MOBILE COMMUNICATION SYSTEM, BASE STATION DEVICE, MOBILE STATION DEVICE, AND MOBILE COMMUNICATION METHOD

摘要

When a base station device has judged that a mobile station device should execute a random access, it is judged whether a reserved signature is available. A valid time during which the mobile station device can use the signature is decided and the end time of the valid period is calculated. The signature and the calculated end time are contained in a random access preamble allocation message, which is transmitted to the mobile station device. The mobile station device extracts the signature and the end time from the random access preamble allocation message and decides a random access channel through which the random access preamble containing the signature can be transmitted according to the extracted end time. Thus, it is possible to provide a base station device which can effectively perform communication with a mobile station device by allocating a signature to another mobile station even during a signature valid period.