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arXiv · 2505.07126

AI-Driven Optimization of Wave-Controlled Reconfigurable Intelligent Surfaces

Gal Ben Itzhak·Miguel Saavedra-Melo·Ender Ayanoglu·Filippo Capolino·A. Lee Swindlehurst
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Abstract

A promising type of Reconfigurable Intelligent Surface (RIS) employs tunable control of its varactors using biasing transmission lines below the RIS reflecting elements. Biasing standing waves (BSWs) are excited by a time-periodic signal and sampled at each RIS element to create a desired biasing voltage and control the reflection coefficients of the elements. A simple rectifier can be used to sample the voltages and capture the peaks of the BSWs over time. Like other types of RIS, attempting to model and accurately configure a wave-controlled RIS is extremely challenging due to factors such as device non-linearities, frequency dependence, element coupling, etc., and thus significant differences will arise between the actual and assumed performance. An alternative approach to solving this problem is data-driven: Using training data obtained by sampling the reflected radiation pattern of the RIS for a set of BSWs, a neural network (NN) is designed to create an input-output map between the BSW amplitudes and the resulting sampled radiation pattern. This is the approach discussed in this paper. In the proposed approach, the NN is optimized using a genetic algorithm (GA) to minimize the error between the predicted and measured radiation patterns. The BSW amplitudes are then designed via Simulated Annealing (SA) to optimize a signal-to-leakage-plus-noise ratio measure by iteratively forward-propagating the BSW amplitudes through the NN and using its output as feedback to determine convergence. The resulting optimal solutions are stored in a lookup table to be used both as settings to instantly configure the RIS and as a basis for determining more complex radiation patterns.

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Gal Ben Itzhak, Miguel Saavedra-Melo, Ender Ayanoglu, Filippo Capolino, A. Lee Swindlehurst. 2025-05-11. AI-Driven Optimization of Wave-Controlled Reconfigurable Intelligent Surfaces. https://arxiv.org/abs/2505.07126

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