RIS辅助共生无线电通信的速率分拆多址资源分配方案

Rate Splitting Multiple Access Resource Allocation Scheme for RIS-assisted Symbiotic Radio Communication

随着通信场景和网络架构的日益复杂,无线电网络频谱资源稀缺与能耗问题是无线通信的关键挑战,为此,提出了一种新的基于速率分拆多址接入技术(Rate Splitting Multiple Access,RSMA)广播信号的可重构智能表面(Reconfigurable Intelligent Surface,RIS)辅助共生无线电(Symbiotic Radio,SR)系统方案。在该方案中主发射机采用RSMA的方式广播信号,并将传统高功耗次发射机用低功耗RIS替代协作信号的后向散射传输。在主发射机发射波束形成,RIS相移系数和公有信息速率分配约束下,构建了最大化主接收最小速率的问题。由于问题的非凸性和变量的耦合性,提出了一种基于逐次凸逼近,凸差函数,罚函数的交替优化方法以求得次优解。仿真结果表明,与空分多址接入和非正交多址接入方案相比,所提RSMA方案能显著提升用户速率。

With the increasing complexity of communication scenarios and network architectures,spectrum resource scarcity and energy consumption problems in radio networks are key challenges for wireless communications.To address these issues,a new reconfigurable intelligent surface(RIS)-assisted symbiotic radio(SR)system scheme based on rate splitting multiple access(RSMA)technique for broadcasting signals is proposed.In this system scheme the primary transmitter broadcasts the signal by RSMA and replaces the conventional high power subtransmitter(ST)with a low power RIS for backward scattering transmission of the collaborative signal.The problem of maximizing the minimum rate of the primary receiver(PR)is constructed under the constraints of PT transmit beamforming,RIS phase shift coefficient and public information rate allocation.Due to the nonconvexity of the problem and the coupling of variables,an alternating optimization(AO)method based on successive convex approximations,convex difference functions,and penalty functions is proposed to find the suboptimal solution.Simulation results show that the proposed RSMA scheme can significantly improve the user rate compared with the non-orthogonal multiple access(NOMA)and space division multiple access(SDMA)schemes.