IRS辅助WPCN用户公平性与系统吞吐量优化方案

User fairness and system throughput optimization scheme forIRS-assisted WPCN

为了解决无线供电网(wireless powered communication network,WPCN)中用户公平性不足与系统灵活性差的问题,提出一种基于智能反射面(intelligent reflecting surface,IRS)的优化方案。该方案直接将公平指数(fairness index,FI)和系统吞吐量加权相加作为优化目标,建立了用户公平性与系统吞吐量的联合优化问题。由于所建立的优化问题是非凸问题,因此,将优化问题拆分为时隙长度和IRS反射系数优化子问题,然后交替求解。针对时隙长度优化子问题,使用逐次凸逼近(successive convex approximation,SCA)算法求解;针对IRS反射系数优化子问题,使用闭式解、SCA和半定松弛(semi definite relaxation,SDR)算法求解。仿真结果表明,所提方案在用户公平性和系统灵活性方面优于其他方案。

To solve the problem of low user fairness and flexibility in WPCN,we propose an optimization scheme based on IRS.The scheme directly takes the sum of weighted FI and system throughput as the optimization goal,and establishes the joint optimization problem of user fairness and system throughput.Since the established optimization problem is nonconvex,the optimization problem is divided into the subproblems of slot length and IRS reflection coefficient optimization,and then they are solved alternately.For the slot length optimization,SCA algorithm is used to solve it.For the IRS reflection coefficient optimization,the closed form solution,SCA and SDR algorithms are used to solve it.Simulation results show that the proposed scheme is superior to other schemes in terms of user fairness and system flexibility.