An improved hybrid STBC scheme with precoding and decision feedback detection

In practical wireless communication systems, the number of receive antennas is more restricted than that of the transmit antennas. The spatial division multiplexing (SDM) technique normally imposes a restriction that the number of receive antennas should be more than or equal to that of the transmit antennas, whereas the space time coding (STC) technique can be adopted without such a limitation. The hybrid STBC scheme is a mixture of the above two systems. We propose two approaches to improve the hybrid STBC scheme: a precoding method and a decision feedback detection method. Applying a linear precoding matrix with full rank property can improve the performance. Also, the decision feedback detection scheme cancels out the interference using already-detected components. Simulation results show that the proposed methods outperform the conventional hybrid STBC detection algorithm for frequency selective channels and its gain increases for higher modulation levels.