Date Added: Oct 2010
Presently there is a scarcity of wireless spectrum worldwide due to an increase in wireless services. Cognitive Radios are proposed as a solution to this problem. They access the spectrum licensed to existing communication services (primary users) opportunistically and dynamically without causing much interference to the primary users. This is made possible via spectrum sensing by the Cognitive Radios (secondary users), to gain knowledge about the spectrum usage by the primary devices. However due to the strict spectrum sensing requirements and the various wireless channel impairments spectrum sensing has become the main challenge faced by the Cognitive Radios.