CN109951229B - Method for jointly transmitting information and energy in visible light communication system - Google Patents

Method for jointly transmitting information and energy in visible light communication system Download PDF

Info

Publication number
CN109951229B
CN109951229B CN201910151387.3A CN201910151387A CN109951229B CN 109951229 B CN109951229 B CN 109951229B CN 201910151387 A CN201910151387 A CN 201910151387A CN 109951229 B CN109951229 B CN 109951229B
Authority
CN
China
Prior art keywords
point
many
power
ipt
energy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910151387.3A
Other languages
Chinese (zh)
Other versions
CN109951229A (en
Inventor
马帅
张凡
赵雨薇
李世银
杜淳
贺阳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China University of Mining and Technology CUMT
Original Assignee
China University of Mining and Technology CUMT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China University of Mining and Technology CUMT filed Critical China University of Mining and Technology CUMT
Priority to CN201910151387.3A priority Critical patent/CN109951229B/en
Publication of CN109951229A publication Critical patent/CN109951229A/en
Application granted granted Critical
Publication of CN109951229B publication Critical patent/CN109951229B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Abstract

The embodiment of the application discloses a method for jointly transmitting information and energy in a visible light communication system, which comprises the steps of establishing a point-to-point S L IPT V L C system, converting a point-to-point transmission signal into visible light through a light emitting diode by a point-to-point transmitting end and transmitting the visible light to a point-to-point receiving end, and carrying out point-to-point information receiving on the visible light through a photodiode or carrying out point-to-point energy collection through a solar cell panel by the point-to-point receiving end.

Description

Method for jointly transmitting information and energy in visible light communication system
Technical Field
The present application relates to the field of visible light communication, and in particular, to a method for information and energy co-transmission (S L IPT) in a visible light communication (V L C) system.
Background
The explosive increase of wireless devices and the increasing demand for high-speed data services put great pressure on conventional wireless Communication networks, including but not limited to radio frequency spectrum (RF) crisis and rapid depletion of batteries, to solve this problem, the technology of visible light Communication (V L C) system with information and energy co-transmission (S L IPT) has become a promising technology for indoor wireless networks with its huge unlicensed spectrum, no electromagnetic interference, good intrinsic safety, etc. from the application point of view, the V L C system, i.e. S L V5C system, which employs S L0 IPT technology, has the advantage of providing illumination, information transmission and energy collection simultaneously, and more particularly the transmitting end of the S L V L C system employs a low-cost light emitting diode (IoT) V L V5C system, which may operate in coordination with a variety of light emitting diodes (edt) for light collection under the Internet shopping environment, light receiving station, Internet access to light receiving terminals (e.g. Internet access, etc. the receiving end of light receiving terminals of light diodes (edv) may operate under the light diodes 36L, IPT 3C) for receiving the light receiving station.
In a first aspect, a solar panel is used for synchronous information reception and energy collection, and an optical wireless communication system is designed that provides a direct current model and an alternating current model of the solar panel, and an energy harvesting V L C system under different lighting conditions is proposed using a DC-offset, field-of-view (FOV) and energy harvesting time, and an S L IPT strategy is proposed to analyze the balance between the collected energy and quality of service (QoS).
Although the signal processing of S L IPT in the radio frequency communication system is widely analyzed, the result cannot be directly applied to the S L IPT V L C system due to its obvious characteristics, one of the main limiting factors is that the average optical power and the peak optical power of the V L C system must guarantee actual illumination at reasonable energy consumption, furthermore, the signal of the V L C system is a non-negative real signal through intensity modulation and direct detection modulation techniques, the capacity realization distribution of the V L C channel is discrete on a limited set of points, while the real capacity is not a closed expression, furthermore, the throughput performance of the V L C system cannot be accurately evaluated by the classical radio frequency Shannon (Shannon) capacity with gaussian input distribution, therefore, the prior art adopts the lower bound of the V L C channel capacity considering only the constraint of the average optical power, and in general, the research on the S L IPT V L C system is well discussed, and three key performance indexes, namely illumination, information transmission and collection, and energy collection, cannot be analyzed at the same time.
Reference documents:
[1]“Silicon PIN photodiode SFH 206K,” http://pdf1.alldatasheetcn.com/datasheet-pdf/view/45619/SIEMENS/SFH206K.html.
[2]“Luxeontx extreme efficacy and best performance,” http://www.mouser.com/ds/2/602/DS133-542348.pdf.
[3]Q.Gao,C.Gong,andZ.Xu,“Joint transceiver and offset design forvisible light communications with input-dependent shot noise,”IEEETrans.Wireless Commun.,vol.16,no.5,pp.2736–2747,May 2017.
[4]S.Yao,X.Zhang,H.Qian,and X.Luo,“Joint dimming and datatransmission optimization for multi-user visible light communication system,”IEEE Access,vol.5,pp.5455–5462,2017.
[5]K.Ying,H.Qian,R.J.Baxley,and G.T.Zhou,“MIMO transceiver design indynamic-range-limited VLC systems,”IEEE Photon.Technol.Lett.,vol.28,no.22,pp.2593–2596,Nov. 2016.
[6]T.Fath and H.Haas,“Performance comparison of mimo techniques foroptical wireless communications in indoor environments,”IEEE Trans.Commun.,vol.61,no.2,pp.733–742,Feb.2013.
[7]T.Q.Wang,Y.A.Sekercioglu,and J.Armstrong,“Analysis of an opticalwireless receiver using a hemispherical lens with application in mimo visiblelight communications,”J.Lightw.Technol.,vol.31, no.11,pp.1744–1754,Jun.2013.
[8]K.Ying,H.Qian,R.J.Baxley,and S.Yao,“Joint optimization of precoderand equalizer in MIMO VLC systems,”IEEE J.Sel.Areas Commun.,vol.33,no.9,pp.1949–1958,Sep.2015.
[9]J.Kahn and J.Barry,“Wireless infrared communications,”Proc.IEEE,vol.85,no.2,pp. 265–298,Feb.1997.
[10]S.Ma,R.Yang,H.Li,Z.-L.Dong,H.Gu,and S.Li,“Achievable rate withclosed-form for SISO channel and broadcast channel in visible lightcommunication networks,”J.Lightw.Technol.,vol. 35,no.14,pp.2778–2787,Jul.2017.
[11]Z.Wang,D.Tsonev,S.Videv,and H.Haas,“Towards self-powered solarpanel receiver for optical wireless communication,”in Proc.IEEEInt.Conf.Commun.(ICC),pp.3348–3353,Jun.2014.
[12]J.M.Palmer,“Radiometry and Photometry FAQ.(2003),” https://employeepages.scad.edu/kwitte/documents/Photometry FAQ.PDF.
[13]S.Ma,T.Zhang,S.Lu,H.Li,Z.Wu,and S.Li,“Energy efficiency of SISOand MISO in visible light communication systems,”J.Lightw.Technol.,vol.36,no.12,pp.2499–2509,Jun.2018.
[14]Y.-C.Kuo,T.-J.Liang,and J.-F.Chen,“Novel maximum-power-pointtracking controller for photovoltaic energy conversion system,”vol.48,pp.594–601,Jul.2001.
[15]C.Hua and C.Shen,“Study of maximum power tracking techniques andcontrol of DC/DC converters for photovoltaic power system,”in Proc.29thAnnu.IEEE PESC,vol.1,pp.86–93,May 1998.
[16]D.-Y.Lee,H.-J.Noh,D.-S.Hyun,and I.Choy,“An improved MPPTconverter using current compensation method for small scaled pv-applications,”in Proc.18th Annu.IEEE APEC,vol.1,pp. 540–545,Feb.2003.
[17]D.Dondi,A.Bertacchini,D.Brunelli,L.Larcher,and L.Benini,“Modelingand optimization of a solar energy harvester system for self-powered wirelesssensor networks,”IEEE Trans.Ind.Electron., vol.55,no.7,pp.2759–2766,Jul.2008.
[18]F.Adamo,F.Attivissimo,A.D.Nisio,and M.Spadavecchia,“Characterization and testing of a tool for photovoltaic panel modeling,”IEEETrans.Instrum.Meas.,vol.60,no.5,pp.1613–1622,May 2011.
[19]A.Nasiri,S.A.Zabalawi,and G.Mandic,“Indoor power harvesting usingphotovoltaic cells for low-power applications,”IEEE Trans.Ind.Electron.,vol.56,no.11,pp.4502–4509,Nov.2009.
[20]J.Fakidis,S.Videv,S.Kucera,H.Claussen,and H.Haas,“Indoor opticalwireless power transfer to small cells at nighttime,”J.Lightw.Technol.,vol.34,no.13,pp.3236–3258,Jul.2016.
[21]D.Sera,R.Teodorescu,and P.Rodriguez,“PV panel model based ondatasheet values,”in IEEE Int.Symp.Ind.Electron.,pp.2392–2396,Jun.2007.
[22]S.A.K.W.De Soto and W.A.Beckman,“Improvement and validation of amodel for photovoltaic array performance,”Sol.Energy,vol.80,no.1,pp.78–88,Jan.2006.
[23]Z.Q.Luo,W.K.Ma,A.M.C.So,Y.Ye,and S.Zhang,“Semidefinite relaxationof quadratic optimization problems,”IEEE Signal Process.Mag.,vol.27,no.3,pp.20–34,May 2010.
[24]“1.5MHz,30A high-efficiency,LED driver with rapid LED currentpulsing,” http://pdf.dzsc.com/MAX/Maxim MAX16818ATI+30010.pdf.
[25]D.Dondi,D.Brunelli,L.Benini,P.Pavan,A.Bertacchini,and L.Larcher,“Photovoltaic cell modeling for solar energy powered sensor networks,”inAdvances in Sensors and Interface 2007.IWASI 2007.2nd International Workshopon,pp.1–6,Jun.2007.
[26]“BQ25504ultra low-power boost converter with battery managementfor energy harvester applications,”http://101.96.10.45/www.ti.com/lit/ds/symlink/bq25504.pdf.
[27]“CY39C831ultra low voltage boost PMIC for solar/thermal energyharvesting,” http://www.cypress.com/file/216476/download.
disclosure of Invention
The application provides a method for jointly transmitting information and energy in a visible light communication system, which aims to solve the problem that the prior art cannot simultaneously analyze three key performance indexes of an S L IPT V L C system, namely illumination, information transmission and energy collection.
In a first aspect, the present application provides a method for information and energy co-transmission in a visible light communication system, including:
step 1, establishing a visible light communication S L IPT V L C system for transmitting point-to-point information and energy together, wherein the point-to-point S L IPT V L C system comprises a point-to-point transmitting end and a point-to-point receiving end, and the point-to-point transmitting end converts a point-to-point transmission signal into visible light through a light emitting diode and sends the visible light to the point-to-point receiving end;
the point-to-point receiving end receives the point-to-point information of the visible light through a photodiode, or collects the point-to-point energy of the visible light through a solar cell panel;
the step 1 comprises the following steps:
step 1.1: calculating the point-to-point transmission signal x:
let s denote successive data symbols and
Figure GDA0002524286110000031
random real numbers of (a);
s has a peak amplitude of-A ≦ s ≦ A, and a variance of s
Figure GDA0002524286110000032
Wherein A is more than 0 and more than 0;
the point-to-point transmission signal x is:
Figure GDA0002524286110000033
where g is the power gain of the power amplifier, IDIs a direct current bias;
the power gain g of the power amplifier should satisfy:
Figure GDA0002524286110000034
average electric power of the point-to-point transmission signal x
Figure GDA0002524286110000035
Comprises the following steps:
Figure GDA0002524286110000036
luminous flux phi of the light emitting diodeOTComprises the following steps:
ΦOT＝354.286x+27, (4)
step 1.2, analyzing the illumination control of the point-to-point S L IPT V L C system according to the point-to-point transmission signal x:
illumination control of the point-to-point S L IPT V L C, namely illumination level tau and average light power of the point-to-point S L IPT V L C system
Figure GDA0002524286110000037
And maximum optical power PTThe relationship between:
Figure GDA0002524286110000038
0＜τ≤1；
average optical power of the point-to-point S L IPT V L C system according to equation (1)
Figure GDA0002524286110000041
Is biased by said direct currentDDetermine, i.e. that
Figure GDA0002524286110000042
Figure GDA0002524286110000043
The power gain g of the power amplifier satisfies:
Figure GDA0002524286110000044
wherein, IHFor maximum allowable current of light-emitting diodes, i.e.
Figure GDA0002524286110000045
Step 1.3.1: analyzing a point-to-point information receiving module of the point-to-point receiving end:
l oS link gain h between the light emitting diode and the photodiode1Comprises the following steps:
Figure GDA0002524286110000046
wherein the content of the first and second substances,
Figure GDA0002524286110000047
is a Lambert index,. phi1/2Is the half power half angle of the LED, d1Is the distance between the light emitting diode and the photodiode, APDDenotes the detector area of the photodiode, phi1The exit angle of the led to the photodiode,
Figure GDA00025242861100000410
is the angle of incidence of the LED to the photodiode, Ψ1Represents the half field angle of the photodiode;
the received signal y is:
y＝h1x+z， (9)
wherein z represents a variance σ2Zero mean gaussian noise of (d);
achievable rate RSISOComprises the following steps:
Figure GDA0002524286110000048
where α and gamma are parameters determined by A and sigma2Variance of zero mean gaussian noise;
achievable rate RSISOLower boundary of (1)
Figure GDA0002524286110000049
Obtained by the following distribution:
Figure GDA0002524286110000051
where α and γ are solutions of the following equations:
T(A)-T(-A)＝e1+α, (12a)
β(eA(β-γA)-e-A(β+γA)-e1+α)＝0, (12b)
eA(β-γA)((β-2γA)e-2Aβ-β-2γA) +(β2+2γ)e1+α＝4γ2e1+α, (12c)
wherein the content of the first and second substances,
Figure GDA0002524286110000052
step 1.3.2: analyzing a point-to-point energy collection module of the point-to-point receiving end:
channel gain h between light emitting diode and solar panel2：
Figure GDA0002524286110000053
Wherein A issRepresenting the detector area of the solar panel, d2Is the distance between the light emitting diode and the solar cell panel, phi2The exit angle of the leds to the solar panel,
Figure GDA0002524286110000054
is the incident angle of the LED to the solar panel, psi2Representing a half field angle of the solar panel;
luminous flux phi received by solar cell panelOR：
ΦOR＝h2ΦOT(14)
The received solar panel illumination E is:
Figure GDA0002524286110000055
wherein the content of the first and second substances,
Figure GDA0002524286110000056
is the relative spectral energy density of the light emitting diode, λ is the wavelength of light,
Figure GDA0002524286110000057
Figure GDA0002524286110000058
as a function of standard luminosity, EaIndicating the illuminance (W/m) of ambient light2)；
Output voltage U and open circuit voltage U by using partial open circuit voltage FOCV method and maximum power point MPP tracking methodocThe approximation is:
U＝ηUoc, (16)
wherein η is a coefficient, η∈ [0.71,0.78 ];
according to the MPP tracking method, the output current I of the solar cell panel is as follows:
Figure GDA0002524286110000061
wherein, IphIs a photo-generated current, Is0To saturate dark current, c1Is the solar panel coefficient, RsIs an equivalent series resistance, RshIs equivalent to parallel resistance, and solar cell panel coefficient
Figure GDA0002524286110000062
qeIs an electronic charge, k is the Boltzmann constant, JfIs the ideal factor of a diode, TaIs ambient temperature;
according to the equivalent circuit model, the output current I of the solar cell panel is approximately as follows:
Figure GDA0002524286110000063
when the circuit is open, namely the output current I of the solar cell panel is equal to 0, there are:
Figure GDA0002524286110000064
Figure GDA0002524286110000065
the photo-generated current IphWith the received solar panel illuminance E and the ambient temperature TaIn proportion:
Figure GDA0002524286110000066
wherein, Isc,stcIs short-circuit current in standard test condition, i.e. illuminance E in standard test conditionstc＝1000W/m2Ambient temperature T under Standard test conditionsa,stcShort-circuit current at 298K, αstcIs the short circuit current temperature coefficient;
the open circuit voltage U obtained by substituting formula (20) for formula (19b)ocIs composed of
Figure GDA0002524286110000067
Wherein the content of the first and second substances,
Figure GDA0002524286110000068
the saturated dark current I in formula (17)s0Dependent on the ambient temperature Ta：
Figure GDA0002524286110000069
Wherein, Is0,stcIs dark saturation current under standard test condition, coefficient
Figure GDA00025242861100000610
Eg,stc1.12eV is the band gap of the material in the standard test state;
when the circuit is short-circuited, i.e. the output voltage U equals 0, there is
Iph＝Isc， (23)
Wherein, IscIs a short circuit current;
according to the formula (18), the dark saturation current I in the standard test state can be obtaineds0,stc：
Figure GDA0002524286110000071
Wherein, Uoc,stcIs the open circuit voltage under the standard test state;
obtaining the output power P of the solar cell panelsolarAs a function of the power gain g for the power amplifier:
Figure GDA0002524286110000072
Figure GDA0002524286110000073
Figure GDA0002524286110000074
Figure GDA0002524286110000075
wherein the content of the first and second substances,
Figure GDA0002524286110000076
Figure GDA0002524286110000077
Figure GDA0002524286110000078
energy Q collected by the solar panel at the time delta tsolar(Δt)：
Qsolar(Δt)＝PsolarΔt (26)
Step 1.4, calculating an illumination-speed-energy area of the point-to-point S L IPT V L C system:
power gain g of the power amplifier and the DC offset IDSatisfies the following conditions:
Figure GDA0002524286110000079
wherein the content of the first and second substances,
Figure GDA00025242861100000710
is the maximum total transmission power;
by combining formula (2), formula (7) and formula (27), it is possible to obtain:
Figure GDA0002524286110000081
introducing illumination-information-energy region CI-R-EThe illumination-information-energy region CI-R-EThe illumination level tau and the achievable rate R under the constraint condition of given emission powerSISOAnd collected energy QsolarComposition of said illumination-information-energy region CI-R-EThe expression of (a) is:
Figure GDA0002524286110000082
wherein the content of the first and second substances,
Figure GDA0002524286110000083
with reference to the first aspect, in an implementation manner, the step 2 includes:
when N LEDs send data and energy to K users at the same time, order skRepresenting the N LEDs to the kData symbols of users, wherek|≤Ak，
Figure GDA0002524286110000084
AkAndkrespectively the amplitude peak value and the variance of the kth data symbol;
the many-to-many transmission signal x is:
Figure GDA0002524286110000085
wherein K is the total number of users,
Figure GDA0002524286110000086
for data symbols skBeamforming vector of 1NA vector in which all the elements of dimension N × 1 are 1;
average electric power of the many-to-many transmission signal x
Figure GDA0002524286110000087
Comprises the following steps:
Figure GDA0002524286110000088
wherein N is the number of light emitting diodes;
the beamforming vector gkSatisfies the following conditions:
Figure GDA0002524286110000089
wherein e isnIs a base vector;
luminous flux phi of nth LEDn,OTComprises the following steps:
Figure GDA0002524286110000091
wherein, gk,nIs the power gain between the nth led and the kth user.
With reference to the first aspect, in an implementation manner, step 2, establishing a many-to-many S L IPT V L C network according to the point-to-point S L IPT V L C system, where the many-to-many S L IPT V L C network includes a many-to-many transmitting end and a many-to-many receiving end, and the many-to-many transmitting end converts many-to-many transmission signals into visible light through two or more light emitting diodes and sends the visible light to the many-to-many receiving end;
the many-to-many receiving end receives many-to-many information of the visible light through more than two photodiodes or collects many-to-many energy of the visible light through more than two solar panels.
The step 2 comprises a step 2.1 of analyzing the illumination control of the many-to-many S L IPT V L C network according to the many-to-many transmission signal x of the many-to-many S L IPT V L C network:
the beamforming vector gkSatisfies the following conditions:
Figure GDA0002524286110000092
wherein, IHMaximum allowable current for the light emitting diode;
average optical power of many-to-many S L IPT V L C network
Figure GDA0002524286110000093
Comprises the following steps:
Figure GDA0002524286110000094
illumination control of the many-to-many S L IPT V L C network, i.e. the illumination level τ, average light power of the many-to-many S L IPT V L C network
Figure GDA0002524286110000095
And said maximum optical power PTThe relationship between:
Figure GDA0002524286110000096
with reference to the first aspect, in an implementation manner, the step 2 includes: step 2.2: analyzing a many-to-many information receiving module of the many-to-many receiving end:
signal y received at the kth user1，kComprises the following steps:
Figure GDA0002524286110000097
wherein, giBeamforming vector, s, for the ith useriFor data symbols sent to the ith user, h1,k,nFor channel gain from the nth LED to the kth user photodiode, h1,k＝[h1,k,1,...,h1,k,N]TRepresenting the channel vector between the LED and the user k, zkIs zero mean and variance is σ2Additive gaussian noise of (a);
reachable rate of kth user
Figure GDA0002524286110000101
Comprises the following steps:
Figure GDA0002524286110000102
wherein the parameter αiAnd gammaiFrom AiAndidetermination of AiAndirespectively the amplitude peak value and the variance of the ith data symbol;
the lower bound of equation (38) is obtained by the following distribution:
Figure GDA0002524286110000103
wherein, αi，βiAnd gammaiIs a solution of the following equation:
Figure GDA0002524286110000104
Figure GDA0002524286110000105
Figure GDA0002524286110000106
with reference to the first aspect, in an implementation manner, the step 2 includes: step 2.3: analyzing a many-to-many energy collection module of the many-to-many receiving end:
illuminance E received at the k-th userkComprises the following steps:
Figure GDA0002524286110000107
wherein h is2,k,nRepresenting the channel gain from the nth led to the kth customer solar panel,
Figure GDA0002524286110000108
Figure GDA0002524286110000109
is the relative spectral energy density of the light emitting diode, λ is the wavelength of light,
Figure GDA00025242861100001010
Figure GDA00025242861100001011
as a function of standard luminosity, EaIndicating the illuminance (W/m) of ambient light2)，Φn,OTLuminous flux of the nth light emitting diode;
at the kth user, the solar panel outputs a voltage UkComprises the following steps:
Uk＝ηUk,oc, (42)
wherein, Uk,ocIs the open circuit voltage of the solar panel at the kth user;
Figure GDA00025242861100001012
wherein the content of the first and second substances,
Figure GDA0002524286110000111
Ik,sc,stcfor short circuit current in the kth solar panel standard test condition, αk,stcShort-circuit current temperature coefficient for kth solar panel, Ek,stcFor the illumination received by the kth user under standard test conditions, Ik,s0Saturated dark current for the kth user;
output current I of kth solar cell panelk：
Figure GDA0002524286110000112
Average output power of solar panel of kth user
Figure GDA0002524286110000113
Comprises the following steps:
Figure GDA0002524286110000119
Figure GDA0002524286110000114
Figure GDA0002524286110000115
wherein the content of the first and second substances,
Figure GDA0002524286110000116
k is the total number of users, h2,k＝[h2,k,1,...,h2,k,N]TRepresenting the channel vector between the led and the kth solar panel,
Figure GDA0002524286110000117
Figure GDA0002524286110000118
