论文标题
队列感知的星际辅助诺玛通信系统
Queue-Aware STAR-RIS Assisted NOMA Communication Systems
论文作者
论文摘要
In this paper, the queue-aware simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) assisted non-orthogonal multiple access (NOMA) communication system is investigated to ensure the system stability, where the long-term stability-oriented problem is reformulated to maximize the per-slot queue-weighted sum rate (QWSR) of users based on the Lyapunov drift theory.通过共同优化NOMA解码顺序，在BS处的主动波束形成系数以及在星-RIS处的被动传输和反射系数，考虑了三个星-RIS工作协议，即能量分解（ES），模式切换（MS）和时间切换（TS）。对于ES，调用了阻塞的坐标下降和连续的凸近似方法来处理高度耦合和非凸问题。对于MS，提出的算法将进一步扩展到基于惩罚的两环算法以解决二进制幅度约束问题。对于TS，将法式的问题分解为两个子问题，每个子问题都可以与ES相似。仿真结果表明：i）我们提出的星际辅助诺玛通信的性能比传统方案更好； ii）重新制定的QWSR最大化问题证实了系统的稳定性； iii）TS在QWSR和平均队列长度方面都取得了出色的性能。
In this paper, the queue-aware simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) assisted non-orthogonal multiple access (NOMA) communication system is investigated to ensure the system stability, where the long-term stability-oriented problem is reformulated to maximize the per-slot queue-weighted sum rate (QWSR) of users based on the Lyapunov drift theory. By jointly optimizing the NOMA decoding order, the active beamforming coefficients at the BS, and the passive transmission and reflection coefficients at the STAR-RIS, three STAR-RIS operating protocols are considered, namely energy splitting (ES), mode switching (MS), and time switching (TS). For ES, the blocked coordinate descent and the successive convex approximation methods are invoked to handle the highly-coupled and non-convex problem. For MS, the proposed algorithm is further extended to a penalty-based two-loop algorithm to solve the binary amplitude constrained problem. For TS, the formulated problem is decomposed into two subproblems, each of which can be solved in a similar manner to ES. Simulation results show that: i) our proposed STAR-RIS assisted NOMA communication achieves better performance than the conventional schemes; ii) the reformulated QWSR maximization problem confirms the system stability; and iii) TS achieves superior performance with respect to both the QWSR and the average queue length.
