An optimal adaptive transmitting and waiting durations based on detected energy values in cognitive radio networks

In cognitive radio networks, to take advantage of idle spectrum of a primary user opportunistically, a cognitive radio user should detect the licensed channel frame-by-frame. In this paper, the cognitive radio user performs spectrum sensing firstly in each frame. If the primary user is found to be absent/ present, the cognitive radio user will transmit/wait for a while accordingly. We optimize a different transmitting/waiting duration when a detected energy value is within a different interval. Then an adaptive transmitting/waiting duration varying with the detected energy value is formulated. Numerical results show that our scheme has a better performance compared with the conventional scheme.