Abstract:
A mobile device communicates with an authenticator affiliated with a recharging facility, to identify itself. To confirm that the mobile device is connected to the correct facility, the authenticator instructs the mobile device to draw electrical charge according to an identifiable pattern. Upon detecting a charge being drawn according to that pattern, the authenticator has confirmation that the identified device is connected to the facility, and permits the charging to proceed. The amount of electricity drawn during the charging procedure can be metered, and then billed to a party associated with the identified mobile device.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation application of application Ser. No. 13/362,416, filed Jan. 31, 2012. The entire content of this application is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present disclosure relates generally to systems and methods for authentication of mobile devices and, more particularly, to the authentication of a mobile electric device using a charging pattern of the mobile device. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many different electronic and mechanical devices include battery storage, which arc connected to the electric utility grid for recharge. Generally, costs for the energy used to recharge such mobile devices are assessed to the owner or provider of the outlet used for charging the mobile device, and are billed based on meter reading at the owner&#39;s meter associated with the outlet used for charging. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    In accordance with embodiments disclosed herein, the cost associated with the recharging of a mobile device can be allocated to the owner of the device, rather than the premises where the outlet is located, through a procedure for authenticating the device owner at the time of recharging the device. The mobile device communicates with an authenticator affiliated with the recharging facility, to identify itself. To confirm that the mobile device is connected to the correct facility, the mobile device draws a charge according to a pattern that is recognized by the authenticator. Upon detecting a charge being drawn according to that pattern, the authenticator has confirmation that an identified device is connected to the facility, and permits the recharging to proceed. The amount of electricity drawn during the recharging procedure can be metered, or otherwise determined and then billed to a party associated with the identified mobile device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0005]    The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
           [0006]      FIG. 1  is a schematic diagram illustrating a system for authenticating a pairing of a power source and mobile device in accordance with an exemplary embodiment of the present invention; 
           [0007]      FIG. 2  is a flowchart illustrating a method of authentication of a mobile device in accordance with a first exemplary embodiment; 
           [0008]      FIG. 3  is a graph illustrating a load pattern used in systems and methods in accordance with exemplary embodiments of the present invention; 
           [0009]      FIG. 4  is a timing diagram illustrating communications between or among a mobile device and authenticators in accordance with a second exemplary embodiment; 
           [0010]      FIG. 5  is a flowchart illustrating a method of managing a charging session in accordance with the second exemplary embodiment; 
           [0011]      FIG. 6  is timing diagram illustrating communications between or among a mobile device and authenticators in accordance with a third exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Mobile electric devices such as plug-in electric cars, laptop computers, notebook computers, PDAs, and cell phones, among others, are proliferating with the advent of a more mobile society. The ability to recharge such devices may be limited to electrical outlets associated with an owner of the mobile electric devices (e.g., where the billing account associated with electrical outlet and the owner of the mobile device are the same entity) or where the billing account owner associated with the electrical outlet allows the owner of the mobile device to recharge the mobile device at no charge. The owner associated with an electrical outlet generally refers to the individual or entity who is financially obligated to pay for the electricity consumed at the electrical outlet, which may include the owner of the electrical outlet or a third party responsible for such payments. 
         [0013]    In various exemplary embodiments, a mobile electronic device may be authenticated to the electrical outlet, power connection or power source used for charging. By authenticating to such an outlet, power connection or power source, the billing account associated with the mobile device may be billed for the cost of recharging of the mobile device. 
         [0014]    In certain exemplary embodiments, an authenticator may negotiate or specify a load pattern used by the mobile electronic device to identify its pairing with the electrical outlet, the power source or the power connection. 
         [0015]    To facilitate an understanding of the concepts that underlie the invention, exemplary embodiments are described in which the mobile device is a plug-in electric vehicle. It will be appreciated, however, that the mobile electric device may be any device which is mobile and capable of recharge from any power source such as the electric grid, a generator, or another mobile device, among others. 
         [0016]      FIG. 1  is a schematic diagram illustrating a system  100  for authenticating a pairing of a power source  122   a  and mobile electrical device  110  in accordance with exemplary embodiments disclosed herein. Referring thereto, system  100  may include mobile electric device  110 , first electric supply site  120   a,  second electric supply site  120   b,  first authenticator  130   a,  second authenticator  130   b  and electric grid  140 . The apparatus and functions associated with first electric supply site  120   a  are substantially the same as those of second electric supply site  120   b.    
         [0017]    First electric supply site  120   a  may include first power source  122   a  and first connector  124   a.  First electric power source  122   a  may be connected to utility grid  140  for supply of electric power to first connector  124   a,  or may be a stand alone power source for generating electrical power. 
         [0018]    Although first electric power supply  122   a  is shown connected to electric grid  140 , it is contemplated that any power source may be used, including both alternating current (AC) and direct current (DC) power sources such as batteries, fuel cells, photovoltaics, and electric generators, among others. First electric power source  122   a  may include a meter/sensor  126   a  and a load switch  128   a.    
         [0019]    Meter/sensor  126   a  may measure current draw through first electric power source  122   a.  Meter sensor  126   a  may be coupled to first authenticator  130   a.  First authenticator  130   a  may be located at the first electric supply site or may be located remotely, for example, in a vicinity of a plurality of electric metering sites or in the vicinity of back office  150 . 
         [0020]    Although first authenticator  130   a  is shown coupled to meter/sensor  122   a,  it is contemplated that first authenticator  130   a  may be coupled to any number of meters/sensors to measure the charge (e.g., current) drawn at a plurality of electric meter sites for authentication of the electrical outlets, power sources or power connections with mobile devices. In certain exemplary embodiments, one authenticator may measure charge drawn from electric meter sites associated with a specified geographic area (e.g., a parking lot, a plurality of parking spots, or a recharging center, among others). In other exemplary embodiments, such an authenticator may be associated with or located at back office  150  and may measure charge draw associated with electric meter sites associated with back office  150 . 
         [0021]    Load switch  128   a  may be controlled by first authenticator  130   a  to connect or disconnect electric utility grid  140  or power source  120   a  from mobile device  110 . Although load switch  128   a  is shown to connect or disconnect power entirely to/from mobile device  110 , it is contemplated that load switch  128   a  may only connect or disconnect a portion of the load of mobile device  110  (e.g., charging circuits of mobile device  110 ) from power source  122   a  or electric utility grid  140 . For example, electric meter site  120   a  may continue to enable power supply to mobile device  110  for functions such as communications with first authenticator  130   a  and other processing functions of mobile device  110  using a low power connection via first connector  124   a.    
         [0022]    Although load switch  128   a  is shown as a single-pole single-throw switching device, it is contemplated that load switch  128   a  may include other configurations to connect or disconnect other connections including, for example a ground connection, a communications connection, and/or a presence detection circuit, among others. 
         [0023]    First authenticator  130   a  may include a current sensor  131   a,  a controller  132   a,  a transceiver  134   a,  a memory  136   a  and an antenna  138   a.  Mobile device  110  may include a network interface  112  having a controller  114 , transceiver  116 , memory  118 , and antenna  119 . Controller  132   a  and controller  114  may establish a communication session (e.g., an internet protocol (IP) session) via transceiver  134   a  and antenna  138   a  of first authenticator  130   a  and transceiver  116  and antenna  119  of network interface  112 . Controller  132   a  may receive information (including measurements, meter readings and/or sensor readings, among others) from meter/sensor  126   a  of first electric metering site  120   a.  First connector  124   a  of first electric metering site  120   a  may connect to connector  115  of mobile device  110  to electrically connect power source  122   a  and/or utility grid  140  to mobile device  110 . 
         [0024]    Although a converter is not shown in  FIG. 1 , mobile device  110  may include a converter to convert AC power to DC power. It is also contemplated that such a converter may be disposed between utility grid  140  and mobile device  110 . 
         [0025]    System  100  may include back office  150  in communication with a plurality of authenticators (e.g., first and second authenticators  130   a  and  130   b ) via communication network  160 . Back office  150  may include a controller  152 , a transceiver  154 , and a memory  155  (e.g., including authentication tables  156 ). Controller  152  may control the operation of back office  150 . Transceiver  154  may receive and send information via communication network  160  to first and/or second authenticators  130   a  and  130   b.  Memory  155  may include data structures used to uniquely identify load patterns monitored by first or second authenticator  130   a  or  130   b  with a mobile device identifier. Authentication tables  156  may include account and billing information associated with mobile devices in system  100 . 
         [0026]    In one embodiment, authentication tables  150  may include records having unique identifiers associated with each mobile device. When mobile device  110  connects to first electric metering site  120   a  via first connector  124   a,  first authenticator  130   a  may monitor for a current draw at first connector  124   a.  The current draw may have a unique load pattern that identifies mobile device  110 . For example, network interface  112  may have a media access control (MAC) address (e.g., a unique address) that is associated with network interface  112 . The MAC address may be encoded as a unique load pattern associated with mobile device  110 . 
         [0027]    In an alternate embodiment, rather than employ a public address or the like as the identifier of the mobile device, a secure value, such as a secret key, that is stored at both the authenticator and the mobile device can be employed as the unique identifier of the mobile device. Furthermore, the same identification credentials can be employed by a group of users. For instance, all of the members of a family who charge to the same billing account can share the secret key, and use it to identify their mobile devices to the authenticator. In a similar manner, a group address or other such form of shared credential can be employed to identify, and authenticate, all of the members of a group. 
         [0028]    First authenticator  130   a  may monitor for the unique load pattern of mobile device  110  and may authenticate the pairing of mobile device  110  with the first electric metering site  120   a  (and/or first power source  122   a ) in response to the unique load pattern being detected. First authenticator  130   a  may continuously monitor first electric metering site  120   a  via meter/sensor  126   a  to determine current draw from connector  124   a.  First authenticator  130   a  may determine the start of a unique load pattern based on current draw at first connector  124   a  which is below a threshold level for a specified period of time (e.g., for greater than one minute) followed by a series of loads (the load pattern) which exceeds the threshold level during at least a portion of an authentication period. 
         [0029]    First authenticator  130   a  may determine an end to the unique load pattern based on the same or similar criteria as the start of the unique load pattern. That is, during the unique load pattern, load may exceed a threshold level to generate a sequence of load values above and below a load reference value, which will dynamically change based on at least a unique identifier of mobile device  110  (e.g., based on a MAC address, a unique identifier, or some other predetermined unique identifier of mobile device  110  and associated with network interface  112 ). First authenticator  130   a  may request validation from back office  150  using authentication tables  156  to validate the unique load pattern of mobile device  110 . For example, controller  132   a  may convert the unique load pattern detected from meter/sensor  126   a  to a digital code and may request validation of the converted code from back office  150 . 
         [0030]    Back office  150  may validate the converted code from first authenticator  130   a  and may provide a message indicating the authentication of mobile device  110 . Controller  132   a  of first authenticator  130   a,  upon receiving the message authenticating mobile device  110 , may control load switch  128   a  to maintain a connection between power source  122   a  and mobile device  110 . 
         [0031]    In certain exemplary embodiments, first authenticator  130   a  may include memory  135   a  for storing program code executable by controller  132   a  and for storing information sent from authentication tables  156  for local authentication. For example, once mobile device  110  is authenticated (e.g., paired) with first electric metering site  120   a,  authentication information associated with mobile device  110  (e.g., the unique load pattern of mobile device  110 ) and an identifier included in authentication tables  156  to identify mobile device  110  may be stored locally in memory  135   a  of first authenticator  130   a,  such that first authenticator  130   a  may authenticate the same mobile device in a subsequent authentication process (without back office  150 ) based on rules established by back office  150  (e.g., when the planned current draw by mobile device  110  is below a threshold, when mobile device is of a certain type (e.g., a laptop, a PDA, a cell phone, or a plug-in vehicle) or may be set as a flag in memory  135   a  from back office  150  based on criteria set by back office  150 ). 
         [0032]    Mobile device may include an energy storage unit  170  and a energy management device  180 . Energy management device  180  may include a controller  182  and a metering unit  184 . Controller  182  of energy management device  180  may control charging and discharging of energy storage unit  170  to power, for example, mobile device  110 . 
         [0033]    In certain exemplary embodiments, the energy management device  180  may be integral to a vehicle management system. In other exemplary embodiments, the energy management device  180  may be separate from and in communications with the vehicle management system. 
         [0034]      FIG. 2  is a flowchart of the pairing authentication in accordance with the first embodiment. At step  210 , mobile device  110  is connected to a power source (e.g., first electric metering site  120   a ). At step  215 , mobile device  110  may initiate a sequence of charge draws. At step  220 , first authenticator  130   a  may determine whether a predetermined time has elapsed since the connection of mobile device  110  to first electric metering site  120   a.  At step  225 , responsive to the predetermined time being exceeded, mobile device  110  may be disconnected from first electric metering site  120   a  via load switch  122   a,  At step  230 , responsive to the predetermined time not being exceeded, first authenticator  130   a  may monitor for the sequence of charge draws. At step  235 , first authenticator  130   a  may determine whether the identity of mobile device  110  is recognizable from the sequence of charge draws. For example, first authenticator  130   a  may match the sequence of charge draws with a unique identifier of mobile device  110 . In certain exemplary embodiments, the unique identifier of mobile device  110  may be stored in authentication tables  158  of back office  150 . In such exemplary embodiments, first authenticator  130   a  may request via communication network  160  authentication information stored in authentication tables  158 . The request for authentication information may be sent via transceiver  134   a  of first authenticator  130   a,  communication network  160  and transceiver  154  of back office  150 . In alternate exemplary embodiments, first authenticator  130   a  may include authentication tables (not shown) for authentication locally (without communication with back office  150 ). 
         [0035]    In other alternative exemplary embodiments, first authenticator  130   a  may send a logical series of bits corresponding to the sequence of charge draws to back office  150  via communication network  160  and back office  150  may determine and direct first authenticator  130   a  regarding the recognition of the identity of the mobile device from the sequence of charge draws. Responsive to the first authenticator  130   a  and/or back office  150  not recognizing the identity of the mobile device from the sequence of charge draws, processing is sent to step  220  to determine whether a predetermined amount of time has elapsed since connection by mobile device  110 . If the predetermined amount of time has elapsed, the mobile device is disconnected at step  225 , to thereby prevent a rogue device from continuing to draw current via the authentication process. 
         [0036]    Responsive to first authenticator  130   a  and/or back office  150  recognizing the identity of the mobile device from the sequence of charge draws, back office  150  may validate at step  240  whether the recognized mobile device has permission to draw power. For example, back office  150  may correlate the recognized identity of mobile device  110  with a billing account and it may determine, based on billing activity, payment terms, arrearages, among others, whether to permit the draw of power. If the back office does not permit the draw of power, back office  150  may send a message to first authenticator  130   a  to block a charging session. For example, first authenticator  130   a  may control load switch  128   a  to disconnect mobile device  110 , at step  245 . At step  250 , responsive to the recognized mobile device having permission to draw power, the first authenticator  130   a  may authenticate mobile device  110  and initiate a charge session. At step  255 , first authenticator  130   a  may determine whether a predetermined time has elapsed since the beginning of the charge session. Responsive to the predetermined time having elapsed, mobile device  110  may be disconnected from first electric metering site  120   a  using load switch  128   a.  Responsive to the predetermined time not having elapsed, first authenticator  130   a  may monitor for an indication that the charge session has ended. For example, first authenticator  130   a  may monitor for a current draw below a threshold level for a specified period to indicate the end of a charge session. 
