KR20110124104A - Method and apparatus for changing data encoding in visible light communications - Google Patents

Abstract

PURPOSE: A data coding change method and apparatus thereof are provided to smoothly perform data transmission in consideration of neighboring illumination according to visible light communication. CONSTITUTION: A controlling unit(312) controls an encoder(313) and a decoder(318) in order to process data through a first coding method or a second coding method. The second coding method is a method for controlling the brightness of output visible light. The controlling unit changes a data coding method.

Description

METHOD AND APPARATUS FOR CHANGING DATA ENCODING IN VISIBLE LIGHT COMMUNICATIONS}

The present invention relates to a visible light communication system, and more particularly, to a method and apparatus for changing a coding scheme for data transmission in a visible light communication system.

Recently, as the luminous efficiency of LED (Light Emitting Diode) is improved and the price is lowered, LED is becoming popular in general lighting market such as fluorescent incandescent lamp as well as special lighting market such as mobile device, display, automobile, traffic light, billboard. have. Recently, due to the depletion of RF (Radio Frequency) band frequency, the possibility of crosstalk between various wireless communication technologies, the increased demand for security of communication, and the arrival of ultra-high ubiquitous communication environment of 4G wireless technology, With increasing interest, research on visible light wireless communication using visible light LED is being conducted in various companies and research institutes.

By modulating the current applied to the LED used as lighting, the lighting LED can be utilized as a communication light source. In other words, broadcasting and data transmission are possible using only illumination LEDs without additional light sources. Referring to the configuration of the visible light communication system using the general visible light communication (VLC) as shown in FIG. As shown in FIG. 1, a general visible light communication system includes an LED or a laser diode (LD) and includes a light source 100 and a visible light transmitting / receiving module that perform data transmission and reception using visible light at the same time as lighting. It is configured to include a visible light communication terminal 110 for performing data transmission and reception 100. The visible light communication terminal 110 may include a mobile terminal such as a mobile phone or a PDA or a fixed terminal in the form of a desktop. The light source 100 may also be coupled to a monitor of a television as well as lighting. In addition, visible light communication can be used more efficiently in combination with communication systems using other communication media, wired and wireless.

In addition, data transmission and reception using visible light may be performed between the visible light communication terminal A 120 and the visible light communication terminal B 130.

On the other hand, since the visible light communication transmits and receives through a light source that can be recognized by the user, the intensity of the light source should be stable so as not to tired the user's eyes. Although the user can visually check the transmission and reception of data through a light source such as an LED / LD of a monitor such as a television, the DC representing the appropriate amount of change of 0 and 1 signals required for data to be transmitted or synchronized at a low speed. (Direct Current) Flickering may occur when the balance is out of balance. As described above, 0 and 1 serve to provide clock information to a PLL (Phase Locked Loop) of a receiver as a change boundary of data. However, when the user experiences such flickering, the user not only feels tired eyes but also significantly reduces the effect of visible light communication, which is visible communication. In order to keep sync while preventing or reducing such flickering, it is necessary to uniformly configure on / off characteristics, that is, bit 1 and 0 ratios.

Therefore, in the system using visible light communication, a number of coding techniques are used to make the ratio of 0 and 1 constant during data transmission. For example, 2B4B coding or 8B10B coding.

The 2B4B coding scheme converts a 2-bit input into a 4-bit output, whereby the number of 1s and 0s constituting the 4 bits can be adjusted appropriately.

The 8B10B coding scheme converts an 8-bit input into a 10-bit output. An example of such an 8B10B coding method is illustrated in FIG. 2. FIG. 2 illustrates a method of determining output 10 bits for input 8 bits by configuring 3B4B and 5B6B in parallel in the process of making 8B10B. The first encoding table 201 illustrates a method of outputting 4-bit portions corresponding to 3 bits by separating 3 bits and 5 bits from an 8-bit input. The second encoding table 203 illustrates a method of outputting 6-bit portions corresponding to 5 bits by separating 3 bits and 5 bits from an 8-bit input. Looking at the uniformity of the rate of change of the signals 0 and 1 in the 4-bit output of the first encoding table 201, the ratio of 0 and 1 is 2: 2, which accounts for 50% and the remainder is 0 and 1 It can be seen that this is 3: 1 or 1: 3. In the 4-bit output of the second encoding table 203, when the ratio of 0 and 1 is 3: 3, it occupies 56%.

Since visible light communication is a communication method for transmitting and receiving data using visible light, it affects the ambient light environment during communication. Therefore, there is a need for an adaptive transmission method capable of smoothly transmitting data while considering the influence on the ambient illumination during data transmission.

Accordingly, the present invention provides a method and apparatus for smoothly transmitting data while taking into consideration the ambient illumination caused by visible light communication.

The present invention also provides a method and apparatus for selectively using two or more coding schemes according to a communication environment.

Accordingly, the present invention provides a method of changing the data coding of a visible light communication apparatus, by processing data using any one of a first coding scheme and a coding scheme of a second coding scheme for adjusting brightness of output visible light for visible light communications. A process of transmitting and receiving, receiving a coding scheme change request message, and a coding scheme included in the coding scheme change request message is different from any one of the currently used coding schemes. Changing the data coding scheme.

In another aspect, the present invention provides a visible light communication device to process and transmit and receive data using any one of an encoder and a decoder, a first coding scheme, and a coding scheme of a second coding scheme for adjusting brightness of output visible light for visible light communications. A control unit for controlling the encoder and the decoder and changing the data coding scheme to the included coding scheme if the coding scheme included in the received coding scheme change request message is different from any one of the currently used coding schemes. It includes.

The present invention allows the data transmission to be performed smoothly while taking into consideration the ambient illumination caused by visible light communication. In addition, the present invention allows two or more coding schemes to be selectively used according to a communication environment.

1 is a view showing the configuration of a general visible light communication system,
2 illustrates an 8B10B data coding scheme,
3 is a view showing the configuration of a visible light communication apparatus according to an embodiment of the present invention;
4 to 7 are views showing the operation of the visible light communication apparatus according to the embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and an operation method of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific matters such as specific elements are shown, which are provided to help a more general understanding of the present invention. It is self-evident to those of ordinary knowledge in Esau. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Visible light communication transmits and receives through visible light that can be perceived by the user, so the light intensity must be stable so that the user's eyes are not tired. However, flickering may occur when data is transmitted at a low speed or when a direct current (DC) balance indicating a change rate of a signal of 0 and 1 that is necessary for synchronizing is not balanced. However, when the user experiences such flickering, the user not only feels tired eyes but also significantly reduces the effect of visible light communication, which is visible communication. In order to keep sync while preventing or reducing such flickering, it is necessary to uniformly configure on / off characteristics, that is, bit 1 and 0 ratios. Accordingly, in the system using visible light communication, various coding schemes capable of keeping a ratio of 0 and 1 during data transmission are used. For example, 2B4B coding or 8B10B coding.

In addition, since visible light communication is a communication method for transmitting and receiving data using visible light, it affects the ambient light environment during communication. Therefore, the data transfer should be considered at the same time, and the data should be transmitted normally.

The present invention is to meet this need, and to use two or more coding schemes adaptively selected according to the communication environment. In other words, the present invention is one of a first coding technique which can easily adjust the brightness of the output visible light among the various coding techniques, and a second coding technique which randomly codes data without considering the brightness of the output visible light. Is appropriately selected and changed according to the communication environment, and data is transmitted and received according to the selected coding scheme. Accordingly, in an embodiment of the present invention, the 2B4B coding technique is used as the first coding technique for brightness adjustment and the 8B10B coding technique is used as the second coding technique for general coding.

Since the 8B10B coding technique converts an 8-bit input into a 10-bit output, the data processing speed is faster than that of the 2B4B coding technique.

Since 2B4B coding has fewer output bits than 8B10B coding, it is relatively easy to determine the output value considering the ratio of 1 and 0, and the classification of output values according to the ratio of 1 and 0 may be simpler. There is an advantage. In visible light communication, the ratio of 1 and 0 of the output value determines the brightness of visible light used in communication. Therefore, the brightness of the visible light may be adjusted step by step using the ratio of 1 and 0 of the output value. In the 2B4B coding scheme, the brightness of the visible light may be easily adjusted by classifying the output value according to the ratio of 1 and 0.

