OSA's Digital Library

Applied Optics

Applied Optics


  • Vol. 44, Iss. 20 — Jul. 10, 2005
  • pp: 4368–4374

Effect of encoder–decoder mismatch due to wavelength and time misalignments on the performance of two-dimensional wavelength–time optical code-division multiple access systems

Rhys Adams and Lawrence R. Chen  »View Author Affiliations

Applied Optics, Vol. 44, Issue 20, pp. 4368-4374 (2005)

View Full Text Article

Enhanced HTML    Acrobat PDF (194 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



We examine the effects of encoder and decoder mismatch due to wavelength and time chip misalignments on the bit-error rate (BER) performance of two-dimensional (2D) wavelength–time optical code-division multiple access systems. We investigate several instances of misalignment in the desired user encoder and decoder as well as in the interfering user encoders. Our simulation methodology can be used to analyze any type of 2D wavelength–time code family as well as probability distribution for misalignment. For illustration purposes, we consider codes generated by use of the depth-first search algorithm and a Gaussian distribution for the misalignment. Our simulation results show that, in the case of a misalignment in either wavelength or time chip, the variance of the distribution for the misalignment must be below 0.01 for the corresponding degradation in the BER system’s performance to be less than 1 order of magnitude compared with that when there is no mismatch between the encoders and decoders. The tolerances become even more strict when misalignments in both wavelength and time chips are considered. Furthermore, our results show that the effect of misalignment in wavelength (time chips) is the same regardless of the number of wavelengths (time chips) used in the codes.

© 2005 Optical Society of America

OCIS Codes
(060.2330) Fiber optics and optical communications : Fiber optics communications
(060.4510) Fiber optics and optical communications : Optical communications

Original Manuscript: November 18, 2004
Revised Manuscript: February 8, 2005
Manuscript Accepted: February 14, 2005
Published: July 10, 2005

Rhys Adams and Lawrence R. Chen, "Effect of encoder–decoder mismatch due to wavelength and time misalignments on the performance of two-dimensional wavelength–time optical code-division multiple access systems," Appl. Opt. 44, 4368-4374 (2005)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. A. Stok, E. H. Sargent, “Lighting the local area: optical code-division multiple access and quality of service provisioning,” IEEE Network 14(6), 42–46 (2000). [CrossRef]
  2. J. Shah, “Optical CDMA,” Opt. Photon. News 14(4), 42–47 (2003). [CrossRef]
  3. P. R. Prucnal, M. A. Santoro, T. R. Fan, “Spread spectrum fiber-optic local area network using optical processing,” J. Lightwave Technol. 4, 547–554 (1986). [CrossRef]
  4. J. A. Salehi, “Code division multiple-access techniques in optical fiber networks. 1. Fundamental principles,” IEEE Trans. Commun. 37, 824–833 (1989). [CrossRef]
  5. M. Kavehrad, D. Zaccarin, “Optical code-division-multiplexed systems based on spectral encoding of noncoherent sources,” J. Lightwave Technol. 13, 534–545 (1995). [CrossRef]
  6. C. F. Lam, D. T. K. Tong, M. C. Wu, E. Yablonovitch, “Experimental demonstration of bipolar optical CDMA system using a balanced transmitter and complementary spectral encoder,” IEEE Photon. Technol. Lett. 10, 1504–1506 (1998). [CrossRef]
  7. A. M. Weiner, J. P. Heritage, J. A. Salehi, “Encoding and decoding of femtosecond pulses,” Opt. Lett. 13, 300–302 (1988). [CrossRef] [PubMed]
  8. J. A. Salehi, A. M. Weiner, J. P. Heritage, “Coherent ultrashort light pulse code-division multiple access communication systems,” J. Lightwave Technol. 8, 478–491 (1990). [CrossRef]
  9. K. Kitayama, “Novel spatial spread spectrum based fiber optic CDMA networks for image transmission,” IEEE J. Sel. Areas Commun. 12, 762–772 (1994). [CrossRef]
  10. E. Park, A. J. Mendez, E. M. Garmire, “Temporal/spatial optical CDMA networks—design, demonstration, and comparison with temporal networks,” IEEE Photon. Technol. Lett. 4, 1160–1162 (1992). [CrossRef]
  11. L. Tančevski, I. Andonovic, “Wavelength hopping/time spreading code division multiple access systems,” Electron. Lett. 30, 1388–1390 (1994). [CrossRef]
  12. E. Jugl, T. Kuhwald, K. Iversen, “Algorithm for construction of (0, 1)-matrix codes,” Electron. Lett. 33, 227–229 (1997). [CrossRef]
  13. H. Fathallah, L. A. Rusch, S. LaRochelle, “Passive optical fast frequency-hop CDMA communications systems,” J. Lightwave Technol. 17, 397–405 (1999). [CrossRef]
  14. S. Kim, K. Yu, N. Park, “A new family of space/wavelength/time spread three dimensional optical code for OCDMA networks,” J. Lightwave Technol. 18, 502–511 (2000). [CrossRef]
  15. A. J. Mendez, R. M. Gagliardi, H. X. C. Feng, J. P. Heritage, J.-P. Morookian, “Strategies for realizing optical CDMA for dense, high-speed, long span, optical network applications,” J. Lightwave Technol. 18, 1685–1696 (2000). [CrossRef]
  16. K. Yu, N. Park, “Design of new family of two-dimensional wavelength-time spreading codes for optical code division multiple access networks,” Electron. Lett. 35, 830–831 (1999). [CrossRef]
  17. C. Zuo, W. M. Hongtu, J. Lin, “The impact of group velocity on frequency-hopping optical code division multiple access system,” J. Lightwave Technol. 19, 1416–1419 (2001). [CrossRef]
  18. E. K. H. Ng, G. E. Weichenberg, E. H. Sargent, “Dispersion in multiwavelength optical code-division-multiple-access systems: impacts and remedies,” IEEE Trans. Commun. 50, 1811–1816 (2002). [CrossRef]
  19. A. Sahin, A. E. Willner, “System limitations due to chromatic dispersion and receiver bandwidth for 2-D time-wavelength OCDMA systems,” in Conference Proceedings of the 16th Annual Meeting of the IEEE Lasers and Electro-Optics Society LEOS ’03 (Institute of Electrical and Electronics Engineers, 2003), Vol. 2, pp. 551–552. [CrossRef]
  20. L. Tančevski, L. A. Rusch, “Impact of the beat noise on the performance of 2-D optical CDMA systems,” IEEE Commun. Lett. 4, 264–266 (2000). [CrossRef]
  21. We note that good mechanisms exist to keep the wavelengths of optical filters locked. Moreover, the filter responses can be designed to have boxlike shapes with flat tops and high adjacent-channel cross-talk rejection. Thus, from a practical perspective, we expect wavelength misalignments to be typically a fraction of one wavelength band. Optical path differences (improperly defined delay lines), however, can cause time chip misalignments to extend beyond one time chip. The actual extent will depend on the precision in fabricating and controlling the optical delays as well as on the chip rate of the system. As the chip rate increases, the corresponding chip time decreases, such that a given optical path difference will result in time misalignments extending over a larger fraction of a time chip or even over multiple time chips. In our simulations we do not consider path differences that extend beyond a single time chip, though such situations are straightforward and easy to handle.
  22. R. M. H. Yim, L. R. Chen, J. Bajcsy, “Design and performance of 2-D codes for wavelength–time optical CDMA,” IEEE Photon. Technol. Lett. 14, 714–716 (2002). [CrossRef]
  23. R. M. H. Yim, “New approaches to optical code-division multiple access,” M. Eng. thesis (Department of Electrical and Computer Engineering, McGill University, 2002).

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited