| 摘要 |
A fast correlator transform (FCT) algorithm and methods and systems for implementing same, correlate an encoded data word (X<SUB>0</SUB>-X<SUB>M-</SUB>) with encoding coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>), wherein each of (X<SUB>0</SUB>-X<SUB>M-1</SUB>) is represented by one or more bits and each said coefficient is represented by one or more bits, wherein each coefficient has k possible states, and wherein M is greater than 1. In accordance with the invention, X<SUB>0 </SUB>is multiplied by each state (C<SUB>0(0) </SUB>through C<SUB>0(k-1)</SUB>) of the coefficient C<SUB>0</SUB>, thereby generating results X<SUB>0</SUB>C<SUB>0(0) </SUB>through X<SUB>0</SUB>C<SUB>0(k-1)</SUB>. This is repeating for data bits (X<SUB>1</SUB>-X<SUB>M-1</SUB>) and corresponding coefficients (C<SUB>1</SUB>-C<SUB>M-1</SUB>), respectively. The results are grouped into N groups. Members of each of the N groups are added to one another, thereby generating a first layer of correlation results. The first layer of results is grouped and the members of each group are summed with one another to generate a second layer of results. This process is repeated as necessary until a final layer of results is generated. The final layer of results includes a separate correlation output for each possible state of the complete set of coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>). The final layer of results is compared to identify a most likely code encoded on said data word. In an embodiment, the summations are pruned to exclude summations that would result in invalid combinations of the encoding coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>). In an embodiment, substantially the same hardware is utilized for processing in-phase and quadrature phase components of the data word (X<SUB>0</SUB>-X<SUB>M-1</SUB>). In an embodiment, the coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>) represent real numbers. In an alternative embodiment, the coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>) represent complex numbers. In an embodiment, the coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>) are represented with a single bit. Alternatively, the coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>) are represented with multiple bits (e.g., magnitude). In an embodiment, the coefficients (C<SUB>0</SUB>-C<SUB>M-1</SUB>) represent a cyclic code keying ("CCK") code set substantially in accordance with IEEE 802.11 WLAN standard.
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