Cognitive Radio: An Information-Theoretic Perspective

TL;DR

This paper analyzes the capacity limits of cognitive radios that adapt their transmission to avoid interfering with primary users, using an information-theoretic approach to characterize optimal communication rates.

Contribution

It provides a novel information-theoretic characterization of the maximum reliable communication rate for cognitive radios with side-information, ensuring no interference to primary users.

Findings

Maximum cognitive radio transmission rate under interference constraints

Conditions for zero interference to primary users

Modeling cognitive radio as a transmitter with side-information

Abstract

Cognitive radios have been proposed as a means to implement efficient reuse of the licensed spectrum. The key feature of a cognitive radio is its ability to recognize the primary (licensed) user and adapt its communication strategy to minimize the interference that it generates. We consider a communication scenario in which the primary and the cognitive user wish to communicate to different receivers, subject to mutual interference. Modeling the cognitive radio as a transmitter with side-information about the primary transmission, we characterize the largest rate at which the cognitive radio can reliably communicate under the constraint that (i) no interference is created for the primary user, and (ii) the primary encoder-decoder pair is oblivious to the presence of the cognitive radio.