| 1. |
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| 2. |
- Ahmad, Tauseef, 1986, et al.
(författare)
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Methodology for Power-Aware Coherent Receiver Design
- 2013
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; , s. SPT4D.4-
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Konferensbidrag (refereegranskat)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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| 3. |
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| 4. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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A Discrete-Time Model for Uncompensated Single-Channel Fiber-Optical Links
- 2012
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 60:11, s. 3440-3450
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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A novel multilevel coded modulation scheme for fiber optical channel with nonlinear phase noise
- 2010
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Ingår i: Proc. Global Communications Conference, Miami, FL. - 9781424456383
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Konferensbidrag (refereegranskat)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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| 6. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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On nonlinearly-induced noise in single-channel optical links with digital backpropagation
- 2013
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:22, s. 26376-26386
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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Signal Statistics in Fiber-Optical Channels with Polarization Multiplexing and Self-Phase Modulation
- 2011
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:16, s. 2379 - 2386
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Beygi, Lotfollah, 1977, et al.
(författare)
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The Limits of Digital Backpropagation in Nonlinear Coherent Fiber-Optical Links
- 2012
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Ingår i: 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-
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Konferensbidrag (refereegranskat)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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| 9. |
- Björkholm, P., et al.
(författare)
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Navigation in vehicle crash test using MEMS-based IMU
- 2010
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Ingår i: IEEE PLANS, Position Location and Navigation Symposium. - 9781424450367 ; , s. 27-31
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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| 10. |
- Borkowski, R., et al.
(författare)
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Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers
- 2014
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Ingår i: Optical Fiber Technology. - : Elsevier BV. - 1095-9912 .- 1068-5200. ; 20:2, s. 158-162
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Tidskriftsartikel (refereegranskat)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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| 11. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Modulation Format Independent Joint Polarization and Phase Tracking for Coherent Receivers
- 2016
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 13:14, s. 3354-3364
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Tidskriftsartikel (refereegranskat)abstract
- © 1983-2012 IEEE. The state of polarization and the carrier phase drift dynamically during transmission in a random fashion in coherent optical fiber communications. The typical digital signal processing solution to mitigate these impairments consists of two separate blocks that track each phenomenon independently. Such algorithms have been developed without taking into account mathematical models describing the impairments. We study a blind, model-based tracking algorithm to compensate for these impairments. The algorithm dynamically recovers the carrier phase and state of polarization jointly for an arbitrary modulation format. Simulation results show the effectiveness of the proposed algorithm, having a fast convergence rate and an excellent tolerance to phase noise and dynamic drift of the polarization at low complexity, which make the algorithm a strong candidate for future optical systems.
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| 12. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Polarization Drift Channel Model for Coherent Fibre-Optic Systems
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6, s. 21217-
-
Tidskriftsartikel (refereegranskat)abstract
- A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincare sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.
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| 13. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Temporal stochastic channel model for absolute polarization state and polarization-mode dispersion
- 2017
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Ingår i: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings. - 2162-2701. - 9781943580231
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Konferensbidrag (refereegranskat)abstract
- We propose and validate a discrete-time channel model for the temporal drift of the absolute polarization state and polarization-mode dispersion for coherent fiber optic systems. The model can be used in simulations to test and develop DSP for coherent receivers.
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| 14. |
- Eliasson, Henrik, 1985, et al.
(författare)
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Mitigation of nonlinearities using conjugate data repetition
- 2015
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 23:3, s. 2392-2402
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate a time-domain implementation of generalized phase-conjugated twin waves which we call conjugate data repetition. A theory based on time-domain perturbation analysis explaining the mitigation of nonlinear effects is provided, and the concept is evaluated using numerical simulations. Compared to PM-QPSK at the same channel bit rate, the single-channel transmission reach in a conventional system with standard single-mode fiber of conjugate data repetition-QPSK is increased by approximately a factor of 2.
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| 15. |
- Eliasson, Henrik, 1985, et al.
(författare)
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Transmitter mask testing for 28 GBaud PM-QPSK
- 2013
-
Ingår i: Optical Communication (ECOC 2013), 39th European Conference and Exhibition on. - : Institution of Engineering and Technology. - 9781849197595 ; , s. 282 - 284
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Konferensbidrag (refereegranskat)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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| 16. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Achievable Rates Comparison for Phase-Conjugated Twin-Waves and PM-QPSK
- 2016
-
Ingår i: 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016, Niigata, Japan, 3-7 July 2016. - 9784885523052 ; , s. TuB3-3
-
Konferensbidrag (refereegranskat)abstract
- Phase-conjugated twin-waves (PCTW)-QPSK is experimentally compared to PM-QPSK in terms of achievable information rate for bit-wise decoders. For typical long-haul transmission distances, PM-QPSK with soft-decision FEC achieves significantly higher spectral efficiency than PCTW-QPSK.
