Patent Application
20060188266
The invention relates to networking and, more particularly, to powering an optical network terminal (ONT) in a passive optical network (PON).
A passive optical network (PON) can deliver voice, video and other data among multiple network nodes, using a common optical fiber link. Passive optical splitters and combiners enable multiple optical network terminals (ONT)s to share the optical fiber link. Each ONT terminates the optical fiber link for a residential or business subscriber, and is sometimes referred to as a subscriber premises node that delivers Fiber to the Premises (FTTP). An ONT is connected to one or more subscriber devices, such as televisions, set-top boxes, telephones, computers, or network appliances, which ultimately receive the voice, video and data delivered via the PON.
Generally, a PON includes a PON interface, sometimes referred to as an optical line terminator (OLT), having multiple, independent PON interface modules that serve multiple optical fiber links. A PON interface module provides an interface for transmission and reception of data packets over a particular optical fiber link that serves a group of ONTs. A PON is inherently a downstream-multicast medium. Each packet transmitted on an optical fiber link can be received by every ONT served by that link. ONTs identify selected packets or frames on the fiber link based on addressing information included within the packets or frames.
Network equipment in a cable or hybrid network may be connected to power provided by a central office, which commonly utilizes battery and generator back-up power to maintain a continuous power supply. In contrast, an ONT in an all-fiber optical network is ordinarily powered locally at the subscriber premises. For this reason, an ONT often includes a battery to provide back up power during a power outage to maintain critical services, such as voice service. Many FTTP service providers provide an uninterruptible power source (UPS) unit that may be mounted within or outside the service subscriber's premises. A UPS unit provides AC-to-DC voltage conversion from line power within the subscriber premises and includes a battery for backup power. In any case, different providers may want to implement different power options depending on several options, such as cost, reliability, and distance from a power source to the ONT.
In general, the invention is directed to an optical network terminal (ONT) for use in a passive optical network (PON) that includes power conversion circuitry to accommodate a variety of power source options. In particular, the power conversion circuitry converts a wide range of input direct current (DC) voltages to a DC supply voltage that powers ONT circuitry that supports communication of information via the PON.
An ONT is typically powered locally at the subscriber premises. Thus, circuitry is provided to convert standard alternating current (AC) line power to DC power. Some ONTs are generally designed to be powered by either a 12 volt direct current (VDC). Other ONTs are designed to be powered by a 48 VDC power supply. Accordingly, an ONT designed for 12 VDC operation will not operate with a 48 VDC power supply. Similarly, an ONT designed for 48 VDC operation will not operate with a 12 VDC power supply. Consequently, the power supply options offered to the fiber-to-the-premises (FTTP) service provider are generally limited by the design of the ONT.
In accordance with an embodiment of the invention, an ONT includes power conversion circuitry comprising a wide input voltage range power converter. The power conversion circuitry accommodates a wide input voltage range, e.g., 10.5-56.5 VDC, and converts the input voltage to an appropriate DC supply voltage to power the ONT. For example, the power conversion circuitry may convert the wide input voltage range to a supply voltage in a range of approximately 8 to 15 VDC for an ONT designed for a 12 VDC power supply. For example, the input power to the ONT circuitry, as generated by the power conversion circuitry, may be 12 VDC. In this manner, the invention enables an ONT to be used with a variety of different input power source options, including 12 VDC or 48 VDC power supplies.
In one embodiment, the invention provides an optical network termination (ONT) for use in a passive optical network (PON), the ONT comprising ONT circuitry to support communication of information via the PON, and power conversion circuitry to provide operating power to the ONT circuitry, wherein the power conversion circuitry is capable of converting a range of input voltages to a supply voltage that powers the ONT circuitry.
In another embodiment, the invention provides a method for powering an optical network termination (ONT) for use in a passive optical network (PON), the method comprising generating an input voltage, and converting the input voltage to a supply voltage to power circuitry within the ONT using power conversion circuitry that is capable of converting a range of input voltages to the supply voltage.
