New linear PIC detectors based on non-monotone line-search techniques

In this communication, three novel linear parallel interference cancellation (LPIC) detectors that exhibit fast convergence, low complexity, low memory requirements and can be used to efficiently approximate the decorrelator/MMSE detector in large-scale wireless communication systems are proposed. Unlike conjugate gradient based LPIC detectors, the proposed LPIC detectors maintain their efficiency and do not break down quickly if the matrix–vector products are performed only approximately. These detectors employ non-monotone line search techniques and use a pre-conditioner that exploits the structure of the inter-carrier interference (ICI) matrix to speed up the convergence of the conventional LPIC detector. Moreover, the chaotic behavior observed in the convergence of the proposed detector in AWGN channel is greatly reduced, thanks to the time-varying nature of the fading channel. Simulation results support well our theoretical findings.