Active-RIS enhances the multi-user rate of multi-carrier communications
Active-RIS enhances the multi-user rate of multi-carrier communications
This paper explores a multi-user multi-carrier system leveraging an active reconfigurable intelligent surface (RIS), where the joint design of the RIS’s programmable reflecting elements and the subcarrier-wise beamformers at the base station is investigated. To overcome the limitation of the conventional design, which aims solely at sum-rate maximization resulting in zero rates for some users across all sub-carriers and thus failing to boost all users rates, we propose the two alternative designs: one maximizing the geometric mean of the users’ rates (GM-rate maximization) and the other maximizing the soft users’ minimum rate (soft max-min rate optimization). However, they pose challenges as large-scale nonconvex problems, rendering convex-solver computational approaches impractical. To tackle this, we develop iterative computational procedures based on closed-form expressions of scalable complexity. Extensive simulations demonstrate the substantial benefits of these novel designs in significantly enhancing multi-user rates. Notably, under the same power budget, the active-RIS-assisted multi-carrier system achieves approximately twice the minimum user-rate or sum rate compared to RIS-less or passive-RIS-assisted counterparts.
Active reconfigurable intelligent surface, Closed-form solutions, Indexes, large-scale computation, multi-carrier communication, multi-user rate enhancement, OFDM, Optimization, Reconfigurable intelligent surfaces, subcarrier-wise beamforming, Symmetric matrices, Vectors
16948-16963
Tuan, H.D.
47dc4b79-2c0f-43bd-8952-d8f4a6a04711
Nasir, A.A.
d97ca733-e302-4089-83a2-3909ca148380
Dutkiewicz, E.
758c11d4-76a2-4df8-8ec9-451a8ff91aab
Poor, H.V
2ce6442b-62db-47b3-8d8e-484e7fad51af
Hanzo, L.
66e7266f-3066-4fc0-8391-e000acce71a1
4 July 2024
Tuan, H.D.
47dc4b79-2c0f-43bd-8952-d8f4a6a04711
Nasir, A.A.
d97ca733-e302-4089-83a2-3909ca148380
Dutkiewicz, E.
758c11d4-76a2-4df8-8ec9-451a8ff91aab
Poor, H.V
2ce6442b-62db-47b3-8d8e-484e7fad51af
Hanzo, L.
66e7266f-3066-4fc0-8391-e000acce71a1
Tuan, H.D., Nasir, A.A., Dutkiewicz, E., Poor, H.V and Hanzo, L.
(2024)
Active-RIS enhances the multi-user rate of multi-carrier communications.
IEEE Transactions on Vehicular Technology, 73 (11), .
(doi:10.1109/TVT.2024.3423433).
Abstract
This paper explores a multi-user multi-carrier system leveraging an active reconfigurable intelligent surface (RIS), where the joint design of the RIS’s programmable reflecting elements and the subcarrier-wise beamformers at the base station is investigated. To overcome the limitation of the conventional design, which aims solely at sum-rate maximization resulting in zero rates for some users across all sub-carriers and thus failing to boost all users rates, we propose the two alternative designs: one maximizing the geometric mean of the users’ rates (GM-rate maximization) and the other maximizing the soft users’ minimum rate (soft max-min rate optimization). However, they pose challenges as large-scale nonconvex problems, rendering convex-solver computational approaches impractical. To tackle this, we develop iterative computational procedures based on closed-form expressions of scalable complexity. Extensive simulations demonstrate the substantial benefits of these novel designs in significantly enhancing multi-user rates. Notably, under the same power budget, the active-RIS-assisted multi-carrier system achieves approximately twice the minimum user-rate or sum rate compared to RIS-less or passive-RIS-assisted counterparts.
Text
aRIS_OFDM_01_07_24_final
- Accepted Manuscript
More information
Accepted/In Press date: 1 July 2024
Published date: 4 July 2024
Additional Information:
Publisher Copyright:
IEEE
Keywords:
Active reconfigurable intelligent surface, Closed-form solutions, Indexes, large-scale computation, multi-carrier communication, multi-user rate enhancement, OFDM, Optimization, Reconfigurable intelligent surfaces, subcarrier-wise beamforming, Symmetric matrices, Vectors
Identifiers
Local EPrints ID: 492054
URI: http://eprints.soton.ac.uk/id/eprint/492054
ISSN: 0018-9545
PURE UUID: b8f602bf-0149-43a0-a687-8eb93795dbe4
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Date deposited: 15 Jul 2024 16:42
Last modified: 12 Dec 2024 02:32
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Contributors
Author:
H.D. Tuan
Author:
A.A. Nasir
Author:
E. Dutkiewicz
Author:
H.V Poor
Author:
L. Hanzo
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