A method for visible light communication for display and MIMO systems

Abstract

The application relates to the field of communication and provides a visible light communication method for display and MIMO systems, which comprises the following steps: obtaining to-be-displayed content and to-be-transmitted data; determining the QAM order of each pixel corresponding channel according to the number S of pixels to be lightened at a time for the to-be-displayed content; dividing the to-be-transmitted data into P groups of transmission data so that each group of transmission data is transmitted through a channel; performing QAM mapping on the P groups of transmission data according to the QAM order to generate P groups of QAM symbols; performing OFDM modulation on the P groups of QAM symbols to generate P modulation signals; and driving a micro-LED array to synchronously emit P light signals and perform communication based on the P modulation signals. The application combines the advantages of MIMO and micro-LED, improves the spectral utilization efficiency on the basis of improving the modulation bandwidth, and maximizes the communication rate of the visible light communication system.

Description

Technical Field

[0001] This application relates to the field of communications, specifically to a visible light communication method for display and MIMO systems. Background Technology

[0002] With the increasingly widespread application of communication technology in people's lives, radio frequency (RF) spectrum resources are becoming increasingly scarce, making the utilization of more spectrum resources a recent research hotspot. The visible light band possesses abundant spectrum resources, thus attracting significant attention as a novel information carrier. The rapid on / off characteristic of LEDs has led to the emergence of LED-based visible light communication. How to achieve higher transmission rates in VLC (Visible Light Communication) is currently a key research focus. Micro-LEDs, as a novel light source, possess characteristics of high current density, high brightness, and high modulation bandwidth. The modulation bandwidth of micro-LEDs can reach hundreds or even thousands of megahertz, significantly improving the signal bandwidth of VLC systems compared to the approximately ten megahertz modulation bandwidth of ordinary LEDs. Furthermore, micro-LEDs, with their micrometer-level dimensions, offer high-resolution display capabilities, and their extremely small transmitter size allows for integration with chips. DCO-OFDM modulation technology, an OFDM modulation technique optimized for optical communication, improves the bandwidth utilization of VLC systems. Equalizers reduce inter-symbol interference and signal waveform tailing; software pre-equalization is easier to optimize parameters for specific systems than hardware equalization, and single-tap equalizers in OFDM systems achieve good equalization results. Imaging MIMO, by using lenses or lens arrays, focuses the optical signal onto the detector, significantly reducing inter-channel interference and fully utilizing spatial resources to achieve higher spectral efficiency. VLC systems based on micro-LEDs combined with OFDM and imaging MIMO technologies have the capability to achieve communication rates of tens or even hundreds of Gbps.

[0003] In existing imaging MIMO technologies, imaging lenses are used to image the light signals generated by an LED array onto a camera array, with each transmitting unit corresponding to a receiving unit. A feedback control module is also designed to initiate an adaptive modulation mode based on the uplink light signal carrying modulation parameters. The drawbacks of existing technologies are that the system uses ordinary commercial LEDs as the signal transmission source. The small bandwidth of ordinary commercial LEDs and the low sampling rate of the camera greatly limit the system's transmission rate, and no equalizer is added to increase bandwidth. Furthermore, adding transmitting units requires increasing the number of transmitting LEDs, which would multiply the size of the transmitting end, hindering integration with chips, increasing the complexity of the imaging lens's optical path design and system architecture, and making the steps to reduce inter-channel interference more complex.

[0004] Another existing technology is a visible light adaptive spatial modulation method. This method sets a system interference tolerance and selectively illuminates the LED array when the interference level does not exceed the tolerance value. That is, it selects a few specific LEDs in the MIMO transmitter array to participate in information transmission, thereby reducing inter-channel interference. The drawback of this existing technology is that commercial LED arrays are limited by low bandwidth, resulting in limited transmission rates. Selectively illuminating only some LEDs to reduce inter-channel interference further reduces information transmission efficiency. Furthermore, selectively illuminating LEDs does not achieve display functionality. In a communication system, the communication rate is directly proportional to the system bit error rate; reducing the communication rate can reduce the bit error rate. This method sacrifices communication rate to reduce the bit error rate and is not suitable for scenarios requiring high communication rates. Summary of the Invention

[0005] In view of this, the present invention proposes a visible light communication method for display and MIMO systems, which combines the advantages of both MIMO and micro-LED. It improves the spectrum utilization efficiency while increasing the modulation bandwidth, maximizes the communication rate of the visible light communication system, and ensures stable communication rate and bit error rate below the threshold when displaying different content.

