This paper describes the state-of-the-art of polarization multiplexing for optical networks transmission. The use of polarization division multiplexing (PDM) permits to multiply the user capacity and increase the spectral efficiency. Combining PDM and orthogonal frequency division multiplexed (OFDM) modulation allows maximizing the optical transmission capacity. The experimental demonstration of transmitting OFDM signals following ECMA-368 ultrawide band (UWB) standard in radio-over-fiber using PDM in passive optical networks is herein reported. The impact of cross-polarization and cochannel crosstalk is evaluated experimentally in a three-user OFDM-UWB subcarrier multiplexed (SCM) configuration per polarization. Each SCM uses up to three OFDM-UWB channels of 200？Mbit/s each, achieving an aggregated bitrate of 1.2？Gbit/s with 0.76？bit/s/Hz spectral efficiency when using PDM transmission. The experimental results for the polarization-multiplexed SCM indicate that a 4？dB additional polarization crosstalk interference can be expected compared to a nonpolarization-multiplexed transmission system which translates to 2.4？dB EVM penalty in the UWB signals. The successful PDM transmission of SCM multiuser OFDM-UWB over a passive optical network of 25？km standard-single mode fiber (SSMF) reach is demonstrated. 1. Introduction The ever-growing transmission capacity demand in optical transmission systems has brought out the necessity of increasing the spectral efficiency employing different transmission techniques. Several approaches have been proposed to date in order to increase the transmission capacity, that is, bitrate by number of users. In particular, the use of efficient modulation formats altogether with advanced multiplexing techniques has been indicated as an interesting approach. New modulation formats have been reported suitable for providing higher bitrate to the final customer. Especially, orthogonal frequency division multiplexing (OFDM) modulation has been adopted by several wireless standards such as 3GPP long-term evolution (LTE) or IEEE 802.16 worldwide interoperability for microwave access (WiMAX), between others. Also, new transmission technologies based on spreading techniques such as ultrawide band (UWB) use OFDM modulation. These signals can achieve high spectral efficiency when using several hundreds of OFDM subcarriers. Another advantage of the OFDM signals is the capability to correct multipath fading thanks to the cyclic prefix of the OFDM signal. For these reasons, OFDM suitability for optical communications has attracted a lot of
References
[1]
I. Morita, “Optical OFDM for high-speed transmission,” in Proceedings of the 14th OptoElectronics and Communications Conference (OECC '09), July 2009.
[2]
T. Koonen, M. García Larrodé, P. Urban et al., “Fibre-based versatile broadband access and in-building networks,” in Proceedings of the IET Workshop from Access to Metro, December 2007.
[3]
M. I. Hayee, M. C. Cardakli, A. B. Sahin, and A. E. Willner, “Doubling of bandwidth utilization using two orthogonal polarizations and power unbalancing in a polarization-division-multiplexing scheme,” IEEE Photonics Technology Letters, vol. 13, no. 8, pp. 881–883, 2001.
[4]
L. G. Kazovsky, W.-T. Shaw, D. Gutierrez, N. Cheng, and S.-W. Wong, “Next-generation optical access networks,” IEEE/OSA Journal of Lightwave Technology, vol. 25, no. 11, pp. 3428–3442, 2007.
[5]
M. Morant, R. Llorente, J. Hauden, T. Quinlan, A. Mottet, and S. Walker, “Dual-drive LiNbO3 interferometric Mach-Zehnder architecture with extended linear regime for high peak-to-average OFDM-based communication systems,” Optics Express, vol. 19, no. 26, pp. 197–202, 2011.
[6]
L. J. Cimini, I. M. I. Habbab, R. K. John, and A. A. M. Saleh, “Preservation of polarization orthogonality through a linear optical system,” Electronics Letters, vol. 23, no. 25, pp. 1365–1366, 1987.
[7]
T. Ito, T. Ono, Y. Yano et al., “Feasibility study on over 1？bit/s/Hz high spectral efficiency WDM with optical duobinary coding and polarization interleave multiplexing,” in Proceedings of the Optical Fiber Communication Conference (OFC '97), pp. 43–44, February 1997.
[8]
H. Sotobayashi, W. Chujo, and K.-I. Kitayama, “1.6？bit/s/Hz, 6.4？Tbit/s OCDM/WDM (4？OCDM × 40？WDM × 40？Gbit/s) transmission experiment,” in Proceedings of the 27th European Conference on Optical Communication (ECOC '01), vol. 6, pp. 6–7, 2001.
[9]
B. C. Collings and L. Boivin, “Nonlinear polarization evolution induced by cross-phase modulation and its impact on transmission systems,” IEEE Photonics Technology Letters, vol. 12, no. 11, pp. 1582–1584, 2000.
[10]
J. P. Gordon and H. Kogelnik, “PMD fundamentals: Polarization mode dispersion in optical fibers,” Proceedings of the National Academy of Sciences of the United States of America, vol. 97, no. 9, pp. 4541–4550, 2000.
[11]
L. E. Nelson, T. N. Nielsen, and H. Kogelnik, “Observation of PMD-induced coherent crosstalk in polarization-multiplexed transmission,” IEEE Photonics Technology Letters, vol. 13, no. 7, pp. 378–390, 2001.
[12]
S. L. Jansen, I. Morita, and H. Tanaka, “10 × 121.9-Gb/s PDM-OFDM transmission with 2-b/s/Hz spectral efficiency over 1,000？km of SSMF,” in Proceedings of the Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC '08), PDP2, February 2008.
[13]
D. Gesbert, M. Shafi, D.-S. Shiu, P. J. Smith, and A. Naguib, “From theory to practice: an overview of MIMO space-time coded wireless systems,” IEEE Journal on Selected Areas in Communications, vol. 21, no. 4, pp. 281–282, 2003.
[14]
M. Morant, R. Llorente, and J. Prat, “LTE advanced carrier aggregation supporting fully standard 3GPP MIMO by optical polarization multiplexing,” in Proceedings of the Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC '14), paper M3D.2, March 2014.
[15]
D. Qian, N. Cvijetic, J. Hu, and T. Wang, “40-Gb/s MIMO-OFDM-PON using polarization multiplexing and direct-detection,” in Proceedings of Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC '09), paper OMV3, March.
[16]
M. Morant, J. Perez, R. Llorente, and J. Marti, “Combined analysis of OFDM-UWB transmission in hybrid wireless-optical access networks,” IEEE Photonics Technology Letters, vol. 21, no. 19, pp. 1378–1380, 2009.
[17]
M. Morant, T. Quinlan, S. Walker, and R. Llorente, ““Real world” FTTH optical-to-radio interface performance for bi-directional multi-format OFDM wireless signal transmission,” in Proceedings of the Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC '11), paper NTuB6, March 2011.
[18]
FCC 02-48, Revision of Part 15 of the Commission’s Rules Regarding Ultra-Wideband Transmission Systems, FCC, 2002.
[19]
ECMA-368 International Standard, High Rate Ultra Wideband PHY and MAC Standard, 2005.
[20]
R. Llorente, T. Alves, M. Morant et al., “Ultra-wideband radio signals distribution in FTTH networks,” IEEE Photonics Technology Letters, vol. 20, no. 11, pp. 945–947, 2008.
[21]
M. Morant, J. Perez, R. Llorente, and J. Marti, “Transmission of 1.2？Gbit/s polarization-multiplexed UWB Signals in PON with 0.76？bit/s/Hz spectral efficiency,” in Proceedings of Optical Fiber Communication Conference (OFC '09), paper OTuJ6, March 2009.
[22]
J. Perez, M. Morant, R. Llorente, and J. Martí, “Joint distribution of polarization-multiplexed UWB and WiMAX radio in PON,” Journal of Lightwave Technology, vol. 27, no. 12, pp. 1912–1919, 2009.
[23]
M. Morant, J. Pérez, and R. Llorente, “Effect of multi-channel MB-OFDM UWB radio-over-fiber transmission using polarization multiplexed distribution in FTTH networks,” in Proceedings of the Access Networks and In-House Communications (ANIC '10), paper AThA6, June 2010.
[24]
General Photonics, “Reset-free polarization stabilizer—PolaStay,” http://www.generalphotonics.com/pdf/PolaStay.pdf.
[25]
T. Pratt, B. Walkenhorst, and S. Nguyen, “Adaptive polarization transmission of OFDM signals in channels with polarization mode dispersion and polarization-dependent loss,” IEEE Transactions on Wireless Communications, vol. 8, no. 7, pp. 3354–3359, 2009.
[26]
M. T. Core, “Cross polarization interference cancellation for fiber optic systems,” IEEE Journal of Lightwave Technology, vol. 24, no. 1, pp. 305–312, 2006.
[27]
T. Alves and A. Cartaxo, “Performance degradation due to OFDM-UWB radio signal transmission along dispersive single-mode fiber,” IEEE Photonics Technology Letters, vol. 21, no. 3, pp. 158–160, 2009.
