Dynamic Spectrum Access: The Capacity Trade-off

Since 2000, cognitive radio has slowly been moving from theory into reality. One major driving force for that is tangible commercial applications for cognitive radio, the most major of which is dynamic spectrum access (DSA). A wide variety of DSA techniques have been proposed, in an effort to take advantage of every ounce of unused spectrum. This paper analyzes the three main approaches: frequency coexistence, time coexistence, and interference coexistence. An ideal radio would employ all three to fully exercise all the available spectrum, however each in many scenarios it’s often not worthwhile to do much more than basic dynamic frequency selection. We analyze the different scenarios and provide guidance on when different approaches are practical.