         [0037]    If the end of a charge session is indicated, first authenticator  130   a  may control load switch  128   a  to disconnect mobile device  110  at step  265 . If the end of a charging session is not indicated by the monitored charge draw, at step  260 , processing is transferred to step  255  to determine if a predetermined time has elapsed since the beginning of the charge session. 
         [0038]      FIG. 3  is a graph of one example of a possible load pattern. The graph includes load history  310  and filtered data  320  which corresponds to load history data with high frequency components (e.g., components above a threshold frequency) removed. The load history represents a series of load patterns provided by mobile device  110 . Prior to sending its unique identification, the mobile device may first draw current according to a generic pattern that indicates an intent to draw power, during an initial period  340 . The load pattern during the initial period  340  may indicate that mobile device  110  is connected to the utility grid via first electrical metering site  120   a,  and alerts the authenticator  130   a  to begin looking for a load pattern that indicates a unique identifier. Thereafter, the mobile device  110  sends its identifier during an authentication period  350 . The load pattern associated with mobile device  110  presents a binary pattern  330  that is derived from filtered data  320 . 
         [0039]    In response to detection and authentication of a specified load pattern, the first authenticator  120   a  may enable the initiation of a charging period  360 . If a valid load pattern is not detected, the first authenticator  120   a  may control the load switch  128   a  to open and disconnect the mobile device from the external power source. That is, the first authenticator  120   a  blocks charging of the mobile device  110 . 
         [0040]    In one implementation of the first embodiment, the unique identifier of the mobile device may be a secret that is shared between the mobile device and the authenticator, rather than being transmitted in the clear. For example, each of the authenticator and the mobile device may store an algorithm that is seeded by the identifier of the mobile device and an identifier of the authenticator, such as its MAC address. When the mobile device initiates the generic load pattern during the initial period  340 , the authenticator can respond with its identifier, by varying any parameter of the power that is capable of being detected by the mobile device. For instance, the authenticator may cause the power source  122   a  to vary the voltage, phase or current of the power, or simply turn the power on and off, so as to encode the identifier in the power received via the connectors  115  and  124   a.  In response to receiving this identifier, the mobile device can execute the algorithm, using the received identifier and its own unique identifier as inputs, to obtain a result value. This result value is sent to the authenticator during the authentication period. Applying an inverse of the algorithm to the received result value, the authenticator can then derive the unique identifier of the mobile device. This derived identifier can then be checked against the table of authorized identifiers to authenticate the mobile device. 
         [0041]    In the first embodiment described above, the communication between the mobile device and the authenticator are carried out via the power line connection, through current draws or other forms of modulation of the power delivered to the mobile device. In a second embodiment described hereinafter, wireless RF communication can be employed to transmit at least some of the information that is exchanged between the mobile device and one or more authenticators. 
         [0042]    Now referring to  FIG. 4 , at step  410 , when the mobile device  110  is plugged into a power outlet, it may broadcast a message to authenticators within operational range (e.g., authenticators  130   a  and  130   b ) via the network interface  112  and antenna  119 . The broadcast message may advertise an intent for mobile device  110  to charge. First authenticator  130   a  and second authenticator  130   b  may each send a response message to mobile device  110  to initiate a load pattern, at steps  420  and  430 , respectively. The load pattern may be specific to each authenticator, and/or a time stamp. Alternatively, the pattern may be specific to mobile device  110 , a fixed pattern, or portions of the load pattern may be a combination thereof. In certain exemplary embodiments, the load pattern may be based on a unique identifier of the mobile device  110  and may be obscured by hashing the unique identifier with a hash algorithm. 
         [0043]    Responsive to receiving one or more response messages from first authenticator  130   a  and second authenticator  130   b,  at step  440  mobile device  110  may determine which one of the authenticators in its operational range (e.g., first authenticator  130   a  or second authenticator  130   b ) to select for authentication. The selection of authenticator  130   a  or authenticator  130   b  may be based on the authenticator having the highest signal strength. Alternatively, or in addition, the mobile device may store a list of known addresses, and select an authenticator based on an address included in the responses from the authenticators. Mobile device  110  may draw charge according to the load pattern established with the selected authenticator (e.g., first authenticator  130   a ). 
         [0044]    Although first authenticator  130   a  and second authenticator  130   b  are shown in the timing diagram of  FIG. 4 , it is contemplated that more or fewer authenticators may be within operating range of mobile device  110  and each authenticator may send a response message and monitor for charge draw. In certain exemplary embodiments, the selection of the authenticator may be improper (i.e., mobile device  110  may choose an authenticator associated with an electric metering site not connected to mobile device  110 ).  FIG. 4  depicts a situation in which the mobile device  110  selects the second authenticator  130   b,  but it is connected to the power source associated with the first authenticator  130   a.  At step  450 , the authenticator which discovers a load draw after sending a response message to mobile device  110  (in this case authenticator  130   a ) may send a further response message to indicate to mobile device  110  that the authenticator has monitored a charge draw and also indicating the proper load pattern for the mobile device  110 . At step  460 , mobile device  110  may then determine the proper authenticator and draw charge according to the load pattern established with the proper authenticator. 
         [0045]    At step  470 , based on the monitoring at step  420 , first authenticator  130   a  (as the selected authenticator) determines that mobile device  110  is drawing charge according to the load pattern indicated in the response message at step  420 . First authenticator  130   a  may send an acknowledgment of the pairing of mobile device  110  with first electric metering site  120   a  and may enable the initiation of a charge session for mobile device  110  based on the detected load pattern (e.g., when responsive to the load pattern being detected). 
         [0046]    In certain embodiments the reselection of an authenticator may be eliminated if the load pattern is based on only the unique identification associated with mobile device  110 , such as a Mac address or other unique identifier. 
         [0047]    Now referring to  FIG. 5 , at step  510 , the charging system of mobile device  110  (e.g., a plug-in vehicle) may be prepared for charging. At step  520 , the mobile device&#39;s network interface (e.g., the plug-in vehicle&#39;s network interface card) may advertise to all authenticators (e.g., all meter network interface cards) stored in the mobile device&#39;s memory  117  (e.g., as a neighborhood table in memory  117 ) the plug-in vehicle&#39;s intent to charge. At step  525 , the mobile device&#39;s network interface receives acknowledgement from the neighboring NICs in response to the advertisement, indicating their readiness to detect a message. At step  530 , the charging system  111  of plug-in vehicle  110  may initiate a series of loading following a pattern indicative of third party electrical loads. At step  540 , neighboring meter network interface cards that acknowledge vehicle advertisement monitor the load registers of their respective meters at a predetermined interval. For example, the sampling interval for load registers associated with meters that may be used for charging the plug-in vehicle&#39;s charging system may be increased from a normal sample range of about  30  seconds to about five minutes, to a faster range of about five seconds to about one minute, depending on the metering unit  126   a  used. At step  550 , the neighboring meter network interface card may determine whether to acknowledge the load pattern. Responsive to the neighboring meter network interface controller  132   a  acknowledging the load pattern of the third party load, at step  570 , the load pairing of first electric metering site  120   a  and plug-in vehicle  110  are verified using any of the previously disclosed authentication processes. At step  560 , if the neighboring meter network interface controller does not acknowledge the load pattern of the third party load, the monitoring of the load registers of the neighboring meter (e.g., meter unit  126   a ) may resume normal operations. For example, the sampling interval of the meter registers may be adjusted to a normal interval. 
