Registration of mobile packet data terminals after disaster

摘要

Registration attempts by a terminal using a contention protocol to communicate with a central system are controlled by transmitting a registration index from the central system to the terminal at specified temporal periods, and modifying the value of the registration index when the terminal should attempt to register with the central system. A mode flag is transmitted from the central system to the terminal at predetermined temporal intervals, and the value of the mode flag is modified when the central system is recovering from a disaster so that the terminal refrains from immediately attempting to register with the central system. During disaster recovery, the terminal is able to associate itself with one of a plurality of sub-intervals. The central system transmits a sub-interval designator to the terminal at regular temporal periods during disaster recovery. The central system modifies the value of the sub-interval designator after a predetermined number of the regular temporal periods. The flow of registration attempts by a community of terminals is smoothed from a situation wherein essentially the entire community of terminals is contending to register after a disaster to a situation wherein subsets of the community try to register in respective sub-intervals after the disaster.