GB2602457A - Component for connection at network termination point - Google Patents

Abstract

A component for connection at a network termination point demarcating an access network from a home network, the component configured to monitor at least one characteristic of the home network S202; receive a signal from the access network S204; modulate the signal received from the access network to encode a representation (e.g. a watermark) of the at least one characteristic S206; and send the modulated signal to the access network S208. The component may be a dongle connectable to network termination equipment (NTE) for connection to a digital subscriber line (DSL) to a home modem or may itself be NTE. The characteristics monitored may be indicative of whether the home network is connected to the access network, and may include an electrical characteristic of the home network. The modulated signal may be an amplitude, frequency or phase modulated signal. A gateway device comprising the component is also disclosed.

Description

COMPONENT FOR CONNECTION AT NETWORK TERMINATION POINT

Technical Field

This invention relates to a component for connection at a network termination point, and to use of components for connection at a network termination point.

Background

Digital subscriber line (DSL) services, commonly referred to as "broadband" services, are deployed using metallic public switched telephone network (PSTN) lines that run between a digital subscriber line access multiplexer (DSLAM) and modems in subscribers' properties. With asymmetric DSL (ADSL) the DSLAM is located in the exchange and the line can be typically up to 7km in length. With very-high bit-rate DSL (VDSL), the DSLAM is located in a local cabinet with the line being much shorter, typically a maximum of 2km. The line is normally made up of a twisted copper pair, but can include lengths of aluminium.

Faults on DSL lines are not uncommon, and currently most faults are found by customers reporting problems such as their line being noisy, having slower than expected broadband speed, or even interrupted broadband service. Troubleshooting a fault often includes performing line tests on the line. Line tests can also be performed proactively to identify faults before a customer reports them. These line tests are typically electrical line tests that measure the electrical characteristics of a line and check that the results meet a standard (for example, as set out in SIN349 by British Telecommunications plc). It is also possible to compare line tests over a period of time to see if the line's electrical characteristics are deteriorating. Once a fault has been detected, an engineer can use electrical line testing, typically pair quality tests, to try and determine where the fault is located and make the appropriate repairs.

Some lines traverse private premises for which access is unavailable. Tests such as electrical line tests (ELTs) and single-ended line tests (SELTs) can be used to locate faults in lines such as this. However, the results of these tests can be inconclusive without knowledge of the network or components within the private premises. For example, both ELTs and SELTs can be used to determine a variation in loop length (which is e.g. an approximation of the physical length of the line). However, without knowledge of the network within a particular premises, it can be difficult to determine whether a foreshortening of the measured loop length indicates a disconnection within the premises or outside the premises.

Summary

According to a first aspect of the present disclosure, there is provided a component for connection at a network termination point demarcating an access network from a home network, the component configured to: monitor at least one characteristic of the home network; receive a signal from the access network; modulate the signal received from the access network to encode a representation of the at least one characteristic; and send the modulated signal to the access network.

In some examples, the component is a dongle connectable to network termination equipment arranged at the network termination point. In some of these examples, the dongle is connectable to a network interface of the network termination equipment for connection to a digital subscriber line to a home modem. In some of these examples, the dongle is configured to monitor the at least one characteristic by monitoring whether the dongle is connected to the network termination equipment.

In some examples, the component is network termination equipment. In some of these examples, the network termination equipment is further configured to monitor whether the network termination equipment is connected to at least one further electrical component and/or a power 20 source.

In some examples, the component comprises: a module to monitor the at least one characteristic; and a controller to receive the signal, modulate the signal and send the modulated signal to the access network.

In some examples, the signal received from the access network is a line testing signal.

In some examples, modulating the signal received from the access network comprises modulating the signal received from the access network to include a watermark indicative of the at least one 30 characteristic In some examples, the at least one characteristic comprises a characteristic indicative of whether the home network is connected to the access network at the network termination point.

In some examples, the at least one characteristic comprises an electrical characteristic of the home network.

In some examples, the component is associated with an identifier, and the component is configured to modulate the signal received from the access network to further encode a representation of the identifier.

In some examples, the component is configured to modulate the signal received from the access network to further encode a representation of a modulation scheme used to modulate the signal received from the access network.

In some examples, the component is configured to modulate the signal using a carrier voltage.

In some examples, the modulated signal comprises at least one of: an amplitude modulated signal, a frequency modulated signal and a phase modulated signal. In some of these examples, the component is configured to modulate the signal to adjust an amplitude of a plurality of nonadjacent frequencies of the signal received from the access network to encode the representation of the at least one characteristic. In some of these examples, the component is configured to: monitor a plurality of characteristics of the home network; and modulate the signal such that the amplitude of each respective one of the plurality of non-adjacent frequencies indicates a state of a corresponding one of the plurality of characteristics.

According to a second aspect of the present disclosure, there is provided a gateway device comprising the component according to any example in accordance with the first aspect of the present disclosure.

According to a third aspect of the present disclosure, there is provided a method comprising: monitoring at least one characteristic of a home network, using a component connected at a network termination point demarcating an access network from the home network; receiving a signal from the access network; modulating the signal received from the access network to encode a representation of the at least one characteristic; and sending the modulated signal to the access network.

In some examples of the third aspect, the component is a dongle connected to network termination equipment arranged at the network termination point. In some of these examples, the dongle is connected to a network interface of the network termination equipment for connection to a digital subscriber line to a home modem.

In some examples of the third aspect, the component is network termination equipment.

In some examples of the third aspect, the signal received from the access network is a line testing signal.

In some examples of the third aspect, modulating the signal received from the access network comprises modulating the signal received from the access network to include a watermark indicative of the at least one characteristic.

In some examples of the third aspect, the at least one characteristic comprises a characteristic indicative of whether the home network is connected to the access network at the network termination point.

Examples in accordance with the present disclosure may include any novel aspects described and/or illustrated herein. The disclosure also extends to methods and/or apparatus substantially as herein described and/or as illustrated with reference to the accompanying drawings. Any apparatus feature may also be provided as a corresponding step of a method, and vice versa Any feature in one aspect of the disclosure may be applied, in any appropriate combination, to other aspects of the disclosure. Any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination. Particular combinations of the various features described and defined in any aspects of the disclosure can be implemented and/or supplied and/or used independently.

As used throughout, the word 'or' can be interpreted in the exclusive and/or inclusive sense, unless otherwise specified.

Brief Description of the Drawings

For a better understanding of the present disclosure, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 is a system diagram showing a telecommunications network including a component for connection at a network termination point according to examples; Figure 2 is a flow diagram of a method using a component for connection at a network termination point according to examples; Figure 3 is a schematic diagram of a component for connection at a network termination point according to examples; Figure 4 is a schematic diagram of a component for connection at a network termination point according to further examples; Figures 5a and 5b are plots showing a variation in voltage of a DSL line connected to a home modem according to examples; Figure 6 is a schematic diagram of a component for connection at a network termination point according to yet further examples; Figure 7 is a schematic diagram of a plug sensor switch according to examples; Figure 8 is a schematic diagram of a plug sensor switch according to further examples; Figures 9a and 9b are plots showing the modulation of a signal to encode a representation of a characteristic according to examples; Figure 10 is a plot showing the encoding of a representation of a characteristic according

to further examples;

Figure 11 is a schematic diagram of circuitry to modulate a signal to encode a representation of a characteristic according to examples; and Figures 12a and 12b are plots showing, respectively, full rejection and partial rejection of a signal of a particular frequency.

Detailed Description

Apparatus and methods in accordance with the present disclosure are described herein with reference to particular examples. The invention is not, however, limited to such examples.

Figure 1 illustrates a simplified system diagram of a telecommunications network 100, which in this example is an asymmetric digital subscriber line (ADSL) network. Some elements have been omitted for simplicity, and conversely in some practical deployments, some elements shown are not required. Similarly, some elements described as being overhead may be underground.

The telecommunications network 100 includes an exchange building 102 housing a digital subscriber line access multiplexer (DSLAM) 104 and line test equipment 106. The DSLAM 104 provides digital subscriber line (DSL) services to connected lines and associated customer premises. The connected lines are thus also referred to as digital subscriber lines, or DSL lines, though it will be appreciated that the lines can also provide PSTN services. The lines normally comprise a metallic pair, such as copper or aluminium, which is typically a twisted metallic pair.

A multi-pair cable 108 (comprising multiple lines) connects the DSLAM 104 to a Primary Cross Connection Point (PCP) 110. From the PCP 110, DSL lines 112a, 112b, 112c (collectively referred to as DSL lines 112) each extend to a respective customer premises 114a, 114b, 114c (collectively referred to as customer premises 114). Each of the DSL lines 112 is connected to a respective network termination equipment (NTE) 116a, 116b, 116c (collectively referred to as NTEs 116). Each of the NTEs in this case is arranged at a network termination point demarcating the part of the telecommunications network 100 associated with the operator (which in this case is an access network), and the part of the telecommunications network 100 associated with the customer, which may be referred to as a home network. In other words, each of the NTEs 116 corresponds to a demarcation point within the telecommunications network 100.

Each of the NTEs 116 is connected to a home modem 118a, 118b, 118c (collectively referred to as home modems 118) via respective further DSL lines 120a, 120b, 120c (collectively referred to as further DSL lines 120). The home modems 118 are for example DSL modems or hubs. The further DSL lines 120 are for example internally wired within the respective customer premises 114.

Figure 2 is a flow diagram of a method 200 using a component, such as one of the NTEs 116 of Figure 1, for connection at a network termination point according to examples. The method 200 of Figure 2 for example allows a home network to be monitored remotely, in a straightforward manner. For example, it can be determined with greater accuracy that the home network is disconnected from the access network at a particular point in a telecommunications network (in this case, the network termination point), which can improve the performance of a line test compared to existing approaches in which there may be uncertainty as to whether the home network is disconnected or at which location the home network is disconnected from the access network.

At item S202 of Figure 2, at least one characteristic of a home network is monitored, using the component connected at the network termination point. Examples of a suitable component are discussed further below with particular reference to Figures 3, 4 and 6. At item S204 of Figure 2, a signal is received from an access network, which may be a line test signal or another signal, e.g. sent before the start of a line test or sent periodically to monitor the status of the home network. At item S206 of Figure 2, the signal received from the access network is modulated to encode a representation of the at least one characteristic. At item S208 of Figure 2, the modulated signal is sent to the access network.

With the method 200 of Figure 2, the at least one characteristic of the home network can be derived from the modulated signal at the access network, without requiring access to the customer premises 114. In this way, the at least one characteristic can be obtained without manually performing measurements within the customer premises 114, such as the further DSL lines 120 shown in Figure 1. The home network can hence be monitored more straightforwardly than otherwise, and with improved accuracy (as manual measurements can be prone to errors).

Furthermore, the method 200 can be used in situations in which the customer premises 114 is inaccessible.

Figure 3 is a schematic diagram of a component for connection at a network termination point according to examples. Features of Figure 3 that are similar to corresponding features of Figure 1 are labelled with the same reference numeral, incremented by 200; corresponding descriptions are to be taken to apply. In the example of Figure 3, the component is a dongle 322. As the skilled person will appreciate, a dongle 322 is for example a small device that is connectable to a port of another device, for example to provide additional functionality. For example, the dongle 322 may be a portable device, which may be utilised by an engineer performing a line test.

In Figure 3, the dongle 322 is connected to an NTE 316. As the dongle 322 is connected to the NTE 316 (which is arranged at a network termination point demarcating an access network from a home network), the dongle 322 itself is considered to be connected at the network termination point. The NTE 316 is connected to a DSL line 312 to an access network via a first network interface 324a. The NTE 316 also includes a second network interface 324h for connection to a DSL line to a home modem (such as the further DSL line 120 shown in Figure 1). However, in Figure 3, the second network interface 324b is connected to the dongle 322 instead of the DSL line to the home modem. For ease of illustration, Figure 3 shows the second network interface 324b as connected to the dangle 322 via a line 326 extending between the NTE 316 and the dongle 322. However it is to be appreciated that the line 326 may, in some examples that are otherwise the same as Figure 3, be internal to the dongle 322, and may, for example, correspond to an electrical connection between the second network interface 324b and internal components of the dongle 322. In other words, in these other examples, a plug of the dongle 322 may be directly inserted into a suitable socket of the NTE 316 (which for example corresponds to the second network interface 324b).

The NTE 316 in this example includes solely one network interface for connection to the DSL to the home modem (the second network interface 324b). On this basis, the physical connection of the dongle 322 to the NTE 316 means that other wiring and/or equipment cannot be plugged into this network interface at the same time. Hence, by connecting the NTE 316 of Figure 3 to the dongle 322 instead of the home modem, the home network is disconnected from the access network at the network termination point. In other words, connection of the dongle 322 at the second network interface 324b indicates disconnection of the home network from the access network at the network termination point. Knowledge of connection of the dongle 322 at the second network interface 324b (and, hence, disconnection of the home network from the access network) can be exploited to improve the accuracy of a line test performed on the DSL line 312 to the access network.

For example, an engineer can visit a customer premises 114 to which the DSL line 312 to be tested is connected. The engineer can disconnect the equipment within the customer premises, for example by disconnecting the DSL line 120 to the home modem 118 from the second network interface 324b of the NTE 316. The engineer can then connect the dongle 322 to the NTE 316. For example, the dongle 322 can be connected to the NTE 316 before a remote line test such as an ELT or a SELT is performed.

In some cases, the dongle 322 is connected to the NTE 316 by plugging the dongle 322 into a faceplate of the NTE 316. Some NTEs 316 have network interfaces (e.g. corresponding to respective sockets of the faceplate) for a plurality of different services such as PSTN and broadband (e.g. VDSL). For example, a socket may be a filtered socket, which may be referred to as a filter, a microfilter or a splitter. In this context, a filter includes a plurality of ports to provide different respective services (e.g. a port for connection to a home modem 118 and another port for connection to telephone equipment). In examples in which an NTE has a plurality of network interfaces, the dongle 322 is connected to the network interface that is appropriate to the test being performed. For example, to perform a SELT of broadband services provided by a DSL line 312 to the access network, the dongle 322 can be connected to the network interface for use in providing the broadband services (i.e. the second network interface 324b in the example of Figure 3) In some cases, a faceplate and a filter of an NTE 316 are removable, allowing the dongle 322 to be directly connected to the NTE 316 (e.g. to a portion of the DSL line 312 within the NTE 316, for example via an internal test socket of the NTE 316), rather than connecting the dongle 322 to the NTE 316 via an external interface. This provides further assurance that the equipment within the customer premises 114 has been disconnected.

In Figure 3, the dongle 322 is configured to monitor at least one characteristic of the home network. In this case, the dongle 322 is configured to monitor the at least one characteristic by monitoring whether the dongle 322 is connected to the NTE 316. Monitoring whether the dongle 322 is connected to the NTE 316 can, in this case, be used as a proxy for monitoring whether the home network is connected to the access network at the network termination point, since the connection of the dongle 322 to the NTE 316 indicates, in turn, that the home modem is disconnected and hence that the home network is disconnected from the access network. The dongle 322 can monitor whether the dongle 322 is connected to the NTE 316 in various ways.

For example, if the dongle 322 receives a signal (e.g. a signal with particular characteristics, such as a particular frequency and/or amplitude), this may be taken as an indication that the dongle 322 is connected to the NTE 316. Conversely, the absence of such a signal can be taken as an indication that the dongle 322 is disconnected from the NTE 316.

The dongle 322 is configured to receive a signal from the access network, via the DSL line 312 to the access network and the NTE 316. The dongle 322 then modulates the signal received from the access network to encode a representation of the at least one characteristic of the home network (which in this example is an indication of whether the home network is connected to the access network). In the dongle 322 of Figure 3, the modulation of the signal is performed by a controller 328, which is for example suitable control circuitry configured to modulate received signals. Example circuitry is shown in Figure 11, discussed in more detail below. The modulated signal is then sent back to the access network, via the NTE 316 and the DSL line 312.

In this way, a determination of whether the home network is connected to the access network can be performed remotely, based on analysis of the signal returned to the access network. This allows it to be determined that the DSL line 312 has been disconnected at a predetermined location (which in this case corresponds to the location of the NTE 316 to which the DSL line 312 is connected), without accessing the customer premises 114. This can be used to improve the accuracy of a line test. For example, the modulated signal provides more certainty of a characteristic of the home network (in this case, that the NTE 316 has been disconnected from a home modem) than a manual determination (e.g. performed by an engineer), which can be subject to errors. In other words, the presence of the dongle 322, and hence the disconnection of the home network from the access network, can be more accurately verified. Properties of the DSL line 312 (e.g. length) between the DSLAM 104 and the NTE 316 are typically readily available to a service provider, as the DSL line 312 is generally accessible to the service provider. Hence, if line tests performed on the DSL line 312 after disconnection indicate that the measured properties of the disconnected DSL line 312 (e.g. length) differ from the expected properties, a fault can be detected with greater accuracy than in existing systems, in which properties of a DSL line which at least partly traverses private premises are generally not known or are not easily accessible or in which it is uncertain whether a DSL line has genuinely been disconnected at a particular location within a telecommunications network 100.

Use of a dongle 322 for example allows line tests to be improved without modification of the NTE 316 itself. Line tests can hence be improved more straightforwardly than with other approaches that involve alterations to other circuitry (such as circuitry of the NTE 316 itself).

The signal received by the dongle 322 may be sent prior to the performance of a line test, for example to check that the home network has been disconnected before the commencement of a line test. In other cases, though, the signal received from the access network is a line testing signal. In these cases, the line testing signal itself is modulated to encode an indication of whether the home network is connected to the access network. This provides more certainty than modulation of a signal prior to the line test, as the home network could for example be reconnected to the access network after the signal prior to the line test has been modulated, but before a line testing signal is received. As will be appreciated, the line test may be any test which returns a frequency response, such as an SELT, a SELT or a metallic line test (MELT).

In some cases, the dongle 322 modulates the signal received from the access network to include a watermark indicative of the at least one characteristic, i.e. indicative of whether the home network is connected to the access network. A watermark for example allows the at least one characteristic to be encoded in the signal without unduly affecting the signal. For example, watermarking of a signal can be performed while leaving a majority of the original signal intact or recoverable. This can be beneficial when the signal is a line testing signal, as it allows a representation of the at least one characteristic (e.g. the indication of whether the home network is connected to the access network) to be encoded in the modulated signal without affecting the result of the line test. Modulation of a signal to encode a representation of at least one characteristic of a home network is discussed further with reference to Figures 9 to 12.

Figure 4 is a schematic diagram of a component for connection at a network termination point according to further examples. Features of Figure 4 that are similar to corresponding features of Figure 1 are labelled with the same reference numeral, incremented by 300; corresponding descriptions are to be taken to apply. In the example of Figure 4, the component is a NTE 416, which is arranged at a network termination point demarcating an access network from a home network. The NTE 416 is connected to a DSL line 412 to an access network via a first network interface 424a. The NTE 416 also includes a second network interface 424b for connection to a DSL line 420 to a home modem 418. The first and second network interfaces 424a, 424b are connected via a line 436, for sending signals received from the DSL line 412 to the access network to the DSL line 420 to the home modem 418 (when the home modem 418 is connected to the NTE 416). Like the dongle 322 of Figure 3, the NTE 416 of Figure 4 is configured to monitor at least one characteristic of the home network. In some cases, the at least one characteristic monitored is relevant to a line test on the incoming DSL line 412 (such as whether the home network is connected to the access network at the network termination point). In these cases, by monitoring the at least one characteristic, the accuracy of the line test can be improved, without requiring access to the customer premises 114. In other cases, though, the NTE 416 may additionally or alternatively monitor another characteristic that is not relevant to a line test, such as a characteristic that is relevant for a diagnostic system other than line test equipment 106.

The NTE 416 of Figure 4 includes a module 430 to monitor the at least one characteristic of the home network, and a controller 428 to receive a signal from an access network, modulate the signal received from the access network to encode a representation of the at least one characteristic, and send the modulated signal to the access network. The controller 428 is connected to the module 430 via a line 432, and the module 430 is located between the controller 428 and the second network interface 424b. The module 430 is connected to the second network interface 424b via a further line 437 so that the module 430 can monitor, for example, an electrical characteristic of the home network. The modulation of the signal is for example similar to the signal modulation described with reference to the dongle 322 of Figure 3, described in detail with reference to Figures 9 to 12. Although not shown in Figure 4, it is to be appreciated that each of the lines 432, 436, 437 shown in Figure 4 may include a pair of lines.

The NTE 416 may be used to monitor the at least one characteristic of the home network periodically, e.g. at predetermined intervals (a duration of which may be constant or may vary over time), or in response to the occurrence of a particular event, such as connection of a component to the NTE 416 (e.g. to a faceplate of the NTE 416), reconnection of the faceplate of the NTE 416 Of the faceplate was previously removed), or receipt of a command signal, e.g. via the DSL line 412. For example, the NTE 416 may monitor the at least one characteristic before a line test is performed. In such cases, the signal modulated may be a signal sent before the line test is performed, or the line test signal itself. A line test is typically performed with the home network disconnected from the access network. Hence, to perform a line test on the DSL line 412 to the access network, the further DSL line 420 to the home modem 418 is typically disconnected from the second network interface 424b of the NTE 416.

An NTE such as the NTE 416 may monitor at least one of various characteristics of the home network. Characteristics that may be monitored include: * whether the home network is connected to the access network at the network termination point (which in this case corresponds to the NTE itself). ;* an electrical characteristic of the home network, such as the voltage or current level. An electrical characteristic can be used to infer activity within the home network, which may impact on the result of a diagnostic test such as a line test.

In the example of Figure 4, the module 430 of the NTE 416 includes a line voltage sensor which is arranged to monitor the voltage on the DSL line 420 to the home modem 418 (as the voltage on the further line 437 to which the module 430 is connected is for example the same or substantially the same as the voltage on the DSL line 420 to the home modem 418). The voltage can be monitored by the line voltage sensor over time, to identify a variation in the voltage over time.

Figures 5a and 5b are plots to illustrate two different examples of the voltage measured by a line voltage sensor of an NTE over time, for a DSL line connected between the NTE and a home modem, such as the DSL line 420 of Figure 4. The voltage is for example a DSL carrier voltage. The plot 500a of Figure 5a shows the voltage with the home modem connected to the NTE and connected to a power source. The plot 500a of Figure 5a illustrates that the voltage varies over time as broadband traffic is sent and/or received over the DSL line. In contrast, the plot 500b of Figure 5b shows the voltage with the home modem disconnected from the NTE On other words, with the home network disconnected from the access network). In the plot 500b of Figure 5b, the voltage remains constant over time. On this basis, by monitoring the voltage, the NTE can identify activity performed within the home network (in this case, whether the home modem is connected and receiving broadband traffic). For example, if a voltage indicative of a home modem being connected to the NTE and to a power source is detected shortly prior to a line test, it may be assumed that the home modem was also on during the line test itself. This information can be used to interpret the line test result, as the presence of a powered on home modem typically alters the response to a line test signal.

