Positioning systems for wireless networks
First Claim
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1. A method of computing positioning of a wi-fi device in a wi-fi network, the method comprising:
- exchanging wi-fi packets among plural pairs of wi-fi nodes by transmission of the wi-fi packets through RF radios in the wi-fi nodes, including assigning local clock values, from local clocks in the wi-fi nodes, to packets upon sending and receiving the packets from each of the wi-fi nodes in the pair, and communicating the local clock values in wi-fi packets exchanged between the pairs of wi-fi nodes;
capturing at least a receipt count stamp from a local clock of a wi-fi node in wi-fi packet communication between a mobile device and wi-fi nodes in the plural pairs;
determining from the local clock values and the receipt count stamps, differential ranges between the mobile device and each of plural pairs of wi-fi nodes;
estimating a path delay for a packet communication with a wi-fi node from the differential ranges and known distances between wi-fi nodes, the path delay comprising a delay in time of flight due to multipath;
determining range estimates between the mobile device and wi-fi nodes from the differential ranges and the path delay;
determining location of the mobile device by finding a candidate location that minimizes differences between the range estimates and the candidate location; and
determining pseudo ranges from the differential ranges, and searching for a candidate location where the pseudo-ranges have minimum error;
wherein the path delay is estimated for the wi-fi nodes and removed from the differential ranges; and
wherein the path delay is estimated by evaluating differential range estimates of wi-fi nodes to the mobile device computed from packets transmitted between mobile device and the pairs of wi-fi nodes, and assigning path delay to the pairs of wi-fi nodes.
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Abstract
The invention provides a method of computing positioning of a mobile device in a wireless network. This positioning method exchanges packets between pairs of wi-fi nodes. The packets include count stamps of packet transmit and receipt. Differential ranges between a mobile device and plural pairs of wi-fi nodes are used to locate the mobile device.
90 Citations
20 Claims
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1. A method of computing positioning of a wi-fi device in a wi-fi network, the method comprising:
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exchanging wi-fi packets among plural pairs of wi-fi nodes by transmission of the wi-fi packets through RF radios in the wi-fi nodes, including assigning local clock values, from local clocks in the wi-fi nodes, to packets upon sending and receiving the packets from each of the wi-fi nodes in the pair, and communicating the local clock values in wi-fi packets exchanged between the pairs of wi-fi nodes; capturing at least a receipt count stamp from a local clock of a wi-fi node in wi-fi packet communication between a mobile device and wi-fi nodes in the plural pairs; determining from the local clock values and the receipt count stamps, differential ranges between the mobile device and each of plural pairs of wi-fi nodes; estimating a path delay for a packet communication with a wi-fi node from the differential ranges and known distances between wi-fi nodes, the path delay comprising a delay in time of flight due to multipath; determining range estimates between the mobile device and wi-fi nodes from the differential ranges and the path delay; determining location of the mobile device by finding a candidate location that minimizes differences between the range estimates and the candidate location; and determining pseudo ranges from the differential ranges, and searching for a candidate location where the pseudo-ranges have minimum error; wherein the path delay is estimated for the wi-fi nodes and removed from the differential ranges; and wherein the path delay is estimated by evaluating differential range estimates of wi-fi nodes to the mobile device computed from packets transmitted between mobile device and the pairs of wi-fi nodes, and assigning path delay to the pairs of wi-fi nodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A non-transitory computer readable medium, on which is stored instructions, which when executed by one or more computers, perform a method of computing positioning of a wi-fi device in a wi-fi network, the method comprising:
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exchanging wi-fi packets among plural pairs of wi-fi nodes by transmission of the wi-fi packets through RF radios in the wi-fi nodes, including assigning local clock values, from local clocks in the wi-fi nodes, to packets upon sending and receiving the packets from each of the wi-fi nodes in the pair, and communicating the local clock values in wi-fi packets exchanged between the pairs of wi-fi nodes; capturing at least a receipt count stamp from a local clock of a wi-fi node in wi-fi packet communication between a mobile device and wi-fi nodes in the plural pairs; determining from the local clock values and the receipt count stamps, differential ranges between a mobile device and each of plural pairs of wi-fi nodes; estimating a path delay for a packet communication with a wi-fi node from the differential ranges and known distances between wi-fi nodes, the path delay comprising a delay in time of flight due to multipath; determining range estimates between the mobile device and wi-fi nodes from the differential ranges and the path delay; and determining location of the mobile device by finding a candidate location that minimizes differences between the range estimates and the candidate location; the method including;
determining pseudo ranges from the differential ranges, and searching for a candidate location where the pseudo-ranges have minimum error;wherein the plural pairs of wi-fi nodes comprise infrastructure nodes and at least some of the exchanging of wi-fi packets among the infrastructure nodes is performed with regularity in a pair-wise manner according to a full duplex mode; wherein full duplex exchanges between the plural pairs of wi-fi nodes are used to determine path delays by determining a round trip time of a full duplex exchange between first and second wi-fi nodes in a first pair and deriving a path delay associated with the first pair from the round trip time and distance between the first and second wi-fi nodes; and wherein the path delay is used to compensate for multipath error in computing the pseudo ranges. - View Dependent Claims (11, 12, 13, 14)
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15. A method of computing positioning of a wi-fi device in a wi-fi network, the method comprising:
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exchanging wi-fi packets among plural pairs of wi-fi nodes by transmission of the wi-fi packets through RF radios in the wi-fi nodes, including assigning local clock values, from local clocks in the wi-fi nodes, to packets upon sending and receiving the packets from each of the wi-fi nodes in the pair, and communicating the local clock values in wi-fi packets exchanged between the pairs of wi-fi nodes; capturing at least a receipt count stamp from a local clock of a wi-fi node in wi-fi packet communication between a mobile device and wi-fi nodes in the plural pairs; determining from the local clock values and the receipt count stamps, differential ranges between the mobile device and each of plural pairs of wi-fi nodes; estimating a path delay for a packet communication with a wi-fi node from the differential ranges and known distances between wi-fi nodes, the path delay comprising a delay in time of flight due to multipath; determining range estimates between the mobile device and wi-fi nodes from the differential ranges and the path delay; and determining location of the mobile device by finding a candidate location that minimizes differences between the range estimates and the candidate location; the method including;
determining pseudo ranges from the differential ranges, and searching for a candidate location where the pseudo-ranges have minimum error;wherein the plural pairs of wi-fi nodes comprise infrastructure nodes and at least some of the exchanging of wi-fi packets among the infrastructure nodes is performed with regularity in a pair-wise manner according to a full duplex mode; wherein full duplex exchanges between the plural pairs of wi-fi nodes are used to determine path delays by determining a round trip time of a full duplex exchange between first and second wi-fi nodes in a first pair and deriving a path delay associated with the first pair from the round trip time and distance between the first and second wi-fi nodes; and wherein the path delay is used to compensate for multipath error in computing the pseudo ranges. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification