Although most of the spectrum is allocated much of it is unused. The enormous growth in the wireless industry has come from using a small part of the wireless spectrum, nominally less than 10% under 3 GHz. There is growing evidence of scarcity and overcrowding in these bands reflected for example, by price paid for cellular spectrum. However, measurements have shown other parts of the spectrum -- although allocated -- are virtually unused, and known widely as spectrum white spaces. These white spaces vary from place to place and time to time. Cognitive Radio (CR) technologies enable harnessing these spectrum white spaces, permitted by new spectrum regulation. Specifically, spectrum regulation to allow the unlicensed use of television bands is well underway in the US.

The breakthrough provided by Cognitive Radios is significant because it allows the development of new and innovative types of devices and services for businesses and consumers, without disrupting television and other authorized services. Key benefits include: (a) access to abundant new spectrum, (b) better propagation therefore reliable, low outage communication and low power operation, and (c) peaceful coexistence with other wireless networks. Cognitive Radio topic has featured in MIT Technology Review's top ten most promising emerging technologies. Accordingly, during the last few years, there has been a lot of effort by the FCC, industry and standard groups to make CRs happen. There has also been significant research effort in academia for better understanding of the technical requirements and potential solutions.

In this presentation, we will discuss the status of spectrum regulation in allow unlicensed use of television bands, and technical challenges and solutions to realize the potential of Cognitive Radios.

Kiran Challapali is a Project Leader and Principal Member at Philips Research North America. He leads the Cognitive Radio research at Philips. His team was recently awarded Frost and Sullivan Excellence in Research Award for Cognitive Networks for 2007. He has published over twenty five technical papers in IEEE Journals and Conferences. He is the recipient of the Chester Sall Award for the Best Transactions Paper (second place) from the IEEE Consumer Electronics Society for a paper published in 1992. He has about twenty-five patents, issued or pending, and is a Member of the IEEE.