Maximum likelihood detection of precoded SFBC in frequency-selective fading channels

Abstract

In this paper, we derive the maximum likeli-hood detector (MLD) for precoded space-frequency block coded (SFBC) systems where orthogonal frequency divi-sion multiplexing (OFDM) is incorporated. The obtained results reveal that the precoding process can be exploited to construct low complexity MLD even when the channel frequency response is not equal across each SFBC block. The derived MLD structure is similar to the conventional Alamouti linear decoder except that the decoding matrix has to be selected from four possible matrices. However, the decoding matrix selection and symbols' detection can be performed jointly, which minimizes the additional computational complexity of the derived MLD as com-pared to the conventional Alamouti decoder. Monte Carlo simulation results show that the MLD outperforms the suboptimal detector reported in [1] by about 5 dB at bit error rate (BER) of 10-4 under various channel conditions. 2017 IEEE.