KR20130085490A - Method of visible light communication between vehicles using inverted signal and apparatus for the same - Google Patents

Abstract

PURPOSE: A visible light wireless communication method using inverted signals and a device for the same are provided to be applied to communication between vehicles having high external noises and far communication distances using both lamps of a vehicle as two conductive wires in a differential signal mode. CONSTITUTION: A pulse width modulation (PWM) section determination unit (1320) determines the length of an additional PWM section based on brightness information corresponding to headlight, tail light, and brake light from a bright information providing unit (1390) corresponding to a central control unit of a vehicle. A left signal transmission unit (1330) and a right signal transmission unit (1340) generate a transmission signal which is generated by synthesizing a data signal and a PWM signal based on a received data signal and PWM section length information received from the PWM section determination unit. The generated transmission signal is transmitted from a left LED emitting unit (1360) and a right LED emitting unit (1370) according to a signal from a transmission timing determination unit (1350) in order to prevent a transmission timing error. [Reference numerals] (1310) Inverse data signal generation unit; (1320) PWM section determination unit; (1330) Left signal transmission unit; (1340) Right signal transmission unit; (1350) Transmission timing determination unit; (1360) Left LED emitting unit; (1370) Right LED emitting unit; (1380) Transmission data providing unit; (1390) Bright information providing unit; (AA) Data section length calculation unit; (BB) Data section brightness calculation unit; (CC) PWM section length calculation unit; (DD,FF) Data and PWM signal synthesizing unit; (EE,GG) Data and PWM signal transmission unit

Description

Visible vehicle wireless communication method using inverted signal and apparatus therefor {METHOD OF VISIBLE LIGHT COMMUNICATION BETWEEN VEHICLES USING INVERTED SIGNAL AND APPARATUS FOR THE SAME}

The present invention relates to a visible light wireless communication technology, and more particularly, to a visible light wireless communication method and apparatus that can communicate even in the daytime with a lot of external noise (ambient light) using the LED light and the differential signal method used in a vehicle. .

Visible light is a light ray having a wavelength in a range visible to the human eye among electromagnetic waves and corresponds to a wavelength of 380 nm to 780 nm. Within visible light, the change in properties along with wavelength is represented by each color, and the wavelength becomes shorter from red to violet. Light with a longer wavelength than red is called infrared, and light with a shorter wavelength than purple is called ultraviolet. For monochromatic light, 700nm to 610nm is red, 610nm to 590nm is orange, 590nm to 570nm is yellow, 570nm to 500nm is green, 500nm to 450nm is blue, and 450nm to 400nm is purple. Various colors can be realized by mixing colors of each wavelength.

Visible light, unlike ultraviolet or infrared light, is visible to humans, and the light that emits light has various requirements such as accurate color representation. One of them should be no flickering. However, since humans cannot recognize more than 200 flashes per second, lighting using the LED is blinking using pulse width modulation (PWM) using the fast blinking performance of the LED.

Visible light wireless communication is a wireless communication technology using a wavelength between 380 nm and 780 nm in the visible region, which is similar to infrared communication, but uses a different wavelength range. The communication technology using light in the communication area includes infrared data wireless communication (IrDA) using infrared light, visible light wireless communication using visible light, optical communication using optical fiber, and the like.

Infrared Data Association (IrDA) is a private standards body established in 1993 to establish standards for infrared data communications, but is commonly used as a term for communications standards set by IrDA. The main specifications used in personal computers are IrDA1.0 with a maximum data transfer rate of 2.4-115.2kbps and IrDA1.1 with 1.152Mbps and 4Mbps. This infrared communication is a technology for communicating using the infrared region having a wavelength of 850nm ~ 900nm described above.

Visible light communication is a communication technology using wavelengths in the range of 380nm to 780nm, and standardization is under way from IEEE 802.15 Wireless Personal Area Network (WPAN) to Study Group, and a visible light wireless working group is operated by Korea Information and Communication Technology Association (TTA). In the process.

Several modulation schemes have been proposed and tested for visible light wireless communication. Typically, there is On-Off Keying (OOK). OOK indicates '1' when the signal is high, '0' when low, or vice versa, '0' when high, and '1' when low. Modulation method shown. This OOK method is also a method commonly used in optical communication because the OOK signal can be switched to the flashing of light. In addition, Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), and Sub-Carrier 4PPM (SC-4PPM) incorporating a carrier wave into a PPM signal have been tested to find a modulation method for visible light wireless communication.

