基于非完美信道信息的MIMO NOMA系统和速率最大化

Sum-rate maximization in MIMO NOMA system with imperfect CSI

基于非完美信道状态信息,针对系统发射功率受限和用户速率需求约束下的系统和速率最大化问题,结合多输入多输出(MIMO)和非正交多址接入(NOMA)技术设计预编码和接收机。限定强用户的每条数据流都需要解码相应的弱用户信号以利用串行干扰技术消除弱用户信号的干扰,利用半正定规划和一阶泰勒展开将所形成的非凸优化问题转化为D.C.问题,并采用罚函数解决预编码秩为1的限制。仿真结果表明,相比于正交多址接入技术,所提出的D.C.算法可以提高系统和速率。

In order to solve the problem of maximizing the sum rate under the constraints of transmission power limitation and users’ rates requirements, precoder and receiver were devised by combining multiple-input multiple-output(MIMO) and non-orthogonal multiple access(NOMA) based on imperfect channel state information(CSI). To take advantage of successive interference cancellation(SIC) techniques to eliminate interference from weak user’s signal, each data stream of the strong user needed to decode the corresponding weak user’s signal. Since the problem formed was non-convex, it was converted into the problem with the difference of two convex functions(D.C.) by using semi-positive definite programming and first-order Taylor expansion, and a penalty function was used to solve the constraint of the rank of the precoding covariance matrix. The simulation results show that compared with the orthogonal multiple access technology, the proposed D.C. algorithm can improve system sum rate.