Maximum-Likelihood Sequence Estimation for Optical Phase-Shift Keyed Modulation Formats

Alfiad, M. S.; Borne, D. van den; Hauske, Fabian N.; Napoli, Antonio; Koonen, Ton; Waardt, H. de

doi:10.1109/jlt.2009.2025148

Cited by 25 publications

(17 citation statements)

References 23 publications

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“…Τhis feature can be justified by noting that the constructive output port is resembles a duobinary (DB) signal, while the destructive output port resembles an alternatingmark-inversion (AMI) signal [27,28]. The intrinsic high tolerance of the DB modulation format in chromatic dispersion originates from its narrow spectrum [29] and can explain the better performance of every equalizer when the constructive, rather than the destructive, port (of each channel) is maintained to undergo the process of equalization [30]. Figure 9.…”

Section: Optical Layer Simulationmentioning

confidence: 99%

High-Speed, High-Performance DQPSK Optical Links with Reduced Complexity VDFE Equalizers

et al. 2017

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Optical transmission technologies optimized for optical network segments sensitive to power consumption and cost, comprise modulation formats with direct detection technologies. Specifically, non-return to zero differential quaternary phase shift keying (NRZ-DQPSK) in deployed fiber plants, combined with high-performance, low-complexity electronic equalizers to compensate residual impairments at the receiver end, can be proved as a viable solution for high-performance, high-capacity optical links. Joint processing of the constructive and the destructive signals at the single-ended DQPSK receiver provides improved performance compared to the balanced configuration, however, at the expense of higher hardware requirements, a fact that may not be neglected especially in the case of high-speed optical links. To overcome this bottleneck, the use of partially joint constructive/destructive DQPSK equalization is investigated in this paper. Symbol-by-symbol equalization is performed by means of Volterra decision feedback-type equalizers, driven by a reduced subset of signals selected from the constructive and the destructive ports of the optical detectors. The proposed approach offers a low-complexity alternative for electronic equalization, without sacrificing much of the performance compared to the fully-deployed counterpart. The efficiency of the proposed equalizers is demonstrated by means of computer simulation in a typical optical transmission scenario.

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Section: Optical Layer Simulationmentioning

confidence: 99%

High-Speed, High-Performance DQPSK Optical Links with Reduced Complexity VDFE Equalizers

et al. 2017

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“…As a result, MLSE has been commercially available for a number of years [3]. However, in [1,4,5] it has been demonstrated that neither of the two techniques is capable of compensating the residual CD in D(Q)PSK modulated signals. Hence, in [6] the principle of joint-MLSE was proposed as an alternative structure of conventional MLSE for D(Q)PSK modulated signals.…”

Section: Equalization For Direct-detection Receiversmentioning

confidence: 99%

“…Joint-MLSE is based on having more than one input to the MLSE representing the same signal, and then using a joint probability on the input signals it can provide a better estimation of the received signal. In [5], we experimentally evaluated the performance of the joint-MLSE technique and we proved its potential to significantly enhance the tolerance of the direct-detection receiver against CD. However, a major drawback for joint-MLSE is the need to use double as much ADCs, as well as the extra memory locations for storing the histograms of the extra input signals.…”

Section: Equalization For Direct-detection Receiversmentioning

confidence: 99%

“…However, a major drawback for joint-MLSE is the need to use double as much ADCs, as well as the extra memory locations for storing the histograms of the extra input signals. In order to overcome the implementation complexity problem of joint-MLSE, we have proposed in [5] the use of a shortened (less than one bit) Mach Zehnder delay interferometer (MZDI) together with a conventional MLSE. Using this approach we showed a CD tolerance of up to 4000 ps/nm for a 10 Gb/s DPSK signal using a 0.5 bit-delay MZDI and MLSE.…”

Section: Equalization For Direct-detection Receiversmentioning

confidence: 99%

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FFE, DFE and MLSE equalizers in phase modulated transmission systems

Alfiad

Borne

Kuschnerov³

et al. 2009

2009 IEEE LEOS Annual Meeting Conference Proceedings

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“…First, it monitors the phase detuning in a DLI used for PSK signal demodulation. This is particularly true for the cases replacing inline dispersion compensation with electrical equalization [14] , in which the signal is severely distorted by a large accumulated CD, resulting in the failure of other monitoring schemes based on waveforms [12] . In practice, we inserted another PD in front of the DLI to detect the power fluctuation and used the ratio of these two PD outputs to cancel out the effect of the power fluctuation.…”

mentioning

confidence: 99%

Phase shift monitoring of delay-line interferometer and its application in phase-shift keying signal system

Wen¹,

Liao²,

Zheng³

et al. 2012

中国光学快报

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The relation between the phase shift and the mean optical power (MOP) output from a delay-line interferometer (DLI) port applied for phase-shift keying (PSK) signal demodulation is proven of a cosine law irrelevant to signal modulation condition. The variation amplitude of the MOP is proportional to the transition duration of the modulation pulses. This phenomenon is interpreted as the result of the statistical and waveform characteristics of the PSK. The conclusions verified by simulation and experiment are generalized to other modulation formats and then applied to phase detuning monitoring, delay time judgment of DLI, and independence of modulation data assessment.OCIS codes: 060.5060, 120.3180, 070.1170. doi: 10.3788/COL201210.070601. Delay-line interferometer (DLI) has been widely used in optical communication to demodulate phase-shift keying (PSK) signal for direct detection by converting the optical phase information to amplitude [1,2] . The phase shift of DLIs greatly affects the quality of the demodulated signal, that is, minor phase shift detuning results in an eye opening closing, lowered noise tolerance, and increased bit error ratio (BER) [3,4] . These deteriorations become more severe in the case of multi-level modulation formats. The tolerable phase shift detuning effects at a 1-dB optical signal-to-noise ratio (OSNR) penalty are about 16 • and 6 • for differential PSK (DPSK) and differential quadrature PSK (DQPSK) formats, respectively [4] . Such a stringent requirement puts a great challenge on the design, manufacturing, and packaging of the DLI-based demodulators. Precise temperature control combined with athermal package is required to stabilize the phase shift [5] ; however, long term stabilization cannot be guaranteed due to device aging and control circuit operation drifting. Consequently, an effective way for phase shift detuning monitoring is necessary. Some proposed approaches include the engineeringoriented BER monitoring [6] , optical frequency dithering [7,8] , phase dithering [9] , pilot insertion [10,11] , and two-dimensional waveform analysis [12] . However, they are more or less inefficient or unpractical. The BER approach needs a forward error correction module operating at the bit rate, which is difficult for high data rate. Moreover, this approach is unable to differentiate the mixed impairments induced by many factors, such as chromatic dispersion (CD), polarization mode mode dispersion (PMD), and noise. The frequency dithering cannot be applied to the modules manufactured by different vendors as they obey different private protocols. Pilot insertion demands a change of the current transponder structure. Meanwhile, the perturbation-free schemes are preferred for its simplicity and adaptability.In this letter, we treat the PSK signal itself as a probe signal, through which we study the influence on the output signal given by DLI phase shift detuning. The mean optical power (MOP) output from one DLI port varies with the phase shift in the form of a cosine, which is irrelevan...

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Maximum-Likelihood Sequence Estimation for Optical Phase-Shift Keyed Modulation Formats

Cited by 25 publications

References 23 publications

High-Speed, High-Performance DQPSK Optical Links with Reduced Complexity VDFE Equalizers

High-Speed, High-Performance DQPSK Optical Links with Reduced Complexity VDFE Equalizers

FFE, DFE and MLSE equalizers in phase modulated transmission systems

Phase shift monitoring of delay-line interferometer and its application in phase-shift keying signal system

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