5.3.5 Announcing Alert Procedures – restricted discovery

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

5.3.5.1 Announcing Alert (non-roaming)

Figure 5.3.5.1-1: Announcing Alert (non-roaming)

In non-roaming case, when the ProSe Function in the HPLMN of the announcing UE receives a Monitor Request from a UE which is in the vicinity of the announcing UE and detects the associated Announcing Enabled indication stored in the announcing UE context, the ProSe Function triggers an Announcing Alert procedure towards the announcing UE in HPLMN.

1. The HPLMN ProSe Function informs the announcing UE with the Announcing Alert Request (RPAUID, ProSe Restricted Code, Discovery Entry ID) message. The RPAUID indicates what the UE is interested to announce which was obtained in step 0 of Announce Request procedure in clauses 5.3.3.2A and 5.3.3.3A. The Application ID represents a unique identifier of the UE application that has triggered the transmission of the Discovery Request message. The ProSe Restricted Code is retrieved from the announcing UE context. If restricted Direct Discovery with application-controlled extension was requested by the announcing UE, the ProSe Restricted Code is replaced by the ProSe Restricted Code Prefix, and the Announcing Alert Request message also contains the ProSe Restricted Code Suffix pool for the RPAUID retrieved from the announcing UE context.

NOTE: How the ProSe Function in the HPLMN determines whether the announcing UE and the monitoring UE are close enough to trigger the Announcing Alert procedure is left to the implementation of ProSe Function.

2. The UE responds with an Announce Alert Response message to the ProSe Function. Upon receiving the Announce Alert Response message the ProSe Function removes the Announcing Enabled indication associated to that ProSe Restricted Code from the user context.

3. The UE may start announcing the provided ProSe Restricted Code in the serving PLMN, using the radio resources authorised and configured by E-UTRAN to be used for ProSe as defined in RAN specifications.

5.3.5.2 Announcing Alert (roaming)

Figure 5.3.5.2-1: Announcing Alert (roaming)

The UE is only allowed to announce in the carrier frequency signalled from serving PLMN. When inter-PLMN discovery transmission is supported, the carrier frequency may be operated by Local PLMN.

In roaming case or UE performs inter-PLMN discovery transmission, when the ProSe Function in the HPLMN of the announcing UE receives a Monitor Request from a UE which is in the vicinity of the announcing UE and detects the associated Announcing Enabled indication stored in the UE context, the ProSe Function triggers an Announcing Alert procedures towards the announcing UE in VPLMN or Local PLMN.

1. The HPLMN ProSe Function informs the ProSe Function in VPLMN or Local PLMN with the Announce Authorization (RPAUID, Application ID, validity timer, ProSe Restricted Code, UE Identity, Discovery Entry ID) message. The RPAUID and Application ID correspond to the request from the UE, whereas the ProSe Restricted Code indicates the assigned code for this request and retrieved from the announcing UE context. The request shall include the UE identity information e.g. IMSI or MSISDN and validity timer in order to allow the ProSe Function in VPLMN or Local PLMN to perform charging. The validity timer indicates for how long this ProSe Restricted Code is going to be valid. If the ProSe Function in VPLMN or Local PLMN receives the same Discovery Entry ID in a subsequent Announce Authorization message, it updates the announcing UE’s corresponding discovery entry replacing the existing ProSe Restricted Code and validity timer with the last received ones.

NOTE How the ProSe Function in the HPLMN determines whether the announcing UE and the monitoring UE are close enough to trigger the Announcing Alert procedure is left to the implementation of ProSe Function.

2. The ProSe Function in VPLMN or Local PLMN authorizes the UE to perform Restricted ProSe Discovery announcing.

3. The HPLMN ProSe Function informs the announcing UE with the Announcing Alert Request (RPAUID, ProSe Restricted Code, Discovery Entry ID) message. The RPAUID indicates what the UE is interested to announce which was obtained in step 0 of Announce Request procedure in clauses 5.3.3.2A and 5.3.3.3A. The Application ID represents a unique identifier of the UE application that has triggered the transmission of the Discovery Request message. The ProSe Restricted Code is retrieved from the announcing UE context. If restricted Direct Discovery with application-controlled extension was requested by the announcing UE, the ProSe Restricted Code is replaced by the ProSe Restricted Code Prefix, and the Announcing Alert Request message also contains the ProSe Restricted Code Suffix pool for the RPAUID retrieved from the announcing UE context.

4. The UE responds with an Announce Alert Response message to the ProSe Function. Upon receiving the Announce Alert Response message the ProSe Function removes the Announcing Enabled indication associated to that ProSe Restricted Code from the user context.

5. The UE may start announcing the provided ProSe Restricted Code in the serving PLMN, using the radio resources authorised and configured by E-UTRAN to be used for ProSe as defined in RAN specifications.