WO2014166268A1

WO2014166268A1 - Multiple-input and multiple-output visible light transmitting device and method and receiving device and method

Info

Publication number: WO2014166268A1
Application number: PCT/CN2013/088637
Authority: WO
Inventors: 支周; 许超; 杨涛; 韦玮; 禹忠; 吕宁
Original assignee: 中兴通讯股份有限公司
Priority date: 2013-07-26
Filing date: 2013-12-05
Publication date: 2014-10-16
Also published as: CN104348545B; CN104348545A

Abstract

A multiple-input and multiple-output visible light transmitting device and method and receiving device and method. The transmitting device comprises: a signal transmitting unit and a signal modulation unit. The signal transmitting unit comprises an array consisting of 1 or more light-emitting components, where the light-emitting components are for use in emitting visible lights, and the visible lights emitted by different light-emitting components are of different frequencies. The signal modulation unit is configured as: to load a signal of each channel onto the visible light of one frequency, where the signals loaded onto the visible lights of different frequencies belong to different channels. The receiving device comprises: a signal receiving unit and a signal processing unit. The signal receiving unit comprises along an incident light direction: an incident light collimating device, a layer of substrate, and a detection array chip. A light-blocking layer is attached onto a surface of the substrate that is perpendicular to an incident light. A diffraction hole two-dimensional array constituted by 2 or more diffraction holes having different aperture sizes is arranged on the light-blocking layer. The detection array chip comprises 2 or more detection pixel elements.

Description

Multiple input multiple output visible light emitting device, method and receiving device and method

Technical field

The present invention relates to a multiple-input multiple-output (MIMO) visible light communication system, and more particularly to a multiple input multiple output visible light emitting device, method and receiving device and method.

Background technique

Visible Light Communications (VLC) is a wireless communication technology that uses visible light with a frequency between 390 ΤΗζ (wavelength 770 nm) and 857 ΤΗζ (wavelength 350 nm) as a communication medium to complete information transmission.

In recent years, with the rapid development of semiconductor technology, visible light communication based on LED (Light Emitting Diode) illumination has been greatly developed as a wireless access technology. The use of LED visible light signal transmission data has the following advantages: LED light source has the characteristics of low power consumption, long service life, small size, easy drive, green environmental protection, etc. It provides high-speed data transmission without electromagnetic interference while illuminating, and solves the problem of broadband radio system. The problem of narrow frequency band and electromagnetic interference is that the visible light communication technology, as a replacement or supplement technology for indoor communication in radio communication technology, has great development prospects and has attracted wide attention and research.

In order to improve communication capacity, frequency division multiplexing or wavelength division multiplexing is commonly used for both radio communication and fiber-optic communication. Compared to single frequency communication, the frequency division multiplexing technique uses multi-frequency transmission signals. The electromagnetic wave of each frequency can transmit different signals as an independent signal carrier, thereby greatly improving the communication capacity. However, the receiving end of the radio frequency division multiplexing needs to configure the antenna to receive the electromagnetic wave signal and convert the electromagnetic wave into an electric signal. The effect of receiving the information has a great relationship with the performance of the antenna and the position of the antenna. Separating the signals at different frequencies in the channel requires the use of a bandpass filter, but the filtering characteristics are not ideal. There are also nonlinear effects in the channel, etc., so it is easy to generate inter-path interference and waveform distortion. In the wavelength division multiplexing technology of optical fiber communication, a grating is usually used as a demultiplexer, but the grating is generally bulky, and it is difficult to separate signals having very close frequencies.

The newly developed visible light MIMO technology is based on the concept of frequency division multiplexing. Multiple light sources are used to transmit optical signals of multiple frequencies. At the signal receiving end, frequency dividing devices are used to transmit signals of various frequencies. The numbers are extracted separately. The conventional frequency division multiplexing receiving system is large in size and low in frequency resolution, and it is inconvenient to integrate in a small mobile device such as a mobile phone.

Summary of the invention

It is an object of the present invention to provide a multiple input multiple output visible light emitting device, method and receiving device and method for overcoming the disadvantages of a conventional frequency division multiplexing receiving system having a large volume and a low frequency resolution.

In order to solve the above problems, the present invention provides a multiple input multiple output visible light signal transmitting apparatus, including: a signal transmitting unit and a signal modulating unit;

The signal transmitting unit is configured to: include an array composed of one or more light emitting devices, wherein each of the light emitting devices is configured to emit visible light, and different light emitting devices emit different visible light frequencies; the signal modulation unit is configured to: The signals of one channel are loaded onto the visible light of one frequency, and the signals carried by the visible light of different frequencies belong to different channels; wherein the power of different frequencies changes in power at different times.

Preferably, the signal transmitting unit further includes two or more filters, and the visible light emitted by each of the illuminating devices passes through different filters and the visible light has different frequencies.

Preferably, the light emitting device is a light emitting diode (LED), a field electron emission display (FED) or an organic light emitting diode (OLED).

The present invention also provides a multi-input multi-output visible light signal receiving apparatus, comprising: a signal receiving unit and a signal processing unit;

The signal receiving unit includes, in order of incident light direction, an incident light collimating device, a layer of a substrate and a detecting array chip;

The incident light collimating device is configured to: ensure that incident light is incident perpendicularly on the substrate; a light blocking layer is attached to a surface of the substrate perpendicular to the incident light, and the light blocking layer is provided with 2 a two-dimensional array of diffractive holes composed of diffractive holes having different aperture sizes, the aperture size of each diffractive hole is close to the wavelength of the incident light, and the depth of each diffractive hole is the same as the thickness of the light blocking layer; Including more than 2 detection pixel elements, the position of each detection pixel element Disposing the positions of the respective diffractive holes in the two-dimensional array of the diffractive holes; the detecting array chip is configured to: the detecting signal output end is connected to the signal processing unit, and the visible light of each frequency detected by each detecting pixel element Transmitting power to the signal processing unit; the signal processing unit is configured to: detect, according to the received power of each frequency light detected by each of the detecting pixel elements, and a predicted detection rate of each of the detecting pixel elements for each frequency component, Decompose data for each channel data transmitted by different frequencies of visible light.

Preferably, the signal processing unit is configured to:

Taking the power value of the visible light of each frequency as an unknown number, the received power value detected by each of the detecting pixel elements is used as an augmentation matrix, and the detection rate of each of the detecting pixel elements for each frequency component measured in advance is taken as The coefficient matrix is solved by the regularization method to obtain the power of the visible light at each moment.

Preferably, the incident light collimating means is formed in a columnar shape by a light absorbing material, and the incident light is transmitted through the columnar material.

Preferably, the substrate is made of a transparent material.

Preferably, the light blocking layer is made of an opaque material.

Preferably, the detecting pixel element is a charge coupled device (CCD) or a complementary metal oxide semiconductor element (CMOS).

Preferably, the signal processing unit is further configured to: convert the visible light signal into an electrical signal according to the calculated power of the visible light of each frequency, and then distribute the signal to each subchannel for transmission, and perform demodulation by the demodulator to obtain the original modulation. signal.

Correspondingly, the present invention also provides a multi-input multi-output visible light signal transmitting method, which is applied to a visible light signal transmitting device, and includes:

Each of the light-emitting devices in the visible light signal emitting device emits visible light, wherein frequencies of visible light emitted by different light-emitting devices are different;

The signals of each channel are loaded onto visible light of one frequency, and the signals carried by visible light of different frequencies belong to different channels; wherein, the visible light of different frequencies changes in power at different times. Preferably, the light emitting device is a light emitting diode (LED), a field electron emission display (FED) or an organic light emitting diode (OLED).

Correspondingly, the present invention further provides a method for receiving a multi-input and multi-output visible light signal, which is applied to a visible light signal receiving apparatus, and includes:

The incident light collimating device vertically incidents the incident light onto the substrate;

a light blocking layer is attached to a surface of the substrate perpendicular to the incident light, and a two-dimensional array of diffractive holes composed of two or more diffractive holes having different aperture sizes on the light blocking layer project visible light; wherein each The aperture size of the diffraction aperture is close to the wavelength of the incident light, and the depth of each diffraction aperture is the same as the thickness of the light blocking layer;

The detection array chip includes two or more detection pixel elements, and the positions of the detection pixel elements are offset from the positions of the respective diffraction holes in the two-dimensional array of the diffraction holes; the detection signal output end of the detection array chip and the signal The processing unit is connected to transmit the power of each frequency visible light detected by each detecting pixel element to the signal processing unit;

The signal processing unit solves the channel data of different frequencies of visible light transmission according to the received power of the visible light of each frequency detected by each of the detecting pixel elements and the predicted detection rate of each of the detecting pixel elements for each frequency component. data.

