DE102005007682A1 - Data communication method for use over digital subscriber line-data link, involves introducing filter arrangement with high and low pass filters, and lying filter frequencies in frequency separation distance, and presenting frequency range - Google Patents

Abstract

The method involves presenting a digital subscriber line (DSL)-upward channel (13) for data communication to a customer connection, and a DSL-downward channel (14) for reverse data communication. A filter arrangement with a high-pass filter and a low-pass filter is introduced for separating both the channels. The filter arrangement has two filter frequencies that lie in a frequency separation distance and present a frequency range.

Description

The The invention relates to a method for data transmission over a DSL data connection the preamble of claim 1.

In the journal for Education and Training (Lesson 5, C 10964 of 10 May 1999) becomes the principle of a frequency-separation-method (Data-over-Voice) for ADSL systems.

One Feature of these systems is that they work simultaneously with an existing one Telephone connection or ISDN basic connection via one Line can be operated.

Of the DSL channel is in an upstream - upstream - and one Downstream - Downstream - divided. For each transmission direction So a frequency band is reserved. The downstream channel is in a higher frequency range and has a higher one Bandwidth as the upstream channel on.

Around an available one It is known, not to be able to exploit bandwidth optimally to transmit the same bitrate in both directions. It is known, with it the customer on the Internet (World Wide Web) can optimally "surf" that an asymmetric bitrate distribution he follows. For the downloading of data from the Internet is therefore the customer a higher one Bitrate available.

One Splitter is used to separate the narrowband signal (telephone) and the broadband signal or DSL signal (Internet).

at a connection with frequency separation method, in which Reason for a long connection line an amplifier circuit in the connection line is arranged, the data stream to the customer (downlink) and the data stream from the customer (uplink) via a Filter arrangement with a high-pass and a low-pass filter separated.

These Filters are expensive to realize or connected with a high construction cost and thereby expensive. The filters need namely limit the frequencies relatively sharply and therefore a high slope have. In the other case or with insufficient steepness exists the Risk of feedback when using an amplifier, what a data transfer impaired.

Of the Invention is based on the object, a method according to the preamble of Claim 1 continue to form in a simple manner the cost of such a filter arrangement is reduced, and Although without a loss at the reliability the data transmission connected is.

These The object is achieved by the characterizing features of claim 1 solved in conjunction with its generic features.

Of the Invention is based on the idea that by a shift the filter frequencies a frequency range arises that neither on the High pass still passes the low pass. This area points for both frequency bands and for that both directions a high damping on. This shift reduces the risk of feedback in a circuit, in particular an amplifier circuit, even with filters with less steepness. Filters with less steepness are cheaper to realize.

To The invention therefore provides the filter arrangement with two uplink channels and the downlink channel separating filter frequencies - fu, fo - operated such that a first up the channel associated filter frequency fu and a second the downstream channel associated filter frequency fo are present, both filter frequencies fo, fu in a frequency interval Δf away from each other and thereby a frequency range available is where the signals are neither over the lowpass filter still over get the high pass filter.

According to the invention thus the separation of the bands no longer at a single crossover frequency ftr. The crossover frequency of the low pass is no longer consistent with the crossover frequency of the high pass.

One Another advantage of the method is that existing Techniques without changes Insert bar are. The range of high attenuation, between fu and fo, is automatically detected and turned off accordingly in the use or only slightly loaded. When DSL system or DSL method is namely expediently the line or the respective signal-to-noise ratio or another suitable Size at the Commissioning measured. Because of the result, the individual will Carrier, e.g. 255 carriers, which work practically as small parallel modems or 255 frequency bands, accordingly burdened or possibly completely switched off. By the shutdown then work less than 255 vehicles. As the carrier number but still very high, the data transfer speed becomes not significantly affected.

Another advantageous influence in Be Train on the feedback behavior of a signal amplifier used is obtained when a resonant frequency is used with a resonant frequency. For example, the resonant frequency is centered between fu and fo, where fu and fo define the unused area. For example, the absorption circuit is located between the high pass and the amplifier. This further improves the feedback behavior.

Especially is provided that the downlink channel in a higher Frequency range as the upstream channel lies. As before, you can the advantages of the frequency position method be used.

A Circumcision of the frequency bands takes place according to specifications of the operator. So it is preferably provided that by at least one shift frequencies of the filter at least one channel region of the two channels is reduced. A lowest and highest channel frequency, e.g. 138 kHz and 1.1 MHz, preferably remain receive. in principle can both channel regions, i. that of the upstream channel and that of the downstream channel, be downsized.

If both bands cropped, down and down speeds are reduced (Up and down channel). However, this reduction plays against the achieved reliability the data transmission a minor role.

Basically, for each transmission direction one amplifier each be used, so that a total of two amplifiers in a unit needed become.

To an advantageous embodiment of the method according to the invention However, it is envisaged that only one frequency range of the high-frequency downlink channel is amplified by an amplifier. Preferably, the entire frequency range of the downstream channel strengthened.

by virtue of the physical characteristics of the telephone cable emerges the cable length an upper limit of a transferable Bit rate.

In In practice, the range plays a big role. For customers with known solutions a DSL connection would like, the distance to the exchange may be due to the existing cable loss of the transmission cable not bigger than 4 to 5 km. However, this is not enough in many cases. In further remote areas must be used repeaters become. These amplifiers are expensive and expensive and are also prone to failure.

With the amplifier, the higher Amplified frequencies, will easily be a higher one Range created in a simplified way. It is preferably only the frequency range of the downstream channel amplified by the amplifier.

This measure The underlying idea is that the data transfer in the upward direction due to the low frequency position at the required distances as well as at greater distances without reinforcement safe to operate. Too high cable damping or too low SNR is that through the line inductance and the line capacity only available at high frequencies. At low frequencies plays that of a transmission link dependent Line inductance and -capacity a minor role.

Around the range for DSL connections to increase, enough it is exclusive the high frequency range for the signals in the downward direction too strengthen what the construction of a repeater device very simplified. The amplifier can for this to be reinforced Frequency range to be optimized.

The simple exclusively reinforcing in one direction amplifier circuit has a relatively low power consumption. That's it possible, the amplifier device independently from a separate power source - connection from an energy supplier - in outdoor enclosures (outdoor enclosures) too operate as provided in accordance with a preferred embodiment of the invention is. A power supply can - internally - through one or more separate pairs from the Office done, in which case over a used for power double charger supplied several amplifier devices should be. Also, the power supply - internally - from a POTS system of one of the respective Connection done. Another advantage is that a telephone connection in case of failure of the amplifier still works. Therefore is it cheap if filters are designed as passive filters. It also works the upward channel continue if the amplifier should fail. This channel can then issue a fault message be used.

If For example, the customer announces his DSL connection, can a circuit with the amplifier remain in the line with filters. The POTS ports are still operable.

In order to prevent a feedback of the higher frequencies to the input of the amplifier, a signal coming from the exchange in the downlink channel via the high-pass filter is supplied to the amplifier, while a signal coming from a customer in the uplink channel unver strengthens through the low-pass filter is performed.

Of the Telephone connection does not need to be strengthened because of this deep Uses frequencies where line attenuation is low. He can an ISDN basic line and / or an analog telephone line.

There In a DSL connection "surfing" on the Internet occurs more often as a data transfer from the customer to the exchange, is also at a preferred Realization advantageous if an asymmetric operation exists is such that the frequency width of the downstream channel is larger than the up channel.

Further advantageous developments of the invention are characterized in the subclaims.

Further Advantages, features and applications of the present Invention will become apparent from the following description in conjunction with the embodiment shown in the drawing.

The Invention will be described below with reference to the drawing Embodiment described in more detail. In the description, in the claims, the abstract and in the drawing, the list given in the back of the reference numerals used terms and associated reference numerals. In show the drawing:

1 a circuit arrangement for carrying out a method according to the invention, and

2 a preferred frequency allocation with a frequency separation according to the invention in comparison with a frequency assignment according to the prior art.

The exemplary embodiment relates to a method for data transmission via a DSL data connection or a DSL system. The system includes a telephone line and a DSL data connection with a common line 7 , The telephone line can be an analog or ISDN basic line. To separate the telephone line and DSL, a splitter is connected to a TAE socket at the customer's premises.

1 shows a circuit arrangement or amplifier circuit arrangement 1 or amplifier unit or amplifier circuit for carrying out the method according to the invention.

The method described is used to avoid feedback through an amplifier 4 , As 2 shows is a DSL upstream channel for data transmission 13 from a customer connection to an exchange 6 directed, available. Furthermore, a DSL downlink channel 14 for reverse data transmission available.

The DSL upstream channel 13 therefore serves for data transmission from a customer connection to a central office and the DSL downlink channel 14 for reverse data transfer.

It takes place like 2 shows an asymmetric operation such that the frequency width of the downstream channel 14 is greater than that of the upstream channel 13 ,

Furthermore, a filter arrangement with a low-pass filter 2 and a high pass filter 3 used to separate both channels, such as 1 shows.

In accordance with the invention, the filter arrangement is operated with two filter frequencies fu, fo which separate the two channels, such that a first one is located upstream of the upstream channel 13 associated filter frequency fu and a second the downstream channel 14 associated filter frequency fo are present, wherein both filter frequencies are at a frequency distance .DELTA.f from each other and thereby a frequency range is present, in which signals neither via the low-pass filter 2 still over the high pass filter 3 reach and thus creates a range of high attenuation.

