| 摘要 |
<p>1. Method of search, by a mobile unit, for a free time slice on a time-shared communications channel, for sending a standardised message including at least one indication of geographic position, the mobile unit participating with others located in the same geographical area in an anti-collision system in which the time is, in a conventional way, divided into reproducible time periods T, each period including a number N of time slices marked 1, 2, 3,...i,...N, in which system access to a time slice for sending the message from the mobile unit is done by marking free time slices in the course of at least one listening period T, then by random choice of a slice i from among the slices marked as free, the method being characterised in that: a) for at least one period after the mobile unit has decided to take up slice i, the time of the slice i is distributed randomly into receiving subslices R and transmitting subslice E; b) as long as no transmission from another mobile unit has been received during the receiving subslices R, a transmission is commenced or continued during the following transmission subslices E of the slice i in progress, and the slice i is kept in the course of the following period; c) if a transmission is received from another mobile unit in the course of a reception subslice R no or no further transmission is made in the course of the following transmission periods E provided in the slice i in progress, and a new free slice j is chosen; d) the operations a and b above are done again on slice j, and if a transmission is received from another mobile unit operation C is done again. <IMAGE></p> |
