Green sensing and access: energy-throughput trade-offs in cognitive networking

Limited spectrum resources and the dramatic growth of high data rate applications have motivated opportunistic spectrum access exploiting the promising concept of cognitive networks. Although this concept has emerged primarily to enhance spectrum utilization and to allow the coexistence of heterogeneous network technologies, the importance of energy consumption imposes additional challenges, because energy consumption and communication performance can be at odds. In this article the approaches for energy efficient spectrum sensing and spectrum handoff, fundamental building blocks of cognitive networks, are investigated. The trade-offs between energy consumption and throughput, under local as well as under cooperative sensing, are characterized. We also discuss the additional factors that need to be investigated to achieve energy efficient cognitive operation under various application requirements.