Closed loop space-time block code

In 3GPP FDD specifications, space time transmit diversity (STTD) employs space-time block code (STBC) to maintain orthogonality between the two antennas in order to avoid self-interference in fading channels. However, the STTD technique is just open loop transmit diversity, and we investigate whether we can obtain further gain if closed loop STBC is used. A novel scheme based on closed loop STBC is proposed first. And then an optimized allocation scheme of a fixed transmitter power budget between two transmit antennas is presented. Finally, COSSAP simulation results show a significant performance improvement between closed loop STBC and traditional STBC. Moreover, these simulation results also show a good agreement with our theoretical analyses.