Analyzing the Performance of Spectrum Sensing in Cognitive Radio Systems With Dynamic PU Activity

In this letter, we study the performance of the energy detector for opportunistic spectrum access (OSA) by a secondary user (SU) in dynamic scenarios, where a primary user (PU) switches from active to inactive at random time instances. Specifically, we model the PU activity using a two-state Markov chain and derive analytical expressions for the probabilities of detection and false alarm that explicitly consider the changes in the PU signal that may occur during the sensing interval by the SU. The expressions obtained are corroborated with numerical results obtained from simulations.