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| 17. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Biorthogonal modulation in 8 dimensions experimentally implemented as 2PPM-PS-QPSK
- 2014
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Ingår i: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886984-
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Konferensbidrag (refereegranskat)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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| 18. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Comparison of 128-SP-QAM and PM-16QAM in long-haul WDM transmission
- 2013
-
Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 21:16, s. 19269-19279
-
Tidskriftsartikel (refereegranskat)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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| 19. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Experimental comparison of PS-QPSK and LDPC-coded PM-QPSK with equal spectral efficiency in WDM transmission
- 2014
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Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964035-
-
Konferensbidrag (refereegranskat)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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| 20. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Frequency and polarization switched QPSK
- 2013
-
Ingår i: 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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Konferensbidrag (refereegranskat)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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| 21. |
- Eriksson, Tobias, 1986, et al.
(författare)
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K-Over-L Multidimensional Position Modulation
- 2014
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 32:12, s. 2254-2262
-
Tidskriftsartikel (refereegranskat)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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| 22. |
- Fehenberger, Tobias, et al.
(författare)
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On the impact of carrier phase estimation on phase correlations in coherent fiber transmission
- 2015
-
Ingår i: 2015 Tyrrhenian International Workshop on Digital Communications, TIWDC 2015. - 9781467392600 ; , s. 35-38
-
Konferensbidrag (refereegranskat)abstract
- Carrier phase estimation (CPE) is an integral part of the digital signal processing (DSP) of coherent optical communication systems as it compensates laser phase noise (LPN) introduced by free-running transmitter and local oscillating (LO) lasers. Nonlinear interactions during propagation are another source of correlated phase noise. In this paper, we show through simulations and in experiments that blind decision-directed (DD) CPE with regular block lengths removes a large portion of the memory. This makes it virtually impossible in practice to quantify correlations that come from propagation effects, or to obtain rate gains by exploiting the nonlinear phase noise (NLPN). Larger CPE block lengths leave the memory partly intact. This, however, comes at the expense of reduced information rates. We are able to fully recover this rate loss in simulations by using idealized processing of phase distortions. In experiments with full DSP, an almost full rate recovery is reported.
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| 23. |
- Forzati, Marco, et al.
(författare)
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Reduction of intra-channel four-wave mixing using the alternate-phase RZ modulation format
- 2002
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 14:9
-
Tidskriftsartikel (refereegranskat)abstract
- —The authors propose a modulation format in which the phase of the signal pulses alternates, in order to reduce the intrachannel four-wave mixing. They demonstrate numerically that the performance of a 40-Gb/s transmission link can be substantially improved.
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| 24. |
- Fougstedt, Christoffer, 1990, et al.
(författare)
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Dynamic Equalizer Power Dissipation Optimization
- 2016
-
Ingår i: 2016 Optical Fiber Communications Conference and Exhibition. - 9781943580071
-
Konferensbidrag (refereegranskat)abstract
- We investigate power dissipation/performance trade-off in a 28nm ASIC implementation of a parallel dynamic equalizer. Over 50% dissipation improvement is possible by sample pruning during filter updates, with only minor tracking-performance reduction.
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| 25. |
- Fougstedt, Christoffer, 1990, et al.
(författare)
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Filter Implementation for Power-Efficient Chromatic Dispersion Compensation
- 2018
-
Ingår i: IEEE Photonics Journal. - 1943-0655. ; 10:4
-
Tidskriftsartikel (refereegranskat)abstract
- Chromatic dispersion (CD) compensation in coherent fiber-optic systems represents a very significant DSP block in terms of power dissipation. Since spectrally efficient coherent systems are expected to find a wider deployment in systems shorter than long haul, it becomes relevant to investigate filter implementation aspects of CD compensation in the context of systems with low-to-moderate amounts of accumulated dispersion. The investigation we perform in this paper has an emphasis on implementation aspects such as power dissipation and area usage, it deals with both time-domain and frequency-domain CD compensations, and it considers both A/D-conversion quantization and fixed-point filter design aspects. To enable an accurate analysis on power dissipation and chip area, the evaluated filters are implemented in a 28-nm fully depleted silicon-on-insulator (FD-SOI) process technology. We show that an optimization of the filter response that takes pulse shaping into account can significantly reduce power dissipation and area usage of time-domain implementations, making them a viable alternative to frequency-domain implementations.
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| 26. |
- Fougstedt, Christoffer, 1990, et al.
(författare)
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Power-Efficient Time-Domain Dispersion Compensation Using Optimized FIR Filter Implementation
- 2015
-
Ingår i: Signal Processing in Photonics Communications, SPPCom 2015; Boston, MA; United States; 27 June 2015-1 July 2015. - 9781557520005 ; , s. SpT3D.3-
-
Konferensbidrag (refereegranskat)abstract
- We investigate fixed-point aspects and time-domain ASIC implementations of CD compensation. An optimized implementation gives significant power dissipation reduction for short links, with further reduction if pulse shaping is considered.
