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Channel access method for powerline carrier based media access control protocol

  • US 7,570,656 B2
  • Filed: 06/18/2001
  • Issued: 08/04/2009
  • Est. Priority Date: 06/18/2001
  • Status: Expired due to Fees
First Claim
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1. A method of accessing a channel in a communication transceiver coupled to a communications channel, the transceiver adapted to provide carrier sense signals including a fast carrier detect (FCD) signal to predict the early start of transmission on said channel and having a high false alarm rate and a carrier detect (CD) signal having a low false alarm rate and indicating that a transmission is starting, said method comprising the steps of:

  • establishing a channel contention period divided into a plurality of time slots, the width of each time slot substantially equal to the time of said FCD signal;

    initializing a backoff counter with a backoff count equal to a random number of time slots;

    decrementing said backoff counter while said medium is idle;

    suspending said backoff counter upon receipt of a FCD signal;

    resuming decrementing said backoff counter upon failure of a CD signal to arrive within a CD time, said CD time proportional to a time period during which the arrival of a CD signal is expected in the event a transmission is received;

    deferring transmission until a next contention period upon receipt of a CD signal; and

    starting transmission upon expiration of said backoff counter.

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