LAUSR

For a CR system operating under the energy detection scheme of spectrum sensing, it is much important to have low values of probability of false alarm $$P_{fa}$$Pfa and probability of missed detection $$P_{md}$$Pmd. However, due to inherent tradeoff between $$P_{fa}$$Pfa and $$P_{md}$$Pmd, it is challenging to simultaneously achieve high value of throughput while maintaining a sufficient level of protection to the licensed users. To overcome this challenge, this paper proposes a CR system which while operating under the double threshold scheme does not only promise a high value of throughput but it also ensures a target level of protection to the licensed users. We further study the problem of designing a sensing duration to maximize the achievable throughput for the secondary network under the constraint that the primary users are sufficiently protected. We formulate the sensing-throughput tradeoff problem mathematically, and prove that the formulated problem indeed has one optimal sensing time which yields the highest throughput for the secondary network. To overcome uncertainties of the wireless communication channel, the proposed approach was further been implemented under the cooperation of $$n - out - of - k$$n-out-of-k CRs. It is observed that, under the proposed approach, the CR user while ensuring a target level of protection to the licensed users achieves a significant gain in throughput than the CR systems based on the single and double thresholds both.