Performance enhancement of LEO-to-ground FSO systems using All-optical HAP-based relaying

Abstract

In this paper, we propose to use all-optical high altitude platform (HAP)-based relaying technique to improve the performance of the free-space optical communication (FSO) system from a low-earth orbit (LEO) satellite to the ground station. Two all-optical relaying techniques are applied to HAP-based relay node including optical amplify-and-forward (OAF) and optical detect-amplify-and-forward (ODAF). A closed-form expression for bit error rate (BER) of the proposed relay-assisted LEO-to-ground FSO system under the effects of free space loss, path loss, and atmospheric turbulence is derived. We also carry out Monte-Carlo (M-C) simulation to verify the theoretical results in terms of BER and the quality of image transmission. The numerical results show that 28 dB power gain at BER of 10−9 can be achieved thanks to the use of HAP-based relaying. Also, lower BER that results in better quality of restored images at the ground station is demonstrated in this paper.