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| 27. |
- Geréb, Gabor, et al.
(författare)
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Sensor Platform for Low-Power Underwater Monitoring using Hydroacoustic Communication
- 2021
-
Ingår i: 2021 Smart Systems Integration (SSI).
-
Konferensbidrag (refereegranskat)abstract
- The development of a compact, battery-powered sensor platform intended for underwater applications and using hydroacoustic communication is reported. The design and manufacturing of the device is described with emphasis on the method used to monitor and reduce the current consumption. The devices have been encapsulated in epoxy and evaluated under field conditions, which showed that the system is usable in its current form. In addition to hardware improvements, e.g., in order to increase battery lifetime, the next generation of the system will implement forward error correction and improved receiver signal processing to reduce the impact of signal reflections.
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| 28. |
- Häger, Christian, 1986, et al.
(författare)
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A Low-Complexity Detector for Memoryless Polarization-Multiplexed Fiber-Optical Channels
- 2014
-
Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 18:2, s. 368-371
-
Tidskriftsartikel (refereegranskat)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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| 29. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(författare)
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Extending Digital Backpropagation to Account for Noise
- 2013
-
Ingår i: 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-
-
Konferensbidrag (refereegranskat)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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| 30. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(författare)
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Improved Lower Bounds on Mutual Information Accounting for Nonlinear Signal--Noise Interaction
- 2018
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 36:22, s. 5152-5159
-
Tidskriftsartikel (refereegranskat)abstract
- In fiber-optic communications, evaluation of mutual information (MI) is still an open issue due to the unavailability of an exact and mathematically tractable channel model. Traditionally, lower bounds on MI are computed by approximating the (original) channel with an auxiliary forward channel. In this paper, lower bounds are computed using an auxiliary backward channel, which has not been previously considered in the context of fiber-optic communications. Distributions obtained through two variations of the stochastic digital backpropagation (SDBP) algorithm are used as auxiliary backward channels and these bounds are compared with bounds obtained through the conventional digital backpropagation (DBP). Through simulations, higher information rates were achieved with SDBP, which can be explained by the ability of SDBP to account for nonlinear signal--noise interactions
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| 31. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(författare)
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On Maximum Likelihood Sequence Detectors for Single-channel Coherent Optical Communications
- 2014
-
Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964134-
-
Konferensbidrag (refereegranskat)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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| 32. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(författare)
-
Stochastic Digital Backpropagation
- 2014
-
Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 62:11, s. 3956-3968
-
Tidskriftsartikel (refereegranskat)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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| 33. |
- Irukulapati, Naga Vishnukanth, 1987, et al.
(författare)
-
Stochastic Digital Backpropagation with Residual Memory Compensation
- 2016
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 34:2, s. 566-572
-
Tidskriftsartikel (refereegranskat)abstract
- Stochastic digital backpropagation (SDBP) is an extension of digital backpropagation (DBP) and is based on the maximum a posteriori principle. SDBP takes into account noise from the optical amplifiers in addition to handling deterministic linear and nonlinear impairments. The decisions in SDBP are taken on a symbol-by-symbol (SBS) basis, ignoring any residual memory, which may be present due to non-optimal processing in SDBP. In this paper, we extend SDBP to account for memory between symbols. In particular, two different methods are proposed: a Viterbi algorithm (VA) and a decision directed approach. Symbol error rate (SER) for memory-based SDBP is significantly lower than the previously proposed SBS-SDBP. For inline dispersion-managed links, the VA-SDBP has up to 10 and 14 times lower SER than DBP for QPSK and 16-QAM, respectively.
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| 34. |
- Jiang, Nan, et al.
(författare)
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Stochastic Backpropagation for Coherent Optical Communications
- 2011
-
Ingår i: European Conference and Exposition on Optical Communications, ECOC. - Washington, D.C. : OSA. - 2162-2701. - 9781557529312 - 9781557529312
-
Konferensbidrag (refereegranskat)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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| 35. |
- Johannisson, Pontus, 1976, et al.
(författare)
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A Blind Phase Stabilization Algorithm for Parallel Coherent Receivers
- 2011
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:24, s. 3737-3743
-
Tidskriftsartikel (refereegranskat)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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| 36. |
- Johannisson, Pontus, 1976, et al.
