一种基于嵌套晶格码的MIMO中继多用户矢量预编码设计

针对多输入多输出(MIMO)中继多用户系统的多址传输问题，为了提高系统可达速率和误码率性能，该文利用嵌套晶格码具有可达加性高斯白噪声信道容量的特性，设计一种基站和中继联合预编码的方法。基站端的嵌套晶格码结合矢量扰动(VP)预编码，以控制发送信号的功率。由于矢量扰动预编码和嵌套晶格码都存在相同的模运算步骤，因此在中继端的模运算抑制噪声功率的同时消除了冗余矢量。接着实现中继联合迫整数预编码方法，这种基站/中继混合预编码技术能够控制等效噪声功率，实现对蜂窝用户的有效信号传输。更进一步地，在给出整系数矩阵和扰动矢量矩阵的计算方法后，以最大化系统可达速率为目标对基站和中继的功率实现最优分配。实验结果表明，该方案在可达速率和误码性能方面优于现有方案。

Vector Precoding Design Based on Nested-lattice-coding for MU-MIMO Relay Systems

This paper focused on the problem of the multi-access transmission in multiuser Multiple-Input Multiple-Output (MIMO) relay systems. In order to improve the performance in terms of system capacity and bit error rate, a joint precoding approach for the base station and the relay station is proposed by exploiting nested lattice coding which is capable of achieving modulo-channel capacity with additive Gaussian noise. At base station, the nested lattice coding is equipped up with Vector Perturbation (VP) precoding, leading to a reduction in transmit power. Since the modulo operation with respect to VP precoding is identical to that in nested coding, the relay can not only depress the noise power but also remove the redundant information with one-step modulo operation. An integer-forcing precoding method is designed for the relay to reduce the equivalent noise. Moreover, the acquisition of both the integral coefficient matrix and the vector perturbation matrix is provided. The transmit power allocation between the base station and the relay is optimized to maximize the system sum rate. The outstanding performance of the proposed scheme is validated by the simulation results.