the invention analyzes the signal flow of a point-to-point S L IPT V L C system to describe three main performance indexes of illumination, information transmission and energy collection, and researches a signal processing method on a point-to-point transmitting end.Next, the invention estimates the average illumination level based on illumination control, also deduces the relation between the output voltage and current of a Power Amplifier (PA) of the point-to-point transmitting end and a solar panel, and quantifies the energy collected by the point-to-point receiving end, then, the invention obtains an illumination-rate-energy area of the point-to-point S L0 IPT V L C system, realizes the common transmission of the information and the energy in a point-to-point S L IPT V L C system, finally, researches the downlink broadcast transmission of a multi-to-multi S L IPT V4C network, and deduces the common transmission of the illumination, the information transmission and the energy collection of the multi-to-multi S L IPT V L C network with an explicit expression, and realizes the common transmission of the multi-to-multi-S L IPT V L C network.
Drawings
FIG. 1 is a schematic flow chart of a method according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a point-to-point transmitting end in a point-to-point S L IPT V L C system according to an embodiment of the present application;
fig. 3 is a schematic diagram of a receiving end in a conventional visible light communication system;
fig. 4 is a schematic diagram of a point-to-point receiving end in a point-to-point S L IPT V L C system according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a basic equivalent circuit of a solar panel according to an embodiment of the present disclosure;
fig. 6 is a schematic diagram of a downlink unicast transmission of a many-to-many S L IPT V L C network according to an embodiment of the present application;
FIG. 7a shows the energy Q collected by the solar panel according to the embodiment of the present applicationsolarAnd lower achievable rate limit
Figure GDA0002524286110000121
Following DC offset IDA graph of the variation;
FIG. 7b isEnergy Q collected by solar cell panelsolarAnd lower achievable rate limit
Figure GDA0002524286110000122
A curve diagram varying with the power gain g of the power amplifier;
FIG. 8a shows an embodiment of the present application
Figure GDA00025242861100001211
And total transmission power in three cases of 1.5bits/sec/Hz
Figure GDA0002524286110000123
The curve diagram of the change with the number N of the light-emitting diodes;
FIG. 8b shows the electric power of the embodiment of the present application
Figure GDA0002524286110000124
Rate dependent threshold
Figure GDA0002524286110000125
A graph of the variation;
FIG. 8c shows an embodiment of the present application
Figure GDA0002524286110000126
And 6bits/sec/Hz electric power
Figure GDA0002524286110000127
Along with energy collection threshold
Figure GDA0002524286110000128
Schematic diagram of the variation curve of (1);
FIG. 9 shows a maximum rate lower bound of an embodiment of the present application
Figure GDA0002524286110000129
Energy dependent threshold
Figure GDA00025242861100001212
The curve of the change is shown schematically.
Detailed Description
The invention discloses a method for jointly transmitting information and energy in a visible light communication system.
Referring to fig. 1, a schematic flowchart of a method for jointly transmitting information and energy in a visible light communication system provided in this embodiment is shown, including the following steps:
step 1, establishing a visible light communication S L IPT V L C system for transmitting point-to-point information and energy together, wherein the point-to-point S L IPT V L C system comprises a point-to-point transmitting end and a point-to-point receiving end, and the point-to-point transmitting end converts a point-to-point transmission signal into visible light through a light emitting diode and sends the visible light to the point-to-point receiving end;
the point-to-point receiving end receives point-to-point information of the visible light through a photodiode, or collects point-to-point energy of the visible light through a solar cell panel; i.e. the point-to-point transmitting end has only one light emitting diode, the point-to-point transmission signal can be sent to a point-to-point receiving end in a time period.
Step 2, analyzing a many-to-many S L IPT V L C network according to a point-to-point S L IPT V L C system, wherein the many-to-many S L IPT V L C network comprises a many-to-many transmitting end and a many-to-many receiving end, and the many-to-many transmitting end converts many-to-many transmission signals into visible light through more than two light emitting diodes and sends the visible light to the many-to-many receiving end;
the many-to-many receiving end receives many-to-many information through more than two photodiodes or collects many-to-many energy through more than two solar panels. Namely, the many-to-many transmitting terminal is provided with a plurality of light emitting diodes, and can send many-to-many transmission signals to the many-to-many receiving terminal.
Specifically, the invention studies a point-to-point S L IPT V L C system with a light emitting diode at the transmission end, as shown in FIG. 2. at the point-to-point transmission end, the signal is modulated into a digital signal by a modulator, then the digital signal is converted into an analog form by a digital-to-analog converter, amplified by a power amplifier, and then the signal passes through a bias device after passing through the power amplifier and is added with direct current of a light emitting diode source.
Step 1 comprises step 1.1: a point-to-point transmission signal x is calculated. As shown in FIG. 2, let s denote consecutive data symbols and
Figure GDA00025242861100001210
random real numbers of (2). Further, given A > 0 and > 0, the peak amplitude and variance are-A ≦ s ≦ A and
Figure GDA0002524286110000131
after passing through the power amplifier, the point-to-point transmission signal x is:
Figure GDA0002524286110000132
where g is the power gain of the power amplifier, IDIs a dc bias. Since the point-to-point transmission signal x is non-negative, i.e.
Figure GDA0002524286110000133
So g should satisfy:
Figure GDA0002524286110000134
the average electrical power of the point-to-point transmission signal x is:
Figure GDA0002524286110000135
in addition, the luminous flux Φ of the light-emitting diodeOTIs [2 ]]：ΦOT＝354.286x+27, (4)
The step 1 comprises the step 1.2 of analyzing the illumination control of the point-to-point S L IPT V L C system according to the point-to-point transmission signal x, wherein the illumination control is one of the basic requirements of the V L C system and meets the actual illumination requirement by adjusting the average light power, let tau denote the illumination level,
Figure GDA0002524286110000136
representing the average optical power. The values of tau are,
Figure GDA0002524286110000137
and PTThe relationship between:
Figure GDA0002524286110000138
wherein P isTIs the maximum optical power, therefore 0 < tau.ltoreq.1. Further, according to the formula (1), the average optical power
Figure GDA0002524286110000139
Biased by DCDDetermining, namely:
Figure GDA00025242861100001310
thus, the control of the light level can be by IDIs adjusted to achieve, i.e.
Figure GDA00025242861100001311
Considering eye safety and maximum allowable current of LED 3]-[5]Is provided with IHThe maximum allowable current for the led, that is,
Figure GDA00025242861100001312
therefore, the power gain g of the power amplifier satisfies:
Figure GDA00025242861100001313
thus, the point-to-point transmitting end can control the power gain g to meet lighting and safety requirements. The signal emitted by the light emitting diode is in the form of light waves and is uniformly distributed in space. The light waves are transmitted to the point-to-point receiving end through the optical channel, and the light waves can be captured by a photodiode or a solar panel at the point-to-point receiving end. As shown in fig. 3, the receiving end in the prior art uses a photodiode or a solar panel to receive signals, and uses a power splitting technique to obtain separate signals, one part is used for information decoding, and the other part is used for energy collection. However, the photodiode and the solar panel have respective advantages in different tasks, and thus the present invention adopts a combined structure, i.e., one photodiode for information reception and one solar panel for energy collection, as shown in fig. 4.
Step 1 includes step 1.3.1 of analyzing a point-to-point information receiving module of a point-to-point receiving end, where an optical channel is between the light emitting diode and the photodiode and is dominated by a direct line-of-sight (L oS) link, and the gain of the reflected link is negligible [6 ]]–[8]. Let h1Indicating L oS link gain between light emitting diode and photodiode [9]：
Figure GDA0002524286110000141
Wherein
Figure GDA0002524286110000142
Is a Lambert index; phi is a1/2Is the half power half angle of the light emitting diode; d1Is the distance between the light emitting diode and the photodiode; a. thePDRepresents the detector area of the photodiode; phi is a1And
Figure GDA0002524286110000147
the exit angle and the incident angle from the light emitting diode to the photodiode, respectively; Ψ1Represents half of the field-of-view (FOV) of the photodiode, i.e., the half field angle of the photodiode.
In the information receiving module, the photodiode converts light emitted from the light emitting diode into an analog signal, and then the analog-to-digital converter samples the analog signal into a digital form. It is assumed that the non-linearity of the light emitting diode is mitigated by using pre-distortion and post-distortion techniques. In general, the received signal y can be expressed as:
y＝h1x+z， (9)
wherein z represents a variance σ2Zero mean gaussian noise.
The channel capacity of the V L C channel is unknown and the present invention employs [10 ]]In a practical mannerRate expressions for analysis of S L IPT V L C System RSISORepresenting the achievable rate:
Figure GDA0002524286110000143
where α and gamma are determined by A and R is the achievable rateSISOR of (A) to (B)SISOThe lower bound is obtained by the following distribution [10 ]]：
Figure GDA0002524286110000144
Where α and γ are solutions of the following equations:
T(A)-T(-A)＝e1+α, (12a)
β(eA(β-γA)-e-A(β+γA)-e1+α)＝0, (12b)
eA(β-γA)((β-2γA)e-2Aβ-β-2γA) +(β2+2γ)e1+α＝4γ2e1+α, (12c)
wherein the content of the first and second substances,
Figure GDA0002524286110000145
the invention uses
Figure GDA0002524286110000146
To represent R in the formula (10)SISOThe lower bound of (c).
Step 1 comprises step 1.3.2: analyzing a point-to-point energy collection module of a point-to-point receiving end: in the energy collection module, light emitted by the light emitting diode and ambient light are converted into analog electric signals by the solar panel, and the analog electric signals are filtered by the rectifier and stored in the battery. In the same way, let h2Representing the channel gain between the leds and the solar panel:
