Methods and apparatus for identifying asset location in communication networks
First Claim
1. A method for identifying a location of an asset in a communication network, said network having at least a first receiver device and a second receiver device, each receiver device having a known position, said method comprising:
- estimating a first time-of-arrival of an 802.11 communication sequence transmitted by said asset, said first time-of-arrival corresponding to arrival of said sequence at said first receiver device;
estimating a second time-of-arrival of said sequence, said second time-of-arrival corresponding to arrival of said sequence at said second receiver device; and
calculating a first time-difference-of-arrivals using said first and second times-of-arrival.
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Accused Products
Abstract
The location of unmodified wireless assets in a wireless communication network may be identified using time differences of arrivals of a communication sequence at different network receivers. Time-stamping devices may include correlator circuits in parallel with signal decoders to time-stamp communication sequences. Cellular wireless networks may be frequency-multiplexed to increase spatial time-stamping density. Tags may be attached to passive assets to provide location identification information to network devices. Locations of assets broadcasting standard 802.11 radio frequency structures may be identified. Noise inherent in correlating a communication sequence may be reduced by using a selected correlation function.
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Citations
27 Claims
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1. A method for identifying a location of an asset in a communication network, said network having at least a first receiver device and a second receiver device, each receiver device having a known position, said method comprising:
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estimating a first time-of-arrival of an 802.11 communication sequence transmitted by said asset, said first time-of-arrival corresponding to arrival of said sequence at said first receiver device;
estimating a second time-of-arrival of said sequence, said second time-of-arrival corresponding to arrival of said sequence at said second receiver device; and
calculating a first time-difference-of-arrivals using said first and second times-of-arrival. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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- 8. The method of claim 8 wherein said identifying comprises estimating an intersection of said first plurality and said second plurality.
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15. A method for identifying a location of an asset in a communication network, said network having a first receiver device at a first station and a second receiver device at a second station, each receiver device having a known position, said method comprising:
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estimating more than one first time-of-arrival estimator value, said first time-of-arrival estimator value corresponding to arrival at said first station of an 802.11 communication signal from said asset;
estimating more than one second time-of-arrival estimator value, said second time-of-arrival estimator value corresponding to arrival of said communication signal at said second station;
calculating a time-difference-of arrivals using said first and second time-of-arrival estimators. - View Dependent Claims (16, 17, 18, 19)
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20. A method for identifying a location of an asset in a communication network, said network having at least three receivers, said method comprising:
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estimating a time-of-arrival of an 802.11 communication sequence at said receivers;
collecting at least one time-of-arrival estimate for each of said receivers, said estimate corresponding to a time-of-arrival of said communication sequence at a respective one of said receivers;
calculating a difference for each of at least two pairs of said estimates; and
estimating said location using said differences. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification