MAXIMUM-LIKELIHOOD SYMBOL SYNCHRONIZATION AND DETECTION OF OPPM SEQUENCES

For an optical Poisson channel, we consider the problem of symbol sync hronization and detection of chip-synchronized, random overlapping pul se-position modulation (OPPM) sequences. Maximum-likelihood algorithms are derived for both synchronization and detection and for soft and h ard data, and their performances are evaluated through simulations and an upper bound on the symbol detection and symbol synchronization pro babilities. As for the case of pulse-position modulation previously st udied, it is seen that a performance ceiling exists when only chip syn chronization is present, which can be removed through the periodic ins ertion of synchronizable symbols in the random data stream.