Optimal sensing duration based on primary feedback in energy limited cognitive networks

We consider a secondary node with fixed energy budget per frame aiming at exploiting the time intervals of primary inactivity. Although a long sensing duration leads to better primary protection, it reduces the time and energy left for the secondary transmission. We seek to exploit the knowledge of the cross channel state information (CCSI) between the secondary transmitter and the primary receiver in order to minimize the required sensing duration, thereby increasing the secondary time and energy for transmission leading to an increase in his throughput. The optimal sensing duration is derived and the benefit of exploiting the cross channel state information is substantiated.