Self-configuring wireless network location system

• US 8,155,662 B2
• Filed: 05/24/2007
• Issued: 04/10/2012
• Est. Priority Date: 02/19/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Zill, Brian D., Wolman, Alastair, Padhye, Jitendra D., Bahl, Paramvir, Chandra, Ranveer
• Primary Examiner(s): Kincaid, Lester
• Assistant Examiner(s): WOO, KUO-KONG
• Application Number:
  US11/753,536
• Publication Number:
  US 20080200181A1
• Time in Patent Office: 1,783 Days
• Field of Search: 455/435.1, 455/456.1, 455/456.2, 455/456.3, 455/456.6, 455/67.11, 455/445, 370/328, 370/310, 370/241, 702/186, 726/23
• US Class Current: 455/456.1
• CPC Class Codes: G01S 2205/02 Indoor
• CPC Class Codes: G01S 5/02524 Creating or updating the radio-map
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/0806 for initial configuration or provisioning, e.g. plug-and-play
• CPC Class Codes: H04L 41/0886 Fully automatic configuration
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

Wireless adapters are installed on one or more general purpose computing devices and are connected via a network in an enterprise environment. The adapters are densely deployed at known locations throughout the environment and are configured as air monitors. The air monitors monitor signals transmitted by one or more transceiver devices and records information about these signals. One or more analysis or inference engines may be deployed to obtain the recorded signal information and the air monitor locations to determine a location of the one or more wireless transceivers devices deployed in the environment.

Claims

1. A method comprising:

receiving a wireless signal transmitted by a transceiver device;

storing a signal strength indication for the received wireless signal;

determining a location of each one of a plurality of air monitors; and

determining a location of the transceiver device by correlating the determined location of one of the plurality of air monitors with a corresponding retrieved signal strength indication for the transceiver device, the correlating comprising;

commanding each of the plurality of air monitors to broadcast a probe signal;

storing, by each of the plurality of air monitors, probe signal strength indicators of received probe signals transmitted by each other of the plurality of air monitors; and

generating a profile based on the probe signal strength indicators and the determined locations of each of the plurality of air monitors.

2. The method as recited in claim 1 wherein the signal strength indication is stored in a data store, and wherein the method further comprises retrieving the stored signal strength indication from the data store, and wherein the determined location of the transceiver device is determined using the corresponding strongest retrieved signal strength indication for the transceiver device.

3. The method as recited in claim 2 wherein the wireless signal is received by the plurality of air monitors, and wherein the signal strength indication is stored in the data store by the plurality of air monitors.

4. The method as recited in claim 2 further comprising:

deriving from the wireless signal by each of the air monitors an address of the transceiver device;

storing in the data store with each of the air monitors the address of the transceiver device along with the signal strength indication; and

wherein the determining a location of the transceiver device includes receiving from each of the air monitors the address of the transceiver device.

5. The method as recited in claim 1, wherein at least one air monitor includes a computer, wherein a user accesses a network with that computer, and determining the location of the at least one air monitor comprises:

monitoring an access history by the user of the computer, the access history comprising a logon to the computer by the user;

identifying in the data store a record containing a pre-assigned location of the user based on the access history;

associating the pre-assigned location with the at least one air monitor; and

storing physical coordinates for the pre-assigned location in the data store as the location of the at least one air monitor.

6. The method as recited in claim 1 further comprising automatically generating a map identifying the location of the air monitors and the transceiver device.

7. The method as recited in claim 1, wherein determining the location of the transceiver device by correlating the determined location of one of the plurality of air monitors with the corresponding retrieved signal strength indication for the transceiver device comprises:

determining relationships in an enterprise environment between a distance between air monitors and the strength of signals received by each of the air monitors;

setting an initial location of the transceiver device based on the signal strength of the signal from the transceiver device as indicated by a some of the plurality of air monitors; and

adjusting the initial location using the determined relationship.

8. The method as recited in claim 7 wherein determining relationships comprises generating a curve corresponding to the determined relationships in the enterprise environment;

and wherein adjusting the initial location comprises setting a distance between the air monitor and the transceiver device based on an intersection of the corresponding signal strength for the air monitor as received from the transceiver and the curve, and modifying the initial location using the set distance.

9. The method as recited in claim 1, wherein determining a location of the transceiver device by correlating the determined location of one of the plurality of air monitors with the corresponding retrieved signal strength indication for the transceiver device comprises:

obtaining signal strength for the wireless signal from the transceiver device as received by the plurality of air monitors;

selecting some of the plurality of air monitors as air monitors indicating a signal strength for the transceiver device as a predetermined amount of a maximum signal strength for the transceiver device for all the air monitors;

determining a geographic center point of the some of the plurality of air monitors; and

setting the location of the transceiver device as the geographic center point of the some of the plurality of air monitors.

10. The method as recited in claim 1 further comprising using an inference engine in a server for the retrieving and determining a location of the transceiver device.

