Methods and apparatuses for determining tag velocity

A RFID reader, comprising:

• a radar configured to:
• transmit at least one incident radar signal;
• receive at least one reflected radar signal in response to the at least one incident radar signal reflected from a person associated with the RFID tag;
• a RFID driver configured to:
• transmit at least one incident RFID signal;
• receive at least one backscattered RFID signal from the RFID tag;
• and
• a processor configured to:
• determine a first movement vector of the person based on the reflected radar signal;
• determine a second movement vector of the RFID tag based on at least one phase measurement of the at least one backscattered RFID signal;
• and
• determine whether the RFID tag is associated with the person based on the first movement vector and the second movement vector.

A non-transitory computer readable medium comprising instructions that, when executed by a processor, cause the processor to:

• cause a radar to:
• transmit at least one incident radar signal;
• receive at least one reflected radar signal in response to the at least one incident radar signal reflected from a person associated with the RFID tag,
• cause a RFID driver to:
• transmit at least one incident RFID signal;
• receive at least one backscattered RFID signal from the RFID tag,
• determine a first movement vector of the person based on the reflected radar signal,
• determine a second movement vector of the RFID tag based on at least one phase measurement of the at least one backscattered RFID signal, and
• determine whether the RFID tag is associated with the person based on the first movement vector and the second movement vector.

A method by a radio frequency identification (RFID) scanner to determine a position of a RFID tag in a retail store, comprising:

• transmitting a first incident radar signal of the plurality of incident radar signals toward a first direction of a plurality of directions;
• transmitting a second incident radar signal of the plurality of incident radar signals toward a second direction of a plurality of directions;
• receiving a first reflected radar signal of the plurality of reflected radar signals in response to the first incident radar signal impinging on the person at a first time;
• receiving a second reflected radar signal of the plurality of reflected radar signals in response to the second incident radar signal impinging on the person at a second time
• measuring a first radar transmit time between transmitting the first incident radar signal of the plurality of incident radar signals and receiving the first reflected radar signal of the plurality of reflected radar signals;
• measuring a second radar transmit time between transmitting the second incident radar signal of the plurality of incident radar signals and receiving the second reflected radar signal of the plurality of reflected radar signals;
• determining a first position of the person based on the first radar transit time and the first direction;
• determining a second position of the person based on the second radar transit time and the second direction;
• determining a first movement vector based on the first position and the second position;
• transmitting a first incident RFID signal having a wavelength;
• transmitting a second incident RFID signal having the wavelength within a threshold duration after the first incident RFID signal, wherein the threshold duration is less than an estimated time for the RFID tag to move one-fourth or one-half of the wavelength;
• receiving a first backscattered RFID signal in response to the first incident RFID signal impinging on the RFID tag at a first time;
• receiving a second backscattered RFID signal in response to the second incident RFID signal impinging on the RFID tag at a second time;
• determining a first phase shift between the first incident RFID signal and the first backscattered RFID signal;
• determining a second phase shift between the second incident RFID signal and the second backscattered RFID signal;
• determining a first position of the RFID tag based on the first phase shift;
• determining a second position of the RFID tag based on the second phase shift;
• and
• determining the second movement vector based on the first position and the second position.