Figure 6 illustrates another example of an NTE 616 for connection at a network termination point. Features of Figure 6 that are similar to corresponding features of Figure 4 are labelled with the same reference numeral, incremented by 200; corresponding descriptions are to be taken to apply. The NTE 616 of Figure 6 is the same as the NTE 416 of Figure 4 except for the module 630. Whereas the module 430 of Figure 4 is configured to monitor the voltage on the DSL line 420 to the home modem 418, the module 630 of Figure 6 includes a plug sensor switch, which is configured to monitor whether the DSL line 620 to the home modem 618 is connected to the NTE 616 (and hence whether the home network is connected to the access network). The plug sensor switch is connected to the controller 628 via two lines 632, 634, so that the controller 628 can encode a representation of the state of the plug sensor switch (which e.g. indicates whether the home network is connected to the access network) by modulating a signal received from the access network via the DSL line 612. The DSL line 612 is connected to the NTE 616 via a first network interface 624a. Signals received via the DSL line 612 are sent in parallel to the module 630 via the controller 628 and the two lines 632, 634, and to a second network interface 624b of the NTE 616 via a further line 636, for sending to the DSL line 620 to the home modem 618 (when the home modem 618 is connected to the NTE 616).

Figures 7 and 8 are schematic diagrams of two example plug sensor switches 738, 838 that may be used in an NTE such as the NTE 616 of Figure 6. Features of Figures 7 and 8 that are similar to corresponding features of Figure 6 are labelled with the same reference numeral but incremented by 100 and 200, respectively; corresponding descriptions are to be taken to apply.

In Figure 7, a further DSL line 720 to a home modem terminates in a plug 740, which is connected to a socket 724b of an NTE (which in this case corresponds to the second network interface 624b of Figure 6). The socket 724b is connected to a DSL line 712 to the access network and is also connected to a controller (such as the controller 628 of Figure 6, not shown in Figure 7) via two lines 732, 734. Figure 7 shows schematically a connection point 742 between the DSL line 712 and the further DSL line 720. However, it is to be appreciated that the DSL line 712 and/or the further DSL line 720 may be connected to the connection point 742 directly (without intervening components) or indirectly, e.g. via a further line such as the further line 636 of Figure 6.

In the example of Figure 7, the plug sensor switch 738 is an electrical contact on the socket 724b, which is toggled by plugging the plug 740 into the socket 724b. In this way, a signal can be sent to the controller, indicating the state of the plug sensor switch 738 (i.e. whether the switch 738 is open or closed), and hence indicating whether a plug 740 is plugged into the socket 724b. This is an example of a characteristic of the home network, which can be encoded in a signal received by the controller from an access network.

The arrangement of Figure 8 is similar to that of Figure 7. However, in Figure 8, the plug sensor switch 838 includes a reed switch 844, which is actuated by a magnet 846 arranged in a plug 840 of the further DSL line 820. The reed switch 844 is connected to a controller (such as the controller 628 of Figure 6, not shown in Figure 8) via two lines 832, 834. The reed switch 844 is toggled when the plug 840 is inserted into a socket 824b of an NTE (which in this case corresponds to the second network interface 624b of Figure 6). The socket 824b is also connected to a DSL line 812 to the access network, so as to connect the DSL line 812 to the further DSL line 820 via a connection point 842 with the plug 840 inserted in the socket 824b.

In some cases, an NTE such as the NTEs 416, 616 of Figures 4 and 6 are further configured to monitor at least one further characteristic associated with the NTE, such as whether the NTE is connected to at least one further electrical component and/or a power source. For example, the NTE may include at least one further socket than a socket for connection to a DSL line to a home modem. In such examples, the NTE may include, for each further socket, a plug sensor switch such as the plug sensor switches 738, 838 of Figures 7 and 8, but arranged to be detect whether a plug is connected to the further socket. In addition or instead, the NTE may include suitable circuitry to detect whether the NTE is connected to a power source or whether the NTE is open-circuited or short-circuited.

As explained above, after monitoring of at least one characteristic of a home network, components according to examples herein (such as a dongle or an NTE) are configured to modulate a signal received from an access network to encode a representation of the at least one characteristic. It is to be appreciated that a signal may be modulated in various different ways. In some examples, a signal is modulated using a carrier voltage to encode a representation of the at least one characteristic. For example, the modulated signal may include an amplitude modulated signal, a frequency modulated signal and/or a phase modulated signal. This allows the modulated signal to be provided straightforwardly, exploiting existing mechanisms for generating signals using network-side signalling equipment (which may be similar to those employed by the DSLAM 104 of Figure 1).

In some examples, the carrier voltage is itself modified to encode the representation of the at least one characteristic. For example, the amplitude of the carrier voltage may be modified (e.g. by changing the carrier voltage to a higher or lower voltage or to zero volts), to encode the representation of the at least one characteristic. In other examples, the carrier voltage is unmodified, but at least one signal (for example at least one frequency signal) is placed onto the carrier voltage to encode the representation of the at least one characteristic.

In some examples, the amplitude of at least one frequency of a signal received from the access network is modulated to encode the representation of the at least one characteristic. The amplitude of different predetermined frequencies may be used to indicate different characteristics.

For example, the absolute value of the amplitude at a particular frequency may be taken to indicate the value of a particular characteristic (where in some cases the value of the amplitude is modified to one of a set of predetermined, discrete, values). In other cases, the presence of a modified amplitude at a particular set of frequencies may be taken to indicate that the home network has a particular characteristic.

For example, the signal may be modulated to adjust an amplitude of a plurality of non-adjacent frequencies of the signal received from the access network to encode the representation of the at least one characteristic. While a change in a single frequency may naturally arise during line testing, e.g. due to noise or other artefacts, changes in amplitude at a plurality of frequencies provides a more distinctive indication of the representation of the at least one characteristic. Nonadjacent frequencies are for example frequencies that are separated in value by at least one other frequency. The non-adjacent frequencies may each be respective frequency ranges, rather than single frequencies, to simplify the encoding of the representation of the at least one characteristic.

Figures 9a and 9b are plots showing the modulation of a signal to encode a representation of a characteristic according to these examples. Figure 9a is a plot 900a of the amplitude of a signal versus frequency, prior to modulation of the signal to encode the representation of the at least one characteristic. Figure 9b is a plot 900b showing the amplitude of the signal versus frequency, after the signal has been modulated to encode the representation of the at least one characteristic. In Figure 9b, the amplitude of the signal has been reduced to zero at three specific frequencies: [1, [2 and f3, although in other cases the amplitude may be modified to a different value than zero. In some cases, the amplitude of a signal may be increased rather than decreased, since the DSL line 112 to the access network provides additional power that can be used to boost the amplitude of the signal to encode the representation of the characteristic. However, amplification typically requires more complex circuitry than circuitry for attenuating the amplitude of a signal, such as a frequency attenuator.

Modulating the signal to generate the modulated signal alters the signal returned to the access network. Line testing typically involves measuring the returned amplitude and phase of a signal for a spectrum of frequency bands. However, in some cases, the component is configured to modulate the signal so as to avoid unduly affecting the result of the line test, e.g. so that a majority of the signal returned is unmodulated or so that the unmodulated signal can be extracted from the modulated signal. As explained above, this may be referred to as watermarking of the signal to include a watermark corresponding to the amplitudes of the predetermined frequencies. In the example of Figure 9b, this is achieved by modulating the signal at a limited number of predetermined frequencies. This further simplifies the detection of the at least one characteristic from the modulated signal, e.g. by the line test equipment 106, by reducing the number of frequencies to be investigated for changes. In examples in which the component is a dongle, it can for example be determined that the dongle is not connected to the NTE if no changes (or if no predetermined amplitudes) are observed at the predetermined frequencies.

The unmodulated signal at the first, second and third frequencies ft, ft and /3 of Figure 9b can be obtained from the modulated signal for example by interpolation of the amplitude of the modulated signal at frequencies close in value to f, [2 and [3, respectively. In other cases, the signal can instead or in addition be modulated in a frequency range that is unimportant for the result of the line test. In such cases, interpolation of the modulated signal may be omitted.

In further examples, the signal can be modulated by delaying the signal at particular frequencies. However, interpretation of the phase of the modulated signal to identify the at least one characteristic encoded by modulation in this manner is more complex than detecting the at least one characteristic based on changes in amplitude of a signal. In addition, the circuitry to produce a controlled delay are typically more complex than those for modifying the power (and hence the amplitude) of a signal.

In some examples, the component is associated with an identifier. For example, the identifier may indicate a type of the component and/or where the component is a dongle, the identifier may uniquely identify the dongle (and may for example indicate a particular engineer or engineering team associated with the dongle). In such cases, the component may be configured to modulate the signal received from the access network to further encode a representation of the identifier. This provides further context for the line test result, for example allowing the identity of the component and/or the engineer or engineering team associated with the component to be identified. This for example allows the line test result to be modified further depending on the identifier. For example, if particular types of components, such as particular dongles, exhibit particular behaviour that needs to be compensated for in the line test result, the compensation can be applied in response to detecting, from the modulated signal, that the component is of a particular type.

A predetermined set of frequencies may be used for the modulation of the signal to encode the representation of the identifier. For example, a set of eight frequencies provides for the possibility of 28 or 256 unique identifiers to be encoded, assuming that each frequency is either unchanged or is attenuated to a particular level (i.e. assuming that each frequency takes one of two binary levels). Using more frequencies and/or different attenuation levels provides the capability to encode more identifiers. For example, using 16 frequencies and two different attenuation levels (in addition to an unchanged level) would allow the encoding of 318 or 256 unique identifiers.

The component may also or instead be configured to modulate the signal received from the access network to further encode a representation of a modulation scheme used to modulate the signal received from the access network. For example, a particular frequency or set of frequencies can be used to encode the modulation scheme (which may be referred to as an encoding scheme). The receiving system (e.g. the line test equipment 106) can determine, from the particular frequency or set of frequencies, which modulation scheme is being used for the remainder of the modulated signal, such as for at least one further frequency. This allows the evolution and interoperability of the modulation scheme. For example, a modulation scheme that initially modulates the signal to encode a representation of whether a component is one of a small number of component types can be adjusted to a new modulation scheme that can encode a representation of whether a component is one of a larger number of component types. It is to be appreciated that multiple modulation schemes are possible without specifically identifying the modulation scheme in the modulated signal. However, identifying the modulation signal in the modulated signal removes doubt that may otherwise arise, e.g. where the modulation for different modulation schemes is similar. Furthermore, identifying the modulation signal allows different modulation schemes to re-use the same frequencies and amplitude levels.

Figure 10 is a plot 1000 showing the encoding of a representation of a characteristic according to further examples. In the plot 1000 of Figure 10, an amplitude response for nine predetermined frequencies (labelled as fi to h) has been converted to a corresponding voltage level. A first set of frequencies 1002 (the first three predetermined frequencies, f1 to f3) are used to encode a representation of the modulation scheme in binary, i.e. by modulating each of the first set of frequencies to one of two amplitudes (corresponding to voltage levels of 0 and 1, respectively).

The first set of frequencies correspond to the binary number 010, which is 4 in decimal, indicating that the signal has been modulated using a fourth modulation scheme. A second set of frequencies 1004 (the latter six predetermined frequencies, LI to 19) are used to encode a representation of an identifier of the component used to perform the modulation in base three, i.e. by modulating each of the second set of frequencies to one of three amplitudes (corresponding to voltage levels of 0, 1 and 2, respectively). The second set of frequencies correspond to the base three number 021001, which is 190 in decimal, indicating that the component, which is e.g. a dongle, is associated with the identifier 190. The identifier 190 may uniquely indicate the component or may indicate the type of the component, e.g. that the component is a dongle with a particular configuration. It is to be appreciated that the voltage levels of 0, 1 and 2 are merely illustrative and need not correspond to voltage values of 0 volts (V), 1V and 2V, respectively.

Similarly, although the predetermined frequencies are shown as equally spaced along the frequency axis of the plot 1000, the predetermined frequencies need not be equally spaced in frequency value.

