A visible light based communication system

Abstract

The application provides a visible light-based communication system, wherein the first visible light receiver and the second visible light receiver each comprise a distance-optimized receiving module, an angle-optimized receiving module and a merging module; the receiving end of the distance-optimized receiving module receives a first visible light signal irradiated at multiple angles, generates a first electric signal and sends the first electric signal to the first receiving end of the merging module through an output end; the receiving end of the angle-optimized receiving module receives the first visible light signal, generates a second electric signal and sends the second electric signal to the second receiving end of the merging module through an output end; the merging module merges the received first electric signal and the second electric signal, generates an optimized electric signal and sends the optimized electric signal to the visible light receiving pin of the first control panel / second control panel through an output end, so that the first control panel / second control panel performs corresponding processing steps according to the optimized electric signal.

Description

Technical Field

[0001] This application relates to the field of communication technology, and more specifically, to a communication system based on visible light. Background Technology

[0002] Radio communication technology has become a crucial infrastructure of modern information society, widely used in mobile communications, the Internet of Things, broadcasting, and other fields. Traditional radio communication relies on electromagnetic waves to propagate information through space, but its application is limited by transmission power and electromagnetic interference. To address this issue, visible light communication (VLC) technology has emerged. This technology utilizes the high-frequency flickering characteristics of LED lighting sources to transmit data, offering advantages such as no electromagnetic radiation, unlicensed spectrum, and the ability to be co-located with lighting equipment.

[0003] Existing visible light communication systems typically consist of LED lights equipped with dedicated modulation circuits and terminal devices with photoelectric sensors, forming an integrated "lighting-communication" network architecture. In typical applications, downlink data is transmitted via the visible light band, while uplink data is mostly transmitted via infrared or radio frequencies. However, current systems have significant drawbacks: high-speed communication can only be achieved when the transmitting and receiving ends maintain a fixed relative position. When the terminal moves, causing the optical path to be blocked or the incident angle to change, the stability of the communication link drops sharply. Summary of the Invention

[0004] The purpose of this application is to provide a visible light-based communication system to solve the technical problem of poor high-speed communication performance in existing visible light communication systems when the distance between the transmitter and receiver is not fixed.

[0005] In a first aspect, the present invention provides a visible light-based communication system. The communication system includes multiple communication terminals and multiple lamp terminals. Each communication terminal includes a first visible light receiver, a first visible light transmitter, and a first control board. Each lamp terminal includes a second visible light receiver, a second visible light transmitter, and a second control board. Both the first and second visible light receivers include a distance optimization receiving module, an angle optimization receiving module, and a merging module. The receiving end of the distance optimization receiving module receives the first visible light signal irradiated from multiple angles and generates a first electrical signal, which is then sent to the first receiving end of the merging module through its output end. The receiving end of the angle optimization receiving module receives the first visible light signal and generates a second electrical signal, which is then sent to the second receiving end of the merging module through its output end. The merging module merges the received first and second electrical signals to generate an optimized electrical signal, which is then sent to the visible light receiving pin of the first / second control board through its output end, so that the first / second control board performs corresponding processing steps according to the optimized electrical signal.

[0006] In an optional embodiment, the distance-optimized receiving module includes a convex lens and a first photodiode. The convex lens is disposed at a first opening on the surface of the housing of the communication terminal and forms a first receiving space with the housing. The first photodiode is disposed within the first receiving space and is located at the focal point of the convex lens.

[0007] In an optional embodiment, the angle optimization receiving module includes a planar transparent mirror and a second photodiode. The planar transparent mirror is disposed at a second opening on the surface of the housing of the communication terminal and forms a second receiving space with the housing. The second photodiode is disposed within the second receiving space and is located on the central axis of the planar transparent mirror.

[0008] In an optional embodiment, the communication terminal further includes a voice receiver, a first control board including a main control chip and a voice processing chip interconnected, the voice receiver being connected to the voice processing chip, and a first visible light emitter including a third photodiode connected to the main control chip.

[0009] The voice receiver receives the voice of the person holding the communication terminal, generates an analog signal, and sends it to the voice processing chip.

[0010] The voice processing chip processes the received analog signals into digital signals and sends them to the main control chip;

[0011] Based on the received digital signal, the main control chip drives the third photodiode to emit the first visible light signal.

[0012] In an optional implementation, the network ports of the second control boards at multiple lamp terminals are connected via network cables to form a local area network.

[0013] In an optional implementation, after the second visible light receiver at the target lamp receives the first visible light signal, it sends the optimized electrical signal to the second control board at other lamps via a local area network.

[0014] The second control boards at the other lamp ends each generate corresponding second visible light signals based on the optimized electrical signals, and transmit them through the second visible light transmitters, so that the first visible light receiver of the communication terminal can receive the second visible light signals at different locations.

[0015] In an optional implementation, the communication terminal further includes a voice player, and the first visible light signal is used to indicate the audio data collected by the voice receiver, the terminal identifier of the communication terminal, and the channel identifier.

[0016] After the main control chip of the communication terminal receives the optimized electrical signal corresponding to the first visible light signal, it determines whether the terminal identifier and channel identifier indicated by the signal have passed the verification.

[0017] If the verification is successful, the corresponding audio data will be played through the voice player.

[0018] In an optional implementation, the communication terminal further includes a display for displaying the channel identifier of the terminal device.

[0019] In an optional implementation, the communication terminal further includes a communication button.

[0020] The main control chip responds to the communication signal triggered by the communication button, controlling the voice receiver to start collecting sound.

[0021] In an optional implementation, after the second visible light receiver at the target lamp receives the first visible light signal, it sends the optimized electrical signal through the local area network to the second control board of all other lamps under the current channel identifier.

[0022] This application provides a visible light-based communication system, wherein the communication system includes multiple communication terminals and multiple lamp terminals. Each communication terminal includes a first visible light receiver, a first visible light transmitter, and a first control board. Each lamp terminal includes a second visible light receiver, a second visible light transmitter, and a second control board. Both the first and second visible light receivers include a distance optimization receiving module, an angle optimization receiving module, and a merging module. The receiving end of the distance optimization receiving module receives first visible light signals irradiated from multiple angles and generates a first electrical signal, which is then sent to the first receiving end of the merging module via its output end. The receiving end of the angle optimization receiving module receives the first visible light signals and generates a second electrical signal, which is then sent to the second receiving end of the merging module via its output end. The merging module merges the received first and second electrical signals to generate an optimized electrical signal, which is then sent to the visible light receiving pin of the first / second control board via its output end, so that the first / second control board performs corresponding processing steps based on the optimized electrical signal. By adding optical components to the visible light receiver, the receiver can receive light at a wider angle and over a longer distance, thereby reducing the limitations of visible light communication networks in terms of angle and distance. This allows for good high-speed communication even when the transmitter and receiver are moving relative to each other. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a visible light-based communication system provided in an embodiment of this application;

[0025] Figure 2 A schematic diagram of the logic control structure of a communication terminal provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram of a logic control structure for a lamp terminal provided in an embodiment of this application. Detailed Implementation

[0027] First, the application scenarios of this application will be described. The technical solution of this application can be applied to visible light communication.

[0028] Existing visible light communication systems transmit downlink data via the visible light band, while uplink data is mostly transmitted via infrared or radio frequencies, forming an integrated "lighting-communication" network architecture. However, traditional visible light communication systems suffer from poor mobile reception, limited coverage, and are unsuitable for certain scenarios where infrared signals are restricted.

[0029] Based on this, this application provides a communication system based on visible light.

[0030] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0031] Example 1

[0032] Figure 1 This is a schematic diagram of a visible light-based communication system provided as an embodiment of this application. Figure 1 As shown, the communication system includes multiple communication terminals and multiple lamp terminals. The specific number of communication terminals and lamp terminals is not limited here.

[0033] The communication terminal includes a first visible light receiver, a first visible light transmitter, and a first control board. The first visible light transmitter can be an LED light.

[0034] The lamp includes a second visible light receiver, a second visible light emitter, and a second control board. The second visible light emitter can be an LED lamp.

[0035] In visible light communication systems, for engineering reasons, LED lights also need to serve an illumination function; therefore, the light from LEDs is usually diffused. Based on the characteristics of light, the more focused the light, the higher its energy, and the more communication data can be transmitted, achieving a higher transmission rate, but the transmission distance will be shorter.

[0036] In this embodiment, the visible light emitter has an illumination function and performs optical modulation on all downlink data. While the LED light disperses the light, this application also performs large-angle, long-distance light focusing and collection on the visible light receiver.

[0037] Both the first and second visible light receivers include a distance-optimized receiving module, an angle-optimized receiving module, and a merging module.

[0038] The distance optimization receiving module here may include a convex lens and a first photodiode. The convex lens is disposed at a first opening on the surface of the communication terminal's housing, forming a first receiving space with the housing. The first photodiode is disposed within the first receiving space and located at the focal point of the convex lens. The receiving end of the distance optimization receiving module receives a first visible light signal irradiated from multiple angles, generates a first electrical signal, and sends it to the first receiving end of the merging module through its output end.

[0039] Specifically, the convex lens here can be mounted on the opening on the front housing surface of the communication terminal / lamp terminal via a mounting bracket. The front housing and the rear housing are fixed together by a snap-fit ​​mechanism.

[0040] The angle optimization receiving module includes a planar transparent mirror and a second photodiode. The planar transparent mirror is disposed at a second opening on the surface of the communication terminal's housing, forming a second receiving space with the housing. The second photodiode is disposed within the second receiving space and located on the central axis of the planar transparent mirror. The second photodiode can receive incident light with an incident angle of 30° to 150° through the planar transparent mirror. The receiving end of the angle optimization receiving module receives a first visible light signal, generates a second electrical signal, and sends it to the second receiving end of the merging module through its output end.

[0041] The planar transparent mirror here can be glued to the opening on the front housing surface of the communication terminal / lamp end. The planar transparent mirror can be made of transparent acrylic sheet, transparent glass, or other transparent materials.

[0042] Specifically, when an external light source shines perpendicularly onto the convex lens, the light is focused onto the first photodiode. Under the same light intensity, the focusing effect of the convex lens increases the current in the diode. Even when the distance between the light source and the receiver increases, the receiver with the convex lens can still receive signals from a distance. The angle-optimized receiving module can also receive incident light with a large angle of incidence, achieving wide-angle signal reception.

[0043] When a visible light source shines on a photodiode at an angle (not perpendicular), the convex lens above the first photodiode has a very small focusing angle, resulting in a weak signal on the first photodiode. At this time, the second photodiode, acting as a plane mirror, receives the light source signal with a certain incident angle.

[0044] The merging module merges the received first and second electrical signals to generate an optimized electrical signal, which is then sent to the visible light receiving pin of the first / second control board via the output terminal, so that the first / second control board can perform the corresponding processing steps according to the optimized electrical signal.

[0045] The combining module combines the first and second electrical signals. Specifically, it can employ various signal combining algorithms such as Maximum Ratio Combining (MRC), Equal Gain Combining (EGC), Selection Combining (SC), and Switching Combining; no specific limitations are specified here. The optimized electrical signal output by the combining module combines the first electrical signal from the distance-optimized receiving module and the second electrical signal from the angle-optimized receiving module, which can significantly reduce the probability of signal fading and ensure communication quality.

[0046] This application provides a visible light-based communication system that, by adding optical devices to the visible light receiver, enables the receiver to receive light at a wider angle and over a longer distance, thereby alleviating the limitations of visible light communication networks in terms of angle and distance. This system can achieve good high-speed communication even when the transmitter and receiver are moving relative to each other.

[0047] Example 2

[0048] In one embodiment of this application, a communication method based on a visible light communication system is provided.

[0049] The network ports of the second control boards for multiple lamp terminals are connected via network cables to form a local area network (LAN). Different lamp terminals can exchange signals.

