Pulse testing device and pulse testing system

Abstract

A pulse testing device according to an embodiment of the present invention can be applied to an optical access network. The optical access network comprises optical fiber cores for individually connecting an in-station device and an in-home device for each user. Each of the optical fiber cores has an interposed marker for optical fiber core discrimination that indicates the unique response characteristics of the optical fiber core. The pulse testing device is equipped with a user identifier confirmation unit, an optical pulse test execution unit, a test result determination unit, and a database update unit. The user identifier confirmation unit queries a target in-home device to specify a user identifier assigned to the in-home device. The optical pulse test execution unit executes an optical pulse test on the optical fiber core connected to the target in-home device. The test result determination unit uses a result of the optical pulse test as a basis for determining identification information for the optical fiber core connected to the target in-home device. The database update unit uses the specified user identifier and the determined identification information for the optical fiber core as a basis for updating a database in which associations between optical fiber cores and users are retained by means of a table containing user identifiers and identification information for optical fiber cores.

Description

Pulse test equipment and pulse test system

[0001] One aspect of the present invention relates to a pulse test device and a pulse test system applicable to an optical access network.

[0002] Optical access networks are the last-mile infrastructure connecting telecommunications carriers and users (subscribers), and regular management and maintenance are essential. From the perspective of maintenance and operation, such as repairs, it is necessary to accurately know which optical fiber cable accommodates which user. For this reason, it is common to set up an equipment management database and manage the correspondence between optical fiber cables and accommodated users.

[0003] However, because inputting data into the database traditionally relied on manual labor, it was difficult to prevent data omissions and the inclusion of incorrect data due to mistakes. For example, when the optical fiber accommodating a user was changed during a repair, the maintenance staff might forget to register the change in the equipment management database, resulting in outdated equipment management data. Furthermore, there is a possibility that the equipment management data could be updated with incorrect information due to a maintenance staff member's misunderstanding or incorrect operation. In many cases, there is no other objective data available, making it impossible to verify the data by cross-checking. This often resulted in inaccurate data being left in the equipment management database, and a solution was needed.

[0004] "Optical fiber cable," [online], [searched March 5, 2024], Internet <URL: https: / / www.fujikura.co.jp / resource / pdf / opt_A.pdf> "Search method for optical fiber faults," NTT Technical Journal, October 2006, pp. 53-54

[0005] As long as the optical fiber of an optical access network is normal from the perspective of both the central office equipment and the customer premises equipment, it does not affect communications. Therefore, it is difficult to identify which optical fiber extending from the central office equipment a customer premises equipment is connected to. For this reason, with existing technology, the only way to manage the data (configuration information) used to manage which optical fiber a user is connected to is to register and update facility management data based on the recognition and operation of maintenance personnel. This makes it impossible to detect data errors introduced by work omissions, misidentifications, or operational errors, making it difficult to build an objectively reliable database. A solution to this problem was therefore desired.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a technique that enables error-free management of the association between optical cores and users in an optical access network.

[0007] The pulse test device of the embodiment can be applied to an optical access network. The optical access network includes optical fibers that individually connect an intra-office device and customer premises devices for each user. An optical fiber identification marker exhibiting a unique response characteristic is inserted into each optical fiber. The pulse test device includes a user identifier confirmation unit, an optical pulse test implementation unit, a test result determination unit, and a database update unit. The user identifier confirmation unit queries a target customer premises device to identify a user identifier assigned to the target customer premises device. The optical pulse test implementation unit performs an optical pulse test on the optical fiber connected to the target customer premises device. The test result determination unit determines identification information of the optical fiber connected to the target customer premises device based on the results of the optical pulse test. The database update unit updates a database that stores correspondence between optical fibers and users using a table including user identifiers and optical fiber identification information, based on the identified user identifier and the determined optical fiber identification information.

[0008] According to the present invention, it is possible to manage the association between optical cores and users in an optical access network without any errors.

