earticle

영어

To implement transmit beamforming, which is an effective way of leveraging the diversity
gains, for multiple-input single-output orthogonal frequency division multiplexing (MISOOFDM)
systems, (partial) channel state information is required at the transmitter. In this paper, we present a new limited feedback scheme in MISO-OFDM systems with transmit beamforming. By dividing the total subcarriers of an OFDM symbol into a series of clusters, from the codebook we choose the “proper” one, which minimizes the average bit error rate (BER) per subcarrier of the considered cluster, as the beamforming vector for this cluster. The scheme can reduce the feedback overhead remarkably while obtain good BER performance. Further, a simple sub-optimal algorithm exploiting the correlation of channel frequency responses at different ubcarriers is proposed to avoid exhaustive search in the optimal solution. The complexity analysis and simulations show that the proposed method has low computational complexity and provides improvement over the existing schemes.