Method of determining a start of a transmitted frame in a frame-based communications network
First Claim
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.
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Accused Products
Abstract
A method of determining a start of a transmitted frame at a receiver on a frame-based communications network. A received transmitted frame is filtered using filter coefficients matched to a preamble symbol sequence to provide a correlation sequence. The correlation sequence is low-pass filtered and delayed to provide a delayed low-pass filtered correlation signal. The delayed low-pass filtered correlation signal is compared with the low-pass filtered correlation signal and a fixed predetermined threshold to provide a correlation difference indicator. Energy of the received transmitted frame is detected and the energy is low-pass filtered to provide a low-pass filtered energy signal. The low-pass filtered correlation signal is compared with the low-pass filtered energy signal to provide a correlation peak indicator. A logical-AND of the correlation difference indicator and the correlation peak indicator is formed to determine a match/no match comparison indicative of the start of a transmitted frame.
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Citations
7 Claims
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1. A method of determining a start of a transmitted frame at a receiver on a frame-based communications network, the method comprising:
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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 Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification