KR101027598B1 - Method and system for human body communication using chirp spread spectrum modulation - Google Patents

Abstract

The present invention relates to a human body communication method and system using chirp spread spectrum (CSS) modulation. According to an aspect of the present invention, a human body communication method using chirp spread spectrum (CSS) modulation, comprising: (a) modulating an input signal on off keying (OOK), and (b) Chirp spread spectrum modulating an off modulated signal, and (c) transmitting the chirp spread spectrum modulated signal. According to the present invention, it is possible to achieve stable and reliable human body communication and to reduce the transmission power by not having to increase the signal strength excessively in order to avoid interference.

Human Body Communication, Chirp Spread Spectrum, CSS, On-Off Modulation, OOK, Differential Binary Phase Shift Keying, DBPSK

Description

Human body communication method and system using chirp spread spectrum modulation {METHOD AND SYSTEM FOR HUMAN BODY COMMUNICATION USING CHIRP SPREAD SPECTRUM MODULATION}

The present invention relates to a human body communication method and system using chirp spread spectrum modulation, and more particularly On Off Keying (OOK) modulation or differential binary phase shift keying (DBPSK) modulation scheme and chirp By combining a spread spectrum (CSS) modulation scheme, the present invention relates to a human body communication method and system that does not require channel estimation but is robust to the influence of ambient interference signals.

With the recent development of wireless communication technology, it has become possible to design and manufacture ultra-compact, low-power transceivers in wireless communication systems. It can be used for diagnosis and treatment.

In particular, the wireless communication system using a very small, low-power transceiver, the function of obtaining information about the human body such as image information, temperature, pressure, pH, etc. inside the human body and transmitting the obtained information to a system located outside the human body It is widely applied to human body communication system. For example, a wireless capsule endoscope system is an example. According to the human body communication system, the wireless capsule endoscope swallowed through the oral cavity moves along the digestive organ, acquires image information of the internal organs of the human body, and obtains the acquired information. May transmit a function to a receiver located outside the body.

However, since the human body communication system performs wireless communication using the inside of the human body, transmission loss may occur largely as the radio signal passes through the human body, and when the high frequency signal is used, it may adversely affect the human body. I have a problem.

Due to the above reasons, the communication through the human body, that is, the communication through the human body channel has a severe limitation on the transmission power, and thus, there are active studies on the technology capable of accurately estimating the characteristics of the human body channel. To date, it is very difficult to estimate the characteristics of the human channel.

Therefore, the general wireless communication technique that requires accurate channel estimation has a limitation that it is not suitable for use in human body communication. If the general wireless communication technique is used for human body communication, it is vulnerable to interference signals from other communication networks. There will be a problem that is not.

Therefore, the need for development of a human body communication method and system that can minimize such problems has emerged.

The present invention is to solve the above problems, On Off Keying (OOK) modulation or Differential Binary Phase Shift Keying (DBPSK) modulation scheme and chirp spread spectrum (CSS) By proposing a system combining a modulation scheme, an object of the present invention is to provide a human body communication system that is robust against the influence of ambient interference signals without requiring channel estimation.

Representative configuration of the present invention for achieving the above object is as follows.

According to an aspect of the present invention, a human body communication method using chirp spread spectrum (CSS) modulation, comprising: (a) modulating an input signal on off keying (OOK), and (b) Chirp spread spectrum modulating an off modulated signal, and (c) transmitting the chirp spread spectrum modulated signal.

According to another aspect of the present invention, a human body communication method using chirp spread spectrum (CSS) modulation, comprising: (a) a signal modulated by on off keying (OOK) modulation and chirp spread spectrum modulation; Receiving, (b) performing band pass filtering on the received signal, (c) performing low pass filtering on the band pass filtered signal, and (d) performing the low pass filtered signal. A method of generating a predetermined output signal by comparing a with a predetermined reference value is provided.

According to another aspect of the present invention, a human body communication method using chirp spread spectrum (CSS) modulation, comprising: (a) modulating an input signal with differential binary phase shift keying (DBPSK), (b) chirp spread spectrum modulating the differential binary phase shift modulated signal, and (c) transmitting the chirp spread spectrum modulated signal.

