Abstract

We have experimentally demonstrated two novel pulse position modulation techniques, namely Double Pulse Position Modulation (2-PPM) and Differential Pulse Position Modulation (DPPM) in Time-Wavelength OCDMA systems that will operate at a higher bit rate compared to traditional OOK-OCDMA systems with the same bandwidth. With 2-PPM technique, the number of active users will be more than DPPM while their bit rate is almost the same. Both techniques provide variable quality of service in OCDMA networks.

© 2007 Optical Society of America

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References

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  1. J. A. Salehi, "Code division multiple-access techniques in optical fiber networks. I. Fundamental principles," IEEE Trans. Commun. 37, 824-833 (1989).
    [CrossRef]
  2. A. Stok and E. H. Sargent, "The role of optical CDMA in access networks," IEEE Commun. Magazine 40, 83-87 (2002).
    [CrossRef]
  3. P. Saghari, R. Omrani, A. E. Willner, and P. V. Kumar, "Analytical interference model for two-dimensional (timewavelength) asynchronous O-CDMA systems using various receiver structures," J. Lightwave Technol. 23, 3260-3269 (2005).
    [CrossRef]
  4. H. Sugiyama and K. Nosu, "MPPM: a method for improving the band-utilization efficiency in optical PPM," J. Lightwave Techol. 7, 465-472 (1989).
    [CrossRef]
  5. D. Shiu and J. M. Kahn, "Differential pulse-position modulation for power-efficient optical communication," IEEE Trans. Commun. 47, 1201-1210 (1999).
    [CrossRef]
  6. H. M. H. Shalaby, "Performance analysis of optical synchronous CDMA communication systems with PPM signaling," IEEE Trans. Commun. 43, 624-634 (1995).
    [CrossRef]
  7. H. M. H. Shalaby, "A performance analysis of optical overlapping PPM-CDMA communication systems," J. Lightwave Techonl. 17, 426-433 (1999).
    [CrossRef]
  8. S. Zahedi, J. A. Salehi, and M. Nasiri-Kenari, "M-ary infrared CDMA for indoors wireless communications," IEEE PIMRC Conf. 2, E6-E10 (2001).
  9. P. Saghari, M. Haghi, V. R. Arbab, S. Kumar, R. Golizadeh, A. E. Willner, P. V. Kumar, and J. D. Touch "Experimental Demonstration of Code Position Modulation in an O-CDMA System to Increase the Number of Users," IEEE/OSA Conf. Lasers and Electroptics, CWH3, (2006).
  10. P. Saghari, R. Omrani, V. R. Arbab, A. E. Willner, and P. V. Kumar, "Increasing the Number of Users in an Optical CDMA System by Pulse Postition Modulation," IEEE/OSA Optical Fiber Conf. JThA72, (2007).
  11. H. Fathallah, L. A. Rusch, S. LaRochelle, "Passive optical fast frequency-hop CDMA communications system," J. Lightwave Technol. 17, 397-405 (1999)
    [CrossRef]

2005 (1)

2002 (1)

A. Stok and E. H. Sargent, "The role of optical CDMA in access networks," IEEE Commun. Magazine 40, 83-87 (2002).
[CrossRef]

2001 (1)

S. Zahedi, J. A. Salehi, and M. Nasiri-Kenari, "M-ary infrared CDMA for indoors wireless communications," IEEE PIMRC Conf. 2, E6-E10 (2001).

1999 (3)

H. Fathallah, L. A. Rusch, S. LaRochelle, "Passive optical fast frequency-hop CDMA communications system," J. Lightwave Technol. 17, 397-405 (1999)
[CrossRef]

D. Shiu and J. M. Kahn, "Differential pulse-position modulation for power-efficient optical communication," IEEE Trans. Commun. 47, 1201-1210 (1999).
[CrossRef]

H. M. H. Shalaby, "A performance analysis of optical overlapping PPM-CDMA communication systems," J. Lightwave Techonl. 17, 426-433 (1999).
[CrossRef]

1995 (1)

H. M. H. Shalaby, "Performance analysis of optical synchronous CDMA communication systems with PPM signaling," IEEE Trans. Commun. 43, 624-634 (1995).
[CrossRef]

