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

摘要

A mobile station device that communicates with a base station device, including: a downlink synchronization error detecting portion that detects the occurrence of a downlink synchronization error from the measurement result of a transmission signal of the base station device; a synchronization monitoring portion that sets information showing the occurrence of a downlink synchronization error into a random access channel based on the downlink synchronization state or both the downlink and uplink synchronization states of the mobile station device; and a downlink synchronization error notifying portion that transmits the random access channel to the base station device.