Design of near optimum electrical equalizers for optical transmission in the presence of PMD

Haunstein, H.; Sticht, K.; Dittrich, Andreas; Sauer-Greff, W.; Urbansky, R.

doi:10.1109/ofc.2001.928437

Cited by 38 publications

(11 citation statements)

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“…The use of MLSE to compensate for deterministic non-linear distortions in channels exhibiting memory [2], [3], and the importance of the Viterbi algorithm (VA) [4] will be described. The branch metrics used by the VA can be implemented using non-parametric histogram approximations to the actual PDFs, or parametric analytic closed form expressions [9].…”

Section: Mlse Backgroundmentioning

confidence: 99%

Review of Recent Progress in MLSE Receiver Technologies

Whiteaway¹,

Fludger²,

Langenbach³

et al. 2007

2007 Digest of the IEEE/LEOS Summer Topical Meetings

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MLSE offers adaptive non-linear receiver-sided equalization for channels with memory. New areas of application considered are directly modulated DFB laser, D(B/Q)PSK, and duo-binary transmission systems. Reduced computational complexity is a new research area.I. MLSE BACKGROUND An overview of FFE, DFE and MLSE [1] (maximum likelihood sequence estimator) receiver-sided equalization technologies will be presented. The use of MLSE to compensate for deterministic non-linear distortions in channels exhibiting memory [2], [3], and the importance of the Viterbi algorithm (VA) [4] will be described. The branch metrics used by the VA can be implemented using non-parametric histogram approximations to the actual PDFs, or parametric analytic closed form expressions [9]. The chromatic dispersion (CD) compensation benefits of MLSE have been experimentally demonstrated with two commercial realizations of an MLSE processor [5], [6]. A reach of 150 km has been shown for NRZ transmission using a 4-state MLSE at the receiver [5]. Training sequences can be used to establish the branch metrics in the MLSE, but in practice this adds complexity to the system and reduces the transmission capacity. An MLSE processor with automated acquisition has been developed [5], and a theoretical investigation into the design of a MLSE with blind acquisition capability has been reported [7]. The dynamic polarization mode dispersion (PMD) compensation capability has also been demonstrated by experimental results, which showed that an MLSE update rate of 2 kHz is suitable to compensate for a polarization rotation rate of up to 0.25 rad/ms with first order PMD [8]. II. NEW TRENDS IN MLSE DESIGN A. Applications requiring an increased number of statesThe ability of a MLSE to compensate for CD is related to the number of states that are used. The increasing capability of electronic processors will therefore lead to the development of MLSE processors with an increasing compensation capability. However this places increasing demands on the clock recovery, which is expected to increase in sophistication as the number of states in MLSE processors increases in the future. B. Signal statisticsThe best performance is obtained from the MLSE when the branch metrics are closely matched to the real statistical noise distribution of the signal samples. The histogrambased approach to constructing the branch metrics, used in the Viterbi trellis, requires a significant time to accumulate the data, particularly for the less probable events in the tails of the histograms. The inherent quantization also introduces performance limitations. However the branch metrics do then approach the complex measured non-central statistical noise distributions.The time delay involved in implementing this approach has driven the effort to simplify the branch metrics using analytic functions [9], [10]. A range of analytic approximations has been examined from Gaussian, to simple and non-central chi-squared functions, to the more complex Karhunen-Loeve expansion. Unfortunately these functio...

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Section: Mlse Backgroundmentioning

confidence: 99%

Review of Recent Progress in MLSE Receiver Technologies

Whiteaway¹,

Fludger²,

Langenbach³

et al. 2007

2007 Digest of the IEEE/LEOS Summer Topical Meetings

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“…There two decisions with different thresholds are provided simultaneously and one of both is selected by a multiplexer in a digital feedback loop depending on the last decision. Integrated circuits (IC) exclusively designed for 10-Gb/s signal processing and based on SiGe or GaAs technology [42,43,44,45,46] have been manufactured for lab use and also first product prototypes are already on the market. First ICs suitable for 40-Gbit/s operation might appear in research labs in the next time (2004).…”

Section: Basic Electronic Equalizersmentioning

confidence: 99%

“…The maximum likelihood signal detection (MLSD) scheme is based on delayed decision after analyzing a whole distorted signal sequence over a few bit slots [40,42]. MLSD exhibits the ultimate performance of electrical processing schemes.…”

Section: Viterbi Equalizermentioning

confidence: 99%

PMD compensation techniques

Bülow

Lanne²

2004

J Optic Comm Rep

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Mitigating PMD is still a challenge in today's optical communications. After giving the key performance indicators dictated by the statistical nature of PMD, we introduce the classification of PMD compensation schemes into 2 categories: optical and electrical PMD compensators. In a first part, we explain the operation principle of a PMD compensator by taking a detailed look at the basic optical PMD compensator and appropriate feedback signals. More complex multistage structures and a feed-forward adaptation approach are also discussed. This first part is closed by results from a oneyear field trial confirming the behavior and performance of a prototype compensator. In the second part of this article, electronic equalization for PMD mitigation is explained. Starting with a discussion on performance and adaptation of linear equalizers suitable for analog electronic signal processing, finally also the Viterbi equalizer basing on digital signal processing is analyzed. A comparative review of mitigation by optical or electronic means concludes the discussion.

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“…The use of electronic signal processing in the receiver can reduce this problem and easily adapt to changing channel conditions. It has been shown [2] that MLSE receivers can efficiently cope with impairments such as nonlinear dispersion and nongaussian signal-dependent noise.…”

Section: Introductionmentioning

confidence: 99%

MLSE-based receivers on DWDM lightwave systems

Carrer

Hueda

Crivelli

The Ninth International Conference onCommunications Systems, 2004. ICCS 2004.

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In dense wavelength division multiplexed (DWDM) links, the need for greater available bandwidth results in smal ler channel separation and larger channel count. This in creases the importance of nonlinear coupling effects such as four wave mixing (FWM) and cross-phase modulation (CPM). These impairments, together with chromatic disper sion (CD), polarization mode dispersion (PMD), and ampli fi ed spontaneous emission (AS E) noise limit the maximum reach of the optical links. Maximum likelihood sequence estimation (MLSE) receivers can incorporate detailed know ledge of the statistical properties of noise and crosstalk into the decision process, therefore improving performance in the presence of these impairments. These receivers have been previously proposed in [1,2] to combat CD and PMD in IM/DD optical channels.In this paper we propose to extend the use of MLSE to DWDM links to combat the combined effect of nonlin ear crosstalk, dispersion and noise. We derive a new ana lytical expression for the statistics of the received signal in the presence of FWM which is necessary to implement the MLSE receiver. As a second important contribution of this paper, we present a theoretical performance analysis of MLSE in DWDM optical channels. Computer simulations show excellent agreement between the prediction of the the ory and simulation results.

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Design of near optimum electrical equalizers for optical transmission in the presence of PMD

Cited by 38 publications

References 1 publication

Review of Recent Progress in MLSE Receiver Technologies

Review of Recent Progress in MLSE Receiver Technologies

PMD compensation techniques

MLSE-based receivers on DWDM lightwave systems

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