Low Complexity PIC-MMSE Detector for LDS Systems over Frequency-Nonselective Channels

We consider minimum mean square error (MMSE) and parallel interference cancellation (PIC) (MMSE-PIC) detection for low-density spreading (LDS) systems and compared its bit error rate (BER) performance to LDS systems using MPA-based detection the detection. In this paper, we extend the research of [1] to the frequency-nonselective Rayleigh fading channel, where we show that the BER performance of the MMSE-PIC receiver is only a small fraction of a dB behind that of the MPA-based detector. Therefore the MMSE-PIC receiver is a very good low-complexity alternative to MPA-based detection as it greatly reduces computation complexity without making a large sacrifice in BER performance.