[0009] FIG. 1 is a diagram illustrating an example of a pulse testing system according to an embodiment. FIG. 2 is a diagram illustrating an optical core cable discrimination marker. FIG. 3 is a diagram illustrating a unique response characteristic assigned to the optical core cable discrimination marker. FIG. 4 is a diagram illustrating an example of a received waveform in an optical pulse testing. FIG. 5 is a diagram illustrating an example of the appearance of an optical core cable discrimination marker on which decimal identification information is displayed. FIG. 6 is a functional block diagram illustrating an example of a pulse testing system according to an embodiment. FIG. 7 is a diagram illustrating an example of a state of an existing optical access system. FIG. 8 is a diagram illustrating an example of an equipment management database corresponding to the state of FIG. 7. FIG. 9 is a diagram illustrating an example of a state after an optical core cable has been replaced due to a fault. FIG. 10 is a diagram illustrating an example of an unupdated equipment management database. FIG. 11 is a diagram illustrating an example of an erroneously updated equipment management database. FIG. 12 is a diagram illustrating an example of a state after an optical core cable replacement work has been performed in an optical access network according to an embodiment. FIG. 13 is a diagram illustrating an example of a received light pattern obtained by an optical pulse testing. FIG. 14 is a diagram illustrating an example of the contents of the equipment management database 51 before an optical core cable replacement work has been performed. Fig. 15 is a diagram showing an example of the contents of the equipment management database 51 after core cable replacement work. Fig. 16 is a diagram showing an example of changes in the contents of the equipment management database 51 accompanying state transitions of optical core cables. Fig. 17 is a diagram showing an example of a sequence chart when an optical pulse test is performed in this embodiment.

[0010] 1 is a diagram illustrating an example of a pulse test system according to an embodiment. In FIG. 1, an intra-office device 20 is installed in, for example, a central office of a service provider. The intra-office device 20 is connected to a core network 30 of a telecommunications carrier and an optical access network.

[0011] The optical access network includes optical fiber cables 12 (#1 to #n) that individually connect an intra-office device 20 with each user's on-premises device (optical network unit: ONU). Here, the on-premises device 40 is, for example, an optical network unit loaned to each user by a service provider, and is assigned a unique user identifier in advance.

[0012] Furthermore, optical core line discrimination markers 120 are inserted along the optical core lines 12 (#1) to (#n) extending from the central office device 20 to each of the customer premises devices. Each optical core line discrimination marker 120 has a unique response characteristic. The pulse testing device 10 individually identifies the optical core lines on which the optical pulse test has been performed based on the unique response characteristic of the optical core line discrimination markers 120 along the optical core line.

[0013] In Fig. 1, the optical core line 12 (#1) is connected to the home device 40 (#1) of a first user. The optical core line 12 (#2) is connected to the home device 40 (#2) of a second user. The optical core line 12 (#3) is connected to the home device 40 (#3) of a third user. The optical core line 12 (#n) is a spare optical core line in preparation for a future failure.

[0014] 2 is a diagram illustrating an optical fiber discrimination marker. In FIG. 2, the optical fiber discrimination marker 120 includes a cover 123 and an optical fiber 124 that is bent and accommodated in an internal space 122 of the cover 123. The curvature of the optical fiber 124 is preferably kept within a range that does not affect optical communication. Both ends of the optical fiber 124 are connected to the optical fiber 12 at fusion points A and B.

[0015] FIG. 3 is a diagram illustrating the unique response characteristics imparted to the optical fiber identification marker. FIG. 3( a) shows the optical fiber 124 in a straightened state. At any position between fusion points A and B, optical signal attenuation characteristics can be imparted by, for example, changing the impurity doping ratio or applying bending stress. As shown in FIG. 3( b), four sections K1, K2, K3, and K4 of the same length (L) are set, and attenuation characteristics are imparted to sections K1, K2, and K4. By irradiating an optical pulse onto an optical fiber containing such an optical fiber identification marker and performing an optical pulse test, the return light shown in FIG. 3( b) is observed. If the return light pulse is set to "1" and the rest to "0," a bit "1" is observed in sections K1, K2, and K4, and a bit "0" is observed in section K3. This can be used directly as an identifier for this optical fiber. In other words, if "1101" is set as the response characteristic of this optical core discrimination marker, optical cores of 4 bits can be distinguished.

[0016] As shown in Figure 3(c), a bit "1" may always be set in section K1 to confirm the start position. In this case, the identifier section will be three bits, making it possible to distinguish eight optical fibers, a sufficient number for operational purposes. It is recommended to use "5," which is the decimal representation of binary "101," as the identification information for this optical fiber identification marker. The number of sections is not limited to four, and can be freely determined depending on the number of optical fibers hanging from the intra-office device 20 in the optical access network. In other words, the number of digits in the identification information can be increased or decreased as desired depending on the attenuation level of the optical signal, as long as it does not affect communication.