[0006] According to a first aspect of the present invention, a visible light communication method for a display and MIMO system is provided, the MIMO system including a micro-LED array for displaying and emitting optical signals, adjusting in real time when displaying different content to ensure stable communication rate and a bit error rate below a threshold; the method includes:

[0007] Get the content to be displayed and the data to be transmitted;

[0008] Based on the number S of pixels that need to be lit at one time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined, wherein the value of S is greater than or equal to 2.

[0009] The data to be transmitted is divided into P groups of data for transmission, such that each group of data is transmitted through a channel, where S≥P≥2;

[0010] Based on the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols; and OFDM modulation is performed on the P groups of QAM symbols to generate P modulation signals.

[0011] Based on the P modulation signals, the micro-LED array is driven to synchronously transmit P optical signals and communicate; wherein, during the communication process, the illuminated pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed, so as to achieve real-time adjustment.

[0012] Preferably, determining the QAM order of the channel corresponding to each pixel based on the number S of pixels S that need to be lit at one time for the content to be displayed includes:

[0013] Test signals are simultaneously transmitted to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a user-defined value;

[0014] The QAM order of each subcarrier in each channel is calculated based on the relationship between signal-to-noise ratio (SNR) and QAM order, whereby the relationship between SNR and QAM order is expressed as follows:

[0015]

[0016] Wherein, MN represents the QAM order of the Nth subcarrier, SNR gap is the difference between the actual channel capacity and the theoretical channel capacity set according to the channel conditions, and SNR is the signal-to-noise ratio of the channel.

[0017] Preferably, the step of simultaneously transmitting test signals to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel includes:

[0018] Obtain the received and transmitted symbols of N subcarriers in each channel;

[0019] The error vector magnitude (EVM) of the N subcarriers is determined based on the received and transmitted symbols.

[0020] Based on the error vector magnitude EVM, the signal-to-noise ratio of each of the N subcarriers in each channel is determined.

[0021] Preferably, according to the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols, including:

[0022] Each group of transmitted data is divided into N groups of sub-data, so that each group of sub-data is carried on a subcarrier;

[0023] The sub-data on each subcarrier is modulated into QAM symbols of the QAM order corresponding to the current subcarrier, generating N QAM symbols. These N QAM symbols are a set of QAM symbols corresponding to the current transmitted data, thus obtaining P sets of QAM symbols.

[0024] Preferably, the P groups of QAM symbols are respectively subjected to OFDM modulation to generate P modulated signals, including:

[0025] Pilot signals for channel estimation are inserted into each of the N QAM symbols contained in each group of QAM symbols to generate N frequency domain signals;

[0026] Each frequency domain signal is converted to the time domain using IFFT, generating N time domain signals;

[0027] Each time-domain signal is converted from parallel to serial, and a cyclic prefix is ​​added to the front end of the OFDM frame to generate a modulation signal corresponding to a set of QAM symbols, thereby obtaining P modulation signals corresponding to P sets of transmitted data.

[0028] Preferably, the step of driving the micro-LED array to synchronously transmit P optical signals and perform communication based on the P modulation signals includes:

[0029] The P modulation signals are combined with a DC bias voltage to drive the micro-LED array to emit P optical signals.

[0030] The P-path optical signals are sequentially subjected to spot separation and spot focusing to generate P-path intermediate optical signals;

[0031] The P-channel intermediate optical signals are photoelectrically converted and the electrical signals are converted into digital signals to obtain P groups of digital signals;

[0032] The P groups of digital signals are sequentially demodulated using OFDM and QAM to obtain the P groups of demodulated data.

[0033] Preferably, combining the P modulation signals with a DC bias voltage to drive the micro-LED array to emit P optical signals includes:

[0034] The P modulation signals are imported into the waveform generator of the MIMO system to generate P analog signals;

[0035] The P analog signals are combined with a DC power supply, and P driving electrical signals are generated through a T-type biaser.

[0036] The P driving electrical signals are respectively applied to the corresponding pixels in the micro-LED array.

[0037] Preferably, the step of sequentially performing OFDM demodulation and QAM demapping on the P groups of digital signals to obtain P groups of demodulated data includes:

[0038] For each group of digital signals, sequentially perform cyclic prefix removal, serial-to-parallel conversion, FFT, channel estimation, QAM demapping, and parallel-to-serial conversion to generate P groups of demodulated data.

[0039] Preferably, the step of sequentially performing spot separation and spot focusing on the P-path optical signals to generate P-path intermediate optical signals includes:

[0040] A single convex lens is used to separate the P-path optical signals to generate P-path separated optical signals.

[0041] The P-path separated optical signal is focused using a lens array to generate the P-path intermediate optical signal.

[0042] Preferably, the MIMO system includes 16 receivers and 16 transmitters;

[0043] When the micro-LED array has a -3dB modulation bandwidth of 200MHz, the communication rate of the MIMO system reaches 37Gbps.

[0044] The beneficial effects of the present invention are that the visible light MIMO communication system based on micro-LED array of the present invention uses micro-LED to form a 4×4 array as the emission source, replacing the traditional ordinary LED array. The emission source is extremely small, and only a convex lens is needed to separate the light path. The emission end does not require a complex lens array, does not occupy space, and is conducive to subsequent industrial integration.

[0045] Secondly, this invention combines communication and display through an algorithm, ensuring that changes in display content do not affect communication quality, thus guaranteeing the effective operation of the micro-LED array in terms of communication and display functions, and has the potential to realize a new generation of optical interconnects.

[0046] Furthermore, this invention uses micro-LED as a light source. Micro-LED has the characteristic of high modulation bandwidth, which is tens of times higher than that of ordinary LED, and can effectively improve the data rate of visible light communication.

[0047] Finally, this invention combines MIMO and micro-LED, taking advantage of the advantages of both to improve spectrum utilization efficiency while increasing modulation bandwidth, thereby maximizing the communication rate of visible light communication systems. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a flowchart illustrating a visible light communication method for display and MIMO systems according to the present invention.

[0050] Figure 2 This is a schematic diagram of the DCO-OFDM principle combined with the QAM order adjustment algorithm in an embodiment of the present invention;

[0051] Figure 3This is a schematic diagram of the structure of a MIMO communication integration system according to an embodiment of the present invention;

[0052] Figure 4 This is a schematic diagram illustrating the display effect of a micro-LED array in a MIMO communication integrated system according to an embodiment of the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] The terms “comprising” and “having”, and any variations thereof, in this application are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0055] According to one embodiment of the present invention, Figure 1 This is a flowchart illustrating a visible light communication method for display and MIMO systems according to the present invention, as shown below. Figure 1 As shown, the present invention provides a visible light communication method for display and MIMO systems, comprising:

[0056] Get the content to be displayed and the data to be transmitted;

[0057] Based on the number S of pixels that need to be lit at one time for the content to be displayed, determine the QAM order of the channel corresponding to each pixel, where the value of S is greater than or equal to 2.

[0058] The data to be transmitted is divided into P groups for transmission, so that each group of data is transmitted through a channel, where S≥P≥2;

[0059] Based on the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols; and OFDM modulation is performed on the P groups of QAM symbols to generate P modulated signals.

[0060] Based on P modulation signals, the micro-LED array is driven to synchronously transmit P optical signals and communicate; during the communication process, the illuminated pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed, so as to achieve real-time adjustment.

