Passive positioning utilizing round trip time information
First Claim
Patent Images
1. A method for exchanging positioning messages between access points, including:
- detecting, with a transceiver, an incoming message from an access point;
determining a Round Trip Time (RTT) value associated with the access point;
generating an acknowledgment message;
calculating a time of departure for the acknowledgment message based, at least in part, on the RTT value; and
sending, with the transceiver, the acknowledgment message at the time of departure.
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Abstract
Techniques for passive positioning of a client station are disclosed. In an example a passive positioning scheme may include detecting an incoming message from an access point, determining a Round Trip Time (RTT) value associated with the access point, generating an acknowledgment message, calculating a time of departure for the acknowledgment message based on the RTT value, and sending the acknowledgment message at the time of departure.
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Citations
26 Claims
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1. A method for exchanging positioning messages between access points, including:
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detecting, with a transceiver, an incoming message from an access point; determining a Round Trip Time (RTT) value associated with the access point; generating an acknowledgment message; calculating a time of departure for the acknowledgment message based, at least in part, on the RTT value; and sending, with the transceiver, the acknowledgment message at the time of departure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of positioning on a client station utilizing inter-access point messaging, comprising:
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detecting, at a client station, a broadcast message from a first access point indicating a message exchange with a second access point; detecting a first message, wherein the first message is sent from the first access point to the second access point; detecting a second message, wherein the second message is sent from the second access point to the first access point; determining location information associated with the first access point and the second access point; determining a Short Inter-Frame Space (SIFS) value; determining a message length value for the first message; determining time difference of arrival (TDOA) information based, at least in part, on the detecting of the first message and the second message; and calculating a position estimate based on the location information associated with the first access point and the second access point, the TDOA information, the SIFS value, and the message length value. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A system to exchange messages for use in passive positioning of a mobile unit, comprising:
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a memory unit; a transceiver; at least one processor coupled to the memory unit and the transceiver, and configured to; detect, with the transceiver, an incoming message from an access point; determine a Round Trip Time (RTT) value associated with the access point; generate an acknowledgment message; calculate a time of departure for the acknowledgment message based on the RTT value; and send, with the transceiver, the acknowledgment message at the time of departure. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A client station comprising:
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a processor; a positioning unit coupled to the processor and configured to; detect a broadcast message from a first access point indicating a message exchange with a second access point; detect a first message, wherein the first message is sent from the first access point to the second access point; detect a second message, wherein the second message is sent from the second access point to the first access point; determine location information associated with the first access point and the second access point; determine a Short Inter-Frame Space (SIFS) value; determine a message length value for the first message; determine time difference of arrival (TDOA) information based, at least in part, the detecting of the first message and the second message; and calculate a position estimate based on the location information associated with the first access point and the second access point, the TDOA information, the SIFS value, and the message length value. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification