Abstract

A simple optical OFDM (OOFDM) synchronization technique utilizing subtraction and Gaussian windowing at the symbol rate is proposed and implemented in FPGA-based OOFDM receivers. End-to-end real-time symbol synchronization of 128-QAM-encoded OOFDM signals at raw bit rates of 6.56Gb/s is experimentally demonstrated, for the first time, over directly modulated DFB laser-based 25km SMF intensity modulation and direct detection (IMDD) systems. Experimental investigations show that the proposed synchronisation technique offers a number of salient advantages including low complexity, fast tracking speed, high accuracy and suitability for high-capacity optical transmission systems.

© 2010 OSA

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  15. J. M. Tang and X. Q. Jin, “Synchronization process in optical frequency division multiplexing transmission systems,” UK patent application no. 0919057.0, (2009)
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    [CrossRef] [PubMed]
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  20. F. Buchali, R. Dischler, A. Klekamp, M. Bernhard, and D. Efinger, “Realization of a real-time 12.1 Gb/s optical OFDM transmitter and its application in a 109 Gb/s transmission system with coherent reception,” European Conference on Optical Communication (ECOC), (Vienna, 2009), PD paper 2.1.
  21. D. Qian, T. T.-O. Kwok, N. Cvijetic, J. Hu, and T. Wang, “41.25Gb/s real-time OFDM receiver for variable rate WDM-OFDMA-PON transmission,” Optical Fibre Communication/National Fibre Optic Engineers Conference (OFC/NFOEC), (OSA, 2010), Paper PDPD9.

2010 (2)

2009 (3)

2008 (2)

2006 (2)

J. M. Tang and K. A. Shore, “30 Gb/s signal transmission over 40-km directly modulated DFB-laser-based single-mode-fibre links without optical amplification and dispersion compensation,” J. Lightwave Technol. 24(6), 2318–2327 (2006).
[CrossRef]

H. Minn, V. K. Bhargava, and K. B. Letaief, “A combined timing and frequency synchronization and channel estimation for OFDM,” IEEE Trans. Commun. 54(3), 416–422 (2006).
[CrossRef]

2001 (2)

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

1999 (1)

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

1998 (1)

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

1997 (1)

T. M. Schmidl and D. C. Cox, “Robust frequency and timing synchronization for OFDM,” IEEE Trans. Commun. 45(12), 1613–1621 (1997).
[CrossRef]

Benlachtar, Y.

Bhargava, V. K.

H. Minn, V. K. Bhargava, and K. B. Letaief, “A combined timing and frequency synchronization and channel estimation for OFDM,” IEEE Trans. Commun. 54(3), 416–422 (2006).
[CrossRef]

Bouziane, R.

Breyer, F.

Cartolano, A.

Chandrasekhar, S.

Chen, Y.-K.

Cho, H. B.

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Choi, H. J.

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Cox, D. C.

T. M. Schmidl and D. C. Cox, “Robust frequency and timing synchronization for OFDM,” IEEE Trans. Commun. 45(12), 1613–1621 (1997).
[CrossRef]

Do, S. H.

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Fechtel, S.

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

Fechtel, S. A.

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

Fock, G.

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

Giacoumidis, E.

Giddings, R. P.

Glick, M.

Hanzo, L.

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

Hoe, J. C.

Hugues-Salas, E.

Jin, X. Q.

Kaneda, N.

Keller, T.

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

Killey, R. I.

Kim, D. K.

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Kim,, K. B.

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Koonen, A. M. J.

Koutsoyannis, R.

Lee, S. C. J.

Letaief, K. B.

H. Minn, V. K. Bhargava, and K. B. Letaief, “A combined timing and frequency synchronization and channel estimation for OFDM,” IEEE Trans. Commun. 54(3), 416–422 (2006).
[CrossRef]

Liu, X.

Ma, Y.

Mandarini, P.

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

Meyr, H.

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

Milder, P.

Minn, H.

H. Minn, V. K. Bhargava, and K. B. Letaief, “A combined timing and frequency synchronization and channel estimation for OFDM,” IEEE Trans. Commun. 54(3), 416–422 (2006).
[CrossRef]

Piazzo, L.

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

Püschel, M.

Randel, S.

Rangaraj, D.

Schmidl, T. M.

T. M. Schmidl and D. C. Cox, “Robust frequency and timing synchronization for OFDM,” IEEE Trans. Commun. 45(12), 1613–1621 (1997).
[CrossRef]

Shieh, W.

Shore, K. A.

Speth, M.

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

Tang, J. M.

van den Boom, H. P. A.

Watts, P. M.

Wei, J. L.

Yang, Q.

Yi, X.

