CN107359936B - Novel light source based on visible light communication and power distribution method thereof - Google Patents

Novel light source based on visible light communication and power distribution method thereof Download PDF

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CN107359936B
CN107359936B CN201710571376.1A CN201710571376A CN107359936B CN 107359936 B CN107359936 B CN 107359936B CN 201710571376 A CN201710571376 A CN 201710571376A CN 107359936 B CN107359936 B CN 107359936B
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leds
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white
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CN107359936A (en
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王承祥
宋健
孙健
张文胜
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Shandong 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
    • 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
    • H04B10/564—Power control

Abstract

The invention relates to a novel light source based on visible light communication and a power distribution method thereof. The novel light source provides a brand new concept for the transmitting end of visible light communication; the novel light source overcomes the defects of the traditional light source in the visible light communication, and establishes a new standard for the development of the transmitting terminal in the visible light communication.

Description

Novel light source based on visible light communication and power distribution method thereof
Technical Field
The invention relates to a novel light source based on visible light communication and a power distribution method thereof, in particular to a novel visible light communication light source which combines white light LEDs with one or more groups of RGB LEDs and realizes communication and illumination functions simultaneously by regulating and controlling the power distribution of the RGB LEDs and the white light LEDs and a power distribution technology thereof, belonging to the technical field of visible light communication.
Background
In recent years, with the development of mobile communication, internet of things and smart cities, the number of applications and smart devices of wireless broadband communication is rapidly increasing, so that the traditional wireless spectrum resources are in short supply. This restricts the development and application of mobile communication, and at the same time, people have higher and higher requirements for communication service quality, and even more, the critical problem of spectrum resources is forced to be solved urgently in the next generation of 5G mobile communication. Compared with the traditional wireless communication, the visible light occupies extremely abundant spectrum resources, has high safety and electromagnetic immunity, and becomes a communication technology with great potential in 5G. Visible Light Communication (VLC) generally uses an LED as a transmitting end, converts an electrical signal into light intensity through the LED, and then reaches a receiving end through a free space. The optical signal is converted to an electrical signal at the receiving end by a photodetector.
Visible light communication systems need to implement both lighting and communication functions. Namely, no matter what kind of LED is adopted as the emitting end in the visible light communication system, the light source is ensured to provide white light meeting the lighting condition. Visible light communication systems generally use two common methods to obtain white light. One is to use a blue LED in combination with one or more phosphors to produce white light. The other is to use three primary colors RGB LEDs to generate white light. Although white LEDs can provide good illumination, the bandwidth and speed of the system are limited due to the low response rate of the phosphor. RGB LEDs will cost more to implement the illumination function than white LEDs, but RGB LEDs can provide higher system bandwidth for visible light systems. More importantly, RGB LEDs can make better use of Wavelength Division Multiplexing (WDM) and MIMO technologies for visible light systems, providing more independent communication channels for the system.
There are many colleges and research institutes from all parts of the world now conducting intensive research on visible light communication systems. In these studies, visible light communication systems all employ white light LEDs, monochromatic LEDs or multicolor LEDs as an emitting end, and mainly study modulation techniques and system performance. Visible light communication systems combining white light LEDs and RGB LEDs are not seen.
Chinese patent document CN 205909061U discloses an LED light source for visible light communication, which includes: a lighting module, a communication module and a base module; the lighting module consists of a white light LED; the communication module consists of RGBLED; the base module is a substrate carrying the lighting module and the communication module. However, this patent has the following drawbacks: 1. this patent only proposes lighting module and constitutes for white light LED, and communication module constitutes for RGB LED, and two are solitary modules to the high service quality requirement problem of illumination and communication simultaneously is not really solved. The lighting module does not take into account the control of the communication module's specific impact on the lighting at the time of lighting, and the communication module does not take into account the control of the lighting module's specific impact on the communication at the time of communication. The packaging mode of the patent cannot fundamentally solve the influence of the white light LED on the RGB LEDs during communication, and does not fundamentally solve the influence of the RGB LEDs on the white light LEDs during illumination. 2. The patent mainly relates to a composition material and an encapsulation material of a light source, and does not relate to specific technology and research in the communication field. The color development research between the white light LED and the RGB LEDs in different layouts is not involved. No specific communication means of white LEDs and RGB LEDs are involved. The specific light composition condition of RGB LEDs during communication is not involved, and other monochromatic light LEDs (such as yellow LEDs, cyan LEDs and the like) are not mentioned, so that the LED has no adaptivity. The power distribution problem in lighting and communication is not involved. 3. The materials and process flow consumables required by the light source in the patent are labor-consuming.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a novel light source based on visible light communication;
the invention also provides a power distribution method of the novel light source based on visible light communication;
based on the advantages of white light LEDs and RGB LEDs, the present invention proposes for the first time to combine the two into a visible light communication system. The combination provides firm technical support for the selection of the light source of the visible light communication system, and further expands the application of the visible light communication system.
Interpretation of terms:
1. VLC, which is visible light communication;
2. LEDs, referred to as light emitting diodes;
3. RGB LEDs, which refer to red, green and blue light emitting diodes;
4. WDM, which refers to wavelength division multiplexing technology;
5. MIMO, refers to multiple input multiple output technology;
6. CIE, refers to the international commission on illumination;
7. CRI, which refers to color rendering index;
8. OOK, which refers to on-off keying modulation;
9. PPM, which refers to pulse position modulation;
10. CAP, which refers to carrierless amplitude and phase modulation;
11. CSK, color shift keying modulation;
12. OFDM, refers to orthogonal frequency division multiplexing.
The technical scheme of the invention is as follows:
a novel light source based on visible light communication comprises a power divider, an LED driver, combined light of any one or combination of a plurality of monochromatic LEDs, wherein the monochromatic LEDs comprise R LEDs, G LEDs, B LEDs, yellow LEDs, cyan LEDs and the like, and the combined light of the combination of the plurality of LEDs comprises RG LEDs, RB LEDs, GB LEDs, RGB LEDs and the like. The power divider adaptively adjusts a power division coefficient according to a data stream received during communication, namely a power ratio coefficient between the power of the combined light and the power of the white light LED, and controls the LED driver to light the white light LED and the combined light through the power divider.
The novel light source provides a brand new concept for the transmitting end of visible light communication; the novel light source overcomes the defects of the traditional light source in the visible light communication, and establishes a new standard for the development of the transmitting terminal in the visible light communication.
According to the power distribution method of the novel light source based on visible light communication, the white light LEDs and the combined light are used as the emitting end and the light source, the physical optical filter and the photoelectric detector are used as the receiving end, the light source is separated into independent red, green and blue light channels through the physical optical filter, and independent red, green and blue light signals are detected and converted into electric signals through the photoelectric detector, and the power distribution method comprises the following steps:
(1) determination of the relative optical power spectrum S of white LEDswhite(lambda) and relative optical power spectra of the combined light
Figure BDA0001349760870000021
And
Figure BDA0001349760870000022
(2) the power ratios of the combined light and white LEDs were set as:
Figure BDA0001349760870000023
and
Figure BDA0001349760870000024
refers to the power of the R LEDs in RGB LEDs,
Figure BDA0001349760870000026
refers to the power of G LEDs in RGB LEDs,refers to the power, P, of B LEDs in RGB LEDswhiteRefers to the power, η, of white light LEDsrRefers to the ratio of the power of R LEDs to the power of white LEDs in RGB LEDs, ηgRefers to the ratio of the power of G LEDs to the power of white LEDs in RGB LEDs, ηbRefers to the ratio of the power of the B LEDs in the RGB LEDs to the power of the white LEDs;
(3) calculating the relative optical power spectrum S of the novel light sourceLight(λ), the calculation formula is shown in formula (I):
SLight(λ)＝Swhite(λ)+ηSLED(λ) (Ⅰ)
in the formula (I), eta SLED(λ) is corresponding
Figure BDA0001349760870000028
Figure BDA0001349760870000029
One of (1);
when the white light LEDs are combined with the R LEDs,
Figure BDA00013497608700000319
when white LEDs are combined with G LEDs,
Figure BDA0001349760870000031
when white LEDs are combined with B LEDs,
Figure BDA0001349760870000033
when white LEDs are combined with RG LEDs,
Figure BDA0001349760870000034
Figure BDA0001349760870000035
white lightWhen the LEDs are combined with the RB LEDs,
Figure BDA0001349760870000036
when white light LEDs are combined with GB LEDs,
Figure BDA0001349760870000037
when white LEDs are combined with RGB LEDs,
Figure BDA0001349760870000038
Figure BDA0001349760870000039
(4) calculating tristimulus value X of novel light sourceLight、YLight、ZLight: the calculation formula is shown in formulas (II) to (IV):
Figure BDA00013497608700000310
Figure BDA00013497608700000311
Figure BDA00013497608700000312
in the (II) to (IV),
Figure BDA00013497608700000313
andrespectively CIE1931 standard chromaticity observer tristimulus values;
(5) calculating the coordinate value (x) of the novel light source in the chromaticity coordinate systemlight,ylight) Coordinate value (u)light,vlight)。xlight、ylightIs the coordinate value of the novel light source in CIE1931 chromaticity coordinate, ulight、vlightIs a novel light source in the CIE 1960 uniform color space (CIE 1960 uniform color space isA coordinate system for measuring colors), the calculation formula is represented by formulas (v) - (ix):
Figure BDA00013497608700000316
zlight＝1-xlight-ylight (Ⅶ)
Figure BDA00013497608700000317
Figure BDA00013497608700000318
(6) obtaining the coordinate value (x) according to the step (5)light,ylight) Coordinate value (u)light,vlight) And a CIE 1964 uniform color space, wherein the CIE 1964 uniform color space is obtained by improving a 1960 uniform chromaticity space in 1964 by the CIE, and is a two-dimensional coordinate system for measuring color, and the color difference delta E of 14 test color samples respectively irradiated by a novel light source and a standard light source is obtainedjThe standard light source refers to a Planckian radiator or a standard illuminant D or other international standard illuminants specified by CIE; the 14 test color samples refer to 14 munsell standard color samples used to measure color rendering index; color difference Δ EjThe specific calculation process is calculated according to the standard determined by the international commission on illumination, and the process is as follows:
Figure BDA0001349760870000041
in formula (X), u'j，v'jIs adaptive color shift; c and d are parameters of the novel light source; cr，drIs a parameter of a standard illuminant; cj，djIs a parameter for 14 color samples under the novel light source;is a parameter for converting chromaticity data into CIE 1964 uniform chromaticity space;
(7) finding the special color rendering index R of a novel light sourcejThe calculation formula is shown as formula (XI):
Rj＝100-4.6△Ej (Ⅺ)
formula (xi) wherein j is 1, …, 14;
(8) the color of the novel light source, i.e. the general color rendering index R, was evaluated using 1-8 test color samples (the first 8 of 14 color samples)aThe calculation formula is shown as formula (XII):
Figure BDA0001349760870000043
Rathe larger the value, the closer the new light source is to the standard light source; when R isaEqual to 100, the new light source is identical to the standard light source. For indoor lighting, R is requiredaNot less than 80, i.e. with RaEta is constrained by more than or equal to 80r、ηgAnd ηbIs measured.
(9) After being transmitted through a free optical channel, the optical signal reaches a receiving end, and the multicolor optical signals detected by the photoelectric detectors are respectively as follows:
after passing through the red filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000051
The formula (XII) and (XIII) are shown as follows:
Figure BDA0001349760870000052
Figure BDA0001349760870000053
after passing through the green filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000054
The formula (II) is shown in formulas (XIV) and (XV):
Figure BDA0001349760870000055
Figure BDA0001349760870000056
after passing through a blue filter, the average optical signal power received by a receiving end
Figure BDA0001349760870000057
The calculation formula (XVI) is shown in formulas (XVI) and (XVII):
in the formula (XI) -formula (XVI), GT(f) The frequency response of the combined light is the optical power spectral density, B is the system bandwidth,
Figure BDA00013497608700000510
the direct channel gain in visible light communication is expressed as shown in formula (XVIII):
Figure BDA00013497608700000511
in the formula (XVII), ε means a radiation angle,
Figure BDA00013497608700000512
is referred to as the angle of incidence, AAPDRefers to the area of the photodetector; gain of optical filterThe value is 1 and the field angle of the photodetector is phio(ii) a Lambertian index t ═ ln2/ln (cos Φ)o)；
Figure BDA00013497608700000514
Is the Euclidean distance from the transmitting end to the receiving end; when in use
Figure BDA00013497608700000515
Time, condenser gain
Figure BDA00013497608700000516
m is a refractive index when
Figure BDA00013497608700000517
Time, condenser gain
Figure BDA00013497608700000518
When in use
Figure BDA00013497608700000519
Decision function
Figure BDA00013497608700000520
When in useDecision function
Figure BDA00013497608700000522
(10) If the lighting and communication functions are provided in a spatial manner, namely: the white light LEDs provide illumination, the combined light provides a communication function, the step (11) is carried out, if the illumination and the communication function are provided in a time division mode, namely the white light LEDs are periodically flashed, the RGB LEDs communicate when the white light LEDs are extinguished, the communication time is set to be T within one period, the illumination time is (1-T) T, and the T is more than or equal to 0 and less than or equal to 1, the step (12) is carried out;
(11) at the receiving end of the communication, the receiver,
after passing through the red filter, the signal-to-noise ratio of the receiving end is as shown in formula (XIX):
Figure BDA0001349760870000061
after passing through the green filter, the signal-to-noise ratio of the receiving end is as shown in formula (XX):
Figure BDA0001349760870000062
after passing through the blue filter, the signal-to-noise ratio of the receiving end is as shown in formula (XXI):
Figure BDA0001349760870000063
in the formula (XIV) -formula (XXI), R means the responsivity of the photodetector;
Figure BDA0001349760870000064
refers to the total power of noise, including shot noise, thermal noise and amplifier noise;
the total noise power is expressed as shown in equations (XXII) - (XXV):
Figure BDA0001349760870000065
Figure BDA0001349760870000066
Figure BDA0001349760870000067
in the formulae (XXII) to (XXV), T is absolute temperature, q is amount of charge, IBCIs referred to as background current, I20.562; v is the fixed capacitance per unit area of the photodetector, κCIs the Boltzmann constant, GoIs open loop voltage gain, theta is field effect crystalPipe channel noise factor, gmRefers to the transconductance of a field effect transistor,
Figure BDA0001349760870000069
refers to the average optical power received by the photodetector from the white LEDs and the combined light,
Figure BDA00013497608700000610
including average optical power through red filter
Figure BDA00013497608700000611
Average optical power through green filterAnd average optical power through the blue filter
Figure BDA00013497608700000613
Average optical power through red filter
Figure BDA00013497608700000614
As shown in formula (XXVI):
Figure BDA00013497608700000615
average optical power through green filter
Figure BDA0001349760870000071
As shown in formula (XXVII):
Figure BDA0001349760870000072
average optical power through blue filter
Figure BDA0001349760870000073
As shown in formula (XXVIII):
entering a step (13);
(12) in the time division mode, the optical power received by the photodetector is the optical signal power: since in this operating mode the white light illumination does not influence the communication of the RGB LEDs. The control period T eliminates the effect on illumination when rgblds are communicating during human visual persistence.
