基于STAR-RIS和中继集成系统的下行NOMA覆盖增强技术  

Downlink NOMA Coverage Enhancement Based on Integrated STAR-RIS and Relay

作　　者：陈思宇 申滨[1,2] 元文军 CHEN Siyu;SHEN Bin;YUAN Wenjun(School of Communications and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China;Chongqing Key Laboratory of Mobile Communications Technology,Chongqing 400065,China)

机构地区：[1]重庆邮电大学通信与信息工程学院,重庆400065 [2]移动通信技术重庆市重点实验室,重庆400065

出　　处：《电讯技术》2025年第3期469-476,共8页Telecommunication Engineering

基　　金：国家自然科学基金资助项目(62371082)。

摘　　要：可重构智能表面(Reconfigurable Intelligent Surface,RIS)与中继技术相结合是近年来兴起的新型增强型无线通信技术。为实现下行覆盖增强,提出了一种基于同时反射和透射的可重构智能表面(Simultaneously Transmitting and Reflecting Reconfigurable Intelligent Surface,STAR-RIS)与解码转发(Decode-and-Forward,DF)中继协同工作的下行非正交多址(Non-orthogonal Multiple Access,NOMA)双用户系统。在Nakagami-m信道假设下,通过联合优化基站和中继处的NOMA功率分配以及STAR-RIS的能量分裂系数,实现最大化该系统中两个用户的可实现速率之和。在满足功率约束和理想连续干扰消除的条件下,提出了一种基于两阶段中继系统流量平衡的双层迭代算法,通过内层迭代功率分配和外层迭代能量分裂系数来得到最优值。仿真结果表明,该集成系统覆盖性能在系统功率同为1 W的情况下要优于纯中继系统,且优势随STAR-RIS元件数量增多而变大;当STAR-RIS元件个数小于200或发射信噪比小于80 dB时,该系统相较于纯STAR-RIS系统亦可获得0.5~2 b/s/Hz的系统和速率增益。The combination of reconfigurable intelligent surface(RIS)and relaying technology is a new enhanced wireless communication technology emerging in recent years.To achieve downlink coverage enhancement,a dual-user system for downlink non-orthogonal multiple access(NOMA)based on simultaneously transmitting and RIS(STAR-RIS)working in concert with decode-and-forward(DF)relay is proposed.Under the Nakagami-m channel assumption,the sum of the achievable rates of the two users in this system is maximized by jointly optimizing the NOMA power allocation at the base station and the relay as well as the energy splitting coefficient of STAR-RIS.Subject to satisfying the total power constraint and ideal successive interference cancellation,a two-layer iterative algorithm based on flow balancing in two-phase relay systems is proposed to obtain the optimal value by iterating the power allocation in the inner layer and the energy splitting coefficient in the outer layer.The simulation results show that the coverage performance of the integrated system is better than that of the single relay system under the same system power of 1 W,and the advantage increases with the increase of the number of STAR-RIS components;when the number of STAR-RIS components is less than 200 or the transmission signal-to-noise ratio is less than 80 dB,the system can also achieve sum-rate gain of 0.5~2 b/s/Hz compared with single STAR-RIS systems.

关 键 词：STAR-RIS 非正交多址(NOMA) 解码转发中继 集成系统 功率分配 

分 类 号：TN929.5[电子电信—通信与信息系统]