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 instant;
receiving relative time information from a second communication system;
obtaining internal timing information from a local clock;
estimating absolute time at a second time instant based on the absolute time for the first time instant, the relative time information from the second communication system, and the internal timing information; and
determining the position of the receiver unit based at least in part on the absolute time estimate for the second time instant.
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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.
41 Citations
21 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 instant; receiving relative time information from a second communication system; obtaining internal timing information from a local clock; estimating absolute time at a second time instant based on the absolute time for the first time instant, the relative time information from the second communication system, and the internal timing information; and determining the position of the receiver unit based at least in part on the absolute time estimate for the second time instant. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A mobile device comprising:
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a receiving system configured to receive signals from a first communication system and a second communication system; processor circuitry configured to; process signals from the first communication system to obtain absolute time at a first time instant; process signals from the second communication system to obtain relative time information; obtain internal timing information from a clock included in the mobile device; estimate absolute time at a second time instant based on the absolute time for the first time instant, the relative time information from the second communication system, and the internal timing information, and determine the position of the receiver unit based at least in part on the absolute time estimate for the second time instant. - View Dependent Claims (9, 10)
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11. A wireless device comprising:
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means for obtaining absolute time from a first communication system for a first time instant; 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 instant based on the absolute time for the first time instant, the relative time information from the second communication system, and the internal timing information; and means for determining the position of the receiver unit based at least in part on the absolute time estimate for the second time instant. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. An article comprising machine readable media having instructions stored thereupon as executable software that, when executed, cause one or more machines to perform operations comprising:
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accessing information indicative of absolute time received from a first communication system for a first time instant; accessing relative time information from a second communication system; accessing internal timing information from a local clock; generating an estimate of absolute time at a second time instant based on the absolute time for the first time instant, the relative time information from the second communication system, and the internal timing information; and generating information indicative of the position of the receiver unit based at least in part on the generated estimate of absolute time for the second time instant. - View Dependent Claims (19, 20, 21)
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Specification