Patent ID: 8908655

Claim:
A radio communication system comprising: a mobile station apparatus that carries out an initial transmission of a signal in a random access channel (RACH) using one of a plurality of sequences, and carries out at least one retransmission of the signal in the RACH using the one of the plurality of sequences; and a base station apparatus that combines the signal transmitted in the initial transmission with the signal transmitted in the retransmission from the mobile station apparatus based on the plurality of sequences, wherein: a plurality of predetermined time slots in a RACH frame for use in the initial transmission and the retransmission of the signal are set in advance for the initial transmission and the retransmission; and a transmission number of the signal is used as an index for performing a unique determination of which of the plurality of predetermined time slots in the RACH frame is used for the initial transmission and the retransmission of the signal in the transmission number, wherein, in said determination, a first time slot of the predetermined time slots is used only for the initial transmission and a second time slot of the predetermined time slots is used only for the retransmission.