Angle-of-Arrival Estimation of Narrow Gaussian Beams for Mobile FSO Platforms

TL;DR

This paper investigates how to improve angle-of-arrival estimation for narrow Gaussian laser beams in mobile free-space optical systems by utilizing both the spot location and energy on the focal plane, leading to enhanced accuracy.

Contribution

The study introduces a novel receiver design that exploits both the location and energy of the laser spot to improve angle-of-arrival estimation accuracy for narrow Gaussian beams.

Findings

Significant performance improvement when using both spot location and energy.

Derived Cramer-Rao bounds show enhanced system performance.

Analysis confirms the importance of energy information for narrow beams.

Abstract

Due to the narrow beamwidths of laser Gaussian beams, accurate tracking of laser beam's angle-of-arrival is an important problem in mobile free-space optical communications. In most optical receivers today, fine tracking of angle-of-arrival involves estimating the location of the focused beam spot projected onto a focal plane array. However, for very thin Gaussian beams, both the location as well as the energy of the spot varies considerably with the variation of angle-of-arrival. In this study, we have analyzed the relationship between the angle-of-arrival and the energy of laser spot on the focal plane. We then exploited this relationship to enhance the angle-of-arrival estimation performance of our proposed receiver that takes into account both the location as well as the energy of the laser spot while estimating the angle-of-arrival. The derived Cramer-Rao bounds indicate that the system performance can be enhanced significantly for narrow Gaussian beams when both the spot location and energy are exploited for angle-of-arrival estimation.