Patent Publication Number: US-2023147188-A1

Title: Unauthorized tracking device detection and prevention

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/373,782, filed Jul. 13, 2021, now patent Ser. No. ______, which is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     This disclosure relates generally to tracking devices, and more specifically, to preserving a user&#39;s data security and privacy in a tracking device environment. 
     Electronic tracking devices track the location of people and/or objects. For example, a user can use GPS technology to track a device remotely and determine a location of a user of the device. In another example, a user can attach a tracking device to an important object, such as keys or a wallet, and use the features of the tracking device to more quickly locate the object, (e.g., if it becomes lost). 
     However, tracking devices and corresponding systems suffer from one or more disadvantages. If a tracking device is attached to a possession of a user without the user&#39;s permission, location and/or movement of the user or the user&#39;s possession can be tracked without authorization from the user. Accordingly, there is a need to prevent the unauthorized tracking of the user in such circumstances, thereby protecting the privacy of the user. 
     SUMMARY 
     A system and method for detecting unauthorized tracking devices are described herein. Unauthorized tracking devices may be devices that can track a user&#39;s location without the user knowing or consenting. In some cases, unauthorized tracking devices periodically change the identity information they emit to prevent detection. The system and method are configured to detect unauthorized tracking devices including those that change their identity information (herein referred to as complex identifier devices or rotating identifier devices). 
     The unknown device emits identity information over a broadcast distance (e.g., the broadcast range of the unknown device) and changes the identity information it emits periodically, after the passage of a set interval of time. The mobile device of the user detects multiple advertisement signals from an unknown device and communicates those advertisement signals to a tracking system along with location information of the mobile device and a time at which the signals were detected. The tracking system checks for matching identity information in the signals received during the set interval of time and once the mobile device&#39;s location has changed by at least a broadcast distance of the unknown device. For example, the mobile device may receive a signal with a first identity from an unknown device at a first location. At a second location at least the broadcast distance from the first location, the mobile device receives a second signal with the first identity during the interval of time. In response to the detection of two advertisement signals with matching identities, the tracking system tags the unknown device as following the user and generates an interface on the mobile device of the user to indicate the presence of the unknown device. 
     By surveying the signals received during the set interval of time since a first signal is received, the system can detect devices that rotate their identity information periodically at the set interval of time. The system avoids false positives from stationary devices in the environment of the user that are not following the user by ensuring that the user has traveled at least the broadcast distance of a device while monitoring for received signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example tracking system environment in which a tracking device can operate, according to one embodiment. 
         FIG.  2    illustrates an example tracking system for use in a tracking system environment, according to one embodiment. 
         FIG.  3    illustrates an example user mobile device for use in a tracking system environment, according to one embodiment. 
         FIG.  4    illustrates an example community mobile device for use in a tracking system environment, according to one embodiment. 
         FIG.  5    illustrates an example tracking device for use in a tracking system environment, according to one embodiment. 
         FIG.  6    illustrates an example unauthorized tracking device manager of a tracking system environment, according to one embodiment. 
         FIG.  7    illustrates an example tracking system environment including unauthorized devices, according to one embodiment. 
         FIG.  8    illustrates a process for managing unauthorized tracking devices, according to one embodiment. 
         FIG.  9    illustrates a process for identifying an unauthorized tracking device, according to one embodiment. 
         FIG.  10    illustrates a process for identifying an unauthorized tracking device with a complex identifier, according to one embodiment. 
         FIGS.  11 A , B, and C illustrate an example use case for identifying an unauthorized tracking device with a complex identifier, according to one embodiment. 
     
    
    
     The figures depict various embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein. 
     DETAILED DESCRIPTION 
     Environment Overview 
     Embodiments described herein detail functionality associated with a tracking device. A user can attach a tracking device to or enclose the tracking device within an object, such as a wallet, keys, a car, a bike, a pet, or any other object that the user wants to track. The user can then use a mobile device (e.g., by way of a software application installed on the mobile device) or other device or service to track the tracking device and corresponding object. For example, the mobile device can perform a local search for a tracking device attached to a near-by object. However, in situations where the user is unable to locate the tracking device using their own mobile device (e.g., if the tracking device is beyond a distance within which the mobile device and the tracking device can communicate), the user can leverage the capabilities of a community of users of a tracking device system. 
     In particular, a tracking system (also referred to herein as a “cloud server” or simply “server”) can maintain user profiles associated with a plurality of users of the tracking device system. The tracking system can associate each user within the system with one or more tracking devices associated the user (e.g., tracking devices that the user has purchased and is using to track objects owned by the user). If the user&#39;s object becomes lost or stolen, the user can send an indication that the tracking device is lost to the tracking system, which is in communication with one or more mobile devices associated with the community of users in communication with the system. The tracking system can set a flag indicating the tracking device is lost. When one of a community of mobile devices that are scanning for nearby tracking devices and providing updated locations to the tracking system identifies a flagged tracking device, the tracking system can associate the received location with the flagged tracking device, and relay the location to a user of the tracking device, thereby enabling the user to locate the lost tracking device. 
       FIG.  1    illustrates an example tracking system environment in which a tracking device can operate, according to one embodiment. The environment of  FIG.  1    includes a tracking system  100  communicatively coupled to a mobile device  102  associated with the user  103  via a first network  108 . The tracking system  100  is also communicatively coupled to a plurality of community mobile devices  104   a  through  104   n  (collectively referred to herein as “community mobile devices  104 ”) associated with a plurality of users  105   a  through  105   n  of the tracking system  100  (collectively referred to herein as “community users  105 ”) via the first network  108 . As will be explained in more detail below, the tracking system  100  can allow the user  103  to manage and/or locate a tracking device  106  associated with the user  103 . In some embodiments, the tracking system  100  leverages the capabilities of community mobile devices  104  to locate the tracking device  106  if the location of the tracking device is unknown to the user  103  and beyond the capabilities of mobile device  102  to track. In some configurations, the user  103  may own and register multiple tracking devices  106 . Although  FIG.  1    illustrates a particular arrangement of the tracking system  100 , mobile device  102 , community mobile devices  104 , and tracking device  106 , various additional arrangements are possible. For example, in some embodiments, the tracking system  100  can be implemented within the mobile device  102 . 
     In some configurations, the user  103  may be part of the community of users  105 . Further, one or more users  105  may own and register one or more tracking devices  106 . Thus, any one of the users within the community of users  105  can communicate with tracking system  100  and leverage the capabilities of the community of users  105  in addition to the user  103  to locate a tracking device  106  that has been lost. 
     The tracking system  100 , mobile device  102 , and plurality of community mobile devices  104  may communicate using any communication platforms and technologies suitable for transporting data and/or communication signals, including known communication technologies, devices, media, and protocols supportive of remote data communications. 
     In certain embodiments, the tracking system  100 , mobile device  102 , and community mobile devices  104  may communicate via a network  108 , which may include one or more networks, including, but not limited to, wireless networks (e.g., wireless communication networks), mobile telephone networks (e.g., cellular telephone networks), closed communication networks, open communication networks, satellite networks, navigation networks, broadband networks, narrowband networks, the Internet, local area networks, and any other networks capable of carrying data and/or communications signals between the tracking system  100 , mobile device  102 , and community mobile devices  104 . The mobile device  102  and community of mobile devices  104  may also be in communication with a tracking device  106  via a second network  110 . The second network  110  may be a similar or different type of network as the first network  108 . In some embodiments, the second network  110  comprises a wireless network with a limited communication range, such as a Bluetooth or Bluetooth Low Energy (BLE) wireless network. In some configurations, the second network  110  is a point-to-point network including the tracking device  106  and one or more mobile devices that fall within a proximity of the tracking device  106 . In such embodiments, the mobile device  102  and community mobile devices  104  may only be able to communicate with the tracking device  106  if they are within a close proximity to the tracking device, though in other embodiments, the tracking device can use long-distance communication functionality (for instance, a GSM transceiver) to communicate with either a mobile device  102 / 104  or the tracking system  100  at any distance. In some configurations, the mobile device  102  and one or more community mobile devices  104  may each be associated with multiple tracking devices associated with various users. 
     As mentioned above,  FIG.  1    illustrates the mobile device  102  associated with the user  103 . The mobile device  102  can be configured to perform one or more functions described herein with respect to locating tracking devices (e.g., tracking device  106 ). For example, the mobile device  102  can receive input from the user  103  representative of information about the user  103  and information about a tracking device  106 . The mobile device  102  may then provide the received user information, tracking device information, and/or information about the mobile device  102  to the tracking system  100 . Accordingly, the tracking system  100  is able to associate the mobile device  102 , the user  103 , and/or the tracking device  106  with one another. In some embodiments, the mobile device  102  can communicate with the tracking device  106  and provide information regarding the location of the tracking device to the user  103 . For example, the mobile device  102  can detect a communication signal from the tracking device  106  (e.g., by way of second network  110 ) as well as a strength of the communication signal or other measure of proximity to determine an approximate distance between the mobile device  102  and the tracking device  106 . The mobile device  102  can then provide this information to the user  103  (e.g., by way of one or more graphical user interfaces) to assist the user  103  to locate the tracking device  106 . Accordingly, the user  103  can use the mobile device  102  to track and locate the tracking device  106  and a corresponding object associated with the tracking device  106 . If the mobile device  102  is located beyond the immediate range of communication with the tracking device  106  (e.g., beyond the second network  110 ), the mobile device  102  can be configured to send an indication that a tracking device  106  is lost to the tracking system  100 , requesting assistance in finding the tracking device. The mobile device  102  can send an indication of a lost device in response to a command from the user  103 . For example, once the user  103  has determined that the tracking device  106  is lost, the user can provide user input to the mobile device  102  (e.g., by way of a graphical user interface), requesting that the mobile device  102  send an indication that the tracking device  106  is lost to the tracking system  100 . In some examples, the lost indication can include information identifying the user  103  (e.g., name, username, authentication information), information associated with the mobile device  102  (e.g., a mobile phone number), information associated with the tracking device (e.g., a unique tracking device identifier), or a location of the user (e.g., a GPS location of the mobile device  102  at the time the request is sent). 
     The tracking system  100  can be configured to provide a number of features and services associated with the tracking and management of a plurality of tracking devices and/or users associated with the tracking devices. For example, the tracking system  100  can manage information and/or user profiles associated with user  103  and community users  105 . In particular, the tracking system  100  can manage information associated with the tracking device  106  and/or other tracking devices associated with the user  103  and/or the community users  105 . 
     As mentioned above, the tracking system  100  can receive an indication that the tracking device  106  is lost from the mobile device  102 . The tracking system  100  can then process the indication in order to help the user  103  find the tracking device  106 . For example, the tracking system  100  can leverage the capabilities of the community mobile devices  104  to help find the tracking device  106 . In particular, the tracking system  100  may set a flag for a tracking device  106  to indicate that the tracking device  106  lost and monitor communications received from the community mobile devices  104  indicating the location of one or more tracking devices  106  within proximity of the community mobile devices  104 . The tracking system  100  can determine whether a specific location is associated with the lost tracking device  106  and provide any location updates associated with the tracking device  106  to the mobile device  102 . In one example, the tracking system may receive constant updates of tracking device  106  locations regardless of whether a tracking device  106  is lost and provide a most recent updated location of the tracking device  106  in response to receiving an indication that the tracking device  106  is lost. 
     In some configurations, the tracking system  100  can send a location request associated with the tracking device  106  to each of the community mobile devices  104 . The location request can include any instructions and/or information necessary for the community mobile devices  106  to find the tracking device  102 . For example, the location request can include a unique identifier associated with the tracking device  106  that can be used by the community mobile devices  104  to identify the tracking device  106 . Accordingly, if one of the community mobile devices  104  detects a communication from the tracking device  106  (e.g., if the community mobile device  104  is within range or moves within range of the communication capabilities of the tracking device  106  and receives a communication signal from the tracking device  106  including or associated with the unique identifier associated with the tracking device  106 ), the community mobile device  104  can inform the tracking system  100 . Using the information received from the community mobile devices  104 , the tracking system  100  can inform the user (e.g., by way of the mobile device  102 ) of a potential location of the tracking device  106 . 
     As shown in  FIG.  1    and as mentioned above, the tracking system  100  can communicate with a plurality of community mobile devices  104  associated with corresponding community users  105 . For example, an implementation may include a first community mobile device  104   a  associated with a first community user  105   a , a second community mobile device  104   b  associated with a second community user  105   b , and additional communication mobile devices associated with additional community users up to an nth community mobile device  104   n  associated with an nth community user  105   n . The community mobile devices  104  may also include functionality that enables each community mobile device  104  to identify a tracking device  106  within a proximity or communicable range of the community mobile device  104 . In one example, a first community mobile device  104   a  within proximity of a tracking device  106  can communicate with the tracking device  106 , identify the tracking device  106  (e.g., using a unique identifier associated with the tracking device  106 ), and/or detect a location associated with the tracking device  106  (e.g., a location of the first mobile community device  104   a  at the time of the communication with the tracking device  106 ). This information can be used to provide updated locations and/or respond to a location request from the tracking system  100  regarding the tracking device  106 . In some embodiments, the steps performed by the first community mobile device  104   a  can be hidden from the first community user  105   a . Accordingly, the first community mobile device  104   a  can assist in locating the tracking device  106  without bother and without the knowledge of the first community user  105   a.    
     As mentioned above, the tracking system  100  can assist a user  103  in locating a tracking device  106 . The tracking device may be a chip, tile, tag, or other device for housing circuitry and that may be attached to or enclosed within an object such as a wallet, keys, purse, car, or other object that the user  103  may track. Additionally, the tracking device  106  may include a speaker for emitting a sound and/or a transmitter for broadcasting a beacon. In one configuration, the tracking device  106  may periodically transmit a beacon signal that may be detected using a nearby mobile device  102  and/or community mobile device  104 . In some configurations, the tracking device  106  broadcasts a beacon at regular intervals (e.g., one second intervals) that may be detected from a nearby mobile device (e.g., community mobile device  104 ). The strength of the signal emitted from the tracking device  106  may be used to determine a degree of proximity to the mobile device  102  or community mobile device  104  that detects the signal. For example, a higher strength signal would indicate a close proximity between the tracking device  106  and the mobile device  102  and a lower strength signal would indicate a more remote proximity between the tracking device  106  and the mobile device  102 , though in some embodiments, the tracking device  106  can intentionally vary the transmission strength of the beacon signal. In some cases, the strength of signal or absence of a signal may be used to indicate that a tracking device  106  is lost. 
     System Overview 
       FIG.  2    illustrates an example tracking system for use in a tracking system environment, according to one embodiment. As shown, the tracking system  100  may include, but is not limited to, an association manager  204 , a tracking device location manager  206 , a data manager  208 , and an unauthorized tracking device manager, each of which may be in communication with one another using any suitable communication technologies. It will be recognized that although managers  204 - 208  are shown to be separate in  FIG.  2   , any of the managers  204 - 208  may be combined into fewer managers, such as into a single manager, or divided into more managers as may serve a particular embodiment. 
     The association manager  204  may be configured to receive, transmit, obtain, and/or update information about a user  103  and/or information about one or more specific tracking devices (e.g., tracking device  106 ). In some configurations, the association manager  204  may associate information associated with a user  103  with information associated with a tracking device  106 . For example, user information and tracking information may be obtained by way of a mobile device  102 , and the association manager  204  may be used to link the user information and tracking information. The association between user  103  and tracking device  106  may be used for authentication purposes, or for storing user information, tracking device information, permissions, or other information about a user  103  and/or tracking device  106  in a database. 
     In some embodiments, the association manager  204  may be used to facilitate identification of authorized and unauthorized devices from one or more wireless devices connected with the mobile device  102 . For example, the association manager  204  may be configured to access authorized device identifiers defining a set of authorized devices. The authorized devices may define authorized tracking devices, such as owner tracking devices associated with the user of the mobile device, shared tracking devices associated with a connected user of the user of the mobile device, or other authorized (e.g., non-tracking) wireless devices (e.g., a peripheral device). Each authorized device may be associated with a device identifier. A detected wireless device that fails to include an authorized device identifier may be identified as an unauthorized device. In some embodiments, a list of unauthorized device identifiers may also be stored and referenced to determine whether detected wireless device is an authorized or unauthorized device. 
     The tracking system  100  also includes a tracking device location manager  206 . The tracking device location manager  206  may receive and process an indication that the tracking device  106  is lost from a mobile device (e.g., mobile device  102  or community mobile devices  104 ). For example, the tracking system  100  may receive a lost indication from a mobile device  102  indicating that the tracking device  106  is lost. The tracking device location manager  206  may set a flag on a database (e.g., tracker database  212 ) indicating that the tracking device  106  is lost. The tracking device location manager  206  may also query a database to determine tracking information corresponding to the associated user  103  and/or tracking device  106 . The tracking system  100  may obtain tracking device information and provide the tracking device information or other information associated with the tracking device  106  to a plurality of community mobile devices  104  to be on alert for the lost or unavailable tracking device  106 . 
     The tracking device location manager  206  may also receive a location from one or more community mobile devices  104  that detect the tracking device  106 , for instance in response to the community mobile device receiving a beacon signal transmitted by the tracking device  106 , without the tracking device  106  having been previously marked as lost. In such embodiments, a user corresponding to the mobile device  102  can request a most recent location associated with the tracking device from the tracking system  100 , and the location manager  206  can provide the location received from the community mobile device for display by the mobile device  102 . In some embodiments, the location manager  206  provides the location of the tracking device  106  received from a community mobile device either automatically (for instance if the tracking device  106  is marked as lost) or at the request of a user of the mobile device  102  (for instance, via an application on the mobile device  102 ). The location manager  206  can provide a location of a tracking device  106  to a mobile device  102  via a text message, push notification, application notification, automated voice message, or any other suitable form of communication. 
     The tracking device location manager  206  may further manage providing indications about whether a tracking device  106  is lost or not lost. For example, as discussed above, the tracking device location manager  206  may provide a location request to the community of mobile devices  104  indicating that a tracking device  106  is lost. Additionally, upon location of the tracking device  106  by the user  103  or by one of the community of users  105 , the tracking device location manager  206  may provide an indication to the user  103 , community user  105 , or tracking system  100  that the tracking device  106  has been found, thus removing any flags associated with a tracking device and/or canceling any location request previously provided to the community of users  105 . For example, where a user  103  sends an indication that the tracking device  106  is lost to the tracking system  100  and later finds the tracking device  106 , the mobile device  102  may provide an indication to the tracking system  100  that the tracking device  106  has been found. In response, the tracking device location manager  206  may remove a flag indicating that the tracking device  106  is lost and/or provide an updated indication to the community of users  105  that the tracking device  106  has been found, thus canceling any instructions associated with the previously provided location request. In some configurations, the notification that the tracking device  106  has been found may be provided automatically upon the mobile device  102  detecting the tracking device  106  within a proximity of the mobile device  102 . Alternatively, the notification that the tracking device  106  has been found may be provided by the user  103  via user input on the mobile device  102 . In another example, a known user (e.g., a friend or family member) with whom the tracking device  106  has been shared may provide an indication that the tracking device  106  has been found. 
     The tracking system  100  additionally includes a data manager  208 . The data manager  208  may store and manage information associated with users, mobile devices, tracking devices, permissions, location requests, and other data that may be stored and/or maintained in a database related to performing location services of tracking devices. As shown, the data manager  208  may include, but is not limited to, a user database  210 , a tracker database  212 , permissions data  214 , and location request data  216 . It will be recognized that although databases and data within the data manager  208  are shown to be separate in  FIG.  2   , any of the user database  210 , tracker database  212 , permissions data  214 , and location request data  216  may be combined in a single database or manager, or divided into more databases or managers as may serve a particular embodiment. 
     The data manager  208  may include the user database  210 . The user database  210  may be used to store data related to various users. For example, the user database  210  may include data about the user  103  as well as data about each user  105  in a community of users  105 . The community of users  105  may include any user that has provided user information to the tracking system  100  via a mobile device  102 ,  104  or other electronic device. The user information may be associated with one or more respective tracking devices  106  or may be stored without an association to a particular tracking device. For example, a community user  105  may provide user information and permit performance of tracking functions on the community mobile device  104  without owning or being associated with a tracking device  106 . The user database  210  may also include information about one or more mobile devices or other electronic devices associated with a particular user. 
     The user database  210  may also include information defining shared tracking devices. A shared tracking device refers to a tracking device that is owned by a different user but is an authorized device for tracking the user. For example, the user database  210  may associate the user with another user (e.g., a friend, connection, etc.) such that a tracking device owned by the other is identified as a shared tracking device for the user. 
     The data manager  208  may also include a tracker database  212 . The tracker database  212  may be used to store data related to tracking devices. For example, the tracker database  212  may include tracking data for any tracking device  106  that has been registered or otherwise authorized with the tracking system  100 . Tracking data may include unique tracker identifications (IDs) or “device identifiers” associated with individual tracking devices  106 . Tracker IDs may be associated with a respective user  103 . Tracker IDs may also be associated with multiple users. Additionally, the tracker database  212  may include any flags or other indications associated with whether a specific tracking device  106  has been indicated as lost and whether any incoming communications with regard to that tracking device  106  should be processed based on the presence of a flag associated with the tracking device  106 . In some embodiments, the tracker database  212  may further include an authorized tracking device flag indicating whether a specific tracking device  106  has been identified as an unauthorized tracking device for a user. 
     The data manager  208  may further include permissions data  214  and location request data  216 . Permissions data  214  may include levels of permissions associated with a particular user  103  and/or tracking device  106 . For example, permissions data  214  may include additional users that have been indicated as sharing a tracking device  106 , or who have been given permission to locate or receive a location of a tracking device  106 . Location request data  216  may include information related to a location request or a lost indication received from the user  103  via a mobile device  102 . 
     The tracking system  100  further includes an unauthorized device manager  218 . The unauthorized device manager  218  may be configured to perform the functionalities discussed herein with respect to identifying unauthorized tracking devices from wireless devices detected by a mobile device  102  and performing suitable remedial actions. The unauthorized device manager  218  may be further configured to remotely disable an authorized tracking device if possible, such as when the unauthorized tracking device is a tracking device managed by the tracking system  100  (or a “managed tracking device,” as used herein). In another example, if the unauthorized tracking device is not a managed tracking device or otherwise cannot be controlled by the tracking system  100 , then a notification may be sent to a (e.g., third party) system associated with the unauthorized tracking device. 
       FIG.  3    illustrates an example user mobile device for use in a tracking system environment, according to one embodiment. As shown, the mobile device  102  may include, but is not limited to, a user interface manager  302 , a location request manager  304 , a database manager  306 , and a tracking manager  308 , each of which may be in communication with one another using any suitable communication technologies. It will be recognized that although managers  302 - 308  are shown to be separate in  FIG.  3   , any of the managers  302 - 308  may be combined into fewer managers, such as into a single manager, or divided into more managers as may serve a particular embodiment. 
     As will be explained in more detail below, the mobile device  102  includes the user interface manager  302 . The user interface manager  302  may facilitate providing the user  103  access to data on a tracking system  100  and/or providing data to the tracking system  100 . Further, the user interface manager  302  provides a user interface by which the user  103  may communicate with tracking system  100  and/or tracking device  106  via mobile device  102 . 
     The mobile device  102  may also include a location request manager  304 . The location request manager  304  may receive and process a request input to the mobile device  102  to send an indication that a tracking device  106  is lost to a tracking system  100 . For example, the user  103  may provide an indication that a tracking device  106  is lost, unreachable, or otherwise unavailable from the mobile device  102  via the user interface manager  302 , and the location request manager  304  may process the lost indication and provide any necessary data to the tracking system  100  for processing and relaying a location request to other users  105  over a network  108 . In some configurations, an indication that a tracking device  106  is lost is provided via user input. Alternatively, the indication may be transmitted automatically in response to the mobile device  102  determining that a tracking device  106  is lost. 
     In addition, the location request manager  304  can request a location of the tracking device  106  without the tracking device  106  being identified as lost. For instance, a user can access a tracking device location feature of an application running on the mobile device  102  (for example, via the user interface manager  302 ), and the location request manager  304  can request a most recent location of the tracking device  106  from the tracking system  100 . The location request manager  304  can receive the most recent location from the tracking system  100  and can display the most recent location via the user interface manager  302 . 
     The mobile device  102  may also include a database manager  306 . The database manager  306  may maintain data related to the user  103 , tracking device  106 , permissions, or other data that may be used for locating a tracking device  106  and/or providing a request to a tracking system  100  for locating one or more tracking devices  106  associated with the user  103 . Further, the database manager  306  may maintain any information that may be accessed using any other manager on the mobile device  102 . 
     The mobile device  102  may further include a tracking manager  308 . The tracking manager  308  may also comprise a tracking application (e.g., a software application) for communicating with and locating a tracking device  106  associated with the user  103 . The tracking manager  308  may be configured to communicate with the unauthorized tracking device manager  218  of the tracking system  100  to provide the functionality discussed herein with respect to unauthorized device detection and handling. For example, the tracking manager  308  may be configured to receive notifications regarding unauthorized devices and facilitate user definition of authorized devices. 
     The tracking manager  308  may be one configuration of a tracking application installed on the mobile device  102  that provides the functionality for locating a tracking device  106  and/or requesting location of a tracking device  106  using a tracking system  100  and/or a plurality of community mobile devices  104 . As shown, the tracking manager  308  may include, but is not limited to, a Bluetooth Low Energy (BLE) manager  310 , a persistence manager  312 , a local files manager  314 , a motion manager  316 , a secure storage manager  318 , a settings manager  320 , a location manager  322 , a network manager  324 , a notification manager  326 , a sound manager  328 , a friends manager  330 , a photo manager  332 , an authentication manager  334 , and a device manager  336 . Thus, the tracking manager  308  may perform any of the functions associated with managers  310 - 338 , described in additional detail below. 
     The BLE manager  310  may be used to manage communication with one or more tracking devices  106 . The persistence manager  312  may be used to store logical schema information that is relevant to the tracking manager  308 . The local files manager  314  may be responsible for managing all files that are input or output from the mobile device  102 . The motion manager  316  may be responsible for all motion management required by the tracking manager  308 . The secure storage manager may be responsible for storage of secure data, including information such as passwords and private data that would be accessed through this sub-system. The settings manager  320  may be responsible for managing settings used by the tracking manager  308 . Such settings may be user controlled (e.g., user settings) or defined by the tracking manager  308  for internal use (e.g., application settings) by a mobile device  102  and/or the tracking system  100 . The location manager  322  may be responsible for location tracking done by the tracking manager  308 . For example, the location manager  322  may manage access to the location services of the mobile device  102  and works in conjunction with other managers to persist data. The network manager  324  may be responsible for all Internet communications from the tracking manager  308 . For example, the network manager  324  may mediate all Internet API calls for the tracking manager  308 . The notification manager  326  may be responsible for managing local and push notifications required by the tracking manager  308 . The sound manager  328  may be responsible for playback of audio cues by the tracking manager  308 . The friends manager  330  may be responsible for managing access to contacts and the user&#39;s social graph. The photo manager  332  may be responsible for capturing and managing photos used by the tracking manager  308 . The authentication manager  334  may be responsible for handling the authentication (e.g., sign in or login) of users. The authentication manager  334  may also include registration (e.g., sign up) functionality. The authentication manager  334  further coordinates with other managers to achieve registration functionality. The device manager  336  may be responsible for managing the devices discovered by the tracking manager  308 . The device manager  336  may further store and/or maintain the logic for algorithms related to device discovery and update. 
       FIG.  4    illustrates an example community mobile device for use in a tracking system environment, according to one embodiment. As shown, the community mobile device  104  may include, but is not limited to, a user interface manager  402 , a tracking device manager  404 , a database manager  406 , and a tracking manager  408 , each of which may be in communication with one another using any suitable communication technologies. The user interface manager  402 , database manager  406 , and tracking manager  408  illustrated in  FIG.  4    may include similar features and functionality as the user interface manager  302 , database manager  306 , and tracking manager  308  described above in connection with  FIG.  3   . It will be recognized that although managers  402 - 408  are shown to be separate in  FIG.  4   , any of the managers  402 - 408  may be combined into fewer managers, such as into a single manager, or divided into more managers as may serve a particular embodiment. 
     The community mobile device  104  may include a tracking device manager  404 . The tracking device manager  404  may facilitate scanning for nearby tracking devices  106 . In some configurations, the tracking device manager  404  can continuously or periodically scan (e.g., once per second) for nearby tracking devices  106 . The tracking device manager  404  may determine whether to provide an updated location of the nearby tracking device  106  to the tracking system  100 . In some configurations, the tracking device manager  404  provides a location of a nearby tracking device  106  automatically. Alternatively, the tracking device manager  404  may determine whether the location of the tracking device  106  has been recently updated, and may determine whether to provide an updated location based on the last time a location of the tracking device  106  has been updated (e.g., by the community mobile device  104 ). For example, where the community mobile device  104  has provided a recent update of the location of a tracking device  106 , the tracking device manager  404  may decide to wait a predetermined period of time (e.g., 5 minutes) before providing an updated location of the same tracking device  106 . 
     In one configuration, the tracking device manager  404  may receive and process a location request or other information relayed to the community mobile device  104  by the tracking system  100 . For example, the tracking device manager  404  may receive an indication of a tracking device  106  that has been indicated as lost and provide a location of the tracking device  106  if it comes within proximity of the community mobile device  104 . In some configurations, the community mobile device  104  is constantly scanning nearby areas to determine if there is a tracking device  106  within a proximity of the community mobile device  104 . Therefore, where a tracking device  106  that matches information provided by the tracking system  100  (e.g., from the location request) comes within proximity of the community mobile device  104 , the tracking device manager  404  may generate and transmit a response to the location request to the tracking system  100 , which may be provided to the user  103  associated with the tracking device  106 . Further, generating and transmitting the response to the tracking request may be conditioned on the status of the tracking device  106  being flagged as lost by the mobile device  102  and/or the tracking system  100 . 
     The tracking device manager  404  may additionally provide other information to the tracking system  100  in response to receiving the tracking request. For example, in addition to providing a location of the community mobile device  104 , the tracking device manager may provide a signal strength associated with the location to indicate a level of proximity to the location of the community mobile device  104  provided to the user  103 . For example, if a signal strength of a communication signal is high, the location provided to the user  103  is likely to be more accurate than a location accompanied by a low signal strength. This may provide additional information that the user  103  may find useful in determining the precise location of tracking device  106 . 
     As described above, the tracking device manager  404  may determine whether to send a location within the proximity of the tracking device  106  to the tracking system  100 . The determination of whether to send a location to the tracking system  100  may be based on a variety of factors. For example, a tracking device manager  404  may determine to send a location of the tracking device  106  to a tracking system  100  based on whether the detected tracking device  106  has been indicated as lost or if a tracking request has been provided to the community mobile device  104  for the particular tracking device  106 . In some configurations, the community mobile device  104  may send an update of a location of a tracking device  106  even if the tracking device  106  is not associated with a current tracking request or if the tracking device  106  is not indicated as lost. For example, where the location of a tracking device  106  has not been updated for a predetermined period of time, the community mobile device  104  may provide an update of a tracking device location to the tracking system  100 , regardless of whether a tracking request has been received. 
     In some configurations, the community mobile device  104  may include additional features. For example, the community mobile device  104  may allow a tracking system  100  to snap and download a photo using photo functionality of the community mobile device  104 . In some configurations, this may be an opt-in feature by which a community user  105  permits a tracking system  100  to take a snap-shot and possibly provide a visual image of an area within a proximity of the tracking device  106 . 
       FIG.  5    illustrates an example tracking device for use in a tracking system environment, according to one embodiment. The tracking device  106  of  FIG.  5    includes an interface  502 , a transceiver  504 , a controller  506 , and one or more sensors  508 . The transceiver  504  is a hardware circuit capable of both transmitting and receiving signals. It should be noted that in other embodiments, the tracking device  106  includes fewer, additional, or different components than those illustrated in  FIG.  5   . 
     The interface  502  provides a communicative interface between the tracking device  106  and one or more other devices, such as a mobile device  102 . For instance, the interface  502  can instruct the transceiver  504  to output beacon signals as described above (for example, periodically or in response to a triggering event, such as a detected movement of the tracking device  106 ). The interface  502  can, in response to the receiving of signals by the transceiver  504  from, for instance, the mobile device  102 , manage a pairing protocol to establish a communicative connection between the tracking device  106  and the mobile device  102 . As noted above, the pairing protocol can be a BLE connection, though in other embodiments, the interface  502  can manage other suitable wireless connection protocols (such as WiFi, Global System for Mobile Communications or GSM, and the like). 
     The controller  506  is a hardware chip that configures the tracking device  106  to perform one or more functions or to operate in one or operating modes or states. For instance, the controller  506  can configure the interval at which the transceiver broadcasts beacon signals, can authorize or prevent particular devices from pairing with the tracking device  106  based on information received from the devices and permissions stored at the tracking device, can increase or decrease the transmission strength of signals broadcasted by the transceiver, can configure the interface to emit a ringtone or flash an LED light, can enable or disable various tracking device sensors, can enable or disable communicative functionality of the tracking device  106  (such as a GSM transmitter and receiving), can configure the tracking device into a sleep mode or awake mode, can configure the tracking device into a power saving mode, and the like. The controller  506  can configure the tracking device to perform functions or to operate in a particular operating mode based on information or signals received from a device paired with or attempting to pair with the tracking device  106 , based on an operating state or connection state of the tracking device  106 , based on user-selected settings, based on information stored at the tracking device  106 , based on a detected location of the tracking device  106 , based on historical behavior of the tracking device  106  (such as a previous length of time the tracking device was configured to operate in a particular mode), based on information received from the sensors  508 , or based on any other suitable criteria. 
     In some embodiments, the controller  506  may be configured to facilitate remote activation or deactivation of the tracking device  105 , such as based on received instructions from the tracking system  100 . The tracking system  100  may be configured to communicate activation or deactivation instructions to the tracking device  105  via the mobile device  102 . For example, the instruction may be generated by the tracking system  100  when an unauthorized device is identified as an unauthorized tracking device managed by the tracking system  100 , then sent to the mobile device  102  via the first network  108 , and then to the tracking device  106  via the second network  110 . In another example, the instruction may be provided to the tracking device  106  via a community mobile device  104 . In another example, the instruction may be provided to the tracking device  106  without traveling through a mobile device  102 / 104 , such as directly through the first network  108 . 
     The sensors  508  can include motion sensors (such as gyroscopes or accelerators), altimeters, orientation sensors, proximity sensors, light sensors, or any other suitable sensor configured to detect an environment of the tracking device  106 , a state of the tracking device  106 , a movement or location of the tracking device  106 , and the like. The sensors  508  are configured to provide information detected by the sensors to the controller  506 . 
     Privacy Preservation in a Tracking Device Environment 
     In some embodiments, a tracking system environment may be configured to facilitate unauthorized tracking device management, including unauthorized tracking device detection and remote handling. 
       FIG.  6    illustrates an example unauthorized tracking device manager of a tracking system environment, according to one embodiment. The tracking system  100  includes an unauthorized tracking device manager  218 . The unauthorized tracking device manager  218  may include an unauthorized tracking device detector  602  and a complex identifier device detector  604 . The unauthorized tracking device detector  602  implements processes, such as processes  800  and  900 , for identification and classification of unauthorized tracking devices as well as deactivating those devices. The complex identifier device detector  604  implements a detection process  1000  for identifying and managing devices using complex identifiers, described in conjunction with  FIG.  10    below. Complex identifier devices may periodically change the communication signals they emit to prevent detection of the device. Commonly, complex identifier devices rotate between identification signals they emit after a set interval of time. The detection of complex identifier devices is described in greater detail below. 
       FIG.  7    illustrates an example tracking system environment including unauthorized devices, according to one embodiment. The environment in  FIG.  7    is a local environment of the user  103  carrying the mobile device  102 , including the second network  110  and one or more wireless devices connected with the mobile device  102  via the second network  110 . 
     As discussed above, the second network  110  may include a wireless network with a limited communication range, such as a Bluetooth or Bluetooth Low Energy (BLE) wireless network. In one example, the second network  110  is a BLE wireless network having a communication range of approximately 10 meters from the mobile device  102 . The second network  110  may include other types of suitable personal area networks capable of wireless communication at a limited communication range such that communication with a wireless device indicates location proximity between the wireless device and the mobile device  102 . 
     The wireless devices connected with the mobile device  102  may include one or more unauthorized devices  702  and one or more authorized devices  704 . When an unknown device is detected by the mobile device  102  via the second network, the unknown device may be classified into one of the classes of devices  702 - 714 . Examples of an unauthorized device  702  may include an unauthorized tracking device  706  or other unauthorized (non-tracking) wireless device  708 . An authorized device  704  may include an owner tracking device  710 , a shared tracking device  712 , or other authorized (non-tracking) wireless device  714 . 
     The unauthorized tracking device  708  refers to a tracking device which may be managed by the tracking system  100  (e.g., a “managed tracking device,” as used herein), or alternatively, a tracking device managed or associated with a separate system. The unauthorized device  708  refers to a wireless device that is not authorized by the user  103 , but has not been identified as a tracking device (e.g., connection qualities indicate low tracking device probability) or has been identified as being a device different from a tracking device (e.g., nearby mobile device of another user). 
     The owner tracking device  710  refers to a tracking device owned by the user  103 . For example, the user  103  may have registered the owner tracking device  710  with the tracking system  100  as the owner or manager of the owner tracking device  710 . The shared tracking device  712  refers to a tracking device owned by another user. The shared tracking device  712  may be associated with the user  103 , such as based on the owner of the shared tracking device  712  being a connected user of the user  103 . The authorized wireless device  714  refers to a non-tracking device that is authorized by the user  103 . 
     In some embodiments, authorized devices may be stored to facilitate device identification. For example, each authorized device may be associated with a unique device identifier that is stored at the tracking system  100  (e.g., at tracker database  212 ). The mobile device  102  may be configured to scan, listen for, or otherwise detect wireless devices within the communicable range of the mobile device  102 . In some embodiments, unique identifiers associated with known unauthorized devices may additionally or alternatively be stored to facilitate device identification. 
     As discussed above in connection with  FIG.  1   , the mobile device  102  is connected with the tracking system  100  via the first network  108 . The wireless devices  702 / 704  are connected with the mobile device  102  via the second network  110 . Thus, the mobile device  102  may serve as intermediary for communications between a tracking device  106  and the tracking system  100  (e.g., even when the tracking device  106  supports only short range wireless communication). In some embodiments, the tracking system  100  may be configured to remotely control tracking devices  106 , such as the activation or deactivation of managed tracking devices, based on sending an instruction to the tracking devices  106 . The instruction may be provided directly to the tracking device or through the mobile device  102 , such as via the first network  108 , the mobile device  102 , the second network  110 , and then to the tracking device  106 . 
       FIG.  8    illustrates a process  800  for managing unauthorized tracking devices, according to one embodiment. Process  800  may be performed within the tracking system environments shown in  FIGS.  1  and  7    to enable a user to detect and prevent unauthorized tracking devices. Process  800  is primarily discussed with respect to a tracking system configuration, where an unauthorized tracking device manager  218  of the tracking system  100  is configured to perform remote management of tracking devices  106  for a mobile device  102 . However, in a local configuration, some or all of the functionality may be performed by the tracking manager  308  of the mobile device  102 . 
     At  810 , the mobile device  106  may be configured to detect wireless devices within a communication range of the mobile device  106 . The mobile device  102  may be configured to scan, listen for, or otherwise detect wireless devices within the communicable range of the mobile device  102  using the second network  110 . The wireless devices may include unauthorized devices, authorized devices, or unknown devices without a classification. Some of the wireless devices, whether authorized or unauthorized, may be tracking devices. 
     The mobile device  102  and the wireless devices may be configured to transfer communication signals. In some embodiments, a communication signal may include a device identifier or other unique identifier associated with the wireless device. If the wireless device is a tracking device  106 , the tracking device  106  may store the device identifier in a memory and broadcast the device identifier to nearby mobile devices  102  (e.g., as a beacon at regular intervals). The mobile device  102  may be configured to receive the device identifiers of connected wireless devices and transmit the device identifiers to the tracking system  100 . 
     At  820 , the tracking system  100  (e.g., the unauthorized tracking device manager  218 ) may be configured to identify an unauthorized tracking device from the detected wireless devices. Identification of an unauthorized tracking device may include determining, from the pool of detected wireless devices, a wireless device that is both unauthorized and exhibiting communication signal or connection characteristics that indicate the wireless device is tracking the user. The identification may be based on user input (e.g., device authorization based on registration) and/or programmatic analysis of communication signals between the mobile device  102  and the detected wireless devices. Although various techniques may be used to identify unauthorized tracking devices from unknown wireless devices, an example process  900  is discussed below in connection with  FIG.  9   . 
     At  830 , the tracking system  100  may be configured to determine whether the unauthorized tracking device is a managed tracking device of the tracking system  100 . A managed tracking device refers to a tracking device  106  that is controlled by the tracking system  100 . The tracking system  100  may store a managed tracking device list including unique device IDs for managed tracking devices. The device ID of an unauthorized tracking device may be compared with the device IDs of managed tracking devices to determine whether the unauthorized tracking device is a managed tracking device. 
     In response to determining that the unauthorized tracking device is a managed tracking device, process  800  may proceed to  840 , where the tracking system  100  may be configured to remotely deactivate the managed tracking device. After a managed tracking device has been identified, the tracking system  100  may attempt to remotely control the managed tracking device if possible. For example, the tracking device  106  may be configured to provide a security token, password, key or other code that is recognized by the tracking device  106 , and causes the tracking device  106  to function in accordance with instructions sent from the tracking system  100 . 
     For an unauthorized tracking device  706  managed by the tracking system  100 , the instruction may define a remote deactivation command that prevents the unauthorized tracking device  706  from wirelessly communicating with, listening to, or detecting the mobile device  102 . Thus, the tracking functionality of the unauthorized tracking device  706  is disabled. Remote commands are not necessarily limited to deactivation. In another example, an instruction may define a remote activation command that enables wireless communication for the tracking device. Deactivation may refer to powering down the tracking device, or deactivation of wireless communication components (e.g., transmitter, receiver, etc.) of the tracking device. In another example, deactivation may include unregistering the unauthorized tracking device  706  for the owner, deactivating mobile device location detection/sharing for the unauthorized tracking device  706 , disassociating the unauthorized tracking device  706  with the user profile of the owner, or terminating/suspending the user profile or account of the owner, etc. 
     In some embodiments, remotely deactivating the managed tracking device may include sending the instruction to the managed tracking device via the mobile device  102 . For example, the tracking system  100  may be configured to control the tracking device  106  via the network  108 , the mobile device  102 , the second network  110 , and then the tracking device  106 . 
     In some embodiments, remotely deactivating the managed tracking device may include sending the instruction to the managed tracking device via a community mobile device  104  separate from the mobile device  102 . For example, the tracking system  100  may be configured to control the tracking device  106  by communicating with the community mobile device  104  via the first network  108 , and the community mobile device  104  may communicate with the tracking device  106  via the first network  108 , the mobile device  102 , the second network  110 , and then the tracking device  106 . For example, the community device  104  may own or be associated with the tracking device  106  and may be used to provide a security code or the like to deactivate the tracking device  106 . 
     In some embodiments, the control instructions and/or other communications between the tracking system  100  and the tracking device  106  does not pass through any mobile device  102 . For example, the tracking device  106  may directly connect with the tracking system  100  via first network  108 . 
     Returning to  830 , in response to determining that the unauthorized tracking device is not a managed tracking device, process  800  may proceed to  850 , where the tracking system  100  may be configured to send a notification to a system associated with the unauthorized tracking device. The notification may include a message indicating that the unauthorized tracking device has been identified for tracking the user  103  without authorization, which may trigger remedial action by the system. In some embodiments, the notification may include a request to deactivate to unauthorized tracking device. Method  800  may be repeated to provide tracking device identification and handling for wireless devices detected over time by the mobile device  102 . 
     In some embodiments, the tracking system  100  identifies unauthorized tracking devices tracking a user  103  based on communicating with one or more community wireless devices  104  of other users  105 . The community wireless device  104  may provide detection even when the user  103  is not carrying a mobile device  102  or carries the mobile device  102  intermittently. For example, the user  103  can carry an authorized tracking device, such as owner tracking device  710  or shared tracking device  712 , for instance, coupled to the user&#39;s keys. Continuing with this example, the user can also have an unauthorized tracking device attached to the user or an object that moves with the user. Even if the user does not carry the mobile device  102 , the tracking system  100  communicates with one or more community mobile devices  104  of other users  105  to detect wireless signals from the authorized tracking device of the user  103 , and wireless signals from the unauthorized tracking device. The tracking system  100  collects tracking data associated with both tracking devices from community wireless devices  104  and detects the close proximity of the tracking devices in multiple locations at different times, resulting in identification of the unauthorized device. The tracking system  100  may send a notification to the mobile device  102  or other computing device of the user  103  when the unauthorized tracking device is detected. The tracking system  100  may remotely deactivate the unauthorized tracking device or perform other remedial actions. 
     In some embodiments, a tracking device includes a network connection to the tracking system  100 . For example, the tracking device is an authorized tracking device that moves with the user. Using techniques as discussed herein for the mobile device  102 , the tracking device may be configured to scan and report tracking data of other wireless devices, including unknown devices which may be unauthorized tracking devices. Tracking devices may identify and remember one another (i.e. via a mesh topology), generate tracking data, and report the tracking data to the tracking system  100  via the network  108 . 
       FIG.  9    illustrates a process  900  for identifying an unauthorized tracking device, according to one embodiment. Method  900  may be performed at  820  of method  800  to identify unauthorized tracking devices from unknown wireless devices detected by the mobile device  102 . It should be noted that although reference is made herein to the performance of the process  900  by the tracking system  100 , in some embodiments, the process can be performed by a mobile device or other suitable device. 
     At  905 , the tracking system  100  may be configured to identify an unknown device from a set of wireless devices detected by the mobile device  102 . Identification of the unknown device may be performed by referencing a listing of known devices accessible to the tracking system  100 . Known devices may include authorized devices and unauthorized devices. 
     Device authorization may be predefined, such as by referencing an authorized device list and/or unauthorized device list. The known device list(s) may be stored and compared with received device IDs of detected wireless devices to determine whether the wireless devices associated with the received device IDs are known devices. A wireless device that fails to include a known device ID, may be determined as an unknown device. Various types of devices may be defined as authorized devices, such as owner tracking device  710 , shared tracking device  712 , or authorized wireless device  714 . The tracking system  100  may be configured to determine that a wireless device fails to be a known device, and thus classifies the device as an unknown device. 
     In some embodiments, known devices may include shared tracking devices  712  owned by other users. Such devices may be identified by on querying an associated user (e.g., friend, connection, etc.) of the user  103  from the user database  210 , identifying the owner tracking device of the associated user, and determining that the owner tracking device of the associated user is a shared tracking device  712  of the user  103 . 
     At  910 , the tracking system  100  may be configured to generate tracking data based on communication signals between the unknown device and the mobile device  102  over time. The tracking data represents the connection behavior of the unknown device with respect to the mobile device  102 . The mobile device  102  may be configured to communicate with nearby wireless device over time (e.g., polling at time intervals). For each wireless device, the tracking data may indicate a connection status over time between the wireless device and the mobile device  102 . Therefore, tracking data may be used to evaluate the characteristics or properties of communication signals, and used to determine whether the wireless device is tracking the user. The tracking data may further include communication signal characteristics, such as signal strength, over time. 
     At  915 , the tracking system  100  may be configured to determine a tracking device value for the unknown device based on the tracking data. The tracking device value refers to a measure of likelihood that the unknown device is behaving like a tracking device  106 . The tracking device value may be used as criteria for triggering various unknown device handling tasks. These tasks may include sending warnings or notifications to the mobile device  102  regarding an unknown device and allowing the user to classify the unknown device as an authorized device or unauthorized device. In another example, a tracking device value indicating a high likelihood of user tracking may trigger programmatic remedial actions, such as deactivation of the unauthorized tracking devices by the tracking system  100 . 
     In some embodiments, the tracking device value may be determined based on the duration of connection between an unknown device and the mobile device  102 . For example, an unknown device that has not been previously detected, but has followed the user for several minutes, may indicate a higher likelihood that the unknown device is a tracking device. An unknown device that maintains a connection for only a short period of time, and with no subsequent connections for example, may indicate a lower likelihood that the unknown device is a tracking device. 
     In some embodiments, the tracking device value may also be determined based on a location data of the mobile device  102 . For example, a connection that is maintained while the user is in motion may indicate a higher likelihood that the unknown device is tracking the user (e.g., the device is attached to the user, an object being transported by or transporting the user, etc.). As a user moves around with an attached unauthorized device, the probability that the unauthorized device is being used to track movement or the behavior of an object increases. 
     In some embodiments, the tracking device value may be determined based on repeated or recurring connections between the unknown device and the mobile device  102 . If the unknown device and the mobile device  102  connect at intermittent (e.g., daily, twice a day, etc.) or otherwise at repeated times, this may indicate that the unknown device is a tracking device. For example, a tracking device may be planted on the user&#39;s car, and thus becomes detected by the mobile device  102  each time the user is within or near the car. Thus, an unknown device may be more likely to be a tracking device if there are recurring connections. 
     As discussed in the preceding examples, the tracking device value may be determined based on algorithmic transformations of the tracking data. An algorithmic transformation maps or transforms the tracking data input to a tracking device value. In some embodiments, tracking device values may be determined based on machine learning algorithm. For example, the algorithmic transformation may be generated based on generating training sets (e.g., of ground truth input/output examples), and applying the training sets to a neural network to generate a trained neural network model. The neural network model relates the tracking data input to an output tracking device value. A tracking device value for an unknown device may be determined based on applying input tracking data to the trained neural network model and receiving a tracking device value as an output. 
     In some embodiments, the tracking data of the unknown device is generated by one or more community mobile devices  104  of other users  105 . Here, the user  103  that is being tracked is not required to carry the mobile phone  102  to receive unauthorized tracking device detection services from the tracking system  100 . For example, the user carries an authorized tracking device that is detected by community mobile devices  104 . If the user is also being tracked by an unauthorized tracking device, the community mobile devices  104  also detect the unauthorized tracking device. The community mobile devices  104  generate tracking data representing the connection behavior of the unknown device and an authorized tracking device of the user  103 . The tracking data is wirelessly detected by the one or more community mobile devices  104  of other users  105 . For example, different community mobile devices  104  may detect wireless signals from both the unknown device and the authorized tracking device of the user  103  over time, and at different locations. The tracking system  100  may be configured to determine a tracking device value for the unknown device relative to the authorized tracking device based on the tracking data generated by the community mobile devices  104 . For example, tracking data that indicates the close proximity of the authorized tracking device and the unknown device at multiple locations and at different times may indicate a higher likelihood that the unknown device is behaving like a tracking device with respect to the user. 
     At  920 , the tracking system  100  may be configured to determine a tracking device warning threshold. The tracking device warning threshold defines a minimum likelihood that an unknown device is a tracking device for the unknown device to be of further interest. Put another way, communication signals that fail to exceed the tracking device warning threshold are sufficiently likely associated with non-tracking devices (e.g., wireless devices of others that happen to enter the communication range of the mobile device  102 ), and thus no user notification or other tracking device handling is required. 
     The tracking device warning threshold may define a minimum likelihood that a wireless device is a tracking device that is needed to initiate an alert to the user  103  regarding the wireless device. The alert may allow the user to provide a classification for the unknown device as authorized or unauthorized. 
     At  925 , the tracking system  100  is configured to determine whether the tracking device value of the unauthorized device exceeds the tracking device warning threshold. 
     The tracking device warning threshold may be set at a low value to provide more frequent warnings with higher probability of a false positive (e.g., a non-tracking device identified as tracking device). In contrast, the tracking device warning threshold may be set at a high value to provide less frequent warnings, but with a higher possibility of a false negative (e.g., a tracking device that fails to be identified as a tracking device until significant tracking activity has already occurred). In some embodiments, the tracking device warning threshold may correspond with the tracking data indicating that a wireless device was not previously detected, and then maintained a connection for at least a predefined time (e.g., 10 minutes). As such, when tracking data of a wireless device satisfies such characteristics, the tracking data can be determined to exceed the device warning threshold. 
     In response to determining that the tracking device value fails to exceed the tracking device warning threshold, process  900  may return to  910 , where additional tracking data may be generated based on communication signals between the unknown device and the mobile device  102 . The additional tracking data may then be used to determine tracking device values, and so forth. Thus, the tracking device value of a wireless device is subject to update over time to facilitate continuous monitoring for unknown devices. 
     Returning to  925 , in response to determining that the tracking device value exceeds the tracking device warning threshold, process  900  may proceed to  930 , where the tracking system  100  may be configured to provide a notification regarding the unauthorized device to the mobile device. 
     The notification may include a message or other indication that the unknown device has been detected by the mobile device  102  and has been flagged as a potential tracking device. The notification may include a user interface that facilitates user management of the unknown device. For example, the user interface may allow the user to classify the unknown device as an authorized device or unauthorized device. The mobile device  102  identifies the unknown device and notifies the user of the mobile device of a presence of the unknown device. 
     The notification may further include various informational displays that facilitate user management for the unknown device. For example, the notification may include a list of wireless devices connected with the mobile device  102 . The wireless devices may be identified based on device ID, device name, or other unique identifier. The list may include status indications for each wireless device indicating device status such as whether the wireless device is authorized, whether the device is a tracking device, and tracking device type (e.g., owner, shared, unauthorized, etc.). In some embodiments, the notification may further include a graph or other graphical representation of tracking data. For example, the graph may include tracking device values and/or connection signal strength as a function of time. Informational displays may also be provided to the display of the mobile device based on user request (e.g., even if no tracking device warning threshold has been exceeded). 
     At  935 , the tracking system  100  may be configured to determine whether the user  103  authorizes the unknown device. The determination may be based on a user generated message or user input provided in response to the notification at  930 . The mobile device  102  receives a confirmation from the user that the unknown device is an authorized or unauthorized device. In response to receiving the confirmation from the user, the mobile device  102  provides an indication that the unknown device is an authorized or unauthorized device to the tracking system  100 , where it is classified accordingly. 
     In response to determining that the user  103  authorizes the unknown device, method  900  may proceed to  940 , where the tracking system  100  may be configured to classify the unknown device as an authorized device. For example, the device ID of the unknown device may be stored in an authorized device list. As such, the authorized device is not identified as an unknown device at  905  for subsequent connections of the authorized device with the mobile device  102 . 
     Returning to  935 , in response to determining that the user  103  does not authorize the unknown device, or in response to an explicit classification of the device as suspicious or unauthorized by the user, method  900  may proceed to  945 , where the tracking system  100  may be configured to classify the unknown device as an unauthorized device. For example, the device ID of the unknown device may be stored in an unauthorized device list. As such, the unauthorized device is not identified as an unknown device at  905  for subsequent connections of the unauthorized device with the mobile device  102 . 
     At  950 , the tracking system  100  may be configured to determine a tracking device identification threshold for the unauthorized device. The tracking device identification threshold defines a minimum tracking device value needed to identify and classify a wireless device as a tracking device. The tracking device identification threshold may be a higher level threshold than the tracking device warning threshold discussed at  920 . Put another way, tracking data for some devices may be sufficiently characteristic of a tracking device to issue a user notification (e.g., higher than minimum 10% likelihood threshold), but insufficient to identify the device as being a tracking device with higher level certainty (e.g., 50% likelihood or greater). 
     The tracking device identification threshold and tracking device warning threshold are two examples of threshold values that may be applied to tracking device values. In various embodiments, more or fewer threshold values may be used. For example, a single threshold value may be used that triggers user notification, and identification as a tracking device. Here, unknown tracking devices may be identified from wireless devices within communication range of the mobile device. The user may be notified of presence of the unknown tracking device and may classify the unknown tracking device as being authorized or unauthorized as discussed above. 
     Each threshold value may be associated with different functionality and handling, ranging from a low intervention for low threshold value satisfaction (e.g., warning a user) to a high intervention for high threshold value satisfaction (e.g., deactivating a tracking device). In some embodiments, the tracking device warning threshold and/or tracking device identification threshold may be set by the user. 
     At  955 , the tracking system  100  may be configured to determine whether the tracking device value for the unauthorized device exceeds the tracking device identification threshold. For example, if a larger tracking device value corresponds with a higher likelihood of being a tracking device, then the tracking device value may be determined to exceed the tracking device identification threshold if the tracking device value exceeds the tracking device identification threshold. 
     In response to determining that the tracking device value fails to exceed the tracking device identification threshold, process  900  may return to  910 , where additional tracking data may be generated based on communication signals between the unauthorized device and the mobile device  102 , and determine tracking device values based on the communication signals. 
     Returning to  955 , in response to determining that the tracking device value exceeds the tracking device identification threshold, process  900  may proceed to  960 , where the tracking system  100  may be configured to identify and classify the unauthorized device as an unauthorized tracking device. As such, tracking device values and thresholds may be used to identify tracking devices from the wireless devices that are detected by the mobile device  102 . In response to the unauthorized device being identified as an unauthorized tracking device, various remedial actions may be performed as discussed at  940 - 960  of process  900 . 
     Privacy Preservation in a Tracking Device Environment with Complex Identifier Devices 
     As discussed with reference to  FIG.  6   , the complex identifier device detector  604  of the tracking system  100  is configured to detect tracking devices that rotate the identifier value they emit. Complex identifier devices may be configured to rotate identifier values (e.g., change the identifier value emitted) after a set interval of time. The detector  604  identifies these devices by recording communication signals received from devices within a local area (i.e. within the detection range) of a mobile device over an interval of time. If the detector  604  receives two or more communication signals detected by the mobile device with matching identifier values after the mobile device moves a distance greater than a communicative range of the unknown device within the interval of time, the detector  604  may tag the device as an unauthorized complex identifier tracking device and generate a notification indicating its presence for display by the mobile device. 
       FIG.  10    illustrates a process for identifying an unauthorized tracking device with a complex identifier (or rotating identifier), according to one embodiment. The method  1000  is configured to detect a complex identifier tracking device that is following a user  103 . The method  1000  relies on a user moving at least a distance greater than a predicted broadcast range of the unknown device during an interval of time, after which the device is predicted to rotate its identifier value. The combination of moving at least the broadcast distance within the interval of time ensures that the detected device is not a stationary device in the environment around the user and is in fact a device that is following the user. If the user does not move at least the broadcast distance within the interval of time, the tracking system  100  may be unable to differentiate between a device that is following the user  103  and a stationary device and may not generate a notification alerting the user. 
     The tracking system  100  detects  1010 , via a mobile device of a user, a first advertisement signal (i.e. communication signal) from an unknown device including a first identity of the unknown device. The first advertisement signal may be detected by the mobile device of the user and conveyed to the tracking system  100 . The advertisement signal may comprise identification information of the unknown device including a first identity or first identifier value. Upon receiving the first signal, the tracking system  100  may record the values associated with the advertisement signal (i.e. the first identity) as well as a time stamp and location of when and where the signal was received. 
     The tracking system determines  1020  that the mobile device has moved a distance greater than a broadcast range of the unknown device within the interval of time since the first signal was detected. The broadcast range may be determined by the tracking system  100  by analysis of the advertisement signal. For instance, the advertisement signal can include information identifying a manufacturer of the unknown device, or a identifying a transmission standard or protocol, and the tracking system  100  can determine the broadcast range of the unknown device based on the manufacturer or transmission standard or protocol. If the advertisement signal does not contain information about the broadcast range, the tracking system may use a default predicted value of the broadcast distance. The interval of time represents a period of time in which a complex identifier tracking device is predicted to change its identifier value. The tracking system  100  may determine the mobile device has moved at least the broadcast distance from the location where the signal was received by comparing the current location value (i.e. GPS coordinates) recorded by a location manager  322  of the mobile device  102  to the previous location value where the signal was received. 
     After the mobile device moves a distance greater than the broadcast range of the unknown device, the tracking system detects  1030  a second advertisement signal from the unknown device, the second advertisement signal including the first identity within the interval of time. Between the detection of the first and second advertisement signal including the first identifier, other advertisement signals may also be detected and recorded by the tracking system  100 . However, the tracking system  100  identifies a complex identifier device as following the user if it detects two advertisement signals with matching identities received within the interval of time and after a user has moved at least a broadcast distance from the location where the first signal was received. For example, the tracking system may detect a first advertisement signal with a first identifier and a second advertisement signal with a second identifier within the interval of time because the rate of sampling by the tracking system may not be aligned with the period of identifier rotation of the complex identifier device. In this example, the detection of a third advertisement signal with the second identifier may be necessary to identify the complex identifier device as following the user. In some embodiments, in order to guarantee that a same identifier is received within two consecutive identifier rotation periods, the tracking system may sample for advertisement signals at a rate that is less than two thirds of the identifier rotation rate of the complex identifier device. 
     In some embodiments, the tracking system  100  generates the interface on the mobile device only if the first and second advertisement signals including the first identifier have been detected for more than a threshold percentage of an interval of time. In this embodiment, the method  1000  prevents a false alarm from detecting a device that moves in and out of the detection area in two different locations. This situation may be caused by another person carrying a device walking past a user multiple times in a public place. In this example, the device carried by the person is not within a broadcast range of the user for more than a threshold percentage of an interval of time, thus enabling the tracking system to determine that the device is not following the user. 
     In some embodiments, the tracking system  100  records the signal strength of each signal received from a device over time. In these embodiments, the tracking system  100  may only determine that a device is following a user if the signal strength of the device stays within a threshold signal strength or within a threshold signal strength range. This prevents classification of devices that are moving independent of the user from being classified as unauthorized tracking devices following the user, since a device that is following the user will remain within a relatively constant distance from the user (and thus the signal strength will stay within a relatively constant range). 
     The tracking system, upon detecting a first and a second advertisement signal including the first identity, generates  1040  an interface on the mobile device of the user indicating the presence of an unknown device (a device tagged as following the user, or a “tagged device”). The interface generated on the user&#39;s mobile device may present remediation options for the user to choose between. For example, in one embodiment for compatible devices, the interface may present an option to the user that causes the tagged device to emit a sound (e.g., by transmitting an audio trigger signal corresponding to a manufacturer of the unknown device), enabling the user to find the tagged device. In another embodiment, the interface may present an option to the user that remotely deactivates the tagged device or sends a notification to the system associated with the tagged device. The interface may also display a signal strength indicator of the tagged device to enable the user to determine an approximate distance to the tagged device. In additional embodiments, the interface may display the tracking history of the tagged device such as the time and location at which the first advertisement signal was received to enable the user to determine when the device started following them. Information corresponding to a manufacturer of the tagged device (e.g., determined from advertisement signals of the tagged device) may also be recorded and displayed to the user within the interface such that the user can identify the device. 
       FIGS.  11 A , B, C illustrates an example use case for identifying an unauthorized tracking device with a complex identifier, according to one embodiment. Environment  1100  includes external tracking devices including stationary devices  1106 A-D, static identifier device  1108  and rotating identifier device  1110 . The user  103  has a mobile device on their person with a detection area  1104 . The detection area may represent the area in which the mobile device can detect signals emitted from other devices and may be dependent on the broadcast range of the devices. Beyond the detection area  1104 , the mobile device may not detect signals emitted by other devices. The threshold distance  1102  represents a distance greater than a broadcast distance of an external tracking device. If the user  103  moves beyond the threshold distance  1102  away from an external tracking device, the mobile device may not detect the signal emitted by the external tracking device. 
     In  FIG.  11 A , the user  103  is at a first location in the environment  1100 , where three external devices are within the detection area  1104  of the mobile device. The devices within the detection area  1104  at the first location are stationary device  1106 A, static identifier device  1108 , and rotating identifier device  1110 . Because the devices are within detection area  1104 , the mobile device can detect advertisement signals from  1106 A,  1108 , and  1110 . The mobile device detects signals with identifiers 1, 5, and 6 from the devices. Once the tracking system receives a notification of the advertisement signals from the mobile device, the tracking system  100  records the time and location at which each of the signals were received and records the contents of the advertisements signals. 
     In  FIG.  11 B , the user and their mobile device have moved at least a threshold distance  1102  away from the location of  FIG.  11 A . At this location, stationary device  1106 C, static identifier device  1108 , and rotating identifier device  1110  are within the detection area. Accordingly, the mobile device detects advertisement signals 2, 5, and 7 from the external devices. The tracking system  100  checks whether the mobile device location has changed by at least a threshold distance since receiving signals 1, 5, and 6. If so, the tracking system checks the identifier values (i.e. identities) in the advertisement signals to see if they match other signals received during the interval of time and after the threshold distance  1102  was traveled. At this location, the tracking system  100  detects that it has received the advertisement signal with identifier 5 twice. As such, the tracking system  100  tags static identifier device  1108  emitting identifier 5 as following the user  103 . The tracking system  100  then generates an interface on the mobile device indicating that static identifier device  1108  is following the user  103 . The interface may allow the user to mark the tagged device as an authorized device (i.e. a device that the user  103  is aware of) such that they will not be notified of that the device with the identifier 5 is an unknown device again. 
     Stationary devices  1106 A,  1106 B, and  1106 C will not be tagged as following the user in the example shown in  FIG.  11 B  because the tracking system  100  will have only detected their signals with identifier values (1, 2, and 4) once due to the user moving away from the devices or never being within range (i.e. within the detection area  1104 ) of the devices. Note, though, that rotating identifier device  1110  has been present in the detection area  1104  twice, in each of  FIG.  11 A  and  FIG.  11 B . However, during the time the user moved from the location of  FIG.  11 A  to the location of  FIG.  11 B , the rotating identifier device  1110  changed the identifier value in its advertisement signal from 6 to 7. Therefore, though the rotating identifier device  1110  has followed the user  103  between  FIGS.  11 A and  11 B , the tracking system has not yet tagged it as an unknown device because advertisement signal 6 does not match advertisement signal 7. 
     In  FIG.  11 C , the user  103  has moved again at least a threshold distance  1102  from the locations in  FIGS.  11 A and  11 B . At this location, the detection area  1104  includes stationary device  1106 D, static identifier device  1108 , and rotating identifier device  1110 . The tracking system  100  detects advertisement signals 3, 5, and 7 from the external devices within the detection area  1104 . Signal 3 has only been detected once, so stationary device  1106 D will not be tagged. Signal 5 from static identifier device  1108  has now been detected 3 times and the user was notified via a user interface on the mobile device while the user was at the location of  FIG.  11 B . If the user has marked the device as known they will not be notified of the presence of device  1108  again. Signal 7 has now been detected twice, once at the location of  FIG.  11 B  and once at the location of  FIG.  11 C , the second detection occurring after the user  103  has moved at least a threshold distance and within an interval of time corresponding to the interval in which the device  1110  rotates identifiers. Responsive to the second detection of advertisement signal 7, the tracking system tags the device as following the user  103  and generates a user interface indicating the presence of rotating identifier device  1110  to the user  103  on the mobile device. 
     Rotating identifier device  1110  underwent a cycle of identifier rotations during the interval of time between the events of  FIG.  11 A ,  FIG.  11 B , and  FIG.  11 C . In  FIG.  11 A  the device  1110  was emitting advertisement signal 6, in  FIG.  11 B  the device  1110  was emitting advertisement signal 7, and in  FIG.  11 C  the device  1110  was emitting advertisement signal 7. Thus, despite detecting the device  1110  for the second time in the embodiment of  FIG.  11 B , the tracking system  100  does not tag the device as a potentially unauthorized tracking device following the user, since the device identifier rotated from 6 to 7 while the user moved from the location of  FIG.  11 A  to the location of  FIG.  11 B . Instead, the tracking system  100  tags the device  1110  as a potentially unauthorized tracking device following the user only after the user moves to the location of  FIG.  11 C , when the device identifier 7 is received from the device for the second time, during an interval between identifier rotations by the device  1110 , and after the user moves a distance greater than a broadcast range of the device  1110 . 
     Additional Considerations 
     The foregoing description of the embodiments of the invention has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. 
     Any of the devices or systems described herein can be implemented by one or more computing devices. A computing device can include a processor, a memory, a storage device, an I/O interface, and a communication interface, which may be communicatively coupled by way of communication infrastructure. Additional or alternative components may be used in other embodiments. In particular embodiments, a processor includes hardware for executing computer program instructions by retrieving the instructions from an internal register, an internal cache, or other memory or storage device, and decoding and executing them. The memory can be used for storing data or instructions for execution by the processor. The memory can be any suitable storage mechanism, such as RAM, ROM, flash memory, solid state memory, and the like. The storage device can store data or computer instructions, and can include a hard disk drive, flash memory, an optical disc, or any other suitable storage device. The I/O interface allows a user to interact with the computing device, and can include a mouse, keypad, keyboard, touch screen interface, and the like. The communication interface can include hardware, software, or a combination of both, and can provide one or more interfaces for communication with other devices or entities. 
     Some portions of this description describe the embodiments of the invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. 
     Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. 
     Embodiments of the invention may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     Embodiments of the invention may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein. 
     Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.