WATCH: Enabling WiFi in Active TV Channels
Knightly, Edward W.
Master of Science
"White space” model allows TV channels that are not being used regionally by a TV broadcaster to be re-purposed for secondary access. Unfortunately, populated areas have few these unused channels. Nonetheless, Nielsen data show severe under-utilization with vast regions in range of TV transmitters having no active TV receivers even at peak TV viewing time. In this thesis, I present the design, implementation, and evaluation of WATCH (WiFi in Active TV CHannels), the first system to (i) enable secondary WiFi transmission in the presence of kilowatt-scale TV transmitters by employing WATCH-IC (Interference Cancellation) and CAT (Constructive Addition Transmission); (ii) protect active TV receivers by employing their spatial-spectral requirements. With FCC permission to test WATCH implementation, I show that WATCH can provide at least 6.0 times the total achievable rate to 4 watt secondary devices compared to white space model, while increasing the TV channel switching time by less than 5%.