On the Statistics of Cognitive Radio Capacity in Shadowing and Fast Fading Environments

TL;DR

This paper analyzes the capacity of cognitive radio channels in fading environments, deriving an accurate approximation for a key power loss parameter and examining how environmental factors influence system performance.

Contribution

It introduces a simple, accurate approximation for the power loss parameter $oldsymbol{ extalpha}$, providing new insights into cognitive radio capacity in fading conditions.

Findings

The approximation for $oldsymbol{ extalpha}$ is highly accurate across scenarios.

The probability of the low interference regime is high in practical deployments.

Environmental factors significantly impact cognitive radio capacity.

Abstract

In this paper we consider the capacity of the cognitive radio channel in a fading environment under a "low interference regime". This capacity depends critically on a power loss parameter, $\alpha$, which governs how much transmit power the cognitive radio dedicates to relaying the primary message. We derive a simple, accurate approximation to $\alpha$ which gives considerable insight into system capacity. We also investigate the effects of system parameters and propagation environment on $\alpha$ and the cognitive radio capacity. In all cases, the use of the approximation is shown to be extremely accurate. Finally, we derive the probability that the "low interference regime" holds and demonstrate that this is the dominant case, especially in practical cognitive radio deployment scenarios.