According to another aspect of the present invention, a human body communication method using chirp spread spectrum (CSS) modulation, comprising: (a) differential binary phase shift keying (DBPSK) modulation and chirp spread spectrum modulation; Receiving the modulated signal, (b) performing band pass filtering on the received signal, and (c) using the mixer to filter the band pass filtered signal and the band pass filtered signal for a predetermined time. Synthesizing the delayed signal, (d) performing low pass filtering on the synthesized signal, and (e) comparing the low pass filtered signal with a predetermined reference value to generate a predetermined output signal There is provided a method comprising a.

According to still another aspect of the present invention, there is provided a human body communication system using chirp spread spectrum (CSS) modulation, comprising: an on-off modulator (On Off Keying, OOK) modulating an input signal, the on-off modulation A system including a chirp spread spectrum modulator for chirp spread spectrum modulating a preconstructed signal and a transmitter for transmitting the chirp spread spectrum modulated signal is provided.

According to another aspect of the present invention, a human body communication system using chirp spread spectrum (CSS) modulation, which receives a signal modulated by on off keying (OOK) modulation and chirp spread spectrum modulation. A receiver, a band pass filter unit performing band pass filtering on the received signal, a low pass filter unit performing low pass filtering on the band pass filtered signal, and the low pass filtered signal with a predetermined reference value. A system is provided that includes a comparison unit for comparing and generating a predetermined output signal.

According to still another aspect of the present invention, there is provided a human body communication system using chirp spread spectrum (CSS) modulation, wherein the differential binary phase shift modulation modulates an input signal by differential binary phase shift keying (DBPSK). And a chirp spread spectrum modulator for chirp spread spectrum modulating the differential binary phase shift modulated signal, and an output section for transmitting the chirp spread spectrum modulated signal.

According to another aspect of the present invention, a human body communication system using chirp spread spectrum (CSS) modulation, which is modulated by differential binary phase shift keying (DBPSK) modulation and chirp spread spectrum modulation. A receiver for receiving a signal, a band pass filter for performing band pass filtering on the received signal, a mixer for synthesizing a signal obtained by delaying the band pass filtered signal and the band pass filtered signal by a predetermined time, and A low pass filter for performing low pass filtering on the synthesized signal and a system for comparing the low pass filtered signal with a predetermined reference value to generate a predetermined output signal are provided.

According to the present invention, by combining On Off Keying (OOK) modulation or Differential Binary Phase Shift Keying (DBPSK) modulation scheme and chirp spread spectrum modulation, it is robust to ambient interference signals without requiring channel estimation. Since the human body communication system can be provided, the effect of enabling stable and reliable human body communication and eliminating the need to increase the signal strength excessively in order to avoid interference is achieved.

In addition, according to the present invention, since the human body communication system can be simplified by adopting a simple structure of a conventional digital modulation type transceiver, the size of the human body communication system such as an endoscope inserted into the human body can be reduced in size. Is achieved.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention.

Configuration of the entire system

1 and 2 are views showing the configuration of a human body communication system according to an embodiment of the present invention by way of example. More specifically, FIGS. 1 and 2 illustrate a transmitter of a human body communication system using an On Off Keying (OOK) modulation scheme and a Chirp Spread Spectrum (CSS) modulation scheme according to an embodiment of the present invention. 100 and a receiver 200 respectively.

1 and 2, a transmitter 100 according to an embodiment of the present invention includes an input unit 110, an on-off modulator 120, a chirp spread spectrum modulator 130, and a transmitter 140. The receiver 200 according to an embodiment of the present invention may include a receiver 210, a band pass filter 220, a low pass filter 230, a comparator 240, and an output 250. It may include.

According to an embodiment of the present invention, the signal input through the input unit 110 is externally through the transmitter 140 after the modulation is performed by the on-off modulator 120 and the chirp spread spectrum modulator 130. It may be transmitted to the receiver 200.

Next, according to an embodiment of the present invention, a signal transmitted from the transmitter 100 through the receiver 210 is received and band pass filtering by the band pass filter 220 and the low pass filter 230, respectively. After the low pass filtering is performed, the low pass filtering may be restored by the comparing unit 240 and output through the output unit 250.

Hereinafter, the operation principle and experimental results of the human body communication system according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 7. For reference, all of the graphs shown in FIGS. 4 to 7 represent the magnitude of the corresponding signal, and it should be understood that all numbers on the vertical axis of each graph represent the relative strength of the signal.

First, the first graph of FIG. 3 is a graph showing an example of a waveform of an input signal input through the input unit 110. Referring to the first graph of FIG. 3, an input signal according to an embodiment of the present invention may be a binary signal having a value of 0 and 1.

3 is a graph showing a waveform of a signal modulated by the on-off modulator 120 by way of example. On-off modulation refers to a modulation method that generates a modulated signal by multiplying an input signal and a carrier. According to this on-off modulation, when the value of the input signal is 1, a modulated signal exists and the value of the input signal is changed. If 0, the modulated signal may not exist. That is, referring to the second graph of FIG. 3, the signal modulated by the on-off modulation scheme according to an embodiment of the present invention represents a value of 1 when the input signal is 1 and 0 when the input signal is 0. It can be seen that the value of.

3 is a graph illustrating a waveform of a signal modulated by the chirp spread spectrum modulator 130 via the on / off modulator 120. Chirp spread spectrum modulation is a type of spread spectrum modulation that modulates using a chirp signal, which is a pulsed signal that increases or decreases in frequency over a period of time. And the influence from the interfering signal can be reduced. Referring to the third graph of FIG. 3, a signal modulated by the chirp spread spectrum modulation method according to an embodiment of the present invention may have a waveform in which a frequency gradually decreases during a time occupied by 1 bit data. .

Next, FIG. 4 is a diagram exemplarily illustrating a signal modulated by on-off modulation and chirp spread spectrum modulation. The first graph of FIG. 4 is a graph showing a signal modulated and transmitted by the transmitter 100 in the frequency domain. Referring to this, it can be seen that the center frequency is about 500 MHz. In addition, the second graph of FIG. 4 is a graph showing a signal modulated and transmitted by the transmitter 100 in the time domain, and it can be seen that the time occupied by one bit data is about 50 nsec.

5 is a diagram exemplarily illustrating a signal received by the receiver 210 of the receiver 200. For reference, the first graph of FIG. 5 shows a frequency domain graph and the second graph of FIG. 5 shows a time domain graph. The signal transmitted from the transmitter 100 (see FIG. 4) may be affected by noise such as interference signals while passing through the human body channel. Referring to the frequency domain graph and the time domain graph of FIG. It can be seen that the signal received by 210 appears as a waveform having a lot of noise.

Next, FIG. 6 is a diagram exemplarily illustrating a signal filtered by the band pass filter 220. For reference, the first graph of FIG. 6 shows a frequency domain graph and the second graph of FIG. 6 shows a time domain graph. According to an embodiment of the present invention, since the chirp spread spectrum modulation scheme used in the transmitter 100 performs a function of spreading the on-off modulated signal in a wide frequency region, the receiver 200 makes the received signal intact. In order to recover, a band pass filter having a wider bandwidth than a band pass filter used in a receiver of a conventional on-off modulation system may be used. That is, according to an embodiment of the present invention, it is possible to demodulate a signal modulated by the chirp spread spectrum modulation method by adjusting the bandwidth of the band pass filter of the receiver to be wider than the conventional on / off modulation / demodulation system. . According to an embodiment of the present invention, since the center frequency of the signal transmitted from the transmitter 100 may be 500 MHz, the center frequency of the pass band of the band pass filter 220 may be set to 500 MHz. Referring to FIG. 6, the waveform of the signal passing through the band pass filter 220 having a pass band having a center frequency of about 500 MHz may be confirmed according to an exemplary embodiment.

Next, FIG. 7 is a diagram exemplarily illustrating a signal filtered by the low pass filter 230. For reference, the first graph of FIG. 7 shows a frequency domain graph and the second graph of FIG. 7 shows a time domain graph. According to an embodiment of the present invention, the high pass signal caused by the chirp spread spectrum modulated signal, the noise signal, etc. may be removed by low pass filtering, and thus the signal passing through the low pass filter 230 is turned on and off. It will have a waveform similar to the signal (see FIG. 3).

Finally, according to an embodiment of the present invention, the comparator 240 may determine the value of the output signal by comparing the signal passing through the low pass filter 230 with a predetermined reference value. For example, the comparison unit 240 may determine the value of the output signal as 1 when the value of the signal passing through the low pass filter unit 230 is greater than the preset value, and when the value of the signal is less than the preset value, You can make the value 0. However, the value of the output signal is not necessarily limited to 0 and 1, and the value of the output signal may be changed appropriately within a range in which the output signal has a different value according to the comparison result with the reference value. .

