due to roaming agreements, Preferred and Supported Network Behaviour, load redistribution, etc. Operator policies in EPC and 5GC are assumed to avoid steering UEs back and forth between EPC and 5GC.
To redirect a UE from 5GC to EPC, when the UE sends a Registration Request or Service Request, the AMF sends a Registration Reject or Service Reject with an EMM cause value indicating that the UE should not use 5GC. The UE disables N1 mode and re-enables S1 mode, if it was disabled. The UE then performs either an Attach or TAU in EPC as described in clause 5.17.2.
To redirect a UE from EPC to 5GC, when the UE requests an Attach or TAU procedure or Service Reject, the MME sends a reject message with an EMM cause indicating the UE should not use EPC. The UE disables S1 mode and re-enables N1 mode, if it was disabled. The UE then registers with 5GC as described in clause 5.17.2.
When determining whether to redirect the UE, the AMF/MME takes into account the UE support of S1/N1 mode, respectively and the UE's Preferred Network Behaviour and the Supported Network Behaviour of the network the UE is being redirected towards.
When determining to redirect the UE in 5GMM-CONNECTED mode to EPC, the AMF shall initiate the UE Configuration Update procedure to indicate registration requested and release of the N1 NAS signalling connection not requested, then the AMF redirects the UE to EPC by rejecting the subsequent Registration Request, see TS 24.501 [47].
If after redirection the UE cannot find a cell supporting connectivity, the UE may re-enable the disabled N1/S1 mode and then perform Registration, Attach or TAU. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.4 Control Plane CIoT 5GS Optimisation | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.4.1 General | The Control Plane CIoT 5GS Optimisation is used to exchange user data between the UE and the SMF as payload of a NAS message in both uplink and downlink directions, avoiding the establishment of a user plane connection for the PDU Session. The UE and the AMF perform integrity protection and ciphering for the user data by using NAS PDU integrity protection and ciphering. For IP and Ethernet data, the UE and the SMF may negotiate and perform header compression.
NOTE: In the context of Control Plane CIoT 5GS Optimisation, established or activated user plane resources/connection refers to radio user plane resources/connection i.e Data Radio Bearer and N3 tunnel.
UE and AMF negotiate support and use of Control Plane CIoT 5GS Optimisation as defined in clause 5.31.2. When the Control Plane CIoT 5GS Optimisation feature is used and the PDU Session Type is unstructured, the SMF selects either NEF or UPF based on information in the UE's subscription.
If UE and network have negotiated support and use of Control Plane CIoT 5GS Optimisation then the following paragraphs of this clause apply.
During the PDU Session Establishment procedure the AMF indicates to the SMF that Control Plane CIoT 5GS Optimisation is available for data transmission.
During the PDU Session Establishment procedure the AMF also determines based on Preferred and Supported Network Behaviour (see clause 5.31.2), subscription data, other already established PDU Sessions and local policy whether a new PDU Session shall only use the Control Plane CIoT 5GS Optimisation (i.e. that a user-plane connection shall never be established for the new PDU Session). If a PDU Session shall only use Control Plane CIoT 5GS Optimisation, the AMF provides a Control Plane Only Indicator to the SMF during the PDU Session Establishment. The SMF provides the Control Plane Only Indicator in the Session Management Request to the UE. A UE and SMF receiving the Control Plane Only Indicator for a PDU Session shall always use the Control Plane CIoT 5GS Optimisation for this PDU Session.
The following rules apply for the use of the Control Plane Only Indicator during PDU Session Establishment:
- If N3 data transfer was not successfully negotiated, all PDU Sessions shall include Control Plane Only Indicator.
- If N3 data transfer was successfully negotiated then:
- For a new PDU Session for a DNN/S-NSSAI for which the subscription data for SMF Selection includes an Invoke NEF indication (i.e. for a PDU Session which will be anchored in NEF), the AMF shall always include the Control Plane Only Indicator.
- For a new PDU Session for a DNN/S-NSSAI for which the subscription data for SMF Selection does not include an Invoke NEF indication (i.e. for a PDU Session which will be anchored in UPF) and that supports interworking with EPS based on the subscription data defined in TS 23.502 [3]:
- for the first PDU Session the AMF determines based on local policy whether to include the Control Plane Only Indicator or not;
- if the AMF previously included a Control Plane Only Indicator for PDU Sessions that support interworking with EPS based on the subscription data defined in TS 23.502 [3] and that are anchored in UPF, the AMF shall include it also for the new PDU Session;
- if the AMF previously did not include a Control Plane Only Indicator for any of the PDU Sessions that support interworking with EPS based on the subscription data defined in TS 23.502 [3] and that are anchored in UPF, the AMF shall not include it for the new PDU Session.
- For a new PDU Session for a DNN/S-NSSAI for which the subscription data for SMF Selection does not include an Invoke NEF indication (i.e. for a PDU Session which will be anchored in UPF) and that does not support interworking with EPS based on the subscription data defined in TS 23.502 [3], AMF determines individually per PDU Session whether to include the Control Plane Only Indicator or not.
As described in clause 5.31.4.2, if UE and AMF successfully negotiate N3 data transfer in addition to Control Plane CIoT 5GS Optimisation, the UE or SMF may request to establish N3 data transfer for one or more PDU Sessions for which Control Plane Only Indicator was not received. In CM-CONNECTED, the UE and the network use N3 delivery for PDU Sessions for which user plane resources are established and uses NAS for data transmission for PDU Sessions for which user plane resources are not established.
If the AMF determines that Control Plane Only indication associated with PDU Session is not applicable any longer due to e.g. change of Preferred and Supported Network Behaviour, subscription data and local policy, the AMF should request the SMF to release the PDU Session as specified in clause 4.3.4.2 or clause 4.3.4.3 of TS 23.502 [3].
Early Data Transmission may be initiated by the UE for mobile originated Control Plane CIoT 5GS Optimisation when the RAT Type is E-UTRA.
The QoS model as defined in clause 5.7 is not supported for PDU Sessions using Control Plane CIoT 5GS Optimisation as user plane resources are not established for those PDU Sessions. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.4.2 Establishment of N3 data transfer during Data Transport in Control Plane CIoT 5GS Optimisation | If UE and AMF have successfully negotiated N3 data transfer in addition to Control Plane CIoT 5GS Optimisation based on the Preferred and Supported Network Behaviour as defined in clause 5.31.2, then the SMF may decide to establish N3 data transfer for any PDU session for which Control Plane Only Indicator was not included based on local SMF decision e.g. based on the amount of data transferred in UL or DL using Control Plane CIoT 5GS Optimisation. In that case, the SMF initiates the SMF-triggered N3 data transfer establishment procedure as described in clause 4.2.10.2 of TS 23.502 [3].
If UE and AMF successfully negotiate N3 data transfer in addition to Control Plane CIoT 5GS Optimisation based on the Preferred and Supported Network Behaviour as defined in clause 5.31.2, then the UE may decide to establish N3 data transfer for any PDU session for which Control Plane Only Indicator was not included based on local decision, e.g. based on the amount of data to be transferred. In that case, the UE performs the UE triggered N3 data transfer establishment procedure as described in clause 4.2.10.1 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.4.3 Control Plane Relocation Indication procedure | For intra-NB-IoT mobility when UE and AMF are using Control Plane CIoT 5GS Optimisation, the CP Relocation Indication procedures may be used. The purpose of the CP Relocation Indication procedure is to request the AMF to authenticate the UE's re-establishment request (see TS 33.501 [29]) and initiate the establishment of the UE's N2 connection after the UE has initiated an RRC Re-Establishment procedure in a new NG-RAN node (see TS 38.300 [27]).
The RRC Re-Establishment procedure uses the Truncated 5G-S-TMSI as the UE identifier. The NG-RAN is configured with the sizes of the components of the Truncated 5G-S-TMSI and it is configured with how to recreate the AMF Set ID, the AMF Pointer and 5G-TMSI from the equivalent truncated parameters (see TS 23.003 [19]).
The AMF configures the UE with the Truncated 5G-S-TMSI Configuration that provides the sizes of the components of the Truncated 5G-S-TMSI as described in TS 24.501 [47] during the Registration. The configuration of these parameters are specific to each PLMN.
NOTE: Network sharing default configuration of the sizes of the truncated components is described in TS 23.003 [19]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.5 Non-IP Data Delivery (NIDD) | Functions for NIDD may be used to handle Mobile Originated (MO) and Mobile Terminated (MT) communication for unstructured data (also referred to as Non-IP). Such delivery to the AF is accomplished by one of the following two mechanisms:
- Delivery using the NIDD API;
- Delivery using UPF via a Point-to-Point (PtP) N6 tunnel.
NIDD is handled using an Unstructured PDU session to the NEF. The UE may obtain an Unstructured PDU session to the NEF during the PDU Session Establishment procedure. Whether or not the NIDD API shall be invoked for a PDU session is determined by the presence of a "NEF Identity for NIDD" for the DNN/S-NSSAI combination in the subscription. If the subscription includes a "NEF Identity for NIDD" corresponding with the DNN and S-NSSAI information, then the SMF selects that NEF and uses the NIDD API for that PDU session.
The NEF exposes the NIDD APIs described in TS 23.502 [3] on the N33/Nnef reference point.
The NEF uses the provisioned policies to map an AF Identifier and UE Identity to a DNN/S-NSSAI combination if the Reliable Data Service (RDS) is not enabled. If RDS is enabled, the NEF determines the association based on RDS port numbers and the provisioned policies that may be used to map AF Identifier and User identity to a DNN.
The NEF also supports distribution of Mobile Terminated messages to a group of UEs based on the NIDD API. If an External Group Identifier is included in the MT NIDD request, the NEF uses the UDM to resolve the External Group Identifier to a list of SUPIs and sends the message to each UE in the group with an established PDU Session.
The Protocol Configuration Options (PCO) may be used to transfer NIDD parameters to and from the UE (e.g. maximum packet size). The PCO is sent in the 5GSM signalling between UE and SMF. NIDD parameters are sent to and from the NEF via the N29 interface. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.6 Reliable Data Service | The Reliable Data Service (RDS) may be used between the UE and NEF or UPF when using a PDU Session of PDU Type 'Unstructured'. The service provides a mechanism for the NEF or UPF to determine if the data was successfully delivered to the UE and for the UE to determine if the data was successfully delivered to the NEF or UPF. When a requested acknowledgement is not received, the Reliable Data Service retransmits the packet. The service is enabled or disabled based on DNN and NSSAI Configuration per SLA.
When the service is enabled, a protocol is used between the end-points of the unstructured PDU Session. The protocol uses a packet header to identify if the packet requires no acknowledgement, requires an acknowledgement, or is an acknowledgment and to allow detection and elimination of duplicate PDUs at the receiving endpoint. RDS supports both single and multiple applications within the UE. Port Numbers in the header are used to identify the application on the originator and to identify the application on the receiver. The UE, NEF and the UPF may support reservation of the source and destination port numbers for their use and subsequent release of the reserved port numbers. Reliable Data Service protocol (as defined in TS 24.250 [80]) also enables applications to query their peer entities to determine which port numbers are reserved and which are available for use at any given time. The header is configured based on Reliable Data Service Configuration information which is obtained in the NIDD configuration, MT NIDD and MO NIDD procedures with the AF as specified in TS 23.502 [3].
During NIDD Configuration, the AF may indicate which serialization formats it supports for mobile originated and mobile terminated traffic in the Reliable Data Server Configuration. When port numbers are reserved by the UE, the serialization format that will be used by the application may be indicated to the NEF. When port numbers are reserved by the NEF, the serialization format that will be used by the application may be indicated to the UE. If the receiver does not support the indicated serialization format, it rejects the port number reservation request and the sender may re-attempt to reserve the port number with a different serialization format. If, during NIDD Configuration, the AF indicated that it supports multiple serialization formats, the NEF determines the serialization format that it will indicate to the UE based on local policies and previous negotiations with the UE (e.g. the NEF may indicate the same serialization format that was indicated by the UE or avoid indicating a serialization format that was previously rejected by the UE). When serialization formats are configured for reserved port numbers, the NEF stores the serialization formats as part of the Reliable Data Service Configuration and provides the updated Reliable Data Service Configuration to the AF.
NOTE: Whether the UE Application or AF supports a given serialization format is outside the scope of 3GPP specifications.
The UE indicates its capability of supporting RDS in the Protocol Configuration Options (PCO) and the SMF negotiates RDS support with the NEF or UPF. If the NEF or UPF supports and accepts RDS then the SMF indicates to the UE, in the PCO, that the RDS shall be used if enabled in the DNN and NSSAI configuration.
In order to prevent situations where an RDS instance needs to interface to both the user and control plane, RDS may only be used with PDU Sessions for which the "Control Plane CIoT 5GS Optimisation" indication is set or with PDU sessions using the Control Plane CIoT 5GS Optimisation when the AMF does not move the PDU session to the user plane.
Reliable Data Service protocol is defined in TS 24.250 [80]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7 Power Saving Enhancements | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.1 General | To enable UE power saving and to enhance MT reachability while using MICO mode, e.g. for CIoT, the following features are specified in the following clauses:
- Extended Discontinuous Reception (DRX) for CM-IDLE and CM-CONNECTED with RRC_INACTIVE;
- MICO mode with Extended Connected Time;
- MICO mode with Active Time;
- MICO mode and Periodic Registration Timer Control.
If a UE requests via NAS to enable both MICO mode with Active Time and extended idle mode DRX, e.g. based on local configuration, Expected UE Behaviour, if available, UE requested Active Time value, UE subscription information and network policies etc, the AMF may decide to enable MICO mode with or without Active Time, extended idle mode DRX or both.
The functions and procedures to enable a UE using power saving functions to receive MBS service are defined in TS 23.247 [129]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.2 Extended Discontinuous Reception (DRX) for CM-IDLE and CM-CONNECTED with RRC-INACTIVE | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.2.1 Overview | The UE and the network may negotiate over non-access stratum signalling the use of extended idle mode DRX for reducing its power consumption, while being available for mobile terminating data and/or network originated procedures within a certain delay dependent on the DRX cycle value. Extended DRX in CM-IDLE is supported for E-UTRA and NR connected to 5GC. Extended DRX in CM-CONNECTED with RRC_INACTIVE mode is supported for WB-E-UTRA, LTE-M and NR connected to 5GC. RRC_INACTIVE is not supported by NB-IoT connected to 5GC.
The negotiation of the eDRX parameters for NR, WB-E-UTRA and LTE-M is supported over any RAT.
Applications that want to use extended idle mode DRX need to consider specific handling of mobile terminating services or data transfers and in particular they need to consider the delay tolerance of mobile terminated data. A network side application may send mobile terminated data, an SMS, or a device trigger and needs to be aware that extended idle mode DRX may be in place. A UE should request for extended idle mode DRX only when all expected mobile terminating communication is tolerant to delay.
NOTE 1: The extended idle mode DRX cycle length requested by UE takes into account requirements of applications running on the UE. Subscription based determination of eDRX cycle length can be used in those rare scenarios when applications on UE cannot be modified to request appropriate extended idle mode DRX cycle length. The network accepting extended DRX while providing an extended idle mode DRX cycle length value longer than the one requested by the UE, can adversely impact reachability requirements of applications running on the UE.
UE and NW negotiate the use of extended idle mode DRX as follows:
If the UE decides to request for extended idle mode DRX, the UE includes an extended idle mode DRX parameters information element in the Registration Request message. The UE may also include the UE specific DRX parameters information element for regular idle mode DRX according to clause 5.4.5. The extended DRX parameters information element includes the extended idle mode DRX cycle length.
The AMF decides whether to accept or reject the UE request for enabling extended idle mode DRX. If the AMF accepts the extended idle mode DRX, the AMF based on operator policies and, if available, the extended idle mode DRX cycle length value in the subscription data from the UDM, may also provide different values of the extended idle mode DRX parameters than what was requested by the UE. The AMF taking into account the RAT specific Subscribed Paging Time Window, the UE's current RAT and local policy also assigns a Paging Time Window length to be used and provides this value to the UE during Registration Update procedures together with the extended idle mode DRX cycle length in the extended DRX parameter information element. If the AMF accepts the use of extended idle mode DRX, the UE shall apply extended idle mode DRX based on the received extended idle mode DRX length, the UE's current RAT (NR, NB-IoT, WB-E-UTRA or LTE-M) and RAT specific Paging Time Window length. If the UE does not receive the extended DRX parameters information element in the relevant accept message because the AMF rejected its request or because the request was received by AMF not supporting extended idle mode DRX, the UE shall apply its regular discontinuous reception as defined in clause 5.4.5. For NR, Paging Time Window applies for extended DRX lengths greater than 10.24s as defined in TS 38.304 [50]. For WB-E-UTRA, Paging Time Window applies for extended DRX lengths of 10.24s and greater as defined in TS 36.304 [52].
When the UE is accessing NR, if the AMF provides an extended idle mode DRX cycle length value of 10.24s and the registration area of the UE contains only NR cells, the AMF does not include a Paging Time Window. If the AMF provides an extended idle mode DRX cycle length value of 10.24s and the registration area of the UE contains E-UTRA cells and NR cells if the UE supports both E-UTRA and NR, the AMF includes a Paging Time Window.
For WB-E-UTRA and LTE-M the eNB broadcasts an indicator for support of extended idle mode DRX in 5GC in addition to the existing indicator for support of extended idle mode DRX in EPC as defined in TS 36.331 [51]. For NR the gNB broadcasts an indicator for support of extended idle mode DRX as defined in TS 38.331 [28]. This indicator is used by the UE in CM-IDLE state.
NOTE 2: A broadcast indicator for support of extended idle mode DRX is not needed for NB-IoT as it is always supported in NB-IoT.
The specific negotiation procedure handling is described in TS 23.502 [3].
NOTE 3: If the Periodic Registration Update timer assigned to the UE is not longer than the extended idle mode DRX cycle the power savings are not maximised.
For RAT types that support extended DRX for CM-CONNECTED with RRC_INACTIVE state, the AMF passes the UE's accepted idle mode eDRX values to NG-RAN. If the UE supports eDRX in RRC_INACTIVE, based on its UE radio capabilities, NG-RAN configures the UE with an eDRX cycle in RRC_INACTIVE as specified in TS 38.300 [27] up to the value for the UE's idle mode eDRX cycle as provided by the AMF in "RRC Inactive Assistance Information" as defined in clause 5.3.3.2.5.
If an eDRX cycle is applied in RRC_INACTIVE, the RAN can buffer DL packets up to the duration of the eDRX cycle chosen by NG-RAN if the eDRX cycle does not last more than 10.24 seconds. If the CN based MT communication handling support indication is received in RRC Inactive Assistance Information, the NG-RAN may select an eDRX cycle that lasts more than 10.24s. In this case, based on implementation the NG-RAN may send an indication in N2 message that the UE is transitioning to RRC_INACTIVE state and the NG-RAN determined eDRX values (i.e. the eDRX cycle length and the Paging Time Window length) for RRC_INACTIVE to the AMF. The CN takes the indication in the N2 message into account, then handles mobile terminated (MT) communication as specified in clause 5.31.7.2.4 and it can apply high latency communication as specified in clause 5.31.8. The AMF replies to NG-RAN that the indication in the N2 message has been taken into account and the MT signalling or data may be buffered by the Core Network based on high latency communication. If and when the NG-RAN chooses to send the indication is up to NG-RAN implementation. If the NG-RAN delays sending the indication and it receives a DL NAS message for the UE, the NG-RAN proceeds as described in clause 4.8.1.1a of TS 23.502 [3].
NOTE 4: If the indication that the UE is transitioning to RRC_INACTIVE state is not sent (or sent after UE has entered RRC_INACTIVE state) by the NG-RAN then until CN receives it the CN cannot apply the high latency communication functionality, other NFs will not be aware of the UE reachability, certain high latency communication related services provided to the AF via NEF would not be available, NAS message delivery might fail and downlink data in RAN might be lost.
NOTE 5: The CN based MT communication handling support indication in RRC Inactive Assistance Information is provided when all entities (e.g. AMF, SMF and UPF) involved in the CN support corresponding functionalities (including the support providing buffered downlink data size) based on deployment and configuration.
When the UE has PDU Session associated with emergency services, the UE and AMF follow regular discontinuous reception as defined in clause 5.4.5 and shall not use the extended idle mode DRX. Extended idle mode DRX parameters may be negotiated while the UE has PDU Session associated with emergency services. When the PDU Session associated with emergency services is released, the UE and AMF shall reuse the negotiated extended idle mode DRX parameters in the last Registration Update procedure.
The UE shall include the extended DRX parameters information element in each Registration Request message if it still wants to use extended idle mode DRX. At AMF to AMF, AMF to MME and MME to AMF mobility, the extended idle mode DRX parameters are not sent from the old CN node to the new CN node as part of the MM context information. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.2.2 Paging for extended idle mode DRX in E-UTRA and NR connected to 5GC | 5.31.7.2.2.0 General
For WB-E-UTRA and LTE-M connected to 5GC, the extended idle mode DRX value range will consist of values starting from 5.12s (i.e. 5.12s, 10.24s, 20.48s, etc.) up to a maximum of 2621.44s (almost 44 min). For NB-IoT, the extended idle mode DRX value range will start from 20.48s (i.e. 20.48s, 40.96s, 81.92, etc.) up to a maximum of 10485.76s (almost 3 hours) (see TS 36.304 [52]). For NR, the extended idle mode DRX value range will consist of values starting from 2.56s (i.e. 2.56s, 5.12s, 10.24s, 20.48s, etc.) up to a maximum of 10485.76s (almost 3 hours) (see TS 38.304 [50]). The extended idle mode DRX cycle length is negotiated via NAS signalling. The AMF includes the extended idle mode DRX cycle length for NR, WB-E-UTRA, LTE-M or NB-IoT in paging message to assist the NG-RAN node in paging the UE. For NR, Paging Time Window applies for extended DRX lengths longer than 10.24s as defined in TS 38.304 [50]. For WB-E-UTRA, LTE-M and NB-IoT, Paging Time Window applies for extended DRX lengths of 10.24s and longer as defined in TS 36.304 [52].
The network follows the regular paging strategy as defined in clause 5.4.5 when the extended idle mode DRX cycle length is 5.12s or less for WB-E-UTRA, LTE-M and NB-IoT, or 10.24s or less for NR.
Clauses 5.31.7.2.2.1, 5.31.7.2.2.2 and 5.31.7.2.2.3 apply when the extended idle mode DRX cycle length is 10.24s or longer for WB-E-UTRA, LTE-M and NB-IoT, or longer than 10.24s for NR.
5.31.7.2.2.1 Hyper SFN, Paging Hyperframe and Paging Time Window length
A Hyper-SFN (H-SFN) frame structure is defined on top of the SFN used for regular idle mode DRX. Each H-SFN value corresponds to a cycle of the legacy SFN of 1024 radio frames, i.e. 10.24s. When extended idle mode DRX is enabled for a UE, the UE is reachable for paging in specific Paging Hyperframes (PH), which is a specific set of H-SFN values. The PH computation is a formula that is function of the extended idle mode DRX cycle and a UE specific identifier, as described in TS 36.304 [52] and TS 38.304 [50]. This value can be computed at all UEs and AMFs without need for signalling. The AMF includes the extended idle mode DRX cycle length and the PTW length in paging message to assist the NG-RAN nodes in paging the UE.
The AMF also assigns a Paging Time Window length and provides this value to the UE during Registration Update procedures together with the extended idle mode DRX cycle length. The UE first paging occasion is within the Paging Hyperframe as described in TS 36.304 [52] and TS 38.304 [50]. The UE is assumed reachable for paging within the Paging Time Window. The start and end of the Paging Time Window is described in TS 36.304 [52] and TS 38.304 [50]. After the Paging Time Window length, the AMF considers the UE unreachable for paging until the next Paging Hyperfame.
5.31.7.2.2.2 Loose Hyper SFN synchronization
NOTE: This clause applies when the extended DRX cycle length is 10.24s or longer for WB-E-UTRA, LTE-M and NB-IoT and longer than 10.24s for NR.
In order for the UE to be paged at roughly similar time, the H-SFN of all NG-RAN nodes and AMFs should be loosely synchronized.
Each NG-RAN node and AMF synchronizes internally the H-SFN counter so that the start of H-SFN=0 coincides with the same a preconfigured time epoch. If NG-RAN nodes and AMFs use different epochs, e.g. due to the use of different time references, the GPS time should be set as the baseline and the NG-RAN nodes and AMFs synchronize the H-SFN counter based on the GPS epoch considering the time offset between GPS epoch and other time-reference epoch a preconfigured time. It is assumed that NG-RAN nodes and AMFs are able to use the same H-SFN value with accuracy in the order of legacy DRX cycle lengths, e.g. 1 to 2 seconds. There is no need for synchronization at SFN level.
There is no signalling between network nodes required to achieve this level of loose H-SFN synchronization.
5.31.7.2.2.3 AMF paging and paging retransmission strategy
NOTE: This clause applies when the extended DRX cycle length is 10.24s or longer for WB-E-UTRA, LTE-M and NB-IoT and longer than 10.24s for NR.
When the AMF receives trigger for paging and the UE is reachable for paging, the AMF sends the paging request. If the UE is not reachable for paging, then the AMF pages the UE just before the next paging occasion.
The AMF determines the Paging Time Window length and a paging retransmission strategy and executes the retransmission scheme.
For extended DRX length of 10.24s, in the paging request message the AMF sends the Paging Time Window to the ng-eNB but does not send the Paging Time Window to the gNB. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.2.3 Paging for a UE registered in a tracking area with heterogeneous support of extended idle mode DRX | When the UE is registered in a registration area with heterogeneous support of extended idle mode DRX (e.g. comprising WB-E-UTRA and NR cells) and has negotiated eDRX, the AMF shall, for any paging procedure, perform at least one paging attempt during a PTW.
