System and associated method of maintaining packet switching capability in a cellular network

A mobile communication method in which a mobile station performs a location registration to one of plural exchanges which manage a location registration area where the mobile station is located, in a mobile communication system where a radio network controller is connected to the plural exchanges, the mobile communication method comprising:

• storing, at the mobile station, a temporary identifier of the mobile station which is allocated in a location registration area where the mobile station has performed the location registration, and the temporary identifier includes an identifier of the one of the plural exchanges that has performed the location registration of the mobile station;
• detecting, at the radio network controller, an inaccessibility to a specific exchange among the plural exchanges when a failure or congestion occurs at the specific exchange;
• notifying the mobile station by an access restriction signal under control of the radio network controller, the access restriction signal including an identifier of the specific exchange in which the failure or congestion occurred;
• notifying the mobile station of an identifier of the location registration area under control of the radio network controller;
• determining whether the identifier of the specific exchange notified by the access restriction signal from the radio network controller matches the identifier of the exchange that has performed the location registration of the mobile phone and which is stored in the temporary identifier of the mobile station;
• stopping, at the mobile station, transmission of signals to the exchange which has performed the location registration of the mobile station when the identifier of the specific exchange notified by the access restriction signal from the radio network controller matches the identifier of the exchange stored in the temporary identifier of the mobile station;
• and
• enabling, at the mobile station, transmission of signals to the exchange which has performed the location registration of the mobile station when the identifier of the specific exchange notified by the access restriction signal from the radio network controller is different than the identifier of the exchange stored in the temporary identifier of the mobile station,
• wherein the access restriction signal includes a location or a bit number of the identifier of the specific exchange in which the failure or congestion occurred, the method further comprising:
• determining whether the identifier of the specific exchange in which the failure or congestion occurred is the identifier of the exchange, stored in the temporary identifier, of the one of the plural exchanges that has performed the location registration of the mobile station based on the location or the bit number included in the access restriction signal.

A mobile station for performing location registration in a mobile communication system to one of plural exchanges managing a location registration area where the mobile station is located, the mobile communication system including a radio network controller connected to the plural exchanges, the mobile station comprising:

• a determiner configured to determine whether an identifier of an exchange received in an access restriction signal from the radio network controller matches an identifier of the one of the plural exchanges that has performed the location registration of the mobile station, the access restriction signal is broadcast from the radio network controller when a failure or congestion occurs in one of the plural exchanges, and the access restriction signal includes an identifier to identify an exchange in which the failure or congestion occurred;
• and
• a communication controller configured to enable transmission of signals to the exchange which has performed the location registration of the mobile station when the identifier of the exchange received in the access restriction signal from the radio network controller is different than the identifier of the exchange that has performed the location registration of the mobile station,
• wherein the access restriction signal includes a location or a bit number of the identifier of the specific exchange in which the failure or congestion occurred;
• the identifier of the one of the plural exchanges that has performed the location registration of the mobile station is included in a temporary identifier of the mobile station;
• and
• the communication controller determines if the identifier of the exchange in which the failure or congestion occurred is different from the identifier of the exchange of the one of the plural exchanges that has performed the location registration of the mobile station based on the location or the bit number included in the access restriction signal.