Two-Real-Symbol-Decoding for O-STBC with Offset QAM for Four Transmit Antennas

A novel 4 x 1 scheme of transmitting two real orthogonal space-time block codes (O-STBC) on the I- and Q-channels with pulse-shaped offset QAM has recently been proposed. In order to achieve good spectral confinement, a pulse shape that introduces a small amount of controlled interference between I/Q- channels is used for the offset QAM signal. In this paper, two-real- symbol joint decoding is investigated for the scheme. This joint decoding can outperform the single-real symbol decoding proposed previously and the best-performing quasi-orthogonal space-time block code (QO-STBC) by more than 1 dB at bit error probability of 10^-5 when the interference introduced by the pulse shape is relatively large.