Improved Performance for Hybrid STBC and Spatial Multiplexing OFDM Systems with Linear Receivers

In this paper, we study a practical design for hybrid space-time block coding (STBC) and spatial multiplexing (SM) with orthogonal frequency division multiplexing (OFDM) systems. The hybrid STBC-SM OFDM systems can achieve both spatial diversity and multiplexing gains simultaneously in frequency selective MIMO channels. For the hybrid designs, zero forcing (ZF) and minimum mean square error (MMSE) linear receivers are derived by a simple transformation. To improve error rate performance, we propose weighted soft decision Viterbi decoding by using the SINR of the transformed equivalent channel matrix. The proposed scheme can mitigate noise enhancement inherent to ZF and MMSE linear detectors. Extensive simulations show that the proposed technique with low complexity exhibit robust performance improvement for different propagation channels and modulations.