信道反馈延迟时上行多用户MIMO中继系统预编码

Precoding for Up-link Multi-user MIMO Relay Systems with Feedback Delay

研究了信道存在反馈延迟和估计误差条件下,上行多用户多输入多输出中继系统的线性预编码算法.在中继发射功率受限条件下,考虑发送端-中继节点以及中继节点-目的端信道估计方法的局限性及反馈链路的时延性.根据最小均方误差准则设计以预编码矩阵为变量的优化问题,并采用联合迭代法求得中继端和接收端处理矩阵的闭式解.数值仿真结果表明,当存在信道反馈延迟和估计误差时,所提方案比现有算法更能有效降低系统误比特率.

This paper proposes an optimal linear precoding scheme for uplink multi-user multiple-input multiple-output（MIMO） relay systems applicable to a channel with feedback delay and channel estimation errors. Limitations of the channel estimation method and the time delay of feedback link are considered. Design of transceiver is simplified as an optimal problem with precoding matrix variables, derived with a maximum power constraint at the relay station based on the minimum mean-square error（MMSE） criterion.The relay precoding matrix and decoding matrix are obtained, and the equalizer optimized with a linear iterative searching algorithm. Numerical simulation shows that the proposed scheme can effectively reduce the bit error rate of the system when channel feedback delay and estimation error exist.