Average optical power through red filter
Figure BDA0001349760870000075
As shown in formula (XXIX):
Figure BDA0001349760870000076
average optical power through green filter
Figure BDA0001349760870000077
As shown in formula (XXX):
average optical power through blue filter
Figure BDA0001349760870000079
As shown in formula (XXXI):
Figure BDA00013497608700000710
(13) the power of the combined light and white LEDs is constrained: calculating R under different combinations according to the steps (1) to (8)aCalculating SNR from the formula (XII) to the formula (XVII)r、SNRgAnd SNRbTo constrain ηr，ηgAnd ηb；
(14) The visible light communication system judges whether the color rendering index is qualified, and if so, the power and root of the combined light are adjustedDetermining the SNR of the lowest receiving end of the system, the BER of the maximum bit error rate and the general color rendering index R of the illumination requirement according to different modulation modesaCo-confining of eta of combined lightr、ηgAnd ηbIf not, the control system adjusts the power of the combined light, gives out the maximum power ratio range of the combined light under different power combinations, and then enters the step (14);
(15) judging whether the signal-to-noise ratio and the bit error rate are qualified, if so, determining the range of the communication power ratio of the combined light, otherwise, adjusting the power ratio of the white light LEDs and the combined light, giving the minimum power ratio of the system, and entering the step (15) again. The range of power ratios that the combined light can use for communication is ultimately determined by the color rendering index, signal-to-noise ratio, and bit error rate requirements.
According to a preferred embodiment of the invention, the relative optical power spectrum S of the white LEDs is determined using a double Gaussian modelwhite(lambda) and relative optical power spectra of the combined light
Figure BDA0001349760870000081
And
Figure BDA0001349760870000082
the formula is shown as formula (XXXII) and formula (XXXIII):
Figure BDA0001349760870000083
Figure BDA0001349760870000084
in the formulae (XXXII), (XXXIII) and (XXXIII), SLED(lambda) is the relative optical power spectrum S of the white LEDswhite(λ), relative optical power spectrum of the combined light
Figure BDA0001349760870000085
Andany one of (a); λ is the spectral wavelength, λ0Is the peak wavelength, Δ λ0.5Is the peak wavelength half-width (spectral radiance bandwidth).
The invention has the beneficial effects that:
1. the invention provides a novel light source combining white light LEDs and RGB LEDs for the first time, and provides a brand new concept for the emitting end of visible light communication; the novel light source overcomes the defects of the traditional light source in visible light communication, and establishes a new standard for the development of the transmitting end in the visible light communication; the new light source technology will promote the further development of the lighting market, and provide the necessary technical support for the development of visible light communication in the future.
2. The invention provides a new power configuration algorithm constraint, and realizes the simultaneity, high quality and robustness of illumination and communication.
3. The white light LEDs in the invention are responsible for illumination, and the combined light is responsible for communication. The white light LEDs can provide stable illumination, so that the illumination is flicker-free, and the injury to human eyes caused by light stroboflash is avoided.
4. The invention realizes the functions of illumination and communication in a space mode and a time division mode, further increases the diversity of system communication, and improves the multi-scene application of the system, such as: underwater communication, mine communication, outdoor communication, indoor communication, vehicle-to-vehicle communication, aircraft communication, and the like.
5. The combined light has seven groups and modes, and the structure is flexible, so that the flexibility and the adaptability of the visible light communication system are improved.
6. The invention restricts the power ratio of the combined light and the white light LEDs based on the algorithm of the color rendering index, the signal-to-noise ratio and the bit error rate, can control the communication area of the visible light communication system to improve the safety of the system and ensure the rights and interests of users.
Drawings
FIG. 1 is a theoretical model diagram of a novel light source;
FIG. 2 is a structural connection diagram of the novel light source;
FIG. 3 is a schematic diagram of the provision of lighting and communication functions in a spatial manner;
FIG. 4 is a schematic diagram of the provision of illumination and communication functions in a time division manner;
FIG. 5 is a power control logic diagram;
FIG. 6 is a graph showing the results of performance analysis of the combination of R LEDs and white LEDs in example 8 using DCO-OFDM modulation;
FIG. 7 is a graph showing the results of performance analysis of the combination of G LEDs and white light LEDs in example 9 using DCO-OFDM modulation;
FIG. 8 is a graph showing the results of performance analysis of the combination of B LEDs and white LEDs in example 10 using DCO-OFDM modulation;
Detailed Description
The invention is further defined in the following, but not limited to, the figures and examples in the description.
Example 1
A novel light source based on visible light communication comprises a power divider, an LED driver, white light LEDs and R LEDs. As shown in fig. 2; the power divider adaptively adjusts a power distribution coefficient according to a data stream received during communication, namely a power ratio coefficient between the power of the RLEDs and the power of the white light LED, and controls the LED driver to light the white light LED and the R LEDs through the power divider.
The novel light source provides a brand new concept for the transmitting end of visible light communication; the novel light source overcomes the defects of the traditional light source in the visible light communication, and establishes a new standard for the development of the transmitting terminal in the visible light communication.
Example 2
The novel light source based on visible light communication in embodiment 1 is characterized by comprising a power divider, an LED driver, white light LEDs and G LEDs.
Example 3
The novel light source based on visible light communication in embodiment 1 is characterized by comprising a power divider, an LED driver, white light LEDs and B LEDs.
Example 4
The novel light source based on visible light communication described in embodiment 1 is distinguished by comprising a power divider, an LED driver, white light LEDs and RG LEDs.
Example 5
The novel light source based on visible light communication described in embodiment 1 is distinguished by comprising a power divider, an LED driver, white light LEDs and RB LEDs.
Example 6
The novel light source based on visible light communication in embodiment 1 is characterized by comprising a power divider, an LED driver, white light LEDs and GB LEDs.
Example 7
The novel light source based on visible light communication in embodiment 1 is characterized by comprising a power divider, an LED driver, white light LEDs and RGB LEDs.
Example 8
In the power distribution method of the novel light source described in embodiment 1, white LEDs and R LEDs are used as an emitting end and a light source, a physical filter and a photodetector are used as a receiving end, the light source is separated into independent red, green and blue light channels by the physical filter, and the independent red, green and blue light channels are converted into electrical signals by the photodetector, as shown in fig. 1, the method includes the following steps:
(1) determination of the relative optical power spectrum S of white LEDswhiteRelative optical power spectra of (lambda) and R LEDsThe formula is shown as formula (XXXII) and formula (XXXIII):
Figure BDA0001349760870000093
in the formulae (XXXII), (XXXIII) and (XXXIII), SLED(lambda) is the relative optical power spectrum S of the white LEDswhiteRelative optical power spectra of (lambda), R LEDs
Figure BDA0001349760870000094
λ is the spectral wavelength, λ0Is the peak wavelength, Δ λ0.5Is the peak wavelength half-width (spectral radiance bandwidth).
