Methods and systems for localization
First Claim
1. A system configured to track a client device, the system including:
- a transmitter station configured to transmit a first wireless signal;
at least three receiver stations; and
a location management station, wherein;
each receiver station is configured to receive the first signal and a second wireless signal transmitted from the client device and triggered by receipt of the first signal by the client device;
the receiver stations and/or the location management station are configured to determine a time difference of arrival between the first signal and second signal for each of the receiver stations;
the location management station is configured to, at multiple times;
compute, based on the corresponding time difference of arrival for each receiver station, a plurality of ellipses each associated with a respective receiver station, each ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station;
determine a plurality of intersection points between pairs of said ellipses;
estimate the location of the client device using said determined intersection points; and
the location management station is configured to use the locations estimated at the multiple times to track movement of the client device.
2 Assignments
0 Petitions
Accused Products
Abstract
This invention relates to methods and systems for localization. It is particularly concerned with localization techniques based on time difference of arrival for wireless devices. Embodiments of the invention relate to techniques in which a transmitter transmits periodic distinguishable signals which are relayed upon receipt by the client whose location is sought in a form distinguishable from that of the transmitter. Signals from both the transmitter and the client are received by at least three signal receivers which generate a time difference of arrival based on the difference taken for a signal to reach the receiver directly and via the client. Further embodiments of the invention provide a phase detector in the receivers to determine the time difference of arrival between the signals.
1 Citation
27 Claims
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1. A system configured to track a client device, the system including:
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a transmitter station configured to transmit a first wireless signal; at least three receiver stations; and a location management station, wherein; each receiver station is configured to receive the first signal and a second wireless signal transmitted from the client device and triggered by receipt of the first signal by the client device; the receiver stations and/or the location management station are configured to determine a time difference of arrival between the first signal and second signal for each of the receiver stations; the location management station is configured to, at multiple times; compute, based on the corresponding time difference of arrival for each receiver station, a plurality of ellipses each associated with a respective receiver station, each ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determine a plurality of intersection points between pairs of said ellipses; estimate the location of the client device using said determined intersection points; and the location management station is configured to use the locations estimated at the multiple times to track movement of the client device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of tracking a client device using a wireless network, the method having the steps of:
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transmitting, from a transmitter station, a first signal; receiving, at a client device, the first signal; transmitting, from the client device, a second signal which corresponds to the first signal and whose transmission is triggered by receipt of the first signal; receiving, at each of at least three receiver stations, the first signal and the second signal; determining, for each of the receiver stations, a time difference of arrival between the first signal and second signal; computing, for each of the receiver stations and based on the corresponding time difference of arrival, an ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determining a plurality of intersection points between pairs of said ellipses; estimating the location of the client device using said determined intersection points; repeating the above steps to obtain a plurality of estimated locations of the client device; and using the plurality of estimated locations to track the client device. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A location tracking management station, connected to a wireless network, and having a processor, wherein the processor is configured to:
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receive, from each of at least three receiver stations connected to the wireless network, a time difference of arrival measurement, the time difference of arrival measurement being the time difference between the arrival of a first signal and a second signal at the respective received stations, wherein; the first signal is a signal transmitted from a transmitter station; and the second signal is a signal corresponding to the first signal and transmitted from a client device, the transmission of which is triggered by receipt, at the client device, of the first signal; compute, for each of the receiver stations and based on the corresponding time difference of arrival, an ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determine a plurality of intersection points between pairs of said ellipses; and estimate the location of the client device using said determined intersection points; repeat the above steps to obtain a plurality of estimated locations of the client device; and use the plurality of estimated locations to track the client device.
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Specification