Network Coding for Cognitive Radio Networks
Alfred Asterjadhi · Padua Research Archive (University of Padova) · 2011
Cognitive Radio Networks are a promising technology likely to be deployed in the very near future as a viable solution to the spectrum shortage problems faced by traditional wireless systems. Technological breakthroughs in the field of Software Defined Radios enabled the development of flexible cognitive radio transceivers capable of dynamically changing their transmission parameters in order to efficiently exploit the available wireless resources. This increased capability of cognitive radios to self adapt based on interactions with the surrounding environment makes them the perfect candidates for opportunistic spectrum access in those bands that are assigned to primary users. While these primary users are allowed to access their licensed spectrum resources anytime and anywhere, within the contractual limits imposed by spectrum management authorities, cognitive radios have to scan and identify any unused spectrum in the licensed bands. Most importantly, in order not to interfere with primary users, they have to rapidly vacate the licensed spectrum as soon as the primary user begins to use its legitimate spectrum resources. The coexistence of cognitive radios with such primary users is very challenging. When considering the natural evolution of cognitive radio networks to more complex systems, the challenges and problems to be faced increase substantially. More specifically, the inherent capability of cognitive radios to base their decisions on their view of the wireless spectrum makes their operation susceptible to a variety of malicious attacks. Hence, in such a challenging environment, mechanisms such as cooperation, learning, and negotiation help cognitive radios make the necessary decisions to ensure reliable communications in a non-interfering manner. We hereby investigate a novel architectural solution for Cognitive Radio Networks that uses network coding for fast control information exchange among cognitive radios, enabling them to maintain coherent and reliable information regarding the status of the wireless environment. This control information is used by cognitive radios to perform cooperative detection of primary users and efficient reuse of the available spectrum resources while guaranteeing robust communication and a prompt reaction to wireless environmental changes.