Method and terminal for transmitting feedback signal in wireless communication system

1. A method for transmitting a feedback signal by a reception user equipment (UE) in a wireless communication system comprising:

receiving, by the reception user equipment (UE), a first reference signal and a second reference signal from a transmission user equipment (UE); and

transmitting, by the reception user equipment (UE), the feedback signal to the transmission user equipment (UE) based on the first reference signal and the second reference signal,

wherein

the feedback signal includes information about a time difference between a first FFT (Fast Fourier Transform) window for receiving the first reference signal and a second FFT window for receiving the second reference signal; and

a distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated based on a time difference between the first FFT window and the second FFT window.

2. The method according to claim 1 , wherein the receiving includes:

receiving the first reference signal through a first frequency domain; and

receiving the second reference signal through a second frequency domain different from the first frequency domain.

3. The method according to claim 1 , wherein:

the feedback signal further includes information about the first FFT window and information about the second FFT window.

4. The method according to claim 1 , further comprising:

acquiring, by the reception user equipment (UE), a phase difference between the first reference signal and the second reference signal, the phase difference being caused by a first radio frequency (RF) chain for receiving the first reference signal and a second radio frequency (RF) chain for receiving the second reference signal,

wherein

the transmitting includes transmitting the feedback signal including information about the phase difference to the transmission user equipment (UE); and

the distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated based on the phase difference information.

5. The method according to claim 1 , further comprising:

calculating a time difference between a first transmission time point where the transmission user equipment (UE) transmits the first reference signal and a second transmission time point where the transmission user equipment (UE) transmits the second reference signal, based on a time difference between a first reception time point where the reception user equipment (UE) receives the first reference signal and a second reception time point where the reception user equipment (UE) receives the second reference signal.

6. The method according to claim 5 , wherein the feedback signal further includes:

information about a time difference between the first reception time point where the reception user equipment (UE) receives the first reference signal and the second reception time point where the reception user equipment (UE) receives the second reference signal.

7. The method according to claim 5 , wherein:

the feedback signal includes a first feedback signal corresponding to the first reference signal and a second feedback signal corresponding to the second reference signal,

the method further comprises:

transmitting, by the reception user equipment (UE), at least one of first information about a time difference between the first reception time point and a third transmission time point where the reception user equipment (UE) transmits the first feedback signal, and second information about a time difference between the second reception time point and a fourth transmission time point where the reception user equipment (UE) transmits the second feedback signal, to the transmission user equipment (UE), and

the distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated based on at least one of the first information indicating a time difference between the third transmission time point and the first reception time point and the second information indicating a time difference between the fourth transmission time point and the second reception time point.

8. The method according to claim 1 , wherein:

the feedback signal includes a first feedback signal corresponding to the first reference signal and a second feedback signal corresponding to the second reference signal,

the method further comprises:

transmitting, by the reception user equipment (UE), at least one of first information about a time difference between the third transmission time point where the reception user equipment (UE) transmits the first feedback signal and the fourth transmission time point where the reception user equipment (UE) transmits the second feedback signal, to the transmission user equipment (UE), and

the distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated based on information about a time difference between the third transmission time point and the fourth transmission time point.

9. The method according to claim 1 , wherein:

the distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated further based on a time difference between a transmission time point where the first reference signal is transmitted and a transmission time point where the second reference signal is transmitted.

10. The method according to claim 1 , wherein:

the reference signal is a reference signal for positioning or a reference signal for ranging.

11. A reception user equipment (UE) for transmitting a feedback signal in a wireless communication system comprising:

a transceiver; and

a processor,

wherein

the processor is configured to:

receive a first reference signal and a second reference signal from a transmission user equipment (UE); and

transmit the feedback signal to the transmission user equipment (UE) based on the first reference signal and the second reference signal,

wherein

the feedback signal includes information about a time difference between a first FFT (Fast Fourier Transform) window for receiving the first reference signal and a second FFT window for receiving the second reference signal; and

a distance between the transmission user equipment (UE) and the reception user equipment (UE) is calculated based on a time difference between the first FFT window and the second FFT window.

12. The reception user equipment (UE) according to claim 11 , wherein:

the reception user equipment (UE) is configured to communicate with at least one of a mobile terminal, a network, and an autonomous vehicle other than the device.

13. The reception user equipment (UE) according to claim 11 , wherein:

the reception user equipment (UE) is configured to implement at least one advanced driver assistance system (ADAS) function based on a signal for controlling movement of the reception user equipment (UE).

14. The reception user equipment (UE) according to claim 11 , wherein:

the reception user equipment (UE) receives a user input signal from a user, switches a driving mode of the device from an autonomous driving mode to a manual driving mode, or switches a driving mode of the device from the manual driving mode to the autonomous driving mode.

15. The reception user equipment (UE) according to claim 11 , wherein:

the reception user equipment (UE) is autonomously driven based on external object information,

wherein the external object information includes at least one of information indicating presence or absence of an object, position information of the object, information about a distance between the reception user equipment (UE) and the object, and information about a relative speed between the reception user equipment (UE) and the object.