Visible light communication method for display and MIMO system

Abstract

The invention relates to the field of communication, and provides a visible light communication method for a display and MIMO system, and the method comprises the steps: obtaining to-be-displayed content and to-be-transmitted data; according to the number S of pixels, needing to be lightened at a single time, of the to-be-displayed content, the QAM order of a channel corresponding to each pixel is determined; dividing the data to be transmitted into P groups of transmission data, so that each group of transmission data is transmitted through one channel; respectively performing QAM mapping on the P groups of transmission data according to the QAM order to generate P groups of QAM code elements; respectively carrying out OFDM modulation on the P groups of QAM code elements to generate P modulation signals; and driving the micro-LED array to synchronously transmit P paths of optical signals and perform communication based on the P modulation signals. According to the invention, the advantages of MIMO and micro-LED are combined, the spectrum utilization efficiency is improved on the basis of improving the modulation bandwidth, and the communication rate of a visible light communication system can be maximized.

Description

Technical Field

[0001] The present application relates to the field of communications, and in particular to a visible light communication method for display and MIMO systems. Background Art

[0002] As communication technology is increasingly used in people's lives, spectrum resources in the radio frequency band are becoming increasingly scarce, and utilizing more spectrum resources has become a recent research hotspot. The visible light band has very rich spectrum resources, so it has attracted much attention as a new type of information carrier. The fast on and off characteristics of LEDs have given rise to visible light communications based on LEDs. How to make VLC achieve a higher transmission rate is the focus of research at this stage. Micro-LED, as a new type of light source, has the characteristics of high current density, high brightness and high modulation bandwidth. The modulation bandwidth of micro-LED can reach hundreds or even thousands of MHz, which greatly improves the signal bandwidth of the VLC system compared to the modulation bandwidth of ordinary LEDs of about ten MHz. Moreover, micro-LED has a micron-level size and the ability to display high resolution. The extremely small volume of the transmitter can be integrated with the chip. DCO-OFDM modulation technology is an OFDM modulation technology optimized for optical communication, which can improve the frequency band utilization of the VLC system. The equalizer can reduce inter-code interference and the problem of signal waveform tailing. Software pre-equalization is easier to optimize parameters for a specific system than hardware equalization. Using a single-tap equalizer in an OFDM system can achieve better equalization effects. Imaging MIMO uses lenses or lens arrays to focus the optical signal on the detector, greatly reducing the interference between channels and making full use of spatial resources to obtain higher spectrum utilization efficiency. The VLC system based on micro-LED and combined with OFDM and imaging MIMO technology has the ability to reach communication rates of tens of Gbps or even hundreds of Gbps.

[0003] In the prior art, imaging MIMO uses an imaging lens to image the optical signal generated by the LED array onto the camera array, and each transmitting unit corresponds to a receiving unit; a feedback control module is also designed to start the adaptive modulation mode according to the uplink optical signal carrying the modulation parameters. The disadvantage of the prior art is that the system uses ordinary commercial LEDs as signal transmission sources. The small bandwidth of ordinary commercial LEDs and the low sampling rate of the camera greatly limit the transmission rate of the system, and no equalizer is added to increase the bandwidth. In addition, increasing the number of transmitting units requires increasing the number of transmitting LEDs, which will cause the volume of the transmitting end to increase exponentially, which is not conducive to integration with the chip. The optical path design of the imaging lens and the complexity of the system construction increase, and the steps to reduce interference between channels are more complicated.

[0004] There is also a visible light adaptive spatial modulation method in the prior art. This method sets a system interference tolerance and selectively lights up the LED array when the system interference level is not greater than the tolerance value. That is, a specific number of LEDs are selected in the MIMO transmission array to participate in the transmission of information in order to reduce the interference between channels. The disadvantage of this prior art is that the commercial LED array is limited by low bandwidth and its transmission rate is limited. In order to reduce the interference between channels, this technology selectively lights up some LEDs, which will further reduce the efficiency of information transmission. And selectively lighting up LEDs cannot achieve the display function. In a communication system, the communication rate is proportional to the system bit error rate. Reducing the communication rate can reduce the bit error rate. This method reduces the bit error rate at the expense of the communication rate and is not suitable for scenarios where high communication rates are required. 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, improves the spectrum utilization efficiency while increasing the modulation bandwidth, and can maximize the communication rate of the visible light communication system. When displaying different contents, the communication rate is stable and the bit error rate is lower than the threshold.

[0006] According to a first aspect of the present invention, the present invention provides a visible light communication method for a display and MIMO system, wherein the MIMO system comprises a micro-LED array, the micro-LED array is used to display and emit light signals, and is adjusted in real time when displaying different contents, so that the communication rate is stable and the bit error rate is lower than a threshold; the method comprises:

[0007] Obtaining content to be displayed and data to be transmitted;

[0008] According to the number S of pixels to be lit at a time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined respectively, wherein the value range of S is greater than or equal to 2;

[0009] Divide the data to be transmitted into P groups of transmission data, so that each group of transmission data is transmitted through one channel, wherein S≥P≥2;

[0010] According to the QAM order, respectively perform QAM mapping on the P groups of transmission data to generate P groups of QAM symbols; and respectively perform OFDM modulation on the P groups of QAM symbols to generate P modulated signals;

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

[0012] Preferably, the step of determining the QAM order of the channel corresponding to each pixel according to the number S of pixels to be lit at a time for the content to be displayed comprises:

[0013] Simultaneously transmit test signals to the channels corresponding to the S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a custom value;

[0014] The QAM order of each subcarrier in each channel is calculated according to the relationship between the signal-to-noise ratio and the QAM order, wherein the relationship between the signal-to-noise ratio and the QAM order is expressed as follows:

[0015]

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

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

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

[0019] Determine the error vector magnitude (EVM) of N subcarriers according to the received codewords and the transmitted codewords;

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

[0021] Preferably, according to the QAM order, performing QAM mapping on the P groups of transmission data respectively to generate P groups of QAM symbols includes:

[0022] Each group of transmission data is divided into N groups of sub-data, so that each group of sub-data is carried on one sub-carrier;

[0023] The sub-data on each sub-carrier is modulated into a QAM symbol of the QAM order corresponding to the current sub-carrier, generating N QAM symbols, which are a group of QAM symbols corresponding to the current transmission data, thereby obtaining P groups of QAM symbols.

[0024] Preferably, performing OFDM modulation on the P groups of QAM symbols respectively to generate P modulated signals includes:

[0025] Inserting pilot signals for channel estimation into N QAM symbols included in each group of QAM symbols to generate N frequency domain signals;

[0026] Use IFFT to convert each frequency domain signal into the time domain to generate 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 group of QAM code elements, thereby obtaining P modulation signals corresponding to P groups of transmission data.

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

[0029] Combining the P modulation signals with a DC bias voltage to drive the micro-LED array to emit P optical signals;

[0030] Separating and focusing the P optical signals in sequence to generate P intermediate optical signals;

[0031] Performing photoelectric conversion on the P intermediate optical signals, and converting the electrical signals into digital signals, to obtain P groups of digital signals;

[0032] OFDM demodulation and QAM demapping are performed on the P groups of digital signals in sequence to obtain P groups of demodulated data.

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

[0034] Importing the P modulated signals into a waveform generator of the MIMO system to generate P analog signals;

[0035] Combining the P analog signals with a DC power supply and generating P driving electrical signals through a T-type bias device;

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

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

[0038] Each group of digital signals is sequentially subjected to 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-channel optical signals to generate P-channel intermediate optical signals includes:

[0040] Using a single convex lens to perform light spot separation on the P-channel optical signal to generate a P-channel separated optical signal;

[0041] The P-channel separated optical signals are spot-focused by using a lens array to generate P-channel intermediate optical signals.

[0042] Preferably, the MIMO system includes 16 receiving ends and 16 transmitting ends;

[0043] When the -3db modulation bandwidth of the micro-LED array is 200MHZ, the communication rate of the MIMO system reaches 37Gbps.

[0044] The beneficial effect of the present invention is that the visible light MIMO communication system based on the micro-LED array of the present invention adopts 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 requires 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.

[0045] Secondly, the present invention realizes the combination of communication and display through an algorithm, and the communication quality will not change due to changes in display content, ensuring that the micro-LED array can effectively operate the communication and display functions, and has the potential to realize a new generation of optical interconnection;

[0046] In addition, the present invention uses micro-LED as a light source. Micro-LED has the characteristics of high modulation bandwidth, which is dozens of times higher than that of ordinary LED, and can effectively improve the data rate of visible light communication;

[0047] Finally, the present invention combines MIMO and micro-LED, utilizing the advantages of both, improving the spectrum utilization efficiency while increasing the modulation bandwidth, and maximizing the communication rate of the visible light communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A schematic flow chart of a visible light communication method for display and MIMO system of the present invention;

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

[0051] Figure 3A schematic diagram of the structure of a MIMO communication integration system in an embodiment of the present invention;

[0052] Figure 4 Schematic diagram of the display effect of a micro-LED array of a MIMO communication integrated system in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] The terms "including" and "having" and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or equipment.

[0056] According to one embodiment of the present invention, Figure 1 FIG. 1 is a flow chart of a visible light communication method for display and MIMO system of the present invention, as shown in FIG. Figure 1 As shown, the present invention provides a visible light communication method for display and MIMO system, comprising:

[0057] Obtaining content to be displayed and data to be transmitted;

[0058] According to the number S of pixels to be lit at a time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined respectively, wherein the value range of S is greater than or equal to 2;

[0059] Divide the data to be transmitted into P groups of transmission data, so that each group of transmission data is transmitted through one channel, where S≥P≥2;

[0060] According to the QAM order, QAM mapping is performed on P groups of transmission data to generate P groups of QAM code elements; and OFDM modulation is performed on the P groups of QAM code elements to generate P modulated signals;

[0061] Based on P modulation signals, the micro-LED array is driven to synchronously emit P optical signals and communicate. During the communication process, the lit pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed to achieve real-time adjustment.

[0062] In this embodiment, the MIMO system includes a micro-LED array, which is used to display and emit light signals, and is adjusted in real time when displaying different contents, so that the communication rate is stable and the bit error rate is lower than the threshold. The design of the present invention uses a 4×4 array of micro-LEDs with a size of 40μm as the emission source. The modulation bandwidth of micro-LEDs is nearly 100 times higher than that of ordinary LEDs. A single link of visible light communication using micro-LEDs can achieve a communication rate of several Gbps. Using micro-LED arrays to transmit data in parallel, the communication rate can reach tens of Gbps, and the combination of display and lighting can be realized. The communication quality will not change due to changes in the displayed content, ensuring that the micro-LED array effectively operates the communication and display functions.

[0063] The above-obtained content to be displayed and data to be transmitted are N binary bit streams generated by PC-side MATLAB software. The value range of N is 0-16, and the value of N depends on the content to be displayed. S pixels are lit, and the QAM order of each pixel is determined according to the density of pixel lighting. Optionally, the value range of S is greater than or equal to 2.

[0064] The QAM order adjustment algorithm that takes into account both communication and display is as follows:

[0065] Before communication, a binary phase shift keying signal is first transmitted to test the signal-to-noise ratio of the channel corresponding to a pixel. The signal-to-noise ratio is obtained based on the error vector amplitude of the received data. The corresponding relationship between the signal-to-noise ratio and the QAM order calculated according to the following formula specifies the QAM order for the channel corresponding to the pixel when it is lit alone:

[0066]

[0067] Wherein, EVM(N) is the error vector magnitude of the Nth subcarrier;

[0068] SNR(N) is the signal-to-noise ratio of the Nth subcarrier;

[0069] Q is the number of binary phase-shift keying symbols;

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

[0071] S kt (N) is the Kth received symbol on the Nth subcarrier;

[0072] N is the number of subcarriers.

[0073]

[0074] Among them, MN is the QAM order of the Nth subcarrier;

[0075] The SNR gap is the difference between the actual channel capacity set according to the channel conditions and the theoretical channel capacity, which is adjusted according to the quality of the channel. The SNR is the signal-to-noise ratio of the tested channel.

[0076] When two pixels transmit data together, the interference between channels will increase, resulting in a decrease in the signal-to-noise ratio. If the QAM order when the pixels are lit separately is still used after the signal-to-noise ratio is reduced, the bit error rate will increase. In order to control the bit error rate below the threshold, it is necessary to measure the new SNR of the channel when two adjacent pixels transmit data together, and calculate the QAM order M corresponding to the current channel based on the newly tested signal-to-noise ratio. N After determining the QAM order for different situations, the QAM order can be assigned to the channel when actually transmitting data, without having to measure the signal-to-noise ratio during the transmission process.

[0077] After determining the QAM order, the data to be transmitted is divided into P groups of transmission data, so that each group of transmission data is transmitted through one channel, where S≥P≥2;

[0078] The sub-data on each sub-carrier is modulated into a QAM symbol of the QAM order corresponding to the current sub-carrier, generating N QAM symbols, which are a group of QAM symbols corresponding to the current transmission data, thereby obtaining P groups of QAM symbols.

[0079] Inserting pilot signals for channel estimation into N QAM symbols included in each group of QAM symbols to generate N frequency domain signals;

[0080] Use IFFT to convert each frequency domain signal into the time domain to generate N time domain signals;

[0081] 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 group of QAM code elements, thereby obtaining P modulation signals corresponding to P groups of transmission data. The P modulation signals are combined with DC bias to drive the micro-LED array and synchronously transmit P optical signals for communication:

[0082] A lens is set at the transmitting end, and a lens array is set at the receiving end to separate and focus the light spot; the light spots of P-channel optical signals are separated and focused in turn to generate P-channel intermediate optical signals; the P-channel intermediate optical signals are received by a photoelectric detector array for photoelectric conversion, and the electrical signals are converted into digital signals through an oscilloscope connected to the photoelectric detector to obtain P groups of digital signals; the P groups of digital signals are transmitted to the PC end, and OFDM demodulation and QAM demapping are used to obtain P groups of demodulated data; finally, the binary bit stream is restored to obtain the highest data transmission rate within the allowable bit error rate.

[0083] Optional, Figure 2 This is a schematic diagram of the DCO-OFDM principle combined with the QAM order adjustment algorithm. The above OFDM modulation and demodulation 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 become N groups of data, and then the QAM adjustment algorithm is performed according to the displayed content, and the data of each channel is mapped to the QAM symbol of the corresponding order. Then, after inserting the pilot for channel estimation, IFFT is used to generate a real-valued signal in the time domain, and the modulated signal is formed after parallel-to-serial conversion, 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 is reconstructed into binary data and the transmitted data is restored through the process of removing the cyclic prefix, serial-to-parallel conversion, FFT, channel estimation, QAM mapping and parallel-to-serial conversion. Among them, inserting the pilot can perform channel estimation to reduce the characteristics of channel fading; for the receiving end, inserting the received signal into a cycle can reduce inter-symbol interference.

[0084] During the communication process, the lit pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed to achieve real-time adjustment.

[0085] The visible light MIMO communication method based on the micro-LED array of the present invention, on the one hand, uses 40μm micro-LEDs to form a 4×4 array as the emission source, and uses the characteristics that the modulation bandwidth of micro-LEDs is dozens of times higher than that of ordinary LEDs, which can reach hundreds of megahertz or even thousands of megahertz, and combines OFDM modulation to obtain a single channel. The communication rate can reach several Gbps. By combining OFDM modulation with MIMO, the micro-LED array is used as the emission source. The volume is very small, and only a convex lens is needed to separate the light path. Compared with the traditional visible light MIMO system with ordinary LEDs as the emission source, the transmitting end does not need a complex lens array, so as to achieve the effect of simplifying the system and improving the spectrum utilization, and it can be integrated with the chip. On the other hand, in addition to communication, the micro-LED array can also realize display and lighting. In the present invention, the channel QAM order adjustment algorithm compatible with communication and display can ensure that the bit error rate is lower than the threshold value in the case of high inter-channel interference. The visible light MIMO communication system based on the micro-LED array of the present invention combines the advantages of both micro-LED and MIMO, and can fully utilize the advantages of micro-LED high bandwidth and OFDM and MIMO high spectrum efficiency to obtain high-speed communication rate. When combined with a display, it utilizes a QAM order adjustment algorithm without affecting the quality of communication.

[0086] In another embodiment of the present invention, Figure 3is a structural diagram of a MIMO communication integration system in an embodiment of the present invention, Figure 4 is a schematic diagram of the display effect of a micro-LED array of a MIMO communication integrated system in an embodiment of the present invention; Figure 3 and Figure 4 As shown, a MIMO communication integrated system,

[0087] The system at least includes: a transmitting module and a receiving module;

[0088] The transmitting module at least includes: a photodetector array, an oscilloscope and a computer (PC terminal);

[0089] The receiving module at least includes: a waveform generator, a Bias-tee, a DC power supply, a Micro-LED array, and a lens.

[0090] The PC is used to generate a binary sequence in MATLAB; the binary sequence is mapped to QAM symbols according to the display and QAM adjustment algorithm; the digital signal is modulated by the OFDM algorithm to obtain the data file that needs to be sent to the arbitrary waveform generator (Tektronix AWG 710B 4.2GS / s 2.1GHz);

[0091] A DC power supply is used to illuminate the micro-LED array;

[0092] The lens is used to separate the light spots;

[0093] The lens array is used to converge the light spots generated by the micro-LED array;

[0094] The waveform generator is used to convert the received OFDM signal into an analog signal, which is combined with the DC bias to drive the micro-LED array through the Bias-tee.

[0095] The waveform generator is also used to set the signal transmission rate, the peak-to-peak voltage, and the DC power supply setting current to be dynamically adjusted according to the test results;

[0096] High-speed photodetector array is used to receive optical signals and convert them into electrical signals;

[0097] A high-speed oscilloscope (Agilent DSA-X 96204Q 160GS / s 62GHz) is used to receive the signal generated by the photodetector and display the waveform; the acquisition frequency of the oscilloscope must satisfy the sampling theorem to acquire the received digital signal;

[0098] The PC is also used to demodulate the decoded data through the MATLAB program and compare it with the transmitted signal to calculate the bit error rate and signal-to-noise ratio.

[0099] In the test of this system, a communication rate of 37Gbps was achieved using a micro-LED array with a 200MHz modulation bandwidth, and numbers could be displayed clearly.

[0100] Furthermore, according to the number S of pixels to be lit at a time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined respectively, including:

[0101] Simultaneously transmit test signals to the channels corresponding to S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a custom value;

[0102] The QAM order of each subcarrier in each channel is calculated based on the relationship between the signal-to-noise ratio and the QAM order, where the relationship between the signal-to-noise ratio and the QAM order is expressed as follows:

[0103]

[0104] Among them, M N It represents the QAM order of the Nth subcarrier. SNR gap is the difference between the actual channel capacity set according to the channel conditions and the theoretical channel capacity. SNR is the signal-to-noise ratio of the channel.

[0105] In this embodiment, in order to solve the problem that when two pixels transmit signals together, the interference between channels will increase, resulting in a decrease in the signal-to-noise ratio, and if the QAM order when the signal-to-noise ratio is reduced and the QAM order when the pixels are lit separately is still used, the bit error rate will increase, the new SNR of the channel is measured when two adjacent pixels transmit signals together, and the QAM order M corresponding to the current channel is calculated according to the newly tested SNR. N After determining the QAM order for different situations, the QAM order can be assigned to the channel when actually transmitting data, without measuring the SNR during the transmission process.

[0106] Furthermore, a test signal is simultaneously transmitted to the channels corresponding to the S pixels to obtain the signal-to-noise ratio of the N subcarriers in each channel, including:

[0107] Obtain received codewords and transmitted codewords of N subcarriers in each channel;

[0108] Determine the error vector magnitude (EVM) of N subcarriers based on the received codewords and the transmitted codewords;

[0109] According to the error vector magnitude EVM, the signal-to-noise ratio of the N subcarriers in each channel is determined respectively.

[0110] In this embodiment, the signal-to-noise ratio of N subcarriers in each channel is determined according to the EVM, which can be used to calculate the corresponding relationship between the SNR and the QAM order.

[0111] Further, according to the QAM order, QAM mapping is performed on P groups of transmission data respectively to generate P groups of QAM symbols, including:

[0112] Each group of transmission data is divided into N groups of sub-data, so that each group of sub-data is carried on one sub-carrier;

[0113] The sub-data on each sub-carrier is modulated into a QAM symbol of the QAM order corresponding to the current sub-carrier, generating N QAM symbols, which are a group of QAM symbols corresponding to the current transmission data, thereby obtaining P groups of QAM symbols.

