Methods and apparatus for identifying asset location in communication networks
First Claim
1. An apparatus for identifying a location of a wireless asset comprising:
- a synchronization signal generator; and
at least one network resource in electrical communication with said generator, said resource configured to time-stamp an 802.11 communication sequence.
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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
118 Claims
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1. An apparatus for identifying a location of a wireless asset comprising:
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a synchronization signal generator; and
at least one network resource in electrical communication with said generator, said resource configured to time-stamp an 802.11 communication sequence. - View Dependent Claims (2, 3, 4)
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5. A system for providing a time-of-arrival estimate of a communication sequence at a location, said system comprising:
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a device for receiving radio frequency signals; and
a first circuit in electronic communication with said device;
wherein said first circuit comprises at least one correlator selected from the group;
a. a two-symbol correlator;
b. a three-symbol correlator;
c. a four-symbol correlator;
d. a five-symbol correlator;
e. an N-symbol correlator, wherein N is an integer greater than five; and
f. a combination of at least two of a-e. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 20, 21, 22, 23, 25, 26, 27, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61)
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15. A signal processing circuit for processing radio signals comprising:
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a carrier tracking circuit having a tracking circuit output;
a chipping code correlator circuit having a correlator circuit output;
a time-stamping circuit; and
a receiver interface;
wherein;
said correlator circuit is in serial electronic communication with said tracking circuit and said receiver interface; and
said time-stamping circuit is connected to said tracking circuit output, said correlator circuit output, and said receiver interface.
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19. A method for identifying a location of an asset in a communication network, said network having at least one first receiver pair and at least one second receiver pair, said first receiver pair configured to receive signals at a first frequency, said second receiver pair configured to receive signals at a second frequency, said method comprising:
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receiving a first communication sequence from said asset using said first receiver pair;
receiving a second communication sequence from said asset using said second receiver pair; and
identifying said location using a first time-difference-of-arrivals and a second time-difference-of-arrivals, said first time-difference-of-arrivals corresponding to said first receiver pair, said second time-difference-of-arrivals corresponding to said second receiver pair.
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24. A method for providing location estimation information to a communication network, said information corresponding to an asset, said asset having a location, said network having at least one first receiver pair and at least one second receiver pair, said first receiver pair configured to receive signals at a first frequency, said second receiver pair configured to receive signals at a second frequency, said method comprising:
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transmitting a first communication sequence configured for estimation of said location at said first frequency; and
transmitting a second communication sequence configured for estimation of said location at said second frequency.
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28. A method for selectively identifying a location of a mobile asset in a communication network, said method comprising:
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receiving a communication sequence from said asset, said communication sequence having an asset identifier, said asset identifier identifying said asset; and
optionally estimating said location when said asset identifier corresponds to a selected identifier.
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35. A method for providing a time-of-arrival estimate of a data signal at a receiver, said method comprising:
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receiving said data signal;
demodulating said signal;
decoding said signal to form a decoded signal;
optionally selecting a correlation function for said decoded signal if said data signal is not encoded for time stamping; and
estimating said time-of-arrival using said correlation function.
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62. 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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optionally selecting a correlation function for said decoded signal if said data signal is not encoded for time-stamping;
estimating a first time-of-arrival using said correlation function, said first time-of-arrival corresponding to arrival at said first receiver device of a communication sequence transmitted by said asset;
estimating a second time-of-arrival using said correlation function, said second time-of-arrival corresponding to arrival at said second receiver device of said communication sequence; and
calculating a first time-difference-of-arrivals using said first and second times-of-arrival. - View Dependent Claims (63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80, 81, 82, 83)
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79. A method for identifying a location of an asset in a communication network, said network having a first receiver device and a second receiver device, each receiver device having a known position, said method comprising:
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estimating more than one first time-of-arrival estimator value using a correlation function, said first time-of-arrival estimator value corresponding to arrival at said first station of a communication signal from said asset;
estimating more than one second time-of-arrival estimator value using said correlation function, 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.
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84. 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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decoding a data signal from said asset to form a decoded signal;
determining if said decoded signal is encoded for time-stamping;
selecting a correlation function for estimating a time-of-arrival of a 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 (85, 86, 87, 88, 89, 90, 91)
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92. 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 (93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105)
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106. A method for identifying a location of an asset in a communication network, said network having a first receiver device and a second receiver device, 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 (107, 108, 109, 110)
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111. 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 (112, 113, 114, 115, 116, 117, 118)
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Specification