| 1. |
- Ahmad, Tauseef, 1986, et al.
(author)
-
Methodology for Power-Aware Coherent Receiver Design
- 2013
-
In: Optics InfoBase Conference Papers. - 2162-2701. ; , s. SPT4D.4-
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Conference paper (peer-reviewed)abstract
- We describe a methodology to design and evaluate DSP hardware for a coherent receiver. Important parameters that can be assessed include DSP power consumption and chip area.
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| 2. |
- Beygi, Lotfollah, 1977, et al.
(author)
-
A Discrete-Time Model for Uncompensated Single-Channel Fiber-Optical Links
- 2012
-
In: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 60:11, s. 3440-3450
-
Journal article (peer-reviewed)abstract
- An analytical discrete-time model is introduced for single-wavelength polarization multiplexed nonlinear fiber-optical channels based on the symmetrized split-step Fourier method (SSFM). According to this model, for high enough symbol rates, a fiber-optic link can be described as a linear dispersive channel with additive white Gaussian noise (AWGN) and a complex scaling. The variance of this AWGN noise and the attenuation are computed analytically as a function of input power and channel parameters. The results illustrate a cubic growth of the noise variance with input power. Moreover, the cross effect between the two polarizations and the interaction of amplifier noise and the transmitted signal due to the nonlinear Kerr effect are described. In particular, it is found that the channel noise variance in one polarization is affected twice as much by the transmitted power in that polarization than by the transmitted power in the orthogonal polarization.The effect of pulse shaping is also investigated through numerical simulations. Finally, it is shown that the analytical performance results based on the new model are in close agreement with numerical results obtained using the SSFM for a symbol rate of 28 Gbaud and above.
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| 3. |
- Beygi, Lotfollah, 1977, et al.
(author)
-
A novel multilevel coded modulation scheme for fiber optical channel with nonlinear phase noise
- 2010
-
In: Proc. Global Communications Conference, Miami, FL. - 9781424456383
-
Conference paper (peer-reviewed)abstract
- A multilevel coded modulation (MLCM) system in the presence of nonlinear phase noise for fiber optical communication is introduced. The proposed scheme exploits a 16-point ring constellation with nonlinear post compensation of the self phase modulation produced via the Kerr effect. A new set partitioning based on the Ungerboeck approach is introduced to maintain unequal error protection in amplitude and phase direction. The rate allocation for the MLCM component codes for different fiber lengths and transmit powers are done numerically. Simulation results show that the proposed MLCM system provides up to 2 dB gain over a forward error correcting scheme for a block error rates around 10-9, with the same overhead (7%) and complexity. ©2010 IEEE.
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| 4. |
- Beygi, Lotfollah, 1977, et al.
(author)
-
On nonlinearly-induced noise in single-channel optical links with digital backpropagation
- 2013
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 21:22, s. 26376-26386
-
Journal article (peer-reviewed)abstract
- In this paper, we investigate the performance limits of electronic chromatic dispersion compensation (EDC) and digital backpropagation (DBP) for a single-channel non-dispersion-managed fiber-optical link. A known analytical method to derive the performance of the system with EDC is extended to derive a first-order approximation for the performance of the system with DBP. In contrast to the cubic growth of the variance of the nonlinear noise-like interference, often called nonlinear noise, with input power for EDC, a quadratic growth is observed with DBP using this approximation. Finally, we provide numerical results to verify the accuracy of the proposed approach and compare it with existing analytical models.
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| 5. |
- Beygi, Lotfollah, 1977, et al.
(author)
-
Signal Statistics in Fiber-Optical Channels with Polarization Multiplexing and Self-Phase Modulation
- 2011
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:16, s. 2379 - 2386
-
Journal article (peer-reviewed)abstract
- In this paper, the statistics of received signals in a single-channel dispersion-managed dual-polarization fiber-optical channel are derived in the limit of low dispersion. The joint probability density function (pdf) of the received amplitudes and phases of such a system is derived for both lumped and distributed amplification. The new pdf expressions are used to numerically evaluate the performance of modulation formats over channels with nonlinear phase noise. For example, a sensitivity gain of up to 2 dB is calculated for a specific system using polarization-multiplexed 8-ary phase shift keying compared with a similar single-polarization system at the same spectral efficiency and a symbol error rate of 5*10^(-4). Moreover, the accuracy of the derived pdf is evaluated for some single-channel dispersion-managed fiber-optical links with different dispersion-maps using the split-step Fourier transform method.
