Systems and methods of providing communications between UEs are generally described. A notification resource indicating subsequent transmission of a discovery message is transmitted from a UE to another UE using a discovery ID selected from a limited number of discovery IDs stored in the other UE. The other UE transmits a random access request to the UE having a temporary ID. The UE may not respond if the temporary ID is already used or may transmit data transmission information scrambled by the temporary ID. The other UE transmits a contention resolution PDU to the UE and may receive an ACK to indicate ID contention is not present, or either no response or a NACK to indicate the presence of ID contention. The other UE may either select a new temporary ID or use a backoff timer to retransmit the random access request at a random time.