WIRELESS COMMUNICATION SYSTEM, ITS CONTROL METHOD, AND ITS PROGRAM

摘要

PROBLEM TO BE SOLVED: To prevent unauthorized use of a cellular phone or the like due to camouflage of an electric field strength level by means of a repeater.

SOLUTION: In order to judge in a wireless communication system that a user 12 carries a cellular phone 1 when a receiving signal strength indicator (RSSI) value (first electric field strength level) of a telegram message from the cellular phone 1 to a pocket key 2 exceeds a threshold value, broadcast reception is carried out by a fixed wireless device 3 provided at a relative distance making it possible to always receive the telegram message from the cellular phone 1 with a substantially constant RSSI value (second electric field strength level). When the RSSI value (second electric field strength level) is larger than a determined upper limit value, it is judged that the electric field strength level is camouflaged by means of a radio wave repeater or the like, and then the functions of the related devices are locked so that any unauthorized speech communication or unjust account settlement may not be carried out. Thus, unauthorized use can be prevented.

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