Accordingly, in one embodiment of the present invention, when setting the brightness adjustment mode to adjust the brightness of the visible light in the visible light communication using a 2B4B coding technique, it is not necessary to adjust the brightness of the output visible light, relatively fast data transmission 8B10B coding is used when setting the required general mode.

In addition, the present invention provides a message transmitted and received and the operation process of each device in order to enable the transmitting side visible light communication device and the receiving side visible light communication device to use the same coding scheme.

The 8B10B coding scheme converts an 8-bit input into a 10-bit output. An example of such an 8B10B coding method is illustrated in FIG. 2. 2 illustrates a method of determining 3 to 4 bits and 5 to 6B in parallel to determine an output 10 bit for an input 8 bit. The first encoding table 201 illustrates a method of outputting 4-bit portions corresponding to 3 bits by separating 3 bits and 5 bits from an 8-bit input. The second encoding table 203 illustrates a method of outputting 6-bit portions corresponding to 5 bits by separating 3 bits and 5 bits from an 8-bit input.

The 2B4B encoding method converts two input bits into four output bits, and there may be various definitions of four bits corresponding to two input values. In the present invention, since the 2B4B encoding method is used to adjust the brightness of visible light, 4 bits of output values are classified according to a ratio of 1 or 0, and the classified 4 bits of output values are defined by matching 2 bits of input values. For example, based on the number of 1s included in a 4-bit output, you can classify the output into 1 percent 25 percent, the 50 percent output, and the 75 percent output. Table 1 shows an example of the 2B4B coding matching table configured accordingly.

data Input value 00 01 10 11 Output value according to duty cycle 25% 0001 0010 0100 1000 50% 1001 0110 1100 0011 75% 1110 1101 1011 0111

In Table 1, the duty cycle is divided into 25 percent, 50 percent, and 75 percent, depending on the ratio of the output value to 1, and the 4-bit output value corresponding to each input value does not overlap. And the higher the inclusion ratio of 1 in the output value, the brighter the output visible light. Therefore, the brightness level of visible light can be adjusted by appropriately changing the duty cycle. For example, if you are displaying visible light at 50 percent brightness, encode the input into an output that corresponds to a 50 percent duty cycle. If we assume that the visible light is output at 37.5 percent of the brightness, we can encode it using 25 percent duty cycle and 50 percent duty cycle, enabling 37.5 percent brightness level adjustment. The 2B4B coding matching table as shown in Table 1 is stored in each visible light communication device.

Referring to Table 1, when the duty cycle is 25 percent, input bit '00' becomes encoder output '0001'. In addition, the receiving side visible light communication device detects that the original bit is '00' by searching the received bit '0001' in Table 1 even if there is no information on the duty cycle used by the transmitting side visible light communication device.

3 illustrates a configuration of a visible light communication device performing visible light communication according to the present invention using the above-described 2B4B coding technique and 8B10B coding technique.

Referring to FIG. 3, the visible light communication device 300 includes a memory 311, a controller 312, an encoder 313, a modulator 314, a transmission driver 315, a light emitting diode (LED) 316, The decoder 318 includes a demodulator 319, a reception driver 320, and a photodiode (PD) 317.

The controller 312 processes data for data transmission and reception according to visible light communication, controls the encoder 313 and the decoder 318, and controls the overall operation of the visible light communication device 300.

The encoder 313 encodes the transmission data input from the controller 312 and outputs the encoded data to the modulator 314. The modulator 314 modulates the input transmission data and outputs the modulated transmission data to the transmission driver 315.

The output driver 315 is an LED 316 driver. The output driver 315 optically modulates transmission data input from the modulator 314 and drives the LED 316.

The LED 316 is a light emitting device provided to transmit transmission data to an external device using an optical signal and is driven by the output driver 315.

The photodiode 317 is a photosensitive device that senses an optical signal transmitted from an external device. The photodiode 317 receives an optical signal including received data from a light source, converts the optical signal into an electrical signal, and outputs the converted optical signal to the reception driver 320.

The reception driver 320 is a driver for the photodiode 321 and adjusts the wavelength detection band of the photodiode 317. The reception driver 320 outputs an electrical signal input from the photodiode 317 to the demodulator 319.

The demodulator 319 demodulates the electrical signal input from the reception driver 320 into data according to the optical wireless communication method, thereby outputting the received data to the decoder 318.

The decoder 318 decodes the received received data and outputs the received data to the controller 312, and the controller 312 appropriately processes the received data input from the decoder 318.

The memory 311 stores a program for processing and controlling the control unit 312, reference data, various kinds of updatable storage data, and the like, and is provided as a working memory of the control unit 312. In addition, according to the present invention, various reference data and program data for performing the 2B4B coding scheme and the 8B10B coding scheme are stored. For example, a coding matching table as shown in FIG. 2 or Table 1 may be stored. The controller 312 controls the encoder 313 and the decoder 318 using the coding matching table.

The memory 311 stores coding scheme selection criteria according to the present invention. Coding technique selection criteria are criteria for selecting any one of a first coding technique that can easily adjust the brightness of the output visible light and a second coding technique that can be used in a situation where the brightness of the output visible light is not needed. to be. For example, the coding scheme selection criterion may be a user's request for a specific technique, or may be a data transmission rate required in response to related data. Alternatively, the brightness of the output visible light may be required according to a communication environment.

The configuration of the visible light communication device 300 configured as described above is applicable to a base station including a light source and a communication control device as well as a visible light communication terminal. Each light source in the base station may be configured to include an LED 316 and a PD 317 in the visible light communication control device 300, or further include a transmit driver 315 and a receive driver 320, the communication The control device 200 can be configured to include the remaining components.

The visible light communication device configured as above changes the coding scheme adaptively to the communication environment. For example, if it is necessary to reduce flickering during data transmission, the controller 312 sets the 8B10B coding scheme and controls the encoder 313 and the decoder 318 to operate according to the 8B10B coding scheme. And if the brightness of the output visible light is above a certain brightness or below a certain brightness, the controller 312 sets the 2B4B coding scheme, so that the encoder 313 and decoder 318 can operate according to the 2B4B coding scheme. To control.

However, when the transmitting visible light communication device changes or newly sets a coding scheme, the receiving visible light communication device that receives the corresponding data may also decode the corresponding data only by using the changed coding technique. Accordingly, the transmitting side visible light communication terminal notifies the receiving side visible light communication device of the coding scheme to be changed before the coding scheme is changed, and the receiving side visible light communication device responds to the transmitting side visible light communication device whether to change the coding scheme. need.

To this end, the present invention is a DCC-REQ message (Duty Cycle Change Request Message) and DCC-RSP message (Duty Cycle Change) corresponding to the twelfth type and the thirteenth type among various management messages defined as shown in Table 2. Response Message).

Type Message name Message description 0 Null no management message One AS-REQ Association Request message 2 AS-RSP Association Response message 3 DAS-REQ Disassociation Request message 4 DAS-RSP Disassociation Response message 5 ARQ-FBK ARQ Feedback message 6 AS-ACK Association Acknowledge message 7 DAS-ACK Disassociation Acknowledge message 8 SLP-REQ Sleep Request message 9 SLP-RSP Sleep Response message 10 SLP-AREQ Aperiodic Sleep Request message 11 SLP-ARSP Aperiodic Sleep Response message 12 DCC-REQ Duty Cycle Change Request 13 DCC-RSP Duty Cycle Change Response 14-255 reserved for future use

The management message of Table 2 can be selected using an 8-bit type. According to an embodiment of the present invention, the DCC-REQ message corresponding to the 12th type is a message for requesting a coding scheme change, and the DCC-RSP message (Duty Cycle Change Response Message) corresponding to the 13th type is a coding scheme change. This is a message for reply. The request message and the response message are messages for changing the coding scheme from the 2B4B coding scheme to the 8B10B coding scheme or changing the coding scheme from the 8B10B coding scheme to the 2B4B coding scheme.

Table 3 below shows an example of the DCC-REQ message according to the present invention.

Syntax Size (bits) Description Management message type = 12 Duty Cycle Mode One 0: 8B10B
1: duty cycle to 2B4B Reserved 15 Shall be set to 0 on transmission and ignored upon reception

Referring to Table 3, a field value of a duty cycle mode field indicates a coding scheme to be used, where a field value of 0 means using an 8B10B coding scheme and a field value of 1 means using a 2B4B coding scheme. do. For example, if the coding is performed according to the 8B10B coding scheme, to maintain the 8B10B coding scheme, the duty cycle mode field value of the DCC-REQ message becomes bit 0, and the 2B4B coding scheme for adjusting the light source brightness is used. To change, the duty cycle mode field value is bit1.

Table 4 shows an example of the DCC-RSP message according to the present invention.

Syntax Size (bits) Description Management message type = 13 Approve One 0: approve to 8B10B
1: approve to 2B4B Reserved 15 Shall be set to 0 on transmission and ignored upon reception

In Table 4, the approve field is a field in which a value indicating whether to agree with the coding scheme requested by the DCC-REQ message is stored. According to an embodiment of the present invention, when the value of the grant field is '0', it means the use of the 8B10B coding scheme, and when the value of the grant field is '1', it means the use of the 2B4B coding scheme.

The coding scheme change request message and the coding scheme change response message may be stored in the memory 311 of each visible light communication device.

Hereinafter, a process of changing a coding scheme in a transmission / reception side visible light communication terminal according to an embodiment of the present invention will be described with reference to FIGS. 4 to 7.

4 and 5 illustrate a process of changing to 8B10B coding scheme for adjusting the light source brightness in a state in which each visible light communication device on the transmitting and receiving side codes and transmits data according to the 8B10B coding scheme. The operation process of the communication terminal is shown, and FIG. 5 shows the operation process of the receiving side visible light communication terminal.

Referring to FIG. 4, in step 401, the controller 312 of the visible light communication terminal synchronizes a coding scheme with a receiving side visible light communication device. This may be possible by using a predetermined default coding technique. The default coding scheme may be an 8B10B coding scheme or a 2B4B coding scheme according to an embodiment. In the following embodiment, the 8B10B coding scheme is assumed as the default coding scheme. Accordingly, in step 401, the controller 312 sets the fast transmission mode so that the encoder 313 and the decoder 318 can operate with the 8B10B coding scheme. In step 403, the controller 312 transmits 8B10B encoded data.

Thereafter, the controller 312 checks whether there is a request for using the brightness control mode. A request for using the brightness control mode may occur according to a user input, and a visible light output above a certain brightness or below a certain brightness may be required according to the current illumination condition. Alternatively, when the power of the visible light device is equal to or less than a predetermined value, it may occur when the visible light needs to be output at a specific brightness or less.

As such, when the use of the brightness control mode is requested in step 405, the controller 312 proceeds to step 407 in which a coding scheme change request message for requesting the coding scheme to be changed to the 2B4B scheme is requested to the receiving side visible light communication device, that is, DCC. Construct a REQ message. That is, when changing to the duty cycle mode during communication using 8B10B, set the field value of the duty cycle mode of the DCC-REQ message to bit '1' and proceed to step 409. A coding scheme change request message, that is, a DCC-REQ message is transmitted.

An operation of the visible light communication device that receives the DCC-REQ message configured as shown in FIG. 4 will be described with reference to FIG. 5. Referring to FIG. 5, in step 501, the controller 312 performs a transceiver synchronization process, and in step 503, receives data from the transmitter visible light communication device and decodes the received data according to the 8B10B coding scheme. do. Thereafter, in step 505, if a coding scheme change request is received by receiving a DCC-REQ message, the process proceeds to step 507. If the DCC-REQ message is analyzed in step 507 and the brightness control mode request is included, that is, if the bit value of the duty cycle mode field is '1', it is determined that the brightness control mode use request is included and the process proceeds to step 511. do. In step 511, the controller 312 changes the coding scheme to the 2B4B scheme. If the DCC-REQ message is checked in step 505 and the request for using the brightness control mode is not included, that is, if the bit value of the duty cycle mode field is '0', the process proceeds to step 509 to maintain the 8B10B coding scheme and step 513. Proceed to

In step 513, the controller 312 transmits a coding scheme response including a value representing a currently set coding scheme to the transmitting side visible light communication terminal. That is, if the 2B4B coding scheme is set, the value of the acknowledgment field of the DCC-RSP message is set to '1' and transmitted. If the 8B10B coding scheme is set, the acknowledgment field of the DCC-RSP message is set to '0'. Set to and send.

The transmitting side visible light communication device receives the coding scheme response, that is, the DCC-RSP message, confirms whether the receiving side visible light communication terminal has set the coding scheme according to the request, and finally changes the coding scheme.

Although not shown in FIG. 5, the receiving visible light communication apparatus may not support the 2B4B coding scheme or the 8B10B coding scheme, depending on the type. Alternatively, 2B4B coding or 8B10B coding may not be available depending on the communication environment. As such, the receiving visible light communication device may not be able to set a coding scheme included in the DCC-REQ message, and thus, the coding scheme finally set in the visible visible communication device is transmitted in the DCC-RSP message. .

6 and 7 illustrate a process for changing to 8B10B coding in a state in which a 2B4B coding scheme is set.

Referring to FIG. 6, in step 601, the controller 312 of the visible light communication terminal synchronizes a coding scheme with a receiving side visible light communication device. Synchronization at this time may be possible according to the transmission and reception of the DCC-REQ message and DCC-RSP message shown in FIG. 4 and FIG. In this embodiment, it is assumed to be synchronized with the 2B4B coding scheme. Accordingly, in step 601, the controller 312 sets the brightness control mode so that the encoder 313 and the decoder 318 can operate with the 2B4B coding technique. In operation 603, the controller 312 determines a brightness level. The brightness level may be determined according to the ambient light condition, the brightness of the requested output visible light, and the like. In operation 605, the controller 312 transmits 2B4B encoded data according to the determined brightness level.

In step 607, the controller 312 checks whether there is a general transmission mode request. The request to use the normal transmission mode may occur depending on user input, or may occur when it is no longer necessary to keep the brightness of the output visible light constant at a certain brightness.

As such, when a request for using the normal transmission mode is detected in step 607, the flow proceeds to step 609 to set the duty cycle mode field value of the DCC-REQ message to '0' so that the receiving side visible light communication terminal is changed to the 8B10B coding scheme. Constructs a coding scheme change request message. In step 611, the DCC-REQ message is transmitted to the visible visible light communication terminal.

The operation of the visible light communication device receiving the DCC-REQ message configured as shown in FIG. 6 will be described with reference to FIG. 7. Referring to FIG. 7, in step 701, the controller 312 performs a transceiver synchronization process, and in step 703, receives data from the transmitting visible light communication device and decodes the received data according to a 2B4B coding scheme. do. Thereafter, in step 705, if a coding scheme change request is received by receiving a DCC-REQ message, the flow proceeds to step 707.

In step 707, if the DCC-REQ message is analyzed and the general transmission mode use request is included, that is, if the bit value of the duty cycle mode field is '0', it is determined that the general transmission mode use request is included. do. In step 711, the control unit 312 changes the coding scheme to the 8B10B technique. If the DCC-REQ message is checked in step 707 and a request for using the brightness control mode is included, that is, if the bit value of the duty cycle mode field is '0', the method proceeds to step 709 to maintain the 2B4B coding scheme and proceeds to step 713. Proceed.

In step 713, the controller 312 transmits a coding scheme response including a value indicating a currently set coding scheme to the transmitting side visible light communication terminal. That is, if the 2B4B coding scheme is set, the value of the acknowledgment field of the DCC-RSP message is set to '1' and transmitted. If the 8B10B coding scheme is set, the acknowledgment field of the DCC-RSP message is set to '0'. Set to and send.

The transmitting side visible light communication device receives the coding scheme response, that is, the DCC-RSP message, confirms whether the receiving side visible light communication terminal has set the coding scheme according to the request, and finally changes the coding scheme.

In the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be defined by the equivalent of claims and claims.

Claims (20)

In the data coding change method of the visible light communication device,
Processing and transmitting and receiving data by using any one of a first coding technique and a second coding technique for adjusting the brightness of output visible light for visible light communication;
Receiving a coding scheme change request message;
If the coding scheme included in the coding scheme change request message is different from any one of the currently used coding schemes, changing the data coding scheme to the included coding scheme. How to change your coding. The data of claim 1, further comprising: constructing a coding scheme change response message including the type of the changed data coding scheme and transmitting the coding scheme change request message to the visible light communication device. How to change your coding. The method of claim 2, wherein the one coding scheme is the first coding scheme,
And when a coding scheme change request message for requesting a change to the second coding scheme is received, a data coding scheme is changed to the second coding scheme. The method of claim 2, wherein the one coding scheme is the second coding scheme,
And when a coding scheme change request message for requesting a change to the first coding scheme is received, a data coding scheme is changed to the first coding scheme. The method of claim 2, further comprising: detecting a change request occurrence to a coding scheme different from the currently set data coding scheme;
Constructing a coding change request message requesting to change to the other coding scheme and transmitting the same to a visible light communication device;
And when a coding change response message indicating that the other coding scheme is set is received from the corresponding visible light communication device, changing the data coding scheme to the other coding scheme. The data coding change of claim 5, wherein when the other coding scheme is the second coding scheme, a change request to the other coding scheme occurs when the brightness of the output visible light is to be output at a specific brightness. Way. 7. The method of claim 6, wherein the change request to the other coding scheme occurs when the power of the visible light communication device is equal to or less than a specific value. 8. The method of claim 7, wherein the first coding technique is used when the brightness of the output visible light does not have to be maintained at a specific value. The method according to any one of claims 1 to 8, wherein the first coding technique is an 8B10B coding technique and the second coding technique is a 2B4B coding technique. 10. The method of claim 9, wherein the matching table used for the 2B4B coding scheme classifies output values of 4 bits into a plurality of groups according to an inclusion ratio of '1', and outputs belonging to each group by 2 for each of the plurality of groups. And one or more groups of the plurality of groups are selected and used for coding according to the brightness levels of the output visible light. A data coding change device of a visible light communication device,
With encoders and decoders,
Control the encoder and the decoder to process and transmit and receive data by using one of a first coding scheme and a coding scheme of a second coding scheme for adjusting brightness of output visible light for visible light communication, and changing a received coding scheme. And a control unit for changing and setting a data coding scheme to the included coding scheme if the coding scheme included in the request message is different from any one of the currently used coding schemes. The data coding change of claim 11, wherein the controller configures a coding scheme change response message including the type of the changed data coding scheme and transmits the coding scheme change request message to the visible light communication device. Device. The method of claim 12, wherein the one coding scheme is the first coding scheme,
And a data coding scheme is changed to the second coding scheme when a coding scheme change request message for requesting a change to the second coding scheme is received. The method of claim 12, wherein the one coding technique is the second coding technique,
And a data coding scheme is changed to the first coding scheme when a coding scheme change request message for requesting a change to the first coding scheme is received. The method of claim 12, wherein, when the controller detects a change request for the data coding scheme to the different coding scheme, the controller constructs a coding change request message requesting the change to the different coding scheme, and transmits it to the visible light communication device. And when a coding change response message indicating that the different coding scheme is set is received from the corresponding visible light communication device, the data coding scheme is changed to the different coding scheme. 16. The data coding change of claim 15, wherein when the other coding scheme is the second coding scheme, a change request to the other coding scheme occurs when the brightness of the output visible light is to be output at a specific brightness. Device. 17. The apparatus of claim 16, wherein the change request to the other coding scheme occurs when the power of the visible light communication apparatus is equal to or less than a specific value. 18. The apparatus of claim 17, wherein the first coding technique is used when the brightness of the output visible light does not have to be maintained at a specific value. 19. The apparatus of any one of claims 11 to 18, wherein the first coding technique is an 8B10B coding technique and the second coding technique is a 2B4B coding technique. 20. The method of claim 19, wherein the matching table used for the 2B4B coding scheme classifies output values of 4 bits into a plurality of groups according to an inclusion ratio of '1', and outputs belonging to each group are 2 for each of the plurality of groups. And at least one group of the plurality of groups is selected and used for coding according to the brightness levels of the output visible light.

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