CN105187119A - Method for identifying equidistant fault of passive optical network link based on optical time domain reflectometer - Google Patents

Abstract

The present invention discloses a method for identifying an equidistant fault of a passive optical network link based on an optical time domain reflectometer. Similarity analysis is carried out on a measured polymerized trace and a synthetic trace including a corresponding fault link, and a corresponding fault branch in an equidistant link is judged by calculating a Pearson correlation coefficient of the two traces. The method can effectively solve the problem of failing to distinguish the equidistant fault with a reflection peak referring analysis method in monitoring the passive optical network link in case that an original network topology is not changed. The method can be complementary with the reflection peak referring analysis method, thereby realizing that the optical time domain reflectometer finds and locates the fault without a blind area in a point-to-multipoint network rapidly and accurately.

Description

Based on the equidistant fault recognition method of EPON link of optical time domain reflectometer

Technical field

The invention belongs to technical field of optical fiber communication, relate to a kind of equidistant fault recognition method of EPON link based on optical time domain reflectometer in EPON.

Background technology

Along with the continuous upgrading of passive optical network capacity, the situation of the same communal facility of multiple users share also grows with each passing day.Meanwhile, user is also improving constantly the requirement of telecommunication service quality, and the maintenance and management problem of passive optical network optical link is become increasingly conspicuous.In the process of fixing a breakdown, how fast and accurately localizing faults becomes its problem first needing to solve.In recent years, the research of locating about EPON link failure have also been obtained to be paid close attention to widely and studies.

As everyone knows, in the monitoring of traditional point-to-point optical fiber link, optical time domain reflectometer is widely used.The backscattering that Rayleigh scattering when it mainly utilizes light signal to transmit in a fiber and Fresnel reflection produce and the electrical integrated instrument of precise light made are a kind of instruments can measured problems such as the decay of whole optical fiber link, fusion point, connector, bending or fractures.Its operation principle is similar to optical radar, and the luminous power spectrum returned by each point on optical fiber, is obtained the loss information of optical fiber link, and show with the form of trajectory diagram.The length of optical fiber link, the distance of link load and optical fiber attenuation and each fault, loss, disconnection and fiber strain state etc. can be obtained to the analysis of fibre system attenuation characteristic by optical time domain reflectometer.Because it is easy to use, practical, have very high accuracy, and there is non-destructive, widely use in optical fiber production, optical cable project construction and fiber optic cable maintenance work.But, in the EPON of tree structure, optical time domain reflectometer monitoring will run into point-to-multipoint problem, the back rayleigh scattering signal detected due to optical time domain reflectometer is the linear superposition of each branch road back rayleigh scattering signal, thus define multipath reflection, the test curve of optical time domain reflectometer accurately cannot be occurred on concrete branch road by localizing faults, thus lose monitoring effect.But, much proposed in a large number based on optical time domain reflectometer monitoring technique, and obtained application to a certain degree in passive optical network monitoring.Such as, based on the monitoring technology etc. of the optical time domain reflectometer monitoring technology of Single wavelength, tunable optical time domain reflectometer monitoring technology, Brillouin optical time-domain reflectometer monitoring technology and embedded optical time domain reflectometer.What be worth proposition is, reference reflection peak analytic approach is one comparatively simple effective method, the method is based on optical time domain reflectometer, introducing a reflector at each branch link is formed with reference to reflection peak, using the optical time domain reflectometer tracing waveform under each for EPON link health status as with reference to value, carried out the analysis of network state by the change of actual measurement reference reflection peak amplitude.Regrettably, this method requires that each branch link length can not be identical, otherwise there is the reference reflection peak that equal length link obtains will overlap, when fault occurs on equidistant link just, only cannot judge corresponding fault branch from geometric locus from each equidistant link.Thus also make this method be restricted in actual applications.

Summary of the invention

Technical problem: the invention provides a kind of can realization and the complementation with reference to reflection peak analytic approach in passive optical network monitoring, the reference reflection peak analytic approach made up based on optical time domain reflectometer is not suitable for the problem distinguishing equidistant link failure, realizes the equidistant fault recognition method of EPON link based on optical time domain reflectometer of quick, the accurate location to fault.The inventive method can be eliminated timely if optical fiber is due to bending, and the link performance that the faults such as fracture cause worsens and affects the hidden danger of proper communication.

Technical scheme: the equidistant fault recognition method of EPON link based on optical time domain reflectometer of the present invention, comprises the following steps:

1) acquisition of reference trace in each branch link in point-to-multipoint network, described reference trace comprises reference trace and the non-equidistant link reference trace of equidistant link;

2) generation of fault simulation trace in each equidistant link in point-to-multipoint network;

3) containing the generation of the fault simulation trace of equidistant link and the synthesis trace of non-equidistant link reference trace;

4) analyze data point in each synthesis trace and survey the similarity of being polymerized data point in trace with corresponding, using the link at maximum for similarity one group of corresponding data point place as the faulty link identified.

Further, described step 1) in obtain reference trace be when in point-to-multipoint network, each branch link is under normal communication state respectively, gathered separately the trace data of storage by optical time domain reflectometer successively, comprise the various event informations on link diverse location.

Further: described step 2) in generate fault simulation trace in the following manner:

First the abort situation point on the actual measurement trace collected according to optical time domain reflectometer, in described step 1) reference trace that obtains calculates the active loss W of branch link in fault point according to following formula _r:

$W_r=-5log\[N\left({10}^{\frac{-W_a}{5}}-1\right)+1\]$

Wherein, W _afor the display loss that branch link fault causes, be also the loss numerical value that optical time domain reflectometer can directly read, N is branch link sum in network;

And then by described active loss W _rthe fault simulation trace of each equidistant link under single connection state is simulated with the abort situation point on the actual measurement trace that optical time domain reflectometer collects.

Further, described step 3) in, containing in equidistant network, generate the fault simulation trace A of each equidistant link respectively by following formula _iwith non-equidistant link reference trace B each in network _jsynthesis trace C _i:

$C_i=10log\[\frac{1}{K}({10}^{A_i/10}+\mathrm{\Σ}{10}^{B_j/10})\];$

Wherein, K is link in network sum, and be equidistant number of links all in network and non-equidistant number of links sum, i is each equidistant link number, and j is each non-equidistant link number.

Further, described step 4) in each synthesis trace data point survey the similarity of being polymerized data point in trace with corresponding, be the Pearson correlation coefficient PCC according to following formula calculating:

$PCC=\frac{n\underset{m=1}{\overset{n}{\Σ}}{x}_m{y}_m-\underset{m=1}{\overset{n}{\Σ}}{x}_m\·\underset{m=1}{\overset{n}{\Σ}}{y}_m}{\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{x}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{x}_m\right)}^2}\·\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{y}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{y}_m\right)}^2}}$

Wherein, x _mfor described step 3) data point in the synthesis trace that generates, y _mfor the data point in actual measurement polymerization trace, m is data point sequence number, and n is number of data points.

Beneficial effect: the present invention compared with prior art, has the following advantages:

1, the present invention can directly calculate true loss by display loss, and then to generate fast in point-to-multipoint network fault simulation trace in each equidistant link, generative process is simple, directly deduct active loss value by the value of fault point and just can obtain fault simulation trace, can significantly raise the efficiency, for the real-time of network monitor provides guarantee;

2, the present invention when not changing legacy network topological structure, can solve optical time domain reflectometer in monitoring EPON, when fault occurs in equidistant optical link, is difficult to the problem which branch concrete occurs Judging fault.In network during non-equidistant link occurs fault, under its corresponding reflection peak relative health, there will be the situation of reduction; When there is equidistant link in network, and when fault just occurs in the equidistant link of one of them, carrying out differentiation and localizing faults place link and position by method provided by the invention, not being limited to the length restriction of each branch circuit link in network;

3, utilize Pearson correlation coefficient to do similarity analysis to actual measurement polymerization trace and synthesis trace, judged result can be provided more intuitively.By calculating each synthesis trace and surveying the Pearson correlation coefficient being polymerized trace, can draw by the value that correlation coefficient value is larger the synthesis trace that similarity is the highest, and then can obtain the concrete link of guilty culprit, deterministic process is very directly perceived.

Accompanying drawing explanation

Fig. 1 is the optical time domain reflectometer monitoring of structures figure containing equidistant optical link.

Fig. 2 is experimental verification schematic diagram.

Fig. 3 is reference locus figure.

Fig. 4 is actual measurement polymerization trace and synthesis trace diagram.

Embodiment

Below in conjunction with embodiment and Figure of description, the present invention is further illustrated.

First, in EPON as shown in Figure 1, there is equidistant optical link, as terminal optical network unit ONU ₁with ONU _n-1corresponding linkage length is equal, is L ₁, when fault occurs among these two links, the optical time domain reflectometer at place of central office cannot judge the concrete branch road that fault occurs.In order to verify the feasibility of proposed method in the present invention, experimental provision is built by shown in Fig. 2.In 1 × 4 network have a mind to the equidistant link L of setting two ₂=L ₄=2.22km, trunk optical fiber length L=1.01km, and difference analog link L ₂with L ₄by the result of calculation of this method gained during respective disconnection.

Reference trace is that in point-to-multipoint network, each branch link is in the data being gathered separately storage under normal communication state by optical time domain reflectometer successively respectively, as shown in Figure 3, and each linkage length L ₁, L ₂, L ₃and L ₄when being respectively 1.37km, 2.22km, 3.01km and 2.22km, the geometric locus under the health status that each link is corresponding, wherein each link fiber adopts the mode of end face reflection by direct impulse signal reflex light echo time-domain reflectomer.

The generation of fault simulation trace, by the reference trace obtained, chooses each equidistant link, respective links L in this confirmatory experiment respectively ₂and L ₄, the abort situation point on the actual measurement trace collected by optical time domain reflectometer, reference trace is calculated containing active loss W _rfault simulation trace.Concrete grammar is: the display loss W caused due to branch link fault on the polymerization trace of optical time domain reflectometer actual measurement _afollowing relation is there is at the active loss of fault point with branch link: the loss provided by optical time domain reflectometer can extrapolate the active loss of link, and then simulates the fault trace of respective links under single connection state.In this confirmatory experiment, simulated failure point occurs in L ₂and L ₄link is about 2.02km place, and the display loss produced by fibre-optical bending is respectively 0.487dB and 0.394dB, and its active loss is 3.53dB and 2.53dB.In conjunction with active loss, can simulate fault trace by corresponding reference trace, the data namely after reference trace fault point all deduct active loss value, and trace forms precipitous step-like distribution in fault point.

Generative process containing corresponding failure link-road synthesis trace is, by the fault simulation trace A of above-mentioned gained _iwith other link reference trace B in network _jsynthesis trace C is generated by following relation _i:

$C_i=10log\[\frac{1}{K}({10}^{A_i/10}+\mathrm{\Σ}{10}^{B_j/10})\]$

Wherein, K is link in network sum, is equidistant number of links all in network and non-equidistant number of links sum.

In this experimental verification, containing L ₂the synthesis trace of faulty link is by simulation L ₂fault trace and healthy L ₁, L ₃, L ₄reference trace is formed by stacking, containing L ₄the synthesis trace of faulty link is by simulation L ₄fault trace and healthy L ₁, L ₂, L ₃reference trace be formed by stacking.

With actual measurement, trace is polymerized to synthesis trace and does similarity analysis, be mainly: be designated as x by containing the data point in corresponding failure link-road synthesis trace _m, the data point of actual measurement polymerization trace is designated as y _m, wherein n by total number at peek strong point, utilize Pearson correlation coefficient (PCC) to do similarity by following formula to the two:

$PCC=\frac{n\underset{m=1}{\overset{n}{\Σ}}{x}_m{y}_m-\underset{m=1}{\overset{n}{\Σ}}{x}_m\·\underset{m=1}{\overset{n}{\Σ}}{y}_m}{\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{x}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{x}_m\right)}^2}\·\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{y}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{y}_m\right)}^2}}$

To being polymerized after trace does similarity analysis respectively with actual measurement containing corresponding synthesis trace, in each group of PPC value, choose maximum, the faulty link in corresponding synthesis trace is concrete fault branch.In this confirmatory experiment, on the corresponding geometric locus in strong point of peeking from fault point to the region of fault waveform end, when fault occurs in L ₂time in link, simulation L ₂the PCC value of the synthesis trace broken down is 0.9944, is greater than simulated failure and L occurs ₄pCC value 0.9737 in link; When fault occurs in L ₄time in link, simulation L ₄the PCC value of the synthesis trace broken down is 0.9969, is greater than simulated failure and L occurs ₂pCC value 0.9742 in link.It can thus be appreciated that the method successfully can identify that fault occurs in concrete fault branch in equidistant link.

Above-described embodiment is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention; some improvement and equivalent replacement can also be made; these improve the claims in the present invention and are equal to the technical scheme after replacing, and all fall into protection scope of the present invention.

Claims (5)

1., based on the equidistant fault recognition method of EPON link of optical time domain reflectometer, it is characterized in that, the method comprises the following steps:

1) acquisition of reference trace in each branch link in point-to-multipoint network, described reference trace comprises reference trace and the non-equidistant link reference trace of equidistant link;

2) generation of fault simulation trace in each equidistant link in point-to-multipoint network;

3) containing the generation of the fault simulation trace of equidistant link and the synthesis trace of non-equidistant link reference trace;

4) analyze data point in each synthesis trace and survey the similarity of being polymerized data point in trace with corresponding, using the link at maximum for similarity one group of corresponding data point place as the faulty link identified.

2. a kind of equidistant fault recognition method of EPON link based on optical time domain reflectometer according to claim 1, it is characterized in that, described step 1) in obtain reference trace be when in point-to-multipoint network, each branch link is under normal communication state respectively, gathered separately the trace data of storage by optical time domain reflectometer successively, comprise the various event informations on link diverse location.

3. a kind of equidistant fault recognition method of EPON link based on optical time domain reflectometer according to claim 1, is characterized in that: described step 2) in generate fault simulation trace in the following manner:

First the abort situation point on the actual measurement trace collected according to optical time domain reflectometer, in described step 1) reference trace that obtains calculates the active loss W of branch link in fault point according to following formula _r:

$W_r=-5log\[N\left({10}^{\frac{-W_a}{5}}-1\right)+1\]$

Wherein, W _afor the display loss that branch link fault causes, be also the loss numerical value that optical time domain reflectometer can directly read, N is branch link sum in network;

And then by described active loss W _rthe fault simulation trace of each equidistant link under single connection state is simulated with the abort situation point on the actual measurement trace that optical time domain reflectometer collects.

4. a kind of equidistant fault recognition method of EPON link based on optical time domain reflectometer according to claim 1,2 or 3, it is characterized in that, described step 3) in, containing in equidistant network, generate the fault simulation trace A of each equidistant link respectively by following formula _iwith non-equidistant link reference trace B each in network _jsynthesis trace C _i:

$C_i=10log\[\frac{1}{K}({10}^{A_i/10}+\mathrm{\Σ}{10}^{B_j/10})\];$

Wherein, K is link in network sum, and be equidistant number of links all in network and non-equidistant number of links sum, i is each equidistant link number, and j is each non-equidistant link number.

5. a kind of equidistant fault recognition method of EPON link based on optical time domain reflectometer according to claim 1,2 or 3, it is characterized in that, described step 4) in each synthesis trace data point survey the similarity of being polymerized data point in trace with corresponding, be the Pearson correlation coefficient PCC according to following formula calculating:

$PCC=\frac{n\underset{m=1}{\overset{n}{\Σ}}{x}_m{y}_m-\underset{m=1}{\overset{n}{\Σ}}{x}_m\·\underset{m=1}{\overset{n}{\Σ}}{y}_m}{\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{x}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{x}_m\right)}^2}\·\sqrt{n\underset{m=1}{\overset{n}{\Σ}}{y}_m^2-{\left(\underset{m=1}{\overset{n}{\Σ}}{y}_m\right)}^2}}$

Wherein, x _mfor described step 3) data point in the synthesis trace that generates, y _mfor the data point in actual measurement polymerization trace, m is data point sequence number, and n is number of data points.