(författare)
-
A Modified CMA for PS-QPSK
- 2011
-
Ingår i: Advanced Photonics, Signal Processing in Photonic Communications. - Washington, D.C. : OSA. - 9781557529138 - 9781557529138
-
Konferensbidrag (refereegranskat)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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| 37. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Cancellation of Nonlinear Phase Distortion in Self-Homodyne Coherent Systems
- 2010
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 22:11, s. 802-804
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Tidskriftsartikel (refereegranskat)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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| 38. |
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| 39. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Convergence Comparison of CMA and ICA for Blind Polarization Demultiplexing of QPSK and 16-QAM Signals
- 2010
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Ingår i: Proceedings of European Conference on Optical Communication, ECOC 2010, Turin, Italy, September 19-23, 2010. - 9781424485352
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Konferensbidrag (refereegranskat)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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| 40. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Convergence Comparison of the CMA and ICA for Blind Polarization Demultiplexing
- 2011
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 3:6, s. 493-501
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Tidskriftsartikel (refereegranskat)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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| 41. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Four-Dimensional Modulation Formats for Long-Haul Transmission
- 2014
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Ingår i: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886527-
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Konferensbidrag (refereegranskat)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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| 42. |
- Johannisson, Pontus, et al.
(författare)
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Generation and dynamics of ghost pulses in strongly dispersion-managed fiber-optic communication systems
- 2001
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Ingår i: Optics Letters. - : Optical Society of America (OSA). - 0146-9592 .- 1539-4794. ; 26:16, s. 1227-1229
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the nonlinear generation and dynamics of ghost pulses in high-speed strongly dispersion-managed fiber-optic communication systems. Particular consideration is given to the importance of system parameters for the properties of the emerging ghost pulses. Conclusions are drawn about the growth rate and the temporal position of the ghost pulses in different systems.
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| 43. |
- Johannisson, Pontus, et al.
(författare)
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Impact-driven up-conversion in piezoelectric MEMS energy harvesters with pulsed excitation
- 2018
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Ingår i: Journal of Physics. - : IOP Publishing.
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Konferensbidrag (refereegranskat)abstract
- The potential of impact-driven frequency up-conversion in a MEMS EH is evaluated using numerical simulations. The investigated design is compared to a conventional cantilever EH in terms of output power and loss rate. The upshifting can lead to significantly increased output power at a similar loss rate but as the time scale for the loss is long, the benefit is limited. This also requires an effective upshifting process. The design of the impact introduces a length scale that must be selected with excitation, gravity, and pre-stress taken into account. This makes this type of EH application-dependent as a non-optimal choice may result in low output power.
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| 44. |
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| 45. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Modeling of Nonlinear Signal Distortion in Fiber-Optic Networks
- 2014
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 32:23, s. 3942-3950
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Tidskriftsartikel (refereegranskat)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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| 46. |
- Johannisson, Pontus, 1976, et al.
(författare)
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Modified constant modulus algorithm for polarization-switched QPSK
- 2011
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:8, s. 7734-7741
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Tidskriftsartikel (refereegranskat)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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| 47. |
- Johannisson, Pontus, et al.
(författare)
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Multi-axis piezoelectric energy harvesting using MEMS components with slanted beams
- 2016
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 773:1
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Tidskriftsartikel (refereegranskat)abstract
- During the manufacturing of MEMS components, slanted beams can be produced in the etching process. We show that this can be used to produce skew motion that causes deflection of a proof mass out of the device plane also when the excitation is confined to the device plane. This allows construction of an energy harvester that uses a planar manufacturing process and produces power also with in-plane excitation. To obtain this with traditional methods it would be necessary to manufacture separate components and then mount them with their sensitive axes orthogonal to each other.
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| 48. |
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| 49. |
- Johannisson, Pontus, 1976
(författare)
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Nonlinear intrachannel distortion in high-speed optical transmission systems
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Kerr nonlinearity in optical fibres tends to generate signal distortion in dispersion-managed fibre-optic communication systems. Within a wavelength channel, the resulting intrachannel effects are timing jitter, i.e., random temporal shifting of the signal pulses, amplitude jitter, and generation of noise pulses in empty bit slots, referred to as ghost pulses. An investigation of these effects is carried out using both a variational and a perturbation analysis of the nonlinear Schrödinger equation. This allows the nonlinear interaction to be described analytically and numerical simulations are presented that support and extend the obtained results.The interaction range, i.e., the number of bit slots over which the nonlinear interaction is significant, is an important concept when designing and interpreting system simulations. Analytical and numerical results are given which allow a priori estimations valid for realistic systems. The growth rate of the nonlinear distortion has been examined in order to investigate the possibilities for suppressing the nonlinear interaction.Methods for counteracting the nonlinear effects are proposed, and special emphasis is given to the suppressive effects obtained from phase shifting of consecutive signal pulses. All-optical regeneration is discussed as an alternative method of reducing the signal distortion and in particular two types of regenerators are studied. The first type is based on nonlinear spectral widening and bandpass filtering and is suitable for return-to-zero data. The second type can reduce the phase fluctuations in differential phase-shift keying data and the analysis provides a description of an already experimentally implemented device.
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| 50. |
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