Signal detection for space-frequency OFDM systems with quasi-orthogonal space-time block codes

In this paper, we use a quasi-orthogonal STBC (QO-STBC) instead of the conventional O-STBC as the inner code for OFDM MIMO systems, resulting in quasi-orthogonal space-frequency block coding (QOSFBC). Due to the effect of multi-path, the conventional signal detector in Ill will cause an irreducible error floor in the high signal-to-noise ratio (SNR) region for these new QO-SF-OFDM systems This paper addresses this issue by employing a Zero-forcing approach, which has the potential advantage of low complexity and can fully remove the error floor.