KR102091970B1 - Method and apparatus for modulating and demodulating optical camera communication signal - Google Patents

Abstract

According to the present invention, an operation method of an optical camera communication (OCC) device supporting OCC comprises the steps of: obtaining a binary data signal; converting the binary data signal into a global phase shift signal having an integer value from 0 to (M-1); generating a data signal group from the global phase shift signal based on a preset symbol group mapping diagram; generating a pulse wave signal by modulating the data signal group; and flashing each of a plurality of light sources included in the OCC device according to the pulse wave signal.

Description

METHOD AND APPARATUS FOR MODULATING AND DEMODULATING OPTICAL CAMERA COMMUNICATION SIGNAL}

The present invention relates to a method of transmitting and receiving a signal using an optical camera communication (optical camera system, OCC), and more particularly, to a method of modulating and transmitting an OCC signal and a method of demodulating the received OCC signal.

Recently, Visible Light Communication (VLC) technology, a technology that enables wireless communication by adding a communication function to visible light wavelengths, is being actively researched, and the IEEE 802.15.7 international standard is also completed to promote the discovery of a business model for commercialization. have. However, IEEE 802.15.7 is mainly limited to data transmission using a photodiode (PD), and there is a problem in that a dedicated communication device such as a VLC dongle is required. As a result, IEEE 802.15.7m OWC TG (Task Group) is an international standardization of optical wireless communication (OCC) that mainly uses an image sensor such as a camera rather than a photodetector and includes infrared and ultraviolet wavelengths as well as visible light. In progress. OCC can be used in various fields, and in particular, it can be used for vehicle-to-vehicle (V2V) communication and vehicle-to-vehicle (V2X) communication.

However, since the sampling time of the two light sources may differ depending on the state of the light source of the transmitting node and the image sensor of the receiving node and the environmental factors between the light source of the transmitting node and the image sensor of the receiving node, this may result in a blinking phase difference between the two light sources. Lead to fluctuations, and errors may occur as a result of demodulation In an embodiment of the present invention, a data modulation method of a transmitting node and a data demodulation method of a receiving node may be required to reduce such errors.

The object of the present invention for solving the above problems is to modulate the signal by the OCC (optical camera communication) protocol and in demodulating the modulated OCC signal, by utilizing an artificial neural network (artificial neural network) of the OCC signal It provides a way to correct errors.

An operation method of an OCC device supporting optical camera communication (OCC) according to an embodiment of the present invention for achieving the above object, the method comprising: obtaining a binary data signal; Converting the binary data signal into a global phase shift signal having an integer value from 0 to (M-1); Generating a data signal group from the global phase shift signal based on a preset symbol group mapping diagram; Generating a pulse wave signal by modulating the data signal group; And flashing each of the plurality of light sources included in the OCC device according to the pulse wave signal.

까지의 정수 값을 갖는 상기 전역 위상 천이 신호로 변환하는 것을 특징으로 할 수 있다. Here, in the step of converting the global phase shift signal, the binary data signals are grouped by k bits, starting from 0.

It may be characterized in that the conversion to the global phase shift signal having an integer value up to.

Here, the symbol group mapping diagram may show a connection relationship between a plurality of symbols, and may include sub triangles to which the plurality of symbols are connected.

Here, the step of generating a data signal group based on the preset symbol group mapping diagram includes: among the sub triangles included in the symbol group mapping diagram, one sub triangle including a value of the global phase shift signal. Determining; And combining a plurality of symbols included in the one sub triangle according to a preset method.

Here, the step of generating a data signal group based on the preset symbol group mapping diagram includes: a first symbol disposed in the symbol group mapping diagram and a second symbol having a largest Hamming distance value from the first symbol Adding one of the symbols; And adding one symbol among a plurality of preset symbols that do not generate a sub-triangle on the symbol group mapping diagram.

In an operation method of an OCC device supporting optical camera communication (OCC) according to another embodiment of the present invention for achieving the above object, a flashing state of a plurality of light sources included in an OCC signal transmission device for transmitting an OCC signal Detecting; Converting the blinking state information of the light sources into a data signal group; Obtaining a global phase shift signal from the data signal group based on a symbol group mapping table generated from a preset symbol group mapping diagram; And converting the global phase shift signal to obtain binary data.

Here, after the step of converting the blinking state of the light sources into a data signal group, the symbols included in the data signal group are converted into a gray coding method, so that a distance between adjacent symbols reflects a hamming distance. In order to do so, the data signal group may be further pre-processed.

Here, the symbol group mapping diagram may show a connection relationship between a plurality of symbols, and may include sub triangles to which the plurality of symbols are connected.

Here, the symbol group included in the symbol group mapping table may be a combination of symbols included in the sub triangle according to a preset method.

Here, the symbol group included in the symbol group mapping table includes: a symbol of one of a preset first symbol arranged in the symbol group mapping diagram and a second symbol having a largest Hamming distance value from the first symbol; And one symbol among a plurality of preset symbols that do not generate a sub-triangle on the symbol group mapping diagram.

Here, obtaining a global phase shift signal from the data signal group may include: determining whether the data signal group is included in the mapping table; And when the data signal group is not included in the mapping table, an error-corrected data signal is corrected by correcting an error in the data signal group based on a hamming distance between the data signal group and a symbol group included in the mapping table. And generating a group, and correcting the error may be performed by an artificial neural network of the OCC device.

Here, after the step of correcting the error, calculating error information between the data signal group transmitted by the OCC signal transmission device and the error-corrected data signal group; And updating the weight vector of the artificial neural network by back-propagating the error information.

A node supporting optical camera communication (OCC) according to the present invention transmits a data signal group further including a data symbol and an additional symbol to a receiving node based on a preset symbol group mapping diagram. Can be improved.

A node supporting OCC according to the present invention can improve the reception accuracy of an OCC signal by correcting an error of a data signal received from a transmitting node using an artificial neural network.

1 is a conceptual diagram showing an embodiment of the configuration of an optical camera communication (OCC) system.
2 is a flowchart illustrating an embodiment of a signal transmission operation of an OCC transmission node.
3 is a conceptual diagram illustrating a first embodiment of a symbol mapping diagram.
4 is a conceptual diagram illustrating a second embodiment of a symbol mapping diagram.
5 is a flowchart illustrating an embodiment of a signal reception operation of an OCC receiving node.
6 is a flowchart illustrating an embodiment of an error correction operation of an OCC receiving node.
7 is a diagram illustrating an embodiment of arrangement between symbols for pre-coding mapping.
8 is a conceptual diagram illustrating an embodiment of an artificial neural network included in an OCC receiving node.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is a conceptual diagram showing an embodiment of the configuration of an optical camera communication (OCC) system.

Referring to FIG. 1, the OCC system according to an embodiment of the present invention may include an optical wireless transmitting device 110 and an optical wireless receiving device 120. The optical wireless transmission apparatus 110 may include a modulator 111 and a transmitter 112. The transmitter 112 may include at least one or more light sources 112-1 and 112-2, and the light sources 112-1 and 112-2 may be LEDs. The optical wireless reception device 120 may include a receiver 121 and a demodulator 123, and may further include a light source detector 122. The receiver 121 may include an image sensor 121-1 such as a camera.

The modulator 111 may receive a binary data signal D [i], which is a bit sequence to be transmitted, and generate binary data signals S1 (t) and S2 (t) having a modulated pulse waveform. have. S1 and S2 may be continuous signals or discrete signals.

The transmitter 112 may transmit data by flashing each of the plurality of light sources 112-1 and 112-2 according to the binary data signals S1 (t) and S2 (t). Here, the blinking does not necessarily indicate a method in which the light sources 112-1 and 112-2 are completely turned on and off, but two states of binary values 0 and 1 are used by changing the brightness of the light sources 112-1 and 112-2. It may include any way to represent. If the flashing frequencies of the light sources 112-1 and 112-2 are greater than or equal to a certain value (eg, 200 Hz), a person may not be able to feel the flashing of the light sources 112-1 and 112-2.

The receiver 121 may receive an image sequence in which the image sensors 121-1 continuously photograph (sample) the light sources 112-1 and 112-2. The light source detector 122 may detect the positions of the light sources 112-1 and 112-2 in the received image. The demodulator 123 can demodulate the data signal from the flashing states of the light sources 112-1 and 112-2.

2 is a flowchart illustrating an embodiment of a signal transmission operation of an OCC transmission node.

까지의 정수 값을 갖는 전역 위상 천이 신호로 변환할 수 있다(S210). OCC 송신 노드(110)의 변조기(111)는 송신하는 신호의 변조 방식에 따라 이진 데이터 신호를 전역 위상 천이 신호로 변환할 수 있다. OCC 송신 노드의 변조기는 M-ASK(M-amplitude shift keying), M-FSK(M-frequency shift keying), M-PSK(M-phase shift keying), DSM-PSK(dimmable spatial M-phase shift keying) 등의 변조 방식에 따라 이진 데이터 신호를 변조할 수 있다. 예를 들어, M=8 이고, k=3일 경우, OCC 송신 노드(110)의 변조기(111)는 표 1에 따라 이진 데이터 신호를 전역 위상 천이 신호로 변환할 수 있다(S210). Referring to FIG. 2, the OCC transmitting node 110 may acquire a binary data signal D [i]. In addition, the modulator 111 of the OCC transmitting node 110 groups the obtained binary data signal into a plurality of preset bit units, and starts from 0.

It can be converted into a global phase shift signal having an integer value up to (S210). The modulator 111 of the OCC transmission node 110 may convert a binary data signal into a global phase shift signal according to a modulation method of a transmitted signal. The modulators of the OCC transmitting node are M-amplitude shift keying (M-ASK), M-frequency shift keying (M-FSK), M-phase shift keying (M-PSK), and dimmable spatial M-phase shift keying (DSM-PSK). ) Can modulate the binary data signal according to a modulation method. For example, when M = 8 and k = 3, the modulator 111 of the OCC transmission node 110 may convert a binary data signal into a global phase shift signal according to Table 1 (S210).

The modulator 111 of the OCC transmission node 110 may convert a binary data signal into a global phase shift signal according to Table 1, and each global phase shift signal obtained as a result of the conversion is transmitted by the OCC transmission node 110 The group ID of the data signal group can be indicated.

The modulator 111 of the OCC transmitting node 110 may generate a data signal group including a plurality of symbols based on the obtained group ID (S220). Specifically, the modulator 111 of the OCC transmission node 110 may generate a data signal group based on a preset symbol mapping diagram (S220). The symbol mapping diagram may be defined according to a modulation method of a signal transmitted by the OCC transmitting node 110.

3 is a conceptual diagram illustrating a first embodiment of a symbol mapping diagram.

Referring to FIG. 3, the diagram of FIG. 3 may be a diagram in which 8 symbols are arranged by an 8-PSK modulation scheme. In addition, the diagram of FIG. 3 may show a connection relationship between 8 symbols by an 8-PSK modulation scheme, and may include sub-triangles to which 3 symbols are connected. For example, the diagram of FIG. 3 is (0-7-5), (7-5-4), (7-4-6), (5-4-2), (6-3-4), ( 4-1-2), (4-3-1), (3-0-1) and (0-6-2) may include 9 sub triangles.

The modulator 111 of the OCC transmitting node 110 that transmits the signal modulated by the 8-PSK method is the OCC transmitting node according to the value of the global phase shift signal based on the preset symbol mapping diagram of FIG. 3. One of the sub triangles may determine a sub triangle. For example, when the value of the global phase shift signal is 1, the OCC transmitting node may determine one sub triangle (eg, (4-3-1) sub triangle) among sub triangles including 1.

