Recursive Sliding-Window LMMSE-Based Equalization in Wireless Mobile Coded OFDM

Orthogonal frequency division multiplexing (OFDM) system suffers extra performance degradation in fast fading channels due to intercarrier interference (ICI). Combining frequency domain equalization and bit-interleaved coded modulation (BICM), the iterative receiver is able to harvest both temporal and frequency diversity. Using the fact that ICI energy is clustered in adjacent subcarriers, frequency domain equalization is made localized. Conventional localized q-tap frequency domain equalizer still bears a formidable computational complexity of O(K²q), where K is the number of subcarriers. By further restricting the observation window size, sliding-window (SW) type of equalizer is proposed in the literature with complexity O(Kq³). This paper proposes a recursive SW LMMSE based equalizer which further reduces the computational complexity to O(Kq²) and more importantly without compromising performance.