[0017] Optical pulse testing is a test that measures the state of an optical line by extracting "backward scattered light" that returns to the input side from the Rayleigh scattered light that occurs when an optical pulse is input into an optical fiber, and returned light due to "Fresnel reflection" that occurs due to a sudden change in refractive index at a connection point, etc. By measuring the elapsed time after inputting an optical pulse and the level of the returned light, it is possible to determine optical loss, the location of the connection point, and the location of a break.

[0018] When an optical access network is constructed, i.e., before operation, optical pulses with the same wavelength as those used for communications can be input. However, during operation, a dedicated optical wavelength set for testing is used to prevent optical interference.

[0019] 4A and 4B are diagrams showing examples of received waveforms in an optical pulse test. Assume that return light exhibiting the response characteristic R shown in FIG. 4B is observed from the optical core discrimination marker 120 shown in FIG. 4A. It is preferable to make the optical fiber 124 sufficiently long so that the waveform shown in FIG. 4B can be observed within the resolution range of the pulse test equipment 10.

[0020] 5 is a diagram showing an example of the appearance of an optical fiber discrimination marker on which decimal identification information is displayed. For example, by writing identification information corresponding to the response characteristics on the exterior of the case of the optical fiber discrimination marker 120, it is possible to provide convenience to workers on site.

[0021] 6 is a functional block diagram showing an example of a pulse test system according to an embodiment. In addition to the pulse test equipment 10, this system includes an equipment management system 50 and a maintenance operator terminal 60. The equipment management system 50 is, for example, a database (DB) constructed in a resource on a network and can be accessed from the pulse test equipment 10. The maintenance operator terminal 60 is, for example, a laptop computer or tablet, and can be carried by a maintenance operator on-site when repairing a malfunction. The maintenance operator terminal 60 communicates with the pulse test equipment 10 via a wireless or wired communication line, and can issue various commands and receive responses to instructions.

[0022] The equipment management system 50 includes an equipment management database 51. The equipment management database 51 stores a table including user identifiers and identification information of optical core lines, and uses this table to maintain the correspondence between optical core lines and users.

[0023] 6, the equipment management database 51 holds a correspondence between user identifier 1 and optical core line 1. This indicates that a user with user identifier 1 is accommodated by optical core line 1. Similarly, the equipment management database 51 manages that a user with user identifier 2 is accommodated by optical core line 2, and a user with user identifier 3 is accommodated by optical core line 3. Optical core line 4 is a spare core line.

[0024] The facility management database 51 must be updated every time the status of the optical access network changes. Below, we will explain a technology for automatically updating the facility management database 51 after identifying and specifying the optical core lines in use in the optical access network.

[0025] The pulse test device 10 includes, as functional blocks according to the embodiment, a user identifier confirmation unit 10a, a test result determination unit 10b, a pulse test unit 10c, a test execution unit 10d, an equipment management DB update unit 10e, and an update instruction receiving unit 10f. These functional blocks are realized by the pulse test device 10 serving as a computer executing a program.

[0026] The user identifier confirmation unit 10a sends an inquiry message based on, for example, a predetermined protocol to the home device whose correspondence with the optical fiber is to be confirmed, and decodes the response to identify the user identifier assigned to the home device. The pulse test unit 10c and the test execution unit 10d perform an optical pulse test on the optical fiber connected to the home device whose user identifier has been identified.

[0027] The test result determination unit 10b determines the identification information of the optical fiber connected to the customer's premises device based on the results of the optical pulse test. The equipment management DB update unit 10e accesses the equipment management database 51 in response to the results of the optical pulse test and updates the equipment management database 51 based on the identified user identifier and the determined identification information of the optical fiber. The update instruction receiving unit 10f receives instructions (commands) from the maintenance operator terminal 60 via the communication line and causes the test execution unit 10d and the pulse test unit 10c to perform an optical pulse test based on the received instructions.

[0028] Fig. 7 is a diagram showing an example of the state of an existing optical access system. The correspondence between optical cores and user identifiers in Fig. 7 is shown in Fig. 8. From this state, assume that user 3's home equipment breaks down as shown in Fig. 9, and replacement work is carried out with a new spare core. In this case, optical core 4 should be immediately associated with user identifier 3 in the equipment management database 51. However, with existing technology, due to a maintenance worker's forgetfulness, outdated data may be registered as shown in Fig. 10, or incorrect data may be registered as shown in Fig. 11.

