Distance estimation
First Claim
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1. A method, comprising:
- receiving, at a receiving node, a packet from a transmitting node, wherein the packet is an acknowledgement packet for a data packet;
obtaining channel state information from the packet;
obtaining a received signal strength indicator from the packet;
determining a direct path energy estimate from the channel state information;
determining a path loss exponent from the direct path energy estimate and the received signal strength indicator; and
determining a first distance estimate between the receiving node and the transmitting node from the path loss exponent and the direct path energy estimate;
obtaining an estimated time of departure of the data packet;
obtaining an estimated time of arrival of the packet;
determining a second distance estimate between the receiving node and the transmitting node using the estimated time of departure and the estimated time of arrival;
comparing the second distance estimate to an expected distance determined from the first distance estimate to determine if the second distance estimate is an outlier; and
if the second distance estimate is not an outlier, combining the second distance estimate with a previously determined distance estimate to determine a refined distance estimate.
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Abstract
A distance estimate between two nodes may be determined from a path loss exponent and a direct path energy estimate. The direct path energy estimate may be determined from channel state information of a packet received from one of the nodes. The path loss exponent may be determined from the direct path energy estimate and a received signal strength indicator.
19 Citations
14 Claims
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1. A method, comprising:
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receiving, at a receiving node, a packet from a transmitting node, wherein the packet is an acknowledgement packet for a data packet; obtaining channel state information from the packet; obtaining a received signal strength indicator from the packet; determining a direct path energy estimate from the channel state information; determining a path loss exponent from the direct path energy estimate and the received signal strength indicator; and determining a first distance estimate between the receiving node and the transmitting node from the path loss exponent and the direct path energy estimate; obtaining an estimated time of departure of the data packet; obtaining an estimated time of arrival of the packet; determining a second distance estimate between the receiving node and the transmitting node using the estimated time of departure and the estimated time of arrival; comparing the second distance estimate to an expected distance determined from the first distance estimate to determine if the second distance estimate is an outlier; and if the second distance estimate is not an outlier, combining the second distance estimate with a previously determined distance estimate to determine a refined distance estimate. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system, comprising:
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a transceiver to transmit a plurality of data packets and to receive a corresponding plurality of acknowledgement packets from a network device; an expected time of flight calculator, implemented as computer executable instructions stored on a non-transitory medium and executed by a processor, to; use a plurality of channel state information sets corresponding to the plurality of acknowledgement packets to determine a plurality of direct path energy estimates and a plurality of path loss exponents, and determine an expected time of flight using the plurality of direct path energy estimates and the plurality of path loss exponents; a time of flight estimator, implemented as computer executable instructions stored on the non-transitory medium and executed by the processor, to determine a plurality of estimated times of flight to the network device using the plurality of channel state information sets; a validator, implemented as computer executable instructions stored on the non-transitory medium and executed by the processor, to compare each time of flight of the plurality of estimated times of flight to the expected time of flight and to discard invalid estimated times of flight to provide a validated plurality of estimated times of Flight; and a length estimator, implemented as computer executable instructions stored on the non-transitory medium and executed by the processor, to use the validated plurality of estimated times of flight to provide a length estimate. - View Dependent Claims (8, 9)
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10. A non-transitory computer readable medium storing instructions executable by a processor to:
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transmit a data packet to a network node; obtain an estimated time of departure of the data packet; receive an acknowledgement packet from the network node; obtain a preliminary estimated time of arrival of the acknowledgement packet; determine a power delay profile from channel state information of the acknowledgement packet; determine an adjusted estimated time of arrival by using the power delay profile to adjust the preliminary estimated time of arrival; and use the estimated time of departure and the adjusted estimated time of arrival to determine an estimated time of flight to the network node. - View Dependent Claims (11, 12, 13, 14)
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Specification