KR102393233B1 - Visible light communication device and method for detecting malicious interferers - Google Patents

Abstract

The present invention is to provide a visible light notification device and method for detecting a malicious interferer. The visible light notification device according to the present invention comprises: a light source management unit which transmits data by controlling a lighting lamp for visible light communication; a receiving unit which receives a signal fed back from a terminal having received data from the lighting lamp; and a control unit which determines whether a malicious interferer exists based on the feedback signal.

Description

VISIBLE LIGHT COMMUNICATION DEVICE AND METHOD FOR DETECTING MALICIOUS INTERFERERS

The present invention relates to a visible light communication device and a method for detecting a malicious interferer, and more particularly, to an apparatus and method for detecting a malicious interferer on a visible light communication network and mitigating the interference of the malicious interferer.

Visible light wireless communication is a communication technology by applying modulation technology using fast blinking of LEDs using infrastructure in which lighting such as incandescent bulbs and fluorescent lamps is replaced with Light Emitting Diode (LED) lighting by digital semiconductors. That is, visible light communication is a technology that can use illumination light as a communication light source as semiconductors begin to use it as lighting, and it can be said that it is a fusion of lighting and communication. Currently, standards such as IEEE 802.15 VLC and TTA visible light communication service working group are being promoted, and new communication services such as optical ID, optical sensor, ultra-precision indoor positioning, and location broadcasting can be provided by utilizing LED lighting infrastructure.

Visible light wireless communication communicates in the visible light band from 400nm (750THz) to 700nm (400THz), and there is IrDA (infrared communication) as a communication similar to visible light wireless communication. have it

Visible light communication has the following characteristics. First, since the LED plays an important role as a lighting function as well as communication, it has a characteristic of visibility. Second, since visible light communication can communicate up to the distance that light reaches, and thus, unlike RF communication, communication security can be achieved, so it has a feature of security. Third, since light is harmless to the human body under conditions in consideration of eye safety, it has the characteristic of being healthy.

As a light source (LED & Photodetector) used for modulation/demodulation in the wireless visible light communication band, LEDs with low power consumption and long lifespan are in the spotlight. Advantages of LED light sources include low power consumption and long lifespan. Incandescent bulbs convert only 10% of power into light, whereas LEDs convert 90% of power into light, so power consumption is significantly lower. In addition, while the lifespan of conventional light bulbs is up to 4,000 hours, the lifespan of LEDs is as long as 100,000 hours.

1 is for explaining the communication concept of visible light communication using a light emitting diode. The transmitting unit 100 of the visible light communication modulates an electrical signal input to the LED into light to transmit the intensity-modulated signal through the light source, and the receiving unit 110 transmits the received optical signal to a photodiode. ) as a change in the current magnitude directly to detect (direct detection). This transmission method is called an intensity modulation/direct detection (IM/DD) method.

The representative modulation/demodulation techniques used in the transmitter and receiver of visible light communication in FIG. 1 are largely a baseband modulation method in which modulation is performed in a baseband and a subcarrier modulation method in which a subcarrier is used to transmit. can be classified. Representative baseband modulation techniques include line coding and pulse modulation using pulse characteristics such as position, width, and interval. can Modulation techniques currently being considered in visible light communication include an on-off keying (hereinafter referred to as OOK) modulation technique and Pulse Position Modulation (PPM), which are already used in infrared communication.

2 shows a modulation technique used for visible light communication. 2(a) illustrates an OOK modulation technique. It can be said to be the basic form of the amplitude modulation technique. As shown in Fig. 2(a), it is a method of transmitting data by turning an electrical signal on/off according to binary information. OOK modulation technique is used when high noise immunity is not required because of its relatively simple implementation and high frequency efficiency compared to other modulation techniques. way to be

FIG. 2(b) illustrates a pulse position modulation (PPM) method, and among them, 4-PPM is illustrated. PPM is a method of transmitting a pulse by changing the position of a pulse according to binary information. It has excellent energy efficiency and is used as a standard modulation/demodulation method for infrared communication.

2(c) shows inverter pulse position modulation (hereinafter, Inverted 4-PPM). This was proposed as a method to improve the lighting function by inverting the pulse of the M-ary pulse position modulation technique to increase the light output. The peak value of the OOK modulation technique is reduced to half of the peak value of 4-PPM, so bit error rate performance is degraded, and optical output is also reduced by half. When using the inverted 4-PPM method, compared with 4-PPM, if the peak value is assumed to be the same, there is an advantage that the average light output can be improved 3 times from A/4 to 3A/4.