1989 (2)

J. A. Salehi, "Code division multiple-access techniques in optical fiber networks. I. Fundamental principles," IEEE Trans. Commun. 37, 824-833 (1989).
[CrossRef]

H. Sugiyama and K. Nosu, "MPPM: a method for improving the band-utilization efficiency in optical PPM," J. Lightwave Techol. 7, 465-472 (1989).
[CrossRef]

IEEE Commun. Magazine (1)

A. Stok and E. H. Sargent, "The role of optical CDMA in access networks," IEEE Commun. Magazine 40, 83-87 (2002).
[CrossRef]

IEEE PIMRC Conf. (1)

S. Zahedi, J. A. Salehi, and M. Nasiri-Kenari, "M-ary infrared CDMA for indoors wireless communications," IEEE PIMRC Conf. 2, E6-E10 (2001).

IEEE Trans. Commun. (3)

D. Shiu and J. M. Kahn, "Differential pulse-position modulation for power-efficient optical communication," IEEE Trans. Commun. 47, 1201-1210 (1999).
[CrossRef]

H. M. H. Shalaby, "Performance analysis of optical synchronous CDMA communication systems with PPM signaling," IEEE Trans. Commun. 43, 624-634 (1995).
[CrossRef]

J. A. Salehi, "Code division multiple-access techniques in optical fiber networks. I. Fundamental principles," IEEE Trans. Commun. 37, 824-833 (1989).
[CrossRef]

J. Lightwave Technol. (2)

J. Lightwave Techol. (1)

H. Sugiyama and K. Nosu, "MPPM: a method for improving the band-utilization efficiency in optical PPM," J. Lightwave Techol. 7, 465-472 (1989).
[CrossRef]

J. Lightwave Techonl. (1)

H. M. H. Shalaby, "A performance analysis of optical overlapping PPM-CDMA communication systems," J. Lightwave Techonl. 17, 426-433 (1999).
[CrossRef]

Other (2)

P. Saghari, M. Haghi, V. R. Arbab, S. Kumar, R. Golizadeh, A. E. Willner, P. V. Kumar, and J. D. Touch "Experimental Demonstration of Code Position Modulation in an O-CDMA System to Increase the Number of Users," IEEE/OSA Conf. Lasers and Electroptics, CWH3, (2006).

P. Saghari, R. Omrani, V. R. Arbab, A. E. Willner, and P. V. Kumar, "Increasing the Number of Users in an Optical CDMA System by Pulse Postition Modulation," IEEE/OSA Optical Fiber Conf. JThA72, (2007).

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Figures (5)

Fig. 1.
Fig. 1.

Different pulse position modulation techniques with M=4 (a) PPM, 4 possible symbols, (b) 2-PPM, 6 possible symbols, (c) DPPM, 4 possible symbols, 2.5 time-slots needed for each symbol in average, (d) comparison of the average number of transmitted bits per symbol time for the three PPM techniques versus M.

Fig. 2.
Fig. 2.

Block diagram of a 2-PPM- (or DPPM-) OCDMA system. Four different wavelengths are shown by different patterns and multiple access interference is shown by the black pulses. Error in transmission happens when MAI or noise changes a zero slot to one.

Fig. 3.
Fig. 3.

Experimental setup for implementing 2-PPM and DPPM OCDMA.

Fig. 4.
Fig. 4.

(a) 2-PPM symbols after the modulator, (b) Encoded symbols after the FBG, (c) Decoded symbols in presence of four other active users, (d) BER curve vs. the received power of the main user, (e) required amount of extra power to switch from PPM-OCDMA to 2-PPM-OCDMA.

Fig. 5.
Fig. 5.

(a), (b), (c) OOK, PPM, and DPPM transmission time comparison, (d) encoded DPPM-OCDMA symbols, (e) decoded symbols (single user), (f) decoded symbols with MAI from two other interfering users, (g) BER curves for different number of users in the network vs. the received power.

Equations (2)

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R b ( 2 PPM ) = log 2 M ( M 1 ) 2 T s
R b ( DPPM ) = log 2 M ( 1 + 2 + + M ) T s M 2 = 2 M log 2 M ( M + 1 ) T s

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