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Wireless networks have become an integral part of our daily life, supporting a myriad of applications. As we march towards 6G and beyond, wireless networks are evolving to support an even broader spectrum of applications and use cases. This trend introduces increasing heterogeneity, which manifests through several fundamentals of wireless signal propagation, ranging from different signal propagation media, diverse operating frequencies to assorted deployment environments. Such heterogeneity leads to critical connectivity challenges – cross-medium link failure, inefficient wideband infrastructure, and coverage blind spots. Conventional solutions of optimizing wireless endpoints are either incapable of solving these challenges or too inefficient for more sustainable next-generation wireless networks.
This dissertation presents an unconventional approach – bridging heterogeneous wireless networks by programming the radio environments with metasurfaces. We present novel metasurface systems as wireless infrastructure to address the emerging challenges of heterogeneous networks efficiently. By controlling wireless signal propagation, our systems create favorable radio environments to address the root causes of connectivity challenges. We develop metasurface hardware designs that provide new signal manipulation capabilities, while ensuring scalability, low power consumption, low complexity, and cost-effectiveness. With efficient surface configuration algorithms tailored to the hardware designs, our systems boost link-layer and network-layer performance using signal-level control primitives.
Following this approach, we explore the design space with three systems. First, to boost cross-medium connectivity, we present RF-Mediator, the first programmable impedance-matching metasurface, which masks the propagation medium interfaces under dynamic environmental changes. Second, we present Scrolls, a frequency-tunable surface that efficiently provides wideband coverage enhancement across multiple colocated networks. Third, we develop AutoMS, the first automated service framework for mmWave coverage in assorted environments by co-optimizing the design and placement of passive metasurfaces. Building on our experience with surface systems, we further propose SurfOS, a vision to manage surfaces and provide diverse services using operating system-like software abstractions.