System and method for wireless communications
First Claim
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1. A method of estimating position of a moving RFID tag, comprising:
- transmitting at least one interrogator signal;
receiving, at an interrogator antenna, a reflected signal from the RFID tag;
determining phase changes of the reflected signal with respect to a phase of the at least one interrogator signal;
mathematically weighting the phase changes based on instant power corresponding to the phase changes;
producing a phase trajectory for the reflected signal based on the weighted phase changes, wherein the phase trajectory represents the phase changes with respect to a distance from the interrogator antenna; and
generating an estimated phase trajectory based on averaged values of the phase trajectory; and
determining a position of the RFID tag relative to the interrogator antenna based on a peak of the estimated phase trajectory for the reflected signal.
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Abstract
A method and system for estimating position of a moving RFID tag is provided. The method includes transmitting at least one interrogator signal; receiving, at an interrogator antenna, a reflected signal from the RFID tag; determining phase changes of the reflected signal with respect to the phase of the at least one interrogator signal; weighting the phase changes based on instant power corresponding to the phase changes; producing a phase trajectory for the reflected signal based on the weighted phase changes; and estimating position of the RFID tag relative to the interrogator antenna based on the peak of the phase trajectory for the reflected signal.
79 Citations
14 Claims
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1. A method of estimating position of a moving RFID tag, comprising:
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transmitting at least one interrogator signal; receiving, at an interrogator antenna, a reflected signal from the RFID tag; determining phase changes of the reflected signal with respect to a phase of the at least one interrogator signal; mathematically weighting the phase changes based on instant power corresponding to the phase changes; producing a phase trajectory for the reflected signal based on the weighted phase changes, wherein the phase trajectory represents the phase changes with respect to a distance from the interrogator antenna; and generating an estimated phase trajectory based on averaged values of the phase trajectory; and determining a position of the RFID tag relative to the interrogator antenna based on a peak of the estimated phase trajectory for the reflected signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for estimating position of a moving RFID tag, comprising:
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a transmitter for transmitting at least one interrogator signal; a receiver in communication with at least one interrogator antenna receiving a reflected signal from the RFID tag; a phase detector determining phase changes of the reflected signal with respect to a phase of the at least one interrogator signal; a power detector determining instant power of the reflected signal corresponding to the phase changes; a phase peak estimator mathematically weighting the phase changes based on instant power and producing a phase trajectory for the reflected signal based on the weighted phase changes, wherein the phase trajectory represents the phase changes with respect to a distance from the interrogator antenna; the phase peak estimator further generating an estimated phase trajectory based on averaged values of the phase trajectory; and a position estimator determining a position of the RFID tag relative to the at least one interrogator antenna based on a peak of the estimated phase trajectory. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification