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A Novel Channel Model for Reconfigurable Intelligent Surfaces with Consideration of Polarization and Switch Impairments

De-Ming Chian, Chao-Kai Wen, Chi-Hung Wu, Fu-Kang Wang, Kai-Kit Wong

TL;DR

A new channel model for RIS is proposed that considers important properties, including the reflected field, scattered field, and antenna resonant mode, and is an improvement over existing models and can be used in the practical design of RIS technology.

Abstract

Future wireless networks require the ability to actively adjust the wireless environment to meet strict performance indicators. Reconfigurable Intelligent Surface (RIS) technology is gaining attention for its advantages of low power consumption, cost-effectiveness, and ease of deployment. However, existing channel models for RIS often ignore important properties, such as the impairment in the RIS's switch component and the polarization efficiency among antennas, limiting their practical use. In this paper, we propose a new channel model for RIS that considers these ignored properties, including the reflected field, scattered field, and antenna resonant mode. We verify the proposed model through the practical implementation of a 4 x 4 RIS array with patch antennas in the 3.5 GHz band, using a phase shifter as the switch component of a RIS element. The equivalent model of the phase shifter is also formulated and incorporated into the channel model. We propose a blind controlling algorithm to discuss the properties of our channel model and emphasize the importance of considering polarization and tracking mechanisms for the controlling algorithm. Our channel model is an improvement over existing models and can be used in the practical design of RIS technology. The proposed algorithm provides a practical approach to controlling the wireless environment, suitable for various wireless applications.

A Novel Channel Model for Reconfigurable Intelligent Surfaces with Consideration of Polarization and Switch Impairments

TL;DR

A new channel model for RIS is proposed that considers important properties, including the reflected field, scattered field, and antenna resonant mode, and is an improvement over existing models and can be used in the practical design of RIS technology.

Abstract

Future wireless networks require the ability to actively adjust the wireless environment to meet strict performance indicators. Reconfigurable Intelligent Surface (RIS) technology is gaining attention for its advantages of low power consumption, cost-effectiveness, and ease of deployment. However, existing channel models for RIS often ignore important properties, such as the impairment in the RIS's switch component and the polarization efficiency among antennas, limiting their practical use. In this paper, we propose a new channel model for RIS that considers these ignored properties, including the reflected field, scattered field, and antenna resonant mode. We verify the proposed model through the practical implementation of a 4 x 4 RIS array with patch antennas in the 3.5 GHz band, using a phase shifter as the switch component of a RIS element. The equivalent model of the phase shifter is also formulated and incorporated into the channel model. We propose a blind controlling algorithm to discuss the properties of our channel model and emphasize the importance of considering polarization and tracking mechanisms for the controlling algorithm. Our channel model is an improvement over existing models and can be used in the practical design of RIS technology. The proposed algorithm provides a practical approach to controlling the wireless environment, suitable for various wireless applications.
Paper Structure (15 sections, 26 equations, 12 figures, 1 table, 1 algorithm)

This paper contains 15 sections, 26 equations, 12 figures, 1 table, 1 algorithm.

Table of Contents

  1. I. Introduction
  2. II. RIS Modeling
  3. III. Channel Model for RIS
  4. IV. Blind Controlling Algorithm
  5. V. Experiments, Simulations, and Discussions
  6. VI. Conclusion

Figures (12)

  • Figure 1: (a) RIS element, (b) transmission line model for a $4$-bits DPS in a RIS element, and (c) channel model for a RIS element.
  • Figure 2: Reflection coefficient of our $4$-bits DPS-O.
  • Figure 3: (a) Coordinate system on the patch antenna. The patch antenna's normalized (b) total antenna gain, (c) vertical antenna gain ${\bf E}^{\rm V}$, and (d) horizontal antenna gain ${\bf E}^{\rm H}$ for all angle pairs by being measured in the anechoic chamber.
  • Figure 4: Experimental setup for the transmit antenna and the receive antenna scenario (a) without or (b) with the RIS element.
  • Figure 5: Rotation of the receive antenna corresponding to Fig. \ref{['fig:Environment']}(a).
  • ...and 7 more figures