NOTE: Heterogeneous support of extended idle mode DRX in tracking areas assigned by AMF in a TAI list can result in significant battery life reduction in the UE as compared to homogeneous support by NG-RAN nodes of extended idle mode DRX. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.2.4 Paging for extended DRX for RRC_INACTIVE in NR connected to 5GC | For NR, the NG-RAN may request the CN to handle mobile terminated (MT) communication for the UE configured with eDRX for RRC_INACTIVE state by means of the Connection Inactive procedure with CN based MT communication handling Procedure (see clause 4.8.1.1a of TS 23.502 [3]). This allows the CN to apply high latency communication functions as specified in clause 5.31.8. The NG-RAN provides the determined eDRX values (i.e. the eDRX cycle length and the Paging Time Window length) for RRC_INACTIVE to AMF (i.e. >10.24s). Based on the request from NG-RAN, the AMF responds to NG-RAN and informs other NFs (e.g. SMF and UPF) involved in downlink data or signalling handling and trigger the data buffering as specified in clause 4.8.1.1a of TS 23.502 [3]. Based on local policy and/or an indication from the AMF, e.g. the RAT type of REDCAP or the CN based MT handling indication, the SMF may trigger the UPF to provide the DL data size in case of DL data arrival when data buffering is executed in the UPF.
When MT data or signalling arrives for a UE in RRC_INACTIVE state, the other NFs communicate with the AMF for delivery of MT data or signalling. The AMF calculates the UE reachability based on the eDRX values for RRC_INACTIVE state provided by NG-RAN and triggers NG-RAN paging via an N2 RAN Paging Request message if the UE is considered reachable as specified in clause 4.8.2.2b of TS 23.502 [3]. Otherwise, the AMF stores the information received in the NF request and replies to the requesting NF to apply high latency communication functions as specified in clause 5.31.8 based on eDRX values for RRC_INACTIVE (e.g. an Estimated Maximum Wait Time is calculated based on eDRX values for RRC_INACTIVE). When the AMF determines that the UE has become reachable for paging, the AMF uses the stored information to send an N2 RAN Paging Request message. If UPF/SMF provides the downlink data size information, the AMF provides the information to NG-RAN as described in clause 4.8.2.2b of TS 23.502 [3].
When the UE resumes the RRC connection as specified in TS 38.300 [27] (e.g. including mobile originated small data transmission procedure), if the NG-RAN had sent the indication for the CN to handle mobile terminated (MT) communication, NG-RAN proceeds as specified in clause 4.8.2.2 of TS 23.502 [3], which indicates to the AMF that the UE is now reachable for downlink data and/or signalling. The AMF then informs other NFs that the UE is now reachable using the high latency communication functions as specified in clause 5.31.8 and MT data and signalling can be delivered to the UE. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.3 MICO mode with Extended Connected Time | When a UE, using MICO mode, initiates MO signalling or MO data and the AMF is aware of pending or expected MT traffic, the AMF may keep the UE in CM-CONNECTED state and the RAN may keep the UE in RRC_CONNECTED state for an Extended Connected Time period in order to ensure the downlink data and/or signalling is delivered to the UE. The Extended Connected Time is determined by the AMF and is based on local configuration and/or the Maximum Response Time, if provided by the UDM.
The AMF maintains the N2 connection for at least the Extended Connected Time and provides the Extended Connected Time value to the RAN. The Extended Connected Time value indicates the minimum time the RAN should keep the UE in RRC_CONNECTED state regardless of inactivity. The Extended Connected Time value is provided to the RAN together with the
- NAS Registration Accept message; or
- NAS Service Accept message.
At inter-RAN node handovers, if some signalling or data are still pending, the target AMF may send the Extended Connected Time value to the target RAN node. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.4 MICO mode with Active Time | During a Registration procedure the UE may optionally request an Active Time value from the AMF as part of MICO Mode negotiation. In response, if the AMF receives an Active Time value from the UE and determines that the MICO mode is allowed for the UE, the AMF may assign an Active Time value for the UE, e.g. based on local configuration, Expected UE Behaviour if available, UE requested Active Time value, UE subscription information and network policies and indicates it to the UE during Registration procedure. When an Active Time value is assigned to the UE the AMF shall consider the UE reachable for paging after the transition from CM-CONNECTED to CM-IDLE for the duration of the Active Time. Together with the Active Time value, the UE may request a periodic registration time value as specified in clause 5.31.7.45.
When the AMF indicates MICO mode with an Active Time to a UE, the registration area may be constrained by paging area size. To avoid paging in the entire PLMN, when the AMF allocates the Active Time the AMF should not allocate "all PLMN" registration area to the UE.
The UE and AMF shall set a timer corresponding to the Active Time value negotiated during the most recent Registration procedure. The UE and AMF shall start the timer upon entering CM-IDLE state from CM-CONNECTED. When the timer expires (i.e. reaches the Active Time) the UE enters MICO mode and the AMF can deduce that the UE has entered MICO mode and is not available for paging. If the UE enters CM-CONNECTED state before the timer expires, the UE and AMF shall stop and reset the timer.
If no Active Time value was negotiated during the most recent Registration procedure the UE shall not start the timer and it shall instead enter MICO mode directly upon entering CM-IDLE state.
Active Time is not transferred between AMF and MME. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.7.5 MICO mode and Periodic Registration Timer Control | If the Expected UE Behaviour indicates the absence of DL communication, the AMF may allow MICO mode for the UE and allocate a large periodic registration timer value based on e.g. Network Configuration parameters to the UE so that the UE can maximise power saving between Periodic Registration Updates.
If the Expected UE Behaviour indicates scheduled DL communication the AMF should allow MICO mode for the UE and allocate a periodic registration timer value such that the UE performs Periodic Registration Update to renegotiate MICO mode before or at the scheduled DL communication time, if the AMF decides to allow MICO mode for the UE. When UE requests the MICO mode with active time, the UE may also request a periodic registration timer value suitable for the latency/responsiveness of the DL communication service known to UE. If the UE wants to change the periodic registration timer value, e.g. when the conditions are changed in the UE, the UE consequently requests the value it wants in the registration procedure. The AMF takes the UE requested periodic registration time value into consideration when providing the periodic registration timer to UE during Registration procedure as specified in clause 4.2.2.2.2 of TS 23.502 [3].
If the UE supports 'Strictly Periodic Registration Timer Indication', the UE indicates its capability of supporting 'Strictly Periodic Registration Timer Indication' in the Registration Request message. If the UE indicates its support of 'Strictly Periodic Registration Timer Indication' in the Registration Request message, the AMF may provide a Strictly Periodic Registration Timer Indication to the UE together with the periodic registration timer value, e.g. based on Expected UE Behaviour. If the indication is provided by the AMF, the UE and the AMF shall start the periodic registration timer after completion of the Registration procedure. The UE and the AMF shall neither stop nor restart the periodic registration timer when the UE enters CM-CONNECTED and shall keep it running while in CM-CONNECTED state and after returning to CM-IDLE state. If and only when the timer expires and the UE is in CM-IDLE, the UE shall perform a Periodic Registration Update. If the timer expires and the UE is in CM-CONNECTED state, the AMF and the UE restart the periodic registration timer while still applying 'Strictly Periodic Registration Timer Indication'. The AMF may use the UE Configuration Update procedure to trigger the UE to perform Registration procedure, in which the periodic registration timer value and 'Strictly Periodic Registration Timer Indication' can be renegotiated.
When the UE and the AMF locally disable MICO mode (e.g. when an emergency service is initiated), the UE and the AMF shall not apply 'Strictly Periodic Registration Timer Indication'.
If the periodic registration timer is renegotiated during a Registration procedure, e.g. triggered by UE Configuration Update and if the periodic registration timer is running, then the periodic registration timer is stopped and restarted using the renegotiated value even when the Strictly Periodic Registration Timer Indication was provided to the UE. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.8 High latency communication | Functions for High latency communication may be used to handle mobile terminated (MT) communication with UEs being unreachable while using power saving functions as specified in clause 5.31.7 or due to discontinuous coverage as described in clause 5.4.13. "High latency" refers to the initial response time before normal exchange of packets is established. That is, the time it takes before a UE has woken up from its power saving state and responded to an initial downlink packet or signal.
When a NR RedCap UE requests to use the power saving functions as specified in clause 5.31.7, then the AMF may, based on local policy, reroute the Registration Request to another AMF that supports High latency communication as specified in clause 6.3.5.
High latency communication is supported by extended buffering of downlink data in the UPF, SMF or NEF when a UE is using power saving functions in CM-IDLE state or in RRC_INACTIVE state, or when the UE is using a satellite access with discontinuous coverage and the UE is not reachable. For UPF anchored PDU sessions the SMF configures during AN release or when NG-RAN indicates via the AMF the UE is in extended DRX for RRC_INACTIVE, the UPF with user data Forwarding Action Rule and user data Buffering Action Rule according to TS 29.244 [65]. The rules include instructions whether UPF buffering applies or the user data shall be forwarded to the SMF for buffering in the SMF. For NEF anchored PDU sessions only extended buffering in the NEF is supported in this release of the specification. During the Network Triggered Service Request procedure or Mobile Terminated Data Transport procedures when using Control Plane CIoT 5GS Optimisation, the AMF provides an Estimated Maximum Wait Time to the SMF if the SMF indicates the support of extended buffering. The SMF determines the Extended Buffering Time based on the received Estimated Maximum Wait Time or local configuration. The handling is e.g. specified in the Network Triggered Service Request procedure, clauses 4.2.3.3, 4.2.6, 4.24.2 and 4.25.5 of TS 23.502 [3].
High latency communication is also supported through notification procedures. The following procedures are available based on different monitoring events:
- UE Reachability;
- Availability after DDN failure;
- Downlink Data Delivery Status.
An AF may request a one-time "UE Reachability" notification when it wants to send data to a UE which is using a power saving function (see event subscription procedure in clause 4.15.3.2 of TS 23.502 [3]). The SCS/AS/AF then waits with sending the data until it gets a notification that the UE is reachable (see notification procedures in TS 23.502 [3]).
An AF may request repeated "Availability after DDN failure" notifications where each UE reachability notification is triggered by a preceding DDN failure, i.e. the AF sends a downlink packet to request a UE reachability notification when the UE becomes reachable. That downlink packet is discarded by the UPF or SMF or NEF (see notification procedures in TS 23.502 [3]).
An AF may request repeated "Downlink Data Delivery Status" notifications when it wants indications that DL data has been buffered or when buffered DL data has been delivered to the UE.
If MICO mode or extended idle mode DRX is enabled, Idle Status Indication allows the AF to determine when the UE transitions into idle mode. When requesting to be informed of either "UE Reachability" or "Availability after DDN failure" notification, the AF may also request Idle Status Indication. If the UDM and the AMF support Idle Status Indication, then when the UE for which MICO mode or extended idle mode DRX is enabled transitions into idle mode, the AMF includes in the notification towards the NEF the time at which the UE transitioned into idle mode, the active time and the periodic registration update timer granted to the UE by the AMF, the eDRX cycle length and the Suggested number of downlink packets if a value was provided to the SMF.
An AF may provide parameters related to High latency communication for different methods to UDM, via NEF, as part of provisioning capability as specified in clause 5.20. The UDM can further deliver the parameters to other NFs (e.g. AMF or SMF) as specified in clause 4.15.6 of TS 23.502 [3].
If the AMF is aware that some signalling or data is pending in the network for an UE that is known as being unreachable for a long duration, e.g. for UE's having extended idle mode DRX, extended DRX for RRC_INACTIVE or MICO enabled, the AMF maintains the N2 connection for at least the Extended Connected Time and provides the Extended Connected Time value in a NG-AP message to the RAN. The Extended Connected Time value indicates the minimum time the RAN should keep the UE in RRC_CONNECTED state regardless of inactivity. At inter-RAN node handovers, if some signalling or data are still pending, the target AMF may send the Extended Connected Time value to the target RAN node. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.9 Support for Monitoring Events | The Monitoring Events feature is intended for monitoring of specific events in the 3GPP system and reporting such Monitoring Events via the NEF. The feature allows NFs in 5GS to be configured to detect specific events and report the events to the requested party. Clause 5.20 further discusses the Monitoring capabilities of the NEF.
For CIoT, the list of supported monitoring events is specified in Table 4.15.3.1-1 of TS 23.502 [3].
Support for Monitoring Events can be offered via AMF, UDM, NSACF and SMF and can be reported via the NEF, as specified in clause 4.15.3 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.10 NB-IoT UE Radio Capability Handling | NB-IoT Radio Capabilities are handled in the network independently from other RATs' Radio Capabilities, see clause 5.4.4.1. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.11 Inter-RAT idle mode mobility to and from NB-IoT | Tracking Areas are configured so that they do not contain both NB-IoT and other RATs' cells, so when the UE is changing RAT type to or from NB-IoT while remaining registered with 5GC, the UE will perform the Mobility Registration Update procedure, see clause 5.3.2.3. When the UE is changing RAT type to or from NB-IoT and moving between 5GC and EPC, during the Registration, Attach or TAU procedure the RAT type change is determined.
The specification in this clause does not apply to RAT type corresponding to Non-3GPP Access type.
PDU session handling is controlled by "PDU Session continuity at inter RAT mobility" in the UE's subscription data, which indicates per DNN/S-NSSAI whether to;
- maintain the PDU session,
- disconnect the PDU session with a reactivation request,
- disconnect the PDU session without reactivation request, or
- leave it up to local VPLMN policy
when the UE moves between a "broadband" RAT (e.g. NR or WB-E-UTRA) and a "narrowband" RAT (NB-IoT).
During PDU session establishment the SMF retrieves the "PDU Session continuity at inter RAT mobility" subscription information (if available) from the UDM. Local SMF configuration is used if "PDU Session continuity at inter RAT mobility" is not available for a PDU Session.
The AMF informs the SMF at an inter-RAT idle mobility event, e.g. to or from NB-IoT connected to 5GC about the RAT type change in the Nsmf_PDUSession_UpdateSMContext message during the Registration procedure. Based on this (H-)SMF handles the PDU session according to "PDU session continuity at inter RAT mobility information" subscription data or based on local policy.
NOTE: The "PDU Session continuity at inter RAT mobility" and "PDN continuity at inter-RAT mobility" subscription should be the same so that the PDU sessions/PDN connections are handled the same by both CN types.
During inter-RAT idle mode mobility to NB-IoT, if a PDU session has more than one QoS rule, the SMF shall initiate a PDU session modification procedure as described in TS 23.502 [3] to remove any non-default QoS rule and maintain only the default QoS rule. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.12 Restriction of use of Enhanced Coverage | Support of UEs in E-UTRA Enhanced Coverage is specified in TS 36.300 [30].
The usage of Enhanced Coverage requires use of extensive resources (e.g. radio and signalling resources). Specific subscribers can be restricted to use the Enhanced Coverage feature through Enhanced Coverage Restricted information that is stored in the UDM as part of subscription data and specifies per PLMN whether the Enhanced Coverage functionality is restricted or not for the UE. For eMTC, the Enhanced Coverage Restricted information indicates whether CE mode B is restricted for the UE, or both CE mode A and CE mode B are restricted for the UE, or both CE mode A and CE mode B are not restricted for the UE. For NB-IoT, the NB-IoT Enhanced Coverage Restricted information indicates whether the Enhanced Coverage is restricted or not for the UE.
The AMF receives Enhanced Coverage Restricted information from the UDM during the Registration procedure. If the UE includes the support for restriction of use of Enhanced Coverage in the Registration Request message, the AMF based on local configuration, UE Usage setting, UE subscription information and network policies, or any combination of them, determines whether Enhanced Coverage is restricted for the UE and stores updated Enhanced Coverage Restriction information in the UE context in the AMF. If the UE usage setting indicated that UE is "voice centric", then the AMF shall set CE mode B restricted for the UE in Enhanced Coverage Restriction information.
The AMF sends Enhanced Coverage Restricted information to the UE in the Registration Accept message. The UE shall use the value of Enhanced Coverage Restricted information to determine if enhanced coverage feature is restricted or not. The AMF provides an Enhanced Coverage Restricted information to the RAN via N2 signalling whenever the UE context is established in the RAN, e.g. during N2 Paging procedure, Service Request procedure, Initial Registration and Periodic Registration procedure.
For roaming UEs, if the UDM doesn't provide any Enhanced Coverage Restricted information or the provided Enhanced Coverage Restricted information is in conflict with the roaming agreement, the AMF uses default Enhanced Coverage Restricted information locally configured in the VPLMN based on the roaming agreement with the subscriber's HPLMN.
The UE indicates its capability of support for restriction of use of Enhanced Coverage to the AMF in the Registration procedure for the RAT it is camping on. A UE that supports Enhanced Coverage shall also support restriction of the Enhanced Coverage.
The UE shall assume that restriction for use of Enhanced Coverage indicated by Enhanced Coverage Restricted information is the same in the equivalent PLMNs. NB-IoT cells also broadcast the support of restriction of use of Enhanced Coverage as defined in TS 36.331 [51].
If the UE supports CE mode B and use of CE mode B is not restricted according to the Enhanced Coverage Restriction information in the UE context in the AMF, then the AMF shall use the extended NAS-MM timer setting for the UE as specified in TS 24.501 [47] and shall send the extended NAS-SM timer indication during PDU session establishment to the SMF.
If the UE supports CE mode B and use of CE mode B changes from restricted to unrestricted or vice versa in the Enhanced Coverage Restriction information in the UE context in the AMF (e.g. due to a subscription change) then:
- The AMF determines when to enforce the change of restriction of use of Enhanced Coverage.
- When the UE is in CM-CONNECTED mode, the AMF can use the UE Configuration Update procedure, as specified in step 3a of clause 4.2.4.2 of TS 23.502 [3], to trigger a mobility registration update procedure in CM-CONNECTED mode for the AMF to inform the change of restriction of Enhanced Coverage towards the UE.
- If the UE has already established PDU sessions, then the AMF shall trigger a PDU session modification to the SMFs serving the UE's PDU sessions to update the use of the extended NAS-SM timer setting as described in step 1f of clause 4.3.3.2 of TS 23.502 [3] when the AMF determines that NAS-SM timer shall be updated due to the change of Enhanced Coverage Restriction.