On the other hand, unlike RF wireless communication, visible light communication has several advantages, such as harmless to the human body, unregulated spectrum resources, high data rate, and high energy efficiency due to low power consumption, but is vulnerable to channel interference that causes performance degradation.

A light detector, a component of a visible light communication system, may receive co-channel interference caused by a nearby transmitter that transmits data using the same frequency.

Various approaches are being studied to reduce co-channel interference in a visible light communication system. Color shift modulation can be applied to reduce co-channel interference and increase the bit rate per symbol. Co-channel interference can be eliminated by using orthogonal frequency division multiplexing technology in a visible light communication system. Interference can be mitigated by adding a Zero Forcing Equalizer. Co-channel interference can be reduced by replacing the optical detector (receiver) of the visible light communication system with an Angular Diversity Receiver (ADR).

Various approaches have been studied to reduce co-channel interference as described above, but there is no approach considering the actual environment in which malicious interference that may intentionally cause degradation of communication performance exists.

[Prior literature]

[Non-patent literature]

Prior Document 1: TV Pham, H. Le-Minh, and AT Pham, "Multi-user visible light communication broadcast channels with zero-forcing precoding," IEEE Trans. Commun. , vol. 65, no. 6, pp. 2509-2521, June 2017

Prior Document 2: HB Eldeeb et al., “Co-channel interference cancellation using constraint field of view ADR in VLC channel,” 2017 IEEE Photonics Conf. (IPC) Part II , Orlando, FL, USA, pp. 1-2, Oct. 2017.

In order to solve the above problems, an object of the present invention is to provide a visible light notification apparatus and method for detecting a malicious interferer.

A visible light communication device according to an embodiment of the present invention for achieving the above object, the light source management unit for transmitting data by controlling an illumination lamp for visible light communication; a receiver for receiving a signal fed back from a terminal receiving data from the lighting lamp; and a control unit that determines whether a malicious interferer exists based on the feedback signal.

In an embodiment, in the visible light communication device, the fed back signal is an error check result of data received by the terminal, and the controller determines that a malicious interferer exists if the error check result error is greater than or equal to a preset first threshold value characterized by judging.

In one embodiment, when it is determined that a malicious interferer exists, the controller changes the communication channel.

In one embodiment, when it is determined that the intelligent interferer exists, the control unit repeatedly performs a pre-stored interferer utility maximization algorithm and a visible light communication network algorithm to maximize transmission efficiency of visible light communication and transmit power and sub-channels. It is characterized by estimating.

In one embodiment, the interferer utility maximization algorithm is characterized in that it finds the interference power that maximizes the SINR reduction of the visible light communication network based on a preset interferer battery energy.

According to another embodiment of the present invention for achieving the above object, there is provided a method for detecting a malicious interferer of a visible light communication device for controlling an illumination lamp for visible light communication, wherein a signal fed back from a terminal receiving data from the illumination lamp is provided. receiving; and determining whether a malicious interferer exists based on the fed back signal.

In an embodiment, the fed back signal is an error check result of data received by the terminal.

In an embodiment, the determining of the presence of the malicious interferer may include determining that the malicious interferer exists when the error is greater than or equal to a preset first threshold as a result of the error check.

In an embodiment, the determining of the presence of the malicious interferer may further include changing an activation channel according to a result of determining whether the malicious interferer exists.

In one embodiment, when it is determined that the intelligent interferer exists, in the step of changing the communication channel, a previously stored interferer utility maximization algorithm and a visible light communication network algorithm are repeatedly performed to maximize transmission efficiency of visible light communication. It is characterized in that the communication channel is changed to the estimated sub-channel by estimating the power and the sub-channel.

According to an embodiment of the present invention, there is an effect that the interference can be mitigated by easily detecting a malicious interferer.

In addition, there is an effect of improving the performance of the visible light communication network by applying game theory in the visible light communication system, and using the optimal resource allocation to efficiently use power.

1 is a diagram of a transceiver of general visible light communication.
2 is a modulation technique applied to general visible light communication.
3 is a view for explaining the configuration of a visible light communication system having a malicious interferer according to an embodiment of the present invention.
4 is a block diagram illustrating the configuration of a visible light communication device according to an embodiment of the present invention.
5 is a flowchart illustrating a method for detecting a malicious interferer in a visible light communication device according to an embodiment of the present invention.
6 is a diagram illustrating an example of an indoor visible light system according to an embodiment of the present invention.
7 is a diagram for explaining a game algorithm according to an embodiment of the present invention.
8 is a graph for comparing the performance of a game algorithm according to an embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same components in the drawings are denoted by the same reference numbers and reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

3 is a view for explaining the configuration of a visible light communication system having a malicious interferer according to an embodiment of the present invention.