Figure GDA0002524286110000151
wherein A issRepresenting the detector area of the solar panel, d2Is the distance between the light emitting diode and the solar cell panel, phi2The exit angle of the leds to the solar panel,
Figure GDA0002524286110000152
is the incident angle of the LED to the solar panel, psi2Representing the half field angle of the solar panel.
Luminous flux phi received by solar cell panelORFrom [11 ]]The following can be obtained:
ΦOR＝h2ΦOT(14)
since the background light and the led light are usually incoherent, the received solar panel illumination is:
Figure GDA0002524286110000153
wherein
Figure GDA0002524286110000154
Relative spectral energy density for light emitting diodes [2 ]]And lambda is the wavelength of the light wave,
Figure GDA0002524286110000155
Figure GDA0002524286110000156
as a function of standard luminosity [12 ]]；EaIndicating the illuminance (W/m) of ambient light2)。
The basic equivalent circuit of a solar panel is shown in fig. 5. Since the solar panel generally has a certain nonlinear volt-ampere characteristic, a Maximum Power Point (MPP) tracking technique is generally used to analyze the output power. There are multiple MPP tracking methods [13]-[16]The present invention employs a fractional open-circuit voltage (FOCV) method that is widely used in small solar panel systems [15 ]]，[16]. Output voltage U and open circuit voltage U using FOCV method and MPP tracking methodocCan be approximated as [16 ]]：
U＝ηUoc, (16)
η∈ [0.71,0.78] is a coefficient, according to the equivalent circuit model, the output current I of the solar panel is [17], [18 ]:
Figure GDA0002524286110000157
wherein, IphIs a photo-generated current, Is0To saturate dark current, c1Is the solar panel coefficient, RsIs an equivalent series resistance, RshIs equivalent to parallel resistance, and solar cell panel coefficient
Figure GDA0002524286110000158
qeIs an electronic charge, k is the Boltzmann constant, JfIs the ideal factor of a diode, TaIs ambient temperature.
Under indoor conditions, the output current I and the series resistance RsValues of (d) are typically at milliampere and milliohm levels, respectively [19 ]]、[20]. Output voltage U is not more than 10 volts, and parallel resistor RshNot less than 1 kiloohm [19 ]]、[20]. Thus, in formula (17)
Figure GDA0002524286110000161
The term can be ignored, and Rsh＞＞RsSo the output current I can be approximated as:
Figure GDA0002524286110000162
when the circuit is open, i.e. I is 0, there are:
Figure GDA0002524286110000163
Figure GDA0002524286110000164
in addition, the photo-generated current IphWith illuminance E and ambient temperature TaProportional ratio [17]、[22]：
Figure GDA0002524286110000165
Wherein Isc,stcIs in a Standard Test Condition (STC), i.e., the illuminance is Estc＝1000W/m2(ii) a Ambient temperature Ta,stcShort-circuit current at 298K, αstcIs the short circuit current temperature coefficient.
Open circuit voltage U obtained by substituting formula (20) for formula (19b)ocComprises the following steps:
Figure GDA0002524286110000166
wherein
Figure GDA0002524286110000167
The saturated dark current in equation (17) depends on the ambient temperature Ta[17]，[22]：
Figure GDA0002524286110000168
Wherein Is0,stcFor dark saturation current in the standard test state,
Figure GDA0002524286110000169
Eg,stc＝1.12eV。
when the circuit is short-circuited, i.e. U is 0, there are:
Iph＝Isc， (23)
according to formula (18), can be obtained Is0,stc：
Figure GDA00025242861100001610
Wherein, Uoc,stcIs the open circuit voltage under standard test conditions.
And finally, obtaining a function of the output power of the solar panel as the power gain g of the power amplifier:
Figure GDA0002524286110000171
Figure GDA0002524286110000172
Figure GDA0002524286110000173
Figure GDA0002524286110000174
wherein
Figure GDA0002524286110000175
The approximation of the formula (25c) is that
Figure GDA0002524286110000176
And a first order taylor expansion:
Figure GDA0002524286110000177
Figure GDA0002524286110000178
Figure GDA0002524286110000179
therefore, the invention can obtain the energy collected by the solar panel at the time delta t:
Qsolar(Δt)＝PsolarΔt (26)
step 1 includes the step 1.4 of calculating the illumination-rate-energy area of the point-to-point S L IPT V L C system:
the present invention has thus far obtained explicit expressions of the rate and harvested energy as a function of the power gain g of the power amplifier, given in equations (10) and (25), respectively, under practical circuit considerations, the electrical power of the V L C signal is also limited. Thus, the power gains g and I of the power amplifierDSatisfies the following conditions:
Figure GDA00025242861100001710
wherein the content of the first and second substances,
Figure GDA00025242861100001711
is the maximum total transmission power.
By combining formula (2), formula (7) and formula (27), it is possible to obtain:
Figure GDA00025242861100001712
finally, the invention introduces an illumination-information-energy region bounded by an illumination level τ and an achievable rate R for a given emission powerSISOAnd collected energy QsolarComposition, illumination-information-energy region CI-R-EThe expression of (a) is:
Figure GDA0002524286110000181
wherein the content of the first and second substances,
Figure GDA0002524286110000182
in step 2, the many-to-many transmitting terminal is configured with a plurality of light emitting diodes, and can transmit many-to-many transmission signals to a many-to-many receiving terminal, wherein each receiving module in the many-to-many receiving terminal represents one user. As shown in fig. 6, N leds transmit data and power to K users simultaneously. Let skData symbols representing N LEDs to a kth user, where | sk|≤Ak，
Figure GDA0002524286110000183
AkAndkrespectively, the amplitude peak and the variance of the kth data symbol. Order to
Figure GDA0002524286110000184
Representing a data symbol skThe many-to-many transmission signal x is:
Figure GDA0002524286110000185
wherein K is the total number of users, gkFor data symbols skBeamforming vector of 1NA vector with N × 1 dimensional elements all being 1.
The average electrical power of the many-to-many transmission signal x is:
Figure GDA0002524286110000186
wherein N is the number of light emitting diodes. Ensuring non-negativity of many-to-many transmitted signals x, beamforming vectors gkSatisfies the following conditions:
Figure GDA0002524286110000187
wherein e isnIs a base vector; in addition, the luminous flux of the nth light emitting diode is:
Figure GDA0002524286110000188
wherein, gk,nIs the power gain between the nth led and the kth user.
Step 2 comprises the step 2.1 of analysing the illumination control of a many-to-many S L IPT V L C network from the many-to-many transmission signal x of the many-to-many S L IPT V L C network, assuming that the non-linearity of the LEDs can be reduced using pre-and post-distortion techniqueskSatisfies the following conditions:
Figure GDA0002524286110000191
wherein, IHFor maximum allowance of light-emitting diodesThe average optical power of a many-to-many S L IPT V L C network is:
Figure GDA0002524286110000192
illumination control of many-to-many S L IPT V L C networks, i.e. illumination level τ, average light power of many-to-many S L IPT V L C networks
Figure GDA0002524286110000193
And maximum optical power PTThe relationship between:
Figure GDA0002524286110000194
step 2 comprises step 2.2: analyzing a many-to-many information receiving module of a many-to-many receiving end:
similar to formula (8), let h1,k,nFor channel gain from the nth LED to the kth user photodiode, let h1,k＝[h1,k,1,...,h1,k,N]TRepresenting the channel vector between the led light source and user k, the signal y received at the kth user1,kComprises the following steps:
Figure GDA0002524286110000195
wherein, giBeamforming vector, s, for the ith useriFor data symbols sent to the ith user, zkIs zero mean and variance is σ2Additive gaussian noise.
According to [10 ]]Reachable rate of kth user
Figure GDA0002524286110000196
Comprises the following steps:
Figure GDA0002524286110000197
wherein the parameter αiAnd gammaiFrom AiAndidetermination of AiAndirespectively, the amplitude peak and the variance of the ith data symbol. The lower bound of formula (38) is obtained by the following distribution [10]：
Figure GDA0002524286110000198
Wherein, αi，βiAnd gammaiIs a solution of the following equation:
Figure GDA0002524286110000201
Figure GDA0002524286110000202
Figure GDA0002524286110000203
step 2 comprises step 2.3: analyzing a many-to-many energy collection module of a many-to-many receiving end:
similar to formula (13), let h2,k,nChannel gain of nth led to kth customer solar panel. At the kth user, the received illuminance EkComprises the following steps:
Figure GDA0002524286110000204
wherein the content of the first and second substances,
Figure GDA0002524286110000205
Figure GDA0002524286110000206
is the relative spectral energy density of the light emitting diode, λ is the wavelength of light,
Figure GDA0002524286110000207
Figure GDA0002524286110000208
as a function of standard luminosity, EaIndicating the illuminance (W/m) of ambient light2)，Φn,OTIs the luminous flux of the nth light emitting diode.
At the kth user, the solar panel outputs a voltage UkComprises the following steps:
Uk＝ηUk,oc, (42)
wherein, Uk,ocTo the kth user, the open circuit voltage of the solar panel, i.e.:
Figure GDA0002524286110000209
wherein
Figure GDA00025242861100002010
Ik,sc,stcFor short circuit current in the kth solar panel standard test condition, αk,stcShort-circuit current temperature coefficient for kth solar panel, Ek,stcFor the illumination received by the kth user under standard test conditions, Ik,s0Is the saturated dark current for the kth user.
Meanwhile, the output current I of the kth solar cell panelk：
Figure GDA00025242861100002011
Thus, the average output power of the solar panel of the kth user
Figure GDA00025242861100002012
Comprises the following steps:
Figure GDA0002524286110000211
Figure GDA0002524286110000212
Figure GDA0002524286110000213
wherein the content of the first and second substances,
Figure GDA0002524286110000214
h2,k＝[h2,k,1,...,h2,k,N]Trepresenting the channel vector between the led and the kth solar panel,
Figure GDA0002524286110000215
Figure GDA0002524286110000216
the invention discloses a method for solving a design problem of a many-to-many S L IPT V L C network based on a method for jointly transmitting information and energy in a visible light communication system, which comprises the following steps of 3, researching two typical S L IPT V L C system design problems, namely a total transmission power minimization problem and a minimum rate maximization problem, on the basis of analyzing a many-to-many S L IPT V L C network, wherein the step 3 comprises the step 3.1 of utilizing an explicit reachable rate expression (38) and an energy collection expression (45C) so as to minimize the total transmission power and simultaneously meet the rate requirement, the minimum energy collection requirement and an illumination control constraint, and mathematically, the total transmission power minimization problem of the many-to-many S L IPT V L C network can be expressed as:
Figure GDA0002524286110000217
Figure GDA0002524286110000218
Figure GDA0002524286110000219
Figure GDA00025242861100002110
NID＝τPT, (46e)
wherein r iskFor the speed requirement of the kth user, vkThe collected energy requirement for the kth user.
Substituting equation (46e) for equation (46d), the problem (46) can be equivalently restated as:
Figure GDA0002524286110000221
Figure GDA0002524286110000222
Figure GDA0002524286110000223
Figure GDA0002524286110000224
this is a non-convex problem due to the rate constraint (47b) and the energy harvesting constraint (47 c).
To solve the problem (47), the present invention first introduces the following new definition:
Figure GDA0002524286110000225
Figure GDA0002524286110000226
Figure GDA0002524286110000227
Figure GDA0002524286110000228
Figure GDA0002524286110000229
Figure GDA00025242861100002210
Figure GDA00025242861100002211
according to definition (48), the question (47) can be rewritten into the compact form:
Figure GDA00025242861100002212
Figure GDA00025242861100002213
Figure GDA00025242861100002214
Figure GDA00025242861100002215
wherein
Figure GDA00025242861100002216
To handle the non-convex constraints (49b) and (49c), the present invention employs SDR techniques. Specifically by using the following attributes:
Figure GDA00025242861100002217
and ignoring the non-convex rank constraint rank (g) 1, the problem (49) relaxes to:
Figure GDA0002524286110000231
Figure GDA0002524286110000232
Figure GDA0002524286110000233
Figure GDA0002524286110000234
Figure GDA00025242861100002323
definition of
Figure GDA0002524286110000235
Is the optimal solution of the problem (51) if
Figure GDA0002524286110000236
Obtaining (51) optimal beamforming vectors for the problem by eigenvalue decomposition
Figure GDA0002524286110000237
If it is
Figure GDA0002524286110000238
Randomizing Gauss Process [23 ]]For
Figure GDA0002524286110000239
Obtain a feasible solution to the problem (51)
Figure GDA00025242861100002310
Step 3 includes step 3.2 many-to-many S L IPT V L C network minimum rate maximization, considering user rate fairness policy, by optimizing the design of the beam former, i.e. design set
Figure GDA00025242861100002311
The value of the medium element maximizes the minimum rate, and simultaneously meets the minimum energy collection requirement and the illumination control constraint:
Figure GDA00025242861100002312
Figure GDA00025242861100002313
Figure GDA00025242861100002314
NID＝τPT(52d)
Figure GDA00025242861100002315
wherein v iskFor the energy harvesting requirement of the kth user,
Figure GDA00025242861100002316
is the maximum total transmission power.
Substituting (52d) into (52c) and introducing auxiliary variable
Figure GDA00025242861100002317
The problem (52) can be equivalently restated as:
Figure GDA00025242861100002318
Figure GDA00025242861100002319
Figure GDA00025242861100002320
Figure GDA00025242861100002321
Figure GDA00025242861100002322
this is a non-convex problem due to the rate constraint (53b) and the energy harvesting constraint (53 c).
According to definition (48), the question (53) can be rewritten to a concise form:
Figure GDA0002524286110000241
Figure GDA0002524286110000242
Figure GDA0002524286110000243
Figure GDA0002524286110000244
Figure GDA0002524286110000245
wherein the content of the first and second substances,
Figure GDA0002524286110000246
to handle the non-convex constraints (54b) and (54c), the present invention employs SDR techniques. Specifically, ignoring the non-convex rank constraint rank (g) 1, the problem (54) may be relaxed as:
Figure GDA0002524286110000247
Figure GDA0002524286110000248
Figure GDA0002524286110000249
Figure GDA00025242861100002410
Figure GDA00025242861100002411
Figure GDA00025242861100002425
due to variables in the constraint (55b)
Figure GDA00025242861100002422
This problem remains non-convex. However, for a given
Figure GDA00025242861100002423
The problem (55) is convex. Thus, the problem (55) is a pseudo-convex optimization problem whose global optimal solution can be searched with a simple dichotomy. In particular, for a given
Figure GDA00025242861100002424
The problem (55) can be summarized as the SDP feasibility sub-problem sequence:
findG (56a)
Figure GDA00025242861100002412
Figure GDA00025242861100002413
Figure GDA00025242861100002414
Figure GDA00025242861100002426
algorithm 1 describes a dichotomy of the processing problem (55). Definition of
Figure GDA00025242861100002415
Is the optimal solution to the problem (55). If it is
Figure GDA00025242861100002416
Then the optimal beam form of the problem (54) is obtained by eigenvalue decompositionVector of formation
Figure GDA00025242861100002417
If it is not
Figure GDA00025242861100002418
The present invention can randomize the Gaussian [23 ]]Application to
Figure GDA00025242861100002419
Obtain a feasible solution to the problem (54)
Figure GDA00025242861100002420
Table 1 algorithm 1: dichotomy
Figure GDA00025242861100002421
Figure GDA0002524286110000251
And 4, step 4: and (5) simulation results. Some numerical results are given to analyze the impact of key factors on system performance. Assume that the peak amplitude and variance of the input data s are a 2 and 1, respectively. The parameters of the light-emitting diode, the photodiode and the solar panel are shown in a table 2, the parameters are quoted from [1], [24], and the circuit architecture of the solar panel adopts [25] - [27 ]. The photovoltaic module adopts a monocrystalline silicon solar cell. The power spectral density of additive noise is-98.82 dBm.
TABLE 2 LED, photodiode and solar Panel parameters
Half power half angle of light emitting diode φ1/2 60°
Half field angle of photodiode Ψ1 60°
Half field angle of solar cell panel Ψ2 60°
Detector area of photodiode APD 1cm2
Detector area of solar panel As 10cm2
Variance of zero mean gaussian noise σ2 -98.82dBm
Maximum optical power PT 50w
Level of illumination τ 0.9
Short circuit current under standard test conditions Isc,stc 200mA
Open circuit voltage under standard test conditions Uoc,stc 5V
Step 4 includes step 4.1 simulation results of point-to-point S L IPT V L C System, FIG. 7a, with DC bias IDIncreasing, the energy collected increases logarithmically. This is because as shown in (25),
Figure GDA0002524286110000252
is of the order of PsolarIs the dominant place. Lower limit of achievable rate
Figure GDA0002524286110000253
First increasing and then slowly decreasing. This is because, as shown in equation (29), the lower limit of the rate is
Figure GDA0002524286110000254
Not one relating to dc offset IDA monotonic function. Note that in the simulation, the power gain g of the power amplifier is equal to
Figure GDA0002524286110000255
When DC bias IDSmaller, with DC bias IDThe power gain g of the power amplifier increases quadratically. DC offset IDWhen larger, the power gain g of the power amplifier follows the DC bias IDThe increase in (a) decreases quadratically.
As shown in FIG. 7b, as the power gain g of the power amplifier increases, the energy Q collected by the solar panel increasessolarIncreased, lower bound on achievable rate
Figure GDA0002524286110000261
A fast increase followed by a slow increase indicates that increasing the power gain g of the power amplifier is an efficient energy transfer, not an efficient liftingHigh transmission speed.
Step 4 comprises the simulation results of a step 4.2 many-to-many S L IPT V L C network-assuming there are 9 leds and 2 users, i.e. N-9, K-2-furthermore, assuming that there are 9 leds and 2 users
Figure GDA0002524286110000262
Figure GDA0002524286110000263
The positions of the photodiode s, the solar panel and the light emitting diode are shown in table 3.
TABLE 3 positions of photodiodes, LEDs and solar panels
Position of Position of
PD1 (5.1，6.0，1.5) PD2 (5.1，4.0，1.5)
Sloar1 (5.0，5.1，1.5) Sloar2 (5.0，4.9，1.5)
LED1 (4.9，4.9，3.0) LED2 (4.9，5.0，3.0)
LED3 (4.9，5.1，3.0) LED4 (5.0，4.9，3.0)
LED5 (5.0，5.0，3.0) LED6 (5.0，5.1，3.0)
LED7 (5.1，4.9，3.0) LED8 (5.1，5.0，3.0)
LED9 (5.1，5.1，3.0)
In FIG. 8a
Figure GDA0002524286110000264
K2, it can be seen that the total power in the three cases decreases as the number N of leds increases. In addition to this, the present invention is,
Figure GDA0002524286110000265
the higher the value, the more demanding the transmission powerIs large. In FIG. 8b, it can be seen that the electrical power, with or without harvesting energy constraints
Figure GDA0002524286110000266
All following the rate threshold
Figure GDA0002524286110000267
The increase is monotonically increasing. Comparison
Figure GDA0002524286110000268
And
Figure GDA0002524286110000269
in both cases, the higher the energy collection threshold, the greater the transmission power consumption. In FIG. 8c, the electric power is known
Figure GDA00025242861100002610
Along with energy collection threshold
Figure GDA00025242861100002611
The increase in (c) is logarithmic. At the same time, the rate threshold
Figure GDA00025242861100002612
The higher the required transmission power. In FIG. 9, the lower limit of the maximum rate is known
Figure GDA00025242861100002616
With energy collection threshold
Figure GDA00025242861100002613
Is increased and decreased. Finally, by comparing the power budgets
Figure GDA00025242861100002614
In this case, it can be seen that the higher the transmission power budget is, the lower the maximum rate limit is
Figure GDA00025242861100002615
The larger.
The invention further deduces the explicit expressions of information transmission and energy collection of a plurality of pairs of S L IPTV L C networks, and researches the design of a beam former for the problem of minimization of total transmission power and the problem of lower limit of maximized rate respectively.
In specific implementation, the present application further provides a computer storage medium, where the computer storage medium may store a program, and the program may include some or all of the steps in the embodiments of the method for jointly transmitting information and energy in a visible light communication system provided by the present application when executed. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM) or a Random Access Memory (RAM).
Those skilled in the art will clearly understand that the techniques in the embodiments of the present application may be implemented by way of software plus a required general hardware platform. Based on such understanding, the technical solutions in the embodiments of the present application may be essentially implemented or a part contributing to the prior art may be embodied in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the embodiments or some parts of the embodiments of the present application. The same and similar parts in the various embodiments in this specification may be referred to each other.
The above-described embodiments of the present application do not limit the scope of the present application.

Claims (5)

1. A method for co-transmitting information and energy in a visible light communication system, comprising:
step 1, establishing a visible light communication S L IPT V L C system for transmitting point-to-point information and energy together, wherein the point-to-point S L IPT V L C system comprises a point-to-point transmitting end and a point-to-point receiving end, and the point-to-point transmitting end converts a point-to-point transmission signal into visible light through a light emitting diode and sends the visible light to the point-to-point receiving end;
the point-to-point receiving end receives the point-to-point information of the visible light through a photodiode, or collects the point-to-point energy of the visible light through a solar cell panel;
the step 1 comprises the following steps:
step 1.1: calculating the point-to-point transmission signal x:
let s denote successive data symbols and
Figure FDA0002524286100000011
random real numbers of (a);
s has a peak amplitude of-A ≦ s ≦ A, and a variance of s
Figure FDA0002524286100000012
Wherein A is more than 0 and more than 0;
the point-to-point transmission signal x is:
Figure FDA0002524286100000013
where g is the power gain of the power amplifier, IDIs a direct current bias;
the power gain g of the power amplifier should satisfy:
Figure FDA0002524286100000014
average electric power of the point-to-point transmission signal x
Figure FDA0002524286100000015
Comprises the following steps:
Figure FDA0002524286100000016
luminous flux phi of the light emitting diodeOTComprises the following steps:
ΦOT＝354.286x+27, (4)
step 1.2, analyzing the illumination control of the point-to-point S L IPT V L C system according to the point-to-point transmission signal x:
illumination control of the point-to-point S L IPT V L C, namely illumination level tau and average light power of the point-to-point S L IPT V L C system
Figure FDA0002524286100000017
And maximum optical power PTThe relationship between:
Figure FDA0002524286100000018
0＜τ≤1；
average optical power of the point-to-point S L IPT V L C system according to equation (1)
Figure FDA0002524286100000019
Is biased by said direct currentDDetermine, i.e. that
Figure FDA00025242861000000110
Figure FDA00025242861000000111
The power gain g of the power amplifier satisfies:
Figure FDA0002524286100000021
wherein, IHFor maximum allowable current of light-emitting diodes, i.e.
Figure FDA0002524286100000022
Step 1.3.1: analyzing a point-to-point information receiving module of the point-to-point receiving end:
l oS link gain h between the light emitting diode and the photodiode1Comprises the following steps:
Figure FDA0002524286100000023
wherein the content of the first and second substances,
Figure FDA0002524286100000024
is a Lambert index,. phi1/2Is the half power half angle of the LED, d1Is the distance between the light emitting diode and the photodiode, APDDenotes the detector area of the photodiode, phi1The exit angle of the led to the photodiode,
Figure FDA0002524286100000025
is the angle of incidence of the LED to the photodiode, Ψ1Represents the half field angle of the photodiode;
the received signal y is:
y＝h1x+z， (9)
wherein z represents a variance σ2Zero mean gaussian noise of (d);
achievable rate RSISOComprises the following steps:
Figure FDA0002524286100000026
where α and gamma are parameters determined by A and sigma2Variance of zero mean gaussian noise;
the achievable rate RSISOLower boundary of (1)
Figure FDA0002524286100000027
Is obtained by the following distribution：
Figure FDA0002524286100000028
Where α and γ are solutions of the following equations:
T(A)-T(-A)＝e1+α, (12a)
β(eA(β-γA)-e-A(β+γA)-e1+α)＝0, (12b)
eA(β-γA)((β-2γA)e-2Aβ-β-2γA)+(β2+2γ)e1+α＝4γ2e1+α, (12c)
wherein the content of the first and second substances,
Figure FDA0002524286100000031
step 1.3.2: analyzing a point-to-point energy collection module of the point-to-point receiving end:
channel gain h between light emitting diode and solar panel2：
Figure FDA0002524286100000032
Wherein A issRepresenting the detector area of the solar panel, d2Is the distance between the light emitting diode and the solar cell panel, phi2The exit angle of the leds to the solar panel,
Figure FDA0002524286100000033
is the incident angle of the LED to the solar panel, psi2Representing a half field angle of the solar panel;
luminous flux phi received by solar cell panelOR：
ΦOR＝h2ΦOT(14)
The received solar panel illumination E is:
Figure FDA0002524286100000034
wherein the content of the first and second substances,
Figure FDA0002524286100000035
is the relative spectral energy density of the light emitting diode, λ is the wavelength of light,
Figure FDA0002524286100000038
Figure FDA0002524286100000036
as a function of standard luminosity, EaIndicating the illuminance (W/m) of ambient light2)；
Output voltage U and open circuit voltage U by using partial open circuit voltage FOCV method and maximum power point MPP tracking methodocThe approximation is:
U＝ηUoc, (16)
wherein η is a coefficient, η∈ [0.71,0.78 ];
according to the equivalent circuit model, the output current I of the solar cell panel is as follows:
Figure FDA0002524286100000037
wherein, IphIs a photo-generated current, Is0To saturate dark current, c1Is the solar panel coefficient, RsIs an equivalent series resistance, RshIs equivalent to parallel resistance, and solar cell panel coefficient
Figure FDA0002524286100000041
qeIs an electronic charge, k is the Boltzmann constant, JfIs the ideal factor of a diode, TaIs ambient temperature;
the output current I of the solar panel is approximately:
Figure FDA0002524286100000042
when the circuit is open, namely the output current I of the solar cell panel is equal to 0, there are:
Figure FDA0002524286100000043
Figure FDA0002524286100000044
the photo-generated current IphWith the received solar panel illuminance E and the ambient temperature TaIn proportion:
Figure FDA0002524286100000045
wherein, Isc,stcIs short-circuit current in standard test condition, i.e. illuminance E in standard test conditionstc＝1000W/m2Ambient temperature T under Standard test conditionsa,stcShort-circuit current at 298K, αstcIs the short circuit current temperature coefficient;
the open circuit voltage U obtained by substituting formula (20) for formula (19b)ocIs composed of
Figure FDA0002524286100000046
Wherein the content of the first and second substances,
Figure FDA0002524286100000047
the saturated dark current I in formula (17)s0Dependent on the ambient temperature Ta：
Figure FDA0002524286100000048
Wherein, Is0,stcIs dark under standard test conditionsSaturation current, coefficient of
Figure FDA0002524286100000049
Eg,stc1.12eV is the band gap of the material in the standard test state;
when the circuit is short-circuited, i.e. the output voltage U equals 0, there is
Iph＝Isc， (23)
Wherein, IscIs a short circuit current;
according to the formula (18), the dark saturation current I in the standard test state can be obtaineds0,stc：
Figure FDA0002524286100000051
Wherein, Uoc,stcIs the open circuit voltage under the standard test state;
obtaining the output power P of the solar cell panelsolarAs a function of the power gain g for the power amplifier:
Figure FDA0002524286100000052
wherein the content of the first and second substances,
Figure FDA0002524286100000053
Figure FDA0002524286100000054
Figure FDA0002524286100000055
energy Q collected by the solar panel at the time delta tsolar(Δt)：
Qsolar(Δt)＝PsolarΔt (26)
Step 1.4, calculating an illumination-speed-energy area of the point-to-point S L IPT V L C system:
power gain g of the power amplifier and the DC offset IDSatisfies the following conditions:
Figure FDA0002524286100000056
wherein the content of the first and second substances,
Figure FDA0002524286100000057
is the maximum total transmission power;
by combining formula (2), formula (7) and formula (27), it is possible to obtain:
Figure FDA0002524286100000058
introducing illumination-information-energy region CI-R-EThe illumination-information-energy region CI-R-EThe illumination level tau and the achievable rate R under the constraint condition of given emission powerSISOAnd collected energy QsolarComposition of said illumination-information-energy region CI-R-EThe expression of (a) is:
Figure FDA0002524286100000061
wherein the content of the first and second substances,
Figure FDA0002524286100000062
2. the method of claim 1, comprising the step 2 of establishing a many-to-many S L IPT V L C network according to the point-to-point S L IPT V L C system, wherein the many-to-many S L IPT V L C network comprises a many-to-many transmitting terminal and a many-to-many receiving terminal, and the many-to-many transmitting terminal converts many-to-many transmission signals into visible light through more than two light emitting diodes and transmits the visible light to the many-to-many receiving terminal;
the many-to-many receiving end receives many-to-many information of the visible light through more than two photodiodes or collects many-to-many energy of the visible light through more than two solar panels;
the method specifically comprises the following steps:
when N LEDs send data and energy to K users at the same time, order skData symbols representing said N LEDs to a kth user, where | sk|≤Ak，
Figure FDA0002524286100000063
AkAndkrespectively the amplitude peak value and the variance of the kth data symbol;
the many-to-many transmission signal x is:
Figure FDA0002524286100000064
wherein K is the total number of users,
Figure FDA0002524286100000065
for data symbols skBeamforming vector of 1NA vector in which all the elements of dimension N × 1 are 1;
average electric power of the many-to-many transmission signal x
Figure FDA0002524286100000066
Comprises the following steps:
Figure FDA0002524286100000067
wherein N is the number of light emitting diodes;
the beamforming vector gkSatisfies the following conditions:
Figure FDA0002524286100000068
wherein e isnIs a base vector;
the nth hairLuminous flux phi of photodioden,OTComprises the following steps:
Figure FDA0002524286100000071
wherein, gk,nIs the power gain between the nth led and the kth user.
3. The method of claim 2, wherein step 2 comprises:
step 2.1, analyzing the illumination control of the many-to-many S L IPTV L C network according to the many-to-many transmission signal x of the many-to-many S L IPT V L C network:
the beamforming vector gkSatisfies the following conditions:
Figure FDA0002524286100000072
wherein, IHMaximum allowable current for the light emitting diode;
average optical power of many-to-many S L IPT V L C network
Figure FDA0002524286100000073
Comprises the following steps:
Figure FDA0002524286100000074
illumination control of the many-to-many S L IPT V L C network, i.e. the illumination level τ, average light power of the many-to-many S L IPT V L C network
Figure FDA0002524286100000075
And said maximum optical power PTThe relationship between:
Figure FDA0002524286100000076
4. the method of claim 3, wherein the step 2 comprises:
step 2.2: analyzing a many-to-many information receiving module of the many-to-many receiving end:
signal y received at the kth user1,kComprises the following steps:
Figure FDA0002524286100000077
wherein, giBeamforming vector, s, for the ith useriFor data symbols sent to the ith user, h1,k,nFor channel gain from the nth LED to the kth user photodiode, h1,k＝[h1,k,1,...,h1,k,N]TRepresenting the channel vector between the LED and the user k, zkIs zero mean and variance is σ2Additive gaussian noise of (a);
reachable rate of kth user
Figure FDA0002524286100000078
Comprises the following steps:
Figure FDA0002524286100000079
wherein the parameter αiAnd gammaiFrom AiAndidetermination of AiAndirespectively the amplitude peak value and the variance of the ith data symbol;
the lower bound of equation (38) is obtained by the following distribution:
Figure FDA0002524286100000081
wherein, αi，βiAnd gammaiIs a solution of the following equation:
Figure FDA0002524286100000082
5. the method of claim 4, wherein the step 2 comprises:
step 2.3: analyzing a many-to-many energy collection module of the many-to-many receiving end:
illuminance E received at the k-th userkComprises the following steps:
Figure FDA0002524286100000083
wherein h is2,k,nRepresenting the channel gain from the nth led to the kth customer solar panel,
Figure FDA0002524286100000084
Figure FDA0002524286100000085
is the relative spectral energy density of the light emitting diode, λ is the wavelength of light,
Figure FDA0002524286100000089
Figure FDA0002524286100000086
as a function of standard luminosity, EaIndicating the illuminance (W/m) of ambient light2)，Φn,OTLuminous flux of the nth light emitting diode;
at the kth user, the solar panel outputs a voltage UkComprises the following steps:
Uk＝ηUk,oc, (42)
wherein, Uk,ocIs the open circuit voltage of the solar panel at the kth user;
Figure FDA0002524286100000087
wherein the content of the first and second substances,
Figure FDA0002524286100000088
Ik,sc,stcfor short circuit current in the kth solar panel standard test condition, αk,stcShort-circuit current temperature coefficient for kth solar panel, Ek,stcFor the illumination received by the kth user under standard test conditions, Ik,s0Saturated dark current for the kth user;
output current I of kth solar cell panelk：
Figure FDA0002524286100000091
Average output power of solar panel of kth user
Figure FDA0002524286100000092
Comprises the following steps:
Figure FDA0002524286100000093
wherein the content of the first and second substances,
Figure FDA0002524286100000094
h2,k＝[h2,k,1,...,h2,k,N]Trepresenting the channel vector between the led and the kth solar panel,
Figure FDA0002524286100000095
Figure FDA0002524286100000096
CN201910151387.3A 2019-02-28 2019-02-28 Method for jointly transmitting information and energy in visible light communication system Active CN109951229B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910151387.3A CN109951229B (en) 2019-02-28 2019-02-28 Method for jointly transmitting information and energy in visible light communication system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910151387.3A CN109951229B (en) 2019-02-28 2019-02-28 Method for jointly transmitting information and energy in visible light communication system

