摘要
针对上行多用户MIMO中继系统,在信道存在反馈延迟及估计误差的条件下,以误比特率(Bit error rate,BER)为优化目标,提出了基于最小均方误差(Minimum mean?squared error,MMSE)准则的预编码算法。所提算法将求解发射端、中继节点、接收端矩阵的复杂非凸问题分解为3个独立的子优化问题,发射端的用户配备单天线且服从空间独立分布,先确定发射端预编码矩阵,将求解中继矩阵的凸优化问题转化为半正定规划(Semi?definite programming,SDP)问题,采用CVX工具箱求解,接收端处理矩阵通过线性搜索法求解,最后采用联合迭代法得到各节点矩阵的最优解。仿真结果表明,所提算法能有效改善系统的误比特率性能。
For up?link multi?user multiple?input multiple?output relay systems,with the aim of minimizing the bit error rate,a linear precoding scheme design is proposed based on the minimum mean?squared error(MMSE)rule in the presence of the feedback delay and channel estimation error. The proposed precoding algorithm decomposes the constrained optimization problem into three sub?convex optimization problems that are solved separately. The transmitter equipped with single antenna is subject to independent distribution,and it can be assumed that the precoding matrix is a diagonal matrix. The convex optimization problem of relay matrix is transformed into semi?definite programming problem(SDP),which can be solved by CVX toolbox. The equalizer matrix can be introduced by the gradient?based line search algorithms. Then the optimal solution is obtained by using joint iteration. The simulation results show that the proposed scheme can achieve better system performance.
引文
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