Free-space optical communication through a forest canopy

Abstract

We model the effects of the leaves of mature broadleaf (deciduous) trees on air-to-ground free-space optical communication systems operating through the leaf canopy. The concept of leaf area index (LAI) is reviewed and related to a probabilistic model of foliage consisting of obscuring leaves randomly distributed throughout a treetop layer. Individual leaves are opaque. The expected fractional unobscured area statistic is derived as well as the variance around the expected value. Monte Carlo simulation results confirm the predictions of this probabilistic model. To verify the predictions of the statistical model experimentally, a passive optical technique has been used to make measurements of observed sky illumination in a mature broadleaf environment. The results of the measurements, as a function of zenith angle, provide strong evidence for the applicability of the model, and a single parameter fit to the data reinforces a natural connection to LAI. Specific simulations of signal-to-noise ratio degradation as a function of zenith angle in a specific ground-to-unmanned aerial vehicle communication situation have demonstrated the effect of obscuration on performance.

A novel receiving system based on optical taper applied to wireless optical communication

“…By using optical design software [11][12] , the receiving system with the optical taper was modeled. In order to investigate the energy distribution on the end of the optical taper, we increase the FOV from 0° to 0.5° and observe the energy and the angle distribution of the light out of the taper by tracing light with a number of 10000.…”

Beam reception and data transmission performance analysis of optical taper used in a mobile wireless optical communication

“…Wireless optical communication has been developed many years and has lots of advantages [1][2][3][4][5], such as high bandwidth, fast setup, high data rate, license free and no cables required to be laid into the ground, etc. So it is considered to be an attractive option for the rapid provisioning of multi-gigabit data per second links.…”