Patent Description:
<CIT> refers to a DSL feature for enabling POTS on digital lines in the event of a power failure.

The need for information exchange and communication has drastically increased. There exists a plurality of different network and communication services that are to be provided to a customer premises equipment (CPE). These services may distinguish in topology, physical and logical infrastructure, transmission paths, content, speed and so on.

An example of these services is the Plain Old Telephone Service (POTS). This POTS is a standard analog telephone service and it did exist before digital services such as Integrated Services Digital Network (ISDN), Digital Subscriber Line (xDSL), Voice over IP (VoIP) services were introduced.

POTS is provided to the CPE via a subscriber line. With the transition to digital services, the actual length of a subscriber line supplying a digital service is oftentimes shortened. This is also based on the fact the short subscriber lines are required for a high quality or bandwidth of a digital service.

Such shortened subscriber lines are also used for POTS signals, which result in audible noise and/or crosstalk.

The problem to be solved is to overcome these drawbacks by improving the analog communication service via subscriber lines.

This problem is solved according to the features of the independent claims. Further embodiments result from the depending claims.

In order to overcome this problem, a network component is provided, which is configured to:.

The network component may be a component of a communications network, e.g., comprising voice and/or data communication. The network component may be a multi-service-access-node (MSAN) or a line card. The network component may interface with at least one, in particular with a plurality of customer premises equipments (CPEs). The network component can provide analog and/or digital services to at least one subscriber line.

The analog communication service may comprise an analog communication service, in particular analog voice communication, analog telephony and/or analog data communication such as analog facsimile. The analog communication service may employ analog signal transmission over a subscriber line.

The subscriber line may be connected to a CPE at a subscriber's home. A connected subscriber line may also be referred to as subscriber loop. The subscriber line may comprise of a pair of wires, referred to as a- and b-wire (also known as ring- and tip-wire). The subscriber line may be a twisted pair cable.

In an embodiment, the criterion of the subscriber line is determined by measurement. Such measurement may be conducted once during an initialization phase of the network component resulting in determining and storing the criterion. The criterion can be used for modifying the electrical parameter.

It is also an option that the measurement is conducted when an analog communication service is to be provided across the subscriber line.

The at least one electrical parameter can be flexibly set, adjusted or modified based on a condition (the criterion) to reduce or limit any disturbance that would otherwise be caused by the at least one electrical parameter when it is conveyed towards the CPE. Hence, a subscriber line may dictate a criterion for set the at least one electrical parameter.

This setting or modifying of the at least one electrical parameter may reduce noise and/or crosstalk induced to the CPE or any other CPE or subscriber line.

It is an option to utilize such setting once per call.

In an embodiment, the analog communication service is the Plain Old Telephone Service.

In an embodiment, the at least one electrical parameter comprises a signaling information.

Signaling information may require electrical parameters (signals) of a predetermined amplitude and/or frequency (repetition of signal pulses).

In an embodiment, the signaling information is at least one of the following:.

In an embodiment, the electrical parameter is a voltage or a current.

The subscriber line may carry a voltage and/or a current of a predetermined amplitude. This amplitude can be adjusted by setting the at least one electrical parameter.

In an embodiment, the network component further comprises a subscriber line test component for determining the criterion of the subscriber line.

Via the subscriber line test component the network component is capable of monitoring and/or testing the individual subscriber line(s). The line test component may be provided by an Integrated Line Test Function (II,TF) module. One dedicated subscriber line test component may be used for several network components, in particular for several line cards.

In an embodiment, the network component is configured to detect a condition of the at least one customer premises equipment.

A condition of the CPE may be based on a change of a state at the CPE, e.g., an off-hook condition (e.g., the picking up the telephone receiver by the user).

Additionally or alternatively, the condition may be a preceding off-hook condition (e.g., a ring tone, a call-progress tone). Hence, the at least one electrical parameter is set based on a previously determined condition.

In an embodiment, the criterion of the subscriber line is at least one of the following:.

A subscriber line may in particular be arranged between the CPE and the network component.

As an option, at least one of the above mentioned criteria may be stored in a memory. Also, the at least one criterion can be compared with a value stored in a memory, in particular in a lookup-table.

In an embodiment, the network component further comprises a digital signal processor to modify the at least one electrical parameter of the analog communication service.

In an embodiment, at least one the coefficient of the digital signal processor is supplied or provided by an external device.

In an embodiment, the network component is further configured to provide at least one digital service to the at least one customer premises equipment via the subscriber line.

The digital service may be one of the following: ISDN, xDSL, VOIP, IPTV.

The digital service can be provided via the same physical subscriber line and may be transmitted simultaneously.

In an embodiment, the network component is further configured to provide at least one additional analog communication service and/or at least one digital service to at least one additional customer premises equipment via at least one additional subscriber line.

Also, a method is suggested for providing an analog communication service, the method comprising:.

In an embodiment, the system further comprises:.

A computer program product is suggested, which is directly loadable into a memory of a digital computer, comprising software code portions for performing the steps of the method described herein.

A computer-readable medium provided having computer-executable instructions adapted to cause a computer system to perform the steps of the method as described herein.

It is noted that the steps of the method stated herein may be executable on the network component.

It is further noted that the above mentioned network component can comprise at least one, in particular several means that are arranged to execute the steps of the method described herein. The means may be logically or physically separated; in particular several logically separate means could be combined in at least one physical unit.

Furthermore, the problem stated above is solved by a system comprising the network component as described above and at least one CPE connected to the network component via a subscriber line.

Said network component may comprise at least one of the following: a processor, a microcontroller, a hard-wired circuit, an ASIC, an FPGA, a logic device.

Embodiments are shown and illustrated with reference to the drawings. The drawings serve to illustrate the basic principle, so that only aspects necessary for understanding the basic principle are illustrated. In the drawings the same reference characters denote like features. These exemplary embodiments do not limit the scope of the invention. The same reference signs in different drawings indicate the same elements/components or at least the same functions unless otherwise stated.

As an example, a network component and a method for providing of an analog communication service, such as the POTS, via the network component to a customer premise equipment (CPE) is proposed, wherein at least one electrical parameter for the analog communication service is modified based on a criterion of the subscriber line.

The network component may be a multi-service-access-node (MSAN) or at least a component thereof. The MSAN connects at least one subscriber line to a core network to provide at least an analog and/or at least one digital service from a single platform. An MSAN may comprise a narrowband service (the POTS), a broadband service (xDSL), a battery with a rectifier, an optical transmission unit or a copper distribution frame.

The network component may provide a number of (subscriber line) ports for digital services, such as internet access and/or for analog communication service, such as the POTS via subscriber lines. The subscriber line may be a physical wire, a phone cable or a coax cable to connect the network component with the CPE. Each of the ports may establish a voice or data connection according to specific DSL and/or G. fast recommendations. It is noted that DSL or G. fast are mentioned as exemplary digital communication standards. However, other communication standards may be used accordingly.

In addition, the network component may provide transport of data traffic via an uplink media, which may be at least one optical fiber connected to a telecommunication service network and/or a POTS network.

The network component may provide switching and/or routing functions for the voice and/or data traffic. As an option, the network component may comprise a memory for storing electrical parameter of the POTS temporarily or persistently.

In an embodiment, the network component is or comprises a line card. The line card may comprise an electronic circuit designed to interface with a service access network. The line card may be connected to at least one subscriber line. On the other side, such subscriber line may be connected to a customer premises equipment, which may be a telephone, modem, or any telecommunication processing device.

The line card may provide analog-to-digital and/or digital-to-analog conversion for voice, data, off-hook detection, ring supervision, line integrity tests, and other BORSCHT functions. BORSCHT is an acronym for battery feed (B), over-voltage protection (O), ringing (R), signaling (S), coding (C), hybrid (H), and test (T). The line card may generate a ringing current and decode Dual Tone Multi Frequency (DTMF) signals, it may further terminate the subscriber line supporting analog communication service. Some line cards may be capable of terminating more than one type of service.

The POTS may use a bi-directional (full duplex) communication via the subscriber line. The communication of voice data may optionally be limited to a narrow frequency range from <NUM> Hertz to <NUM> Hertz (voice band). The POTS may use balanced signaling of a voltage on a two-wire copper loop with a nominal DC voltage amounting to 48V. The POTS may also provide the BORSCHT functions.

The POTS is supplied over a subscriber line. The subscriber line may comprise a twisted pair of wires, referred to as a- and b-wire (also known as ring- and tip-wire). The subscriber line is switched or connected to a subscriber's home. If connected, the subscriber line may be referred to as a subscriber loop.

For signaling purposes, the POTS uses, e.g., metering, ring tones, dial tones, call-progress tones and/or information tones to signal different information and/or statuses to/from the CPE.

