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ABSTRACT: We present a channel-matched coding method for the compensation of dispersion in coarsely quantized coherent optical communication systems. The approach consists in optimizing a subset of equiprobable input symbols for each channel state, which is robust against dispersion and coarse quantization. This codebook optimization is solved efficiently using an iterative algorithm. The performance of the channel-matched codes is simulated for a 42.8Gbit/s dual-polarization coherent optical fiber system with QPSK modulation and single-bit analog-to-digital (A/D) conversion. Apart from the optimization, the proposed coding method does not increase the encoding/decoding complexity, but yields a considerable coding gain.
Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE; 01/2011
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ABSTRACT: We demonstrate the application of superscalar and interleaving hardware parallelization scheme on carrier recovery for coherent optic receivers. The combination of superscalar parallelization with feedback carrier recovery provides performance close to the theoretical limit.
Optical Communication (ECOC), 2010 36th European Conference and Exhibition on; 10/2010
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ABSTRACT: Coherent systems based on QPSK rely on differential encoding to avoid catastrophic error propagation. A simple solution for soft differential decoding is presented that limits the penalty after FEC to 0.75dB, similar to pre-FEC binary differential decoding.
Optical Communication (ECOC), 2010 36th European Conference and Exhibition on; 10/2010
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ABSTRACT: Coherent communication systems are largely limited by the laser linewidth of the local oscillator. In addition to phase noise, large frequency deviations can occur if the laser is mechanically vibrated. The detrimental effect of the frequency instability is measured for coherent optical receivers on a typical laser and numerically analyzed for quadrature phase-shift keying and 16-quadrature amplitude modulation using common feed-forward carrier phase recovery algorithms.
IEEE Photonics Technology Letters 09/2010; · 2.19 Impact Factor
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ABSTRACT: The performance of coherent polarization- multiplexed optical systems is evaluated in the presence of polarization-dependent loss (PDL) for linear and maximum- likelihood receivers and lumped noise at the receiver. The boundaries of PDL mitigation methods are discussed.
IEEE Photonics Technology Letters 07/2010; · 2.19 Impact Factor
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ABSTRACT: Fiber-optic research in signal processing for the first generation of coherent communication systems was dominated by receivers with blind adaptation. Next-generation systems will require a scalable and modular design for higher order modulation formats. Due to the nature of the fiber channel and the required parallelization in high-speed receivers, data-aided and blind algorithms call for a general reassessment when used in coherent optic receivers employing higher order modulation formats. In this paper, blind and data-aided receivers are compared for coherent single-carrier optical systems in terms of complexity, tracking ability, and convergence speed. Methods for equalization are discussed for time-domain- and frequency-domain-based receivers covering the most important algorithms. The general superiority of data-aided frequency-domain equalization is demonstrated.
IEEE Photonics Journal 07/2010; · 2.32 Impact Factor
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ABSTRACT: Data-aided algorithms for coherent optic receivers are discussed as an extension of existing non-data aided methods. The concept presents a scalable approach with low implementation complexity and limited overhead for higher-order modulation formats.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: In this paper, we present a method for combined fiber parameter estimation from digital filter coefficients of a polarization diverse coherent receiver. All deterministic linear optical channel parameters like residual chromatic dispersion (CD), polarization-mode dispersion (PMD), and polarization-dependent loss (PDL) are continuously monitored by analysis of the filter impulse response of the adaptive equalizer. After deriving the according equations from the theoretical linear fiber channel model, we demonstrate robust estimation for a joint combination of all impairments.
Journal of Lightwave Technology 09/2009; · 2.78 Impact Factor
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ABSTRACT: In this paper, we outline the design of signal processing (DSP) algorithms with blind estimation for 100-G coherent optical polarization-diversity receivers in single-carrier systems. As main degrading optical propagation effects, we considered chromatic dispersion (CD), polarization-mode dispersion (PMD), polarization-dependent loss (PDL), and cross-phase modulation (XPM). In the context of this work, we developed algorithms to increase the robustness of the single DSP receiver modules against the aforesaid propagation effects. In particular, we first present a new and fast algorithm to perform blind adaptive CD compensation through frequency-domain equalization. This low complexity equalizer component inherits a highly precise estimation of residual dispersion independent from previous or subsequent blocks. Next, we introduce an original dispersion-tolerant timing recovery and illustrate the derivation of blind polarization demultiplexing, capable to operate also in condition of high PDL. At last, we propose an XPM-mitigating carrier phase recovery as an extension of the standard Viterbi-Viterbi algorithm.
Journal of Lightwave Technology 09/2009; · 2.78 Impact Factor
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ABSTRACT: We propose applications of well-known algorithms for non-data aided spectrum-based frequency offset estimation in optical coherent receivers. The algorithms are independent of the modulation format and robust against channel distortion.
