有限反馈MISO-OFDM系统中最大化容量的波束成形

Throughput-Maximizing Limited Feedback for Transmit Beamforming in MISO-OFDM Systems

该文提出了一种在有限反馈条件下多输入单输出-正交频分复用(MISO-OFDM)系统中基于最大化容量的波束成形方案。将OFDM符号的所有子载波分成若干簇,从码本中选择能够最大化该簇每个子载波平均容量的码字,作为该簇的波束成形向量。在低信噪比区域,求出了最优波束成形向量的闭合解;鉴于在高信噪比区域无法求出闭合解,基于簇内不同子载波信道频响之间的相关性提出了一种简化的次优算法以降低搜索最优解时的计算复杂度。仿真结果表明,在典型参数设置下,所提方案能够取得比其他已有方案更高的容量和更低的误码率。

In this paper, a new throughput-maximizing transmit beamforming scheme with limited feedback is presented in Multiple-Input Single-Output Orthogonal Frequency Division Multiplexing （MISO-OFDM） systems. By dividing the total subcarriers of an OFDM symbol into a series of clusters, from the codebook the ＂proper＂ codeword maximizing the average throughput per subcarrier of the considered cluster is chosen as the BeamForming Vector （BFV） for this one. In low Signal to Noise Ratio （SNR） range, the close-form expression of the optimal BFV is derived. While in high SNR range, since the close-form expression of the optimal BFV is difficult to found, a simple sub-optimal algorithm exploiting the correlation of channel frequency responses at different subcarriers is proposed to reduce the computational complexity of the exhaustive search in the optimal solution. The simulation results show that the proposed algorithm can provide not only higher throughput but also lower bit error rate than other existing schemes.