(2) The power ratio of the R LEDs to the white LEDs is set as:
Figure BDA0001349760870000095
refers to the power, P, of R LEDs in RGB LEDswhiteRefers to the power, η, of white light LEDsrRefers to the ratio of the power of the R LEDs in the RGB LEDs to the power of the white LEDs;
(3) calculating the relative optical power spectrum S of the novel light sourceLight(λ), the calculation formula is shown in formula (I):
SLight(λ)＝Swhite(λ)+ηSLED(λ) (Ⅰ)
in the formula (I), the compound is shown in the specification,
Figure BDA0001349760870000101
(4) calculating tristimulus value X of novel light sourceLight、YLight、ZLight: the calculation formula is shown in formulas (II) to (IV):
Figure BDA0001349760870000102
Figure BDA0001349760870000104
in the (II) to (IV),
Figure BDA0001349760870000105
and
Figure BDA0001349760870000106
respectively CIE1931 standard chromaticity observer tristimulus values;
(5) calculating the coordinate value (x) of the novel light source in the chromaticity coordinate systemlight,ylight) Coordinate value (u)light,vlight)。xlight、ylightIs the coordinate value of the novel light source in CIE1931 chromaticity coordinate, ulight、vlightThe coordinate values of the novel light source in a CIE 1960 uniform chromaticity space (the CIE 1960 uniform color space is a coordinate system for measuring color), and the calculation formulas are shown in formulas (V) - (IX):
Figure BDA0001349760870000107
Figure BDA0001349760870000108
zlight＝1-xlight-ylight (Ⅶ)
Figure BDA0001349760870000109
Figure BDA00013497608700001010
(6) obtaining the coordinate value (x) according to the step (5)light,ylight) Coordinate value (u)light,vlight) And a CIE 1964 uniform color space, wherein the CIE 1964 uniform color space is obtained by improving a 1960 uniform chromaticity space in 1964 by the CIE, and is a two-dimensional coordinate system for measuring color, and the color difference delta E of 14 test color samples respectively irradiated by a novel light source and a standard light source is obtainedjThe standard light source refers to a Planckian radiator or a standard illuminant D or other international standard illuminants specified by CIE; the 14 test color samples refer to 14 munsell standard color samples used to measure color rendering index; color difference Δ EjSpecific obtaining procedure ofThe calculation process is as follows according to the standard determined by the international commission on illumination:
Figure BDA0001349760870000111
in formula (X), u'j，v'jIs adaptive color shift; c and d are parameters of the novel light source; cr，drIs a parameter of a standard illuminant; cj，djIs a parameter for 14 color samples under the novel light source;is a parameter for converting chromaticity data into CIE 1964 uniform chromaticity space;
(7) finding the special color rendering index R of a novel light sourcejThe calculation formula is shown as formula (XI):
Rj＝100-4.6△Ej (Ⅺ)
formula (xi) wherein j is 1, …, 14;
(8) the color of the novel light source, i.e. the general color rendering index R, was evaluated using 1-8 test color samples (the first 8 of 14 color samples)aThe calculation formula is shown as formula (XII):
Rathe larger the value, the closer the new light source is to the standard light source; when R isaEqual to 100, the new light source is identical to the standard light source. For indoor lighting, R is requiredaNot less than 80, i.e. with RaEta is constrained by more than or equal to 80r、ηgAnd ηbIs measured.
(9) After being transmitted through a free optical channel, the optical signal reaches a receiving end, and the multicolor optical signals detected by the photoelectric detectors are respectively as follows:
after passing through the red filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000114
The formula (XII) and (XIII) are shown as follows:
Figure BDA0001349760870000121
Figure BDA0001349760870000122
after passing through the green filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000123
The formula (II) is shown in formulas (XIV) and (XV):
Figure BDA0001349760870000124
Figure BDA0001349760870000125
after passing through a blue filter, the average optical signal power received by a receiving end
Figure BDA0001349760870000126
The calculation formula (XVI) is shown in formulas (XVI) and (XVII):
in the formula (XI) -formula (XVI), GT(f) The spectral power density of the frequency response of the LEDs, B the system bandwidth,
Figure BDA0001349760870000129
the direct channel gain in visible light communication is expressed as shown in formula (XVIII):
in the formula (XVII), ε means a radiation angle,
Figure BDA00013497608700001211
is referred to as the angle of incidence, AAPDRefers to the area of the photodetector; gain of optical filter
Figure BDA00013497608700001212
The value is 1 and the field angle of the photodetector is phio(ii) a Lambertian index t ═ ln2/ln (cos Φ)o)；
Figure BDA00013497608700001213
Is the Euclidean distance from the transmitting end to the receiving end; when in use
Figure BDA00013497608700001214
Time, condenser gain
Figure BDA00013497608700001215
m is a refractive index when
Figure BDA00013497608700001216
Time, condenser gain
Figure BDA00013497608700001217
When in use
Figure BDA00013497608700001218
Decision function
Figure BDA00013497608700001219
When in use
Figure BDA00013497608700001220
Decision function
Figure BDA00013497608700001221
(10) If the illumination and communication functions are provided in a spatial manner, as shown in fig. 3, the white LEDs provide stable illumination, and the R LEDs adjust their power according to the power of the white LEDs in different combinations. Namely: the white light LEDs provide illumination and the R LEDs provide communication functions at the same time, step (11) is carried out, if the illumination and communication functions are provided in a time division mode, as shown in FIG. 4, the white light LEDs are periodically flashed, the R LEDs communicate when the white light LEDs are extinguished, the communication time is set to be T within one period, the illumination time is (1-T) T, and T is more than or equal to 0 and less than or equal to 1, and step (12) is carried out;
(11) at the receiving end of the communication, the receiver,
after passing through the red filter, the signal-to-noise ratio of the receiving end is as shown in formula (XIX):
Figure BDA00013497608700001222
after passing through the green filter, the signal-to-noise ratio of the receiving end is as shown in formula (XX):
Figure BDA0001349760870000131
after passing through the blue filter, the signal-to-noise ratio of the receiving end is as shown in formula (XXI):
Figure BDA0001349760870000132
in the formula (XIV) -formula (XXI), R means the responsivity of the photodetector;
Figure BDA0001349760870000133
refers to the total power of noise, including shot noise, thermal noise and amplifier noise;
the total noise power is expressed as shown in equations (XXII) - (XXV):
Figure BDA0001349760870000134
Figure BDA0001349760870000135
Figure BDA0001349760870000136
Figure BDA0001349760870000137
in the formulae (XXII) to (XXV), T is absolute temperature, q is amount of charge, IBCIs referred to as background current, I20.562; v is the fixed capacitance per unit area of the photodetector, κCIs the Boltzmann constant, GoIs referred to as open loop voltage gain, theta is referred to as field effect transistor channel noise factor, gmRefers to the transconductance of a field effect transistor,
Figure BDA0001349760870000138
refers to the average optical power received by the photodetector from the white LEDs and the R LEDs,
Figure BDA0001349760870000139
including average optical power through red filterAverage optical power through green filter
Figure BDA00013497608700001311
And average optical power through the blue filter
Figure BDA00013497608700001312
Average optical power through red filter
Figure BDA00013497608700001313
As shown in formula (XXVI):
Figure BDA00013497608700001314
average optical power through green filter
Figure BDA00013497608700001315
As shown in formula (XXVII):
average optical power through blue filter
Figure BDA0001349760870000142
As shown in formula (XXVIII):
Figure BDA0001349760870000143
entering a step (13);
(12) in the time division mode, the optical power received by the photodetector is the optical signal power: since in this operating mode the white light illumination does not influence the communication of the RGB LEDs. The control period T eliminates the effect on illumination when rgblds are communicating during human visual persistence.
Average optical power through red filter
Figure BDA0001349760870000144
As shown in formula (XXIX):
Figure BDA0001349760870000145
average optical power through green filterAs shown in formula (XXX):
Figure BDA0001349760870000147
average optical power through blue filter
Figure BDA0001349760870000148
As shown in formula (XXXI):
Figure BDA0001349760870000149
(13) the power of R LEDs and white LEDs is constrained: calculating R under different combinations according to the steps (1) to (8)aCalculating SNR from the formula (XII) to the formula (XVII)rTo constrain ηr；
As shown in FIG. 5, in order to secure the color rendering index R when only R LEDs and white LEDs are combineda≥80，ηrIt is necessary to ensure 0.124 or less. When OOK is selected as the modulation mode, in order to satisfy SNRr15.6dB or more, and the BER of the bit error rate is 10 or more-6When it is necessary to ensure ηrGreater than or equal to 0.063, so that 0.063. ltoreq. eta.r≤0.124。
When DCO-OFDM is selected as the modulation mode, high-quality communication with the bit error rate of 0.85m high and the radius of 1.8m can be ensured, and eta is more than or equal to 0.12 and can be determinedrLess than or equal to 0.124. As shown in fig. 6, a graph of the performance analysis results when the R LEDs and the white LEDs are combined using DCO-OFDM modulation, the abscissa represents the horizontal distance of the photoreceiver from the R LEDs, and the ordinate represents the bit error rate.
