KR20150105179A - Method and apparatus of proximity estimation using round trip time in a wireless communication system - Google Patents

Method and apparatus of proximity estimation using round trip time in a wireless communication system Download PDF

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KR20150105179A
KR20150105179A KR1020140157057A KR20140157057A KR20150105179A KR 20150105179 A KR20150105179 A KR 20150105179A KR 1020140157057 A KR1020140157057 A KR 1020140157057A KR 20140157057 A KR20140157057 A KR 20140157057A KR 20150105179 A KR20150105179 A KR 20150105179A
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signal
distance
frequency
communication system
wireless communication
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KR1020140157057A
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Korean (ko)
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안드레이 조벤코
김수용
정진용
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삼성전자주식회사
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Priority to US14/640,747 priority Critical patent/US20150256974A1/en
Publication of KR20150105179A publication Critical patent/KR20150105179A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0284—Relative positioning
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
    • H04L27/12—Modulator circuits; Transmitter circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/029—Location-based management or tracking services

Abstract

The present invention relates to a method and an apparatus for proximity estimation for measuring distance of a device in a wireless communications system. The method in the present invention comprises the following processes: a first device transmits a first signal to a second device; the first device receives a second signal from the second device as a response to the first signal; and the first device measures distance between the first device and the second device based on a phase difference between the first signal and the second signal.

Description

[0001] The present invention relates to a proximity estimation method and apparatus using a round-trip delay time in a wireless communication system, and a method and an apparatus for providing a location-based service using the round-

The present invention relates to a method and apparatus for estimating a position in a wireless communication system, and more particularly, to a method and apparatus for estimating a proximity position that can be used indoors.

One of the important technologies required in Internet-of-Things (IoT) and Location Based Services (LBS) is the Indoor Positioning System (IPS).

The IPS may be implemented using, for example, an Inertial Navigation System (INS) using microelectromechanical systems (MEMS) sensors, a fingerprinting method using Received Signal Strength, And may be implemented in a time-of-arrival (TOA) scheme (unlike a TOA scheme using satellite receivers in a Global Navigation Satellite System (GNSS)).

On the other hand, in the case of implementing the IPS in the wireless communication system, power consumption of a terminal using a battery having a limited capacity should be considered, so power consumption must be minimized by using a simple but accurate algorithm. However, there is a trade-off between the power consumption of the terminal and the accuracy of the position estimation.

For example, in order to provide an effective LBS such as geofencing in a shopping center with a high flow population, information for location measurement is required such that the IPS has a positioning accuracy of, for example, few meters. However, in a wireless communication system, it is difficult to provide accurate LBS due to a serious multipath environment and complexity of radio waves and limited power consumption in a terminal.

It is also necessary to measure very short timing intervals (e.g., tens of nanoseconds) to improve the TOA estimation accuracy of a terminal in a wireless communication system. For this measurement, it is required to use high frequency in the delay measurement module provided in the terminal, but use of high frequency increases power consumption and development complexity of the terminal.

The present invention provides a proximity estimation method and apparatus for efficiently measuring a distance of a device located in a room in a wireless communication system.

The present invention also provides a method and apparatus for effectively providing location-based services to devices located indoors in a wireless communication system.

A proximity estimation method for measuring a distance of a device in a wireless communication system according to an embodiment of the present invention includes the steps of: a first device transmitting a first signal to a second device; Receiving a second signal in response to the first signal; measuring a distance between the first device and the second device based on a phase difference between the first signal and the second signal; .

In addition, a first device for measuring a distance in a wireless communication system according to an embodiment of the present invention includes a communication interface for communicating with a wireless network, and a second interface for transmitting a first signal to a second device, Receiving a second signal in response to a signal and measuring a distance between the first device and the second device based on a phase difference between the first signal and the second signal, And a control unit for controlling an operation of orthogonal modulation with a frequency.

1 is a block diagram illustrating a proximity estimation method for measuring a distance between devices in a wireless communication system according to an embodiment of the present invention;
2 is a diagram for explaining a process of generating a search signal in a first device according to an embodiment of the present invention,
3 is a diagram for explaining a process of generating a response signal in a second device according to an embodiment of the present invention;
4 is a view for explaining a delay compensation operation performed in a second device according to an embodiment of the present invention;
5 is a diagram for explaining a proximity estimation method performed in a first device according to an embodiment of the present invention;
6 is a flowchart illustrating a proximity estimation method for measuring a distance between devices in a wireless communication system according to an embodiment of the present invention.
7 is a block diagram showing the configuration of a device in a wireless communication system according to an embodiment of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The conventional positioning or distance measuring method using satellite signals can not be used because the signal intensity reaches almost zero level in a room such as a building. The present embodiment, which will be described below, proposes a proximity estimation method for measuring a distance between devices transmitting and receiving a wireless signal for a location-based service in an indoor environment. The wireless communication system to which the proximity estimation method of this embodiment can be applied may be various systems using a wireless communication system based on Wi-Fi, Bluetooth, or Institute of Electrical and Electronics Engineers (IEEE) 802.x.

In addition, the proximity estimation scheme of this embodiment can employ a low power design employing frequencies below the GHz range by employing frequency down conversion by a mixer in the device to reduce power consumption in the device. Therefore, the proximity estimation method proposed in the present embodiment can be applied to various wearable products and mobile devices such as Internet object products. In addition, when the proximity estimation method of the present embodiment is applied to a wireless communication system based on IEEE 802.11, special circuit development is not required in a device using Wi-Fi. For example, a conventional Wi-Fi QAM (Quadrature Amplitude Modulation) A modulator can be easily implemented.

1 is a block diagram illustrating a proximity estimation method for measuring a distance between devices in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 1, when the distance between the first device 110 and the second device 130 is measured, the first device 110 transmits the first signal 11 to the second device 130, And the second device 130 generates and transmits the second signal 13, which is a response signal to the first signal 11, This distance measurement may be performed in devices such as a premises or a shopping center with a proximity within a few meters to several tens of meters, and in this embodiment the first device 110 may be configured to receive the first signal 11 ) Using the phase difference between the first and second signals 11 and 13 based on the round trip time until the second signal 13 is received, And estimates the distance between the device 110 and the second device 130. When the proximity estimation is performed using the propagation delay caused by the reciprocal propagation of the signals transmitted / received between the devices, the accuracy of the proximity estimation can be further improved.

The first and second devices 110 and 130 may be a mobile phone, a tablet PC, a notebook computer, a relay station, a base station, an access point (AP) And the like, and the wireless device will be referred to as a device for the sake of convenience. In the embodiment of FIG. 1, the first device 110 may be various wireless devices used by a user who wants to measure the distance, and the second device 130 may be a repeater, an AP, a base station, or the like. The second device 130 is used as a reference point for distance measurement.

Also, in the present embodiment, the first and second signals 11 and 13 may use a separate navigation signal provided for distance measurement.

The search signal includes, for example, a synchronization field, a physical layer convergence protocol (PLCP) field, a data field, and a cyclic redundancy check (CRC) field when applied to the IEEE 802.11 standard Lt; / RTI > The data field is located in the physical layer, and the remaining fields are included in the transport layer and used in the payload. In the IPS, the data field may be replaced with a format of the orthogonal modulation search signal instead of the Orthogonal Frequency Division Multiplexing (OFDM) format.

Hereinafter, the proximity estimation method according to the present embodiment will be described in more detail with reference to FIGS. 2 to 5. FIG.

2 is a diagram for explaining a process of generating a search signal in the first device 110 according to an embodiment of the present invention. The navigation signal may be referred to as a sounding signal.

The first device 110 generates a search signal having an envelope as shown in FIG. 2 (b) by combining two harmonic signals 21 and 22 as shown in FIG. 2 (a) do. It is assumed that the two harmonic signals 21 and 22 have different frequencies of f 1 and f 2 , respectively, and have the same amplitude. As shown in FIG. 2 (c), the frequency difference between f 1 and f 2 is shown by Δf. Here, the amplitudes equal to those of the different frequencies f 1 and f 2 cause beating of the envelope in the search signal of the first frequency f cur1 . A search signal transmitted by the second device 130 of FIG. 1 as a response signal to the first device 110 may also be generated using the scheme of FIG.

3 is a diagram for explaining a process of generating a response signal in the second device 130 according to an embodiment of the present invention. 3, reference numerals 31 and 33 denote search signals (hereinafter referred to as first signals) transmitted by the first device 110, search signals (hereinafter referred to as second signals) transmitted by the second device 130 as response signals, Respectively.

In the embodiment of FIG. 3, it is assumed that the first and second signals 31 and 33 are transmitted at different frequencies, respectively. 3, the first signal 31 has a first frequency f cur1 and the second signal 33 has a second frequency f cur2 . Most devices using a wireless LAN (WLAN) are compliant with the IEEE 802.11 standard using Time Division Duplex (TDD). For example, to implement the features of IEEE 802.11n / ac, the latest RF front-end ICs can all have dual bands (e.g., 2.4 GHz and 5 GHz, bandwidths from 20 MHz to 160 MHz per protocol).

Thus, in accordance with the IEEE 802.11 standard, the first signal 31 may be transmitted at a carrier frequency of 2.4 GHz and the second signal 33 may be transmitted at a carrier frequency of 5 GHz. The reverse is also possible. In this embodiment, it is assumed that the first and second signals 31 and 33 are transmitted through different frequency bands. However, the first and second signals 31 and 33 may be transmitted through the same frequency band.

In the example of FIG. 3, based on the structures of WLAN according to the IEEE 802.11 standard, a sine synthesizer (not shown) in the first device 110 first generates a 2.4 GHz carrier signal. The generated carrier signal is input to an orthogonal modulator (not shown) in the first device 110 together with a sine wave signal having a frequency of 1 to 20 MHz, RF (Radio Frequency) modulated, and amplified by an amplifier And is transmitted to the first signal 31. [

In the example of FIG. 3, the second device 130 demodulates the received first signal 31 (301) and re-modulates the received first signal 31 into a second signal 33 (305). At this time, the frequency band to be remodulated may be 5 GHz. The phase of the envelope of the first signal 31 received by the second device 130 and the phase of the envelope of the second signal 33 transmitted by the second device 130 should be the same. That is, in the example of FIG. 3, the phase of the envelope of the first signal 11 transmitted on the 5 GHz carrier and the phase of the envelope of the second signal 13 transmitted on the 2.4 GHz carrier should be the same.

However, in practice, a slight delay and a phase shift may occur in the signal processing process in the second device 13. In the example of FIG. 3, the second device 13 may perform delay compensation 303 to compensate for this delay and phase shift. The delay compensation 303 may be selectively performed.

4 is a view for explaining a delay compensation operation performed in the second device 130 according to an embodiment of the present invention.

Referring to FIG. 4, reference numerals 401 and 403 denote delays generated in the process of generating and transmitting the first signal 11, that is, delays generated in the process of generating the first signal 11 in the first device 110 (T 1 ) and a delay (t 2 ) generated in the process of transmitting the first signal 11 through the wireless network (t 1 + t 2 ). Reference numeral 405 denotes a delay (? T 3 ) generated in the signal processing process in the second device 130. And 407 denotes a delay (? T 4 ) issued in the process of transmitting the second signal (13) through the wireless network. The delay compensation operation performed in the second device 130 is for compensating the delay? T 3 .

To this end, the second device 130 calculates the phase of the first signal 11 and subtracts the phase delay that the first signal 11 uses to pass through the second device 130 from the calculated phase . The second device 130 then synthesizes the phase-compensated envelope signal by orthogonal modulation. By the delay compensation operation described above, the second signal 13 can compensate for the delay? T 3 in the total phase delay such that the phase delay of the second signal 13 received by the first device 110 is Only the distance between the first and second devices 110 and 130 is required.

Returning to the description of FIG. 3, the second device 13 places the second signal 13 on a new carrier (e.g., a 2.4 GHz carrier) through remodulation 305. And it is assumed that the two harmonic signals used to generate the second signal 13 have different frequencies of f 3 and f 4 , respectively, and have the same amplitude, as in the example of FIG.

5 is a diagram for explaining a proximity estimation method performed by the first device 110 according to an embodiment of the present invention.

Referring to FIG. 5, the first device 110 determines the phase of the first signal 11 in FIG. 5A transmitted by itself through a phase detector (not shown) The phase difference 53 of the two phases is compared with the phase of the second signal 13 in the received device 51 delayed in dependence on the distance between the second device 130 and the first device 110 To the distance between the first device 130 and the second device 130.

In the proximity estimation according to the present embodiment, the coverage range R depends on one cycle of the harmonic frequency and can be expressed by Equation (1) below.

Figure pat00001

Where c is the speed of light and f h is the harmonic frequency (i.e., the envelope frequency in quadrature modulation). For example, when the envelope frequency is 20 MHz, R is about 15 m, and when used at 10 MHz, R is about 30 m.

Indeed, in the case of an indoor environment, such a coverage range R is sufficient to identify the location of the device.

The proximity measurement proposed in this embodiment does not require synchronization between the devices because the proximity measurement uses the periodic signal such as the search signal to measure the distance. However, due to the periodicity and multipath propagation of the modulated signals, there may be multi-solutions for calculating the RTT, and irregular values may be discarded based on the coverage range of the envelope frequencies, considering this. Also, multipath signals that are attenuated in typical indoor conditions, such as in a shopping center or in a residence, are distinguished from directly transmitted signals. Nevertheless, it is possible to use different non-aliquot frequencies of the carriers to avoid confusion caused by multiple solutions. For example, the first signal may be modulated at 20 MHz and the second signal at 18.7 MHz. If the first and second devices know the information, the phase detector of the first device can find the correct solution to the coverage range.

In the phase detection operation of the first device 110, phase detection by I-Q modulation is performed, and phase difference is measured by RTT. The first device 110 transmits the modulated first signal 11 and stores the envelope signal through two quantizers (not shown) of each I-Q branch. The first device 110 then receives and demodulates the second signal 13 transmitted at a different carrier frequency and then compares the phase of the first signal 11 with the phase of the second signal 13 through the phase detector, The distance between the first device 110 and the second device 130 is estimated. The phase detector is based on a matched filter and the distance can be calculated from the angle between the vectors of the first signal and the second signal at the IQ surface (i.e., the phase difference) as in the example of Figure 5 .

If the phase difference is P IQ , the distance D can be calculated by Equation (2) below.

Figure pat00002

Where c is the speed of light and f h is the harmonic frequency.

2 to 5, the first device 110 performs an efficient proximity estimation that increases the positioning accuracy using the round trip delay time (RTT) and reduces the power consumption by using the orthogonal modulation .

6 is a flowchart illustrating a proximity estimation method for measuring a distance between devices in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 6, in step 601, the first device 110 transmits the first signal 11 modulated at the first frequency to the second device 130. At this time, it is possible to use a relatively low frequency orthogonal modulation so as to reduce power consumption in transmission of the first signal 11. In operation 603, the first device 110 demodulates the first signal 11 from the second device 130, and then receives the second signal 13, which is re-modulated to the second frequency. At this time, after demodulation of the first signal 11 in the second device 130, delay compensation is performed, and then re-modulation to the second signal 13 can be performed. In step 605, the first device 110 demodulates the second signal 13 received from the second device 130 and demodulates the first signal 11 and the second signal 13 based on the phase difference between the first signal 11 and the second signal 13, The distance between the device 110 and the second device 130 is measured.

7 is a block diagram showing a configuration of a device in a wireless communication system according to an embodiment of the present invention, and the configuration of FIG. 7 is a schematic view of a configuration that can be applied to the first device 110 and the second device 130 .

