Maximum-likelihood symbol synchronization and detection of OPPM sequences

摘要

For an optical Poisson channel, we consider the problem of symbol synchronization and detection of chip-synchronized, random overlapping pulse-position modulation (OPPM) sequences. Maximum-likelihood algorithms are derived for both synchronization and detection and for soft and hard data, and their performances are evaluated through simulations and an upper bound on the symbol detection and symbol synchronization probabilities. As for the case of pulse-position modulation previously studied, it is seen that a performance ceiling exists when only chip synchronization is present, which can be removed through the periodic insertion of synchronizable symbols in the random data stream.