双向MIMO中继网络中采用信道独立预编码的自干扰消除技术

双向中继网络在提高频谱效率的同时会引入额外的自干扰，本文针对放大转发（AF）模式下双向多输入多输出（MIMO）中继网络中的自干扰抵消问题，从消除信道估计误差引入的剩余自干扰着手，提出一种采用信道独立预编码的盲干扰抵消（BIC）方案。新方案在源节点对信息进行行空间预编码，从而构建不依赖于MIMO信道矩阵的期望信号子空间和自干扰子空间，实现未知信道状态下自干扰抵消和期望信号分离，从而消除非理想信道估计带来的剩余自干扰信号。在此基础上，以最大化有效信噪比为目标设计最佳预编码，通过推导可达和速率的闭合表达式，分析不同方案下信道估计误差对可达和速率的影响。仿真结果表明，新方案在不同的信道估计误差下，能够实现完美自干扰消除，其检测性能和容量均优于基于信道估计的自干扰消除方案。 

Self-Interference Cancelation for Two-way MIMO Relay Network Based on Channel Independent Precoding

In two-way relay network, it brings the additional self-interference when improving the spectrum effectiveness. This paper considers the self-interference cancellation for amplify-and-forward multi-input multi-output (MIMO) two-way relay network. In order to cancel the residual self-interference with the imperfect channel estimation, a blind interference cancelation scheme (BIC) based on channel independent precoding is proposed. In the new scheme, the transmit data blocks at source node are precoded using row-space-mapping，with the target signal subspace and self-interference signal subspace established that is independent of MIMO channel state information (CSI), which can cancel the self-interference and decouple the target signal without CSI. On this basis, we design the optimal precoding matrix to maximum effective signal-to-noise ratio, derive the close-form expression of achievable sum rate and analysis the effect of channel estimation error under different scheme on achievable sum rate. Simulation results present that the new scheme can cancel the residual self-interference with different channel estimation error. The detectability and capacity both perform better compared to self-interference schemes based on channel estimation.