In another embodiment, the invention is directed to a computer-readable medium containing instructions. The instructions cause a programmable processor to
The invention may offer one or more advantages. Unlike ONTs designed to be powered by either a 12 VDC or a 48 VDC power supply, the described ONT includes power conversion circuitry that converts a wide range of DC input voltages to a DC supply voltage that powers the ONT. Consequently, rather than the FTTP service provider being limited by the design of the ONT, the FTTP service provider may select from a variety of different power source options, including 12 VDC or 48 VDC for a given ONT. In this manner, the FTTP service provider may select a power source depending on several factors, such as cost, complexity, reliability, and distance from a power source to the ONT. The described invention provides a flexible solution that may be configured to accommodate different ONT power supply options.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
In general, the invention is directed to an optical network terminal (ONT) for use in a passive optical network (PON) that includes power conversion circuitry to accommodate a variety of power source options. In particular, the power conversion circuitry converts a wide range of input direct current (DC) voltages to a DC supply voltage that powers ONT circuitry that supports communication of information via the PON.
In one example, an offline converter converts standard AC input line power to DC power. The offline converter may be located inside the premises of a FTTP subscriber. The wide input voltage range of the power conversion circuitry of the ONT enables the output voltage of the offline converter to be anywhere within a wide input voltage range of the ONT.
In another example, an uninterruptible power supply (UPS) unit provides AC-to-DC voltage conversion from line power within the subscriber premises and also includes a battery for backup power during a power outage. The UPS unit may be located within or outside the service subscriber's premises. Again, the wide input voltage range of the power conversion circuitry permits the use of any of a wide range of voltages produced by the UPS unit to power the ONT.
In a further example, an offline converter provides a supply voltage to the ONT via the power conversion circuitry and also provides DC power to a UPS unit. The UPS unit may utilize the DC power as a supply voltage for a battery charger. This configuration may be particularly desirable in the event a supplier desires battery backup outside the subscriber premises, but does not have access to AC line power outside the premises.
An OLT 12 may receive voice information, for example, from the public switched telephone network (PSTN) 14 via a switch facility 16. In addition, OLT 12 may be coupled to one or more Internet service providers (ISP's) 18 via the Internet and a router 20. As further shown in
ONTs 28 include hardware for receiving information from PON 10 via optical fiber links 11, and delivering the information to one or more connected subscriber devices (not shown). For example, each ONT 28 may serve as a PON access point for one or more computers, network appliances, televisions, set-top boxes, wireless devices, or the like, for video and data services. In addition, each ONT 28 may be connected to subscriber telephones for delivery of telephone services. Hence, ONT 28 may provide video to support television applications, data to support Internet access, and voice to support telephone services. ONT 28 includes appropriate conversion hardware to convert optical signals to electrical signals, and electrical signals to optical signals. OLT 12 may be located near or far from a group 26 of ONTs 28. In some existing networks, however, OLT 12 may reside in a central office (CO) situated within approximately ten miles from each ONT 28.
An ONT 28 may be located at any of a variety of locations, including residential or business sites, any of which may be referred to as subscriber premises. In addition, a single ONT 28 may operate on a shared basis to deliver information to two or more closely located residences or businesses via copper or additional optical fiber connections, either directly or via a network hub, router or switch. A group 26 of ONTs 28 may refer to nodes served by OLT 12 via a common optical fiber link 11. Each group 26 in
ONT 28 also may include hardware for transmitting information over PON 10. For example, an ONT 28 may transmit voice information over PSTN 14 via OLT 12 and switch facility 16 in the course of a telephone conversation. In addition, an ONT 28 may transmit data to a variety of nodes on the Internet via ISP 18, router 20 and OLT 12. Multiple ONTs 28 typically transmit upstream over a common optical fiber link 11 using time division multiplexing techniques, and rely on a downstream grant packet for assignment of upstream time slots to individual ONTs.
Each of ONTs 28 is powered locally at the subscriber premises. ONTs 28 are generally designed to be powered by either a 12 volt direct current (VDC) or 48 VDC power supply, depending on the design of the ONT. Accordingly, an ONT designed for 12 VDC operation will not operate with a 48 VDC power supply. Similarly, an ONT designed for 48 VDC operation will not operate with a 12 VDC power supply. Consequently, the power supply options offered to the FTTP service provider are generally limited by the design of the ONT.
In accordance with the invention, however, an ONT is equipped with power conversion circuitry that permits the ONT to be powered by 12 VDC or 48 VDC power supply. The power conversion circuitry accepts a wide input range voltage, e.g., from 10.5 VDC to 56.5 VDC, and converts the voltage to a supply voltage appropriate for the ONT, e.g., 8 to 15 VDC. For example, the power conversion circuitry may output a 12 VDC supply to the ONT processing circuitry. With the wide input voltage range, however, the FTTP service provider has the option of using 12 VDC, 48 VDC or other supply voltages as input voltages for application to the power conversion circuitry of the ONT.
Fiber-to-the-premises (FTTP) providers may desire to implement different power options depending on several factors, such as cost, complexity, reliability, and distance from a power source to the ONT. For example, some providers may elect to include battery power, while other providers may elect to eliminate battery power. Similarly, some providers may select implementations that require indoor or outdoor battery placement. Thus, it may be advantageous to provide a flexible solution that can be configured to accommodate different power options rather than provide a unique solution for each power option.
Each of ONTs 28 in PON 10 may include power conversion circuitry to convert a wide range of input direct current (DC) voltages to a DC supply voltage that powers the ONT hardware. By permitting a wide range of input DC voltages at the ONT, the FTTP service provider may select a variety of different power source options.
ONT 28 provides an interface between an optical fiber link 11 on a PON 10 and subscriber equipment 38 in a fiber-to-the-premises (FTTP) network. ONT 28 receives information in the form of voice, video and data from PON 10 over optical fiber link 11 from OLT 12. ONT 28 processes the information to deliver telephone, television and Internet services to subscriber equipment 38. Subscriber equipment 38 may include telephones, computers, televisions, set-top boxes, network applications, and the like. ONT 28 sends video signals to subscriber equipment 38 via coaxial cable, data via network cables such as Ethernet cable, and telephone signals over twisted pair wire. Voice, video and data are examples of information that may be received and transmitted by ONT 28.
As further shown in
ONT processing circuitry 34 handles reception and transmission of information in the form of frames, packets or other units of information over PON 10. For example, ONT processing circuitry 34 may be responsible for identifying information directed to and from particular subscriber equipment 38, and formatting the information to support respective telephone, video or data services within the subscriber premises and over PON 10. ONT processing circuitry 34 may also include data circuitry, video circuitry, and telephone circuitry to process incoming data for delivery of Internet, television and telephone services, respectively. ONT processing circuitry 34, data circuitry, video circuitry, and telephone circuitry may be implemented together or separately as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent logic circuitry.
ONT 28 is powered locally at the subscriber's premises with AC power supply 49. In particular, offline converter 48 converts power from AC power supply 49 to a DC input voltage for ONT 28. Power conversion circuitry 36 is designed to convert a wide range of DC input voltages to a DC supply voltage that powers ONT 28. For example, power conversion circuitry 36 may accommodate a wide input voltage range of approximately 10.5 to 56.5 VDC and output a supply voltage in a range of approximately 8 to 15 VDC, thereby providing suitable power for an ONT designed to operate with a 12 VDC power supply. Importantly, with the wide input voltage range accommodated by power conversion circuitry 36, the DC voltage out of offline converter 48 can be anywhere in the input voltage range of power conversion circuitry 36, providing the FTTP service provider with flexibility in the selection of power supply options.
ONT 28 may be designed to be powered by either a 12 VDC or a 48 VDC power supply. When ONT 28 is designed to be powered by a 12 VDC power supply, power conversion circuitry 36 converts the DC input voltage to a 12 VDC supply voltage. In this manner, offline converter 48 may provide a supply voltage of 12 VDC or 48 VDC, which is converted by power conversation circuitry 36 to 12 VDC to power ONT processing circuitry 34. Similarly, in some embodiments, when ONT 28 is designed to be powered by a 48 VDC power supply, power conversion circuitry 36 may be provided to convert the DC input voltage to a 48 VDC supply voltage.
Power conversion circuitry 36 may comprise a wide input voltage range integrated circuit (IC). One example of a suitable wide input voltage range IC is the LTC3703 IC commercially available from Linear Technology Corporation of Milpitas, Calif. However, power conversion circuitry 36 may be any suitable DC-to-DC converter that accommodates a wide input voltage range and outputs an appropriate supply voltage to power ONT 28.
Offline converter 48 may comprise an inexpensive “wall wart” or other suitable AC-to-DC converter that outputs a DC voltage within the wide input voltage range of power conversion circuitry 36. Generally, offline converter 48 may include a transformer to reduce the voltage of AC power supply 49 to a DC voltage within the input range of power conversion circuitry 36, a rectifier to perform the AC-to-DC conversion, and a capacitor to filter the output. In any case, offline converter 48 may be located within or outside the premises of a FTTP subscriber.
For example, offline converter 48 may be a wall wart that simply plugs into a standard AC outlet within the installation premises. The output voltage generated by offline converter 48 may be delivered to ONT 28 via a power cord. In some embodiments, a supply voltage of 48 VDC may be selected to permit longer power cords due to the lower voltage drop at ONT 28.
