This project presents TIMO, the first WiFi receiver that can decode in the presence of high-power unknown cross-technology interference. Traditionally, researchers have addressed cross-technology interference by dynamically searching for and switching to unused frequencies. We approach the problem from a different perspective: can one operate in already used frequencies in the presence of potentially unknown interferers? We build a new cognitive framework for the unlicensed band which allows multi-antenna devices to work in used frequencies. We show that, in practice, our approach allows WiFi to operate in the presence of potentially unknown interferers such as microwave ovens, baby monitors, and cordless phones. Faculty: Gollakota