1. A method for a User Equipment (UE) operating in a wireless communication system, the method comprising:configuring a Contention Based (CB) grant and a CB-Radio Network Temporary Identifier (RNTI) associated with the CB grant;
transmitting a first Medium Access Control (MAC) Protocol Data Unit (PDU) including an identifier of the UE without uplink data using the CB grant;
receiving a CB MAC Control Element (CE) indicated by a Physical Downlink Control Channel (PDCCH) addressed to the CB-RNTI in response to the MAC PDU transmission; and
transmitting a second MAC PDU including the identifier of the UE without the uplink data using the CB grant, when the CB MAC CE does not include the identifier of the UE.