6.5 Support of 3GPP Application Layer Architecture for Enabling Edge Computing
23.5483GPP5G System Enhancements for Edge ComputingRelease 17Stage 2TS
6.5.1 General
The 3GPP application layer architecture for Enabling Edge Computing that is specified in TS 23.558 [5] includes the following functional entities:
– Edge Enabler Client (EEC).
– Edge Configuration Server (ECS).
– Edge Enabler Server (EES).
A UE may host EEC(s) as defined in TS 23.558 [5] and support the ability to receive ECS address(es) from the 5GC and to transfer the ECS address(es) to the EEC(s). In this case, the ECS address provisioning via 5GC is described in clause 6.5.2.
NOTE: The features described in the other clauses of this specification do not require the UE and the network to support the 3GPP application layer architecture for Enabling Edge Computing that is specified in TS 23.558 [5].
6.5.2 ECS Address Provisioning
6.5.2.1 ECS Address Configuration Information
The ECS Address Configuration Information consists of one or more ECS Configuration Information as defined in clause 8.3.2.1 of TS 23.558 [5]. The ECS Configuration Information may contain Spatial Validity Conditions, which includes one of the following alternatives:
– a Geographical Service Area (see TS 23.558 [5]);
– a list of TA(s); or
– a list of countries (list of MCC).
A UE may receive multiple instances of ECS Address Configuration Information e.g., corresponding to different ECSPs (e.g., the MNO or a 3rd party service provider).
The ECS Address Configuration Information is sent to the UE on a per PDU Session basis. The same PDU session can be used by multiple ECS providers.
The SMF does not need to be aware of the internal structure of the ECS Address Configuration Information.
6.5.2.2 ECS Address Configuration Information Provisioning to the UE
If the UE hosts an EEC and supports transferring the ECS address received from the 5GC to the EEC, the UE indicates in the PCO at PDU Session establishment that it supports the ability to receive ECS address(es) via NAS and to transfer the ECS Address(es) to the EEC(s) (see TS 23.502 [3]). As described in TS 23.502 [3], if the UE supports the ability to receive ECS Address Configuration Information via NAS and to transfer the ECS address(es) to the EEC(s), the UE may receive ECS Address Configuration Information from the SMF via PCO during PDU Session Establishment and/or during PDU Session Modification procedures. If Spatial Validity Condition of ECS is provided, the UE uses the appropriate ECS as defined in TS 23.558 [5].
The SMF may receive ECS Address Configuration Information and associated spatial validity conditions from the UDM together with SM subscription information. The UDM in the HPLMN may provide the SMF (in HPLMN in HR case, in VPLMN in LBO case) with ECS address configuration information that depends on the serving PLMN of the UE.
The SMF determines the ECS Address Configuration Information to be sent to the UE based on UE subscription information received from UDM(as described in clause 4.15.6.3d-2 of TS 23.502 [3]).
The SMF may decide to send updated ECS Address Configuration Information to the UE based on locally configured policy or updated UE subscription information. The PDU Session Modification procedure is used to send updated ECS Address Configuration Information to the UE as described in clause 4.3.3 of TS 23.502 [3].
NOTE 1: In home routed sessions, the ECS Address Configuration Information comes from the H-SMF. The traffic to the indicated Edge Configuration Server(s) can be transmitted via a PDU Session with local breakout.
NOTE 2: Although the Service Provisioning procedure with the ECS can take place over a HR session, the UE needs to establish an LBO PDU Session to access the EES(s) and EAS(s) in VPLMN. As the UE is not aware of whether a PDU Session is working in LBO or in HR mode, in this case the PDU Session used to access the EES(s) would need to use another combination of (DNN, S-NSSAI) than the PDU Session working in HR mode.
NOTE 3: The Service Provisioning procedure is described in TS 23.558 [5].
6.5.2.3 ECS Address Provisioning by a 3rd Party AF
As described in TS 23.558 [5], the Edge Configuration Server can be deployed in a 3rd party domain by a service provider. An AF in the MNO domain or, if the Edge Configuration Server is deployed in a 3rd party domain by a service provider, a 3rd party AF can use Nnef_ParameterProvision to provide, update, or delete AF provided ECS Address Configuration Information applying on a DNN and/or S-NSSAI for a group of UE, or any UE (See clause 4.15.6.2 of TS 23.502 [3]).
When the AF uses Nnef_ParameterProvision to send a new AF provided ECS Address Configuration Information to the UDM (e.g. because on Application layer activity, etc.), the UDM may notify the impacted SMF(s) of the updated Subscription provided ECS Address Configuration Information and the new ECS Address Configuration Information will be sent to the UE(s) in a PDU Session Modification procedure.
NOTE 1: Mechanisms to avoid signalling overload when the AF uses Nnef_ParameterProvision to send new ECS Address Information to many UEs are defined in TS 23.502 [3].
NOTE 2: The AF provides ECS Address Configuration Information to 5GC that target any UEs or a group of UE.
6.5.2.4 ECS Address Provisioning by MNO
The ECS Address Configuration Information can be provisioned by the MNO subscription provisioning in UDM.
6.5.2.5 Interworking with EPC
In interworking scenarios, if the UE hosts an EEC and supports transferring the ECS address received from the 5GC to the EEC, the UE indicates in the PCO at PDN Connection establishment that it supports the ability to receive ECS address(es) via NAS and to transfer the ECS Address(es) to the EEC(s) (see TS 23.502 [3]) and the bearer modification procedure without bearer QoS update procedure is used to send updated ECS Address Configuration Information to the UE as described in clause 4.11.0a.5 of TS 23.502 [3].