Electromagnetics-consistent design and modeling of reconfigurable intelligent surfaces for next-generation wireless networks
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School of Electrical Engineering |
Doctoral thesis (article-based)
| Defence date: 2025-11-19
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Language
en
Pages
118 + app. 81
Series
Aalto University publication series Doctoral Theses, 230/2025
Abstract
The explosive growth of smartphones, IoT nodes, and other wireless devices is pushing traditional base station-centric networks toward their capacity and coverage limits. To relieve this pressure, research has pivoted toward scattering-based infrastructure, with reconfigurable intelligent surfaces (RISs) emerging as one of the leading candidates. RISs are flat panels equipped with many tiny elements whose properties can be electronically adjusted, so they act like steerable mirrors that bend or redirect wireless signals exactly toward predetermined targets. In essence, they are programmable low-power "smart walls" that help strengthen and shape radio coverage without adding new transmitters. This doctoral thesis presents a practical bridge between the physics of reconfigurable intelligent surfaces and the needs of network engineers. It builds a circuit-based model of large, irregular RIS panels so that their complex wave-shaping behavior can be described by just a handful of tunable impedance values. These concise parameters are optimized for specific tasks, such as beam steering or angle-of-arrival detection, and then fed directly into standard network simulators. The result is a workflow that predicts how RIS-enhanced networks will perform, without running costly full-wave calculations or making extensive field measurements, enabling faster and more accurate design of next-generation wireless systems. The first part of the thesis is devoted to developing a circuit model for load-tunable RIS panels. It shows how to optimally tune the loads at the RIS elements so that the panel can efficiently bend an incoming wave in a chosen direction as well as sense its angle of arrival. By turning every patch into a miniature, programmable scatterer, the surface achieves simultaneous anomalous reflection and sensing without bulky RF chains. Full wave simulations of realistic patch arrays confirm the concept. The second part provides background on RIS scattering models and introduces a macroscopic communication model that integrates electromagnetically consistent RIS scattering models into network simulators. This integration is achieved through rapid macroscopic parameter mapping, significantly reducing modeling complexity and computational overhead.Description
Supervising professor
Asadchy, Viktar, Prof., Aalto University, Department of Electronics and Nanoengineering, FinlandThesis advisor
Valkonen, Risto, Dr., Nokia Bell Labs, FinlandViikari, Ville, Prof., Aalto University, Department of Electronics and Nanoengineering, Finland
Other note
Parts
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[Publication 1]: S. K. R. Vuyyuru, R. Valkonen, D. H. Kwon, and S. A. Tretyakov. Efficient Anomalous Reflector Design Using Array Antenna Scattering Synthesis. IEEE Antennas and Wireless Propagation Letters, Vol. 22, No. 7, pp. 1711 - 1715, July 2023.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202304052675DOI: 10.1109/LAWP.2023.3260920 View at publisher
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[Publication 2]: S. K. R. Vuyyuru, R. Valkonen, S. A. Tretyakov, and D. H. Kwon. Efficient Synthesis of Large Finite Patch Arrays for Scanning Wide-Angle Anomalous Reflectors. IEEE Open Journal of Antennas and Propagation, Vol. 6, No. 1, pp. 75 - 87, February 2025.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202410026602DOI: 10.1109/OJAP.2024.3466890 View at publisher
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[Publication 3]: S. K. R. Vuyyuru, L. Hao, M. Rupp, S. A. Tretyakov, and R. Valkonen. Modeling RIS from Electromagnetic Principles to Communication Systems–Part I: Synthesis and Characterization of a Scalable Anomalous Reflector. IEEE Transactions on Antennas and Propagation, Vol. 73, No. 3, pp. 1743 - 1755, March 2025.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202501151204DOI: 10.1109/TAP.2024.3520416 View at publisher
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[Publication 4]: M. Movahediqomi, S. K. R. Vuyyuru, G. Ptitcyn, R. Valkonen, V. S. Asadchy, D.-H. Kwon, and S. A. Tretyakov. Design and Analysis of Reconfigurable Patch Arrays for Angle-of-Arrival Sensing and Perfect Anomalous Reflection. IEEE Transactions on Antennas and Propagation, November 2025.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202511198807DOI: 10.1109/TAP.2025.3630704 View at publisher
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[Publication 5]: L. Hao, S. K. R. Vuyyuru, S. A. Tretyakov, A. Salihu, M. Rupp, and R. Valkonen. Modeling RIS from Electromagnetic Principles to Communication Systems–Part II: System-Level Simulation, Ray Tracing, and Measurement. IEEE Transactions on Antennas and Propagation, Vol. 73, No. 3, pp. 1756 - 1767, March 2025.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202502242507DOI: 10.1109/TAP.2025.3533902 View at publisher
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[Publication 6]: L. Hao, S. K. R. Vuyyuru, S. A. Tretyakov, M. Rupp, and R. Valkonen. Analysis of Scalable Electromagnetically-Modeled Anomalous Reflectors through Ray Tracing and Measurements. IEEE Open Journal of Antennas and Propagation, August 2025 (Early Access).
DOI: 10.1109/OJAP.2025.3597865 View at publisher