Method for measuring distance in wireless communication system and device therefor

Patent metadata

Field	Value
Publication number	US-11394595-B2
Application number	US-201816500709-A
Country	US
Kind code	B2
Filing date	Apr 3, 2018
Priority date	Apr 4, 2017
Publication date	Jul 19, 2022
Grant date	Jul 19, 2022

Abstract

According to one embodiment of the present invention, a method by which a first wireless device receives a reference signal for distance measurement in a wireless communication system can comprise the steps of: receiving, from a second wireless device, a first reference signal including a first sinusoidal signal having a first angular frequency and a second sinusoidal signal having a second angular frequency; performing fast Fourier transform (FFT) on the first reference signal; acquiring a phase difference between the first sinusoidal signal and the second sinusoidal signal on the basis of the FFT result; and transmitting, to the second wireless device, a second reference signal for the distance measurement and a third reference signal indicating information on the phase difference. The first wireless device is capable of communicating with at least one of another wireless device, a wireless device related to an autonomous driving vehicle, a base station or a network.

First claim

What is claimed is:

1. A method of receiving a reference signal for distance measurement by a first wireless device in a wireless communication system, the method comprising:
receiving, from a second wireless device, a first reference signal including a first sinusoidal signal of a first angular frequency and a second sinusoidal signal of a second angular frequency;
performing fast Fourier transform (FFT) on the first reference signal;
obtaining a phase difference between the first sinusoidal signal and the second sinusoidal signal based on a result of the FFT; and
transmitting a second reference signal for distance measurement and a third reference signal indicating information about the phase difference to the second wireless device,
wherein the phase difference is calculated by Equation A,

X
RX

⁡

(

w
2

)

X
RX

⁡

(

w
1

)

=

exp
⁡

(

j
*

(

w
2

-

w
1

)

⁢

(

t

s
,
RX

-

t

a
,
RX

)

)

[

Equation
⁢

⁢
A

]

where ‘t s,RX ’ represents a starting time of the FFT for the first reference signal, ‘t a,RX ’ represents an arrival time of the first reference signal at the first wireless device, ‘w 1 ’ represents the first angular frequency, ‘w 2 ’ represents the second angular frequency, ‘X RX (w 1 )’ represents an FFT result of the first sinusoidal signal, and ‘X RX (w 2 )’ represents an FFT result of the second sinusoidal signal.

2. The method according to claim 1 , wherein a phase of the third reference signal has as large an offset as the phase difference from a phase of the second reference signal.

3. The method according to claim 1 , wherein a distance between the first wireless device and the second wireless device is calculated by Equation B,

d
=

c
2

⁢

(

t
symb

-

θ

2
⁢
π
*
Δ
⁢

⁢
f

-

delta
2

)

[

Equation
⁢

⁢
B

]

where ‘d’ represents the distance between the first wireless device and the second wireless device, ‘c’ represents the speed of light, ‘t symb ’ represents one symbol length, ‘θ’ represents the phase difference, Δf represents a subcarrier spacing between the second reference signal and the third reference signal, and ‘delta 2 ’ represents a difference between an arrival time of the second reference signal at the second wireless device and a time of performing FFT on the second reference signal.

4. The method according to claim 3 , wherein ‘delta 2 ’ is calculated by Equation C,
delta 2 =t s,Tx +( n+ 1)* t _symb− t a,Tx   [Equation C]

where ‘t s,Tx ’ represents a time when the first reference signal is transmitted from the second wireless device, ‘t a,Tx ’ represents the arrival time of the second reference signal at the second wireless device, and ‘n’ represents the number of symbols between the first reference signal and the second reference signal.

5. The method according to claim 1 , wherein a process of exchanging the first reference signal, the second reference signal, and the third reference signal is performed alternately in a plurality of wireless devices including the first wireless device, the second wireless device, and the third wireless device.

6. The method according to claim 5 , wherein the first wireless device estimates a distance between the second wireless device and the third wireless device by overhearing

Assignees

• Lg Electronics Inc

Inventors

• Lee Sangrim
• Lee Hojae
• Seo Hanbyul
• Yoon Sukhyon

Classifications

• G01S5/0289

  of multiple transceivers, e.g. in ad hoc networks · CPC title

• H04L5/0048 Primary

  Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091) · CPC title

• G01S13/84

  for distance determination by phase measurement · CPC title

• H04L27/2672

  Frequency domain · CPC title

• H04L27/265 Primary

  Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators (H04L27/26524 takes precedence) · CPC title