Adaptive congestion control for mobility in cognitive radio networks

Communication requirements for the cognitive radio networks need novel solutions, to overcome the limitations of dynamic spectrum access. In this regard, the Channel Assigning Agent (CAA) was introduced at the mobile Internet Protocol (IP) layer to allow cognitive mobile users to use their channel as long as possible, to avoid any increase in interruption loss due to unnecessary channel adaptations. This prior forecasting for the mobile transition actions helps to improve traffic planning and minimize the spectral congestion resulting from mobility. In this paper, the Transport-layer (TCP) performance is examined with the CAA application, to evaluate the TCP/IP interface effects and to analyse the performance on congestion control and capacity utilisation. Results show that CAA deployment increases the reliability of connections, with less aborted calls and more guaranteed load throughputs. Congestion control is performed at the network end by systems with an intermediate CRoF core that intelligently direct traffic according to the available spectrum holes. The proposed model has been very successful, producing a highly stable and scalable network.