[0114] Further, the P groups of QAM symbols are respectively subjected to OFDM modulation to generate P modulated signals, including:

[0115] Inserting pilot signals for channel estimation into N QAM symbols included in each group of QAM symbols to generate N frequency domain signals;

[0116] Use IFFT to convert each frequency domain signal into the time domain to generate N time domain signals;

[0117] 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 group of QAM code elements, thereby obtaining P modulation signals corresponding to P groups of transmission data.

[0118] In this embodiment, inserting pilots for channel estimation into the N QAM symbols included in each group of QAM symbols can reduce the characteristics of channel fading;

[0119] 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.

[0120] Furthermore, based on P modulation signals, the micro-LED array is driven to synchronously emit P optical signals and communicate, including:

[0121] Combining P modulation signals with a DC bias voltage to drive the micro-LED array to emit P optical signals;

[0122] Separate and focus the light spots of the P-channel optical signals in sequence to generate the P-channel intermediate optical signals;

[0123] Perform photoelectric conversion on the intermediate optical signals of P paths, and convert the electrical signals into digital signals to obtain P groups of digital signals;

[0124] OFDM demodulation and QAM demapping are performed on P groups of digital signals in sequence to obtain P groups of demodulated data.

[0125] Further, P modulation signals are combined with a DC bias to drive the micro-LED array to emit P optical signals, including:

[0126] Importing P modulated signals into a waveform generator of the MIMO system to generate P analog signals;

[0127] P analog signals are combined with a DC power supply and P driving electrical signals are generated through a T-type bias device;

[0128] P driving electrical signals are respectively loaded onto corresponding pixels in the micro-LED array.

[0129] Further, the P groups of digital signals are sequentially subjected to OFDM demodulation and QAM demapping to obtain P groups of demodulated data, including:

[0130] Each group of digital signals is sequentially subjected to cyclic prefix removal, serial-to-parallel conversion, FFT, channel estimation, QAM demapping and parallel-to-serial conversion to generate P groups of demodulated data.

[0131] In this embodiment, removing the cyclic prefix can reduce inter-symbol interference, serial-to-parallel conversion can carry P groups of digital signals on P subcarriers respectively, FFT is used to convert the digital signal into a frequency domain signal, and channel estimation can reduce the characteristics of channel fading.

[0132] Further, the P-channel optical signals are sequentially subjected to light spot separation and light spot focusing to generate P-channel intermediate optical signals, including:

[0133] A single convex lens is used to separate the light spots of P-channel optical signals to generate P-channel separated optical signals;

[0134] The P-channel separated optical signals are spot-focused by using a lens array to generate P-channel intermediate optical signals.

[0135] Furthermore, the MIMO system includes 16 receiving ends and 16 transmitting ends; when the -3db modulation bandwidth of the micro-LED array is 200MHZ, the communication rate of the MIMO system reaches 37Gbps.

[0136] The beneficial effects of the present invention are that, firstly, the present invention adopts 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 requires a convex lens to separate the light path. The emission end does not require a complex lens array and does not take up space, which is conducive to subsequent industrial integration.

[0137] Secondly, the present invention realizes the combination of communication and display through an algorithm, and will not cause changes in communication quality due to changes in display content, thereby ensuring that the micro-LED array effectively operates the communication and display functions.

[0138] In addition, the present invention uses micro-LED as the light source. Micro-LED has the characteristics of high modulation bandwidth, which is dozens of times higher than that of ordinary LED, and can effectively improve the data rate of visible light communication.

[0139] Finally, the present invention combines MIMO and micro-LED, utilizing the advantages of both, improving the spectrum utilization efficiency while increasing the modulation bandwidth, and maximizing the communication rate of the visible light communication system.

[0140] So far, specific embodiments of the present application have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recorded in the claims can be performed in a different order and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing can be advantageous.

[0141] The present application is described with reference to the flowcharts and / or block diagrams of the methods according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0142] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0143] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods and devices. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt 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.

[0144] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0145] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A visible light communication method for display and MIMO system, characterized in that: The MIMO system includes a micro-LED array, which is used to display and emit light signals, and is adjusted in real time when displaying different contents so that the communication rate is stable and the bit error rate is lower than a threshold; the method includes: Obtaining content to be displayed and data to be transmitted; According to the number S of pixels to be lit at a time for the content to be displayed, the QAM order of the channel corresponding to each pixel is determined respectively, wherein the value range of S is greater than or equal to 2; Divide the data to be transmitted into P groups of transmission data, so that each group of transmission data is transmitted through one channel, wherein S≥P≥2; According to the QAM order, respectively perform QAM mapping on the P groups of transmission data to generate P groups of QAM symbols; and respectively perform OFDM modulation on the P groups of QAM symbols to generate P modulated signals; Based on the P modulation signals, the micro-LED array is driven to synchronously emit P optical signals and communicate; wherein, during the communication process, the lighted pixels and the QAM order of the channel corresponding to each pixel are changed according to the next content to be displayed to achieve real-time adjustment.

2. The visible light communication method for display and MIMO communication system according to claim 1, characterized in that: The step of determining the QAM order of the channel corresponding to each pixel according to the number S of pixels that need to be lit at a time for the content to be displayed comprises: Simultaneously transmit test signals to the channels corresponding to the S pixels to obtain the signal-to-noise ratio of N subcarriers in each channel, where N is a custom value; The QAM order of each subcarrier in each channel is calculated according to the relationship between the signal-to-noise ratio and the QAM order, wherein the relationship between the signal-to-noise ratio and the QAM order is expressed as follows: Among them, the M N It represents the QAM order of the Nth subcarrier. SNR gap is the difference between the actual channel capacity set according to the channel conditions and the theoretical channel capacity. SNR is the signal-to-noise ratio of the channel.

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

4. The visible light communication method for display and MIMO communication system according to claim 2, characterized in that: According to the QAM order, performing QAM mapping on the P groups of transmission data respectively to generate P groups of QAM symbols, including: Each group of transmission data is divided into N groups of sub-data, so that each group of sub-data is carried on one sub-carrier; The sub-data on each sub-carrier is modulated into a QAM symbol of the QAM order corresponding to the current sub-carrier, generating N QAM symbols, which are a group of QAM symbols corresponding to the current transmission data, thereby obtaining P groups of QAM symbols.

5. The visible light communication method for display and MIMO communication system 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: Inserting pilot signals for channel estimation into N QAM symbols included in each group of QAM symbols to generate N frequency domain signals; Use IFFT to convert each frequency domain signal into the time domain to generate 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 group of QAM code elements, thereby obtaining P modulation signals corresponding to P groups of transmission data.

6. The visible light communication method for display and MIMO communication system according to claim 1, characterized in that: The method of driving the micro-LED array to synchronously emit P optical signals and communicate based on the P modulation signals includes: Combining the P modulation signals with a DC bias voltage to drive the micro-LED array to emit P optical signals; Separating and focusing the P optical signals in sequence to generate P intermediate optical signals; Performing photoelectric conversion on the P intermediate optical signals, and converting the electrical signals into digital signals, to obtain P groups of digital signals; OFDM demodulation and QAM demapping are performed on the P groups of digital signals in sequence to obtain P groups of demodulated data.

7. The visible light communication method for display and MIMO communication system 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: Importing the P modulated signals into a waveform generator of the MIMO system to generate P analog signals; Combining the P analog signals with a DC power supply and generating P driving electrical signals through a T-type bias device; The P driving electrical signals are respectively loaded onto corresponding pixels in the micro-LED array.

8. The visible light communication method for display and MIMO communication system 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: Each group of digital signals is subjected to cyclic prefix removal, serial-to-parallel conversion, FFT, channel estimation, QAM demapping and parallel-to-serial conversion in sequence to generate P groups of demodulated data.

9. The visible light communication method for display and MIMO communication system according to claim 6, characterized in that: The step of sequentially performing light spot separation and light spot focusing on the P-channel optical signals to generate P-channel intermediate optical signals includes: Using a single convex lens to perform light spot separation on the P-channel optical signal to generate a P-channel separated optical signal; The P-channel separated optical signals are spot-focused by using a lens array to generate P-channel intermediate optical signals.

10. The visible light communication method for display and MIMO communication system according to claim 1, characterized in that: The MIMO system includes 16 receiving ends and 16 transmitting ends; When the -3db modulation bandwidth of the micro-LED array is 200MHZ, the communication rate of the MIMO system reaches 37Gbps.

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