EP1118202A1

EP1118202A1 - Method for testing subscriber lines

Info

Publication number: EP1118202A1
Application number: EP99969872A
Authority: EP
Inventors: Svend Christensen; Ulrich LIEFLÄNDER; Franz SCHMÖLLER; Ludwig Dirscherl; Hans-Werner Rudolf
Original assignee: Siemens AG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 1998-09-30
Filing date: 1999-09-27
Publication date: 2001-07-25
Also published as: JP2002526987A; CA2345676A1; US7286952B1; CN1143507C; BR9914214A; CN1328741A; JP4082867B2; WO2000019690A1

Abstract

According to the invention, the testing is decentralised, and is carried out online and almost permanently, with the help of the digital processor of the subscriber line. The test results are collected at a central point and from there, are signalled to particular locations on the subscriber access network when necessary, e.g. to a distributor node on which maintenance work is being carried out.

Description

description

Procedure for testing subscriber lines

The invention relates to a method for testing subscriber lines, including the associated subscriber line circuit and connected subscriber terminal of a digital telecommunications system.

So far, the testing of subscriber connections has mainly been carried out with the aid of central test facilities, which are activated by establishing a test connection for the subscriber connection concerned. This means that such tests are routinely only carried out at longer intervals of the order of weeks or even months. In practice, this means that a very high percentage of errors that occur are determined by customer complaints, which, depending on the type of error, are often delayed compared to the first time an error is detected. The organization of troubleshooting as quickly as possible is thus made considerably more difficult.

However, it is also already known to use this digital signal processor for evaluating line parameters and thus for carrying out tests for subscriber line circuits whose functions are at least partially implemented using a digital signal processor (European patent application 0 451 759 A3). In the known solution, access points to the transmission branch and the reception branch of the subscriber line are created for this purpose, at which voltages occur during operation of the subscriber line circuit, which are evaluated in different combinations to produce a specific test result. The testing of subscriber line circuits is therefore decentralized and can take place online.

Because of the performance of modern digital signal processors, full utilization by implementing the functions of the subscriber line is far from being available.

It is therefore possible with the known test concept mentioned to carry out a plurality of different test functions in a quasi-permanent and automatic manner in order to detect functional errors. Quasi-permanent describes the deviation from a permanent test determination, which results on the one hand from the fact that a digital signal processor, as mentioned, has another main task in this context and, on the other hand, that it is responsible for a plurality of subscriber connections, if necessary individual connections are then only available in time-division multiplex mode.

With such integrated test systems, errors in the subscriber access area can generally be recognized and, depending on the type of error, may already be remedied before they have been noticed by the customer.

The object of the invention is now to further increase the customer benefit by taking advantage of the possibilities of such an integrated test concept.

This object is achieved by a method according to patent claim 1.

Accordingly, the test result data, which is determined decentrally in the known manner, is collected at a central location, taking into account specific selection criteria, and is transmitted to specific locations in the subscriber line area to which the subscriber line belongs, in specific needs. Using the method according to the invention, the function tests can be carried out on a single subscriber line in minutes.

Further refinements of the invention are characterized in the subclaims.

According to claim 2, test result data collected at a central point are transmitted to the location at which interference suppression measures are currently being carried out, provided that they relate to the geographic area of interest. This measure brings advantages in the case of interference suppression or maintenance measures in which there is a risk of causing interference on neighboring subscriber lines, for example in the case of shunting measures. If the maintenance technician has test result data available immediately after the routing of a subscriber connection line in a distribution box, which relates to the other subscriber connection lines accessible in this distribution box and which are also up-to-date because of the quasi-permanent check according to the invention, such subsequent errors can be recognized and immediately rectified again.

According to claim 3, in the transmission of test result data to the place of execution of the interference suppression measure, preferably in addition to the geographical limitation, a time restriction is also made to such test result data that were created in close proximity to the execution of the measure at the fault location. In this way, a possible causal connection between the interference suppression measure and the subsequent error can be recognized even better.

According to claim 4, it is provided that affected telecommunications subscribers are to be sent an error signal on the occasion of the establishment of a telecommunications connection and thus alert the subscriber to a malfunction before he has ascertained this himself. According to claim 5, such a signaling can take place with an outgoing telecommunications connection during the occurrence of the dial tone.

According to claim 6, incoming telephony connections can provide information about the presence of a malfunction in the form of an announcement, for which purpose a conference connection is established.

The invention is explained in more detail below on the basis of an exemplary embodiment, reference being made to a drawing.

The drawing shows:

1 shows the block diagram of a telephone switching system in which the line test is carried out centrally,

FIG. 2 shows a corresponding representation of a telephone switching system in which the line test is carried out in the manner according to the invention.

In FIG. 1, a so-called digital subscriber line unit DLU, a line trunk group LTG, a central switching network SN, and a central coordination processor CP are shown as essential components of a telephone switching system.

Subscriber lines TL are connected to the digital subscriber line unit DLU and connect to subscriber terminals, not shown here. In practice, this can be up to 1000 lines. Furthermore, connecting lines for connection to private branch exchanges can also be connected, for which the same applies with regard to the use of the method according to the invention, but which are not mentioned further below. The subscriber lines open in the digital subscriber line unit DLU in subscriber line-specific subscriber line circuits SLC. In the present case, 16 such subscriber line circuits are combined to form a subscriber line module SLMA.

In practice, there are a large number of such digital subscriber line units. They can be offset or arranged in the vicinity of the exchange. In an implemented embodiment, they are connected to two of the line groups LTG for security reasons.

A common measuring device MK is provided for centralized testing of the subscriber lines TL mentioned, together with the subscriber terminals connected to them and the line-specific subscriber line circuits SLC. The optional connection of this measuring device to the above-mentioned subscriber-specific components takes place via a coupler module KG of the digital line unit DLU.

In order to carry out tests on the parts mentioned by means of the measuring device MK, test connections are made to an external test system ET, which lead via the telephone network PSTN, which also includes the telephone exchange shown and described in extracts.

The figure also shows a maintenance center BCT belonging to the switching center, from which the tests to be carried out are initiated.

The aforementioned subscriber line circuits SLC essentially fulfill the functions of subscriber line feed, overvoltage protection, call feeding, receiving and sending signaling from and to the terminals, coding and filtering, and two-wire, four-wire implementation. In the telephone exchange according to FIG. 2, in which the method according to the invention is used, it is assumed that part of the functions of the subscriber line circuits SLC, namely in particular those of coding and filtering and two-wire to four-wire conversion, are carried out using a digital signal processor are provided, which can be provided either individually for the subscriber, that is to say as part of a subscriber line circuit or for a group of, for example, four or eight subscriber line circuits, that is to say as part of the subscriber line group SLMA.

Today's digital signal processors are so powerful that they are underutilized by the functions mentioned in connection with the subscriber line. They are therefore used in addition to these tasks for the handling of test tasks with regard to the subscriber lines, subscriber terminals and subscriber circuits. For this purpose, such signal processors have access to various points of the receiving branch and the transmitting branch of the subscriber line via a digital interface and can therefore use these points Evaluate occurring voltages in different combinations and thereby determine resistance and capacitance values from which it can be concluded that the condition is correct or that there are faults and defects in subscriber lines, see also the aforementioned European patent application 0 451 759 A3.

In contrast to the situation described with reference to FIG. 1, the test functions are thus decentralized and integrated in the subscriber line circuits SLC or in the subscriber line assemblies SLMA summarizing such - subscriber line circuits. This is shown in FIG. 2 by the addition of ILTF (Integrated Line Test Functions) the designation for the subscriber line modules SLMA indicated.

The decentralized test result data are reported to the maintenance center BCT / ILMP and collected there. The measurement results can be evaluated using existing test systems ET, which is why such is also indicated in FIG. 2. The additional designation ILMP (Integrated Line Maintenance Position) in the designation BCT, for which the maintenance center points, indicates that the test functions are carried out automatically.

It can also be seen from FIG. 2 that decentralized measuring devices MK and the coupler modules required for their connection can be dispensed with.

In specific demand situations, the collected test result values are transferred to certain locations of the subscriber access area to which the subscriber lines from which the test results originate, taking into account specific selection criteria.

Such a situation of need can be the implementation of interference suppression or maintenance measures, for example on a distribution box. Test result data which are related to the connections accessible there can, according to the invention, be transferred to this location and made recognizable with a suitable device connected there. Because of the quasi-permanent determination of the test data, the test data is up-to-date, so that the reaction to the fault clearance measures or maintenance measures such as rearrangements can be recognized on site. In particular, it can be seen if consequential errors occur in the course of the measures carried out, which can then also be eliminated. - The uniqueness of a relationship between the measure taken and the test result obtained can be increased by transferring test result data to such is limited, which occurred in close proximity to the period of implementation of the measures.

The transmission of test result data from the collection point can also be used to notify an affected telecommunications subscriber of an error in the course of the establishment of a telecommunications connection or while the telecommunications connection exists.

In the case of an outgoing connection, the error message can occur during the occurrence of the dial tone, in the case of an incoming connection in the form of an announcement, for which purpose a conference connection is established, in which the maintenance center is involved.

Claims

claims

1. Method for testing subscriber lines (TL) together with the associated subscriber line circuit (SLC) and connected subscriber terminal of a digital telecommunications system, in which a digital signal processor is available for the subscriber line-specific or at least for a small group of subscriber line circuits, which functions are related to telecommunications traffic of the subscriber connection, whereby a plurality of different test functions for identifying functional errors are also carried out quasi permanently and automatically one after the other by this digital signal processor, characterized in that in this way decentrally determined test result data taking into account specific requirements

Selection criteria are collected at a central point and are transmitted to specific locations in the subscriber access area to which the subscriber access lines belong, in specific requirements.

2. The method according to claim 1, characterized in that the test result data collected at a central point (ET) are transmitted to a location where interference suppression measures are currently being carried out, provided that they relate to the geographic region of interest at this point.

3. The method according to claim 1 or 2, characterized in that the transmission of test result data is limited to those which have arisen in close proximity to the time period for the implementation of the interference suppression measures.

4. The method according to claim 1, characterized in that in the presence of error-indicating test results, the affected female participants on the occasion of the establishment or other existence of a telecommunications connection, an error signaling is sent.

5. The method according to claim 4, characterized in that the error signaling takes place during the occurrence of the dial tone in an outgoing telecommunications connection.

6. The method according to claim 4, characterized in that in the case of an incoming telecommunication connection, the error notification takes the form of an announcement, for which purpose a conference connection is established in which the institution issuing the error message is included.