Orthogonal space-time block codes for large MIMO systems

Currently, detailed study of Orthogonal Space-Time Block Codes (OSTBC) in MIMO literature is mostly limited to conventional MIMO, i.e. MIMO systems with at most 8 transmit and 8 receive antennas. In view of the situation, this paper studies the implementation of OSTBC in Large MIMO systems. The paper presents OSTBC for transmission of real symbols that can support up to 32 transmit and 32 receive antennas. Simulation results show that real OSTBC system performance is highly dependent on the code rate of the transmission matrix as well and the number of antennas used. In general, lower code rate OSTBC has better BER performance than higher code rate OSTBC, but for systems with less than 32 transmit or receive antennas, higher code rate OSTBC can outperform the lower code rate OSTBC if the receive diversity gain is significant.