EP1360828A2 - Device and method for characterizing the transmission parameters of a transmission link for high bit rate data transmission - Google Patents

Abstract

The invention relates to a method for determining the transmission parameters of a transmission link for high bit rate data transmission, wherein the transmission link consists of a line module (1) in a switching centre, a subscriber modem (2) and a subscriber connection line (3) for connecting the line module (1) and the modem (2). The invention also relates to a line module (1) for high bit rate data transmission for a switching centre and a modem (2) for high bit rate data transmission for a subscriber in order to carry out said method.

Description

description

Device and method for characterizing the transmission parameters of a transmission link for high bit rate data transmission

The present invention relates to a line module for a switching center, a modem for high-bit data transmission for a subscriber for use with this line module and a method used in this line module and modem for characterizing the transmission parameters between the line module and the modem.

Modern exchanges in the digital digital dialing system (EWSD) are already able to provide subscribers with their end devices in addition to the conventional analog (POTS, Piain Old Telephone Service) or digital (ISDN, Integrated Services Digital Network) telephone services as well as high-bit-rate data transmission services in xDSL To provide transmission system (x Digital Subscriber Line).

For example, in the ADSL transmission system (asymmetry DSL) from the exchange to the subscriber (data downstream), a data transmission rate of up to 8 Mbit per second and in the opposite direction (data upstream) of up to 640 kbit per second is possible.

The interface between the subscriber and the exchange or the telecommunications network is formed by a so-called line module (also called subscriber line module, line card or SLMI, Subscriber Line Module Internet) in the exchange.

As a rule, several subscribers are connected to a line module via a subscriber line with their end devices (eg telephone and PC); both services are via a physical line between participants and exchange switched. At the subscriber, the services are divided into data services and telephone services by a so-called splitter. The PC has an xDSL modem for high bit rate data transmission. The totality of the end devices at the subscriber (telephone, PC with xDSL modem and splitter) is also referred to as customer premises equipment (CPE).

The data transmission takes place in different frequency ranges, each frequency range representing its own transmission channel for data transmission; the data for the telephone services are transmitted in one frequency range, the data for data transmission from the subscriber to the exchange (data upstream) in a second frequency range and the data for data transmission from the exchange to the subscriber (data downstream) in a third frequency range.

The line modules described have an integrated voice / data chipset, with which both a transmission of

Speech in the PCM system (Pulse Code Modulation) via a voice network as well as the transmission of data (e.g. in the frame relay, Ethernet or ATM system) for packet-oriented data transmission via a data transmission network (e.g. the Internet) with high data transmission rates is possible.

In the course of manufacturing and operating xDSL modules, such as modems and line modules in the ADSL or UDSL data transmission system, it is necessary to ensure the functionality of the xDSL modules or the transmission line (subscriber line), the transmission parameters, such as check the amplitude frequency response of the transmit / receive interface (line transceiver) of the respective module and the subscriber line in between.

In the prior art, this problem is solved in that after the end devices (xDSL modem and line module) the physical parameters of the subscriber line are measured (FIG. 1). The disadvantage of this method, however, is that a technician is required on the exchange side as well as on the subscriber side, the corresponding test equipment

(Test transmitter and test receiver) attaches and operates. In addition, only the transmission parameters of the subscriber line can be checked with this method.

Furthermore, a method is known with which it is possible to determine and evaluate the amplitude frequency response of an xDSL line module at the component level without additional measuring means (FIG. 1); this "method for characterizing the amplitude frequency response of an xDSL line transceiver" is described in the patent application with the application number 100 22 710.4 of Siemens AG.

So far, however, no method is known for determining the transmission parameters of the data transmission between the xDSL modem, subscriber line and line module in one process.

The object of the present invention is therefore to provide a method for determining the transmission parameters of a transmission link for high-bit data transmission, a line module and a modem for carrying out this method, in which a simple determination of the transmission parameters of the transmission link between modem, subscriber line and line module is made possible , the transmission parameters for further evaluation and

Processing are available.

This object is achieved by a method for determining the transmission parameters of a transmission link for high-bit data transmission according to appended claim 1, a line module according to appended claim 8 and a modem according to appended claim 11. According to the present invention, the xDSL modem and the line module are actively involved in the measurement process, which is used to determine the parameters of the transmission link for high-bit-rate data transmission. The measuring process thus extends to the modem, the subscriber line and the line module.

For this purpose, the line module according to the invention has a line module test transmitter for generating first test signals and for sending these test signals to a modem.

The modem according to the invention receives these first test signals with the aid of a modem test receiver. A modem evaluation device evaluates the first test signals with regard to the transmission parameters of the transmission link or the transmission channel from the line module to the modem. A modem protocol transmitter then sends a test protocol to the line module. The test protocol contains the evaluation of the first test signals; the line module receives the test protocol by means of a line module protocol receiver.

According to the invention, the modem has a modem test transmitter for determining the transmission parameters from the modem to the line module. The modem test transmitter generates and sends second test signals to the line module in the exchange. The line module has a line module test receiver for this purpose. These test signals are evaluated with regard to the transmission parameters of the transmission link or the transmission channel from the modem to the line module by a line module evaluation device.

The transmission parameters can be determined separately for both directions (modem to line module and vice versa) or carried out in one measurement process. The advantage of. The present invention consists in the fact that only one technician is required for the measurement of the transmission link, specifically in the exchange. The operator places a test order for the transmission path of a certain subscriber, whereupon the measurement is carried out automatically.

Furthermore, the transmission parameters of the entire transmission path, which includes the modem, subscriber line and line module, can be determined in one operation.

This reduces the effort required for commissioning and maintaining an xDSL transmission link; there is no longer any need for an external test device or the use of technicians by the participant.

Advantageous embodiments of the present invention are given in the respective subclaims.

The line module according to the invention includes a communication interface which generally enables access to the line module for procedures which relate to the measuring process for determining the transmission parameters.

This communication interface enables access to the line module evaluation device and the line module protocol receiver for reading out the evaluations of the test signals. Furthermore, these communication interfaces enable access to the line module test transmitter and the line module control transmitter for initializing and executing a test job for the modem and the line module and / or for updating measurement routines stored in the modem or line module.

In this case, for example, access is made manually by a technician on the basis of the transmission parameters determined qualitatively assesses the transmission link. Furthermore, the access can also be made automatically by a computer program, for example at regular intervals or when errors occur frequently.

The possible update of test routines in the modem by the line module ensures that flexible adaptation to changing requirements with regard to test types, test depth, etc. can take place.

Since the transmission parameters, in particular the available transmission bandwidth, are not known from the outset, it makes sense to carry out the data transmission for the test protocol with the lowest possible data transmission rate (bit rate). This ensures that data transmission can be carried out in any case, even if the subscriber line is damaged or has limited functionality with a restricted transmission bandwidth. A frequency range would be conceivable here, for example, which if possible at the beginning of the frequency range of the data

Upstream transmission channel lies and roughly corresponds to the bandwidth of a voice transmission (4 kHz). However, data transmission in the frequency range in which the transmission of the telephone services normally takes place would also be conceivable, for example.

The modem also has a modem control receiver. The modem control receiver receives from the line module the data that contain an initialization of the modem for a test job and / or an update of measurement routines stored in the modem. This data is processed by the modem control receiver, whereupon the respective actions (initialization or update) are stimulated in the modem.

In the simplest case, the first and second test signals exchanged between the line module and the modem are sine waves. signals that are tuned (varied) in a specific frequency band. In this way, the amplitude frequency response of the transmission link from the switching center (line module) to the subscriber (modem) and vice versa can be determined very easily by the respective evaluation devices.

The test signals can also be multi-tone signals that contain a specific frequency spectrum.

The test signals are spectrally evaluated by the respective evaluation devices, as a result of which the amplitude frequency response can be determined in a simple manner.

It would also be conceivable to determine the transmission parameters by transmitting test signals only in one transmission direction. For example, the line module generates a first test signal that covers the entire transmission range (data upstream and data downstream). As described, the evaluation takes place in the modem, which sends a test protocol to the line module for further processing. This determination can also take place in the opposite direction of transmission. In this way, the test signals only have to be evaluated by one device (modem or line module).

The present invention is explained in more detail below on the basis of a preferred exemplary embodiment with reference to the accompanying drawings, in which:

1 is a representation of the test process according to the prior art,

Fig. 2 is an illustration of the transmission link according to the present invention. The present invention is explained in more detail below with reference to FIG. 2, which shows a schematic representation of the transmission link.

The transmission link that is considered with the present invention consists of a line module 1 in the exchange, a modem 2 (xDSL modem) at the subscriber and the subscriber line 3 for connecting the subscriber to the exchange. The subscriber line 3 is shown here so that it can be measured only for this line, as in the prior art, for example.

The line module 1 includes, among other things, the line module test transmitter 11, the line module evaluation device

12, the line module protocol receiver 13, the communication interface 17 and the line module control transmitter 18. Furthermore, the line module 1 contains a transmitting / receiving device 14, which in turn consists of the line module transmission interface 15 and the line module

Receiving interface 16 for connecting the subscriber line 3 to the line module 1 is used for sending and receiving data.

The modem 2 includes, among other things, the modem test transmitter 21, the modem evaluation device 22, the modem protocol transmitter 23 and the line module control receiver 27. Furthermore, the modem 2 contains a transceiver 24, which in turn originates from the modem transmission interface 25 and the modem reception interface 26 for connecting the subscriber line to the modem 2 for sending and receiving data.

To determine (measure) the amplitude frequency response from the line module 1 to the modem 2 (data downstream), a signal generator (line module test transmitter 11) is present in the line module, which generates a signal (first test signal) whose Spectral components are in the desired frequency band for data downstream data transmission.

The modem 2 at the subscriber is initiated by the modem control receiver 27 as a receiver for the first test signal by an initialization, which is excited via the communication interface 17 and sent to the line module control transmitter 18. The modem evaluation device 22 is designed as a spectrum analyzer. The modem 2 thus determines the amplitude values of the expected spectral components of the received first test signal (and thus the nodes of the data downstream amplitude frequency response).

The spectral components are then encoded by the modem protocol transmitter 23 in a test protocol (measurement protocol) and sent to the line module 1 for further evaluation and received there by the line module protocol receiver 13. The test protocol is thus available via the communication interface 17 for further evaluation.

To measure the amplitude frequency response in the opposite direction (data upstream), the modem 2 is initialized as a signal generator using the initialization procedure. The modem test transmitter 21 sends a second test signal to the line module, which has the spectral components of the desired frequency in the data upstream.

After the start of the test run, the line module 1 uses the line module evaluation device 12, which is also designed as a spectrum analyzer, to evaluate the amplitude values of the expected spectral components of the second test signal and thus determines the reference points of the data upstream frequency response.

To implement the present invention, DSP algorithms (digital signal processors) are implemented both in the line module 1 and in the modem 2 enable the test signals of the respective test transmitter to be generated or the test signals received to be evaluated by the respective evaluation device (for example spectral evaluation).

The respective measurement is initiated by a single technician in the exchange who has access to the line module 1 via the communication interface 17. This initiates a test job for a specific subscriber connection (modem 2, subscriber modem), whereupon the line module contacts the subscriber modem 2 via the test protocol and makes the necessary initializations and settings.

At Tes run, in which the line module 1 serves as the source for the test signal (first test signal) and the subscriber modem (modem 2) as the receiver, the received test signal is evaluated in the modem itself. The actual test results are in the form of a measurement protocol (test protocol) transmitted to the line module 1 and are thus available to the technician in the office for further evaluation via the communication interface 17.

In test runs in which a test transmitter on the subscriber side (modem test transmitter 21) is required, the subscriber modem takes over this task after appropriate initialization by the line module 1. The second test signal then received by the line module is evaluated and made available to the technician in a prepared form ,

The present invention enables a particularly flexible measuring method for measuring the transmission path described.

For example, noise measurements and spectral measurements in freely selectable frequency or spectral ranges are possible.

Event-controlled measurements are also conceivable if certain threshold values are exceeded. Such swelling values are eg. Bit errors, wherein when a certain bit error rate is exceeded by the modem 2 or the line module 1, feedback is sent to the exchange, whereupon a measurement is automatically initiated.

In addition, data upstream can be qualified for a line over the entire data downstream bandwidth of the transmission link mentioned. The "method for characterizing the amplitude frequency response of an xDSL line transceiver ^{, λ} ," from Siemens AG proposed in the patent application with the application file number 100 22 710.4 is advantageously suitable for this measurement.

The test results obtained are used, for example, for the qualitative assessment of the transmission link by a technician, for example for troubleshooting and limitation, for setting predetermined parameters for the respective transmission link, etc.

LIST OF REFERENCE NUMBERS

1 line module, subscriber line module 11 line module test transmitter 12 line module evaluation device

13 Line module protocol receiver

14 Line module transceiver, line module line transceiver

15 Line module transmission interface 16 Line module reception interface

17 communication interface

18 line module control transmitter

2 modems

21 modem test transmitter 22 modem evaluation device

23 Modem protocol transmitter

24 modem send / receive interface, modem line transceiver

25 Modem send interface 26 Modem receive interface 27 Modem control receiver

3 subscriber line

Claims

Claims. 1. A method for determining the transmission parameters of a transmission link for high-bit data transmission, the transmission link comprising a line module (1) in a switching center, a modem (2) for a subscriber and a subscriber line (3) for connecting the line module (1) and modem (2), characterized by the steps of generating first test signals by the line module (1) and sending the first test signals to the modem (2), the first test signals being used to determine the transmission parameters of a transmission channel from the switching center to the subscriber Receiving and evaluating the first test signals by the modem (2), Generating second test signals by the modem (2) and sending these test signals to the line module (1), the second test signals being used to determine the transmission parameters of a transmission channel from the subscriber to the exchange, Receiving and evaluating the second test signals by the Line module (1), Generating a test protocol by the modem (2) and sending the test protocol to the line module (1), the test protocol containing an evaluation of the first test signals, and The line module (1) receives and evaluates the test protocol. 2. The method according to claim 1, characterized in that the test protocol and the evaluation of the second test signals are available via a communication interface for further processing and evaluation. 3. The method according to claim 1 or 2, characterized ge ennzeic ne that data containing an initialization of the modem (2) for a test job and / or an update of measurement routines stored in the modem (2) from the line module to the modem (2) will be sent. 4. The method according to claim 1, 2 or 3, characterized gekennzeic net that the data transmission for the test protocol, for initialization for a test job and for updating the measurement routines is carried out with a low data transmission rate. 5. The method according to any one of claims 1 to 4, characterized gekennzeic net that the test signals are sinusoidal signals which are tuned in a certain frequency range to determine the amplitude-frequency response of the subscriber line in combination with the modem and the line module. 6. The method according to any one of claims 1 to 5, characterized gekennzeic net that the test signals are multi-tone signals to determine the Aplituden frequency response of the subscriber line (3) in combination with the modem (2) and the line module (1). 7. The method according to claim 5 or 6, characterized in that the received test signals are spectrally evaluated. 8. Line module (1) for carrying out the method according to one of claims 1 to 7 for a switching center for connecting a modem (2) to a telecommunications network for high bit rate data transmission, the connection between see the modem (2) and the line module (1) via a subscriber line (3), characterized by a line module test transmitter (11) for generating first test signals and for sending these test signals to a modem (2), the first Test signals for determining the transmission parameters of a transmission channel from the switching center to the subscriber are used, a line module evaluation device (12) for receiving and evaluating second test signals sent by the modem (2), the second test signals for determining the transmission parameters of a transmission channel from the subscriber serve to the switching center, and a line module protocol receiver (13) for receiving a test protocol from the modem (2), the test protocol containing an evaluation of the first test signals. 9. Line module (1) according to claim 8, characterized by a communication interface (17) which enables access to the line module (1) for reading out the evaluations of the test signals. 10. Line module (1) according to claim 8 or 9, characterized in that an initialization of the modem (2) for a test job and / or an update of measurement routines stored in the modem (2) by means of a line module via the communication interface (17). Control transmitter (18) is excited. 11. Modem (2) for performing the method according to one of claims 1 to 7 for high bit rate data transmission over a telecommunications network, the connection between the modem (2) and a line module (1) being established in a switching center via a subscriber line (3) . characterized by a modem test transmitter (21) for generating second test signals and for sending these test signals to the line module (1), a modem evaluation device (22) for evaluating first test signals sent by the line module (1), and one Modem protocol transmitter (23) for sending a test protocol to the line module (1), the test protocol containing an evaluation of the first test signals. 12. Modem (2) according to claim 11, characterized by a modem control receiver (27), the data indicating an initialization of the modem (2) for a test job and / or an update of measurement routines stored in the modem (2) included, received and processed by the line module.