Ranging signals methods and systems
First Claim
1. A method of determining a distance between first and second wireless communication devices, comprising the steps of:
- the first device sending a first signal to the second device over a wireless communication channel;
the first device receiving a second signal from the second device in response to the second signal;
determining a first number of clock cycles elapsed between sending the first signal and receiving the second signal;
the first device sending a third signal to the second device over a wireless communication channel;
the first device receiving a fourth signal from the second device in response to the third signal;
determining a second number clock cycles elapsed between sending the third signal and receiving the fourth signal; and
determining a refined time-of-flight estimate between the first and second devices as a function of the first and second numbers of clock cycles.
2 Assignments
0 Petitions
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.
43 Citations
40 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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the first device sending a first signal to the second device over a wireless communication channel; the first device receiving a second signal from the second device in response to the second signal; determining a first number of clock cycles elapsed between sending the first signal and receiving the second signal; the first device sending a third signal to the second device over a wireless communication channel; the first device receiving a fourth signal from the second device in response to the third signal; determining a second number clock cycles elapsed between sending the third signal and receiving the fourth signal; and determining a refined time-of-flight estimate between the first and second devices as a function of the first and second numbers of clock cycles. - 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; the first device sending a first signal to the second device over a wireless communication channel; the first device receiving a second signal from the second device in response to the second signal; determining a first number of clock cycles elapsed between sending the first signal and receiving the second signal; the first device sending a third signal to the second device over a wireless communication channel; the first device receiving a fourth signal from the second device in response to the third signal; determining a second number clock cycles elapsed between sending the third signal and receiving the fourth signal; and determining a refined time-of-flight estimate between the first and second devices as a function of the first and second numbers of clock cycles. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification