Date Added: Aug 2010
Recently the radio spectrum is becoming exhausted because of the growing demands for the radio spectrum. In this regard, the paradigm shifts from the conventional exclusive use of frequency resources by the fixed allocation to the dynamic frequency utilization is indispensable for the future wireless networks. Cognitive Radio (CR) can greatly improve spectrum efficiency through allowing unlicensed users to dynamically access the unused primary spectrum while bringing no harm to the primary users. Spectrum sensing, as a key enabling functionality in Cognitive Radio Networks (CRN), needs to reliably detect signals from licensed primary radios to avoid harmful interference. Generally speaking, spectrum sensing techniques fall into three categories: energy detection, coherent detection and cyclostationary feature detection.