As described above, complete demodulation may be performed through the band pass filter 220, the low pass filter 230, and the comparator 240, and the demodulated signal may be output through the output unit 250. have.

8 and 9 are views showing the configuration of a human body communication system according to another embodiment of the present invention. More specifically, FIGS. 8 and 9 illustrate a transmitter 300 of a human body communication system using a differential binary phase shift keying (DBPSK) modulation method and a chirp spread spectrum modulation method according to another embodiment of the present invention. It is a figure which shows the receiver 400, respectively.

8 and 9, a transmitter 300 according to another embodiment of the present invention includes an input unit 310, a differential binary phase shift modulator 320, a chirp spread spectrum modulator 330, and a transmitter 340. The receiver 400 according to another embodiment of the present invention may include a receiver 410, a band pass filter 420, a mixer 430, a low pass filter 440, and a comparator 450. ), And may include an output unit 460.

According to another exemplary embodiment of the present invention, the signal input through the input unit 310 is modulated by the differential binary phase shift modulator 320 and the chirp spread spectrum modulator 330 and then externally transmitted through the transmitter 340. It may be transmitted toward the receiver 400. Next, according to another embodiment of the present invention, after the band pass filtering is performed by the band pass filter 420, the signal received through the receiver 410, the band pass filtering is performed and the band pass The signal delaying the filtered signal by the time occupied by 1 bit data is synthesized by the mixer unit 430, and the output of the mixer unit 430 is low pass filtered by the low pass filter unit 440, and compared. It may be restored by the unit 450 and output through the output unit 460.

Hereinafter, with reference to FIGS. 10 to 14 will be described in detail the operation principle and the experimental results of the human body communication system according to another embodiment of the present invention. For reference, all of the graphs shown in FIGS. 11 to 14 represent the magnitude of the corresponding signal, and it should be understood that all numbers on the vertical axis of each graph represent the relative strength of the signal.

First, the first graph of FIG. 10 is a graph showing an example of a waveform of an input signal input through the input unit 310. Referring to the first graph of FIG. 10, an input signal according to another embodiment of the present invention may be a binary signal having a value of 0 and 1.

10 is a graph showing a waveform of a signal modulated by the differential binary phase shift modulator 320 by way of example. Differential binary phase shift modulation is a type of phase shift modulation and means a modulation method that transfers data by changing a phase of a carrier. According to the differential binary phase shift modulation, when a value of an input signal is 0, a phase of a carrier is 180 degrees. Also, if the value of the input signal is 1, the phase of the carrier may not be increased.

10 is a graph showing a waveform of a signal modulated by the chirp spread spectrum modulator 330 by way of example. As described above, chirp spread spectrum modulation is a type of spread spectrum modulation, which means a method of modulating using a chirp signal, which is a pulsed signal whose frequency increases or decreases over a predetermined time period. It is not necessary to estimate the channel and reduce the influence of the interference signal. Referring to the third graph of FIG. 10, according to another embodiment of the present invention, a signal modulated by the chirp spread spectrum modulation method may have a waveform in which a frequency gradually decreases during a time occupied by one bit data.

11 is a diagram illustrating a signal received by the receiver 410 by way of example. For reference, the first graph of FIG. 11 represents a frequency domain graph and the second graph of FIG. 11 represents a time domain graph. According to an embodiment of the present invention, since the signal transmitted from the transmitter 300 may be affected by noise such as interference signals while passing through the human body channel, as shown in FIG. 11, the receiver 410. The signal received by) may represent a waveform having a lot of noise. Meanwhile, referring to FIG. 11, it can be seen that the center frequency of the signal received by the receiver 410 is about 500 MHz.

