KR101221327B1 - Wireless communication method using doppler effect and terminal therefor - Google Patents

Abstract

In a wireless communication method between terminals according to the present invention, a first time period for shaking the first terminal in a wireless communication system including a first terminal for generating a sound signal, one or more second terminals each having a sound collector, and a server Generating a sound signal at the first terminal for a time period comprising a; Receiving the sound signal at each of the second terminals; Calculating a deviation frequency with respect to a reference frequency of the sound signal at each of the second terminals; And performing interaction between the first terminal and a second terminal having the largest deviation frequency among the second terminals.

Description

Wireless communication method between terminals using Doppler effect and terminal therefor {WIRELESS COMMUNICATION METHOD USING DOPPLER EFFECT AND TERMINAL THEREFOR}

The present invention relates to a method for wireless communication between terminals using the Doppler effect, and a terminal therefor.

Recently, various mobile terminals such as a mobile phone including a smart phone and a personal digital assistant (PDA) have been used. Performing a specific task within each of these devices is a simple solution.

However, in order to perform interactions such as exchanging data with each other, the devices have to go through a complicated process. In addition, in order to transfer data from the device to a computer or the like, a process such as an external cable connection is required.

There is a need for a technique that can simplify and facilitate interactions such as data transmission and reception between mobile terminals. There is also a need to facilitate interaction such as data transmission and reception between the mobile terminal and a terminal such as a computer.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems and demands of the prior art, and an object thereof is to provide a wireless communication method for easily and simply interacting between terminals using the Doppler effect, and a terminal therefor.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

Terminal according to an embodiment of the present invention comprises a sound collector for receiving a sound signal; A processor for calculating a deviation frequency with respect to a reference frequency of the sound signal; And a communication unit capable of interacting with the originating terminal of the sound signal according to the magnitude of the deviation frequency.

Wireless communication method of the terminal according to an embodiment of the present invention comprises the steps of receiving a sound signal; Calculating a deviation frequency with respect to a reference frequency of the sound signal; And performing interaction with the originating terminal of the sound signal according to the magnitude of the deviation frequency.

In a wireless communication method between terminals according to an embodiment of the present invention, in a wireless communication system including a first terminal for generating a sound signal, at least one second terminal having a sound collector, and a server, the first terminal for shaking the first terminal Generating a sound signal at the first terminal for a time period comprising a one time period; Receiving the sound signal at each of the second terminals; Calculating a deviation frequency with respect to a reference frequency of the sound signal at each of the second terminals; And performing interaction between the first terminal and a second terminal having the largest deviation frequency among the second terminals.

According to the present invention, it is possible to provide a wireless communication method and a terminal therefor that can easily and simply perform interactions between terminals using the Doppler effect. That is, according to the present invention, it is possible to provide a wireless communication method and a terminal therefor, which enable interaction between terminals by only shaking the terminal without an external connection cable or additional manipulation.

1 is a view for explaining the Doppler effect.
2 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.
3 is a flowchart illustrating a method of wireless communication in a wireless communication system according to an embodiment of the present invention.
4 illustrates a method for calculating a deviation frequency according to an embodiment of the present invention.
5 is a graph illustrating the accuracy of object selection in a wireless communication method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of preferred embodiments of the present invention will be given with reference to the accompanying drawings. The shape and the size of the elements in the drawings may be exaggerated for clarity of explanation and the same reference numerals are used for the same elements and the same elements are denoted by the same quote symbols as possible even if they are displayed on different drawings Should be. In the following description, well-known functions or constructions are not described in detail to avoid unnecessarily obscuring the subject matter of the present invention.

The present invention uses a frequency shift phenomenon according to the Doppler effect to perform an interaction such as data transmission and reception between terminals. The Doppler effect refers to a phenomenon in which the frequency and wavelength change depending on the relative velocity of the source and observer of a wave.

1 is a view for explaining the Doppler effect. The source 100 emits a wave having a frequency f ₀ , for example a sound signal. It is assumed that the source 100 moves at a speed of Vs on an extension line with the observer 200. It is assumed that the observation body 200 moves at a speed of Vr on the same extension line. At this time, the frequency of the source measured in the observer 200 is as follows.

수학식1

Equation 1

Where V is the speed in the medium of the wave from the source, i.e. the speed of the sound signal. Vs is the velocity of the source relative to the medium. Vr is the velocity of the object with respect to the medium.

 Here, the frequency f measured by the observer 200 increases when the source 100 and the observer 200 move toward each other, and the source 100 and the observer 200 move away from each other. When moving in the direction, the frequency f measured by the observer 200 decreases.

The difference value Δf between the frequency fo generated at the source 100 and the frequency f observed at the observer 200 may be expressed as follows.

수학식2

Equation 2

That is, the frequency difference value Δf is a difference value between the occurrence frequency fo of the source 100 and the observation frequency f of the observer 200.

As can be seen from Equation 1, the frequency difference value Δf increases as the relative speed between the source 100 and the observer 200 increases. The frequency difference value Δf increases as the frequency fo of the wave generated in the source 100 increases. In addition, when the moving speed of the source 100 and the observer 200 is determined, an extension line between the source 100 and the observer 200 connecting the source 100 and the observer 200 is provided. When the phase moves, the difference value Δf becomes large.

Assuming that the observer 200 is stationary, the difference value Δf increases as the source 100 moves. In addition, when the moving speed of the source 100 is fixed, the difference value Δf when the source 100 moves on the extension line connecting the observer 200 and the source 100 is It is large compared with the difference value (DELTA f) when the source body 100 moves to shift | deviate from the said extension line.

The present invention intends to perform interactions such as data transmission and reception between terminals using this Doppler effect. For example, in order to transfer data between terminals or between a mobile terminal and a computer, a complicated operation such as a cable connection is required. However, in the present invention, data can be transmitted and received between the source terminal and the target terminal only by shaking the source terminal generating a predetermined wave using the Doppler effect. That is, the target terminal may initiate interaction with the source terminal by detecting a predetermined wave of the source terminal, for example, a frequency shift of a sound signal. Such interaction may include various tasks such as connection between terminals, data transmission and reception, data folder sharing, and the like.

2 is a diagram illustrating a wireless communication system according to an embodiment of the present invention. The wireless communication system according to the present invention includes a first terminal 10 for generating a sound signal, at least one second terminal 21, 22, 23 having a sound collector, and the second terminal 21, 22, 23, respectively. It may include a server 30 that can communicate with).

The first terminal 10 and the second terminal 21, 22, 23 may include a mobile terminal such as a smart phone, a mobile phone, a PDA, and the like. In addition, the first terminal 10 and the second terminal (21, 22, 23) may include a terminal such as a laptop (laptop) computer, a desktop (desk top) computer. The first terminal 10 and the second terminal 21, 22, 23 may be any terminal having a sound input / output device.

In addition, the first terminal 10 and / or the second terminal (21, 22, 23) is provided with a communication unit capable of performing wireless communication for interaction such as data transmission and reception. In this case, the first terminal 10 or the second terminal 21, 22, 23 may communicate with the server 30 through the communication unit.

Although two second terminals 21, 22, and 23 are shown in FIG. 2, it is also possible to include a larger number of second terminals or a smaller number of second terminals.

The server 30 may communicate with the first terminal 10 or the second terminal 21, 22, 23 wirelessly or by wire, and may communicate with the first terminal 10 or the second terminal 21, 22, 23. It is a subsystem that can provide certain services upon request.

3 is a flow chart for implementing a wireless communication method according to an embodiment of the present invention in the wireless communication system of FIG.

In the following, an embodiment of the present invention will be described, taking the case where the first terminal 10 intends to transmit data to the second terminal 22.

As shown in FIG. 3, a sound signal may be generated after designating data to be transmitted to the second terminal 22 (S41). It is possible to start the above step even without specifying the data to be transmitted. In this case, it is also possible to specify the data to be transmitted after step S46 to be described below.

In this case, the sound signal is a sound signal having a specific frequency. For example, the reference frequency of the sound signal may have 3 kHz. In addition, it is possible to use different sizes of frequencies according to the embodiment.

Here, the sound signal is generated for a predetermined time period. For example, a sound signal may be generated for about 5 seconds. The shaking of the first terminal 10 may be performed during some time period of the predetermined time period. For example, after 2 to 3 seconds have elapsed after the start of the sound signal generation, the first terminal 10 may be shaken for 1 to 1.5 seconds. Accordingly, the second terminals 21, 22, and 23 may calculate the magnitude of the deviation frequency due to the shaking operation after obtaining the reference frequency of the sound signal generated by the first terminal 10.

However, this is merely an example and the sound signal may occur only while shaking the first terminal 10. This is possible when the second terminals 21, 22, and 23 know information about the reference frequency of the sound signal in advance.

In the case where one or more second terminals 21, 22, and 23 exist, data is stored in a terminal that obtains the largest deviation frequency from the first terminal 10 among the one or more second terminals 21, 22, and 23. Can be transmitted.

In order for the first terminal 10 to transmit data to the second terminal 22 in the middle of the second terminals 21, 22, and 23, the largest deviation frequency must be generated in the second terminal 22. To this end, the shaking operation of the first terminal 10 is preferably performed on an extension line connecting the first terminal 10 and the second terminal 22. For example, in the arrangement as shown in FIG. 2, the first terminal 10 may be shaken to repeatedly move up and down. This shaking motion can be three round trips in approximately 1.5 seconds. In this case, the largest deviation frequency may be obtained from the second terminal 22 among the second terminals 21, 22, and 23.

The shaking operation may be in the form of repetitive reciprocating motion having a predetermined amplitude of the first terminal 10, but this is only an example and may be moved once in one direction.

The sound signal generated by the first terminal 10 is received by one or more second terminals 21, 22, and 23 (S42). The second terminal 21, 22, 23 according to the present invention should be provided with a sound collector capable of receiving a sound signal.

Here, the second terminal 21, 22, 23 may have information about the reference frequency of the sound signal in advance. In this case, the step of calculating the reference frequency of the sound signal received by the second terminal (21, 22, 23) can be omitted. When the second terminals 21, 22, and 23 do not have information on the reference frequency of the sound signal generated by the first terminal 10, the second terminals 21, 22, and 23 calculate the reference frequency. The process can be performed.

For example, the first terminal 10 may generate a sound signal but remain in a stopped state without a shaking operation for the first predetermined time. The second terminals 21, 22, and 23 may obtain information about the reference frequency by obtaining the frequency of the sound signal during the first predetermined time.

One or more second terminals 21, 22, and 23 calculate a deviation frequency Δf relative to the reference frequency of the sound signal, respectively (S43). The deviation frequency Δf is a difference value between the frequency of the sound signal measured by the second terminals 21, 22, and 23 and the reference frequency while shaking the first terminal 10. The frequency of the sound signal measured by the second terminal 21, 22, 23 is different from each other by the shaking operation of the first terminal.

The calculation of the deviation frequency Δf in each of the one or more second terminals 21, 22, and 23 may be performed in the frequency domain. That is, sound data in the time domain may be transformed into data in the frequency domain by Fourier transform. In this case, the deviation frequency Δf may be obtained by normalizing the converted frequency data with respect to the reference frequency of the sound signal.

The second terminal may be equipped with a processor capable of performing the calculation of this deviation frequency and / or reference frequency. In addition, in the second terminal, the calculation of the deviation frequency and / or the reference frequency may be performed by recording the sound signal or may be performed in real time while receiving the sound signal.

4 illustrates a method for calculating a deviation frequency according to an embodiment of the present invention. An example of a method of calculating the deviation frequency of the sound signal received from the first terminal 10. The deviation frequency Δf is calculated from the sound data for a predetermined time period. For example, the sound data includes sound data for 4 seconds.

In this case, in order to obtain the deviation frequency, the four-second time period is divided into a predetermined number of sub-zones. For example, it is divided into four subzones, each subzone representing a time interval of one second. The reason for dividing into sub zones is to adopt only meaningful portions of sound data during the predetermined time period.

Since it is not clear in which time period during the predetermined time period the shaking operation of the first terminal 10 is made, the predetermined time period may be determined to be longer than the duration of the shaking operation. However, the predetermined time period is preferably shorter as long as it includes the time interval of the shaking operation. This is because if the predetermined time period includes the time interval of the shaking operation, the longer the period, the longer the sound signal of the reference frequency which is the original frequency of the sound signal. A section in which no frequency shift occurs during a predetermined time period during which a sound signal is recorded occurs. This meaningless section information may cause an error in calculating the deviation frequency Δf.

Therefore, in order to compensate for the uncertainty at the time of the occurrence of the shaking motion, the frequency shift should be calculated for the sound data of a relatively long time interval, but in order not to consider the meaningless part of the time interval in which the motion is not shaken in the frequency transition calculation. The step of dividing the time interval into smaller zones can be made.

Fourier transform is performed on the sound data of each of the four sub-zones. Here, an FFT (Fast Fourier Transform) capable of performing Discrete Fourier Transforms at high speed may be used. For example, the Radix-2 Cooley-Tukey FFT algorithm may be used. In addition, an In-place FFT algorithm may be used instead of the Cooley-Tukey FFT algorithm, which does not require additional buffer memory. In-Place FFT is similar to Cooley-Tukey FFT except that it uses a loop algorithm instead of a recursion algorithm in the program.

In performing the FFT, the sampling rate is preferably set higher than the Nyquist rate with respect to the reference frequency of the sound signal. This is because the magnitude of the frequency actually measured by the second terminals 21, 22, and 23 may be greater than the reference frequency in the shaking operation such as the reciprocating movement of the first terminal 10.

For example, a sampling frequency of 8 kHz may be used for a sound signal having a reference frequency of 3 kHz. If a reference frequency greater than 3 kHz is used, a sampling frequency greater than 8 kHz is preferably used.

Sound data of each of the four sub-zones is converted into frequency data due to the above conversion. Frequency data for each of the subzones is normalized based on a reference frequency.

Then, the frequency and reference frequency difference value Δf of the normalized frequency data in each of the subzones is calculated. Then, the difference value Δf sums the frequency data of each non-zero subzone. In this case, the Δf value becomes 0 in a section in which no shaking operation is performed in the subregion, and thus may be ignored in calculating the deviation frequency.

The frequency difference values of the non-zero sub-zones are summed and then normalized to finally obtain the deviation frequency Δf of the sound data for the 4-second time interval. In this case, when the finally obtained deviation frequency Δf is a negligible value, it may be ignored. For example, when the deviation frequency Δf has a magnitude less than 10% of the reference frequency magnitude, it may be ignored and the next procedure may not be performed. This is because the frequency shift by the first terminal 10 may be due to a slight movement, not for the purpose of interaction such as data transmission. It is also because the shaking operation by the first terminal is not likely to be the target terminal.

Referring again to FIG. 3, the thus obtained deviation frequency Δf is transmitted from the one or more second terminals 21, 22, and 23 to the server 30, respectively (S44). Such communication with the server 30 may be performed through the communication unit of the second terminal (21, 22, 23). In this case, the deviation frequency Δf may have a magnitude greater than or equal to 10% of the reference frequency.

