TY - GEN
T1 - Channel Capacity Enhancement for Terahertz Massive MIMO Systems Relying on Line-of-Sight RIS
AU - Chen, Shaobin
AU - Wan, Ziwei
AU - Ying, Keke
AU - Mei, Yikun
AU - Gao, Zhen
N1 - Publisher Copyright:
© 2023 IEEE.
PY - 2023
Y1 - 2023
N2 - 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.
AB - 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.
KW - LOS-RIS
KW - Terahertz communications
KW - massive MIMO
KW - reconfigurable intelligent surface
UR - http://www.scopus.com/inward/record.url?scp=85185874319&partnerID=8YFLogxK
U2 - 10.1109/WCSP58612.2023.10404968
DO - 10.1109/WCSP58612.2023.10404968
M3 - Conference contribution
AN - SCOPUS:85185874319
T3 - 2023 IEEE 15th International Conference on Wireless Communications and Signal Processing, WCSP 2023
SP - 1126
EP - 1131
BT - 2023 IEEE 15th International Conference on Wireless Communications and Signal Processing, WCSP 2023
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 15th IEEE International Conference on Wireless Communications and Signal Processing, WCSP 2023
Y2 - 2 November 2023 through 4 November 2023
ER -