Novel search algorithms for closed-loop transmit diversity system with limited number of feedback bits

We propose two simple closed-loop transmit diversity schemes, with a fixed number of feedback bits being allocated for each transmit antenna. Under a low mobility condition and with perfect channel knowledge at the receiver, we show that our proposed schemes can achieve signal-to-noise ratio (SNR) values close to the optimal solution, but with greatly reduced complexity. We also show that our methods outperform other suboptimal schemes, such as the cophasing method.