[0061] In this embodiment, the MIMO system includes a micro-LED array for displaying and emitting optical signals. This array adjusts in real time when displaying different content, ensuring stable communication rates and a bit error rate below a threshold. This invention uses a 4×4 array of 40μm micro-LEDs as the emission source. The modulation bandwidth of micro-LEDs is nearly a hundred times higher than that of ordinary LEDs. A single visible light communication link using micro-LEDs can achieve a communication rate of several Gbps. Parallel data transmission using the micro-LED array can reach communication rates of tens of Gbps. Furthermore, it can combine display and illumination, and the communication quality remains unchanged regardless of changes in the displayed content, ensuring the effective operation of the micro-LED array for both communication and display functions.

[0062] The content to be displayed and the data to be transmitted obtained above are N-channel binary bitstreams generated using MATLAB software on a PC. The value of N ranges from 0 to 16, and depends on how many S pixels need to be lit up for the content to be displayed. The QAM order of each pixel is determined by the pixel density. Optionally, the value of S is greater than or equal to 2.

[0063] The QAM order adjustment algorithm that balances communication and display is as follows:

[0064] Before communication, a binary phase-shift keying signal is first transmitted to test the signal-to-noise ratio (SNR) of the channel corresponding to a single pixel. The SNR is derived from the error vector amplitude of the received data. The correspondence between the SNR and the QAM order calculated using the following formula specifies the QAM order for the channel when the pixel is lit alone:

[0065]

[0066] Where EVM(N) is the error vector magnitude of the Nth subcarrier;

[0067] SNR(N) is the signal-to-noise ratio of the Nth subcarrier;

[0068] Q is the number of binary phase shift keying symbols;

[0069] S kr (N) is the Kth received symbol on the Nth subcarrier;

[0070] S kt (N) is the Kth received symbol on the Nth subcarrier;

[0071] N is the number of subcarriers.

[0072]

[0073] Among them, MN Let be the QAM order of the Nth subcarrier;

[0074] The SNR gap is the difference between the actual channel capacity and the theoretical channel capacity set according to channel conditions. It is adjusted according to the channel quality. SNR is the signal-to-noise ratio of the tested channel.

[0075] When two pixels transmit data together, inter-channel interference increases, leading to a decrease in the signal-to-noise ratio (SNR). If the QAM order used when each pixel is lit individually is still applied after the SNR decreases, the bit error rate (BER) will increase. To control the BER below a threshold, it is necessary to measure the new SNR of the channel when two adjacent pixels transmit data together, and calculate the corresponding QAM order M based on the newly measured SNR. N Once the QAM order is determined for different scenarios, the QAM order can be specified for the channel during actual data transmission without measuring the signal-to-noise ratio during transmission.

[0076] After determining the QAM order, the data to be transmitted is divided into P groups for transmission, so that each group of data is transmitted through a channel, where S≥P≥2;

[0077] The sub-data on each subcarrier is modulated into QAM symbols of the QAM order corresponding to the current subcarrier, generating N QAM symbols. These N QAM symbols are a set of QAM symbols corresponding to the current transmitted data, thus obtaining P sets of QAM symbols.

[0078] Pilot signals for channel estimation are inserted into each of the N QAM symbols contained in each group of QAM symbols to generate N frequency domain signals;

[0079] Each frequency domain signal is converted to the time domain using IFFT, generating N time domain signals;

[0080] Each time-domain signal is converted from parallel to serial, and a cyclic prefix is ​​added to the front end of the OFDM frame to generate a modulation signal corresponding to a set of QAM symbols, thus obtaining P modulation signals corresponding to P groups of transmitted data. These P modulation signals are then combined with a DC bias voltage to drive a micro-LED array, synchronously transmitting P optical signals for communication.

[0081] A lens is installed at the transmitting end, and a lens array is installed at the receiving end to separate and focus the light spot. The P-channel optical signals are sequentially separated and focused to generate P-channel intermediate optical signals. The P-channel intermediate optical signals are received by a photodetector array and converted into digital signals. The electrical signals are then converted into digital signals by an oscilloscope connected to the photodetector to obtain P groups of digital signals. The P groups of digital signals are transmitted to the PC and demodulated using OFDM and QAM to obtain P groups of demodulated data. Finally, the binary bit stream is recovered, and the highest data transmission rate is obtained within the allowable bit error rate.

[0082] Optional, Figure 2 This is a schematic diagram of a DCO-OFDM principle combining a QAM order adjustment algorithm. The OFDM modulation and demodulation described above are all performed offline. Figure 2 As shown, for the transmitting end, the binary data sequence to be transmitted is first converted from serial to parallel to N sets of data. Then, according to the displayed content, a QAM adjustment algorithm is applied, with the data for each channel mapped to a QAM symbol of the corresponding order. After inserting pilots for channel estimation, an IFFT is used to generate a real-valued signal in the time domain. This signal is then converted from parallel to serial to form a modulated signal, and a cyclic prefix is ​​added to the front end of the OFDM frame to eliminate inter-symbol interference. For the receiving end, the received signal undergoes a process of removing the cyclic prefix, serial-to-parallel conversion, FFT, channel estimation, QAM mapping, and parallel-to-serial conversion to reconstruct the binary data and recover the transmitted data. Inserting pilots allows for channel estimation to reduce channel fading; for the receiving end, inserting a cyclic prefix into the received signal reduces inter-symbol interference.

[0083] During communication, the illuminated pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed, so as to achieve real-time adjustment.

[0084] This invention presents a visible light MIMO communication method based on micro-LED arrays. Firstly, it utilizes a 4×4 array of 40μm micro-LEDs as the transmitter. Taking advantage of the fact that micro-LEDs have a modulation bandwidth tens of times higher than ordinary LEDs, reaching hundreds or even thousands of megahertz, and combining this with OFDM modulation, a single channel can achieve a communication rate of several Gbps. By combining OFDM modulation with MIMO, the micro-LED array as the transmitter is extremely small, requiring only a convex lens to separate the optical path. Compared to traditional visible light MIMO systems using ordinary LEDs as the transmitter, the transmitter does not require a complex lens array, simplifying the system and improving spectral efficiency, and allowing for chip integration. Secondly, besides communication, the micro-LED array can also be used for display and illumination. This invention employs a channel QAM order adjustment algorithm compatible with both communication and display, ensuring that the bit error rate remains below a threshold even under high inter-channel interference. This invention, a visible light MIMO communication system based on a micro-LED array, combines the advantages of both micro-LED and MIMO. It can fully utilize the high bandwidth of micro-LED and the high spectral efficiency of OFDM and MIMO to achieve high-speed communication. Furthermore, when combined with a display, the QAM order adjustment algorithm is used to ensure that the communication quality is not affected.

[0085] In another embodiment of the invention, Figure 3This is a schematic diagram of the structure of a MIMO communication integration system according to an embodiment of the present invention. Figure 4 This is a schematic diagram illustrating the display effect of a micro-LED array in a MIMO communication integrated system according to an embodiment of the present invention; as shown. Figure 3 and Figure 4 As shown, a MIMO communication integrated system,

[0086] The system includes at least: a transmitting module and a receiving module;

[0087] The transmitting module includes at least: a photodetector array, an oscilloscope, and a computer (PC).

[0088] The receiving module includes at least: a waveform generator, a bias-tee, a DC power supply, a Micro-LED array, and a lens.

[0089] The PC is used to generate binary sequences in MATLAB; based on the display and the QAM adjustment algorithm, the binary sequences are mapped to QAM symbols; digital signals are modulated using the OFDM algorithm to obtain the data file to be sent to the arbitrary waveform generator (Tektronix AWG 710B 4.2GS / s 2.1GHz);

[0090] DC power is used to light up the micro-LED array;

[0091] Lenses are used to separate light spots;

[0092] Lens arrays are used to converge the light spot generated by the micro-LED array;

[0093] The waveform generator is used to convert the received OFDM signal into an analog signal, which, combined with a DC bias, drives the micro-LED array via a bias-tee.

[0094] The waveform generator is also used to set the signal transmission rate, voltage peak-to-peak value, and DC power supply current, which are dynamically adjusted according to the test results.

[0095] High-speed photodetector arrays are used to receive optical signals and convert them into electrical signals;

[0096] A high-speed oscilloscope (Agilent DSA-X 96204Q 160GS / s 62GHz) is used to receive signals generated by a photodetector and display the waveforms; the oscilloscope's acquisition frequency must satisfy the sampling theorem to acquire the received digital signal.

[0097] The PC is also used to demodulate and decode data using MATLAB programs, and compare the data with the transmitted signal to calculate the bit error rate and signal-to-noise ratio.

[0098] In the test of the system, a micro-LED array with a modulation bandwidth of 200MHz achieved a communication rate of 37Gbps and could clearly display the numbers.

[0099] Furthermore, based on the number S of pixels S that need to be lit at a time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined, including:

[0100] Test signals are simultaneously transmitted to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a user-defined value;

[0101] The QAM order of each subcarrier in each channel is calculated based on the relationship between signal-to-noise ratio (SNR) and QAM order. The relationship between SNR and QAM order is expressed as follows:

[0102]

[0103] Among them, M N The SNR gap represents the QAM order of the Nth subcarrier, the SNR gap is the difference between the actual channel capacity and the theoretical channel capacity set according to the channel conditions, and the SNR is the signal-to-noise ratio of the channel.

[0104] In this embodiment, to address the problem that increased inter-channel interference and reduced signal-to-noise ratio (SNR) occur when two pixels transmit signals together, and the increased bit error rate (BER) if the QAM order used when each pixel is individually lit is still applied after the SNR decreases, a new SNR is measured when two adjacent pixels transmit signals together, and the QAM order M corresponding to the current channel is calculated based on the newly measured SNR. N Once the QAM order is determined for different scenarios, the QAM order can be specified for the channel during actual data transmission without measuring SNR during transmission.

[0105] Furthermore, test signals are simultaneously transmitted to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, including:

[0106] Obtain the received and transmitted symbols of N subcarriers in each channel;

[0107] The error vector magnitude (EVM) of N subcarriers is determined based on the received and transmitted symbols.

[0108] Based on the error vector magnitude EVM, the signal-to-noise ratio of each of the N subcarriers in each channel is determined.

[0109] In this embodiment, the signal-to-noise ratio of N subcarriers in each channel is determined based on the EVM, which can be used to calculate the correspondence between SNR and QAM order.

[0110] Furthermore, based on the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols, including:

[0111] Each group of transmitted data is divided into N groups of sub-data, so that each group of sub-data is carried on a subcarrier;

[0112] The sub-data on each subcarrier is modulated into QAM symbols of the QAM order corresponding to the current subcarrier, generating N QAM symbols. These N QAM symbols are a set of QAM symbols corresponding to the current transmitted data, thus obtaining P sets of QAM symbols.

[0113] Furthermore, the P groups of QAM symbols are respectively subjected to OFDM modulation to generate P modulated signals, including:

[0114] Pilot signals for channel estimation are inserted into each of the N QAM symbols contained in each group of QAM symbols to generate N frequency domain signals;

[0115] Each frequency domain signal is converted to the time domain using IFFT, generating N time domain signals;

[0116] Each time-domain signal is converted from parallel to serial, and a cyclic prefix is ​​added to the front end of the OFDM frame to generate a modulation signal corresponding to a set of QAM symbols, thereby obtaining P modulation signals corresponding to P sets of transmitted data.

[0117] In this embodiment, inserting pilot signals for channel estimation into each of the N QAM symbols in each group of QAM symbols can reduce the channel fading characteristic.

[0118] Each time-domain signal is converted from parallel to serial to form a modulated signal. Adding a cyclic prefix to the front end of the OFDM frame can reduce inter-symbol interference.

[0119] Furthermore, based on P modulation signals, the micro-LED array is driven to synchronously transmit P optical signals and perform communication, including:

[0120] P modulation signals are combined with a DC bias voltage to drive a micro-LED array to emit P optical signals;

[0121] The P-path optical signals are sequentially separated and focused to generate the P-path intermediate optical signal;

[0122] The intermediate optical signal of the P-path is photoelectrically converted and the electrical signal is converted into a digital signal to obtain P groups of digital signals;

[0123] The P groups of digital signals were sequentially demodulated using OFDM and QAM to obtain the demodulated data of the P groups.

