Minimum BER Transmit Beamforming for MIMO-OFDM Systems With Finite Rate Feedback

In recent years, it has become apparent that the performance of multi-antenna wireless systems can be significantly improved by exploiting Channel State Information (CSI) at the transmitter. This is not only true for traditional single-carrier systems but even more so for multi-carrier systems where Orthogonal Frequency Division Multiplexing (OFDM) is used to convert a broadband frequency-selective channel into a number of parallel narrowband frequency-flat channels. Such Multiple-Input Multiple-Output (MIMO) OFDM systems have been adopted in various recent wireless standards such as IEEE 802.11 (WLAN) and IEEE 802.16 (WiMAX).