Patent ID: 8194694

Claim:
A mobile communications system for performing communication using Non-contention based Random Access, in which different random access channel numbers are assigned respectively to a plurality of random access channels in one frame and a configuration of the random access channel numbers is the same in each frame, wherein a base station apparatus, by notifying a mobile station apparatus of a signature number of a signature for the Non-contention based Random Access and one of the random access channel numbers, assigns a signature corresponding to the signature number and a random access channel corresponding to the random access channel number in each frame, covering a plurality of sequential frames, the mobile station apparatus transmits a random access preamble including the signature corresponding to the notified signature number, using the random access channel corresponding to the notified random access channel number in a first frame, and when no response to the random access preamble is detected, the mobile station apparatus transmits the random access preamble including the signature corresponding to the notified signature number once again, using the random access channel corresponding to the notified random access channel number in a second frame.