TIME DIFFERENCE OF ARRIVAL BASED ESTIMATION OF DIRECTION OF TRAVEL IN A WLAN POSITIONING SYSTEM
First Claim
1. A method of estimating a direction of travel of a WLAN-enabled device, the method comprising:
- estimating a speed of travel of the WLAN-enabled device;
estimating a geographic location of the WLAN-enabled device;
the WLAN-enabled device receiving signals transmitted by a WLAN access point in range of the WLAN-enabled device, the signals including a first message and a second message;
accessing a reference database to determine the geographic location of the WLAN access point;
determining an actual time of arrival value of the second message;
determining a time difference of arrival value for the second message based on the actual time of arrival of the second message and an expected time of arrival of the second message, the expected time of arrival of the second message being based on an actual arrival time of the first message;
estimating the direction of travel of the WLAN-enabled device based on the speed of travel of the WLAN-enabled device, the estimated geographic location of the WLAN-enabled device, the time difference of arrival value, and the geographic location of the WLAN access point.
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Accused Products
Abstract
Methods of estimating the bearing of a WLAN-enabled device are provided. A method of estimating a bearing of a WLAN-enabled device includes estimating a speed and geographic location of the device and receiving signals transmitted by an access point, including a first message and a second message. The method further includes accessing a database to determine the geographic location of the access point, determining an actual time of arrival value of the second message, and determining a time difference of arrival value for the second message based on the actual time of arrival of the second message and an expected time of arrival of the second message, which is based on an actual arrival time of the first message. Estimating the bearing of the device is based on the estimated speed and location of the device, the time difference of arrival value, and the location of the access point.
176 Citations
17 Claims
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1. A method of estimating a direction of travel of a WLAN-enabled device, the method comprising:
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estimating a speed of travel of the WLAN-enabled device; estimating a geographic location of the WLAN-enabled device; the WLAN-enabled device receiving signals transmitted by a WLAN access point in range of the WLAN-enabled device, the signals including a first message and a second message; accessing a reference database to determine the geographic location of the WLAN access point; determining an actual time of arrival value of the second message; determining a time difference of arrival value for the second message based on the actual time of arrival of the second message and an expected time of arrival of the second message, the expected time of arrival of the second message being based on an actual arrival time of the first message; estimating the direction of travel of the WLAN-enabled device based on the speed of travel of the WLAN-enabled device, the estimated geographic location of the WLAN-enabled device, the time difference of arrival value, and the geographic location of the WLAN access point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification