On the channel correlation structure of wideband scale-lag Rake fingers

The scale-lag Rake receiver is designed for wideband systems employing direct-sequence spread spectrum with a large bandwidth-to-center frequency ratio, such that the typical narrowband Doppler spread assumptions do not apply to mobile channels, and is capable of exploiting the diversity that results from mobility. We derive autocorrelation expressions for scale-lag Rake channel coefficients and explore the effectiveness of principal components combining (PCC) to reduce receiver complexity while maintaining performance. Such analysis applies, for example, to ultra-wideband (UWB) radio frequency channels and underwater wideband acoustic channels.