As further shown in
While ONT 28 is illustrated as including battery module 40 in
Again, ONT 28 includes power conversion circuitry 36 that converts a wide range of DC input voltages, such as approximately 10.5-56.5 VDC, to a DC supply voltage appropriate to power ONT 28. Power conversion circuitry 36 outputs the supply voltage, e.g., 12 VDC, to power optical receiver 30, optical transmitter 32, and ONT processing circuitry 34 to support communication of information over PON 10 and provide voice, video, and data services. In some embodiments, power conversion circuitry 36 may be configured to output a supply voltage of 48 VDC.
UPS unit 50 may be located within or outside the subscriber's premises. Because battery performance and reliability are adversely affected by temperature extremes, UPS unit 50 may be located within the subscriber's premises. However, when UPS unit 50 is mounted within the premises, the service provider must gain access to the premises in order to service battery 58, which is generally expensive and inconvenient to obtain. Physical access to UPS unit 50 is important because the inability to maintain battery 58 could result in battery failure during an extended power outage causing ONT 28 to lose power and fail to provide critical voice service. Consequently, in some cases, UPS unit 50 may also be mounted outside the subscriber's premises so that UPS unit may be easily accessed. In this case, UPS unit 50 is typically mounted to an exterior wall and may be mounted near or far from ONT 28.
Regardless of where UPS unit 50 is installed, conversion circuitry 52 converts standard power within the subscriber's premises from AC power supply 54 to a DC input voltage within the wide input voltage range (e.g., approximately 10.5 to 56.5 VDC) of power conversion circuitry 36. Again, AC power supply 54 may be obtained from AC line power within the subscriber premises. Battery charger 56 and UPS processing circuitry 59 are also powered by the voltage output by conversion circuitry 52.
Battery charger 56 charges battery 58 so that battery 58 may power ONT 28 over an extended period of time, such as approximately 8 hours, during a power outage. In addition, UPS processing circuitry 59 monitors the status of battery 58. For example, UPS processing circuitry 59 may transmit information associated with the status of battery 48 to ONT 28 or OLT 12. The information may indicate a failure in AC power supply 54, low life of battery 58, replace battery 58, or battery 58 is missing.
Importantly, ONT 28 permits the use of any voltage in the range accommodated by power conversion circuitry 36. Normally, a UPS unit provides either a 12 VDC or a 48 VDC. Consequently, power conversion circuitry 36 permits the use of any voltage in the range produced by a normal UPS unit to power ONT 28. Accordingly, ONT 28 may be used with a UPS unit 50 having a 12 VDC output, a 48 VDC output, or any other output within the wide input voltage range of power conversion circuitry 36. Power conversion circuitry 36 converts any input voltage in the wide input voltage range to a supply voltage appropriate to power ONT 28, such as 12 VDC. By including circuitry to provide backup power in UPS unit, only the providers that choose to include a battery are required to pay for additional circuitry.
Similar to the embodiments illustrated in
As in the example of
Offline converter 48 provides DC power to a battery module in the form of UPS unit 60. UPS unit 60 may include battery charger 56 and one or more batteries that function as a UPS unit. UPS unit 60 can be located remotely anywhere between the offline converter 48 and ONT 28. For example, UPS unit 60 may be located within or outside the installation premises and is powered by the DC voltage output by offline converter 48.
Because offline converter 48 converts the power provided by AC power supply 49 into a DC voltage, UPS unit 60 does not include AC-to-DC conversion circuitry. Rather, UPS unit 60 includes battery charger 56, battery 58, and UPS processing circuitry 59. Again, battery 58 provides backup power to ONT 28 during a power outage, battery charger charges battery 58, and UPS processing circuitry monitors the status of battery 58.
While UPS unit 60 may be mounted within or outside the subscriber's premises, the embodiment illustrated in
By accommodating a wide voltage input range at ONT 28, the FTTP service provider may select different power options depending on several factors such as cost, complexity, reliability, and distance from the ONT. Thus, ONT 28 provides a flexible solution for various power options. ONT 28 with power conversion circuitry 36 may be powered by various power options unlike ONTs that may be powered by only one particular power option.
Various embodiments of the invention have been described. However, one skilled in the art will appreciate that various modifications or additions may be made to the described embodiments without departing from the scope of the claimed inventions.
This application claims the benefit of U.S. provisional application No. 60/639,860, filed Dec. 28, 2004, the entire content of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60639860 | Dec 2004 | US |