2 further illustrates that the downstream channel 14 in a higher frequency range than the upstream channel 13 lies. The upward channel 13 is between 138 kHz and a frequency fu that is significantly smaller than ftr = 276 kHz. The downlink channel 14 is between a frequency fo that is well above 276 kHz and 1.1 MHz or higher.

The frequency ftr = 276 kHz is the cutoff frequency after that at the bottom of the 2 shown prior art.

Basically the values of fo and fu and the difference to ftr determined by the operator. in this connection However, you will be at the Nutzbandbreiten a carrier of a usable frequency range of the DSL data connection, so that Δf always individual carriers and thus an integer multiple of the useful bandwidth of a carrier.

The following applies: fu <ftr and fo> ftr

Of the Frequency difference Δf is formed by the difference between fo - fu.

A Limit or crossover frequency is present at which a signal about about 70% steamed becomes. However, by way of example, for simplicity, a value of 100% damping shown.

As 2 shows, by shifting both filter frequencies from ftr to fu and from ftr to fo at least one channel region of the upper and lower channel is reduced. The lowest channel frequency fku of 138 MHz of the upstream channel 13 and the top channel frequency fko of 1.1 MHz of the downlink channel is maintained. Both channel areas (up and down channel) are reduced by the shift from ftr to fu and fo.

In particular, it is only the frequency range of the downstream channel through the amplifier 4 strengthened. This results in a simple and efficient regenerator.

After this example, the entire frequency range of the downstream channel 14 strengthened.

The amplifier circuit 1 is in the transmission line 7 between the exchange or the office 6 and the customer connection 5 ,

In the path of the transmission line 7 is the low pass filter 2 , It filters out the higher frequency signals and leaves only lower frequency signals from the central office 6 to the customer connection 5 happen, in the frequency range of the uplink channel 13 and the POTS frequency range.

Parallel to the low-pass filter 2 is the high pass filter 3 connected. One from the central office 6 incoming signal in the downstream channel 14 is through the high pass filter 3 transmitted.

At the output of the high pass filter is the amplifier 4 connected. It only has to amplify the high frequencies that are subject to high line attenuation due to the line inductance and line capacitance.

The filters 2 and 3 are preferably designed as passive filters, for example with filter capacitors and filter inductors. The power supply for the amplifier 4 can be through one or more twisted pairs from the central office 6 or from a POTS system (telephone) of the respective connection.

By this amplifier arrangement are in case of failure of the amplifier 4 only signals in the downlink channel 14 interrupted as the circuitry in 1 can be seen.

As 2 shows is for a telephone line, which may be an analog and / or ISDN telephone line, a lower frequency band 11 reserved. The frequency band of the telephone is not amplified, even with an ISDN basic connection, at least not through the amplifier 4 ,

The upward channel 13 lies, how 2 illustrates between the frequency range 11 the telephone line and the unused frequency range .DELTA.f. The transmission also takes place here as in the prior art (lower diagram) according to the frequency separation method.

The frequency bandwidth of the downstream channel 14 is always larger than the up channel 13 ,

Preferably is the transmission path in less than 255 frequency bands (Carrier) divided so that practically many small modems work. A selection the usable frequency bands is determined by measuring the signal-to-noise ratio realized every frequency band.

Furthermore, the amplifier has 4 Preferably, a frequency response, the attenuation distortion of the line 7 the data transmission path is adjusted.

As the 2 shows, become a lower frequency band 11 for the telephone connection, whereby this too can be a fax connection, a lower frequency band 13 and an upper frequency band 14 used for the DSL data connection. The telephone line (POTS) is assigned the lower frequency range.

Alternatively - not shown - by shifting only one frequency fu or fo only one channel 13 or 14 be downsized.

Basically, it is possible that only the upstream channel 13 is cropped, reducing speed in the upstream channel.

The following applies: fu <ftr and fo = ftr

Preferably, however, only the downstream channel becomes 14 cropped, reducing speed in the downstream channel.

It then applies: fu = ftr and fo> ftr.

It is also conceivable, the crossover frequency of the low pass 2 to make fu bigger ftr. This results in the advantage of even lower residual damping for the unreinforced area 13 ,

This variant is particularly advantageous, because thereby the upstream band or the downstream channel 13 is not cropped, which has an advantageous effect on the residual damping in the lower, preferably unreinforced, area.

The upper and the lower channel 14 is through the gain with the amplifier 4 especially in the upper area made better usable. As a result, common downstream speeds can be easily realized despite the separation in the lower area. Common downstream speeds can be easily realized.

The carriers (or frequency bands) between fu and fo can be administratively switched off because they are not required for data transmission, because they are hardly usable due to the high attenuation. To further improve the feedback behavior of the amplifier arrangement 1 for example, between the high pass 3 and the amplifier 4 a suction circuit are arranged whose resonant frequency is located centrally between fu and fo.

Especially is between the filter frequency (fu) and the filter frequency (fo) a suction circuit with a resonant frequency interposed, whereby the Feedback behavior the amplifier circuit arrangement is further improved.

In an advantageous variant of the administrative switching off, it is provided that the amplifier unit or amplifier circuit arrangement 1 on a request or constantly or only in a commissioning phase sends a detection switching criterion or a recognition string. As a result, the aforementioned administrative settings can be carried out automatically, for example by the DSLAM.

The The invention is not limited only to the illustrated examples. individual features this description can be combined with each other. Also, the invention with features, which are explained in the beginning of the description (prior art), be combined.

Also can Digitally adjustable filters are used, which is a high flexibility allows. Which also takes into account the power consumption of the circuit must become. This must therefore be at the power supply from the central office via separate Cable cores or over the power supply of the respective POTS application is considered become. Separate power supplies on site, however, are in the Management, however, hardly limited.

1

Amplifier circuitry

2

Low Pass Filter

3

High Pass Filter

4

amplifier

5

customer connection

6

Exchange / Office

7

transmission line

11

POTS frequency range (Phone)

13

DSL-up channel

14

DSL downlink channel

Claims (15)

Method for data transmission via a DSL data connection, in which a booster device (in a long connecting line) ( 1 ), wherein a DSL upstream channel ( 13 ) for data transmission from a customer connection ( 5 ) to a central office and a DSL downstream channel ( 14 ) for reverse data transmission, as well as a filter arrangement for separating both channels ( 13 . 14 ), which is a low-pass filter ( 2 ) and a high-pass filter ( 3 ), characterized in that the filter arrangement comprises two channels ( 13 . 14 ) separating filter frequencies (fu, fo) is operated such that a first the upstream channel ( 13 ) associated filter frequency (fu) and a second the downstream channel ( 14 Filter frequency (fo) are provided, both filter frequencies (fo, fu) in a frequency spacing (.DELTA.f) are located apart from each other and thereby a frequency range is present, in which signals via the low-pass filter ( 2 ) via the high-pass filter ( 3 ) reach. Method according to claim 1, characterized in that by displacing at least one of the filter frequencies (fu, fo) at least one channel region of the upper or lower channel ( 13 . 14 ) and a lowest channel frequency (fku) of the upstream channel ( 13 ) and a top channel frequency (fko) of the downstream channel ( 14 ) remain unchanged, whereby preferably one or both channel areas are reduced. Method according to claim 1, characterized in that by shifting only the filter frequency (fo) of the downstream channel, the upper channel ( 14 ), the filter frequency (fu) of the upstream channel ( 13 ) remains unchanged (fu = ftr) and thus the entire bandwidth of the upstream channel ( 13 ) preserved. Method according to one of the preceding claims, characterized in that the downstream channel ( 14 ) in a higher frequency range than the upstream channel ( 13 ) lies. Method according to one of the preceding claims, in particular according to claim 4, characterized in that only a single channel ( 13 . 14 ), in particular a frequency range of the higher-frequency downstream channel ( 14 ), through an amplifier ( 4 ) is strengthened. Method according to claim 5, characterized in that the entire frequency range (fko - fo) of the downstream channel ( 14 ) is strengthened. Method according to one of the preceding claims, characterized in that the filter arrangement with the high and low pass filter ( 2 . 3 ) is designed as a passive filter arrangement. Method according to one of the preceding claims, characterized characterized in that at least temporarily below the upward channel a telephone channel is present, wherein the telephone channel is an ISDN channel or a channel for an analog Telephone operator. Method according to one of the preceding claims, characterized by an asymmetrical operation such that the frequency width of the downstream channel ( 14 ) is greater than that of the upstream channel ( 13 ). Method according to one of the preceding claims, characterized by a discrete multitone modulation method (DMT) with 255 frequency bands / carriers. Method according to claim 10, characterized in that that the frequency spacing (Δf) an integer multiple of the useful bandwidth of a carrier of a usable frequency range of the DSL data connection and includes individual carriers. Method according to claim 10 or 11, characterized that some or all between the filter frequency (fu) and the Filter frequency (fo) provided carriers are turned off. Method according to one of claims 10 to 12, characterized that between the filter frequency (fu) and the filter frequency (fo) a absorption circuit is interposed with a resonance frequency. Method according to one of the preceding claims, characterized in that the amplifier circuit arrangement ( 1 ) sends a signal on request, constantly or in the commissioning phase, so that adjustments in connection with the frequency interval (Δf) can be made. Method according to one of the preceding claims, characterized characterized in that the filter arrangement by feininstellbare digital filter is formed.