As shown in FIG. 3 , the visible light communication system includes one or more lighting lamps 20 , a visible light communication device 200 for controlling the lighting lamps 20 to transmit data, and one or more visible light reception for performing visible light communication. It is configured to include the terminal 300 .

Among them, the lighting lamp 20 serves as a general lighting function and is used as a transmitter for transmitting a signal at the same time. LED or LD, etc. are exemplified.

The visible light communication device 200 according to an embodiment of the present invention is connected to the lighting lamp 20 and serves to manage the lighting lamp. As the visible light communication device 200 , an access point (AP) for visible light communication may be exemplified. The visible light communication device 200 controls the illumination lamp 20 to provide a data service using visible light to the visible light receiving terminal 300 located within the irradiation range of the illumination lamp 20 .

The visible light receiving terminal 300 is a terminal for receiving data in the form of visible light from the lighting lamp 20 . The visible light receiving terminal 300 may include an IOT terminal.

In an embodiment, the visible light receiving terminal 300 checks the error of the received data and feeds it back to the visible light communication device 200 .

The visible light communication device 200 determines the presence of a malicious interferer based on the feedback of the visible light receiving terminal 300 .

When it is determined that the interferer X exists as a result of the determination, the visible light communication apparatus 200 may change the visible light channel of the lighting lamp 20 .

The visible light communication device 200 may use an algorithm to which game theory is applied, improve interferer determination and visible light communication network performance, and efficiently use power by using optimal resource allocation.

4 is a block diagram illustrating the configuration of a visible light communication device according to an embodiment of the present invention.

The visible light communication device 200 may include a light source manager 210 , a receiver 220 , and a controller 230 .

The light source management unit 210 manages the lighting lamp 20 .

In an embodiment, the light source controller 210 transmits data to be transmitted to the lighting lamp 20 to transmit a signal through the lighting lamp 20 .

The receiver 220 may include a photodiode 221 . The photodiode 221 converts an electrical signal when a visible light signal is input from outside the photo channel. The receiver 220 may restore data from a signal converted into an electrical signal through the photodiode 221 , and may restore an original transmitted signal through the restored data.

The control unit 230 determines whether a malicious interferer exists based on the signal received through the reception unit 220, and maintains or changes the communication channel according to the determination result.

That is, the control unit 230 may determine whether there is a malicious interferer based on the signal transmitted by the visible light receiving terminal 300 .

In an embodiment, the control unit 230 may use an algorithm to which a game theory stored in advance is applied to improve interferer determination and visible light communication network performance, and to efficiently use power using optimal resource allocation.

The operation of the control unit 230 will be described in detail with reference to FIG. 5 below.

5 is a flowchart illustrating a method for detecting a malicious interferer in a visible light communication device according to an embodiment of the present invention.

In step S110, the visible light communication device receives a signal fed back from the terminal receiving data from the lighting lamp.

In step S120, the visible light communication device determines whether a malicious interferer exists based on the feedback signal received from the terminal.

Here, the fed back signal is an error check result of data received by the terminal. That is, the terminal receives the visible light including data from the lighting lamp, restores the data by demodulation, and checks the error from the restored data. The terminal feeds back an error check result to the visible light communication device. In this case, visible light communication can also be used, and for this, the terminal must include a light source and the visible light communication device must include a photodiode.

In step S120 , the visible light communication device may determine that a malicious interferer exists if the error is greater than or equal to a preset first threshold as a result of the error check.

Also, the visible light communication device may change the communication channel according to a result of determining whether the malicious interferer exists. That is, if it is determined that a malicious interferer exists, the current communication channel may be changed.

When the visible light communication device changes the communication channel, it is possible to estimate the transmission power and sub-channel maximizing the transmission efficiency of the visible light communication by repeatedly performing the previously stored interferer utility maximization algorithm and the visible light communication network algorithm to be described later. The visible light communication device may escape the interference of the interferer or mitigate the influence by changing the communication channel to the estimated sub-channel.

The interferer utility maximization algorithm finds an interference power that maximizes the SINR reduction of the visible light communication network based on a preset interferer battery energy.

A game algorithm including a utility maximization algorithm and a visible light communication network algorithm will be described in detail with reference to FIGS. 6 and 7 .

