Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This invention is related to U.S. patent application Ser. No. 11/539,292 for “STARTER-INTERRUPT DEVICE INCORPORATING GLOBAL POSITIONING SYSTEM FUNCTIONALITY”, filed Oct. 6, 2006, the disclosure of which is incorporated herein by reference. This application is also a continuation U.S. patent application Ser. No. 12/333,904 for “Automated Geo-Fence Boundary Configuration and Activation”, filed Dec. 12, 2008, the disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to location tracking, and more specifically to techniques for specifying and activating a location perimeter (referred to as a geo-fence), and detecting a boundary violation with respect to the specified perimeter. 
     DESCRIPTION OF THE RELATED ART 
     Location tracking is a useful mechanism for limiting or preventing theft of assets such as vehicles, and for recovering stolen assets. Various location tracking mechanisms are well known in the art. For example, Global Positioning System (GPS) functionality is a well-known and ubiquitous technique for tracking a vehicle&#39;s location. In addition, other mechanisms are known, such as triangulation by cellular telephone signal or other means. Radio frequency identification (RFID) systems are also well known, but are generally suitable only for short-range location tracking. 
     It is often useful to provide notification when an asset is moved beyond a defined geographic region, referred to herein as a “geo-fence”. A geo-fence can be defined by reference to a perimeter, or boundary, surrounding a geographic area. The geographic area can be substantially circular or can be a polygon or any other shape. A monitoring system includes a sensor mounted within the asset to be tracked, a communication link, and an alert notification mechanism. Asset owners and/or other parties can thus be notified when the geo-fence boundary is violated by the asset leaving the boundary. Notification of geo-fence violations in this manner can serve to limit or prevent theft, by promptly alerting an owner and/or law enforcement authorities that the asset has been moved without authorization. Ongoing location tracking can help authorities in their efforts to find a vehicle that has been stolen. 
     A limitation inherent in many currently available GPS monitoring systems is that they require a user to specify the geo-fence boundary settings, for example by drawing a perimeter on a map. This can be done, for example, on a website designed to facilitate geo-fence configuration. Other systems allow a user to specify a geo-fence by specifying a point location, for example by entering an address or coordinates, and indicating a maximum distance from the specified point. Thus, the user must obtain, by some means, a description or indication as to where the geo-fence should be placed. 
     Existing techniques for configuring and implementing geo-fences include those describe in, for example: Duvall, U.S. Pat. No. 6,665,613, for “Method of and Apparatus for Dynamically Geofencing Movable Vehicle and Other Equipment and the Like”, issued Dec. 16, 2003; and Harvey, U.S. Pat. No. 7,327,250 for “System for Providing a Virtual Vehicle Boundary”, issued Feb. 5, 2008. 
     One limitation of such techniques is that they fail to provide any mechanism for detecting movement of the asset from an arbitrary current location, unless the current location is manually specified by the user. In addition, whether the geo-fence is specified based on a point location or by drawing a perimeter on a map, existing techniques often fail to provide sufficient precision to detect small movements of the asset; in other words, no boundary violation is detected until the asset has moved outside the geo-fence, which may be a undesirably large area because of the inability to manually specify a small area immediately surrounding the asset. 
     For example, a user may specify a geo-fence surrounding a particular address at which a vehicle will be parked. It may not be feasible or possible to specify the geo-fence specifically or with a fine level of detail, since a) the correlation between address and GPS position may be imperfect, and b) the address may correspond to a large parking lot (such as at an airport), and the user may have no way of knowing where, specifically and within the parking lot, the vehicle is to be parked. Thus, the geo-fence configured by the user may be relatively large. As a consequence, small movements of the vehicle (such as those that remain within the coarse definition of the geo-fence) may go undetected. Such limitations can reduce reliability of the system and impair prompt response to events such as vehicle theft. In addition, current techniques are subject to error, since the user may specify the geo-fence incorrectly. Such error can result in false positives as well as the possibility that theft may go undetected. 
     Furthermore, existing techniques do not provide any automated means for activating location notification automatically or passively under certain conditions, using a geo-fence derived from a current location of the asset. 
     Existing techniques do not provide any mechanism for automatically determining the location of a remote asset and establishing a geo-fence or other boundary surrounding the asset based on its current location. Accordingly, existing location tracking techniques are of limited use in detecting movement of assets and of reliably notifying owners and other parties of asset movement. 
     What is needed is a system and method of location tracking and boundary violation notification that avoids the limitations of the prior art. What is further needed is a system and method that automatically defines a geo-fence based on a current location of an asset. What is further needed is a system and method that is adapted to automatically and/or passively activate boundary violation notification under certain conditions, so as to more reliably provide notification with a minimum of user effort. What is further needed is a system and method by which an owner of an asset can specify conditions in which the owner or some other entity is to be notified if the asset moves outside a geo-fence. 
     SUMMARY OF THE INVENTION 
     In various embodiments, the present invention enables automatic geo-fence establishment and activation. According to the present invention, a geo-fence is defined and established based on a current location of an asset, for example using GPS data comprising latitude and longitude along with some predetermined area based on range or distance. In this manner, the user need not manually specify a location by drawing a perimeter, specifying a point location, or by any other means. 
     Once established, the geo-fence can be activated so as to notify the owner of the asset and/or some other entity of movement of the asset beyond the boundary specified by the geo-fence. In one embodiment, the geo-fence can be automatically activated upon certain conditions, or can be manually activated, or any combination thereof. 
     For example, in one embodiment, the system and method of the present invention can be used to automatically activate a geo-fence when a driver parks a car and takes a portable Bluetooth-enabled device, such as a cellular telephone or RFID key fob, with him or her. An onboard device can be configured to detect the presence or absence of the portable device; when the vehicle is parked and the portable device is taken away from the vehicle, a geo-fence can be automatically defined and activated. The geo-fence can be defined based on a perimeter surrounding the current position of the vehicle. The onboard device communicates with a central server, for example over a cellular telephone network, to locate the vehicle using GPS to establish the geo-fence. 
     An automated notification protocol can be established in connection with the geo-fence, so that the driver (and/or some other entity, such as the police department) is automatically alerted if the vehicle is moved outside the geo-fence. For example, in the event the vehicle is moved outside the geo-fence, a boundary violation message can be sent via a cellular telephone network, by SMS text message, by email, instant message, or by any combination of the above. In some embodiments, more complex notification rule sets can be specified, to define the conditions in which a boundary violation message will be sent. 
     When the driver returns to the vehicle, the onboard device detects the presence of the portable device and deactivates the geo-fence. 
     In another embodiment, a geo-fence can be activated manually. For example, the geo-fence can be activated when the vehicle ignition is turned off, or when the vehicle is locked, or when the user inputs a command and/or enters a password on a keypad associated with the onboard device, or when the user presses a button on the portable device. In one embodiment, portable device can use Radio Frequency (RF) or infrared (IR) techniques to communicate with the onboard device. The onboard device communicates with a central server, for example over a cellular telephone network, to establish the geo-fence around the vehicle based on its current position. 
     Similarly, the geo-fence can be deactivated manually, for example by the user turning the ignition on, or by pressing a button on the portable device, or by entering a password on a keypad on the vehicle, or by some other means. 
     In yet another embodiment, the geo-fence can be activated and/or deactivated without the use of an onboard device at the vehicle. The driver (or other individual) can activate a geo-fence by direct communication with a central server, either by logging on to a web page, or by telephone call, SMS text message, instant message, or by some other means. Upon receiving such an activation message or communication, the central server establishes and activates a geo-fence around the vehicle based on its current position. Upon receiving a deactivation message or communication, the central server deactivates the geo-fence. In this manner, a driver or other individual can control, activate, deactivate, and configure the geo-fence even when he or she is not at the same physical location as the vehicle. 
     By establishing a geo-fence based on current asset position, the present invention provides much greater reliability as compared with prior art systems. The possibility of user error in specifying the geo-fence is reduced, since the geo-fence boundary is automatically determined rather than manually entered. Geo-fences can be established with much finer granularity, since there is no need to encompass an entire parking lot or other location defined in terms of an address; thus small movements of the asset can be detected and response time can be improved. In addition, the present invention provides mechanisms for passively initiating a geo-fence, for example when a vehicle has been parked or under other conditions, with a minimum of burden on the user/driver. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an overall architecture for an embodiment of the invention. 
         FIG. 2  is a flow diagram depicting an overall method of activating a geo-fence according to an embodiment of the present invention. 
         FIG. 3  is a flow diagram depicting a method of establishing a geo-fence based on a current vehicle position, according to an embodiment of the present invention. 
         FIG. 4  is a flow diagram depicting a method of responding to a geo-fence violation, according to an embodiment of the present invention. 
         FIGS. 5A through 5E  depict an example of a sequence of activating a geo-fence and responding to a geo-fence violation, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In one embodiment, the present invention includes or interfaces with location tracking functionality as described in related to U.S. patent application Ser. No. 11/539,292 for “STARTER-INTERRUPT DEVICE INCORPORATING GLOBAL POSITIONING SYSTEM FUNCTIONALITY”, filed Oct. 6, 2006, the disclosure of which is incorporated herein by reference. One skilled in the art will recognize that the present invention can be implemented with or without such location tracking functionality. 
     For illustrative purposes, the description provided herein sets forth the invention in the context of vehicles. However, one skilled in the art will recognize that the invention can be used in connection with any product. 
     For purposes of the following description, “vehicle owner”, “owner”, and “user” are synonymous and can refer to any individual who is interacting with the components of the present invention. 
     Referring now to  FIG. 1 , there is shown a block diagram depicting an overall architecture for an embodiment of the invention. 
     According to one embodiment onboard device  111  is installed in vehicle  109 . Onboard device  111  can be pre-installed or can be an add-on component. In one embodiment, onboard device  111  is connected to vehicle starter circuitry  112  so as to provide the ability to selectively disable vehicle  109  in the event of a geo-fence violation. This connection is optional, and is not an essential characteristic of the invention. 
     Onboard device  111  includes processor  115  which performs various functions in connection with the operation of the invention. Bluetooth, RFID or RF interface  113  detects signals from portable device  116  (such as a key fob, cellular telephone, or some other device) held by vehicle owner  110 . Interface  113  can take any known form for detecting the presence or absence of portable device  116 . In one embodiment, as described in more detail below, a geo-fence can be activated in response to the absence of portable device  116 , so that the invention activates the geo-fence when owner  110  parks vehicle  109  and walks away. 
     Onboard device  111  also includes Global Positioning System (GPS) module  114 , which uses well-known techniques for determining the position of vehicle  109  by communication with satellites. In one embodiment, GPS module  114  is external to onboard device  111 , so that onboard device  111  operates in connection with separate GPS hardware that may be installed in vehicle  109 . 
     Wireless network interface  120  communicates via wireless network  105  or by some other means with operations center  101 . Wireless network  105  may be any conventional cellular network, pager network, or other mechanism for transmitting information between vehicle  109  and operations center  101 . In one embodiment, operations center  101  includes wireless network interface  106  facilitating communication via network  105 . 
     Operations center  101  contains various components for implementing the present invention. In one embodiment, operations center  101  is situated at some central location. Appropriate communications infrastructure, such as Internet, wireless, and/or telecommunications connectivity is provided, so as to allow operations center  101  to communicate with other elements of the overall system. 
     Processor  102  at operations center  101  performs many of the functions of the present invention, including controlling the operation of various components of operations center  101 . Mapping module  116  performs mapping functions associated with the present invention, including for example determining vehicle  109  movement outside an activated geo-fence, as described in more detail below. 
     Processor  102  also includes administrator user interface  103  allowing system administrator  104  to control and configure the operation of the system. Processor  102  also includes owner user interface  104  allowing owner  110  to interact with the system, for example to specify conditions in which a geo-fence should be activated, and to specify the type of alerts to be issued in the event of geo-fence boundary violations. As described in more detail below, vehicle owner  110  can also directly activate and/or con figure 117  the system via user interface  104 . 
     Operations center  101  issues geo-fence violation alerts  107  under certain conditions, such as when a geo-fence is active and vehicle  109  position is outside the geo-fence. Geo-fence violation alerts  107  can be transmitted using any known communications medium, including email, SMS, instant message, automated telephone call, or the like. 
     Referring also to  FIG. 2 , there is shown a flow diagram depicting an overall method of activating a geo-fence according to an embodiment of the present invention. Referring also to  FIGS. 5A through 5E , there is shown an example of a sequence of activating a geo-fence and responding to a geo-fence violation, according to an embodiment of the present invention. As mentioned above, the invention is described in connection with a technique for activating a geo-fence for a vehicle; however, one skilled in the art will recognize that the invention can be used in connection with any asset, and is not limited to operation with a vehicle. 
     As shown in  FIGS. 5A and 5B , owner  110  parks  201  vehicle  109 . Owner  110  locks  202  vehicle  109 . The locking step  202  is optional, and can be omitted. Geo-fence  501  is activated  203 . In one embodiment, activation  203  of geo-fence  501  takes place automatically in response to vehicle  109  being locked  202 . In another embodiment, activation  203  takes place automatically in response to some other trigger event, such as detection that a portable device  116  carried by owner  110  has been moved away from vehicle  109 . Proximity of portable device  116  to vehicle  109  can be detected by known techniques that are used for remote keyless entry systems, such as by detecting the presence or absence of a radio frequency signal with a designated, distinct digital identity code associated with a particular portable device  116 . In one embodiment, interface  113  located in vehicle  109  (either as part of onboard device  111  or as a separate component) detects the presence or absence of portable device  116 . 
     In another embodiment, activation  203  takes place automatically in response to any other trigger event, including but not limited to: the engine being turned off; the key being removed from the ignition; detection that the vehicle has not moved in some period of time; detection that the vehicle is in a particular location; or the like. 
     In another embodiment, activation  203  takes place in response to an explicit activation command or operation. For example, owner  110  can press a button on portable device  116  initiating activation  203  of geo-fence  501 . Alternatively, owner  110  can press a button on onboard device  111 , enter a code on a keypad in vehicle  109 , or send a text message, email message, instant message, or other communication directly to operations center  101 . Alternatively, owner  110  can visit a website, log in using an authentication mechanism, and indicate that geo-fence  501  should be activated; the website can communicate this command to operations center  101 . 
     In another embodiment, activation  203  takes place at some preset time of day, such as for example between 11 pm and 6 am, unless countermanded by owner  110 . 
     One skilled in the art will recognize that many other trigger events, operations, and mechanisms for initiating activation  203  of geo-fence  501  can be used. 
     Referring also to  FIG. 3 , there is shown a flow diagram depicting a method of establishing a geo-fence  501  based on a current vehicle  109  position, according to an embodiment of the present invention. Trigger event occurs  301 , whether automatic or manual. The system determines  302  the current position of vehicle  109 , for example by well-known GPS techniques using GPS module  114 . Then, based on the current position and other settings and parameters, the system establishes  303  geo-fence  501 . 
     In one embodiment, the present invention avoids the need for owner  110  or any other individual to manually specify the parameters, bounds, size, or shape of geo-fence  501  or the region defined by geo-fence  501 . Rather, geo-fence  501  is established  303  based on the current position of vehicle  109  and, optionally, other factors. For example, in one embodiment, geo-fence  501  is established as a region centered around the current position of vehicle  109  and having a radius according to some predetermined configuration parameter. In one embodiment, geo-fence  501  can have different shape, size, or characteristics depending on various factors, such as but not limited to: owner-defined preferences; system-wide settings; administrator-defined preferences; current location of vehicle  109 ; geographic considerations; and the like. 
       FIG. 5D  depicts vehicle  109  with geo-fence  501  established and active. In one embodiment, geo-fence  501  is established by processor  115 ; specifically, vehicle  109  position is determined by signals from GPS module  114 , and processor  115  establishes a radius according to some predetermined configuration parameter. In another embodiment, geo-fence  501  is established by operations center  101 ; specifically, vehicle  109  position is determined by signals from GPS module  114  sent to the operations center  101  via wireless network  105 , and processor  102  establishes a radius according to some predetermined configuration parameter. In one embodiment, once geo-fence  501  has been established, the system of the present invention periodically or continuously monitors  304  vehicle  109  position with respect to geo-fence  501 . In one embodiment, position monitoring is performed by periodic signals from GPS module  114  to operations center  101  via wireless network  105 , so that processor  102  can compare current vehicle  109  position with geo-fence  501  to detect geo-fence violations. In another embodiment, the system of the present invention transmits geo-fence  501  information to vehicle  109  so that a geo-fence violation can be detected locally by onboard device  111  at vehicle  109 . Thus, the specific parameters of geo-fence  501  can be stored at operations center  101 , or at vehicle  109 , or at both locations. 
     In some embodiments, the system can be configured to receive periodic transmissions from onboard device  111  even when no geo-fence violation has taken place, so that if onboard device  111  is disabled or inoperative, the lack of transmissions can cause an alert to be issued to indicate a possible geo-fence violation. Thus, a thief cannot disable the system by tampering with or destroying onboard device  111 . 
     Referring now to  FIG. 4 , there is shown a flow diagram depicting a method of responding to a geo-fence violation, according to an embodiment of the present invention.  FIG. 5E  depicts a geo-fence violation, where vehicle  109  is leaving the area defined by geo-fence  501 , for example if it is being stolen. The geo-fence violation is detected  401  in one of several ways. In one embodiment, onboard device  111  has access to the parameters of geo-fence  501  and detects the current position of vehicle  109  via GPS module  114 ; if the current position is outside geo-fence  501 , onboard device  111  sends a signal to operations center  101  via wireless network  105  or by some other means. In another embodiment, the parameters of geo-fence  501  are stored at operations center  101 , and onboard device  111  periodically sends a signal with vehicle  109  position to operations center  101  (or sends a signal when its current location has changed by more than some predetermined amount); the comparison between vehicle  109  position and geo-fence  501  takes place at operations center  101  rather than at vehicle  109 . 
     When a geo-fence violation is detected  401 , operations center  101  issues one or more alerts according to predefined settings and preferences. For example, operations center  101  can transmit a geo-fence violation alert  107  to owner  110  and/or to an external agent  108  such as a local police department. Transmission of alert  107  can take place across any known communication channel or channels, including for example: a telephone call, an email message, an SMS message, an instant message, or the like. Alert  107  to external agent  108  can be sent over police radio or other mechanisms, if desired. Additional information, such as current vehicle location, speed, description, or the like, can also be transmitted as part of alert  107  so as to assist in recovery of vehicle  109 . 
     In this manner, the system of the present invention provides a mechanism by which vehicle theft can be quickly detected, and appropriate action can be taken promptly. 
     In one embodiment, onboard device  111  is optionally connected to vehicle starter circuitry  112  so that vehicle  109  can be disabled when a geo-fence violation is detected. Accordingly, based on predefined parameters and/or in response to a command from administrator  104  or owner  110 , onboard device  111  can disable vehicle  109 . A signal to disable vehicle  109  can be sent from operations center  101  to vehicle, for example via wireless network  105 . Alternatively, onboard device  111  can disable vehicle  109  based on local determination of a geo-fence violation, such as in a configuration where geo-fence parameters are stored locally at onboard device  111  in vehicle  109 . 
     The particular conditions in which the vehicle is disabled can be configured in advance by owner  110 , or by administrator  104 , or by some other party. Alternatively, in one embodiment, when a geo-fence violation alert  107  is received by owner  110  or by external agent  108 , the owner  110  or external agent  108  can be given an opportunity to indicate whether vehicle  109  should be immediately disabled. If feasible and if owner  110  or external agent  108  requests disablement, a signal can be sent to onboard device  111  to disable vehicle  109 . 
     Use Cases 
     Several embodiments can be implemented using the above-described architecture and methods, and variations thereof. The following are three examples of specific use cases including descriptions of specific technologies, protocols and methodologies. 
     Passive Device-Based Geo-Fence 
     A communication link such as Bluetooth or RFID is established between a portable device  116  (such as a key fob, cellular telephone, or other device) carried by owner  110  and onboard device  111 . When onboard device  111  no longer detects the presence of portable device  116 , onboard device  111  establishes a geo-fence. For example, processor  115  can calculate geo-fence coordinates based on a predefined boundary rule stored in processor  115 . Alternatively, onboard device  111  can send a message via wireless network  105  to operations center  101  to initiate activation of a geo-fence to lock down vehicle  109  movement. Upon receiving the message, operations center  101  performs a GPS locate for vehicle  109  and calculates geo-fence coordinates based on a predefined boundary rule. Operations center  101  sends a message over wireless network  105  to onboard device  111  including the established geo-fence coordinates. Onboard device  111  is then able to detect geo-fence violations. 
     If vehicle  109  violates an active geo-fence by leaving the defined region, a boundary violation message is sent over wireless network  105  to operations center  101 . Upon receiving the boundary violation message, operations center  101  executes a “Boundary Violation Routine” which sends out boundary violation messages based on a notification rule set for the particular vehicle  109 . This may result in notifications to owner  110  and/or external agent  108 , as well as possibly sounding a local alarm, and/or disabling vehicle  109 . 
     When onboard device  111  re-establishes connection with portable device  116 , onboard device  111  deactivates the programmed geo-fence, allowing vehicle  109  to be moved without triggering a boundary violation. 
     Active Device-Based Geo-Fence 
     Owner  110  presses an “activate” button or enters a code on a portable device  116  (such as a key fob or other device such as a cellular telephone). This causes a signal to be sent, for example via Bluetooth or RFID, to onboard device  111 , indicating that a geo-fence should be established. For example, processor  115  can calculate geo-fence coordinates based on a predefined boundary rule stored in processor  115 . Alternatively, onboard device  111  can send a message via wireless network  105  to operations center  101  to initiate activation of a geo-fence to lock down vehicle  109  movement. Upon receiving the message, operations center  101  performs a GPS locate for vehicle  109  and calculates geo-fence coordinates based on a predefined boundary rule. Operations center  101  sends a message over wireless network  105  to onboard device  111  including the established geo-fence coordinates. Onboard device  111  is then able to detect geo-fence violations. 
     If vehicle  109  violates an active geo-fence by leaving the defined region, a boundary violation message is sent over wireless network  105  to operations center  101 . Upon receiving the boundary violation message, operations center  101  executes a “Boundary Violation Routine” which sends out boundary violation messages based on a notification rule set for the particular vehicle  109 . This may result in notifications to owner  110  and/or external agent  108 , as well as possibly sounding a local alarm, and/or disabling vehicle  109 . 
     Owner  110  presses a “deactivate” button or enters a code on a portable device  116 . Onboard device  111  deactivates the programmed geo-fence, allowing vehicle  109  to be moved without triggering a boundary violation 
     In one embodiment, the activate signal may be sent automatically when owner  110  locks vehicle  109  via portable device  116  (such as a key fob), and the deactivate signal may be sent automatically when owner  110  unlocks vehicle  109  via portable device  116 . 
     Active Cellular-Based Geo-Fence 
     Owner  110  sends an SMS, text, instant message, or email message from an appropriately enabled device (such as a cellular telephone or PDA) directly to operations center  101  indicating that a geo-fence should be established. This message can be sent when owner  110  is at the vehicle or from any other location. 
     Upon receiving the message, operations center  101  performs a GPS locate for vehicle  109  and calculates geo-fence coordinates based on a predefined boundary rule. Operations center  101  sends a message over wireless network  105  to onboard device  111  including the established geo-fence coordinates. Onboard device  111  is then able to detect geo-fence violations. 
