Adaptive MIMO-OFDM System Based on QO-STBC/SFBC with Improved Feedback Scheme

In this paper, we propose an adaptive multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system based on quasi-orthogonal space time/frequency block coding (QO-STBC/SFBC) with an improved angle feedback scheme. First we exploit the improved feedback scheme which can minimize the non-orthogonality of QO-STBC/SFBC by rotating constellation symbols. Then we investigate its quantification method and the related criterions. Furthermore, we apply the adaptive modulation technique to this scheme in frequency selective channel. Simulation results show that the proposed feedback scheme can provide higher signal-to-noise ratio (SNR) gains, and systems with such scheme can get significant improvement by applying adaptive modulation technique.