The server 30 compares the magnitudes of the deviation frequencies Δf received during a predetermined time. For example, the server 30 may consider only the deviation frequency Δf received for 5 seconds from the time when the deviation frequency Δf is first received. The server 30 determines the largest deviation frequency Δf by comparing the magnitudes of the deviation frequencies Δf received during a predetermined time. For example, the server 30 may determine the largest deviation frequency Δf among the deviation frequencies transmitted from the one or more second terminals 21, 22, and 23. At this time, since the first terminal 10 shakes the second terminal 22 in the center of the second terminals 21, 22, and 23, the deviation frequency of the second terminal 22 ( It is likely that Δf) is determined to be the largest.

The server 30 transmits the result to the second terminal 21, 22, 23. That is, the second terminal 22 in the middle of the second terminals 21, 22, and 23 transmits a command indicating that data can be transmitted. The remaining second terminals 21 and 23 may transmit a command indicating that data cannot be received. In this case, the means for delivering the command may be in the form of a short message service (SMS). In addition, any form of instruction for making the state of the second terminal 22 a data reception state is possible.

In this case, in order for the server 30 to correctly transmit a command to each of the second terminals 21, 22, and 23, the server 30 needs to know which deviation frequency value Δf belongs to which terminal. have.

Each of the second terminals 21, 22, and 23 may transmit its ID to the server 30 when sending its deviation frequency to the server. This ID may be provided from the server 30 when the server 30 is connected.

In response to the command transfer, the second terminal 22 receives data from the first terminal 10 (S47).

In the above, the case where the first terminal 10 transmits data to the second terminal 22 has been described as an example. However, data transmission may be made from the second terminal 22 to the first terminal 10. In addition, the interaction between the first terminal 10 and the second terminal 22 may include tasks such as file sharing.

According to the embodiment of the present invention as described above, it is possible to perform mutual operations such as data transmission and reception to other mobile terminals by simply shaking the mobile terminals. In addition, even between a mobile terminal and a fixed terminal such as a computer, it is possible to perform mutual operations such as data transmission and reception by only shaking the mobile terminal.

5 is a graph illustrating the accuracy of object selection in a wireless communication method according to an embodiment of the present invention. In this experiment, UMPC (Ultra Mobile PC) was used as a sound signal generating terminal and a receiving terminal. The amplitude of the shaking motion of the sound signal generating terminal was approximately 10 cm and the shaking motion was performed three times for approximately 1.5 seconds. The reference frequency of the sound signal is 3 kHz and the sampling rate of the receiving terminal is 8 kHz. At this time, it is a graph showing the accuracy of the object selection according to the distance between the two terminals. From the graph, it can be seen that when the distance between the two terminals is about 40 cm or more, the accuracy of the object selection is almost 100%.

Therefore, in order to implement the present invention, it is necessary to maintain a proper distance between the first terminal 10 and the target terminal 22. In this case, it is apparent that the distance may vary depending on the magnitude of the frequency generated by the first terminal 10, the speed of the movement, the direction of the movement, and / or the sound collecting ability of the second terminal 22. In addition, when the other terminals 21 and 23 are located around the target terminal 22, it is required to shake the first terminal 10 in the direction where the deviation frequency is the largest in the target terminal 22.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be. Therefore, it should be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

100: observer 200: source
10: first terminal 21, 22, 23: second terminal
30: server

Claims (25)