Example 9
In the power distribution method of the novel light source described in embodiment 2, the white LEDs and the G LEDs are used as the emitting end and the light source, the physical filter and the photodetector are used as the receiving end, the light source is separated into independent red, green and blue light channels by the physical filter, and the independent red, green and blue light channels are converted into electrical signals by the photodetector, as shown in fig. 1, the method includes the following steps:
(1) determination of the relative optical power spectrum S of white LEDswhiteRelative optical power spectra of (lambda) and G LEDs
Figure BDA0001349760870000151
The formula is shown as formula (XXXII) and formula (XXXIII):
Figure BDA0001349760870000152
in the formulae (XXXII), (XXXIII) and (XXXIII), SLED(lambda) is the relative optical power spectrum S of the white LEDswhiteRelative optical power spectra of (lambda), G LEDs
Figure BDA0001349760870000154
λ is the spectral wavelength, λ0Is the peak wavelength, Δ λ0.5Is the peak wavelength half-width (spectral radiance bandwidth).
(2) The power ratios of G LEDs to white LEDs were set as:
Figure BDA0001349760870000155
Figure BDA0001349760870000156
refers to the power, P, of G LEDs in RGB LEDswhiteRefers to the power, η, of white light LEDsgRefers to the ratio of the power of the G LEDs in the RGB LEDs to the power of the white LEDs;
(3) calculating the relative optical power spectrum S of the novel light sourceLight(λ), the calculation formula is shown in formula (I):
SLight(λ)＝Swhite(λ)+ηSLED(λ) (Ⅰ)
in the formula (I), the compound is shown in the specification,
Figure BDA0001349760870000157
(4) calculating tristimulus value X of novel light sourceLight、YLight、ZLight: the calculation formula is shown in formulas (II) to (IV):
Figure BDA0001349760870000158
Figure BDA0001349760870000159
Figure BDA00013497608700001510
in the (II) to (IV),
Figure BDA00013497608700001511
and
Figure BDA00013497608700001512
respectively CIE1931 standard chromaticity observer tristimulus values;
(5) calculating the coordinate value (x) of the novel light source in the chromaticity coordinate systemlight,ylight) Coordinate value (u)light,vlight)。xlight、ylightIs the coordinate value of the novel light source in CIE1931 chromaticity coordinate, ulight、vlightThe coordinate values of the novel light source in a CIE 1960 uniform chromaticity space (the CIE 1960 uniform color space is a coordinate system for measuring color), and the calculation formulas are shown in formulas (V) - (IX):
Figure BDA0001349760870000161
Figure BDA0001349760870000162
zlight＝1-xlight-ylight (Ⅶ)
Figure BDA0001349760870000163
Figure BDA0001349760870000164
(6) obtaining the coordinate value (x) according to the step (5)light,ylight) Coordinate value (u)light,vlight) And CIE 1964 uniform color space consisting of InternationalThe Commission on illumination (CIE) was obtained in 1964 by improving 1960 uniform chromaticity space, and is a two-dimensional coordinate system for measuring color, and the color difference Delta E of 14 test color samples respectively irradiated by a novel light source and a standard light source is obtainedjThe standard light source refers to a Planckian radiator or a standard illuminant D or other international standard illuminants specified by CIE; the 14 test color samples refer to 14 munsell standard color samples used to measure color rendering index; color difference Δ EjThe specific calculation process is calculated according to the standard determined by the international commission on illumination, and the process is as follows:
Figure BDA0001349760870000165
in formula (X), u'j，v'jIs adaptive color shift; c and d are parameters of the novel light source; cr，drIs a parameter of a standard illuminant; cj，djIs a parameter for 14 color samples under the novel light source;
Figure BDA0001349760870000171
is a parameter for converting chromaticity data into CIE 1964 uniform chromaticity space;
(7) finding the special color rendering index R of a novel light sourcejThe calculation formula is shown as formula (XI):
Rj＝100-4.6△Ej (Ⅺ)
formula (xi) wherein j is 1, …, 14;
(8) the color of the novel light source, i.e. the general color rendering index R, was evaluated using 1-8 test color samples (the first 8 of 14 color samples)aThe calculation formula is shown as formula (XII):
Figure BDA0001349760870000172
Rathe larger the value, the closer the new light source is to the standard light source; when R isaEqual to 100, the new light source is identical to the standard light source. For indoor lighting, R is requiredaNot less than 80, i.e. with RaEta is constrained by more than or equal to 80r、ηgAnd ηbIs measured.
(9) After being transmitted through a free optical channel, the optical signal reaches a receiving end, and the multicolor optical signals detected by the photoelectric detectors are respectively as follows:
after passing through the red filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000173
The formula (XII) and (XIII) are shown as follows:
after passing through the green filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000176
The formula (II) is shown in formulas (XIV) and (XV):
Figure BDA0001349760870000177
Figure BDA0001349760870000178
after passing through a blue filter, the average optical signal power received by a receiving end
Figure BDA0001349760870000179
The calculation formula (XVI) is shown in formulas (XVI) and (XVII):
Figure BDA00013497608700001710
in the formula (XI) -formula (XVI), GT(f) The G LEDs frequency response optical power spectral density, B the system bandwidth,
Figure BDA00013497608700001712
the direct channel gain in visible light communication is expressed as shown in formula (XVIII):
in the formula (XVII), ε means a radiation angle,
Figure BDA0001349760870000182
is referred to as the angle of incidence, AAPDRefers to the area of the photodetector; gain of optical filter
Figure BDA0001349760870000183
The value is 1 and the field angle of the photodetector is phio(ii) a Lambertian index t ═ ln2/ln (cos Φ)o)；
Figure BDA0001349760870000184
Is the Euclidean distance from the transmitting end to the receiving end; when in use
Figure BDA0001349760870000185
Time, condenser gain
Figure BDA0001349760870000186
m is a refractive index whenTime, condenser gain
Figure BDA0001349760870000188
When in use
Figure BDA0001349760870000189
Decision functionWhen in useDecision function
(10) If the lighting and communication functions are provided in a spatial manner, namely: providing illumination by the white light LEDs and providing a communication function by the G LEDs at the same time, entering step (11), if the illumination and communication functions are provided in a time division mode, namely the white light LEDs are periodically flashed, the G LEDs are communicated when the white light LEDs are extinguished, setting the communication time to be T within a period, setting the illumination time to be (1-T) T, and setting the value of T to be more than or equal to 0 and less than or equal to 1, and entering step (12);
(11) at the receiving end of the communication, the receiver,
after passing through the red filter, the signal-to-noise ratio of the receiving end is as shown in formula (XIX):
Figure BDA00013497608700001813
after passing through the green filter, the signal-to-noise ratio of the receiving end is as shown in formula (XX):
after passing through the blue filter, the signal-to-noise ratio of the receiving end is as shown in formula (XXI):
Figure BDA00013497608700001815
in the formula (XIV) -formula (XXI), R means the responsivity of the photodetector;
Figure BDA00013497608700001816
refers to the total power of noise, including shot noise, thermal noise and amplifier noise;
the total noise power is expressed as shown in equations (XXII) - (XXV):
Figure BDA00013497608700001817
Figure BDA0001349760870000191
Figure BDA0001349760870000192
Figure BDA0001349760870000193
in the formulae (XXII) to (XXV), T is absolute temperature, q is amount of charge, IBCIs referred to as background current, I20.562; v is the fixed capacitance per unit area of the photodetector, κCIs the Boltzmann constant, GoIs referred to as open loop voltage gain, theta is referred to as field effect transistor channel noise factor, gmRefers to the transconductance of a field effect transistor,
Figure BDA0001349760870000194
refers to the average optical power received by the photodetector from the white LEDs and the G LEDs,
Figure BDA0001349760870000195
including average optical power through red filterAverage optical power through green filter
Figure BDA0001349760870000197
And average optical power through the blue filter
Figure BDA0001349760870000198
Average optical power through red filter
Figure BDA0001349760870000199
As shown in formula (XXVI):
average optical power through green filterAs shown in formula (XXVII):
Figure BDA00013497608700001912
average optical power through blue filter
Figure BDA00013497608700001913
As shown in formula (XXVIII):
Figure BDA00013497608700001914
entering a step (13);
(12) in the time division mode, the optical power received by the photodetector is the optical signal power: since in this operating mode the white light illumination does not influence the communication of the RGB LEDs. The control period T eliminates the effect on illumination when rgblds are communicating during human visual persistence.
Average optical power through red filter
Figure BDA00013497608700001915
As shown in formula (XXIX):
Figure BDA0001349760870000201
average optical power through green filter
Figure BDA0001349760870000202
As shown in formula (XXX):
Figure BDA0001349760870000203
average optical power through blue filterAs shown in formula (XXXI):
Figure BDA0001349760870000205
(13) the power of G LEDs and white LEDs is constrained: calculating R under different combinations according to the steps (1) to (8)aCalculating SNR from the formula (XII) to the formula (XVII)rTo constrain ηr；
In order to ensure the color rendering index R when G LEDs and white LEDs are combineda≥80，ηgIt is necessary to ensure 0.2 or less. When OOK is selected as the modulation mode, in order to satisfy SNRg15.6dB or more, and the BER of the bit error rate is 10 or more-6When it is necessary to ensure ηgGreater than or equal to 0.063, so that it can be determined that eta is greater than or equal to 0.062gLess than or equal to 0.2, since when etab>When 0.2, the error is large. When DCO-OFDM is selected as the modulation mode, high-quality communication with the bit error rate of 0.85m high and the radius of 1.8m can be ensured, and the eta is more than or equal to 0.1 and can be determinedgLess than or equal to 0.2. As shown in fig. 7, a graph of performance analysis results when the G LEDs and white LEDs are combined using DCO-OFDM modulation, with horizontal distance of the photo receiver from the G LEDs on the abscissa and bit error rate on the ordinate.
Example 10
The power distribution method of the novel light source based on visible light communication described in embodiment 3, the white LEDs and the B LEDs are used as the emitting end and the light source, the physical filter and the photodetector are used as the receiving end, the light source is separated into independent red, green and blue light channels by the physical filter, and the independent red, green and blue light channels are converted into electric signals by the photodetector, which includes the following steps:
(1) determination of the relative optical power spectra S of white LEDs using a double Gaussian modelwhite(λ) and B LEDS combined relative optical power spectra
Figure BDA0001349760870000206
The formula is shown as formula (XXXII) and formula (XXXIII):
Figure BDA0001349760870000207
in the formulae (XXXII), (XXXIII) and (XXXIII), SLED(lambda) is the relative optical power spectrum S of the white LEDswhite(λ)、
Figure BDA0001349760870000209
Any one of (a); λ is the spectral wavelength, λ0Is the peak wavelength, Δ λ0.5Is the peak wavelength half-width (spectral radiance bandwidth).
(2) The power ratio of the B LEDs to the white LEDs was set as:
Figure BDA0001349760870000212
refers to the power, P, of B LEDs in RGB LEDswhiteRefers to the power, η, of white light LEDsbRefers to the ratio of the power of the B LEDs in the RGB LEDs to the power of the white LEDs;
(3) calculating the relative optical power spectrum S of the novel light sourceLight(λ), the calculation formula is shown in formula (I):
SLight(λ)＝Swhite(λ)+ηSLED(λ) (Ⅰ)
in the formula (I), the compound is shown in the specification,
Figure BDA0001349760870000213
(4) calculating tristimulus value X of novel light sourceLight、YLight、ZLight: formula for calculationAs shown in formulas (II) to (IV):
Figure BDA0001349760870000214
Figure BDA0001349760870000216
in the (II) to (IV),
Figure BDA0001349760870000217
and
Figure BDA0001349760870000218
respectively CIE1931 standard chromaticity observer tristimulus values;
(5) calculating the coordinate value (x) of the novel light source in the chromaticity coordinate systemlight,ylight) Coordinate value (u)light,vlight)。xlight、ylightIs the coordinate value of the novel light source in CIE1931 chromaticity coordinate, ulight、vlightThe coordinate values of the novel light source in a CIE 1960 uniform chromaticity space (the CIE 1960 uniform color space is a coordinate system for measuring color), and the calculation formulas are shown in formulas (V) - (IX):
Figure BDA00013497608700002110
zlight＝1-xlight-ylight (Ⅶ)
Figure BDA00013497608700002111
Figure BDA00013497608700002112
(6) obtaining the coordinate value (x) according to the step (5)light,ylight) Coordinate value (u)light,vlight) And a CIE 1964 uniform color space, wherein the CIE 1964 uniform color space is obtained by improving a 1960 uniform chromaticity space in 1964 by the CIE, and is a two-dimensional coordinate system for measuring color, and the color difference delta E of 14 test color samples respectively irradiated by a novel light source and a standard light source is obtainedjThe standard light source refers to a Planckian radiator or a standard illuminant D or other international standard illuminants specified by CIE; the 14 test color samples refer to 14 munsell standard color samples used to measure color rendering index; color difference Δ EjThe specific calculation process is calculated according to the standard determined by the international commission on illumination, and the process is as follows:
Figure BDA0001349760870000221
in formula (X), u'j，v'jIs adaptive color shift; c and d are parameters of the novel light source; cr，drIs a parameter of a standard illuminant; cj，djIs a parameter for 14 color samples under the novel light source;
Figure BDA0001349760870000222
is a parameter for converting chromaticity data into CIE 1964 uniform chromaticity space;
(7) finding the special color rendering index R of a novel light sourcejThe calculation formula is shown as formula (XI):
Rj＝100-4.6△Ej (Ⅺ)
formula (xi) wherein j is 1, …, 14;
(8) the color of the novel light source, i.e. the general color rendering index R, was evaluated using 1-8 test color samples (the first 8 of 14 color samples)aThe calculation formula is shown as formula (XII):
Figure BDA0001349760870000223
Rathe larger the value, the closer the new light source is to the standard light source; when R isaEqual to 100, the new light source is identical to the standard light source. For indoor lighting, R is requiredaNot less than 80, i.e. with RaEta is constrained by more than or equal to 80r、ηgAnd ηbIs measured.
