Multi-Group Multicasting Systems Using Multiple RISs

作     者：Lee, Hyeongtaek Moon, Seungsik Lee, Youngjoo Oh, Jaeky Chung, Jaehoon Choi, Junil 

作者机构：Korea Adv Inst Sci & Technol Sch Elect Engn Daejeon 34141 South Korea Pohang Univ Sci & Technol Dept Elect Engn Pohang 37673 South Korea LG Elect Inc 6G Core Res & Dev Technol Platform TP Commun & Media Stand Lab ICT Technol CtrCTO Div Seoul 06772 South Korea 

出 版 物：《IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS》 (IEEE Trans. Wireless Commun.)

年 卷 期：2024年第23卷第8期

页      面：9488-9501页

核心收录：

学科分类：0810[工学-信息与通信工程] 0808[工学-电气工程] 08[工学] 

基　　金：LG Electronics Inc Ministry of Science and ICT(MSIT), South Korea [IITP-2024-2020-0-01787] Korea Institute for Advancement of Technology (KIAT) - Ministry of Trade, Industry and Energy (MOTIE) [P0022557] 

主　　题：Multicast communication Array signal processing Interference Reflection coefficient Downlink Wireless communication Computational complexity Reconfigurable intelligent surface (RIS) multiple distributed RISs multi-group multicasting inter-group interference management 

摘      要：In this paper, practical utilization of multiple distributed reconfigurable intelligent surfaces (RISs), which are able to conduct group-specific operations, for multi-group multicasting systems is investigated. To tackle the inter-group interference issue in the multi-group multicasting systems, the block diagonalization (BD)-based beamforming is considered first. Without any inter-group interference after the BD operation, the multiple distributed RISs are operated to maximize the minimum rate for each group. Since the computational complexity of the BD-based beamforming can be too high, a multicasting tailored zero-forcing (MTZF) beamforming technique is proposed to efficiently suppress the inter-group interference, and the novel design for the multiple RISs that makes up for the inevitable loss of MTZF beamforming is also described. Effective closed-form solutions for the loss minimizing RIS operations are obtained with basic linear operations, making the proposed MTZF beamforming-based RIS design highly practical. Numerical results show that the BD-based approach has ability to achieve high sum-rate, but it is useful only when the base station deploys large antenna arrays. Even with the small number of antennas, the MTZF beamforming-based approach outperforms the other schemes in terms of the sum-rate while the technique requires low computational complexity. The results also prove that the proposed techniques can work with the minimum rate requirement for each group.