TWI849290B - Passive asset tracking using observations of wi-fi access points - Google Patents

Abstract

A method of passive asset tracking using observations of Wi-Fi access points includes associating unique identifying information of a Wi-Fi access point with a moveable asset in an asset tracking database, where the Wi-Fi access point is disposed on, attached to, or integrated, receiving observation data from a Wi-Fi AP Database including the unique identifying information of the Wi-Fi access point and location information of the Wi-Fi access point, determining a location of the moveable asset based, at least in part, on the observation data of the Wi-Fi access point, and storing the location of the moveable asset in the asset tracking database. There is no communication between the asset tracking database and one or more wireless devices that report an encounter with the Wi-Fi access point, comprising observation data, to the Wi-Fi AP Database.

Description

Passive asset tracking using observations from Wi-Fi access points

The present invention relates to passive asset tracking using observation of Wi-Fi access points. CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application No. 16/907,806, filed on June 22, 2020, and issued on November 17, 2020 as U.S. patent No. 10,841,749, which is a continuation-in-part of U.S. patent application No. 16/570,195, filed on September 13, 2019, and issued on July 28, 2020 as U.S. patent No. 10,728,709.

This application is a continuation-in-part of U.S. patent application No. 16/812,471, filed on March 9, 2020, and published on November 24, 2020 as U.S. patent No. 10,848,934, which is a continuation-in-part of U.S. patent application No. 16/570,195, filed on September 13, 2019, and published on July 28, 2020 as U.S. patent No. 10,728,709.

This application is a continuation-in-part of U.S. patent application No. 16/812,612, filed on March 9, 2020 and published on November 24, 2020 as U.S. patent No. 10,848,935, which is a continuation-in-part of U.S. patent application No. 16/570,195, filed on September 13, 2019 and published on July 28, 2020 as U.S. patent No. 10,728,709.

All of the patent applications referenced above are hereby incorporated by reference in their entirety.

Wireless networking refers to the use of electromagnetic signaling to exchange information wirelessly between network nodes. Standards-setting organizations, such as the Institute of Electrical and Electronics Engineers ("IEEE"), coordinate, develop, publish, and maintain technical standards that facilitate the implementation of wireless networking standards, which ensure compatibility between competing OEMs and thereby seek to achieve widespread adoption of their respective technologies. The broad IEEE 802.11 standard specifies Wireless Local Area Network ("WLAN") technology, commonly referred to as Wi-Fi, which facilitates wireless communication between devices and often acts as a bridge to networks carrying Internet protocol traffic. Wi-Fi typically operates in the radio portion of the electromagnetic spectrum in the 2.4 GHz or 5 GHz bands.

In its first iteration, the IEEE 802.11a/b standards specified transfer rates of up to 11 Mbps at ranges of up to 150 feet. The IEEE 802.11g amendment implemented various improvements, including Orthogonal Frequency Division Multiplexing (OFDM), to increase the transfer rate to up to 54 Mbps while maintaining backward compatibility with IEEE 802.11b. The IEEE 802.11n amendment added Multiple Input Multiple Output (MIMO) functionality, in which multiple transmitters and receivers operate simultaneously at one or both ends of the link to facilitate transfer rates of up to 300 Mbps and even higher with the use of additional antennas. The IEEE 802.11ac amendment adds support for spatial streams and increases channel width to substantially increase transfer rates from 433 Mbps to several Gbps, operating only in the less crowded 5 GHz band and at ranges of up to 300 feet or more.

The IEEE 802.11 standard is still an evolving technology standard, and future amendments will likely seek to increase transfer rates, improve connectivity in challenging environments, and enhance security. As a result, Wi-Fi remains the world's most widely used wireless network connection standard.

According to one aspect of one or more specific examples of the present invention, a method for passive asset tracking using observations of Wi-Fi access points includes: associating unique identification information of a Wi-Fi access point with a movable asset in an asset tracking database, wherein the Wi-Fi access point is placed on, attached to, or integrated with the movable asset; receiving observation data from a Wi-Fi AP database, the observation data including the unique identification information of the Wi-Fi access point and location information of the Wi-Fi access point; determining a location of the movable asset based at least in part on the observation data of the Wi-Fi access point; and storing the location of the movable asset in the asset tracking database. There is no communication between the asset tracking database and one or more wireless devices, and the one or more wireless devices report an encounter with one of the Wi-Fi access points to the Wi-Fi AP database, the report including observation data.

According to one aspect of one or more specific examples of the present invention, a method for passive asset tracking using observations of a Wi-Fi access point includes: associating unique identification information of a Wi-Fi access point with a movable asset in an asset tracking database, wherein the Wi-Fi access point is placed on, attached to, or integrated with the movable asset; receiving first observation data from one or more direct reporting wireless devices that encounter the Wi-Fi access point, the first observation data including the unique identification information of the Wi-Fi access point and first location information of the Wi-Fi access point; and receiving a first observation data from a Wi-Fi access point. The AP database receives second observation data, the second observation data including the unique identification information of the Wi-Fi access point and second location information of the Wi-Fi access point; determines a location of the movable asset based at least in part on the first observation data and/or the second observation data of the Wi-Fi access point; and stores the location of the movable asset in the asset tracking database. There is no communication between the asset tracking database and one or more indirect reporting wireless devices, and the one or more indirect reporting wireless devices report their respective encounters with the Wi-Fi access point to the Wi-Fi AP database, the reports including the second observation data.

According to one aspect of one or more specific examples of the present invention, a method for passive asset tracking using observations of Wi-Fi access points includes: associating unique identification information of a Wi-Fi access point with a movable asset in an asset tracking database, wherein the Wi-Fi access point is placed on, attached to, or integrated with the movable asset; receiving observation data from one or more wireless devices that encounter the Wi-Fi access point, the observation data including the unique identification information of the Wi-Fi access point and location information of the Wi-Fi access point; determining a location of the movable asset based at least in part on the observation data of the Wi-Fi access point; and storing the location of the movable asset in the asset tracking database.

Other aspects of the invention will be apparent from the following description and the scope of the claims.

One or more specific examples of the present invention are described in detail with reference to the accompanying drawings. For consistency, similar elements are represented by similar figure labels in the various figures. In the following detailed description of the present invention, specific details are described in order to provide a thorough understanding of the present invention. In other cases, in order to avoid confusing the description of the present invention, the aspects that are well known to those with ordinary knowledge in the art are not described.

Known asset tracking systems use dedicated and complex hardware and software systems to track physical assets typically within the confines of a fixed location (e.g., within a warehouse) or from door to door at one or more fixed locations (e.g., tracking departures from a warehouse and exits from a dealership). Some asset tracking systems use simple printed asset tracking labels that are configured to be optically read by a reading device such as a barcode reader or a Quick Response ("QR") reader. Other asset tracking systems use asset tracking tags that are configured to be read by a short-range communication device in the vicinity of the tag using, for example, Near-Field Communication (NFC), Bluetooth Low Energy (BLE), Radio-Frequency Identification (RFID), or other short-range communication technologies. Other asset tracking systems still use asset tracking tags that are configured to be read at a distance using a Long Range (LoRa) network or cellular communications. In some cases, asset tracking systems use asset tracking tags that are able to determine their own location using a Global Positioning System (GPS) and report their own location directly to the asset tracking system via a communication network. However, such systems require large amounts of power, unimpeded access to satellite signals, and the ability to communicate to self-report their location.

These known asset tracking systems may be referred to as closed network systems because dedicated hardware and software systems are purposefully deployed and engaged in the asset tracking mission. Either the asset tag must be read directly by a reader or short range communication device in the vicinity of the tag, or the asset tag must be able to determine its own location and report its own location directly to the asset tracking system. Thus, an inherent limitation in known closed network asset tracking systems is the requirement that the tagging, tracking, hardware and software systems must be purposefully deployed, across areas of coverage, and affirmatively perform and manage the asset tracking mission. This requires a significant investment in expensive hardware and software systems, as well as hiring and training personnel for their use. Furthermore, in a widespread deployment of assets across many locations (perhaps even around the world), deploying and managing conventional closed network asset tracking systems is extremely difficult (if not impossible) and cost-prohibitive.

Thus, in one or more embodiments of the present invention, methods and systems for passive asset tracking use observations of Wi-Fi access points to passively track mobile assets. In certain embodiments, a Wi-Fi access point may be placed on, attached to, or integrated with the mobile asset to be tracked and logically associated in an asset tracking database. The mobile asset may then be deployed in the field or otherwise used in a typical manner. In contrast to closed network asset tracking systems, mobile assets are tracked passively (without requiring the user of the wireless device to be aware that he or she is participating in an asset tracking mission) only when a Wi-Fi enabled wireless device encounters the mobile asset's Wi-Fi access point (logically associated in an asset tracking database). In certain specific embodiments, when one or more wireless devices enter the Wi-Fi signaling range of a Wi-Fi access point associated with a mobile asset to be tracked, the wireless device reports the encounter with the Wi-Fi access point to a Wi-Fi AP database that is typically used to improve location services. The report includes observation data that includes at least unique identification information for the encountered Wi-Fi access point and location information that can be used to determine the location of the Wi-Fi access point. The asset tracking database may receive observations directly from one or more reporting wireless devices that encounter a Wi-Fi access point and/or indirectly from a Wi-Fi AP database that receives observations from one or more reporting wireless devices that encounter a Wi-Fi access point and report the observations to the Wi-Fi AP database. The terms "directly" and "indirectly" are used with reference to the asset tracking database. The asset tracking database may determine the location of a movable asset based at least in part on the observations of an associated Wi-Fi access point. In this manner, movable assets may be deployed anywhere in the world using Wi-Fi access points that do not need to be associated with any wireless device or provide any network connectivity of any kind. Every smartphone in the world that happens to come within Wi-Fi range of a Wi-Fi access point (even if only temporarily) can anonymously and unknowingly participate in the asset tracking mission by reporting observations of the Wi-Fi access point, which the asset tracking database can receive and use to determine the location of movable assets.

A method and system for passive asset tracking utilizes existing infrastructure inherent in smartphones and smartphone operating systems to report unique identification information of Wi-Fi access points encountered and their locations for use in improving the accuracy of location-based services. Advantageously, Wi-Fi wireless network discovery protocols and smartphones' inherent Wi-Fi access point reporting features can be used in concert to passively track Wi-Fi access points associated with movable assets by one or more wireless devices using publicly accessible Wi-Fi signals and in passive scanning applications completely anonymously with respect to asset tracking tasks, without requiring the wireless devices to authenticate with, associate with, or establish connectivity to any particular Wi-Fi access point.

FIG. 1 shows a known Wi-Fi wireless network 100. A Wi-Fi access point 110 facilitates wireless connectivity between one or more of the wireless devices and, in a configuration including an integrated router, may act as a bridge between the wireless devices (e.g., 120 , 130 , 140 , and 150 ) and an upstream network connection (such as an Internet connection provided by a broadband modem 105 ). In conventional use, a wireless connection may be established between one or more wireless devices (e.g., 120 , 130 , 140 , and 150 ), including, for example, a television 120 , a computer 130 , a tablet 140 , a smart phone 150 , or any other wireless device and a Wi-Fi access point 110 , thereby allowing the wireless devices (e.g., 120 , 130 , 140 , and 150 ) to communicate with each other and/or access the Internet via a broadband modem 105. Wi-Fi access points 110 are commonly found in homes, offices, and public places, where Wi-Fi access points are often referred to as Wi-Fi hotspots. Although the number of Wi-Fi access points 110 has not been definitively counted, it is believed that there are over 13 billion Wi-Fi access points (e.g., 110 ) in the world. Efforts to map Wi-Fi signal coverage indicate that most modern cities are covered with publicly accessible Wi-Fi signals. Notwithstanding the foregoing, one of ordinary skill in the art will recognize that a Wi-Fi wireless network 100 does not require a broadband modem 105 or Internet connectivity and may be used purely as a wireless network to facilitate wireless communications between one or more wireless devices (e.g., 120 , 130 , 140 , and 150 ).

FIG. 2A illustrates a passive scanning mode 200 as part of the IEEE 802.11 Wi-Fi wireless network discovery process. Wi-Fi wireless network discovery is a process by which a wireless device identifies and potentially authenticates to, associates with, and establishes data exchange connectivity with an in-range Wi-Fi access point (e.g., 110 ). In the passive scanning mode, one or more wireless devices (e.g., 150 ) listen for beacon frames (e.g., 220 ) broadcast at periodic intervals by one or more in-range Wi-Fi access points (e.g., 110 ) to announce the presence of their respective Wi-Fi wireless networks. A beacon frame (e.g., 220 ) is a type of Wi-Fi management frame that includes information about a broadcast Wi-Fi access point (e.g., 110 ) to facilitate potential authentication, association, and connectivity. Each beacon frame (e.g., 220 ) includes a Service Set Identifier ("SSID"), which is typically a user-given name for a broadcast Wi-Fi wireless network, and information that uniquely identifies the Wi-Fi access point (e.g., 110 ), including but not limited to a unique Basic Service Set Identifier ("BSSID") or Media Access Control ("MAC") address of the Wi-Fi access point (e.g., 110 ) or its broadcast band. As part of the same wireless network, multiple Wi-Fi access points (e.g., 110 ) may share the same SSID, but each Wi-Fi access point (e.g., 110 ) will have unique identification information, including, for example, a unique BSSID. In addition, dual- or multi-band Wi-Fi access points (e.g., 110 ) that broadcast on multiple bands may have a unique BSSID for each band on which the access points broadcast. Typically, a block of BSSIDs is assigned to manufacturers by a self-regulatory agency to allow the manufacturer to use the BSSID for the equipment it produces. Thus, the BSSID of each Wi-Fi access point or its band should be truly unique and distinguishable from all other BSSIDs.

In the example depicted in the figure, a wireless device 150 , such as a smart phone, may be located within the broadcast range of Wi-Fi access points 110a , 110b , and 110c , even if only temporarily passing through the broadcast range. Each Wi-Fi access point 110a , 110b , and 110c may periodically broadcast its respective beacon frame 220a , 220b , and 220c , thereby announcing the presence of its respective Wi-Fi wireless network. The wireless device 150 may listen for and receive the beacon frames 220a , 220b , and 220c from the Wi-Fi access points 110a , 110b , and 110c in range. In known applications, a user of a wireless device 150 who wishes to join a Wi-Fi wireless network may optionally select the SSID, sometimes referred to as the network name, of the wireless network to which he wishes to join via the operating system of his device. Sometimes, the wireless device 150 may automatically connect to a previously joined Wi-Fi wireless network based on user preferences. Once connectivity is established, the wireless device 150 may communicate 290 with the Wi-Fi access point 110a , thereby exchanging data via the Wi-Fi access point 110a and possibly accessing other networks, such as an upstream Internet connection (e.g., 105 of FIG. 1 ). Notably, wireless devices (e.g., 150 ) passively scanning 200 beacon frames (e.g., 220a , 220b , and 220c ) relative to Wi-Fi access points (e.g., 110a , 110b , and 110c ) within reception range are completely anonymous until such time as they choose to authenticate with and associate with a particular Wi-Fi access point (e.g., 110a ). Unless and until a user of wireless device 150 selects a particular Wi-Fi access point (e.g., 110 ) and its Wi-Fi wireless network to authenticate with, associate with, and establish data connectivity with, wireless device 150 may actively receive Wi-Fi signals publicly broadcast by Wi-Fi access points 110a , 110b , and 110c , as well as any other Wi-Fi access points it may encounter, while remaining completely anonymous. However, wireless device 150 records information about the Wi-Fi access points (e.g., 110 ) it encounters, even though such wireless devices never formally join the network, typically unbeknownst to the user, as discussed in greater detail herein.

FIG2B illustrates an active scanning mode 205 as part of IEEE 802.11 Wi-Fi wireless network discovery. In contrast to a passive scanning mode (e.g., 200 of FIG2A ), active scanning mode 205 is a type of Wi-Fi wireless network discovery process in which the wireless device 150 broadcasts a probe request frame 230 to a specific (e.g., 110a ) or all Wi-Fi access points (e.g., 110a , 110b , and 110c ) within Wi-Fi signaling range. The probe request frame 230 is a type of Wi-Fi management frame, which may include information about a specific Wi-Fi access point (e.g., 110a ) with which the wireless device 150 wishes to associate, sometimes referred to as a directed probe request, or the probe request frame may be a probe for all available Wi-Fi access points (e.g., 110a , 110b , 110c ) within Wi-Fi signaling range, sometimes referred to as a null probe request. In response, the in-range Wi-Fi access points 110a , 110b , and 110c transmit probe response frames 240a , 240b , and 240c , which include substantially similar information as a beacon frame (eg, 220 of FIG. 2A ) including their respective SSIDs and BSSIDs.

In contrast to passive scanning (e.g., 200 of FIG. 2A ) in which each Wi-Fi access point (e.g., 110 ) broadcasts its respective beacon frame (e.g., 220 of FIG. 2A ) on a particular channel, in active scanning mode 205 , wireless device 150 may broadcast probe request frames 230 across all available channels for the associated frequency band. In this manner, wireless device 150 may, for example, select a Wi-Fi access point (e.g., 110 a ) that temporarily provides the strongest received signal strength and quality. However, even when a particular wireless device 150 authenticates and associates with a particular Wi-Fi access point (e.g., 110a ), the wireless device 150 may leave the channel and continue to send probe request frames (e.g., 230 ) on other channels. By continuing to actively probe for Wi-Fi access points (e.g., 110 ), the wireless device 150 may maintain a list of known Wi-Fi access points (e.g., 110 ), which may facilitate roaming if the wireless device 150 moves out of range of the currently associated Wi-Fi access point (e.g., 110a ) or requires a better connection. Compared to the passive scanning mode (e.g., 200 of FIG. 2A ), the active scanning mode 205 only requires the wireless device 150 to send a probe request frame 230 on a specific channel within a designated frequency band and then listen for a relatively small amount of time compared to the passive scanning (e.g., 200 of FIG. 2 ). Thus, compared to the broadcast nature of the passive scanning operation (e.g., 200 of FIG. 2A ), the active scanning 205 presents a more direct and targeted approach to the Wi-Fi wireless network discovery process.

2C illustrates a sequence of IEEE 802.11 management frames 210 typically exchanged between a wireless device 150 and a Wi-Fi access point 110 as part of the Wi-Fi wireless network discovery process. The wireless device 150 must successfully identify (e.g., 220 , 230 , and 240 ), authenticate (e.g., 250 and 260 ), and associate (e.g., 270 and 280 ) with the Wi-Fi access point 110 in order to transmit data frames 290 containing data under the protocol. As previously discussed, Wi-Fi wireless network discovery refers to the process by which a wireless device 150 typically identifies a Wi-Fi access point 110 , authenticates to and associates with a Wi-Fi access point in range to enable data transfer with other devices and upstream network connections such as the Internet 105 .

The IEEE 802.11 standard specifies three different types of frames: management frames, data frames, and control frames, each of which is used for a specific purpose under the protocol. For example, management frames are used for supervisory functions including Wi-Fi wireless network discovery, data frames are used to transmit data once authenticated and associated, and control frames are used to control the transmission of data. As mentioned above, the IEEE 802.11 standard specifies two different scenarios in which a wireless device 150 may identify, authenticate to, and associate with a Wi-Fi access point 110 as part of the Wi-Fi wireless network discovery process.

In passive scanning mode, the wireless device 150 listens for beacon frames 220 , which are a type of management frame and are broadcast at periodic intervals by Wi-Fi access points 110 in range. Beacon frames 220 announce the presence of Wi-Fi access points 110 and include information that facilitates potential authentication, association, and ultimately data transmission. For example, the information includes the BSSID and SSID of the broadcasting Wi-Fi access point 110 . For example, a user of a wireless device 150 (a smartphone in this example) may open a Wi-Fi application on their device, view a list of SSIDs corresponding to Wi-Fi access points 110 in range that are broadcasting their respective beacon frames (e.g., 220 ), and select the specific SSID of the Wi-Fi wireless network they wish to join. When the user selects the SSID of a specific Wi-Fi access point 110 , the wireless device 150 transmits a probe request frame 230 , which is another type of management frame, to the specific Wi-Fi access point 110 that includes the capabilities of the wireless device 150 . In the active scanning mode, without necessarily receiving beacon frames 220 , the wireless device 150 may transmit a probe request frame 230 including the capabilities of the wireless device 150 to a specific Wi-Fi access point 110 or all Wi-Fi access points 110 in range. Thus, the Wi-Fi wireless network discovery process may be initiated by the Wi-Fi access point 110 broadcasting the beacon frame 220 or by the wireless device 150 transmitting the probe request frame 230. Regardless of which initiates the process, the remainder of the authentication and associated protocols are substantially the same.

After receiving the probe request frame 230 , if the Wi-Fi access point 110 has compatible parameters, the Wi-Fi access point 110 transmits a probe response frame 240 , which is another type of management frame, to the wireless device 150. The probe response frame 240 includes parameters typically included in a beacon frame 220 , which includes unique identification information and capabilities of the Wi-Fi access point 110. It is important to note that at this stage of the process, the wireless device 150 has not authenticated with and is not associated with the Wi-Fi access point 110 , and cannot transmit data in a data frame 290. After receiving the probe response frame 240 , the wireless device 150 transmits an authentication request frame 250 , which is another type of management frame, to the Wi-Fi access point 110 . The authentication protocol determines whether the wireless device 150 is authenticated to the Wi-Fi access point 110 , i.e., ensures permissions or access with respect to encryption (open or shared key encryption). Without going into the details of the authentication protocol (which is not necessary for purposes of describing the claimed invention), it is noted that the wireless device 150 typically cannot proceed with association and data transfer until it has successfully authenticated to the Wi-Fi access point 110 , as represented by the authentication response frame 260 , which is another type of management frame, thereby confirming successful authentication.

Once authenticated to the Wi-Fi access point 110 , the wireless device 150 transmits an association request frame 270 , which is another type of management frame, to the Wi-Fi access point 110. The association request frame 270 represents a request by the authenticated but not yet associated wireless device 150 to associate with the Wi-Fi access point 110 and enable data transfer via the data frame 290. The association request 270 includes information including, for example, the capabilities of the wireless device 150. After receiving the association request 270 , the Wi-Fi access point 110 compares the capabilities specified in the association request 270 to the capabilities of the Wi-Fi access point 110 to determine if they match. If there is a mismatch, the Wi-Fi access point 110 determines whether the differences are a problem that prevents association and data transfer. If the differences are not substantial, the Wi-Fi access point 110 transmits an association response 280 that is another type of management frame, thereby confirming a successful association. Upon receiving the association response 280 indicating a successful association with the Wi-Fi access point 110 , the wireless device 150 may exchange data 290 with the Wi-Fi access point 110 in data frames that are routed to their final destination via the bridged network connection (typically the Internet 105 ). It is worth noting that in order for the wireless device 150 to transmit data using the Wi-Fi access point 110 instead of the management frame, the wireless device 150 must authenticate and associate with the Wi-Fi access point 110 , thereby enabling the wireless device 150 to transmit and receive data 290. Similarly, until the wireless device 150 has authenticated and associated with the Wi-Fi access point 110 , the Wi-Fi access point 110 cannot transfer data in the data frame to the wireless device 150 .

FIG . 3A illustrates the subtypes of an IEEE 802.11 management frame. In a known management frame (e.g., 1100 of FIG. 11 ), the first octet is defined as a frame control field (e.g., 1110 of FIG. 11 ). The three subfields preceding the frame control field (e.g., 1110 of FIG. 11 ) are present in all IEEE 802.11 frames and include a protocol version (not shown), a frame type, and a frame subtype. The type of the frame subfield indicates whether the frame is a management frame, a data frame, or a control frame. The subtype of the frame subfield indicates a specific subtype of a frame within that type. In the figure, various subtypes of a management frame are shown. The subtype bit 310 represents a binary encoded subtype described by a subtype description 320 . For purposes of the following discussion, emphasis will be placed on the beacon frame and probe response frame subtypes of management frames. However, as can be seen from the enumerated list of management frames, other management frames for supervisory purposes related to identification, authentication, and association by a Wi-Fi wireless device (e.g., 150 ) may be used in accordance with one or more embodiments of the present invention.

FIG3B shows the structure of a known IEEE 802.11 management frame 300 representing the type of management frame transferred between a wireless device (e.g., 150 ) and a Wi-Fi access point (e.g., 110 ). The known management frame 300 includes several predetermined fields that are defined by the specification for the purpose of its protocol definition. For example, the MAC header 305 of the management frame 300 includes a frame control field 310 , a duration field 315 , a destination address field 320 , a source address field 325 , a BSSID 330 , and a sequence control field 335 . The management frame 300 further includes a frame body field 340 , which includes a number of subfields, including some subfields that may vary based on the subtype of the management frame 300 (e.g., 310 of FIG. 3A ). For example, the frame body field 340 includes a mandatory subfield 350 , which includes a timestamp subfield 360 , a beacon interval subfield 365 , a compatibility information subfield 370 , an SSID subfield 375 , and a possible supported rate subfield (not shown). The frame body field 340 may also include one or more optional subfields 355 , which may also vary based on the subtype of the management frame 30 (e.g., 310 of FIG. 3A ). The end of the management frame 300 includes a frame check sequence field 345 , which includes a detection code. Beacon frames, probe response frames, and other management frames during discovery of a Wi-Fi wireless network are in the form of known management frames 300 for the purpose of further identifying, authenticating to, and associating with a Wi-Fi access point (e.g., 110 ).

FIG. 4A illustrates various techniques that may be used to determine the location of a wireless device 150 and one or more Wi-Fi access points (e.g., 110). The wireless device 150 may be a smartphone as depicted in the example of a wireless device or any other type or class that may establish a cellular connection with one or more cell towers 410 that provides cellular network connectivity if it has cellular capabilities. In some cases, an established connection with a particular cell tower 410 may be used to establish the location of the wireless device 150 within a determinable radius of the particular cellular tower 410. Additionally, connectivity patterns with one or more cell towers 410 may be used to establish the location of the wireless device 150 within a determinable radius or even possible movement. However, such techniques are rarely used outside of law enforcement. In fact, wireless device 150 typically relies on GPS signals to determine its own location. Most wireless devices 150 include a GPS receiver (not shown separately) that is capable of receiving one or more GPS signals (not shown) from one or more GPS satellites (e.g., 420a , 420b , and 420c ) in Earth orbit. Typically, no matter where wireless device 150 is located, at least four GPS satellites (e.g., 420 ) are visible to the wireless device overhead anywhere in the world. Each GPS satellite 420a , 420b , and 420c transmits a GPS signal (not shown) at regular time intervals that includes information about the current location of the satellite and the current time. The GPS receiver of the wireless device 150 receives one or more of these GPS signals and calculates the distance of the GPS receiver from each satellite based in part on the time it takes for each respective GPS signal to arrive. If the wireless device 150 receives GPS signals from at least three GPS satellites 420a , 420b , and 420c , the location of the wireless device 150 can be determined with greater accuracy through a process known as trilateration. The GPS-derived location of the wireless device 150 can be determined continuously, periodically, or after executing software that requires location services (such as navigation software or a web browser used to search for nearby places). In open skies and good conditions, GPS is accurate within a radius of approximately 16 feet, but deteriorates near structures and obstacles.

In some cases, the wireless device 150 may use one or more in-range Wi-Fi access points 110a , 110b , and/or 110c to improve the accuracy of GPS location determination and, in situations where GPS is not available, determine its location based solely on Wi-Fi. As part of the Wi-Fi wireless network discovery process, the wireless device 150 typically determines the received signal strength, sometimes referred to as a received signal strength indication (RSSI), of the Wi-Fi signals broadcast by the in-range Wi-Fi access points 110a , 110b , and/or 110c . For the purposes of this discussion, it is assumed that the locations of one or more Wi-Fi access points 110a , 110b and/or 110c are already known to a certain degree of accuracy, and the identified Wi-Fi access points and received signal strength can be used to improve the accuracy of GPS location determination, and in situations when GPS is not available, the location of the wireless device 150 is determined based solely on Wi-Fi positioning. For example, the known location of Wi-Fi access point 110a and the received signal strength of Wi-Fi signals received therefrom may be used alone or in combination with the known locations or received signal strengths of other Wi-Fi access points 110b and 110c to refine or determine the location of wireless device 150 by one or more processes such as RSSI, fingerprinting, angle of arrival, time of flight, or other positioning techniques including triangulation and triangulation. Notably, the received signal strength of Wi-Fi signals received by the wireless device 150 from one or more Wi-Fi access points (e.g., 110a , 110b , and/or 110c ) is determined without requiring the wireless device 150 to authenticate, associate with, or otherwise establish connectivity with any particular Wi-Fi access point (e.g., 110a , 110b , or 110c ). Thus, the wireless device 150 may receive publicly broadcast Wi-Fi signals from Wi-Fi access points (e.g., 110a , 110b , or 110c ) in range with which the wireless device is not using or otherwise associated in any manner.

4B shows an overview of wireless device 150 reporting observations of encountered Wi-Fi access points 110a , 110b , and 110c to Wi-Fi AP database 730. In the discussion of FIG4A , it is assumed that the locations of one or more Wi-Fi access points (e.g., 110a , 110b , and 110c ) are known to a certain degree of accuracy. This assumption is true because wireless devices (e.g., 150 ) report the Wi-Fi access points (e.g., 110 ) they encounter in range and the location information to original equipment manufacturers, operating system developers, and/or third-party software developers, which maintain a database of observations of Wi-Fi access points (e.g., 110a , 110b , and 110c ), which is referred to herein as the Wi-Fi AP database 730. The Wi-Fi AP database 730 stores the reported observations 420 of Wi-Fi access points (e.g., 110a , 110b , and 110c ), which are generally used to enhance location services (i.e., prominent locations, location-based recommendations, location-based alerts, popular content near me, etc.) for end users. While this benefits the user of wireless device 150 in providing improved service, each wireless device (e.g., 150 ) typically reports information about the location of Wi-Fi access points (e.g., 110 ) it encounters on an ongoing and continuous basis without the user's awareness. This typically runs in the background as part of location-based services such as ^{Apple® iOS®} , ^{Google® Android®} , or ^Microsoft® , for example, and is typically available to third-party software developers for commercial use. In addition, many third-party software companies maintain their own Wi-Fi AP databases 730 of observation data including unique identification information and location information of Wi-Fi access points (e.g., 110 ), some of which provide access to their databases commercially for a fee. For example, Cisco Systems ^® , Facebook ^® , WhatsApp ^® , X-Mode ^® , Ruckus ^® , and Skyhook ^® provide commercial versions of Wi-Fi AP databases 730. It is worth noting that the information stored in such databases is typically obtained anonymously through publicly accessible Wi-Fi access point (e.g., 110 ) signals and in accordance with the terms and conditions of use of most smartphones, which typically provide users with the option to forgo participation in such services. Furthermore, the reporting of observations is typically anonymous, and no record is maintained of the reporting wireless device 150. Thus, each user of a wireless device 150 (such as a smart phone) reports observations of Wi-Fi access points (e.g., 110 ) that it encounters to the Wi-Fi AP database 730 on an ongoing and continuous basis, often without the user being aware that they are doing so, yet the user benefits from enhanced location determination when browsing the web to find nearby products or other location services.

Although well known in the art, FIG5 shows a block diagram of a conventional Wi-Fi access point 110. Conventional Wi-Fi access point 110 typically includes a printed circuit board and associated components (not shown) typically disposed within a housing or enclosure 510. Wi-Fi access point 110 typically includes: a processor 520 , which serves as the main computing and processing engine of the system; firmware 530 , which includes software instructions executed by processor 520 and controls the functionality of the system; a radio interface 540 , which transmits and receives information via one or more antennas 550 ; and a power supply 560 . In known applications, power source 560 is typically a DC power source, however, some industrial and commercial applications may be configured for use with AC power, and other applications may still be configured for use with optional battery power 570. Wi-Fi access point 110 may include integrated router capabilities (not separately illustrated).

In certain embodiments of the claimed invention, the Wi-Fi access point 110 may not include one or more features to reduce the size, complexity, and power consumption of the device. For example, if the Wi-Fi access point 110 is strictly used for asset tracking tasks, the router and bridge functionality may not be required and can be removed. In other embodiments of the claimed invention, a virtual Wi-Fi access point 110 may be used that does not need to act as an access point, but the virtual Wi-Fi access point only disguises or emulates the Wi-Fi wireless network discovery protocol or part thereof, thereby transmitting beacon frames, probe response frames, and/or other management frames as if it were a full-featured Wi-Fi access point 110 . Nonetheless, one of ordinary skill in the art will recognize that any Wi-Fi access point 110 , variant thereof, or other device capable of participating in at least a portion of the Wi-Fi wireless network discovery protocol (as if it were an actual Wi-Fi access point 110 ) may be used in accordance with one or more embodiments of the present invention.

6 illustrates an example of an application of passive asset tracking 600 according to one or more embodiments of the present invention. Specifically, in one or more embodiments of the present invention, one or more movable assets 610 , 620 , 630 , and 640 may be passively tracked by one or more wireless devices 150 that are within range of the movable assets 610 , 620, 630, and 640 or even enter and appear out of range and broadcast Wi-Fi signals, even though the wireless devices 150 or their users may not be aware that they are participating in an asset tracking mission. For example, in the depicted example, wireless device 150 may be a smartphone that is carried by a user while in motor vehicle 670 driving along street 660. The user's smartphone 150 may report observations of Wi-Fi access points 110a , 110b , 110c , and 110d that are encountered within range (even if only temporarily) to an asset tracking database (e.g., 710 of FIG. 7A ) and/or a Wi-Fi AP database (e.g., 730 of FIG. 7A ) without the user necessarily being aware of it. The asset tracking database (e.g., 710 of FIG. 7A ) can use one or more observations to determine the location of the movable asset 610 , 620 , 630 , or 640 . Advantageously, the movable assets (and associated Wi-Fi access points) do not require any network connectivity, can be deployed anywhere in the world, and the existing installation of the user of the smart phone 150 can be used to passively track the location of the movable assets 610 , 620 , 630 , and 640 .

Thus, for purposes of this disclosure, passive asset tracking means tracking an asset (e.g., 610 ) based on observations of a Wi-Fi access point (e.g., 110 ) without requiring any particular wireless device 150 to authenticate, associate with, or establish connectivity with any particular Wi-Fi access point (e.g., 110a or any other). Furthermore, passive asset tracking does not require a Wi-Fi access point (e.g., 110 ) associated with an asset (e.g., 610 ) to provide any network connectivity. In some specific examples of the present invention, one or more wireless devices 150 may report observation data of encounters with Wi-Fi access points (e.g., 110a , 110b , 110c , or 110d ) associated with assets (e.g., 610 , 620 , 630 , or 640 ) to a Wi-Fi AP database (e.g., 730 of FIG. 7A ). The asset tracking database (e.g., 710 of FIG. 7A ) may receive observation data from the Wi-Fi AP database (e.g., 730 of FIG. 7A ) containing location information to determine the location of one or more movable assets (e.g., 610 , 620 , 630 , or 640 ). In other specific examples of the present invention, one or more direct reporting wireless devices 150 may report first observation data of encounters with Wi-Fi access points (e.g., 110a , 110b , 110c , or 110d ) associated with the movable asset (e.g., 610 , 620 , 630 , or 640 ) to an asset tracking database (e.g., 710 of FIG. 7A ), and one or more indirect reporting wireless devices (e.g., 150 ) may report second observation data from a Wi-Fi AP database (e.g., 730 of FIG. 7A ). The Wi-Fi AP database (e.g., 730 of FIG. 7A ) may receive second observation data from one or more indirectly reporting wireless devices (e.g., 150 ) that encounter one or more Wi-Fi access points (e.g., 110 a , 110 b , 110 c , or 110 d ) associated with one or more assets (e.g., 610 , 620 , 630 , or 640 ). In yet other specific examples, one or more wireless devices 150 may report observations of encounters with Wi-Fi access points (eg, 110a , 110b , 110c , or 110d ) associated with assets (eg, 610 , 620 , 630 , or 640 ) to an asset tracking database (eg, 710 of FIG. 7A ). In all such specific examples, the Wi-Fi wireless network discovery process and the reporting of observations of encountered Wi-Fi access points (e.g., 110 ) can be advantageously used to passively track one or more assets (e.g., 610 , 620 , 630 , or 640 ) using publicly accessible Wi-Fi signals and in passive scanning applications for anonymity relative to asset tracking tasks without requiring any wireless device 150 to authenticate with, associate with, or join any particular Wi-Fi access point (e.g., 110 ). Additionally, one or more Wi-Fi access points (eg, 110a , 110b , 110c , or 110d ) associated with one or more assets (eg, 610 , 620 , 630 , or 640 ) are not required to provide any network connectivity.

Returning to the example depicted in the figure, one or more Wi-Fi access points 110a , 110b , 110c , and 110d may be disposed on, attached to, or integrated with one or more assets 610 , 620 , 630 , and 640 that may be deployed in a field 650. For purposes of illustration, infrastructure equipment 610 , 620 , 630 , and 640 are shown as examples of movable assets that may be tracked. However, one of ordinary skill in the art will recognize that any movable asset may be tracked according to one or more specific examples of the present invention.

It is important to recognize that Wi-Fi access points 110a , 110b , 110c , and 110d are not required to participate in any particular wireless network or provide any network connectivity. Advantageously, as part of the asset tracking task, Wi-Fi access points 110a , 110b , 110c , and 110d are only required to participate in part of the Wi-Fi wireless network discovery process. Specifically, each Wi-Fi access point 110a , 110b , 110c , and 110d disposed on, attached to, or integrated with assets 610 , 620 , 630 , and 640 may broadcast a beacon frame (e.g., 220 of FIG. 2C ) in a passive scanning mode (e.g., 200 of FIG. 2A ) and/or as part of an active scanning mode (e.g., 205 of FIG. 2B ), in response to a probe request frame (e.g., 240 of FIG. 2C ), wherein the beacon frame (e.g., 220 of FIG. 2C ) or the probe response frame (e.g., 240 of FIG. 2C ) includes information that uniquely identifies the Wi-Fi access point (e.g., 110b ) and, by proxy, identifies the particular asset (e.g., 620 ) itself. It is important to recognize that, other than the ability to participate in at least a portion of the Wi-Fi wireless network discovery process, it is not necessary for each movable asset to be tracked (e.g., 610 , 620 , 630 , and 640 ) to have any communication capabilities of any kind. One of ordinary skill in the art will recognize that beacon frames (e.g., 220 of FIG. 2C ), probe response frames (e.g., 230 of FIG. 2C ), or other management frames (e.g., 300 of FIG. 3A ) may contain other information that may be used as part of the asset tracking task in one or more embodiments of the present invention.

In certain specific examples, in a passive scanning mode (e.g., 200 of FIG. 2A ), Wi-Fi access points 110a , 110b , 110c , and 110d may be physically and logically associated with assets 610 , 620 , 630 , and 640, respectively, and broadcast beacon frames (e.g., 220 of FIG. 2C ) at regular time intervals, each of which includes information uniquely identifying a particular Wi-Fi access point (e.g., 110c ) and (for a person aware of the association) the asset (e.g., 630 ) logically associated with the Wi-Fi access point in an asset tracking database (e.g., 710 of FIG. 7A ). One or more wireless devices 150 may be within range of one or more Wi-Fi access points 110a , 110b , 110c , and 110d and receive one or more beacon frames (e.g., 220 of FIG. 2C ). As previously discussed, wireless devices 150 report observations via cellular or other connections. Each report of observations includes at least unique identification information (e.g., BSSID) of the encountered Wi-Fi access point (e.g., 110 ) and location information of the encountered Wi-Fi access point (e.g., 110 ). The location information may include coordinates such as latitude and longitude or other information that can be used to determine location. In some embodiments, the observation data for a given Wi-Fi access point (e.g., 110 ) may include one or more of the following: reporting the time, date, current location, speed, and direction of travel of the wireless device 150 at or near the time of the encounter, as well as the SSID, received signal strength, or other information related to the encountered Wi-Fi access point (e.g., 110 ). Additionally, the observation data may include any of the above-mentioned information from other in-range Wi-Fi access points (e.g., 110 ) encountered at or near the same time as the given Wi-Fi access point of interest (e.g., 110 ). The observation data is reported to the original equipment manufacturer of the wireless device 150 , the operating system developer of the operating system running on the wireless device 150 , or a third-party software developer, each of which maintains a Wi-Fi AP database (e.g., 730 of FIG. 7A ) and/or a dedicated asset tracking database (e.g., 710 of FIG. 7A ) used to track assets in the present invention.

While observation reporting patterns from wireless devices 150 are typically used to improve the accuracy of location-based services, here the observation data provides information that can be used to estimate the location of one or more Wi-Fi access points 110a , 110b , 110c , and 110d at a particular time and date without requiring any particular wireless device 150 to intentionally participate in any particular Wi-Fi wireless network. Thus, this information can be used to determine the location of one or more Wi-Fi access points 110a , 110b , 110c and 110d , and by proxy server, the location of one or more movable assets 610 , 620 , 630 and 640 with considerable accuracy, which can typically be further improved using well-known location improvement techniques used by wireless device 150 instead of GPS location determination or location-based services or used by wireless device 150 to enhance GPS location determination or location-based services.

In other specific examples, in the active scanning mode (e.g., 205 of FIG. 2B ), one or more wireless devices 150 may transmit a probe request frame (e.g., 230 of FIG. 2C ) that is not directed to any particular Wi-Fi access point (e.g., 110 ), thereby requesting all Wi-Fi access points 110 a , 110 b , 110 c , and 110 d within range to announce their presence. In response, the in-range Wi-Fi access points 110a , 110b , 110c , and 110d may transmit a probe response frame (e.g., 240 of FIG. 2C ) that includes information that uniquely identifies the responding Wi-Fi access point 110a , 110b , 110c , and 110d and (for a person aware of the association) the asset 610 , 620 , 630 , and 640 associated with the Wi-Fi access point. As previously discussed, the wireless device 150 reports observations via a cellular or other connection that include at least unique identification information (e.g., BSSID) of one or more Wi-Fi access points (e.g., 110 ) encountered and location information of one or more Wi-Fi access points (e.g., 110 ) encountered. The location information may include coordinates such as latitude and longitude or other information that can be used to determine location. In some embodiments, the observations for a given Wi-Fi access point (e.g., 110 ) may include one or more of the following: the time, date, current location, speed and direction of travel of the reporting wireless device 150 at or near the time of the encounter, and the SSID, received signal strength, or other information related to the encountered Wi-Fi access point (e.g., 110 ). Additionally, the observations may include any of the above-mentioned information from other in-range Wi-Fi access points (e.g., 110 ) encountered at or around the same time as the given Wi-Fi access point of interest (e.g., 110 ). The observations are reported to the original equipment manufacturer of the wireless device 150 , the operating system developer of the operating system running on the wireless device 150 , or a third-party software developer, each of which maintains a Wi-Fi AP database (e.g., 730 of FIG. 7A ) and/or a dedicated asset tracking database (e.g., 710 of FIG. 7A ) used in the present invention to track assets. The mobile operating system used on the smartphone 150 typically includes existing infrastructure to report observations to the operating system developer's Wi-Fi AP database (e.g., 730 of FIG. 7A ) in the background without the user being aware of it.

Although a single wireless device 150 is depicted, one of ordinary skill in the art will recognize that any number of wireless devices 150 may enter and leave the range of assets 610 , 620 , 630 , and 640 over time, each of which may independently report observations of the Wi-Fi access points 110a , 110b , 110c , and 110d that it encounters within range (and other information that may be applicable to the asset tracking task). In fact, tracking accuracy may be improved based on the number of observations made over time or may provide additional information, such as the movement of assets 610 , 620 , 630 , and 640 throughout the day or the speed at which the assets move or even the time when the assets leave the boundaries of the work site 650 .

7A illustrates a system 700 for passive asset tracking using observations of Wi-Fi access points (e.g., 110 ) according to one or more embodiments of the present invention. The system 700 may include a software application including an asset tracking database 710 executing on a computing system 800 and a client portal 720 that provides an asset tracking client (not shown) access to data stored in the asset tracking database 710 .

In some embodiments, the asset tracking database 710 may be a database software application that includes a backend that performs housekeeping software functions, a database management system (DBMS) that provides data processing functions, a data store (text database) containing observation data and other data, one or more management interfaces, and one or more other interfaces to the data contained in the asset tracking database 710. Those skilled in the art will recognize that the asset tracking database 710 may include other software, functions, and features known in the art necessary to deploy a database-type application according to one or more embodiments of the present invention. In some embodiments, the client portal 720 may be a web-based portal (not separately illustrated) that provides access to data stored in the asset tracking database 710. In other embodiments, the client portal 720 may be an independent software application (not separately illustrated) that provides access to data stored in the asset tracking database 710. In still other embodiments, the client portal 720 may be an interface that is integrated with the asset tracking database 710 to provide front-end access to the asset tracking database 710 . Those skilled in the art will recognize that, in accordance with one or more embodiments of the present invention, the client portal 720 may include software, functions, and features known in the art necessary to access the data contained in the database.

At the outset, it is important to recognize that everything depicted to the right of dividing line 740 in the figure (included only to enhance understanding) (except for the Wi-Fi access point 110 disposed on, attached to, or integrated with the asset 610 ) represents an existing infrastructure that represents a smartphone ecosystem of users and infrastructure. The behavior of wireless devices 150 participating in this ecosystem (including the inherent reporting characteristics of the Wi-Fi access points (e.g., 110 ) they encounter) can be exploited to passively track assets in situations that may not be realized with respect to the existing infrastructure according to one or more embodiments of the present invention.

In some embodiments, the asset tracking database 710 may obtain observation data indirectly from a third-party Wi-Fi AP database 730 , which typically receives observations from one or more wireless devices (e.g., 150b , 150c , and 150d ) based on reports of observation data used to improve the accuracy of location services. In such embodiments, the Wi-Fi AP database 730 may be a database that is independently established, operated, and maintained by an original equipment manufacturer of a wireless device (e.g., 150 ), an operating system developer of an operating system running on the wireless device (e.g., 150 ), or a third-party software developer, separately and separately from the asset tracking database 710 . For example, in some embodiments, the Wi-Fi AP database 730 may be a location-based service database of ^{Apple® iOS®} , ^{Google® Android®} , or ^Microsoft® , which is typically used to improve the accuracy of location determination for its respective end-users. In other embodiments, the Wi-Fi AP database 730 may be an observed database that includes unique identification information of Wi-Fi access points (e.g., 110 ) and information about the locations of Wi-Fi access points (e.g., 110 ), which is commercially provided by third parties including, for example, Cisco ^Systems® , ^Facebook® , ^WhatsApp® , X- ^Mode® , ^Ruckus® , and ^Skyhook® . One or more wireless devices (e.g., 150a ) may report observations to Wi-Fi AP database 730 for storage in the database of wireless devices, and asset tracking database 710 may obtain observations from Wi-Fi AP database 730 for use with asset tracking tasks without Wi-Fi AP database 730 , the reporting wireless devices (e.g., 150b , 150c , and 150d ), or their users being aware that they are participating in an asset tracking task. The observations reported to the Wi-Fi AP database 730 and the observations obtained by the asset tracking database 710 may or may not be the same, but the observations obtained by the asset tracking database 710 include at least unique identification information and location information of the encountered Wi-Fi access points 110 associated with the asset 610 .

In other embodiments, the asset tracking database 710 may obtain observations directly from one or more directly reporting wireless devices (e.g., 150a ), and may also obtain observations indirectly from the Wi-Fi AP database 730 , which receives observations from one or more indirectly reporting wireless devices (e.g., 150b , 150c , and 150d ). In such hybrid embodiments, observations may be reported directly to the asset tracking database 710 and/or indirectly to the asset tracking database 710 via the Wi-Fi AP database 730. The asset tracking database 710 may give a preference or value to directly reported observations that is different from indirectly reported observations. The priority selection may be used for location determination via the asset tracking database 710 .

In still other embodiments, the asset tracking database 710 may obtain observations directly from one or more direct reporting wireless devices (e.g., 150a ). In such embodiments, one or more wireless devices (e.g., 150a ) may report observations directly to the asset tracking database 710 for use in asset tracking tasks. Reports of observations may be received and processed as discussed in greater detail herein, and stored in the asset tracking database 710 , which may serve as a functional equivalent and replacement for the Wi-Fi AP database 730 .

For purposes of illustration, one or more Wi-Fi access points 110 may be placed on, attached to, or integrated with one or more movable assets 610 that need to be tracked. Unique identification information of the Wi-Fi access point 110 may be used to uniquely identify the asset 610 , which is physically and logically associated with the asset 610 in the asset tracking database 710. The one or more assets 610 may then be deployed in a field without the need for co-location. Advantageously, the deployed Wi-Fi access points 110 do not require any network or any kind of communication connectivity, nor do they need to receive GPS signals. As part of the Wi-Fi wireless network discovery process, these Wi-Fi access points only need to broadcast a beacon frame (e.g., 220 of FIG. 2C ) or respond to a probe request frame (e.g., 230 of FIG. 2C ) with a probe response frame (e.g., 240 of FIG. 2C ), each of which includes unique identification information of the Wi-Fi access point 110 .

When one or more wireless devices (e.g., 150 ) enter the range of one or more Wi-Fi access points 110 disposed on, attached to, or integrated with one or more assets 610 , each of the Wi-Fi access points 110 in range may broadcast its beacon frame (e.g., 220 of FIG. 2C ) or respond to a probe request frame (e.g., 230 of FIG. 2C ) with a probe response frame (e.g., 240 of FIG. 2C ), each of which includes information that can be used by the asset tracking database 710 to uniquely identify the Wi-Fi access point 110 and other information that may be applicable to asset tracking tasks, including beacon frames (e.g., 220 of FIG. 2C ) or probe response frames (e.g., 240 of FIG. 2C ). One or more wireless devices 150 may report observations of Wi-Fi access points 110 encountered within range directly to the asset tracking database 710 and/or the Wi-Fi AP database 730 based on the application or design.

As previously discussed, the wireless device 150 reports observations via a cellular or other connection. The observations include at least unique identification information (such as a BSSID) of one or more Wi-Fi access points 110 encountered and location information of one or more Wi-Fi access points 110 encountered. The location information may include coordinates such as latitude and longitude or other information that can be used to determine the location of the encountered Wi-Fi access point 110. In some specific examples, the observations for a given Wi-Fi access point 110 may include one or more of the following: the time, date, current location, speed and direction of travel of the reporting wireless device 150 at or near the time of the encounter, and the SSID, received signal strength, or other information related to the encountered Wi-Fi access point 110 . Additionally, the observation data may include any of the above-mentioned information from other in-range Wi-Fi access points (e.g., 110 ) encountered at or near the same time of encountering a given Wi-Fi access point of interest 110. In some cases, the current location of the reporting wireless device 150 at or near the time of the encounter may be used in conjunction with other information to establish the location of the encountered Wi-Fi access point 110 as of the time and date of the encounter.

The observation data may be reported directly to the Wi-Fi AP database 730 maintained by the original equipment manufacturer of the wireless device 150 , the operating system developer of the operating system running on the wireless device 150 , or a third-party software developer and/or the dedicated asset tracking database 710 of the present invention for tracking assets. If the wireless device 150 is not network-capable at the time of the encounter, one or more wireless devices 150 may report their encounter with the Wi-Fi access point 110 in range at the approximate encounter time or later. The asset tracking database 710 may use observation data obtained directly from one or more wireless devices (e.g., 150a ) and/or data obtained from the Wi-Fi AP database 730 (e.g., from 150b , 150c , and 150d ) to identify and locate one or more assets (e.g., 610 ), the data of which may be stored in the asset tracking database 710. Depending on the type of data received, the asset tracking database 710 may manipulate, extrapolate, or generate additional data stored therein based on available relevant information.

Although various specific examples of system 700 have been described, a person skilled in the art will recognize that subsets, supersets, or combinations of functions or features may be integrated, distributed, or excluded in whole or in part based on application or design according to one or more specific examples of the present invention, and that the present description is not intended to limit the types, kinds, or configurations of system 700 that may be implemented, including types, kinds, or configurations that include, integrate, distribute, separate, or exclude various aspects or features of one or more specific examples according to the present invention.

Continuing, FIG7B shows an example of observation data 740 of one or more Wi-Fi access points (e.g., 110 of FIG7A ) reported by a wireless device (e.g., 150a of FIG7A ) based on encounters according to one or more specific embodiments of the present invention. As previously discussed, the wireless device (e.g., 150a of FIG7A ) may report observation data via a cellular or any other network connection. Each report of the observation data may include at least unique identification information (e.g., BSSID) of one or more Wi-Fi access points (e.g., 110 of FIG7A ) encountered and location information of one or more Wi-Fi access points (e.g., 110 of FIG7A ) encountered. In some embodiments, the observation data for a given Wi-Fi access point (e.g., 110 ) may include one or more of the following: reporting the time, date, current location, speed, and direction of travel of the wireless device 150 at or near the time of the encounter, as well as the SSID, received signal strength, or other information related to the encountered Wi-Fi access point (e.g., 110 ). In addition, the observation data may include any of the above-mentioned information from other Wi-Fi access points (e.g., 110 ) encountered in range at or near the same time as the given Wi-Fi access point of interest (e.g., 110 ). The observation data may be reported directly to an asset tracking database (e.g., 710 of FIG. 7A ) or a Wi-Fi AP database (e.g., 730 of FIG. 7A ).

The unique identification information may include any information that can be used to uniquely identify an encountered Wi-Fi access point (e.g., 110 of FIG. 7A ), including any single field of a beacon frame (e.g., 220 of FIG. 2C ) or a probe response frame (e.g., 240 of FIG. 2C ) transmitted therefrom that can be used or reused to transmit information about the Wi-Fi access point (e.g., 110 of FIG. 7A ) or an asset associated with the Wi-Fi access point (e.g., 610 of FIG. 7A ). For example, due to the unique nature of the BSSID, the BSSID of a Wi-Fi access point (e.g., 110 of FIG. 7A ) can be used to uniquely identify the Wi-Fi access point (e.g., 110 of FIG. 7A ) and the asset (e.g., 610 of FIG. 7A ) on which the Wi-Fi access point is physically located, attached to, or integrated with the asset and logically associated with the asset in the asset tracking database (e.g., 710 of FIG. 7A ). However, the MAC address, SSID, and/or other fields included with the management frame can be used to further identify the Wi-Fi access point (e.g., 110 of FIG. 7A ) as an asset tracking type of Wi-Fi access point or otherwise used for asset tracking tasks. One of ordinary skill in the art will recognize that any information that can be used to uniquely identify a Wi-Fi access point (e.g., 110 of FIG. 7A ) transmitted from a Wi-Fi access point (e.g., 110 of FIG. 7A ) as part of a beacon frame (e.g., 220 of FIG. 2C ) or a probe response frame (e.g., 240 of FIG. 2C ) can be used in accordance with one or more embodiments of the present invention.

The location information may include coordinates reported for a Wi-Fi access point (e.g., 110 of FIG. 7A ) that represent a location such as latitude and longitude or any other information that may be used to determine the location of a Wi-Fi access point (e.g., 110 of FIG. 7A ) . For example, other information that may be used to determine the location of a particular Wi-Fi access point (e.g., 110 of FIG. 7A ) may include RSSI, fingerprinting, angle of arrival, time of flight, or other data associated with a Wi-Fi access point (e.g., 110 of FIG. 7A ) of interest or any information associated with other nearby Wi-Fi access points (e.g., 110 ) that may aid in location determination.

It will be appreciated by those skilled in the art that, according to one or more embodiments of the present invention, the type and kind of information reported by a reporting wireless device (e.g., 150 of FIG. 7A ) based on an encounter with a Wi-Fi access point (e.g., 110 of FIG. 7A ) may vary based on application or design, but must at least include unique identification information of the encountered Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information associated therewith.

Continuing, FIG7C shows an example of asset data 740 stored or generated by an asset tracking database (e.g., 710 of FIG7A ) according to one or more embodiments of the present invention. The asset tracking database (e.g., 710 of FIG7A ) can associate unique identification information (e.g., BSSID) of a specific Wi-Fi access point (e.g., 110 of FIG7A ) with a specific asset (e.g., 610 of FIG7A ) to identify the asset (e.g., 610 of FIG7A ) within the system (e.g., 700 of FIG7A ) on which the Wi-Fi access point is placed, attached to, or integrated with the specific asset. Once associated, an asset tracking database (e.g., 710 of FIG. 7A ) can use observations reported directly or indirectly by one or more wireless devices (e.g., 150 of FIG. 7A ) that encounter a Wi-Fi access point (e.g., 110 of FIG. 7A ) to passively track assets (e.g., 610 of FIG. 7A ), and in many cases, the wireless device (e.g., 150 of FIG. 7A ) or its user is unaware that they are participating in an asset tracking mission.

The asset tracking database (e.g., 710 of FIG. 7A ) may receive and store observation data obtained directly from a direct reporting wireless device (e.g., 150a of FIG. 7A ) or from a Wi-Fi AP database (e.g., 730 of FIG. 7A ) that reports encounters with Wi-Fi access points (e.g., 110 of FIG. 7A ). The observation data includes at least unique identification information (e.g., BSSID) of one or more Wi-Fi access points (e.g., 110 ) encountered and location information of one or more Wi-Fi access points (e.g., 110 ) encountered. The asset tracking database (e.g., 710 of FIG. 7A ) may also store one or more of: a last known location for a Wi-Fi access point (e.g., 110 of FIG. 7A ) and an asset associated therewith (e.g., 610 ), a history of the last known location for a Wi-Fi access point (e.g., 110 of FIG. 7A ) and an asset associated therewith (e.g., 610 ), and a current location of a Wi-Fi access point (e.g., 110 of FIG. 7A ) and an asset associated therewith (e.g., 610 ). The asset tracking database (e.g., 710 of FIG. 7A ) may also receive and store one or more of the following: the time, date, current location, speed, and direction of travel of the reporting wireless device (e.g., 150 of FIG. 7A ) at or near the time of the encounter, as well as the SSID, received signal strength, or other information about the encountered Wi-Fi access point (e.g., 110 ). Additionally, the asset tracking database (e.g., 710 of FIG. 7A ) may receive and store any of the above-mentioned information from other in-range Wi-Fi access points (e.g., 110 ) encountered at or near the same time as the encounter of the Wi-Fi access point of interest (e.g., 110 ).

In some embodiments, an asset tracking database (e.g., 710 of FIG. 7A ) may determine a location for a movable asset to be tracked (e.g., 610 of FIG. 7A ) based on the last known reported location of an associated Wi-Fi access point (e.g., 110 of FIG. 7A ) . However, the asset tracking database (e.g., 710 of FIG. 7A ) may use one or more of the following: historical data regarding the location of a Wi-Fi access point (e.g., 110 of FIG. 7A ), the time, date, last known location, and received signal strength to the Wi-Fi access point (e.g., 110 of FIG. 7A ), and the time, date, location, last known location, and received signal strength to known Wi-Fi access points (e.g., 110 ) near the Wi-Fi access point of interest (e.g., 110 of FIG. 7A ). Depending on the available information, well-known GPS, Wi-Fi, location services, triangulation, triangulation, and any other positioning technology may be used to determine or improve the accuracy of the location determination of the particular Wi-Fi access point of interest (e.g., 110 of FIG. 7A ) and, associated therewith, the location of the asset (e.g., 610 of FIG. 7A ). Thus, the asset tracking database (e.g., 710 of FIG. 7A ) may generate historical trends of the location of a particular asset (e.g., 610 of FIG. 7A ) over a period of time and possible other information about the particular asset. Thus, tracking accuracy may be increased based on the number of observations obtained by the asset tracking database (e.g., 710 of FIG. 7A ).

For purposes of example, an asset tracking database (e.g., 710 of FIG. 7A ) may include a data structure that includes the time, date, GPS or current location (e.g., latitude (“GPS LAT”) and longitude (“GPS LNG”)), SSID, BSSID, and received signal strength of a discovered Wi-Fi access point (e.g., 110 of FIG. 7A ) received directly or indirectly from a wireless device (e.g., 150 of FIG. 7A ) that encounters a Wi-Fi access point (e.g., 110 of FIG. 7A ) in range as part of each report. The BSSID of a discovered Wi-Fi access point (e.g., 110 of FIG. 7A ) may be associated with or used to reference a particular asset (e.g., 610 ) tracked within the asset tracking database (e.g., 710 of FIG. 7A ). The asset tracking database (e.g., 710 of FIG. 7A ) may receive, calculate, or estimate the last known (“AP LK”) location of a discovered Wi-Fi access point (e.g., 110 of FIG. 7A ). If the last known location of the Wi-Fi access point (e.g., 110 of FIG. 7A ) is not known, it may be estimated from the GPS or current location of the most recent wireless device (e.g., 150 of FIG. 7A ) that reported an observation of the Wi-Fi access point (e.g., 110 of FIG. 7A ), or determined or further refined using well-known positioning techniques. An asset tracking database (e.g., 710 of FIG. 7A ) may calculate the current (“AP CUR”) location for one or more Wi-Fi access points (e.g., 110 of FIG. 7A ) based on available information, and, relatedly, the current location of their associated assets (e.g., 610 of FIG. 7A ). Those skilled in the art will appreciate that calculating a location based on the last known location of one or more Wi-Fi access points (if any), the GPS or current location (if available) of one or more wireless devices (e.g., 150 of FIG. 7A ) reporting the Wi-Fi access point (e.g., 110 of FIG. 7A ) and their relative received signal strength, and possibly other information associated therewith, may be used to determine and/or improve the location determination of one or more Wi-Fi access points (e.g., 110 of FIG. 7A ) and assets associated therewith (e.g., 610 of FIG. 7A ) using well-known positioning and location improvement techniques. The calculated current location may be stored in an asset tracking database (e.g., 710 of FIG. 7A ) as a best estimate of the location where a particular Wi-Fi access point (e.g., 110 of FIG. 7A ) and, in association, an associated asset (e.g., 610 of FIG. 7A ) may be located. The accuracy of the location determination may be enhanced over time by utilizing more observations of other wireless devices (e.g., 150 ) that come within range of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

A person skilled in the art will recognize that, according to one or more specific examples of the present invention, an asset tracking database (e.g., 710 of FIG. 7A ) may receive, generate, or store any other relevant data related to a Wi-Fi access point (e.g., 110 of FIG. 7A ), an asset associated with the Wi-Fi access point (e.g., 610 of FIG. 7A ), or any other information related to an asset tracking task based on application or design.

FIG . 7D illustrates an example of a client portal 720 to an asset tracking database (e.g., 710 of FIG. 7A ) according to one or more specific embodiments of the present invention. A user (not shown) may access data contained in the asset tracking database (e.g., 710 of FIG. 7A ) via the client portal 720. The client portal 720 may provide the user with the ability to access at least some of the data stored in the asset tracking database (e.g., 710 of FIG. 7A ). For example, in the depicted example, the user may inquire about the location of a particular asset ( Asset1 ), which is a cement mixer truck. The client portal 720 issues a query to the asset tracking database (e.g., 710 of FIG. 7A ), receives the requested data, which in this case may include unique identification information of the asset (e.g., 610 of FIG. 7A ) and its last known location, and optionally includes a map showing the last known location. One of ordinary skill in the art will recognize that interfacing with, interacting with, and displaying data through the client portal 720 according to one or more specific embodiments of the present invention may vary based on the application or design.

In one or more embodiments of the present invention, a method of passive asset tracking may use only observations of Wi-Fi access points (eg, 110 of FIG. 7A ) received from a Wi-Fi AP database (eg, 730 of FIG. 7A ).

In one or more specific examples of the present invention, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data including unique identification information of Wi-Fi access points (e.g., 110 of FIG. 7A ) encountered by one or more reporting wireless devices (e.g., 150 b , 150 c , and 150 d of FIG. 7A ) and location information of the Wi-Fi access points (e.g., 110 of FIG. 7A ). The Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be established, operated, and maintained separately and separately from the asset tracking database (e.g., 710 of FIG . 7A ) . In some specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by an original equipment manufacturer of a wireless device (e.g., 150 of FIG. 7A ). In other specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by an operating system developer of an operating system executed on the wireless device (e.g., 150 of FIG. 7A ). For example, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a location service database of Apple ^® iOS ^® , Google ^® Android ^® , or Microsoft ^® , which is typically used to improve the accuracy of location determination for their respective end users. In other specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by a software developer. For example, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data commercially provided by Cisco Systems ^® , Facebook ^® , WhatsApp ^® , X-Mode ^® , Ruckus ^® , and Skyhook ^® . In other specific examples, according to one or more specific examples of the present invention, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of any other type or kind of observation data.

For purposes of the present disclosure, a Wi-Fi access point (e.g., 110 of FIG. 7A ) may be a known Wi-Fi access point, an industrial Wi-Fi access point, a virtual Wi-Fi access point, or any other type or kind of Wi-Fi access point (e.g., 110 of FIG. 7A ) capable of participating in at least a portion of a Wi-Fi wireless network discovery process, wherein the virtual Wi-Fi access point disguises or simulates at least a portion of a Wi-Fi wireless network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ). In some embodiments, a customized or virtual Wi-Fi access point (e.g., 110 of FIG. 7A ) may remove unnecessary features or characteristics to reduce the footprint and/or power consumption of the device. Nevertheless, one skilled in the art will recognize that any type or type of device capable of disguising or emulating at least a portion of a Wi-Fi network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ) may be used in accordance with one or more embodiments of the present invention.

The method may include associating unique identification information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) with a movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ), wherein the Wi-Fi access point (e.g., 110 of FIG. 7A ) may be disposed on, attached to, or integrated with the movable asset (e.g., 610 of FIG. 7A ). The unique identification information may be any information that uniquely identifies the Wi-Fi access point (e.g., 110 of FIG. 7A ), including, for example, a BSSID of the Wi-Fi access point (e.g., 110 of FIG. 7A ). The unique identification information may be entered into an asset tracking database (e.g., 710 of FIG. 7A ) and logically associated with the movable asset (e.g., 610 of FIG. 7A ) that is placed on, attached to, or otherwise integrated with the movable asset for the purpose of participating in the asset tracking mission. Additionally, any other information about the Wi-Fi access point (e.g., 110 of FIG. 7A ) or the movable asset may be stored in the same or related records of the asset tracking database (e.g., 710 of FIG. 7A ).

The method may include receiving observation data (e.g., 740 of FIG. 7B ) from a Wi-Fi AP database (e.g., 730 of FIG. 7A ) at an asset tracking database (e.g., 710 of FIG . 7A ) , the observation data including unique identification information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ). The Wi-Fi AP database (e.g., 730 of FIG. 7A ) may receive observation data from one or more wireless devices (e.g., 150 b , 150 c , and 150 d of FIG. 7A ) that encounter a Wi-Fi access point (e.g., 110 of FIG. 7A ) and report unique identification information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) to the Wi-Fi AP database (e.g., 730 of FIG. 7A ). In some specific examples, the location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) may include the latitude and longitude of the Wi-Fi access point (e.g., 110 of FIG. 7A ). In other specific examples, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the latitude and longitude of the reporting wireless device (e.g., 150 b , 150 c , or 150 d in FIG. 7A ) at or near the time when the reporting wireless device meets the Wi-Fi access point (e.g., 110 in FIG. 7A ). In still other specific examples, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the received signal strength of the Wi-Fi access point (e.g., 110 in FIG. 7A ) measured by the reporting wireless device (e.g., 150 b , 150 c , or 150 d in FIG. 7A ) at or near the time when the reporting wireless device meets the Wi-Fi access point (e.g., 110 in FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) that the wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) was close to the Wi-Fi access point (e.g., 110 of FIG. 7A ) at or near the time of encountering the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the location of the wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) and in relation to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) close to the Wi-Fi access point (e.g., 110 of FIG. 7A ), received signal strength, any of the above-mentioned information, or any other information.

The method may include determining the location of a movable asset (e.g., 610 of FIG. 7A ) based at least in part on observations of a Wi-Fi access point (e.g., 110 of FIG. 7A ) by an asset tracking database (e.g., 710 of FIG. 7A ). In some embodiments, determining the location of the movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of the Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) at or near the time of encounter with a Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the received signal strength of a Wi-Fi access point (e.g., 110 of FIG. 7A ) measured by a reporting wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of the encounter of the reporting wireless device with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). In the case of using well-known Wi-Fi positioning techniques, the received signal strength may be used to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). For example, the received signal strength may be used to determine a radius of the location of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ), which radius may be used alone or in combination with other location information to determine or enhance the location determination of a Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) encountered by a reporting wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of the reporting wireless device's encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the locations of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used alone or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the location of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) relative to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG . 7A ) near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ), received signal strength, any of the above-mentioned information, or any other information to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the received signal strengths of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used individually or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

Those skilled in the art will recognize that historical location information, reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) location information, Wi-Fi access point (e.g., 110 of FIG. 7A ) location information, other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, received signal strength of Wi-Fi access point (e.g., 110 of FIG. 7A ) location information, other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, ) The received signal strength of the location information and any other information may be used alone or in combination with known positioning technologies, including but not limited to smartphone positioning, network-based positioning, hybrid positioning, GPS positioning, cellular positioning, Wi-Fi positioning, triangulation, trilateration, arrival time, arrival angle, and any other positioning technology or combination thereof may be used according to one or more specific examples of the present invention. In addition, those skilled in the art will recognize that the positioning technology used may vary based on the type or kind of observation data available when making a location determination.

The method may further include storing the location of the movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ). The method may further include providing user access to the location of the movable asset (e.g., 610 of FIG. 7A ) stored in the asset tracking database (e.g., 710 of FIG. 7A ) via a client portal (e.g., 720 of FIG. 7A ). In some specific examples, the client portal (e.g., 720 of FIG. 7A ) may include a software interface for querying and receiving information from the asset tracking database (e.g., 710 of FIG. 7A ). The client portal (e.g., 720 of FIG. 7A ) may be part of the same computing system as the computing system of the asset tracking database (e.g., 710 of FIG. 7A ), or may be part of a separate and different computing system (e.g., 800 of FIG. 8 ) or wireless device (e.g., 150 ) that is connected to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection. The client portal (e.g., 720 of FIG. 7A ) may be a web-based portal to the asset tracking database (e.g., 710 of FIG. 7A ) or a stand-alone software application that provides access to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection.

Advantageously, there is no communication between the asset tracking database (e.g., 710 of FIG. 7A ) and one or more wireless devices (e.g., 150 b , 150 c , or 150 d of FIG. 7A ), thereby enabling passive asset tracking in an open network environment where network connectivity is not required, and the one or more wireless devices report encounters with Wi-Fi access points (e.g., 110 of FIG. 7A ) to the Wi-Fi AP database (e.g., 730 of FIG. 7A ), the reports including observation data. In this open network configuration, existing infrastructure represented by an ecosystem of wireless devices (e.g., 150 ) such as smart phones and the inherent reporting features of wireless device operating systems or other software (e.g., 150 ) for reporting observations of encounters with Wi-Fi access points (e.g., 110 of FIG. 7A ) can be utilized to passively track assets (e.g., 610 of FIG. 7A ) without the wireless device (e.g., 150 ) or its user being aware that it is participating in an asset tracking mission. In addition, one or more wireless devices (e.g., 150b , 150c , or 150d of FIG. 7A ) or their users may not be aware that they are participating in an asset tracking mission. A wireless device (eg, 150b , 150c , or 150d of FIG. 7A ) simply reports observations of Wi-Fi access points (eg, 110 of FIG. 7A ) that it encounters to a Wi-Fi AP database (eg, 730 of FIG. 7A ), typically as part of participating in location services.

In one or more specific examples of the present invention, a method of passive asset tracking may use first observation data received directly from one or more direct reporting wireless devices (e.g., 150a of Figure 7A ) and second observation data received from a Wi-Fi AP database (e.g., 730 of Figure 7A ), which receives observation data from one or more indirectly reporting wireless devices (e.g., 150b , 150c , or 150d of Figure 7A ).

In one or more specific examples of the present invention, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data including unique identification information of Wi-Fi access points (e.g., 110 of FIG. 7A ) encountered by one or more indirect reporting wireless devices (e.g., 150 b , 150 c , and 150 d of FIG. 7A ) and location information of the Wi-Fi access points (e.g., 110 of FIG. 7A ). The Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be established, operated, and maintained separately and separately from the asset tracking database (e.g., 710 of FIG . 7A ) . In some specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by an original equipment manufacturer of a wireless device (e.g., 150 of FIG. 7A ). In other specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by an operating system developer of an operating system executed on the wireless device (e.g., 150 of FIG. 7A ). For example, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be an ^{Apple® iOS®} , ^{Google® Android®} , or ^Microsoft® location service database, which is typically used to improve the accuracy of location determination for their respective end users. In other specific examples, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data maintained by a software developer. For example, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of observation data commercially provided by Cisco Systems ^® , Facebook ^® , WhatsApp ^® , X-Mode ^® , Ruckus ^® , and Skyhook ^® . In other specific examples, according to one or more specific examples of the present invention, the Wi-Fi AP database (e.g., 730 of FIG. 7A ) may be a database of any other type or kind of observation data.

For purposes of the present disclosure, a Wi-Fi access point (e.g., 110 of FIG. 7A ) may be a known Wi-Fi access point, an industrial Wi-Fi access point, a virtual Wi-Fi access point, or any other type or kind of Wi-Fi access point (e.g., 110 of FIG. 7A ) capable of participating in at least a portion of a Wi-Fi wireless network discovery process, the virtual Wi-Fi access point disguising or emulating at least a portion of a Wi-Fi network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ). In some embodiments, a customized or virtual Wi-Fi access point (e.g., 110 of FIG. 7A ) may remove unnecessary features or aspects to reduce the footprint and/or power consumption of the device. Nevertheless, one of ordinary skill in the art will recognize that any type or variety of devices capable of disguising or emulating at least a portion of a Wi-Fi network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ) may be used in accordance with one or more embodiments of the present invention.

The method may include associating unique identification information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) with a movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ), wherein the Wi-Fi access point (e.g., 110 of FIG. 7A ) may be disposed on, attached to, or integrated with the movable asset (e.g., 610 of FIG. 7A ). The unique identification information may be any information that uniquely identifies the Wi-Fi access point (e.g., 110 of FIG. 7A ), including, for example, a BSSID of the Wi-Fi access point (e.g., 110 of FIG. 7A ). The unique identification information may be entered into an asset tracking database (e.g., 710 of FIG. 7A ) and logically associated with the movable asset (e.g., 610 of FIG. 7A ) that is placed on, attached to, or otherwise integrated with the movable asset for the purpose of participating in the asset tracking mission. Additionally, any other information about the Wi-Fi access point (e.g., 110 of FIG. 7A ) or the asset may be stored in the same or related records of the asset tracking database (e.g., 710 of FIG. 7A ).

The method may include receiving, at an asset tracking database (e.g., 710 of FIG. 7A ), first observation data (e.g., 740 of FIG. 7B ) from one or more direct reporting wireless devices (e.g., 150a of FIG. 7A ) that encounter a Wi-Fi access point (e.g., 110 of FIG . 7A ), the first observation data including unique identification information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) and first location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

The method may include receiving second observation data (e.g., 740 of FIG. 7B ) from a Wi-Fi AP database (e.g., 730 of FIG. 7A ) at an asset tracking database (e.g., 710 of FIG. 7A ), the second observation data including unique identification information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ). The Wi-Fi AP database (e.g., 730 of FIG. 7A ) may receive observation data from one or more indirect reporting wireless devices (e.g., 150 b , 150 c , and 150 d of FIG. 7A ) that encounter a Wi-Fi access point (e.g., 110 of FIG. 7A ) and report unique identification information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) to the Wi-Fi AP database (e.g., 730 of FIG. 7A ).

In some specific examples, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the latitude and longitude of the Wi-Fi access point (e.g., 110 in FIG. 7A ). In other specific examples, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the latitude and longitude of the reporting wireless device (e.g., 150 b , 150 c , or 150 d in FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 in FIG. 7A ). In yet another specific example, the location information of a Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the received signal strength of the Wi-Fi access point (e.g., 110 in FIG. 7A ) measured by the reporting wireless device (e.g., 150 b , 150 c , or 150 d in FIG. 7A ) at or near the time when the reporting wireless device encounters the Wi-Fi access point (e.g., 110 in FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) that were close to the Wi-Fi access point (e.g., 110 of FIG. 7A ) when or near the time when the wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) encountered the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the location of the wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) and in relation to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) close to the Wi-Fi access point (e.g., 110 of FIG. 7A ), received signal strength, any of the above-mentioned information, or any other information.

The method may include determining, by using an asset tracking database (e.g., 710 of FIG. 7A ), a location of a movable asset (e.g., 610 of FIG. 7A ) based at least in part on first and/or second observations of a Wi-Fi access point (e.g., 110 of FIG. 7A ). In some embodiments, determining the location of the movable asset (e.g., 610 of FIG . 7A ) may include using the latitude and longitude of the Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) at or near the time of encounter with a Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the received signal strength of a Wi-Fi access point (e.g., 110 of FIG. 7A ) measured by a reporting wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of the encounter of the reporting wireless device with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). In the case of using well-known Wi-Fi positioning techniques, the received signal strength may be used to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). For example, the received signal strength may be used to determine a radius of the location of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ), which radius may be used alone or in combination with other location information to determine or enhance the location determination of a Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) encountered by a reporting wireless device (e.g., 150 b , 150 c , or 150 d of FIG. 7A ) at or near the time of the reporting wireless device's encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the locations of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used alone or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the location of a reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) relative to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG . 7A ) near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ), received signal strength, any of the above-mentioned information, or any other information to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the received signal strengths of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used individually or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

Those skilled in the art will recognize that historical location information, reporting wireless device (e.g., 150b , 150c , or 150d of FIG. 7A ) location information, Wi-Fi access point (e.g., 110 of FIG. 7A) location information, other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, received signal strength of Wi-Fi access point (e.g., 110 of FIG. 7A ) location information, received signal strength of other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, and other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG . 7A ) location information and other Wi-Fi access points (e.g., 110 of FIG. 7A ) location information) can be used alone or in combination with known positioning techniques. ) or any other information related to nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ), such known positioning technologies include but are not limited to smartphone positioning, network-based positioning, hybrid positioning, GPS positioning, cellular positioning, triangulation, triangulation, arrival time, arrival angle, and any other positioning technology or combination of positioning technologies may be used according to one or more specific examples of the present invention. In addition, those skilled in the art will recognize that the positioning technology used may vary based on the type or type of observation data available when making a position determination.

The method may further include storing the location of the movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ). The method may further include providing user access to the location of the movable asset (e.g., 610 of FIG. 7A ) stored in the asset tracking database (e.g., 710 of FIG. 7A ) via a client portal (e.g., 720 of FIG. 7A ). In some specific examples, the client portal (e.g., 720 of FIG. 7A ) may include a software interface for querying and receiving information from the asset tracking database (e.g., 710 of FIG. 7A ). The client portal (e.g., 720 of FIG. 7A ) may be part of the same computing system as the computing system of the asset tracking database (e.g., 710 of FIG. 7A ), or may be part of a separate and different computing system (e.g., 800 of FIG. 8 ) or wireless device (e.g., 150 ) that is connected to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection. The client portal (e.g., 720 of FIG. 7A ) may be a web-based portal to the asset tracking database (e.g., 710 of FIG. 7A ) or a standalone software application that provides access to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection.

Advantageously, there is no communication between the asset tracking database (e.g., 710 of FIG. 7A ) and one or more indirect reporting wireless devices (e.g., 150 b , 150 c , or 150 d of FIG. 7A ), thereby enabling passive and potentially anonymous asset tracking in areas where network connectivity is absent, wherein the one or more wireless devices report encounters with Wi-Fi access points (e.g., 110 of FIG. 7A ) to a Wi-Fi AP database (e.g., 730 of FIG. 7A ), the reports including observation data. In this hybrid open network configuration, existing infrastructure represented by an ecosystem of wireless devices (e.g., 150 ) such as smart phones and the inherent reporting features of the wireless device operating system or other software (e.g., 150 ) for reporting observations of encounters with Wi-Fi access points (e.g., 110 of FIG. 7A ) can be utilized to passively track assets (e.g., 610 of FIG. 7A ) without the wireless device (e.g., 150 ) or its user being aware that it is participating in an asset tracking mission. In addition, one or more wireless devices (e.g., 150b , 150c , or 150d of FIG. 7A ) or their users may not be aware that they are participating in an asset tracking mission. A wireless device (eg, 150b , 150c , or 150d of FIG. 7A ) simply reports observations of Wi-Fi access points (eg, 110 of FIG. 7A ) that it encounters to a Wi-Fi AP database (eg, 730 of FIG. 7A ), typically as part of participating in location services.

In one or more embodiments of the present invention, a method of passive asset tracking may use observations received directly from one or more direct reporting wireless devices (eg, 150a of FIG. 7A ) encountering a Wi-Fi access point (eg, 110 of FIG. 7A ).

For purposes of the present disclosure, a Wi-Fi access point (e.g., 110 of FIG. 7A ) may be a known Wi-Fi access point, an industrial Wi-Fi access point, a virtual Wi-Fi access point, or any other type or kind of Wi-Fi access point (e.g., 110 of FIG. 7A ) capable of participating in at least a portion of a Wi-Fi wireless network discovery process, the virtual Wi-Fi access point disguising or emulating at least a portion of a Wi-Fi network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ). In some embodiments, a customized or virtual Wi-Fi access point (e.g., 110 of FIG. 7A ) may remove unnecessary features or aspects to reduce the footprint and/or power consumption of the device. Nonetheless, one of ordinary skill in the art will recognize that any type or variety of devices capable of disguising or emulating at least a portion of a Wi-Fi network discovery process by broadcasting a beacon frame (e.g., 230 of FIG. 7A ) or a probe response frame (e.g., 240 of FIG. 2C ) may be used in accordance with one or more embodiments of the present invention.

The method may include associating unique identification information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) with a movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ), wherein the Wi-Fi access point (e.g., 110 of FIG. 7A ) may be disposed on, attached to, or integrated with the movable asset. The unique identification information may be any information that uniquely identifies the Wi-Fi access point (e.g., 110 of FIG. 7A ), including, for example, a BSSID of the Wi-Fi access point (e.g., 110 of FIG. 7A ). The unique identification information may be entered into an asset tracking database (e.g., 710 of FIG. 7A ) and logically associated with the movable asset (e.g., 610 of FIG. 7A ) that is placed on, attached to, or otherwise integrated with the movable asset for the purpose of participating in the asset tracking task. Additionally, any other information about the Wi-Fi access point (e.g., 110 of FIG. 7A ) or the asset may be stored in the same or related records of the asset tracking database (e.g., 710 of FIG. 7A ).

The method may include receiving observation data (e.g., 740 of FIG. 7B ) at an asset tracking database (e.g., 710 of FIG. 7A ) from one or more direct reporting wireless devices (e.g., 150 a of FIG. 7A ) that encounter a Wi-Fi access point (e.g., 110 of FIG . 7A ) , the observation data including unique identification information of the Wi-Fi access point (e.g., 110 of FIG. 7A ) and location information of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

In some embodiments, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the latitude and longitude of the Wi-Fi access point (e.g., 110 in FIG. 7A ). In other embodiments, the location information of the Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the latitude and longitude of the reporting wireless device (e.g., 150 a in FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 in FIG. 7A ). In yet another specific example, the location information of a Wi-Fi access point (e.g., 110 in FIG. 7A ) may include the received signal strength of the Wi-Fi access point (e.g., 110 in FIG. 7A ) measured by the reporting wireless device (e.g., 150 a in FIG. 7A ) at or near the time when the reporting wireless device encountered the Wi-Fi access point (e.g., 110 in FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) that the wireless device (e.g., 150 a of FIG. 7A ) was close to the Wi-Fi access point (e.g., 110 of FIG. 7A ) at or near the time of encountering the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, the location information of a Wi-Fi access point (e.g., 110 of FIG. 7A ) may include reporting the location of the wireless device (e.g., 150 a of FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) and in relation to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ), received signal strength, any of the above-mentioned information, or any other information.

The method may include determining a location of a movable asset (e.g., 610 of FIG. 7A ) based at least in part on observations of a Wi-Fi access point (e.g., 110 of FIG. 7A ) . In some embodiments, determining the location of the movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of the Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In other embodiments, determining the location of the movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of the reporting wireless device (e.g., 150a of FIG. 7A ) at or near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) as the location of the movable asset (e.g., 610 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the received signal strength of a Wi-Fi access point (e.g., 110 of FIG. 7A ) measured by a reporting wireless device (e.g., 150a of FIG. 7A ) at or near the time of the encounter of the reporting wireless device with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). In the case of using well-known Wi-Fi positioning techniques, the received signal strength may be used to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). For example, the received signal strength may be used to determine a radius of the location of the reporting wireless device (e.g., 150a of FIG. 7A ), which radius may be used alone or in combination with other location information to determine or enhance the location determination of a Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the latitude and longitude of one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) encountered by the reporting wireless device (e.g., 150a of FIG. 7A ) at or near the time of the encounter with the Wi-Fi access point (e.g., 110 of FIG. 7A ) to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the locations of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used alone or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ). In yet other specific examples, determining the location of a movable asset (e.g., 610 of FIG. 7A ) may include using the location of the reporting wireless device (e.g., 150a ) relative to one or more other Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) near the time of encounter with the Wi-Fi access point (e.g., 110 of FIG . 7A ) , received signal strength , any of the information mentioned above, or any other information to determine the location of the movable asset (e.g., 610 of FIG. 7A ). When using well-known Wi-Fi positioning techniques, the received signal strengths of nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) may be used individually or in combination to determine or enhance the location determination of the Wi-Fi access point (e.g., 110 of FIG. 7A ).

Those skilled in the art will recognize that historical location information, reporting wireless device (e.g., 150a of FIG. 7A ) location information, Wi-Fi access point (e.g., 110 of FIG. 7A ) location information, other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, received signal strength of Wi-Fi access point (e.g., 110 of FIG. 7A ) location information, received signal strength of other nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) location information, and location information associated with a Wi-Fi access point (e.g., 110 of FIG. 7A ) or nearby Wi-Fi access points (e.g., other nearby Wi-Fi access points 110 not shown in FIG. 7A ) can be used alone or in combination with known positioning techniques. ), such known positioning technologies include but are not limited to smartphone positioning, network-based positioning, hybrid positioning, GPS positioning, cellular positioning, triangulation, triangulation, arrival time, arrival angle, and any other positioning technology or combination of positioning technologies may be used according to one or more specific examples of the present invention. In addition, those skilled in the art will recognize that the positioning technology used may vary based on the type or kind of observation data available when making a position determination.

The method may further include storing the location of the movable asset (e.g., 610 of FIG. 7A ) in an asset tracking database (e.g., 710 of FIG. 7A ). The method may further include providing user access to the location of the movable asset (e.g., 610 of FIG. 7A ) stored in the asset tracking database (e.g., 710 of FIG. 7A ) via a client portal (e.g., 720 of FIG. 7A ). In some specific examples, the client portal (e.g., 720 of FIG. 7A ) may include a software interface for querying and receiving information from the asset tracking database (e.g., 710 of FIG. 7A ). The client portal (e.g., 720 of FIG. 7A ) may be part of the same computing system as the computing system of the asset tracking database (e.g., 710 of FIG. 7A ), or may be part of a separate and different computing system (e.g., 800 of FIG. 8 ) or wireless device (e.g., 150 ) that is connected to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection. The client portal (e.g., 720 of FIG. 7A ) may be a web-based portal to the asset tracking database (e.g., 710 of FIG. 7A ) or a standalone software application that provides access to the asset tracking database (e.g., 710 of FIG. 7A ) via a network connection.

The method may further include providing unique identification information of a Wi-Fi access point from an asset tracking database (e.g., 710 of FIG. 7A ) to one or more wireless devices (e.g., 150 a of FIG. 7A ) to limit observation data reported by the one or more wireless devices (e.g., 150 a of FIG. 7A ) to data related to the Wi-Fi access point (e.g., 110 of FIG. 7A ) associated with the movable asset to be tracked (e.g., 610 of FIG. 7A ). One or more wireless devices (e.g., 150a of FIG. 7A ) may limit the observations reported directly to the asset tracking database (e.g., 710 of FIG. 7A ) to observations associated with Wi-Fi access points (e.g., 110 of FIG. 7A ) associated with the movable asset to be tracked (e.g., 610 of FIG. 7A ). Unique identification information may be provided at any time, including before receiving observations from one or more wireless devices (e.g., 150a of FIG. 7A ) encountering the Wi-Fi access point (e.g., 110 of FIG. 7A ).

The method may further include filtering, at an asset tracking database (e.g., 710 of FIG. 7A ), observations received from one or more wireless devices (e.g., 150 a of FIG. 7A ) to data associated with a Wi-Fi access point (e.g., 110 of FIG. 7A ) associated with a movable asset to be tracked (e.g., 610 of FIG. 7A ). The filtering may be performed by the asset tracking database (e.g., 710 of FIG. 7A ) at any time, including after receiving observations from one or more wireless devices (e.g., 150 a of FIG. 7A ) encountering a Wi-Fi access point (e.g., 110 of FIG. 7A ).

In this configuration, limiting and/or filtering the observations to data associated with Wi-Fi access points (e.g., 110 of FIG. 7A ) associated with the movable asset to be tracked (e.g., 610 of FIG. 7A ) can enhance tracking capabilities and reduce the latency in reporting the observations and querying the asset tracking database (e.g., 710 of FIG. 7A ).

In one or more specific embodiments of the present invention, a method of passive asset tracking utilizing existing standalone infrastructure may include placing a Wi-Fi access point on, in, or otherwise attached to or integrated with a movable physical asset to be tracked. The Wi-Fi access point may be a known off-the-shelf industrial, battery-powered, or any other type or kind of Wi-Fi access point. However, because the Wi-Fi access point does not require routing features or true Wi-Fi functionality other than participating in the Wi-Fi wireless network discovery protocol, a customized Wi-Fi access point that eliminates the unimplemented features may be used to reduce the footprint and power consumption of the device. In addition, devices configured to disguise the Wi-Fi wireless network discovery protocol can be dedicated to asset tracking tasks. Nevertheless, those skilled in the art will recognize that any Wi-Fi access point or related device capable of participating in the Wi-Fi wireless network discovery protocol can be used according to one or more specific embodiments of the present invention.

The method may further include logically associating unique identification information of the Wi-Fi access point with the asset in an asset tracking database. The unique identification information may be any information that uniquely identifies a Wi-Fi access point, including, for example, a BSSID of the Wi-Fi access point. The asset tracking database may be any type or kind of database or software application configured to store and potentially manipulate data. Wi-Fi access points associated with a particular movable asset may be stored in the same or related records in the asset tracking database, or otherwise associated to indicate their association, particularly using the location of the Wi-Fi access point as a proxy for the location of the asset.

The method may further include receiving information about the locations of Wi-Fi access points encountered by one or more wireless devices and storing at least a portion of the received information in an asset tracking database. In some embodiments, the information about the locations of the encountered Wi-Fi access points is received directly or indirectly from a Wi-Fi AP database or a third-party provider. In other embodiments, the information about the locations of the encountered Wi-Fi access points is received directly or indirectly from one or more of the reporting wireless devices. In some embodiments, one or more wireless devices or their users may not be aware that they are participating in an asset tracking mission. The wireless devices simply report their locations and unique identification information of the Wi-Fi access points they encounter as part of participating in location services. In other embodiments, one or more wireless devices may be used to intentionally participate in asset tracking tasks. In all such embodiments, whenever the wireless device comes within range of a Wi-Fi access point and receives unique identification information about the Wi-Fi access point, the wireless device typically reports at least its location and the unique identification information of the Wi-Fi access point directly or indirectly to one or more of an original equipment manufacturer, an operating system developer, a location-based service provider, a Wi-Fi AP database, or a third-party software application or database, or directly to the asset tracking database itself via a cellular connection. Information about the location of a wireless device may include, for example, the time the wireless device was reported, data, GPS location, the last known location of a Wi-Fi access point, unique identification information of other Wi-Fi access points in range, and their respective signal strengths. One of ordinary skill in the art will recognize that other information may be used and may vary based on the application or design according to one or more specific embodiments of the present invention. Thus, information about the location of Wi-Fi access points may be received by an asset tracking database directly or indirectly from one or more wireless devices that report their location and unique identification information of one or more Wi-Fi access points they encounter.

The method may further include tracking the location of the Wi-Fi access point and, relatedly, the location of the asset itself in an asset tracking database. The asset tracking database may maintain a record of reports about the Wi-Fi access point and receive or calculate an estimated location for the Wi-Fi access point and, relatedly, maintain a record of reports about the asset itself and receive or calculate an estimated location for the asset. This information and any other information suitable for storage in the asset tracking database may be stored in the asset tracking database as the estimated current location of the asset. As mentioned above, the asset tracking database may receive information that provides an estimate of the location of a Wi-Fi access point or information that can be used to estimate the location of a Wi-Fi access point using one or more of GPS determined location, Wi-Fi access point location and possibly associated received signal strength, triangulation, or triangulation. The method may further include providing user access to information stored in the asset tracking database via a client portal. The client portal may include a software interface for querying and receiving information from the asset tracking database. The client portal may be part of the same computing system as the computing system of the asset tracking database, or may be part of a separate and different computing system or wireless device that is connected to the asset tracking database via a network connection. In one or more specific embodiments of the present invention, a non-transitory computer-readable medium contains software instructions that, when executed by a processor, can perform any of the methods mentioned above.

In one or more specific embodiments of the present invention, a system for passive asset tracking utilizing existing standalone infrastructure may include a computing system having a central processing unit, system memory, a network interface, and storage, and a Wi-Fi access point disposed on, in, or otherwise attached to a movable asset to be tracked. An asset tracking database executing on the computing system may associate unique identification information of the Wi-Fi access point with the asset. The asset tracking database may receive information regarding the location of the Wi-Fi access point, which is identified by the unique identification information transmitted by the Wi-Fi access point as part of discovery of a Wi-Fi wireless network. The asset tracking database can track the location of Wi-Fi access points and, relatedly, the location of associated assets.

In one or more embodiments of the present invention, a non-transitory computer-readable medium contains software instructions, which, when executed by a processor, can perform any of the above-mentioned methods according to one or more embodiments of the present invention.

FIG8 illustrates a computing system 800 according to one or more embodiments of the present invention. One or more of the asset tracking database (e.g., 710 of FIG7A ) and the client portal (e.g., 720 of FIG7A ) may be a software application containing software instructions that, when executed by one or more processors of the computing system 800 , perform one or more of the methods described herein. One of ordinary skill in the art will recognize that the computing system 800 described herein is merely illustrative of a computing system that may be used to perform any of the software methods mentioned above, and that other computing systems known in the art may be used according to one or more embodiments of the present invention.

The computing system 800 may include one or more central processing units 805 , sometimes referred to as processors (hereinafter referred to as "CPUs" in the singular or "CPUs" in the plural), a host bridge 810 , an input/output ("IO") bridge 815 , a graphics processing unit ("GPU" in the singular or "GPUs" in the plural) 825 , and/or application specific integrated circuits ("ASIC" in the singular or "ASICs" in the plural) (not shown) disposed on one or more printed circuit boards (not shown) that perform computing operations. Each of the one or more CPUs 805 , GPUs 825 , or ASICs (not shown) may be a single-core (not separately illustrated) device or a multi-core (not separately illustrated) device. Multi-core devices typically include multiple cores (not shown) mounted on the same physical die (not shown), or multiple cores (not shown) mounted on multiple dies (not shown) mounted together in the same mechanical package (not shown).

The CPU 805 may be a general purpose computing device typically configured to execute software instructions. The CPU 805 may include an interface 808 to a host bridge 810 , an interface 818 to a system memory 820 , and an interface 823 to one or more IO devices such as one or more GPUs 825. The GPU 825 may function as a dedicated computing device typically configured to perform graphics functions associated with frame buffer manipulation. However, one of ordinary skill in the art will recognize that the GPU 825 may be used to perform computationally intensive non-graphics related functions. In some embodiments, the GPU 825 may be directly interfaced 823 with the CPU 805 (and interfaced 818 with the system memory 820 via the CPU 805 ). In other embodiments, the GPU 825 may be interfaced 821 with the host bridge 810 (and interfaced 816 or 818 with the system memory 820 via the host bridge 810 or the CPU 805 , depending on the application or design). In still other embodiments, the GPU 825 may be interfaced 833 with the IO bridge 815 (and interfaced 816 or 818 with the system memory 820 via the host bridge 810 or the CPU 805 , depending on the application or design). The functionality of the GPU 825 may be integrated with the CPU 805 in whole or in part.

The host bridge 810 may be an interface device that interfaces between one or more computing devices and the IO bridge 815 and, in some embodiments, the system memory 820. For embodiments where the CPU 805 does not include an interface 818 to the system memory 820 , an interface 816 to the system memory 820 , the host bridge 810 may include an interface 808 to the CPU 805 , an interface 813 to the IO bridge 815 , and for embodiments where the CPU 805 does not include an integrated GPU 825 or an interface 823 to the GPU 825 , the host bridge may include an interface 821 to the GPU 825. The functionality of the host bridge 810 may be integrated with the CPU 805 in whole or in part. IO bridge 815 may be an interface device that interfaces between one or more computing devices and various IO devices (e.g., 840 , 845 ) and IO expansion or add-on devices (not illustrated separately). IO bridge 815 may include an interface 813 to host bridge 810 , one or more interfaces 833 to one or more IO expansion devices 835 , an interface 838 to keyboard 840 , an interface 843 to mouse 845 , an interface 848 to one or more local storage devices 850 , and an interface 853 to one or more network interface devices 855. The functionality of IO bridge 815 may be integrated with CPU 805 and/or host bridge 810 in whole or in part. Each local storage device 850 , if present, may be a solid state memory device, a solid state memory device array, a hard drive, a hard drive array, or any other non-transitory computer-readable medium. The network interface device 855 may provide one or more network interfaces including any network protocol suitable for facilitating network connection communications.

In addition to or in lieu of one or more local storage devices 850 , the computing system 800 may also include one or more network attached storage devices 860. Each network attached storage device 860 , if present, may be a solid-state memory device, an array of solid-state memory devices, a hard drive, an array of hard drives, or any other non-transitory computer-readable medium. The network attached storage device 860 may or may not be collocated with the computing system 800 and may be accessed by the computing system 800 via one or more network interfaces provided by the one or more network interface devices 855 .

A person skilled in the art will recognize that the computing system 800 may be a known computing system or a dedicated computing system (not shown). In some specific examples, the dedicated computing system (not shown) may include one or more ASICs (not shown) that perform one or more dedicated functions in a more efficient manner. The one or more ASICs (not shown) may be directly interfaced with the CPU 805 , the host bridge 810 , or the GPU 825 , or interfaced via the IO bridge 815 . Alternatively, in other specific examples, a dedicated computing system (not shown) may be reduced to only those components necessary to perform the desired functions in an effort to reduce one or more of chip count, printed circuit board footprint, thermal design power, and power consumption. One or more ASICs (not shown) may be used in place of one or more of the CPU 805 , host bridge 810 , IO bridge 815 , or GPU 825. In such a system, one or more ASICs may incorporate sufficient functionality to perform certain network and computing functions in a minimal footprint with substantially fewer component devices.

