EP1402670A2 - Procede et dispositif de determination et de separation d'effets de canaux individuels lors du transfert optique d'un signal de multiplexage par repartition en longueur d'onde (wdm) - Google Patents
Procede et dispositif de determination et de separation d'effets de canaux individuels lors du transfert optique d'un signal de multiplexage par repartition en longueur d'onde (wdm)Info
- Publication number
- EP1402670A2 EP1402670A2 EP02760083A EP02760083A EP1402670A2 EP 1402670 A2 EP1402670 A2 EP 1402670A2 EP 02760083 A EP02760083 A EP 02760083A EP 02760083 A EP02760083 A EP 02760083A EP 1402670 A2 EP1402670 A2 EP 1402670A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrical
- channel
- determined
- sdi
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
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- 238000004364 calculation method Methods 0.000 description 4
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07951—Monitoring or measuring chromatic dispersion or PMD
Definitions
- the invention relates to a method and an arrangement for determining and separating single channel effects in the optical transmission of a wavelength division multiplex (-WDM) signal.
- -WDM wavelength division multiplex
- Nonlinear interference occurs when WDM signals are transmitted through optical fibers.
- multi-channel interactions manifest themselves as an increased noise on the signal levels of all or some channels
- channel signals have deterministic distortions due to single-channel effects.
- these interference effects must be determined and then minimized.
- methods for measuring the quality properties of a transmitted signal are known, for example, by determining the Q factor or the bit error rate or the number of corrected bits by means of a forward error correction (-FEC) module (see "Optical Fiber Communications ", IIIA, i ' .P. Kaminow, TL Koch, 1997, p. 316).
- WDM wavelength division multiplex
- the Kerr effect mainly causes four-wave mixing (“Four Wave Mixing” FWM) and / or cross-phase modulation (“Cross Phase Modulation” XPM).
- the nonlinear scattering process causes stimulated Raman scattering ("Stimulated Ra an Scattering” SRS).
- FIGS. 1 and 2 show two amplitude histograms of a channel with GVD and / or SPM effects or with an ICC effect. Show:
- Fig. 2 Amplitude histograms with different crosstalk within one wavelength.
- the amplitude histogram AH shown in FIG. 1 was obtained with different channel powers 0, 6, 12, 15 dBm after 50 km of a standard single-mode fiber with complete dispersion compensation, e.g. B. by means of a dispersion compensation created the (-DCF) fiber.
- a synchronous sampling of a binary channel signal by means of a variable sampling voltage U s was used. It can be seen that the single-channel effect GVD is completely compensated for by the DCF fiber, so that no signal distortion of a channel can be determined if the channel power is low and SPM does not make any contribution.
- high channel power on the other hand, due to the increased SPM, there are several maxima or saddle points in the amplitude distribution of the level “1” of a channel. This can be used as a criterion to determine a non-optimized dispersion compensation between GVD and SPM.
- the object of the present invention is to determine and separate occurring single channel effects GVD, SPM, ICC and SBS, which occur during the optical transmission of wavelength division multiplex signals.
- the inventive method for determining and separating single channel effects GVD, SPM, ICC and SBS in the optical transmission of a wavelength division multiplex (-WDM) signal, whose channels are separated and converted into electrical signals, is based on the analysis of the amplitude histogram and Spectrum diagram for each electrical signal.
- the amplitude histogram is determined as the probability density distribution of the amplitudes of the electrical signal, the two levels (0) and (1) being the only maxima in the amplitude histogram with optimal transmission or with un- Different signal-to-noise ratios of a channel are provided.
- the single channel effects of dispersion and self-phase modulation GVD / SPM, in particular with high channel powers, or the crosstalk ICC are determined by more than two maxima or saddle points in the amplitude histogram.
- the spectrum diagram is also determined as the power density spectrum of the electrical signal, with several frequencies of transmitted data of the electrical signal being represented in the spectrum diagram over a corresponding data bandwidth.
- the single channel effect dispersion GVD is determined by at least a minimum within and above the data bandwidth in the spectrum diagram.
- the single-channel effect of self-phase modulation SPM is determined by at least one minimum within the data bandwidth in the spectrum diagram.
- the effects GVD and SPM can therefore be advantageously determined and compensated for.
- the spectrum diagram remains unchanged when the ICC crosstalk occurs.
- the single-channel effect ICC can therefore be determined by looking at the amplitude histogram obtained to date in conjunction with the corresponding spectrum diagram and separated from the other single-channel effects GVD / SPM.
- the single-channel effect SBS (stimulated Brillouin scattering) is determined by weakening the channels in the range of low frequencies (below approx. 100 MHz) in the spectrum diagram of the method according to the invention. This effect does not occur for the GVD, SPM and ICC single-channel effects determined so far.
- the amplitude histogram can also be used to carry out a quality measurement of the transmission, which outputs a quality parameter such as the Q factor, the bit error rate or the eye opening of a signal.
- the power density in the electrical spectrum drops for small frequencies of the transmitted data of the electrical signal. Through this Attenuation of the carrier at SBS also decreases the signal quality, ie for example the Q factor decreases.
- FIG. 3 the arrangement according to the invention
- FIG. 4 the electrical spectrum diagram for different pulse shapes of an NRZ data signal
- FIG. 5 the electrical spectrum analyzer
- FIG. 6 the electrical spectrum diagrams for different dispersion values with linear propagation
- FIG. 7 the electrical spectrum diagrams with complete dispersion compensation with different channel powers
- FIG. 8 the electrical spectrum diagrams with different crosstalk values ICC
- Figure 9 the deterioration in transmission quality at SBS.
- the arrangement according to the invention is shown schematically in FIG.
- At least a portion of a WDM signal S decoupled from a transmission link LWL is fed to the input of the arrangement as an input signal IS.
- the input signal IS is passed to a demultiplexer DEMUX, for example a spectrally tunable optical filter, to separate its channels Kj. (I> 0).
- At least one channel K ⁇ is still by an optical-electrical converter OEW, z. B. a photodiode, converted into an analog electrical signal ESi.
- the electrical signal ESj. on the one hand electrical amplitude distributor EAS and, on the other hand, an electrical spectrum analyzer ESA.
- An amplitude histogram AHi of the electrical signal ESi is generated in the electrical amplitude distributor EAS by synchronous sampling.
- FIGS. 1 and 2 represent such amplitude histograms AHi.
- a measurement of the Q factor Q, the bit error rate BER or the eye opening of data transmitted by the electrical signal ESi for estimating the transmission quality of a channel K is also possible ⁇ to be carried out.
- Other methods for measuring the quality of the channel transmission are possible, but are not mentioned further here.
- the amplitude histogram AHi enables the determination of the individual channel effects GVD, SPM and ICC, but the separation between GVD / SPM and ICC single channel effects cannot be realized.
- the electrical spectrum analyzer ESA provides a broadband spectrum diagram SDi of the electrical signal ESi with binary coded and broadband data DSi. All or selected frequencies of the data DSi are determined and displayed in the spectrum diagram SDi.
- the data DSi are usually binary coded at two levels “0 ⁇ and“ l ⁇ and modulated in a data bandwidth limited by the so-called carrier frequency.
- FIG. 4 shows electrical spectrum diagrams SDi in the frequency range F in each case for two different pulse shapes generated by a simulation - with cosine squared edges deformed in power (solid curve) or in amplitude (dotted curve) - of a non-return-to-zero ( -NRZ) - data signal with a data rate of 10 Gbit / s.
- PRBS pseudo random sequence
- the pulse shape has a strong influence on the side lines at 10, 20 GHz and higher orders of the carrier frequency, but has virtually no effect on the course of the spectrum of the data DSi in the data bandwidth. The entire spectrum outside the side lines can therefore be used to determine the individual channel effects. Deviations from the expected form allow conclusions to be drawn about signal distortions and are also not caused by small fluctuations in the transmitters.
- FIG. 5 shows a schematic representation of the electrical spectrum analyzer ESA for analyzing the electrical signal ESi.
- ESA electrical spectrum analyzer
- FIG. 6 shows electrical spectrum diagrams SD ⁇ below and above the first side line 10 GHz for different dispersion values (0, 500, 1000, 1500 ps / nm) with linear propagation, i. h with small channel powers or with so-called small signal approximation.
- the dispersion GVD and the self-phase modulation SPM are expressed in a change in the received spectrum diagram SDi as an electrical power density spectrum compared to the output signal of an optical one Fiber.
- This effect can be described analytically by the fiber transfer function, especially with small signal approximation. This effect is known from "S all Signal Analysis for Dispersive Optical Fiber Communication Systems” 1 , Jiammin Wang, Klaus Petermann, Journal of Lightwave Technology, Vol. 10, No. 1, January 1992, pp. 96-99.
- the curves shown in FIG. 6 are shifted vertically for clarity.
- the point representation corresponds to the numerical simulation with the electrical signal ESi used in FIG. 4 and the solid line to the analytical calculation for small signal approximation.
- minima are formed which are completely in agreement between the numerical simulation and the analytical calculation. At the location of these minima, the frequencies corresponding to the data DSi become worse or no longer transferable.
- the depth of the minima depends on the discretization of the electrical signal ES ⁇ in the numerical simulation.
- the spectrum diagrams SDi from FIG. 6 are shown in FIG. 7, but with increasing to high channel powers and with complete dispersion compensation.
- a corresponding non-linear extension of the fiber transfer function was carried out.
- the curves for different channel powers 0, 5, 13, 15, 18 dBm are vertically shifted for clarity.
- the optical fiber used for the simulation is a 100 km long standard single-mode fiber with an additional 21.5 km long dispersion-compensating fiber DCF.
- the spectrum diagram is used for increasing channel outputs ever flatter and has a minimum below the first 10 GHz side line, especially with high channel powers, which reduces the usable data bandwidth. Above the 10 GHz sideline, the spectrum diagram also becomes flatter as the channel power increases.
- single channel effects of dispersion GVD and self-phase modulation SPM with small and high channel powers are determined by level splitting by occurrence of minima or deformation of the spectrum diagram SDi.
- a distinction between the two single channel effects GVD and SPM is not necessary, since the two effects work in opposite directions. When these effects occur, an attempt is made to achieve an adequate balance between the two effects in order to improve the data quality in the desired data bandwidth.
- FIG. 8 shows electrical spectrum diagrams for different crosstalk values ICC (no ICC, -20 dB, -8 dB) in a channel K x by means of a numerical simulation. The curves have been shifted vertically for clarification.
- the single-channel effect ICC does not change the spectrum diagram SDi int in contrast to GVD and SPM.
- the spectrum histogram SDi in which the crosstalk ICC is not determined in one channel, provides a means of separating the crosstalk ICC of GVD and SPM single channel effects.
- FIG. 9 shows the deterioration in the transmission quality with stimulated Brillouin scattering SBS.
- the fluctuation of the Q factor or known as the so-called Q-
- Penalty ⁇ (20 log Q), represented as a function of the attenuation D of the wearer.
- the Q factor can be derived directly from the amplitude histogram AHi can be determined.
- the Q penalty increases as the wearer's steam increases due to SBS. This can also be determined by narrower eye openings, in particular for small frequencies of the data DS below approximately 100 MHz. Therefore, the spectrum diagram SD ⁇ will have an attenuation of the lowest frequencies with the single channel effect SBS. Therefore, the single channel effect SBS can be determined and further separated from the other line effects GVD, SPM and ICC.
- the method according to the invention can be carried out on an already installed WDM transmission system during operation or during installation. Integration in a DWDM system and thus in its control concepts is also possible. In future systems, this invention offers control of adaptive dispersion or PMD compensation.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optical Communication System (AREA)
Abstract
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10132584 | 2001-07-05 | ||
DE10132584A DE10132584B4 (de) | 2001-07-05 | 2001-07-05 | Verfahren und Anordnung zur Ermittlung und Trennung von Einzelkanaleffekten bei der optischen Übertragung eines Wellenlängen-Multiplex(-WDM)-Signals |
PCT/DE2002/002473 WO2003005620A2 (fr) | 2001-07-05 | 2002-07-05 | Procede et dispositif de determination et de separation d'effets de canaux individuels lors du transfert optique d'un signal de multiplexage par repartition en longueur d'onde (wdm) |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1402670A2 true EP1402670A2 (fr) | 2004-03-31 |
Family
ID=7690699
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP02760083A Withdrawn EP1402670A2 (fr) | 2001-07-05 | 2002-07-05 | Procede et dispositif de determination et de separation d'effets de canaux individuels lors du transfert optique d'un signal de multiplexage par repartition en longueur d'onde (wdm) |
Country Status (4)
Country | Link |
---|---|
US (1) | US20040179837A1 (fr) |
EP (1) | EP1402670A2 (fr) |
DE (1) | DE10132584B4 (fr) |
WO (1) | WO2003005620A2 (fr) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4468656B2 (ja) | 2003-05-27 | 2010-05-26 | 株式会社日立製作所 | 信号波形劣化補償器 |
JP4629506B2 (ja) * | 2005-06-07 | 2011-02-09 | 日本オプネクスト株式会社 | 光受信モジュールおよび光受信モジュールシステム |
JP6048049B2 (ja) * | 2012-10-04 | 2016-12-21 | 富士通株式会社 | デジタルコヒーレント光受信器、その制御方法、及び伝送装置 |
US10686520B2 (en) * | 2015-11-26 | 2020-06-16 | Nippon Telegraph And Telephone Corporation | Transmission quality estimation system, transmission quality estimation device, and transmission quality estimation method |
US10469176B2 (en) * | 2017-07-07 | 2019-11-05 | Inphi Corporation | Histogram based optimization for optical modulation |
US10574391B2 (en) * | 2017-08-03 | 2020-02-25 | Facebook, Inc. | Adaptable forward error correction |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5666062A (en) * | 1994-09-19 | 1997-09-09 | Hamamatsu Photonics K.K. | Voltage measuring using electro-optic material's change in refractive index |
ATA799A (de) * | 1999-01-04 | 2000-10-15 | Rasztovits Wiech Michael Dipl | Messung der signalqualität in digitalen optischen glasfaserübertragungsnetzen durch auswertung des signalhistogramms |
DE19905814A1 (de) * | 1999-02-12 | 2000-08-17 | Deutsche Telekom Ag | Verfahren zur Überwachung der Übertragungsqualität eines optischen Übertragungssystems, insbesondere eines optischen Wellenlängenmultiplexnetzes |
US6665622B1 (en) * | 2000-01-19 | 2003-12-16 | Agilent Technologies, Inc. | Spectral characterization method for signal spectra having spectrally-separated signal peaks |
US6904237B2 (en) * | 2001-05-21 | 2005-06-07 | Siemens Aktiengesellschaft | Circuit for measurement of the signal quality in digital optical fiber transmission networks by interpreting the signal histogram |
US20040208515A1 (en) * | 2001-12-21 | 2004-10-21 | Edmund Walker | Signal to noise ratio measurement in a communications system |
-
2001
- 2001-07-05 DE DE10132584A patent/DE10132584B4/de not_active Expired - Fee Related
-
2002
- 2002-07-05 EP EP02760083A patent/EP1402670A2/fr not_active Withdrawn
- 2002-07-05 WO PCT/DE2002/002473 patent/WO2003005620A2/fr not_active Application Discontinuation
-
2004
- 2004-01-05 US US10/752,377 patent/US20040179837A1/en not_active Abandoned
Non-Patent Citations (1)
Title |
---|
See references of WO03005620A2 * |
Also Published As
Publication number | Publication date |
---|---|
US20040179837A1 (en) | 2004-09-16 |
DE10132584A1 (de) | 2003-01-23 |
WO2003005620A2 (fr) | 2003-01-16 |
DE10132584B4 (de) | 2004-02-05 |
WO2003005620A3 (fr) | 2003-06-26 |
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