In the method of controlling the brightness of LED lighting, a simple variable resistor is used to change the amount of current flowing through the LED by changing the voltage applied to the resistor. There are many ways to adjust. In lighting equipment using LEDs, the brightness of the lighting is controlled using pulse width modulation (PWM), which provides the highest efficiency and the most precise current control. The pulse width modulation method adjusts the ratio of the signal on / off, and adjusts the brightness of the light by controlling the time when the LED light is turned on. In other words, the longer the time turned on per unit time, the LED light is bright light, the shorter the principle is dark. The pulse width modulation method is a modulation method for originally digital communication, and is also a modulation method in which information is transferred in a duty cycle of a signal.

Visible light wireless communication technology includes VPPM (Variable PPM) technology that allows communication and dimming at the same time. This technique enables simultaneous communication and dimming by varying the length of the intervals that are turned on in a symbol in the PPM.

On the other hand, most electrical signals are single-ended and consist of a single conductor (signal line) and ground. The differential signal uses two wires that are opposite to each other. When one wire swings to the positive pole, the other wire swings to the negative pole of the same size. The receiving circuit responds only to the voltage difference between the two leads and ignores the common mode voltage. This approach reduces the effects of external electrical interference. Because noise affects both leads equally, common mode rejection also ignores that noise.

SUMMARY OF THE INVENTION An object of the present invention is to provide a visible light wireless communication method and apparatus suitable for inter-vehicle communication having a lot of external noise (ambient light) and having a long communication distance by utilizing both left and right lamps of a vehicle as if they are two wires of a differential signaling method. will be.

In addition, an object of the present invention is to enable efficient visible light communication while maintaining the brightness change function that the vehicle lamp must implement.

In the vehicle-to-vehicle visible light communication method of the visible light wireless communication transmitter installed in a vehicle according to the present invention for achieving the above object, generating the first transmission data transmitted through any one of the left lamp and the right lamp of the vehicle; ; Inverting the first transmission data to generate second transmission data transmitted through the other of the left ramp and the right ramp; And simultaneously transmitting visible light wirelessly through the left lamp and the right lamp through the first transmission data and the second transmission data.

In addition, in the vehicle-to-vehicle visible light communication method of the visible light wireless communication receiver installed in a vehicle according to an embodiment of the present invention, respectively, the first received signal and the second received signal received from the left lamp and the right lamp of the transmitting vehicle Making; Generating an inverted signal by inverting any one of the first and second received signals; And generating a reconstruction signal by combining the inverted signal with another one of the first and second received signals.

According to the present invention, by using both the left and right lamps of the vehicle as if the two conductors of the differential signal method, it is possible to provide a visible light wireless communication method and apparatus suitable for communication between vehicles with a lot of external noise (ambient light) and a long communication distance Can be.

In addition, the present invention enables efficient visible light communication while maintaining the brightness change function that the vehicle lamp must implement.

1 is a waveform diagram illustrating a left lamp transmission signal and a reception signal of a visible light wireless communication method according to an exemplary embodiment of the present invention.
2 is a waveform diagram illustrating a right lamp transmission signal and a reception signal of the visible light wireless communication method according to an exemplary embodiment of the present invention.
3 is a waveform diagram illustrating a reception inversion signal inverting the right ramp reception signal illustrated in FIG. 2.
4 is a waveform diagram illustrating a signal in which a DC component is removed from a left ramp reception signal shown in FIG. 1 and a reception inversion signal shown in FIG. 3.
FIG. 5 is a waveform diagram of a reconstruction signal generated by combining a left ramp reception signal and a reception inversion signal illustrated in FIG. 4.
6 is a waveform diagram illustrating a left ramp transmission signal and a reception signal in consideration of a PWM section and an OFF section for brightness correction in addition to transmission data.
7 is a waveform diagram illustrating a right ramp transmission signal and a reception signal in consideration of a PWM section and an OFF section for brightness correction in addition to transmission data.
FIG. 8 is a waveform diagram illustrating a reception inversion signal inverting the right lamp reception signal shown in FIG. 7.
FIG. 9 is a waveform diagram illustrating a signal in which a DC component is removed from a left ramp reception signal illustrated in FIG. 6 and a reception inversion signal illustrated in FIG. 8.
FIG. 10 is a waveform diagram of a reconstruction signal generated by combining a left ramp reception signal and a reception inversion signal illustrated in FIG. 9.
FIG. 11 is a block diagram illustrating an operation of a transmitting side of an inter-vehicle visible light wireless communication method according to an exemplary embodiment of the present invention.
12 is a block diagram illustrating an operation of a receiving side of a method for visible light wireless communication between vehicles according to an embodiment of the present invention.
13 is a block diagram illustrating an inter-vehicle visible light wireless communication transmitter according to an embodiment of the present invention.
14 is a flowchart illustrating an operation of a transmitting side of a method for visible light wireless communication between vehicles according to an embodiment of the present invention.
15 is a block diagram illustrating an inter-vehicle visible light wireless communication receiver according to an embodiment of the present invention.
16 is a flowchart illustrating an operation of a receiving side of an inter-vehicle visible light wireless communication method according to an exemplary embodiment of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Lamps are mounted on the left and right sides of the vehicle, respectively. The present invention uses each of the left and right lamps as differential signal wires opposite to each other in the differential signaling method to provide a visible light communication technique that is resistant to noise by utilizing the advantages of the differential signaling method without compromising the characteristics of the vehicle lamp. Can be.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a waveform diagram illustrating a left lamp transmission signal and a reception signal of a visible light wireless communication method according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the left lamp transmission signal 110 of the visible light wireless communication method according to an embodiment of the present invention is received as a left lamp received signal 120 through a visible light wireless communication channel. In this case, a DC offset including channel noise may be added to the left ramp receiving signal 120.

