5.3.2 Overall procedure for ProSe Direct Discovery (Model A)

23.3033GPPProximity-based services (ProSe)Release 17Stage 2TS

Figure 5.3.2-1: Overall procedure for ProSe Direct Discovery

This procedure is only applied for open and restricted ProSe Direct Discovery when the ProSe enabled UE is served by E-UTRAN.

1. Service authorisation for ProSe direct services is performed for ProSe Direct Discovery as defined in clauses 5.2, and 4.5.1.

If the UE is authorised to announce:

2a. When the UE is triggered to announce, then it sends a discovery request for announcing to the ProSe Function in HPLMN as defined in clauses 5.3.3.2 and 5.3.3.3 for open ProSe Direct Discovery, and in clauses 5.3.3.2A and 5.3.3.3A for restricted ProSe Direct Discovery. In addition, for restricted ProSe Direct Discovery, the ProSe Function further interacts with the ProSe Application server for the authorization of the discovery request.

3a. If the request is successful and is provided with ProSe Application Code/ProSe Restricted Code then it starts announcing on PC5 interface.

For ProSe restricted discovery and UE requests "on demand" announcing, ProSe Restricted Code may be provided to UE after this procedure. In this case, UE waits for the ProSe Restricted Code allocation and starts to announce the ProSe Restricted Code on PC5 after receiving it in Announcing Alert procedure specified in clause 5.3.5.

NOTE 1: More details on the Access Stratum protocol of this step are provided in RAN specifications.

If the UE is authorised to monitor:

2b. When the UE is triggered to monitor, it sends a discovery request for monitoring to the ProSe Function as defined in clauses 5.3.3.4 and 5.3.3.5 for open ProSe Direct Discovery, and in clauses 5.3.3.2A and 5.3.3.3A for restricted ProSe Direct Discovery. In addition, for restricted ProSe Direct Discovery, the ProSe Function further interacts with the ProSe Application server for the authorization of the discovery request.

3b. If the request is successful and the UE is provided with a Discovery Filter consisting of ProSe Application Code(s)/ProSe Restricted Code(s) and/or ProSe Application Mask(s) it starts monitoring for these ProSe Application Codes/ProSe Restricted Codes on the PC5 interface.

NOTE 2: More details on the Access Stratum protocol of this step are provided in RAN specifications.

4b. When the UE detects that one or more ProSe Application Code(s)/ProSe Restricted Code(s) that match the filter (see clause 4.6.4.2), it reports the ProSe Application Code(s)/ProSe Restricted Code(s) to the ProSe Function as defined in clause 5.3.4.

Non roaming direct discovery procedures cover the case where both the "announcing UE" and "monitoring UE" are served by their respective HPLMN. Roaming direct discovery procedures cover the other cases.