Clock phase ranging methods and systems
First Claim
1. A method of determining a distance between first and second wireless communication devices, comprising the steps of:
- conducting a first estimate of a time of flight of a signal between the first and second wireless communication devices;
conducting subsequent estimates of time of flight of signals between the first and second wireless communication devices, wherein the subsequent estimates are each performed with a clock phase in one of the devices that is offset relative to its phase in a prior estimate;
computing differences between the first time of flight estimate and the subsequent estimates;
computing a refined estimate of the time of flight of a signal between the first and second wireless communication devices based on the differences between the subsequent and prior time-of-flight estimates; and
computing a distance based on the refined time-of-flight estimate.
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Accused Products
Abstract
A system and method for estimating the range between two devices performs two or more ranging estimates with subsequent estimates performed using a clock that is offset in phase with respect to a prior estimate. The subsequent estimate allows estimate uncertainties due to a finite clock resolution to be reduced and can yield a range estimate with a higher degree of confidence. In one embodiment, these additional ranging estimates are performed at n/N (for n=1, . . . N−1, with N>1 and a positive integer) clock-period offset introduced in the device. The clock-period offset can be implemented using a number of approaches, and the effect of clock drift in the devices due to relative clock-frequency offset can also be determined. To eliminate the bias due to clock-frequency offset, a system and method to estimate the clock-frequency offset is also presented.
27 Citations
37 Claims
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1. A method of determining a distance between first and second wireless communication devices, comprising the steps of:
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conducting a first estimate of a time of flight of a signal between the first and second wireless communication devices; conducting subsequent estimates of time of flight of signals between the first and second wireless communication devices, wherein the subsequent estimates are each performed with a clock phase in one of the devices that is offset relative to its phase in a prior estimate; computing differences between the first time of flight estimate and the subsequent estimates; computing a refined estimate of the time of flight of a signal between the first and second wireless communication devices based on the differences between the subsequent and prior time-of-flight estimates; and computing a distance based on the refined time-of-flight estimate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An electronic device configured to determine a distance between a first wireless device and a second wireless device, the electronic device comprising:
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a memory configured to store instructions; and a processor configured to read instructions from the memory, the instructions configured to cause the device to; conduct a first estimate of a time-of-flight of a signal between the first and second wireless communication devices; conduct subsequent estimates of time of flight of signals between the first and second wireless communication devices, wherein the subsequent estimates are each performed with a clock phase in one of the devices that is offset relative to its phase in a prior estimate; compute differences between the first time of flight estimate and the subsequent estimates; and compute a refined estimate of the time of flight of a signal between the first and second wireless communication devices based on the differences between the subsequent and prior time-of-flight estimates; and compute a distance based on the refined time of flight estimate. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification