Can Cognitive Radio Operating in the TV White Spaces Completely Protect Licensed TV Broadcasting?
Policy Paper
Jan. 30, 2007
This study and report were produced with funding from Microsoft Corporation.
Policy Background
In 2004, the FCC proposed to allow unlicensed wireless devices to utilize vacant television channel frequencies in each market, a rulemaking that is currently in its final stages. The FCC discussed three methods (control signals, position determination, and cognitive radio with dynamic frequency selection) to ensure that unlicensed TV band devices operate only on vacant channels without harmful interference to broadcast TV service. Of these methods, cognitive radio has spurred the most debate. The cognitive radio method uses spectrum sensing and dynamic frequency selection (DFS) to identify and avoid occupied TV channels. This method has been approved by the Defense Department for unlicensed devices to share spectrum with military radar in the upper 5 GHz band. Potential service providers and equipment manufacturers embrace it because it does not require external infrastructure. However, TV broadcasters oppose it because they do not understand it and fear it will result in harmful interference. This report answers the following question that is central to the FCC’s current rulemaking: can unlicensed TV band devices using cognitive radio techniques completely protect licensed broadcast TV services?