This book discusses the performance study of different types of energy detection schemes used in Cognitive Radio. In this book, the conventional single threshold based spectrum sensing algorithm has been simulated and its performance in terms of probability of detection has been proved to be lower than that of the double threshold based algorithm, at low SNR conditions. The performance of double-threshold energy detection has also been also compared in this book based on two parameters: probability of collision and the probability of spectrum unavailability.Lecturer at Pokhara University.ME in Communication Engineering from Kathmandu University