基于NOMA的室内可见光通信最优功率分配方案

Optimal Power Allocation Scheme for Indoor Visible Light Communication Based on NOMA

在基于非正交多址接入技术的多用户下行室内可见光通信(Visible light communication system based on non⁃orthogonal multiple access technology,VLC⁃NOMA)系统中,针对和速率与用户公平性冲突的问题,提出一种基于加权和速率最大化的迭代功率分配方案。该方案以最大化加权和速率为目标,可通过改变权重因子来调节用户公平性。由于目标问题属于非凸优化问题,通过辅助变量法和凸优化理论将该非凸问题转化为凹问题,再通过拉格朗日对偶法进行求解,并根据问题的解设计了一种迭代功率分配算法。对所提算法的收敛性、系统和速率以及用户公平性进行了仿真。结果表明,所提迭代功率分配算法具有良好的收敛性,相较于VLC⁃OMA系统,VLC⁃NOMA系统能够获得更好的和速率性能。通过调整权重因子,在牺牲较小系统和速率的情况下能够获得比现有功率分配方案更好的系统和速率与用户公平性。

In multi-user downlink indoor visible light communication system based on non-orthogonal multiple access technology(VLC-NOMA),an iterative power allocation scheme based on weighted sumrate maximization is proposed to solve the problem of the conflict between sum-rate and user fairness.The objective of this scheme is to maximize the weighted sum-rate,and the user fairness can be adjusted by changing the weighted factor.Since the target problem is a non-convex optimization problem,this nonconvex problem is transformed into a concave problem by auxiliary variable method and convex optimization theory,then solved by the Lagrange dual method,and an iterative power allocation algorithm is designed according to the solution of the problem.The convergence of the proposed algorithm,system sum-rate and user fairness are simulated.Results show that the proposed iterative power allocation algorithm has good convergence,and VLC-NOMA system can obtain better sum-rate performance than VLC-OMA system.By adjusting the weighted factor,better system sum-rate and user fairness can be obtained than the existing power allocation scheme at the smaller expense of system sum-rate.