There is a perceived spectrum scarcity issue facing the wireless industry today. Most allocated spectrum is entirely spoken for, which reinforces the myth that we are running out of spectrum for wireless communications. A simple spectral analysis of commercial spectrum bands indicates that there is up to 90% of unused spectrum at any given time or place. Craig Mathias, author of the white paper Rethinking Spectrum Scarcity – Database-Driven Cognitive Radio, says that “We actually have access to vast quantities of spectrum in any given geographic location, and, given natural signal strength fading due to the inverse power law, we can further multiply efficiency via the reuse of spectrum over distance.”
One solution that Craig proposes towards solving the spectrum crisis is that of a database-driven cognitive radio approach. Cognitive radios are radios that are, “capable of transmitting and receiving across channels covering a potentially very wide range of frequencies.” By utilizing a database-driven networking approach, these radios will be the first step towards efficiently utilizing the unused or idle spectrum at any given point in time.
One example of an area where database-driven cognitive radios can be effective is in the TV White Spaces spectrum. The FCC is proposing that devices operating in these unlicensed frequencies will need to be certified against a TV White Spaces database to ensure that there are no interference issues. Deploying a database-driven cognitive radio in a band like this, which spans from 54MHz to 698MHz, provides a dynamic network approach to allocating spectrum.
TV White Spaces are a prime example of how cognitive radios can communicate with a database, thus enabling the radio to determine the appropriate frequency to operate on without any human interaction. In the future, we can foresee cognitive radios operating across multiple frequencies in different bands, helping to alleviate the perceived spectrum scarcity. For more information on Database-Driven Cognitive Radios, click here.
- Joe Hamilla