Patent ID: 8644222

Claim:
A wireless communication system in which a base station apparatus and a mobile station apparatus are configured to communicate with each other using a plurality of component carriers, the wireless communication system comprising: said base station apparatus which is configured to: transmit, to said mobile station apparatus, first control information indicative of a set of physical random access channel resources corresponding to a specific downlink component carrier, and transmit, to said mobile station apparatus, second control information including information instructing to start a random access procedure and information indicative of a preamble; and said mobile station apparatus which is configured to: set a set of said physical random access channel resources in accordance with said first control information received from said base station apparatus, determine a group of preambles to be selected, upon receipt of said second control information from said base station apparatus, select one physical random access channel resource from among the set of said physical random access channel resources in accordance with said second control information, randomly select one preamble from among said determined group of preambles in a case of all said pieces of said information indicative of a preamble being set to zero, transmit said selected a-preamble using said selected physical random access channel resource on an uplink component carrier, and receive, on said specific downlink component carrier, a random access response corresponding to said transmitted preamble and including an uplink grant used for an allocation of a physical uplink shared channel resource on said uplink component carrier.