Analysis of free space optical (FSO) communications and networking using adaptive waveforms for LEO satellites

Abstract

In this paper, we model the use of free space optical (FSO) links that employ adaptive waveforms such as n-PSK in the context of links to and from low earth orbit (LEO) satellite systems. FSO link models are described that can be used to predict dynamic link quality to and from a surface terminal to a LEO terminal. Because the link margin can vary by 10-20 dB in a LEO pass, we consider the use of adaptive waveforms. Higher order waveforms are used when the link margin is high, stepping back down to on-off keying when the margin is low. We also describe the design and development of network emulation and simulation capabilities to help analyze the use of dynamic FSO-LEO link models within existing network experimentation frameworks. We present a network emulation demonstration of the designed FSO-LEO link models involving data transfer between two surface observers and multiple opportunistic LEO satellite events. We discuss both the emerging opportunities and ongoing challenges of effectively using such FSO-LEO capabilities within a larger data network context.