The Announcing UE (UE-1) sends a Ranging/SL Positioning Announcement message. The Ranging/SL Positioning Announcement message includes the Type of Discovery Message, security protection element, RSPP metadata information, the User Info ID of Announcing UE and optionally serving PLMN ID of Announcing UE.
Announcing UE can be SL Reference UE, Located UE and SL Positioning Server UE.
The Destination Layer-2 ID used to send the Ranging/SL Positioning Announcement message is configured in
clause 5.2.
The Source Layer-2 ID to send the Ranging/SL Positioning Announcement message is self-assigned by the Announcing UE.
Announcing UE sends the Announcement message only if it is authorized to be the corresponding UE role in RSPP metadata information.
The User Info ID of Announcing UE is the Announcing UE's Application Layer ID.
A Monitoring UE determines the Destination Layer-2 ID for signalling reception based on the configuration in
clause 5.2.
A Monitoring UE selects the Announcing UE based on the information received in step 1.
Announcing UE may include an indication of whether its serving network supports Ranging/SL Positioning.
Announcing UE may include its serving PLMN ID in the Announcement message if its role is Located UE.
The contents of RSPP metadata information (e.g. the UE Role) are defined in
clause 6.11 of TS 38.355.