- The UE and network applies the new Enhanced Coverage Restriction information after mobility registration procedure is completed.
Based on the extended NAS-SM timer indication, the SMF shall use the extended NAS-SM timer setting for the UE as specified in TS 24.501 [47].
The support for Enhanced Coverage Restriction Control via NEF enables AF to query status of Enhanced Coverage Restriction or enable/disable Enhanced Coverage Restriction per individual UEs. The procedure for Enhanced Coverage Restriction Control via NEF is described in clause 4.27 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.13 Paging for Enhanced Coverage | Support of UEs in E-UTRA Enhanced Coverage is specified in TS 36.300 [30].
Whenever N2 is released and Paging Assistance Data for CE capable UE is available for the UE, the NG-RAN sends it to the AMF as described in clause 4.2.6 of TS 23.502 [3].
The AMF stores the received Paging Assistance Data for CE capable UE and then the AMF includes it in every subsequent Paging message for all NG-RAN nodes selected by the AMF for paging.
If Enhanced Coverage is restricted for the UE as described in clause 5.31.12, the AMF sends the Enhanced Coverage Restriction parameter as defined in TS 38.413 [34].
NOTE: Only the NG-RAN node which cell ID is included in the Paging Assistance Data considers the assistance data. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.14 Support of rate control of user data | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.14.1 General | The rate of user data sent to and from a UE (e.g. a UE using CIoT 5GS Optimisations) can be controlled in two different ways:
- Serving PLMN Rate Control;
- Small Data Rate Control.
Serving PLMN Rate Control is intended to allow the Serving PLMN to protect its AMF and the Signalling Radio Bearers in the NG-RAN from the load generated by NAS Data PDUs.
Small Data Rate Control is intended to allow HPLMN operators to offer customer services such as "maximum of Y messages per day".
NOTE: Existing Session-AMBR mechanisms are not suitable for such a service since, for radio efficiency and UE battery life reasons, an AMBR of e.g. > 100kbit/s is desirable and such an AMBR translates to a potentially large daily data volume.
The SMF in the Serving PLMN may send the Small Data rate control parameter for an emergency PDU session. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.14.2 Serving PLMN Rate Control | The Serving PLMN Rate Control value is configured in the (V-)SMF.
NOTE 1: Homogeneous support of Serving PLMN Rate Control in a network is assumed.
At PDU Session establishment and PDU Session modification, the (V-)SMF may inform the UE and UPF/NEF of any per PDU Session local Serving PLMN Rate Control that the Serving PLMN intends to enforce for NAS Data PDUs. The (V-)SMF shall only indicate a Serving PLMN Rate Control command to the UPF if the PDU Session is using N4 and is set to Control Plane only. The (V-)SMF shall only indicate a Serving PLMN Rate Control command to the NEF if that PDN connection is using NEF.
Serving PLMN rate control is operator configurable and expressed as "X NAS Data PDUs per deci hour" where X is an integer that shall not be less than 10. There are separate limits for uplink and downlink NAS Data PDUs:
- The UE shall limit the rate at which it generates uplink NAS Data PDUs to comply with the Serving PLMN policy. In the UE the indicated rate control applies only on the PDU Session where it was received and therefore the UE shall limit the rate of its uplink NAS Data PDUs to comply with the rate that is indicated for the PDU Session. The indicated rate is valid until the PDU Session is released.
- The UPF/NEF shall limit the rate at which it generates downlink Data PDUs. In the UPF/NEF the indicated rate control applies only on the PDU Session where it was received and therefore the UPF/NEF shall limit the rate of its downlink Data PDUs to comply with the rate that is indicated for the PDU Session.
- The (V-)SMF may enforce these limits per PDU Session by discarding or delaying packets that exceed these limits. The Serving PLMN Rate does not include SMS using NAS Transport PDUs. The (V-)SMF starts the Serving PLMN Rate Control when the first NAS Data PDU is received.
NOTE 2: If the UE/UPF/NEF start the Serving PLMN rate control at a different time than the (V-)SMF, PDUs sent within the limit enforced at the UE/UPF/NEF can still exceed the limit enforced by the (V-)SMF.
NOTE 3 It is assumed that the Serving PLMN Rate is sufficiently high to not interfere with the Small Data Rate Control as the Small Data Rate Control, if used, is assumed to allow fewer messages. NAS PDUs related to exception reports are not subject to the Serving PLMN Rate Control. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.14.3 Small Data Rate Control | The (H-)SMF may consider, e.g. based on operator policy, subscription, DNN, S-NSSAI, RAT type etc. to determine whether to apply Small Data Rate Control or not. The (H-)SMF can send a Small Data Uplink Rate Control command to the UE using the PCO information element. The (H-)SMF informs the UPF or NEF of any Small Data Rate Control that shall be enforced.
The Small Data Rate Control applies to data PDUs sent on that PDU Session by either Data Radio Bearers or Signalling Radio Bearers (NAS Data PDUs).
The rate control information is separate for uplink and downlink and in the form of:
- an integer 'number of packets per time unit' and
- an integer 'number of additional allowed exception report packets per time unit' once the rate control limit has been reached.
The UE shall comply with this uplink rate control instruction. If the UE exceeds the uplink 'number of packets per time unit', the UE may still send uplink exception reports if allowed and the 'number of additional allowed exception reports per time unit' has not been exceeded. The UE shall consider this rate control instruction as valid until it receives a new one from (H-)SMF.
When a PDU Session is first established, the (H-)SMF may provide the configured Small Data Rate Control parameters to the UE and UPF or NEF.
When the PDU Session is released, the Small Data Rate Control Status (including the number of packets still allowed in the given time unit, the number of additional exception reports still allowed in the given time unit and the termination time of the current Small Data Rate Control validity period) may be stored in the AMF so that it can be retrieved for a subsequent re-establishment of a new PDU Session.
At subsequent establishment of a new PDU Session, the (H-)SMF may receive the previously stored Small Data Rate Control Status and if the validity period has not expired, it provides the parameters to the UE in the PCO and to the UPF/NEF as the initially applied parameters, in addition to the configured Small Data Rate Control parameters. If the initially applied parameters are provided, the UE and UPF or NEF shall apply them and shall use the SMF provided configured Small Data Rate Control parameters once the initially applied Small Data Rate Control validity period expires.
NOTE 1: Storage of Small Data Rate Control Status information for very long time intervals can be implementation specific.
For the UPF and NEF, Small Data Rate Control is based on a 'maximum allowed rate' per direction. If (H-)SMF provided the 'number of additional allowed exception report packets per time unit', then the 'maximum allowed rate' is equal to the 'number of packets per time unit' plus the 'number of additional allowed exception report packets per time unit', otherwise the 'maximum allowed rate' is equal to the 'number of packets per time unit'.
The UPF or NEF may enforce the uplink rate by discarding or delaying packets that exceed the 'maximum allowed rate'. The UPF or NEF shall enforce the downlink rate by discarding or delaying packets that exceed the downlink part of the 'maximum allowed rate'.
NOTE 2: It is assumed that the Serving PLMN Rate is sufficiently high to not interfere with the Small Data Rate Control as the Small Data Rate Control, if used, is assumed to allow fewer messages. NAS PDUs related to exception reports are not subject to the Serving PLMN Rate Control.
For NB-IoT the AMF maintains an "MO Exception Data Counter" which is incremented when the RRC establishment cause "MO exception data" is received from NG-RAN. The AMF reports whether the UE accessed using "MO exception data" RRC establishment cause, to all (H-)SMFs which have PDU Sessions that are subject to Small Data Rate Control and if the UE is accessing using "MO exception data" then the "MO Exception Data Counter" is also provided by the AMF. The SMF indicates each use of the RRC establishment cause "MO Exception Data" by including the related counter on the charging information.
NOTE 3: Since Exception Data PDUs and normal priority PDUs cannot be distinguished within an RRC connection, the AMF is only counting the number of RRC Connection establishments with "MO Exception data" priority.
If the UE moves to EPC then the UE and the PGW-U+UPF store the current Small Data Rate Control Status for all PDU Sessions that are not released. If the UE moves back to 5GC the stored Small Data Rate Control Status is restored and continues to apply to PDU Session(s) that are moved from EPC to 5GC, taking into account remaining validity period of the stored Small Data Rate Control Status. When the UE moves to EPC the Small Data Rate Control Status for all PDU Session(s) may also be stored in the AMF if the PDU Session is released while the UE is connected to EPC and re-established when the UE moves to 5GC. The time to store the Small Data Rate Control Status information is implementation specific. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.15 Control Plane Data Transfer Congestion Control | NAS level congestion control may be applied in general for all NAS messages. To enable congestion control for control plane data transfer, a Control Plane data back-off timer is used, see clause 5.19.7.6. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.16 Service Gap Control | Service Gap Control is an optional feature intended for CIoT UEs to control the frequency at which these UEs can access the network. That is, to ensure a minimum time gap between consecutive Mobile Originated data communications initiated by the UE. This helps reducing peak load situations when there are a large number of these UEs in an operator network. Service Gap Control is intended to be used for "small data allowance plans" for MTC/CIoT UEs where the applications are tolerant to service latency.