[0050] The communication terminal here also includes a voice receiver and a voice player. The first control board includes a main control chip and a voice processing chip that are interconnected. The voice receiver is connected to the voice processing chip. The first visible light emitter includes a third photodiode, which is connected to the main control chip.

[0051] The chip here can be an MCU (Microcontroller Unit), etc.

[0052] The voice receiver can be a microphone used to collect the user's voice. The voice receiver receives the user's voice, generates an analog signal, and sends it to the voice processing chip. The voice processing chip processes the received analog signal into a digital signal and sends it to the main control chip. Based on the received digital signal, the main control chip drives a third photodiode to emit a first visible light signal. The voice player can be an amplifier and a speaker. The communication terminal may also include a headphone jack for the user to use headphones.

[0053] After receiving the first visible light signal, the second visible light receiver at the target lamp end sends the optimized electrical signal to the second control boards at other lamp ends via the local area network. Each of the second control boards at the other lamp ends generates a corresponding second visible light signal based on the optimized electrical signal and transmits it through a second visible light transmitter, enabling the first visible light receiver at the communication terminal to receive the second visible light signal. The communication terminal can then convert the received first visible light signal into corresponding audio data and play it.

[0054] For example, communication terminal A can convert the holder's voice into a corresponding visible light signal and send it to lamp terminal A. Lamp terminal A can receive the first visible light signal through a second visible light receiver and forward it to lamp terminal B via a network cable. Lamp terminal B, based on the optimized electrical signal, converts it into a corresponding second visible light signal through a second control board and sends it to communication terminal B through a second visible light transmitter. Communication terminal B receives the signal through the first visible light receiver and plays it through a voice player.

[0055] In one implementation, to avoid communication channel congestion, each communication terminal can be preset with a corresponding communication terminal ID. The second control board at the lamp end can store all communication terminal IDs, and the lamp end establishes a data transmission channel by identifying the communication terminal ID.

[0056] The first visible light signal emitted by the communication terminal or the lamp terminal is used to indicate the audio data collected by the voice receiver, and can also indicate the terminal identifier and channel identifier of the corresponding communication terminal.

[0057] The lamp identifies the terminal identifier and channel identifier indicated by the first visible light signal sent by the communication terminal. For different channel identifiers, frequency division multiplexing can be achieved based on hybrid multiplexing technology, where different channels use different sub-frequency bands. Specifically, this can include spatial multiplexing (SDM) and frequency division multiplexing (FDM) methods, such as MIMO-OFDM, which achieves spatial multiplexing through multiple transmit and receive arrays in the system.

[0058] For example, after the main control chip of the communication terminal receives the optimized electrical signal corresponding to the first visible light signal, it determines whether the terminal identifier and channel identifier indicated by the signal have passed verification. If the verification is successful, the corresponding audio data is played through the voice player.

[0059] This allows the lamp to connect to multiple communication terminals, avoiding communication confusion between different terminals.

[0060] Example 3

[0061] In this embodiment, a communication terminal and a lamp terminal are provided.

[0062] The logic control structure schematic diagram of the communication terminal can be as follows: Figure 2 As shown. The communication terminal can be a handheld terminal. The communication terminal may include a first visible light receiver, a first visible light transmitter, and a first control board. The first control board may include a main control chip, a voice processing chip, a charging management chip, an EEPROM chip, a FLASH chip, and a fuel gauge chip that are interconnected.

[0063] The communication terminal also includes a display screen, which shows the terminal device's channel identifier, terminal name, and other information. It can also display information such as the communication terminal's operating status, battery level, and volume.

[0064] The main control chip of the communication terminal is connected to indicator lights via GPIO pins. These indicator lights can indicate the terminal's operating status, battery / charging status, voice upload / answer prompts, etc. These indicator lights can be red-green dual-color LEDs.

