VIRTUAL REAL-TIME CLOCK BASED ON TIME INFORMATION FROM MULTIPLE COMMUNICATION SYSTEMS
First Claim
1. A method for determining a position of a receiver unit in a wireless communication system, comprising:
- obtaining absolute time from a first communication system for a first time;
receiving relative time information from a second communication system;
obtaining internal timing information from a local clock;
estimating absolute time at a second time based on the absolute time for the first time, the relative time information from the second communication system, and the internal timing information; and
determining a first pseudorange between a first transmitter and the receiver unit based at least in part on the absolute time estimate for the second time.
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Accused Products
Abstract
Method and apparatus to implement a “virtual” real-time clock at a terminal based on time information from multiple communication systems. At least one system (e.g., GPS) provides “absolute” time information for the virtual real-time clock, and at least one other system (e.g., a cellular system) provides “relative” time information. The virtual real-time clock is “time-stamped” with absolute time as it becomes available from the first system. Relative time (which may be received from multiple asynchronous transmitters) is mapped to the timeline of the virtual real-time clock as it is received from the second system. Absolute time at any arbitrary time instant on the timeline may then be estimated based on the absolute time from the first system and the relative time from the second system. Absolute times from the first system for two or more time instants may also be used to calibrate the relative time from the second system.
30 Citations
27 Claims
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1. A method for determining a position of a receiver unit in a wireless communication system, comprising:
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obtaining absolute time from a first communication system for a first time; receiving relative time information from a second communication system; obtaining internal timing information from a local clock; estimating absolute time at a second time based on the absolute time for the first time, the relative time information from the second communication system, and the internal timing information; and determining a first pseudorange between a first transmitter and the receiver unit based at least in part on the absolute time estimate for the second time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A mobile device comprising:
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a satellite positioning system receiver to receive signals from one or more satellite positioning systems; a terrestrial receiver to receive signals from at least one terrestrial communication system; a local clock; a processing unit configured to; access absolute time information for a first time obtained from received signals from the satellite positioning system; access relative time information obtained from received signals from the at least one terrestrial communication system; access internal timing information from the local clock; generate an estimate of absolute time at a second time based on the absolute time information for the first time, the relative time information, and the internal timing information; and determine a first pseudorange between a first transmitter and the mobile device based at least in part on the absolute time estimate for the second time. - View Dependent Claims (11, 12, 13, 14)
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15. A mobile device comprising:
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means for obtaining absolute time from a first communication system for a first time; means for receiving relative time information from a second communication system; means for obtaining internal timing information from a local clock; means for estimating absolute time at a second time based on the absolute time for the first time, the relative time information from the second communication system, and the internal timing information; and means for determining a first pseudorange between a first transmitter and the receiver unit based at least in part on the absolute time estimate for the second time. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. An article comprising computer-readable instructions stored on a computer-readable medium that, when executed, cause one or more machines to perform operations comprising:
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obtaining absolute time from a first communication system for a first time; receiving relative time information from a second communication system; obtaining internal timing information from a local clock; estimating absolute time at a second time based on the absolute time for the first time, the relative time information from the second communication system, and the internal timing information; and determining a first pseudorange between a first transmitter and the receiver unit based at least in part on the absolute time estimate for the second time. - View Dependent Claims (24, 25, 26, 27)
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Specification