Abstract:
Described herein are systems and methods for a field-configurable optical network terminal (ONT) device at a subscriber to provide one or more communication services to the subscriber. The field-configurable ONT device is of a modular design operable for the insertion of additional communication modules or removal of existing communication modules from the ONT device for scaling the device to increased or decreased communication capacity as desired.

Description:
BACKGROUND 
     Passive optical networks (PONs) are fast replacing hybrid fiber coaxial networks (HFCNs) as the communication topology of choice for service providers such as telephone, cable television, and Internet service providers. In a HFCN, a fiber optic cable is used to transmit optical signals between a central premise or office of a communication service provider (hereinafter, “service provider”) and a fiber optic node located near a service subscriber or customer, such as a residential home subscribing to a telephone service, cable television (CATV) service, data (e.g., Internet) service, or any combination thereof. The fiber optic node employs powered or active components to receive and convert the optical signals into radio frequency (RF) signals for transmission via a coaxial cable to the subscriber&#39;s home. Like a HFCN, a PON is a point-to-multipoint communication network that uses a fiber optical cable to transmit optical signals. However, as its name implies, the PON employs non-powered or passive optical elements to provide optical signals from an optical line terminal (OLT) of the service provider to the service subscribers or customers without the need for a fiber optic node to perform optical-to-RF conversion. Each subscriber&#39;s home is equipped with an optical network terminal (ONT) apparatus or unit that provides the necessary optical-to-RF conversion to provide the subscriber with the subscribed telephone, CATV, and data services. 
     A conventional ONT unit is typically found mounted to the side of a subscriber&#39;s home and factory-configured to provide a fixed number of telephone lines, video feeds, and data lines to the subscriber&#39;s home. Thus, once the subscriber desires more telephone, video, or data lines than the ONT unit is capable of providing, the old ONT unit must be replaced with a new, more capable ONT unit. This problem is more prevalent in a multi-dwelling unit, such as an apartment building or a commercial business building with multiple tenants, wherein the number of communication or service lines (e.g., telephone, video, and data lines) periodically vary due to the constant migration of tenants in and out of such a premise. A typical solution to this problem is to initially provide an ONT unit that has more communication or service capacity than needed so as to accommodate any future increased need for communication lines. However, such a solution is not cost effective because it requires a more expensive upfront purchase and installation of a more-capable ONT unit that initially is not fully utilized and may or may not be fully utilized in the future. 
     SUMMARY 
     Described herein are embodiments for an ONT unit of a modular design that provides multiple subscribers with service connections for their telephony appliances (telephones, fax machines, modems, etc), video components (set top boxes, TVs, VCRs, etc.) and data networking equipments (switches, routers, gateways, etc.). The ONT unit includes one or more removable communication modules for providing multiple communication lines, such as telephone, video, and data lines. The modular design of the ONT unit provides it with the flexibility to be field configurable during its operation, as opposed to permanent factory-configured, to provide scalability for communication capacity. Thus, the scalable ONT unit is cost effective for an operator to purchase and configure with the requisite number of communication modules to provide the desired communication capacity (e.g., desired number of communication lines). The unit&#39;s modular design also enables the user to reconfigure the unit during its operation in the field by facilitating additional communication modules or removal of existing communication modules to accommodate a desire increase or decrease in communication lines. 
     Accordingly, in one embodiment, there is provided an optical network termination (ONT) device for deployment at a subscriber of at least one communication service provided via a fiber optic network, wherein the ONT device includes a first communication module that operates to provide the at least one communication service to the subscriber via the fiber optic network, a plurality of slots that operate to interface with the first communication module to provide the at least one communication service to the subscriber via the fiber optic network, a system controller module that operates to control the first communication module and any other communication module through the plurality of slots to effect the at least one communication service to the subscriber, and a backplane communication bus that operates to electrically connect the plurality of slots to the system controller module, and wherein the ONT device is field configurable to provide a decrease in a communication capacity of the at least one communication service to the subscriber through a removal of the first communication module from interfacing with at least one of the plurality of slots. 