[0029] 12 is a diagram showing an example of a state in which fiber re-routing work has been performed in the optical access network according to the embodiment. In FIG. 12, in order to recover from a fault, the accommodation of user 3 is changed to optical fiber 4, and an optical pulse test is performed by connecting pulse test equipment 10 to optical fiber 4. As a result, it is assumed that the pulse test result shown in FIG. 13 is obtained.

[0030] From the waveform pattern of the returned light, it can be seen that the identification information in Fig. 13 indicates "0100" in binary. That is, the result of the optical fiber identification marker portion of the pulse test result confirms connection to the optical fiber 4. In response to this result, the pulse test equipment 10 accesses the equipment management system 50 and updates the contents of the equipment management database 51. As a result, the equipment management database 51 is updated from the state before the work shown in Fig. 14 to the contents shown in Fig. 15 after the fiber replacement work, for example.

[0031] FIG. 16 illustrates an example of changes in the contents of the equipment management database 51 accompanying the state transition of an optical fiber. In the initial state of FIG. 16 , a new optical fiber is installed and registered in the equipment management database 51. Next, a user's home device 3 is connected to this optical fiber, and the user identifier is associated with the optical fiber's identification information, thereby updating the state of the equipment management database 51 (setting it to "in use"). If a failure or other problem occurs and construction is performed to change the optical fiber in use, the optical fiber that was in use is no longer reused and becomes unavailable ("final state"). Unlike metal cables, optical fibers that have been used to accommodate users are generally not reused. Therefore, the optical fiber irreversibly follows the state transition of FIG. 16 . By updating the equipment management database for optical fibers based on objective data and without relying on human judgment or input, it is possible to prevent update omissions and the inclusion of erroneous data due to input errors.

[0032] 17 is a diagram showing an example of a sequence chart when an optical pulse test is performed in the embodiment. In FIG. 17, it is assumed that optical fiber 3 has failed, and a maintenance worker has performed work to replace the home equipment of user 3 with optical fiber 4. In step (1) of FIG. 17, the maintenance operator operates maintenance operator terminal 60 to instruct the performance of an optical pulse test and the updating of equipment management database 51.

[0033] In step (2), the instruction is received by the update instruction receiving unit 10f of the pulse test device 10 via a network such as wirelessly. In step (3), the update instruction receiving unit 10f requests, based on the received instruction, to conduct a test and update the equipment management database 51. In step (4), the test conducting unit 10d requests confirmation of the user identifier to confirm the target user.

[0034] In step (5), the user identifier confirmation unit 10a requests the in-home device 3 to return the user identifier. In step (6), the in-home device 3 returns the user identifier (user identifier 3) to the source of the inquiry. In step (7), the user identifier confirmation unit 10a returns the confirmation result of the user identifier (user identifier 3) to the test implementation unit 10d.

[0035] In step (8), the test execution unit 10d requests the pulse test unit 10c to execute an optical pulse test. In step (9), the pulse test unit 10c executes the pulse test and obtains the results. In step (10), the pulse test unit 10c returns the results of the pulse test to the test execution unit 10d.

[0036] In step (11), the test execution unit 10d requests the test result determination unit 10b to determine the identification information of the optical core based on the results of the optical pulse test. In step (12), the test result determination unit 10b determines the identification information of the optical core, and in step (13), returns the determination result of the optical core identification information to the test execution unit 10d (optical core identifier 4).

[0037] In step (14), the test execution unit 10d uses the user identifier of the target user (user identifier 3) as a key to request the equipment management DB update unit 10e to obtain the current contents of the equipment management database 51. After steps (15), (16), and (17), the contents of the equipment management database 51 are returned to the test execution unit 10d (user identifier 3: accommodated optical fiber 3).

[0038] In step (18), the test execution unit 10d compares the pulse test determination result (user identifier 3: accommodated optical fiber 4) with the contents of the equipment management database 51 (user identifier 3: accommodated optical fiber 3) to check whether there has been an update. If it is confirmed in step (18) that there has been an update, in step (19), the test execution unit 10d requests the equipment management DB update unit 10e to update the equipment management database 51 with contents based on the pulse test result (user identifier 3: accommodated optical fiber 4).