Before explaining the game algorithm, let's look at the factors required for the game algorithm.

6 is a diagram illustrating an example of an indoor visible light system according to an embodiment of the present invention.

Referring to FIG. 6 , the horizontal distance 230 between the lighting lamp 20 and the visible light receiving terminal 300 , the vertical distance h between the lighting lamp 20 and the visible light receiving terminal 300 , and the visible light emission angle of the lighting lamp (ψ), the visible light incident angle (ϕ).

Referring to FIG. 2 , the gain of an indoor visible light communication channel including a LoS and a reflection component may be expressed as [Equation 1].

[Equation 1]

는 램버시안(Lambertian) 지표로 절반 강도 각도(half-intensity angle)

로 표현되고,

는 포토다이오드(photo-diode, PD)의 물리적 면적,

수신기 시야(Field of View, FoV)의 절반 각도,

는 광필터의 이득,

는 concentrator 이득을 의미한다.here,

is a Lambertian index and is the half-intensity angle.

is expressed as

is the physical area of the photodiode (PD),

Half angle of receiver Field of View (FoV),

is the gain of the optical filter,

is the concentrator gain.

[Equation 2]

Referring to FIG. 6 , the signal-to-interference-plus-noise ratio (SINR) of user k from the visible light communication access point may be defined as in [Equation 3].

[Equation 3]

는 척도 함수로

는 채널 n이 사용자 k에 할당된 것을 의미하고,

는 광학적 특성을 전기적 특성으로 전환하는 계수,

는 가시광통신 액세스 포인트에서 사용자 k에 대한 평균 송신전력,

는 잡음 전력,

는 간섭자로부터의 간섭 전력,

는 간섭자에서 사용자 k까지의 채널 이득으로 [수학식 4]와 같이 정의할 수 있다.here,

is a scale function

means that channel n is assigned to user k,

is the coefficient that converts optical properties into electrical properties,

is the average transmit power for user k in the visible light communication access point,

is the noise power,

is the interference power from the interferer,

can be defined as [Equation 4] as the channel gain from the interferer to the user k.

[Equation 4]

는 간섭자와 사용자 사이의 수평거리,

는 간섭자의 높이,

는 방사 각도,

는 입사 각도이다.here,

is the horizontal distance between the interferer and the user,

is the height of the interferer,

is the radiation angle,

is the angle of incidence.

와 가시광통신 네트워크가 동작하기 위해 사용하는 전력

는 [수학식 5], [수학식 6]으로 각각 표현할 수 있다.Referring to FIG. 1 , power used by a malicious interferer to interfere with a visible light communication network

and the power used by visible light communication networks to operate

can be expressed by [Equation 5] and [Equation 6], respectively.

[Equation 5]

[Equation 6]

7 is a diagram for explaining a game algorithm according to an embodiment of the present invention.

The game algorithm according to an embodiment of the present invention is a visible light communication Stackelberg game model by applying game theory to the visible light network system described with reference to FIGS. 1 to 5 .

As shown in FIG. 7 , the algorithm may include a Takelberg game model, an interferer utility max algorithm (S310), a visible light communication network utility max algorithm (S320), and a Stackelberg game algorithm (S330).

Here, the two players can be a visible light communication device and a malicious interferer.

A malicious interferer may be a leader, and a visible light communication device may be a follower.

The malicious interferer may maximize his/her utility by observing the transmission power and channel of the visible light communication network according to the interferer utility maximum algorithm ( S310 ).

The visible light communication device may maximize its utility by observing the interference power of the malicious interferer according to the visible light communication network utility maximum algorithm ( S320 ).

The Stackelberg game model can be defined as in [Equation 7].

[Equation 7]

G = (N, A, U)

Here, N is a set of players composed of a malicious interferer and a visible light communication network, A is a set of constraints, and U is a set of utilities.

The utility of the malicious interferer refers to the degree to which the malicious interferer reduces the SINR of the visible light communication network in consideration of its limited battery power. A malicious interferer's utility seeks to find an interference power that maximizes the SINR reduction of a visible light communication network in consideration of limited battery power.

The utility maximization problem of a malicious interferer considering limited battery power can be expressed as [Equation 8]. When implementing the actual Stackelberg game model, variables such as battery power of the malicious interferer may be set to values assumed by the designer.

[Equation 8]

{

}subject to:

{

}

는 악의적 간섭자의 최대 간섭 전력이고

는 단위 송신전력의 비용이다. here,

is the maximum interference power of the malicious interferer,

is the cost of unit transmit power.

