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Performance of the multi-stage detector for a MC-CDMA system in a Rayleigh fading channel

Multi-carrier (MC) CDMA is a multiple access scheme that combines multi-carrier modulation (or OFDM) with direct sequence spread spectrum (DS-SS), and allows for efficient utilization of the bandwidth, resistance against frequency selectivity inherent in broadband mobile radio channels, and efficient implementation using the FFT. Since the complexity of the optimum maximum likelihood detector (MLD) grows exponentially with the number of users, simpler suboptimum detectors are considered in practical applications. We analyze the performance of a new form of the multi-stage detector using the threshold orthogonality restoring correlation (TORC) detector at the initial stage, in a frequency selective, slowly fading Rayleigh channel. Analytical and simulation results are presented for the initial stage (TORC detector) and the first stage of the multi-stage detector, which show that with only one stage significant performance enhancement can be achieved.