(9) After being transmitted through a free optical channel, the optical signal reaches a receiving end, and the multicolor optical signals detected by the photoelectric detectors are respectively as follows:
after passing through the red filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000231
The formula (XII) and (XIII) are shown as follows:
Figure BDA0001349760870000232
after passing through the green filter, the average optical signal power received by the receiving end
Figure BDA0001349760870000234
The formula (II) is shown in formulas (XIV) and (XV):
Figure BDA0001349760870000235
Figure BDA0001349760870000236
after passing through a blue filter, the average optical signal power received by a receiving end
Figure BDA0001349760870000237
Is shown as formula (XV)I) And (XVII):
Figure BDA0001349760870000238
Figure BDA0001349760870000239
in the formula (XI) -formula (XVI), GT(f) The frequency response of the combined light is the optical power spectral density, B is the system bandwidth,
Figure BDA00013497608700002310
the direct channel gain in visible light communication is expressed as shown in formula (XVIII):
Figure BDA00013497608700002311
in the formula (XVII), ε means a radiation angle,
Figure BDA00013497608700002312
is referred to as the angle of incidence, AAPDRefers to the area of the photodetector; gain of optical filter
Figure BDA00013497608700002313
The value is 1 and the field angle of the photodetector is phio(ii) a Lambertian index t ═ ln2/ln (cos Φ)o)；
Figure BDA00013497608700002314
Is the Euclidean distance from the transmitting end to the receiving end; when in use
Figure BDA00013497608700002315
Time, condenser gain
Figure BDA00013497608700002316
m is a refractive index when
Figure BDA00013497608700002317
Time, condenser gain
Figure BDA00013497608700002318
When in use
Figure BDA00013497608700002319
Decision function
Figure BDA00013497608700002320
When in use
Figure BDA00013497608700002321
Decision function
Figure BDA00013497608700002322
(10) If the lighting and communication functions are provided in a spatial manner, namely: the white light LEDs provide illumination, the B LEDs provide a communication function, the step (11) is carried out, if the illumination and the communication function are provided in a time division mode, namely the white light LEDs are periodically flashed, the B LEDs communicate when the white light LEDs are extinguished, the communication time is set to be T within a period, the illumination time is (1-T) T, and the T is more than or equal to 0 and less than or equal to 1, the step (12) is carried out;
(11) at the receiving end of the communication, the receiver,
after passing through the red filter, the signal-to-noise ratio of the receiving end is as shown in formula (XIX):
Figure BDA0001349760870000241
after passing through the green filter, the signal-to-noise ratio of the receiving end is as shown in formula (XX):
Figure BDA0001349760870000242
after passing through the blue filter, the signal-to-noise ratio of the receiving end is as shown in formula (XXI):
Figure BDA0001349760870000243
in the formula (XIV) -formula (XXI), R means the responsivity of the photodetector;
Figure BDA0001349760870000244
refers to the total power of noise, including shot noise, thermal noise and amplifier noise;
the total noise power is expressed as shown in equations (XXII) - (XXV):
Figure BDA0001349760870000245
Figure BDA0001349760870000246
Figure BDA0001349760870000248
in the formulae (XXII) to (XXV), T is absolute temperature, q is amount of charge, IBCIs referred to as background current, I20.562; v is the fixed capacitance per unit area of the photodetector, κCIs the Boltzmann constant, GoIs referred to as open loop voltage gain, theta is referred to as field effect transistor channel noise factor, gmRefers to the transconductance of a field effect transistor,refers to the average optical power received by the photodetector from the white LEDs and the combined light,
Figure BDA00013497608700002410
including average optical power through red filterAverage optical power through green filter
Figure BDA00013497608700002412
And byAverage optical power of blue filter
Figure BDA00013497608700002413
Average optical power through red filter
Figure BDA0001349760870000251
As shown in formula (XXVI):
average optical power through green filter
Figure BDA0001349760870000253
As shown in formula (XXVII):
Figure BDA0001349760870000254
average optical power through blue filterAs shown in formula (XXVIII):
Figure BDA0001349760870000256
entering a step (13);
(12) in the time division mode, the optical power received by the photodetector is the optical signal power: since in this operating mode the white light illumination does not influence the communication of the RGB LEDs. The control period T eliminates the effect on illumination when rgblds are communicating during human visual persistence.
Average optical power through red filterAs shown in formula (XXIX):
Figure BDA0001349760870000258
average optical power through green filterAs shown in formula (XXX):
Figure BDA00013497608700002510
average optical power through blue filter
Figure BDA00013497608700002511
As shown in formula (XXXI):
Figure BDA00013497608700002512
(13) the power of B LEDs and white LEDs is constrained: calculating R under different combinations according to the steps (1) to (8)aCalculating SNR from the formula (XII) to the formula (XVII)bTo constrain ηb；
In order to ensure the color rendering index R when B LEDs and white LEDs are combineda≥80，ηb0.0861 or less needs to be ensured.
When OOK is selected as the modulation mode, in order to satisfy SNRb15.6dB or more, and the BER of the bit error rate is 10 or more-6When it is necessary to ensure ηbGreater than or equal to 0.062, so that it can be determined that 0.062. ltoreq. etab≤0.0861。
When DCO-OFDM is selected as the modulation mode, high-quality communication with the bit error rate of 0.85m high and the radius of 1.4m can be ensured, and the eta of 0.062 ≤ can be determinedbLess than or equal to 0.09. As shown in fig. 8, a graph of performance analysis results when the B LEDs and the white LEDs were combined using DCO-OFDM modulation, with horizontal distance of the photo receiver from the B LEDs on the abscissa and bit error rate on the ordinate.

Claims (2)

1. A power distribution method of a novel light source based on visible light communication is characterized in that the novel light source based on visible light communication comprises a power distributor, an LED driver, combined light of any one or a combination of a plurality of types of white light LEDs and monochromatic LEDs, the power distributor adaptively adjusts a power distribution coefficient according to data flow received during communication, namely a power ratio coefficient between the power of the combined light and the power of a white light LED, and the LED driver is controlled by the power distributor to light the white light LED and the combined light;
the white light LEDs and the combined light are used as an emitting end and a light source, the physical optical filter and the photoelectric detector are used as a receiving end, the light source is separated into independent red, green and blue light channels through the physical optical filter, and the independent red, green and blue light channels are converted into electric signals through the photoelectric detector, and the method comprises the following steps:
(1) determination of the relative optical power spectrum S of white LEDswhite(lambda) and relative optical power spectra of the combined light
Figure FDA0002260549410000011
And
(2) the power ratios of the combined light and white LEDs were set as:
Figure FDA0002260549410000013
and
Figure FDA0002260549410000014
Figure FDA0002260549410000015
refers to the power of the R LEDs in RGB LEDs,
Figure FDA0002260549410000016
refers to the power of G LEDs in RGB LEDs,refers to the power, P, of B LEDs in RGB LEDswhiteRefers to the power, η, of white light LEDsrRefers to the ratio of the power of R LEDs to the power of white LEDs in RGB LEDs, ηgRefers to the ratio of the power of G LEDs to the power of white LEDs in RGB LEDs, ηbRefers to the ratio of the power of the B LEDs in the RGB LEDs to the power of the white LEDs;
(3) calculating the relative optical power spectrum S of the novel light sourceLight(λ), the calculation formula is shown in formula (I):
SLight(λ)＝Swhite(λ)+ηSLED(λ)(Ⅰ)
in the formula (I), eta SLED(λ) is corresponding
Figure FDA0002260549410000018
Figure FDA0002260549410000019
One of (1);
when the white light LEDs are combined with the R LEDs,
Figure FDA00022605494100000110
when white LEDs are combined with G LEDs,
Figure FDA00022605494100000111
Figure FDA00022605494100000112
when white LEDs are combined with B LEDs,
Figure FDA00022605494100000113
when white LEDs are combined with RG LEDs,
Figure FDA00022605494100000114
Figure FDA00022605494100000115
when the white light LEDs are combined with the RB LEDs,
Figure FDA00022605494100000116
when white light LEDs are combined with GB LEDs,
Figure FDA00022605494100000117
when white LEDs are combined with RGB LEDs,
Figure FDA00022605494100000118
Figure FDA00022605494100000119
(4) calculating tristimulus value X of novel light sourceLight、YLight、ZLight: the calculation formula is shown in formulas (II) to (IV):
Figure FDA0002260549410000021
Figure FDA0002260549410000022
Figure FDA0002260549410000023
in the (II) to (IV),
Figure FDA0002260549410000024
and