The utility of the visible light communication network means the transmission efficiency of the visible light communication network. A utility of a visible light communication network seeks to find a transmission power and sub-channel that maximizes the transmission efficiency of a visible light communication network in a limited environment.

The utility maximization problem of a visible light communication network in a limited environment can be expressed as [Equation 9].

[Equation 9]

subject to:

는 가시광통신 액세스 포인트의 최대 전송 전력,

는 신뢰성 있는 가시광통신을 가능하게 하는 최소 SINR이다.here,

is the maximum transmit power of the visible light communication access point,

is the minimum SINR that enables reliable visible light communication.

The Stackelberg game algorithm (S330) may perform optimal resource allocation by receiving optimal parameters from the malicious interferer utility maximization algorithm (S310) and the visible light communication network utility maximization algorithm (S320).

The Stackelberg game algorithm (S330) repeatedly performs two algorithms by exchanging interference power, transmission power, and sub-channels from the malicious interferer utility maximization algorithm (S310) and the visible light communication network utility maximization algorithm (S320).

8 is a graph for comparing the performance of a game algorithm according to an embodiment of the present invention.

The SINR values at each game trial in Fig. 8 are shown.

It can be seen that the signal-to-noise ratio of the graph according to an embodiment of the present invention is the highest. On the other hand, it is the highest compared to the case where the scale function is fixed, the average transmission power for the reception terminal k is fixed in the visible light communication device, or nothing is applied.

When the number of repetitions is 6, the SINR according to an embodiment of the present invention is 9.3 dB higher than that in which nothing is applied.

In addition, it can be seen that when the number of repetitions exceeds a certain number of times (6) or more, there is no significant gain in SINR.

The method according to an embodiment of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and 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 available to those skilled in the computer software field. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - Includes magneto-optical media and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. In addition, the above-mentioned medium may be a transmission medium such as an optical or metal wire or waveguide including a carrier wave for transmitting a signal designating a program command, a data structure, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations may be made by those of ordinary skill in the art to which the present invention pertains without departing from the essential characteristics of the present invention. Accordingly, the embodiments implemented in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

20: lighting lamp
200: visible light communication device
210: light source management unit
220: receiver
230: control unit
300: visible light receiving terminal

Claims (10)

a light source management unit for transmitting data by controlling the lighting lamp for visible light communication;
a receiver for receiving a signal fed back from a terminal receiving data from the lighting lamp; and
A control unit that determines the presence of a malicious interferer based on the feedback signal
including,
When it is determined that the malicious interferer exists, the control unit repeatedly performs a pre-stored interferer utility maximization algorithm and a visible light communication network algorithm to estimate transmission power and sub-channel maximizing transmission efficiency of visible light communication, and a communication channel to the sub-channel,
wherein the interferer utility maximization algorithm finds an interference power that maximizes a signal-to-interference and noise ratio (SINR) of a visible light communication network based on a preset interferer battery energy.
According to claim 1,
The feedback signal is an error check result of data received by the terminal,
The control unit determines that a malicious interferer exists when the error is greater than or equal to a preset first threshold as a result of the error check.
delete delete According to claim 1,
Signal-to-Interference-plus-Noise Ratio (SINR) is a visible light communication device, characterized in that defined as follows.

here,

is a scale function

means that channel n is assigned to user k,

is the coefficient that converts optical properties into electrical properties,

is the average transmit power for user k in the visible light communication access point,

is the noise power,

is the interference power from the interferer,

is the channel gain from interferer to user k.
A method for detecting a malicious interferer in a visible light communication device for controlling an illumination lamp for visible light communication, the method comprising:
receiving a signal fed back from a terminal receiving data from the lighting lamp; and
determining whether a malicious interferer exists based on the fed back signal
including,
In the step of determining the existence of the malicious interferer,
When it is determined that the malicious interferer exists, the pre-stored interferer utility maximization algorithm and the visible light communication network algorithm are repeatedly performed to estimate the transmission power and sub-channel that maximizes the transmission efficiency of visible light communication, and the estimated sub-channel is used. change the communication channel;
wherein the interferer utility maximization algorithm finds an interference power that maximally reduces the SINR of a visible light communication network based on a preset interferer battery energy.
7. The method of claim 6,
The feedback signal is an error check result of data received by the terminal,
The determining of the existence of the malicious interferer may include determining that the malicious interferer exists if the error is greater than or equal to a preset first threshold as a result of the error check.
delete delete delete

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