Research Article Open Access

Turbo-coding of Coherence Multiplexed Optical PPM CDMA System With Balanced Detection

K. Chitra1 and V.C. Ravichandran1
  • 1 ,
American Journal of Applied Sciences
Volume 4 No. 5, 2007, 264-268

DOI: https://doi.org/10.3844/ajassp.2007.264.268

Submitted On: 29 November 2006 Published On: 31 May 2007

How to Cite: Chitra, K. & Ravichandran, V. (2007). Turbo-coding of Coherence Multiplexed Optical PPM CDMA System With Balanced Detection . American Journal of Applied Sciences, 4(5), 264-268. https://doi.org/10.3844/ajassp.2007.264.268

Abstract

The effects of turbo-coding on the coherence multiplexed optical PPM CDMA systems are shown by evaluating bit error rate (BER) with respect to system parameters such as interleaver length (K), number of simultaneous users (N), code length (f), initial pulsewidth (t0) and normalized threshold (θ) by including the effects of thermal noise and shot noise. Turbo-codes increase the number of simultaneous users besides reducing the BER for a decreasing normalized threshold. As the initial pulsewidth reduces from 7ps to 5ps the BER reduces from 1.6392x10-17 to 7.0167x10-18. For a fixed number of simultaneous users (N=20), an initial pulsewidth, (t0 = 5ps) and a normalized threshold (θ = 0.84), it is seen that the turbo-codes of interleaver length 10 reduces BER in the order 10-10, 10-18 and 10-32 for the code length varying as 63, 127 and 255 respectively. On comparison with the direct detection it is found that the balanced detection could accommodate an additional number of 8 users at a reduced BER of 10-16.

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Keywords

  • Coherence multiplexing
  • CDMA networks
  • turbo-coded PPM
  • balanced detection