Ergodic Capacity Analysis of Free-Space Optical Links With Nonzero Boresight Pointing Errors

TL;DR

This paper provides a comprehensive capacity analysis of free-space optical links considering nonzero boresight pointing errors and different detection methods, offering exact moments and capacity approximations verified by simulations.

Contribution

It introduces exact closed-form moments of the SNR for FSO links with pointing errors and derives simple capacity approximations for various SNR regimes.

Findings

Exact moments of SNR derived for FSO links with pointing errors

Closed-form capacity approximations at high and low SNRs

Results validated through Monte-Carlo simulations

Abstract

A unified capacity analysis of a free-space optical (FSO) link that accounts for nonzero boresight pointing errors and both types of detection techniques (i.e. intensity modulation/direct detection as well as heterodyne detection) is addressed in this work. More specifically, an exact closed-form expression for the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system is presented in terms of well-known elementary functions. Capitalizing on these new moments expressions, we present approximate and simple closed-form results for the ergodic capacity at high and low SNR regimes. All the presented results are verified via computer-based Monte-Carlo simulations.