This book contains the spectrum sensing issue in cognitive radio. In order to utilize the spectrum efficiently, the role of spectrum sensing is essential in cognitive radio networks. The transmitter detection based techniques, energy detection, cyclostationary feature detection, and matched filter detections are most commonly used for the spectrum sensing. However, detection performance in practice is often compromised with multipath fading, shadowing and receiver uncertainty issues. To mitigate the impact of these issues, cooperative spectrum sensing has been shown to be an effective method...