US20040203870A1 - Method and system for location finding in a wireless local area network - Google Patents

Method and system for location finding in a wireless local area network Download PDF

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US20040203870A1
US20040203870A1 US10225267 US22526702A US2004203870A1 US 20040203870 A1 US20040203870 A1 US 20040203870A1 US 10225267 US10225267 US 10225267 US 22526702 A US22526702 A US 22526702A US 2004203870 A1 US2004203870 A1 US 2004203870A1
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location
arrival
wireless
signal
time
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US10225267
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Daniel Aljadeff
Yair Granot
Shalom Tsruya
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Aeroscout Ltd
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Aeroscout Ltd
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATIONS NETWORKS
    • H04W64/00Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205Details
    • G01S5/021Calibration, monitoring or correction
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/06Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements

Abstract

A method and system for location finding in a wireless local area network (LAN) enables enhanced security via network intrusion management and connection access management, as well as providing a mechanism for physically mapping a wireless network. Multiple receivers are employed to determine time-difference-of-arrival (TDOA) of signals transmitted from a wireless device. The location of the transmitting device is determined by triangulating between multiple receivers. The receivers may be devices within the wireless network that have been enhanced to include TDOA capability, or multiple dedicated location units may be employed within the wireless network or a wired network that may be a completely separate infrastructure depending on the requirements of a particular installation.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • The present application is related to previously-filed United States patent applications assigned to the same assignee: “METHOD AND APPARATUS FOR ENHANCING SECURITY IN A WIRELESS NETWORK USING DISTANCE MEASUREMENT TECHNIQUES”, Ser. No. 10/156,244, filed May 24, 2002 and “METHOD AND APPARATUS FOR INTRUSION MANAGEMENT IN A WIRELESS NETWORK USING PHYSICAL LOCATION DETERMINATION”, Ser. No. 10/171,427, filed Jun. 13, 2002. The specifications of the above-referenced U.S. patent applications are herein incorporated by reference.[0001]
  • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention [0002]
  • The present invention relates generally to wireless networks, and more specifically, to a method and system for determining the physical location of devices within a wireless network. [0003]
  • 2. Background of the Invention [0004]
  • A multitude of wireless communications systems are in common use today. Mobile telephones, pagers and wireless-connected computing devices such as personal digital assistants (PDAs) and laptop computers provide portable communications at virtually any locality. Wireless local area networks (WLANs) and wireless personal area networks (WPANs) according to the Institute of Electrical and Electronic Engineers (IEEE) specifications 802.11 (WLAN) (including 802.11a, 802.11b, etc.), 802.15.1 (WPAN) and 802.15.4 (WPAN-LR) also provide wireless interconnection of computing devices and personal communications devices, as well as other devices such as home automation devices. [0005]
  • Within the above-listed networks and wireless networks in general, it is desirable to know the location of devices for operation of location-based services, mapping of network facilities, and security. The above-incorporated patent applications describe wireless networks in which intrusion management and connection access control use a physical location determination as an indicator of the desirability of a particular connection to a wireless device. It is further desirable to provide services based on the location of a device, such as coupling of a portable device to a workstation when the devices are in proximity, or provision of a financial transaction menu when the portable device is brought in proximity with a transaction terminal. [0006]
  • Techniques that may be used to determine location are disclosed in the above-incorporated patent applications. The techniques include loop delay measurement for distance determination or received signal strength measurement (RSSI), time-difference-of-arrival techniques (TDOA), and angle-of-arrival techniques (AOA) for location finding. However, the infrastructure of present-day wireless networks has not been adapted to provide physical location determination. [0007]
  • Existing systems that determine the physical location of assets (that may include wireless network devices) typically use a separate radio-frequency identification (RFID) tag attached to the asset. The RFID tag broadcasts a signal, separate from the wireless network signals and protocols, that can be received at a short distance by a specially adapted receiver. [0008]
  • The use of tags for locating wireless network devices adds cost and complexity to the wireless network. Also, the tags are typically battery-operated devices that are attached to the asset, and as such have a limited life or will require replacement of the power source. Further, the separate attachment of tags is an inconvenience and is subject to incorrect tagging or tampering such as removal from the asset or relocation to another asset. [0009]
  • Therefore, it would be desirable to provide a method and system for location finding in a wireless network, so that the physical location of wireless network devices may be determined, and without adding tags or using special signals for determining the location of wireless network devices. [0010]
  • SUMMARY OF THE INVENTION
  • The above objectives of physically locating devices in a wireless network is achieved in a method and system. The method is embodied in a system that determines a physical location of a wireless device by comparing the time difference between signals received from the wireless device at multiple receiving stations. The arrival times of the signals are sent from each of the multiple receiving stations to a master unit, where they are compared to known physical location information for the receiving stations stored within the master unit. The master unit then determines the location of the wireless device in conformity with the differences between arrival times at the multiple receiving stations and their known locations. The location of standard wireless network devices having no special location-finding circuitry can be determined by the location units and standard network signaling can be detected and time difference measurements performed thereon to determine the locations of standard network devices. [0011]
  • The receiving stations may be transceivers, receive only devices or devices performing other network functions that have been enhanced to include embodiments of the present invention. The receiving stations further may be hard-wired to a network channel to provide secure sharing of time difference data, or the time difference data may be communicated via the wireless network channels or via other wireless means. The master device may also be one of the receiving stations. [0012]
  • The foregoing and other objectives, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiment of the invention, as illustrated in the accompanying drawings. [0013]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a pictorial diagram depicting a wireless network in accordance with an embodiment of the present invention. [0014]
  • FIG. 2 is a block diagram of a location finding unit in accordance with an embodiment of the present invention. [0015]
  • FIG. 3 is a graph depicting operation of multiple location finding units in accordance with an embodiment of the present invention. [0016]
  • DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
  • The present invention provides location finding within a wireless network, such as a WLAN (e.g., IEEE 802.11) or WPAN network, by determining a time-difference-of-arrival (TDOA) profile for signals received from wireless devices connected to or attempting to connect to the wireless network. Once the location of a wireless device is determined via the TDOA profile, location-based services can be provided, the device can be mapped in a network facility map, and security can be managed in conformity with the device's location. In contrast to the use of RFID tags, the present invention provides a wireless network with location-finding capability where no special signaling (e.g., the separate channels used by the RFID tags) and no separate device or tag is required. [0017]
  • Existing wireless network devices (generally the access points or “APs”) may be enhanced to provide a TDOA measurement of physical device location without adding a separate infrastructure, thereby providing position determination and consequent enhanced network security with low incremental cost. Alternatively, a separate infrastructure employing a series of dedicated location finding units may be added to a wireless network facility for providing device location information, avoiding the need to replace installed devices or otherwise reconfigure the wireless network. By adding a set of dedicated location finding units, standard network signals (e.g., request-to-send (RTS), clear-to-send (CTS) and beacon signals (broadcast) can be observed and used to determine the location of the transmitting devices) and standard wireless network devices can be located without requiring any modification to the located devices. [0018]
  • In TDOA techniques, the location of a transmitting source can be determined by triangulation based on the timing between the signal arrivals at the multiple receivers. Referring now to the figures and in particular to FIG. 1, a wireless network [0019] 10 within which the present invention is embodied is depicted in a pictorial diagram. Access points (APs) 14A-14C include time-of-arrival (TOA) electronics and software for measuring the arrival time of signals from other wireless network devices. One such device, wireless device 16 is depicted at the intersection of two hyperbolic curves 18A and 18B. Curves 18A and 18B represent points for which the difference between TOAs for a pair of locating device (APs 14A and 14C for curve 18B and APs 14B and 14C for curve 18A) is a constant. Therefore, once a pair of TOAs are determined by two of APs 14A-C, a curve may be drawn that intersects the location of the device that transmitted the signal received by the pair of APs. The TOA difference from another pair of APs is then used to determine a second curve and the intersection of the two curves yields the physical location of the transmitting device. The curves are hyperbolic with foci a the location of each of the APs in the pair, since the hyperbolic curve represents the set of points for which the difference between the distance to the two foci is a constant. A particular TOA difference determines the particular curve (i.e., a new curve is generated for each measurement) and represents all of the possible positions of the transmitting device for the determined TOA difference (TDOA) between a pair of receivers. There are two hyperbolic curves that satisfy the absolute value time difference location equation, but the sign of the time difference determines the proper curve, as for negative signs, the hyperbolic curve on which the transmitting device lies is the one closest to the base station for which the time or arrival was subtracted.
  • Extending the above-described technique, if at least three receivers are employed, it is possible to locate a transmitting device in two dimensions via the intersection of the two curves generated by two pairs of receivers is detected. The technique can be further extended to three-dimensional space using hyperbolic sections and/or additional pairs of receivers can be used to reduce error in measurement by interpolating between location results or rejecting location results that are bad statistical fits for the measurement. [0020]
  • The curve calculations described above are performed by a master unit MST (which may be one of the location units or software executing within of another network device) that receives the TOA information from each of the location units (APs [0021] 14A-C in the exemplary embodiment), calculates the differences and determines the location of the transmitting device via the intersection of the above-described hyperbolic curves. Master unit MST may also provide synchronization between the location units (or an independent synchronization mechanism may be employed) and control of the location finding process by requesting that the location units capture TOA information and send the TOA information to master unit MST.
  • Generally, the present invention uses wireless network signals that are already in place for network communications and while the system of the present invention may monitor communications without intervening in wireless network operation, active location finding may be performed in accordance with an embodiment of the present invention. A useful protocol is to transmit a request-to-send to a particular wireless network device to be located. The TDOA computations can be performed on the clear-to-send response generated by the particular device. In the above-described manner, the wireless network (or a particular device only) may be polled in order to obtain low-latency location information for a device, the entire network or a portion thereof. [0022]
  • Referring now to FIG. 2, an enhanced wireless network device, in which an embodiment of the present invention is included, is depicted in a block diagram. Location unit [0023] 20 may be a dedicated location unit, or may be a wireless network device having enhanced features for location determination according to TDOA measurements. A WLAN transmitter/receiver 22A is coupled to an antenna 21 for receiving wireless network signals, which will generally be digital spread-spectrum signals (DSSS). A DSSS baseband processor 24A detects and decodes the DSSS signals and passes the decoded information to a media access control (MAC) processor 26A that generates MAC (layer 3) network packets and passes then to a transmission control protocol/Internet protocol (TCP/IP) interface 28 for conversion to the TCP/IP (layer 4) packets for communication with the network-coupled device. In the return direction, TCP/IP packets received from the network-coupled device at TCP/IP interface 28 are converted to MAC packets by MAC processor 26A and are passed for encoding (DSSS modulation) to DSSS baseband processor 24A, which provides a signal input to the transmit portion of WLAN transmitter/receiver 22A. WLAN transmitter/receiver 22A transmits a wireless network signal to other network devices via antenna 21.
  • A location signal section is provided by a second WLAN transmitter/receiver [0024] 22B (or a single transmitter/receiver can be used for the location section and network section of the location unit as long as the TOA measurement requirements are fulfilled by the receiver design). WLAN transmitter/receiver 22B receives a signal from antenna 21 and sends it to a special DSSS processor 24B that determines the TOA of the received signal. The TOA information is passed to a location controller that includes a MAC interface 26B coupled to MAC processor 26A in the network section, so that the TOA information can be communicated to a master unit within the wireless network. Alternatively, the communications path from MAC interface 26B can be passed to a non-wireless Ethernet interface or other wired LAN interface for communicating the TOA information to the master unit.
  • The signaling components of location unit [0025] 20 are depicted as two separate subsystems coupled to the same antenna 21, but the structure of a wireless network device in accordance with embodiments of the present invention may be varied. For a location-only unit (i.e., a device that provides only the location-finding capability of the present invention without serving as a wireless network access point or other devices) may be implemented by including only the location signal section comprising WLAN transmitter/receiver 22B coupled to antenna 21 and DSSS processor 24B. Alternatively a fully network capable wireless device may include all of the depicted elements, but the transmitter/receiver blocks and DSSS processing blocks may be merged as mentioned above with respect to the transmitter/receiver, so that the location finding capabilities of the present invention are integrated within the standard wireless network device electronics. However, while standard signal processing blocks for a wireless network device generally process only the messages encoded for the address of the device (message level detection), location units decode the symbol level of these otherwise undeciphered messages to determine time of arrival information. If the location unit itself is addressed, or the location unit knows the address of another wireless device, message level detection can further enhance the signal to noise ratio of the location finding. The message level detection improves the signal to noise ratio of the location measurement by using known address information to further decode the message, permitting rejection of spurious signals, and raising the confidence of the measurement.
  • Referring now to FIG. 3, details of DSSS processor [0026] 24B are depicted in a block diagram. The decode input accepts signals from a receiver (WLAN transmitter/receiver 22B) and a PN sequence matched filter 32 correlates the location signal to provides a series of samples in (I,Q) pairs that are stored in a sample buffer 33. Matched filter 32 provides increased immunity from multipath effects due to reflections within the network facility. Therefore, the locations of access points (or another network device used to perform location measurements) do not need to be optimized to achieve accurate location finding results. If the immunity to multipath effects was lower than that provided by the system of the present invention, the position of the transmitting devices (generally access points being observer) and location units would require careful control of placement in order to avoid location error due to multipath effects. In some multipath environments, it would not be possible to locate all of the devices such that multipath error could be sufficiently reduced.
  • A Time Slot Start signal is provided by WLAN transmitter/receiver [0027] 22B and is used to start the sampling process via a timer latch 35. A timebase 36 provides synchronization of the location unit containing DSSS processor 24B to the other location units, so that the TOA information is precisely related among the locating units and the TDOA differences computed are accurate. A digital signal processor (DSP) 34 computes the TOA of a received signal and transmits the TOA information to the master unit over the wireless network. Location controller and MAC interface 26B sends the TOA information to MAC processor 26A which formats the TOA message and TCP/IP interface 28 sends the message through the wireless network to the master station.
  • DSP [0028] 34 calculates a best-estimate of the TOA for the received signal by performing coherent or non-coherent detection. Coherent detection at the message level is preferred if information about the transmitted message and signal is available such as frequency deviation of the signal and content of the message. In either case, coherent detection is performed at the symbol level by matched filter 32, providing a high signal to noise ratio (SNR) for the TOA measurement.
  • The signal/message detection techniques differ in complexity and performance. While coherent detection provides the best theoretical performance, the non-coherent detector represents a simpler implementation with potentially reduced performance. One of the important advantages of the location method described above is its ability to perform well in low signal to noise ratios (SNR). Even if the receiver cannot decode the WLAN message due to noise, the TOA may still be determined with adequate accuracy. Signal energy detection techniques using mean-square estimation as are well known in the art of signal detection may be used to estimate the greatest likelihood arrival time. Other suitable detection algorithms may also be used depending on the type of signals used and the desired complexity of the detection hardware and/or processors. [0029]
  • While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form, and details may be made therein without departing from the spirit and scope of the invention. [0030]

Claims (30)

    What is claimed is:
  1. 1. A method for determining the location of a wireless device within a wireless local area network (LAN), said method comprising:
    receiving a wireless LAN signal from said wireless device at multiple location units;
    in response to said receiving, determining multiple times of arrival of said standard wireless LAN signal at each corresponding one of said multiple location units;
    sending said times of arrival from each of said corresponding multiple location units to a master unit; and
    determining, within said master unit, the location of said wireless device by comparing location information for said multiple location units with said multiple times of arrival to determine said location of said wireless device.
  2. 2. The method of claim 1, wherein said master unit is one of said multiple location units, whereby said sending said time of arrival is not performed for said time of arrival determined at said master unit.
  3. 3. The method of claim 1, further comprising synchronizing a timer in each of said location units, whereby a precise time relationship between said multiple times of arrival is maintained.
  4. 4. The method of claim 1, wherein each of said location units is coupled to said master unit via a wired network, and wherein said sending said times of arrival is performed over said wired network.
  5. 5. The method of claim 1, wherein said sending is performed over said wireless network.
  6. 6. The method of claim 1, further comprising transmitting a request-to-send signal to said wireless device, and wherein said receiving receives a clear-to-send from said wireless device issued in response to said request-to-send signal.
  7. 7. The method of claim 1, wherein said receiving further comprises:
    filtering said received signal with a matched filter;
    sampling and storing quadrature symbol detection outputs of said matched filter; and
    subsequently computing an estimate of said time of arrival of said received signal.
  8. 8. The method of claim 7, wherein said computing computes said estimate of said time of arrival in conformity with a maximal mean-square profile of said received signal correlated with a spread-spectrum sequence.
  9. 9. The method of claim 6, wherein said computing further computes said estimate of said time of arrival in conformity with a maximal mean-square profile of said received signal convolved with a predetermined message sequence.
  10. 10. A wireless local area network (LAN), comprising:
    a plurality of location units for receiving a wireless LAN signal transmitted by a wireless device within said wireless LAN and determining a time of arrival for said received signal;
    at least one master unit for receiving said time of arrival from each of said location units, whereby said location of said wireless devices is be determined in conformity with said time of arrival.
  11. 11. The wireless LAN of claim 10, wherein said master unit is one of said multiple location units.
  12. 12. The wireless LAN of claim 10, wherein each of said location units comprises a timebase for maintaining precision in said time of arrival among said location units.
  13. 13. The wireless LAN of claim 12, wherein said master unit further synchronizes said timebase in each of said location units by sending a synchronization message to said location units.
  14. 14. The wireless LAN of claim 10, wherein each of said location units is coupled to said master unit via a wired network, and wherein said time of arrival is sent from said location units to said master unit over said wired network.
  15. 15. The wireless LAN of claim 10, wherein said time of arrival is sent from said location units to said master unit over said wireless network.
  16. 16. The wireless LAN of claim 10, further comprising an location measurement initiating unit that transmits a request-to-send signal to said wireless device, and wherein said wireless LAN signal is a clear-to-send message sent from said wireless device in response to said request-to-send signal.
  17. 17. The wireless LAN of claim 16, wherein said measurement initiating unit is one of said location units.
  18. 18. The wireless LAN of claim 16, wherein said measurement initiating unit is said master unit.
  19. 19. The wireless LAN of claim 10, wherein each of said location units comprises a receiver including:
    a matched filter for filtering said received signal;
    a sampler and memory for sampling and storing quadrature symbol detection outputs of said matched filter; and
    a signal processor for computing an estimate of said time of arrival of said received signal from said stored samples.
  20. 20. The wireless LAN of claim 19, wherein said signal processor further computes said estimate of said time of arrival in conformity with a maximal mean-square profile of said received signal correlated with a spread-spectrum sequence.
  21. 21. The wireless LAN of claim 20, wherein said signal processor further computes said estimate of said time of arrival in conformity with a maximal mean-square profile of said received signal convolved with a predetermined message sequence.
  22. 22. A location unit, comprising:
    a receiver for receiving wireless local area network (LAN) signals from a wireless device in a wireless network;
    a time measurement unit coupled to said receiver for determining the time of arrival of said signals from said wireless device; and
    an interface for sending said time of arrival information to a master unit.
  23. 23. The location unit of claim 22, wherein said receiver comprises a spread-spectrum receiver and wherein said time measurement unit comprises a processor for determining said time of arrival in conformity with samples stored from an output of said receiver.
  24. 24. The location unit of claim 23, wherein said processor computes an estimated time of arrival via mean-square estimation.
  25. 25. The location unit of claim 22, wherein said wireless LAN signal is a clear-to-send signal received from said wireless device.
  26. 26. A master unit, comprising:
    a data interface for receiving from multiple external location units, times of arrival of a standard wireless local area network (LAN) signal received from a wireless device by said multiple external location units;
    a database including physical location information of said multiple external location units; and
    a computation unit for comparing said times of arrival from said multiple external location units in conformity with location information retrieved from said database to determine a location of wireless devices in a wireless LAN.
  27. 27. The master unit of claim 26, wherein said computation unit computes differences between pairs of said time of arrival received from pairs of said location units, projects a hyperbolic curve for each of said differences, said curve having foci at physical locations of said pair of location units associated with a corresponding difference, and determines said location of said wireless device in conformity with an intersection of said hyperbolic curves.
  28. 28. The master unit of claim 26, wherein said master unit transmits a command to issue a request-to-send signal to said wireless device over said data interface, and wherein said wireless LAN signal is a clear-to-send signal transmitted by said wireless device in response to said request-to-send signal.
  29. 29. The master unit of claim 26, wherein said master unit includes a wireless LAN transmitter, and wherein said master unit transmits a request-to-send signal to said wireless device, and wherein said wireless LAN signal is a clear-to-send signal transmitted by said wireless device in response to said request-to-send signal.
  30. 30. The master unit of claim 26, wherein said master unit includes a wireless LAN receiver, and wherein said master unit receives said wireless LAN signal and measures a time of arrival at said master unit of said wireless LAN signal, and wherein said computation unit further compares said time of arrival at said master unit of said wireless LAN signal.
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PCT/IL2003/000683 WO2004019559A3 (en) 2002-08-20 2003-08-18 Method and system for location finding in a wireless local area network
JP2004530484A JP2005536944A (en) 2002-08-20 2003-08-18 Detection method and system location in a wireless local area network
US10677440 US6968194B2 (en) 2002-08-20 2003-10-02 Method and system for synchronizing location finding measurements in a wireless local area network

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Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040157621A1 (en) * 2003-02-07 2004-08-12 Hitachi., Ltd. Positioning system and method based on time difference of arrival
US20050105600A1 (en) * 2003-11-14 2005-05-19 Okulus Networks Inc. System and method for location tracking using wireless networks
US6933888B1 (en) * 2004-06-14 2005-08-23 Bae Systems Information And Electronic Systems Integration Inc. Multi-ship coherent geolocation system
US20050198933A1 (en) * 2004-03-15 2005-09-15 Klein John A. Deck for mowers
US20050247775A1 (en) * 2003-12-30 2005-11-10 Gloekler John S Methods and apparatus of meshing and hierarchy establishment for tracking devices
US20050258955A1 (en) * 2003-12-30 2005-11-24 Gloekler John S Method and apparatus for aggregating and communicating tracking information
US20050275588A1 (en) * 2004-05-25 2005-12-15 Richard Schiffmiller Coherent geolocation system
US20060068853A1 (en) * 2004-09-28 2006-03-30 Thomas Dejanovic GPS receiver having RF front end power management and simultaneous baseband searching of frequency and code chip offset
US20060122944A1 (en) * 2004-07-20 2006-06-08 Ryan Philip J Methods and systems for enabling communication to and from asset tracking devices
US20060125694A1 (en) * 2004-07-30 2006-06-15 Thomas Dejanovic Location determination method and system for asset tracking devices
US20060203762A1 (en) * 2005-03-10 2006-09-14 Taubenheim David B Method and apparatus for transmitting location data within a communication system
US20070184818A1 (en) * 2005-02-28 2007-08-09 Research In Motion Limited Method and system for enhanced security using location based wireless authentication
US20070254015A1 (en) * 2006-04-28 2007-11-01 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Sanitizing surfaces
US20090232703A1 (en) * 2006-03-31 2009-09-17 Searete Llc Methods and systems for monitoring sterilization status
US20090315717A1 (en) * 2005-06-16 2009-12-24 Koninklijke Philips Electronics N.V. Tracking rfid objects with integrated communication link
US20100090837A1 (en) * 2006-03-31 2010-04-15 Searete Llc Methods and systems for sterilization
US20100214948A1 (en) * 2005-06-23 2010-08-26 Koninklijke Philips Electronics, N.V. Apparatus and method of configuring a device in a network
US20110002821A1 (en) * 2006-03-31 2011-01-06 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Surveying sterilizer methods and systems
US20110037573A1 (en) * 2009-08-11 2011-02-17 Samsung Electronics Co. Ltd. Apparatus and method for providing information of goods in mobile terminal
US20120113971A1 (en) * 2010-11-08 2012-05-10 Qualcomm Incorporated Efficient wlan discovery and association
US8277724B2 (en) 2006-03-31 2012-10-02 The Invention Science Fund I, Llc Sterilization methods and systems
US20130115945A1 (en) * 2011-11-08 2013-05-09 Microsoft Corporation Service-assisted network access point selection
US8645569B2 (en) * 2004-03-12 2014-02-04 Rockwell Automation Technologies, Inc. Juxtaposition based machine addressing
US8932535B2 (en) 2006-03-31 2015-01-13 The Invention Science Fund I, Llc Surveying sterilizer methods and systems
EP2876579A1 (en) 2013-11-20 2015-05-27 Aeroscout Ltd Identification tag and location system
US9467862B2 (en) 2011-10-26 2016-10-11 Milwaukee Electric Tool Corporation Wireless tracking of power tools and related devices
US9466198B2 (en) 2013-02-22 2016-10-11 Milwaukee Electric Tool Corporation Wireless tracking of power tools and related devices
WO2016197002A1 (en) * 2015-06-05 2016-12-08 Ubiqomm Llc Position determination using time of arrival measurements in a wireless local area network
US9723451B2 (en) * 2015-11-17 2017-08-01 Sony Mobile Communications, Inc. Providing location information of a terminal in a communication network

Families Citing this family (91)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10055289B4 (en) * 2000-11-08 2006-07-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. System for determining the position of an object
US7079812B2 (en) * 2002-05-16 2006-07-18 Cognio, Inc. Systems and methods for interference mitigation with respect to periodic interferers in short-range wireless applications
US6889052B2 (en) * 2002-08-30 2005-05-03 Motorola, Inc. Method and apparatus for generating time of arrival estimates for use in determining a location
US7359711B2 (en) * 2002-10-31 2008-04-15 Siemens Communications, Inc. Methods and apparatus for improving accuracy of radio timing measurements
US20040087277A1 (en) * 2002-10-31 2004-05-06 Siemens Information And Communication Mobile Llc. Method and apparatus for improving accuracy of radio timing measurements
US8971913B2 (en) 2003-06-27 2015-03-03 Qualcomm Incorporated Method and apparatus for wireless network hybrid positioning
US8483717B2 (en) 2003-06-27 2013-07-09 Qualcomm Incorporated Local area network assisted positioning
US7412246B2 (en) * 2003-10-06 2008-08-12 Symbol Technologies, Inc. Method and system for improved wlan location
US7406320B1 (en) 2003-12-08 2008-07-29 Airtight Networks, Inc. Method and system for location estimation in wireless networks
US7856209B1 (en) 2003-12-08 2010-12-21 Airtight Networks, Inc. Method and system for location estimation in wireless networks
US7002943B2 (en) 2003-12-08 2006-02-21 Airtight Networks, Inc. Method and system for monitoring a selected region of an airspace associated with local area networks of computing devices
WO2005067686A3 (en) * 2004-01-12 2008-05-29 Andrew Corp Method and apparatus for synchronizing wireless location servers
US7440434B2 (en) 2004-02-11 2008-10-21 Airtight Networks, Inc. Method and system for detecting wireless access devices operably coupled to computer local area networks and related methods
US7339914B2 (en) 2004-02-11 2008-03-04 Airtight Networks, Inc. Automated sniffer apparatus and method for monitoring computer systems for unauthorized access
US7319878B2 (en) 2004-06-18 2008-01-15 Qualcomm Incorporated Method and apparatus for determining location of a base station using a plurality of mobile stations in a wireless mobile network
JP4385293B2 (en) 2004-07-05 2009-12-16 ソニー株式会社 Wireless communication system
US7855973B2 (en) * 2004-07-14 2010-12-21 Sony Ericsson Mobile Communications Ab Apparatus, methods and computer program products for transmission of data over an adjustable synchronous radio channel
US20060223447A1 (en) * 2005-03-31 2006-10-05 Ali Masoomzadeh-Fard Adaptive down bias to power changes for controlling random walk
CA2550812A1 (en) * 2005-06-22 2006-12-22 Axigon Healthcare Technologies Incorporated Two-way wireless monitoring system and method
GB2427973B (en) * 2005-07-01 2008-11-12 Roke Manor Research Apparatus and method for determining receiver performance in a multilateration system
US20070021127A1 (en) * 2005-07-22 2007-01-25 Haihong Zheng Method and apparatus for supporting location service over radio communication systems
US7411937B2 (en) * 2005-08-09 2008-08-12 Agilent Technologies, Inc. Time synchronization system and method for synchronizing locating units within a communication system using a known external signal
US7257413B2 (en) 2005-08-24 2007-08-14 Qualcomm Incorporated Dynamic location almanac for wireless base stations
CN106054129A (en) * 2005-11-07 2016-10-26 高通股份有限公司 Positioning for wlans and other wireless networks
RU2390791C2 (en) 2005-11-07 2010-05-27 Квэлкомм Инкорпорейтед Positioning for wlan and other wireless networks
WO2007066963A1 (en) * 2005-12-08 2007-06-14 Electronics And Telecommunications Research Institute Method for transferring data frame end-to-end using virtual synchronization on local area network and network devices applying the same
US7710933B1 (en) 2005-12-08 2010-05-04 Airtight Networks, Inc. Method and system for classification of wireless devices in local area computer networks
US20070184852A1 (en) * 2006-01-17 2007-08-09 Johnson David W Method and system for location of objects within a specified geographic area
JP4445951B2 (en) 2006-01-24 2010-04-07 株式会社エヌ・ティ・ティ・ドコモ Area estimation system and the area estimation method
US7450069B2 (en) * 2006-02-27 2008-11-11 Olympus Corporation Technology Of America Ranging system and method
US7933612B2 (en) * 2006-02-28 2011-04-26 Microsoft Corporation Determining physical location based upon received signals
US8892065B2 (en) 2006-04-26 2014-11-18 Zebra Enterprise Solutions Corp. Method, apparatus, and computer program product for wireless signal storage with signal recognition detection triggering
US8768343B2 (en) 2006-03-31 2014-07-01 Zebra Enterprise Solutions Corp Wireless local area network receiver and associated method
GB0607864D0 (en) * 2006-04-20 2006-05-31 Ubisense Ltd Calibration Of A Location System
US9362976B2 (en) * 2006-04-26 2016-06-07 Zih Corp. Wireless local area network system and receiver adapted for use thereof and associated method
US7656855B2 (en) * 2006-04-29 2010-02-02 At&T Intellectual Property Ii, Lp Arrangement for synchronizing access points in WLAN using direct-sequence spread spectrum signaling
US8248959B2 (en) * 2006-05-30 2012-08-21 Telecom Ventures, L.L.C. Methods, apparatus and computer program products for beacon generation and processing in an OFDM communications system
KR100738370B1 (en) 2006-06-12 2007-07-05 주식회사 아이웨어 System and method for location search of person in group
US7768963B2 (en) 2006-07-07 2010-08-03 Skyhook Wireless, Inc. System and method of improving sampling of WLAN packet information to improve estimates of Doppler frequency of a WLAN positioning device
US8576829B2 (en) * 2006-08-08 2013-11-05 Aeroscout, Ltd. Multi-channel TDOA system
US8665799B2 (en) 2006-09-14 2014-03-04 Qualcomm Incorporated Beacon assisted cell search in a wireless communication system
US7619523B2 (en) 2006-09-25 2009-11-17 American Air Liquide, Inc. Gas cylinders monitoring by wireless tags
EP2512085A1 (en) * 2006-10-03 2012-10-17 Qualcomm Incorporated Synchronization Transmissions in a Wireless Communication System
US7729707B2 (en) * 2006-10-24 2010-06-01 Aeroscout, Inc. Method and system for synchronization offset reduction in a TDOA location system
US9226257B2 (en) 2006-11-04 2015-12-29 Qualcomm Incorporated Positioning for WLANs and other wireless networks
KR101061662B1 (en) * 2006-11-06 2011-09-01 콸콤 인코포레이티드 Cell-based navigation beacons in a wireless communication system
US7856234B2 (en) 2006-11-07 2010-12-21 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
JP2008128726A (en) * 2006-11-17 2008-06-05 Yokohama National Univ Positioning system, device and method using particle filter
US8208939B2 (en) * 2007-02-05 2012-06-26 Aeroscout Ltd. Dual bandwidth time difference of arrival (TDOA) system
US8005487B2 (en) * 2007-06-14 2011-08-23 Intel Corporation Techniques for optimization of location determination in wireless network
EP2107691B1 (en) * 2007-06-22 2013-01-09 Feig Electronic GmbH Wireless method for gates
JP4616315B2 (en) 2007-08-13 2011-01-19 株式会社エヌ・ティ・ティ・ドコモ Area estimation system, an area estimation method and the area estimation apparatus
KR101418380B1 (en) 2007-09-21 2014-07-11 삼성전자주식회사 Mobile communication systems and ranging methods thereof
US7970894B1 (en) * 2007-11-15 2011-06-28 Airtight Networks, Inc. Method and system for monitoring of wireless devices in local area computer networks
KR100957215B1 (en) * 2008-03-07 2010-05-11 한국전자통신연구원 Method for estimating location of mobile node in wireless sensor network
US20090273465A1 (en) * 2008-05-02 2009-11-05 Adi Shamir Room separation in a wlan based rtls and method therefor
EP2294439A4 (en) 2008-05-26 2015-04-08 Commw Scient Ind Res Org Measurement of time of arrival
US20090310593A1 (en) * 2008-06-17 2009-12-17 Qualcomm Incorporated Self-positioning access points
WO2010000036A1 (en) * 2008-07-04 2010-01-07 Commonwealth Scientific And Industrial Research Organisation Wireless localisation system
US8471706B2 (en) * 2008-09-05 2013-06-25 John Schuster Using a mesh of radio frequency identification tags for tracking entities at a site
US8045576B2 (en) * 2008-10-14 2011-10-25 Texas Instruments Incorporated Methods and apparatus to manage power consumption in wireless local area network devices
US8160609B2 (en) 2008-11-26 2012-04-17 Andrew Llc System and method for multiple range estimation location
US8249622B2 (en) 2008-11-26 2012-08-21 Andrew, Llc System and method for multiple range estimation location
EP2200383B1 (en) 2008-12-18 2013-06-19 Koninklijke KPN N.V. Method of determining a location of a mobile device and method of managing a list for use in such a method
EP2199818A1 (en) 2008-12-19 2010-06-23 Koninklijke KPN N.V. Method of determining a location of a mobile device and method of managing a list for use in such a method
EP2199819A1 (en) * 2008-12-19 2010-06-23 Koninklijke KPN N.V. Method of determining a location of a mobile device and method of managing a list for use in such a method
JP5168137B2 (en) * 2008-12-26 2013-03-21 ソニー株式会社 Communication device, a communication method, a program, an information management apparatus and communication system
US8914038B2 (en) * 2009-02-11 2014-12-16 Telefonaktiebolaget L M Ericsson (Publ) Method and arrangement for determining terminal position
US8249049B2 (en) * 2009-03-17 2012-08-21 Cisco Technology, Inc. Clock synchronization
DE102009055871A1 (en) * 2009-04-22 2010-10-28 Siemens Aktiengesellschaft A method for computer-assisted processing of measurements of characteristics of a radio network
US9407357B1 (en) * 2009-05-29 2016-08-02 Rockwell Collins, Inc. Systems and methods for radio node synchronization based on range calculations
US8022877B2 (en) 2009-07-16 2011-09-20 Skyhook Wireless, Inc. Systems and methods for using a satellite positioning system to detect moved WLAN access points
US9606219B2 (en) 2010-08-02 2017-03-28 Progeny Systems Corporation Systems and methods for locating a target in a GPS-denied environment
US8316155B2 (en) * 2010-12-17 2012-11-20 Microsoft Corporation Distributed robust clock synchronization
CN102185746A (en) * 2011-04-27 2011-09-14 深圳和而泰智能控制股份有限公司 Automatic layout method and system for indoor equipment
WO2012150750A1 (en) * 2011-05-01 2012-11-08 엘지전자 주식회사 Method and device for transmitting a synchronization signal in a wireless communication system
EP2525236B1 (en) 2011-05-16 2017-08-02 Nanotron Technologies GmbH Method and System for multipath reduction for wireless synchronizing and/or locating
WO2013088279A1 (en) * 2011-12-14 2013-06-20 Koninklijke Philips Electronics N.V. Wireless ranging.
US20130163453A1 (en) * 2011-12-27 2013-06-27 Xintian E. Lin Presence sensor with ultrasound and radio
WO2013124292A1 (en) 2012-02-21 2013-08-29 Karlsruher Institut für Technologie Method and system for simultaneous receiver calibration and object localisation for multilateration
JP5775651B2 (en) * 2012-07-11 2015-09-09 エンパイア テクノロジー ディベロップメント エルエルシー Mechanism for providing a private wireless network
US8995228B2 (en) 2012-10-22 2015-03-31 Symbol Technologies, Inc. Ultrasonic locationing using only time difference of arrival measurements
US8837558B1 (en) 2013-03-15 2014-09-16 Motorola Solutions, Inc. Systems, methods, and devices for improving signal detection in communication systems
KR101713035B1 (en) * 2013-05-26 2017-03-07 인텔 아이피 코포레이션 Apparatus, system and method of estimating a location of a mobile device
US9830424B2 (en) 2013-09-18 2017-11-28 Hill-Rom Services, Inc. Bed/room/patient association systems and methods
US9307424B2 (en) 2014-03-05 2016-04-05 Qualcomm Incorporated Calibration and tracking to assist inter-frequency measurements of LTE cell by WLAN radio
US9374727B2 (en) * 2014-03-05 2016-06-21 Qualcomm Incorporated Calibration and tracking to assist inter-frequency measurements of LTE cell by WLAN radio
US9641974B2 (en) 2014-12-10 2017-05-02 Qualcomm Incorporated Techniques for determining a position fix of an object using one or more mobile devices co-located with the object
WO2016189526A1 (en) * 2015-05-26 2016-12-01 Intraposition Ltd Real-time wireless positioning system and method thereof
CN106559870A (en) * 2015-09-30 2017-04-05 华为技术有限公司 Positioning method and device based on wireless network
US20170118235A1 (en) * 2015-10-27 2017-04-27 Sk Planet Co., Ltd. Method and apparatus for detecting abnormal state of beacon device in wireless mesh network and recording medium storing computer program for executing the method

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6154657A (en) * 1997-10-21 2000-11-28 Telefonaktiebolaget Lm Ericsson Smart subdivision of base station candidates for position location accuracy
US20010030625A1 (en) * 2000-01-12 2001-10-18 Doles Daniel T. Local clock-referenced DTOA geolocation system with wireless infrastructure
US20020080759A1 (en) * 2000-12-20 2002-06-27 Wherenet Corp Wireless local area network system with mobile access point station determination
US6414634B1 (en) * 1997-12-04 2002-07-02 Lucent Technologies Inc. Detecting the geographical location of wireless units
US20020086640A1 (en) * 2000-12-29 2002-07-04 Wherenet Corp Interference suppression for wireless local area network and location system
US20020098852A1 (en) * 2000-11-14 2002-07-25 Goren David P. Methods and apparatus for identifying as set location in communication networks
US20020164997A1 (en) * 2001-05-07 2002-11-07 Travis Parry Method and system for controlling selective wireless communication access
US6556832B1 (en) * 2000-02-04 2003-04-29 Qualcomm Incorporated Method and apparatus for evaluation of position location performance
US6577274B1 (en) * 2001-12-19 2003-06-10 Intel Corporation Method and apparatus for controlling access to mobile devices
US6768730B1 (en) * 2001-10-11 2004-07-27 Meshnetworks, Inc. System and method for efficiently performing two-way ranging to determine the location of a wireless node in a communications network
US6801782B2 (en) * 1999-08-02 2004-10-05 Itt Manufacturing Enterprises, Inc. Method and apparatus for determining the position of a mobile communication device

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4698781A (en) * 1983-08-01 1987-10-06 Spymark, Incorporated Systems for determining distances to and locations of features on a golf course
GB2270438B (en) * 1992-09-08 1996-06-26 Caterpillar Inc Apparatus and method for determining the location of a vehicle
US5732354A (en) * 1995-06-07 1998-03-24 At&T Wireless Services, Inc. Method and apparatus for determining the location of a mobile telephone
WO2001061883A2 (en) * 2000-02-17 2001-08-23 Pinpoint Corporation Method and apparatus for integrating wireless communication and asset location
US6356608B1 (en) * 1998-06-29 2002-03-12 Telefonaktiebolaget Lm Ericsson (Publ) Method, apparatus, and system for determining a location of a frequency synchronization signal
US6429809B1 (en) * 2001-01-30 2002-08-06 Qualcomm Incorporated Method and apparatus for determining location using a coarse position estimate
US6717516B2 (en) * 2001-03-08 2004-04-06 Symbol Technologies, Inc. Hybrid bluetooth/RFID based real time location tracking

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6154657A (en) * 1997-10-21 2000-11-28 Telefonaktiebolaget Lm Ericsson Smart subdivision of base station candidates for position location accuracy
US6414634B1 (en) * 1997-12-04 2002-07-02 Lucent Technologies Inc. Detecting the geographical location of wireless units
US6801782B2 (en) * 1999-08-02 2004-10-05 Itt Manufacturing Enterprises, Inc. Method and apparatus for determining the position of a mobile communication device
US20010030625A1 (en) * 2000-01-12 2001-10-18 Doles Daniel T. Local clock-referenced DTOA geolocation system with wireless infrastructure
US6556832B1 (en) * 2000-02-04 2003-04-29 Qualcomm Incorporated Method and apparatus for evaluation of position location performance
US20020098852A1 (en) * 2000-11-14 2002-07-25 Goren David P. Methods and apparatus for identifying as set location in communication networks
US20020080759A1 (en) * 2000-12-20 2002-06-27 Wherenet Corp Wireless local area network system with mobile access point station determination
US20020086640A1 (en) * 2000-12-29 2002-07-04 Wherenet Corp Interference suppression for wireless local area network and location system
US20020164997A1 (en) * 2001-05-07 2002-11-07 Travis Parry Method and system for controlling selective wireless communication access
US6768730B1 (en) * 2001-10-11 2004-07-27 Meshnetworks, Inc. System and method for efficiently performing two-way ranging to determine the location of a wireless node in a communications network
US6577274B1 (en) * 2001-12-19 2003-06-10 Intel Corporation Method and apparatus for controlling access to mobile devices

