Multi-Frequency Measurement and Analysis for RIS-assisted MIMO Communication System in Outdoor Environment

• Published in: 2024 IEEE/CIC International Conference on Communications in China (ICCC) pp. 786 - 791
• Main Authors: Gao, Boning, Sang, Jian, Lan, Jifeng, Yang, Chenhong, Wang, Ziang, Li, Xiao, Tang, Wankai, Wang, Haiming, Jin, Shi
• Format: Conference Proceeding
• Language: English
• Published: IEEE 07.08.2024
• Subjects: Channel capacity; channel measurement; Couplings; Frequency division multiplexing; Frequency measurement; Millimeter wave measurements; MIMO channel model; Reconfigurable intelligent surfaces; RIS-assisted system; Wireless communication
• DOI: 10.1109/ICCC62479.2024.10682029

Reconfigurable intelligent surface (RIS) is regarded as a highly promising technology in the forthcoming 6 G communication system, due to its capability of manipulating the wireless propagation environment. However, the channel measurement and modeling of RIS-assisted multiple-input multiple-output (MIMO) system in practical environment, which is very important for practical transmission design, is rarely reported. Thus, in this paper, we conduct the channel measurement for RIS-assisted MIMO communication systems at sub-6 \mathbf{G H z} and millimeter wave (mmWave) frequency bands in an outdoor environment. Three representative communication cases including the non-line-of-sight (NLOS), line-of-sight (LOS) and obstructed-line-of-sight (OLOS) scenarios are measured. The improvements brought by RIS on the power gain and multiplexing gain are evaluated, based on the empirical data. In addition, the Weichselberger channel model is utilized for characterizing the correlation between sub-channels of the RIS-assisted MIMO system. The results demonstrate that the employment of RIS provides power gain in NLOS scenario, while offering multiplexing gain in LOS and OLOS scenarios. It is evidenced that the Weichselberger model is capable of predicting the RIS-assisted MIMO channel characteristics accurately. By analyzing the coupling matrix extracted from the Weichselberger model, it indicates that the channel capacity improvement brought by RIS originates from creating an additional transmission path between the transceiver ends.