Joint maximum likelihood symbol and slot synchronization for optical OPPM channels

A jointly optimum slot and symbol clock recovery scheme for a direct-detection optical communication system with overlapping pulse position modulation (OPPM) is proposed. To arrive at the suggested optimum synchronizer, the maximum likelihood (ML) estimation technique is used when the observed process is a Poisson point process (i.e., shot noise limited receiver). Two suboptimal synchronizer models computationally superior to the ML model are also proposed