Considerations for Successful Cognitive Radio Systems in US TV White Space

On February 17, 2009, the United States will complete the transition to digital television. The FCC is in the process of establishing rules to allow unlicensed secondary use of the TV "white space" that this transition creates. This television white space (TVWS) opens vital new portions of limited radio spectrum and enables delivery of new communication services, particularly wireless broadband, to millions of underserved Americans. In some rural markets, up to 250 MHz of spectrum could be utilized. Expected initial system deployments in TVWS include wireless Internet service providers (WISPs) and broadband coverage systems for business enterprises. It is critical that these early services are successful, both technically in protecting incumbent licensed users as well as financially in being commercially viable. Cognitive radio technologies are available that enable radio systems operating in the TVWS spectrum to reliably protect the incumbent licensed users. These technologies include geolocation, augmented by sensing, and beaconing. Existing protocols, such as WiMax, WiFi, and proprietary protocols, rebanded to the UHF frequency ranges, will provide broadband data throughput at adequate ranges to allow practical services. It is important to develop and deploy early viable solutions into this band that protect incumbent licensed users so that cycles of learning can start. Lessons from these early systems will allow the industry to accept more aggressive cognitive radio technologies and services, will offer greater comfort to critics of the technology, and will provide regulatory agencies worldwide with data for future rulemaking.