The Capacity of Cognitive Ad Hoc Networks

We analyze the capacity of an ad hoc networks when cognitive radio (CR) is deployed for traffic load reduction. This capacity, the per-link capacity, is defined as an average of Shannon capacities achieved by all links in a route. For this purpose, we propose a generalized ad hoc network model which is based on CR in its retransmission. Given the model, our analysis shows that the capacity is Ω(1/N log N)1 according to the number of nodes N, outperforming the conventional ad hoc network of which the capacity is Ω(1/N2. Further, we can also see that there exists an optimal signal-to-interference ratio (SIR) threshold that maximizes the capacity by controlling the average number of nodes served depending on CR in a link.