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| 6. |
- Beygi, Lotfollah, 1977, et al.
(author)
-
The Limits of Digital Backpropagation in Nonlinear Coherent Fiber-Optical Links
- 2012
-
In: 2012 38th European Conference and Exhibition on Optical Communications, ECOC 2012; Amsterdam; Netherlands; 16 September 2012 through 20 September 2012. - 9781557529503 ; , s. Art. no. 6706029-
-
Conference paper (peer-reviewed)abstract
- The performance of a single-channel fiber-optical link is evaluated with linear (dispersive) and nonlinear equalization. The results show a quadratic growth of the noise variance with input power for a system with nonlinear equalization and also justify the known cubic growth for linear equalization.
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| 7. |
- Björkholm, P., et al.
(author)
-
Navigation in vehicle crash test using MEMS-based IMU
- 2010
-
In: IEEE PLANS, Position Location and Navigation Symposium. - 9781424450367 ; , s. 27-31
-
Conference paper (other academic/artistic)abstract
- Results from our experiments on inertial navigation in crash testing of vehicles are presented. A custom designed inertial measurement unit (IMU) has been developed, and several tests in dummy calibration rigs including full-scale Euro NCAP collisions have been performed at our partners' crash test laboratories. For reference, the IMU data is compared to camera data and traditional single-axis inertial sensors. ©2010 IEEE.
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| 8. |
- Borkowski, R., et al.
(author)
-
Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers
- 2014
-
In: Optical Fiber Technology. - : Elsevier BV. - 1095-9912 .- 1068-5200. ; 20:2, s. 158-162
-
Journal article (peer-reviewed)abstract
- We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) and against differential group delay (DGD) in an experiment involving 112 Gbit/s polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16 QAM) and quaternary phase-shift keying (QPSK).
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| 9. |
- Eliasson, Henrik, 1985, et al.
(author)
-
Transmitter mask testing for 28 GBaud PM-QPSK
- 2013
-
In: Optical Communication (ECOC 2013), 39th European Conference and Exhibition on. - : Institution of Engineering and Technology. - 9781849197595 ; , s. 282 - 284
-
Conference paper (peer-reviewed)abstract
- We suggest a method for pass/fail testing of PM-QPSK transmitters. The test is based on mask testing with time-resolved EVM and accepts transmitters where individual impairments cause less than 0.5 dB OSNR penalty. The design of the test is performed by computer simulations followed by experimental verification of some key results.
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| 10. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Biorthogonal modulation in 8 dimensions experimentally implemented as 2PPM-PS-QPSK
- 2014
-
In: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886984-
-
Conference paper (peer-reviewed)abstract
- We experimentally demonstrate biorthogonal modulation in 8 dimensions as binary pulse-position modulation polarization-switched QPSK. We compare this format with PM-QPSK at the same bit rate and show a 1.4 dB sensitivity gain and 84 % increased transmission distance.
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| 11. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Comparison of 128-SP-QAM and PM-16QAM in long-haul WDM transmission
- 2013
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 21:16, s. 19269-19279
-
Journal article (peer-reviewed)abstract
- We investigate 128-level set-partitioning quadrature amplitude modulation (128-SP-QAM) experimentally and compare the performance to polarization-multiplexed 16QAM both at the same bit rate and at the same symbol rate. Using a recirculating loop we study both single channel and wavelength-division multiplexing (WDM) transmission and demonstrate a reach of up to 2680 km at a bit-error rate of 10−3 for 128-SP-QAM. We confirm that 128-SP-QAM has an increased sensitivity compared to PM-16QAM and show that the maximum transmission distance can be increased by more than 50 % at the same bit rate for both single channel and WDM transmission. We also investigate the performance at the same symbol rate as a possible fall back solution in a degrading link.
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| 12. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Experimental comparison of PS-QPSK and LDPC-coded PM-QPSK with equal spectral efficiency in WDM transmission
- 2014
-
In: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964035-
-
Conference paper (peer-reviewed)abstract
- We compare QPSK with a rate 0.75 LDPC-code and PS-QPSK, which have the same spectral efficiency, in long-haul WDM transmission. We show that LDPC-coded PM-QPSK can achieve up to 98% increased transmission distance over uncoded PS-QPSK at BER = 10-3.
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| 13. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Frequency and polarization switched QPSK
- 2013
-
In: 39th European Conference and Exhibition on Optical Communication, ECOC 2013; London; United Kingdom; 22 September 2013 through 26 September 2013. - : Institution of Engineering and Technology. - 9781849197595 ; :622 CP, s. 816-818
-
Conference paper (peer-reviewed)abstract
- We propose 8-dimensional biorthogonal modulation as a format with 3 dB increased asymptotic power efficiency over PM-QPSK. We demonstrate one possible experimental implementation of this format based on frequency and polarization switching and compare with dual-carrier PM-QPSK and PS-QPSK.
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| 14. |
- Eriksson, Tobias, 1986, et al.
(author)
-
K-Over-L Multidimensional Position Modulation
- 2014
-
In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 32:12, s. 2254-2262
-
Journal article (peer-reviewed)abstract
- We analyze a family of modulation formats based on multidimensional position modulation (MDPM) with multiple pulses per frame (K-over-L-MDPM) in combination with quadrature phase shift keying (QPSK), polarization multiplexed QPSK (PM-QPSK) and polarization-switched QPSK (PS-QPSK) for coherent communication systems. MDPM is a generalization of pulse position modulation where different pulse slots can be realized by time slots, polarization states, frequencies, modes of multimode fibers, cores in multicore fibers or a combination of these. We show that by using K-over-L-MDPM with QPSK, it is possible to simultaneously increase both the spectral efficiency and the asymptotic power efficiency over QPSK. We also identify K-ary inverse-MDPM (KiMDPM-QPSK) as the special case of K-over(K -1)-MDPM and show that 4iMDPM-QPSK has a 1.25 dB increased asymptotic power efficiency over QPSK with a maintained spectral efficiency.
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| 15. |
- Häger, Christian, 1986, et al.
(author)
-
A Low-Complexity Detector for Memoryless Polarization-Multiplexed Fiber-Optical Channels
- 2014
-
In: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 18:2, s. 368-371
-
Journal article (peer-reviewed)abstract
- A low-complexity detector is introduced for polarization-multiplexed M-ary phase shift keying modulation in a fiber-optical channel impaired by nonlinear phase noise, generalizing a previous result by Lau and Kahn for single-polarization signals. The proposed detector uses phase compensation based on both received signal amplitudes in conjunction with simple straight-line rather than four-dimensional maximum-likelihood decision boundaries.
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| 16. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(author)
-
Extending Digital Backpropagation to Account for Noise
- 2013
-
In: Proc. of 39th European Conference and Exhibition on Optical Communication (ECOC 2013). - : Institution of Engineering and Technology. - 9781849197595 ; :622 CP, s. We.3.C.4-
-
Conference paper (peer-reviewed)abstract
- We propose a maximum a posteriori-based scheme that extends digital backpropagation (DBP) by accounting for the nonlinear signal-noise interaction. With periodic dispersion compensation we find up to 20% reach improvement over DBP. For uncompensated links DBP is close to optimal.
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| 17. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(author)
-
On Maximum Likelihood Sequence Detectors for Single-channel Coherent Optical Communications
- 2014
-
In: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964134-
-
Conference paper (peer-reviewed)abstract
- Two different detectors that account for the nonlinear signal–noise interaction in a single channel coherent optical link are compared. The results indicate that accounting for the correlation between the samples leads to improved performance over stochastic digital backpropagation.
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| 18. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(author)
-
Stochastic Digital Backpropagation
- 2014
-
In: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 62:11, s. 3956-3968
-
Journal article (peer-reviewed)abstract
- In this paper, we propose a novel detector for single-channel long-haul coherent optical communications, termedstochastic digital backpropagation (SDBP), which takes into account noise from the optical amplifiers in addition to handling deterministic linear and nonlinear impairments. We discuss the design approach behind this detector, which is based on the maximum a posteriori (MAP) principle. As closed-form expressions of the MAP detector are not tractable for coherent optical transmission, we employ the framework of Bayesian graphical models, which allows a numerical evaluation of the proposed detector. Through simulations, we observe that by accounting for nonlinear signal–noise interactions, we achieve a significant improvement in system reach with SDBP over digital backpropagation (DBP) for systems with periodic inlineoptical dispersion compensation. In uncompensated links withhigh symbol rates, the performance difference in terms of system reach for SDBP over DBP is small. In the absence of noise, the proposed detector is equivalent to the well-known DBP detector.
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| 19. |
- Jiang, Nan, et al.
(author)
-
Stochastic Backpropagation for Coherent Optical Communications
- 2011
-
In: European Conference and Exposition on Optical Communications, ECOC. - Washington, D.C. : OSA. - 2162-2701. - 9781557529312 - 9781557529312
-
Conference paper (peer-reviewed)abstract
- We present stochastic backpropagation, a novel maximum a posteriori detection method for coherent optical communication. The proposed detector is shown to outperform conventional backpropagation in a scenario where nonlinear phase noise is the dominant impairment.
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| 20. |
- Johannisson, Pontus, 1976, et al.
(author)
-
A Blind Phase Stabilization Algorithm for Parallel Coherent Receivers
- 2011
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:24, s. 3737-3743
-
Journal article (peer-reviewed)abstract
- The impact from phase drifts in the different branches of parallel coherent receivers is investigated and it is shown how the spectrum is broadened when the receiver branches are not phase stabilized. Based on this, we propose a blind algorithm for compensating these phase drifts in digital signal processing by minimization of the spectral width. The algorithm performance is then evaluated by numerical simulations of quadrature phase-shift keying data using return-to-zero modulation. It is found that the algorithm is capable of identifying the phases with sufficient accuracy to make the residual effect of the phase mismatches negligible compared to the signal distortion by noise at a bit error rate of 0.001.
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| 21. |
- Johannisson, Pontus, 1976, et al.
(author)
-
A Modified CMA for PS-QPSK
- 2011
-
In: Advanced Photonics, Signal Processing in Photonic Communications. - Washington, D.C. : OSA. - 9781557529138 - 9781557529138
-
Conference paper (peer-reviewed)abstract
- A modified constant modulus algorithm (CMA) is presented that allows polarization demultiplexing of polarization-switched QPSK. The suggested algorithm has been found to work well on both numerical and experimental data.
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| 22. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Cancellation of Nonlinear Phase Distortion in Self-Homodyne Coherent Systems
- 2010
-
In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:11, s. 802-804
-
Journal article (peer-reviewed)abstract
- Using the self-homodyne detection scheme it is possible to compensate for the nonlinear phase distortion that, if left uncompensated, would distort the received constellation diagram. The suggested compensation method is evaluated using numerical simulations and validated in an experiment.
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| 23. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Convergence Comparison of CMA and ICA for Blind Polarization Demultiplexing of QPSK and 16-QAM Signals
- 2010
-
In: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352
-
Conference paper (peer-reviewed)abstract
- Two algorithms for blind polarization demultiplexing, based on the constant modulus criterion and independent component analysis, are compared. It is found that the latter converges significantly faster to within a given SNR penalty tolerance.
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| 24. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Convergence Comparison of the CMA and ICA for Blind Polarization Demultiplexing
- 2011
-
In: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 3:6, s. 493-501
-
Journal article (peer-reviewed)abstract
- An algorithm based on independent component analysis for blind polarization demultiplexing in a coherent transmission system is presented. A comparison with the constant modulus algorithm in terms of the convergence properties is performed, and it is found that the suggested algorithm has a significantly faster convergence rate and does not have any singularity problems. We also demonstrate that the algorithm convergence is strongly dependent on the choice of starting condition and show how this can be exploited to increase the convergence rate.
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| 25. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Four-Dimensional Modulation Formats for Long-Haul Transmission
- 2014
-
In: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886527-
-
Conference paper (peer-reviewed)abstract
- A number of four-dimensional modulation formats are described theoretically and from an implementation point of view. The requirements for digital signal processing and the trade-off between spectral efficiency and receiver sensitivity is discussed.
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| 26. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Modeling of Nonlinear Signal Distortion in Fiber-Optic Networks
- 2014
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 32:23, s. 3942-3950
-
Journal article (peer-reviewed)abstract
- A low-complexity model for signal quality prediction in a nonlinear fiber-optic network is developed. The model, which builds on the Gaussian noise model, takes into account the signal degradation caused by a combination of chromatic dispersion, nonlinear signal distortion, and amplifier noise. The center frequencies, bandwidths, and transmit powers can be chosen independently for each channel, which makes the model suitable for analysis and optimization of resource allocation and routing in large-scale optical networks applying flexible-grid wavelength-division multiplexing.
