×

Method of determining a start of a transmitted frame in a frame-based communications network

  • US 6,993,101 B2
  • Filed: 04/04/2001
  • Issued: 01/31/2006
  • Est. Priority Date: 04/07/2000
  • Status: Expired due to Term
First Claim
Patent Images

1. A method of determining a start of a transmitted frame at a receiver on a frame-based communications network, the method comprising:

  • providing a preamble format for the transmitted frame wherein a plurality of identical copies of a preamble symbol sequence are transmitted sequentially;

    filtering a received transmitted frame using filter coefficients matched to the preamble symbol sequence to provide a correlation sequence;

    computing a squared-magnitude of the correlation sequence;

    low-pass filtering the squared-magnitude of the correlation sequence to provide a low-pass filtered correlation signal;

    delaying the low-pass filtered correlation signal to provide a delayed low-pass filtered correlation signal;

    comparing the delayed low-pass filtered correlation signal with the low-pass filtered correlation signal to provide a correlation difference indicator;

    comparing the correlation difference indicator with a first fixed predetermined threshold to provide a threshold compared correlation difference indicator;

    detecting energy of the received transmitted frame and low-pass filtering the energy to provide a low-pass filtered energy signal;

    comparing the low-pass filtered correlation signal with the low-pass filtered energy signal to provide a correlation peak indicator;

    comparing the correlation peak indicator with a second fixed predetermined threshold to provide a threshold compared correlation peak indicator; and

    forming a logical-AND of the threshold compared correlation difference indicator and the threshold compared correlation peak indicator to determine a match/no match comparison indicative of the start of a transmitted frame.

View all claims
  • 7 Assignments
Timeline View
Assignment View
    ×
    ×