[0065] In an optional implementation, the communication terminal also includes communication buttons, with the main control chip connected to the buttons via GPIO pins. The main control chip responds to a communication signal triggered by the communication buttons, controlling the voice receiver to begin acquiring sound. Multiple buttons can be used, for controlling "volume up," "volume down," "PTT," "channel switching," and "power on / off." Power on / off control, volume up / down control, and channel switching control are unaffected by service requirements and can be adjusted by the user at any time. The PTT control button's effectiveness is affected by service requirements; it only functions to control voice services after successfully acquiring channel resources.

[0066] The main control chip of the communication terminal is also connected to a TYPE-C interface via the SWD / USART pin. The TYPE-C interface can be used for battery charging, program burning, and communication, and can also be used as a headphone jack.

[0067] The main control chip of the communication terminal is also connected to the battery voltage acquisition circuit through the ADC pin to monitor the battery status.

[0068] The main control chip of the communication terminal is also connected to the power meter chip via IIC / GPIO pins, the charging management chip via GPIO pins, the Flash chip via SPI pins, and the EEPROM chip via IIC pins.

[0069] The main control chip of the communication terminal is connected to the output of the merging module via a detector operational amplifier and a comparator circuit. The main control chip of the communication terminal is connected to the detector operational amplifier and comparator circuit through the USART pin.

[0070] The main control chip of the communication terminal is connected to the voice processing chip via IIC / SPI pins. The voice processing chip is used for signal encoding and decoding. The analog signal collected by the microphone is converted into a digital signal, encoded and modulated by the voice processing chip, and sent to the main control chip. The main control chip drives the corresponding LEDs based on the received modulated signal, thus converting the sound signal into a light signal.

[0071] In a specific embodiment, the communication terminal can actively connect to the light source. If the communication terminal does not receive a heartbeat packet from the light source within a timeout period, it automatically goes offline. When the communication terminal is placed under the light, it automatically initiates connection. This function ensures that the communication terminal is controlled by the system after joining the network, guaranteeing the orderliness and security of concurrent optical path interaction among multiple users under the light.

[0072] After two minutes of inactivity, the communication terminal automatically turns off its screen and other peripherals, entering sleep mode. While in sleep mode, the terminal retains its ability to monitor services. It automatically exits sleep mode upon detecting any event, such as a status change or the presence of service activity.

[0073] After successful network access, the communication terminal can provide voice services to users. When the communication terminal detects that a user has pressed the PTT button, it requests channel resources from the lamp terminal, collects sound through the microphone, compresses it, and uploads it to the lamp terminal via the optical path. Simultaneously, it displays a prompt on the screen to complete the voice upload. When the communication terminal listens to the optical signal sent by the lamp terminal, it automatically analyzes the optical signal. If the terminal identifier and channel identifier are correct, it decodes and plays the signal, and can also display a prompt on the screen.

[0074] The logic control structure schematic diagram at the lamp end can be shown as follows: Figure 3 As shown. The lamp end is equipped with a TYPE-C interface, a DC interface, an LED lamp control interface, a visible light receiver port, an Ethernet interface, and an indicator light control interface.

[0075] The TYPE-C interface connects to the main control chip at the lamp end via SWD or USART pins for programming and communication. The DC (power) interface outputs switching signals to the LED driver board. The visible light receiver port receives optimized electrical signals. The Ethernet port enables bidirectional data transmission with other lamp ends. The LED control interface connects to the main control chip at the lamp end via USART pins to control the LEDs to emit visible light signals. The indicator light control interface connects to the main control chip at the lamp end via GPIO pins to control the indicator lights. The indicator lights display the operating status of the lamp.

[0076] The second visible light receiver, the second visible light emitter, and the second control board at the lamp end can be integrated into the same housing or formed independently. For example, the second control board and the main body of the second visible light emitter can be deployed on the ceiling, and the main body of the second visible light receiver can be deployed on the ceiling or a wall.

[0077] After the communication system is initialized, once the communication terminal successfully connects to the lamp terminal, the lamp terminal can record the terminal identifier and channel identifier of the communication terminal and start periodically polling the terminal. If the terminal does not respond within the timeout period, it is considered offline and all resources occupied by the device are released.

[0078] The lamp terminal can automatically listen to voice packets reported by the terminal and transmit the optimized electrical signal corresponding to the voice data reported by the communication terminal as a network packet to other lamp terminals in the local area network. The lamp terminal also automatically listens to network packets in the local area network and sends the network packets to the communication terminal as an optical signal.

[0079] When the lamp receives a network access / offline or voice request from the communication terminal, the lamp can also determine whether the channel resources meet the requirements and send a response to the communication terminal based on the determination result.

[0080] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0081] Furthermore, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0083] It should be noted that if the function is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0084] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0085] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A visible light-based communication system, characterized in that, The communication system includes multiple communication terminals and multiple lamp terminals. Each communication terminal includes a first visible light receiver, a first visible light emitter, and a first control board. Each lamp terminal includes a second visible light receiver, a second visible light emitter, and a second control board. Both the first and second visible light receivers include a distance-optimized receiving module, an angle-optimized receiving module, and a merging module. The receiving end of the distance optimization receiving module receives the first visible light signal irradiated from multiple angles, generates a first electrical signal, and sends it to the first receiving end of the merging module through the output end; The receiving end of the angle optimization receiving module receives the first visible light signal, generates a second electrical signal, and sends it to the second receiving end of the merging module through the output end; The merging module merges the received first and second electrical signals using a maximum ratio merging algorithm to generate an optimized electrical signal, which is then sent to the visible light receiving pin of the first / second control board via the output terminal, so that the first / second control board can perform corresponding processing steps based on the optimized electrical signal. The network ports of the second control boards at multiple lamp terminals are connected via network cables to form a local area network; The communication terminal also includes a voice receiver, a first control board including a main control chip and a voice processing chip interconnected, the voice receiver being connected to the voice processing chip, and a first visible light emitter including a third photodiode connected to the main control chip. The voice receiver receives the voice of the person holding the communication terminal, generates an analog signal, and sends it to the voice processing chip. The voice processing chip processes the received analog signals into digital signals and sends them to the main control chip; Based on the received digital signal, the main control chip drives the third photodiode to emit the first visible light signal; After receiving the first visible light signal, the second visible light receiver at the target lamp end sends the optimized electrical signal to the second control board at other lamp ends via the local area network; The second control boards at other lamp ends each generate corresponding second visible light signals according to the optimized electrical signals, and transmit them through the second visible light transmitters, so that the first visible light receiver of the communication terminal can receive the second visible light signals at different positions. The communication terminal also includes a voice player, and the first visible light signal is used to indicate the audio data collected by the voice receiver, the terminal identifier of the communication terminal, and the channel identifier. After the main control chip of the communication terminal receives the optimized electrical signal corresponding to the first visible light signal, it determines whether the terminal identifier and channel identifier indicated by the signal have passed the verification. If the verification is successful, the corresponding audio data will be played through the voice player.

2. The system according to claim 1, characterized in that, The distance-optimized receiving module includes a convex lens and a first photodiode. The convex lens is disposed at a first opening on the surface of the casing of the communication terminal and forms a first receiving space with the casing. The first photodiode is disposed within the first receiving space and is located at the focal point of the convex lens.

3. The system according to claim 1, characterized in that, The angle optimization receiving module includes a planar transparent mirror and a second photodiode. The planar transparent mirror is disposed at a second opening on the surface of the housing of the communication terminal and forms a second receiving space with the housing. The second photodiode is disposed within the second receiving space and is located on the central axis of the planar transparent mirror.

4. The system according to claim 1, characterized in that, The communication terminal also includes a display for displaying the channel identifier of the terminal device.

5. The system according to claim 1, characterized in that, The communication terminal also includes communication buttons. The main control chip responds to the communication signal triggered by the communication button, controlling the voice receiver to start collecting sound.

6. The system according to claim 1, characterized in that, After receiving the first visible light signal, the second visible light receiver at the target lamp end sends the optimized electrical signal through the local area network to the second control board of all other lamp ends under the current channel identifier.

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