Mobile communication system, base station apparatus and mobile station apparatus

A processing method in a base station configured to communicate with a mobile station, the processing method comprising:

• transmitting a parameter indicating a value to the mobile station, wherein
• the value represents a count of randomly selectable signatures for the mobile station and a count of non randomly selectable signatures for the mobile station,
• a signature is randomly selected, by the mobile station, from the randomly selectable signatures specified based on the value,
• each signature of the randomly selectable signatures is one of a constant number of usable signatures,
• each signature of the non randomly selectable signatures is one of the constant number of the usable signatures, and
• each signature of all the usable signatures is usable in random access.

A mobile station configured to communicate with a base station, comprising:

• circuitry configured or programmed to acquire a parameter indicating a value from the base station, wherein
• the value represents a count of randomly selectable signatures for the mobile station, and a count of non randomly selectable signatures for the mobile station,
• a signature is randomly selected, by the mobile station, from the randomly selectable signatures specified based on the value,
• each signature of the randomly selectable signatures is one of a constant number of usable signatures,
• each signature of the non randomly selectable signatures is one of the constant number of the usable signatures, and
• each signature of all the usable signatures is usable in random access.

A processing method in a mobile station configured to communicate with a base station, the processing method comprising:

• acquiring a parameter indicating a value from the base station, wherein
• the value represents a count of randomly selectable signatures for the mobile station, and a count of non randomly selectable signatures for the mobile station,
• a signature is randomly selected, by the mobile station, from the randomly selectable signatures specified based on the value,
• each signature of the randomly selectable signatures is one of a constant number of usable signatures,
• each signature of the non randomly selectable signatures is one of the constant number of the usable signatures, and
• each signature of all the usable signatures is usable in random access.