Preferably, according to the received power of each frequency of the visible light detected by each of the detecting pixel elements and the predicted detection rate of each of the detecting pixel elements for each frequency component, performing channel data of different frequency visible light transmissions Solve data, including:

Preferably, the signal processing unit further converts the visible light signal into an electrical signal according to the calculated power of the visible light of each frequency, and then distributes it to each subchannel for transmission, and demodulates by the demodulator to obtain the original modulated signal. Embodiments of the present invention have the following beneficial effects:

1. Using the method of adding a light-emitting device and a filter to obtain visible light of each frequency, the visible light of each frequency only needs to add different filters after the same visible light source, thereby reducing the cost;

2. The visible light signal receiving device can be made of ordinary materials, has small volume, strong anti-vibration interference capability, simple manufacturing process and high integration. The detection array chip can use CCD or CMOS, both of which are mature products that can be easily obtained and integrated into small mobile terminals (such as mobile phones);

3. The frequency distribution of each channel is dense and the frequency distribution range is wide. Since the number of detecting pixel elements of the detecting array chip determines the frequency resolution of the signal receiving device, the frequency range of the visible light signal detectable by the detecting array chip determines the distribution range of each channel frequency, and now the detecting array chip such as CCD, CMOS The detection pixel is easy to reach more than one million to more than 10 million, and its measurement range covers the entire visible light band. Therefore, the MIMO visible light system can achieve high frequency resolution and transmit data over a wide range of visible light signals, thereby greatly Increased signal transmission capacity. BRIEF abstract

1 is a schematic perspective view of a MIMO visible light communication system according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a frequency division method of an incident optical signal used in an embodiment of the present invention; FIG. 3 is a MIMO visible light communication system according to an embodiment of the present invention; The obtained optical signal simulation map. Preferred embodiment of the invention

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the features in the embodiments and the embodiments in the present application may be arbitrarily combined with each other.

In the present embodiment, the visible light communication system includes a signal transmitting device and a signal receiving device. The signal transmitting device includes: a signal transmitting unit and a signal modulating unit; and the signal receiving device includes a signal receiving unit and a signal processing unit. specifically:

The signal transmitting unit includes an array of one or more light emitting devices, each of which is configured to emit visible light. In order to achieve frequency division multiplexing, the signal transmitting unit may further include two or more filters, and visible light emitted by each of the light emitting devices passes through different filters to transmit visible light. The frequencies are different from each other, respectively, fl, f2, G, ... fn; where η is the number of filters; the frequency of visible light emitted by different light-emitting devices is different, and the light-emitting device can be, but not limited to, LEDs used ( Light-Emitting Diode (LED), FED (Field Emission Display) or OLED (Organic Light-Emitting Diode)

The signal modulating unit is configured to respectively load the signal of each channel onto the visible light of a certain frequency, and the signals carried by the visible light of different frequencies belong to different channels; the power of different frequencies of visible light may change at different times;

The signal receiving unit includes, in order of incident light direction, an incident light collimating device, and the light absorbing material is formed into a column shape, and the incident light is transmitted through the columnar material to ensure that the incident light is perpendicularly incident to the two-dimensional array of the diffraction holes; a substrate made of a transparent material; a light blocking layer formed on a surface of the substrate perpendicular to the incident light, the light blocking layer being made of an opaque material having two or more perforations having different aperture sizes The perforation two-dimensional array, the aperture size of each hole is close to the incident light wavelength (the range of incident light wavelength is the range of visible light wavelength, between 350 nm and 770 nm, and the aperture size of each diffraction hole and the wavelength of the incident light are The same or a larger order of magnitude), the depth of each diffraction hole is the same as the thickness of the light blocking layer; the detection array chip includes more than two detection pixel elements, and the detection array chip may be a CCD (Charge-coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), Detecting Array Chips Signal output terminal is connected to the signal processing unit, the probe array chips each pixel detecting a position of the diffraction element array porous two-dimensional position of each staggered hole diffraction;

The signal processing unit is mainly composed of a calculation and analysis component, and is configured to perform data decoding on each channel data of visible light transmission of different frequencies. The process of solving the data is as follows: the power value of the visible light of each frequency is taken as an unknown number; the power value detected by the detecting pixel element at different positions of the detecting array chip is used as an augmentation matrix; each of the different positions of the detecting array chip is measured in advance Detecting the detection rate of each frequency component of the pixel element, and using the detection rate as a coefficient matrix; solving the matrix equation by the regularization method, the power of the visible light of each frequency at a certain moment can be obtained. By continuously and quickly measuring the array chip, the signal processing unit continuously and quickly calculates the power of the visible light at each frequency at each moment, and then knows the signals of the visible light at each frequency. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

The core components of the MIMO visible light communication system of the present invention include:

The array of light emitting devices (in this example, an LED array is taken as an example), an incident light collimating device, a two-dimensional array of diffractive holes, a layer of substrate, and a detecting array chip.

As shown in Figure 1, the LED array 7 is used to transmit visible light of different frequencies, wherein each

The LED emits a visible light signal of a frequency. Lens 6 is an incident light collimating device to ensure that the visible light signal is incident perpendicularly to the two-dimensional array of diffractive apertures. The substrate 3 is made of a transparent material (such as polymer PMMA (poly(decyl acrylate) or PS (polystyrene)); a two-dimensional array of diffractive holes 1 is constructed in the light blocking layer 2 on the surface of the substrate 3, the light blocking layer 2 is made of opaque material and can be made of metal chromium. The two-dimensional array of diffraction holes comprises a series of diffraction holes having different aperture sizes, and the aperture size of each diffraction hole is close to the wavelength of the incident light, and the depth of each diffraction hole is the same. And the thickness of the light blocking layer is equal to; the detecting array chip 5 contains more than one detecting pixel element, and the detecting pixel elements are calibrated to ensure that visible light of the same wavelength and the same power is incident on the detecting pixel elements, and each pixel element The output data is the same; the respective diffraction holes in the two-dimensional array of the diffraction holes are offset from the positions of the respective detection pixel elements in the detection array chip;

At the transmitting end, in order to achieve frequency division multiplexing, visible light of one or more visible light sources may be respectively transmitted through different filters, and the frequencies of the outgoing light passing through the respective filters are different from each other, respectively, fl, f2 , G, ... fn., loading the channel signals to be transmitted to different frequencies fl, f2, G, ... fn visible light, using LED arrays or other arrays of light-emitting elements for visible light signals of different frequencies The power level changes at different times are transmitted.

At the receiving end, the visible light signal first passes through the incident light collimating device to ensure that the visible light signal is perpendicularly incident on the two-dimensional array of the diffractive holes; then, the visible light signal passes through the two-dimensional array of diffractive holes, and transmits the diffractive apertures of different sizes, visible light signals. Different degrees of diffraction occur, and different light intensity distributions are formed under each diffraction hole. Finally, the detected pixel elements in the detection array chip measure different visible light powers, and the detected data can be composed into a linear equation: the power value of visible light in each incident light is used as an unknown number, and the different positions of the array chip are detected. Detecting the value detected by the pixel element as an augmentation matrix, detecting the detection rate of each detecting pixel element at each position of the detecting array chip in advance to each frequency component, and using the detection rate as a coefficient matrix; solving by a regularization method Matrix equation, you can get the power of visible light at each moment. Detecting array The chip continuously and quickly measures, and the signal processing unit continuously and quickly calculates the signal of visible light at each frequency at each moment.

