KR101352404B1 - Visible light communication device and method for controlling the same - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to improve a visible light communication device and a control method thereof, by dividing a bit length of a data signal into an arbitrary length and improving light efficiency with respect to power by adjusting the bit length of the data signal according to brightness of illumination. . To this end, a 1-bit signal having an arbitrary pulse width is divided into arbitrary numbers so as to have an equal length, and a pulse shorter by an arbitrary size than the total pulse width of the divided 1-bit signal or the total pulse width of the 1-bit signal. A signal generator for generating a pulse signal having a pulse width of any one of widths; And a modulator for modulating the pulse signal generated by the signal generator so that an on / off transition occurs at a predetermined period. Therefore, the bit length of the data signal is divided into an arbitrary length, and the bit length of the data signal is adjusted according to the brightness of the lighting, thereby improving the light efficiency compared to the power.

Description

Visible light communication device and its control method {VISIBLE LIGHT COMMUNICATION DEVICE AND METHOD FOR CONTROLLING THE SAME}

The present invention relates to a visible light communication apparatus and a control method thereof, and more particularly, to divide the bit length of a data signal into an arbitrary length, and to adjust the bit length of the data signal according to the brightness of an illumination to improve light efficiency compared to power. A visible light communication device and a control method thereof.

Visible wireless communication technology is a wireless communication technology that transmits information wirelessly using light in the visible wavelength band (380n to 780 nm range) that can be recognized by the human eye. This technology uses light in the visible wavelength band. Is distinguished from the existing wired optical communication technology.

Visible light wireless communication technology, unlike widely used RF (Radio Frequency) wireless communication, has excellent convenience, physical security, and user can see the communication link without any restriction or permission in terms of frequency use. It is distinguished by the fact that, among other things, there is a characteristic as a fusion technology that can simultaneously obtain the unique purpose and communication function of the light source.

On the other hand, in the digital visible light wireless communication system using the LED light source, since it is difficult for the receiver to detect information on the phase of the transmitted optical signal, the electrical data signals "0" and "1" are changed to the intensity of the visible light signal as shown in FIG. Modulation strength modulation method or OOK (On-Off Keying) modulation method is generally applied, which has the advantage of relatively simple configuration.

In addition, it has a coding block for mapping the digital signals "0" and "1" into signal waveforms of "0" and "1" defined by the system. According to the characteristics of the system, Non Return-to-Zero (NRZ), Coding techniques such as Return-to-Zero and Manchester are mainly used.

In the NRZ-OOK and Manchester-OOK coding and modulation methods, the average output of the optical signal output from the visible light source of the transmitter is stochastic that the number of data "1" and "0" is equally equal. This is the same as the light output when a signal of half the magnitude is constantly applied.

For example, as shown in FIG. 2, the 4B5B line code is a 4-bit transmission data changed to 5 bits, so that 4 bits can form 16 bit patterns, and 5 bits can form 32 bit patterns. Of the 32 patterns of 5 bits, only 16 patterns with many variations of "1" and "0" are selected and corresponded to the 4-bit transmission data pattern one-to-one to reduce the occurrence of "0" or "1". Can be.

 In this case, if the ratio of "1" and "0" per unit time is not constant, there is a problem that the user feels flicker by changing the brightness. As shown in FIG. 5 (a), "1" is 4 in the 5-bit pattern transmitted. If there is a pattern having one dog and one "0", and three ones, two "1" s, three "0s", etc. are mixed as shown in Fig. 5 (b), four "1s" are provided. , If the pattern of one "0" comes out in succession, the brightness of the light is 80%, but if the patterns of two "1" and three "0" are continuous, the brightness of the light is reduced to 40%. have.

In addition, when such a pattern is repeated, the LED light flickers, which is a serious problem in visible light wireless communication using the LED light.

In addition, as shown in Table 1, when data is coded as 4B6B, the light source is always turned on at 50% regardless of the data.

Source code 4B6B line cord 0 0000 001110 One 0001 001101 2 0010 010011 3 0011 010110 4 0100 010101 5 0101 100011 6 0110 100110 7 0111 100101 8 1000 011001 9 1001 011010 A 1010 011100 B 1011 110001 C 1100 110010 D 1101 101001 E 1110 101010 F 1111 101100

In other words, regardless of the data value, the ratio of "1" and "0" in the total of 6 bits becomes 3: 3 so that half of the lights can be turned on. .

In addition, when it is desired to change the brightness of the illumination, a PWM (Pulse Width Modulation) method of changing the length of the pulse width may be introduced as shown in FIG. 3.

However, such a prior art has a problem in that the light efficiency is lowered because only 50% of the total time is turned on. In addition, when PWM is applied, data “0” can clearly know the timing of synchronization. In the case of 1 ", the start position of the pulse signal is changed to cause a problem of Clock Data Recovery (CDR).

In order to solve this problem, the present invention divides the bit length of the data signal into an arbitrary length, and adjusts the bit length of the data signal according to the brightness of the illumination to improve the power efficiency of the visible light communication device and control method thereof The purpose is to provide.

In order to achieve the above object, the present invention provides a visible light communication device,
One bit signal having an arbitrary pulse width is divided into an arbitrary number so as to have an equal length, and among the pulse widths shorter than the total pulse width of the divided one bit signal or the total pulse width of the one bit signal, A signal generator for generating a pulse signal having any one pulse width; And a modulator for modulating the pulse signal generated by the signal generator to generate on / off transitions at regular intervals, wherein a pulse width shorter by the entire pulse width or an arbitrary size of the 1-bit signal depends on the brightness of the light source. Wherein the total pulse width of the one-bit signal is "1" of the data to be transmitted, and the pulse width shorter by any magnitude than the total pulse width of the one-bit signal is "0" of the data to be transmitted. It is done.

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In addition, the visible light communication apparatus according to the invention is characterized in that it further comprises an optical signal output unit for performing the visible light communication through the light source according to the signal modulated by the modulator.

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In addition, the present invention is a visible light communication device,

An optical signal receiver for receiving a visible light communication signal; A demodulator for demodulating the visible light communication signal received by the optical signal receiver; A timer that counts an arbitrary time that elapses after the rising edge is detected when the rising edge of the pulse signal is detected from the demodulated received signal; And outputting a control signal to operate the timer for a predetermined time when the rising edge of the pulse signal is detected from the demodulated received signal, and sampling on the received signal when the timer counted time reaches the predetermined time. And a signal analyzer configured to store the bit value of the pulse signal detected through the data packet in a preset format.

In addition, the sampling of the visible light communication apparatus according to the present invention is characterized in that the time interval between the total pulse width of the 1-bit signal and the average value of the pulse width shorter by an arbitrary size than the total pulse width of the 1-bit signal.

In addition, the signal analyzer according to the present invention is characterized in that when the reception of the data packet from the demodulated reception signal is completed, initialize the count time of the timer to any time.

In addition, the control method of the visible light communication apparatus according to the present invention comprises the steps of: a) a signal generator for receiving a transmission target data signal; b) the signal generator divides the number of 1-bit signals having an arbitrary pulse width into arbitrary numbers so that the signal has an equal length, and the total pulse width of the divided 1-bit signal is "1" of the data to be transmitted; A pulse width shorter than the total pulse width of the divided 1-bit signal generates a pulse signal having a "0" of the data to be transmitted, and the signal generator receives the brightness signal of the light source and applies it to the brightness signal of the light source. Adjusting the pulse width of the bit signal to increase or decrease accordingly; And c) modulating the pulse signal generated by the signal generator so that an on / off transition occurs at a predetermined period.

In addition, the control method of the visible light communication apparatus according to the invention is characterized in that it further comprises the step of performing the visible light communication through the light source in accordance with the signal modulated by the optical signal output unit modulator.

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In addition, the control method of the visible light communication apparatus according to the present invention includes the steps of: i) the optical signal receiving unit initializes the transmission period value for visible light communication, and when the visible light communication signal is received, the demodulator demodulates and outputs the received communication signal; ; ii) if the signal analyzer detects the rising edge of the pulse signal from the demodulated received signal, counting time until the timer reaches an arbitrary time after detecting the rising edge; iii) detecting the bit value of the pulse signal through sampling on the demodulated received signal after the counting of the timer, and storing the bit value of the pulse signal as a data packet having a preset format; And iv) analyzing the stored data packet to determine whether reception is completed, and terminating data reception or receiving additional data according to the determination result.

In addition, the sampling of step iii) according to the present invention is characterized in that the time interval between the total pulse width of the 1-bit signal and the average value of the pulse width shorter by an arbitrary size than the total pulse width of the 1-bit signal.

In addition, the step iv) according to the present invention is characterized in that when the reception of the data packet is completed, initialize the count time of the timer to any time.

The present invention has the advantage of dividing the bit length of the data signal into an arbitrary length, and improving the light efficiency to power by adjusting the bit length of the data signal according to the brightness of the illumination.

In addition, in the present invention, since "1" and "0" each have a probability of 50%, the effective average pulse width becomes the average value of the pulse width of "1" bit and the pulse width of "0" bit so that all data pulses are The advantage is that it can be synchronized and transmitted at regular intervals.

In addition, the present invention not only facilitates synchronization with the transmission apparatus at the time of reception, but also has the advantage that the bit rate, which is the transmission rate of transmission / reception data, can be greatly improved by changing the data only once in the data bit.

In addition, the present invention has the advantage that it is possible to minimize the power consumption through the prediction reception because it is possible to receive the prediction time of the sync pulse at the receiving side.

1 is a waveform diagram of modulating a data signal using a general NRZ-OOK.
2 is a waveform diagram of modulating a data signal using 4B5B according to the prior art.
Figure 3 is a waveform diagram showing a change in brightness of the illumination using PWM according to the prior art.
4 is a block diagram showing a configuration of a transmitter of a visible light communication apparatus according to the present invention;
5 is a waveform diagram showing a data signal according to an embodiment of the visible light communication apparatus according to the present invention;
6 is a waveform diagram showing a data signal according to another embodiment of the visible light communication apparatus according to the present invention;
7 is a block diagram showing the configuration of a receiver of a visible light communication apparatus according to the present invention;
8 is a flowchart illustrating an operation process of a transmitter of a visible light communication apparatus according to the present invention.
9 is a flowchart illustrating an operation process of a receiver of a visible light communication apparatus according to the present invention;

Hereinafter, a preferred embodiment of a visible light communication apparatus and a control method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

(Visible light communication device)

4 is a block diagram showing a configuration of a transmitter of a visible light communication apparatus according to the present invention, FIG. 5 is a waveform diagram showing a data signal according to an embodiment of the visible light communication apparatus according to the present invention, and FIG. 7 is a waveform diagram illustrating a data signal according to another embodiment of the visible light communication device, and FIG. 7 is a block diagram showing the configuration of a receiver of the visible light communication device according to the present invention.

As shown in FIG. 4 and FIG. 7, the visible light communication apparatus according to the present invention detects and demodulates the demodulated and decoded visible light communication signals output from the transmitter 100 and the transmitter 100 that modulate and output the data to be transmitted. And a receiver 200 for converting a signal into data having a predetermined format and outputting the signal.

The transmitter 100 converts the transmission target data input from any device into a signal having an arbitrary pulse width, modulates the converted signal, and outputs the converted signal as a visible light communication signal. The modulator 120 and the optical signal output unit 130 are configured.

The signal generator 110 divides the 1-bit signal having an arbitrary pulse width into an arbitrary number such that the 1-bit signal has an equal length and is larger than the total pulse width of the divided 1-bit signal or the total pulse width of the 1-bit signal. It generates a pulse signal having a pulse width of any one of pulse widths as short as an arbitrary magnitude.

As shown in Fig. 5, when the one-bit signal is, for example, a pulse signal having a pulse width of "15" in length, the pulse signal is divided into 15 equal parts so as to have a uniform width, and the total pulse width of the one-bit signal is shown. (Pulse Width = 15) is defined as the data signal "1", and the pulse width (PW = 14) shorter by an arbitrary size (for example, '1') than the total pulse width (PW = 15) of the 1-bit signal. Defines a data signal "0" to generate a pulse signal for visible light communication with respect to the data signal to be transmitted.

In addition, since the pulse width is closely related to the brightness of the illumination, when the data signal is transmitted in a state where the brightness of the illumination is darkened, as shown in FIG. 6, the pulse width is reduced, for example, the data signal "1" is the pulse width. A signal can be generated such that this is "2", and the data signal "0" can generate a signal such that the pulse width becomes "1".

