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Method to optimize the bit rate of a communications channel in time-division mode

  • US 5,544,075 A
  • Filed: 07/20/1994
  • Issued: 08/06/1996
  • Est. Priority Date: 07/20/1993
  • Status: Expired due to Term
First Claim
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1. A method by which a moving body can search for an unoccupied time slot in a time-division communications channel for the transmission of a message comprising at least one information element on geographical position, the moving body participating with other moving bodies located in one and the same geographical zone in an anti-collision system in which the time is conventionally divided into reproducible time periods T, each period comprising a number N of time slots referenced 1, 2, 3 . . . i . . . N, the access to a time slot for the transmission of the message from the moving body being done by the identifying of the unoccupied time slots during at least one listening period T, followed by a random choice of one slot i from among the slots identified as being unoccupied, wherein:

  • a) for at least one period after the moving body has decided to occupy the slot i, the time of this slot i is divided randomly into reception sub-slots R and transmission sub-slots E;

    b) so long as no transmission from another moving body has been received during the reception sub-slots R, a transmission is begun or continued during the following transmission sub-slots E of the slot i in progress and the slot i is kept during the following period;

    c) if a transmission is received from another moving body during a reception sub-slot R, there is no transmission made or there is no longer any transmission made during the following transmission periods E planned in the slot i in progress, and a new unoccupied slot j is chosen;

    d) the above operations a) and b) are carried out again on the slot j, and if a transmission is received from another moving body, the operation c) is carried out again.

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