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Carrier sense multiple access with collision avoidance utilizing rotating time staggered access windows

  • US 4,628,311 A
  • Filed: 10/19/1983
  • Issued: 12/09/1986
  • Est. Priority Date: 10/19/1983
  • Status: Expired due to Fees
First Claim
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1. In a communications system wherein a plurality of stations each transmit at different times to one another over a shared communications medium, each said station including detection means for detecting the presence or absence of a transmission on said communications medium, a method of controlling access by each station to said communications medium, said method comprising the steps of:

  • reserving an arbitration period of time commencing from the termination of each transmission on said medium,;

    dividing said arbitration period into a plurality of access windows;

    assigning unique arbitration addresses to stations sharing said medium;

    generating, at each station desiring access to said medium, an access control number independent of the address of said each station to be transmitted to said medium as part of its communication;

    receiving said access control number at each other station desiring access to said medium and combining said received access control number with the respective assigned address of said each other station to determine one of said plurality of access windows assigned to said each other station during the next arbitration period;

    detecting at each station the termination of a transmission transmitted over said medium;

    generating at each station a new access control number calculated from the current access control number; and

    transmitting said new access control number from any station desiring access to said medium, during its respective access window if no other station has transmitted during a previous access window in the same arbitration period.

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