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| 27. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Modified constant modulus algorithm for polarization-switched QPSK
- 2011
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7734-7741
-
Journal article (peer-reviewed)abstract
- A modified constant modulus algorithm (CMA) is presentedthat allows polarization demultiplexing and equalization of polarizationswitchedQPSK. An implementation is suggested that allows easy switchingbetween the traditional and the modified CMA. Using numerical simulations,the suggested algorithm is shown to have similar performance asCMA has for polarization-multiplexed QPSK.
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| 28. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Perturbation Analysis of Nonlinear Propagation in a Strongly Dispersive Optical Communication System
- 2013
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 31:8, s. 1273-1282
-
Journal article (peer-reviewed)abstract
- We discuss an analytical model that predicts the impact of the Kerr nonlinearity in optical communication systems when the signal spectrum is wide and the accumulated dispersion during propagation is large. A detailed derivation of this model is given for a generalized system by means of a perturbation analysis of the Manakov equation with attenuation, gain, and third order dispersion included. As in the case with previous studies, three simplifying assumptions are necessary. These are that (i) the nonlinearity is weak, (ii) the input signal is of a given specific form, and (iii) the signal-noise interaction can be neglected. Under these assumptions, the result is found exactly. We also discuss the accuracy of the analytical result and show that third order dispersion has a small impact in practice.
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| 29. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Practical Detection Schemes for Power Efficient Modulation Formats
- 2013
-
In: Optics InfoBase Conference Papers. - 2162-2701. - 9781557529817
-
Conference paper (peer-reviewed)abstract
- We discuss the detection process for a selection of power efficient formats. The receiver subsystems of dynamic equalization, phase estimation, and data detection are described with emphasis on the case with differential encoding.
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| 30. |
- Karout, Johnny, 1985, et al.
(author)
-
CMA Misconvergence in Coherent Optical Communication for Signals Generated from a Single PRBS
- 2011
-
In: Wireless & optical communications conference, New Jersey, 15-16 April 2011. - 9781457704543
-
Conference paper (peer-reviewed)abstract
- In the experimental study of modulators for coherent optical communications, it is common to generate multilevel signals using a single pseudo-random binary sequence. This simple experimental realization leads to symbol correlation. When modulators are studied in combination with adaptive receiver algorithms that rely on independent data, misconvergence may result. In this contribution, we investigate the impact of such correlation on a standard blind equalization method and provide guidelines to avoid misconvergence. Our results indicate that care needs to be taken when using a single PRBS sequence and that decorrelation delays must be chosen appropriately. We present simulation and theoretical results for 16-QAM, and show how our results can be applied to other multi-level constellations.
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| 31. |
- Lu, Guo-Wei, 1976, et al.
(author)
-
40-Gbaud 16-QAM transmitter using tandem IQ modulators with binary driving electronic signals
- 2010
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 18:22, s. 23062-23069
-
Journal article (peer-reviewed)abstract
- We propose a novel 16-quadrature amplitude modulation (QAM) transmitter based on two cascaded IQ modulators driven by four separate binary electrical signals. The proposed 16-QAM transmitter features scalable configuration and stable performance with simple bias-control. Generation of 16-QAM signals at 40 Gbaud is experimentally demonstrated for the first time and visualized with a high speed constellation analyzer. The proposed modulator is also compared to two other schemes. We investigate the modulator bandwidth requirements and tolerance to accumulated chromatic dispersion through numerical simulations, and the minimum theoretical insertion attenuation is calculated analytically.
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| 32. |
- Nafta, A., et al.
(author)
-
Blind Equalization in Optical Communications Using Independent Component Analysis
- 2013
-
In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 31:12, s. 2043-2049
-
Journal article (peer-reviewed)abstract
- We propose a multi-tap independent component analysis (ICA) scheme for blind equalization and phase recovery in coherent optical communication systems. The proposed algorithm is described and evaluated in the cases of QPSK and 16-QAM transmission. Comparison with CMA equalization shows similar performance in the case of QPSK and an advantage for the ICA equalizer in the case of 16-QAM. The equalization scheme was evaluated in a multi-span optical communications system impaired by both polarization mode dispersion (PMD) and polarization dependent loss (PDL).
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| 33. |
- Peng, Fangrong, 1986, et al.