7, the device includes a controller 701 for controlling the operation of the device as a whole, as well as for controlling the proximity estimation operation according to the method described with reference to FIGS. 1 to 6, a general controller 701 for transmitting signals to the wireless network A transmitter 703 including a modulator and an amplifier as a communication module, and a receiver 703 including a demodulator, an amplifier, and the like as a typical communication module for receiving signals from the wireless network. The controller 701 may be implemented by selectively including envelope detecting means, phase detecting means, delay compensating means, and the like in accordance with the configuration of the device for the proximity estimating operation. Although the transmitting unit 703 and the receiving unit 705 are shown as separate components, they may be implemented by one or more communication interfaces. The communication interface may also include a frequency downconversion mixer to reduce power consumption. In the above embodiment, the measurable distance and accuracy of the proximity estimation may vary depending on the envelope frequency.

The location-based service using the above proximity estimation method can be applied to, for example, a shopping center, a department store, an indoor playground, an amusement park, an apartment, an apartment factory, a premises (hereinafter referred to as a shopping center) in a building.

In this case, a mobile phone or the like of the user operates an application for providing the location-based service and operates as a first device, and a repeater, AP, or base station installed in the shopping center or the like operates as a second device. The application installed in the first device is configured to visually display the measured distance according to the proximity estimation method through a screen provided through the application. The point where the second device is located can be expressed as a store, a facility, or the like, which is easy for the user to recognize at a shopping center or the like, thereby providing various location-based services to the user.

The second device receives distance information measured from the first device according to an operation of the application and provides location-based advertisement information or the like to at least one first device located within a predetermined distance from the second device .

In another embodiment, a user's mobile phone or the like operates as the second device, and a repeater, an AP, or a base station installed in the shopping center or the like in a certain area may operate as the first device. In this case, the first device may provide advertisement information or the like to at least one second device that is measured to be located within a certain distance of the second devices. In this case, when the unique identification information of the second device is stored in the first device, the user location of the second device may be notified to other users related to the user of the second device so that the user can be utilized for searching for missing persons.

According to the embodiment described above, it is possible to have a positioning accuracy of approximately 1 meter, using round-trip delay time (RTT) measurements and proximity estimation using quadrature modulation at a frequency relatively lower than the carrier frequency (e.g., less than GHz) , Reducing power usage in the device.

In addition, according to the above-described embodiment, since the existing structures for signal processing in the device can be reused, the implementation of the device is simple.

Claims (10)

A proximity estimation method for measuring a distance of a device in a wireless communication system,
The first device transmitting the first signal to the second device;
The first device receiving a second signal from the second device in response to the first signal; And
And the first device measures a distance between the first device and the second device based on a phase difference between the first signal and the second signal.
The method according to claim 1,
Wherein the transmitting comprises orthogonally modulating the first signal at a frequency lower than a carrier wave.
The method according to claim 1,
Wherein the first signal and the second signal are modulated at different frequencies and transmitted.
The method according to claim 1,
Wherein the second signal is a signal obtained by demodulating the first signal and then re-modulating the frequency of the first signal to a frequency different from the frequency of the first signal.
5. The method of claim 4,
Wherein the second signal is a signal to which delay compensation is applied by signal processing delay in the second device after demodulation of the first signal.
The method according to claim 1,
Wherein the first device and the second device are located indoors.
The method according to claim 1,
Wherein the first and second signals are generated using a plurality of harmonic signals having different frequencies and having the same amplitude, respectively.
The method according to claim 1,
The step of measuring the distance includes:
Calculating a phase difference by comparing a phase of the first signal with a phase of the second signal; And
And measuring the distance using the phase difference and an envelope frequency used in transmission of the first signal.
A first device for measuring distance in a wireless communication system,
A communication interface for communicating with a wireless network; And
Receiving a second signal from the second device in response to the first signal and transmitting the first signal to the first device based on a phase difference between the first signal and the second signal, And a controller for controlling an operation of measuring a distance between the first device and the second device and orthogonally modulating the first signal to a frequency lower than a carrier wave.
10. The method of claim 9,
Wherein the first signal and the second signal are modulated at different frequencies and transmitted, respectively.
KR1020140157057A 2014-03-06 2014-11-12 Method and apparatus of proximity estimation using round trip time in a wireless communication system KR20150105179A (en)

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