Secure Outage Analysis of FSO Communications Over Arbitrarily Correlated M\'alaga Turbulence Channels

TL;DR

This paper investigates the impact of correlation between main and eavesdropper FSO links modeled by M"alaga turbulence, revealing non-monotonic effects on secrecy outage performance with increasing correlation.

Contribution

It provides exact and asymptotic expressions for secrecy metrics in correlated M"alaga turbulence channels, offering new insights into channel correlation effects.

Findings

Secrecy outage probability exhibits non-monotonic behavior with correlation.

Increased correlation initially worsens SOP, then improves it beyond a threshold.

Correlation significantly influences FSO secrecy performance.

Abstract

In this paper, we analyze the secrecy outage performance for more realistic eavesdropping scenario of free-space optical (FSO) communications, where the main and wiretap links are correlated. The FSO fading channels are modeled by the well-known M\'alaga distribution. Exact expressions for the secrecy performance metrics such as secrecy outage probability (SOP) and probability of the non zero secrecy capacity (PNZSC) are derived, and asymptotic analysis on the SOP is also conducted. The obtained results reveal useful insights on the effect of channel correlation on FSO communications. Counterintuitively, it is found that the secrecy outage performance demonstrates a non-monotonic behavior with the increase of correlation. More specifically, there is an SNR penalty for achieving a target SOP as the correlation increases within some range. However, when the correlation is further increased beyond some threshold, the SOP performance improves significantly.