This paper investigates intelligent reflecting surface (IRS)-aided multicell wireless networks, where an IRS is deployed to assist the joint processing coordinated multipoint (JP-CoMP) transmission from multiple base stations (BSs) to multiple cell-edge users. By taking into account the fairness among cell-edge users, we aim at maximizing the minimum achievable rate of cell-edge users by jointly optimizing the transmit beamforming at the BSs and the phase shifts at the IRS. As a compromise approach, we transform the non-convex max-min problem into an equivalent form based on the mean-square error method, which facilities the design of an efficient suboptimal iterative algorithm. In addition, we investigate two scenarios, namely the single-user system and the multiuser system. For the former scenario, the optimal transmit beamforming is obtained based on the dual subgradient method, while the phase shift matrix is optimized based on the Majorization-Minimization method. For the latter scenario, the transmit beamforming matrix and phase shift matrix are obtained by the second-order cone programming and semidefinite relaxation techniques, respectively. Numerical results demonstrate the significant performance improvement achieved by deploying an IRS. Furthermore, the proposed JP-CoMP design significantly outperforms the conventional coordinated scheduling/coordinated beamforming coordinated multipoint (CS/CB-CoMP) design in terms of max-min rate.

中文翻译：

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智能反射面辅助联合处理协调多点传输

本文研究了智能反射面 (IRS) 辅助的多小区无线网络，其中部署了 IRS 以协助联合处理从多个基站 (BS) 到多个小区边缘用户的协调多点 (JP-CoMP) 传输。通过考虑小区边缘用户之间的公平性，我们旨在通过联合优化 BS 的发射波束成形和 IRS 的相移来最大化小区边缘用户的最小可实现速率。作为一种折衷方法，我们将非凸最大最小问题转换为基于均方误差方法的等效形式，这有助于设计高效的次优迭代算法。此外，我们研究了两种场景，即单用户系统和多用户系统。对于前一种情况，基于对偶次梯度法得到最优发射波束成形，而基于Majorization-Minimization法优化相移矩阵。对于后一种情况，发射波束成形矩阵和相移矩阵分别通过二阶锥规划和半定松弛技术获得。数值结果表明通过部署 IRS 实现了显着的性能改进。此外，所提出的 JP-CoMP 设计在最大-最小速率方面明显优于传统的协调调度/协调波束成形协调多点 (CS/CB-CoMP) 设计。发射波束成形矩阵和相移矩阵分别通过二阶锥规划和半定松弛技术得到。数值结果表明通过部署 IRS 实现了显着的性能改进。此外，所提出的 JP-CoMP 设计在最大-最小速率方面明显优于传统的协调调度/协调波束成形协调多点 (CS/CB-CoMP) 设计。发射波束成形矩阵和相移矩阵分别通过二阶锥规划和半定松弛技术得到。数值结果表明通过部署 IRS 实现了显着的性能改进。此外，所提出的 JP-CoMP 设计在最大-最小速率方面明显优于传统的协调调度/协调波束成形协调多点 (CS/CB-CoMP) 设计。