Some optimal and suboptimal receivers deriving information from nonsynchronized Poisson data

The author derives receivers that make optimal sequence decisions from observations of modulated data in the absence of symbol synchronization for the direct-detection optical channel. He shows that, for soft-decision sequence estimation, the average number of likelihoods that must be evaluated need increase only linearly with the sequence length, with the average number of likelihood evaluations actually needed being smaller than the sequence length. Finally, the author presents computer simulations that compare the performance of two of the receivers to the performance of a receiver utilizing a separate synchronizer and to that of a receiver that is perfectly synchronized.

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