A reduced complexity RAKE receiver with decision feedback equalization for DS/SS communication over multipath fading channels

Abstract

Spread spectrum communication over a multipath fading channel usually outperforms narrowband communication because the number of resolvable paths is higher when the signal bandwidth is larger. Unfortunately, the complexity of the optimum RAKE receiver is proportional to the ratio of the channel delay spread to the chip duration, which might be very large when the delay spread exceeds the symbol duration. We introduce a reduced complexity RAKE receiver, followed by decision feedback equalization. Assuming the multipath intensity profile of the channel consisting of distinct clusters with random delays (as is the case for the HF radio channel), we compare the performance of the proposed receiver with the performances of the optimum RAKE receiver for spread spectrum communication and the receiver for narrowband communication. Although the proposed receiver structure has a performance loss of a few dB as compared to the optimum RAKE receiver, we find that it still outperforms narrowband communication.