Reduction of Computational Complexity in Multistage DS-CDMA System

Multiple Access Interference (MAI) is one of the major problems that limit the system capacity of Direct Sequence-Code Division Multiple Access (DS-CDMA) Wireless Communication Systems. The reduction of MAI to improve system capacity without increasing computational Complexity is the motivation to do this work. The objective of this paper is to develop efficient multiuser detection algorithms that improve the DS-CDMA system performance i.e., to achieve a low Bit Error Rate (BER) and high Signal to Noise Ratio (SNR) with less computational complexity. The BER performance of the multistage multiuser detection schemes using Kasami spreading sequences and MMSE detector is found to be better than that of a conventional Matched Filter detector in a single-stage multiuser detection scheme but the Computational Complexity increases with the number of stages and the number of users. The BER performance of the multistage multiuser PIC detection scheme is found to be better than that of a single-stage multiuser PIC detection scheme but at the cost of computational complexity increasing with a number of stages and users. It is found that the BER performance of the multistage multiuser PPIC detection scheme is better than that of the multistage multiuser PIC detection scheme but the computational complexity increases. Though the computational complexity is found reduced in the multistage multiuser DPIC when compared to the multistage multiuser PIC, the BER performance remains almost the same as that in multistage multiuser PIC.