Backhaul Communication for High-Altitude Platform Networks: Results of STROPEX, the Stratospheric Optical Payload Experiment

Abstract

A high bitrate optical downlink was performed from a stratospheric balloon. The objectives of the stratospheric optical payload experiment (STROPEX), a part of the EU project CAPANINA, were to plan and build the necessary hardware to demonstrate and carry out channel measurements on an optical backhaul downlink from a stratospheric platform test bed to the ground. During the stratospheric campaign at ESRANGE, near Kiruna, Sweden, all these objectives were achieved. The transportable optical ground station received a nearly error free 1.25 Gbit/s data signal from the stratosphere. The distance was 64.1 km and the bit error rate better than 10-9. This paper gives an overview of the optical terminal, the successful trial, and scientific results. First, the developed optical terminal with precise autonomous acquisition abilities is explained. Next, the experiment, trial realization, and boundary conditions are outlined. Finally, the principles of operation of the turbulence instruments, which monitored the characteristic atmospheric parameters during data transmission, are explained and measurement data are presented.