基于低分辨率DAC的IRS辅助去蜂窝大规模MIMO系统联合预编码设计  

Joint Precoding for IRS-assisted Cell-Free Massive MIMO Systems with Low-resolution DACs

作　　者：李飞[1] 耿晨雨 李汀[1] 季薇[1] 梁彦[1] 闫志伟 LI Fei;GENG Chenyu;LI Ting;JI Wei;LIANG Yan;YAN Zhiwei(School of Communications and Information Engineering,Nanjing University of Posts and Telecommunications,Nanjing,Jiangsu 210003,China)

机构地区：[1]南京邮电大学通信与信息工程学院,江苏南京210003

出　　处：《信号处理》2023年第6期1070-1078,共9页Journal of Signal Processing

基　　金：国家自然科学基金(61871238,62271265)。

摘　　要：本文研究了下行链路智能反射面(Intelligent Reflective Surface, IRS)辅助去蜂窝大规模MIMO(Cell-Free Massive Multiple-Input Multiple-Output)系统,其中每个接入点(Access Point, AP)都采用了低分辨率的数模转换器(Digital-to-Analog Converters,DAC)。本文将IRS应用于去蜂窝系统并在AP处配备低分辨率DAC,进一步降低了硬件成本和功耗。采用加性量化噪声模型对低分辨率DAC进行数学建模,进而建立了下行链路用户和速率的表达式。由于公式具有非凸性和高复杂性,本文提出了一个交替优化框架来解决此问题,从而提高用户和速率。特别地,我们通过分数规划解耦这个问题,并采用拉格朗日乘子法和半定规划(Semi-Definite Programming,SDP)方法求得预编码矩阵和相移矩阵的表达式。最后,仿真结果表明,与传统的去蜂窝网络相比,该方案下的网络容量可以显著提高。In this paper,we studied a downlink Intelligent Reflective Surface(IRS)-assisted cell-free Massive multipleinput multiple-output(MIMO)system in which each Access Point(AP)used low-resolution Digital-to-analog Converters(DACs).To further reduce the hardware cost and power consumption,we combined IRS with cell-free system and equipped the AP with a low-resolution DACs.And then we mathematically modeled the low-resolution DACs using an additive quantization noise model,while establishing expressions for downlink users sum rate.Due to the non-convexity and high complexity of this formulation,an alternating optimization framework was proposed in this paper to solve this problem in order to improve the user sum rate.In particular,we decoupled this problem by fractional programming and used the Lagrange multiplier method as well as semi-definite programming(SDP)method to obtain the expressions of precoding matrix and phase shift matrix.Finally,the simulation results show that the network capacity under this scheme can be significantly improved compared with traditional cell-free network.

关 键 词：去蜂窝大规模MIMO 智能反射面 低分辨率DAC 联合预编码 

分 类 号：TN928[电子电信—通信与信息系统]