Use of erasure information in parallel combinatorial spread spectrum systems

This paper investigates the effects of using erasure information in Reed Solomon (RS) coded parallel combinatorial spread spectrum (PC/SS) communication systems over AWGN and Rayleigh fading channels. The PC/SS system is an advanced multicode direct sequence spread spectrum (DS/SS) system for high-speed data transmission. Our previous works have shown that the RS coded PC/SS systems provide significant improvement in error rate performance over conventional DS/SS systems. To achieve further performance improvement in the PC/SS systems, error-and-erasure decoding techniques are implemented in an RS coded PC/SS receiver. To obtain the erasure location information, a threshold test for the squared ratio of the correlator outputs is applied. Simulation results show that the coded PC/SS system using the erasure information provides significant improvement in word error rate (WER) and bit error rate (BER). With errors-only decoding, the PC/SS systems cannot improve the error rate performance because of large SNR penalty introduced by coding. On the contrary, error-and-erasure decoding using erasure information still improves the performance of PC/SS systems