In the present disclosure, a UE transmits a random access preamble (RAP) on a physical random access channel (PRACH) and a control channel (CCCH) service data unit (SDU) on a physical uplink shared channel (PUSCH); and receives a medium access control (MAC) protocol data unit (PDU) based on transmitting the RAP and the CCCH SDU. The MAC PDU includes a first part, and a second part after the first part. The first part includes multiple UE contention resolution identities (UE CRIDs).