Generalized closed loop transmit diversity algorithm for WCDMA

A previously proposed transmit diversity algorithm for four antennas is extended to an algorithm for eight transmit antennas. Depending on a signal-to-interference-plus-noise ratio maximization criterion, either full (all available transmit antennas) or partial diversity (only a subset or all available transmit antennas) is used. Phase adjustments are also applied between the selected antennas. The proposed algorithm offers a considerable gain in transmit signal-to-noise ratio per bit compared to all-antenna transmission and one-antenna selection transmit diversity. The gain is present for both uncorrelated fading and for correlated fading between transmit antennas. Furthermore, it has been shown that the proposed algorithm is more robust to the channel estimation errors than an all-antenna transmit diversity or one-antenna selection transmit diversity.