The left ramp transmission signal 110 may be regarded as a reference signal corresponding to a positive signal among differential signals. For example, the reference signal is based on OOK modulation type visible light wireless communication, when the data is '0' LED of the lamp is turned off (OFF) and when the LED of the lamp may be turned on (on).

2 is a waveform diagram illustrating a right lamp transmission signal and a reception signal of the visible light wireless communication method according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the right lamp transmission signal 210 of the visible light wireless communication method according to an embodiment of the present invention is received as the right lamp received signal 220 at a receiver of a rear vehicle through the visible light wireless communication channel. In this case, a DC offset including channel noise may be added to the right ramp receiving signal 220.

The right ramp transmission signal 210 may be viewed as an inverted signal corresponding to the negative signal among the differential signals.

In a differential signal, the anode swings from one lead to the cathode on the other, but cathode swings are not possible in visible light wireless communications using LED lamps.

Therefore, the right lamp transmission signal 210 may be inverted only the signal level of the reference signal of the left lamp.

For example, if the reference signal is the OOK modulation type visible light wireless communication, if the data is '0', the LED of the lamp is off (OFF) and if the LED of the lamp is on (On), the inverted signal When the data is '1' the LED is off (OFF) and when the '0' LED of the lamp can be turned on (On).

3 is a waveform diagram illustrating a reception inversion signal inverting the right ramp reception signal illustrated in FIG. 2.

Referring to FIG. 3, it can be seen that in order to obtain the same principle as the differential signal, the right lamp receiving signal in which data is inverted and transmitted is inverted to a cathode based on a common line.

4 is a waveform diagram illustrating a signal in which a DC component is removed from a left ramp reception signal shown in FIG. 1 and a reception inversion signal shown in FIG. 3.

Referring to FIG. 4, when the DC component is removed from the left ramp received signal and the received inverted signal, the waveforms are almost the same.

FIG. 5 is a waveform diagram of a reconstruction signal generated by combining a left ramp reception signal and a reception inversion signal illustrated in FIG. 4.

Referring to FIG. 5, it can be seen that the left ramp reception signal and the reception inversion signal are signal added to generate a recovery signal resistant to noise.

In addition to the fact that LED lamps are not capable of cathode swings, the factor to be considered in vehicular visible light wireless communication is that the vehicular lamps must be capable of varying brightness.

The taillight of the vehicle requires two levels of brightness: a taillight for night driving and a brake light that is brighter than the taillight to indicate braking. The present invention should also be designed in consideration of such brightness level in order to be utilized in visible light communication through the rear light of the vehicle.

6 is a waveform diagram illustrating a left ramp transmission signal and a reception signal in consideration of a PWM section and an OFF section for brightness correction in addition to transmission data.

Referring to FIG. 6, it can be seen that the transmission and reception signals include not only a data section 610 but also a PWM section 620 and an OFF section 630 for brightness correction.

That is, by reducing the brightness by minimizing the PWM section 620 and maximizing the OFF section 630 in the taillight state, by increasing the brightness by maximizing the PWM section 620 and minimizing the OFF section 630 in the brake light state It can provide two levels of brightness.

