| 1. |
- Eriksson, Tobias, 1986, et al.
(author)
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Comparison of 128-SP-QAM and PM-16QAM in long-haul WDM transmission
- 2013
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In: Optics Express. - 1094-4087 .- 1094-4087. ; 21:16, s. 19269-19279
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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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| 2. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Experimental Demonstration of 128-SP-QAM in Uncompensated Long-Haul Transmission
- 2013
-
In: 2012 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013, Anaheim, 17-21 March 2013. - 9781479904570 ; , s. OTu3B.2-
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Conference paper (peer-reviewed)abstract
- We demonstrate 128-SP-QAM experimentally for the first time and compare the performance to PM-16QAM at the same symbol rate (10.5 Gbaud). We find a 1.7 dB increased sensitivity and 50% increased transmission reach over PM-16QAM.
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| 3. |
- Eriksson, Tobias, 1986, et al.
(author)
-
Frequency and polarization switched QPSK
- 2013
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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
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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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| 4. |
- Johannisson, Pontus, 1976, et al.
(author)
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A Modified CMA for PS-QPSK
- 2011
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In: Advanced Photonics, Signal Processing in Photonic Communications. - Washington, D.C. : OSA. - 9781557529138 - 9781557529138
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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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| 5. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Cancellation of Nonlinear Phase Distortion in Self-Homodyne Coherent Systems
- 2010
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:11, s. 802-804
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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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| 6. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Convergence Comparison of CMA and ICA for Blind Polarization Demultiplexing of QPSK and 16-QAM Signals
- 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
- 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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| 7. |
- 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
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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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| 8. |
- Johannisson, Pontus, 1976, et al.
(author)
-
Four-Dimensional Modulation Formats for Long-Haul Transmission
- 2014
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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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| 9. |
- 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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| 10. |
- Karout, Johnny, 1985, et al.
(author)
-
CMA Misconvergence in Coherent Optical Communication for Signals Generated from a Single PRBS
- 2011
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In: Wireless & optical communications conference, New Jersey, 15-16 April 2011. - 9781457704543
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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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