Therefore, when a signal for controlling the brightness of the light source is input from the outside, the pulse width of the 1-bit signal is adjusted to adjust the minimum and maximum brightness by the light source.

The configuration of such a pulse signal has a 50% probability that the data signals " 1 " and " 0 " are respectively 50%. Therefore, the effective average pulse width is the average value of the pulse width of the data signal " 1 " In addition, since all data pulses of the data signals "1" and "0" are synchronized and transmitted at regular intervals, when the receiver 200 receives the visible light communication signal, synchronization with the transmitter 100 may be easily performed.

The modulator 120 modulates and outputs a pulse signal generated by the signal generator 110 so that an on / off transition occurs at every predetermined period T.

The optical signal output unit 130 is turned on or off so that visible light communication through the light source can be performed according to the signal modulated by the modulator 120 so that the optical signal is output.

The receiver 200 receives and demodulates a visible light communication signal transmitted from the transmitter 100, analyzes the demodulated signal, converts the demodulated signal into a data signal, and outputs the data signal. An optical signal receiver 210 and a demodulator 220 ), A timer 230 and a signal analyzer 240 are configured.

The optical signal receiver 210 detects and outputs a visible light communication signal output from the transmitter 100.

The demodulator 220 demodulates and outputs the visible light communication signal detected by the optical signal receiver 210 at a predetermined period T.

When the rising edge of the pulse signal is detected from the received signal demodulated from the demodulator 220, the timer 230 counts an arbitrary time that elapses after the rising edge is detected. It consists of either counter.

The count time by the timer 230 may be a predetermined count time or may be a count time transmitted from the transmitter 100.

When the rising edge of the pulse signal is detected from the received signal demodulated from the demodulator 220, the signal analyzer 240 outputs an operation control signal to cause the timer 230 to count up or down for a predetermined time. When the time counted by the timer 230 reaches the predetermined time, sampling is performed on the received signal.

The sampling is digitizing, and when the timer 230 reaches a certain time, the state of the received signal (pulse signal) at that moment is detected so that the bit value is determined.

That is, as shown in Figs. 5 and 6, for example, if a random voltage level is detected as a result of sampling at a sampling time on a received signal having an arbitrary period, the bit value is determined as the data signal " 1 " When a zero voltage is detected as a result of sampling at the sampling time of, the bit value is determined as the data signal "0".

The sampling is a time interval between the total pulse width of the 1-bit signal and the average value of the pulse widths shorter than the total pulse width of the 1-bit signal, that is, the pulse width of the data signal "1" and the data signal "0". Between the average value of the pulse widths.

In addition, the signal analyzer 240 stores the bit value of the detected pulse signal according to a data packet having a preset format. When the reception of the data packet is completed, the signal analyzer 240 stores a count time of a timer at an arbitrary time or a transmitter ( Initialize to the count time transmitted from 100).

That is, when the pulse width is changed due to the change in the brightness of the light source, the position of the sampling can be changed together according to the changed pulse width.

(Control method of visible light communication device)

8 is a flowchart illustrating an operation process of a transmitter of a visible light communication apparatus according to the present invention, and FIG. 9 is a flowchart illustrating an operation process of a receiver of a visible light communication apparatus according to the present invention.

4 to 9, a control method of a visible light communication apparatus according to the present invention includes a transmitting step in which the transmitter 100 modulates and outputs data to be transmitted, and a receiver 200 detects and demodulates a visible light communication signal. And a receiving step of converting the demodulated signal into data of a predetermined format and outputting the same.

The transmitting may include receiving a transmission target data signal (S100), receiving a brightness signal of a light source (S110), generating a pulse signal (S120), and modulating and outputting (S130).

In step S100, the signal generator 110 receives a transmission target data signal input by an external device.

In the step S110, when the signal generator 110 receives the brightness control signal of the light source input by the external device, the pulse width is increased or decreased by an arbitrary length so that the brightness of the light source is adjusted according to the received brightness signal of the light source. Adjust as much as possible.

In the step S120, the signal generator 110 divides the signal generator 110 into an arbitrary number so that the one-bit signal having the arbitrary pulse width or the pulse width adjusted in the step S110 has an equal length, and the entirety of the divided one-bit signal. A pulse signal having a pulse width of either one of a pulse width or a pulse width shorter than an entire pulse width of the 1-bit signal is generated.

In step S130, the pulse signal generated by the signal generator 110 is modulated such that an on / off transition occurs at a predetermined period T, and visible light communication is performed through the optical signal output unit 130 according to the modulated signal. To perform.

The receiving step may include initializing a transmission period (S200), demodulating a communication signal to output a received signal (S210), and sampling the received signal to detect a data signal (S220, S270). Include.

In step S200, when the optical signal receiver 210 receives a communication signal transmitted from the transmitter 100 when performing visible light communication, the optical signal receiver 210 initializes the signal to a predetermined transmission cycle value to demodulate the received signal.

In the step S210, when the optical signal receiver 210 receives the visible light communication signal, the demodulator 220 demodulates the received communication signal according to the transmission period and outputs a restored signal.

In step S220, it is determined whether a rising edge of a pulse signal is detected from the demodulated received signal. The rising edge detects a time point at which a data signal "1" or "0" starts.

When the rising edge of the pulse signal is detected, the steps S230 and S240 count down or up count time until the timer 230 reaches a predetermined time after detecting the rising edge.

The count time by the timer 230 may be a predetermined count time or may be a count time transmitted from the transmitter 100.

In step S250, after the timer is finished counting, the signal analyzer detects the bit value of the pulse signal through sampling on the demodulated received signal and stores the bit value of the pulse signal in a data packet having a preset format. It is made in the time interval between the average values of the pulse widths which are shorter by an arbitrary magnitude than the total pulse width of the 1-bit signal.

Steps S260 and S270 analyze the stored data to determine whether reception is completed, and perform step S210 to end data reception or to receive an additional data signal according to the determination result.

On the other hand, in step S260, when the reception of the data packet is completed, by initializing the count time of the timer to a predetermined time or a count time transmitted from the transmitter 100, the sampling position when the pulse width is changed due to the change in the brightness of the light source Can be changed together according to the changed pulse width.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It can be understood that

100 transmitting unit 110 signal generating unit
120: modulator 130: optical signal output unit
200: receiver 210: optical signal receiver
220: demodulator 230: timer
240: signal analysis unit

Claims (13)

delete delete delete delete An optical signal receiver for receiving a visible light communication signal;
A demodulator for demodulating the visible light communication signal received by the optical signal receiver;
A timer that counts an arbitrary time that elapses after the rising edge is detected when the rising edge of the pulse signal is detected from the demodulated received signal; And
When the rising edge of the pulse signal is detected from the demodulated received signal, a control signal is output so that the timer is operated for a predetermined time, and the time counted by the timer reaches the predetermined time so that the voltage level is detected on the received signal. And a signal analysis unit configured to determine the bit value data signal "1" and to determine the bit value as the data signal "0" when the zero voltage is detected, and to store the data value in a data packet having a preset format.
Sampling takes place in a time interval between the full pulse width of the 1-bit signal and the average value of the pulse width shorter than the full pulse width of the 1-bit signal. And initializing the counted time so that the sampling position changes according to the changed pulse width when the pulse width changes due to the change in the brightness of the light source.
delete delete delete delete delete i) demodulating and outputting the received communication signal by a demodulator when the optical signal receiver initializes a transmission period value for visible light communication and receives a visible light communication signal;
ii) if the signal analyzer detects the rising edge of the pulse signal from the demodulated received signal, counting time until the timer reaches an arbitrary time after detecting the rising edge;
iii) If the time counted by the timer reaches the predetermined time after the end of the counting of the timer, the signal analyzing unit pulse width shorter by an arbitrary size than the total pulse width of the 1-bit signal and the total pulse width of the 1-bit signal. Sampling is performed in a time interval between the average values of and when the voltage level is detected on the received signal, the signal analyzer determines the bit value data signal "1", and when the zero voltage is detected, converts the bit value into the data signal "0". Determining and storing the data packet in a predetermined format; And
iv) analyzing the stored data packet to determine whether the reception is completed, and when the reception of the data packet is completed, terminates the data reception and initializes the time counted by the timer. And when the position of the sampling is changed according to the changed pulse width, and receiving the additional data if the reception is not completed. delete delete

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