7 is a waveform diagram illustrating a right ramp transmission signal and a reception signal in consideration of a PWM section and an OFF section for brightness correction in addition to transmission data.

Referring to FIG. 7, it can be seen that the transmit and receive signals include a PWM section 720 and an OFF section 730 for brightness correction as well as a data section 710.

In other words, the brightness is reduced by minimizing the PWM section 720 and maximizing the OFF section 730 in the taillight state, and increasing the brightness by maximizing the PWM section 720 and minimizing the OFF section 730 in the brake lamp state. It can provide two levels of brightness.

As can be seen from FIGS. 6 and 7, the signals of the data section are inverted from each other in the left / right ramps (DATA, DATA '), but the signals of the PWM section and the OFF section are not inverted from each other in the left / right ramps. The same applies, so that the receiver is automatically removed according to the principle of the differential signal to enable efficient data recovery.

FIG. 8 is a waveform diagram illustrating a reception inversion signal inverting the right lamp reception signal shown in FIG. 7.

Referring to FIG. 8, it can be seen that in order to obtain the same principle as the differential signal, the right lamp receiving signal in which data is inverted and transmitted is inverted to a cathode based on a common line.

FIG. 9 is a waveform diagram illustrating a signal in which a DC component is removed from a left ramp reception signal illustrated in FIG. 6 and a reception inversion signal illustrated in FIG. 8.

Referring to FIG. 9, when the DC component is removed from the left ramp reception signal and the reception inversion signal, the waveforms are the same in the data section, and the waveforms are half-fixed in the PWM section and the OFF section.

FIG. 10 is a waveform diagram of a reconstruction signal generated by combining a left ramp reception signal and a reception inversion signal illustrated in FIG. 9.

Referring to FIG. 10, the left ramp reception signal and the reception inversion signal are signal added to generate a signal that is strong against noise in the data section, and the signals of the PWM section and the OFF section correspond to the left / right ramps. It can be seen that is canceled by canceling.

FIG. 11 is a block diagram illustrating an operation of a transmitting side of an inter-vehicle visible light wireless communication method according to an exemplary embodiment of the present invention.

Referring to FIG. 11, in the preceding vehicle, a PWM signal for generating two-stage brightness adjustment to the reference signal 1120 is generated as a reference signal 1120 in the transmission data 1110 to be transmitted. To generate a left signal 1140.

In addition, in the preceding vehicle, the reference signal 1120 is inverted and converted into an inverted signal 1150, and the right signal 1170 is synthesized 1160 by providing a PWM signal for providing two-step brightness control to the converted inverted signal 1150. )

12 is a block diagram illustrating an operation of a receiving side of a method for visible light wireless communication between vehicles according to an embodiment of the present invention.

Referring to FIG. 12, the transmitted left and right signals are received by the left and right receivers in the rear vehicle to generate the received left signal 1210 and the received right signal 1220.

In this case, the left and right receivers may separately receive the left and right received signals by not only increasing the strength of the received signal by using a condenser lens but also narrowing the angle of the received signal.

The received right signal 1220 performs signal inversion 1230, and the received left signal 1210 performs a delay correction 1240 to adjust the timing of the left and right signals. Signal processing and signal removal 1250 are performed on the processed signals, respectively, and data restoration 1260 is possible.

13 is a block diagram illustrating an inter-vehicle visible light wireless communication transmitter according to an embodiment of the present invention.

Referring to FIG. 13, the inter-vehicle visible light wireless communication transmitter according to an exemplary embodiment of the present invention includes an inverted data signal generator 1310, a PWM section determiner 1320, a left signal transmitter 1330, a right signal transmitter 1340, A transmission timing determiner 1350, a left LED light emitter 1360, a right LED light emitter 1370, a transmission data provider 1380, and a brightness information provider 1390 are included.

The transmission data provided from the transmission data providing unit 1380 becomes a reference signal and is sent to the left signal transmitter 1330 and the inversion data signal generator 1310, and also the PWM interval determiner 1320 to calculate the length of the PWM interval. Is sent to.

The PWM section determiner 1320 receives the data to be transmitted, calculates the length and the brightness of the data section, and brightness information corresponding to the lights, taillights, brake lights, etc. from the brightness information providing unit 1390 corresponding to the central control unit of the vehicle. Based on this, the additional PWM section length is determined.

The left signal transmitter 1330 and the right signal transmitter 1340 synthesize the data signal and the PWM signal based on the received data signal (reference signal or inversion signal) and the PWM section length information received by the PWM section determiner 1320. Generate a transmit signal.