Figure FDA0002260549410000025
respectively CIE1931 standard chromaticity observer tristimulus values;
(5) calculating the coordinate value (x) of the novel light source in the chromaticity coordinate systemlight,ylight) Coordinate value (u)light,vlight)；xlight、ylightIs the coordinate value of the novel light source in CIE1931 chromaticity coordinate, ulight、vlightIs the coordinate value of the novel light source in the CIE 1960 uniform chromaticity space, and the calculation formula is shown in formulas (V) - (IX)) Shown in the figure:
Figure FDA0002260549410000026
Figure FDA0002260549410000027
zlight＝1-xlight-ylight(Ⅶ)
Figure FDA0002260549410000028
Figure FDA0002260549410000029
(6) obtaining the coordinate value (x) according to the step (5)light,ylight) Coordinate value (u)light,vlight) And CIE 1964 uniform color space, and calculating the color difference delta E of 14 test color samples respectively irradiated by the novel light source and the standard light sourcejThe standard light source refers to a Planckian radiator or a standard illuminant D or other international standard illuminants specified by CIE; the 14 test color samples refer to 14 munsell standard color samples used to measure color rendering index; color difference Δ EjThe specific calculation process is calculated according to the standard determined by the international commission on illumination, and the process is as follows:
Figure FDA0002260549410000031
in formula (X), u'j，v'jIs adaptive color shift; c and d are parameters of the novel light source; cr，drIs a parameter of a standard illuminant; cj，djIs a parameter for 14 color samples under the novel light source;
Figure FDA0002260549410000032
is the conversion of chromaticity data into CIE 1964Parameters of uniform color space;
(7) finding the special color rendering index R of a novel light sourcejThe calculation formula is shown as formula (XI):
Rj＝100-4.6△Ej (Ⅺ)
formula (xi) wherein j is 1, …, 14;
(8) evaluating the color of the novel light source, i.e. the general color rendering index R, using 1-8 test color samplesaThe calculation formula is shown as formula (XII):
Figure FDA0002260549410000033
(9) after being transmitted through a free optical channel, the optical signal reaches a receiving end, and the multicolor optical signals detected by the photoelectric detectors are respectively as follows:
after passing through the red filter, the average optical signal power received by the receiving endThe formula (XII) and (XIII) are shown as follows:
Figure FDA0002260549410000035
Figure FDA0002260549410000036
after passing through the green filter, the average optical signal power received by the receiving end
Figure FDA0002260549410000041
The formula (II) is shown in formulas (XIV) and (XV):
Figure FDA0002260549410000042
Figure FDA0002260549410000043
after passing through a blue filter, the average optical signal power received by a receiving end
Figure FDA0002260549410000044
The calculation formula (XVI) is shown in formulas (XVI) and (XVII):
Figure FDA0002260549410000046
in the formula (XI) -formula (XVI), GT(f) The frequency response of the combined light is the optical power spectral density, B is the system bandwidth,
Figure FDA0002260549410000047
the direct channel gain in visible light communication is expressed as shown in formula (XVIII):
Figure FDA0002260549410000048
in the formula (XVIII), ε means a radiation angle,
Figure FDA0002260549410000049
is referred to as the angle of incidence, AAPDRefers to the area of the photodetector; gain of optical filter
Figure FDA00022605494100000410
The value is 1 and the field angle of the photodetector is phio(ii) a Lambertian index t ═ ln2/ln (cos Φ)o)；
Figure FDA00022605494100000420
Is the Euclidean distance from the transmitting end to the receiving end; when in use
Figure FDA00022605494100000411
Time, condenser gain
Figure FDA00022605494100000412
m is a refractive index when
Figure FDA00022605494100000413
Time, condenser gain
Figure FDA00022605494100000414
When in use
Figure FDA00022605494100000415
Decision function
Figure FDA00022605494100000416
When in use
Figure FDA00022605494100000417
Decision function
Figure FDA00022605494100000418
(10) If the lighting and communication functions are provided in a spatial manner, namely: the white light LEDs provide illumination, the combined light provides a communication function, the step (11) is carried out, if the illumination and the communication function are provided in a time division mode, namely the white light LEDs are periodically flashed, the RGB LEDs communicate when the white light LEDs are extinguished, the communication time is set to be T within one period, the illumination time is (1-T) T, and the T is more than or equal to 0 and less than or equal to 1, the step (12) is carried out;
(11) at the receiving end of the communication, the receiver,
after passing through the red filter, the signal-to-noise ratio of the receiving end is as shown in formula (XIX):
after passing through the green filter, the signal-to-noise ratio of the receiving end is as shown in formula (XX):
after passing through the blue filter, the signal-to-noise ratio of the receiving end is as shown in formula (XXI):
Figure FDA0002260549410000052
in the formula (XIX) -formula (XXI), R means the responsivity of the photodetector;
Figure FDA0002260549410000053
refers to the total power of noise, including shot noise, thermal noise and amplifier noise;
the total noise power is expressed as shown in equations (XXII) - (XXV):
Figure FDA0002260549410000054
Figure FDA0002260549410000055
Figure FDA0002260549410000056
Figure FDA0002260549410000057
in the formulae (XXII) to (XXV), T is absolute temperature, q is amount of charge, IBCIs referred to as background current, I20.562; v is the fixed capacitance per unit area of the photodetector, κCIs the Boltzmann constant, GoIs referred to as open loop voltage gain, theta is referred to as field effect transistor channel noise factor, gmRefers to the transconductance of a field effect transistor,
Figure FDA0002260549410000058
refers to the average optical power received by the photodetector from the white LEDs and the combined light,
Figure FDA0002260549410000059
including average optical power through red filter
Figure FDA00022605494100000510
Average optical power through green filter
Figure FDA00022605494100000511
And average optical power through the blue filter
Average optical power through red filter
Figure FDA00022605494100000513
As shown in formula (XXVI):
Figure FDA00022605494100000514
average optical power through green filter
Figure FDA00022605494100000515
As shown in formula (XXVII):
Figure FDA0002260549410000061
average optical power through blue filter
Figure FDA0002260549410000062
As shown in formula (XXVIII):
entering a step (13);
(12) in the time division mode, the optical power received by the photodetector is the optical signal power:
average optical power through red filter
Figure FDA0002260549410000064
As shown in formula (XXIX):
Figure FDA0002260549410000065
average optical power through green filter
Figure FDA0002260549410000066
As shown in formula (XXX):
Figure FDA0002260549410000067
average optical power through blue filter
Figure FDA0002260549410000068
As shown in formula (XXXI):
Figure FDA0002260549410000069
(13) the power of the combined light and white LEDs is constrained: calculating R under different combinations according to the steps (1) to (8)aCalculating SNR from the formula (XIX) -formula (XXI)r、SNRgAnd SNRbTo constrain ηr，ηgAnd ηb；
(14) The visible light communication system judges whether the color rendering index is qualified, if so, the power of the combined light is adjusted, and the signal-to-noise ratio (SNR) of the lowest receiving end, the maximum Bit Error Rate (BER) and the general color rendering index (R) required by illumination of the system are determined according to different modulation modesaCo-confining of eta of combined lightr、ηgAnd ηbIf not, the control system adjusts the power of the combined light, gives out the maximum power ratio range of the combined light under different power combinations, and then enters the step (14);
(15) and (4) judging whether the signal-to-noise ratio and the bit error rate are qualified, if so, determining the range of the communication power ratio of the combined light, otherwise, adjusting the power ratio of the white light LEDs and the combined light, giving the lowest power ratio of the system, entering the step (15) again, and finally determining the range of the communication power ratio of the combined light according to the requirements of the color rendering index, the signal-to-noise ratio and the bit error rate.
2. The method of claim 1 wherein the relative optical power spectra S of white LEDs is determined using a double Gaussian modelwhite(lambda) and relative optical power spectra of the combined light
Figure FDA00022605494100000610
And
Figure FDA0002260549410000071
the formula is shown as formula (XXXII) and formula (XXXIII):
Figure FDA0002260549410000072
Figure FDA0002260549410000073
in the formulae (XXXII), (XXXIII) and (XXXIII), SLED(lambda) is the relative optical power spectrum S of the white LEDswhite(λ), relative optical power spectrum of the combined light
Figure FDA0002260549410000074
And
Figure FDA0002260549410000075
any one of (a); λ is the spectral wavelength, λ0Is the peak wavelength, Δ λ0.5Is the peak wavelength half width.
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