物联网学报

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基于统计 CSI 的空中智能反射面辅助大规模 MIMO 系统传输优化方案

马露洁 梁彦 李飞   

  1. 南京邮电大学通信与信息工程学院,江苏 南京 210003
  • 作者简介:马露洁(1997-),女,南京邮电大学通信与信息工程学院硕士研究生,主要研究方向为空中智能反射面辅助系统的波束成形技术。 梁彦(1979-),女,博士, 南京邮电大学通信与信息工程学院副教授,硕士生导师、博士,主要研究方向为无线通信、信号处理。 李飞(1966-),女,博士,南京邮电大学通信与信息工程学院教授,博士生导师,主要研究方向为量子智能计算、群智能算法和无线通信中的信号处理算法。

The transmission optimization scheme of aerial intelligent reflecting surface-aided massive MIMO systems based on statistical CSI

MA Lujie LIANG Yan LI Fei   

  1. School of Communications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

摘要: 智能反射面(IRS)被认为是下一代移动通信的核心技术,其在增强网络覆盖、频谱效率、能源效率和部署成本方面具有显著优势。空中智能反射面(AIRS)结合了空中平台的高移动性和智能反射面提供的优质链路特性,可以有效解决复杂通信场景中基站与用户之间易受障碍物阻挡的问题,从而增强网络覆盖。针对 AIRS 辅助的多用户大规模多输入多输出(MIMO)系统,研究了基站波束成形、AIRS 部署位置与相移设计的联合优化问题。在已知统计信道状态信息(CSI)的条件下,提出了一种基于块坐标下降法(BCD)的系统遍历和速率优化方案。首先,建立了一个联合优化基站端波束成形、AIRS 的部署位置与 AIRS 相移的复杂优化模型。其次,通过 BCD下降算法,将非凸优化问题解耦成三个易于处理的子问题。最后分别采用拉格朗日乘子法、松弛变量法和 RMSProp 梯度下降算法求解子问题。仿真结果表明,所提出的优化方案有效地提高了系统的遍历和速率,并且具有较好的收敛性。

关键词: 大规模 MIMO, 空中智能反射面, 统计信道状态信息, 位置优化, 波束成形

Abstract: The intelligent reflecting surface (IRS) is considered a core technology of next-generation mobile communication. It has significant advantages in enhancing network coverage, spectrum efficiency, energy efficiency, and deployment cost. The aerial intelligent reflecting surface (AIRS), which combines the high mobility of the air platform and the high-quality link characteristics provided by the intelligent reflecting surface, can effectively assist the transmission from the base station to the users in complex communication scenarios and enhance the network coverage. A joint optimization problem of the transmit beamforming, as well as the placement and passive beamforming for the AIRS was studied for AIRS assisted multi-user massive multiple input multiple output (MIMO) systems. Under the condition that the statistical channel state information (CSI) is known, an optimization scheme of system ergodic sum rate based on block coordinate descent (BCD) was proposed. Firstly, an optimization model was established by jointly optimizing the transmit beamforming at base station, the placement and the passive beamforming for AIRS. Secondly, the nonconvex optimization problem was decoupled into three subproblems that are easy to deal with by BCD descent algorithm. Finally, Lagrange multiplier method, relaxation variable method and RMSProp gradient descent algorithm were used to solve the subproblems respectively. The simulation results show that the proposed optimization scheme can effectively improve the ergodic sum rate of the system with good convergence properties.

Key words: Massive MIMO, Aerial intelligent reflecting surface, Statistical CSI, Location optimization, Beam forming

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