PDM-QPSK: on the system benefits arising from temporally interleaving polarization tributaries at 100Gb/s.
TL;DR: It is demonstrated that the amount of benefits provided by this technique is dependent on the configuration of the WDM transmission system.
Abstract: We experimentally study, over a dispersion-managed link relying on low chromatic dispersion fibre, the origins of the system benefits provided by temporally interleaving the polarization tributaries of 100Gb/s coherent RZ-PDM-QPSK by half a symbol period. Hence, we demonstrate that the amount of benefits provided by this technique is dependent on the configuration of the WDM transmission system.
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TL;DR: In this article, an extensive Monte Carlo simulation analysis on the impact of DP-QPSK pulse shape in high-spectral efficiency WDM transmission at 112 Gb/s per channel is presented.
Abstract: This paper reports results of an extensive Monte Carlo simulation analysis on the impact of DP-QPSK pulse shape in high-spectral efficiency WDM transmission at 112 Gb/s per channel. The pulse shapes studied include NRZ, 50% duty cycle RZ and 67% duty cycle RZ. Both symbol-aligned and symbol-interleaved formats are investigated and compared for nonlinear transmission tolerance on common dispersion maps used in terrestrial long-haul systems. The RZ pulse shape shows the greatest improvement in nonlinear tolerance with symbol-interleaving. However, symbol-interleaving only provides significant benefit in optical line systems designed to preserve the pulse shape during transmission, such as systems based on distributed dispersion compensating fiber (DCF). The duty cycle of the RZ pulse has only a minor impact on nonlinear performance, and even systems based on the NRZ pulse shape can gain significant benefit from symbol-interleaving.
27 citations
Cites background from "PDM-QPSK: on the system benefits ar..."
...leaving of the polarization tributaries can significantly reduce the impact of XpolM on coherent DP-QPSK systems [6]–[8]....
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TL;DR: In this article, the authors compare different optical methods to improve the resilience of coherent 112-Gb/s PDM-QPSK transmissions against cross-channel nonlinearities, and find that the best performance is achieved by iRZ-PDM-Q PSK in a dispersion-managed link with an XPM suppressor at each span.
Abstract: We compare by simulation different optical methods to improve the resilience of coherent 112-Gb/s polarization-division multiplexing (PDM)-quadrature phase-shift keying (QPSK) wavelength-division-multiplexing (WDM) transmissions against cross-channel nonlinearities. Such methods consist of 1) increasing the line group velocity dispersion (GVD), or 2) the line polarization-mode dispersion (PMD), or 3) inserting in-line cross-phase modulation (XPM) suppressors. Such methods are tested using nonreturn-to-zero (NRZ), aligned return-to-zero (aRZ), and interleaved RZ (iRZ) pulse formats. We show that the nonlinearity-mitigating effect underlying all three methods is an increase of the interchannel decorrelation, obtained by either increasing walk-off (methods 1 and 3) or by depolarizing the WDM channels (method 2). Interchannel decorrelation improves performance and reduces the difference among the three pulse formats. We find that the best performance is achieved by iRZ-PDM-QPSK in a dispersion-managed link with an XPM suppressor at each span.
18 citations
Cites methods from "PDM-QPSK: on the system benefits ar..."
...As a way to mitigate cross-channel effects in dispersion-managed (DM) systems, some experiments [2] and simulations [1] verified the benefits of the interleaved return-to-zero (iRZ) pulse format, in which the polarization tributaries are 50%-RZ shaped and delayed by half a symbol time....
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04 Nov 2010
TL;DR: In this article, the interplay between PMD and nonlinearities experienced by polarization-multiplexed signals detected with a coherent receiver was investigated and an experimental analysis over 2000 random draws of PMD conditions over an SSMF link was performed.
Abstract: We report on the interplay between PMD and nonlinearities experienced by polarization-multiplexed signals detected with a coherent receiver. An experimental analysis over 2000 random draws of PMD conditions over an SSMF link shows that PMD can improve significantly system performance.
17 citations
TL;DR: In this article, the nonlinear threshold (NLT) versus per-channel symbol rate at constant bandwidth efficiency for a 15-channel wavelength-division multiplexing long-haul coherent optical transmission over a 20 times$ ǫ 100-km single-mode fiber link, both dispersion-managed (DM) and dispersion uncompensated (DU), with several popular polarization multiplexed modulation formats.
Abstract: We provide simulations of the nonlinear threshold (NLT) versus per-channel symbol rate at a constant bandwidth efficiency for a 15-channel wavelength-division multiplexing long-haul coherent optical transmission over a 20 $\times$ 100 km single-mode fiber link, both dispersion-managed (DM) and dispersion-uncompensated (DU), with several popular polarization multiplexed modulation formats. We exploit the nonlinearity-decoupling method to estimate the NLT due to each individual nonlinear effect, and, thus, show how the dominant nonlinearity changes with symbol rate. Plots of the NLT normalized to the symbol rate also reveal the symbol rate achieving the longest distance. Assuming a signal-independent Gaussian nonlinear interference, we derive a new formula yielding the system reach based on knowledge of NLT measurements on a much shorter link. We finally provide reach simulations to verify the accuracy of the new reach formula for both DM and DU links.
17 citations
Cites background or methods from "PDM-QPSK: on the system benefits ar..."
...For all formats we used NRZ supporting pulses, and for PDMBPSK and PDM-QPSK we also considered iRZ pulses with 50% duty cycle [16], [17]....
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...Compared to [15], we here extend the investigation to higher spectral efficiency, and to polarization switched QPSK (PS-QPSK) and interleaved return to zero (iRZ) for both PDM-BPSK and PDM-QPSK [16], [17]....
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...3) iRZ pulses in PDM-PSK formats were proposed because they quite effectively suppress XPolM [16], [17]....
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TL;DR: A state of art over different strategies employing PM-QPSK techniques to achieve an enhancement in various optical performance parameters is presented.
Abstract: Nowadays, public demands high capacity global internet traffic in terms of cloud computing, video gaming, fiber to the home and mobile networks, etc. To fulfill such huge traffic requirement, high-...
15 citations
References
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IBM1
TL;DR: This paper solves the general problem of adaptive channel equalization without resorting to a known training sequence or to conditions of limited distortion.
Abstract: Conventional equalization and carrier recovery algorithms for minimizing mean-square error in digital communication systems generally require an initial training period during which a known data sequence is transmitted and properly synchronized at the receiver. This paper solves the general problem of adaptive channel equalization without resorting to a known training sequence or to conditions of limited distortion. The criterion for equalizer adaptation is the minimization of a new class of nonconvex cost functions which are shown to characterize intersymbol interference independently of carrier phase and of the data symbol constellation used in the transmission system. Equalizer convergence does not require carrier recovery, so that carrier phase tracking can be carried out at the equalizer output in a decision-directed mode. The convergence properties of the self-recovering algorithms are analyzed mathematically and confirmed by computer simulation.
2,645 citations
TL;DR: A class of nonlinear estimation algorithms is described to estimate the unknown phase of a carrier which is fully modulated by m -ary PSK modulation, and the effect of quantization and finite read-only-memory implementation of the nonlinearity are determined by computer simulation.
Abstract: Burst transmission of digital data and voice has become commonplace, particularly in satellite communication systems employing time-division multiple-access (TI)MA) and packet demand-assignment multiple-access (DAMA) techniques. In TDMA systems particularly, phase estimation on each successive burst is a requirement, while bit timing and carrier frequency can be accurately tracked between bursts. A class of nonlinear estimation algorithms is described to estimate the unknown phase of a carrier which is fully modulated by m -ary PSK modulation. Performance of the method is determined in closed form and compared to the Cramer-Rao lower bound for the variance of the estimation error in the phase of an unmodulated carrier. Results are also obtained when the carrier frequency is imprecisely known. Finally, the effect of quantization and finite read-only-memory (ROM) implementation of the nonlinearity are determined by computer simulation.
1,116 citations
01 Jan 2008
TL;DR: In this paper, the use of a coherent digital receiver for compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard is discussed.
Abstract: We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.
405 citations
TL;DR: It is found that the LO phase noise to amplitude noise conversion can cause significant penalties in the 112-Gb/s system with only electronic dispersion compensation if distributed feedback lasers are used, but by using time-interleaved return-to-zero (RZ) P -QPSK, which can significantly suppress nonlinear polarization scattering.
Abstract: Using numerical simulations, we study and compare the performance of 42.8-Gb/s and 112-Gb/s intradyne coherent polarization-division- multiplexed quadrature-phase-shift-keying (PDM-QPSK) systems in wavelength-division-multiplexed (WDM) transmission with inline dispersion compensation fiber (DCF) and that with fully electronic dispersion compensation. Two effects are considered in the studies. One is fiber nonlinearities and the other is the local oscillator (LO) phase noise to amplitude noise conversion induced by electronic dispersion compensation. Results of 1000-km transmission employing standard single-mode fiber (SSMF) show that, for non-return-to-zero (NRZ) PDM-QPSK, both the 42.8-Gb/s and 112-Gb/s WDM systems with DCF have less tolerance to fiber nonlinearities than those with electronic dispersion compensation due to nonlinear polarization scattering. However, by using time-interleaved return-to-zero (RZ) P -QPSK, which can significantly suppress nonlinear polarization scattering in a system with inline DCF, the 42.8-Gb/s system with DCF can achieve better performance than that with electronic dispersion compensation, and comparable performance can be obtained for the 112-Gb/s system with DCF and that with electronic dispersion compensation. We find that the LO phase noise to amplitude noise conversion can cause significant penalties in the 112-Gb/s system with only electronic dispersion compensation if distributed feedback lasers are used.
93 citations
22 Mar 2009
TL;DR: In this article, the demodulation of PDM-QPSK waveforms is performed with digital processing in a coherent receiver over 7,040km of large effective area fiber, separated by Raman-assisted erbium repeaters.
Abstract: 100Gb/s channels are transmitted over 7,040km. After propagation across eighty-eight 80km-long sections of large effective area fiber, separated by Raman-assisted erbium repeaters, demodulation of PDM-QPSK waveforms is performed with digital processing in a coherent receiver.
80 citations