US 6,674,818 B1 · Reduced complexity decision circuitry

Abstract

The present invention groups a set of N, nearly orthogonal, CCK code words into M subgroups, with each subgroup consisting of N/M orthogonal code words. For the 64-ary CCK communication standard for wireless local area networks (WLAN), N is 64 and M is preferably 8. Based on the orthogonal subgrouping, most significant bit (MSB) comparitors, instead of full-scale comparitors, are used to compare cross-correlations for each subgroup. In the subgroup containing the desired maximum correlation, all other cross-correlations, except the maximum, are zero in an ideal case, or very close to zero in a noisy environment due to the selected orthogonality. The maximum correlation value can be distinguished by looking at only the most significant bit or bits among all the cross-correlations. In the subgroups that do not contain the global, maximum correlation value, it does not matter which cross-correlation value is picked. The maximum correlation from all the subgroups, which will include the global maximum from one of the subgroups, are monitored to select the maximum correlation value and the corresponding code word.

Claims29

Dependent claims

Cross-correlation circuitry for an N word code set wherein the code set has M subgroups of N/M orthogonal code words, said cross-correlation comprising:

a) correlation circuitry adapted to cross-correlate a received code word with each code word in the code set and provide N cross-correlation values for each cross-correlation;
b) M decision circuits, each decision circuit adapted to:
i) receive N/M cross-correlation values corresponding to one subgroup of orthogonal code words;
ii) select the largest cross-correlation value of the subgroup;
and
iii) associate a cross-correlation corresponding to the largest cross-correlation value of the subgroup;
and
c) overall maximum decision circuitry adapted to select the overall largest cross-correlation value from the M cross-correlation values selected from said M decision circuits and associate a cross-correlation corresponding to the overall largest cross-correlation value.

5 more elements

Dependencies are inferred from the claim text.

Reduced complexity decision circuitry

Life of this patent

Reduced complexity decision circuitry

Life of this patent

Abstract

Claims29