Enhancement of tolerance to MAIs by the synergistic effect between M-ary PAM and the chip-level receiver for optical CDMA systems

Takaya Miyazawa, Iwao Sasase

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In this paper, an M-ary pulse-amplitude modulation (PAM) coded optical code division multiple access (CDMA) system applying the chip-level receiver with M-level threshold detection is proposed. First, in order to increase the number of transmitted bits per pulse, the PAM coded system is considered. However, when the correlator is applied in the receiver, the multiple access interferences (MAIs) with high intensities deteriorate the system performance significantly even if the number of MAIs is small. Consequently, the chip-level receiver with M-level threshold detection instead of the correlator in the M-ary PAM-CDMA system is proposed. The proposed system can obtain the synergistic effect between the PAM and the chip-level receiver, in which the chip-level receiver reduces more MAIs compared with the correlator and the PAM has the larger number of transmitted bits per frame than ON-OFF keying (OOK). As a result, the proposed system can increase the code length and the number of weights, and achieves higher tolerance to MAIs than the OOK-CDMA system with the chip-level receiver under the condition in which the chip duration, the bit rate, and the number of subscribers are kept constant. It is shown that the proposed M-ary PAM-CDMA system with the chip-level receiver achieves better bit error probability (BEP) than the OOK-CDMA system with the chip-level receiver.

Original languageEnglish
Pages (from-to)658-666
Number of pages9
JournalJournal of Lightwave Technology
Volume24
Issue number2
DOIs
Publication statusPublished - 2006 Feb 1

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Keywords

  • Chip-level receiver
  • M-ary pulse-amplitude modulation (PAM)
  • Multiple access interference (MAI)
  • Optical code division multiple access (CDMA)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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