On estimating the end-to-end bandwidth in multi-transceiver multi-hop cognitive radio networks

Cognitive radios promise to revolutionize the performance of wireless networks in general and multi-hop wireless networks in particular by making efficient use of the portion of the licensed spectrum left un-utilized. Realizing this promise, however, requires revisiting many of the current network architectures and protocols, which is the subject of a very active research effort. In this work, we focus on Quality of Service routing and more specifically, admission control. We consider a multi-hop cognitive radio network where every node is equipped with multiple transceivers. Because the research and development of a widely accepted MAC protocol for these networks is still ongoing, we assume a bare-bones TDMA protocol at the link layer. We show that, for the network considered, the problem of finding the maximum end-to-end bandwidth of a given path is NP-Complete. Given this result, we consider a relaxed version of the problem wherein the slot allocations are carried out at each node by selecting at random the required number of slots among those available. For this case, we provide a linear time algorithm for computing the average residual end-to-end bandwidth. We perform an extensive numerical analysis that demonstrates its accuracy and enabling value for performing admission control.