A sound collector for receiving a sound signal;
A processor for calculating a deviation frequency with respect to a reference frequency of the sound signal; And
And a communication unit capable of interacting with the originating terminal of the sound signal according to the magnitude of the deviation frequency. The method of claim 1,
The interaction is characterized in that it comprises a data transmission and reception or data sharing with the originating terminal. The method of claim 1,
Wherein,
Transmitting the deviation frequency to a server and receiving a command from the server as to whether to perform the interaction, and performing the interaction according to the command. The method of claim 1,
And the reference frequency is a peak frequency of the sound signal. 5. The method of claim 4,
The deviation frequency is,
And a maximum difference value between the frequency of the sound signal and the reference frequency for a predetermined time period. Claim 6 has been abandoned due to the setting registration fee. The method of claim 5,
The predetermined size is a terminal, characterized in that 10% of the reference frequency size. The method of claim 1,
The processor comprising:
Divide the predetermined time period into a predetermined number of sub-zones,
Obtaining a difference value between the frequency of the sound signal and the reference frequency in each sub-zone, and
And calculating the deviation frequency by normalizing the sum of frequency values in each of the non-zero subzones. Claim 8 was abandoned when the registration fee was paid. The method of claim 7, wherein
And the deviation frequency is calculated in the frequency domain. Receiving a sound signal;
Calculating a deviation frequency with respect to a reference frequency of the sound signal; And
Performing interaction with the originating terminal of the sound signal according to the magnitude of the deviation frequency;
Wireless communication method of the terminal. 10. The method of claim 9,
And said interaction comprises transmitting and receiving data or sharing data with said originating terminal. 10. The method of claim 9,
Performing the interaction includes:
Transmitting the deviation frequency to a server, receiving a command from the server as to whether to perform the interaction, and performing the interaction according to the command. 10. The method of claim 9,
The reference frequency is a wireless communication method of the terminal, characterized in that the peak (peak) frequency of the sound signal (peak). 10. The method of claim 9,
The deviation frequency is,
And a maximum difference value between the frequency of the sound signal and the reference frequency for a predetermined time period. Claim 14 has been abandoned due to the setting registration fee. The method of claim 13,
The predetermined size is a wireless communication method of the terminal, characterized in that 10% of the reference frequency size. 10. The method of claim 9,
The step of calculating the deviation frequency is:
Dividing the predetermined time period into a predetermined number of sub-zones;
Obtaining a difference value between the frequency of the sound signal and the reference frequency in each sub-zone; And
And calculating the deviation frequency by summing and then normalizing frequency values in each of the sub-zones whose difference is not equal to zero. Claim 16 has been abandoned due to the setting registration fee. 16. The method of claim 15,
The deviation frequency is calculated in the frequency domain wireless communication method of the terminal. In a wireless communication system comprising a first terminal for generating a sound signal, one or more second terminals each having a sound collector, and a server,
Generating a sound signal at the first terminal for a time period comprising a first time period for shaking the first terminal;
Receiving the sound signal at each of the second terminals;
Calculating a deviation frequency with respect to a reference frequency of the sound signal at each of the second terminals;
Performing an interaction between the first terminal and a second terminal having the largest deviation frequency among the second terminals;
Wireless communication method between terminals. 18. The method of claim 17,
And wherein said interaction comprises data transmission and reception or data sharing with said originating terminal. 18. The method of claim 17,
Before generating the sound signal,
Connecting each of the second terminals to a server; And
And providing a unique ID to each of the second terminals at the server. 18. The method of claim 17,
After calculating the deviation frequency,
Each of the second terminals transmitting the deviation frequency to a server;
Determining the largest deviation frequency of the deviation frequencies received by the server; And
Transmitting a command to perform the interaction to a second terminal having the largest deviation frequency. 18. The method of claim 17,
And the reference frequency is a peak frequency of the sound signal. 18. The method of claim 17,
The deviation frequency is,
And a maximum difference value between a frequency of said sound signal and said reference frequency for a predetermined time period. Claim 23 has been abandoned due to the setting registration fee. The method of claim 22,
And the predetermined magnitude is 10% of the reference frequency magnitude. 18. The method of claim 17,
The step of calculating the deviation frequency is:
Dividing the predetermined time period into a predetermined number of sub-zones;
Obtaining a difference value between the frequency of the sound signal and the reference frequency in each sub-zone; And
And calculating the deviation frequency by summing and then normalizing the frequency values in each of the sub-zones whose difference value is not zero. Claim 25 is abandoned in setting registration fee. 25. The method of claim 24,
The deviation frequency is calculated in the frequency domain.

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