IRS-OFDMA系统中基于用户QoS的下行资源分配方案

Downlink resource optimization scheme based on user’s QoSfor IRS-assisted OFDMA system

针对智能反射面(intelligent reflecting surface,IRS)辅助的正交频分多址(orthogonal frequency division multiple access,OFDMA)系统中最大化下行系统吞吐量问题,在保障用户服务质量(quality of service,QoS)的前提下,提出了一种有关子载波、功率和IRS反射相位的资源分配方案。在固定反射相位的情况下,基于用户优先级准则分配载波,载波分配后采用注水算法对用户载波间功率进行分配;在固定子载波和功率分配的情况下,通过连续凸逼近求出相位解;多次交替优化后在满足迭代次数及收敛精度要求时,得到子载波分配因子、功率分配系数和反射相位的近似解。仿真结果表明,方案相较于其他方案可以有效提高系统吞吐量且保障用户QoS速率。

Aiming to improve the downlink system throughput in intelligent reflecting surface(IRS)assisted orthogonal frequency division multiple access(OFDMA),this paper proposes a resource allocation scheme based on user’s quality of service(QoS),which jointly optimizes the subcarrier allocation,power allocation and the phase shifts of the IRS.Firstly,with fixed reflection phases,subcarriers are allocated based on a user priority criterion,followed by distributing power among user subcarriers using a water-filling algorithm.Secondly,with fixed subcarrier and power allocation,the phase solution is derived through successive convex approximation.Finally,we obtain the approximate solutions of the subcarrier distribution factor,power distribution coefficient and reflection phase after serval times of alternate optimization,satisfying the requirements of iteration times and convergence accuracy.Simulation results show that compared with other schemes,the proposed scheme can effectively improve OFDMA system throughput and guarantee user’s QoS.