[0124] Furthermore, the P modulation signals are combined with a DC bias voltage to drive the micro-LED array to emit P optical signals, including:

[0125] P modulation signals are input into the waveform generator of the MIMO system to generate P analog signals;

[0126] P analog signals are combined with a DC power supply, and P driving electrical signals are generated through a T-type bias circuit.

[0127] P driving electrical signals are applied to the corresponding pixels in the micro-LED array.

[0128] Furthermore, the P groups of digital signals are sequentially demodulated using OFDM and demapped using QAM to obtain the P groups of demodulated data, including:

[0129] For each group of digital signals, sequentially perform cyclic prefix removal, serial-to-parallel conversion, FFT, channel estimation, QAM demapping, and parallel-to-serial conversion to generate P groups of demodulated data.

[0130] In this embodiment, removing the cyclic prefix can reduce inter-symbol interference, serial-to-parallel conversion can carry P groups of digital signals onto P subcarriers respectively, FFT is used to convert digital signals into frequency domain signals, and channel estimation can reduce the characteristics of channel fading.

[0131] Furthermore, the P-path optical signals are sequentially subjected to spot separation and spot focusing to generate the P-path intermediate optical signal, including:

[0132] A single convex lens is used to separate the P-path optical signals into P-path separated optical signals;

[0133] The P-path separated optical signal is focused using a lens array to generate the P-path intermediate optical signal.

[0134] Furthermore, the MIMO system includes 16 receivers and 16 transmitters; when the micro-LED array has a -3dB modulation bandwidth of 200MHz, the communication rate of the MIMO system reaches 37Gbps.

[0135] The beneficial effects of this invention are as follows: First, this invention uses a 4×4 array of micro-LEDs as the emission source, replacing the traditional ordinary LED array. The emission source is extremely small, requiring only a convex lens to separate the light path. The emission end does not require a complex lens array, does not occupy space, and is conducive to subsequent industrial integration.

[0136] Secondly, this invention combines communication and display through an algorithm, ensuring that changes in the displayed content do not affect the communication quality and guaranteeing that the micro-LED array can effectively perform its communication and display functions.

[0137] Furthermore, this invention uses micro-LED as the light source. Micro-LED has the characteristic of high modulation bandwidth, which is tens of times higher than that of ordinary LED, and can effectively improve the data rate of visible light communication.

[0138] Finally, this invention combines MIMO and micro-LED, taking advantage of the advantages of both to improve spectrum utilization efficiency while increasing modulation bandwidth, thereby maximizing the communication rate of visible light communication systems.

[0139] Specific embodiments of this application have now been described. Other embodiments are within the scope of the appended claims. In some cases, the actions described in the claims can be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing can be advantageous.

[0140] This application is described with reference to flowchart illustrations and / or block diagrams of methods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0141] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0142] Those skilled in the art will understand that the embodiments of this application can be provided as methods or apparatus. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0143] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0144] The above are merely embodiments of this application and are not intended to limit the scope 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 the claims of this application.

Claims

1. A visible light communication method for display and MIMO systems, characterized in that, The MIMO system includes a micro-LED array for displaying and emitting optical signals, which adjusts in real time when displaying different content to ensure stable communication rate and a bit error rate below a threshold; the method includes: Get the content to be displayed and the data to be transmitted; Based on the number S of pixels that need to be lit at one time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined, wherein the value of S is greater than or equal to 2. The data to be transmitted is divided into P groups of data for transmission, such that each group of data is transmitted through a channel, where S≥P≥2; Based on the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols; and OFDM modulation is performed on the P groups of QAM symbols to generate P modulation signals. Based on the P modulation signals, the micro-LED array is driven to synchronously transmit P optical signals and communicate; wherein, during the communication process, the illuminated pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed, so as to achieve real-time adjustment.

