Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations

• US 8,103,288 B2
• Filed: 06/18/2009
• Issued: 01/24/2012
• Est. Priority Date: 05/08/2006
• Status: Active Grant

• Current Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Original Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Inventors: Alizadeh-Shabdiz, Farshid, Pahlavan, Kaveh, Morgan, Edward James
• Primary Examiner(s): DOAN, KIET M
• Application Number:
  US12/486,907
• Publication Number:
  US 20090252138A1
• Time in Patent Office: 950 Days
• Field of Search: 455/456.5, 455/456.1, 455/67.11, 455/456.6, 455/416, 455/502, 455/456.2, 455/410, 342/387, 342/357.2, 342/457, 370/328, 705/301
• US Class Current: 455/456.1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

A method for estimating the speed and bearing of a Wi-Fi enabled device using WLAN radio signals in a WLAN based location service is provided. A method used to estimate a speed of travel of a Wi-Fi enabled device comprises the Wi-Fi enabled device receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device, and using the signals to estimate the speed of and/or direction of travel of the Wi-Fi enabled device.

Claims

1. A method used for facilitating the determination of a direction of travel of a Wi-Fi enabled device within a location-based services system having a reference database of Wi-Fi access points in a target area, the reference database having estimated geographic locations for at least a subset of Wi-Fi access points in the target area, the method comprising:

identifying Wi-Fi access points based on signals received by the Wi-Fi enabled device transmitted by Wi-Fi access points in range of the Wi-Fi enabled device;

accessing the reference database to retrieve the corresponding geographical locations of the identified Wi-Fi access points;

using the geographical locations of the identified Wi-Fi access points to estimate a sequence of positions of the Wi-Fi enabled device occurring during a window of time, the sequence having a first position;

calculating a plurality of directions of travel of the Wi-Fi enabled device based on the first position and at least two of the later positions of the sequence, each direction calculation using a different later position for each individual calculation; and

calculating an estimated direction of travel of the Wi-Fi enabled device based on the plurality of directions of travel.

2. The method of claim 1, wherein the Wi-Fi enabled device communicates with at least one of the Wi-Fi access points to cause the Wi-Fi access point to transmit signals.

3. The method of claim 1, further comprising:

accessing the reference database to retrieve reliability measurements corresponding to the identified Wi-Fi access points; and

using reliability measurements of the Wi-Fi access points when estimating the positions of the Wi-Fi enabled device.

4. The method of claim 1, wherein at least one of the accessing the reference database, estimating the sequence of positions, calculating the plurality of directions of travel, and calculating the estimated direction of travel of the Wi-Fi enabled device is performed by the Wi-Fi enabled device.

5. The method of claim 1, wherein the sequence of positions estimated is between about 10 and 15 position estimations.

6. The method of claim 1, wherein the calculating the estimated direction of travel of the Wi-Fi enabled device is based on an average of the plurality of directions of travel.

7. A location-based services system used for facilitating the determination of a direction of travel of a Wi-Fi enabled device, the system having a reference database of Wi-Fi access points in a target area, wherein each of a subset of Wi-Fi access points in the target area is associated with a corresponding estimated geographical location, the system comprising:

logic for identifying Wi-Fi access points based on signals received by the Wi-Fi enabled device transmitted by Wi-Fi access points in range of the Wi-Fi enabled device;

logic for accessing the reference database to retrieve the corresponding geographical locations of the identified Wi-Fi access points;

logic for using the geographical locations of the identified Wi-Fi access points to estimate a sequence of positions of the Wi-Fi enabled device occurring during a window of time, the sequence having a first position;

logic for calculating a plurality of directions of travel of the Wi-Fi enabled device based on the first position and at least two of the later positions of the sequence, each direction calculation using a different later position for each individual calculation; and

logic for calculating an estimated direction of travel of the Wi-Fi enabled device based on the plurality of directions of travel.

8. The system of claim 7, wherein the Wi-Fi enabled device communicates with at least one of the Wi-Fi access points to cause the Wi-Fi access point to transmit signals.

9. The system of claim 7, further comprising:

logic for accessing the reference database to retrieve reliability measurements corresponding to the identified Wi-Fi access points; and

logic for using reliability measurements of the Wi-Fi access points when estimating the positions of the Wi-Fi enabled device.

10. The system of claim 7, wherein the sequence of positions estimated is between about 10 and 15 position estimations.

11. The system of claim 7, wherein at least one of the logic for identifying WiFi-access points, logic for accessing the reference database, logic for using the geographical locations, logic for calculating the plurality of directions, and logic for calculating the estimated direction of travel are located in the Wi-Fi enabled device.

12. The system of claim 7, the logic for calculating the estimated direction of travel of the Wi-Fi enabled device including logic for determining an average of the plurality of directions of travel.