Energy efficiency in cognitive radio network

Cognitive radio techniques have been introduced to improve the spectrum utilization in the frequency bands already allocated to licensed users. Under spectrum sharing model, secondary users can share spectrum with primary users with the condition that total interference caused by SUs should not be exceeded from a predefined level. Energy efficiency is one of the important metric in cognitive radio networks as it has to work under strict transmit power constraint. In this paper, we explore how better energy efficiency can be achieved in a spectrum sharing environment. Our analysis shows that energy efficiency in cognitive radio network is better when number of secondary users is more than available channels.