RIS-Measurements for Codebook Design

TL;DR

This work addresses creating practical codebooks for RIS by performing detailed reflection measurements of OpenSourceRIS boards in a real environment. The authors systematically vary azimuth/elevation angles, polarization, the number of RIS boards, and the RIS-to-antenna geometry using a $16 \times 16$ RIS with $256$ elements and 1-bit control, implying a pattern space of $2^{256}$. They demonstrate substantial pattern-dependent variability and polarization/distance effects, and show that adding a second RIS alters the angular power distribution, providing empirical guidance for codebook design. The results highlight how careful polarization alignment, distance management, and multi-RIS configurations can enable targeted propagation control in future wireless networks.

Abstract

Reconfigurable Intelligent Surfaces (RIS) have gained significant attention for some time. Thanks to the possibility of individual steering of each reflecting element of the boards, they are envisaged to impact the propagation environment significantly. In this work, we concentrate on the practical verification of this concept. We present the results of detailed measurements of the reflection characteristics of the RIS boards, which have been conducted intentionally in the real environment. Various potential impacting factors have been considered (impact of azimuth and elevation angle, polarization, number of RIS boards, and distance). Achieved measurement results constituted the basis for conceptual analysis on the practical possibility of creating a codebook (consisting of RIS patterns - codewords) for some applications.

Figures (10)

• Figure 1: View of the measured patterns.
• Figure 2: Measurement scheme: A - top view, B - side view
• Figure 3: Side view after additional RIS was added.
• Figure 4: Results for 1st pattern.
• Figure 5: Results for 2nd pattern.