Patent ID: 7848346

Claim:
A method of performing a random access to a base station by a terminal, the method comprising: transmitting, by the terminal, a random access preamble to the base station; receiving, from the base station in response to the random access preamble, a random access response message having a format of medium access control protocol data unit (MAC PDU) including only a backoff indicator subheader in a header portion of the MAC PDU; and considering a random access response reception corresponding to the transmitted random access preamble as a reception failure, and performing a subsequent procedure for a random access responses reception failure, wherein the terminal is adapted to consider a random access response reception corresponding to the transmitted random access preamble as a reception failure, if no random access response is received within a random access response window having a predetermined time length, or if none of all received random access responses contains a random access preamble identifier corresponding to the transmitted random access preamble, wherein a case in which none of all received random access responses contains the random access preamble identifier corresponding to the transmitted random access preamble comprises: a first case in which all received random access responses contain random access preamble identifiers that do not match the transmitted random access preamble; or a second case in which the random access response message having the format of MAC PDU including only the backoff indicator subheader in the header portion of the MAC PDU is received.