Efficient Turbo Frequency Domain Equalization Based on Symbol-Wise Detection

This paper proposes an efficient turbo frequency domain equalizer (FDE) for single carrier systems with cyclic-prefix (CP). At each iteration, the proposed algorithm performs soft inter-symbol interference (ISI) cancellation and symbol-wise minimum mean-square error (MMSE) filtering both in the frequency domain to minimize the performance degradation caused by frequency-selective channels. After the one-tap frequency domain filtering, the assumption of an equivalent additive white Gaussian noise (AWGN) channel is used to compute the extrinsic log likelihood ratios (LLRs) of coded bits as the inputs of soft-in soft-out (SISO) decoder. Simulation results show that our proposed algorithm achieves the best trade-off between BER performance and computational complexity compared to other existing methods.