SNR Wall for Energy Detection with Noise Power Estimation
Since the very early literature on Cognitive Radio (CR), spectrum sensing has been identified as the enabling function for opportunistic spectrum access. A survey of spectrum sensing methodologies for CR is presented in. Remarkable spectrum sensing performance can be reached with feature detectors, that exploit some known characteristic of the Primary User (PU) signals at the expense of a long observation time. ED instead is the optimum detector when the primary signal is completely unknown and no feature detection is therefore possible. Although the receiver has some knowledge of the signal to be detected, ED may be chosen for the simplicity of its implementation.