NOTE 1: Time critical applications, such as regulatory prioritized services like Emergency services can suffer from the latency caused by the Service Gap Control feature. Therefore Service Gap Control feature is not recommended for subscriptions with such applications and services.
Service Gap Time is a subscription parameter used to set the Service Gap timer and is enforced in the UE and in the AMF on a per UE level (i.e. the same Service Gap Timer applies for all PDU Sessions that the UE has). The UE indicates its capability of support for Service Gap Control in the Registration Request message to the AMF. The AMF passes the Service Gap Time to the UE in the Registration Accept message for a UE that has indicated its support of the Service Gap Control. The Service Gap Control shall be applied in a UE when a Service Gap Time is stored in the UE context and applied in the AMF when the Service Gap Time is stored in the UE Context in the AMF.
Service Gap Control requires the UE to stay in CM-IDLE mode for at least the whole duration of the Service Gap timer before triggering Mobile Originated user data transmission, except for procedures that are exempted (see TS 24.501 [47]). The Service Gap timer shall be started each time a UE moves from CM-CONNECTED to CM-IDLE, unless the connection request was initiated by the paging of a Mobile Terminated event, or after a Mobility or Periodic Registration procedure without Follow-on Request indication and without Uplink data status, which shall not trigger a new or extended Service Gap interval. When a Service Gap timer expires, the UE is allowed to send a connection request again. If the UE does so, the Service Gap timer will be restarted at the next CM-CONNECTED to CM-IDLE transition.
The Service Gap control is applied in CM-IDLE state only and does not impact UE Mobile Originated user data transmission or Mobile Originated signalling in CM-CONNECTED state. The Service Gap timer is not stopped upon CM-IDLE state to CM-CONNECTED state transition. The UE shall not initiate connection requests for MO user plane data, MO control plane data, or MO SMS when a Service Gap timer is running. The UE shall not initiate PDU Session Establishment Requests when a Service Gap timer is running, unless it is for Emergency services which are allowed. CM-CONNECTED with RRC_INACTIVE is not used for UEs that have a Service Gap Time configured.
NOTE 2: As a consequence of allowing Initial Registration Request procedure, the UE with a running Service Gap timer does not initiate further MO signalling, except for Mobility Registration procedure, until the UE receives MT signalling or after the UE has moved to CM-IDLE state and the Service Gap Timer is not running.
NOTE 3: Implementations need to make sure that latest and up-to-date data are always sent when a Service Gap timer expires.
The AMF may enforce the Service Gap timer by rejecting connection requests for MO user plane data, MO control plane data, or MO SMS when a Service Gap timer is running. The AMF may enforce the Service Gap timer by not allowing MO signalling after Initial Registration requests when a Service Gap timer is running except for Mobility Registration procedure, Periodic Registration procedure or access to the network for regulatory prioritized services like Emergency services, which are allowed. When rejecting the connection requests and the SM signalling after Initial Registration Requests while the Service Gap timer is running, the AMF may include a Mobility Management back-off timer corresponding to the time left of the current Service Gap timer. For UEs that do not support Service Gap Control (e.g. pre-release-16 UEs), Service Gap Control may be enforced using "General NAS level congestion control" as defined in clause 5.19.7.2.
NOTE 4: After MT signalling in CM-CONNECTED state the AMF does not further restrict MO signalling when a Service Gap timer is running as this case is considered equal to a connectivity request in response to paging.
When the AMF starts the Service Gap timer, the AMF should invoke the Service Gap timer with a value that is slightly shorter than the Service Gap Time value provided to the UE based on the subscription information received from the UDM.
NOTE 5: This ensures that the AMF does not reject any UE requests just before the Service Gap timer expires e.g. because of slightly unsynchronized timers between UE and AMF.
A UE which transitions from a MICO mode or eDRX power saving state shall apply Service Gap Control when it wakes up if the Service Gap timer is still running.
Additional aspects of Service Gap Control:
- Service Gap Control applies in all PLMNs.
- When the Service Gap timer is running and the UE receives paging, the UE shall respond as normal.
- Service Gap Control does not apply to exception reporting for NB-IoT.
- Access to the network for regulatory prioritized services like Emergency services are allowed when a Service Gap timer is running.
- Service Gap Control shall be effective also for UEs performing de-registration and re-registration unless access to the network for regulatory prioritized services like Emergency services is required.
- If the Service Gap timer is running, the Service Gap is applied at PLMN selection as follows:
a) Re-registration to the registered PLMN: The remaining Service Gap timer value survives.
b) Registration to a different PLMN: The remaining Service Gap timer value survives.
c) USIM swap: The Service Gap timer is no longer running and the Service Gap feature does not apply, unless re-instantiated by the serving PLMN.
- Multiple uplink packets and downlink packets are allowed during one RRC connection for UE operating within its Rate Control limits.
The following procedures are impacted by Service Gap Control:
- Registration Procedure, see clause 4.2.2.2 of TS 23.502 [3];
- UE Triggered Service Request, see clause 4.2.3.2 of TS 23.502 [3];
NOTE 6: Since UE triggered Service Request is prevented by Service Gap timer, this implicitly prevents the UE from initiating UPF anchored Mobile Originated Data Transport in Control Plane CIoT 5GS Optimisation (see clause 4.24.1 of TS 23.502 [3]), NEF Anchored Mobile Originated Data Transport (see clause 4.25.4 of TS 23.502 [3]) and MO SMS over NAS in CM-IDLE (see clause 4.13.3.3 of TS 23.502 [3]). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.17 Inter-UE QoS for NB-IoT | To allow NG-RAN to prioritise resource allocation between different UEs accessing via NB-IoT when some of the UEs are using Control Plane CIoT 5GS Optimisation, NG-RAN may, based on configuration, retrieve from the AMF the subscribed NB-IoT UE Priority for any UE accessing via NB-IoT by using the UE's 5G-S-TMSI as the identifier.
In order to reduce signalling load on the AMF, NG-RAN may be configured to request the NB-IoT UE Priority from the AMF e.g. only when the NG-RAN's NB-IoT load exceeds certain threshold(s) or when the NG-RAN needs to cache the QoS profile. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.18 User Plane CIoT 5GS Optimisation | User Plane CIoT 5GS Optimisation enables transfer of user plane data from CM-IDLE without the need for using the Service Request procedure to establish Access Stratum (AS) context in NG-RAN and UE.
If the following preconditions are met:
- UE and AMF negotiated support User Plane CIoT 5GS Optimisation (see clause 5.31.2) over NAS,
- the UE has indicated support of User Plane CIoT 5GS Optimisation in the UE radio capabilities as defined in TS 36.331 [51],
- AMF has indicated User Plane CIoT 5GS Optimisation support for the UE to NG-RAN,
- the UE has established at least one PDU session with active UP connection, i.e. AS context is established in NG-RAN and the UE,
then the RRC connection can be suspended by means of the Connection Suspend Procedure (see clause 4.8.1.2 of TS 23.502 [3]).
Based on a trigger from the NAS layer when a UE is in CM-IDLE with Suspend, the UE should attempt the Connection Resume in CM-IDLE with Suspend procedure (clause 4.8.2.3 of TS 23.502 [3]). If the Connection Resume in CM-IDLE with Suspend procedure fails, the UE initiates the pending NAS procedure. To maintain support for User Plane CIoT 5GS Optimisation for UE mobility across different NG-RAN nodes, the AS Context should be transferred between the NG-RAN nodes, see TS 38.300 [27] and TS 38.423 [99].
For MT data or signalling when the UE is in CM-IDLE with Suspend, Network Triggered Service Request procedure (clause 4.2.3.3 of TS 23.502 [3]) applies.
By using the Connection Suspend Procedure:
- the UE at transition into CM-IDLE stores the AS information;
- NG-RAN stores the AS information, the NGAP UE association and the PDU session context for that UE;
- AMF stores the NGAP UE association and other information necessary to later resume the UE, interacts with the SMF(s) to deactivate the user plane resources for the UE's PDU Sessions and enters CM-IDLE.
NG-RAN may decide based on implementation to delete the stored UE context and NGAP association. In that case, the RAN shall initiate the AN Release procedure as described in clause 4.2.6 of TS 23.502 [3]. NG-RAN does not initiate any RRC procedure to notify the UE of the UE context release.
By using the Connection Resume in CM-IDLE with Suspend procedure:
- the UE resumes the connection from CM-IDLE with the network using the AS information stored during the Connection Suspend procedure;
- NG-RAN notifies the AMF that the connection with the UE has been resumed;
- AMF enters CM-CONNECTED and interacts with the SMF to activate the user plane resources for the UE's PDU Sessions.
