| 摘要 |
<p>PROBLEM TO BE SOLVED: To securely transfer information without the lack of information when information is transferred between plural responders and one question unit in a communication area. SOLUTION: A road machine transmits an inquiry signal (communication 1) and an on-vehicle machine stores and returns present time in the on-vehicle machine, which is received at first, as start time (communication 2). When answers are given from the plural on-vehicle machines, the road machine selects the on-vehicle machine with the earliest time among the plural received start times as the on-vehicle machine of a communication object. The on-vehicle machine which passes a communication area the earliest is selected and an answer signal for a handshake is transmitted to the on-vehicle machine (communication 3). The on-vehicle machine gives the reply (communication 4). When the handshake between the road machine and the on-vehicle machine is realized, data is transferred between the road machine and the on-vehicle machine.</p> |