Thus, a person skilled in the art will recognize that, according to one or more specific embodiments of the present invention, the CPU 805 , host bridge 810 , IO bridge 815 , GPU 825 or ASIC (not shown) or a subset, superset or combination of their functions or features may be integrated, distributed or excluded in whole or in part based on application, design or appearance size. Therefore, the description of the computing system 800 is merely exemplary and is not intended to limit the type, kind or configuration of component devices that constitute the computing system 800 suitable for executing the software method according to one or more specific embodiments of the present invention. Notwithstanding the above, one of ordinary skill in the art will recognize that the computing system 800 may be a stand-alone, laptop, desktop, industrial, server, blade, or rack-mountable system and may vary based on application or design.

Advantages of one or more embodiments of the present invention may include one or more of the following:

In one or more embodiments of the present invention, methods and systems for passive asset tracking using observation of Wi-Fi access points allow movable assets to be actively tracked by one or more potentially unrelated wireless devices that are within range of an asset broadcasting a Wi-Fi signal, even though the wireless device or its user may not be aware that it is participating in the asset tracking mission. In this way, each smartphone in the vicinity of an asset that needs to be tracked can anonymously and unknowingly participate in the asset tracking mission.

In one or more embodiments of the present invention, methods and systems for passive asset tracking using observation of Wi-Fi access points utilize already existing devices, systems, and networks to passively track the location of assets without requiring the assets themselves to have any connectivity to the Internet or other networks.

In one or more specific embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points uses one or more Wi-Fi access points that do not require connection to any particular network to identify one or more assets in a field using Wi-Fi wireless network discovery and Wi-Fi access point reporting characteristics and location services of modern smart phones to passively identify the location of one or more assets. A movable asset may be passively tracked by one or more wireless devices, which may be independent and unrelated, whenever any one or more of the wireless devices simply comes within range of an asset associated with a Wi-Fi access point broadcasting a Wi-Fi signal, and without any intention or awareness on the part of the wireless devices or their users that they are participating in an asset tracking mission due to the nature of the Wi-Fi wireless network discovery protocol.

In one or more specific embodiments of the present invention, methods and systems for passive asset tracking using observation of Wi-Fi access points utilize existing infrastructure inherent to smartphones, operating systems, and software applications to report their location and unique identification information of Wi-Fi access points they encounter for use in improving the accuracy of location-based services used for asset tracking tasks without their awareness.

In one or more specific embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points uses the Wi-Fi wireless network discovery protocol and the Wi-Fi access point reporting characteristics of a smartphone to passively track assets associated with Wi-Fi access points by one or more wireless devices using publicly accessible Wi-Fi signals and in a passive scanning application in a completely anonymous manner relative to the asset tracking task, without requiring the wireless devices to be associated with any specific Wi-Fi access point.

In one or more specific embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points, Wi-Fi access points associated with assets, do not require any connectivity to the Internet or any other network connection, and do not require a GPS receiver, but instead rely on one or more wireless devices to report the time, date, and relative location of Wi-Fi access points in range associated with the asset.

In one or more embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points and an asset tracking database receives unique identification information received directly or indirectly from one or more wireless devices or a Wi-Fi AP database and information about the location of one or more Wi-Fi access points. The location of the asset can be tracked in the asset tracking database using the location of the Wi-Fi access point.

In one or more specific embodiments of the present invention, methods and systems for passive asset tracking using observations of Wi-Fi access points may use Wi-Fi access points that allow alternative meanings to be assigned to portions of a beacon frame or probe response that correspond to attributes of the Wi-Fi access point or an asset that is physically and logically associated therewith.

In one or more embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points reduces theft by providing trackable assets that are unaware of the asset tracking hardware or software system. If a thief moves a trackable asset within range of any one or more wireless devices, the discovery of the Wi-Fi access point will be reported, and the asset tracking database will be able to locate the associated asset without the thief being aware that the asset has been tracked.

In one or more embodiments of the present invention, a method and system for passive asset tracking using observation of Wi-Fi access points substantially reduces the complexity and cost associated with deploying a comprehensive asset tracking system. In contrast to conventional asset tracking systems, one or more wireless devices may be completely independent of the asset tracking mission and unrelated thereto as the tracking infrastructure.

Although the present invention has been described in terms of the specific embodiments mentioned above, a person of ordinary skill in the art having benefit of the contents of this disclosure will recognize that other specific embodiments can be designed within the scope of the present invention as described herein. Therefore, the scope of the present invention shall be limited only by the scope of the attached patent application.

100: Wi-Fi wireless network 105: Broadband modem 110: Wi-Fi access point 110a: Wi-Fi access point 110b: Wi-Fi access point 110c: Wi-Fi access point 120: Wireless device 130: Wireless device 140: Wireless device 150: Wireless device 150a: (Report) Wireless device 150b: (Report) Wireless device 150c: (Report) Wireless device 150d: (Report) Wireless device 200: Passive scanning mode 205: Active scanning mode 210: Management frame 220: Beacon frame 220a: Beacon frame 220b: Beacon frame 220c: Beacon frame 230: Probe request frame 240: Probe request frame 240a: Probe response frame 240b: Probe response frame 240c: Probe response frame 250: Verification request frame 260: Verification response frame 270: Correlation request frame 280: Correlation response 290: Data frame 300: Management frame 305: MAC header 3 10: Subtype bit 315: Duration field 320: Subtype description 325: Source address field 330: BSSID 335: Sequence control field 340: Frame body field 345: Frame check sequence field 350: Required subfield 355: Subfield 360: Timestamp subfield 365: Beacon interval subfield 370: Compatibility information subfield 375: SSID subfield 410: Cell tower 420: GPS satellite 420a: GPS satellite 420b: GP S satellite 420c: GPS satellite 510: Housing or enclosure 520: Processor 530: Firmware 540: Radio interface 550: Antenna 560: Power supply 570: Battery power 610: (Mobile) asset 620: (Mobile) asset 630: (Mobile) asset 640: (Mobile) asset 650: Site/operation site 660: Street 670: Motor vehicle 700: System 710: Asset tracking database 720: Client portal 730: Wi-Fi AP database 740: Boundary/Observational data/Asset data 800: Computing system 805: Central processing unit 808: Interface 810: Host bridge 813: Interface 815: Input/output ("IO") bridge 816: Interface 818: Interface 820: System memory 821: Interface 823: Interface 825: Graphics processing unit 833: Interface 835: IO expansion device 838: Interface 840: Keyboard 843: Interface 845: Mouse 848: Interface 850: Local storage device 853: Interface 855: Network interface device 860: Network attached storage device

[Figure 1] shows a familiar Wi-Fi wireless network.

[Figure 2A] shows the passive scanning mode as part of the IEEE 802.11 Wi-Fi wireless network discovery process.

[Figure 2B] shows the active scanning mode as part of the IEEE 802.11 Wi-Fi wireless network discovery process.

[FIG. 2C] illustrates a sequence of IEEE 802.11 management frames typically exchanged between a wireless device and a Wi-Fi access point as part of the Wi-Fi wireless network discovery process.

[Figure 3A] shows the subtypes of IEEE 802.11 management frames.

[FIG. 3B] shows the structure of a known IEEE 802.11 management frame representing the types of management frames transferred between a wireless device and a Wi-Fi access point.

[FIG. 4A] illustrates various techniques that may be used to determine the location of a wireless device and one or more Wi-Fi access points.

[FIG. 4B] shows an overview of a wireless device that reports observations of one or more encountered Wi-Fi access points to a Wi-Fi AP database.

[Figure 5] shows a block diagram of known Wi-Fi access points.

[FIG. 6] illustrates an example of an application of passive asset tracking using observation of Wi-Fi access points according to one or more specific embodiments of the present invention.

[FIG. 7A] illustrates a system for passive asset tracking using observation of Wi-Fi access points according to one or more embodiments of the present invention.

[FIG. 7B] shows an example of observation data of one or more Wi-Fi access points reported by a wireless device based on an encounter according to one or more embodiments of the present invention.

[FIG. 7C] illustrates an example of asset data stored or generated by an asset tracking database according to one or more specific embodiments of the present invention.

[FIG. 7D] illustrates an example of a client entry to an asset tracking database according to one or more embodiments of the present invention.

[Figure 8] shows a computing system according to one or more specific examples of the present invention.

110: Wi-Fi access point

150a: (Report) Wireless device

150b: (Report) Wireless device

150c: (Report) Wireless device

150d: (Report) Wireless device

230: Probe request frame

610: (Movable) Assets

700: System

710:Asset tracking database

720: Client entrance

730:Wi-Fi AP database

740: Boundary/Observational Data/Asset Data

800:Computing system

Claims (26)

A method for passive asset tracking using observations of Wi-Fi access points, comprising: associating unique identification information of a Wi-Fi access point with a movable asset to be tracked in an asset tracking database, wherein the Wi-Fi access point is disposed on, attached to, or integrated with the movable asset, wherein one or more wireless devices encountering the Wi-Fi access point report observation data including the unique identification information of the Wi-Fi access point and location information of the Wi-Fi access point to a Wi-Fi AP database, and wherein there is no communication between the asset tracking database and the one or more wireless devices, and the one or more wireless devices report encounters with the Wi-Fi access point to the Wi-Fi AP database. AP database; at the asset tracking database, receiving observation data from the Wi-Fi AP database, the observation data including the unique identification information of the Wi-Fi access point and the location information of the Wi-Fi access point; at the asset tracking database, determining the location of the movable asset based at least in part on the observation data of the Wi-Fi access point received from the Wi-Fi AP database, and providing the location of the movable asset to a user of the asset tracking database. The method of claim 1 further comprises: storing the location of the movable asset in the asset tracking database. The method of claim 1, wherein the unique identification information of the Wi-Fi access point includes the basic service set identifier (BSSID) of the Wi-Fi access point. As in the method of claim 1, wherein the location information of the Wi-Fi access point includes the latitude and longitude of the Wi-Fi access point. The method of claim 1, wherein the location information of the Wi-Fi access point includes the latitude and longitude of the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point. The method of claim 1, wherein the location information of the Wi-Fi access point includes the received signal strength of the Wi-Fi access point measured by the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point. The method of claim 1, wherein the location information of the Wi-Fi access point includes reporting the latitude and longitude of one or more other Wi-Fi access points that are close to the Wi-Fi access point at or near the time when the wireless device encounters the Wi-Fi access point. The method of claim 1, wherein the location information of the Wi-Fi access point includes reporting the received signal strength of one or more other Wi-Fi access points that are close to the Wi-Fi access point at or near the time when the wireless device encounters the Wi-Fi access point. The method of claim 1, wherein determining the location of the movable asset includes using the latitude and longitude of the Wi-Fi access point as the location of the movable asset. The method of claim 1, wherein determining the location of the movable asset includes using the latitude and longitude of the reporting wireless device as the location of the movable asset. The method of claim 1, wherein determining the location of the movable asset comprises using the received signal strength of the Wi-Fi access point measured by the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point to determine the location of the movable asset. The method of claim 1, wherein determining the location of the movable asset comprises using the latitude and longitude of one or more other Wi-Fi access points encountered by the reporting wireless device at or near the time when the reporting wireless device encountered the Wi-Fi access point to determine the location of the movable asset. The method of claim 1, wherein determining the location of the movable asset comprises using the received signal strength of one or more other Wi-Fi access points measured by the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point to determine the location of the movable asset. A method for passive asset tracking using observations of Wi-Fi access points, comprising: associating unique identification information of a Wi-Fi access point with a movable asset to be tracked in an asset tracking database, wherein the Wi-Fi access point is placed on, attached to, or integrated with the movable asset, wherein one or more wireless devices encountering the Wi-Fi access point report observation data including the unique identification information of the Wi-Fi access point and second location information of the Wi-Fi access point to a Wi-Fi AP database, wherein there is no communication between the asset tracking database and the one or more wireless devices, and the one or more wireless devices report encounters with the Wi-Fi access point to the Wi-Fi AP database. AP database; at the asset tracking database, receiving first observation data from one or more direct reporting wireless devices that encounter the Wi-Fi access point, the first observation data including the unique identification information of the Wi-Fi access point and the first location information of the Wi-Fi access point; at the asset tracking database, receiving second observation data from the Wi-Fi AP database, the second observation data including the unique identification information of the Wi-Fi access point and the second location information of the Wi-Fi access point; at the asset tracking database, determining the location of the movable asset based at least in part on the first observation data and/or the second observation data of the Wi-Fi access point; and providing the location of the movable asset to a user of the asset tracking database. The method of claim 14 further comprises: storing the location of the movable asset in the asset tracking database. The method of claim 14, wherein the unique identification information of the Wi-Fi access point includes the basic service set identifier (BSSID) of the Wi-Fi access point. The method of claim 14, wherein the first location information and/or the second location information of the Wi-Fi access point includes the latitude and longitude of the Wi-Fi access point. The method of claim 14, wherein the first location information and/or the second location information of the Wi-Fi access point includes the latitude and longitude of the reporting wireless device at or near the time of encounter with the Wi-Fi access point. The method of claim 14, wherein the first location information and/or the second location information of the Wi-Fi access point includes the received signal strength of the Wi-Fi access point measured by the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point. The method of claim 14, wherein the first location information and/or the second location information of the Wi-Fi access point includes reporting the latitude and longitude of one or more other Wi-Fi access points that are close to the Wi-Fi access point at or near the time when the wireless device encounters the Wi-Fi access point. The method of claim 14, wherein the first location information and/or the second location information of the Wi-Fi access point includes reporting the received signal strength of one or more other Wi-Fi access points close to the Wi-Fi access point at or near the time when the wireless device encounters the Wi-Fi access point. The method of claim 14, wherein determining the location of the movable asset includes using the latitude and longitude of the Wi-Fi access point as the location of the movable asset. The method of claim 14, wherein determining the location of the movable asset includes using the latitude and longitude of the reporting wireless device as the location of the movable asset. The method of claim 14, wherein determining the location of the movable asset comprises using the received signal strength of the Wi-Fi access point measured by the reporting wireless device at or near the time when the reporting wireless device encounters the Wi-Fi access point to determine the location of the movable asset. The method of claim 14, wherein determining the location of the movable asset comprises using the latitude and longitude of one or more other Wi-Fi access points encountered by the reporting wireless device at or near the time when the reporting wireless device encountered the Wi-Fi access point to determine the location of the movable asset. The method of claim 14, wherein determining the location of the movable asset comprises determining the location of the movable asset using received signal strength of one or more other Wi-Fi access points measured by the reporting wireless device at or near the time of encounter with the Wi-Fi access point.