DE29924714U1 - Arrangement to estimate transmission channel characteristics of a transmission channel by transferring information collected at a remote terminal to the central office - Google Patents

Abstract

The characteristics of the transmission channel between a remote terminal (RT) and a central office (CO) are estimated by collecting characteristic information at the RT and transferring this information to the CO, where this information is matched to a remote terminal simulation mode where parameters define the channel characteristics. This allows determination of the values of the parameters of the channel and of the remote terminal. Independent claims are included for a transmission channel and for a remote terminal.

Description

Such a method for estimating a transmission channel characteristic and the equipment associated therewith are already known in the art, eg from the US patent US 4,105,995 entitled "Digitally Controlled Transmission Impairment Measurement Apparatus". Typically, the network operator needs to know certain channel characteristics of a transmission channel between a central office and a remote terminal in order to be able to guarantee a particular service to a subscriber who has installed a remote terminal. The presence of line imperfections, such as bridged taps, line attenuation, aging effects, interferences such as radio frequency interference, and so on, must be estimated by the network operator before any particular quality of service can be guaranteed. To estimate all of the basic parameters needed to characterize the channel's capabilities for transporting traffic US 4,105,995 a portable, microprocessor-controlled device which measures specified parameters for a telephone channel. The known device for estimating the channel characteristic consists either of two units respectively connected to both ends of the transmission channel or of a single unit connected to a single end of the transmission channel. The latter embodiment of the known device for estimating the channel characteristic requires a manual loopback at the end of the transmission channel to which the device is not coupled. In summary it can be said that US 4,105,995 describes a special test equipment for transmission channels, which allow an offline measurement of the channel characteristic. In order to apply the known technique, the transmission of user data over the transmission channel must be interrupted and the test equipment must be connected to the transmission channel either on one or both sides of the channel.

It An object of the present invention is an arrangement for estimating a transmission channel characteristic and related equipment similar to the described above, but which are both an online as well as an offline estimate allow the channel characteristic without the need for a special test equipment the transmission channel to join.

According to the invention This object is achieved by the arrangement defined in claim 1 appraisal a transmission channel characteristic, and the defined in claim 8 remote terminal.

Actually captured the remote terminal itself all the information needed to estimate the transmission channel characteristic of interest and sends this information back to the exchange, where the information with a simulation model the transmission channel and the remote terminal be matched. The information collected by the remote terminal can be found under Application of a multiplexing process simultaneously with the user data be reported back so that traffic over the transmission channel does not have to be interrupted. The simulation model used in the Exchange for the Matching process is used, typically contains a number of parameters, e.g. the location of a bridged tap along the transmission line, which of the transmission channel characteristic of interest. While The adjustment process determines the values of these parameters.

It It should be noted that the term "comprising" as used in the claims is not so construed that he should be re the devices listed below would have a restrictive effect. Therefore the scope of the term "a device comprising device A and B "is not limited to devices which consist only of components A and B. He means, that in view of the present invention, the only relevant Components of the device A and B are.

In similar It should be noted that the one also used in the claims Term "coupled" not so interpreted should be limited to direct connections only. Therefore, should the scope of the term "a device A coupled with a device B" does not apply to devices or systems limited where an output of device A is directly connected to an input of the device B connected is. It means that there is a path between an exit of A and an entrance of B which can be a path the other devices or devices.

One additional Feature of the arrangement according to the present The invention is defined in claim 2.

In fact, a remote terminal of an Asymmetric Digital Subscriber Line (ADSL) system operated in accordance with ANSI Standard T1.413, Issue 2, for example, automatically acquires information indicating the attenuation of a set of carriers in the same Frequency spacing, as can be deduced from paragraph 9.9.8.1 of the draft version 2 of ANSI standard T1E1.413, which is entitled: "Standards Pro ject for Interfaces Relating to Carrier to Customer Connection of Asymmetric Digital Subscriber Line (ADSL) Equipment. "This information is used for the purposes of the bit rate selection method described in paragraph 9.9.8.2 of the cited draft standard and for use in the bit allocation method described in paragraph 9.9.14 of the cited draft standard, but are also very useful in estimating certain transmission channel characteristics, such as the position of a bridged tap along the line Use.

One Another feature of the arrangement according to the present invention is defined in claim 3.

So can be achieved by multiplexing the acquired information necessary for the transmission channel characterization be used with the user data a transmission channel without interruption be characterized by the system. This is so because the remote terminal that is for transmission the user data is able to not be replaced by test equipment needs to be.

alternative becomes as defined in claim 4, a transmission channel characteristic estimated offline.

So can by interrupting the transfer from user data via the channel and putting the system in a test phase a transmission channel characteristic according to the present invention also estimated offline will, without the need for a special test equipment to connect the channel.

One Another feature of the arrangement according to the present invention is defined in claim 5.

On this way you can Information showing the damping and phase rotation of carriers indicate which have different frequencies, as they are typically in a multi-carrier ADSL ("Asymmetric Digital Subscriber Line ") Modem can be detected, in addition for the Channel characterization can be used.

Yet another feature of the arrangement according to the present invention is defined in claim 6.

On this way you can Information indicating noise is the carrier with different frequencies impaired as typically detected in a multi-carrier ADSL modem and in it for the assignment of bits to the carrier frequencies to be used in addition for the Channel characterization can be used.

Furthermore As stated in claim 7, the present invention is very good for the implementation in an ADSL (Asymmetric Digital Subscriber Line) system or similar System, e.g. a VDSL ("Very High Speed Digital Subscriber Line ") System.

One additional advantageous feature of the arrangement for estimating a transmission channel characteristic according to the present The invention is defined in claim 9.

Therefore can Information for the use in the method of transmission channel characterization are suitable over a certain time interval are detected and the exchange reported as soon as this time interval has elapsed.

The mentioned above as well as other objects and features of the invention will become clearer and the invention itself will be best understood by will refer to the following description of an embodiment which together with the attached Drawing is presented, which is a block diagram of a telecommunications system in which the arrangement for estimating a transmission channel characteristic according to the present invention Invention is applied.

In In the figure, the exchange CO and the remote terminal RT are one ADSL ("Asymmetric Digital Subscriber Line ") Systems shown. The remote terminal RT contains in addition to the traditional ADSL receive circuits that are assumed to be part of of the receiver RX , and the traditional ADSL transmission circuits, from which are assumed to be part of the transmitter TX, a channel information acquiring unit INFO and a channel information memory MEM. The exchange CO over the traditional ADSL transmission circuit, which is not shown in the figure, contains a channel and modem matching unit MATCH.

The receiver RX in the remote terminal RT is coupled between an input / output port and an output terminal of this remote terminal RT and further has an output coupled to the channel information acquiring unit INFO. The transmitter TX in the remote terminal RT is coupled between an input terminal and the above-mentioned input / output port of the remote terminal RT. With a second input be-terminal device of the transmitter TX, the channel information memory MEM is coupled. An output of the channel information acquiring unit INFO and an input of the channel information memory MEM are interconnected. A twisted pair telephone line CHANNEL serves as a bidirectional physical communication medium between the remote terminal RT and the switch CO. The remote terminal RT is coupled to this telephone line CHANNEL via the input / output port mentioned above. In the central office, an input of the channel and modem matching unit MATCH is coupled to the telephone line CHANNEL.

In In the illustrated ADSL system, digital data becomes bidirectional above the phone signals over transmit the telephone line CHANNEL. Either on the remote side as well as on the side of the central office A splitter separates the received digital data from received ones Phone signals, routes the digital data to the ADSL remote terminal RT or to the ADSL exchange CO and redirects the phone signals to the phone device of the customer respectively to a POTS ("Plain Old Telephone Service ") Line card. In the drawing, the splitters are on the remote side and the switchboard page and the customer's telephone as well as the POTS line card not shown, because the present invention only effects to the ADSL exchange CO and the ADSL remote terminal RT has.

