Location and tracking system
First Claim
1. A mobile radio-frequency communication system, comprising:
- a network of at least two fixed base stations arranged to transmit the same signals to at least one mobile radio-frequency transceiver, and receive signals from the one or more mobile radio-frequency transceivers;
a reference receiver located at a fixed location a known distance from each of the base stations and including measuring means to measure the times of arrival of signals transmitted from the base stations;
determination means to use the known distances and measured times to determine the relative time offsets of transmissions from each base station; and
location means to use the determined relative time offsets to calculate the position of a mobile transceiver in the network area using hyperbolic positioning techniques involving comparison of the times of arrival of signals from the base stations at the mobile transceiver.
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Abstract
A method is disclosed for finding the position of a mobile radio-frequency transceiver in a communication system. A network of at least two unsynchronized base stations is arranged to transmit and receive signals to and from at least one mobile radio frequency transceiver. A reference receiver located at a known distance from the base stations measures the times of arrival of signals transmitted from the base stations. Using the known distances and measured times, a determination is made of the relative time offsets of transmission from each base station. The determined relative time offsets are used to calculate the position of the mobile transceiver in the network area using hyperbolic positioning techniques. A number of other enhancements including the use of Doppler, carrier information, and direction of arrival to improve the performance of mobile telephone-based positioning systems are also described.
121 Citations
23 Claims
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1. A mobile radio-frequency communication system, comprising:
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a network of at least two fixed base stations arranged to transmit the same signals to at least one mobile radio-frequency transceiver, and receive signals from the one or more mobile radio-frequency transceivers;
a reference receiver located at a fixed location a known distance from each of the base stations and including measuring means to measure the times of arrival of signals transmitted from the base stations;
determination means to use the known distances and measured times to determine the relative time offsets of transmissions from each base station; and
location means to use the determined relative time offsets to calculate the position of a mobile transceiver in the network area using hyperbolic positioning techniques involving comparison of the times of arrival of signals from the base stations at the mobile transceiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of finding the position of a mobile radio-frequency transceiver in a communication system comprising a network of at least two fixed base stations arranged to transmit the same signals, comprising the steps of:
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locating a reference receiver at known distances from the base stations;
measuring the times of arrival at the reference receiver of signals transmitted from the base stations;
determining the relative time offsets of transmissions from each base station, using the known distances and measured times; and
calculating the position of a mobile transceiver in the network area using the determined relative time offsets and hyperbolic positioning techniques. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
transmitting signals from the base stations at several different frequencies; and
calculating the phase difference between the different signals having different frequencies that have been transmitted from the same base station in order to calculate its position.
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18. A method according to claim 15, comprising the additional step of:
calculating the impulse response to the channel between a base station and a mobile transceiver and using this information in the mobile transceiver to reduce multi-path effects.
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19. A method according to claim 15, comprising the additional step of:
synthesising a wide aperture while the mobile transceiver is moving to provide additional information for position calculation.
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20. A method according to claim 15, comprising the additional step of:
synthesising a wide aperture while the mobile transceiver is moving to provide additional information to reduce multi-path effects.
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21. A method according to claim 15, comprising the additional step of:
using a directional antenna, either at base station or on a mobile transceiver, for position ambiguity resolution, position determination or to reduce multi-path effects.
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22. A method according to claim 15, comprising the additional step of:
using Doppler estimates of the velocity of mobile transceivers to calculate the position or location of the mobile transceiver.
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23. A method according to claim 15, comprising the additional step of:
using information at least one of map data, dead reckoning and communications broadcasts to improve mobile transceiver position estimates.
Specification