Method of determining an end of a transmitted frame in a frame-based communications network
View Patent ↗A method of determining an end of a transmitted frame at a receiver on a frame-based communications network. An end of frame format for the transmitted frame is provided having an end of frame plurality of symbols. A received transmitted frame is filtered using filter coefficients matched to the end of frame plurality of symbols to provide a correlation sequence low-pass filtered signal. A squared magnitude of the correlation sequence is computed. The squared magnitude of the correlation sequence is low-pass filtered to provide a low-pass filtered correlation signal. The low-pass filtered correlation signal is delayed to provide a delayed low-pass filtered correlation signal. The delayed low-pass filtered correlation signal is multiplied by a fixed predetermined threshold to provide a multiplied correlation signal. The multiplied correlation signal is compared with the low-pass filtered correlation signal to provide a match/no match comparison indicative of the possible end of a transmitted frame.
1. A method of determining an end of a transmitted frame at a receiver on a frame-based communications network comprising:
providing an end of frame format for the transmitted frame having an end of frame plurality of symbols;
filtering a received transmitted frame using filter coefficients matched to the end of frame plurality of symbols to provide a correlation signal;
computing a squared aagnitude of the correlation signal;
low-pass filtering the squared magnitude of the correlation signal to provide a low-pass, filtered correlation signal;
delaying the low-pass filtered correlation signal to provide a delayed low-pass filtered correlation sequence signal;
multiplying the delayed low-pass filtered correlation signal by a fixed predetermined threshold to provide a multiplied correlation signal; and
comparing the multiplied correlation signal with the low-pass filtered correlation signal to provide a match/no match comparison indicative of the possible end of a transmitted frame.
2. The method of claim 1 , wherein the filtering is linear matched filtering.
3. The method of claim 1 , wherein the filter coefficients are a time-reversed complex-conjugated end of frame symbol sequence.
4. The method of claim 3 , wherein the time-reversed complex-conjugated end of frame symbol sequence is a constant-amplitude zero-autocorrelation sequence.
5. The method of claim 3 , wherein the time-reversed complex-conjugated end of frame symbol sequence includes complex symbols drawn from a Quadrature Phase Shift Keying or 4-Quadrature Amplitude Modulation constellation.
6. The method of claim 1 , wherein the multiplying includes first computing 10*log10(.), or an approximation of 10*log10(.), of each low-pass filtered correlation signal operand to provide a plurality of low-pass filtered correlation signal log operands and then adding each of the plurality of low-pass filtered correlation signal log operands.
7. The method of claim 1 , wherein the comparing includes performing a comparison a predetermined number of times before an end of a transmitted frame is determined.
8. A method of determining an end of a transmitted frame at a receiver on a frame-based communications network comprising:
providing an end of frame format for the transmitted frame having an and of frame plurality of symbols;
linear matched filtering a received transmitted frame using filter coefficients matched to the end of frame plurality of symbols to provide a correlation sequence, the filter coefficients being a time-reversed complex-conjugated end of frame symbol sequence including complex symbols drawn from a Quadrature Phase Shift Keying or 4-Quadrature Amplitude Modulation constellation;
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;
multiplying the delayed low-pass filtered correlation signal by a fixed predetermined threshold by first computing 10*log10(.), or an approximation of 10*log10(.), of each low-pass filtered correlation signal operand to provide a plurality of low-pass filtered correlation signal log operands and then adding each of the plurality of low-pass filtered correlation signal log operands to provide a multiplied correlation signal; and
comparing the multiplied correlation signal with the low-pass filtered correlation signal to provide a match/no match comparison indicative of the possible end of a transmitted frame and performing a comparison a predetermined number of times before an end of a transmitted frame is determined.