An iterative multiuser detection with frequency-domain equalization for relay-assisted SFBC single-carrier systems

In this paper, an iterative multiuser detection scheme for relay-assisted space-frequency block code (SFBC) single-carrier systems with frequency-domain equalization is proposed. In practical mobile applications, relay-assisted SFBC in SC-FDE suffers performance degradation from double-selective (time and frequency selective) channels, resulting in a deviation from the basic assumption of Alamouti codeword. In the proposed algorithm, diagonalized SFBC decoding, soft multi-user interference (MUI) cancellation and soft inter-symbol interference (ISI) cancellation with minimum mean-square error (MMSE) filtering were performed iteratively to suppress interferences. An approximate implementation for complexity reduction with little performance loss was also proposed. The bit error rate (BER) performances and extrinsic information transfer (EXIT) charts were presented for Rayleigh fading channels. Simulation results show that our proposed algorithm outperforms other existing ones in severely double-selective channels without increasing computational complexity.