The modulator 111 of the OCC transmission node 110 that transmits the signal modulated by the 8-PSK method may generate a data signal group by combining symbols included in the sub-triangle according to a preset method (S220). The OCC transmitting node combines the symbols included in the sub triangle (eg, (4-3-1) sub triangle) counterclockwise to generate a data signal group (eg, “134” data signal group, etc.). It can be done (S220). Data signal groups that can be generated according to the symbol mapping diagram of FIG. 3 may be as shown in Table 2.

Data signal groups that can be generated according to the symbol mapping diagram of FIG. 3 may be generated such that a hamming distance between data signal groups exceeds a preset threshold. The Hamming distance between the data signal groups generated according to the symbol mapping diagram of FIG. 3 may be calculated by Equation 1.

Equation 1 may indicate the sum of Hamming distances between the first to third symbols included in the data signal group. The hamming distance between symbols may be a hamming distance between symbols shown in FIG. 3. The minimum hamming distance of the data signal groups generated according to the symbol mapping diagram of FIG. 3 may be 3.

The modulator 111 of the OCC transmission node 110 that transmits a signal modulated by the 8-PSK scheme is a data signal group of one of the data signal groups shown in Table 2 from the global transition signals based on the symbol mapping diagram of FIG. 3. You can create When transmitting the signal by the 8-PSK modulation method, the modulator 111 of the OCC transmission node 110 may generate a data signal group including three symbols (S220).

4 is a conceptual diagram illustrating a second embodiment of a symbol mapping diagram.

Referring to FIG. 4, the diagram of FIG. 4 may be a diagram in which 8 symbols are arranged by a DS8-PSK modulation scheme. In addition, the diagram of FIG. 4 may show a connection relationship between 8 symbols by the DS8-PSK modulation method, and may include sub triangles to which 3 symbols are connected. For example, the diagram of FIG. 4 will include four sub triangles that are a combination of (1-2-3), (3-4-5), (5-6-7), and (7-0-1). You can.

The modulator 111 of the OCC transmission node 110 that transmits a signal modulated by the DS8-PSK scheme may determine one sub-triangle of the sub-triangle of FIG. 4 based on a preset symbol mapping diagram of FIG. 4. For example, when the value of the phase shift signal is 1, the modulator 111 of the OCC transmitting node 110 may determine a sub triangle (eg, (1-2-3) sub triangle) including symbol 1 have.

The modulator 111 of the OCC transmission node 110 that transmits a signal modulated by the DS8-PSK method combines the symbols included in the sub-triangle according to a preset method, and includes a 3-symbol group (3 symbols) (3) -symbol group). The modulator 111 of the OCC transmitting node 110 combines symbols included in the sub-triangle (eg, (1-2-3) sub-triangle) counterclockwise to form a three-symbol group (eg, " 123 "3-symbol group). The 3-symbol groups that can be generated according to the symbol mapping diagram of FIG. 4 may be as shown in Table 3. Referring to Table 3, the modulator 111 of the OCC transmission node 110 may generate 12 three-symbol groups according to the symbol mapping diagram of FIG. 4.

The modulator 111 of the OCC transmitting node 110 that transmits a signal modulated by the DS8-PSK method may generate a 4-symbol group by adding a fourth symbol to the 3-symbol group. The fourth symbol may be one of two different preset symbols. The two different preset symbols may have the largest Hamming distance value on the symbol mapping diagram of FIG. 4. For example, one symbol of two different symbols may be 0, and the other symbol may be 4. The 4-symbol group according to the symbol mapping diagram of FIG. 4 may be as shown in Table 4.

