Low Complexity LSQR-Based Block Decision Feedback Equalizer for OFDM Systems over Rapidly Time-Varying Channels

In orthogonal frequency division multiplexing (OFDM) systems, Doppler effect introduced by high-mobility leads to the loss of subcarrier orthogonality and the occurrence of inter-carrier interference (ICI). In this paper, a novel low complexity block decision feedback equalizer (BDFE) is proposed in order to mitigate ICI over rapidly time-varying channels. The proposed equalizer algorithm obtains the tradeoff between computations and performance by exploiting band factorization and time domain LSQR iterative computation. Simulation results show that the proposed equalizer outperforms existing MMSE-DFE algorithms for the same complexity over rapidly time-varying channels.