Multiuser Cognitive Radio Networks: An Information Theoretic Perspective

TL;DR

This paper derives achievable rate regions and outer bounds for three-user interference channels with unidirectional message sharing, analyzing different sharing schemes and their impact on interference management through theoretical and simulation results.

Contribution

It introduces three new message-sharing schemes for three-user cognitive interference channels and derives their achievable rate regions using advanced coding techniques.

Findings

Different message-sharing schemes significantly affect achievable rates.

Rate-splitting strategies improve interference management.

Simulation results compare rate regions and outer bounds for Gaussian channels.

Abstract

Achievable rate regions and outer bounds are derived for three-user interference channels where the transmitters cooperate in a unidirectional manner via a noncausal message-sharing mechanism. The three-user channel facilitates different ways of message-sharing between the primary and secondary (or cognitive) transmitters. Three natural extensions of unidirectional message-sharing from two users to three users are introduced: (i) Cumulative message sharing; (ii) primary-only message sharing; and (iii) cognitive-only message sharing. To emphasize the notion of interference management, channels are classified based on different rate-splitting strategies at the transmitters. Standard techniques, superposition coding and Gel'fand-Pinsker's binning principle, are employed to derive an achievable rate region for each of the cognitive interference channels. Simulation results for the Gaussian channel case are presented; they enable visual comparison of the achievable rate regions for different message-sharing schemes along with the outer bounds. These results also provide useful insights into the effect of rate-splitting at the transmitters, which aids in better interference management at the receivers.