[0039] In step (20), the facility management DB update unit 10e requests the facility management database 51 to update its contents (user identifier 3: accommodated optical fiber 4). In step (21), the facility management database 51 updates its contents (user identifier 3: accommodated optical fiber 4). Then, after steps (22) to (25), a completion response is returned to the maintenance operator terminal 60.

[0040] If there is no update in step (18), the test execution unit 10d outputs an alarm response, taking into consideration the possibility of an erroneous instruction from the maintenance operator. The alarm response is returned to the maintenance operator terminal 60 via steps (19') and (20'). The optical pulse test is performed through the above processing procedure, and the equipment management database 51 is updated based on the results.

[0041] Note that, for example, by transmitting and receiving a request signal and a response signal as optical signals using TCP / IP as a communication means, the communication with the in-home device 3 in steps (5) and (6) can be realized. Of course, this is not limiting and other communication means may also be used.

[0042] As described above, in the embodiment, an optical access network is constructed by connecting the optical core line identification marker 120 to the optical core line in advance, and a pulse test is performed by irradiating the optical core line with an optical pulse. The optical core line being used is identified based on the characteristics of the optical core line discrimination marker that appear in the test results. Here, the optical core line identification marker 120 is set so that it can be determined whether or not there is attenuation over a short distance within the resolution range of the pulse test device.

[0043] Next, the identifier of the user who changed the accommodation of the in-home device 3 is obtained from the in-home device 3, an optical pulse test is performed on the optical core line leading to the in-home device 3, and optical core line identification information is determined from the result. In addition, the corresponding accommodation optical core line identification information is obtained from the equipment management database 51 using the user identifier as a key.

[0044] The determined optical core identification information is compared with the acquired optical core identification information, and if there is an update, the contents of the equipment management database 51 are updated to the determined optical core identification information. If there is no update, an alarm is output, taking into consideration the possibility that the user who changed the accommodation of the in-home device 3 made an error in specifying the optical core identification information.

[0045] This processing prevents data errors from being introduced due to omissions, misidentifications, or operational errors by maintenance personnel, etc., and makes it possible to accurately determine which optical fiber cable accommodates which user. As a result, according to the embodiment, it is possible to provide a technology that can accurately manage the association between optical fibers and users in an optical access network.

[0046] It should be noted that the present invention is not limited to the above-described embodiments, and that the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0047] 3...In-house device 4...Optical core cable 10...Pulse testing device 10a...User identifier confirmation unit 10b...Test result determination unit 10c...Pulse testing unit 10d...Test implementation unit 10e...Facility management DB update unit 10f...Update instruction receiving unit 12...Optical core cable 20...In-station device 30...Core network 40...In-house device 50...Facility management system 51...Facility management database 60...Maintenance operator terminal 120...Optical core cable discrimination marker 122...Internal space 123...Cover 124...Optical fiber.

Claims

1. A pulse testing device applicable to an optical access network having optical core lines that individually connect an intra-office device and each user's home device, and optical core line identification markers that are inserted into each optical core line and show unique response characteristics, the pulse testing device comprising: a user identifier confirmation unit that queries a target home device to identify a user identifier assigned to the target home device; an optical pulse test implementation unit that performs an optical pulse test on the optical core lines connected to the target home device; a test result determination unit that determines identification information of the optical core lines connected to the target home device based on the results of the optical pulse test; and a database update unit that updates a database that maintains correspondence between optical core lines and users using a table containing user identifiers and identification information of optical core lines based on the specified user identifier and the determined identification information of the optical core lines.

2. The pulse testing device according to claim 1, further comprising an update instruction receiving unit that receives an instruction from a maintenance operator terminal via a communication line and causes the optical pulse testing unit to perform the optical pulse test based on the instruction.

3. A pulse testing system applicable to an optical access network having optical core lines that individually connect an intra-office device and a customer premises device for each user, comprising: a database that stores correspondence between the optical core lines and the users; optical core line identification markers that are inserted into each optical core line and show unique response characteristics; and a pulse testing device, wherein the pulse testing device comprises: a user identifier confirmation unit that queries a target customer premises device to identify a user identifier assigned to the target customer premises device; an optical pulse testing unit that performs an optical pulse test on the optical core lines connected to the target customer premises device; a test result determination unit that determines identification information of the optical core line connected to the target customer premises device based on the result of the optical pulse test; and a database update unit that updates the database that stores correspondence between optical core lines and users using a table including user identifiers and identification information of the optical core lines based on the specified user identifier and the determined identification information of the optical core lines.

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