Referring to Table 4, 4-symbol groups may be symbols in which symbol 0 or symbol 4 is further added to the 3-symbol group in Table 3. For example, the modulator 111 of the OCC transmitting node 110 adds symbol 0 or symbol 4 to a 3-symbol group (eg, 3-symbol group 123), and thus, two 4-symbol groups (eg, For example, a 4-symbol group 1234 or 1230) can be created. The modulator 111 of the OCC transmitting node 110 may generate 24 4-symbol groups according to the symbol mapping diagram of FIG. 4.

The modulator 111 of the OCC transmission node 110 that transmits a signal modulated by the DS8-PSK method may generate a data signal group by adding a fifth symbol to the 4-symbol group (S220). The fifth symbol may be one of two preset sets of different symbols. For example, two different sets of preset symbols may include three symbols on the symbol mapping diagram, and the three symbols included in the symbol set cannot form a sub-triangle on the symbol mapping diagram of FIG. 4. Can be For example, one symbol set of two different symbol sets may be (0-3-6), and the other symbol set may be (2-4-7). The data signal group generated according to the symbol mapping diagram of FIG. 4 may be as shown in Table 5.

Referring to Table 5, data signal groups may further include one of two different symbol sets preset in the 4-symbol group of Table 4. For example, the modulator 111 of the OCC transmitting node 110 may generate one data signal group by adding a fifth symbol to one 4-symbol group. The modulator 111 of the OCC transmitting node 110 may generate 24 data signal groups according to the symbol mapping diagram of FIG. 4.

Data signal groups that can be generated according to the symbol mapping diagram of FIG. 4 may be generated such that a hamming distance between the data signal groups exceeds a preset threshold. The Hamming distance between data signal groups generated according to the symbol mapping diagram of FIG. 4 may be calculated by Equation (2).

Equation 2 may indicate the sum of Hamming distances between the first to fifth symbols included in the data signal group. The hamming distance between symbols may be a hamming distance between symbols shown in FIG. 4. The minimum hamming distance of the data signal groups generated according to the symbol mapping diagram of FIG. 4 may be 6.

The modulator 111 of the OCC transmission node 110 that transmits a signal modulated by the DS8-PSK method is a data signal group of one of the data signal groups shown in Table 5 from the global transition signal based on the symbol mapping diagram of FIG. 4. It can be generated (S220). When transmitting a signal by the DS8-PSK modulation method, the modulator 111 of the OCC transmission node 110 may generate a data signal group including five symbols (S220).

Referring back to FIG. 2, the modulator 111 of the OCC transmission node 110 may generate a data signal group based on FIG. 3 or FIG. 4 (S220), and modulate the data signal group to generate a plurality of pulse wave signals. You can create them (S230). The modulator 111 of the OCC transmitting node 110 may transmit a plurality of pulse wave signals to the transmitter 112 of the OCC transmitting node 110.

The transmitter 112 of the OCC transmitting node 110 may acquire pulse wave signals from the modulator 111 of the OCC transmitting node 110. In addition, the transmitter 112 of the OCC transmission node 110 may transmit a signal by flashing each of the light sources (for example, LED, etc.) included in the transmitter 112 according to the generated plurality of pulse wave signals. (S240).

5 is a flowchart illustrating an embodiment of a signal reception operation of an OCC receiving node.

Referring to FIG. 5, the receiver 121 of the OCC receiving node 120 may detect a flashing state of a plurality of light sources included in the transmitter 112 of the OCC transmitting node 110. Specifically, an image sensor (for example, a camera, etc.) included in the receiver 121 of the OCC receiving node 120 can continuously capture images and deliver images to the demodulator 123 of the OCC receiving node 120. have. The demodulator 123 of the OCC receiving node 120 may detect a flashing state of a light source (eg, LED, etc.) included in the OCC transmitting node based on the images acquired from the image sensor (S510). And the demodulator 123 of the OCC receiving node 120 is a plurality of symbols (M-PSK symbol or DSM-PSK symbol, etc.) based on the flashing state of the light source included in the transmitter 112 of the OCC transmitting node 110 It can be obtained (S520). The demodulator 123 of the OCC receiving node 120 may correct errors of the acquired symbols (S530).

