DE10120070A1 - Device and method for adapting the line properties in high bit rate data transmissions - Google Patents

Abstract

The invention relates to a line module (2) for a switching center (1) for connecting terminals (7) to a telecommunications network, with a determination device (4) for determining the impedance of the subscriber line (6) with terminals (7) connected to it, and one Matching device (5) for automatically matching the impedance of the line module (2) to the determined impedance. DOLLAR A Furthermore, the present invention relates to a method used in this line module for adapting the line module (2) to a subscriber line (6) with terminals (7) connected to it.

Description

The present invention relates to a line module for a Exchange for connecting terminals to a tele communication network and one used in this line module method for adapting the line module to a part subscriber line with connected devices.

Modern exchanges in the Di electronic dialing system gital (EWSD) are already able to provide participants with their End devices in addition to the analog (POTS, Plain Old Telephone Ser vice) or digital (ISDN, Integrated Services Digital Net work) telephone services also high bit rate data services in the xDSL transmission method (x Digital Subscriber Line) for To make available. For example, in the ADSL process (Asymmetric DSL) from the exchange to the subscriber (data downstream) a data transfer rate of up to 8 Mbit / s and in the opposite direction (data upstream) of up to 640 kbit / s possible.

DSL data transmission is, for example, in the standards G.992.1 (G.dmt) and G.992.2 (G. Lite) from International Tele communication Union (ITU).

The interface between the participants and the operator or a telecommunications network forms in the Exchange a so-called line module (also line card or subscriber line module) and with the part an xDSL modem that internally or externally to a person nalcomputer (PC) of the participant is connected.

There are usually several participants on a line module with their end devices (e.g. one or more telephones, PC with  xDSL modem) connected; both services (voice service and Data service) are via a physical line (Subscriber line) in different frequency bands between Transfer switching center and subscriber. At the participant the services through a so-called splitter in data services and telephone services divided. The entirety of Devices at the participant (phone (s), splitter and PC with xDSL modem), customer premises equipment (CPE) is also used Nannt.

The line modules described have an integrated one Voice / data chipset that allows both a transmission of Language in the PCM system (Pulse Code Modulation) via one Voice network as well as a transmission of data (e.g. in Fra me relay, ethernet, or ATM system) for packet-oriented Data transmission (e.g. over the Internet) with high data transfer rates is possible.

The subscriber's modem can either be internal or ex ternes modem be formed. The external devices are included for example via an Ethernet (10Base-T) or USB (Uni Versal Serial Bus) interface connected to the PC. The internal devices are as plug-in cards, e.g. B. as a NIC (Network Interface Card) for a PCI slot, part of the PC's.

The maximum possible transfer rate at which data is transferred can depend on various factors. For example, the attenuation of the subscribers line, interference on this subscriber line and the Impedance of the subscriber line with the connected ones End devices influence the maximum possible data transfer transfer rate.

Procedures are described in the ITU standards mentioned ben to the data transmission to the respective areas adjust the characteristics of the transmission link. So at  for example when setting up a data transmission during a Initialization procedure the maximum possible data transfer rate determined and set. Furthermore, the ever transmit power (from line module or modem) to the respective receiver (modem or line module) set.

In the prior art, however, the impedance of the cut position of the line module with which the line module with the Subscriber line and the terminals is connected Value that is fixed. That is, the impedance the interface once to a value (e.g. Z = 100 Ω) is set, which is good practice for practice has proven worth.

The data transfer is therefore only set transmission rate and transmission power to an existing transmission route (line module, subscriber line and terminals of the Participant). However, these procedures do not take into account directly the impedance behavior of the connected participants line with the terminals; in the event of an incorrect adjustment These methods only react indirectly to the impedance by the transmission rate to this incorrect adjustment ask, which leads to a reduction in the maximum data transfer lead rate.

However, the impedance of the end devices can vary, for example change if the subscriber has additional end devices (e.g. Tele phones, modems, fax machines) to the subscriber line. Likewise, the impedance of the end devices cannot be exactly predicted be said, since the impedance of the terminals z. B. at ver different manufacturers.

The object of the present invention is thus a lei tion module for a switching center to connect End devices to a data transmission network and one in this lei to provide the applied module in which  an automatic optimization of the impedance behavior of the Transmission path is reached.

This task is performed by a line module for an operator lungsstelle for connecting terminals to a data transfer supply network according to the appended claim 1 and in this Line module method used to adjust the lei tion module to a subscriber line with connected to it NEN terminals solved according to the appended claim 6.

The line module according to the invention for an exchange le for connecting a subscriber's terminals to a tele communication network, with at least one terminal via a Subscriber line is connected to the line module holds an interface for connecting the subscriber line, a determining device for determining the impedance of the Subscriber line with the connected devices, and an adjustment device for automatically adjusting the Impedance of the interface to the determined impedance.

According to the present invention, the impedance of the Subscriber line with the connected devices determined by the line module and the impedance of the Lei tion module or its interface to the subscriber line adapted to this determined impedance.

The advantage of the present invention is that by adapting the impedance of the Lei according to the invention module to the subscriber line with the connected End devices reduce the bit error rate during data transmission is decorated. By reducing the bit error rate, the maximum possible data transfer rate increased.

Advantageous refinements of the present invention are reproduced in the respective subclaims.  

The impedance is automatically adjusted for everyone Establishing a connection for data transmission. For this the Impe the subscriber line with the connected end devices from the investigating device at each connection structure of data transfer determined.

The automatic adjustment can also be done periodically. because to determine the impedance in each case after certain intervals. The line module is thus in able to respond to short term and short term changes in the Line properties (impedance) to react when z. B. a additional end device (e.g. telephone) connected or the Picking up the handset of a telephone.

In the simplest case, the determining device determines the Impedance for a single frequency. This will reduce the effort kept as low as possible to implement the adjustment. Au In addition, the impedance measurement (determination of the impe danz) can be carried out very quickly.

The determining device advantageously determines the Impedance for a certain frequency range. That has the Advantage that the impedance matching is further optimized that can be done by adjusting over this frequency range is made.

The adjustment device contains an adjustment for adjustment bares filter, the adjustment by the automatic on set the filter. The filter has the task be, the frequency response of the impedance subscriber line with the connected devices if possible to achieve an optimal adjustment. The filter can an analog or digital filter or a combination be from both filter types.

The present invention is described below with reference to the accompanying drawing explains in more detail, in which the only  

Fig. 1 is a schematic representation of the piping module 2 according to the invention shows in an exchange 1.

The terminals 9 , 10 of the subscriber 7 are connected via a subscriber line 6 to the switching center 1 or the line module 2 . The subscriber 7 has, for example, one or more telephones 10 for using voice services and / or one or more PCs 9 , each with an xDSL modem for using data services (for example Internet).

A splitter 8 separates the available services from the respective end device (telephone 10 or PC 9 ). The splitter 8 shown is drawn in FIG. 1 as an independent component, but it can also be integrated as a filter for the respective services in the terminals (so-called distributed splitter).

The piping module 2 has for the subscriber line 6 via an interface 3 (transmit / receive interface 3) for transmitting and receiving the data to be transmitted or language. For reasons of clarity, the line module 2 with a single interface 3 is shown in FIG. 1; As a rule, however, several subscribers (ie subscriber lines 6 with terminals 9 , 10 ) are connected to a line module 2 . For this, the line module 2 for each partici merleitung 6 on its own interface. 3

Depending on the type of information, the line module ( 2 ) uses either a voice network (e.g. in the PCM system) or a data network (e.g. a packet-oriented transmission network, Internet) to transmit the information (data or voice). ,

According to the present invention, the impedance of the subscriber line 6 with the terminals 9 , 10 connected to it is determined by the determining device 4 . This process (impedance measurement) is carried out, for example, in which an alternating signal with a specific voltage is applied to the subscriber line 6 by the determining device 4 and the resulting current is measured.

Due to the impedance of the subscriber line 6 determined by the determination device 4 with the terminals 9 , 10 connected to it, the impedance of the interface 3 is automatically adapted by an adaptation device 5 . If there are several interfaces 3 , the adaptation for each interface 3 takes place individually.

The adaptation is advantageously carried out in the context of Initialization procedure during connection establishment to Data transfer.

The impedance measurement and adaptation can also (additionally) at certain time intervals, e.g. B. every 5 minutes. This has the advantage that the line module 2 can react to changes in the impedance of the subscriber line 6 and the terminals 9 , 10 connected to it. Such a change in the impedance can take place, for example, if a further terminal is connected or the handset of a telephone 10 is removed, the impedance of this telephone 10 changing.

In the simplest case, the impedance measurement can be carried out for a single one Frequency. The adjustment can be done by an ohmic resistance with the corresponding value is successful This has the advantage that the impedance measurement and matching solution can be implemented easily and inexpensively. Wei Furthermore, impedance measurement and matching can both be very effective be done quickly. However, in this case the Adjustment only for a frequency of the transmission signal opti times.

In order to further optimize the adaptation, the impedance measurement solution for a certain frequency range. The  Adjustment then takes place through a filter (analog, digital or mixed), which determines the determined impedance over the frequency rich by setting the appropriate coefficients (Filter parameters) if possible. This reali Sierung is more complex and costly, however the bit error rate is reduced over the frequency range and thus the maximum possible data transfer rate increased.

Claims (10)

1. Line module ( 2 ) for a switching center ( 1 ) for the connection of terminals ( 9 , 10 ) to a subscriber ( 7 ) to a telecommunications network, at least one terminal being connected via a subscriber line ( 6 ) to the line module ( 2 ) , With
an interface ( 3 ) for connecting the subscriber line ( 6 ),
marked by
a determination device ( 4 ) for determining the impedance of the subscriber line ( 6 ) with the terminal devices ( 9 , 10 ) connected to it, and
a matching device ( 5 ) for automatically matching the impedance of the interface ( 3 ) to the determined impedance. 2. Line module ( 2 ) according to claim 1, characterized in that the determining device ( 4 ) determines the impedance each time a connection is established for data transmission. 3. Line module ( 2 ) according to claim 1 or 2, characterized in that the determining device ( 4 ) periodically determines the impedance after certain time intervals. 4. Line module ( 3 ) according to claim 1, 2 or 3, characterized in that the determining device ( 4 ) determines the frequency dependence of the impedance for a specific frequency range. 5. Line module ( 3 ) according to one of claims 1 to 4, characterized in that the adaptation device ( 5 ) contains an adjustable filter, the adaptation being carried out by the automatic adjustment of the filter. 6. A method for adapting a line module ( 2 ) to a subscriber line ( 6 ) with terminals ( 9 , 10 ) of a subscriber ( 7 ) connected to it, the line module ( 2 ) for connecting terminals ( 9 , 10 ) to a telecommunications network serves and at least one terminal is connected via the subscriber line ( 6 ) to an interface of the line module ( 2 ), characterized by the steps
Determine the impedance of the subscriber line ( 6 ) with the terminals connected to it ( 9 , 10 ), and
automatic adaptation of the impedance of the interface ( 3 ) to the determined impedance. 7. The method according to claim 6, characterized, the impedance each time a connection is established for data transmission is determined. 8. The method according to claim 6 or 7, characterized, that the impedance periodically after certain time intervals is averaged. 9. The method according to claim 6, 7 or 8, characterized, that the frequency dependence of the impedance for a certain th frequency range is determined. 10. The method according to any one of claims 6 to 9, characterized, that the adjustment by automatically setting a Filters done.