WO2022188243A1 - 自适应调光的可见光通信系统及调制解调方法 - Google Patents

自适应调光的可见光通信系统及调制解调方法 Download PDF

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WO2022188243A1
WO2022188243A1 PCT/CN2021/088356 CN2021088356W WO2022188243A1 WO 2022188243 A1 WO2022188243 A1 WO 2022188243A1 CN 2021088356 W CN2021088356 W CN 2021088356W WO 2022188243 A1 WO2022188243 A1 WO 2022188243A1
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adaptive
signal
visible light
transmitter
photoelectric sensor
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French (fr)
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由骁迪
熊超然
沈纲祥
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Suzhou University
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Suzhou University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

Definitions

  • the invention relates to the technical field of optical communication, in particular to an adaptive dimming visible light communication system and a modulation and demodulation method.
  • Cia Patent Publication No. CN103763829A discloses a light source dimming method based on OFDM signal, which is a hybrid visible light communication system based on MPPM dimming control, orthogonal frequency division multiplexing (OFDM) and multi-pulse position modulation (MPPM) Combined, it not only supports high-speed visible light communication, but also meets the needs of users for brightness adjustment of lighting sources.
  • This hybrid modulation method ensures that the system has the dimming function of MPPM, and the introduced OFDM transmission can effectively improve the spectral efficiency.
  • the transmission rate of the MPPM-based dimming control scheme is limited by the duty cycle of the dimming control signal.
  • Chinese Patent Publication No. 201610320643.3 discloses a visible light OFDM communication device with infrared compensation full-range dimming; the method is capable of both full-range dimming and transmission of OFDM signals, and the transmission rate, The transmission quality has a small impact, which can reduce the dependence of the signal transmission performance on the dimming duty cycle in the traditional scheme, and effectively reduce the system complexity.
  • the transmission rate based on the MPPM dimming control scheme is limited by the duty cycle of the dimming control signal. Therefore, in the environment where the visible light intensity is weak, or even in complete darkness, this system cannot achieve stable signal transmission. Full-field dimming. And this system does not consider the delay time of the rising and falling edges of the actual MPPM signal. In practice, the transmission of the OFDM signal is susceptible to the interference of the rising and falling edges, so the theoretical high transmission rate and low error rate cannot be achieved.
  • the rising and falling edges of the dimming pulse signal limit the alternate transmission of visible light and infrared signals.
  • the step response characteristics of the existing commercial visible light illumination LEDs and infrared emitters are poor. If the delay time of the rising and falling edges of the high and low levels is not considered, the rate and quality of the alternate transmission will be greatly reduced, and this technical solution cannot be effective. Filter out the visible light and infrared LED's falling edge signal interference. In certain duty cycles under certain pulse modulation methods, the bit error rate and transmission rate are even better than the transmission methods without infrared compensation.
  • the visible light OFDM communication system using infrared compensation full-range dimming cannot separate the visible light and infrared signals at the receiving end, and the two signals will interfere at the receiving end, which will increase the bit error rate.
  • the complexity of OFDM is high, especially when the real-time system is implemented, the research and development cycle is long.
  • the peak-average value of OFDM signals is relatively high, which requires a large linear working area of the light source, resulting in a large maximum transmit power, and at the same time, the cost of components, driving circuits, etc. will also increase, and greater power will bring worse frequency response will reduce the bandwidth.
  • the OFDM signal cannot automatically adapt to the lamp beads whose performance is degraded due to aging, resulting in signal distortion and increased bit error rate. Using OFDM signals can only improve the rate in an ideal experimental environment, and is not suitable for specific practical application scenarios.
  • the technical problem to be solved by the present invention is to provide a visible light communication system with adaptive dimming and a modulation and demodulation method, which realizes the switching between visible light and infrared dual-channel signals without interval and delay, and can be loaded with adaptive light at any time.
  • M-PAM modulated signal M-PAM modulated signal.
  • an adaptive dimming visible light communication system which is characterized by comprising:
  • an adaptive M-PAM modulator which is connected to the signal source, and the adaptive M-PAM modulator modulates the signal sent by the signal source into a first electrical signal and a second electrical signal respectively;
  • a visible light transmitter connected to the adaptive M-PAM modulator, the visible light transmitter converting the second electrical signal into visible light
  • an infrared light transmitter which is connected to the adaptive M-PAM modulator, and the infrared light transmitter converts the first electrical signal into infrared light;
  • a dual pulse generator which alternately generates a first pulse control signal and a second pulse control signal, the first pulse control signal and the second pulse control signal are both periodic signals, the first pulse control signal and the visible light signal
  • the transmitter is connected to control the visible light signal transmitter to work, and the second pulse control signal is connected to the infrared light transmitter to control the infrared light transmitter to work;
  • the first pulse control signal starts to be generated.
  • it also includes a first photoelectric sensor, a second photoelectric sensor and a transmitter controller, and the transmitter controller is respectively connected with the first photoelectric sensor and the second photoelectric sensor;
  • the first photoelectric sensor collects the light intensity of visible light emitted by the visible light transmitter, and the second photoelectric sensor collects the light intensity of the infrared light emitted by the infrared light transmitter;
  • the transmitter controller controls the adaptive M-PAM modulator and the dual pulse generator according to the light intensity collected by the first photoelectric sensor and the second photoelectric sensor.
  • the receiving end of the visible light communication system includes a third photoelectric sensor, a fourth photoelectric sensor, an analog switch, a receiver controller and an adaptive M-PAM demodulator;
  • the third photoelectric sensor collects the light signal emitted by the visible light transmitter, and the fourth photoelectric sensor collects the light signal emitted by the infrared light transmitter;
  • the receiver controller is connected with an analog switch and an adaptive M-PAM demodulator
  • the analog switch is connected with the third photoelectric sensor and the fourth sensor to gate effective signals of visible light signals and infrared signals, and the effective signals are output after being demodulated by the adaptive M-PAM demodulator to Xinshu.
  • it also includes a first visible light filter, a first infrared light filter, a second visible light filter and a second infrared light filter;
  • the first visible light filter is arranged at the detection end of the first photoelectric sensor, and the first infrared light filter is arranged at the detection end of the second photoelectric sensor;
  • the second visible light filter is arranged at the detection end of the third photoelectric sensor, and the second infrared light filter is arranged at the detection end of the fourth photoelectric sensor.
  • the invention discloses a modulation and demodulation method for an adaptive dimming visible light communication system. Based on the above-mentioned adaptive dimming visible light communication system, the following steps are included:
  • the light decay D range of the nth grade is
  • the transmitter controller When the transmitter controller detects that the order M needs to be changed, the transmitter controller transmits the changed M' modulation order to the adaptive M-PAM modulator;
  • the adaptive M-PAM modulator controls the optical transmitter to transmit the optical signal that needs to be transformed with the current order M, and the optical signal that needs to be transformed carries the transformed order M';
  • the photoelectric sensor at the receiving end converts the optical signal carrying the M' modulation order into an electrical signal carrying the M' modulation order
  • the receiver controller obtains the electrical signal carrying the M' modulation order, and obtains the M' demodulation order according to the electrical signal carrying the M' modulation order;
  • the receiver controller transmits the obtained M' demodulation order to the adaptive M-PAM demodulator, and the adaptive M-PAM demodulator demodulates the communication signal according to the M' demodulation order operate.
  • the dual-channel dimming pulse generator When the dual-channel dimming pulse generator detects that the transmitted data is the last data frame, the dual-channel dimming pulse generator controls the adaptive M-PAM modulator to generate an electrical signal carrying dual-channel switching.
  • the adaptive M-PAM modulator controls the optical transmitter to transmit the dual-channel switching instruction signal at the current order M, and the dual-channel pulse generator returns to the off state.
  • it also includes:
  • the transmitter controller controls the dual pulse generator to generate an optical output that prolongs the transmission time of one data frame.
  • it also includes the calculation of the delay time of the rising edge of the first pulse control signal and the calculation of the delay time of the rising edge of the second pulse control signal;
  • the delay time calculation of the rising edge includes:
  • the pulse control signal is the first pulse control signal or the second pulse control signal
  • T is the rising edge delay time of the LED lamp bead of the optical transmitter tested at the last level
  • A is the attenuation coefficient
  • the attenuation coefficient is the absolute value of the tangent slope of the factory light decay curve of the LED lamp bead.
  • the present invention discloses a demodulation method for an adaptive dimming visible light communication system. Based on the above-mentioned adaptive dimming visible light communication system, the method includes:
  • the third photoelectric sensor and the fourth photoelectric sensor collect optical signals and convert the optical signals into electrical signals
  • the analog switch gates the effective signals of the visible light signal and the infrared signal, and inputs the gated result to the receiver controller;
  • the receiver controller When the receiver controller detects that the modulation order of the gating branch changes, the receiver controller outputs a corresponding new demodulation order, and the adaptive M-PAM demodulator uses the new demodulation order demodulate the effective signal by number; when the receiver controller does not detect the change of the modulation order of the gating branch, the adaptive M-PAM demodulator demodulates the effective signal;
  • the receiver controller When the receiver controller detects an optical path switching signal, the receiver controller sends a switching instruction to the analog switch and the adaptive M-PAM demodulator, the analog switch switches to another optical path, the The adaptive M-PAM demodulator selects the demodulation order corresponding to the other optical path to demodulate.
  • the receiver controller When the receiver controller detects the transformed M' modulation order of the adaptive M-PAM modulator, the receiver controller obtains the M' demodulation order according to the M' modulation order;
  • the receiver controller transmits the M' demodulation order to the adaptive M-PAM demodulator to update the demodulation order.
  • the present invention can eliminate the delay problem caused by the rising edge and the falling edge of the actual dimming pulse signal, and realize the alternate transmission of high-efficiency mixed signals without interval and delay.
  • the adaptive M-PAM signal of the present invention does not depend on high-performance visible light and infrared LEDs, and is simple to deploy and has strong portability.
  • the bit error rate is not limited by the use time and life of the LED, and the most efficient adaptive M-PAM modulation order can be adaptively adopted.
  • the signal can be separated, so that the visible light signal and the infrared signal can be transmitted independently without interfering with each other, and the bit error rate can be effectively reduced.
  • Fig. 1 is the visible light communication system diagram of adaptive dimming of the present invention
  • Fig. 2 is the algorithm flow chart of the dual-channel dimming pulse generator
  • Figure 3 is a timing waveform diagram of a dual-channel dimming pulse generator
  • Figure 4 shows typical waveforms of visible light and infrared emitters in one dimming pulse period
  • Fig. 5 is the signal waveform entering into the adaptive M-PAM demodulator
  • Figure 6 shows the bit error rate of the adaptive M-PAM mixed modulation signal under different duty ratios.
  • the present invention discloses an adaptive dimming visible light communication system, including a signal source, an adaptive M-PAM modulator, a transmitter controller, a visible light transmitter, an infrared light transmitter and Dual pulse generator.
  • the adaptive M-PAM modulator is connected with the signal source, and the adaptive M-PAM modulator modulates the signal sent by the signal source into a first electrical signal and a second electrical signal respectively.
  • the visible light transmitter is connected with the adaptive M-PAM modulator, and the visible light transmitter converts the second electrical signal into visible light.
  • the infrared light transmitter is connected with the adaptive M-PAM modulator, and the infrared light transmitter converts the first electrical signal into infrared light.
  • the dual pulse generator generates the first pulse control signal and the second pulse control signal alternately, the first pulse control signal and the second pulse control signal are both periodic signals, and the first pulse control signal is connected with the visible light signal transmitter to control the visible light
  • the signal transmitter works
  • the second pulse control signal is connected with the infrared light transmitter to control the infrared light transmitter to work.
  • the second pulse control signal starts to be generated.
  • the first pulse control signal starts to be generated.
  • the present invention discloses a dual-channel pulse generation method, based on the above-mentioned adaptive dimming visible light communication system, comprising: when the remaining working time of the high level of the first pulse control signal is equal to the second pulse At the time of the rising edge of the signal, the second pulse control signal starts to be generated so that the infrared light signal and the visible light signal are continuously generated and switched without delay; when the transmitted data is the last data frame, a switching instruction signal is sent to the receiver, and the double The circuit pulse generator returns to the off state.
  • the present invention designs visible light and infrared into three modes, which are shutdown, preparation, and transmission.
  • the invention also includes a first photoelectric sensor, a second photoelectric sensor and a transmitter controller, and the transmitter controller is respectively connected with the first photoelectric sensor and the second photoelectric sensor.
  • the first photoelectric sensor collects the light intensity of visible light emitted by the visible light transmitter
  • the second photoelectric sensor collects the light intensity of the infrared light emitted by the infrared light transmitter.
  • the transmitter controller controls the adaptive M-PAM modulator and the dual pulse generator according to the light intensity collected by the first photoelectric sensor and the second photoelectric sensor.
  • the receiving end of the visible light communication system includes a third photoelectric sensor, a fourth photoelectric sensor, an analog switch, a receiver controller and an adaptive M-PAM demodulator.
  • the third photoelectric sensor collects the light signal emitted by the visible light transmitter
  • the fourth photoelectric sensor collects the light signal emitted by the infrared light transmitter
  • the receiver controller is connected with the analog switch and the adaptive M-PAM demodulator.
  • the analog switch is connected with the third photoelectric sensor and the fourth sensor to select the effective signal of the visible light signal and the infrared signal, and the effective signal is demodulated by the adaptive M-PAM demodulator and output to the sink.
  • the present invention also includes a first visible light filter, a first infrared light filter, a second visible light filter and a second infrared light filter.
  • the first visible light filter is arranged at the detection end of the first photoelectric sensor, and the first infrared light filter is arranged at the detection end of the second photoelectric sensor.
  • the second visible light filter is arranged at the detection end of the third photoelectric sensor, and the second infrared light filter is arranged at the detection end of the fourth photoelectric sensor.
  • the bandwidth requirement is low, and the sensor only needs to detect the intensity of visible light, and the sensor is sensitive in the visible light band.
  • the bandwidth requirement is low, and it only needs to detect the intensity of infrared light, and the sensor is sensitive in the infrared band.
  • the bandwidth requirement is relatively high, and it detects visible light communication signals, and the sensor is sensitive in the visible light band.
  • the fourth sensor its bandwidth requirement is relatively high, and the sensor is sensitive in the visible light band to detect infrared communication signals.
  • the invention also discloses a modulation and demodulation method for an adaptive dimming visible light communication system. Based on the above-mentioned adaptive dimming visible light communication system, the following steps are included:
  • Step 1 Obtain the optimal light intensity I 0 of the LED lamp of the optical transmitter when it leaves the factory.
  • the optical transmitter is a visible light transmitter or an infrared transmitter.
  • Step 2 Collect the average light intensity I i of the LED lamp in one transmission period through a photoelectric sensor.
  • the photoelectric sensor is the photoelectric sensor corresponding to the light transmitter
  • the visible light transmitter is corresponding to the first photoelectric sensor
  • the infrared light transmitter is corresponding to the second photoelectric sensor.
  • the light decay D w 1 d i +w 2 d(t) is obtained, where w 1 and w 2 are weights.
  • the transmitter controller needs to obtain the orders corresponding to visible light and infrared light respectively.
  • the adaptive M-PAM modulator can use the corresponding orders of visible light and infrared light to adjust the corresponding light beams.
  • Step 6 When the transmitter controller detects that the order M needs to be changed, the transmitter controller transmits the changed M' modulation order to the adaptive M-PAM modulator.
  • the adaptive M-PAM modulator controls the optical transmitter to transmit the optical signal of the current order M that needs to be transformed, and the optical signal that needs to be transformed carries the transformed order M'.
  • the photoelectric sensor at the receiving end converts the optical signal carrying the M' modulation order into an electrical signal carrying the M' modulation order.
  • the receiver controller obtains the electrical signal carrying the M' modulation order, and obtains the M' demodulation order according to the electrical signal carrying the M' modulation order.
  • the receiver controller transmits the M' demodulation order to the adaptive M-PAM demodulator, and the adaptive M-PAM demodulator performs a demodulation operation on the communication signal according to the M' demodulation order.
  • the modulation order of the transmitting end is adaptively adjusted according to the light intensity of the optical transmitter, and when the modulation order of the transmitting end is adaptively adjusted, the demodulation order of the receiving end can also be adjusted by The above steps are changed synchronously, thereby realizing adaptive demodulation.
  • the modulation and demodulation method for the above visible light communication system further includes: when the dual-channel dimming pulse generator detects that the transmitted data is the last data frame, the dual-channel dimming pulse generator controls the adaptive M-PAM modulator An electrical signal carrying dual-channel switching is generated, the adaptive M-PAM modulator controls the optical transmitter to transmit a dual-channel switching instruction signal at the current order M, and the dual-channel pulse generator returns to the off state.
  • the transmitter controller controls the dual pulse generator to generate an optical output that prolongs the transmission time of one data frame.
  • the first pulse control signal is connected to the visible light transmitter
  • the second pulse control signal is connected to the infrared light transmitter.
  • the delay time calculation of the rising edge includes:
  • Step 1 Determine the light attenuation level of the LED of the optical transmitter corresponding to the pulse control signal, wherein the pulse control signal is the first pulse control signal or the second pulse control signal.
  • Step 2 Calculate the rising edge delay time of the light beam emitted by the optical transmitter corresponding to the pulse control signal Among them, T is the rising edge delay time of the LED lamp bead of the optical transmitter tested at the last level, A is the attenuation coefficient, and the attenuation coefficient is the absolute value of the tangent slope of the factory light decay curve of the LED lamp bead.
  • the M order of the adaptive M-PAM can be dynamically adjusted according to the current performance of the lamp bead and the time of preparation in the dual-channel dimming pulse generator, which can complete the two-channel signal without interval and delay.
  • Alternate transmission can also make the adaptive M-PAM modulation signal match the performance of the LED lamp beads in real time, reduce the signal distortion caused by the aging of the device, and reduce the bit error rate.
  • the present invention adopts the bipolar adaptive M-PAM signal. , so it has little impact on the dimming accuracy, can meet the high-precision dimming requirements, and enhance the practicability and stability of the system.
  • the present invention also discloses a demodulation method for an adaptive dimming visible light communication system. Based on the above-mentioned adaptive dimming visible light communication system, the method includes the following steps:
  • Step 1 The third photoelectric sensor and the fourth photoelectric sensor collect optical signals, and convert the optical signals into electrical signals.
  • Step 2 The analog switch gates the effective signals of the visible light signal and the infrared signal, and inputs the gated result to the receiver controller.
  • Step 3 When the receiver controller detects that the modulation order of the gating branch changes, the receiver controller outputs the corresponding new demodulation order, and the adaptive M-PAM demodulator uses the new demodulation order. Demodulate the effective signal; when the receiver controller does not detect the change of the modulation order of the gating branch, the adaptive M-PAM demodulator demodulates the effective signal.
  • the receiver controller detects the optical path switching signal, the receiver controller sends a switching instruction to the analog switch and the adaptive M-PAM demodulator, the analog switch switches to another optical path, and the adaptive M-PAM demodulator Select the demodulation order corresponding to the other optical path for demodulation.
  • the receiver controller when the receiver controller detects the transformed M' modulation order of the adaptive M-PAM modulator, the receiver controller obtains the M' demodulation order according to the M' modulation order. The receiver controller transmits the M' demodulation order to the adaptive M-PAM demodulator to update the demodulation order.
  • the present invention can eliminate the delay problem caused by the rising edge and the falling edge of the actual dimming pulse signal, and realize the alternate transmission of high-efficiency mixed signals without interval and delay.
  • the adaptive M-PAM signal does not depend on high-performance visible light and infrared LEDs, which is easy to deploy and has strong portability.
  • the bit error rate is not limited by the use time and life of the LED, and the most efficient adaptive M-PAM modulation order can be adaptively adopted.
  • the signal can be separated, so that the visible light signal and the infrared signal can be transmitted independently without interfering with each other, and the bit error rate can be effectively reduced.
  • bipolar adaptive M-PAM signal its average amplitude is 0, which does not affect the dimming accuracy.
  • the present invention is applied under the condition that the duty cycle is 35.8%, and the data transmission rate is 10Mbit/s, which is 13.6% higher than that of the existing visible light communication system supporting dimming control using adaptive M-PAM modulation. , the bit error rate is stable below 10 -4 .
  • Table 1 shows the corresponding relationship between the service life of visible light and infrared LEDs and their modulation adaptive M-PAM orders.
  • the adaptive M-PAM-32 is used for modulation and demodulation, and then the two adaptive M-PAM orders are adjusted and mixed according to their aging degree. To reduce signal distortion and bit error rate.
  • Figure 4 shows typical waveforms of visible light and infrared emitters in one dimming pulse period.
  • Figure 5 it is the signal waveform of the signal entering the adaptive M-PAM demodulator.
  • the visible light and infrared signals are transmitted without interval and delay at the transmitting end, and the signal separation is realized through the control of two photoelectric sensors, an analog switch and a receiver controller at the receiving end, and the visible light and infrared signals are eliminated.
  • the mutual interference of the two falling edge signals reduces the distortion of the signal.
  • bit error rate of adaptive M-PAM hybrid modulation signal transmission is stabilized below 10 -4 , which improves the system stability.
  • the present invention improves an adaptive dimming control visible light communication system, which can realize the alternate transmission of high-efficiency mixed signals without interval and delay.
  • the dual-channel dimming pulse generator is designed for three modes of signal: close, prepare, and transmit.
  • the present invention generates a method for alternately switching dimming pulse signals with no interval and no delay, and realizes clock synchronization by adding an indication signal to the last data frame of transmission.
  • the receiving end separates the two signals to eliminate the interference of the falling edge on the receiving end.
  • the present invention uses bipolar adaptive M-PAM signal to replace the original OFDM signal, which reduces the complexity of actual system implementation and enhances portability.
  • M-PAM modulation order can be dynamically adjusted according to the use time of the lamp bead, instead of using a constant modulation order, which enhances the stability of the system in the actual system and does not depend on continuous high-performance lamp beads.
  • the bipolar adaptive M-PAM signal will not affect the dimming accuracy.
  • the present invention solves the problem not only limited to visible light and infrared, but any dual or multi-channel mixed signal alternation through the design switching of three modes of shutdown, preparation and transmission. Interval, delay and signal synchronization issues during transmission.
  • the present invention realizes complete signal separation at the receiving end, so that there is almost no mutual interference between mixed signals, and there is no need to pass the judgment step for the mixed signals, thereby effectively improving the transmission quality and efficiency.
  • the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
  • computer-usable storage media including, but not limited to, disk storage, CD-ROM, optical storage, etc.
  • These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions
  • the apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

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Abstract

本发明涉及一种自适应调光的可见光通信系统及调制解调方法，包括：信源；自适应M-PAM调制器将信源发出的信号分别调制成第一电信号和第二电信号；双路脉冲产生器，其交替产生第一脉冲控制信号和第二脉冲控制信号，第一脉冲控制信号和第二脉冲控制信号皆为周期性信号；当第一脉冲控制信号的高电平的剩余工作时间等于第二脉冲信号的上升沿的时间时，第二脉冲控制信号开始产生；当第二脉冲控制信号的高电平的剩余工作时间等于第一脉冲信号的上升沿的时间时，第一脉冲控制信号开始产生。其实现了可见光和红外双路信号的无间隔、无延迟切换，随时可以加载自适应M-PAM调制信号。

Description

自适应调光的可见光通信系统及调制解调方法 技术领域
本发明涉及光通信技术领域，尤其是指一种自适应调光的可见光通信系统及调制解调方法。
背景技术
随着5G和大数据技术的发展，人们对网络的速度和覆盖程度产生了更高的需求。对于传统的电磁波通信，由于其无法穿透金属，以及频谱资源受限，因此无法实现对于金属密闭及需要电磁屏蔽空间的信号覆盖传输。近年来，使用LED的室内可见光通信系统由于具有速率高、安全、节能环保、频谱资源丰富等优势，成为了解决传统电磁波通信的热门技术。尽管可见光通信系统兼有照明和通信的功能，但是前者的优先级在系统设计中的优先级更高。实际上，为了适应不同应用场景和节能环保的要求，LED的亮度等级需要进行调整，因此，支持调光控制的可见光通信系统已成为研究的热点。然而，由于其实现原理和系统复杂度的限制，还是存在着无法同时支持全光域调光和信号稳定传输的困难，限制了该系统的普及速度和应用范围。
中国专利公开号为CN103763829A的专利公开了一种基于OFDM信号的光源调光方法，其基于MPPM调光控制的混合可见光通信系统，正交频分复用(OFDM)与多脉冲位置调制(MPPM)相结合,不仅支持高速可见光通信,同时满足了用户对照明源的亮度调节的需求。这种混合调制方法确保系统具有MPPM的调光功能,且引入的OFDM传输可以有效地提高频谱效率。基于MPPM调光控制方案的传输速率受限于调光控制信号的占空比大小，因此在需求可见光光强较弱，甚至完全黑暗的环境下，此系统无法实现信号的稳定传输，实现全光域调光。并且此系统没有考虑实际MPPM信号的上升沿和下降沿延迟时 间，在实际情况中，OFDM信号的传输易受到上升沿和下降沿的干扰，因此无法实现理论的高传输速率和低误码率。
中国专利公开号为201610320643.3的专利公开了一种红外补偿全范围调光的可见光OFDM通信装置；该方法是既可以全范围调光又可以传输OFDM信号，且调光时对OFDM信号的传输速率、传输质量造成较小影响，能够降低传统方案中信号传输性能对调光占空比的依赖性，并有效降低系统复杂度。
现有技术存在以下缺陷：
1、基于MPPM调光控制方案的传输速率受限于调光控制信号的占空比大小，因此在需求可见光光强较弱，甚至完全黑暗的环境下，此系统无法实现信号的稳定传输，实现全光域调光。并且此系统没有考虑实际MPPM信号的上升沿和下降沿延迟时间，在实际情况中，OFDM信号的传输易受到上升沿和下降沿的干扰，因此无法实现理论的高传输速率和低误码率。
2、对于使用红外补偿全范围调光的可见光OFDM通信系统，调光脉冲信号上升沿和下降沿限制了可见光和红外信号的交替传输。现有的商用可见光照明LED和红外发射器的阶跃响应特性较差，若不考虑高低电平的上升沿和下降沿延迟时间，交替传输的速率和质量会大大下降，而此技术方案无法有效滤除可见光和红外LED的下降沿信号干扰，在某些脉冲调制方式下的特定占空比中，误码率和传输速率甚至不如不加入红外补偿的传输方式。
3、使用红外补偿全范围调光的可见光OFDM通信系统在接收端无法做到可见光和红外两路信号的分离，两路信号在接收端会形成干扰，使误码率升高。
4、OFDM复杂度较高，尤其在实时系统实现时，研发周期较长。并且OFDM信号的峰均比较高，要求光源的线性工作区范围要很大，导致最大发射功率需要很大，同时器件、驱动电路等成本也会上升,而更大的功率带来的是更差的频率响应，会降低带宽。此外，随着LED使用时间的积累，OFDM信号无法自动适应由于老化而性能降低的灯珠，造成信号的失真，误码率提高。使用 OFDM信号只能在理想实验环境下提升速率，不适用于具体实际的应用场景中。
5、现有技术中，系统实际实现过程中的上升沿和下降沿延迟时间，即准备时间，会导致传输效率降低，双路混合信号之间相互干扰，误码率升高等问题。
发明内容
为此，本发明所要解决的技术问题在于提供一种自适应调光的可见光通信系统及调制解调方法，其实现了可见光和红外双路信号的无间隔、无延迟切换，随时可以加载自适应M-PAM调制信号。
为解决上述技术问题，本发明提供了一种自适应调光的可见光通信系统，其特征在于，包括：
信源；
自适应M-PAM调制器，其与信源连接，所述自适应M-PAM调制器将所述信源发出的信号分别调制成第一电信号和第二电信号；
可见光发射机，其与所述自适应M-PAM调制器连接，所述可见光发射机将所述第二电信号转换成可见光；
红外光发射机，其与所述自适应M-PAM调制器连接，所述红外光发射机将所述第一电信号转换成红外光；
双路脉冲产生器，其交替产生第一脉冲控制信号和第二脉冲控制信号，所述第一脉冲控制信号和第二脉冲控制信号皆为周期性信号，所述第一脉冲控制信号与可见光信号发射机连接以控制可见光信号发射机工作，所述第二脉冲控制信号与红外光发射机连接以控制红外光发射机工作；
当所述第一脉冲控制信号的高电平的剩余工作时间等于所述第二脉冲信号的上升沿的时间时，所述第二脉冲控制信号开始产生；
当所述第二脉冲控制信号的高电平的剩余工作时间等于所述第一脉冲信号的上升沿的时间时，所述第一脉冲控制信号开始产生。
作为优选的，还包括第一光电传感器、第二光电传感器和发射机控制器,所述发射机控制器分别与所述第一光电传感器和第二光电传感器连接；
所述第一光电传感器采集所述可见光发射机发射出的可见光的光强，所述第二光电传感器采集所述红外光发射机发射出的红外光的光强；
所述发射机控制器根据第一光电传感器和第二光电传感器采集的光强对自适应M-PAM调制器和双路脉冲产生器进行控制。
作为优选的，所述可见光通信系统的接收端包括第三光电传感器、第四光电传感器、模拟开关、接收机控制器和自适应M-PAM解调器；
所述第三光电传感器采集可见光发射机发射的光信号，所述第四光电传感器采集红外光发射机发射的光信号；
所述接收机控制器与模拟开关和自适应M-PAM解调器连接；
所述模拟开关与所述第三光电传感器和第四传感器连接以对可见光信号和红外信号的有效信号的进行选通，所述有效信号经所述自适应M-PAM解调器解调后输出至信宿。
作为优选的，还包括第一可见光滤镜、第一红外光滤镜、第二可见光滤镜和第二红外光滤镜；
所述第一可见光滤镜设置在所述第一光电传感器的探测端，所述第一红外光滤镜设置在所述第二光电传感器的探测端；
所述第二可见光滤镜设置在所述第三光电传感器的探测端，所述第二红外光滤镜设置在所述第四光电传感器的探测端。
本发明公开了一种自适应调光的可见光通信系统的调制及解调方法，基于上述的自适应调光的可见光通信系统，包括以下步骤：
获取光发射机的LED灯的出厂时的最佳光强I 0；
通过光电传感器采集LED灯在一个传输周期内的平均光强I i；
计算实际实时光强衰减d i＝(I 0-I i)/I o，并根据LED灯使用时间对应其出厂光衰曲线中的理论光强衰减d(t)，进行加权运算，得到光衰D＝w 1d i+w 2d(t)，w 1、w 2为权重；
将光衰D分为N个等级，N由LED灯的带宽决定，规定N＝BW/100k,第n级的光衰D范围为
Figure PCTCN2021088356-appb-000001
发射机控制器求得阶数M＝[32/n]；
当发射机控制器检测到阶数M需要改变时，发射机控制器将改变后的M’调制阶数传输给自适应M-PAM调制器；
所述自适应M-PAM调制器控制光发射机以当前阶数M发射需要变换阶数的光信号，所述需要变换阶数的光信号携带变换后的阶数M’；
接收端的光电传感器将携带M’调制阶数的光信号转换成携带M’调制阶数的电信号；
所述接收机控制器获取携带M’调制阶数的电信号，并根据携带M’调制阶数的电信号获得M’解调阶数；
所述接收机控制器将得M’解调阶数传输至自适应M-PAM解调器，所述自适应M-PAM解调器根据所述M’解调阶数对通信信号做解调操作。
作为优选的，包括：
当所述双路调光脉冲产生器检测到所传数据为最后一个数据帧时，所述双路调光脉冲产生器控制自适应M-PAM调制器产生携带双路切换的电信号，所述自适应M-PAM调制器控制光发射机以当前阶数M发射双路切换指示信号，所述双路脉冲产生器返回关闭状态。
作为优选的，还包括：
当变换阶数M控制信号与切换信号同时到达自适应M-PAM调制器，则发射机控制器控制双路脉冲产生器产生延长一个数据帧的传输时间的光输出。
作为优选的，还包括第一脉冲控制信号的上升沿的延迟时间计算和第二脉冲控制信号的上升沿的延迟时间计算；
所述上升沿的延迟时间计算包括：
判断脉冲控制信号对应的光发射机的LED的光衰等级，其中，所述脉冲控制信号为第一脉冲控制信号或第二脉冲控制信号；
计算脉冲控制信号对应的光发射机发射的光束的上升沿延迟时间
Figure PCTCN2021088356-appb-000002
其中，T为光发射机的LED灯珠在最后一个等级经过测试的上升沿延迟时间，A为衰减系数，所述衰减系数为LED灯珠的出厂的光衰曲线的切线斜率的绝对值。
本发明公开了一种自适应调光的可见光通信系统的解调方法，基于上述的自适应调光的可见光通信系统，包括：
第三光电传感器和第四光电传感器采集光信号，并将光信号转换成电信号；
所述模拟开关对可见光信号和红外信号的有效信号的进行选通，并将选通结果输入至接收机控制器；
当接收机控制器检测到选通支路的调制阶数变化时，所述接收机控制器输出对应的新的解调阶数，所述自适应M-PAM解调器使用新的解调阶数对有效信号解调；当所述接收机控制器未检测到选通支路的调制阶数变化时，所述自适应M-PAM解调器对有效信号解调；
当接收机控制器检测到光通路切换信号时，所述接收机控制器向所述模拟开关和自适应M-PAM解调器发送切换指示，所述模拟开关切换至另一光通路，所述自适应M-PAM解调器选用另一路光通路对应的解调阶数解调。
作为优选的，包括:
当所述接收机控制器检测到自适应M-PAM调制器的变换后的M’调制阶数时，所述接收机控制器根据M’调制阶数获得M’解调阶数；
所述接收机控制器将M’解调阶数传输至自适应M-PAM解调器以更新解调阶数。
本发明的上述技术方案相比现有技术具有以下优点：
1、本发明可以消除实际调光脉冲信号上升沿和下降沿所带来的延迟问题，实现无间隔、无延迟的高效混合信号交替传输。
2、本发明自适应M-PAM信号不依赖于高性能的可见光和红外LED，部署简单，可移植性强。
3、误码率不受LED使用时间和寿命的限制，可以自适应采用最高效的自适应M-PAM调制阶数。
4、可以对信号进行分离，使得可见光信号和红外信号独立传输，互不干扰,有效降低误码率。
附图说明
图1是本发明自适应调光的可见光通信系统图；
图2为双路调光脉冲产生器算法流程图；
图3为双路调光脉冲产生器时序波形图；
图4为可见光和红外发射器在一个调光脉冲周期内的典型波形；
图5为进入自适应M-PAM解调器的信号波形；
图6为自适应M-PAM混合调制信号在不同占空比下误码率。
具体实施方式
下面结合附图和具体实施例对本发明作进一步说明，以使本领域的技术人员可以更好地理解本发明并能予以实施，但所举实施例不作为对本发明的限定。
参照图1-图3所示，本发明公开了一种自适应调光的可见光通信系统，包括信源、自适应M-PAM调制器、发射机控制器、可见光发射机、红外光发射机和双路脉冲产生器。
自适应M-PAM调制器与信源连接，自适应M-PAM调制器将信源发出的信号分别调制成第一电信号和第二电信号。
可见光发射机与自适应M-PAM调制器连接，可见光发射机将第二电信号转换成可见光。
红外光发射机与自适应M-PAM调制器连接，红外光发射机将第一电信号转换成红外光。
双路脉冲产生器交替产生第一脉冲控制信号和第二脉冲控制信号，第一脉冲控制信号和第二脉冲控制信号皆为周期性信号，第一脉冲控制信号与可见光信号发射机连接以控制可见光信号发射机工作，第二脉冲控制信号与红外光发射机连接以控制红外光发射机工作。
当第一脉冲控制信号的高电平的剩余工作时间等于第二脉冲信号的上升 沿的时间时，第二脉冲控制信号开始产生。当第二脉冲控制信号的高电平的剩余工作时间等于第一脉冲信号的上升沿的时间时，第一脉冲控制信号开始产生。
参见图2所示，本发明公开了一种双路脉冲产生方法，基于上述的自适应调光的可见光通信系统，包括：当第一脉冲控制信号的高电平的剩余工作时间等于第二脉冲信号的上升沿的时间时，第二脉冲控制信号开始产生以使得红外光信号与可见光信号无间断产生和无延迟切换；当所传数据为最后一个数据帧，向接收机发射一个切换指示信号，双路脉冲产生器返回关闭状态。
本发明将可见光和红外设计为3个模式，分别为关闭、准备、传输，首先根据此路的上升沿需要时间和另一路传输剩余时间比较，若两者相等那么开始本路的上升沿，进入传输的准备状态，一旦另一路的传输结束，便可马上进行此路的信息传输，实现几乎无时间延迟的切换，接着，若所传数据为最后一个数据帧，那么就向接收机发射一个切换指示信号，然后返回关闭状态，其时序波形图如图3所示，这样实现了可见光和红外双路信号的无间隔、无延迟切换，随时可以加载自适应M-PAM调制信号。本发明还包括第一光电传感器、第二光电传感器和发射机控制器,发射机控制器分别与第一光电传感器和第二光电传感器连接。第一光电传感器采集可见光发射机发射出的可见光的光强，第二光电传感器采集红外光发射机发射出的红外光的光强。发射机控制器根据第一光电传感器和第二光电传感器采集的光强对自适应M-PAM调制器和双路脉冲产生器进行控制。可见光通信系统的接收端包括第三光电传感器、第四光电传感器、模拟开关、接收机控制器和自适应M-PAM解调器。第三光电传感器采集可见光发射机发射的光信号，第四光电传感器采集红外光发射机发射的光信号，接收机控制器与模拟开关和自适应M-PAM解调器连接。模拟开关与第三光电传感器和第四传感器连接以对可见光信号和红外信号的有效信号的进行选通，有效信号经自适应M-PAM解调器解调后输出至信 宿。
本发明还包括第一可见光滤镜、第一红外光滤镜、第二可见光滤镜和第二红外光滤镜。第一可见光滤镜设置在第一光电传感器的探测端，第一红外光滤镜设置在第二光电传感器的探测端。通过第一可见光滤镜和第一红外光滤镜，使得只有可见光进入第一光电传感器，红外光则进入第二光电传感器。而第二可见光滤镜设置在第三光电传感器的探测端，第二红外光滤镜设置在第四光电传感器的探测端。通过设置第二可见光滤镜和第二红外光滤镜，可使得只有红外光进入第四光电传感器，可见光进入第三光电传感器。
对于第一传感器，其带宽要求低，只需检测可见光光强，传感器在可见光波段灵敏。对于第二传感器，其带宽要求低，只需检测红外光强，传感器在红外波段灵敏。对于第三传感器，其带宽要求较高，检测可见光通信信号，传感器在可见光波段灵敏。对于第四传感器，其带宽要求较高，检测红外通信信号，传感器在可见光波段灵敏。
本发明还公开了一种自适应调光的可见光通信系统的调制及解调方法，基于上述的自适应调光的可见光通信系统，包括以下步骤：
步骤一、获取光发射机的LED灯的出厂时的最佳光强I 0。此处，光发射机为可见光发射机或者红外发射机。
步骤二、通过光电传感器采集LED灯在一个传输周期内的平均光强I i。此处，光电传感器即为光发射机对应的光电传感器，可见光发射机对应第一光电传感器，红外光发射机对应第二光电传感器。
步骤三、计算实际实时光强衰减d i＝(I 0-I i)/I o，并根据LED灯使用时间对应其出厂光衰曲线中的理论光强衰减d(t)，进行加权运算，得到光衰D＝w 1d i+w 2d(t)，w 1、w 2为权重。
步骤四、将光衰D分为N个等级，N由LED灯的带宽决定，规定N＝BW/100k,第n级的光衰D范围为
Figure PCTCN2021088356-appb-000003
步骤五、发射机控制器求得阶数M＝[32/n]。此处，发射机控制器需要分别获得可见光和红外光对应的阶数。如此，自适应M-PAM调制器可使用可见光和红外光对应的阶数调整对应的光束。
步骤六、当发射机控制器检测到阶数M需要改变时，发射机控制器将改变后的M’调制阶数传输给自适应M-PAM调制器。自适应M-PAM调制器控制光发射机以当前阶数M发射需要变换阶数的光信号，需要变换阶数的光信号携带变换后的阶数M’。接收端的光电传感器将携带M’调制阶数的光信号转换成携带M’调制阶数的电信号。接收机控制器获取携带M’调制阶数的电信号，并根据携带M’调制阶数的电信号获得M’解调阶数。接收机控制器将得M’解调阶数传输至自适应M-PAM解调器，自适应M-PAM解调器根据M’解调阶数对通信信号做解调操作。通过上述方式，发射端的调制阶数根据光发射机的光强，对发射端的调制阶数做自适应调整，而当发射端的调制阶数做自适应调整时，接收端的解调阶数也可通过上述步骤同步变化，从而实现自适应解调。
对于上述可见光通信系统的调制及解调方法，还包括：当双路调光脉冲产生器检测到所传数据为最后一个数据帧时，双路调光脉冲产生器控制自适应M-PAM调制器产生携带双路切换的电信号，自适应M-PAM调制器控制光发射机以当前阶数M发射双路切换指示信号，双路脉冲产生器返回关闭状态。
而当变换阶数M控制信号与切换信号同时到达自适应M-PAM调制器，则发射机控制器控制双路脉冲产生器产生延长一个数据帧的传输时间的光输出。
本发明中，需要对于第一脉冲控制信号的上升沿的延迟时间计算和第二脉冲控制信号的上升沿的延迟时间计算。第一脉冲控制信号与可见光发射机 连接，第二脉冲控制信号与红外光发射机连接，通过分别获取第一脉冲和第二脉冲上升沿的时间，可以实现红外光和可见光发射的的无间隔切换。
而上升沿的延迟时间计算包括：
步骤一、判断脉冲控制信号对应的光发射机的LED的光衰等级，其中，脉冲控制信号为第一脉冲控制信号或第二脉冲控制信号。
步骤二、计算脉冲控制信号对应的光发射机发射的光束的上升沿延迟时间
Figure PCTCN2021088356-appb-000004
其中，T为光发射机的LED灯珠在最后一个等级经过测试的上升沿延迟时间，A为衰减系数，衰减系数为LED灯珠的出厂的光衰曲线的切线斜率的绝对值。通过所提出的算法，可以根据灯珠目前的性能动态调整自适应M-PAM的M阶数以及双路调光脉冲产生器中从何时刻进行准备，既能完成两路信号的无间隔无延迟交替传输，也能够使得自适应M-PAM调制信号实时匹配LED灯珠性能，减小由于器件使用老化而带来的信号失真，降低误码率，本发明采用双极性自适应M-PAM信号，因此对调光精度影响较小，可以满足高精度的调光需求，增强系统的实用性和稳定性。
本发明还公开了一种自适应调光的可见光通信系统的解调方法，基于上述的自适应调光的可见光通信系统，包括以下步骤：
步骤一、第三光电传感器和第四光电传感器采集光信号，并将光信号转换成电信号。
步骤二、模拟开关对可见光信号和红外信号的有效信号的进行选通，并将选通结果输入至接收机控制器。
步骤三、当接收机控制器检测到选通支路的调制阶数变化时，接收机控制器输出对应的新的解调阶数，自适应M-PAM解调器使用新的解调阶数对有效信号解调；当接收机控制器未检测到选通支路的调制阶数变化时，自适应 M-PAM解调器对有效信号解调。当接收机控制器检测到光通路切换信号时，接收机控制器向模拟开关和自适应M-PAM解调器发送切换指示，模拟开关切换至另一光通路，自适应M-PAM解调器选用另一路光通路对应的解调阶数解调。
具体的，当接收机控制器检测到自适应M-PAM调制器的变换后的M’调制阶数时，接收机控制器根据M’调制阶数获得M’解调阶数。接收机控制器将M’解调阶数传输至自适应M-PAM解调器以更新解调阶数。
本发明的有益效果如下：
1、本发明可以消除实际调光脉冲信号上升沿和下降沿所带来的延迟问题，实现无间隔、无延迟的高效混合信号交替传输。
2.自适应M-PAM信号不依赖于高性能的可见光和红外LED，部署简单，可移植性强。
3.误码率不受LED使用时间和寿命的限制，可以自适应采用最高效的自适应M-PAM调制阶数。
4.可以对信号进行分离，使得可见光信号和红外信号独立传输，互不干扰,有效降低误码率。
5.使用双极性自适应M-PAM信号，其幅度均值为0，不影响调光精度。
下面，结合具体实施例对本发明的方案进行进一步说明。
为了评估所提出的自适应调光控制可见光通信系统，我们在不同的占空比和LED使用时间下，评估其传输速率和误码率。下面使本发明在占空比为35.8％的情况下应用，实现了速率为10Mbit/s的数据传输，比现有使用自适应M-PAM调制的支持调光控制的可见光通信系统速率提升13.6％，误码率稳定低于10 -4。
表1为可见光和红外LED使用寿命和其调制自适应M-PAM阶数对应关系。
表1
可见光LED使用时长/h 0-2500 2500-6000 6000-8000 8000-10000 10000+
可见光调制自适应M-PAM阶数 32 16 8 4 2
红外LED使用时长/h 0-1600 1600-4800 4800-6400 6400-8000 8000+
红外调制自适应M-PAM阶数 32 16 8 4 2
如表1所示，在可见光和红外LED有最佳性能时，采用自适应M-PAM-32进行调制解调，而后根据其衰老程度，对两路自适应M-PAM阶数进行调整混合，以减小信号失真和误码率。
如图4所示，为可见光和红外发射器在一个调光脉冲周期内的典型波形。如图5所示，为信号进入自适应M-PAM解调器的信号波形。通过所提出的系统，在发射端实现了可见光和红外信号的无间隔、无延迟发射，通过接收端的两个光电传感器、模拟开关以及接收机控制器控制，实现了信号分离，消除了可见光和红外两路下降沿信号的互相干扰，减小了信号的失真。
如图6所示，在不同的占空比下，自适应M-PAM混合调制信号传输的误码率稳定于10 -4以下,提升了系统稳定性。
本发明具有以下优点：
1、本发明提高了一种自适应调光控制可见光通信系统，可以实现无间隔、无延迟的高效混合信号交替传输。
2、双路调光脉冲产生器对于信号三种模式，关闭、准备、传输三种模式的设计。
3、本发明产生双路无间隔、无延时交替切换调光脉冲信号的方法，通过在传输最后一个数据帧加入指示信号实现时钟同步的方法。
4、根据LED使用寿命调节自适应M-PAM信号阶数、计算上升沿延迟时间。
5、接收端对两路信号的分离，消除下降沿对接收端的干扰。
6、本发明使用双极性自适应M-PAM信号代替原有的OFDM信号，降低了实际系统实现复杂度，增强移植性。并且能够根据灯珠的使用时长来动态调整M-PAM调制阶数，而不是使用恒定的调制阶数，增强了系统在实际系统中的稳定性，不依赖于持续高性能的灯珠。同时，双极性自适应M-PAM信号不会影响调光精度。
7、本发明根据实际实现系统中的上升沿和下降沿延迟时间，通过关闭、准备、传输三个模式的设计切换，解决了不仅限于可见光和红外，而是任何双路或多路混合信号交替传输时的间隔、延迟和信号同步问题。
