| 摘要 |
PROBLEM TO BE SOLVED: To collect vehicle information at a high speed from each motor vehicle in each service area without radio interference by using a plurality of base stations. SOLUTION: Base stations 2 and 3 continuously transmit poling group signals P1 and P2 including the group signal of vehicles by adding base station information to the signals P1 and P2 and each vehicle receives the signals P1 and P2 without radio interference and judges whether or not the vehicle is requested to answer to the signals P1 and P2. When the vehicle judges that the vehicle is requested to answer, the vehicle decides the time slot to be used exclusively by the vehicle for the answer from the base station information and its own vehicle number and transmits its own vehicle information within the time slot.
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