Symbol synchronization for optical multi-pulse pulse position modulation systems

The demand for high throughput and power efficient telecommunication systems can never be overstated. In this regard, optical multi-pulse pulse-position-modulation (MPPM) has received greater attention and has been proposed as an alternative to QPPM (4-ary PPM) for applications in high speed optical inter-satellite communications. Realizing the ever growing need for high capacity, our objective is to study symbol synchronization of optical MPPM, derive maximum likelihood synchronization rules, identify suboptimal rules that are easier to implement and evaluate their performance through computer simulations. We show that for high signal-to-noise ratios, perfect symbol synchronization can be achieved asymptotically in the limit of using long sequences of MPPM symbols.