Percolation on the Information-Theoretically Secure Signal to Interference Ratio Graph

Abstract: We consider a continuum percolation model consisting of two types of nodes, namely legitimate and eavesdropper nodes, distributed according to independent Poisson point processes (PPPs) in $\bbR ^2$ of intensities $\lambda$ and $\lambda_E$ respectively. A directed edge from one legitimate node $A$ to another legitimate node $B$ exists provided the strength of the {\it signal} transmitted from node $A$ that is received at node $B$ is higher than that received at any eavesdropper node. The strength of the received signal at a node from a legitimate node depends not only on the distance between these nodes, but also on the location of the other legitimate nodes and an interference suppression parameter $\gamma$. The graph is said to percolate when there exists an infinite connected component. We show that for any finite intensity $\lambda_E$ of eavesdropper nodes, there exists a critical intensity $\lambda_c < \infty$ such that for all $\lambda > \lambda_c$ the graph percolates for sufficiently small values of the interference parameter. Furthermore, for the sub-critical regime, we show that there exists a $\lambda_0$ such that for all $\lambda < \lambda_0 \leq \lambda_c$ a suitable graph defined over eavesdropper node connections percolates that precludes percolation in the graphs formed by the legitimate nodes.