Early Data Transmission may be initiated by the UE for mobile originated User Plane CIoT 5GS Optimisation during Connection Resume.
If the AMF establishes an NGAP UE association with a new NG-RAN node different from the stored NGAP UE association, e.g. the UE initiates service request or registration procedure from a different NG-RAN node, the AMF initiates UE N2 release command towards the old NG-RAN node.
NG-RAN maintains the N3 tunnel endpoint information while a UE is in CM-IDLE with Suspend. UPF is instructed to remove DL N3 Tunnel Info of AN during Connection Suspend procedure, while UPF keeps UL N3 Tunnel Info (i.e. UPF accepts and forwards UL data). If a UE sends MO data with resume procedure, the NG-RAN can send the MO data to the UPF which is addressed by the N3 tunnel endpoint information. In the case of change of serving NG-RAN node due to UE mobility, if NG-RAN determines that it is not able to connect to the UPF which is addressed by the N3 tunnel endpoint information, NG-RAN performs Path Switch procedure before sending the MO data received from the UE.
Early Data Transmission may be initiated by the UE for mobile originated User Plane CIoT 5GS Optimisation when the RAT Type is E-UTRA. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.19 QoS model for NB-IoT | 5GC QoS model described in clause 5.7 applies to NB-IoT with the following requirements:
- The default QoS rule shall be the only QoS rule of a PDU Session for a UE connected to 5GC via NB-IoT. There is only one QoS Flow (corresponding to the default QoS rule) per PDU session.
- Reflective QoS is not supported over NB-IoT.
- For NB-IoT, there is a 1:1 mapping between the QoS Flow corresponding to the default QoS of a PDU session and a Data Radio Bearer when user plane resources are active for that PDU session.
- A maximum of two Data Radio Bearers are supported over NB-IoT. Therefore, at most two PDU sessions can have active user plane resources at the same time.
- The capability of multiple UP resource support for NB-IoT UEs is indicated in the UE 5GMM Core Network Capability (see TS 24.501 [47]). During PDU Session Establishment or UP resource activation, the AMF checks if the UE can support the establishment of user plane resources (See clause 4.2.3.2 and clause 4.3.2.2.1 of TS 23.502 [3]). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.31.20 Category M UEs differentiation | This functionality is used by the network to identify traffic to/from Category M UEs, e.g. for charging differentiation.
A Category M UE using E-UTRA shall provide a Category M indication to the NG-RAN during RRC Connection Establishment procedure as defined in TS 36.331 [51].
When the UE has provided a Category M indication to the NG-RAN during RRC Connection Establishment, the NG-RAN shall provide an LTE-M Indication to the AMF in the Initial UE Message (see clause 4.2.2.2.1 of TS 23.502 [3] and TS 38.413 [34]).
When the AMF receives an LTE-M Indication from NG-RAN in an Initial UE Message or from an MME during EPS to 5GS handover, the AMF shall store the LTE-M Indication in the UE context, consider that the RAT type is LTE-M and signal it accordingly to the SMSF during registration procedure for SMS over NAS, to the SMF during PDU Session Establishment or PDU Session Modification procedure. The PCF can also receive the RAT Type as LTE-M, when applicable from the AMF using the PCRT on Access Type change specified in clause 6.1.2.5 of TS 23.503 [45] during AM Policy Association Establishment or AM Policy Association Modification procedure and from the SMF using the PCRT on Access Type change specified in clause 6.1.3.5 of TS 23.503 [45] during SM Policy Association Establishment or SM Policy Association Modification procedure.
The NFs generating CDRs shall include the LTE-M RAT type in their CDRs.
Upon AMF change or inter-system mobility from 5GS to EPS, the source AMF shall provide the "LTE-M Indication" to the target AMF or MME as part of the UE context.
During EPS to 5GS Mobility Registration Procedure, the AMF shall disregard any "LTE-M Indication" received from the MME in the UE context (see TS 23.401 [26]) and take into account the "LTE-M Indication" received from NG-RAN, as specified above. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.32 Support for ATSSS | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.32.1 General | The ATSSS feature is an optional feature that may be supported by the UE and the 5GC network.
The ATSSS feature enables a multi-access PDU Connectivity Service, which can exchange PDUs between the UE and a data network by simultaneously using one 3GPP access network and one non-3GPP access network and two independent N3/N9 tunnels between the PSA and RAN/AN. The multi-access PDU Connectivity Service is realized by establishing a Multi-Access PDU (MA PDU) Session, i.e. a PDU Session that may have user-plane resources on two access networks. This assumes both 3GPP access and non-3GPP access are allowed for the S-NSSAI of the PDU Session.
The UE may request a MA PDU Session when the UE is registered via both 3GPP and non-3GPP accesses, or when the UE is registered via one access only.
After the establishment of a MA PDU Session and when there are user-plane resources on both access networks, the UE applies network-provided policy (i.e. ATSSS rules) and considers local conditions (such as network interface availability, signal loss conditions, user preferences, etc.) for deciding how to distribute the uplink traffic across the two access networks. Similarly, the UPF anchor of the MA PDU Session applies network-provided policy (i.e. N4 rules) and feedback information received from the UE via the user-plane (such as access network Unavailability or Availability) for deciding how to distribute the downlink traffic across the two N3/N9 tunnels and the two access networks. When there are user-plane resources on only one access network, the UE applies the ATSSS rules and considers local conditions for triggering the establishment or activation of the user plane resources over another access.
The type of a MA PDU Session may be one of the following types defined in clause 5.6.1: IPv4, IPv6, IPv4v6 and Ethernet. In this release of the specification, the Unstructured type is not supported. The clause 5.32.6.2.1, the clause 5.32.6.2.2 and the clause 5.32.6.3.1 below define what Steering Functionalities can be used for each supported type of a MA PDU Session.
The handling of 3GPP PS Data Off feature for MA PDU Session is specified in clause 5.24.
The ATSSS feature can be supported over any type of access network, including untrusted and trusted non-3GPP access networks (see clauses 4.2.8 and 5.5), wireline 5G access networks (see clause 4.2.8), etc. as long as a MA PDU Session can be established over this type of access network.
In this Release of the specification, a MA PDU Session using IPv6 multi-homing (see clause 5.6.4.3) or UL Classifier (see clause 5.6.4.2) is not specified.
In this Release of the specification, support for ATSSS assumes SMF Service Areas covering the whole PLMN or that a MA PDU Session is released over both accesses when the UE moves out of the SMF Service Area.
A MA PDU Session does not support LADN. If the AMF receives a request to establish a MA PDU Session for a LADN DNN, the AMF shall reject the request. If the AMF receives a request to establish a PDU Session for a LADN DNN with "MA PDU Network-Upgrade Allowed" indication, the AMF shall not forward "MA PDU Network-Upgrade Allowed" indication to the SMF.
If the UE, due to mobility, moves from being served by a source AMF supporting ATSSS to a target AMF not supporting ATSSS, the MA PDU Session is released as described in TS 23.502 [3].
NOTE 1: Deployment of ATSSS that is homogeneous per PLMN, or network slice enables consistent behaviour. In the case of non-homogenous support of ATSSS in a PLMN/slice (i.e. some NFs in a PLMN/slice may not support ATSSS), MA PDU Sessions can be released due to UE mobility.
A Multi-Access PDU Session may, for the 3GPP access and/or non-3GPP access, use user-plane resources of an associated PDN Connection in EPC (e.g. one 3GPP access path via EPC and one non-3GPP access path via 5GC or one 3GPP access path via 5GC and one non-3GPP access path via ePDG/EPC). Such use of ATSSS with EPS interworking may apply to Ethernet and IP-based PDU Session and PDN Connection types.
NOTE 2: Co-existence with NBIFOM is not defined. It is assumed that NBIFOM and the multi-access connectivity described in this clause are not deployed in the same network.
NOTE 3: To the MME and SGW this is a regular PDN Connection and the support for ATSSS is transparent to MME and SGW.
For a MA PDU Session established for the Ethernet PDU Session type, if the UE has not indicated support for Ethernet PDN connection type or if the network does not support Ethernet PDN connection type, when the 3GPP access use user-plane resources of an associated PDN Connection, the following takes place:
- The SMF+PGW-C considers that the Multi-Access PDU Session is still using the Ethernet PDU Session / PDN Connection type but in a restricted mode where EPS signalling can only refer to non-IP PDN Connection type.
- MAR rules in the UPF are still used for distributing DL traffic between 3GPP access and non-3GPP access.
- For traffic on 3GPP access, the SMF may update N4 rules and QoS rules/EPS bearer contexts on the UE to take into account that no QoS differentiation is possible over 3GPP access.
Support of Multi-Access PDU Sessions using one leg associated with PDN Connection in EPC and one leg associated with PDU Session in 5GC is further defined in TS 23.502 [3].
The following clauses specify the functionality that enables ATSSS. |
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