Performance of MIMO systems with combined polarization multiplexing and transmit diversity

Spatial multiplexing and space-time block codes are promising techniques that effectively exploit multiple-input multiple-output (MIMO) transmission to achieve a higher data rate and more reliable communication, respectively. On the other hand, the use of dual-polarized antennas in MIMO systems has emerged as a cost- and space-effective alternative, where two spatially separated uni-polarized antennas can be replaced by a single antenna element employing orthogonal polarizations. In this paper, we investigate the use of dual-polarized antennas in a combined spatial multiplexing and space-time block coded system. We present a hybrid transmission scheme that employs transmit diversity over the same polarization of the two transmit dual-polarized antennas and transmits the co-channel space-time coded signals on the orthogonal polarizations. We evaluate the system performance for both the Rayleigh fading channel and the suburban environment of a personal communication system (PCS) at 1800 MHz. It is shown that the performance of PM-STBC approaches that of STBC in the correlated Ricean fading environment and it saves one receive antenna.