Towards Seamless Wireless Link Connection.

Sub-6GHz and mmWave complement each other in the next generation of wireless communications for wide coverage and high capacity. However, there is still a gap between current network technology and seamless connection in indoor environments due to the inevitable occlusions that particularly affect higher frequency bands like Wi-Fi 5GHz and mmWave. To overcome this gap, economical tunable metasurfaces offer a promising solution by redirecting the beam direction of incoming waves to bypass blockages. However, existing metasurface technologies focus on a single frequency band and lack a theoretical framework to guide surface design for multiple desired bands, limiting their potential for diverse applications. This work attempts to provide a general method for cross-band metasurface design, extend wireless link coverage by using a new metasurface prototype called CrossFlit, which can maximize the link quality with efficient aperture usage and low cost. We addressed a series of challenges to enable CrossFlit to independently control the 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 realtime. Empirical evaluation demonstrates that CrossFlit can enhance multiple wireless links simultaneously, providing 10 dB and 15 dB power improvements for Wi-Fi and mmWave links, respectively. CrossFlit achieves less than 4° beam mismatch even in challenging mobile scenarios.