Abstract:
A device may provide a first opening via which a feeder optical fiber cable that carries an input signal enters the device. In addition, the device may include a slot configured to retain a splitter module. The splitter module may include a single-fiber input cable that receives and carries the input signal from the feeder optical fiber cable, an optical splitter that receives the input signal from the single-fiber input cable, splits the input signal into a plurality of output signals, and transmits each of the plurality of output signals, and a multi-fiber output cable that receives the plurality of output signals from the optical splitter and carries the plurality of output signals. The device may also provide a second opening via which a multi-fiber distribution cable that receives the plurality of output signals from the multi-fiber output cable exits the device. The multi-fiber distribution cable may carry the plurality of output signals.

Description:
BACKGROUND INFORMATION 
       [0001]    Fiber distribution hubs may be installed inside a building to provide dwellers within the building with optical fiber lines. A fiber distribution hub may include a splitter module that splits an optical beam from an optical fiber (e.g., a fiber in a feeder cable from a service provider) into multiple optical beams, and outputs the split beams to multiple optical fibers. The multiple optical fibers are typically connected to cables that provide service (e.g., cable television programs, video-on-demand, etc.) to customers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  illustrates an exemplary optical network in which concepts described herein may be implemented; 
           [0003]      FIG. 2  is a block diagram of a portion of an exemplary multiple dwelling unit complex; 
           [0004]      FIG. 3  is a functional block diagram of a fiber distribution hub of  FIG. 2 ; 
           [0005]      FIG. 4  illustrates the fiber distribution hub of  FIG. 3  according to one exemplary implementation; 
           [0006]      FIG. 5A  illustrates an exemplary implementation of a splitter module of  FIG. 4 ; 
           [0007]      FIG. 5B  is a diagram illustrating exemplary contents of a splitter container of  FIG. 5A ; 
           [0008]      FIG. 6  illustrates another exemplary implementation of the splitter module of  FIG. 4 ; 
           [0009]      FIG. 7A  is a diagram of an adaptor of  FIG. 4  according to an exemplary implementation; 
           [0010]      FIG. 7B  illustrates operation of the adaptor of  FIG. 7A ; and 
           [0011]      FIG. 8  is a flow diagram of an exemplary process that is associated with operation of the fiber distribution hub of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0012]    The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
         [0013]    As described below, a compact fiber distribution hub may be attached to multi-fiber distribution cables. In such an implementation, a single run of multi-fiber distribution cable may service a number of premises (e.g., living units). In contrast, where a fiber distribution hub is attached to single-fiber distribution cables, multiple runs of single fiber distribution cable may be required to service the same number of premises. Thus, the compact fiber distribution hub may provide for savings in cost associated with cabling (e.g., 30% savings). 
         [0014]    In one implementation, a compact fiber distribution hub may include splitter modules that exclude fiber loop slack. Such a compact fiber distribution hub may be much smaller than ones that include splitter modules with fiber loop slack. Consequently, the compact fiber distribution hubs may be easier to install and configure. 
         [0015]      FIG. 1  shows an exemplary optical network  100  in which the concepts described herein may be implemented. As shown, optical network  100 , which may be referred to as a fiber-to-the-premises (FTTP) network, may include a central office  102 , a multiple dwelling unit complex  104 , a single dwelling unit complex  106 , and feeder optical fiber cables  108 . An actual optical network may include may include additional, fewer, or different dwelling complexes and components than optical network  100 . 
         [0016]    Central office  102  may include a site that houses telecommunication equipment, including switches, optical line terminals, etc. Central office  102  may provide telecommunication services to subscribers, such as telephone service, access to the Internet, cable television programs, etc., via optical line terminals. 
         [0017]    Multiple dwelling unit complex  104  may include apartments, condominiums, and/or other types of living units that are aggregated in a high-rise or another type of building. Single dwelling unit complex  106  may include attached town houses, single detached houses, condominiums, and/or other types of horizontally aggregated living units. 
         [0018]    Feeder optical fiber cables  108  may include optical fiber cable bundles that interconnect multiple dwelling unit complex  104  and/or single dwelling unit complex  106  to optical line terminals in central office  102 . 
         [0019]      FIG. 2  is a diagram of a portion of an exemplary multiple dwelling unit complex  104 . As shown, multiple dwelling unit complex  104  may include a floor/ceiling  202 , a wall  204 , a fiber distribution hub  206 , a distribution cable bundle  208 , a fiber distribution terminal  210 , a drop cable  212 , a optical network terminal  214 , and a living unit  216 . In  FIG. 2 , some components of multiple dwelling unit complex  104  are omitted for the sake of simplicity in illustration (e.g., stairs, doors, elevators, etc.). In addition, depending on the implementation, multiple dwelling unit complex  104  may include additional, fewer, or different components than those illustrated in  FIG. 2 . For example, in some implementations, fiber distribution terminal  210  may be connected to fiber distribution hub  206  through another component, such as a collector box that receives ribbon fiber cables, and provides the ribbon cables connectivity to fiber distribution terminals. 
         [0020]    Ceiling/floor  202  and wall  204  may partition space within multiple dwelling unit complex  104  into multiple living units. Fiber distribution hub  206  may include an enclosure (e.g., a plastic or metal cabinet) to receive feeder optical fiber cables  108 , split an optical signal on an optical fiber within optical fiber cables  108  into multiple optical signals, convey the split optical signals to fiber distribution cables, collect the fiber distribution cables into distribution cable bundle  208 , and provide distribution cable bundle  208 . 
         [0021]    Distribution cable bundle  208  may include fiber distribution cables that carry optical fibers from fiber distribution hub  206  to fiber distribution terminal  210 . In some implementations, distribution cable bundle  208  may be tapered as it is routed vertically through multiple dwelling unit complex  104  and as fiber distribution cables are branched from distribution cable bundle  208  to feed one or more of fiber distribution terminal  210 . Fiber distribution terminal  210 , which is also referred to as fiber access terminal  210 , may include an enclosure to receive a fiber distribution cable from distribution cable bundle  208 . 
         [0022]    Drop cable  212  may include an optical fiber that carries an optical signal from a fiber distribution cable in fiber distribution terminal  210  to optical network terminal  214 . Typically, drop cable  212  may be installed in a raceway that is placed along the ceiling of a hallway, in a conduit, in a duct, etc. 
         [0023]    Optical network terminal  214 , which may also be called optical network unit  214 , may receive optical signals via drop cable  212  and convert the received optical signals into electrical signals that are further processed or carried over, for example, copper wires to one or more living units. In some implementations, optical network terminal  214  may be placed within a living unit, and devices that use services offered by central office  102  may be directly connected to optical network terminal  214 . 
         [0024]    Living unit  216  may include a partitioned space that a tenant or an owner of the living unit  216  may occupy. Living unit  216  may house devices that are attached directly or indirectly, via copper wires, to optical network terminal  214  to receive services that central office  102  provides. 
         [0025]      FIG. 3  is a functional block diagram of fiber distribution hub  206 . As shown, fiber distribution hub  206  may include splitter modules  302 - 1  through  302 - 6  (herein individually and collectively referred to as splitter modules  302  and splitter module  302 , respectively), a splitter output parking unit  304 , and a adaptor matrix  306 . Depending on the implementation, fiber distribution hub  206  may include additional, fewer, or different functional components than those illustrated in  FIG. 3 . For example, in some implementations, fiber distribution hub  206  may include additional splitter modules (e.g., 13 additional splitter modules), and/or may not include splitter output parking unit  304 . 
         [0026]    Splitter module  302  may include an assembly of an optical splitter and optical fiber cables. Splitter module  302  may receive an optical signal over an input cable, split the beam into multiple optical signals, and transmit the multiple optical signals to output cables that are connected to the optical splitter. 
         [0027]    In  FIG. 3 , an input cable of splitter module  302  may be attached to a fiber cable from feeder optical fiber cables  108 . In one implementation, feeder optical fiber cables  108  may enter fiber distribution hub  206  from the bottom or lower portion, be routed through fiber distribution hub  206 , and provide an optical fiber cable that is mated to an input cable of splitter module  302  via connectors and an adaptor. 
         [0028]    Splitter output parking unit  304  may include slots in which ribbon cables from splitter modules  302  may be parked until the ribbon cables are attached to fiber distribution cables to provide signal pathways to living units  216  in multiple dwelling unit complex  104 . 
         [0029]    Adaptor matrix  306  may include a mechanism (e.g., fiber optic patch panel) to hold adaptors via which connectors at ends of output cables from splitter modules  302  and connectors at ends of fiber distribution cables are adjoined. In some implementations, the components may include adaptors (e.g., plugs, etc.) or the like, that join multi-fiber connectors (e.g., mechanical transfer-angle polished connector (MT-APC)). 
         [0030]    Although not illustrated in  FIG. 3 , fiber distribution hub  206  may be housed in a metal or plastic enclosure. The metal or the plastic enclosure may be Underwriters Laboratory (UL) listed. 
         [0031]      FIG. 4  illustrates fiber distribution hub  206  according to one exemplary implementation  400 . As shown, fiber distribution hub  400  may include feeder/input cable space  402 , splitter module slots  404 , adaptor panels  406 - 1  through  406 - 3  (herein collectively and individually referred to as adaptor panels  406  and adaptor panel  406 - x,  respectively), a parking panel  408 , upper slack space  410 , and side slack space  412 . Depending on the implementation, fiber distribution hub  400  may include fewer, additional, or different components than those illustrated in  FIG. 4 . For example, in one implementation, fiber distribution hub  400  may not include parking panel  408 . 
         [0032]    Feeder/input cable space  402  may include space in which feeder optical fiber cables that are routed from the bottom of fiber distribution hub  400  may be spliced or connected to input cables for splitter modules that are inserted in fiber distribution hub  400 . In some implementations, splitter modules in fiber distribution hub  400  may be positioned with their input cables facing the back of hub  400 , and, feeder input cable space  402  may be eliminated or provisioned toward the back of hub  400 . 
         [0033]    Splitter module slots  404  may include slots or space into/from which optical splitter modules may be inserted/removed. Depending on the implementation, splitter module slots  404  may accept a splitter module that splits an input beam into 8, 16, 32, or 64 output beams (e.g., 1×8 splitter module, 1×16 splitter module, 1×32 splitter module, 1×64 splitter module, etc.), 
         [0034]    In one implementation, splitter module slots  404  may be dimensioned to accept splitter modules which do not include a feature that is herein referred to as fiber loop slack, as described below. In other implementations, splitter module slots  404  may accept splitter modules with fiber loop slack. 
         [0035]    Although  FIG. 4  shows splitter module slots  404  that are designed to receive splitter modules, such as splitter module  414 , in the upright position, in a different implementation, splitter module slots  404  may accept splitter modules  414  in different orientations (e.g., horizontal, sideways, angled, etc.). Depending on the number of living units  216  that are to be connected or served via fiber distribution hub  400 , additional splitter modules  414  may be added or removed from splitter module slots  404 . 
         [0036]    Adaptor panel  406 - x  may include a panel/matrix of adaptors (e.g., an adaptor array, a plug array, etc.), such as adaptor  416 . Adaptor panel  406 - x  may include a slot into which adaptor  416  may be inserted, such that front and back ports (not shown) of adaptor  416  face the front and the back of fiber distribution hub  400 , respectively. In such a configuration, the front port of adaptor  416  may receive a connector that is attached to an output cable from a splitter module (e.g., splitter module  414 , and the back port of adaptor  416  may receive a connector that is attached to a distribution cable (e.g., 12-fiber distribution cable), respectively. In a different implementation, adaptor panel  406 - x  may include adaptor slots. The slots may be filled with adaptors based on need. 
         [0037]    In  FIG. 4 , fiber distribution hub  400  is shown as including three adaptor panels  406 , where each adaptor panel has N×M (e.g., 2×9) adaptors/adaptor slots. Depending on the implementation, fiber distribution hub  400  may include additional or fewer adaptor panels  406  (some with different number of adaptors/slots) that may be added or removed based on need. 
         [0038]    Parking panel  408  may include slots, ports, or holes into which connectors that are attached to output cables from splitter modules may be temporarily placed. For instance, assume that adaptor  416  in adaptor panel  406 - 1  is about to be cleaned. In such an instance, a connector that is plugged into adaptor  416  may be unplugged from adaptor  416  and parked in a slot/hole  418  in parking panel  408 . After adaptor  416  is cleaned, the connector may be plugged back into adaptor  416 . 
         [0039]    Upper slack space  410  and side slack space  412  may include space for routing output cables from splitter modules to adaptors in adaptor panel  406 - x  and/or slots/holes in parking panel  408 . As further shown in  FIG. 4 , upper slack space  410  and side slack space  412  may include cable hooks  420 - 1  and  420 - 2 , cable disk  422 , and other cable hooks and disks (not labeled). Cable hooks  420 - 1  and  420 - 2  and cable disk  422  may be used to guide the output cables toward adaptor panel  406 - x  or parking panel  408 . 
         [0040]    For example, in  FIG. 4 , output cable  424  from splitter module  414  may be wound about cable hook  420 - 1 , routed to cable disk  422 , bent around cable disk  422  downwardly toward cable hook  420 - 2 , routed to cable hook  420 - 2 , bent around cable hook  420 - 2 , and routed to adaptor  416 . Each of cable hooks  420  and cable disks  422  has a radius of curvature that is sufficiently large for an optical fiber cable to bend around the cable hook/disk without damaging optical fibers in the cable or degrading optical signaling. 
         [0041]      FIG. 5A  illustrates an exemplary implementation  500  of splitter module  414 . Splitter module  500  includes a feature that is herein referred to as fiber loop slack, as explained further below. As shown, splitter module  500  may include a connector  502 , an input cable  504 , a splitter container  506 , ribbon cables  508 - 1  through  508 - 3  (herein collectively referred to as ribbon cables  508  and individually as ribbon cable  508 - x ), and connectors  510 - 1  through  510 - 3  (herein collectively referred to as connectors  510  and individually as connector  510 - x ). Depending on the implementation, splitter module  500  may include additional, fewer, or different components (e.g., additional ribbon cables  508 , connectors  510 , etc.) than those illustrated in  FIG. 5A . 
         [0042]    Connector  502  may include a component that encases an optical fiber end. When connector  502  is coupled to another component (etc., another optical fiber cable, a waveguide, etc.), the fiber end may be axially aligned with the optical signaling path in the other component. Examples of connector  502  may include a subscriber connector (SC), 2 or 3 millimeter (mm) SC-angle polished connector (SC-APC), etc. In some implementations, such as in APC connectors, a ferrule (e.g., a ceramic holder for the optical fiber end) and the fiber end are polished at an angle to reduce internal reflection of the optical signal where the optical fiber is coupled to the other component. 
         [0043]    Input cable  504  may encase an optical fiber segment that extends from connector  502  to an optical splitter housed in splitter container  506 . In some implementations, input cable  504  may have a fiber that has a functional bend radius of less than or equal to 10 mm. Splitter container  506  may contain splitter components that split an optical signal from input cable  504  into multiple optical signals and output the multiple optical signals via ribbon cables  508 . 
         [0044]    Ribbon cable  508  may encase one or more optical fiber segments that extend from the optical splitter housed in splitter container  506  to connectors  510 . Each ribbon cable  508  may encase multiple optical fiber segments. For example, in one implementation, ribbon cables  508 - 1 ,  508 - 2 , and  508 - 3  may encase 12, 12, and 8 optical fibers, respectively. 
         [0045]    Connector  510  may include a component to encase fiber ends. When connector  510  is coupled to another component (e.g., ribbon cable), the fiber ends may be axially aligned with the optical signaling paths in the other component. Examples of connector  510  may include a mechanical transfer-APC (MT-APC), which may have 1.2 times the form factor (e.g., size) of an SC-APC. Such a connector may be mated to another connector attached to a distribution cable running to one of the floors in multiple dwelling unit complex  104 . Depending on the number of cable drops per floor, connector  510  may be implemented as 4-fiber, 8-fiber, 12-fiber, or other types of MT-APC connector. The 4-fiber, 8-fiber, or 12-fiber MT-APC may allow, respectively, 4, 8, and 12 cables to be dropped on a floor in a single distribution cable run. 
         [0046]    When included in fiber distribution hub  400 , splitter modules (e.g., 1×32 splitter modules) that use MT-APCs (e.g., two 12-fiber MT-APCs and one 8-fiber MT-APC) to couple their output cables to distribution cables may allow fiber distribution hub  400  to provide approximately 20 times the number of connections to living units  216  (e.g., via distribution cables and drop cables) than a similarly sized fiber distribution hub that includes splitter modules (e.g., 1×32 splitter modules) using SC-APCs to couple their output cables to distribution cables. For example, fiber distribution hub  400  that includes 18 1×32 splitter modules with two 12-fiber MT-APCs, and an 8-fiber MT-APC (e.g., to accommodate 32 optical fibers) may provide for 576 connections/drop cables. 
         [0047]      FIG. 5B  is a diagram that illustrates exemplary contents of splitter container  506 . As shown, splitter container  506  may include an optical splitter  512  and fiber loop slack  514 . In an actual implementation, splitter container  506  may include additional or different components than those illustrated in  FIG. 5B . 
         [0048]    Optical splitter  512  may include a component to receive input cable  504  and provide optical signals to ribbon cables  508 . For example, optical splitter  512  may split an optical signal received via input cable  504  into multiple optical signals and output the multiple optical signals via ribbon cables  508 . Optical splitter  512  may be small compared to the overall size of splitter container  506 , whose size may be governed by the size of fiber loop slack  514 . 
         [0049]    Fiber loop slack  514  may include a portion of input cable  504  that is wound into one or more loops before input cable  504  enters optical splitter  512 . In addition, fiber loop slack  514  may include a portion of ribbon cables  508  that are wound into one or more loops before output cables  508  exit splitter container  506 . The size of fiber loop slack  514  may depend on the type of optical fibers in input cable  504  and output cables  508 . 
         [0050]    Typically, splitter container  506  may include fiber loop slack  514  for a number of reasons. For example, if optical splitter  512  is located close to an optical signal source (e.g., laser), in terms of relative distance that the optical signal travels from the source to optical splitter  512 , the optical signal at optical splitter  512  may be distorted. Including fiber loop slack  514  may increase the distance between the source and optical splitter  512 , and therefore, may reduce or eliminate the distortion. 
         [0051]    In another example, if optical splitter  512  is located in an outdoor fiber distribution hub, optical splitter  512  may be exposed to climate changes. At low or high temperatures, input cable  504  and/or ribbon cable  508  may contract/expand relative to the encased optical fiber(s). In such instances, without fiber loop slack  514 , the encased optical fibers may bend at various points on input and output cables  504  and  508 . 
         [0052]      FIG. 6  is a diagram of splitter module  414  according to another implementation  600 . Unlike splitter module  500 , splitter module  600  may not include fiber loop slack. As shown, splitter module  600  may include components that correspond to some of the components illustrated in  FIG. 5A . In  FIG. 6 , components that correspond to those in  FIG. 5A  are labeled with the same numbers. The components illustrated in  FIG. 6  may operate similarly as the corresponding components described with respect to  FIG. 5A . 
         [0053]    In contrast to splitter module  500  in  FIG. 5A , however, splitter module  600  may include splitter container  602  that is smaller than splitter container  506 , as splitter container  602  does not include fiber loop slack, such as fiber loop slack  514 . In further contrast, input cable  504  and ribbon cables  508  in splitter module  600  may be located on the back and front sides of splitter container  602 , and therefore, when splitter container  602  is inserted inside fiber distribution hub  400 , splitter input and outputs may be accessible from the front and back of fiber distribution hub  400 . 
         [0054]    In some implementations, splitter module  600  may include components that protect the optical splitter within splitter container  602  against forces that may be applied to input cable  504 /ribbon cables  508 , such as strain relief guides, fan-outs, etc. Without the components, such forces may detach the optical splitter from optical fibers in input cable  504 /ribbon cables  508 . 
         [0055]      FIG. 7A  is a diagram of adaptor  416  according to an exemplary implementation  700 . As shown, adaptor  700  may include a front port  702 , a back port (not shown), and a fitting feature  704 . 
         [0056]    Front port  702  may provide a slot into which connector  510 - x  may be inserted. The back port may provide another slot into which a connector that is attached to a distribution cable may be inserted. In  FIG. 7A , the back port is not visible due to the orientation in which adaptor  416  is illustrated. Fitting feature  704  may include an element (e.g., a groove, a protrusion, etc.) that may aid in fitting adaptor  416  in a slot  706  placed in adaptor panel  406 - x  (see also  FIG. 4 ). In  FIG. 7A , adaptor  700  may be slid, in the direction indicated by arrow A, into slot  706  and held in place via fitting feature  704  and slot  706 . 
         [0057]      FIG. 7B  illustrates operation of adaptor  700  after adaptor  700  is fitted into slot  706  of adaptor panel  406 - x.  As shown, a connector  708  that is attached to a distribution cable  710  is inserted in the back port of adaptor  700 . Connector  510 - x  may optically couple to connector  708  when connector  510 - x  is inserted in front port  702  in the direction indicated by arrow B. In this manner, adaptor  700  may provide for an optical path from ribbon cable  508 - x  to distribution cable  710 . 
         [0058]      FIG. 8  is a flow diagram of an exemplary process  800  that is associated with operation of fiber distribution hub  400 . Although process  800  is depicted as starting at block  802 , in different implementations, process  800  may start at other blocks (e.g., block  804 ,  808 ,  812 , etc.). 
         [0059]    Splitter module  414  that includes an input cable and a multi-fiber output cable may be inserted into one of splitter module slots  404  of fiber distribution hub  400  (block  802 ). Depending on the implementation, the splitter module may include splitter module  500  or  600 . 
         [0060]    Fiber distribution hub  400  may receive feeder optical fiber cables  108  (block  804 ). For example, in one implementation, feeder optical fiber cables  108  may be inserted into fiber distribution hub  400  and routed through fiber distribution hub  400  toward splitter module slots  404 . 
         [0061]    Fiber distribution hub  400  may receive a distribution cable (block  806 ). For example, the distribution cable may be inserted into fiber distribution hub  400  and routed to the back of adaptor panel  406 - x.    
         [0062]    One of feeder optical fiber cables  108  may be connected to the input cable of splitter module  414  (block  808 ). For example, in one implementation, one of feeder optical fiber cables  108  may be connected to input cable  504 . More specifically, a connector (e.g., SC-APC connector) attached to one of feeder optical fiber cables  108  may be mated to connector  502  (e.g., SC-APC connector) that is attached to input cable  504  of splitter module  600 , via adaptor  416  (e.g., bulkhead adaptor). 
         [0063]    The multi-fiber output cable of splitter module  414  may be connected to the distribution cable (block  810 ). For example, in one implementation, ribbon cable  508 - x  may be connected to the distribution cable. More specifically, a connector (e.g., MT-APC connector) attached to ribbon cable  508 - x  may be mated to another connector (e.g., MT-APC connector) that is attached to the distribution cable, via adaptor  416  (e.g., MT-APC plug). 
         [0064]    In a building that includes fiber distribution hub  400 , the distribution cable may be routed to fiber distribution/access terminal  214  (block  812 ). Once the distribution cable is run to fiber distribution/access terminal  214 , drop cables may be installed from fiber distribution/access terminal  214  to individual livings units to provide optical fiber services from central office  102 . 
         [0065]    The above describes process  800  associated with various implementations of fiber distribution hub  400  and components that are associated with fiber distribution hub  400 . As indicated in the preceding description, fiber distribution hub  400  may be attached to multi-fiber distribution cables. In such cases, a single run of multi-fiber distribution cable may service a number of premises (e.g., living units). For example, a single run of 12-fiber distribution cable may provide for 12 drop cables to 12 different premises. In contrast, where a fiber distribution hub is attached to single-fiber distribution cables, multiple runs of a single-fiber distribution cable may be required to service the same number of premises. Thus, fiber distribution hub  400  may provide for savings in cost associated with deployment (e.g., 30% savings). 
         [0066]    Further, in one implementation, fiber distribution hub  400  may include splitter modules  600  that exclude fiber loop slack. By using such splitter modules, fiber distribution hub  400  may be constructed smaller than ones that include splitter modules with single-fiber output cables and/or fiber loop slack (e.g., 60% smaller). 
         [0067]    In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. 
         [0068]    For example, while a series of blocks have been described with regard to the process illustrated in  FIG. 8 , the order of the blocks may be modified in other implementations. In addition, non-dependent blocks may represent blocks that can be performed in parallel. 
         [0069]    No element, block, or instruction used in the present application should be construed as critical or essential to the implementations described herein unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.