When an MCData user using a ProSe-enabled UE wants to communicate with a specific MCData group or MCData user using ProSe capabilities, the MCData client enables the use of the ProSe layer procedures for public safety, as specified in TS 23.303
For an off-network MCData group communication, the MCData client obtains configuration data such as the user info ID of the MCData user sending data and the ProSe Group IP multicast address and ProSe Layer-2 Group ID associated to the target MCData group (as described in clause 18.104.22.168 of TS 23.280
), and provides it to the ProSe layer. The ProSe Layer-2 Group ID of the target MCData group may be used by the ProSe layer as the target group info and the discovery group ID (defined in TS 23.303
Prior to initiating an off-network MCData group communication, a group member discovery procedure may be initiated to identify whether other members of the target MCData group are in the proximity of the MCData user sending data, as described in the ProSe direct discovery for public safety use procedure in TS 23.303
. The off-network MCData group communication using the ProSe capability is based on the one-to-many ProSe direct communication procedure for public safety use described in TS 23.303
For an off-network one-to-one MCData communication, the MCData client obtains configuration data such as the ProSe discovery group ID and user info ID of the target MCData user from the "List of MCData users this MCData user is authorized to initiate a one to-one communication"
in the MCData user profile and requests the IP address of the MCData UE associated with the target MCData user from the ProSe layer.
The MCData client enables the ProSe layer to determine the IP address for the communication with the target MCData UE by providing the ProSe discovery group ID and user info ID (as defined in TS 23.303
) associated to the target MCData user. This may trigger the ProSe direct discovery for public safety use procedure to identify whether the target MCData user is in the proximity of the MCData user sending data. The user info ID of the target MCData user is used by the ProSe layer as the target info (as defined in TS 23.303
The ProSe layer can then provide the IP address related to the target MCData user to the MCData client to initiate the off-network one-to-one MCData communication based on the one-to-one ProSe direct communication procedure described in TS 23.303
The off-network MCData communication procedures using the ProSe capabilities are described within the corresponding clauses of each MCData capability, e.g. SDS procedures for off-network are described in clause 7.4.3
and file distribution procedures for off-network are described in clause 7.5.3