Holographic Metasurfaces for Extremely Large-Scale MIMO Communications: Design, Implementation, and Experiment Results
Boya Di, Yutong Zhang, Ruoqi Deng, Mengjun Wang, Shaohui Sun, Lingyang Song
Abstract
Benefited from its high spectral efficiency, extremely large-scale multiple-input multiple-output (XL-MIMO) has emerged as a leading technology, captivating the attention of both academia and industry in the 6G era, particularly in the millimeter wave (mm-Wave) band due to its wide bandwidth. Despite its potential, mm-Wave XL-MIMO faces significant challenges due to prohibitively high hardware costs and power consumption of large-scale antenna arrays. In this article, we propose a cost-efficient and power-efficient way to enable XL-MIMO using reconfigurable holographic surface (RHS) which is a novel antenna fabricated with numerous programmable metamaterial elements instead of phase shifters. Specifically, we design a 256-element RHS array prototype operating in mm-Wave band. Utilizing the orthogonal polarizations of multiple RHS arrays, a highly-integrated transmitter is developed to support 2-stream transmission via multiple RHS arrays. Given that, we implement an RHS-enabled XL-MIMO communication prototype for multi-user multi-stream communication. Based on the standards of 3GPP, two test cases are presented to evaluate the performance of our prototype with respect to single-user beam tracking and multi-user transmission. Experimental results show that our prototype boasts both a high data rate and lower power consumption compared to traditional antenna arrays. Future research directions and challenges for RHS-enabled XL-MIMO communications are also discussed.