Temperature-Resilient LC-RIS Phase-Shift Design for Multi-user Downlink Communications

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Hauptverfasser: Gholian, Nairy Moghadas, Delbari, Mohamadreza, Jamali, Vahid, Asadi, Arash
Format: Preprint
Veröffentlicht: 2025
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author Gholian, Nairy Moghadas
Delbari, Mohamadreza
Jamali, Vahid
Asadi, Arash
author_facet Gholian, Nairy Moghadas
Delbari, Mohamadreza
Jamali, Vahid
Asadi, Arash
contents The reflecting antenna elements in most reconfigurable intelligent surfaces (RISs) use semiconductor-based (e.g., positive-intrinsic-negative (PIN) diodes and varactors) phase shifters. Although effective, a drawback of this technology is the high power consumption and cost, which become particularly prohibitive in millimeter-wave (mmWave)/sub-Terahertz range. With the advances in Liquid Crystals (LCs) in microwave engineering, we have observed a new trend in using LC for realizing phase shifter networks of RISs. LC-RISs are expected to significantly reduce the fabrication costs and power consumption. However, the nematic LC molecules are sensitive to temperature variations. Therefore, implementing LC-RIS in geographical regions with varying temperatures requires temperature-resilient designs. The mentioned temperature variation issue becomes more significant at higher temperatures as the phase shifter range reduces in warmer conditions, whereas it expands in cooler ones. In this paper, we study the impact of temperature on the operation of LC-RISs and develop a temperature-resilient phase shift design. Specifically, we formulate a max-min signal-to-interference-plus-noise ratio optimization for a multi-user downlink mmWave network that accounts for the impact of temperature in the LC-RIS phase shifts. The simulation results demonstrate a significant improvement for the considered set of parameters when using our algorithm compared to the baseline approach, which neglects the temperature effects.
format Preprint
id arxiv_https___arxiv_org_abs_2505_05160
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Temperature-Resilient LC-RIS Phase-Shift Design for Multi-user Downlink Communications
Gholian, Nairy Moghadas
Delbari, Mohamadreza
Jamali, Vahid
Asadi, Arash
Signal Processing
The reflecting antenna elements in most reconfigurable intelligent surfaces (RISs) use semiconductor-based (e.g., positive-intrinsic-negative (PIN) diodes and varactors) phase shifters. Although effective, a drawback of this technology is the high power consumption and cost, which become particularly prohibitive in millimeter-wave (mmWave)/sub-Terahertz range. With the advances in Liquid Crystals (LCs) in microwave engineering, we have observed a new trend in using LC for realizing phase shifter networks of RISs. LC-RISs are expected to significantly reduce the fabrication costs and power consumption. However, the nematic LC molecules are sensitive to temperature variations. Therefore, implementing LC-RIS in geographical regions with varying temperatures requires temperature-resilient designs. The mentioned temperature variation issue becomes more significant at higher temperatures as the phase shifter range reduces in warmer conditions, whereas it expands in cooler ones. In this paper, we study the impact of temperature on the operation of LC-RISs and develop a temperature-resilient phase shift design. Specifically, we formulate a max-min signal-to-interference-plus-noise ratio optimization for a multi-user downlink mmWave network that accounts for the impact of temperature in the LC-RIS phase shifts. The simulation results demonstrate a significant improvement for the considered set of parameters when using our algorithm compared to the baseline approach, which neglects the temperature effects.
title Temperature-Resilient LC-RIS Phase-Shift Design for Multi-user Downlink Communications
topic Signal Processing
url https://arxiv.org/abs/2505.05160