WO2018218697A1 - 一种可见光通信收发器与可见光通信系统 - Google Patents

一种可见光通信收发器与可见光通信系统 Download PDF

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Publication number
WO2018218697A1
WO2018218697A1 PCT/CN2017/087415 CN2017087415W WO2018218697A1 WO 2018218697 A1 WO2018218697 A1 WO 2018218697A1 CN 2017087415 W CN2017087415 W CN 2017087415W WO 2018218697 A1 WO2018218697 A1 WO 2018218697A1
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led
light source
visible light
signal
led light
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PCT/CN2017/087415
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English (en)
French (fr)
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李上宾
徐正元
黄博扬
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中国科学技术大学
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Priority to US16/645,147 priority Critical patent/US11374653B2/en
Publication of WO2018218697A1 publication Critical patent/WO2018218697A1/zh

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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
    • H04B10/40—Transceivers
    • 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
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10—Controlling the light source
    • H05B47/165—Controlling the light source following a pre-assigned programmed sequence; Logic control [LC]
    • 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
    • H04B10/40—Transceivers
    • H04B10/43—Transceivers using a single component as both light source and receiver, e.g. using a photoemitter as a photoreceiver
    • 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
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/502—LED transmitters
    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/54—Intensity modulation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light

Definitions

  • Photodetectors convert optical signals into electrical signals and are an important part of visible light communication.
  • the existing photodetectors mainly include photodiodes (PDs), Avalanche Photodiodes (APDs), Light Emitting Diodes (LEDs), and Photomultiplier Tubes (PMTs).
  • PD photodiodes
  • APD Avalanche Photodiodes
  • LEDs Light Emitting Diodes
  • PMTs Photomultiplier Tubes
  • PD, APD and PMT are all widely received in the visible light band. If the optical signal of a specific wavelength is filtered out, a filter of a specific wavelength range needs to be added to receive the optical signal of a specific wavelength.
  • LEDs act as photodetectors, which are capable of independently receiving optical signals, have better wavelength selectivity, and most LEDs have the advantage of narrow spectral response, and do not require a specific wavelength range when receiving optical signals of a specific wavelength. Filter.
  • the visible light communication transceiver with the LED as the receiving end can realize the bidirectional light receiving signal.
  • the present application provides a visible light communication transceiver to achieve simultaneous illumination signals.
  • the present application also provides a visible light communication system based on a visible light communication transceiver, A communication system that simultaneously receives illuminating signals.
  • the present application also provides a multi-color visible light communication system, which realizes low-cost, low-complexity visible light communication system by using multiple pairs of LED-LED links for optical communication according to different narrow spectral bands between multi-color LEDs. .
  • the present application provides a visible light communication transceiver, the visible light communication transceiver includes: an LED light source, a Bias Tee circuit, a driving amplification module, and an adaptive amplification equalization module;
  • the LED light source is connected to the RF and DC mixing ports of the Bias Tee circuit, and the driving amplification module is connected in parallel with the adaptive amplification equalization module, and connected in parallel to the RF port of the Bias Tee circuit;
  • the driving amplification module is configured to perform digital-to-analog conversion and amplification on the digital modulated signal to obtain a first electrical signal, and send the first electrical signal to the Bias Tee circuit through the radio frequency port;
  • the Bias Tee circuit is configured to send the first electrical signal to the LED light source through a radio frequency and a DC port;
  • the LED light source is configured to perform electro-optical conversion on the first electrical signal to generate a first optical signal and transmit the same, and perform photoelectric conversion on the received second optical signal to obtain a second electrical signal; wherein the second light
  • the signal includes an optical signal sent by the opposite end, or an optical signal sent by the LED light source to excite an optical signal generated by the external material, or an optical signal returned after being reflected; and the response of the LED light source to the second optical signal
  • the capability is inversely related to the optical power of the first optical signal;
  • the Bias Tee circuit is configured to acquire the second electrical signal from the LED light source, and transmit the second electrical signal to the adaptive amplification equalization module through the radio frequency port;
  • the adaptive equalization module is configured to adjust a gain of the second electrical signal according to an optical power of the first optical signal to obtain an electrical signal corresponding to the second optical signal.
  • the adaptive amplification equalization module includes: an adaptive gain control circuit and an equalization circuit;
  • the gain coefficient of the adaptive gain control circuit is set to Where V is the forward bias voltage and V 0 is a constant;
  • the gain coefficient of the adaptive gain control circuit is set to e [ ⁇ V] ;
  • the equalization circuit is configured to increase a bandwidth of the second electrical signal.
  • the LED light source comprises: any one of a monochromatic LED light source, a micron-level LED light source, an organic LED light source, a quantum dot LED light source, and an array.
  • the LED light source can receive an external light signal during normal illumination or display.
  • the present application also provides a visible light communication system, the visible light communication system comprising:
  • the two visible light communication transceivers communicate via optical signals.
  • the color of the LED light source of the two visible light communication transceivers includes: red and orange red.
  • the present application also provides a multi-color visible light communication system, the multi-color visible light communication system comprising:
  • each pair of said LED-LED links comprising a transmitter and a receiver; each pair of LEDs in said LED-LED link is configured with a preset color pair and, different LED light sources in LED-LED links are different color pairs;
  • the transmitter is configured to generate and transmit an optical signal
  • the transmitter includes a first processing module, and a first LED light source connected to the first processing module; the first processing module is configured to generate a digital or analog modulated signal, and the digital or Transmitting an analog modulated signal to the first LED light source; the first LED light source for performing electro-optical conversion of the digital or analog modulated signal to obtain an optical signal and transmitting;
  • the receiver is configured to receive the optical signal and obtain required information from the optical signal
  • the receiver includes a second processing module, and a second LED light source coupled to the second processing module; the second LED light source for receiving the optical signal and the optical signal Performing photoelectric conversion to obtain the digital or analog modulated signal; the second processing module for obtaining desired information from the digital or analog modulated signal.
  • the quasi-diagonal channel matrix is formed between the LED-LED links, and the communication mode of the multi-color visible light communication system is full-duplex communication.
  • the multi-color visible light communication system comprises two visible light communication systems, each of the visible light communication systems comprising two pairs of LED-LED links;
  • the LED light source of the transmitter in a pair of LED-LED links of the two pairs of LED-LED links is configured as a red LED light source
  • the LED light source of the receiver is configured as a red LED light source
  • the other pair of LED-LED chains The LED light source of the transmitter in the road is configured as a blue LED light source
  • the LED light source of the receiver is configured as a green LED light source;
  • the communication mode of each of the visible light communication systems is asymmetric full-duplex communication, and specifically includes:
  • the blue LED light source is configured as a downlink communication mode
  • the red LED light source is configured to time-division multiplex uplink and downlink, and when uplinking, the estimated signal-to-noise ratio of the second processing module is fed back to the first processing module and the antenna is selected for transmission. way of communication.
  • the first processing module includes:
  • a low-order modulation sub-module configured to modulate a baseband signal according to a low-order modulation order when the average optical power of the LED-LED link is a low average optical power, to obtain the digital or analog modulated signal
  • a high-order modulation sub-module configured to modulate the baseband signal according to a high-order modulation order when the average optical power of the LED-LED link is a high average optical power, to obtain the digital or analog modulated signal.
  • the present application includes the following advantages:
  • the LED light source performs simultaneous optical signal transmission and reception, which means that the LED light source can also receive external light signals during normal illumination or display; the two physical processes of electro-optical conversion and photoelectric conversion occur on the same material microstructure for the use of visible light communication technology. Location accuracy can be improved when pushing applications based on location.
  • the visible light communication transceiver proposed in the embodiment of the present application drives the amplification module and the adaptive amplification equalization module in parallel at the signal input end.
  • Driving amplification module for digital-to-analog conversion and amplification of digital modulated signals A first electrical signal is obtained, and the first electrical signal is sent to the LED light source through the Bias Tee circuit, and the LED light source controls the optical power of the first optical signal to be generated according to the first electrical signal.
  • the LED light source photoelectrically converts the received second optical signal to obtain a second electrical signal.
  • the ability of the LED light source to photoelectrically convert the received second optical signal to obtain the second electrical signal is negatively correlated with the optical power of the first optical signal. Therefore, the control of the optical power of the first optical signal affects the LED light source to the second
  • the adaptive amplification equalization module in the visible light communication transceiver of the embodiment of the present application adjusts the gain of the second electrical signal according to the optical power of the first optical signal, so that the visible light communication transceiver obtains the second optical signal. Corresponding electrical signals, in turn, enable the visible light communication transceiver to simultaneously receive the illuminating signal.
  • FIG. 1 is a schematic diagram of a visible light communication transceiver in the present application.
  • FIG. 2 is a block diagram of a visible light communication system in the present application.
  • FIG. 4(a) is a schematic diagram showing the relationship between the relative optical signal response intensity and the forward bias voltage of the red LED light source in the present application;
  • 4(b) is a schematic diagram showing the relationship between the relative optical signal response intensity and the forward bias current of the red LED light source in the present application;
  • 5 is a schematic diagram showing the relationship between the two-way reachable rate and the forward working voltage of the red light LED-red LED in the present application in different signal-to-noise ratios;
  • Figure 6 is a block diagram of a multi-color visible light communication system in the present application.
  • FIG. 7 is a block diagram of a full duplex visible light communication system in the present application.
  • Figure 8 is an AC impedance spectrum of the red LED and the green LED as the optical receiver in the present application.
  • FIG. 9 is a schematic diagram showing a relationship between a bit error rate and a communication rate in the present application.
  • FIG. 10 is a schematic diagram showing the relationship between the 3dB bandwidth of the red LED-red LED visible light communication link and the additional series resistance of the receiving end in the present application;
  • FIG. 11 is a block diagram of still another multi-color visible light communication system in the present application.
  • FIG. 12 is a block diagram of a 4 ⁇ 4 multi-color LED MIMO communication system constructed by four pairs of LEDs in the present application;
  • Figure 13 (a) is a schematic diagram of the reachable bit rate of the singular value decomposition plus voltage distribution when the interference ratio is 0.1 in the present application;
  • Figure 13 (b) is a schematic diagram of the reachable bit rate of the singular value decomposition plus voltage distribution when the interference ratio is 0.3 in the present application;
  • Figure 13 (c) is a schematic diagram of the reachable bit rate of the singular value decomposition plus voltage distribution when the interference ratio is 0.7 in the present application;
  • Figure 13 (d) is a diagram showing the reachable bit rate of the singular value decomposition plus voltage distribution when the interference ratio is 0.9 in the present application.
  • the visible light communication transceiver may include: an LED light source 101, a Bias Tee circuit 102, a driving amplification module 103, and an adaptive amplification equalization module 104.
  • the Bias Tee circuit 102 has three ports, which are a DC bias port, a radio frequency port, and a radio frequency and a DC port.
  • the LED light source 101 is connected to the radio frequency and DC ports of the Bias Tee circuit 102, and drives the amplification module 103 and
  • the adaptive amplification equalization modules 104 are connected in parallel and connected in parallel to the RF port of the Bias Tee circuit 102.
  • the working principle of simultaneously receiving the illuminating signal is as follows:
  • the quantum well structure in the LED light source has the possibility of simultaneous electro-optical conversion and photoelectric conversion. Therefore, the quantum well structure based on the LED light source can simultaneously perform the functions of electro-optical conversion and photoelectric conversion, and receive the optical signal while the LED light source transmits.
  • the optical signal transmitted by the LED light source is referred to as a first optical signal
  • the optical signal received by the LED light source is referred to as a second optical signal.
  • the first light transmitted by the LED light source is referred to.
  • this embodiment proposes that the visible light communication transceiver shown in FIG. 1 drives the amplification module 103 and the adaptive amplification equalization module 104 in parallel at the signal input end.
  • the driving amplification module 103 is configured to perform digital-to-analog conversion and amplification on the digital modulation signal.
  • the digital-to-analog conversion and the amplified modulation signal are referred to as a first electrical signal, and the first electrical signal is transmitted to the first electrical signal through the Bias Tee circuit 102.
  • the LED light source 101 controls the optical power of the first optical signal according to the first electrical signal.
  • the LED light source 101 photoelectrically converts the received second optical signal to obtain a second electrical signal. Since the responsiveness of the LED light source 101 to the second optical signal is negatively correlated with the optical power of the transmitted first optical signal, in this embodiment,
  • the LED light source 101 in the visible light communication transceiver shown in FIG. 1 is output to the adaptive amplification equalization module 104 through the RF port of the Bias Tee circuit 102 after obtaining the second electrical signal, and the adaptive amplification equalization module 104 is configured according to the first optical signal.
  • the optical power adjusts the gain of the second electrical signal to obtain an electrical signal corresponding to the second optical signal, so that the LED light source can accurately receive the second optical signal.
  • the drive amplifier module can be implemented by a current feedback type operational amplifier circuit with an external negative feedback resistor.
  • the driving amplification module can also be implemented by using other circuit structures. This embodiment does not limit the specific implementation manner of driving the amplification module.
  • the equalization circuit in the adaptive amplification equalization module 104 may include a low pass filter circuit for increasing the bandwidth of the second electrical signal.
  • the adaptive amplification equalization module 104 can be implemented in various manners, for example, using a triode as a power amplifier component, or using a combination of a buf tube and an operational amplifier for signal amplification and frequency band pre-equalization.
  • the specific implementation manner of the adaptive amplification and equalization module 104 provided by this embodiment is only an implementation that can be referred to. In an actual application, other implementation manners may also be adopted. The specific implementation manner is not limited.
  • the transmitting the first optical signal and the receiving the second optical signal may occupy different frequency bands, when the same frequency band is used, because the first optical signal is transmitted. It is known that the received second optical signal can be determined using a corresponding interference cancellation algorithm in conjunction with an applicable estimation algorithm.
  • a variety of clutter signals appear in the circuit using the op amp, which is caused by the oscillation of the amplifier. It is necessary to adjust the feedback of the circuit to eliminate the influence of parasitic capacitance.
  • the LED light source 101 in the visible light communication transceiver shown in FIG. 1 may be configured as any one of a monochrome LED light source, a micron LED light source, an organic LED light source, a quantum dot LED light source, or an array of the above light sources.
  • a monochrome LED light source a micron LED light source
  • an organic LED light source a quantum dot LED light source
  • an array of the above light sources a monochrome LED light source, a micron LED light source, an organic LED light source, a quantum dot LED light source, or an array of the above light sources.
  • the monochromatic LED light source may include a white LED light source, a red LED light source, a blue LED light source, a green LED light source, and an orange LED light source.
  • the white LED light source is composed of a blue chip and a yellow phosphor, and the blue chip can load the modulation signal; the red chip in the red LED source can load the modulation signal; the blue chip in the blue LED source can load the modulation signal;
  • the green LED light source and the orange LED light source have independent optical signal transmitting and receiving circuits.
  • the visible light communication transceiver includes a modulation module and a demodulation module, wherein the modulation module is coupled to the driving amplification module 103 for generating a digital modulation signal, and transmitting the digital modulation signal to the driving amplification module; the demodulation module Connected to the adaptive amplification module 104 for demodulating the first electrical signal.
  • the visible light communication transceiver can simultaneously receive the illuminating signal. Therefore, according to the circuit design of the visible light communication transceiver of the present embodiment, a large class of light emitting devices such as an LED light source can be used for fabrication simultaneously.
  • the visible light communication transceiver that receives the illuminating signal capability can reduce the manufacturing cost of the communication system composed of the visible light communication transceiver.
  • the present embodiment provides a visible light communication system, and a schematic structural view of the visible light communication system is shown in FIG. 2 .
  • the visible light communication system shown in FIG. 2 is composed of two visible light communication transceivers, and two visible light communication transceivers are respectively distributed at the left and right ends, and the LED light source 201 at the left end may be a red LED light source or an orange red LED light source.
  • the light source transmits both the optical signal and the optical signal;
  • the first light receiving and receiving module 202 is connected to the LED light source 201, and the transmitting and receiving module has the same circuit structure as the visible light communication transceiver in the first embodiment, and the transmitting and receiving module 202 receives the first a modulation signal generated by a terminal 203, and transmits the received signal to the second terminal 204;
  • the LED light source 205 at the right end may be a red LED light source or an orange red LED light source, and the LED light source transmits both the optical signal and the optical signal; and the LED light source 205 is connected to the second transmitting and receiving module 206, and the transmitting and receiving module 206
  • the circuit configuration of the visible light communication transceiver in the embodiment is the same, the transmitting and receiving module 206 receives the modulated signal generated by the third terminal 207, and transmits the received signal to the fourth terminal 208.
  • the first terminal 203 and the third terminal 207 are both implemented by data generation, serial-to-parallel conversion and modulation. In practical applications, the terminal can be completed by the terminal with the FPGA chip; the second terminal 204 and the fourth terminal 208 The functions of analog-to-digital conversion, synchronization, decision demodulation, and parallel-to-serial conversion are realized, and can be completed by a terminal with an FPGA chip in practical applications.
  • the LED-LED link composed of the LED light source 201 and the LED light source 205 performs duplex communication at the same time.
  • a red LED-red LED link can be formed by the LED light source 201 and the LED light source 205.
  • the frequency response curve of the red LED-red LED link is as shown in FIG. 3, wherein the abscissa is the frequency and the ordinate is the frequency response; while the red chip in the red LED source transmits the optical signal simultaneously
  • the response of the received optical signal is as shown in FIG. 4, wherein FIG.
  • FIG. 4(a) is a relationship between the relative optical signal response intensity of the red LED light source and the forward bias voltage, wherein the abscissa is forward biased.
  • the voltage and ordinate are the relative light signal response intensity.
  • Figure 4(b) shows the relationship between the relative optical signal response intensity and the forward bias current of the red LED source.
  • the abscissa is the forward bias current.
  • the coordinate is the reciprocal of the response strength of the optical signal.
  • the high and low level of the LED light source has a great influence on the reachable rate of the visible light communication system, and the specific influence is the OOK of the red LED-red LED link.
  • the duplex system is introduced as an example.
  • the high level is V H and the low level is V L , then the response of the LED light source at the high level is as shown in the following formula (1), and the response at the low level is as follows (2) shown.
  • the gain coefficient is A
  • the noise variance is ⁇ 2
  • the relationship between the red-light LED-red LED full-duplex link in different signal-to-noise ratio bidirectional reachable speed and forward working voltage is shown in Fig. 5, where the abscissa is positive working.
  • the voltage and ordinate are bidirectional reachable rates. It can be seen from Figure 5 that at low SNR, the performance is not ideal due to the suppression of the forward voltage response, but in the case of high SNR. The rate achieves better results and the selection of a suitable high level maximizes the reach rate.
  • the LED light source Since the LED light source has a different response at the high level and the low level as the receiving end, it is desirable to increase the probability of the low level by changing the ratio of the high level and the low level. Increase the reachability of the entire OOK communication system. This goal can be achieved by coding to make the zero-proportion imbalance unbalanced.
  • the capacity of the binary symmetric channel will be correspondingly reduced, by comparing the reachable rates under different signal-to-noise ratios.
  • the signal-to-noise ratio is small, changing the proportion of symbol 1 can increase the maximum reach rate to a certain extent.
  • the signal-to-noise ratio is large or the proportion of symbol 1 is small, the performance deteriorates. It can be seen that selecting the appropriate high level maximizes the reachable rate, which decreases as the signal to noise ratio increases.
  • the visible light communication system shown in FIG. 2 is only composed of two visible light communication transceivers that simultaneously receive the light-emitting signals. In practical applications, other circuits can be built on the visible light communication system shown in FIG. 2, As long as the illuminating signal can be simultaneously received, the present embodiment does not limit the specific structure of the visible light communication system that can simultaneously receive the illuminating signal.
  • the full-duplex LED-LED link simultaneously transmits the optical signal and the received optical signal, and determines the high and low levels of the LED light source when the visible light communication system reaches the maximum reachable rate. In particular, a high level that can maximize the reachable rate is determined.
  • the visible light communication system of the LED-LED link reduces the filter and can reduce the optical communication system. Complexity and cost.
  • the multi-color visible light communication system may include: a first processing module 601, a first LED light source 602, a first processing module 603, and a first An LED light source 604, a second processing module 605, a second LED light source 606, a second processing module 607, and a second LED light source 608.
  • the first processing module 601 is configured to generate a digital or analog modulated signal and transmit the digital or analog modulated signal to the first LED light source 602.
  • the first LED light source 602 is configured to photoelectrically convert the digital or analog modulated signal to obtain an optical signal and transmit the optical signal.
  • a second LED light source 606 configured to receive an optical signal sent by the first LED light source 602, and photoelectrically convert the received optical signal to obtain an electrical signal, and send the electrical signal to the second Processing module 605.
  • the second processing module 605 is configured to obtain required information from the electrical signal.
  • the first processing module 603 is configured to generate a digital or analog modulated signal and transmit the digital or analog modulated signal to the first LED light source 604.
  • the first LED light source 604 functions the same as the first LED light source 602.
  • the second LED light source 608 is configured to receive the optical signal sent by the first LED light source 604, and photoelectrically convert the received optical signal to obtain an electrical signal, and send the electrical signal to the second processing module 607.
  • the second processing module 607 is configured to obtain required information from the electrical signal.
  • all the first processing modules can be transmitted to the Bias Tee circuit by simple on-off keying modulation (OOK) or orthogonal frequency division multiplexing (OFDM), and all the second processing modules can pass through one signal processing board and one client.
  • OOK on-off keying modulation
  • OFDM orthogonal frequency division multiplexing
  • the implementation of the first processing module and the second processing module provided by this embodiment is only an implementation manner. In an actual application, the first processing module and the second processing module may be other implementation manners. As long as the functions of the first processing module and the second processing module can be satisfied.
  • any LED light source of a certain color has a better response to the optical signal emitted by the LED light source of a specific color.
  • a communication system composed of two 3 ⁇ N RGB LED light-emitting diode arrays is taken as an example to determine which color LED light source pairs between red, green and blue colors can achieve better spectral response. effect.
  • Each of the 3 x N RGB LED arrays has N LEDs in each color.
  • the same color LED is connected in series on the module, and the electrical signals between the LEDs of different colors are independent.
  • multicolor LED arrays also exhibit a unique phenomenon that is different from Si detector arrays.
  • the RGB LED array signal distortion caused by partial blocking of the optical link depends on the number and color of the LEDs.
  • a 3 x 3 RGB LED module is used as a photodetector, it can be thought of as a sort of photodetector array.
  • LED arrays exhibit some unique photoresponse phenomena due to their wide bandgap semiconductors.
  • the above 3 ⁇ 3 RGB LED module has the following three characteristics when it receives the offset sine wave corresponding wavelength optical signal as a photodetector:
  • this RGB LED array can be used for multi-color interference management in visible light communication systems or as a multi-mode detector.
  • the 9 LEDs form a 3 ⁇ 3 RGB LED square array with a 30mm lamp spacing, of which three LEDs of the same color are connected in series. Each LED has a lens with a full beam angle of 12°. The lens enables significant channel gain from the LED to LED link.
  • the green and blue LEDs have a transient voltage suppressor (TVS) connected in parallel with the InGaN chip, and are flip-chip packaged, and the red LED is packaged on the ceramic plate of the AlInGaP chip.
  • TVS transient voltage suppressor
  • the two LED modules produce nine possible color pairs because there are red, green or blue LEDs on each side.
  • the output signal from the receiver LED is recorded by the oscilloscope.
  • Nine groups of experiments were carried out: R-R, R-G, R-B, G-R, G-G, G-B, B-R, B-G, B-B.
  • PL photoluminescence
  • EL current-injection electroluminescence
  • LEDs can detect light that is less than 100 nm below its emission wavelength.
  • the structure of the LED is similar to that of a photodiode (PD) which is formed by a PN structure.
  • PD photodiode
  • Two effects constrain the response wavelength.
  • the band gap determines the emission wavelength of the LED and the upper cutoff wavelength as the receiver. Any photon larger than this wavelength does not have enough energy to excite electron-hole pairs.
  • short-wavelength light is incident on the LED, it is mainly affected by the absorption of photons by the material. When the wavelength is short, the photon is more easily absorbed by the surface of the PN junction, and the contribution to the photocurrent is small.
  • the experiment shows that the red LED can respond to red and green light without ringing. Should be blue light. It is speculated that the red LED is insensitive to blue light from the package structure, in which the cathode of the red LED is above, and most of the injected blue light is absorbed by n-GaP and cannot effectively excite the electron-hole pairs of the light-emitting layer. Compared to the response of the red LED to the red LED, the red LED responds much less to the green light emitted by the green LED, with an order of magnitude difference. When a green LED is used as the receiver, it does not respond to red light. In addition, unlike red LEDs, green LEDs do not respond to themselves, but have a strong response to blue light from blue LEDs.
  • blue LEDs can be considered good visible narrow-spectrum blue-light receivers because blue LEDs only respond to blue light. However, its response to blue light is not as good as that of green LEDs.
  • the filter is selected as follows (central wavelength / full width at half maximum, in nm): 525/50, 582/75, 630/38, red LED; 435/40, 475/50, 525/50 green LED; 435/40 , 475/50 blue LED.
  • the white LED is driven by a constant voltage, and the response of the receiving LED is obtained by the oscilloscope measuring the voltage.
  • the response of each LED to the filter is divided by the optical power through the filter. Further normalization (measurement of the LED to the overall white spectral response) is obtained by comparison with the response when there is no filter, and the relative response rate is obtained.
  • the relative response rate without the filter is defined as 1.
  • the relative response of the LED is greater than 1, it means that the contribution in the corresponding wavelength range is greater than the average contribution of the entire spectrum.
  • the response spectrum segments of the RGB LEDs as shown in Table 1, Table 2, and Table 3 can be obtained, wherein Table 1 is the response spectrum segment of the red LED light source, Table 2 is the response spectrum segment of the green LED light source, and Table 3 is blue. The response spectrum of the LED source.
  • the red LED has a strong response under the 582/75 nm and 630/38 nm filters, while the blue and green LED pairs 435/40nm and 475/50nm have strong response.
  • the photoelectric response wavelength of a blue LED is usually shorter than that of a green LED. It may not be optimal to use the same color LED as the transmitter and receiver because its photo-emission and photo-response spectra typically do not match. However, the red LED is an exception, and its emission and response spectrum mismatch is small.
  • a suitable color pair can be found for the transmitter receiver pair, such as a blue light emitting diode, detected with a green light emitting diode.
  • the eight color LED light sources are used as the receiving end and the transmitting end, respectively, and the response voltage between the eight receiving ends and the eight kinds of transmitting ends shown in Table 5 below is obtained.
  • LED Light-emitting diode
  • Color Response spectrum segment Royal Blue 435/40 Blue 435/40 Blue-green (Cyan) 435/40, 475/50 Green 435/40, 475/50 Amber 582/75 Orange-red (Red-orange) 582/72,630/38 Red 630/38, 582/75 Deep Red 630/38,582/75,678/67
  • the first LED light source 602 and the second LED light source 606, the first LED light source 604, and the second LED light source 608 are selected from any of the eight pairs of colors to satisfy Table 5.
  • the matrix element is greater than 0.3.
  • a multi-color visible light communication system is just an example of a visible light communication system with two LED-LED links. In practical applications, it is also possible to build multi-color visible light of three, four, etc. LED-LED links.
  • the communication system is as long as the color of the LED light source in the plurality of LED-LED links is a different color pair among the eight pairs of colors and satisfies the matrix element in Table 5 being greater than 0.3.
  • the first LED light source 602 is configured as a red LED light source
  • the second LED light source 606 is configured as a red LED light source
  • the first LED light source 604 is configured as a blue LED light source.
  • a simple on-off keying modulation (OOK) can provide a data rate of 40-200 kbps, meeting the narrowband Internet of Things (NB-IoT) needs.
  • NB-IoT narrowband Internet of Things
  • Figure 7 shows a block diagram of a full-duplex visible light communication system with a forward link from a red LED to a red LED and a reverse link from a blue LED to a green LED.
  • the signal received by the receiver LED is recorded by the oscilloscope and the bit error rate is calculated offline.
  • Fig. 9 is a diagram showing the relationship between the bit error rate and the frequency, wherein the abscissa is the frequency and the ordinate is the bit error rate, and the figure shows the bit error rate performance from the data rate of 10 kbps to 50 kbps.
  • the minimum error displayed by the RR is determined by the number of transmitted bits (16384), and the BG has a higher error rate. According to this feature, in order to improve the link bandwidth and transmission performance, the LED can be connected to an amplifier circuit with adjustable impedance.
  • a full-duplex multi-color visible light communication system with multiple LED-LED links can be constructed, and the spectral selectivity of the LED light source is utilized, and the multi-color visible light communication system does not need a filter, so that multi-color visible light communication can be constructed.
  • the cost of the system is reduced and the structure is simple.
  • the color pairs of the LED-LED links of the multi-color pairs are different, so that the communication rate of the communication system can be increased.
  • FIG. 11 there is shown a block diagram of another multi-color visible light communication system comprising two RGB LED array modules comprising a half duplex 2 x 2 MIMO LED-LED visible light communication system.
  • the system can provide a data rate of 40-200 kbps using a simple on-off keying modulation (OOK) without any equalization and amplification circuitry, meeting the narrowband Internet of Things (NB-IoT). Therefore, the multi-color visible light communication system can also be applied to a low-complexity narrow-band Internet of Things application scenario.
  • OOK on-off keying modulation
  • the MIMO visible light communication link composed of the R-R LED link and the B-G LED link can reach a rate of 80 kbps without any amplification equalization circuit.
  • the performance can be improved not only by an impedance matching amplifier circuit, but also by adjusting the series impedance of the LED signal current to the signal voltage at the receiving end, in the signal-to-noise ratio and Balance between bandwidth.
  • the multi-color visible light communication system shown in FIG. 11 can also be extended to more color LEDs, organic LEDs, and quantum dot LEDs.
  • This multi-color LED-LED MIMO VLC system can effectively utilize the degree of freedom in the spectrum to improve communication performance. And because the filter is not required, the cost can be greatly reduced and the practicality of the system can be improved.
  • FIG. 12 a block diagram of a 4x4 multi-color LED MIMO communication system constructed from four pairs of LEDs is shown.
  • the single-point-to-single-point OOK modulation offline test using the LED as the receiving end can reach a rate of 30 Mbps, and the bit error rate is less than 10 -3 , according to the different LEDs shown in Table 5.
  • the spectrally selective result of the response between the LED light receivers can be considered as a narrow spectrum photodetector that does not require a filter.
  • the asymmetric multi-color duplex visible light communication system shown in Fig. 12 is designed.
  • the channel matrix and the spectral response curve measured according to the experimental results in Table 5 are obtained. Selecting four pairs of transmit and receive LED pairs, and the channel matrix is a four-by-four MIMO visible light communication system with a block diagonal matrix, the four-by-four MIMO communication system can be simplified to two independent two-by-two In MIMO, the LEDs in each MIMO system have the same rate, that is, there is no problem of unequal rate reception synchronization.
  • the LED transceiver part of the blue-green part uses different LEDs, and the transceiver part of the red part is the same LED, which has symmetry. Therefore, an uplink and downlink asymmetric duplex communication mode is designed. Part of it is only used for downlink, and the red light part is time-multiplexed for uplink and downlink, and the uplink is used for feedback.
  • this embodiment adopts a low complexity MIMO transmission and reception strategy.
  • the constraints of the LEDs at the transmitting end are often the peak constraints caused by the limitation of the linear region of the LED, rather than the total power or single antenna constraints in a conventional wireless communication MIMO system.
  • the influence of peak confinement on SVD decomposition is studied.
  • the effects of SVD decomposition and MMSE-SIC on channel capacity under OOK and 4PAM modulation when transmitting two receivers are compared.
  • the influence of LED voltage distribution on the capacity of the transmitter is analyzed.
  • a low-complexity combined optimal receiver strategy based on the estimated signal-to-noise ratio of the receiver is fed back to the transmitter and the antenna transmission mode is selected.
  • Figure 13 is a diagram showing the reachable bit rate of a singular value decomposition plus voltage distribution of a 2 x 2 LED-LED MIMO visible light communication system under different symmetric color interferences, wherein Figure 13(a) shows an interference ratio of 0.1. Schematic diagram of bidirectional reachable bit rate for singular value decomposition plus voltage distribution, where the abscissa is the signal to noise ratio and the ordinate is the bidirectional reachable bit rate; Figure 13(b) shows the singular value decomposition plus the interference ratio of 0.3. Schematic diagram of the bidirectional reachable bit rate of voltage distribution, wherein the abscissa is the signal to noise ratio and the ordinate is the bidirectional reachable bit rate; FIG.
  • FIG. 13(c) shows the bidirectional value decomposition plus the voltage distribution bidirectional when the interference ratio is 0.7.
  • Figure 13(d) shows the bidirectional reachable bit rate for the singular value decomposition plus voltage distribution with an interference ratio of 0.9.
  • a schematic diagram in which the abscissa is the signal to noise ratio and the ordinate is the bidirectional reachable bit rate.
  • the multi-input multi-color visible light communication system shown in FIG. 12 is constructed by using four pairs of LEDs, but is an example of a multi-input multi-color visible light communication system. In practical applications, It is possible to build a multi-color and multi-color visible light communication system other than 4 pairs of LEDs. This embodiment does not limit the specific structure of the multi-input multi-color visible light communication system.
  • an asymmetric multi-color visible light communication system adopts an asymmetric duplex communication method to eliminate synchronization problems caused by different LED bandwidths and inter-color interference.
  • the multi-color visible light communication system of the present embodiment adopts a low-complexity combined optimal transceiver strategy that feeds back to the transmitting end according to the estimated signal-to-noise ratio of the receiver and selects an antenna transmission mode, so that the multi-color embodiment of the present embodiment Color visible light communication systems are less expensive.
  • the bias driving current affects the luminous efficiency of the light-emitting diode and the electro-optic response spectrum.
  • the larger the drive current the lower the light efficiency and the higher the bandwidth.
  • the logarithm of the 3dB modulation bandwidth and the luminous efficiency are approximately on a straight line with a negative slope.
  • the bias voltage affects the strength of the AC signal actually applied to the LED.
  • the intensity of the AC signal actually applied to the LED and the impedance at the corresponding voltage of the LED are linear with the voltage division of the output impedance of the bias. led
  • the receiving end its photoelectric response spectrum is related to the background light power.
  • the link from the light emitting diode to the photodiode can enhance the signal-to-noise ratio by increasing the signal-to-noise ratio by increasing the optical power of the receiving end to increase the communication rate.
  • the LED transmits the optical signal while receiving the optical signal with the LED, unlike the photodiode receiving end, the signal waveform is distorted as the distance between the transmitting and receiving ends is narrowed. This phenomenon is not caused by the saturation of the LED light receiver, but the bandwidth of the LED receiving end decreases as the optical power at the receiving end increases.
  • the LED dispersion carrier model is modified and compared with the experimental results, and a good matching result is obtained.
  • the effect of LED as a detector's nonlinearity on communication is reflected in bandwidth and signal-to-noise ratio.
  • This embodiment simulates the influence of signal-to-noise ratio and inter-symbol interference (bandwidth) at different optical powers on the reachability of different modulation modes. Different modulation methods have different optimal optical power operating points.
  • the communication rate can be increased under the condition that the optical power limitation or the modulation mode is determined.
  • this embodiment proposes to adaptively adjust the modulation order according to the change in the average optical power caused by the change in the distance and azimuth of the LED-LED link.
  • the above method of adaptively adjusting the modulation order according to the change in the average optical power caused by the change in the distance and azimuth of the LED-LED link can be applied to the visible light communication systems provided in Embodiments 2 to 5.
  • the modulation order can be adaptively adjusted according to the optical power, so that the visible light communication system can reach a higher communication rate.

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Abstract

本申请公开了一种可见光通信收发器，该可见光通信收发器包括：LED光源、Bias Tee电路、驱动放大模块和自适应放大均衡模块。其中，驱动放大模块，用于对数字调制信号进行数模转换和放大得到第一电信号，通过Bias Tee电路传输至LED光源；LED光源，用于将所述第一电信号进行电光转换生成第一光信号并发送，同时对所接收的第二光信号进行光电转换得到第二电信号；Bias Tee电路，用于从所述LED光源获取所述第二电信号，并将所述第二电信号通过所述射频端口传输至所述自适应放大均衡模块；自适应均衡模块，用于根据所述第一光信号的光功率，调整所述第二电信号的增益，得到所述第二光信号对应的电信号。采用本申请实施例的可见光通信收发器，可以实现同时收发光信号。

Description

一种可见光通信收发器与可见光通信系统 技术领域
本申请要求于2017年5月31日提交中国专利局、申请号为201710399665.8、发明名称为“一种可见光通信收发器与可见光通信系统”的国内申请的优先权，其全部内容通过引用结合在本申请中。
背景技术
随着互联网技术的发展，对无线通信速率和容量的需求急剧上升，传统无线通信所使用的频谱资源越来越难以满足需要，由于无线光通信所使用的光谱波段是免频谱许可的，因此，基于可见光波段的无线光通信系统越来越受关注。
光电探测器可将光信号转换为电信号，是可见光通信中的重要组成部分。现有的光电探测器主要有光电二极管(Photodiode，PD)、雪崩光电二极管(Avalanche Photodiode，APD)、发光二极管(Light Emitting Diode，LED)和光电倍增管(Photomultiplier Tube，PMT)。其中，PD、APD与PMT三种光探测器对于可见光波段都是宽光谱接收的，如果滤出特定波长的光信号，需要添加一个特定波长范围的滤波片，来实现对特定波长光信号的接收功能。但是，LED作为光探测器，以其能够独立的接收光信号、具有较好的波长选择性，以及，大多数LED是窄光谱响应的优点，在接收特定波长的光信号时不需要特定波长范围的滤波片。
由于LED能够独立的接收光信号，因此，以LED作为接收端的可见光通信收发器能够实现双向收发光信号。但是，发明人在研究过程中发现，现有以LED作为接收端的可见光通信收发器，以时分复用的方式进行双向收发光信号。因此，一种能够实现同时收发光信号的可见光通信收发器是很必要的。
发明内容
基于此，本申请提供了一种可见光通信收发器，以实现同时收发光信号。
本申请还提供了一种基于可见光通信收发器的可见光通信系统，以实 现同时收发光信号的通信系统。
本申请还提供了一种多色可见光通信系统，根据多色LED之间响应不同的窄光谱波段，使得采用多对LED-LED链路进行光通信，实现低成本、低复杂度的可见光通信系统。
为此，本申请提供的技术方案如下：
本申请提供了一种可见光通信收发器，所述可见光通信收发器包括：LED光源、Bias Tee电路、驱动放大模块和自适应放大均衡模块；
其中，所述LED光源与所述Bias Tee电路的射频和直流混合端口相连接，所述驱动放大模块与所述自适应放大均衡模块并联，并联后与所述Bias Tee电路的射频端口相连接；
所述驱动放大模块，用于对数字调制信号进行数模转换和放大得到第一电信号，并通过所述射频端口，将所述第一电信号发送至所述Bias Tee电路；
所述Bias Tee电路，用于通过射频和直流端口将所述第一电信号发送至所述LED光源；
所述LED光源，用于将所述第一电信号进行电光转换生成第一光信号并发送，同时对所接收的第二光信号进行光电转换得到第二电信号；其中，所述第二光信号包括对端发送的光信号、或者、所述LED光源发送的光信号激励外部材料产生的光信号，或者，反射后传回的光信号；所述LED光源对所述第二光信号的响应能力与所述第一光信号的光功率负相关；
所述Bias Tee电路，用于从所述LED光源获取所述第二电信号，并将所述第二电信号通过所述射频端口传输至所述自适应放大均衡模块；
所述自适应均衡模块，用于根据所述第一光信号的光功率，调整所述第二电信号的增益，得到所述第二光信号对应的电信号。
其中，所述自适应放大均衡模块包括：自适应增益控制电路与均衡电路；
其中，若所述LED光源的正向偏置电压大于所述LED光源的转换电压时，所述自适应增益控制电路的增益系数设置为
Figure PCTCN2017087415-appb-000001
其中，V为正向偏置电压，V0为常数；
若所述LED光源的正向偏置电压小于所述LED光源的转换电压时，所述自适应增益控制电路的增益系数设置为e[βV]；
所述均衡电路，用于增大所述第二电信号的带宽。
其中，所述LED光源包括：单色LED光源、微米级LED光源、有机LED光源、量子点LED光源以及阵列中的任意一种。
其中，所述电光转换和所述光电转换这两个物理过程发生在同一材料微观结构上。
其中，所述LED光源在正常照明或显示时可以接收外部光信号。
本申请还提供了一种可见光通信系统，所述可见光通信系统包括：
两个可见光通信收发器，所述可见光通信收发器为上述任一所述的可见光通信收发器；
所述两个可见光通信收发器之间通过光信号进行通信。
其中，所述两个可见光通信收发器的LED光源颜色包括：红色与橙红色。
本申请还提供了一种多色可见光通信系统，所述多色可见光通信系统包括：
至少两对LED-LED链路，每对所述LED-LED链路包括一个发送器和一个接收器；每对所述LED-LED链路中的LED被配置了预设颜色对，并且，不同LED-LED链路中的LED光源为不同的颜色对；
其中，所述发送器，用于生成并发送光信号；
所述发送器，包括一个第一处理模块，以及，与所述第一处理模块相连的第一LED光源；所述第一处理模块，用于生成数字或模拟调制信号，并将所述数字或模拟调制信号传输至所述第一LED光源；所述第一LED光源，用于将所述数字或模拟调制信号进行电光转换得到光信号并发送；
所述接收器，用于接收所述光信号并从所述光信号中获取所需信息；
所述接收器，包括一个第二处理模块，以及，与所述第二处理模块相连接的第二LED光源；所述第二LED光源，用于接收所述光信号，并将所述光信号进行光电转换得到所述数字或模拟调制信号；所述第二处理模块，用于从所述数字或模拟调制信号中获取所需信息。
其中，所述LED-LED链路之间形成准对角信道矩阵，且，所述多色可见光通信系统的通信方式为全双工通信。
其中，所述多色可见光通信系统包括两个可见光通信系统，每个所述可见光通信系统包括两对LED-LED链路；
所述两对LED-LED链路中一对LED-LED链路中的发送器的LED光源被配置为红色LED光源，接收器的LED光源被配置为红色LED光源；另一对LED-LED链路中的发送器的LED光源被配置为蓝色LED光源，接收器的LED光源被配置为绿色LED光源；
每个所述可见光通信系统的通信方式为非对称全双工通信，具体包括：
蓝色LED光源被配置为下行通信方式，红光LED光源被配置为时分复用上下行，且进行上行时，将第二处理模块估计的信噪比反馈给第一处理模块并选择天线发送的通信方式。
其中，所述第一处理模块，包括：
低阶调制子模块，用于当所述LED-LED链路的平均光功率为低平均光功率时，按照低阶调制阶数对基带信号进行调制，得到所述数字或模拟调制信号；
高阶调制子模块，用于当所述LED-LED链路的平均光功率为高平均光功率时，按照高阶调制阶数对基带信号进行调制，得到所述数字或模拟调制信号。
与现有技术相比，本申请包括以下优点：
LED光源进行同时的光信号收发,意味着LED光源在正常照明或显示时也可以接收外部光信号；电光转换和光电转换这两个物理过程发生在同一材料微观结构上,对于利用可见光通信技术进行基于位置的信息推送应用时,可以提高位置精度。
在实际应用中，LED光源发送的第一光信号与接收的第二光信号的在光功率上存在小比例叠加，使得LED可能不会准确接收第二光信号，为了降低第一光信号与第二光信号在光功率上部分叠加带来的影响，本申请实施例提出的可见光通信收发器，在信号输入端并联驱动放大模块和自适应放大均衡模块。驱动放大模块用于对数字调制信号进行数模转换与放大后 得到第一电信号，通过Bias Tee电路将第一电信号发送至LED光源，LED光源根据第一电信号控制生成第一光信号的光功率。LED光源对接收的第二光信号进行光电转换得到第二电信号。由于LED光源对接收的第二光信号进行光电转换得到第二电信号的能力，与发送第一光信号的光功率负相关，因此，对第一光信号光功率的控制影响LED光源对第二光信号的响应能力，本申请实施例的可见光通信收发器中的自适应放大均衡模块，根据第一光信号的光功率调整第二电信号的增益，使可见光通信收发器得到与第二光信号对应的电信号，进而实现可见光通信收发器同时收发光信号。
当然，实施本申请的任意产品并不一定需要同时达到以上所述的所有优点。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1是本申请中一种可见光通信收发器示意图；
图2是本申请中一种可见光通信系统的框图；
图3是本申请中红光LED-红光LED链路的频率响应曲线图；
图4(a)是本申请中红光LED光源的相对光信号响应强度与正向偏置电压之间的关系示意图；
图4(b)是本申请中红光LED光源的相对光信号响应强度与正向偏置电流之间的关系示意图；
图5是本申请中红光LED-红光LED全双工链路在不同信噪比双向可达速率和正向工作电压间的关系示意图；
图6是本申请中一种多色可见光通信系统的框图；
图7是本申请中一种全双工可见光通信系统的框图；
图8是本申请中红色LED与绿色LED作为光接收器时交流阻抗谱；
图9是本申请中误码率与通信速率的关系示意图；
图10是本申请中红色LED-红色LED可见光通信链路3dB带宽和接收端额外串联阻值的关系示意图；
图11是本申请中又一种多色可见光通信系统的框图；
图12是本申请中一种由四对LED搭建的4×4的多色LED MIMO通信系统框图；
图13(a)是本申请中干扰比率为0.1时奇异值分解加电压分配的可达比特速率的示意图；
图13(b)是本申请中干扰比率为0.3时奇异值分解加电压分配的可达比特速率的示意图；
图13(c)是本申请中干扰比率为0.7时奇异值分解加电压分配的可达比特速率的示意图；
图13(d)是本申请中干扰比率为0.9时奇异值分解加电压分配的可达比特速率的示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
图1是本申请实施例提供的一种可见光通信收发器的示意图，该可见光通信收发器可以包括：LED光源101、Bias Tee电路102、驱动放大模块103和自适应放大均衡模块104。
其中，可见光通信收发器的结构连接关系为：Bias Tee电路102有三个端口，分别为直流偏置端口、射频端口以及射频和直流端口。LED光源101与Bias Tee电路102的射频和直流端口相连接，驱动放大模块103和 自适应放大均衡模块104并联，并联后与Bias Tee电路102的射频端口相连接。
按照图1所示的可见光通信收发器的结构，实现同时收发光信号的工作原理如下：
研究发现LED光源中的量子阱结构存在同时进行电光转换与光电转换的可能性，因此，基于LED光源中量子阱结构可同时进行电光转换与光电转换的特性，在LED光源发送光信号的同时接收光信号时，在本实施例中，将LED光源发送的光信号称为第一光信号，将LED光源接收的光信号称为第二光信号，在实际应用中，LED光源发送的第一光信号与接收的第二光信号的在光功率上存在小比例叠加，使得LED可能不会准确接收第二光信号，为了降低第一光信号与第二光信号在光功率上部分叠加带来的影响，本实施例提出了图1所示的可见光通信收发器中在信号输入端并联驱动放大模块103和自适应放大均衡模块104。驱动放大模块103用于对数字调制信号进行数模转换与放大，本实施例将进行数模转换与放大后的调制信号称为第一电信号，该第一电信号通过Bias Tee电路102传输至LED光源101，LED光源101根据第一电信号控制生成第一光信号的光功率。LED光源101对接收的第二光信号进行光电转换得到第二电信号，由于LED光源101对第二光信号的响应能力与发送的第一光信号的光功率负相关，因此，本实施例中图1所示的可见光通信收发器中的LED光源101在得到第二电信号后，通过Bias Tee电路102的射频端口输出至自适应放大均衡模块104，自适应放大均衡模块104根据第一光信号的光功率，调整第二电信号的增益，得到第二光信号所对应的电信号，使得LED光源可以准确接收第二光信号。
在实际的应用中，驱动放大模块可以采用电流反馈型运放电路，外接负反馈电阻来实现，其中，负反馈电阻越小，宽带越大，但是电路越不稳定，并且信噪比越小。当然，驱动放大模块也可以采用其他的电路结构来实现，本实施例不对驱动放大模块的具体实现方式做限定。
在本实施例中，自适应放大均衡模块104可以包括自适应增益控制电路和均衡电路，其中，自适应增益控制电路的增益系数与LED光源的正向偏压之间的关系为：若LED光源的正向偏压V大于LED光源的转换电压Vb时，
Figure PCTCN2017087415-appb-000002
其中，α、V0为常数，若LED光源的正向偏压V小于LED光源的转换电压Vb时，增益系数η＝e[βV]，其中，β为常数。
自适应放大均衡模块104中的均衡电路中可以包含低通滤波电路，用于增大第二电信号的带宽。
具体的，自适应放大均衡模块104可采用多种方式实现，例如，采用三极管作为功率放大器件，或者，采用buf管与运放的组合进行信号放大以及频带的预均衡。当然，本实施例提供的自适应放大均衡模块104的具体实现方式仅仅是可参考的实现方式，在实际的应用中，还可以采用其他的实现方式，本实施例对自适应放大均衡模块104的具体实现方式不做限定。
为了尽可能的减小第一光信号与第二光信号之间的干扰，发送第一光信号与接收第二光信号可以占用不同的频带，当采用相同的频带时，因为发送第一光信号已知，接收的第二光信号可以采用相应的干扰消除算法，结合适用的估计算法判决得到。采用运放的电路出现多种杂波信号，为放大器的振荡所致，需要调整电路的反馈，消除寄生电容的影响。
图1所示的可见光通信收发器中的LED光源101可以配置为单色LED光源、微米级LED光源、有机LED光源、量子点LED光源中的任意一种，或者上述光源的阵列中的任意一种。
其中，单色LED光源可以包括白光LED光源、红光LED光源、蓝光LED光源、绿光LED光源以及橙光LED光源等。其中，白光LED光源由蓝色芯片加黄色荧光粉构成，并且，蓝光芯片可以加载调制信号；红光LED光源中的红光芯片可以加载调制信号；蓝光LED光源中的蓝光芯片可以加载调制信号；绿光LED光源和橙光LED光源有独立的光信号收发电路。
在本实施例中，可见光通信收发器包括调制模块与解调模块，其中，调制模块与驱动放大模块103连接，用于生成数字调制信号，并将数字调制信号发送至驱动放大模块；解调模块与自适应放大模块104连接，用于对第一电信号进行解调。
通过本实施例中，根据可见光通信收发器的电路设计原理，可以得知可见光通信收发器可以同时收发光信号。因此，按照本实施例可见光通信收发器的电路设计，LED光源等一大类发光器件可以被用于制作具有同时 收发光信号能力的可见光通信收发器，可以降低由可见光通信收发器构成的通信系统的制造成本。
在实施例1所示的可见光通信收发器的基础上，本实施例提供了一种可见光通信系统，可见光通信系统的结构示意图如图2所示。
图2所示的可见光通信系统由两个可见光通信收发器组成，并且两个可见光通信收发器分别分布在左右两端，左端的LED光源201，可以为红色LED光源或者橘红色LED光源，此LED光源既发送光信号同时也接收光信号；与LED光源201连接的是第一发送接收模块202，此发送接收模块与实施例1中的可见光通信收发器的电路结构相同，发送接收模块202接收第一终端203生成的调制信号，并将接收后的信号传输至第二终端204；
右端的LED光源205，可以为红色LED光源或者橘红色LED光源，此LED光源既发送光信号同时也接收光信号；与LED光源205连接的是第二发送接收模块206，此发送接收模块206与实施例中的可见光通信收发器的电路结构相同，发送接收模块206接收第三终端207生成的调制信号，并将接收后的信号传输至第四终端208。
上述的第一终端203以及第三终端207都实现的是数据生成、串并转换和调制功能，在实际的应用中，均可以通过带FPGA芯片的终端完成；第二终端204与第四终端208实现的是模数转换、同步、判决解调和并串转换的功能，在实际的应用中可以由带FPGA芯片的终端完成。
[根据细则26改正22.08.2017]　
上述图2所示的可见光通信系统中的由LED光源201与LED光源205所组成的LED-LED链路实行同一时刻的双工通信。LED光源201与LED光源205可以组成的红光LED-红光LED链路。并且，红光LED-红光LED链路的频率响应曲线为图3所示，其中，横坐标为频率，纵坐标为频率响应；在红光LED光源中的红光芯片发送光信号的同时对所接收光信号的响应如图4所示，其中，图4(a)为红光LED光源的相对光信号响应强度与正向偏置电压之间的关系，其中，横坐标为正向偏置电压，纵坐标为相对光信号响应强度，图4(b)为红光LED光源的相对光信号响应强度与正向偏置电流之间的关系，其中，横坐标为正向偏置电流，纵坐标为光信号响应强度的倒数。
在以LED光源作为光探测器的可见光通信系统中，LED光源工作的高低电平对可见光通信系统的可达速率有较大影响，具体影响情况以红光LED-红光LED链路的OOK全双工系统为例来介绍。
假设LED光源工作在线性区，高电平为VH，低电平为VL，则该LED光源在高电平时的响应度如下公式(1)所示，在低电平时的响应度如下公式(2)所示。
Figure PCTCN2017087415-appb-000003
Figure PCTCN2017087415-appb-000004
接着，假设LED光源发出的信号经过信道在另一个LED光源接收，增益系数为A，噪声方差为σ2，则在高电平时的信噪比如下公式(3)所示，在低电平时的信噪比如下公式(4)所示。
Figure PCTCN2017087415-appb-000005
Figure PCTCN2017087415-appb-000006
通过公式(3)与公式(4)可以看出，SNRH与SNRL关于VL都是负相关的，VL越小，信噪比越大，因此取VL为电压线性区的下界。简单地考虑，LED光源发送零一等概率，则该OOK系统的可达速率可以写为如下公式(5)所示。
C(VH)＝COOK(SNRH(VH))+COOK(SNRL(VH))    (5)
在OOK系统中信道容量由二进制对称信道容量计算，接着，仿真不同信噪比下可达速率随VH的变化，在仿真的过程中VL＝1.7V，VH∈(1.7,2.2]，α＝26.5，β＝44.4。红光LED-红光LED全双工链路在不同信噪比双向可达速率和正向工作电压间的关系如图5所示，其中，横坐标为正向工作电压，纵坐标为双向可达速率，从图5可以看出，在低信噪比下，由于正向电压对响应的抑制作用，性能不理想，而在高信噪比的情况下，可达速率取得较好的效果，并且选择合适的高电平可使可达速率最大化。
由于LED光源作为接收端时，在高电平与低电平下具有不同的响应，因此希望能够通过改变高电平和低电平的比例，提高低电平出现的概率来 增加整个OOK通信系统的可达速率。这一目标可以通过编码使零一比例不均衡来实现，当然，改变发送端所发信号的零一比例后，二进制对称信道的容量会相应降低，通过比较不同信噪比下的可达速率，在信噪比值较小时候，改变符号1所占比例能有一定程度上提高最大可达速率，而当信噪比值较大或者符号1所占比例较小时，性能反而恶化，从图5可以看出，选择合适的高电平可以使可达速率最大化，这个最优高电平随着信噪比的增加而减小。
需要说明的是，图2所示的可见光通信系统只采用两个同时收发光信号的可见光通信收发器组成，在实际的应用中，可以在图2所示的可见光通信系统上搭建其他的电路，只要可以实现可以同时收发光信号即可，本实施不对可以实现同时收发光信号的可见光通信系统的具体结构作限定。
通过本实施例，实现全双工LED-LED链路同时刻发送光信号与接收光信号，并确定出使得可见光信通系统达到最大可达速率时，LED光源工作的高低电平。尤其是确定出可以使得可达速率最大化的高电平。此外，与现有中LED-PD与滤光片相结合的可见光通信系统相比，本实施例中，LED-LED链路的可见光通信系统，减少了滤光片，可以降低可将光通信系统的复杂度和成本。
参考图6，示出了本申请提供的一种多色可见光通信系统的结构示意图，该多色可见光通信系统可以包括：第一处理模块601、第一LED光源602、第一处理模块603、第一LED光源604、第二处理模块605、第二LED光源606、第二处理模块607以及第二LED光源608。
第一处理模块601，用于生成数字或模拟调制信号，并将该数字或模拟调制信号传输至第一LED光源602。
第一LED光源602，用于将数字或模拟调制信号进行光电转换得到光信号并发送。
第二LED光源606，用于接收第一LED光源602所发送的光信号，并将所接收的光信号进行光电转换得到电信号，并将该电信号发送至第二 处理模块605。
第二处理模块605，用于从电信号中获取所需信息。
第一处理模块603，用于生成数字或模拟调制信号，并将该数字或模拟调制信号传输至第一LED光源604。
第一LED光源604的功能与第一LED光源602相同。
第二LED光源608，用于接收第一LED光源604所发送的光信号，并将所接收的光信号进行光电转换得到电信号，并将该电信号发送至第二处理模块607。
第二处理模块607，用于从电信号中获取所需信息。
其中，所有第一处理模块可以通过简单的开关键控调制(OOK)或者正交频分复用调制(OFDM)传输至Bias Tee电路构成，所有第二处理模块可以通过一个信号处理板与一个客户端相连，当然，本实施例所提供的第一处理模块与第二处理模块的实现方式，只是一种实现方式，在实际的应用中第一处理模块和第二处理模块可以为其他的实现方式，只要可以满足第一处理模块与第二处理模块的功能即可。
由于LED光源具有光谱选择性接收的特性，因此，任一确定颜色的LED光源只对特定颜色的LED光源所发的光信号有较好的响应。为了确定可以响应的LED光源颜色对，以两个3×N的RGB LED发光二极管阵列组成的通信系统为例，确定红绿蓝三种颜色间哪些颜色的LED光源配对可以达到较好的光谱响应效果。
每个3×N的RGB LED发光二极管阵列中，每种颜色有N个发光二极管。同色发光二极管串联连接在模块上，不同颜色的LED之间电信号独立。除了无需额外滤光片就有的光谱带通响应特性，多色LED阵列也表现出不同于Si探测器阵列的独特现象。光链路的部分阻挡引起的RGB LED阵列信号失真取决于LED的数量和颜色。当3×3的RGB LED模块作为光电探测器，它可以被看作是某种光电探测器阵列。然而，如果与Si-PD阵列相比，由于属于宽带隙半导体，LED阵列表现出一些独特的光响应现象。上述3×3RGB LED模块作为光探测器接收有偏置的正弦波对应波长光信号的时候有如下三点特性：
1、如果一个或两个红色LED作为光电探测器被阻挡，直流和交流响应都消失；
2、如果一个绿色LED作为光电探测器被阻挡，直流响应降为零，但是交流响应鲁棒，如果任意两个绿色LED被阻挡，交流响应消失；
3、如果一个蓝色LED作为光电探测器被阻挡，直流响应减半但是交流响应鲁棒，如果任意两个蓝色LED被阻挡，直流响应消失，交流响应减半。
上述三个特性的原因主要有两个方面：一是LED是否与TVS封装，另一个是LED的带隙与TVS的阈值电压之间的匹配。如此，这个RGB LED阵列可以被用在可见光通信系统多色干扰管理，或者作为多模式探测器。
首先使用红色，绿色和蓝色LED同时作为光源和光接收器。9颗LED形成有3×3的RGB LED方阵，灯间距30mm，其中三颗相同颜色的LED串联。每个LED上有一个12°全光束角的透镜。透镜能使得LED到LED链路取得明显信道增益。其中，绿色和蓝色LED中有瞬态电压抑制器(TVS)与InGaN芯片并联，且采用倒装封装，红色LED采用AlInGaP芯片的陶瓷板上正装封装。
两个LED模组产生9个可能的颜色对，因为每边有红色，绿色或蓝色发光二极管。从接收端LED的输出信号通过示波器记录。9组实验进行：R-R，R-G，R-B，G-R，G-G、G-B，B-R，B-G，B-B。以前，基于AlInGaP或InGaN的光电二极管或太阳能电池备受关注。AlInGaP和InGaN/GaN LED的吸收光的光致发光(PL)和电流注入的电致发光(EL)也有相对的研究。Marcin Kowalczyk提到，LED可以探测小于其发射波长100nm以内的光。LED的结构类似于光电二极管(PD)都由PN结构成。两个效应约束了响应波长。带隙决定了LED的发射波长以及作为接收器的上截止波长。任何大于此波长的光子没有足够的能量激发电子-空穴对。但短波长光入射到LED上时，主要受材料对光子的吸收影响。当波长较短时，光子更容易被PN结的表面吸收，对光电流的贡献变小。这两种效应使LED成为比大多数商业光电二极管响应光谱更窄的光探测器。
通过上述实验，实验得出，红色LED可以响应红色和绿色的光，不响 应蓝光。据推测红色LED对蓝光不敏感缘自封装结构，其中红色LED的阴极在上方，大部分注入的蓝光被n-GaP吸收并不能有效激发发光层的电子空穴对。与红色LED对红色LED的响应相比，红色LED对绿色LED发出的绿光的响应要小得多，有数量级的差异。当使用绿色LED作为接收器时，它对红光没有反应。此外，不像红色的LED，绿色发光二极管对自身没有什么反应，但对蓝色LED发的蓝光有很强的响应。
在某种程度上，蓝色LED可以被视为很好的可见光窄谱蓝光接收器件，因为蓝色的LED只响应蓝光。然而，它对蓝光的响应强度和绿色LED相比不是太好。
接着，使用白色光源并在接收LED前放一个滤光片选择出被LED接收到的波长范围。滤光片选择如下(中心波长/半峰全宽，单位nm)：525/50，582/75，630/38，红色LED；435/40，475/50，525/50绿色LED；435/40，475/50蓝色LED。发射白光LED是由一个恒定的电压驱动，接收LED的响应由示波器测量电压得到。每个LED与滤光片的响应除以通过滤光片的光功率进行归一化。进一步通过与没有滤光片时的响应相比进行归一化(LED对整个白色光谱响应的测量)，得到相对响应率。因此，没有滤光片的相对响应率被定义为1。当LED的相对响应率大于1时，意味着在相应的波长范围内的贡献大于整个光谱的平均贡献。相对响应率越大意味着LED在这个光谱范围越敏感。
可以得到如表1、表2和表3所示的RGB LED的响应谱段，其中，表1为红色LED光源的响应谱段，表2为绿色LED光源的响应谱段，表3为蓝色LED光源的响应谱段。
表1
Figure PCTCN2017087415-appb-000007
表2
Figure PCTCN2017087415-appb-000008
表3
滤波器 无 435/40 475/50
响应电压(V) 4.7 3.3 0.61
相对响应率 1 2.89 2.16
根据上述表1、表2和表3所列出了RGB LED响应的结果，可以看出红色LED在582/75nm和630/38nm滤光片下有较强的响应，而蓝、绿发光二极管对435/40nm和475/50nm有较强响应。和绿色的LED相比，蓝光LED的光电响应波长通常较短。用同一颜色的LED作为发射机和接收机可能不是最优的，因为它的光电发射和光电响应光谱通常不匹配。然而，红色LED是个例外，它的发射和响应光谱不匹配程度较小。除此之外，可以为发射机接收器对找到合适的颜色对，例如蓝色发光二极管发射，用绿色发光二极管探测。
通过上述实验，可以发现两个相互之间几乎没有干扰的链路，R-R和B-G。此外，根据实验得到表4所示的品蓝色、蓝色、蓝绿色、绿色、琥珀色、橙红色、红色、深红色这8种颜色的响应光谱段。
接着，以这8种颜色LED光源分别作为接收端与发送端，得到如下表5所示的8中接收端与8种发送端之间的响应电压。
表4
发光二极管(LED)的颜色 响应光谱段
品蓝色(Royal Blue) 435/40
蓝色(Blue) 435/40
蓝绿色(Cyan) 435/40,475/50
绿色(Green) 435/40,475/50
琥珀色(Amber) 582/75
橙红色(Red-orange) 582/72,630/38
红色(Red) 630/38,582/75
深红色(Deep Red) 630/38,582/75,678/67
表5
Figure PCTCN2017087415-appb-000009
从表5中可以得出8对颜色对，分别为品蓝色与蓝色、蓝色与绿色、蓝绿色与绿色、绿色与深红色、琥珀色与深红色、橘红色与深红色、红色与橘红色、深红色与深红色。
图6所示的多色可见光通信系统中第一LED光源602与第二LED光源606、第一LED光源604与第二LED光源608只要从所述8对颜色中选择任意两对满足表5中矩阵元大于0.3即可。需要说明的是，图6所示 的一种多色可见光通信系统只是一种两条LED-LED链路的可见光通信系统的示例，在实际的应用中，还可以搭建三条、四条等等多条LED-LED链路的多色可见光通信系统，只要多条LED-LED链路中LED光源的颜色是为八对颜色中的不同颜色对并且满足表5中矩阵元大于0.3即可。
将图6所示的多色可见光通信系统中，第一LED光源602被配置为红色LED光源，第二LED光源606被配置为红色LED光源，第一LED光源604被配置为蓝色LED光源，第二LED光源608被配置为绿色LED光源时，并且在没有任何均衡和放大电路的情况下采用简单的开关键控调制(OOK)能提供的数据速率可达40-200kbps，满足窄带物联网(NB-IoT)的需求。得到如图7所示的一种全双工可见光通信系统的框图，可以适用于双向窄带物联网应用场景下。
图7显示了一种全双工可见光通信系统的框图，正向链路是从红色LED到红色LED，反向链路由蓝色LED到绿色LED。OOK信号由任意波形发生器产生并由发送端LED发送，偏置电压Vdc＝8V，峰峰值Vpp＝1V。接收端LED接收到的信号由示波器记录，离线计算误码率。
[根据细则26改正11.10.2017]　
红色LED和绿色LED作为接收端，如果接收端的阻抗与示波器的阻抗不匹配会影响接收信号强度，图8示出了红色LED与绿色LED作为光接收器时交流阻抗谱，其中，横坐标为频率，纵坐标为交流阻抗模值，该图给出了由网络分析仪测量得到的红色和绿色LED的阻抗大小，阻抗的实部是电阻，为了将LED输出电流转化为较大的电压，示波器的输入阻抗为1MΩ而不是50Ω。从图8中可以看出绿色LED相比于红色LED具有更小的电阻，因此受到阻抗不匹配更大的影响。图9示出了误码率与频率的关系示意图，其中，横坐标为频率，纵坐标为误码率，该图显示了从10kbps到50kbps数据率的误码率性能。R-R显示的最小误差是由发送的比特数确定(16384)，B-G有更高的误码率。根据此特性，为了提高链路带宽和传输性能，LED后可以接一个阻抗可调的放大电路。通过图10所示红色LED-红色LED可见光通信链路3dB带宽和接收端额外串联阻值的关系示意图，其中，横坐标为接收端额外串联阻值，纵坐标为3dB带宽，从图10的实验数据表明，提高链路带宽和传输性能可以通过阻抗调整的电路显著增加数据速率。
通过本实施例，可以构建多条LED-LED链路的全双工的多色可见光通信系统，利用LED光源的光谱选择性，多色可见光通信系统不需要滤光片，使得搭建多色可见光通信系统的成本降低，并且结构简单。此外，多颜色对的LED-LED链路的颜色对不同，因此可以提高通信系统的通信速率。
参考图11，示出了另外一种多色可见光通信系统的框图，此多色可见光通信系统由两个RGB LED阵列模块组成一个半双工2×2的MIMO LED-LED的可见光通信系统。在忽略颜色间干扰等情况下，该系统在没有任何均衡和放大电路的情况下采用简单的开关键控调制(OOK)能提供的数据速率可达40-200kbps，满足窄带物联网(NB-IoT)的需求，因此，该多色可见光通信系统同样可以适用于低复杂度窄带物联网的应用场景中。
如图9所示，由R-R LED链路和B-G LED链路构成的MIMO可见光通信链路在没有任何放大均衡电路的情况下,可以达到80kbps的速率。根据对发光二极管型光电探测器的研究，性能能够除了能由一个阻抗匹配的放大电路显著提升以外，还可以自适应的通过调节接收端LED信号电流到信号电压的串联阻抗，在信噪比和带宽之间获得平衡。图11所示的多色可见光通信系统还可以扩展到更多颜色的LED、有机LED，以及量子点LED等。
通过本实施例，采用不同LED具有波长选择性，响应光谱的特征搭建多色的MIMO VLC具有很大的潜力。这种多色LED-LED的MIMO VLC系统能够有效地利用光谱上的自由度，提升通信性能。并且由于不需要使用滤光片，能够极大地降低成本，提高系统的实用性。
参考图12，示出了一种由四对LED搭建的4×4的多色LED MIMO通信系统框图。
在未使用任何均衡和信道编码的情况下，用LED作为接收端的单点对单点的OOK调制离线测试能达到30Mbps的速率，并且误码率小于10-3，根据表5所示的不同LED之间响应的光谱选择性结果，LED光接收器可被认作是无需滤光片的窄谱光探测器。在实际搭建LED-LED MIMO VLC的时候，当选择窄光束角的LED光源时，由于偏离LED法线方向的角度增大，光强迅速减小，因此可以通过调节发送端和接收端排列，使得波长接近的LED在空间上分开，进一步减小干扰，这样能够使不同的LED之间的影响很小，在使用波分复用的时候干扰消除更加简单有效。
因此，设计出了图12所示的非对称多色双工可见光通信系统，为了消除不同LED带宽不同以及颜色间干扰而带来的同步问题，根据如表5实验测量的信道矩阵以及频谱响应曲线，选择其中的4对发送接收LED对，并且，信道矩阵为分块对角矩阵的四乘四的MIMO可见光通信系统，该四乘四的MIMO通信系统可以简化为两个独立的二乘二的MIMO，每一个MIMO系统中的LED速率相同，即不存在不等速率接收同步的问题。此外，蓝绿光部分的LED收发端使用的是不同的LED，而红光部分的收发端则是相同的LED，具有对称性，因此设计了一种上下行非对称的双工通信方式，蓝光部分只用作下行，红光部分时分复用上下行，上行进行反馈。
为了进一步降低LED-LED MIMO可见光通信的成本，本实施例采用低复杂度的MIMO收发策略。在可见光通信中，发送端LED的约束往往是由LED线性区的限制导致的峰值约束，而不是传统无线通信MIMO系统里的总功率或单根天线约束。这使得本实施例在使用MIMO的一些发送接收技术的时候需要做出响应的调整。本实施例研究了峰值受限对SVD分解产生的影响，比较了不同灯间干扰情况下两发送两接收端时SVD分解和MMSE-SIC对OOK和4PAM调制下的信道容量的影响。进一步分析了发送端LED电压分配对容量的影响，提出了根据接收机估计出的信噪比反馈给发送端并选择天线发送方式的低复杂度的组合最优发送接收机策略。
[根据细则26改正22.08.2017]　　
图13示出了2×2LED-LED MIMO可见光通信系统在不同对称颜色干扰下的奇异值分解加电压分配的可达比特速率的示意图，其中，图13(a)示出了干扰比率为0.1时奇异值分解加电压分配的双向可达比特速率的示意图，其中，横坐标为信噪比，纵坐标为双向可达比特速率；图13(b)示出了干扰比率为0.3时奇异值分解加电压分配的双向可达比特速率的示意图，其中，横坐标为信噪比，纵坐标为双向可达比特速率；图13(c)示出了干扰比率为0.7时奇异值分解加电压分配的双向可达比特速率的示意图，其中，横坐标为信噪比，纵坐标为双向可达比特速率；图13(d)示出了干扰比率为0.9时奇异值分解加电压分配的双向可达比特速率的示意图，其中，横坐标为信噪比，纵坐标为双向可达比特速率。根据不同干扰比率下的最优策略，确定了最优的调制方式以及MIMO算法后，经过数据输入、串并转换和调制，信号经Bias-T和偏置驱动合并输入到发送端LED上，接收端LED把光信号转变为电流信号，经信号放大和模数转换后通过FPGA芯片实现同步、判决解调和并串转换,最后输出数据。
需要说明的是，上述图12所示的多进多出多色可见光通信系统是采用4对LED搭建，只是一个多进多出的多色可见光通信系统的一个示例，在实际的应用中，还可以搭建除4对LED外的多进多出的多色可见光通信系统，本实施例不对多进多出的多色可见光通信系统具体的结构作限定。
通过本实施例，提供了一种非对称的多色可见光通信系统，此可见光通信系统采用非对称的双工通信方式，以消除不同LED带宽不同以及颜色间干扰而带来的同步问题。并且，本实施例的多色可见光通信系统采用，根据接收机估计出的信噪比反馈给发送端并选择天线发送方式的低复杂度的组合最优发送接收机策略，使得本实施例的多色可见光通信系统成本更低。
发光二极管作为光信号发送端时，偏置驱动电流会影响发光二极管的发光效率和电光响应频谱。驱动电流越大光效越低，带宽越高。对于同一种材料不同类型的蓝色发光二极管，3dB调制带宽的对数和发光效率近似在一条负斜率的直线上。同时偏置电压会对实际加载到发光二极管上的交流信号强度产生影响。实际加载到发光二极管上的交流信号强度和发光二极管对应电压处的阻抗与偏置器输出阻抗的分压成线性关系。发光二极管 作为接收端的时候，其光电响应谱和背景光功率有关。光功率增大会导致响应带宽的降低。对发光二极管作为光信号探测时作等效电路分析，发现接收的光功率平均值越大，结电容越大，漏电电阻越小，输出交流电流信号相对减小。
在可见光通信链路中，从发光二极管到光电二极管的链路能够通过拉近收发端的距离，以增强接收端的光功率的方式增强信噪比从而达到提升通信速率的目的。而以LED发送光信号，同时用LED接收光信号的时候，与光电二极管接收端不同，随着收发端距离的拉近，信号波形发生畸变。该现象不是因为LED光接收器饱和所致，而是LED接收端的带宽随着接收端光功率的增加而降低。本实施例通过分析导致LED的带宽随光功率变化的物理机理，修正了LED色散载流子模型，并与实验结果比较分析,获得了较好的匹配结果。LED作为探测器的非线性对通信的影响体现在带宽和信噪比上。本实施例仿真了不同光功率下的信噪比和符号间干扰(带宽)对不同调制方式的可达速率的影响。不同的调制方式有不同的最佳光功率工作点。据此本实施例可以在光功率限制或调制方式确定的条件下提升通信速率。在调制深度固定的情况下,低平均光功率会导致LED-LED链路高带宽低信噪比,低阶调制性能更优,高平均光功率会导致低带宽高信噪比,高阶调制性能更优。因此针对LED-LED光通信链路的这个特点，本实施例提出根据LED-LED链路的距离和方位角的变化导致的平均光功率的变化来自适应地调整调制阶数。
上述的根据LED-LED链路的距离和方位角的变化导致的平均光功率的变化来自适应地调整调制阶数的方法，可以应用于实施例2到实施例5所提供的可见光通信系统。
通过本实施例对不同光功率下的信噪比和符号间干扰对不同调制方式的可达速率的影响的研究，得出低平均光功率下，采用低阶调制方式，高平均光功率下，采用高阶调制方式，可以达到更高的可达速率。将这一性质应用在实施例2到实施例5中的可见光通信系统中，都可以根据光功率自适应调整调制阶数，使可见光通信系统达到更高的通信速率。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

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  1. 一种可见光通信收发器，其特征在于，所述可见光通信收发器包括：LED光源、Bias Tee电路、驱动放大模块和自适应放大均衡模块；
    其中，所述LED光源与所述Bias Tee电路的射频和直流混合端口相连接，所述驱动放大模块与所述自适应放大均衡模块并联，并联后与所述Bias Tee电路的射频端口相连接；
    所述驱动放大模块，用于对数字调制信号进行数模转换和放大得到第一电信号，并通过所述射频端口，将所述第一电信号发送至所述Bias Tee电路；
    所述Bias Tee电路，用于通过射频和直流端口将所述第一电信号发送至所述LED光源；
    所述LED光源，用于将所述第一电信号进行电光转换生成第一光信号并发送，同时对所接收的第二光信号进行光电转换得到第二电信号；其中，所述第二光信号包括对端发送的光信号、或者、所述LED光源发送的光信号激励外部材料产生的光信号，或者，反射后传回的光信号；所述LED光源对所述第二光信号的响应能力与所述第一光信号的光功率负相关；
    所述Bias Tee电路，用于从所述LED光源获取所述第二电信号，并将所述第二电信号通过所述射频端口传输至所述自适应放大均衡模块；
    所述自适应均衡模块，用于根据所述第一光信号的光功率，调整所述第二电信号的增益，得到所述第二光信号对应的电信号。
  2. 根据权利要求1所述的可见光通信收发器，其特征在于，所述自适应放大均衡模块包括：自适应增益控制电路与均衡电路；
    其中，若所述LED光源的正向偏置电压大于所述LED光源的转换电压时，所述自适应增益控制电路的增益系数设置为
    Figure PCTCN2017087415-appb-100001
    其中，V为正向偏置电压，V0为常数；
    若所述LED光源的正向偏置电压小于所述LED光源的转换电压时，所述自适应增益控制电路的增益系数设置为e[βV]；
    所述均衡电路，用于增大所述第二电信号的带宽。
  3. 根据权利要求1所述的可见光通信收发器，其特征在于，所述LED光源包括：单色LED光源、微米级LED光源、有机LED光源、量子点LED光源以及阵列中的任意一种。
  4. 根据权利要求1所述的可见光通信收发器，其特征在于，所述电光转换和所述光电转换这两个物理过程发生在同一材料微观结构上。
  5. 根据权利要求1所述的可见光通信收发器，其特征在于，所述LED光源在正常照明或显示时可以接收外部光信号。
  6. 一种可见光通信系统，其特征在于，所述可见光通信系统包括：
    两个可见光通信收发器，所述可见光通信收发器为所述权利要求1～5任一项所述的可见光通信收发器；
    所述两个可见光通信收发器之间通过光信号进行通信。
  7. 根据权利要求6所述的可见光通信系统，其特征在于，所述两个可见光通信收发器的LED光源颜色包括：红色与橙红色。
  8. 一种多色可见光通信系统，其特征在于，所述多色可见光通信系统包括：
    至少两对LED-LED链路，每对所述LED-LED链路包括一个发送器和一个接收器；每对所述LED-LED链路中的LED被配置了预设颜色对，并且，不同LED-LED链路中的LED光源为不同的颜色对；
    其中，所述发送器，用于生成并发送光信号；
    所述发送器，包括一个第一处理模块，以及，与所述第一处理模块相连的第一LED光源；所述第一处理模块，用于生成数字或模拟调制信号，并将所述数字或模拟调制信号传输至所述第一LED光源；所述第一LED 光源，用于将所述数字或模拟调制信号进行电光转换得到光信号并发送；
    所述接收器，用于接收所述光信号并从所述光信号中获取所需信息；
    所述接收器，包括一个第二处理模块，以及，与所述第二处理模块相连接的第二LED光源；所述第二LED光源，用于接收所述光信号，并将所述光信号进行光电转换得到所述数字或模拟调制信号；所述第二处理模块，用于从所述数字或模拟调制信号中获取所需信息。
  9. 根据权利要求8所述的多色可见光通信系统，其特征在于，所述LED-LED链路之间形成准对角信道矩阵，且，所述多色可见光通信系统的通信方式为全双工通信。
  10. 根据权利要求8所述的多色可见光通信系统，其特征在于，所述多色可见光通信系统包括两个可见光通信系统，每个所述可见光通信系统包括两对LED-LED链路；
    所述两对LED-LED链路中一对LED-LED链路中的发送器的LED光源被配置为红色LED光源，接收器的LED光源被配置为红色LED光源；另一对LED-LED链路中的发送器的LED光源被配置为蓝色LED光源，接收器的LED光源被配置为绿色LED光源；
    每个所述可见光通信系统的通信方式为非对称全双工通信，具体包括：
    蓝色LED光源被配置为下行通信方式，红光LED光源被配置为时分复用上下行，且进行上行时，将第二处理模块估计的信噪比反馈给第一处理模块并选择天线发送的通信方式。
  11. 根据权利要求8～10任意一项所述的多色可见光通信系统，其特征在于，所述第一处理模块，包括：
    低阶调制子模块，用于当所述LED-LED链路的平均光功率为低平均光功率时，按照低阶调制阶数对基带信号进行调制，得到所述数字或模拟调制信号；
    高阶调制子模块，用于当所述LED-LED链路的平均光功率为高平均 光功率时，按照高阶调制阶数对基带信号进行调制，得到所述数字或模拟调制信号。
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112489410A (zh) * 2019-09-11 2021-03-12 李冰 一种用于光电信号的收发装置及其运行方法
CN112865864A (zh) * 2020-12-31 2021-05-28 华南师范大学 可见光通信系统的发射信号模拟方法及信号模拟机
CN113271146A (zh) * 2021-05-14 2021-08-17 中车青岛四方机车车辆股份有限公司 一种可见光通信方法、装置、系统及计算机可读存储介质
CN113992267A (zh) * 2020-07-10 2022-01-28 Oppo广东移动通信有限公司 通信控制方法、装置、电子设备及存储介质
CN114499696A (zh) * 2021-11-29 2022-05-13 中国科学院西安光学精密机械研究所 水下蓝绿光高速全双工动中通系统及方法
CN115102614A (zh) * 2022-05-23 2022-09-23 中航光电科技股份有限公司 一种具有除污功能的全双工水下可见光mimo通信系统
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Families Citing this family (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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CN107968679B (zh) * 2017-11-20 2021-11-05 南京艾凯特光电科技有限公司 可见光通信装置
CN108234021A (zh) * 2017-12-28 2018-06-29 南京邮电大学 一种基于量子阱二极管器件的音频接收系统
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CN110609161A (zh) * 2019-09-26 2019-12-24 江苏理工学院 基于stm32的太阳能便携式示波器
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WO2022263009A1 (en) * 2021-06-18 2022-12-22 Telefonaktiebolaget Lm Ericsson (Publ) Reciprocity based optical wireless communication
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WO2023232271A1 (en) * 2022-05-31 2023-12-07 Telefonaktiebolaget Lm Ericsson (Publ) Mimo processing with led based reception of optical communication signals
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CN116054940B (zh) * 2023-04-03 2023-06-30 南昌大学 一种可见光通信装置
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CN117614529B (zh) * 2023-11-02 2024-08-09 浙江恒业电子股份有限公司 一种基于li-fi通讯技术的电能表