Next, FIG. 12 is a diagram exemplarily illustrating a signal filtered by the band pass filter 420. For reference, the first graph of FIG. 12 shows a frequency domain graph and the second graph of FIG. 12 shows a time domain graph. According to another embodiment of the present invention, since the chirp spread spectrum modulation scheme used in the transmitter 300 performs a function of spreading a differential binary phase shift modulated signal in a wide frequency region as described above, the receiver 400 In order to recover the received signal intact, it is possible to use a band pass filter having a wider bandwidth than the band pass filter used in the receiver of the conventional differential binary phase shift modulation system. That is, according to another embodiment of the present invention, by modulating the bandwidth of the band pass filter of the receiver 400 wider than the bandwidth of the band pass filter in the conventional differential binary phase shift modulation / demodulation system by modulating the chirp spread spectrum modulation method The demodulated signal can be demodulated. Referring to FIG. 12, according to another embodiment of the present invention, the waveform of the signal passing through the band pass filter 420 having a pass band having a center frequency of 500 MHz may be confirmed.

Next, FIG. 13 is a diagram illustrating a signal passing through the mixer unit 430 by way of example. For reference, the first graph of FIG. 13 shows a frequency domain graph and the second graph of FIG. 13 shows a time domain graph. According to another exemplary embodiment of the present invention, the mixer unit 430 may synthesize a band pass filtered signal and a signal obtained by delaying the band pass filtered signal by the time occupied by 1 bit data, and thus 1 bit in the time domain. The time difference occupied by the data makes it possible to restore the input signal by referring to the phase difference between adjacent signals.

Next, FIG. 14 is a diagram exemplarily illustrating a signal filtered by the low pass filter 440. For reference, the first graph of FIG. 14 shows a frequency domain graph and the second graph of FIG. 14 shows a time domain graph. Referring to FIG. 14, a high frequency signal due to a chirp spread spectrum modulated signal, a noise signal, or the like may be removed according to another embodiment of the present invention.

Finally, according to another exemplary embodiment of the present invention, the comparator 450 may determine the value of the output signal by comparing the signal passing through the low pass filter 440 with a predetermined reference value. For example, the comparator 450 may determine the value of the output signal to be 1 when the value of the signal passing through the low pass filter 440 is greater than the predetermined value, and when the value is less than the predetermined value, You can make the value 0. However, the value of the output signal is not necessarily limited to 0 and 1, and the value of the output signal may be changed appropriately within a range in which the output signal has a different value according to the comparison result with the reference value. .

As a result, an input signal input through the input unit 310 of the transmitter 300 may be output to the output unit 460 of the receiver 400 through a modulation and demodulation process.

Experiment result

Hereinafter, the results of the actual experiment using the human body communication system according to the present invention will be described.

15 shows a conventional on-off (hereinafter referred to as "OOK") modulation scheme, a chirp spread spectrum-on-off (hereinafter referred to as "CSS-OOK") modulation scheme according to the present invention, and a chirp spread spectrum-differential according to the present invention. A diagram showing a result of performing human body communication according to a binary phase shift (hereinafter, referred to as "CSS-DBPSK") modulation scheme. For reference, the horizontal axis of the graph illustrated in FIG. 15 represents a signal to noise ratio (SNR) and the vertical axis represents a bit error rate (BER). In this case, the higher the signal-to-noise ratio, the greater the strength of the transmission signal and the larger the transmission power. The higher the bit error rate, the greater the data error, and the lower the transmission performance. Meanwhile, graphs 1510, 1520, and 1530 indicated by solid lines in FIG. 15 represent experimental results in the absence of interference signals, and graphs 1540, 1550, and 1560 indicated by dotted lines represent experimental results in the presence of interference signals.

First, a human body communication system of the CSS-OOK method according to the present invention will be described. Referring to FIG. 15, the human body communication system 1520 of the CSS-OOK method according to the present invention regardless of the presence or absence of an interference signal is more than the conventional human body communication system 1510 of the OOK method in a section in which a signal-to-noise ratio is about 7 dB or more. It can be seen that the bit error rate is low, that is, the transmission performance is high. Considering the fact that the signal-to-noise ratio is 10 dB or more in the actual human body communication, the CSS-OOK human body communication system 1520 according to the present invention can be said to have superior transmission performance than the conventional OOK human body communication system 1510. .

For example, it may be assumed that a target bit error rate value is set to 10 ⁻⁵ in a human body communication environment in which no interference signal exists. Although the target bit error rate can be achieved by setting the signal strength to be 13 dB to 14 dB, the CSS-OOK human body communication system 1520 according to the present invention has a relative signal strength so that the signal to noise ratio is 11 dB. Even if it is set to be small, the target bit error rate can be achieved. That is, according to the CSS-OOK human body communication system 1520 according to the present invention, it is possible to take advantage of 2dB to 3dB in signal strength as compared to the conventional OOK human body communication system 1510. The power consumption can be reduced and the strong signal can be prevented from adversely affecting the human body.

Next, a human body communication system of the CSS-DBPSK method according to the present invention will be described. Referring to FIG. 15, regardless of the presence or absence of an interference signal, the CSS-DBPSK human body communication system 1530 according to the present invention exhibits a lower bit error rate than the conventional OOK human body communication system 1510 in all sections. That is, it can be seen that the transmission performance is high. That is, according to the CSS-DBPSK-based human body communication system 1530 according to the present invention, it is possible to take advantage in signal strength as compared to the conventional OOK-based human body communication system 1510, thereby reducing power consumption. It becomes possible.

FIG. 16 is a diagram illustrating a result of a comparison experiment between a CSS-OOK human body communication system and a conventional OOK human body communication system according to the present invention. For reference, in the comparison experiment of FIG. 16, the signal-to-noise ratio was all fixed at 12 dB and the size of the interference signal was set to increase gradually. Here, the horizontal axis of the graph shown in FIG. 16 represents the magnitude of the interference signal and the vertical axis represents the bit error rate. In addition, graphs 1610 and 1620 indicated by solid lines in FIG. 16 represent experimental results when no interference signal is present, and graphs 1630 and 1640 shown by dotted lines indicate experimental results when there is an interference signal.

Referring to FIG. 16, when the interference signal does not exist, the CSS-OOK human body communication system 1620 according to the present invention confirms that a bit error rate is lower than that of the conventional OOK human body communication system 2010. Can be.

In addition, referring to FIG. 16, when the interference signal is present, the CSS-OOK human body communication system 1640 and the conventional OOK human body communication system 1630 according to the present invention increase in intensity of the interference signal. Although both bit error rates increase, it can be seen that the human body communication system 1640 of the CSS-OOK method according to the present invention exhibits a significantly lower bit error rate than the conventional human body communication system 1630 of the OOK method. The experimental result may be interpreted to mean that the CSS-OOK human body communication system 1640 according to the present invention is more robust to interference signals than the conventional OOK human body communication system 1630. .

FIG. 17 is a diagram illustrating a result of a comparison experiment between a CSS-DBPSK scheme human body communication system and a conventional OOK scheme human body communication system. Referring to FIG. For reference, in the comparative experiment of FIG. 17, in consideration of the fact that synchronization of time delays (ie, time delays in the mixer unit 430) in an actual human communication environment is difficult to be made accurately, the CSS − The time delay synchronization of the DBPSK type human body communication system was set to be out of order. Meanwhile, the horizontal axis of the graph illustrated in FIG. 17 represents a signal-to-noise ratio, and the vertical axis represents a bit error rate. In addition, the graph indicated by a solid line in FIG. 17 is a conventional OOK-type human body communication system 1710 and a CSS-DBPSK-type human body communication system 1720 according to the present invention. In the case of the human body communication system 1720, synchronization is not achieved. The graphs 1730 to 1750, which represent the state correctly formed and indicated by the dotted lines, indicate a system in which the synchronization is not accurately performed as the human body communication system of the CSS-DBPSK method according to the present invention.

Referring to FIG. 17, the CSS-DBPSK-type human body communication system 1720 according to the present invention has a bit error rate higher than that of the conventional OOK-type human body communication system 1710 in all sections when time delay synchronization is accurately performed. You can see that it appears low. In addition, referring to FIG. 17, when the synchronization of time delays is π / 5, 9π / 5, and 2π in the CSS-DBPSK type human body communication system according to the present invention (1730, 1780, and 1750, respectively), The bit error rate is lower than that of the OOK-based human body communication system 1710, while the CSS-DBPSK-based human body communication system according to the present invention has a deviation of 2π / 5, 3π / 5, π, In the case of 8π / 5 (1740, 1750, 1760, and 1770, respectively), it can be seen that the bit error rate is higher than that of the conventional OOK-type human body communication system 1710. Therefore, unless the deviation of time delay synchronization is too large, it can be said that the CSS-DBPSK type human body communication system 1720 according to the present invention is superior to the conventional OOK type human body communication system 1710.

