双向中继对秩亏MIMO信道容量影响的分析

Impact of Bi-Directional Relays on the Capacity of Rank-Deficient MIMO Channels

针对多输入多输出(MIMO)信道矩阵严重的秩亏问题,使用基于放大转发协议的协同双向中继,形成富散射环境,从而有效提高信道矩阵的秩.由于在两个节点之间双向同时传输数据,提高了频谱利用率.理论分析和仿真表明,与不使用中继辅助的MIMO信道相比,所提出方案在视距环境中能够有效提高秩亏MIMO信道的容量;同时,由于使用双向中继,利用自干扰消除的检测方法,使得其所需的时隙仅为传统放大转发中继的一半.信道增益矩阵的选取在传统放大转发协议的基础上增加了门限约束,进一步提高信道容量.

Aiming at the rank-deficient problem of multiple-input-multiple-output（MIMO） channel,the bi-directional relay based on the amplify-and-forward（AF） protocol is used to effectively increase the rank of the MIMO channels via forming the rich scattering environment.Because of bi-directional simultaneous transmission of data between the two nodes,the utilization of the spectral efficiency is increased.Theoretical analysis and simulation results show that compared with the MIMO channels without relay assistant,using bi-directional relays can solve the problem of rank-deficient MIMO channels.Because of using bi-directional relays,it requires half of the number of the time slots compared with the conventional AF relays utilizing the self-interference cancellation detection.The choice of the channel gain matrix adds the threshold restriction to the traditional AF protocol,so the capacity of the channel is improved further.