动态超表面天线阵列混合发射波束成形

Hybrid transmit beamforming for dynamic metasurface antenna array

动态超表面天线(dynamic metasurface antenna,DMA)阵列是一种可实现模拟-数字混合波束成形的新型阵列结构,其模拟波束成形部分由DMA实现,系统实现的复杂度低。本文研究基于DMA阵列的混合发射波束成形,核心问题是模拟与数字发射权值的联合优化。该文基于交替优化思想将模拟-数字权值联合优化问题分解为多个子问题,提出一种基于交替方向乘子法(alternating direction multiplier method,ADMM)的求解方法。该方法首先引入辅助变量简化问题模型,然后通过交替优化求解辅助变量、数字权值和模拟权值。其中,辅助变量求解具有闭式表达式,数字权值与模拟权值解耦合后利用ADMM分别求解。仿真结果表明,DMA阵列与典型的唯相混合阵列和恒模约束下的唯相阵列相比,具有更好的混合发射波束成形性能。

Dynamic metasurface antenna(DMA)array is a novel structure to implement the analog-digital hybrid beamforming,in which the analog beamforming part is realized by the DMA and thus the system complexity is low.The DMA array-based hybrid transmit beamforming is studied,and the core problem is the joint optimization of analog and digital transmit weights.In virtue of alternating optimization,this paper decomposes the joint optimization problem into several sub-problems and then proposes a solving method by using alternating direction multiplier method(ADMM).The proposed method simplifies the problem model by introducing auxiliary variables firstly,and then resolves the auxiliary variables,digital weights and analog weights by alternating optimization.Among them,the solution of auxiliary variables has a closed-form expression,after decoupling,the digital weights and analog weights are solved separately by ADMM,respectively.Simulation results show that the proposed DMA array has better performance of hybrid transmit beamforming than the typical phase-only hybrid array and phase-only array under constant modulus constraints.