Compact user-specific reconfigurable intelligent surfaces for uplink transmission
Compact user-specific reconfigurable intelligent surfaces for uplink transmission
Large-scale antenna arrays employed by the base station (BS) constitute an essential next-generation communications technique. However, due to the constraints of size, cost, and power consumption, it is usually considered unrealistic to use a large-scale antenna array at the user side. Inspired by the emerging technique of reconfigurable intelligent surfaces (RIS), we firstly propose the concept of user-specific RIS (USRIS) for facilitating the employment of a large-scale antenna array at the user side in a cost- and energy-efficient way. In contrast to the existing employments of RIS, which belong to the family of base-station-specific RISs (BSS-RISs), the US-RIS concept by definition facilitates the employment of RIS at the user side for the first time. This is achieved by conceiving a multilayer structure to realize a compact form-factor. Furthermore, our theoretical results demonstrate that, in contrast to the existing single-layer structure, where only the phase of the signal reflected from RIS can be adjusted, the amplitude of the signal penetrating multi-layer US-RIS can also be partially controlled, which brings about a new degree of freedom (DoF) for beamformer design that can be beneficially exploited for performance enhancement. In addition, based on the proposed multi-layer US-RIS, we formulate the signal-to-noise ratio (SNR) maximization problem of US-RIS-aided communications. Due to the non-convexity of the problem introduced by this multi-layer structure, we propose a multi-layer transmit beamformer design relying on an iterative algorithm for finding the optimal solution by alternately updating each variable. Finally, our simulation results verify the superiority of the proposed multi-layer US-RIS as a compact realization of a large-scale antenna array at the user side for uplink transmission.
Costs, Employment, Phased arrays, Radio frequency, Reconfigurable intelligent surfaces (RIS), Signal to noise ratio, Uplink, Wireless communication, large-scale antenna arrays, multi-layer structure, transmit beamformer design
Liu, Kunzan
8d57a958-1d03-437c-8101-8f5af5ac53f1
Zhang, Zijian
71906992-0498-414d-b79f-1fc0e4c1c091
Dai, Linglong
3eb50fc9-2845-4b5a-9644-35828b2fddbf
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1
Liu, Kunzan
8d57a958-1d03-437c-8101-8f5af5ac53f1
Zhang, Zijian
71906992-0498-414d-b79f-1fc0e4c1c091
Dai, Linglong
3eb50fc9-2845-4b5a-9644-35828b2fddbf
Hanzo, Lajos
66e7266f-3066-4fc0-8391-e000acce71a1
Liu, Kunzan, Zhang, Zijian, Dai, Linglong and Hanzo, Lajos
(2021)
Compact user-specific reconfigurable intelligent surfaces for uplink transmission.
IEEE Transactions on Communications.
(doi:10.1109/TCOMM.2021.3124953).
Abstract
Large-scale antenna arrays employed by the base station (BS) constitute an essential next-generation communications technique. However, due to the constraints of size, cost, and power consumption, it is usually considered unrealistic to use a large-scale antenna array at the user side. Inspired by the emerging technique of reconfigurable intelligent surfaces (RIS), we firstly propose the concept of user-specific RIS (USRIS) for facilitating the employment of a large-scale antenna array at the user side in a cost- and energy-efficient way. In contrast to the existing employments of RIS, which belong to the family of base-station-specific RISs (BSS-RISs), the US-RIS concept by definition facilitates the employment of RIS at the user side for the first time. This is achieved by conceiving a multilayer structure to realize a compact form-factor. Furthermore, our theoretical results demonstrate that, in contrast to the existing single-layer structure, where only the phase of the signal reflected from RIS can be adjusted, the amplitude of the signal penetrating multi-layer US-RIS can also be partially controlled, which brings about a new degree of freedom (DoF) for beamformer design that can be beneficially exploited for performance enhancement. In addition, based on the proposed multi-layer US-RIS, we formulate the signal-to-noise ratio (SNR) maximization problem of US-RIS-aided communications. Due to the non-convexity of the problem introduced by this multi-layer structure, we propose a multi-layer transmit beamformer design relying on an iterative algorithm for finding the optimal solution by alternately updating each variable. Finally, our simulation results verify the superiority of the proposed multi-layer US-RIS as a compact realization of a large-scale antenna array at the user side for uplink transmission.
Text
US-RIS
- Accepted Manuscript
More information
Accepted/In Press date: 26 October 2021
e-pub ahead of print date: 13 November 2021
Additional Information:
Publisher Copyright:
IEEE
Keywords:
Costs, Employment, Phased arrays, Radio frequency, Reconfigurable intelligent surfaces (RIS), Signal to noise ratio, Uplink, Wireless communication, large-scale antenna arrays, multi-layer structure, transmit beamformer design
Identifiers
Local EPrints ID: 452575
URI: http://eprints.soton.ac.uk/id/eprint/452575
ISSN: 0090-6778
PURE UUID: 038d69db-bcb1-4b7a-85b6-57b977d3ff40
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Date deposited: 11 Dec 2021 11:27
Last modified: 18 Mar 2024 02:36
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Contributors
Author:
Kunzan Liu
Author:
Zijian Zhang
Author:
Linglong Dai
Author:
Lajos Hanzo
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