For the purposes of the present document, the terms given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905. Application Context: Application Context Relocation: Application Context Transfer: Application Server: Associated EES: Common EAS: Common EES: Edge Computing: Edge Computing Service Provider: Edge Data Network: EEC Context: Edge Enabler Layer: Edge Hosting Environment: Instantiable EAS: Main EAS: Partner ECS: Partner ECSP:

None.

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905. AC ACID ACR ACT AEF AF APN ASP CAPIF CAS CES DN DNAI DNN H-ECS H-EES EAS EASID ECI ECS ECS-ER ECSP EDN EEC EECID ENS ETSI EEL EES EESID FQDN GPSI GSM GSMA LADN MEC NEF OP OPG PCF PSA S-EAS S-EES SCEF SEAL SMF SSID T-EAS T-EES TAI URSP V-ECS V-EES

For edge computing, it is essential that the ACs are able to locate and connect with the most suitable application server available in the EDN, depending on the needs of the application. The edge enabler layer exposes APIs to support such capabilities. The edge computing capabilities supported by 3GPP are illustrated in the Figure 4.1-1.

The application layer is a consumer of 3GPP specified edge computing capabilities. The 3GPP edge computing capabilities are typically organized as follows:

• Edge enabler layer, specified in this specification;
• Edge hosting environment, details of which are outside the scope of 3GPP;
• 3GPP transport layer, specified in TS 23.401 and TS 23.501; and
• Edge management layer, specified in TS 28.538.

Following clauses provide an overview of the features of edge enabler layer. The edge computing features defined in this specification are applicable to PLMN(s) and to SNPN(s) as 3GPP transport layer. In this specification, when PLMN is mentioned, it is also applicable for SNPN unless stated otherwise.

Service provisioning procedures supply the information required by the UE to access the edge services. The procedure takes UE's location, service requirements, service preferences and connectivity information into account to provide the required configuration. Service provisioning procedures are specified in clause 8.3.

Registration procedures specified in clause 8.4, allow entities (e.g. UE and Application Server) in the edge enabler layer to provide information about itself to other entities of the edge enabler layer.

EAS discovery procedures enable the UE to obtain information about suitable EASs of interest (specified as discovery filters) in the EDN. EAS discovery procedures are specified in clause 8.5.

The edge enabler layer exposes services towards the EASs and EECs. The exposed capabilities include the services of the Edge Enabler Layer and the re-exposed and enhanced services of the 3GPP core network. The capabilities exposed by the edge enabler layer are specified in clause 8.6 and the 3GPP network capability exposure is specified in clause 8.7. Other application layer capabilities like application enabler services and SEAL services may be exposed via edge enabler layer as per CAPIF as illustrated in Annex A.4. The edge enabler layer also supports for an EAS to expose its Service APIs (i.e., EAS Service APIs) towards the other EASs via CAPIF as specified in TS 23.222 by deploying CAPIF core function within the EES to support publish and discovery of EAS Service APIs. The details are provided in Annex A.5.4.

When a UE moves to a new location, different EASs can be more suitable for serving the UE. When no suitable EAS can be found for serving the UE, the service session may transition to a CAS. Such transitions can result from a non-mobility event also, requiring support from the edge enabler layer to maintain the continuity of the service. Support for service continuity provides several features for minimizing the application layer service interruption by replacing the S-EAS connected to the AC in the UE, with a T-EAS or CAS. Support for service continuity is further specified in clause 8.8. When an ACR event occurs, the UE's application context is transferred from the S-EAS to T-EAS. This procedure is termed the Application Context Transmission (ACT) is out of the scope of this specification.

The edge enabler layer supports secure communication amongst the enabler layer entities. Clause 8.11 provides details on EEC authentication and authorization.

The Edge Enabler Layer can interact with the ECSP management system to trigger instantiation of a suitable EAS as per application needs. Details of the EAS instantiation triggering are specified in clause 8.12.

The general architecture and principles applicable for charging of Edge enabling services provided by an ECSP to an ASP, is specified in TS 32.240.

For the purpose of Common EAS discovery, it is relevant whether the deployment is with or without ECS-ER.

The bundle EAS contains two scenarios: direct bundle, proxy bundle. Both type of bundles are provided by the ASP Direct bundle EAS: the AC interact with multiple EASs, so that the AC can obtain services from multiple EAS, then AC can process the data from multiple EASs and calculate the result based on the data obtained from multiple EASs. Proxy bundle EAS: the AC interact with one EAS (i.e. main EAS) of the EAS bundle, and the main EAS interact with other EASs, the main EAS can process the data from other EASs and calculate the result based on the data obtained from other EASs, then main EAS can provide the result to the AC.

Federation and Roaming is a scenario that UE consumes edge service involving two or more ECSPs. For example, two ECSPs (ECSP#1, ECSP#2) has business relationship that is the ECSP#2 can provide edge service to subscriber of ECSP#1, as for subscriber of ECSP#1, the ECSP#2 can be seen as partner ECSP. When ECSP#1' subscriber requires the edge service, the ECSP#1' subscriber could obtain service from ECSP#2's ECS, EES and EAS. For the purpose of EAS discovery in federation and roaming, the partner ECS discovery is described in clause 8.17.2.3. The service provisioning information retrieval procedure is used for obtaining partner ECSP's EDN information as described in clause 8.17.2.4.

When a group of UEs with a common Application Group ID requires application service, the group of UE in different EDNs may connect to multiple common EASs; in such case, EAS content synchronization is required between the common EASs in different EDNs for the UEs in the group.