Cited By (47)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7139583B2 (en) * 2003-02-07 2006-11-21 Hitachi, Ltd. Positioning system and method based on time difference of arrival
US20040157621A1 (en) * 2003-02-07 2004-08-12 Hitachi., Ltd. Positioning system and method based on time difference of arrival
US20050105600A1 (en) * 2003-11-14 2005-05-19 Okulus Networks Inc. System and method for location tracking using wireless networks
US20050258955A1 (en) * 2003-12-30 2005-11-24 Gloekler John S Method and apparatus for aggregating and communicating tracking information
US7394372B2 (en) 2003-12-30 2008-07-01 G2 Microsystems Pty. Ltd. Method and apparatus for aggregating and communicating tracking information
US20050247775A1 (en) * 2003-12-30 2005-11-10 Gloekler John S Methods and apparatus of meshing and hierarchy establishment for tracking devices
US7212122B2 (en) 2003-12-30 2007-05-01 G2 Microsystems Pty. Ltd. Methods and apparatus of meshing and hierarchy establishment for tracking devices
US8645569B2 (en) * 2004-03-12 2014-02-04 Rockwell Automation Technologies, Inc. Juxtaposition based machine addressing
US20050198933A1 (en) * 2004-03-15 2005-09-15 Klein John A. Deck for mowers
US7315280B2 (en) * 2004-05-25 2008-01-01 Bae Systems Information And Electronics Systems Integration Inc. Coherent geolocation system
US20050275588A1 (en) * 2004-05-25 2005-12-15 Richard Schiffmiller Coherent geolocation system
US6933888B1 (en) * 2004-06-14 2005-08-23 Bae Systems Information And Electronic Systems Integration Inc. Multi-ship coherent geolocation system
US20060122944A1 (en) * 2004-07-20 2006-06-08 Ryan Philip J Methods and systems for enabling communication to and from asset tracking devices
US20060125694A1 (en) * 2004-07-30 2006-06-15 Thomas Dejanovic Location determination method and system for asset tracking devices
US7315281B2 (en) 2004-07-30 2008-01-01 G2 Microsystems Pty. Ltd. Location determination method and system for asset tracking devices
US20060068853A1 (en) * 2004-09-28 2006-03-30 Thomas Dejanovic GPS receiver having RF front end power management and simultaneous baseband searching of frequency and code chip offset
US7313421B2 (en) 2004-09-28 2007-12-25 G2 Microsystems Pty. Ltd. GPS receiver having RF front end power management and simultaneous baseband searching of frequency and code chip offset
US20070184818A1 (en) * 2005-02-28 2007-08-09 Research In Motion Limited Method and system for enhanced security using location based wireless authentication
US9014725B2 (en) * 2005-02-28 2015-04-21 Blackberry Limited Method and system for enhanced security using location based wireless authentication
WO2006098841A3 (en) * 2005-03-10 2007-05-31 Motorola Inc Method and apparatus for transmitting location data within a communication system
US7369524B2 (en) 2005-03-10 2008-05-06 Motorola, Inc. Method and apparatus for transmitting location data within a communication system
WO2006098841A2 (en) * 2005-03-10 2006-09-21 Motorola, Inc. Method and apparatus for transmitting location data within a communication system
US20060203762A1 (en) * 2005-03-10 2006-09-14 Taubenheim David B Method and apparatus for transmitting location data within a communication system
US9035772B2 (en) 2005-06-16 2015-05-19 Koninklijke Philips N.V. Tracking RFID objects with integrated communication link
US9801011B2 (en) 2005-06-16 2017-10-24 Koninklijke Philips N.V. Tracking RFID objects with integrated communication link
US20090315717A1 (en) * 2005-06-16 2009-12-24 Koninklijke Philips Electronics N.V. Tracking rfid objects with integrated communication link
US8665762B2 (en) * 2005-06-23 2014-03-04 Koninklijke Philips N.V. Apparatus and method of configuring a device in a network
US20100214948A1 (en) * 2005-06-23 2010-08-26 Koninklijke Philips Electronics, N.V. Apparatus and method of configuring a device in a network
US20090232703A1 (en) * 2006-03-31 2009-09-17 Searete Llc Methods and systems for monitoring sterilization status
US8758679B2 (en) 2006-03-31 2014-06-24 The Invention Science Fund I, Llc Surveying sterilizer methods and systems
US8277724B2 (en) 2006-03-31 2012-10-02 The Invention Science Fund I, Llc Sterilization methods and systems
US20110002821A1 (en) * 2006-03-31 2011-01-06 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Surveying sterilizer methods and systems
US8992837B2 (en) 2006-03-31 2015-03-31 The Invention Science Fund I, Llc Methods and systems for monitoring sterilization status
US8932535B2 (en) 2006-03-31 2015-01-13 The Invention Science Fund I, Llc Surveying sterilizer methods and systems
US20100090837A1 (en) * 2006-03-31 2010-04-15 Searete Llc Methods and systems for sterilization
US20070254015A1 (en) * 2006-04-28 2007-11-01 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Sanitizing surfaces
US20110037573A1 (en) * 2009-08-11 2011-02-17 Samsung Electronics Co. Ltd. Apparatus and method for providing information of goods in mobile terminal
US20120113971A1 (en) * 2010-11-08 2012-05-10 Qualcomm Incorporated Efficient wlan discovery and association
US9467862B2 (en) 2011-10-26 2016-10-11 Milwaukee Electric Tool Corporation Wireless tracking of power tools and related devices
US9019945B2 (en) 2011-11-08 2015-04-28 Microsoft Technology Licensing, Llc Service-assisted network access point selection
US8665847B2 (en) * 2011-11-08 2014-03-04 Microsoft Corporation Service-assisted network access point selection
US20130115945A1 (en) * 2011-11-08 2013-05-09 Microsoft Corporation Service-assisted network access point selection
US9949075B2 (en) 2013-02-22 2018-04-17 Milwaukee Electric Tool Corporation Wireless tracking of power tools and related devices
US9466198B2 (en) 2013-02-22 2016-10-11 Milwaukee Electric Tool Corporation Wireless tracking of power tools and related devices
EP2876579A1 (en) 2013-11-20 2015-05-27 Aeroscout Ltd Identification tag and location system
WO2016197002A1 (en) * 2015-06-05 2016-12-08 Ubiqomm Llc Position determination using time of arrival measurements in a wireless local area network
US9723451B2 (en) * 2015-11-17 2017-08-01 Sony Mobile Communications, Inc. Providing location information of a terminal in a communication network

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