In some examples, the component is configured to monitor a plurality of characteristics, including at least one characteristic of the home network. In these examples, the component may modulate the signal such that the amplitude of each respective one of a plurality of non-adjacent frequencies indicates a state of a corresponding one of the plurality of characteristics. In this way, a vector can be obtained from the modulated amplitude of each frequency, such that the modulated amplitude of each frequency corresponds to an element of the vector (and indicates the state of a particular one of the characteristics). In such examples, a vector can also be obtained by the component itself, representative of the plurality of characteristics, which can be used to determine how the signal received from the access network is to be modulated to encode the plurality of characteristics. For example, the component may select a frequency corresponding to each element of the vector, and may determine that the amplitude of the signal at each frequency is to be adjusted by an amount which depends on the value of the element of the vector corresponding to that particular frequency. This is merely an example, though, which is straightforward to implement. However, other cases may use a different approach for encoding a plurality of characteristics. For example, each one of a plurality of characteristics may be encoded by modulating a plurality of frequencies. For example, four binary characteristics can be encoded using a combination of two frequencies with a single attenuation level (and an unattenuated level).

Alternatively, the same four binary characteristics can be encoded using four different attenuation levels of a single frequency. In general, X frequencies, each with Y attenuation levels, can be used to transmit XY bits of information, using binary encoding.

Components according to examples herein may include any suitable element or elements to modulate a signal to encode a representation of at least one characteristic according to examples.

For example, such components may include suitably-configured circuitry. As an example, one or more narrow band-stop or reject filters may be used to encode a representation of at least one characteristic, for example of a home network. As the skilled person will appreciate, a band-stop filter passes all frequencies with the exception of those within a specified stop band, which are greatly attenuated. Frequency filters that are capable of attenuating specific narrow frequencies are known as notch filters and can be used to attenuate particular frequencies by predetermined amounts, for example to obtain a frequency response in the form of a deep notch. A twin-T notch filter may also or instead be used. It is to be appreciated that a combination of filters can be cascaded (or otherwise used in succession) to reject or attenuate a plurality of predetermined frequencies.

Figure 11 is a schematic diagram of circuitry 1100 to modulate a signal to encode a representation of a characteristic according to examples. The circuitry 1100 may for example form part of the controllers 328, 428, 628 shown in Figures 3, 4 and 6. In Figure 11, the circuitry 1100 is arranged to receive an input signal (indicated in Figure 11 as 1.71), and to process the signal using a low-pass filter 1102 arranged in parallel with a high-pass filter 1104. By connecting the low-pass and high-pass filters 1102, 1104 in parallel, the input signal is applied to both filters 1102, 1104 simultaneously. The filtered signals obtained from the low-pass and high-pass filters 1102, 1104 are recombined and amplified using an amplifier 1106 to obtain a modulated signal (indicated in Figure 11 as VouT). The low-pass filter 1102 is arranged to pass signals with a frequency lower than a selected cut-off frequency, without attenuation, and to attenuate signals with frequencies higher than the cut-off frequency. Conversely, the high-pass filter 1104 is arranged to pass signals with a frequency higher than a selected cut-off frequency, without attenuation, and to attenuate signals with frequencies lower than the cut-off frequency. By selecting the cut-off frequency for the low-pass filter 1102 and the high-pass filter 1104, the circuitry 1100 can be configured to implement a narrow band reject filter, which either provides full rejection of a particular frequency (in which the modulated signal has an amplitude of zero for the particular frequency) or partial rejection of the particular frequency (in which the amplitude of the modulated signal is reduced but non-zero for the particular frequency), while passing remaining frequencies without altering their amplitudes.

Figures 12a and 12b are plots showing, respectively, full rejection and partial rejection of a signal of a particular frequency. Figure 12a shows plots 1200a, 1202a and 1204a of the gain versus frequency for a low-pass filter, a high-pass filter and a reject filter corresponding to a combination of a low-pass filter and a high-pass filter. In Figure 12a, the low-pass filter attenuates the signal for frequencies above a first cut-off frequency 1206a, until the gain reaches zero at a particular frequency. For the high-pass filter, the gain is zero below the particular frequency. However, the attenuation of the signal gradually decreases for frequencies above the particular frequency for the high-pass filter, until the signal is unattenuated at frequencies above a second cut-off frequency 1208a. By combining the low-pass filter and the high-pass filter, a reject filter can be obtained that achieves a gain of zero (or substantially zero) at the particular frequency, without substantially attenuating frequencies below or above the particular frequency (although the frequencies between the first and second cut-off frequencies 1206a, 1208a are attenuated to some degree, with gradually decreasing attenuation with decreasing distance from the particular frequency in frequency space). Figure 12b is similar to Figure 12a and also shows plots 1200b, 1202b and 1204b of the gain versus frequency for a low-pass filter, a high-pass filter and a reject filter corresponding to a combination of a low-pass filter and a high-pass filter. However, in Figure 12b, the first and second cut-off frequencies 1206b, 1208b are closer together, so that the reject filter corresponding to the combination of the low-pass and high-pass filters partially attenuate frequencies between the first and second cut-off frequencies 1206b, 1208b rather than fully attenuating those frequencies (as shown in Figure 12a).

Further examples are envisaged. For example, in Figure 3, the dongle 322 is connectable to the NTE 316 via a network interface for connection to a DSL line 120 to a home modem, and is configured to monitor whether the dongle 322 is connected to the NTE 316. However, in other examples, the dongle 322 may monitor at least one other characteristic of a home network than whether the dongle 322 is connected to the NTE 316, for example if the NTE 316 has a further interface for connection to the dongle 322 in addition to a network interface for connection to a DSL line to a home modem.

In the NTE 416 of Figure 4, the module 430 and controller 428 are shown as separate components. However, in other examples, the functionality of the module 430 and the controller 428 may be combined in a single component, which may be implemented in hardware or software or a combination of hardware and software.

