Selection of spreading sequences for direct-sequence spread-spectrum communications over a doubly selective fading channel with RAKE reception

Error probabilities are evaluated for direct-sequence spread-spectrum communications over channels with double selective fading. The error probability for such a system depends on the spreading sequence, the autocovariance function of the fading process, the receiver structure, and the receiver signal-to-noise ratio. The authors focus on the effect of the spreading sequence on the performance of differentially coherent detection of binary direct-sequence spread-spectrum signals using an equal-gain diversity combining RAKE receiver. Sensitivity of system performance to sequence selection when using RAKE reception is compared with sensitivity when a correlator receiver is used. Performance is considered for a range of channel characteristics and over the full range of signal-to-noise ratios