Patent ID: 7039407

Claim:
A method for determining a value of a first counter of a wireless communication system serving a user station which moves at a time of handover from a first coverage area controlled by a first controller into a second coverage area controlled by a second controller, the method comprising: maintaining in the first controller, substantially until the time of the handover, the value of the first counter which is incremented periodically, sending, at substantially the time of handover, a request to the user station for a constant value representing a difference between the value of the first counter and a value of a second counter, the value of the second counter being maintained in the second coverage area and incremented periodically with the first counter; and receiving an updated value of the second counter at a later time at the second controller and determining an updated value of the first counter at that later time based on the constant value, the value of the first counter at the time of handover and the value of the second counter at the later time.