Wireless positioning approach using time-delay of signals with a known transmission pattern
First Claim
1. A method of determining a location of a mobile device, the method comprising:
- transmitting signals from a plurality of antennas of an access point to the mobile devicei wherein the access point delay shifts the signals transmitted from two of the antennas in the plurality of antennas of the access point;
receiving an acknowledge signal from the mobile device for each signal transmitted to the mobile device;
measuring a round trip delay of each signal as a sum of a time the signal traveled from an antenna of the access point to the mobile device and the time a corresponding acknowledge signal received from the mobile device;
utilizing the delay shift between the signals to determine a difference in time of arrivals of the signals received from each of the two antennas;
determining a distance between the two antennas based on the difference in time of arrivals of the signals; and
determining the location of the mobile device based on (i) the measured round trip delay of the signals and (ii) the distance between said two antennas.
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Abstract
A method of determining the location of a mobile device is provided. The method receives a signal with a known radio transmission pattern at the mobile device from each of several transmitting devices. The method correlates each received signal with a corresponding signal that has a same known radio transmission pattern to determine the time the signal traveled between the corresponding transmitting device and the mobile device. The method determines the location of the mobile device based on the time the signal traveled between the corresponding transmitting device and the mobile device. In some embodiments, determining the location of the mobile device does not require calculating a distance between the mobile device and any of the transmitting devices. In some embodiments determining the location of the mobile device includes solving a function that is dependent on the time the signals traveled between each corresponding transmitting device and the mobile device.
98 Citations
33 Claims
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1. A method of determining a location of a mobile device, the method comprising:
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transmitting signals from a plurality of antennas of an access point to the mobile devicei wherein the access point delay shifts the signals transmitted from two of the antennas in the plurality of antennas of the access point; receiving an acknowledge signal from the mobile device for each signal transmitted to the mobile device; measuring a round trip delay of each signal as a sum of a time the signal traveled from an antenna of the access point to the mobile device and the time a corresponding acknowledge signal received from the mobile device; utilizing the delay shift between the signals to determine a difference in time of arrivals of the signals received from each of the two antennas; determining a distance between the two antennas based on the difference in time of arrivals of the signals; and determining the location of the mobile device based on (i) the measured round trip delay of the signals and (ii) the distance between said two antennas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A non-transitory machine readable medium storing a program for determining a location of a mobile device, the program for execution by at least one processing unit of an access point, the program comprising sets of instructions for:
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transmitting signals from a plurality of antennas of the access point to the mobile device; receiving an acknowledge signal from the mobile device for each signal transmitted to the mobile device; measuring a round trip delay of each signal as a sum of a time the signal traveled from an antenna of the access point to the mobile device and the time a corresponding acknowledge signal received from the mobile device; and determining the location of the mobile device based on the measured round trip delay of the signals, wherein determining the location of the mobile device does not require calculating a distance between the mobile device and the access point. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An access point for determining a location of a mobile device, the access point comprising:
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a plurality of antennas; and a set of radio frequency (RF) components; each access point antenna configured to; transmit signals to the mobile device; receive an acknowledge signal from the mobile device for each signal transmitted to the mobile device; the set of RF components of the access point configured to; measure a round trip delay of each signal as a sum of a time the signal traveled from an antenna of the access point to the mobile device and the time a corresponding acknowledge signal received from the mobile device; delay shift the signals transmitted from two of the antennas in the plurality of antennas of the access point; utilize the delay shift between the signals to determine a difference in time of arrivals of the signals received from each of the two antennas; determine a distance between the two antennas based on the difference in time of arrivals of the signals; and determine the location of the mobile device based on (i) the measured round trip delay of the signals, and (ii) the distance between said two antennas. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification