On the fundamental limit to the use of cognitive radio in underwater acoustic sensor networks

Abstract

Cognitive communication is an effective solution to the spectrum scarcity issues in wireless networks. The underwater sensor networks are prone to large propagation delays which result in the fundamental limitation on introducing cognitive aspects in underwater scenario. This letter explores the fundamental limitation of using cognitive communication in large propagation delay underwater networks. This work proposes a method to find the optimal position of the secondary user, to minimize the interference to primary users, in an underwater cognitive acoustic network. The proposed method also considers the effect of channel randomness which is modeled using the log-normal shadowing model. The method can also be used to select and schedule the secondary user transmissions, from a set of secondary users, such that the interruption time to the primary users is minimized.