8、本发明在接收端实现了完全的信号分离，使得混合信号之间几乎没有互相干扰，且不需要通过对混合信号的判决步骤，有效提高了传输质量和效率。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然，上述实施例仅仅是为清楚地说明所作的举例，并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (10)

  1. 一种自适应调光的可见光通信系统，其特征在于，包括：
    信源；
    自适应M-PAM调制器，其与信源连接，所述自适应M-PAM调制器将所述信源发出的信号分别调制成第一电信号和第二电信号；
    可见光发射机，其与所述自适应M-PAM调制器连接，所述可见光发射机将所述第二电信号转换成可见光；
    红外光发射机，其与所述自适应M-PAM调制器连接，所述红外光发射机将所述第一电信号转换成红外光；
    双路脉冲产生器，其交替产生第一脉冲控制信号和第二脉冲控制信号，所述第一脉冲控制信号和第二脉冲控制信号皆为周期性信号，所述第一脉冲控制信号与可见光信号发射机连接以控制可见光信号发射机工作，所述第二脉冲控制信号与红外光发射机连接以控制红外光发射机工作；
    当所述第一脉冲控制信号的高电平的剩余工作时间等于所述第二脉冲信号的上升沿的时间时，所述第二脉冲控制信号开始产生；
    当所述第二脉冲控制信号的高电平的剩余工作时间等于所述第一脉冲信号的上升沿的时间时，所述第一脉冲控制信号开始产生。
  2. 根据权利要求1所述的自适应调光的可见光通信系统，其特征在于，还包括第一光电传感器、第二光电传感器和发射机控制器,所述发射机控制器分别与所述第一光电传感器和第二光电传感器连接；
    所述第一光电传感器采集所述可见光发射机发射出的可见光的光强，所 述第二光电传感器采集所述红外光发射机发射出的红外光的光强；
    所述发射机控制器根据第一光电传感器和第二光电传感器采集的光强对自适应M-PAM调制器和双路脉冲产生器进行控制。
  3. 根据权利要求2所述的自适应调光的可见光通信系统，其特征在于，所述可见光通信系统的接收端包括第三光电传感器、第四光电传感器、模拟开关、接收机控制器和自适应M-PAM解调器；
    所述第三光电传感器采集可见光发射机发射的光信号，所述第四光电传感器采集红外光发射机发射的光信号；
    所述接收机控制器与模拟开关和自适应M-PAM解调器连接；
    所述模拟开关与所述第三光电传感器和第四传感器连接以对可见光信号和红外信号的有效信号的进行选通，所述有效信号经所述自适应M-PAM解调器解调后输出至信宿。
  4. 根据权利要求3所述的自适应调光的可见光通信系统，其特征在于，还包括第一可见光滤镜、第一红外光滤镜、第二可见光滤镜和第二红外光滤镜；
    所述第一可见光滤镜设置在所述第一光电传感器的探测端，所述第一红外光滤镜设置在所述第二光电传感器的探测端；
    所述第二可见光滤镜设置在所述第三光电传感器的探测端，所述第二红外光滤镜设置在所述第四光电传感器的探测端。
  5. 一种自适应调光的可见光通信系统的调制及解调方法，基于权利要求1-4任一项所述的自适应调光的可见光通信系统，其特征在于，包括以下步骤：
    获取光发射机的LED灯的出厂时的最佳光强I 0；
    通过光电传感器采集LED灯在一个传输周期内的平均光强I i；
    计算实际实时光强衰减d i＝(I 0-I i)/I o，并根据LED灯使用时间对应其出厂光衰曲线中的理论光强衰减d(t)，进行加权运算，得到光衰D＝w 1d i+w 2d(t)，w 1、w 2为权重；
    将光衰D分为N个等级，N由LED灯的带宽决定，规定N＝BW/100k,第n级的光衰D范围为
    Figure PCTCN2021088356-appb-100001
    发射机控制器求得阶数M＝[32/n]；
    当发射机控制器检测到阶数M需要改变时，发射机控制器将改变后的M’调制阶数传输给自适应M-PAM调制器；
    所述自适应M-PAM调制器控制光发射机以当前阶数M发射需要变换阶数的光信号，所述需要变换阶数的光信号携带变换后的阶数M’；
    接收端的光电传感器将携带M’调制阶数的光信号转换成携带M’调制阶数的电信号；
    所述接收机控制器获取携带M’调制阶数的电信号，并根据携带M’调制阶数的电信号获得M’解调阶数；
    所述接收机控制器将得M’解调阶数传输至自适应M-PAM解调器，所述自适应M-PAM解调器根据所述M’解调阶数对通信信号做解调操作。
  6. 根据权利要求5所述的可见光通信系统的调制及解调方法，其特征在于，包括：
    当所述双路调光脉冲产生器检测到所传数据为最后一个数据帧时，所述双路调光脉冲产生器控制自适应M-PAM调制器产生携带双路切换的电信号，所述自适应M-PAM调制器控制光发射机以当前阶数M发射双路切换指示信号， 所述双路脉冲产生器返回关闭状态。
  7. 根据权利要求5所述的可见光通信系统的调制及解调方法，其特征在于，还包括：
    当变换阶数M控制信号与切换信号同时到达自适应M-PAM调制器，则发射机控制器控制双路脉冲产生器产生延长一个数据帧的传输时间的光输出。
  8. 根据权利要求5所述的可见光通信系统的调制及解调方法，其特征在于，还包括第一脉冲控制信号的上升沿的延迟时间计算和第二脉冲控制信号的上升沿的延迟时间计算；
    所述上升沿的延迟时间计算包括：
    判断脉冲控制信号对应的光发射机的LED的光衰等级，其中，所述脉冲控制信号为第一脉冲控制信号或第二脉冲控制信号；
    计算脉冲控制信号对应的光发射机发射的光束的上升沿延迟时间
    Figure PCTCN2021088356-appb-100002
    其中，T为光发射机的LED灯珠在最后一个等级经过测试的上升沿延迟时间，A为衰减系数，所述衰减系数为LED灯珠的出厂的光衰曲线的切线斜率的绝对值。
  9. 一种自适应调光的可见光通信系统的解调方法，基于权利要求3-4任一项所述的自适应调光的可见光通信系统，其特征在于，包括：
    第三光电传感器和第四光电传感器采集光信号，并将光信号转换成电信号；
    所述模拟开关对可见光信号和红外信号的有效信号的进行选通，并将选通结果输入至接收机控制器；
    当接收机控制器检测到选通支路的调制阶数变化时，所述接收机控制器 输出对应的新的解调阶数，所述自适应M-PAM解调器使用新的解调阶数对有效信号解调；当所述接收机控制器未检测到选通支路的调制阶数变化时，所述自适应M-PAM解调器对有效信号解调；
    当接收机控制器检测到光通路切换信号时，所述接收机控制器向所述模拟开关和自适应M-PAM解调器发送切换指示，所述模拟开关切换至另一光通路，所述自适应M-PAM解调器选用另一路光通路对应的解调阶数解调。
  10. 如权利要求9所述的自适应调光的可见光通信系统的解调方法，其特征在于，包括:
    当所述接收机控制器检测到自适应M-PAM调制器的变换后的M’调制阶数时，所述接收机控制器根据M’调制阶数获得M’解调阶数；
    所述接收机控制器将M’解调阶数传输至自适应M-PAM解调器以更新解调阶数。
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