2. The visible light communication method for display and MIMO systems according to claim 1, characterized in that, The step of determining the QAM order of the channel corresponding to each pixel based on the number S of pixels S that need to be lit at one time for the content to be displayed includes: Test signals are simultaneously transmitted to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a user-defined value; The QAM order of each subcarrier in each channel is calculated based on the relationship between signal-to-noise ratio (SNR) and QAM order, whereby the relationship between SNR and QAM order is expressed as follows: Wherein, the M N The SNR gap represents the QAM order of the Nth subcarrier, the SNR gap is the difference between the actual channel capacity and the theoretical channel capacity set according to the channel conditions, and the SNR is the signal-to-noise ratio of the channel.

3. The visible light communication method for display and MIMO systems according to claim 2, characterized in that, The step of simultaneously transmitting test signals to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel includes: Obtain the received and transmitted symbols of N subcarriers in each channel; The error vector magnitude (EVM) of the N subcarriers is determined based on the received and transmitted symbols. Based on the error vector magnitude EVM, the signal-to-noise ratio of each of the N subcarriers in each channel is determined.

4. The visible light communication method for display and MIMO systems according to claim 2, characterized in that, Based on the QAM order, QAM mapping is performed on the P groups of transmitted data to generate P groups of QAM symbols, including: Each group of transmitted data is divided into N groups of sub-data, so that each group of sub-data is carried on a subcarrier; The sub-data on each subcarrier is modulated into QAM symbols of the QAM order corresponding to the current subcarrier, generating N QAM symbols. These N QAM symbols are a set of QAM symbols corresponding to the current transmitted data, thus obtaining P sets of QAM symbols.

5. The visible light communication method for display and MIMO systems according to claim 4, characterized in that, The P groups of QAM symbols are respectively subjected to OFDM modulation to generate P modulated signals, including: Pilot signals for channel estimation are inserted into each of the N QAM symbols contained in each group of QAM symbols to generate N frequency domain signals; Each frequency domain signal is converted to the time domain using IFFT, generating N time domain signals; Each time-domain signal is converted from parallel to serial, and a cyclic prefix is ​​added to the front end of the OFDM frame to generate a modulation signal corresponding to a set of QAM symbols, thereby obtaining P modulation signals corresponding to P sets of transmitted data.

6. The visible light communication method for display and MIMO systems according to claim 1, characterized in that, The step of driving the micro-LED array to synchronously transmit P optical signals and perform communication based on the P modulation signals includes: The P modulation signals are combined with a DC bias voltage to drive the micro-LED array to emit P optical signals. The P-path optical signals are sequentially subjected to spot separation and spot focusing to generate P-path intermediate optical signals; The P-channel intermediate optical signals are photoelectrically converted and the electrical signals are converted into digital signals to obtain P groups of digital signals; The P groups of digital signals are sequentially demodulated using OFDM and QAM to obtain the P groups of demodulated data.

7. The visible light communication method for display and MIMO systems according to claim 6, characterized in that, Combining the P modulation signals with a DC bias voltage to drive the micro-LED array to emit P optical signals includes: The P modulation signals are imported into the waveform generator of the MIMO system to generate P analog signals; The P analog signals are combined with a DC power supply, and P driving electrical signals are generated through a T-type biaser. The P driving electrical signals are respectively applied to the corresponding pixels in the micro-LED array.

8. The visible light communication method for display and MIMO systems according to claim 6, characterized in that, The step of sequentially performing OFDM demodulation and QAM demapping on the P groups of digital signals to obtain P groups of demodulated data includes: For each group of digital signals, sequentially perform cyclic prefix removal, serial-to-parallel conversion, FFT, channel estimation, QAM demapping, and parallel-to-serial conversion to generate P groups of demodulated data.

9. The visible light communication method for display and MIMO systems according to claim 6, characterized in that, The step of sequentially performing spot separation and spot focusing on the P-path optical signals to generate P-path intermediate optical signals includes: A single convex lens is used to separate the P-path optical signals to generate P-path separated optical signals. The P-path separated optical signal is focused using a lens array to generate the P-path intermediate optical signal.

10. The visible light communication method for display and MIMO systems according to claim 1, characterized in that, The MIMO system includes 16 receivers and 16 transmitters; When the micro-LED array has a -3dB modulation bandwidth of 200MHz, the communication rate of the MIMO system reaches 37Gbps.

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