Field measurements of polarization transients on a long-haul terrestrial link

Nelson, L.E.; Birk, Martin; Woodward, S.L.; Magill, Peter

doi:10.1109/pho.2011.6110816

Cited by 10 publications

(3 citation statements)

References 4 publications

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“…In both our simulation and experiment, we fixed the value of PDL and applied continuous random rotations before and after, as in Equation (12). The value of θ and β was set to rotate at a speed of 800 Hz (maximum rotation measured in buried fibers [32]). The BER was averaged out over the length of the frame required by the FEC.…”

Section: Simulation Environmentmentioning

confidence: 99%

Adaptive Pre/Post-Compensation of Cascade Filters in Coherent Optical Transponders

Abdo

D’Amours

2020

Future Internet

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We propose an adaptive joint pre- and post-compensation to correct the filtering effects caused by cascading reconfigurable optical add drop multiplexers (ROADMs). The improvement is achieved without using additional hardware (HW) on the link or within the signal processor in the transponders. Using Monte Carlo simulations, the gradient-descent based method shows an improvement of 0.6 dB and 1.1 dB in the required optical signal-to-noise ratio (R-OSNR) at the threshold pre-decoder bit error rate (BER) of 0.02 versus pre-compensation only in the linear and nonlinear operating region of fiber respectively. We experimentally verified the method with lab measurements in the presence of heavy filtering and optical impairments. We observed a gain up to ~0.4 dB compared to typically used pre-compensation only. Additionally, other tangible system benefits of our method are listed and discussed.

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Section: Simulation Environmentmentioning

confidence: 99%

Adaptive Pre/Post-Compensation of Cascade Filters in Coherent Optical Transponders

Abdo

D’Amours

2020

Future Internet

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“…An in-depth study performed using Verizon aerial fiber in [9,10] showed that aerial fibers typically encounter higher SOP transients than those buried in the ground. In [11], data were collected from an OPGW plant in order to determine the correlation between SOP transients and lightning strikes.…”

Section: Causes Of State-of-polarization Transientsmentioning

confidence: 99%

Adaptive Filtering in Optical Coherent Flexible Bit-Rate Receivers in the Presence of State-of-Polarization Transients and Colored Noise

Abdo

D’Amours

2019

Journal of Computer Networks and Communications

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In this article, we analyze the performance of adaptive filtering in the context of dual-polarization coherent optical flexible bit-rate transceivers. We investigate the ability of different adaptive algorithms to track fast state-of-polarization (SOP) transients in the presence of colored noise. Colored noise exists due to the concatenation of Wavelength Selective Switches (WSSs) and polarization dependent loss (PDL) which can be considered as spatially dependent noise. We consider the use of different modulation formats, and the practical limitation of error signal feedback delay in decision-directed adaptive filters is also taken into account. The back-to-back required signal-to-noise ratio (RSNR) penalty that can be tolerated determines the maximum SOP rate of change that can be tracked by the adaptive filters as well as the filter’s adaptive step size. We show that the recursive least squares algorithm, using the covariance matrix as an aggressive “step size,” has a much better convergence speed compared to the least mean squares (LMS) and normalized LMS (NLMS) algorithms in the presence of colored noise in the fiber. However, the three algorithms have similar tracking capabilities in the absence of colored noise.

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“…5(b) and 5(c), we plot the steady-state BER versus the SOP angular frequency (ω) for both 14 Gbaud and 28 Gbaud PDM-16QAM, respectively. Although high speed SOP transients happen as rare events in a real system and will cause system outages [21,22], we use a fixed ω for each point on Figs. 5(b) and 5(c) to simplify the simulation as well as characterize the tracking limits of all algorithms.…”

Section: Ts-est Algorithm For Tracking Fast Sop Transientsmentioning

confidence: 99%

Ultrafast and low overhead training symbol based channel estimation in coherent M-QAM single-carrier transmission systems

Morsy-Osman¹,

Chagnon²,

Zhuge³

et al. 2012

Opt. Express

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We propose a training symbol based channel estimation (TS-EST) algorithm that estimates the 2 × 2 Jones channel matrix. The estimated matrix entries are then used as the initial center taps of the 2 × 2 butterfly equalizer. Employing very few training symbols for TS-EST, ultrafast polarization tracking is achieved and tap update can be initially pursued using the decision-directed least mean squares (DD-LMS) algorithm to mitigate residual intersymbol interference (ISI). We experimentally verify the proposed TS-EST algorithm for 112 Gbps PDM-QPSK and 224 Gbps PDM-16QAM systems using 10 and 40 training symbols for TS-EST, respectively. Steady-state and transient bit error rates (BERs) achieved using the TS-EST algorithm are compared to those obtained using the constant modulus algorithm (CMA) and the training symbol least mean squares (TS-LMS) algorithm and results show that the proposed TS-EST algorithm provides the same steady-state BER with a superior convergence speed. Also, the tolerance of the proposed TS-EST algorithm to laser phase noise and fiber nonlinearity is experimentally verified. Finally, we show by simulation that the superior tracking speed of the TS-EST algorithm allows not only for initial polarization tracking but also for tracking fast polarization transients if four training symbols are periodically sent during steady-state operation with an overhead as low as 0.57%.

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Field measurements of polarization transients on a long-haul terrestrial link

Cited by 10 publications

References 4 publications

Adaptive Pre/Post-Compensation of Cascade Filters in Coherent Optical Transponders

Adaptive Pre/Post-Compensation of Cascade Filters in Coherent Optical Transponders

Adaptive Filtering in Optical Coherent Flexible Bit-Rate Receivers in the Presence of State-of-Polarization Transients and Colored Noise

Ultrafast and low overhead training symbol based channel estimation in coherent M-QAM single-carrier transmission systems

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