Energy-efficient cognitive radio networks [Guest Editorial]

Spectrum efficiency and energy efficiency are two critical issues for wireless communication networks. As a promising paradigm to improve spectrum usage efficiency, much attention has been paid to cognitive radio (CR) in both academia and industry since it was introduced more than 10 years ago. On the other hand, fast growing wireless applications are consuming more and more energy, and pose big challenges to operators in terms of energy footprint. However, few discussions were held on the energy efficiency issue in CR networks (CRNs) until recently. Actually, energy efficiency is of crucial importance for a CR scenario compared to non-CR ones because it not only involves the greenhouse problem and operational expenditure, but is a prerequisite to achieve high utilization of the limited transmission power consumed to support additional signal processing requirements for the CR system, such as spectrum sensing and signal overhead. Optimizing the energy efficiency of CRNs not only reduces the environmental impact, but also cuts deployment costs to enable economical green wireless networks.