6 is a flowchart illustrating an embodiment of an error correction operation of an OCC receiving node.

Referring to FIG. 6, the demodulator 123 of the OCC receiving node 120 may combine a plurality of symbols to obtain a data signal group. The number of symbols included in the data signal group may be determined according to the modulation scheme of the signal transmitted by the OCC transmission node 110.

When the OCC transmitting node 110 transmits a signal modulated by the 8-PSK modulation method, the demodulator 123 of the OCC receiving node 120 may combine three symbols to generate a data signal group (S531) ). When the OCC transmitting node 110 transmits a signal modulated by the DS8-PSK modulation method, the demodulator 123 of the OCC receiving node 120 may combine five symbols to obtain a data signal group (S531) ).

The demodulator 123 of the OCC receiving node 120 may perform data pre-processing before correcting the error of the symbol from the data signal group (S532). The demodulator 123 of the OCC receiving node 120 may modulate the symbol to reflect the hamming distance between the symbols.

7 is a diagram illustrating an embodiment of arrangement between symbols for pre-coding mapping.

Referring to FIG. 7, the diagram of FIG. 7 may be a constellation diagram in which 8-PSK (or DS8-PSK) symbols are arranged. Specifically, the diagram of FIG. 7 may be a diagram in which 8 symbols of 8-PSK (or DS8-PSK) are arranged at regular intervals on one circumference. Each symbol arranged in the diagram may include 4 bits. Each symbol may be modulated by a gray-coding technique, and the hamming distance of each modulated symbol may be 1.

The demodulator 123 of the OCC receiving node 120 may perform a data preprocessing operation of symbols included in the data signal group based on pre-set arrangement information between symbols. Specifically, the demodulator 123 of the OCC receiving node 120 may perform a data pre-processing operation to obtain a data signal group including gray-coded symbols according to FIG. 7 (S532).

Referring back to FIG. 6, the demodulator 123 of the OCC receiving node 120 may acquire a preprocessed data signal group (S532) and determine whether an error in the preprocessed data signal group is performed.

The demodulator 123 of the OCC receiving node 120 receiving the signal modulated by the 8-PSK method may determine whether the data signal group is included in Table 2. If the data signal group is not included in Table 2, the demodulator 123 of the OCC receiving node 120 may determine that there is an error in the data signal group. In addition, the demodulator 123 of the OCC receiving node 120 receiving the signal modulated by the DS8-PSK method can determine whether the data signal group is included in Table 4. If the data signal group is not included in Table 5, the demodulator 123 of the OCC receiving node 120 may determine that there is an error in the data signal group.

The OCC receiving node 120, which determines that there is an error in the data signal group, may correct the error in the received data signal group (S533). The error correction operation of S533 may be an artificial intelligent error correction (AIEC) operation performed by an artificial neural network included in the OCC receiving node 120.

8 is a conceptual diagram illustrating an embodiment of an artificial neural network included in an OCC receiving node.

Referring to FIG. 8, the artificial neural network of the OCC receiving node 120 may include a plurality of layers, and each layer may include a plurality of artificial nodes. In addition, the artificial neural network of the OCC receiving node 120 may include a plurality of adaptive weight vectors, and artificial nodes included in respective layers of the artificial neural network may be connected by a weight vector. The artificial neural network of the OCC receiving node may include a plurality of layers and artificial nodes according to a preset parameter, and may correct errors in the data signal group received by the OCC receiving node 120.

For example, when the receiving node 120 receives a group of data signals modulated by the 8-PSK method, the OCC receiving node 120 uses the artificial neural network set based on the parameters in Table 6 to determine the group of data signals. The error can be corrected.

Referring to Table 6, the artificial neural network of the OCC receiving node 120 may include four layers, specifically, an input layer, an output layer, and a hidden layer. You can. The input layer may be a layer into which bits included in the preprocessed data signal group are input. The input layer may include 12 artificial nodes, and each artificial node of the input layer may be an artificial node into which bits constituting symbols obtained as a result of data preprocessing are input.

In addition, the output layer may be a layer that outputs a data signal group in which errors are corrected from a data signal group input to the input layer. The output layer may include 27 artificial nodes, and each artificial node included in the output layer may indicate a data signal group defined in Table 2.

And two of the four layers may be a hidden layer. Hidden layers may include 271 artificial nodes. The hidden layer can be connected to the input layer through a weighted vector, or the hidden layer can be connected to an output layer through a weighted vector. The artificial neural network of the OCC receiving node 120 may obtain a data signal group in which errors are corrected according to weighting vectors of the artificial neural network, using the bits of the data signal group generated as a result of data pre-processing as input values.

For example, when a data signal group modulated by the DS8-PSK method is received, the OCC receiving node 120 can correct an error in the data signal group using an artificial neural network set based on the parameters in Table 7. have.

Referring to Table 7, the artificial neural network of the OCC receiving node 120 may include four layers. The first layer may be a layer into which a pre-processed data signal group is input. The first layer may include 20 artificial nodes, and each artificial node may be an artificial node into which bits obtained as a result of data preprocessing are input.

In addition, the second layer may be a layer that outputs a data signal group in which errors are corrected from the data signal group input in the first layer. The second layer may include 24 artificial nodes, and each artificial node included in the second layer may indicate a data signal group defined in Table 5.

Two of the four layers may be a hidden layer. And each hidden layer may include 241 artificial nodes. The hidden layer can be connected to the input layer through a weighted vector, or the hidden layer can be connected to an output layer through a weighted vector. The artificial neural network of the OCC receiving node 120 may obtain a data signal group in which errors are corrected according to weighting vectors of the artificial neural network, using the bits of the data signal group generated as a result of data pre-processing as input values.

The OCC receiving node 120 may perform a learning operation to update the weighted vectors of the artificial neural network. The learning operation may be performed by a multi-layer perceptron classifier included in the OCC receiving node 120.

The OCC receiving node 120 may further include a multi-layer perceptron classifier. The multilayer perceptron classifier can train an artificial neural network through a preset learning algorithm. The learning algorithm may include learning algorithms such as a supervised learning algorithm and a non-supervised learning algorithm.

The artificial neural network of the receiving node 120 of the OCC may perform a feed-forward operation to correct an error in the data signal group, thereby generating an error-corrected data signal group. The multilayer perceptron classifier of the OCC receiving node 120 may calculate error information between a data signal group corrected for an error through an artificial neural network and a data signal group transmitted by the OCC transmitting node 110. The multi-layer perceptron classifier of the receiving node 120 of the OCC may perform a learning operation to correct weighted vectors between layers of the artificial neural network by back-propagating the calculated error information. The multi-layer perceptron classifier of the receiving node 120 of the OCC can perform a learning operation based on the parameters defined in Table 8.

The multi-layer perceptron classifier of the OCC receiving node 120 can modify weight vectors between layers of the artificial neural network through a preset optimization algorithm. The optimization algorithm may include a gradient descent method and the like, and referring to Table 8, an Adam-optimizer algorithm may be further included. The multi-layer perceptron classifier of the OCC receiving node 120 may repeatedly perform a learning operation as many as a preset number of epochs (500 times in Table 8).

까지의 정수 값을 갖는 신호일 수 있다. Referring back to FIG. 6, the demodulator 123 of the OCC receiving node 120 may obtain a group ID and a global phase shift signal from a data signal group in which errors are corrected (S534). The global phase shift signal

It may be a signal having an integer value of.