     In another embodiment, there is provided a method for providing a scalable optical network terminal (ONT) device at a subscriber to provide at least one communication service to the subscriber via a passive optical network (PON), wherein the method includes implementing a plurality of communication modules in the ONT device to provide the at least one communication service to the subscriber via the PON, implementing a plurality of slots in the ONT device to interface with the plurality of communication modules, implementing a system controller module in the ONT device to control the plurality of communication modules through the plurality of slots to provide the at least one communication service to the subscriber via the PON, implementing a power supply module in the ONT device to provide power to the system controller module and the plurality of communication modules, and facilitating a removal of one of the plurality of communication modules to decrease a communication capacity of the ONT device to provide the at least one communication service. 
     In yet another embodiment, there is provided an optical network terminal (ONT) device having a computer-readable medium (CRM) therein to implement the aforementioned method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which: 
         FIG. 1  illustrates a block diagram of an optical network terminal (ONT) unit having a modular design in accordance with one embodiment; 
         FIG. 2  illustrates the connection between an ONT unit and a network interface device (NID), in accordance with one embodiment; 
         FIG. 3  illustrates a modular platform for an ONT unit, in accordance with one embodiment; 
         FIG. 4  illustrates a process for module discovery in an ONT unit, in accordance with one embodiment; and 
         FIG. 5  illustrates a process for module removal from an ONT unit, in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     For simplicity and illustrative purposes, the principles of the embodiments are described by referring mainly to examples thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one of ordinary skill in the art, that the embodiments may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. 
       FIG. 1  illustrates a block diagram of an ONT unit or device  100  having a modular design in accordance with one embodiment. The ONT unit  100  includes a system controller card or module  110 , a communication bus  120 , a plurality of communication modules  130 - 136 , and a power supply module  140 .  FIG. 1  illustrates the communication modules as Ethernet cards or modules  130  and  131 , very high speed digital subscriber line (VDSL) cards or modules  132  and  133  for data lines, plain old telephone service (POTS) cards or modules  134  and  135  for telephone lines, and a video card or module  136  for video feeds. Each Ethernet module  130  or  131  provides a predetermined number of Ethernet ports (e.g., 8 Ethernet ports). Each VDSL module  132  or  133  provides a predetermined number of VDSL ports (e.g., 8 VDSL ports). Each POTS module  134  or  135  provides a predetermined number of POTS lines (e.g., 12 POTS lines). Thus, the ONT unit  100  may accept any complement of Ethernet, VDSL, and POTS modules to realize the desired number of Ethernet, VDSL, and POTS lines. For example, an operator from a telephone company may decide to populate the ONT unit  100  with only one POTS module and one Ethernet module for a small installation. 
     The ONT unit  100  is connected to a PON via a fiber optic cable to receive optical signals sent down from a service provider. Thus, in one embodiment, the video module  136  interfaces to the PON. It contains an optical transducer, such as a triplexer, that provides a single fiber interface for the multiple (e.g., three) wavelengths used on the PON. The triplexer demodulates the optical signals from the PON into downstream electrical signals and forwards the PON data as downstream electrical signals to the system controller module  110  for processing. Thus, the triplexer may include an analog detector, a data detector, an upstream laser, and a wave division multiplexer in a single assembly as understood in the art. The system controller  110  is connected to the communication modules  130 - 136  through the communication bus  120 , which acts as a high speed backplane that also delivers power to the various components and modules in the ONT unit  100  from the power supply module  140 . Thus, in addition to the desired communication modules  130 - 135 , the system controller module  110 , the video module  136 , and the power supply module  140  are included in the ONT unit  110  for operation. 
     Accordingly, the system controller  110  processes the PON data, as received from the video module  136  via the communication bus  120 , and forwards the downstream electrical signals to one of three other module types: Ethernet modules  130  and  131 , VDSL modules  132  and  133 , or POTS (voice) modules  134  and  135 . For example, electrical signals for voice data is passed to each POTS module  134  or  135  via a time-division multiplexing (TDM) channel; electrical signals for Ethernet data or voice over Internet protocol (VoIP) is transferred to each Ethernet module  130  or  131  through use of a 1000Base-X data channel; and electrical signals for VDSL data (e.g., for Internet service) is transferred via a serialized Utopia Interface to each VDSL module  132  or  133 . As for video data, electrical signals for such data are converted to RF signals directly on the video module  136  and output via, for example, a F connector. In an alternative embodiment, the RF conversion for video data may be performed by a dedicated video module, and the demodulation of the optical signals from the PON may be performed by a demodulation module separate from the video module. 
     The system controller module  110  also receives upstream data from each of the communication modules  130 - 135  and places that data on the PON via the video module  136  (or a separate module for modulation/demodulation optical signals to and from the PON) for transmission back to the optical line termination (OLT) at the service provider. Thus, the system controller  110  supports Ethernet data processing (for both data and VoIP) and/or VDSL (ATM) processing as desired by the service provider, wherein return path (upstream) demodulation for signals from the communication modules  130 - 133  is also performed as understood in the art. In one embodiment, the video module  136  includes its own return path demodulator that is operable to demodulate the return path RF signals for video data from a video component (e.g., set top box) and pass the demodulated data through the communication bus  120  to the system controller module  110 , which then processes and inserts the data into the PON return traffic through the video module  136 . The system controller module  110  further supports voice processing for the POTS modules  134  and  135 . The POTS modules  134  and  135  provide a subscriber line interface that transmits and receives analog phone signals over existing in-home telephone wiring via a network interface device (NID) as further described below. The system controller module  110  then takes the analog voice stream and converts it to data packets for further processing, whereby the voice stream passes to a Codec that converts the analog signal to digital if being sent to a digital signal processor (DSP) on the system controller module  110  and digital to analog if sent from the DSP. The DSP packetizes the voice stream for transmission by the video module  136  and depacketizes received data from the video module  136  for conversion back to analog to send to the NID. The DSP also detects tones, such as dual tone multifrequency (DTMF), generates tones such as busy tones, detects dial tones, and eliminates echoes generated in the loop between the subscriber line interface and the telephone. 
     The ONT unit  100  is connected to a NID that is typically installed in the basement, first floor telco room, garage, or outside the subscriber&#39;s premise to provide outputs of the communication modules  130 - 136  to the NID.  FIG. 2  illustrates the connection between the ONT unit  100  and a separate NID  200 . Alternatively, the NID  200  may be housed in the ONT unit  100  but kept separate from the rest of the ONT unit  100 . The NID  200  houses the customer interfaces that perform the typical code conversion, communication protocol conversion, and buffering required for voice, video, and data communication to and from the PON. It represents the demarcation point of the service provider, whereby its network ends and connects with the wiring at the subscriber&#39;s premise. 
       FIG. 3  illustrates a modular platform  300  for the ONT unit  100 , in accordance with one embodiment. The platform  300  includes multiple easy access slots for inserting and removing multiple cards or modules  310 - 316 . As illustrated, the slots are populated by a video module  310  (corresponding to the video module  136 ), a system controller card  311  (corresponding to the system controller module  110 ), two Ethernet or VDSL cards  312  and  313  (corresponding to the Ethernet modules  130 ,  131  or VDSL modules  132 ,  133 ), two POTS or voice cards  314  and  315  (corresponding to POTS modules  134 ,  135 ), and a power supply module  316  (corresponding to the power supply module  140 ). Each slot may include a pair of injector arms  350  for securing a card in place. Although  FIG. 3  illustrates only seven slots for populating seven modules, it should be understood that the platform  300  may include any number of slots as desired or feasible. A cover  318  is provided to protect the platform  300  and components therein, and it also may be used to prevent unauthorized access to the ONT unit.  FIG. 3  also illustrates a fiber storage enclosure  320  attached to the right side of the modular platform  300  to store the fiber optic cable that provides connection of the platform  300  to the PON (e.g., via a NID). 
     The ONT  100  is operable to allow communication or line modules  312 - 315  (i.e., communication modules  130 - 136 ) to be added or removed while power is applied to the ONT  100  from the power supply module  316 . In one embodiment, the system controller module  311  (or module  110 ) is operable to detect the presence, addition, and removal of the line modules  312 - 315 . A module-detect interrupt signal from each slot in the platform  300  may alert the system controller module  311  to a removal or insertion event. At start-up of the ONT unit, the system controller module  311  polls the module detect interrupt signals to determine the device complement populating the slots of the ONT unit. 
       FIG. 4  illustrates a process  400  for module discovery by the system controller module  311  once a module is inserted or discovered at start-up. The system controller module  311  also performs this process after a slot has been provisioned for a previously-detected but unexpected module. For illustrative purposes only and not to be limiting thereof, the method  400  is discussed in the context of the ONT unit  300  ( FIG. 3 ). 
     At  410 , the system controller module  311  detects the type of line module that has been inserted or discovered by reading the module type from the module&#39;s memory, such as an electrically erasable programmable read-only memory (EEPROM). 
     At  412 , the system controller module  311  determines whether it has been provisioned with configuration data for the discovered module and whether the module type matches the configuration data. 
     At  414 , if the discovered module is not of a type expected or provisioned by the configuration data of the system controller module  311 , the system controller module  311  will not configure and activate the discovered module. If the discovered module includes a visual indicator for fault, such as a fault LED, the system controller module  311  may also illuminate such a LED to indicate a failure to configure and activate the discovered module. 
     At  416 , however, if the system controller module  311  has been provisioned with configuration data for the discovered module and the module type matches the configuration data, the system controller module  311  proceeds to provision and configure the discovered module for activation. If necessary the system controller module  311  may download the requisite firmware to the discovered module. 
     At  418 , the system controller module  311  activates the discovered module and allow traffic to pass through the discovered module. For example, if the discovered module is an Ethernet module, the serializer/deserializer (SERDES) for the slot is activated. If the discovered module is a VDSL module, a serial utopia bus for the slot is activated. If the discovered module includes a visual indicator for activation, such as an active light-emitting diode (LED), the system controller module  311  may also illuminate such a LED. 
       FIG. 5  illustrates a process  500  performed by the system controller module  311  for module removal when a module is removed from its slot in the ONT unit, as detected by the aforementioned detect-interrupt signals. The system controller module  311  also performs this process after a slot has been provisioned for a different module than previously expected (thus, removal is desired). For illustrative purposes only and not to be limiting thereof, the method  400  is discussed in the context of the ONT unit  300  ( FIG. 3 ). 
     At  510 , the system controller module  311  sends a notification through the PON to the service provider to indicate that the module has been removed. 
     At  512 , any software drivers or applications for the removed module is unloaded from the system controller module  311 . 
     At  514 , the system controller module  311  deactivates communication services to the removed module. For example, if an Ethernet module is removed, the system controller module  311  proceeds to deactivate the 1000Base-X bus output to that module. If a VDSL module is removed, the SERDES bus to that module is deactivated. If a video module is removed, the system controller module  311  proceeds to deactivate the RF power enable control line. This is done to ensure that RF power will be initially off when a video module is inserted into the ONT unit  300  later. The system controller module  311  also disables the addressable tap power applied to the RF output. 
     To perform the processes  400  and  500  and other functions described above, the system controller module  311  (or  110 ) includes one or more programmable logic devices, such as one or more field programmable gate arrays (FPGAs) or processors of any of a number of computer processors, such as processors from Intel, AMD, or Cyrix. Each programmable logic device is coupled to or includes at least one memory device, such as a computer readable medium (CRM), that is also included in the system controller module  311 . The processor is operable to execute computer-executable program instructions stored in the CRM, such as program code of applications, to run the applications. The computer-executable program instructions include code from any suitable computer-programming language, such as C, C++, C#, Java, or the like. Thus, for example, the CRM may store computer-executable program instructions for execution by the programmable logic device to perform the processes  400  and  500  and other functions of the system controller module  311  as described above. Examples of a CRM include but are not limited to an electronic, optical, magnetic, or other storage or transmission device capable of providing a programmable logic device with computer-readable instructions. Other examples of a suitable CRM include, but are not limited to, a floppy disk, CD-ROM, DVD, magnetic disk, memory chip, ROM, RAM, an ASIC, a configured processor, any optical medium, any magnetic tape or any other magnetic medium, or any other medium from which a programmable logic device is operable to read instructions. 
     The various embodiments of an ONT unit as described herein are field configurable to accommodate any desired number of communication lines, and they are scalable to adjust to a future desire or need to increase or decrease the number of communication lines. Accordingly, such an ONT unit provides a more cost-effective solution for both communication service providers and subscribers to set up communication via a fiber optic network such as a PON. 
     What has been described and illustrated herein are various embodiments along with some of their variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims, and their equivalents, in which all terms are meant in their broadest reasonable sense unless otherwise indicated.