Public defence in Radio Science and Engineering, M.Sc. Sravan Vuyyuru

The title of the thesis: Electromagnetics-consistent design and modeling of reconfigurable intelligent surfaces for next-generation wireless networks

Thesis defender: Sravan Vuyyuru
Opponent: Prof. Oscar Quevedo-Teruel, KTH Royal Institute of Technology, Sweden 
Custos: Prof. Viktar Asadchy, Aalto University School of Electrical Engineering

The exponential growth of smartphones and connected devices strains existing base stations to their limits in capacity and coverage. This research focuses on reconfigurable intelligent surfaces (RIS), engineered panels composed of sub-wavelength scattering elements that can dynamically manipulate electromagnetic (EM) wavefronts. RIS will improve network coverage and capacity in dense scattering environments, predominantly in dead zones. This study advances modeling and synthesis methods for EM scattering and sensing, enabling RIS to be efficient and practical for future wireless networks. The findings contribute to the broader research of wireless communications that bridge communication, sensing, and intelligence using RIS into one unified framework. 

The dissertation is structured into two main parts; the first focuses on EM modeling for synthesizing tunable RIS scatterers, and the second explores the RIS-assisted communication tools for network engineers by integrating EM RIS scattering properties into network simulators. The research develops EM-accurate equivalent circuit models to predict and synthesize the scattering characteristics of the load-controlled RIS. Using the controllable properties, the devices achieve efficient dual functionality, simultaneously sensing and redirecting the impinging wave, without relying on bulky RF chains. These methods are validated through numerical simulations using realistic patch arrays. The second part introduces a RIS-assisted macroscopic communication modeling that incorporates electromagnetically consistent RIS scattering models into network simulators through rapid macroscopic parameter mapping, bridging detailed EM physics with large-scale networks while reducing computational complexity. As a proof of concept, a non-reconfigurable RIS with anomalous reflection functionality is designed, manufactured, and experimentally validated through an anechoic chamber and indoor measurements. 

This dissertation develops an RIS modeling tool for researchers working on advancing wireless network technologies to implement new protocols and technologies. These models should serve as numerical network planning tools with unprecedented physical accuracy to create RIS models in a controlled environment, trying design strategies by simulating and optimizing the patterns, predicting signal propagation, and planning resources before real-world implementation to ensure reliable and cost-effective deployment.

Key words: 6G, reconfigurable intelligent surface (RIS), angle of arrival sensing, anomalous reflector, far-field scattering, integrated sensing and communications (ISAC), loaded scatterers, metasurfaces, network simulators, receiving antennas, smart wall

Thesis available for public display 7 days prior to the defence at Aaltodoc. 

Contact:
sravan.vuyyuru@aalto.fi 
+358 504734381 
https://www.linkedin.com/in/sravan-kumar-reddy-vuyyuru/ 
https://www.aalto.fi/en/department-of-electronics-and-nanoengineering/designer-materials-and-devices

Description of the image: A smart city vision enabled by next-generation communication networks that seamlessly integrate communication, sensing, and computing through reconfigurable intelligent surfaces that adaptively interact with surrounding devices, fostering intelligent, energy-efficient, and ultra-fast connectivity throughout the urban landscape. © Sravan Kumar Reddy Vuyyuru