Pushing Seamless Wireless Communication With Cross-Band Metasurfaces

In the realm of next-generation wireless communications, sub-6GHz and mmWave frequencies are a powerful combination, offering broad coverage and high capacity. Nevertheless, achieving seamless wireless connections in indoor environments remains a challenge, primarily due to obstructions that significantly impact higher frequency bands such as Wi-Fi 5GHz and mmWave. Bridging this divide requires an innovative approach, and economical tunable metasurfaces emerge as a promising solution. These metasurfaces can redirect incoming wave directions to circumvent obstacles. However, existing metasurface technologies are typically tailored to a single frequency band and lack a theoretical framework for designing surfaces that cater to multiple desired bands, constraining their potential for versatile applications. This work takes on the challenge of providing a comprehensive approach to cross-band metasurface design, with the overarching goal of expanding the reach of wireless network. We introduce a novel metasurface prototype named CrossMeta, engineered to optimize link quality while efficiently utilizing apertures and maintaining cost-effectiveness. We tacked a series of challenges to empower CrossMeta to independently manipulate wireless communication links across multiple frequency bands; our proof of concept implementation is for Wi-Fi 5 GHz and mmWave bands. We integrate a fast beam-scanning algorithm into an end-to-end system that actuates the metasurface to optimize links in real-time. Empirical evaluation demonstrates that CrossMeta can enhance multiple wireless links simultaneously, providing 10 dB and 15 dB power improvements for Wi-Fi and mmWave links, respectively. Impressively, CrossMeta achieves less than 4° beam mismatch even in challenging mobile scenarios.