         [0048]    At step  575 , if the load pairing of the first electric metering site  120   a  and plug-in electric vehicle  110  is validated, the meter seal of the plug-in vehicle  110  is validated. At step  580 , if the load pairing is not verified at step  570 , the vehicle charging system is locked out. For example, the load switch  128   a  of first electric metering site  120   a  may be disconnected by meter network interface controller  132   a.  Further, if the meter seal of plug-in vehicle  110  is not validated, the vehicle charging system of plug-in vehicle  110  may be locked out at step  580 . If the meter seal of plug-in vehicle  110  is validated at step  575 , the back office determines whether the customer account associated with the plug-in vehicle is valid at step  585 . For example, the back office  150  may determine that the customer account has sufficient pre-paid funds or that a valid credit account is associated with the customer account. If the customer account is validated, the back office may send a charging commencement message to the meter network interface controller  132  to commence charging at step  590 . If the customer account is determined to be invalid by back office  150 , the back office may send an invalid account message to meter network interface controller  132   a  at step  580  to cause vehicle charging system of plug-in vehicle  110  to be locked out. 
         [0049]    In another embodiment, the mobile device may first attempt to discover potential hosts within its communication range. Referring to  FIG. 6 , at step  610 , mobile device  110  may broadcast a message to discover other communication nodes in operational range (e.g., one-hop nodes or neighboring nodes). For example, mobile device  110  may broadcast a message to first authenticator  130   a  and second authenticator  130   b.  Any neighboring node (authenticator) receiving the broadcast message directly from mobile device  110  may respond by sending a response message establishing the respective node (authenticator) as a neighboring or one-hop node. For example, at step  620 , first authenticator  130   a  may receive directly from mobile device  110  the broadcast message, and may reply with a response message indicating that authenticator  130   a  is a neighboring or one-hop node of mobile device  110 . This response may include instructions to initiate a general charge pattern. At step  630 , second authenticator  130   b  may receive the broadcast message directly from mobile device  110  and may send a response message with instructions to for a charge pattern, establishing second authenticator  130   b  as a neighboring or one-hop node as well. 
         [0050]    Mobile device  110  may receive the response messages from the authenticators which neighbor the mobile device. At step  640 , the mobile device may send a message to the established neighboring nodes that mobile device  110  is initiating a series of current draws. In certain exemplary embodiments the current draws may be below a threshold level and/or may be a predetermined/fixed series of charge draws that are generic to third-party connections. At step  650 , mobile device  110  may initiate a series of charge draws according to the instructed pattern, and at steps  660  and  670  first authenticator  130   a  and second authenticator  130   b  may monitor for the series of charge draws, respectively. In the example of  FIG. 6 , the mobile device is connected to the power source  122   a  associated with authenticator  130   a.  First authenticator  130   a,  upon detecting the current draw, may send an acknowledgment message instructing the mobile device to draw charge based on a unique, predetermined, specified, or negotiated load pattern and may monitor for charge draw according to the instructed load pattern, at step  680 . Mobile device  110  may receive the acknowledgment message and may draw charge according to the instructed load pattern, at step  690 . At step  695 , the authenticator may enable a charge session for mobile device  110  upon detection of the instructed load pattern and verification through the back office system. 
         [0051]    From the foregoing, therefore, it can be seen that the disclosed embodiments provide techniques for associating and authenticating a mobile device with external power sources that can be used to charge the device. Communication between the mobile device and the power source is carried out via the manner in which the device draws power from the source. In some embodiments, wireless communication between the mobile device and the power source are used to enhance the capabilities for pairing the mobile device with the power source, and authenticating the device. 
         [0052]    Once the pairing and authentication have been achieved, various approaches can be employed to quantify the amount of charge delivered to the mobile device. In one implementation, a standard rate of charge draw can be established for a given category of device. By measuring the duration of the charging period, the authenticator at the location of the power source can determine the amount of charge delivered, and report it to the back office  150 , for debiting the account of the device owner. 
         [0053]    In another implementation, a sealed, tamper-proof meter can be installed in the mobile device and connected to its wireless network interface  112 . Once the pairing has been established, the authenticator or the back office can send a command via the network interface, to begin measuring the current draw, and report back, either during the transaction period or upon completion of the period. 
         [0054]    If metering is possible at both the site of the source and within the mobile device, the charge amount measured at each location can be checked against one another for confirmation. In addition, the amount measured at the source can be employed to check the calibration, and/or detect tampering, of the meter in the mobile device. 
         [0055]    Thus, it will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.