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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 24 — Nov. 19, 2012
  • pp: 26786–26797

Performance improvement of FSO/CDMA systems over dispersive turbulence channel using multi-wavelength PPM signaling

Ngoc T. Dang and Anh T. Pham  »View Author Affiliations

Optics Express, Vol. 20, Issue 24, pp. 26786-26797 (2012)

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Previous studies show that, compared to on-off keying (OOK) signaling, pulse-position modulation (PPM) is favorable in FSO/CDMA systems thanks to its energy efficiency and simple detection. Nevertheless, when the system bit rate increases and the transmission distance is far, the FSO/CDMA systems using PPM signaling critically suffer from the impact of pulse broadening caused by dispersion, especially when the modulation level is high. In this paper, we therefore propose to use multi-wavelength PPM (MWPPM) signaling to overcome the limitation of PPM. To further improve the system performance, avalanche photodiode (APD) is also used. The performance of the proposed system is theoretically analyzed using a realistic model of Gaussian pulse propagation. To model the impact of intensity fluctuation caused by the atmospheric turbulence, the log-normal channel is used. We find that, by using MWPPM, the effects of both intensity fluctuation and pulse broadening are mitigated, the BER is therefore significantly improved. Additionally, we quantitatively show that the system performance is further improved by using APD, especially when the average APD gain is chosen properly.

© 2012 OSA

OCIS Codes
(060.4510) Fiber optics and optical communications : Optical communications
(060.2605) Fiber optics and optical communications : Free-space optical communication

ToC Category:
Fiber Optics and Optical Communications

Original Manuscript: August 21, 2012
Revised Manuscript: November 5, 2012
Manuscript Accepted: November 6, 2012
Published: November 13, 2012

Ngoc T. Dang and Anh T. Pham, "Performance improvement of FSO/CDMA systems over dispersive turbulence channel using multi-wavelength PPM signaling," Opt. Express 20, 26786-26797 (2012)

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