(author)
-
Operational Regime of Symbol-by-Symbol Phase Noise Estimation for POLMUX 16-QAM
- 2010
-
In: Proceedings of European Conference on Optical Communication, ECOC, Turin, Italy, September 19-23, 2010. - 9781424485352
-
Conference paper (peer-reviewed)abstract
- A symbol-by-symbol phase noise estimation algorithm for polarization-multiplexed 16-QAM is evaluated. We found that it can cope with laser linewidths of up to 2.2 MHz in high SNR regimes, at 112 Gbit/s.
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| 34. |
- Sen, Debarati, 1975, et al.
(author)
-
MCRB for Timing and Phase Offset for Low-Rate Optical Communication with Self-Phase Modulation
- 2013
-
In: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2558 .- 1089-7798. ; 17:5, s. 1004-1007
-
Journal article (peer-reviewed)abstract
- We derive the modified Cramer-Rao bound (MCRB) for symbol timing and phase offset estimation in the presence of nonlinear self-phase modulation (SPM) in a dispersion compensated long-haul optical fiber link with coherent detection at data rates below 10 Gigabaud. In the presence of a low-pass filter at the receiver front-end, we find that SPM degrades the MCRB. Moreover, depending on the pulse shape, SPM induces underdamped oscillation on the bounds.
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| 35. |
- Shuchang, Yao, 1988, et al.
(author)
-
Spectrum Superposition Based Chromatic Dispersion Estimation for Digital Coherent Receivers
- 2014
-
In: European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. P.3.17-
-
Conference paper (peer-reviewed)abstract
- We propose and experimentally demonstrate a fast blind CD estimation method based on signal spectrum superposition. With only 4096 samples, a maximum estimation error of 0.25% of the accumulated CD for 7 x 112 Gbps DP-QPSK WDM signal is verified.
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| 36. |
- Sjödin, Martin E, 1983, et al.
(author)
-
Comparison of 128-SP-QAM with PM-16-QAM
- 2012
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 20:8, s. 8356-8366
-
Journal article (peer-reviewed)abstract
- In this paper we investigate an interesting modulation format for fiber optic communications, set-partitioning 128 polarization-multiplexed 16-QAM (128-SP-QAM), which consists of the symbols with even parity from the symbol alphabet of polarization-multiplexed 16-QAM (PM-16-QAM). We compare 128-SP-QAM and PM-16-QAM using numerical simulations in long-haul transmission scenarios at bit rates of 112 Gbit/s and 224 Gbit/s, and at the same symbol rates (14 and 28 Gbaud). The transmission link is made up of standard single-mode fiber with 60, 80 or 100 km amplifier spacing and both single channel and WDM transmission (25- and 50 GHz-spaced) is investigated. The results show that 128-SP-QAM achieves more than 40% increase in transmission reach compared to PM-16-QAM at the same data rate for all cases studied for a bit error rate of 10−3. In addition, we find that in single channel transmission there is, as expected, an advantage in terms of transmission distance when using a data rate of 112 Gbit/s as compared to 224 Gbit/s. However, when comparing the two different WDM systems with the same aggregate data rates, the reach is similar due to the smaller impact of nonlinear crosstalk between the WDM channels in the systems with 50 GHz spacing. We also discuss decoding and phase estimation of 128-SP-QAM and implement differential coding, which avoids error bursts due to cycle slips in the phase estimation. Simulations including laser phase noise show that the phase noise tolerance is similar for the two formats, with 0.5 dB OSNR penalty compared to the case with zero phase noise for a laser linewidth to symbol rate ratio of 10−4.
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| 37. |
- Sjödin, Martin E, 1983, et al.
(author)
-
Comparison of polarization-switched QPSK and polarization-multiplexed QPSK at 30 Gbit/s
- 2011
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7839-7846
-
Journal article (peer-reviewed)abstract
- We present the first experimental results for polarization-switched QPSK (PS-QPSK) and make a comparison with polarization-multiplexed QPSK. Our measurements confirm the predicted sensitivity advantage of PS-QPSK. We have also studied the single channel performance after transmission over 300 km and support the results with numerical simulations. It is shown that the two modulation formats have similar nonlinear tolerance and that optical dispersion compensation outperforms compensation with digital signal processing in the single channel case. Finally, we propose a novel transmitter for PS-QPSK based on an IQ modulator and two amplitude modulators driven in a push-pull configuration.
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| 38. |
- Sjödin, Martin E, 1983, et al.
(author)
-
Comparison of PS-QPSK and PM-QPSK at Different Data Rates in a 25 GHz-spaced WDM System
- 2012
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In: Optical Fiber Communication Conference, OFC 2012, Los Angeles, United States, 4-8 March 2012. - 2162-2701. - 9781557529381
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Conference paper (peer-reviewed)abstract
- We compare polarization-switched QPSK and polarization-multiplexed QPSK in a WDM system with 25 GHz channel spacing. We investigate experimentally the transmission distance as a function of the data rate for both modulation formats.
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| 39. |
- Sjödin, Martin E, 1983, et al.
(author)
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Filter Optimization for Self-Homodyne Coherent WDM Systems using Interleaved Polarization Division Multiplexing
- 2011
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:9, s. 1219 - 1226
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Journal article (peer-reviewed)abstract
- We examine the impact of filtering on self-homodynecoherent WDM systems using the interleaved polarization division multiplexing scheme. To investigate the performance limit and to provide more insight into previously obtained experimental results we perform numerical simulations in which different filter shapes and filter bandwidths are used. It is shown that with proper prefiltering of the data and filtering of the pilot tone in the receiver, performance can approach that of an intradyne system, which would make it possible to implement coherent systems with high spectral efficiency without any digitalsignal processing in the receiver.
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| 40. |
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| 41. |
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| 42. |
- Sjödin, Martin E, 1983, et al.
(author)
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Measurement of the Phase Noise Tracking Capability of a Digital Coherent Receiver
- 2011
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In: European Conference and Exposition on Optical Communications, ECOC 2011; Geneva; Switzerland; 18 September 2011 through 22 September 2011. - 2162-2701. - 9781557529312
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Conference paper (peer-reviewed)abstract
- We present a method to evaluate the phase noise tracking performance of a digital coherent receiver. Measurements of the phase error variance of QPSK at different symbol rates are presented for two different algorithms.
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| 43. |
- Sjödin, Martin E, 1983, et al.
(author)
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OSNR Requirements for Self-Homodyne Coherent Systems
- 2010
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:2, s. 91-93
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Journal article (peer-reviewed)abstract
- The OSNR requirements for a self-homodyne coherentsystem are investigated theoretically and experimentallyand compared to intradyne detection. The beneficial effectof band-pass filtering of the co-propagating local oscillator is demonstrated and it is shown that the performance limit for self-homodyne and intradyne systems becomes equal as the filter bandwidth is made small.
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| 44. |
- Sjödin, Martin E, 1983, et al.
(author)
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Transmission of PM-QPSK and PS-QPSK with different fiber span lengths
- 2012
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In: Optics Express. - 1094-4087 .- 1094-4087. ; 20:7, s. 7544-7554
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Journal article (peer-reviewed)abstract
- We perform experimental and numerical investigations of the transmission reach of polarization-switched QPSK (PS-QPSK) and polarization-multiplexed QPSK (PM-QPSK) for three different fiber span lengths: 83, 111 and 136 km. In the experimental comparison we investigate the performance of PS-QPSK at 20 Gbaud and PM-QPSK at the same bit rate (60 Gbit/s) and at the same symbol rate, both the single channel case and a WDM system with 9 channels on a 50 GHz grid. We show that PS-QPSK gives significant benefits in transmission reach for all span lengths. Compared to PM-QPSK, use of PS-QPSK increases the reach with more than 41 % for the same symbol rate and 21 % for the same bit rate. In the numerical simulations we use the same data rates as in the experiment. The simulation results agree well with the experimental findings, but the transmission reach is longer due to the absence of various non-ideal effects and higher back-to-back sensitivity. Apart from using data coded in the absolute phase in the simulations, we also investigate differentially coded PS-QPSK for the first time and compare with PM-QPSK with differential coding. The power efficiency advantage of PS-QPSK then increases with approximately 0.3 dB at a bit error rate of 10-3, resulting in a further relative transmission reach improvement over PM-QPSK. Both the experimental and the numerical results indicate that PS-QPSK has slightly higher tolerance to inter-channel nonlinear crosstalk than PM-QPSK.
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| 45. |
- Tan, Ahmet Serdar, 1982, et al.
(author)
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An ML-based Detector for Optical Communication in the Presence of Nonlinear Phase Noise
- 2011
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In: IEEE International Conference on Communications. - : IEEE. - 1550-3607. - 9781612842332 ; , s. Art. no. 5962741-
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Conference paper (peer-reviewed)abstract
- We present a closed-form maximum likelihood-based data detection algorithm for long-haul optical channels with dominant nonlinear phase noise induced by self-phase modulation. The closed-form detector is evaluated in terms of symbol error rate as a function of input power, and compared with other sub-optimal detectors as well as a non-parametric detector. We show that the performance of the detector deteriorates for high input power levels, resulting in an optimal operation region. We also provide insights into the behavior of the detector in the highly nonlinear regime.
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| 46. |
- Tan, Ahmet Serdar, 1982, et al.
(author)
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Modified Cramer-Rao Bound for Clock Recovery in the Presence of Self-Phase Modulation
- 2012
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In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 30:16, s. 2556-2562
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Journal article (peer-reviewed)abstract
- We investigate the effect of nonlinear self-phase modulation (SPM) on clock recovery in long-haul coherent optical communication systems with low to moderate baud rates. We consider dual-polarization, multilevel quadrature amplitude modulation, and evaluate conventional timing estimators as well as a modified Cramer-Rao bound. As the latter is hard to compute in the presence of nonlinear channel impairments, we derive an approximate closed-form expression. Contrary to linear channel impairments, the nonlinear impairments can degrade the performance for higher input powers. In addition, the bounds exhibit oscillatory behavior due to the oscillations in the signal spectrum in the presence of SPM.
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| 47. |
- Tan, Ahmet Serdar, 1982, et al.
(author)
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The Impact of Self-Phase Modulation on Digital Clock Recovery in Coherent Optical Communication
- 2010
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In: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352
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Conference paper (peer-reviewed)abstract
- The impact of self-phase modulation on the estimation error variance of digital clock recovery schemes for coherent 16-QAM dual-polarization systems is investigated. The error variance increases severely compared to the linear case and the theoretical bounds.
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| 48. |
- Tipsuwannakul, Ekawit, 1982, et al.
(author)
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Performance Comparison of Differential 8-Ary Modulation Formats in High-Speed Optical Transmission Systems
- 2011
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:19, s. 2954-2962
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Journal article (peer-reviewed)abstract
- This paper presents back-to-back and transmission performance comparisons between single-polarization 120 Gbit/s RZ-DQP-ASK and RZ-D8PSK formats in a single-wavelength system. In the back-to-back configuration, we determine the OSNR requirements of the two formats and compare the results with those obtained analytically and numerically. In the transmission experiments, we examine signal constellations to quantify the significance of intra-channel fiber nonlinearities and investigate the BER performance of the two formats over different reaches (up to 480 km). The results show that the performance of DQP-ASK is superior to D8PSK in back-to-back configuration but is inferior over long distances.
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| 49. |
- Wymeersch, Henk, 1976, et al.
(author)
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Maximum Likelihood-Based Blind Dispersion Estimation for Coherent Optical Communication
- 2012
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 30:18, s. 2976-2982
-
Journal article (peer-reviewed)abstract
- Starting from the maximum likelihood criterion, we derive a novel blind chromatic dispersion (CD) estimation method in the presence of unknown data, propagation delay, polarization state, and differential group delay. By using CD estimation, electronic dispersion compensation (EDC) can be carried out without prior knowledge about the amount of accumulated CD. This adds flexibility to the EDC, which may prove valuable in reconfigurable optical networks. Using numerical simulations, we compare the suggested algorithm with a well-known CD estimation algorithm based on the constant modulus algorithm. We find that the proposed algorithm has better estimation performance and lower computational complexity. Furthermore, the impact of differential group delay is small. The derivation of the algorithm also shows the close connection between CD estimation, clock recovery, and polarization effects.
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| 50. |
- Zakrisson, Daniel, 1986, et al.
(author)
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CMA-Based CD and DGD Estimation in Presence of Experimental Higher Order PMD
- 2014
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In: European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. P.3.16-
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Conference paper (peer-reviewed)abstract
- We evaluate 3 methods for CD estimation using CMA filter tap coefficients. The performance of these methods are evaluated with respect to their accuracy and range. We also experimentally evaluate the CD estimation performance in presence of higher order PMD.
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