The demodulator 123 of the OCC receiving node 120 may obtain the binary data signal D [i] by converting the acquired group ID and global phase shift signal (S540). For example, when M = 8 and k = 3, the modulator 123 of the OCC receiving node 120 obtains the binary data signal D [i] from the group ID and global phase shift signal according to Table 1 It can be done (S540).

The methods according to the invention are implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer readable medium. Computer-readable media may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention or may be known and usable by those skilled in computer software.

Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as roms, rams, flash memories, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine code such as that produced by a compiler. The above-described hardware device may be configured to operate with at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. Will be able to.

Claims (12)

In the operation method of the OCC device supporting OCC (optical camera communication),
Obtaining a binary data signal;
Converting the binary data signal into a global phase shift signal having an integer value from 0 to (M-1);
Generating a data signal group from the global phase shift signal based on a preset symbol group mapping diagram;
Generating a pulse wave signal by modulating the data signal group; And
And blinking each of a plurality of light sources included in the OCC device according to the pulse wave signal,
The symbol group mapping diagram,
Shows a connection relationship between a plurality of symbols,
A method of operating an OCC device, characterized in that it comprises sub triangles to which the plurality of symbols are connected. The method according to claim 1,
The step of converting the global phase shift signal,
The binary data signals are grouped by k bits, starting from 0

And converting the global phase shift signal having an integer value up to OCC. delete The method according to claim 1,
Generating a data signal group based on the preset symbol group mapping diagram,
Determining, among the sub triangles included in the symbol group mapping diagram, one sub triangle including a value of the global phase shift signal; And
And combining a plurality of symbols included in the one sub triangle according to a preset method. The method according to claim 4,
Generating a data signal group based on the preset symbol group mapping diagram,
Adding one of the first symbol, which is arranged in the symbol group mapping diagram, and the second symbol having the largest Hamming distance value from the first symbol; And
And adding one symbol among a plurality of preset symbols that do not generate a sub-triangle on the symbol group mapping diagram. In the operation method of the OCC device supporting OCC (optical camera communication),
Detecting a flashing state of a plurality of light sources included in the OCC signal transmission device for transmitting the OCC signal;
Converting the blinking state information of the light sources into a data signal group;
Obtaining a global phase shift signal from the data signal group based on a symbol group mapping table generated from a preset symbol group mapping diagram; And
Converting the global phase shift signal to obtain binary data,
The symbol group mapping diagram,
Shows a connection relationship between a plurality of symbols,
A method of operating an OCC device, characterized in that it comprises sub triangles to which the plurality of symbols are connected. The method according to claim 6,
After the step of converting the blinking state of the light source into a data signal group,
And converting the symbols included in the data signal group into a gray coding method to preprocess the data signal group such that the distance between adjacent symbols reflects a hamming distance. How it works. delete The method according to claim 6,
The symbol group included in the symbol group mapping table,
Method of operation of the OCC device, characterized in that a combination of symbols included in the sub-triangle according to a preset method. The method according to claim 9,
The symbol group included in the symbol group mapping table,
A symbol of one of a preset first symbol disposed in the symbol group mapping diagram and a second symbol having a largest Hamming distance value from the first symbol; And
And a symbol among a plurality of preset symbols that do not generate a sub-triangle on the symbol group mapping diagram. The method according to claim 7,
Acquiring a global phase shift signal from the data signal group,
Determining whether the data signal group is included in the mapping table; And
When the data signal group is not included in the mapping table, an error-corrected data signal group is corrected by correcting an error of the data signal group based on a hamming distance between the data signal group and a symbol group included in the mapping table It includes the steps of generating,
Correcting the error,
Method of operation of the OCC device, characterized in that is performed by an artificial neural network (artificial neural network) of the OCC device. The method according to claim 11,
After the step of correcting the error,
Calculating error information between the data signal group transmitted by the OCC signal transmission device and the data signal group in which the error is corrected; And
And back-propagating the error information to update the weight vector of the artificial neural network.

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