A synchronization method deselecting candidate positions with chip level detection for optical CDMA

Ayako Iwata, Koji Kamakura, Iwao Sasase

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1 Citation (Scopus)

Abstract

In order to reduce the number of preamble bits required for synchronization at correct positions, a method of synchronization by deselecting the candidate positions for synchronization is proposed. As decision methods for each preamble bit, a method using the threshold detection and a method using chip level detection are discussed. Both methods make use of the fact that the preamble bit is the bit "1": any synchronization position judged not to be a "1" bit even once is deselected as a candidate. In this way, the only position eventually remaining without being deselected is judged to be the synchronization position. As a result, it is possible to carry out synchronization with fewer preamble bits than the conventional method in which bit decision is based on the logarithmic likelihood ratio of the continuously transmitted preamble bits. A theoretical analysis is made under the assumption that the output of the photodetector follows a Poisson distribution. It is found that the proposed method can perform synchronization within a shorter time than the conventional synchronization method. Further, in the method using chip level detection, it is shown that synchronization is achieved in a shorter time even if the bit decision threshold is fixed.

Original languageEnglish
Pages (from-to)21-32
Number of pages12
JournalElectronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi)
Volume88
Issue number3
DOIs
Publication statusPublished - 2005 Mar 1

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Keywords

  • Chip level detection
  • Optical code division multiple access system
  • Synchronization method
  • Threshold detection

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering

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