In order to enhance the performance of downlink non-orthogonal multiple access(NOMA)communication systems assisted by reconfigurable intelligent surfaces(RIS)in scenarios with non-uniform user distribution,a distributed user clustering scheme for downlink NOMA assisted by RIS has been proposed.Firstly,the adaptive geometric distribution(AGD)clustering algorithm is utilized to cluster users into user clusters(UCs)and match RIS with each UC.Then,the fractional programming(FP)method is employed to transform non-convex maximization and rate problems into convex optimization problems.Finally,power allocation(PA)and passive beamforming(PB)are performed sequentially for users within UCs.Simulation results demonstrate that,compared to spectral clustering(SPC),K-means,Gaussian mixture model(GMM)clustering schemes and orthogonal mul-tiple access(OMA),the AGD scheme yields approximately 7%,14%,19%and 42%gains in power-to-spectral efficiency,while RIS contributes approximately 16%,19%,26%and 40%improvements in spectral efficiency.
国家科技期刊平台
NSTL
万方数据
维普