In the example NTEs 416, 616 of Figures 4 and 6, the modules 430, 630 include simple circuitry to monitor a characteristic of the home network. However, in other examples, modules of a component for connection at a network termination point (such as an NTE or a dongle for connection to an NTE) may include more complex circuitry, software, or a mixture of hardware and software. For example, a module may be or include a suitably programmed microprocessor.

Various examples of characteristics of a home network that may be monitored are described above, but it is to be appreciated that other characteristics of the home network may be monitored.

For example, the component may also or instead be configured to monitor the power and/or noise level on the home network. In such cases, the component may monitor the power and/or noise level using a two-stage process in which the component monitors the power and/or noise level of a plug of a further DSL line to a home modem before the further DSL line is connected to a DSL line to an access network On other words, before the home network is connected to the access network), for example by suitable circuitry of the plug, using a hardware switch or by introducing an electronic delay in connecting the further DSL line to the DSL line. In other examples, the component is further configured to monitor at least one characteristic of the component itself, an NTE and/or a telecommunications network (which may or may not be characteristics of a home network), for example where such characteristic(s) are relevant to a line test or other diagnostic line test.

A component according to any of the examples above may be provided in a gateway device, which for example provides an entry point to a home network associated with the home modem. For example, the gateway device may include an NTE according to the examples herein, or may be connectable to a dongle according to the examples herein.

Examples herein may be realised, at least in part, by executable computer program code which may be embodied in an application program data. When such computer program code is loaded into the memory of a processor in a controller such as the controllers 328, 428, 628, it provides a computer program code structure which is capable of performing at least part of the methods in accordance with the above-described examples. In examples, such computer program code structure is capable of modulating a signal received from the access network to encode a representation of at least one characteristic of a home network. The computer program code structure may further be capable of monitoring the at least one characteristic of the home network and/or determining a suitable representation of the at least one characteristic of the home network for encoding.

In other examples, as explained above, any of the methods described herein may be implemented using suitably configured circuitry. For example, a controller such as the controllers 328, 428, 628 may be implemented in hardware (or in a combination of hardware and software), for example as a system-on-a-chip.

In general, it is noted herein that while the above describes examples, there are several variations and modifications which may be made to the described examples without departing from the scope of the appended claims. One skilled in the art will recognise modifications to the described examples.

Claims (25)

1. CLAIMS1. A component for connection at a network termination point demarcating an access network from a home network, the component configured to: monitor at least one characteristic of the home network; receive a signal from the access network; modulate the signal received from the access network to encode a representation of the at least one characteristic; and send the modulated signal to the access network.
2. 2. The component of claim 1, wherein the component is a dongle connectable to network termination equipment arranged at the network termination point.
3. 3. The component of claim 2, wherein the dongle is connectable to a network interface of the network termination equipment for connection to a digital subscriber line to a home modem.
4. 4. The component of claim 2 or claim 3, wherein the dongle is configured to monitor the at least one characteristic by monitoring whether the dongle is connected to the network termination equipment.
5. 5. The component of claim 1, wherein the component is network termination equipment.
6. 6. The component of claim 5, wherein the network termination equipment is further configured to monitor whether the network termination equipment is connected to at least one further electrical component and/or a power source.
7. 7. The component of any one of claims 1 to 6, wherein the component comprises: a module to monitor the at least one characteristic; and a controller to receive the signal, modulate the signal and send the modulated signal to the access network.
8. 8. The component of any one of claims 1 to 7, wherein the signal received from the access network is a line testing signal.
9. 9. The component of any one of claims 1 to 8, wherein modulating the signal received from the access network comprises modulating the signal received from the access network to include a watermark indicative of the at least one characteristic.
10. 10. The component of any one of claims 1 to 9, wherein the at least one characteristic comprises a characteristic indicative of whether the home network is connected to the access network at the network termination point.
11. 11. The component of any one of claims 1, 2 or 5 to 10, wherein the at least one characteristic comprises an electrical characteristic of the home network.
12. 12. The component of any one of claims 1 to 11, wherein the component is associated with an identifier, and the component is configured to modulate the signal received from the access network to further encode a representation of the identifier.
13. 13. The component of any one of claims 1 to 12, wherein the component is configured to modulate the signal received from the access network to further encode a representation of a modulation scheme used to modulate the signal received from the access network.
14. 14. The component of any one of claims 1 to 13, wherein the component is configured to modulate the signal using a carrier voltage.
15. 15. The component of any one of claims 1 to 14, wherein the modulated signal comprises at least one of: an amplitude modulated signal, a frequency modulated signal and a phase modulated signal.
16. 16. The component of claim 15, wherein the component is configured to modulate the signal to adjust an amplitude of a plurality of non-adjacent frequencies of the signal received from the access network to encode the representation of the at least one characteristic.
17. 17. The component of claim 16, wherein the component is configured to: monitor a plurality of characteristics of the home network; and modulate the signal such that the amplitude of each respective one of the plurality of non-adjacent frequencies indicates a state of a corresponding one of the plurality of characteristics.
18. 18. A gateway device comprising the component according to any one of claims 1 to 17.
19. 19. A method comprising: monitoring at least one characteristic of a home network, using a component connected at a network termination point demarcating an access network from the home network; receiving a signal from the access network; modulating the signal received from the access network to encode a representation of the at least one characteristic; and sending the modulated signal to the access network.
20. 20. The method of claim 19, wherein the component is a dongle connected to network termination equipment arranged at the network termination point.
21. 21. The method of claim 20, wherein the dongle is connected to a network interface of the network termination equipment for connection to a digital subscriber line to a home modem.
22. 22. The method of claim 19, wherein the component is network termination equipment.
23. 23. The method of any one of claims 19 to 22, wherein the signal received from the access network is a line testing signal.
24. 24. The method of any one of claims 19 to 23, wherein modulating the signal received from the access network comprises modulating the signal received from the access network to include a watermark indicative of the at least one characteristic.
25. 25. The method of any one of claims 19 to 24, wherein the at least one characteristic comprises a characteristic indicative of whether the home network is connected to the access network at the network termination point.