Reduced Complexity Turbo Multi User Detection for a CDMA System Using M-ary PSK

In CDMA systems, turbo multi user detection for multiple access interference cancellation and channel decoding in CDMA systems has an exponentially growing complexity with number of users. In these systems, when bandwidth efficient modulations like M-ary PSK are used another exponential factor that is relates to the levels of modulation prohibitively increases the computational complexity of the receiver. In this paper we have examined a symbol based reduced complexity multi user detector, for coded and un-coded CDMA system, with a performance very near to optimal detector while having extremely low complexity. We have introduced a design formula for the required Hamming distance value for no loss in performance. Simulation results of coded and un-coded CDMA system verify the performance of our reduced complexity detector that we expect.