Patent ID: 8175052

Claim:
A method of performing a random access by a user equipment (UE) in a mobile communication system, the method comprising: transmitting a random access preamble to a network; monitoring downlink control channel information identified by first type identifier information after transmitting the random access preamble; receiving downlink shared channel information including a medium access control packet data unit (MAC PDU) when the downlink control channel information, identified by the first type identifier information, which corresponds to the UE's transmission of the random access preamble, is received, wherein the received MAC PDU comprises a header part and N random access responses, where N is greater than 1, the header part includes N subheaders, each of the N subheaders corresponds to a random access response among the N random access responses, and wherein each of the N subheader comprises second type identifier information; and processing a specific random access response among the N random access responses when the second type identifier information of a specific subheader, which corresponds to the specific random access response, corresponds to the transmitted random access preamble.