CN1694382A - Optical protection exchange method based on quick adjustable coherent receiver - Google Patents
Optical protection exchange method based on quick adjustable coherent receiver Download PDFInfo
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- CN1694382A CN1694382A CNA2005100265978A CN200510026597A CN1694382A CN 1694382 A CN1694382 A CN 1694382A CN A2005100265978 A CNA2005100265978 A CN A2005100265978A CN 200510026597 A CN200510026597 A CN 200510026597A CN 1694382 A CN1694382 A CN 1694382A
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Abstract
An optical protection exchange method of a quick adjustable coherent receiver used in fiber communication system and network includes the following steps: 1. A source node sends data to a working wavelength path and a protection wavelength path via two or more than two different wavelengths. 2. The wavelengths are routed to the adjustable receiver light port at the destination node. 3. Once the destination node detects the fault of the working path, the receiver is switched to the protection path at once to realize quick protection of 1+1.
Description
Technical field
What the present invention relates to is a kind of method of communication technical field, particularly a kind of method based on the light of quick adjustable coherent receiver protection exchange that is applicable to optical fiber telecommunications system and network.
Technical background
In carrier class network, because the needs of its business are wanted and can be reached more than 99.9999% the requirement of network reliability.Like this, the survivability problem of network just becomes a major issue in the network design.The protection of light path and recovery then play a part very crucial to the survivability of network.Along with the raising of optical transmission system speed, the data capacity that single wavelength channel can carry also from before hundreds of million or several Gigabits per second be increased to tens lucky even Gigabits per seconds up to a hundred.Even quite the network of short time interrupts all can causing great data degradation under this speed, bring very serious data to lose and service disconnection for whole network.So now protection is had higher requirement switching time, the 1+1 path protection mode that adopts can not adapt to present needs in the past, and it is the inevitable choice that addresses this problem that the protection of nanosecond order even magnitude of subnanosecond recovers.
The two kinds of methods that adopt existing 1+1 protection realize the switching of working light path and protection light path.A kind of be with two paths of signals all receiving demodulation get off, on electricity, realize to switch then.Though this method can increase receiving the defencive function of fault; but relate to change action between complicated plate when switching owing to protect; so generally need the switching time more than the millisecond magnitude, this method has also increased expensive electrical interface in addition, has improved difficult in maintenance and expense.Another kind method does not adopt electric backup method, but uses optical switch before optical receiver.Change action by optical switch when fault takes place is switched to protection light path received signal.As Chinese patent " the dynamically synchronous switching protection of optical link " (03254764.1) and Chinese patent " node protector for changover ring of wave division multiplexing circuit " (01109025.1) is to adopt optical switch to finish the light path protection to switch.Though this method has overcome the part shortcoming of electric backup method, because now commercial optical switch mainly is based on the mode of mechanical switch or micro-machinery switch, their switching time also can only be several milliseconds to tens of milliseconds magnitudes.Even adopt photoelectricity optical switch fast, but, will finally limit the transmission range of light path, reduce signal transmission quality because they have introduced extra insertion loss.
In order to overcome the shortcoming of these guard methods, a kind of feasible method is to adopt adjustable reception to realize the selection switching of channel at receiving terminal.Common adjustable receiver is also prematurity technically, does not also have the commercialization of reliable nanosecond tunable filter, and still needs the magnitude of tens of nanoseconds switching time.This invention proposes to adopt relevant adjustable method of reseptance to be used for network protection.Coherent receiver has extraordinary channel selectivity characteristic and quick switching characteristic; the channel that studies show that coherent reception that we are nearest is mainly determined by the wavelength regulation time of local oscillations light source and the intermediate-frequency bandwidth of coherent receiver switching time; have the ability to be less than the magnitude of 1 nanosecond by improving Fast Adjustable local oscillator light source, thereby realize fastest protection switching.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art; the method of the outer light protection of a kind of band based on quick adjustable coherent receiver exchange is provided; make it can improve flexibility and success rate that light protection path is set up; simultaneously greatly reduce to switch loss of data and the service disconnection that causes, the no error code protection of final realization exchange.
