| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve correct authentication communication even if a plurality of portable radio communication devices are present in a communication zone of a fixed radio communication device. <P>SOLUTION: There is provided a radio communication system. According to the system, a portable electronic key, upon reception of a request from an ECU, for instance, transmits other electronic key existence checking information (S31 YES, S32), and it tries to receive the information. If the portable electronic key receives the other electronic key existence checking information from other portable electronic keys, other than the portable electronic key existence information of itself (S33 YES), determination is made that a plurality of portable keys inclusive of itself are present in the communication zone of the ECU, and the following processing is executed. That is, the portable electronic key generates random numbers, and determines a response delay time, based on the random numbers, followed by transmitting an answer to the ECU (S34 to S36) after the lapse of the response delay time. The radio communication system is applicable to a vehicle theft preventing system. <P>COPYRIGHT: (C)2008,JPO&INPIT |