The specific visible light processing method is:

As shown in Figure 2, the abscissa represents the frequency in Hertz; the ordinate is the normalized optical signal power in watts per Hz. The incident light signal is divided into n equal parts according to the frequency by calculus, and each of them takes its center frequency, and the bandwidth of each one is Δ/. It is assumed that the transmitting end emits η visible light signals of different frequencies, each signal occupies a frequency /, and the center frequency of each visible light signal is set to /ι and the bandwidth is Δ/. When the number of signals η is relatively large, then according to the principle of calculus, the entire optical power of the incident light can be expressed by the following formula:

P ₀ =∑P(f^f

j ⁼¹

Where, the signal amplitude is expressed as the frequency. After the incident light passes through the two-dimensional array of the diffraction holes, each of the detecting pixel elements in the detecting array chip can detect the visible light power after the diffraction. On the one hand, the power received by the detecting pixel element can be directly detected by itself; on the other hand, the power detected by the detecting pixel element can also be calculated by the power of the incident light. Because the power of visible light at each frequency (ie, the area of each small rectangle in the figure) is detected to some extent by a pixel element. However, due to the different degrees of diffraction of the diffractive holes of different sizes, the proportion of visible light of each frequency component of the incident light is reduced on each of the detecting pixels. When the device is completed, the reduction ratio is a fixed value, which can be detected by the pixel element by measuring the visible light of each frequency in the incident beam through the two-dimensional array of the diffraction holes and then incident on a certain detection pixel. The rate is calculated. Therefore, an equation can be obtained. The left side of the equation is the power measurement value of the detected pixel element. The right side of the equation group is the power of the visible light of each frequency in the incident light and the detection rate of the detection pixel by the visible light of each frequency of the incident light respectively. The calculated values obtained are added again. It is assumed that the incident light is detected by the i-th detecting pixel element after passing through the two-dimensional array of the diffraction holes, and the visible light power obtained on the detecting pixel element can be expressed as:

Where C _3⁄4 (j=l, 2, . . . , n) are respectively the detection rate of the first detection pixel element with respect to the frequency of visible light. When n detecting pixel elements are selected on the detecting array chip, the n pixel elements can measure a series of powers, and the power can be expressed in the form of a matrix, wherein the detection rate constitutes a coefficient matrix. C, and the detected pixel elements in each detection array chip measure the data to form an augmentation matrix y, which is expressed as follows:

Cx = y

J

Where (3⁄4(ί=1,2,3...η)(ί=1,2,3...η) represents the detection rate of the second detection pixel with respect to the frequency of visible light, the detection rate The ratio of the visible power of the frequency received by the first detecting pixel to the visible power of the frequency in the incident light, when the device is completed, the ratio is a fixed value, which can be measured in advance. The value of the augmented matrix is not an accurate value, and there is a measurement error. The above equations are ill-conditioned equations, which are difficult to calculate by ordinary methods. Therefore, the Tikhonov regularization method can be used to solve the linear equations better. The size of the visible light signal at each frequency of the incident light can be obtained by fitting P(fl), P(f2), ... P(fn).

Since the signal transmitted in the light wave changes with time, the value detected by the detecting array chip also changes with time, so the finally calculated visible light signal size of each frequency also changes with time, thus transforming the visible light signal of each frequency. The electrical signal is divided into sub-channels for transmission, and demodulated by a demodulator to obtain the original modulated signal.

3 is a simulation result of a visible light signal obtained by using the MIMO visible light communication system of the present invention and using the above-described normalization calculation method, which compares a transmitted signal with a received signal. In the figure, the abscissa indicates the wavelength, and the unit is nanometer; the ordinate is Normalize the power of the visible light signal in watts per Hz. The measurement wavelength ranges from 400 nm to 800 nm. As can be seen from the figure, the transmitted signal agrees well with the received signal data.

In addition, in this embodiment, a multi-input and multi-output visible light signal transmitting method is applied to the visible light signal transmitting device, and includes:

Loading the signal of each channel onto visible light of one frequency, and visible light of different frequencies The signals carried belong to different channels; wherein, the visible light of different frequencies changes in power at different times.

Preferably, the light emitting device is a light emitting diode (LED), a field electron emission display (FED) or an organic light emitting diode (OLED)

A multi-input multi-output visible light signal receiving method is applied to a visible light signal receiving device, comprising:

Preferably, according to the received power of each frequency of the visible light detected by each of the detecting pixel elements and the predicted detection rate of each of the detecting pixel elements for each frequency component, the channel data for different frequency visible light transmission To solve the data, specifically:

Preferably, the signal processing unit further converts the visible light signal into an electrical signal according to the calculated power of the visible light of each frequency, and then distributes it to each subchannel for transmission, and uses a demodulator to solve the problem. Adjust to get the original modulated signal.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be accomplished by a program instructing the associated hardware, such as a read-only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware or in the form of a software function module. The invention is not limited to any specific form of combination of hardware and software.

The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. In view of the present invention, various other modifications, equivalents, improvements, etc., should be made without departing from the spirit and scope of the invention. It is included in the scope of protection of the present invention.

Industrial and practical

Embodiments of the present invention have the following beneficial effects:

3. The frequency distribution of each channel is dense and the frequency distribution range is wide. Since the number of detecting pixel elements of the detecting array chip determines the frequency resolution of the signal receiving device, the frequency range of the visible light signal detectable by the detecting array chip determines the distribution range of each channel frequency, and now the detecting array chip such as CCD, CMOS The detection pixel is easy to reach more than one million to more than 10 million, and its measurement range covers the entire visible light band. Therefore, the MIMO visible light system can achieve high frequency resolution and transmit data over a wide range of visible light signals, thereby greatly Increased signal transmission capacity.

Claims

Claim

A multiple input multiple output visible light signal transmitting apparatus, comprising: a signal transmitting unit and a signal modulating unit;

2. The apparatus according to claim 1, wherein

The signal transmitting unit further includes two or more filters, and the visible light emitted by each of the light emitting devices passes through different filters and the visible light has different frequencies.

3. The apparatus according to claim 1, wherein

The light emitting device is a light emitting diode (LED), a field electron emission display (FED) or an organic light emitting diode (OLED).

4. A multi-input multi-output visible light signal receiving device, comprising: a signal receiving unit and a signal processing unit;

The incident light collimating device is configured to: ensure that incident light is incident perpendicularly on the substrate; a light blocking layer is attached to a surface of the substrate perpendicular to the incident light, and the light blocking layer is provided with 2 a two-dimensional array of diffractive holes composed of diffractive holes having different aperture sizes, the aperture size of each diffractive hole is close to the wavelength of the incident light, and the depth of each diffractive hole is the same as the thickness of the light blocking layer; Including two or more detecting pixel elements, the positions of the detecting pixel elements are offset from the positions of the respective diffraction holes in the two-dimensional array of the diffraction holes; the detecting array chip is configured as: a detecting signal output end and the signal processing unit Connected, the power of each frequency visible light detected by each detecting pixel element is sent to the signal processing unit; the signal processing unit is configured to: according to the received frequencies detected by the detecting pixel elements The power of the light and the predicted detection rate of each of the detecting pixel elements for each frequency component are used to solve data for each channel data transmitted by different frequencies of visible light.

5. The apparatus according to claim 4, wherein the signal processing unit is configured to:

The apparatus according to claim 4, wherein said incident light collimating means is formed in a columnar shape by a light absorbing material, and the incident light is transmitted through the columnar material.

7. The apparatus according to claim 4, wherein the substrate is made of a transparent material.

8. The device of claim 4, wherein the light blocking layer is made of an opaque material.

9. The apparatus according to claim 4, wherein the detecting pixel element is a charge coupled device (CCD) or a complementary metal oxide semiconductor device (CMOS).

10. The apparatus according to claim 4, wherein

The signal processing unit is further configured to: convert the visible light signal into an electrical signal according to the calculated power of the visible light of each frequency, and then distribute the signal to each subchannel for transmission, and demodulate by the demodulator to obtain the original modulated signal.

A multi-input multi-output visible light signal transmitting method, which is applied to a visible light signal transmitting device, comprising:

The signals of each channel are loaded onto visible light of one frequency, and the signals carried by visible light of different frequencies belong to different channels; wherein the power of different frequencies changes in power at different times.

12. The method of claim 11 wherein

13. A multi-input multi-output visible light signal receiving method, which is applied to a visible light signal receiving device, comprising:

14. The method of claim 13 wherein

And performing, according to the received power of each frequency of the visible light detected by each of the detecting pixel elements, and the predicted detection rate of each of the detecting pixel elements for each frequency component, and performing data decoding on each channel data of different frequency visible light transmission, Includes:

15. The method of claim 13 wherein

The signal processing unit further converts the visible light signal into an electrical signal according to the calculated power of the visible light of each frequency, and then distributes it to each subchannel for transmission, and demodulates by the demodulator to obtain the original modulated signal.