ESTIMATION OF SPEED AND DIRECTION OF TRAVEL IN A WLAN POSITIONING SYSTEM USING MULTIPLE POSITION ESTIMATIONS

• US 20090252138A1
• Filed: 06/18/2009
• Published: 10/08/2009
• 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: Pahlavan, Kaveh, Alizadeh-Shabdiz, Farshid, Morgan, Edward J.
• Granted Patent: US 8,103,288 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• 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, each Wi-Fi access point in the target area positioned at a corresponding geographical location, the method comprising:

the Wi-Fi enabled device receiving signals 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 intermediate directions of travel of the Wi-Fi enabled device based on the first position and the later positions of the sequence, each direction calculation using a different later position for each individual calculation; and

calculating a direction of travel of the Wi-Fi enabled device based on the average of the plurality of intermediate 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 a sequence of positions, calculating a plurality of intermediate directions of travel, and calculating the 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. 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 Wi-Fi access point in the target area is positioned at a corresponding geographical location, the system comprising:

the Wi-Fi enabled device for receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device;

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

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

logic located in the Wi-Fi enabled device for calculating a direction of travel of the Wi-Fi enabled device based on the average of the plurality of intermediate directions of travel.

7. The system of claim 6, 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.

8. The system of claim 6, further comprising:

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

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

9. The system of claim 6, wherein the sequence of positions estimated is between about 10 and 15 position estimations.