| 摘要 |
<p>Subtractive CDMA demodulation optimally decodes a coded information signal embedded in many other overlapping signals making up a received, composite signal. A radio receiver (25) correlates a unique code corresponding to the desired signal to be decoded with the composite signal. Moreover, after each information signal is successfully decoded (processor 40), it is recoded and removed from the composite signal. Subtractive CDMA demodulation is enhanced by decoding the composite signal in the order of strongest to weakest signal strength (signal strength processor 29). The individual information signals are spread using block error correction codes which are correlated with the composite signal using Fast Walsh transforms (correlator 30). Correlated signals identified as the largest transform component are removed from the composite signal and the remaining composite signal is reformulated using an inverted Fast Walsh transform. Any residual error or interference caused during the extraction of a transform component is removed by recorrelating the composite signal using the index of that transform component.</p> |
