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Error Performance of Overlapping Multi-Pulse Pulse Position Modulation (OMPPM) and Trellis Coded OMPPM in Optical Direct-Detection Channel
Tomoaki OHTSUKI Iwao SASASE Shinsaku MORI
IEICE TRANSACTIONS on Communications
Publication Date: 1994/09/25
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Optical Communication
MPPM, OMPPM, trellis codes, distance,
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We analyze the error performance of overlapping multipulse pulse position modulation (OMPPM) in optical direct-detection channel with existing noise. Moreover we analyze the error performance of trellis-coded OMPPM with the small overlap index N=2 in optical direct-detection channel to achieve significant coding gains over uncoded PPM, uncoded MPPM and the trellis coded overlapping PPM (OPPM) with the same pulsewidth. First we analyze the symbol error probability of OMPPM in both the quantum-limited case and the quantum and background noise case by using the distance defined as the number of nonoverlapped pulsed chips between symbols. Second by using this distance, we partition the OMPPM signals and apply the four-state and the eight-state codes described by Unger-boeck to OMPPM. It is shown that the trellis coding over OMPPM is effective in optical direct-detection channel: the eight-state trellis coded (4,2,2) OMPPM can achieve gains of 3.92dB and 3.23dB over uncoded binary PPM in the quantum-limited case and in the quantum and background noise case with noise photons per slot time is one, respectively.