Photonic Networks, 2009 ITG Symposium on; 06/2009
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M.S. Alfiad,
M. Kuschnerov,
T. Wuth,
T.J. Xia,
G. Wellbrock,
E.-D. Schmidt,
D. van den Borne,
B. Spinnler,
C.J. Weiske,
E. de Man, [......],
M. Chbat,
J. Stachowiak,
D. Peterson,
W. Lee,
M. Pollock,
B. Basch,
D. Chen,
M. Freiberger, B. Lankl,
H. de Waardt
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ABSTRACT: We demonstrate transmission of a 111-Gb/s coherent polarization-multiplexed return-to-zero differential quadrature phase-shift keying signal over 1040-km field-deployed fiber together with different types of neighboring channels, and with a cascade of 50-GHz reconfigerable optical add-drop multiplexers. Our transmission experiment proves the feasibility of transmitting a 111-Gb/s phase-modulated channel with 10 times 10.7-Gb/s on-off keying neighboring channels on a 50-GHz grid, despite the presence of strong cross-phase modulation.
IEEE Photonics Technology Letters 06/2009; · 2.19 Impact Factor
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ABSTRACT: Blind adaptive chromatic dispersion equalization for coherent polarization multiplexed (NRZ/RZ)-QPSK receivers is presented. A novel low complexity estimation algorithm precisely estimates arbitrarily large dispersion in a fixed adaptation length.
Optical Fiber Communication - incudes post deadline papers, 2009. OFC 2009. Conference on; 04/2009
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ABSTRACT: We proposed a novel algorithm for carrier phase estimation with differential demodulation, phase coupling between both polarizations and non-redundant error correction. The algorithm is demonstrated on measured 111 Gb/s polarization-multiplexed QPSK with 10times10.7 Gb/s OOK neighbours.
Optical Fiber Communication - incudes post deadline papers, 2009. OFC 2009. Conference on; 04/2009
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ABSTRACT: A novel algorithm for frequency offset compensation and carrier phase estimation in systems with 40 or 111 Gb/s coherent dual-polarization quadrature phase-shift keying (DP-QPSK) with on-off keying or DP-QPSK neighbors is demonstrated. The algorithm, which applies correlation phase adjustment embedded between digital differential demodulation and nonredundant error correction, leads to a significant performance improvement over standard algorithms.
IEEE Photonics Technology Letters 01/2009; · 2.19 Impact Factor
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ABSTRACT: We estimate the DGD tau(omega) over the complete system bandwidth from FIR filter taps in coherent receivers with digital equalization, obtaining accurate DGD values even in presence of higher order PMD.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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ABSTRACT: We demonstrate the transmission of 111-Gb/s POLMUX-RZ-DQPSK over an 1140 km EDFA-only link in the presence of 10times10.7-Gb/s OOK neighbours and show the impact of channel spacing on the cross-talk.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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ABSTRACT: A new low-complexity, dispersion-robust digital timing recovery for coherent systems is presented as a joint implementation with the FIR-equalizer, demonstrated for 112 Gb/s RZ-CP-QPSK.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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M. Kuschnerov,
D. van den Borne,
K. Piyawanno,
F.N. Hauske,
C.R.S. Fludger,
T. Duthel,
T. Wuth,
J.C. Geyer,
C. Schulien,
B. Spinnler,
E.-D. Schmidt, B. Lankl
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ABSTRACT: We demonstrate joint polarization carrier phase estimation for XPM-limited channels with significant improvements over standard methods, demonstrated on measurements of 43 Gb/s NRZ-CP-QPSK with 10.7 Gb/s OOK neighbors.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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T.J. Xia,
G. Wellbrock,
D. Peterson,
W. Lee,
M. Pollock,
B. Basch,
D. Chen,
M. Freiberger,
M. Alfiad,
H. de Waardt, [......],
E. de Man,
C. Xie,
D. van den Borne,
M. Finkenzeller,
S. Spaelter,
R. Derksen,
M. Rehman,
J. Behel,
J. Stachowiak,
M. Chbat
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ABSTRACT: 111-Gb/s transmission combined with 2 times 43-Gb/s and 8 times 10.7-Gb/s on a 50-GHz grid over 1,040-km field fiber and two ROADMs is demonstrated, showing the feasibility of 100G overlaying existing 10G/40G commercial systems.
Optical Communication, 2008. ECOC 2008. 34th European Conference on; 10/2008
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ABSTRACT: We optimize carrier phase estimation (CPE) to increase the XPM tolerance of 111-Gb/s POLMUX-RZ-DQPSK in the presence of 10.7-Gb/s OOK neighbours transmitted over an 1140 km EDFA-only link.
IEEE/LEOS Summer Topical Meetings, 2008 Digest of the; 08/2008