11. The method as recited in claim 1 wherein said signal complies with IEEE 802.11 format, and wherein said air monitors include a wireless network circuit coupled with a computer device.

12. A system comprising:

a plurality of transceiver devices configured to each transmit a wireless signal including an identifier of the source of the signal;

a plurality of air monitors to receive the wireless signal and to store the identifier and a signal strength indication of the wireless signal transmitted by one or more of the plurality of transceiver devices; and

an inference engine to receive the identifier and the corresponding signal strength, to retrieve a predetermined location for each of the air monitors, and to determine a physical location of the transceiver device by correlating the retrieved location with the signal strength indications, the correlating comprising;

storing, by each of the plurality of air monitors, probe signal strength indicators of received probe signals transmitted by each other of the plurality of air monitors; and

generating a profile based on the probe signal strength indicators and the predetermined location for each of the air monitors.

13. The system as recited in claim 12 wherein the air monitors derive from the wireless signal an address of one or more of the transceiver devices, wherein the air monitors store in a data store the address of the transceiver devices along with a corresponding signal strength indication for the transceiver devices;

and wherein the inference engine determines the locations of the transceiver devices after retrieving the address of the transceiver devices.

14. The system as recited in claim 12 wherein the air monitors are located at fixed physical locations, and wherein the physical locations are stored in a data store.

15. A computer readable medium comprising computer-executable instructions that, when executed by one or more processors, perform acts comprising:

storing locations of a plurality of air monitors that each are operable to receive a wireless signal transmitted by a transceiver device and store in records in a data store a signal strength of the signal along with identification data identifying the transceiver device that transmitted the signal;

retrieving from the data store the stored signal strength indications for records with the same identification data; and

determining a location of the transceiver device as a function of the determined locations of the plurality of air monitors and the retrieved signal strength indications, the determining a location of the transceiver device comprising generating a profile based on;

probe signals transmitted and received by each of the plurality of air monitors; and

the locations of the plurality of air monitors.

16. The computer readable medium as recited in claim 15 wherein the wireless signal is received with the plurality of air monitors, and wherein the signal strength indication is stored in the data store by the plurality of air monitors.

17. The computer readable medium as recited in claim 15 further comprising:

deriving from the wireless signal by each of the air monitors an address of the transmitting devices;

storing in the data store with each of the air monitors the addresses of the transceiver devices along with their signal strength indications; and

wherein the determining of a location of the transceiver devices include receiving from each of the air monitors the addresses of the transceiver devices.

18. The computer readable medium as recited in claim 15, wherein at least one air monitor comprises a computer, wherein a user accesses a network with the computer, and determining the location of the at least one air monitor comprises:

monitoring an access history by the user of the computer, the access history comprising a logon to the computer by the user;

identifying in the data store a record containing a pre-assigned location of the user based on the access history;

associating the pre-assigned office location with the at least one air monitor; and

storing physical coordinates for the pre-assigned location in the data store as the location of the at least one air monitor.

19. The computer readable medium as recited in claim 15 wherein determining a location of the transceiver device as a function of the determined locations of the plurality of air monitors and the retrieved signal strength indications further comprises:

obtaining signal strengths for the signal from one of the transceiver devices from some of the plurality of air monitors; and

setting the location of the one of the transceiver devices as a geographic center point of the some of the plurality of air monitors.

20. A method comprising:

receiving a wireless signal transmitted by a transceiver device;

storing a signal strength indication for the received wireless signal;

determining a location of each one of a plurality of air monitors; and

determining a location of the transceiver device by correlating the determined location of one of the plurality of air monitors with a corresponding signal strength indication for the transceiver device comprising;

receiving instructions via a network by each of the plurality of air monitors to broadcast probe packets;

recording probe packets from each broadcasting air monitor by each of the plurality of air monitors;

determining, by each of the plurality of air monitors, a signal strength of packets received from each broadcasting air monitor;

reporting, by each of the plurality of air monitors, the signal strength for each other of the plurality of air monitors;

fitting a set of curves between points associated with distance and signal strength for each of the plurality of air monitors;

selecting a curve from the set of curves with the best fit between the points to create a profile for an enterprise environment of the plurality of air monitors;

setting an initial location of the transceiver device based on the signal strength of the signal from the transceiver device as indicated by some of the plurality of air monitors;

selecting the one of the plurality of air monitors that has the strongest retrieved signal strength indication for the transceiver device; and

adjusting the initial location to minimize an error by setting a distance between the one of the plurality of air monitors and the transceiver device based on an intersection of the corresponding signal strength for the air monitor as received from the transceiver device and the curve, and modifying the initial location using the set distance, wherein the error is the difference between a signal strength indication that the some of the plurality of air monitors received from the transceiver device and an estimate of a signal strength indication that the some of the plurality of air monitors were estimated to have received from the transceiver device as determined from an evaluation of the curve associated with the profile.