Decision-Feedback Equalization of Bandwidth-Constrained N-WDM Coherent Optical Communication Systems

Fickers, Jessica; Ghazisaeidi, Amirhossein; Salsi, M.; Charlet, G.; Emplit, Philippe; Horlin, François

doi:10.1109/jlt.2013.2252883

Cited by 17 publications

(6 citation statements)

References 23 publications

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“…In [21], the authors study the impact of the channel bandwidth on performance and the maximization of spectral efficiency in a multi-channel system using a constant modulus algorithm feed forward equalizer (CMA FF) with a feedback loop (to further compensate for ISI). The equalizer filter coefficients are calculated from the impulse responses of the feed forward and feedback paths.…”

Section: Introductionmentioning

confidence: 99%

Modified Nonlinear Decision Feedback Equalizer for Long-Haul Fiber-Optic Communications

Maiti

Brandt-Pearce

2015

J. Lightwave Technol.

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In a long-haul optical fiber communication system, fiber attenuation, dispersion and nonlinearity combined with nondeterministic noise from optical amplifiers used for periodic regeneration cause adverse effects on system performance. Several optical and electrical signal processing techniques have been proposed and implemented to extract the transmitted data; some provide better performance than others, but at a cost of higher computational complexity. We present a modified nonlinear decision feedback equalizer designed for use in a legacy optical communication system with periodic dispersion compensation. The effects of noise and nonlinearity on the equalizer coefficients are investigated, and a suboptimal convergence algorithm to reduce such effects is proposed and verified. Our equalizer provides performance comparable to that obtained using digital backpropagation while being computationally simpler, compensating linear and nonlinear physical impairment effects effectively even at high power levels where fiber nonlinearity is significant. Performance prediction of the designed DFE is also discussed, using a numerical method, with and without error propagation.

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Section: Introductionmentioning

confidence: 99%

Modified Nonlinear Decision Feedback Equalizer for Long-Haul Fiber-Optic Communications

Maiti

Brandt-Pearce

2015

J. Lightwave Technol.

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“…Under the assumption that the coefficient variation is small compared with its mean value after the tap coefficient converges, the higher-order terms of the variation in Eq. (17) are ignored to obtain a tractable result on the coefficient variance as E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 1 8 ; 3 2 6 ; 4 6 9…”

Section: Analysis On the Feedback Delay Effectmentioning

confidence: 99%

“…The data-aided least-mean square (LMS)-based method and the nondata-aided constant modulus algorithm (CMA)-based method are the two most commonly used ways. [13][14][15] Though there have been a lot of research on the electrical channel equalizers based on simulation or off-line experiments, [16][17][18] the real-time implementation of such digital equalizers for 100 Gb∕s and above rate is difficult due to the bottleneck of the hardware processing speed not available from current chip technology. 19 The computation delay on the error signal feedback from the parallel and pipelined implementation was found to have detrimental effects on the convergence performance of the adaptive TDE.…”

Section: Introductionmentioning

confidence: 99%

Studies on effects of feedback delay on the convergence performance of adaptive time-domain equalizers for fiber dispersive channels

Guo

Qiu

2016

Opt. Eng

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Abstract. Adaptive time-domain equalizer (TDE) is an important module for digital optical coherent receivers. From an implementation perspective, we analyze and compare in detail the effects of error signal feedback delay on the convergence performance of TDE using either least-mean square (LMS) or constant modulus algorithm (CMA). For this purpose, a simplified theoretical model is proposed based on which iterative equations on the mean value and the variance of the tap coefficient are derived with or without error signal feedback delay for both LMS-and CMA-based methods for the first time. The analytical results show that decreased step size has to be used for TDE to converge and a slower convergence speed cannot be avoided as the feedback delay increases. Compared with the data-aided LMS-based method, the CMA-based method has a slower convergence speed and larger variation after convergence. Similar results are confirmed using numerical simulations for fiber dispersive channels. As the step size increases, a feedback delay of 20 clock cycles might cause the TDE to diverge. Compared with the CMA-based method, the LMS-based method has a higher tolerance on the feedback delay and allows a larger step size for a faster convergence speed.

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“…In optical communications, high-speed data transfer is often limited by signal distortion, which is mainly caused by broadening of pulses that results n ISI. To cope with ISI, adaptive algorithms based on the mean squared error (MSE) criterion have been widely chosen [7,8]. Unsupervised equalization algorithms operate without the need for training data for starting or restarting after a communications breakdown and most blind equalization algorithms utilize the nonlinearity of the equalizer output for updating weights.…”

Section: Introductionmentioning

confidence: 99%

Blind Signal Processing for Medical Sensing Systems with Optical-Fiber Signal Transmission

Kim¹,

Byun²

2014

Journal of Sensor Science and Technology

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In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.

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Decision-Feedback Equalization of Bandwidth-Constrained N-WDM Coherent Optical Communication Systems

Cited by 17 publications

References 23 publications

Modified Nonlinear Decision Feedback Equalizer for Long-Haul Fiber-Optic Communications

Modified Nonlinear Decision Feedback Equalizer for Long-Haul Fiber-Optic Communications

Studies on effects of feedback delay on the convergence performance of adaptive time-domain equalizers for fiber dispersive channels

Blind Signal Processing for Medical Sensing Systems with Optical-Fiber Signal Transmission

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