Radio communication system and method therefor and portable radio communication unit and method therefor

摘要

The invention is to achieve normal authentication communication. For example, upon reception of a request from an ECU, a portable electronic key sends information on the presence or absence of another electronic key (YES in S31, S32) to try to receive it. When the portable electronic key receives information on the presence or absence of another electronic key from another portable electronic key in addition to information on the presence or absence of another electronic key from itself (YES in S33), the portable electronic key determines that a plurality of portable electronic keys including itself are present in the communication range of the ECU, and executes the following processes. Specifically, the portable electronic key generates random numbers, determines a response delay time on the basis of the random numbers, and sends an answer to the ECU after a lapse of the response delay time (S34 to S36). The invention can be applied to a vehicle anti-theft system.