Mobile communication system, base station apparatus and mobile station apparatus
When a mobile station 200 is out of uplink synchronization, an efficient procedure is realized no matter whether a dedicated signature can be allocated. In a mobile communication system in which a base station 100 transmits a DL-SCH to a mobile station 200 , when the mobile station 200 is out of uplink synchronization and detects resource allocation, the mobile station 200 performs a random access to the base station 100 . When the base station 100 detects a signature by using a random access channel, it transmits a preamble response to the mobile station 200 . When the mobile station 200 receives the preamble response, it transmits Message 3 to the base station 100.
1. A mobile station apparatus that performs a random access, the mobile station apparatus comprising:
a communication unit configured to perform the random access based on a dedicated signature in response to detecting the dedicated signature informed by a base station apparatus, and
said communication unit further configured to perform the random access based on a randomly selected signature in response to detecting a signature informed by the base station apparatus and not reserved as a dedicated signature.
2. A mobile communication system, comprising:
a base station apparatus; and
a mobile station apparatus, wherein
the base station apparatus informs the mobile station apparatus of a dedicated signature or a signature not reserved as a dedicated signature, and
the mobile station apparatus performs a random access based on the dedicated signature in response to detecting the dedicated signature, and the mobile station apparatus performs a random access based on a randomly selected signature in response to detecting the signature not reserved as a dedicated signature.
3. A method for performing a random access by a mobile station apparatus, the method comprising:
performing the random access based on a dedicated signature in response to detecting the dedicated signature informed by a base station apparatus; and
performing the random access based on a randomly selected signature in response to detecting a signature informed by the base station apparatus and not reserved as a dedicated signature.
4. The method for performing a random access by a mobile station apparatus according to claim 3 , further comprising:
detecting whether a base station apparatus informs the mobile station apparatus of the dedicated signature.