For the operator of the illustrated system is one of the problems in how the customer a particular service at the time of installation or later can be guaranteed without exact knowledge of the channel characteristics to have the phone line CHANNEL. Due to frequent changes in case of interference (e.g. by the presence of an amateur radio) and line faults (for example due to waterlogging) are databases that provide information about the channel characteristics contain a telephone line, usually outdated. Because the remote terminal RT of the displayed ADSL system automatically collects information that for information useful for channel characteristics, allows an access to this information by the network operator this Network operators, changes to track in the channel characteristic.

From the remote terminal RT in the figure is assumed to be according to edition 2 of the ANSI standard T1E1.413 operated and as a result performs certain channel measurements, for example a reinforcement and phase measurement for every carrier frequency, the above transmit the telephone line CHANNEL and a signal-to-noise ratio (SNR) measurement for each carrier frequency. The information obtained in this way will be used to Set parameters of a time domain equalizer and frequency domain equalizer, which are typically part of the ADSL receiver RX, and data bits to carrier frequencies in the ADSL transmitter TX. According to the invention collects the Channel information acquisition unit INFO the information, and the information will be temporary stored in the channel information memory MEM. After that, he reads ADSL transmitter TX the channel information from the channel information memory MEM and sends the information to the exchange CO, so on the side of the network operator for the channel estimation procedure to disposal stand.

In the exchange CO uses the channel and modem matching unit MATCH a simulation model of the telephone line CHANNEL and the remote terminal RT and equals the received information with this simulation model from. The simulation model contains a number of parameters such as the line attenuation, the length of the Telephone line, the length and the location of bridged taps, Presence of waterlogging and so on. By receiving the simulation model with those received from the remote terminal RT Align information determines the channel and modem match unit MATCH the values for different parameters in the simulation model. These parameter values are an estimate the channel characteristics that the network operator relies on can guarantee a particular service to the customer.

There the measurements from the remote terminal RT done online can be The channel characteristics can be monitored in time so that each one Time, if the customer wants to install a new service, current estimates the channel characteristic for the network operator are available, what makes it possible for the network operator quality guarantees in terms of of the newly installed service. The constantly available estimates the channel characteristics put the network operator beyond capable of taking appropriate action in the event of a loss of quality to take changes to monitor the customer's in-house network, which may affect the quality of service affect and complaints of the customer regarding the quality of service to rate quickly.

It should be noted that the channel information acquiring unit INFO, which is coupled to an output terminal of the ADSL receiver RX in the above-described embodiment, may be integrated with this ADSL receiver RX. Since an ADSL receiver RX operating in accordance with the specifications of ANSI standard T1E1.413, output 2, acquires channel information at initialization to be used in the bit allocation algorithm In fact, in certain embodiments of the invention, the channel information acquisition device INFO may actually be integrated into the receiver circuit RX in order to establish equalizer taps.

A Further note goes that although the one shown in the figure Embodiment of present invention includes a channel information memory MEM, the Providing such a channel information memory MEM no mandatory requirement for the implementation of the present invention. Without the channel information memory MEM would namely that from the remote terminal RT acquired channel information immediately to the exchange CO reported back, whereas with a channel information memory MEM the channel information while of a given time interval are collected and determined Reported back in time can be namely between the time intervals in which the channel information is collected become. When a channel information memory MEM is provided, can the collected channel information automatically at regular intervals the CO can be sent, or they can the CO exchange will be sent if they are from the latter be requested.

A Further note is that the channel and remote terminal matching unit MATCH Part of the exchange CO can be, as in the case of in the figure illustrated embodiment the invention is the case; alternatively it can be a separate entity be with an operator terminal of the switch CO connected is.

Yet another remark is that the applicability of the present Invention not on a particular physical communication medium between the central office CO and the remote terminal RT or is restricted to a specific transport protocol for the physical layer. So can a coax cable instead of a twisted pair phone line, an optical fiber, a radio link, a satellite link or even a hybrid transmission medium like a hybrid coax / fiber optic link as a communication medium between serve the central office CO and the remote terminal, and obviously can be used instead of the ADSL ("Asymmetric Digital Subscriber Line ") Protocol any other protocol for the physical layer, e.g. the VDSL ("Very High Speed Digital Subscriber Line ") Protocol or the HFC ("Hybrid Fiber Coax ") protocol chosen in the system in which the present invention is implemented.

Furthermore goes a note that embodiments of the present Invention above as functional blocks have been described. From the functional description of these blocks is for one Person skilled in the field of electronic device design obviously be like embodiments of these blocks can be made with well-known electronic components. A detailed Architecture of functional blocks is therefore for most of them are not specified.

The principle Although the invention has been described above in connection with specific devices, However, this is to be understood clearly that this description only as an example and not as a limitation of the scope the invention is given.

Claims (9)

A channel characteristic estimation apparatus for estimating a transmission channel characteristic of a transmission channel (CHANNEL) between a central office station (CO) and a remote terminal (RT), characterized in that said arrangement comprises: a. Information acquisition devices (INFO) in the remote terminal (RT) adapted for acquiring channel information; b. Information transmission devices (TX) in the remote terminal (RT) coupled to the information detection devices (INFO), the information transmission devices (TX) adapted to supply the channel information from the remote terminal (RT) to the exchange station (CO) transfer; c. Information and model matching devices (MATCH) adapted to match the channel information with a channel and remote terminal simulation model whose parameters define the channel characteristic; and d. Parameter value determining devices integrated into the information and model matching devices (MATCH) and adapted to determine values for the parameters and the channel and remote terminal simulation model. Arrangement for channel characteristic estimation according to Claim 1, characterized in that this channel information automatically detected by the remote terminal (RT) for operational purposes. Arrangement for channel characteristic estimation according to Claim 1 or 2, characterized in that the remote terminal (RT) the Channel information recorded online. Arrangement for channel characteristic estimation according to Claim 1 or 2, characterized in that the remote terminal (RT) the Channel information offline during recorded during a test phase. Arrangement for channel characteristic estimation according to one of the claims 2 to 4, characterized in that the channel information includes gain and phase distortion measurements on a number of frequencies transmitted from the remote terminal (RT) to the Equalizer setting can be detected. Arrangement for channel characteristic estimation according to one of the claims 2 to 5, characterized in that the channel information noise measurements on a number of frequencies detected by the remote terminal (RT) be to carrier frequencies Assign bits, these carrier frequencies for the transmission of data from the remote terminal (RT) to the central office station (CO). Arrangement for channel characteristic estimation according to any of the preceding claims, characterized that the transmission channel (CHANNEL) is a digital subscriber line, the central office station (CO) an exchange for a digital subscriber line, the remote terminal (RT) Modem for a digital subscriber line and the channel information information are the ones when initializing a system for asymmetric Digital subscriber lines are recorded to a selection of upward and down bitrates, Equalizer adjustment and assignment of data bits to carrier frequencies too enable. Remote terminal (RT), suitable for communicating with a central office station (CO) via a intermediate transmission channel (CHANNEL), characterized in that this remote terminal (RT) comprises: a. Information capturing devices (INFO) adapted to capture channel information; b. Information transmission devices (TX), coupled with the information acquisition devices (INFO), wherein adapted these information capture devices (INFO) are the channel information from the remote terminal (RT) the switching center station (CO) to transmit there with a Channel and remote terminal simulation model whose parameter is a transmission channel characteristic for this channel and determine its values as the result of this alignment become. Remote terminal (RT) according to claim 8, CHARACTERIZED THAT this remote terminal (RT) continues Memory devices (MEM) coupled between the information acquisition devices (INFO) and the information transmission devices (TX), and adapted to that over a time interval acquired or collected channel information save.