| 1. |
- Agrell, Erik, 1965, et al.
(författare)
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Influence of Behavioral Models on Multiuser Channel Capacity
- 2015
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 33:17, s. 3507-3515
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Tidskriftsartikel (refereegranskat)abstract
- In order to characterize the channel capacity of a wavelength channel in a wavelength-division multiplexed (WDM) system, statistical models are needed for the transmitted signals on the other wavelengths. For example, one could assume that the transmitters for all wavelengths are configured independently of each other, that they use the same signal power, or that they use the same modulation format. In this paper, it is shown that these so-called behavioral models have a profound impact on the single-wavelength achievable information rate. This is demonstrated by establishing, for the first time, upper and lower bounds on the maximum achievable rate under various behavioral models, for a rudimentary WDM channel model.
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| 2. |
- Czegledi, Cristian Bogdan, 1988, et al.
(författare)
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Symbol-by-Symbol Joint Polarization and Phase Tracking in Coherent Receivers
- 2015
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Ingår i: Optical Fiber Communication Conference, OFC 2015; Los Angeles Convention CenterLos Angeles; United States; 22 March 2015 through 26 March 2015. - Washington, D.C. : OSA. - 9781557529374 - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- An analytical model to describe the combined drift of the state of polarization and absolute phase is presented. To compensate for this drift, a novel, modulation format independent algorithm is proposed, which outperforms state-of-the-art algorithms.
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| 3. |
- Ebenhag, Sven-Christian, 1976, et al.
(författare)
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Two-way coherent frequency transfer in a commercial DWDM communication network in Sweden
- 2015
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Ingår i: 2015 Joint Conference of the IEEE International Frequency Control Symposium and the European Frequency and Time Forum, FCS 2015 - Proceedings. - 1075-6787. - 9781479988662 ; , s. 276-279
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Konferensbidrag (refereegranskat)abstract
- An experimental fiber link is being established between SP Technical Research Institute of Sweden in Boras and Chalmers University of Gothenburg in Sweden. The one way fiber length is about 60 km and implemented in SUNET (Swedish University Network). The aim of the project is to evaluate the signal quality when sending a stable optical frequency utilizing a wavelength in a DWDM (Dense Wavelength Division Multiplexing) system fiber pair. The experiment uses a channel in the DWDM with the wavelength of 1542.14 nm. This wavelength is within the C band and is therefore compatible with common Erbium doped amplifiers in this network. Another aim of the system is to be ultra-stable which corresponds to a stability of 1×10-13 for τ = 1 s as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) (National realization of Universal Time Coordinated within Sweden) to multiple users within the network. Measurements of an optical frequency transfer using a fiber-link based on unidirectional light signals in parallel fibers have shown promising results in a free-running setup and in a lab environment. The fractional frequency stability, analyzed as the Overlapping Allan deviation, is approximately 3×10-13 at τ = 10 s and almost 1×10-14 at 105 s.
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| 4. |
- 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
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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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| 5. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Experimental Investigation of a Four-Dimensional 256-ary Lattice-based Modulation Format
- 2015
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Ingår i: 2015 Optical Fiber Communications Conference and Exhibition, OFC 2015, Los Angeles, United States, 22-26 March 2015. - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- A four-dimensional modulation format with 256 point from the D4-lattice (256-D4) is compared to PM-16QAM in experiments. 256-D4 is more sensitive at high OSNR but with a 21.3% overhead turbo product code, PM-16QAM outperforms 256-D4.
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| 6. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Experimental Investigation of Crosstalk Penalties in Multicore Fiber Transmission Systems
- 2015
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Ingår i: IEEE Photonics Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally study the impact of crosstalk in multicore fibers, using polarization-multiplexed quadrature phase-shift keying signals. Using a 7-core fiber, we perform single-span transmission experiments, where the level of crosstalk to the core under test can be varied. We find the penalty in the required optical signal-to-noise ratio (OSNR), compared to a system with no crosstalk, for different signal-to-crosstalk ratios and at different pre-forward-error-correction target bit-error rates (BERs). We show that, for a 1-dB penalty, a 15.7-dB signal-to-crosstalk ratio can be tolerated at BER = 1 x 10(-3). We also perform recirculating loop experiments with varying amount of crosstalk per span to find the impact on the achievable transmission distance.
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| 7. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Four-Dimensional Estimates of Mutual Information in Coherent Optical Communication Experiments
- 2015
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Ingår i: European Conference on Optical Communications (ECOC), Valencia, Spain, 27 September - 1 October 2015. - 9788460817413
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Konferensbidrag (refereegranskat)abstract
- Mutual information is experimentally investigated for long-haul coherent transmission. Receivers that consider memoryless four-dimensional noise distributions can achieve significantly higher rates than receivers assuming two-dimensional symmetric distributions.
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| 8. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Single parity check-coded 16QAM over spatial superchannels in multicore fiber transmission
- 2015
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Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 23:11, s. 14569-14582
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigate single-parity check (SPC) coded spatial superchannels based on polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16QAM) for multicore fiber transmission systems, using a 7-core fiber. We investigate SPC over 1, 2, 4, 5 or 7 cores in a back-to-back configuration and compare the sensitivity to uncoded PM-16QAM, showing that at symbol rates of 20 Gbaud and at a bit-error-rate (BER) of 10(-3), the SPC superchannels exhibit sensitivity improvements of 2.7 dB, 2.0 dB, 1.7 dB, 1.3 dB, and 1.1 dB, respectively. We perform both single channel and wavelength division multiplexed (WDM) transmission experiments with 22 GHz channel spacing and 20 Gbaud channel symbol rate for SPC over 1, 3 and 7 cores and compare the results to PM-16QAM with the same spacing and symbol rate. We show that in WDM signals, SPC over hl1 core can achieve more than double the transmission distance compared to PM-16QAM at the cost of 0.91 bit/s/Hz/core in spectral efficiency (SE). When sharing the parity-bit over 7 cores, the loss in SE becomes only 0.13 bit/s/Hz/core while the increase in transmission reach over PM-16QAM is 44 %. (C) 2015 Optical Society of America
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| 9. |
- Fehenberger, Tobias, et al.
(författare)
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On the impact of carrier phase estimation on phase correlations in coherent fiber transmission
- 2015
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Ingår i: 2015 Tyrrhenian International Workshop on Digital Communications, TIWDC 2015. - 9781467392600 ; , s. 35-38
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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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| 10. |
- Karlsson, Magnus, 1967, et al.
(författare)
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Coherent transmission channels as 4d rotations
- 2015
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Ingår i: Signal Processing in Photonic Communications, SPPCom 2015; Omni Parker HouseBoston; United States; 27 June 2015 through 1 July 2015. - 9781557520005 ; , s. SpM3E.2-
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Konferensbidrag (refereegranskat)abstract
- We present and discuss a real four-dimensional (4d) channel model for coherent links, and compare it with the more conventional complex two-dimensional (Jones matrix) model.
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