METHOD AND SYSTEM FOR EMPLOYING A DEDICATED DEVICE FOR POSITION ESTIMATION BY A WLAN POSITIONING SYSTEM

• US 20080008117A1
• Filed: 07/06/2007
• Published: 01/10/2008
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Original Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Inventors: ALIZADEH-SHABDIZ, Farshid
• Granted Patent: US 8,144,673 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: G01S 5/019 Energy consumption
• CPC Class Codes: G01S 5/0242 Determining the position of transmitters to be subsequently used in positioning G01S5/0289 takes precedence
• CPC Class Codes: H04B 7/26 at least one of which is mobile
• CPC Class Codes: H04W 4/02 Services making use of location information
• 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 84/12 WLAN [Wireless Local Area Networks]

Abstract

Methods and systems of employing a dedicated device for position estimation by a WLAN-based positioning system. A device estimates the position of itself in response to gathering wireless signal information from WLAN access points (APs). The device includes a receive-only WLAN radio module for receiving WLAN signals transmitted by WLAN APs in range of said device, extraction logic for extracting information from said received WLAN signals to identify the WLAN APs; and logic to cooperate with a WLAN-based positioning system to estimate the position of the device based at least in part on the extracted information identifying the WLAN APs in the range of said device. In other embodiments, the radio module includes a transmitter but one which is only capable of transmitting probe requests.

Claims

1. A device for estimating the position of itself in response to gathering wireless signal information from WLAN access points (APs), said device comprising:

a receive-only WLAN radio module for receiving WLAN signals transmitted by WLAN APs in range of said device;

extraction logic for extracting information from said received WLAN signals to identify the WLAN APs; and

logic to cooperate with a WLAN-based positioning system to estimate the position of the device based at least in part on the extracted information identifying the WLAN APs in the range of said device.

2. The device of claim 1 wherein the logic to cooperate with a WLAN-based positioning system also estimates the velocity of said device.

3. The device of claim 1 wherein the logic to cooperate with a WLAN-based positioning system also estimates the direction of travel of said device.

4. The device of claim 1 wherein the receive-only WLAN radio module passively receives WLAN signals, said WLAN signals being initiated by said WLAN APs and not responsive to signals transmitted from said device.

5. The device of claim 4 wherein said receive-only WLAN radio module sniffs WLAN packets destined for WLAN devices other than said device.

6. The device of claim 4 wherein said receive-only WLAN radio module sniffs WLAN packets destined for WLAN APs.

7. The device of claim 4 wherein said receive-only WLAN radio module sniffs WLAN packets originated by WLAN APs.

8. The device of claim 4 wherein said receive-only WLAN radio module receives broadcast packets from said WLAN APs.

9. The device of claim 4 wherein said receive-only WLAN radio module includes a beacon detector to detect and analyze beacon signals from said WLAN APs.

10. The device of claim 1 wherein said receive-only WLAN radio module consists only of receiver logic and omits WLAN transmission logic.

11. The device of claim 1 said receive-only WLAN radio module includes transmission logic that is purposefully disabled.

12. The device of claim 1 wherein said extraction logic operates at a physical layer of a network protocol and that receives packets at the base data rate of said protocol.

13. The device of claim 1 wherein said device includes carrier sense logic to detect activity on WLAN channels and, in response to detecting activity, to activate said receive-only WLAN radio module from a low power consumption to an active WLAN signal reception state.

14. The device of claim 13 wherein said carrier sense logic, in response to detecting activity, activates said receive-only WLAN radio module to an active WLAN signal reception state only for the duration of a header of a WLAN packet.

15. The device of claim 1 wherein said receive-only radio module includes logic for measuring at least one received signal strength indicator (RSSI) value for the signals received from the WLAN APs and the logic to cooperate provides said RSSI value to said WLAN-based positioning system.

16. The device of claim 15 wherein said device estimates position at least in part based on the RSSI value.

17. The device of claim 15 wherein said device estimates velocity at least in part based on the RSSI value.

18. The device of claim 15 wherein said device estimates direction of travel at least in part based on the RSSI value.

19. The device of claim 1 wherein the extraction logic includes logic to gather a diversity of WLAN packets and to combine the diversity to extract WLAN information from the combination to provide to the WLAN-based positioning system.

20. The device of claim 1 wherein said device only analyzes header information of received WLAN signals and discards payload information.

21. A device for estimating the position of itself in response to gathering wireless signal information from WLAN access points (APs), said device comprising

a transmitter module capable of only transmitting WLAN probe requests;

a receiver module for receiving information in probe response signals from WLAN APs in range of said device;

extraction logic for extracting identities of the WLAN APs from the information in the probe response signals so that the WLAN APs in range of the device are identified; and

logic to cooperate with a WLAN-based positioning system to estimate the position of the device based at least in part on the extracted information identifying the WLAN APs in the range of said device.

22. The device of claim 21 wherein said WLAN radio module sniffs WLAN packets destined for WLAN devices other than said device.

23. The device of claim 21 wherein said WLAN radio module sniffs WLAN packets destined for WLAN APs.

24. The device of claim 21 wherein said WLAN radio module sniffs WLAN packets originated by WLAN APs.

25. The device of claim 21 wherein said WLAN radio module receives broadcast packets from said WLAN APs.