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103281273A (zh) * 2013-05-30 2013-09-04 东南大学 一种多载波可见光通信系统的直流偏置优化方法
CN103546214A (zh) * 2013-10-19 2014-01-29 西安邮电大学 一种基于可见光的图像通信系统
CN104243034A (zh) * 2014-09-30 2014-12-24 中国人民解放军信息工程大学 一种可见光通信系统及可见光通信方法
CN105915284A (zh) * 2016-04-22 2016-08-31 中山大学 一种双向传输的可见光通信装置

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL118873A0 (en) * 1996-07-16 1996-10-31 I R Lan Ltd Optical detector system and optical communication apparatus including same
US6664744B2 (en) * 2002-04-03 2003-12-16 Mitsubishi Electric Research Laboratories, Inc. Automatic backlight for handheld devices
US6941080B2 (en) * 2002-07-15 2005-09-06 Triquint Technology Holding Co. Method and apparatus for directly modulating a laser diode using multi-stage driver circuitry
US7388892B2 (en) * 2004-12-17 2008-06-17 Corning Incorporated System and method for optically powering a remote network component
US8014678B2 (en) * 2006-06-14 2011-09-06 Verizon Patent And Licensing Inc. Power supply
JP5161176B2 (ja) * 2008-09-26 2013-03-13 太陽誘電株式会社 可視光通信用送信機及び可視光通信システム
US9306546B2 (en) * 2012-02-06 2016-04-05 Finisar Corporation Integrated power supply for fiber optic communication devices and subsystems
CN106249850B (zh) * 2015-09-11 2020-03-17 北京智谷睿拓技术服务有限公司 基于可变形设备的交互方法、交互装置及用户设备
CN105812055B (zh) * 2016-03-30 2018-05-01 中国科学技术大学 半双工时分rgb led模组双向可见光通信的方法及系统
CN105959061A (zh) * 2016-06-21 2016-09-21 江苏大学 Led到led的半双工通信系统

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103281273A (zh) * 2013-05-30 2013-09-04 东南大学 一种多载波可见光通信系统的直流偏置优化方法
CN103546214A (zh) * 2013-10-19 2014-01-29 西安邮电大学 一种基于可见光的图像通信系统
CN104243034A (zh) * 2014-09-30 2014-12-24 中国人民解放军信息工程大学 一种可见光通信系统及可见光通信方法
CN105915284A (zh) * 2016-04-22 2016-08-31 中山大学 一种双向传输的可见光通信装置

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112489410A (zh) * 2019-09-11 2021-03-12 李冰 一种用于光电信号的收发装置及其运行方法
CN112489410B (zh) * 2019-09-11 2022-09-02 李冰 一种用于光电信号的收发装置及其运行方法
CN113992267A (zh) * 2020-07-10 2022-01-28 Oppo广东移动通信有限公司 通信控制方法、装置、电子设备及存储介质
CN113992267B (zh) * 2020-07-10 2023-02-28 Oppo广东移动通信有限公司 通信控制方法、装置、电子设备及存储介质
CN112865864A (zh) * 2020-12-31 2021-05-28 华南师范大学 可见光通信系统的发射信号模拟方法及信号模拟机
CN112865864B (zh) * 2020-12-31 2022-03-15 华南师范大学 可见光通信系统的发射信号模拟方法及信号模拟机
CN113271146A (zh) * 2021-05-14 2021-08-17 中车青岛四方机车车辆股份有限公司 一种可见光通信方法、装置、系统及计算机可读存储介质
CN114499696A (zh) * 2021-11-29 2022-05-13 中国科学院西安光学精密机械研究所 水下蓝绿光高速全双工动中通系统及方法
CN114499696B (zh) * 2021-11-29 2022-12-09 中国科学院西安光学精密机械研究所 水下蓝绿光高速全双工动中通系统及方法
CN115102614A (zh) * 2022-05-23 2022-09-23 中航光电科技股份有限公司 一种具有除污功能的全双工水下可见光mimo通信系统
CN115333634A (zh) * 2022-07-20 2022-11-11 大连海事大学 一种适用于商用照明led的高带宽、多自由度无线光通信系统
CN115333634B (zh) * 2022-07-20 2023-10-31 大连海事大学 一种适用于商用照明led的高带宽、多自由度无线光通信系统

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