Realistic channel model considerations in UMTS downlink capacity with space-time block coding

Space-time block coding-based transmit diversity (STTD) has been adopted by 3GPP as the open loop transmit diversity scheme aiming at improving the FDD downlink capacity. Although the assumption of independent channels corresponding to different transmitting antennas is commonly made when assessing theoretically the resulting improvement, in a practical system the actual correlation between antennas is highly dependent on the antenna separation, the angular spread and the multipath environment. A realistic spatio-temporal channel model is employed in order to quantify the impact of these factors on the actual STTD performance and compare it against the ideal case of independent channels.