Hybrid Modelling, Power Management and Stabilization of Cognitive Radio Networks

In this paper, we deal with hybrid modelling, optimal control and stability in cognitive radio networks. Networks that are based on cognitive radio communications are intelligent wireless communication systems. They are conscious about changes in the environment and are able to react in order to achieve an optimal utilization of the radio resources. We provide a general hybrid model of a network of nodes operating under the cognitive radio paradigm. The model abstracts from the physical transmission parameters of the network and focuses on the operation of the control module. The control problem consists in minimizing the consumption of the network, in terms of average transmitted power or total energy spent by the whole network. A hybrid optimal control problem is solved and the power-optimal control law is computed. We introduce the notion of network configuration stability and derive a control law achieving the best compromise between stability and optimal power consumption. Finally, we apply our results to the case of a cognitive network based on UWB technology.