Content for  TS 23.558  Word version:  19.0.0

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0  Introductionp. 17

Edge Computing is a network architecture concept that enables cloud computing capabilities and service environments, which are deployed close to the UE. It promises several benefits such as lower latency, higher bandwidth, reduced backhaul traffic and prospects for new services compared to the cloud environments. This technical specification provides application layer architecture and related procedures for enabling edge applications over 3GPP networks.

1  Scopep. 18

The present document specifies the application layer architecture, procedures and information flows necessary for enabling edge applications over 3GPP networks. It includes architectural requirements for enabling edge applications, application layer architecture fulfilling the architecture requirements and procedures to enable the deployment of edge applications.

2  Referencesp. 18

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
TR 21.905: "Vocabulary for 3GPP Specifications".
TS 23.501: "System architecture for the 5G System (5GS); Stage 2".
TS 23.502: "Procedure for the 5G System (5GS); Stage 2".
TS 29.522: "5G System; Network Exposure Function Northbound APIs; Stage 3".
TS 29.122: "T8 reference point for northbound Application Programming Interfaces (APIs)".
TS 23.222: "Functional architecture and information flows to support Common API Framework for 3GPP Northbound APIs; Stage 2".
TS 23.271: "Functional stage 2 description of Location Services (LCS)".
TS 36.305: "Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Stage 2 functional specification of User Equipment (UE) positioning in E-UTRAN".
TS 23.273: "5G System (5GS) Location Services (LCS); Stage 2".
TS 38.305: "NG Radio Access Network (NG-RAN); Stage 2 functional specification of User Equipment (UE) positioning in NG-RAN".
TS 23.401: "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access".
TS 23.503: "Policy and charging control framework for the 5G System (5GS); Stage 2".
TS 23.434: "Service enabler architecture layer for verticals; Functional architecture and information flows; Stage 2".
TS 23.286: "Application layer support for Vehicle-to-Everything (V2X) services; Functional architecture and information flows ".
ETSI ISG MEC ETSI GS MEC 003 V2.1.1 (2019-01), "Multi-access Edge Computing (MEC); Framework and Reference Architecture"
[16]  Void
TS 23.682: "Architecture enhancements to facilitate communications with packet data networks and applications".
TS 23.288: "Architecture enhancements for 5G System (5GS) to support network data analytics services".
GSMA PRD OPG.02 Operator Platform Telco Edge Requirements version 4.0, available at
TS 23.548: "5G System Enhancements for Edge Computing".
TS 23.032: "Universal Geographical Area Description (GAD)".
TS 28.538: "Management and orchestration; Edge Computing Management".
TS 33.558: "Security aspects of enhancement of support for enabling edge applications".
TS 32.240: "Telecommunication management; Charging management; Charging architecture and principles".
TS 32.257: "Telecommunication management;Charging management;Edge computing domain charging".
TS 23.433: "Service Enabler Architecture Layer for Verticals (SEAL); Data Delivery enabler for vertical applications".
TR 23.958: "Edge Application Standards in 3GPP and Alignment with External Organizations".
TS 23.436: "Functional architecture and information flows for Application Data Analytics Enablement Service".

3  Definitions of terms, symbols and abbreviationsp. 19

3.1  Termsp. 19

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:
A set of data about the Application Client that resides in the Edge Application Server.
Application Context Relocation:
Refers to the end-to-end service continuity procedure described in clause 8.8.
Application Context Transfer:
Refers to the transfer of the Application Context between the source Edge Application Server and the target Edge Application Server, which is a part of the service continuity procedure described in clause 8.8.
Application Server:
Application software resident in the cloud performing the server function.
Associated EES:
One or multiple EES(s) which support all bundled EAS within the same EDN, and each EES of the associated EES(s) serving all or part of EAS list of the bundle EAS.
Common EAS:
An EAS which can serve a group of UEs using the same application.
Common EES:
An EES which has a Common EAS registered with it.
Edge Computing:
A concept, as described in TS 23.501, that enables operator and 3rd party services to be hosted close to the UE's access point of attachment, to achieve an efficient service delivery through the reduced end-to-end latency and load on the transport network.
Edge Computing Service Provider:
A mobile network operator or a 3rd party service provider offering Edge Computing service.
Edge Data Network:
A local Data Network that supports the architecture for enabling edge applications.
EEC Context:
A set of data about the Edge Enabler Client that resides in the Edge Enabler Server.
Edge Enabler Layer:
Refers to the overall functionality provided by the entities such as Edge Enabler Client, Edge Enabler Server, Edge Configuration Server and Cloud Enabler Server, in support of applications as per the architecture defined in clause 6.
Edge Hosting Environment:
An environment providing support required for Edge Application Server's execution.
Instantiable EAS:
EAS type for which the instantiation trigger from the Edge Enabler Layer is considered by the ECSP management system for instantiating EAS.
Main EAS:
An EAS in EAS bundle taking the role of controlling the ACR for EAS bundle in network side decided ACR scenario.
Partner ECS:
Refers to an ECS deployed by a partner ECSP.
Partner ECSP:
An ECSP with whom there is a service level agreement for resource sharing for roaming or federation or both.

3.2  Symbolsp. 20


3.3  Abbreviationsp. 20

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.
Application Client
Application Client Identification
Application Context Relocation
Application Context Transfer
API Exposing Function
Application Function
Access Point Name
Application Service Provider
Common API Framework
Cloud Application Server
Cloud Enabler Server
Data Network
Data Network Access Identifier
Data Network Name
Home Edge Configuration Server
Home Edge Enabler Server
Edge Application Server
Edge Application Server Identification
Edge and Cloud Interworking
Edge Configuration Server
Edge Configuration Server - Edge Repository
Edge Computing Service Provider
Edge Data Network
Edge Enabler Client
Edge Enabler Client Identification
Edge Node Sharing
European Telecommunications Standards Institute
Edge Enabler layer
Edge Enabler Server
Edge Enabler Server Identification
Fully Qualified Domain Name
Generic Public Subscription Identifier
Global System for Mobile Communications
GSM Association
Local Area Data Network
Multi-access Edge Computing
Network Exposure Function
Operator Platform
Operator Platform Group
Policy Control Function
PDU Session Anchor
Source Edge Application Server
Source Edge Enabler Server
Service Capability Exposure Function
Service Enabler Layer Architecture
Session Management Function
Service Set Identifier
Target Edge Application Server
Target Edge Enabler Server
Tracking Area Identity
UE Route Selection Policy
Visited Edge Configuration Server
Visited Edge Enabler Server

4  Overviewp. 21

4.1  Generalp. 21

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.
Reproduction of 3GPP TS 23.558, Fig. 4.1-1: Overview of 3GPP edge computing
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.

4.2  Service provisioningp. 22

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.

4.3  Registrationp. 22

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.

4.4  EAS discoveryp. 22

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.

4.5  Capability exposure to EAS and EECp. 22

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.

4.6  Support for service continuityp. 22

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.

4.7  Securityp. 22

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

4.8  Dynamic EAS instantiation triggeringp. 22

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.

4.9  Chargingp. 22

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.

4.10  Common EAS discovery |R19|p. 23

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

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