COMMUNICATION SYSTEM, BASE STATION DEVICE, MOBILE STATION DEVICE, RANDOM ACCESS TRANSMISSION METHOD, AND INTEGRATED CIRCUIT

摘要

In a communication system, a base station device (2) and a mobile station device (1) aggregate a plurality of serving cells to communicate. The serving cells include a deactivated state showing a state where the serving cells are not used for communication and an activated state showing a state where the serving cells are used for communication. The aggregated plurality of serving cells are configured by a primary serving cell which is not deactivated and at least one secondary serving cell which is activated or deactivated. When setting information necessary for a random access procedure in the primary serving cell and the secondary serving cell, the base station device requests the mobile station device to start the random access procedure in the secondary serving cell by activating the secondary serving cell set with the information necessary for the random access procedure. When the secondary serving cell set with the information necessary for the random access procedure by the base station device is activated (S201, S301), the mobile station device starts the random access procedure in the secondary serving cell (S202, S302).