     If vehicle  109  violates an active geo-fence by leaving the defined region, a boundary violation message is sent over wireless network  105  to operations center  101 . Upon receiving the boundary violation message, operations center  101  executes a “Boundary Violation Routine” which sends out boundary violation messages based on a notification rule set for the particular vehicle  109 . This may result in notifications to owner  110  and/or external agent  108 , as well as possibly sounding a local alarm, and/or disabling vehicle  109 . 
     Owner  110  sends an SMS, text, instant message, or email message from an appropriately enabled device (such as a cellular telephone or PDA) directly to operations center  101  to deactivate the geo-fence. Again, this message can be sent when owner  110  is at the vehicle or from any other location. Operations center  101  sends a message over wireless network  105  to onboard device  111  to deactivate the geo-fence. Onboard device  111  deactivates the programmed geo-fence, allowing vehicle  109  to be moved without triggering a boundary violation. 
     One skilled in the art will recognize that the above-described examples of use cases are intended to be illustrative, rather than limiting, of the scope of the claimed invention. In addition, the use cases can be combined, so that activation by one mechanism can be followed by deactivation by another mechanism. For example, the geo-fence can be established via the active cellular-based method, and subsequently deactivated by the passive device-based method. 
     The above description includes various specific details that are included for illustrative purposes only. One skilled in the art will recognize the invention can be practiced according to many embodiments, including embodiments that lack some or all of these specific details. Accordingly, the presence of these specific details is in no way intended to limit the scope of the claimed invention. 
     In the specification, certain components of the invention may be described in terms of algorithms and/or steps performed by a software application. In many cases, such descriptions are intended to set forth the invention using representations that are commonly used among those of skill in the arts. Accordingly, any descriptions that refer to algorithms, method steps, functional components, and the like, shall be considered to encompass electrical, magnetic, optical, and/or mechanical signals representing such algorithms, method steps, functional components, such signals being capable of being stored, transmitted, input, output, and/or otherwise manipulated. Reference to these signals as variables, bits, symbols, values, and the like may appear herein and is not intended to limit the scope of the claimed invention in any way. 
     All such terms, and any similar terms, are to be considered labels only, and are intended to encompass any appropriate physical quantities or other physical manifestations. Any particular naming or labeling of the various modules, protocols, features, and the like is intended to be illustrative; other names and labels can be used. 
     In addition, various terms such as “processing”, “calculating”, “determining”, “transmitting”, or the like, may be used herein. Such terms are intended to refer to processes performed by a software and/or hardware device such as a computer system. Such terms refer to various types of manipulation and/or transformation of physical and/or electronic components such as registers and memories within the device. These physical and/or electronic components typically represent data elements to be transformed, transmitted, and/or output. 
     Furthermore, the invention can be implemented as a method, system, computer program product, user interface, or any combination thereof. 
     The present invention also relates to a system for performing various steps and operations as described herein. This system may be a specially-constructed device such as an electronic device, or it may include one or more general-purpose computers that can follow software instructions to perform the steps described herein. Multiple computers can be networked to perform such functions. Software instructions may be stored in any computer readable storage medium, such as for example, magnetic or optical disks, cards, memory, and the like. 
     The method steps, user interface layouts, displays, and other components described herein can be implemented on any computer, network, or other apparatus capable of performing the functions described. No limitation as to operation on a particular type of system or apparatus is implied. No particular programming language is required; rather, any type of programming language can be used to implement the present invention. 
     References to “one embodiment” or “an embodiment” indicate that a particular element or characteristic is included in at least one embodiment of the invention. Although the phrase “in one embodiment” may appear in various places, these do not necessarily refer to the same embodiment. 
     One skilled in the art will recognize that the invention can be practiced according to many embodiments other than those described herein, without departing from the essential characteristics of the present invention. The particular descriptions set forth above are intended to be illustrative examples only, and are not intended to limit the scope of the invention.

Technology Category: b