IEEE J. Sel. Areas Comm. (1)

T. Keller, L. Piazzo, P. Mandarini, and L. Hanzo, “Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels,” IEEE J. Sel. Areas Comm. 19(6), 999–1008 (2001).
[CrossRef]

IEEE Trans. Commun. (4)

H. Minn, V. K. Bhargava, and K. B. Letaief, “A combined timing and frequency synchronization and channel estimation for OFDM,” IEEE Trans. Commun. 54(3), 416–422 (2006).
[CrossRef]

T. M. Schmidl and D. C. Cox, “Robust frequency and timing synchronization for OFDM,” IEEE Trans. Commun. 45(12), 1613–1621 (1997).
[CrossRef]

M. Speth, S. A. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for wireless broad-band systems using OFDM—part I,” IEEE Trans. Commun. 47(11), 1668–1677 (1999).
[CrossRef]

M. Speth, S. Fechtel, G. Fock, and H. Meyr, “Optimum receiver design for OFDM-based broadband transmission—part II: a case study,” IEEE Trans. Commun. 49(4), 571–578 (2001).
[CrossRef]

J. Lightwave Technol. (3)

J. Opt. Netw. (1)

Opt. Express (4)

Trans. Consumer Electronics (1)

D. K. Kim, S. H. Do, H. B. Cho, H. J. Choi, and K. B. Kim, “A new joint algorithm of symbol timing recovery and sampling clock adjustment for OFDM systems,” Trans. Consumer Electronics 44(3), 1142–1149 (1998).
[CrossRef]

Other (7)

J. M. Tang and X. Q. Jin, “Synchronization process in optical frequency division multiplexing transmission systems,” UK patent application no. 0919057.0, (2009)

X. Jin, Theoretical and experimental investigations of optical OFDM for local and access networks, Ph.D thesis, (Bangor University, 2010), Chap. 8.

F. Buchali, R. Dischler, A. Klekamp, M. Bernhard, and D. Efinger, “Realization of a real-time 12.1 Gb/s optical OFDM transmitter and its application in a 109 Gb/s transmission system with coherent reception,” European Conference on Optical Communication (ECOC), (Vienna, 2009), PD paper 2.1.

D. Qian, T. T.-O. Kwok, N. Cvijetic, J. Hu, and T. Wang, “41.25Gb/s real-time OFDM receiver for variable rate WDM-OFDMA-PON transmission,” Optical Fibre Communication/National Fibre Optic Engineers Conference (OFC/NFOEC), (OSA, 2010), Paper PDPD9.

R. Dischler, A. Klekamp, F. Buchali, W. Idler, E. Lach, A. Schippel, M. Schneiders, S. Vorbeck, and R.-P. Braun, “Transmission of 3x253-Gb/s OFDM-superchannels over 764 km field deployed single mode fibers,” Optical Fibre Communication/National Fibre Optic Engineers Conference (OFC/NFOEC), (OSA, 2010), Paper PDPD2.

Z. Zan, M. Premaratne, and A. J. Lowery, “Laser RIN and linewidth requirements for direct detection optical OFDM,” Optical Fibre Communication/National Fibre Optic Engineers Conference (OFC/NFOEC), (OSA, 2008), Paper CWN2.

F. Tufvesson, O. Edfors, and M. Faulkner, “Time and frequency synchronization for OFDM using PN-sequence preambles,” Vehicular Technology Conference, Amsterdam, Netherlands (1999).

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Figures (8)

Fig. 5
Fig. 5

Normalized synchronization profile before applying Gaussian windowing (a) and after applying Gaussian windowing (b) for different α coefficients. The results are measured at fixed received optical powers of −16dBm.

Fig. 1
Fig. 1

Diagram of the proposed symbol synchronization technique, L: OOFDM symbol length, N: FFT window length, S/H: sample-and-hold. n is the maximum value within yn(i), Z−1: one-symbol delay.

Fig. 2
Fig. 2

Synchronization profile generation.

Fig. 3
Fig. 3

Definition of centre of gravity (COG) and calculation of sampling clock offset (SCO).

Fig. 4
Fig. 4

Real-time experimental system setup with symbol synchronization.

Fig. 6
Fig. 6

Dynamic COG evolution at received optical powers of −16dBm.

Fig. 7
Fig. 7

BER performance versus initial symbol timing offset (STO) for different signal modulation formats.

Fig. 8
Fig. 8

Transmission performance using the proposed synchronization technique.

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

x n ( i ) = | r n ( i ) r n ( i + N ) | i = 0 , 1 , 2 , , L 1
y n ( i ) = α x n ( i ) + ( 1 α ) y n 1 ( i ) .
q n ( i ) = [ y n ' y n ( i ) ] g ( i i c )
g ( i ) = exp [ ( i i w ) 6 ]
s * ( t ) = s ( t ) h ( t ) + w ( t )
x n ( i ) = | r n ( t ) r n ( t T F ) | | t = ( n L + i ) T S = | + h ( τ ) [ s n ( t τ ) s n ( t T F τ ) ] d τ + w ' ( t ) | | t = ( n L + i ) T S
ξ = ( P 2 P 1 ) / M

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