Abstract:
An optical network terminal (ONT) is powered via a remote power supply. The remote power supply is connected to a standard customer premises electrical power outlet, providing a power source for power at a first format (e.g., 110 VAC). The remote power supply performs a power transformation to convert the power in the first power format to a second format (e.g., 48 VDC). This allows the powering of the ONT from farther distances, and thus allows for the easier installation of ONTs at customer premises which may not have optimally placed power outlets. A battery backup may also be used (either in parallel or serially), in order to provide availability of communications signals during a public power outage. When the battery backup used serially with the remote power supply, additional distance between the power outlet and the ONT may be accommodated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This claims the benefit of prior co-pending U.S. provisional patent application Ser. No. 60/576,675, filed Jun. 3, 2004. 
    
    
     BACKGROUND 
     As part of a deployment of fiber to the premises (FTTP) networking to individual customer premises (for example, residential homes), an “optical network terminal” unit (ONT) needs to be installed at each customer premises. The ONT provides the interface between the customer premises communications equipment (telephone, data, video STB and TVs) and the fiber network. Current ONTs, particularly those used with FTTP networks that are passive optical networks (PONs), require their own power supplies, as the fiber network does not supply power to the customer premises. Current implementations of the ONT may include a power connection to standard customer premises power supply (e.g., 110 VAC) via a cable configured to be usable with standard power outlets. 
     One concern raised by ONTs is that a power outage at the customer premises may prevent access to telephone communications over the fiber network via the ONT. In order to address these concerns, current ONT implementations specify the use of a uninterruptible power supply (UPS)—such as a backup battery—to power the ONT, such that the UPS provides power to the ONT upon power failure. The current specification for ONT UPSs requires that the UPS provide enough power to allow the ONT to provide up to eight hours of telephone services to the customer. The UPS is typically deployed with the ONT, such that the ONT draws its power from the UPS or from the customer premises power supply. The UPS is typically deployed separately from the ONT, allowing it to be independently maintained and placed in environmentally friendly locations (e.g., in the interior of the customer premises). This requires power supply cabling between the ONT and the UPS. 
     Power supply cabling is governed by both physical laws (e.g., Ohm&#39;s law) and legal regulations. For example, the cabling between the ONT and the customer premises power outlet is typically eight feet in length or shorter in order to comply with electrical and building codes. The cabling between the UPS and the ONT is ideally less than 50 feet in length in order to reduce resistive losses. Additionally, the location of the customer premises power source (e.g., a power outlet) must comply with applicable building codes regarding power wiring, which may limit outlet placement. With these restrictions, the installation costs associated with installing an ONT can be significant, as additional electrical installations may be required to accommodate the ONT. 
     Investigating various building constructions and home layouts, it was determined that at least 10% of a sampling of homes would not have a power outlet within the placement constraints of existing power supply cabling. In those cases, an electrical contractor would need to be dispatched and required to install an electrical outlet in an area that was acceptable to the customer and within the design constraints of the UPS/ONT, at a significant expense and delay. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an implementation of an ONT powering system, according to the present invention. 
         FIG. 2  illustrates an exemplary ONT unit, according to the present invention. 
         FIG. 3  illustrates a second implementation of an ONT powering system, according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     To provide additional range for placement of an ONT unit relative to one or more power sources, an additional power supply is introduced between the ONT and a customer premises power source. This additional power supply may convert standard premises power forms (e.g., 110 VAC) to another power form (e.g., 48 VDC power), which allows for sufficient powering of the ONT unit from greater remote distances. Furthermore, as the power requirements are reduced, the cabling between the additional power supply and the ONT unit can use lower gauge wiring, such as typical 24 gauge Cat 3 or Cat 5e cabling, which can be more easily installed (or may already be installed). This combination provides greater installation versatility and reduces the need for additional electrical installations. For example, efficiencies can be realized when the Cat 5e cables placed by the technician for data communications could also be utilized to carry the power to the ONT. A spare pair of existing Cat 3 telephone cable could also be utilized as an alternative. As further described below, the additional power supply can alternatively be connected to a battery backup system which is connected to the ONT unit. This allows even further distances between the customer premises power outlet and the ONT to be accommodated. 
       FIG. 1  illustrates a deployment according to a first preferred embodiment. Customer premises  1  may include various customer premises communications equipment—a telephone  2 , a computing device  3 , a television  4  and a set-top box  5 . Customer premises  1  may also include a centralized structured wiring cabinet (CSWC)  6  to which cabling to customer premises communications equipment may be terminated. As shown in  FIG. 1 , the CSWC  6  may be sited inside customer premises  1 , and may include facilities to provide signals over the terminated cabling (for example, splitters, switches, routers, etc.). 
     Also shown in  FIG. 1  is an ONT unit  7  which, as shown, may be located exterior to customer premises  1  (e.g., mounted to an exterior wall of customer premises  1 ). ONT unit  7  may be connected to a fiber cable  8  that provides connection to the FTTP network. The ONT unit  7  may be connected to the CSWC  6  via various cables  9 —for example, Cat 5e cabling for voice and data communications, and RG6 coaxial cabling for video signals. Cables  9  may be deployed through a conduit  14  that allows cables  9  to pass from the interior of customer premises  1  to the exterior, thus allowing connection to ONT unit  7 . ONT unit  7  may be grounded via a grounding connection  15 . ONT unit  7  may be powered via cable  13  or cable  21 , as further described below. 
       FIG. 2  illustrates an example of an ONT unit  7 . Exemplary ONT unit  7  includes a fiber terminal  17  which allows fiber cable  8  to communicate with ONT unit  7 . ONT unit  7  also includes one or more grounding terminals  18  to electrically connect the ONT to grounding connection  15 . ONT unit  7  also includes one or more power terminals  19  to electrically connect the ONT unit  7  to cable  13  and/or cable  21  for power sourcing. ONT unit  7  also includes communications terminals  20  to connect ONT unit  7  to cables  9  to provide/receive communications signals (e.g., telephone, data, video signals). The power terminals  19  may include one or more battery backup terminals to provide backup power, charge a backup battery, and provide diagnostic signals (e.g., charge level) via a cable  21 , as further described below. ONT unit  7  may include facilities to detect when a loss of power occurs in order to draw power from battery backup. Other implementations of ONT unit  7  are also possible, as known in the art. 
     Referring again to  FIG. 1 , customer premises  1  will include a power outlet  10 , for example a standard 3-prong 110 VAC outlet. As shown, power outlet  10  is sited within customer premises  1 . For purposes of the current example of implementation, the power outlet  10  is located more than 10 feet (for wiring purposes) from the ONT  7 . 
     Further provided in  FIG. 1  is an optical power supply unit (OPSU)  11 . OPSU  11  is connected to power outlet  10  via a standard power cable  12 , consistent with electrical codes (for example, which may require cable  12  to be eight feet or less in length). OPSU  11  may provide a power transformation facility to convert the 110 VAC power provided from power outlet  10  to, for example, 48 VDC power which can be used to power ONT unit  7 . OPSU  11  is connected to the ONT unit  7  via cable  13 . Cable  13  may utilize small gauge wiring such as 24 AWG wiring as used in Cat 5e cables. Cable  13  may be as long as 100 feet, and deployed through the same conduit  14  as cables  9 . 
     A battery backup unit (BBU)  16  is also shown in  FIG. 1 . BBU  16  provides an uninterruptible power source to ONT unit  7 , and may comprise a battery storing charge to supply sufficient power for minimal operation of ONT unit  7  for a certain period of time when ONT unit  7  loses power from OPSU  11 . BBU  16  may be connected to the ONT unit  7  via a cable  21 , which in this example may be bi-directional; ONT unit  7  may provide power to BBU  16  over cable  21  in order to charge BBU  16  while ONT unit  7  is being provided with power, and BBU  16  may provide power to ONT unit  7  over cable  21  when ONT unit  7  is no longer receiving power. Cable  21  may include wiring to provide diagnostic signals between BBU  16  and ONT unit  7  (e.g., charge levels). 
     As  FIG. 1  illustrates, the use of OPSU  11  allows the power outlet  10  to be placed more than ten feet from the ONT unit  7 —in this example, anywhere up to 100 feet from the 
     ONT unit  7 , as OPSU  11  can provide ONT unit  7  with sufficient power over small gauge power cabling (such as 24 AWG wire) over longer distances. 
       FIG. 3  shows another implementation of a system according to the present invention. In contrast to the system shown in  FIG. 1 , the system in  FIG. 3  places a BBU  36  in series between OPSU  11  and an ONT unit  37 . BBU  36  may be different from BBU  16  in that it is configured to receive a power input from OPSU  11  (which, in this example, is a 48 VDC source), and provide a main power supply to the ONT unit  7  over cable  21 . In normal operation, BBU  36  will act as a pass-through, allowing the power provided from OPSU  11  to flow to ONT unit  7  (while using a portion thereof to maintain a charge level on its internal battery). If a power outage occurs, BBU  36  then provides power from its battery backup to the ONT unit  7 . BBU  36  may include facilities to detect such a loss of main power. 
     In an additional alteration to the embodiment shown in  FIG. 3 , BBU  36  may include a power conversion facility to transform the power supply from the OPSU  11  (in this example, 48VDC) to a lower-voltage power form, such as 12VDC. The lower voltage power is then provided to the ONT unit  7 . ONT unit  7  in this case is configured to operate using the lower voltage power instead of the power supplied by the OPSU  11 . 
     By including the BBU in series between the ONT unit  7  and the OPSU  11 , additional distances may be achieved between the power outlet  10  and the ONT unit  7 . For example, where the cable  21  can be a long as 50 feet, a maximum wire distance of 158 feet (50 feet for cable  21 , 100 feet for cable  13  and 8 feet for cable  12 ) may be accommodated. 
     While the present invention(s) has been disclosed through reference to various exemplary and preferred embodiments thereof, those of ordinary skill in the art will understand that various changes may be made in the form and details described herein without departing from the spirit and scope of the invention(s), the scope of which is/are defined by the claims appended hereto. Those of ordinary skill in the art will recognize or be able to ascertain many equivalents to the exemplary embodiments described herein. Such equivalents are intended to be encompassed by the scope of this disclosure and the appended claims.