| Title | Beyond Cell-Free MIMO: Energy Efficient Reconfigurable Intelligent Surface Aided Cell-Free MIMO Communications |
| Authors | Zhang, Yutong Di, Boya Zhang, Hongliang Lin, Jinlong Xu, Chenren Zhang, Daqing Li, Yonghui Song, Lingyang |
| Affiliation | Peking Univ, Dept Elect, Beijing 100871, Peoples R China Imperial Coll London, Dept Comp, London SW7 2BU, England Princeton Univ, Dept Elect Engn, Princeton, NJ 08544 USA Peking Univ, Sch Software & Microelect, Beijing 100871, Peoples R China Peking Univ, Dept Comp Sci & Technol, Beijing 100871, Peoples R China Univ Sydney, Sch Elect & Informat Engn, Sydney, NSW 2006, Australia |
| Keywords | FREE MASSIVE MIMO BEAMFORMING DESIGN CHANNEL ESTIMATION PART I OPTIMIZATION |
| Issue Date | Jun-2021 |
| Publisher | IEEE TRANSACTIONS ON COGNITIVE COMMUNICATIONS AND NETWORKING |
| Abstract | Cell-free systems can effectively eliminate the inter-cell interference by enabling multiple base stations (BSs) to cooperatively serve users without cell boundaries at the expense of high costs of hardware and power sources due to the large-scale deployment of BSs. To tackle this issue, the low-cost reconfigurable intelligent surface (RIS) can serve as a promising technique to improve the energy efficiency of cell-free systems. In this article, we consider an RIS aided cell-free MIMO system where multiple RISs are deployed around BSs and users to create favorable propagation conditions via reconfigurable reflections in a low-cost way, thereby enhancing cell-free MIMO communications. To maximize the energy efficiency, a hybrid beamforming (HBF) scheme consisting of the digital beamforming at BSs and the RIS-based analog beamforming is proposed. The energy efficiency maximization problem is formulated and an iterative algorithm is designed to solve this problem. The impact of the transmit power, the number of RIS, and the RIS size on energy efficiency are investigated. Both theoretical analysis and simulation results reveal that the optimal energy efficiency depends on the numbers of RISs and the RIS size. Numerical evaluations also show that the proposed system can achieve a higher energy efficiency than conventional ones. |
| URI | http://hdl.handle.net/20.500.11897/617682 |
| ISSN | 2332-7731 |
| DOI | 10.1109/TCCN.2021.3058683 |
| Indexed | EI SCI(E) |
| Appears in Collections: | 电子学院 软件与微电子学院 信息科学技术学院 |
