Low-complexity successive detection method for OFDM systems over doubly selective channels

Orthogonal frequency division multiplexing (OFDM) system is robust against inter-symbol interference (ISI) by increasing the symbol duration. However, for high-speed application, time variation of a multipath channel result in inter-carrier interference (ICI). It leads to the performance degradation. This works propose a low-complexity successive detection algorithm combined with the techniques of Newton´s iterative matrix inversion method and successive detection method according to signal to noise ratio (SNR) in OFDM system. With the assumption of linearly varying channel impulse responses under fast fading conditions, the proposed algorithm reduces the complexity from O(N³) of conventional zero-forcing algorithm to O(N²) , meantime it mitigates the noise enhancement problem. In all, it surpasses the performance bound of zero-forcing (ZF) equalization.