Novel Successive Transmit Beamforming Algorithms for MISO-OFDM Systems

In this paper, we focus on the design and evaluation of new transmit beamforming algorithms for the multiple-input single-output (MISO) orthogonal frequency division multiplexing (OFDM) systems. In the MISO-OFDM systems, out transmit beamforming requires a huge amount of channel feedback, this is because the channel state information on each subcarrier has to be conveyed from the receiver to transmitter. In order to reduce the channel feedback requirement in the OFDM system, we take the time and frequency domain correlations of the channel fading into consideration. Based on our successive beamforming (SBF) technique, we develop several classes of feedback algorithms for the OFDM systems. These new algorithms use the knowledge from the previous frame or neighboring subcarrier to aid the beamforming codebook design for the current subcarrier. Through numerical simulations, we demonstrate that the proposed algorithms require a small amount of channel feedback, yet they outperform the other existing finite rate OFDM beamformers.