This presentation discusses cooperative sensing in cognitive radios. It defines cognitive radio and explains that cognitive radios use techniques like spectrum sensing and learning to access licensed spectrum when it is not in use. The document discusses different types of spectrum including licensed and unlicensed bands. It then covers the key aspects of cooperative sensing including centralized, distributed, and relay-assisted sensing approaches as well as issues like probability of detection, false alarms, and accurate detection. The elements and benefits of cognitive radio are also summarized.