As described above, by combining the chirp spread spectrum modulation method with a conventional digital modulation method such as an on-off modulation method and a differential binary phase shift modulation method according to the present invention, it is possible to reduce the bit error rate while reducing the strength of the transmission signal. Thus, the effect of being able to reduce power consumption and improve communication reliability is achieved.

Although the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided only to help a more general understanding of the present invention, the present invention is limited to the above embodiments. However, one of ordinary skill in the art can make various modifications and variations from this description.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

1 and 2 are views showing the configuration of a human body communication system according to an embodiment of the present invention by way of example.

3 is a diagram illustrating waveforms of an input signal input through the input unit 110, a signal modulated by the on-off modulator 120, and a signal modulated by the chirp spread spectrum modulator 130.

4 is a diagram exemplarily illustrating a signal modulated by on-off modulation and chirp spread spectrum modulation.

5 is a diagram exemplarily illustrating a signal received by the receiver 210.

6 is a diagram illustrating a signal filtered by the band pass filter 220.

7 is a diagram illustrating a signal filtered by the low pass filter 230.

8 and 9 are views showing the configuration of a human body communication system according to another embodiment of the present invention.

10 is a diagram illustrating waveforms of an input signal input through the input unit 310, a signal modulated by the time modulator 320, and a signal modulated by the chirp spread spectrum modulator 330.

11 is a diagram exemplarily illustrating a signal received by the receiver 410.

12 is a diagram exemplarily illustrating a signal filtered by the band pass filter 420.

13 is a diagram exemplarily illustrating a signal passing through the mixer 430.

14 is a diagram exemplarily illustrating a signal filtered by the low pass filter 440.

15 shows a conventional on-off modulation (hereinafter referred to as "OOK") scheme, a chirp spread spectrum-on-off modulation scheme (hereinafter referred to as "CSS-OOK") scheme, and a chirp spread spectrum-differential according to the present invention. A diagram showing a result of performing human body communication according to binary phase shift modulation (hereinafter, referred to as "CSS-DBPSK").

FIG. 16 is a diagram illustrating a result of a comparison experiment between a CSS-OOK human body communication system and a conventional OOK human body communication system according to the present invention.

FIG. 17 is a diagram illustrating a result of a comparison experiment between a CSS-DBPSK scheme human body communication system and a conventional OOK scheme human body communication system. Referring to FIG.

<Brief description of the major reference numerals>

100, 300: transmitter

110, 310: input unit

120: on-off modulator

320: differential binary phase shift modulator

130, 330: chirp spread spectrum modulator

140, 340: transmitter

200, 400: receiver

210, 410: receiver

220, 420: band pass filter unit

230: low pass filter

240: comparison unit

250: output unit

430: mixer

440: low pass filter

450: comparator

460: output unit

Claims (18)

A human body communication method using chirp spread spectrum (CSS) modulation, (a) On Off Keying (OOK) modulating the input signal, (b) chirp spread spectrum modulating the on-off modulated signal, and (c) transmitting the chirp spread spectrum modulated signal to a remote human telecommunication receiver such that the signal modulated by the on and off modulation and the chirp spread spectrum modulation is sequentially passed by the bandpass filtering and low pass in the human telecommunication receiver. Allowing the output filter to be generated by allowing pass filtering to be compared with a predetermined reference value. How to include. A human body communication method using chirp spread spectrum (CSS) modulation, (a) receiving a signal modulated by On Off Keying (OOK) modulation and chirp spread spectrum modulation, (b) performing band pass filtering on the received signal; (c) performing low pass filtering on the band pass filtered signal, and (d) comparing the low pass filtered signal with a predetermined reference value to generate a predetermined output signal How to include. The method of claim 2, In step (b), The center frequency and bandwidth of the pass band are determined with reference to the frequency band of the signal received by step (a). The method of claim 2, In step (d), And output a first signal if the low pass filtered signal is greater than the predetermined reference value, and output a second signal if the low pass filtered signal is less than the predetermined reference value. A human body communication method using chirp spread spectrum (CSS) modulation, (a) modulating an input signal with differential binary phase shift keying (DBPSK), (b) chirp spread spectrum modulating the differential binary phase shift modulated signal, and (c) transmitting the chirp spread spectrum modulated signal to a remote human telecommunication receiver such that the signal modulated by the differential binary phase shift modulation and the chirp spread spectrum modulation is band pass filtered at the human telecommunication receiver. And then combining the bandpass filtered signal with a signal delayed by a predetermined time by a mixer, performing lowpass filtering, and then comparing the signal with a predetermined reference value to generate a predetermined output signal. How to include. A human body communication method using chirp spread spectrum (CSS) modulation, (a) receiving a signal modulated by differential binary phase shift keying (DBPSK) modulation and chirp spread spectrum modulation, (b) performing band pass filtering on the received signal; (c) synthesizing the bandpass filtered signal and the signal delaying the bandpass filtered signal by a predetermined time using a mixer, (d) performing low pass filtering on the synthesized signal, and (e) comparing the low pass filtered signal with a predetermined reference value to generate a predetermined output signal How to include. The method of claim 6, In step (b), The center frequency and bandwidth of the pass band are determined with reference to the frequency band of the signal received by step (a). The method of claim 6, In the step (c), And wherein the predetermined time is a time occupied by one bit of data. The method of claim 6, In step (d), And output a first signal if the low pass filtered signal is greater than the predetermined reference value, and output a second signal if the low pass filtered signal is less than the predetermined reference value. A human body communication system using chirp spread spectrum (CSS) modulation, An on-off modulator for modulating an input signal on-off keying (OOK); A chirp spread spectrum modulator for chirp spread spectrum modulating the on-off modulated signal, and Transmitting the chirp spread spectrum modulated signal to a remote human telecommunication receiver such that the signal modulated by the on and off modulation and the chirp spread spectrum modulation is sequentially band pass filtered and low pass filtered at the human telecommunication receiver. And a transmitter to generate a predetermined output signal by comparing the reference value with a predetermined reference value. System comprising a. A human body communication system using chirp spread spectrum (CSS) modulation, A receiver for receiving a signal modulated by on off keying (OOK) modulation and chirp spread spectrum modulation; A band pass filter for performing band pass filtering on the received signal; A low pass filter for performing low pass filtering on the band pass filtered signal, and A comparator for generating a predetermined output signal by comparing the low pass filtered signal with a predetermined reference value System comprising a. The method of claim 11, In the band pass filter unit, The center frequency and bandwidth of the pass band is determined with reference to the frequency band of the signal received by the receiver. The method of claim 11, And the comparing unit outputs a first signal when the low pass filtered signal is greater than the predetermined reference value, and outputs a second signal when the low pass filtered signal is smaller than the predetermined reference value. A human body communication system using chirp spread spectrum (CSS) modulation, Differential Binary Phase Shift Keying (DBPSK) modulates the input signal to differential binary phase shift keying (DBPSK), A chirp spread spectrum modulator for chirp spread spectrum modulating the differential binary phase shift modulated signal, and The chirp spread spectrum modulated signal is transmitted to a remote human telecommunications receiver such that the signal modulated by the differential binary phase shift modulation and the chirp spread spectrum modulation is band pass filtered at the human telecommunication receiver and then to the mixer. An output unit configured to generate a predetermined output signal by combining the bandpass filtered signal with a signal delayed by a predetermined time and then performing low pass filtering and comparing the predetermined reference value System comprising a. A human body communication system using chirp spread spectrum (CSS) modulation, A receiver for receiving a signal modulated by differential binary phase shift keying (DBPSK) modulation and chirp spread spectrum modulation, A band pass filter for performing band pass filtering on the received signal; A mixer for synthesizing the band pass filtered signal and the signal delaying the band pass filtered signal by a predetermined time period; A low pass filter for performing low pass filtering on the synthesized signal, and A comparator for generating a predetermined output signal by comparing the low pass filtered signal with a predetermined reference value System comprising a. The method of claim 15, In the band pass filter unit, The center frequency and bandwidth of the pass band is determined with reference to the frequency band of the signal received by the receiver. The method of claim 15, In the mixer section, And the predetermined time is a time occupied by one bit of data. The method of claim 15, And the comparing unit outputs a first signal when the low pass filtered signal is greater than the predetermined reference value, and outputs a second signal when the low pass filtered signal is smaller than the predetermined reference value.

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