A telephone network provider may offer a metering service (also known as "advice of charge" or Teletax) to its telephone subscriber(s). This service allows cost control and cost monitoring by each subscriber. A metering service can be realized by a metering signal that comprises impulses of <NUM> kilohertz or <NUM> kilohertz, which is an example of the POTS signaling.

Ringing is another example of the POTS signaling used for activating a bell or an electronic sound generator at the CPE for alerting purposes. Ringing may precede off-hook conditions. A ringing tone (or ringback tone) applies to a tone (e.g., in the audible frequency range from <NUM> to <NUM>) which is received by an A-subscriber (=caller) via the telephone receiver or loudspeaker while ringing is sent to a B-subscriber (=callee). Ringing (e.g. <NUM>) is made audible by dedicated CPE parts (e.g., not the telephone receiver or loudspeaker), e.g., a bell or an electronic sound generator of a telephone set.

Another example signaling via the POTS are call-progress tones which are audible tones conveying the status of a call to the subscriber. The CPE (e.g., telephone) receives dial tones and/or busy tones, which are used to inform the subscriber about the state of the call and/or to trigger an action of the subscriber.

POTS signaling may comprise a dial-tone that is sent when an off-hook condition is detected. It indicates that the service to be provided is active and that a telephone call may be initiated. The dial tone may stop when the first digit is dialed. The dial tone indicates to the subscriber that now digits may be entered.

Information tones are a further example of the POTS signaling used to transmit data to or from the CPE (e.g., a Frequency Shift Key (FSK) tone used for a Calling Line Identification Presentation, CLIP also known as a Caller ID).

Most of the CPEs (e.g., telephones) suffer from insufficient analog signaling suppression. Thus, the POTS signaling may cause a discomforting noise audible to the subscriber. The audible noise increases with an increasing amplitude of the POTS signaling.

With the transition to a digital service, the POTS can be supplied in combination with at least one digital service (e.g., ISDN, DSL, VOIP, IPTV, etc.) via the same subscriber line.

Thus, the analog communication service may also disturb the digital service by introducing crosstalk to the subscriber line, which may be the subscriber line carrying the analog and the digital service or to other subscriber lines that may, e.g., be arranged within the same cable binder.

Crosstalk can be regarded as any effect introduced by the analog communication service (the POTS) on any service, e.g., the analog communication service itself, another analog communication service or a digital service. Crosstalk may comprise: Near-End-Crosstalk (NEXT), Power-Sum-Near-End-Crosstalk (PSNEXT), Far-End-Crosstalk (FEXT), Equal-Level-Far-End-Crosstalk (ELFEXT) and/or Alien-Crosstalk (AXT).

By modifying an electrical parameter of the analog communication service based on the actual subscriber line (e.g., a length of the subscriber line) the disturbance (noise and/or crosstalk) can at least be partially reduced or prevented.

There are several electrical parameters that could be subject to modification in order to mitigate the disturbance, e.g.:.

The electrical parameter may be based on at least one coefficient of a digital signal processor (DSP). This at least one coefficient can be used to generate an analog signal that may result in the POTS signaling. There may be several sets of coefficients, each set contributing to (or shaping) a particular analog signal.

As an option, the at least one coefficient may be supplied by an external device, e.g., a test device and/or a management device.

Beneficially, the electrical parameter may be adjusted such that the analog signal conveyed across the subscriber line is limited with regard to its disturbance such as noise or crosstalk. The analog signals may be adjusted for several subscriber lines, optionally for all subscriber lines, of the network component.

<FIG> shows a schematic of an exemplary hardware comprising a MSAN <NUM> as an example of a network component and at least one CPE <NUM> that is connected to the MSAN <NUM> via a subscriber line <NUM>. Further CPEs <NUM>', <NUM>" are connected to the MSAN <NUM> via further subscriber lines <NUM>', <NUM>" (dashed lines).

The MSAN <NUM> provides a POTS <NUM> to the CPE <NUM> via the subscriber line <NUM>. Therefore, a port of a POTS line card <NUM> is electrically coupled to the subscriber line <NUM> to relay the POTS <NUM> via the subscriber line <NUM> to the CPE <NUM>.

A subscriber loop resistance is an ohmic resistance comprising the resistance of the subscriber line <NUM> (including the a- and b-wire, in particular a twisted pair cable) and the resistance value of the CPE <NUM>. A maximum resistance of the subscriber loop in the POTS refers to a maximum length L of, e.g., <NUM> kilometers of the a-wire or the b-wire, which in this example in total refers to a subscriber line length of <NUM> kilometers.

By using standardized twisted pair copper cable, the maximum ohmic resistance may amount to <NUM> Ohms for a maximum length of <NUM> kilometers between the CPE <NUM> and the network component <NUM>.

If the subscriber line <NUM> may be used for digital services, such as xDSL, G. fast, VOIP, the subscriber line <NUM> may be substantially shorter than the maximum subscriber line length admissible for the POTS. For instance, VOIP may have a line length L that is less than <NUM> kilometer.

The electrical parameters of the POTS signaling are set to meet the standardized requirements even if the subscriber line <NUM> is substantially longer than <NUM> kilometer. If the POTS signaling is conveyed towards the CPE <NUM>, noise and/or crosstalk may be recognized at the receiver of the CPE <NUM> or at any of the receivers of the CPEs <NUM>' or <NUM>".

To minimize these disturbances at least one of the electrical parameters of analog signaling towards the CPEs is modified. This may in particular be achieved based on the length L or based on a measurement that determines or estimates this length L of the subscriber line <NUM>.

An Integrated Line Test Function (ILTF) <NUM> of the POTS line card <NUM> can be used to monitor or to test the subscriber line <NUM>. The ILTF <NUM> may thus determine a criterion of the subscriber line <NUM>. The electrical parameter of the POTS signaling may then be adjusted based on this criterion.

Determining the criterion of the subscriber line <NUM> may comprise at least one of the following:.

The criterion of the subscriber line <NUM> may be obtained by measuring a feeding voltage applied at the port of the POTS line card <NUM>. A constant current may be applied to this port. It is also an option that the feeding voltage or current is received or polled without any measurement.

At least one of these determined criteria is used to modify the electrical parameter of the POTS signaling. As an option, a look-up table (LUT) of the network component may be used to determine the actual electrical parameter based on the criterion.

An example might be as follows: A resistance loop of the subscriber line <NUM> amounts to <NUM> Ohm and has a length L of <NUM> kilometers. This corresponds to a reduction of <NUM>% (because of half the length of the loop). Thus, POTS signaling may be reduced by <NUM>%, the actual DSP coefficients may be obtained from the lookup-table stored in the network component. Hence, the lookup-table may comprise entries that determine a (range) of reduction in percent and corresponding values of the DSP coefficients. The DSP coefficients can be read from the lookup-table and used to generate adjusted (modified) electrical parameters that result in a reduced amount of disturbance compared to the full amplitude of these electrical parameters.

As an option, the network component may detect an off-hook condition at the CPE <NUM>. This may trigger that the amplitude of the POTS signaling is reduced. In case of a preceding off-hook-condition, a disturbance due to a ringing tone or other signaling preceding the off-hook can be mitigated.

If an impending POTS signaling is detected at the MSAN <NUM>, the ILTF <NUM> may determine at least one criterion of the subscriber line <NUM>, e.g., by determining the subscriber loop resistance. Depending on this criterion, the amplitude of the POTS signaling may be adjusted. The amplitude may refer to various electrical signals used for signaling purposes, e.g., metering impulses, ringing, dial tones, call-progress tones or information tones.

The electrical parameter to be modified may be represented as at least one coefficient of a DSP, which may be part of the MSAN <NUM> or the line card <NUM>. This at least one coefficient may be used to generate the analog signal to be conveyed towards the CPE <NUM>. By modifying the at least one coefficient, the respective electrical parameter of the generated POTS signaling is adjusted.

<FIG> shows a schematic of another exemplary hardware comprising a MSAN <NUM> for supplying the POTS <NUM> and at least one digital service <NUM> to a CPE <NUM>'. The MSAN <NUM> comprises a control and switching unit <NUM>, a POTS line card <NUM>, a splitter <NUM> and a digital line card <NUM>. The POTS line card <NUM> comprises an ILTF <NUM> and the digital line card <NUM> comprises a line test unit <NUM>. The line test unit <NUM> may provide single ended line test (SELT), double ended line test (DELT) and/or metallic line test (MELT) capabilities. The POTS <NUM> and/or the digital service <NUM> may be conveyed across the control and switching unit <NUM>, the POTS line card <NUM>, the digital line card <NUM> and/or the splitter <NUM> to the various CPEs <NUM>, <NUM>' and <NUM>".

The digital line card <NUM> may be a part of a Digital Subscriber Line Access Multiplexer (DSLAM) (not shown).

The CPE <NUM> comprises a telephone set <NUM> and is supplied with the POTS <NUM> by the POTS line card <NUM> via the subscriber line <NUM>.

The CPE <NUM>' comprises a telephone set <NUM>', a DSL modem <NUM>' and a splitter <NUM>'. The splitter <NUM>' is connected to the telephone set <NUM>' and the DSL model <NUM>'. The splitter <NUM>' is connected to a splitter <NUM> of the MSAN <NUM> via a subscriber line <NUM>'. The POTS line card <NUM> and a digital line card <NUM> are connected to the splitter <NUM>. The telephone set <NUM>' is supplied with the POTS <NUM> and the DSL modem <NUM>' is supplied with the digital service <NUM>.

The CPE <NUM>" comprises a DSL modem <NUM>" and is supplied with the digital service <NUM> by the digital line card <NUM> via the subscriber line <NUM>".

The control and switching unit <NUM> can be used to control providing the services <NUM>, <NUM> towards the CPEs <NUM>, <NUM>' and <NUM>".

A test system <NUM> can be used to manage testing and monitoring of the MSAN <NUM>. This test system <NUM> may be arranged to manage the measurement of the subscriber lines <NUM>, <NUM>', <NUM>" to obtain the criterion for modifying the POTS signaling. The test system <NUM> may supply signaling parameters via an application programming interface (API) to the MSAN <NUM>. The test system <NUM> may be an external device or it may be a part of the MSAN <NUM>.

The electrical parameter to be modified may be based on at least one coefficient of a DSP, which may be located inside the MSAN <NUM> or on the line card <NUM>. This at least one coefficient may be used for generating the POTS signaling. The at least one coefficient may be optionally provided by the test system <NUM>.

<FIG> shows a schematic of another exemplary hardware comprising a MSAN <NUM> for determining a subscriber line criterion.

The MSAN <NUM> is connected to a CPE <NUM> via a subscriber line <NUM>. The subscriber line <NUM> comprises a twisted pair cable (e.g., copper wires) consisting of wires 104a and 104b.

The MSAN <NUM> comprises a line card <NUM>, which is used to provision a POTS <NUM>. The line card <NUM> detects an off-hook condition or a preceding off-hook condition of the CPE <NUM>. In order to modify an electrical parameter of the POTS signaling, the resistance of the line is determined by the line card <NUM>. This resistance comprises the resistances of the wires 104a, 104b and a resistance <NUM> of the CPE <NUM>. Based on the overall resistance, the electrical parameter for the POTS signaling is modified.

<FIG> shows an exemplary flow diagram comprising steps of a method <NUM> for modifying an electrical parameter for providing an analog communication service.

The method <NUM> comprises a step <NUM> in which an analog communication service is provided towards a CPE. In a step <NUM> an analog signaling condition is detected. Such an analog signaling condition may be an off-hook condition or a preceding off-hook condition of the CPE. In a step <NUM> a subscriber line criterion is determined and in a step <NUM> an electrical parameter of the analog signaling of the analog communication service is modified.

If the network component detects an off-hook condition or an preceding off-hook condition, it may start a measurement of the subscriber loop resistance, which is one example of determining a criterion of the subscriber line. Depending on the measurement result, at least one signaling coefficient for the POTS signaling is adjusted. The POTS signaling may comprise metering impulses, ringing, dial tones, call-progress tones and information tones.

It is noted that the at least one coefficient may be provided by an API without any measurement and/or they are subject to at least one measurement cycle.

Claim 1:
A network component configured to:
- providing an analog communication service (<NUM>) to at least one customer premises equipment (<NUM>) via a subscriber line (<NUM>); and
- setting at least one electrical parameter of the analog communication service (<NUM>) based on a criterion of the subscriber line (<NUM>), wherein the electrical parameter is based on at least one coefficient of a digital signal processor, wherein the setting of the at least one electrical parameter is for reducing or preventing disturbance of the communication by modifying analog signaling towards the customer premises equipment (<NUM>);
- wherein the network component is a multi-service-access-node or at least a component thereof;
- wherein the network component comprises a subscriber line test component (<NUM>) for determining the criterion of the subscriber line (<NUM>),
- wherein the at least one coefficient is used to generate an analog signal for the analog communication service,
- wherein the network component is further configured to provide at least one digital service (<NUM>) to the at least one customer premises equipment (<NUM>) via the subscriber line (<NUM>).