PERFORMANCE ANALYSIS OF PULSE POSITION MODULATION SYSTEMS WITH CODING SCHEMES FOR DEEP SPACE OPTICAL CHANNEL

Abstract

The deep space optical communication system involves communication without the optical fiber, i.e. it is an unguided communication system for free space. Since it offers high capacity links for inter-satellite, inter-orbital or deep space mission communication applications, it has been the subject of a lot of significant research. This system typically employs the intensity modulation/ direct detection scheme. Deep space communication channels are characterized by very low SNRs and practically no bandwidth limitations. Since the deep space optical channel is not bandwidth-constrained but is power constrained due to the large distances involved, pulse position modulation is preferred choice of modulation scheme in spite of its large bandwidth requirement, as it is very power efficient. In this thesis, four variants of the PPM scheme have been explored, viz., simple PPM, Amplitude PPM, Overlapping PPM and multi-pulse PPM. Performance evaluations have been carried out for these PPM sy...