Channel Capacity Enhancement for Terahertz Massive MIMO Systems Relying on Line-of-Sight RIS

Shaobin Chen*, Ziwei Wan, Keke Ying, Yikun Mei, Zhen Gao*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

This paper investigates channel capacity in the reconfigurable intelligent surfaces (RIS)-assisted multiple-input multiple-output (MIMO) systems operating in the terahertz (THz) band. Specifically, we conceive an evolved version of RIS, namely line-of-sight (LOS)-RIS, where the RIS element spacing is increased to embrace the near-field effect. With the LOS-RIS, the channel capacity can be significantly enhanced even under LOS-only channels. First, we analyze the channel capacity associated with the LOS-RIS as the RIS element spacing increases under single-user scenario, elucidating the underlying reasons for the enlarged spacing. Then, the analysis is extended to multi-user scenario, which unleashes the potential of utilizing a single LOS-RIS to serve multiple users under LOS-only channels. Furthermore, to accommodate multiple users, we propose a passive beamforming scheme, where the large LOS-RIS is partitioned into multiple subarrays and the phase shifts of each subarray are tailored to steer the reflected beams towards the corresponding user. Simulation results verify the effectiveness of the proposed paradigm, which paves the way for supporting multi-user multi-stream THz communications under LOS-only channels.

Original languageEnglish
Title of host publication2023 IEEE 15th International Conference on Wireless Communications and Signal Processing, WCSP 2023
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages1126-1131
Number of pages6
ISBN (Electronic)9798350324662
DOIs
Publication statusPublished - 2023
Event15th IEEE International Conference on Wireless Communications and Signal Processing, WCSP 2023 - Hangzhou, China
Duration: 2 Nov 20234 Nov 2023

Publication series

Name2023 IEEE 15th International Conference on Wireless Communications and Signal Processing, WCSP 2023

Conference

Conference15th IEEE International Conference on Wireless Communications and Signal Processing, WCSP 2023
Country/TerritoryChina
CityHangzhou
Period2/11/234/11/23

Keywords

  • LOS-RIS
  • Terahertz communications
  • massive MIMO
  • reconfigurable intelligent surface

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