The generated transmission signal is simultaneously transmitted from the left LED light emitting unit 1360 and the right LED light emitting unit 1370 in accordance with the signal of the transmission timing determining unit 1350 to eliminate the transmission timing error at the transmitting end.

14 is a flowchart illustrating an operation of a transmitting side of a method for visible light wireless communication between vehicles according to an embodiment of the present invention.

Referring to FIG. 14, in a vehicle-to-vehicle wireless communication method according to an embodiment of the present invention, data to be transmitted is received (S1410).

In addition, the vehicle-to-vehicle visible light communication method according to an embodiment of the present invention receives the output brightness information (S1420).

The left transmitting end calculates the length of the transmission data (S1440) and calculates the brightness of the transmission data (S1460). Based on the brightness information of the transmission data, the PWM interval length for adjusting the output brightness level is calculated (S1480), and the calculated PWM is combined with the transmission data and ready for transmission (S1491).

The transmission data received in step S1410 is inverted to obtain the same principle as the differential signal (S1430).

Data inversion can be easily performed by replacing '1' and '0' with '0' and '1'.

The right transmitting end calculates the length of the inverted transmission data (S1450) and calculates the brightness of the inverted transmission data (S1470). Based on the brightness information of the inverted transmission data, the PWM interval length for adjusting the output brightness level is calculated (S1490), and the calculated PWM is combined with the inverted transmission data and ready for transmission (S1492).

When the left data and the right data are ready, it is determined whether to start the transmission (S1493). When the transmission starts, the left / right signal is transmitted at the same time (S1494) and it is determined whether there is no more data to be transmitted (S1495). If it does not remain, the transmission ends.

15 is a block diagram illustrating an inter-vehicle visible light wireless communication receiver according to an embodiment of the present invention.

Referring to FIG. 15, an inter-vehicle visible light wireless communication receiver according to an embodiment of the present invention includes a signal receiver 1510, a reception signal manipulator 1520, and a reception data restorer 1530.

The signal receiver 1510 of the receiving end separately receives the left received signal and the right received signal.

The received signal manipulator 1520 may include a delay corrector, a signal inverter, a signal synthesizer, and a noise remover.

The signal received on the left side is delayed by the delay corrector of the reception signal manipulator 1520, and the signal received on the right side is signal inverted by the signal inverter of the received signal manipulator 1520. Each processed signal is subjected to signal combining and noise removal in the signal synthesizing and noise removing unit, and the final data is restored by the reception data restorer 1530 using the synthesized signal.

16 is a flowchart illustrating an operation of a receiving side of an inter-vehicle visible light wireless communication method according to an exemplary embodiment of the present invention.

Referring to FIG. 16, in a vehicle-to-vehicle visible light communication method according to an embodiment of the present invention, a left signal and a right signal are received (S1610 and 1620).

The received left signal is removed through the delay correction (S1630) (S1650) (S1650).

The received right signal is removed through the signal inversion (S1640) (S1660) (S1660).

The left / right signal from which the DC component has been removed is obtained through the signal synthesis (S1670) to remove noise and obtain a data signal with stronger signal strength. Data is extracted from the data signal whose signal strength is increased (S1680).

The above operation is determined whether all the data has been received (S1690) and if not all the data is received is repeated repeatedly.

In the above description, the present invention has been described with reference to an example in which a reference signal is transmitted to a left lamp of a vehicle and a differential signal is transmitted to a right lamp. However, the left lamp and the right lamp may be interchanged.

As described above, the inter-vehicle visible light wireless communication method and apparatus according to the present invention is not limited to the configuration and method of the embodiments described as described above, the embodiments are implemented so that various modifications can be made All or part of the examples may be optionally combined.

1310: Invert data signal generator
1320: PWM range determiner
1330: left signal transmitter
1340: right signal transmitter
1350: transmission timing determining unit
1360: left LED light emitting part
1370: right LED light emitting part
1380: transmission data provider
1390: brightness information provider

Claims (1)

In a visible light wireless communication method between vehicles of a visible light wireless communication transmitter installed in a vehicle,
Generating first transmission data transmitted via one of a left lamp and a right lamp of the vehicle;
Inverting the first transmission data to generate second transmission data transmitted through the other of the left ramp and the right ramp; And
Simultaneously transmitting the first transmission data and the second transmission data to the visible light via the left lamp and the right lamp;
In-vehicle visible light wireless communication method comprising a.

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