空时编码OFDM与多维波束形成组合方案

Simple scheme combining space-time coded OFDM with multi-dimension beamforming

针对MIMO-OFDM系统提出了一种简单灵活的空时分组码与多维特征波束形成组合方案,以充分利用MIMO信道的二阶统计信息。该方案在保证空时编码分集度的同时能最大化系统的编码增益,空时分组码的选取并不受实际发射天线数的限制,因此可以在分集度、编码增益以及系统码率之间进行灵活的折中。理论分析和仿真结果同时表明,当实际发射天线数大于空时码所需天线数时,系统的编码增益随着实际发射天线数的增加大致呈线性增长,发射天线阵列间相关性越强,增长速度越快。

A simple and efficient combining scheme was proposed for MIMO-OFDM system, which jointly designed space time block codes and multi-dimension eigen-beamforming according to second-order statistics of channels. The proposed scheme would achieve the maximum coding gain besides the expected diversity, and the selection of space time block codes was not limited to the number of the actual transmit antennas, thus the appropriate tradeoff among diversity, coding gain and rate was easily made. The following results are found by theoretical analysis and simulations： the increasing of coding gain obtained by this scheme is approximately linear to the number of transmit antennas when the actual transmit antennas are more than the needing antennas by space time block codes; the achieved coding gain increases more quickly if transmit antennas exhibit stronger spatial correlation.