Optimal Power Allocation in an "Off" Spectrum Sensing Interval for Cognitive Radio

Most of the current works about cognitive radio favor a constant power allocation policy during an "off" spectrum sensing interval, which is the time between two spectrum sensing activities when the outcome of the first spectrum sensing indicates "off". However, according to our work, this policy becomes suboptimal with respect to bit error rate minimization, when the traffics of primary user follow an alternating renewal process. Therefore, under this scenario, we suggest the optimal power allocation policy, by solving a convex optimization problem on power allocation of secondary user. Our results provide meaningful insight into the design of transmitting schemes for cognitive radio.