WO2019104373A1

WO2019104373A1 - A system for disabling pots reversion

Info

Publication number: WO2019104373A1
Application number: PCT/AU2018/051111
Authority: WO
Inventors: Colin GARLAND; Jalal ZIAOLHAGH; Charlie WARREN
Original assignee: Netcomm Wireless Limited
Priority date: 2017-11-28
Filing date: 2018-10-12
Publication date: 2019-06-06
Also published as: AU2018377057A1

Abstract

A system (100) for disabling Plain Old Telephone Service (POTS) reversion by a network provider comprising: a Distribution Point Unit (DPU) (10) wherein a Network Management System (NMS) message is sent by the network provider via the DPU 10 to a NCD 50, and in response to a predetermined event, the NCD (50) transmits the NMS message to configure a LSU (12) to operate in DSL mode and prevent subsequent reversion of the LSU to POTS pass-through mode for the first user.

Description

A system for disabling POTS reversion

FIELD OF THE INVENTION

[0001 ] The present invention relates to a system for disabling Plain Old Telephone Service (POTS) reversion for a Distribution Point Unit (DPU) used in data communication networks that employ both fibre optic and copper lines.

BACKGROUND TO THE INVENTION

[0002] FTTdp (Fiber to the Distribution Point) brings the fibre optic connection point of a fibre-optic telecommunications network closer to the home of the customer in comparison to Fiber to the Node (FTTN) broadband architectures. Located at the home of the customer is Customer Premises Equipment (CPE) which includes, as a minimum a modem, optionally a telephone and POTS wiring. In this broadband network architecture the last few meters (e.g. up to 200 metres) of the broadband connection provided through a passive optical network (PON) are provided by the existing twisted pair cabling or copper wire (copper lead-ins) to the home that is currently used for legacy technologies such as POTS and xDSL. In a gigabit passive optical network (GPON) networking protocol can provide 2.4 Gbps download speed for up to 20 kilometres and the NG-PON2 networking protocol can provide 40 Gbps download speed for up to 60 kilometres. To match the increased speed capabilities that come with bringing the fiber nodes closer to the home, the access technology on the copper wire is improving to provide higher speeds. Such access technology on the copper wire can include G.fast (1 Gbps download speed for up to 100 metres) and its successor XG.FAST (3.5 Gbps download speed for up to 100 metres). The signal frequency of G.fast starts at 106MHz (it can be doubled to 212MHz) and XG.fast uses between 350MHz and 500MHz. This copper wire access technology provides more bandwidth for transferring data over copper at higher speeds. To address the problem of signal attenuation at higher frequencies, G.fast and XG.FAST both use vectoring to generate an anti-phase signal to cancel the majority of interference.

[0003] A distribution point unit (DPU) is typically a small piece of

telecommunications equipment that is used in broadband network architecture such as FTTdp. In use, the DPU is placed in an existing underground

communications pit or secured outdoors to a wall or power pole, depending on suitability and other factors. In one example, the DPU takes in one fibre-optic cable for its upstream connection to the optical network and includes an optical- electrical signal converter that converts an incoming optical signal into electrical signals through which network traffic to four or more downstream copper wire or coaxial cable connections that are connected to ports on the DPU. The downstream connections connect to a device for connecting to a network such as a Network Connection Device (NCD), for example, the modem at the customer (user) premises. A Reverse Power Unit (RPU) provides a power feed to the DPU via the copper wire.

[0004] The placement of the DPU in the external environment requires it to be environmentally hardened to withstand harsh and varied weather and

environmental conditions for many years. The DPU must be operable in very challenging circumstances such as immersion in water or mud, and long exposure to direct sunlight in summer. The DPU must operate in extreme temperatures since temperatures can range from -23°C to 51 °C in certain countries.

[0005] Other criteria for DPUs include that they are required to be tamper- resistant, capable of sending a notification if they have been tampered with, be inexpensive to manufacture and install, and the connection to the cables of the DPU should be accessible outside of the DPU housing to enable a technician of a network provider to connect them with copper lead-ins and the fibre-optic cable without opening the DPU housing. [0006] A DPU is installed in series with an existing phone line to allow the existing telephone service (POTS) to remain in use. Some DPUs include a line switching unit (LSU). The LSU enables the DPU to disconnect the existing POTS service and connect to the digital subscription line (DSL) service which is provided by the DPU via fibre optic cable. The LSU is initially in POTS reversion mode when the DPU is installed. When the LSU is in POTS reversion mode, the LSU leaves the POTS line connected unless it receives signalling and power from the Reverse Power Feed Unit (RPF/RPU) located at the customer’s premises. One reason for providing POTS reversion by a DPU is to address a circumstance where an operator wants to install the DPU equipment prior to migrating customer services. The operator can install DPUs in POTS pass-through mode with negligible disruption to the existing customer voice and data services. At a later time, the operator can activate the DPU services and install an RPU or NCD via a self-install or professional installation process. The DPU can automatically detect the type of user (only POTS user or Internet user) by detecting whether there is power and RPU signalling from the RPF/RPU along the twisted pair cable from the customer’s premises to the DPU. The detection of RPU signalling means the customer has an NCD or RPU installed in their premises.

[0007] If the DPU detects a reverse power feed, the LSU disconnects the POTS service and switches to the DSL service (VDSL, G.Fast, XG.Fast or any other type of copper transmission technology) provided by the DPU, with network traffic routed via fibre optic cable. When the DPU is not receiving a reverse power feed, the LSU reverts to POTS pass-through mode by disconnecting the DSL service and reconnecting the POTS service from the exchange. The DPU startup sequence includes a switching step which makes it switch to POTS mode or DSL mode as required.

SUMMARY OF THE INVENTION

[0008] The inventive concept arises from a recognition that servicing an installed Distribution Point Unit (DPU) after installation on-site is expensive and time-consuming, and that improving the start-up time of the DPU after a power outage is beneficial to customers serviced by the DPU.

[0009] The present invention, in one aspect, comprises a system for disabling Plain Old Telephone Service (POTS) reversion by a network provider. The system comprises a DPU. The DPU includes a line switching unit (LSU) operable between a POTS pass-through mode when there is no signalling or power from a Network Connection Device (NCD) of a user, and a DSL mode in response to receiving a reverse power feed from the NCD of the user. The DPU also includes a processing unit for routing traffic between an upstream fibre network and a downstream DSL network. In a first example, a Network Management System (NMS) message is sent by the network provider via the DPU to the NCD for storage. In a second example, the NMS message is received, decoded and immediately retransmitted without being stored in a non-volatile memory of the NCD or modem.

[0010] In the first example, in response to a predetermined event, as noted below, the NCD processes and decodes the NMS message then transmits a message, using a serial or similar protocol, to the RPU instructing it to reconfigure the LSU either immediately or after the next RPU power cycle. The RPU reconfigures the LSU by sending a message, using an RPU signalling protocol, which instructs the LSU to operate in DSL mode and prevent subsequent reversion of the LSU to POTS pass-through mode for the user. After the POTS reversion locking instruction is received at the LSU, the startup sequence includes a step which switches the LSU to DSL mode, rather than the step of switching to POTS mode presently used. In the second example, the

predetermined event is the receipt of the NMS message and the NCD processes and decodes the NMS message then transmits a message to the LSU.

[0011 ] The predetermined event may be a subsequent power cycle of the NCD or RPU. [0012] Advantageously, the NCD will have an architecture comprising both a modem and a reverse power feed unit (RPF/RPU).

[0013] Another NMS message of a second type may be sent by the network provider via the DPU to the modem or NCD for processing, decoding and transmission to configure the LSU to operate in POTS pass-through mode.

[0014] Other advantages and features according to the invention will become apparent to those of ordinary skill upon reading the following description of preferred, non-limiting embodiments of the invention described with reference to the accompanying figures in which like reference numbers denote like elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig. 1 is a block diagram of a system for disabling Plain Old Telephone Service (POTS) reversion in accordance with a preferred embodiment of the present invention;

[0016] Fig. 2 is a flow chart of a start-up process when the LSU is actively switching between a POTS service and DSL service;

[0017] Fig. 3 is a flow chart of a start-up process when the LSU is locked into DSL mode; that is when POTS reversion is locked and POTS mode is no longer available, in accordance with a preferred embodiment of the present invention; and

[0018] Fig. 4 is a perspective view of a DPU depicted in Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION [0019] A distribution point unit (DPU) is illustrated in Fig. 4 and shown generally at reference numeral 10. The DPU 10 comprises a casing 31 including a side wall 20. The casing 31 is also referred to as an enclosure or housing. The side wall 20 is where cables 61 , 65 are securely attached and sealed. The side wall 20 comprises at least one port 30 for entry of at least one cable 61 , 65 carrying optical and electrical signals. The DPU 10 also comprises an electronic board (e.g. a PCB) comprising at least an electronic component for processing the optical and/or electrical signals. The electronic board is housed within the casing 31 which protects the electronic board from damage and being

contaminated by water and dust.

[0020] The DPU 10 is a telecommunications device which routes traffic from an upstream network (such as a fibre optic network e.g. GPON) connected via the optical fibre cable tail 65 to one or more downstream customer end points via the copper lead in cable tails 61. The DPU 10 enables reuse of an existing telecommunications line 60, 62 such as a copper twisted pair to make the last stretch of the telecommunications connection into the customer’s premises. The DPU 10 provides a Digital Subscriber Line (DSL) service via the existing twisted pair telephone line 62. Other network and line technologies can be used. One of the advantages of the fibre to the distribution point (or fibre to the curb) architecture is that the DPU 10 can be installed prior to migrating the customer onto new DSL service. This is possible because the DPU 10 is connected at a location on the copper line 60, 62 between the POTS exchange and the customers’ premises.

[0021 ] Referring to Fig. 1 , a system 100 for disabling Plain Old T elephone Service (POTS) reversion by a network provider is provided. The system 100 comprises the DPU 10, the modem 51 and the RPU 52. In the preferred embodiment, the modem 51 and RPU 52 may be advantageously incorporated into a single device for connecting to a network referred to as a Network

Connection Device (NCD) 50. The DPU 10 includes a line switching unit (LSU) 12 operable between a POTS pass-through mode when there is no signalling or power from the RPU 52 or the NCD 50 of a user, and a DSL mode in response to receiving a reverse power feed from the NCD 50 of the customer. The DPU 10 also includes a processing unit 1 1 for routing traffic between an upstream fibre network 65 and a downstream DSL network 61. In one example, a Network Management System (NMS) message is sent by the network provider via internet protocol (IP) as DSL traffic which passes transparently through the DPU 10 to the modem 51 , which may be incorporated in an NCD 50, for processing and storage if required. In response to a predetermined event, the modem 51 transmits the NMS message to configure the LSU 12 to operate in DSL mode and prevent subsequent reversion of the LSU 12 to POTS pass-through mode for the user. In another example, the NMS message is not stored and therefore the

predetermined event is the receipt of the NMS message and the NCD 50 processes and decodes the NMS message then transmits an RPU message to the LSU 12.

[0022] The DPU 10 contains network processing hardware 1 1 for routing traffic between the upstream fibre network 65 and the downstream DSL network 61. The DPU 10 is powered in the "reverse" direction via the customer line 62 by a reverse power feeding circuitry/reverse power unit (RPF/RPU) 52 which may be incorporated in the NCD 50 located at the customer’s premises. The DSL service provided by the DPU 10 connects via customer line 62 to a modem 51 of the NCD 50.

[0023] Line Switching Unit (LSU)

[0024] Referring to Figs. 1 and 4, each copper line tail 61 on the DPU 10 contains two copper pairs both of which connect to the line switching unit (LSU)

12 of the DPU 10. When the DPU 10 is installed, the existing POTS line 60, 62 (usually in one line) is usually cut, and the pieces are connected to the two copper pairs of the copper line tail 61 of the DPU 10. The LSU 12 has a default mode of POTS pass-through mode and the processing unit 1 1 of the DPU 10 is powered off. If a POTS voltage is detected and present, the LSU 12 draws a small amount of power to charge the switching circuitry ready for activation of the DSL service. Therefore the POTS line 60 coming from the POTS exchange is connected to one copper pair copper line tail 61 input into the LSU 12, and then the customer line 62 to the customers’ premises is connected to the other copper pair of the copper line tail 61 output from the LSU 12.

[0025] The LSU 12 has two modes it can switch between: (1 ) POTS pass through mode and (2) DSL mode. POTS pass-through mode is where the POTS service is electrically connected to the customer line 62 into the customer premises and the DSL equipment of the DPU 10 is idle. DSL mode is where the POTS line 60 from the POTS exchange is disconnected and the DSL equipment of the DPU 10 is connected instead. The LSU 12 has separate switching capabilities for each line 61 , so each customer line 62 can be activated at different times. There may be four, eight or more customer lines 62 connected to a single DPU 10.

[0026] Although the LSU 12 may be a physically separated unit in the DPU 10, in other examples, the LSU 12 may be a logical unit rather than a physical unit.

[0027] Reverse power feeding circuitrv/reverse power unit (RPF/RPU)

[0028] Most network providers installing DPUs 10 prefer the LSU 12 to start in POTS pass-through mode at the time of installation. Even if the DPU 10 is providing a DSL service, a network provider prefers the DPU 10 to automatically revert to POTS pass-through mode if the DPU 10 loses power, for example, so that the customer can make an emergency telephone call. This configuration is referred to as POTS reversion and it allows the original POTS service to remain available with the least amount of interruption.

[0029] When a DSL service on the DPU 10 is to be used, the RPF/RPU 52 needs to be connected inside the customer’s premises to supply power to the DPU 10 via customer line 62. The RPF/RPU 52 can be a separate unit or part of a combined unit such as an NCD 50 containing the RPF/RPU 52 and DSL modem 51. The RPU 52 or NCD 50 can be self-installed by the customer or a technician of the network provider. The RPF/RPU 52 signals the LSU 12 (for example, by pulsing), instructing it to switch to DSL mode. The RPF/RPU 52 detects when the LSU 12 has switched modes to DSL mode and supplies power to the DPU 10. At this moment, the networking hardware such as the processing unit 11 in the DPU 10 draws power (step 207) from the RPF/RPU 52 in the customer’s premises. The DPU 10 can draw power from one or multiple RPUs 52.

[0030] Referring to Fig. 2, when the DPU 10 is first installed, there are usually no RPUs 52 active on its customer lines 62 and POTS reversion is the default mode and is active 200 for the DPU 10. The DPU 10 starts up (step 201 ), switches to POTS mode (step 203) and the DPU 10 stays in a low power mode/state (step 202). The LSU detects (step 204) whether it has received an RPU message generated due to an RPU 52 being installed or power cycled. The RPU message is sent by the RPU 52 as a signal via the customer line 62 to the LSU 12. If no RPU message has been received by the LSU 12, the LSU 12 remains (step 208) in POTS reversion mode. If the POTS service is not active, there is no power to the DPU 10 at all, and the LSU 12 will not begin charging until a voltage is applied to one of the POTS line 60 or customer line 62

originating from the exchange or the customers’ premises, respectively. If an RPU message is received, the LSU 12 switches (step 205) to DSL mode.

[0031 ] When the RPU 52 is connected within a customer’s premises, it tests (step 206) the customer line 62. If there is a fault, this is indicated to the customer via flashing LEDs or some other alert method from the RPU 52 and the DPU 10 returns to low power mode. If there is no line fault, the DPU 10 is powered up (step 207). This process can take up to 2 minutes. If no POTS service is on the customer line 62, the RPU 52 provides a current-limited supply to the LSU 12 while also intermittently signalling the LSU 12 to switch to the DSL mode. This process of charging the LSU 12 and switching is called a dry line migration and can take up to 8 minutes. For safety reasons, the RPU 52 can deal with other possible situations, such as an off-hook telephone on the customer line 62. [0032] Remotely disabling POTS reversion

[0033] After FTTdp has been substantially implemented in a country, city or town and there has been extensive deployment of DPUs 10, the POTS exchange may be decommissioned and the operator can no longer guarantee that the POTS line 60 from the DPU 10 leading to the former exchange is in a useable state without faults or shorts on the line 60. If this occurs, the LSU 12 does not need to switch back to a non-existent POTS system. After the POTS exchange is decommissioned, an advantage in disabling POTS reversion is that it will mitigate the risk that after the POTS exchange is decommissioned the copper

infrastructure could be left in a fault condition and therefore cause unintended harmful consequences to the DPUs 10. If the DPU 10 loses power and the LSU 12 switches back to POTS pass-through mode as per existing practice, a line fault or shorted line would prevent the RPU 52 from powering up the LSU 12 and instructing it to switch back into DSL mode. This would then mean that the network provider would have to service the DPU 10 and rectify the line fault, for example, by cutting and terminating the line which previously ran to the POTS exchange.

[0034] A method for advantageously disabling POTS reversion for a DPU 10 is provided using commands sent through the IP network. POTS reversion for each DPU 10 can be permanently and irreversibly disabled, or it can be semi permanent where previously disabled POTS reversion can be re-enabled later. A network provider is provided with a convenient option they may use in the future after DPUs have been installed to send a message that ultimately reaches the LSU 12 of the DPU 10 instructing it to permanently remain in DSL mode after a power outage i.e. disabling POTS reversion. The LSU 12 would not revert to POTS pass-through mode under any circumstances. The change of behaviour in the LSU 12 applies to all lines 61 and not only the line on which the instruction was transmitted.

[0035] In a preferred embodiment, the network provider uses a Network Management System (NMS) or Device Management System to send an instruction to the modem 51 which, as noted above, can advantageously be incorporated in an NCD 50. The RPF/RPU 52 is connected to the modem 51 , or in the case of an NCD 50, part of the same device with the modem 51. The modem 50 is under management by the network provider using a type of device management system or network management system, which sends messages using a management protocol. The message is sent as network/device

management traffic, using internet protocols of the IP network. The instruction is sent as a configuration parameter by the NMS using a remote management protocol similar to TR-069, SNMP and NETCONF. For example, the configuration parameter may be a single bit change (0 or 1 ) in the NMS message. The DPU 10 does not require any modification to enable pass through of the instruction sent from the NMS because the instruction is sent as internet protocol (IP) network traffic.

[0036] The NMS message sent by the network provider passes through the DPU 10 and is not read or decoded by the DPU 10. The modem 51 of the NCD

50 of a customer receives the NMS message, decodes the message to determine the instruction from the configuration parameter, and passes the instruction to the RPF/RPU 52. In one example, the RPF/RPU 52 stores and records the

instruction in a non-volatile memory for later use. In another example, the

RPF/RPU 52 executes and transmits an RPF message immediately to the LSU 12. The RPF/RPU 52 transmits an RPF message to the LSU 12 using its signalling protocol. The transmission of the configuration parameter to the modem

51 of the NCD 50 to be processed, decoded and transmitted to the LSU 12 allows the DPU 10 to be remotely re-configurable.

[0037] In a preferred embodiment, the RPF/RPU 52 stores the instruction until it next power cycles, and then it sends the instruction to the LSU 12 via customer line 62. The LSU 12 detects and interprets the instruction to deactivate POTS reversion mode. The LSU 12 subsequently remains in DSL mode and does not revert to POTS under any line condition. [0038] Referring to Fig. 3, POTS reversion has been disabled and is locked 300 for the DPU 10 because the LSU 12 has previously received the RPU message instructing the DPU to deactivate the POTS reversion functionality and remain in DSL mode permanently if it loses power. When there is a power outage causing the DPU 10 to lose power, or if the RPF/RPU 52 is connected to a new DPU which is unpowered, the DPU 10 starts up (step 301 ), switches to DSL mode (step 302 and DPU 10 stays in a low power mode/state (step 303). If the LSU 12 detects an RPU message from the RPF/RPU 52, the RPU 52 is connected and tests (step 304) the customer line 62. The step 302 for switching to DSL modem is required so that the LSU 12 remains in a known state after power cycling. The LSU 12 may be unable to determine what its current state is and therefore by forcing itself into a known state (e.g. DSL mode) during the startup process ensures that current state is known. If there is a fault, this is indicated to the customer via flashing LEDs or some other alert method from the RPU 52, and the DPU 10 returns to low power mode. If there is no line fault, the DPU 10 is powered up (step 305).

