On the Statistics of Cognitive Radio Capacity in Shadowing and Fast Fading Environments (Journal Version)

TL;DR

This paper analyzes the capacity of cognitive radio channels in shadowing and fast fading environments, deriving probability models and approximations for key parameters that influence system performance.

Contribution

It introduces a simple, accurate approximation for the power loss parameter in fading environments, enhancing understanding of cognitive radio capacity under various conditions.

Findings

Low interference regime is dominant in practical scenarios.

The approximation for $\alpha$ is highly accurate across environments.

System parameters significantly affect cognitive radio capacity.

Abstract

In this paper we consider the capacity of the cognitive radio channel in different fading environments under a low interference regime. First we derive the probability that the low interference regime holds under shadow fading as well as Rayleigh and Rician fast fading conditions. We demonstrate that this is the dominant case, especially in practical cognitive radio deployment scenarios. The capacity of the cognitive radio channel 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 $\alpha$ in Rayleigh and Rician fading environments 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.