针对MIMO-NOMA系统中配对弱用户的空时编码方案

Space-time coding scheme for the paired weak user in MIMO-NOMA systems

鉴于多天线—非正交多址(MIMO-NOMA)系统中配对弱用户较差的中断性能,采用Alamouti码为弱用户编码,利用其分集作用来改善弱用户的中断性能,并推导出所提模型中强用户各态历经容量的闭合表达式以及弱用户各态历经容量、中断概率的边界表达式。另外,提出了一种优化系统吞吐量的功率分配算法。最后,数值结果验证了所推表达式的准确性和所提算法的有效性,也证实了所提编码方案中弱用户的中断性能要远优于目前只采用垂直分层空时码(V-BLAST)编码方案中弱用户的中断性能。

In view of the paired weak user＇s poor outage performance in multiple-input multiple-output non-orthogonal multiple access（MIMO-NOMA） systems, Alamouti code was adopted to encode for the weak user in order to improve its outage performance by means of diversity, and the closed-form expression of the strong user＇s ergodic capacity as well as the boundary-form expressions of the weak user＇s ergodic capacity and outage probability was derived in the proposed model. Moreover, a power allocation algorithm for optimizing the system＇s throughput was proposed. Finally, the numerical results show the accuracy of the derived expressions, the efficacy of the proposed algorithm, and that the weak user＇s outage performance in the proposed coding scheme is far superior to that in the current coding scheme only adopting vertical Bell lab layered space-time（V-BLAST） code.