[0039] If the POTS reversion lock needs to be removed to allow POTS pass through functionality to be restored, the LSU 12 can be signalled again by sending another NMS message to the modem 51 to re-activate POTS reversion but the message may only be transmitted on start-up of the reverse power feed connection to the DPU 10 following a power cycle of the RPF/RPU 52. This NMS message can contain an extra bit different to the NMS message for disabling POTS reversion. In another example, the NMS message can contain the same bit as the previous NMS message since the LSU 12 may interpret the sequence of NMS messages being received to determine whether to implement POTS reversion lock.

[0040] A first advantage for locking the LSU 12 into DSL mode by disabling POTS reversion is that physically servicing the DPU 10 after installation is expensive. When the POTS exchange is decommissioned or services are deactivated, it is less expensive for the network provider to remotely send an NMS message (or NMS messages in bulk to multiple DPUs) which causes the LSU 12 to lock the DPU 10 into DSL mode so that it will not automatically revert to POTS pass-through mode.

[0041 ] A second advantage for locking the LSU 12 into DSL mode is that it significantly improves the start-up time for the DPU 10. If a power outage does occur, all the lines of the DPU 10 would revert back to POTS pass-through mode. At this moment, if the POTS exchange has been decommissioned there would be no POTS voltage to keep the LSU 12 charged and ready to switch over. This means when power is restored the RPF/RPU 52 would have to charge up the LSU 12 and switch as a dry line migration. This process can take up to 8 minutes. If the LSU 12 is configured to stay in DSL mode then the relay can be left in the correct position for DSL mode and the LSU 12 can start-up and power the DPU 10 within 1 minute as there is no charging or switching signalling to be performed. This results in a 200% to 800% performance increase in reducing start-up time.

[0042] Unless specified to the contrary, any and all components herein described are understood to be capable of being manufactured and, as such, may be manufactured together or separately.

[0043] Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest reasonable manner consistent with the context. In particular, the terms“comprises” and“comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

[0044] The subject headings used in the detailed description are included only for the ease of reference of the reader and should not be used to limit the subject matter found throughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations. [0045] Although the technology herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms“first” and“second” may be used, unless otherwise specified, they are not intended to indicate any order but may be utilised to distinguish between distinct elements.

[0046] It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the spirit and scope of the technology.

Claims

CLAIMS:

1. A system for disabling Plain Old Telephone Service (POTS) reversion by a network provider comprising:

a Distribution Point Unit (DPU) including:

a line switching unit (LSU) operable between a POTS pass-through mode when there is no signalling or power from a Network Connection Device (NCD) of a first user, and a DSL mode in response to receiving a reverse power feed from the NCD of the first user; and

a processing unit for routing traffic between an upstream fibre network and a downstream DSL network;

wherein a Network Management System (NMS) message is sent by the network provider via the DPU to the NCD, and in response to a predetermined event, the NCD transmits the NMS message to configure the LSU to operate in DSL mode and prevent subsequent reversion of the LSU to POTS pass-through mode for the first user.

2. The system according to claim 1 , wherein the predetermined event is a subsequent power cycle of the NCD.

3. The system according to claim 1 , wherein the NCD comprises a modem and reverse power feed unit (RPF/RPU).

4. The system according to claim 1 , wherein another NMS message of a second type is sent by the network provider via the DPU to the NCD for retransmission to configure the LSU to operate in POTS pass-through mode for the first user.

5. The system according to claim 3, wherein the NMS message is stored in a non-volatile memory of the NCD or modem.

6. The system according to claim 1 , wherein the predetermined event is receipt of the NMS message.