全双工MIMO中继系统中一种高性能波束成形算法

全双工中继系统相比于半双工中继系统可以极大地提高频谱利用率，但是中继收发端之间的信号泄漏严重影响全双工系统的性能。为了抑制基于译码转发的全双工多输入多输出中继系统的自干扰，提高信息传输速率，提出了一种波束成形算法。该算法在中继站采用基于最小均方误差的接收与发射波束成形，并联合两个波束成形矩阵建立迭代结构以得到最优解。仿真表明，同传统的零空间投影与最大化信干比算法相比，提出的算法能够有效提高系统性能。在中高信噪比时，该算法较最大化信干比算法获得0.8 bit/(s·Hz)左右的速率增益；当误码率达到10-3以及更低时，该算法相比于最大化信干比算法能获得1.5 dB左右的信噪比增益。

High-Performance Beamforming Algorithm for Full-Duplex MIMO Relay System

Compared to half-duplex relay systems, full-duplex relay systems can greatly improve the spectral efficiency. However, the information leakage between transmitter and receiver of relay degrade the performance of full-duplex system. To deal with the self-interference and enhance the system achievable rate in full-duplex MIMO relay system with decoded-and-forward strategy, an iterative beamforming structure at the relay is proposed. In this structure, the received and transmit beamforming at the relay are optimized with minimum mean square error (MMSE) criterion over both uplink and downlink (called MMSE plus MMSE). And then the two beamforming matrices are combined for optimal solutions. Simulation results show that the proposed MMSE plus MMSE performs better than existing schemes like null space projection (NSP) and maximum signal-to-interference ratio (Max-SIR). For example, The proposed algorithm harvests about 0.8 bps/Hz gain over the Max-SIR when SNR is high. At the BER=10-3, the proposed scheme harvests about 1.5 dB SNR gain over the Max-SIR.