The present invention is achieved by the following technical solutions, the present invention includes following steps:
1. by source node data are sent to operation wavelength path and protection wavelength path respectively by two or more different wavelength;
2. be routed to adjustable receiver optical port simultaneously at these wavelength of destination node;
In case 3. destination node detects the operating path fault, receiver switches to the protection path immediately, realizes 1+1 protection fast.
Described wavelength, network are routed to destination node with these optical wavelength independently.
Described destination node; adopt adjustable coherent receiver to receive data; when operating path just often; receiver receives from operating path; when destination node detects fault happens in operational; adjustable receiver switches to protection passage reception data fast by changing the local oscillator optical wavelength, finishes the protection exchange.Destination node comprises a high speed fault-sensing circuit, and it detects and will trigger the switching action of receiver rapidly after fault takes place.
Described adjustable receiver, its local oscillations optical signal source is made of the adjustable multi-wavelength laser, and its output wavelength can realize selecting fast by quick electric separation messenger.
Described 1+1 protection, source node sends to operation wavelength path and protection wavelength path with data respectively by two or more different wavelength: when the protection wavelength is one, be 1+1 protection, when the protection wavelength is N, be N+1 protection.These different wavelength can not required to have or not the common edge restriction between them by the difference route.
Described source node; its transmitting terminal adopts multifrequency laser; use the laser inner modulation or use external modulator; as Mach-Zehnder or electroabsorption modulator etc.; data are modulated on these multi-wavelengths simultaneously; in these wavelength one is sent on the operating path as operation wavelength; its commplementary wave length will be sent on the protection path for the protection wavelength; after wavelength is modulated; by the Wavelength branching device these wavelength are spatially separated; as thin dielectric film filter or tapered fiber splitter etc., can adopt array waveguide grating when wavelength is more, these wavelength can be routed to destination node independently of one another by optical-fiber network.Because different wavelength is adopted with operating path in the protection path, these wavelength can not interfere with each other by the same optical fiber link in the network.
So be called the outer protection of band based on the difference on this wavelength; guard method is in the band: adopt same wavelength to be used for protection; its protection path and operating path wavelength are mutually exclusive; can not be via same optical fiber link; it also requires to have at least two idle optical fiber links to be connected to the source and destination node simultaneously, and promptly so-called dual homed connects.So the outer guard method of band of the present invention can be avoided these restrictions, thereby increase the flexibility of protection path route.
In described destination node, operating path light signal and protection path light signal are input to the input of Fast Adjustable receiver simultaneously, and adjustable receiver adopts coherent reception method.Typical coherent reception method can adopt heterodyne reception or homostrobe mode.Coherent reception method has avoided using before receiver mechanical optical switch to switch, and can only reach the 10ms magnitude its typical switching time.Use the coherent reception mode, the switching of interchannel is switched realization by the local oscillator optical source wavelength, typically can adopt the nanosecond tunable laser, the array laser of electric absorption multifrequency laser or photoelectric effect optical switch control fast etc. are lower than 1ns the typical switching time of these lasers.
Final optical channel receives the intermediate frequency filtering bandwidth decision of the time of switching by the switch speed and the receiver of local oscillations light, is less than 1ns.Local oscillations is switched by the high speed fault-sensing circuit and is triggered, the monitoring light signals quality, and make threshold triggers with it, and threshold value is located near the receiver sensitivity, and in a single day signal quality is lower than threshold value and sends switching signal to adjustable receiver immediately.
The present invention uses the outer guard method of band, can improve flexibility and success rate that light protection path is set up.The employing of fast switch over method has simultaneously significantly improved protection swap time, thereby greatly reduces to switch loss of data and the service disconnection that causes, thereby finally has the ability to realize that no error code protection exchanges.The present invention utilizes the transmission range difference (supposing to protect the path to be longer than operating path) of two paths; in transmission time delay difference, realize the protection switching; thereby realize reliably no error code protection exchange, this provides the business of high service quality to have great importance for the reliability that improves network.
Description of drawings:
The quick optical protection exchange method schematic diagram of Fig. 1 the present invention
Fig. 2 multi-wavelength transmitter implementation method schematic diagram
Fig. 3 realizes the method schematic diagram of protection exchange fast at receiving terminal
Fig. 4 quick adjustable coherent receiver implementation method schematic diagram
Embodiment
In the optical-fiber network of one 8 node, as shown in Figure 1, optical node interconnects the composition network by optical fiber link.Need to set up a light path and protection light path thereof between source node and destination node.Source node adopts a multi-wavelength transmitter that data are sent on a plurality of wavelength, and wherein one is operation wavelength, and other wavelength are the protection wavelength, and according to protection number of wavelengths N, its guard method is called N+1 protection, and what show among the figure is the 1+1 protection pattern.
The embodiment of multi-wavelength transmitter as shown in Figure 2.Laser array output links to each other with the wavelength mixer, and the output of mixer is connected to external modulator, and external modulator output links to each other with the Wavelength branching device.Laser array is launched the continuous light wave (adopting two laser JDSU CQF935/208 and SUMITOMOSLT5411 at 1+1 protection) of N+1 wavelength, is merged to deliver in the external modulator by the wavelength mixer and (adopts quick lithium niobate Mach-Zender optical switch JDSU 15Gb/s Modulator).External modulation is modulated to data on this N+1 wavelength simultaneously.Each modulated light wave is spatially separated to send to each different light path by the Wavelength branching device.
After two wavelength went out transmitter, operation wavelength sent to working light path and directly transmits, and the protection wavelength sends to the transmission of protection light path.Two paths are routed to destination node jointly via different intermediate nodes, can allow path overlap between them.In general, in order to improve protection efficient, two paths should arrive destination node via different optical fiber links as far as possible.So traditional protection adopts same wavelength to be used for the protection transmission usually, but such method has increased very big restriction also for the route in these paths, and as no common edge, the source and destination node has at least plural optical link to link to each other or the like with network.In mesh network topologies, especially logical topology is compared with initial design when altering a great deal under the dynamic bandwidth supply conditions, and these restrictive conditions are not easy to be satisfied.The present invention adopts different wavelength to be used for the protection transmission; be called the outer guard method of band; it can allow them overlapping at low dangerous optical fiber link, thereby improve flexibility and success rate that the protection path is set up finding and operating path altogether during the light path on limit.
In order to improve the speed of switching of protection exchange, the present invention adopts quick adjustable coherent receiver at receiving terminal.Fig. 3 realizes the embodiment of protection exchange fast at receiving terminal.Two path light signals link to each other with optical branching device, the main luminous power output of splitter links to each other with optical combiner, optical combiner output links to each other with optical mixer unit light one input, and splitter accidental light power take-off links to each other with the optical monitoring signal module, but its output is connected to bar lasing light emitter fast.The output of tunable laser source is connected to optical mixer unit, and mixing output connects the relevant receiver of light.In destination node, working light path footpath signal and protection light path signal are merged the input of delivering to receiver together by optical combiner.By optical branching device the small part luminous power is separated from two ways of optical signals, delivered to the variation that the optical monitoring signal module is monitored signal quality in the optical link in real time, thus the generation of failure judgement.The implementation method of malfunction monitoring is to adopt the threshold triggers method fast, and threshold value is located near the receiver sensitivity, and signal quality one is lower than threshold value and sends the wavelength switching signal to the Fast Adjustable local oscillator light source of adjustable receiver immediately.The output of Fast Adjustable local oscillator light source is sent into light coherent receiver by optical mixer unit with input signal light after realization on the light mixes.Light coherent receiver is only surveyed the mixing light signal that is in same wavelength channel with the local oscillator light source.After the fault of operating path is detected by the optical monitoring signal module; the Fast Adjustable light source will be received the protection switching signal; tunable light source response fast is adjusted to the protection wavelength channel with output light wavelength, thereby coherent receiver will realize that protection is switched at a high speed from corresponding protection channel reception data like this.
Shown in Figure 4 is a kind of specific implementation method of quick adjustable coherent receiver.It is the specific embodiment of adjustable local oscillator light source and light coherent receiver among Fig. 2.Adjustable local oscillator light source is accepted the signal from the optical monitoring signal module, selects module through amplifier (JDSU H301 bandwidth 75kHz-10GHz gain ~ 26dB) be connected to quick electrooptical switching (example adopts quick lithium niobate Mach-Zender optical switch JDSU 15Gb/s Modulator) to realize control by channel.Working channel and protection channel local oscillator light source (JDSU CQF935/208 and SUMITOMO SLT5411) output are connected to the light input end of optical switch, and the light output end of optical switch is connected to photomixing.Its another input receiving optical signals.The output of optical mixer unit is connected to direct sunshine strong receiver (Multiplex MTRX192L BW ~ 10GHz), transfer to and be connected to amplifier (JDSU H301 bandwidth 75kHz-10GHz gain ~ 26dB) behind the signal of telecommunication, amplifier output links to each other with intermediate-frequency filter (bandwidth 6.5-15GHz), the signal of telecommunication of output is divided into two-way and is connected to electric frequency mixer (intermediate-frequency bandwidth 6-18GHz, output DC-3GHz), frequency mixer output is connected to low pass filter (bandwidth DC-4GHz), outputs at last that clock picks up and decision circuit.This adjustable receiver is worked by the following method; when needs select service aisle to receive, the state that the switch of service aisle is in out, the state that is in the pass of protection passage; then opposite when needs are selected the Data Receiving of protection passage, export the local oscillator light of certain channel by these Action Selection.The direct sunshine strong receiver receives mixed light signal, and example adopts the luminous intensity receiver of integrated amplifier.By amplifier the electric high frequency signal that receives is amplified to suitable amplitude.By the unnecessary low frequency signal of intermediate-frequency filter filtering, only by needing the intermediate-freuqncy signal of reception.The output of intermediate frequency filtering obtains the low-frequency oscillation component through frequency mixer.The intermediate frequency and the higher-order of oscillation that is disturbed by low pass filter filters out again obtains the low frequency signal after the demodulation.Clock picks up and decision circuit, is 0 and 1 digital bit stream of forming with the analog waveform correct interpretation.When protecting switching, the bit stream phase place of two channels is normally nonsynchronous, so need adopt the supper-fast phase locking of clock pick-up circuit realization fast to reach correct data demodulates purpose.The rising and falling edges of local oscillations switching optical path is 0.6ns in our experiment, obtains behind intermediate frequency filtering＜channel switching time of 0.8ns, and we remain the two paths of signals Phase synchronization in the experiment.
The physical exchange speed of two channels finally is received the intermediate-frequency bandwidth restriction of machine.Because intersection existence SPA sudden phase anomalies at random in the switching of two-way intermediate-freuqncy signal.Behind intermediate frequency filtering, will produce a transition region that is inversely proportional to bandwidth.The amplitude of supposing two intermediate frequencies (IF) is A
1=A
2=A, frequency is ω
1=ω
2=ω
c, phase place is respectively
1And
2, that is:
IF
1(t)＝Aexp[j(ω
ct+
1)]
IF
2(t)＝Aexp[j(ω
ct+
2)]
The function of time of vibration can be written as:
f(t)＝Aexp(jω
ct)u(t)(expj
1-expj
2)+Aexp[j(ω
ct+
2)]
Make K=A (expj
1-expj
2), its Fourier transform is:
U (t) is a step function:
After intermediate-frequency filter H (ω) filtering, (
ω
fBe filter by half of bandwidth), behind inverse fourier transform, can obtain final r time response (t):
Function
When t → ± ∞,
Its rising edge is 2 π.
When the SPA sudden phase anomalies of two intermediate frequencies is a maximum, as
1=0,
2=π, K=2A at this moment, the amplitude of r (t) will experience a width and be
The exchange transition region, wherein B is the intermediate-frequency filter bandwidth.Suppose that intermediate-frequency bandwidth is 4GHz, then the rise time is t
r=0.5ns.If intermediate-freuqncy signal itself has a rising and falling edges, it equals limited switching time of the t of local oscillator
s, so final channel determines T＜t jointly by these two times switching time
s+ t
rSo can reduce light path protection switching time switching time by increasing local oscillator, but it is subjected to limited intermediate frequency filtering bandwidth constraints the most at last.
Claims (9)
1. the method for the outer light protection of the band based on a quick adjustable coherent receiver exchange is characterized in that, may further comprise the steps:
1. by source node data are sent to operation wavelength path and protection wavelength path respectively by two or more different wavelength;
2. be routed to adjustable receiver optical port simultaneously at these wavelength of destination node;
In case 3. destination node detects the operating path fault, the path is protected in switching to immediately of receiver, realizes 1+1 protection fast.
2. the method for the outer light protection of the band based on quick adjustable coherent receiver as claimed in claim 1 exchange is characterized in that described wavelength, network are routed to destination node with these optical wavelength independently.
3. as claim 1 or 2 described methods based on light protection exchange outside the bands of quick adjustable coherent receiver; it is characterized in that; described destination node; adopt adjustable coherent receiver to receive data; when operating path just often, receiver receives from operating path, when destination node detects fault happens in operational; adjustable receiver switches to protection passage reception data fast by changing the local oscillator optical wavelength, finishes the protection exchange.
4. as claim 1 or 2 described methods based on light protection exchange outside the bands of quick adjustable coherent receiver; it is characterized in that; described destination node; be input to the input of Fast Adjustable receiver simultaneously at its operating path light signal and protection path light signal, adjustable receiver adopts coherent reception method.
5. as claim 1 or 3 described methods based on light protection exchange outside the bands of quick adjustable coherent receiver; it is characterized in that; described adjustable receiver; its local oscillations optical signal source is made of the adjustable multi-wavelength laser, and its output wavelength can realize selecting fast by quick electric separation messenger.
6. the method for the outer light protection of the band based on quick adjustable coherent receiver as claimed in claim 1 exchange; it is characterized in that; described 1+1 protection; source node sends to operation wavelength path and protection wavelength path with data respectively by two or more different wavelength: when the protection wavelength is 1, be 1+1 protection.
7. as claim 1 or 6 described methods based on light protection exchange outside the bands of quick adjustable coherent receiver; it is characterized in that; described source node; its transmitting terminal adopts multifrequency laser; use the laser inner modulation or use external modulator; data are modulated on these multi-wavelengths simultaneously; in these wavelength one is sent on the operating path as operation wavelength; its commplementary wave length is sent on the protection path for the protection wavelength; after wavelength is modulated; by the Wavelength branching device these wavelength are spatially separated, because different wavelength is adopted with operating path in the protection path, these wavelength can not interfere with each other by the same optical fiber link in the network.
8. as claim 1 or 3 described methods based on light protection exchange outside the bands of quick adjustable coherent receiver; it is characterized in that; described switching, final optical channel receive the intermediate frequency filtering bandwidth decision of the time of switching by the switch speed and the receiver of local oscillations light, less than 1ns.
9. the method for the outer light protection of the band based on quick adjustable coherent receiver as claimed in claim 8 exchange; it is characterized in that; described local oscillations; its switching is triggered by the high speed fault-sensing circuit; the real time monitoring optical signal quality; and setting threshold, signal quality one is lower than threshold value and sends switching signal to adjustable receiver immediately.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2343840A1 (en) * | 2010-01-12 | 2011-07-13 | Alcatel Lucent | Method, device and optical node for coherent reception of an optical signal |
| CN101741703B (en) * | 2008-11-25 | 2012-01-25 | 华为技术有限公司 | Method and system for realizing multi-service transmitting network transmission channel |
| CN101552641B (en) * | 2008-04-01 | 2012-04-11 | 富士通株式会社 | Frequency difference monitoring device and method used in digital coherent light receiver |
| CN104811238A (en) * | 2014-01-28 | 2015-07-29 | 中兴通讯股份有限公司 | Channel switching method, device, optical network unit and time-wavelength division multiplexing system |
-
2005
- 2005-06-09 CN CNA2005100265978A patent/CN1694382A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101552641B (en) * | 2008-04-01 | 2012-04-11 | 富士通株式会社 | Frequency difference monitoring device and method used in digital coherent light receiver |
| CN101741703B (en) * | 2008-11-25 | 2012-01-25 | 华为技术有限公司 | Method and system for realizing multi-service transmitting network transmission channel |
| EP2343840A1 (en) * | 2010-01-12 | 2011-07-13 | Alcatel Lucent | Method, device and optical node for coherent reception of an optical signal |
| CN104811238A (en) * | 2014-01-28 | 2015-07-29 | 中兴通讯股份有限公司 | Channel switching method, device, optical network unit and time-wavelength division multiplexing system |
| CN104811238B (en) * | 2014-01-28 | 2019-05-07 | 中兴通讯股份有限公司 | The timely partial wave division multiplexing system of passageway switching method, device, optical network unit |
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