This article proposes a novel framework of resource allocation in multi-cell intelligent reflecting surface (IRS) aided non-orthogonal multiple access (NOMA) networks, where an IRS is deployed to enhance the wireless service. The problem of joint user association, subchannel assignment, power allocation, phase shifts design, and decoding order determination is formulated for maximizing the achievable sum rate. The challenging mixed-integer non-linear problem is decomposed into an optimization subproblem (P1) with continuous variables and a matching subproblem (P2) with integer variables. In an effort to tackle the non-convex optimization problem (P1), iterative algorithms are proposed for allocating transmission power, designing reflection matrix, and determining decoding order by invoking relaxation methods such as convex upper bound substitution, successive convex approximation, and semidefinite relaxation. In terms of the combinational problem (P2), swap matching-based algorithms are developed for achieving a two-sided exchange-stable state among users, BSs and subchannels. Numerical results demonstrate that: i) the sum rate of multi-cell NOMA networks is capable of being increased by 35% with the aid of the IRS; ii) the proposed algorithms for multi-cell IRS-aided NOMA networks can enjoy 22% higher energy efficiency than conventional NOMA counterparts; iii) the trade-off between spectrum efficiency and coverage area can be tuned by judiciously selecting the location of the IRS.

中文翻译：

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多小区 IRS 辅助 NOMA 网络的资源分配


本文提出了一种多小区智能反射面 (IRS) 辅助非正交多址 (NOMA) 网络中的资源分配新框架，其中部署 IRS 来增强无线服务。联合用户关联、子信道分配、功率分配、相移设计和解码顺序确定的问题被公式化以最大化可实现的总速率。具有挑战性的混合整数非线性问题被分解为具有连续变量的优化子问题（P1）和具有整数变量的匹配子问题（P2）。为了解决非凸优化问题（P1），提出了迭代算法来分配传输功率，设计反射矩阵，并通过调用凸上界替换、逐次凸逼近和半定松弛等松弛方法来确定解码顺序。在组合问题（P2）方面，开发了基于交换匹配的算法，以实现用户、BS和子信道之间的双边交换稳定状态。数值结果表明： i) 在IRS的帮助下，多小区NOMA网络的总速率能够提高35%； ii) 所提出的多小区 IRS 辅助 NOMA 网络算法可以比传统 NOMA 网络提高 22% 的能源效率； iii) 频谱效率和覆盖区域之间的权衡可以通过明智地选择 IRS 的位置来调整。