Publications (2)

Publication Number Publication Date
CN109951229A CN109951229A (en) 2019-06-28
CN109951229B true CN109951229B (en) 2020-07-31

Family

ID=67008189

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910151387.3A Active CN109951229B (en) 2019-02-28 2019-02-28 Method for jointly transmitting information and energy in visible light communication system

Country Status (1)

Country Link
CN (1) CN109951229B (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111342897A (en) * 2020-03-06 2020-06-26 沈宏岩 Weak light detection communication energy carrying system and transmission algorithm thereof
CN113541791A (en) * 2020-04-14 2021-10-22 华为技术有限公司 Wireless optical communication method and related device
CN112615672A (en) * 2020-12-15 2021-04-06 华中科技大学 SLIPT-based hybrid VLC/RF cooperative communication system and method
CN113541805B (en) * 2021-06-11 2022-04-29 南京航空航天大学 Method for realizing energy-carrying two-way communication based on laser wireless energy transmission system
CN114499662A (en) * 2022-02-18 2022-05-13 中国科学院空间应用工程与技术中心 Communication device and wireless optical communication and energy transmission positioning integrated system
CN114598389B (en) * 2022-03-09 2024-04-02 国网能源研究院有限公司 Method and device for maximizing visible light information and energy synchronous transmission network and rate
CN115001576B (en) * 2022-05-20 2023-08-15 复旦大学 micro-LED predistortion method and system based on visible light communication system, storage medium and intelligent terminal

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012195692A (en) * 2011-03-15 2012-10-11 Outstanding Technology:Kk Visible light communication device
CN103346834A (en) * 2013-06-26 2013-10-09 上海无线通信研究中心 Visible-light energy-carrying communication system and method
CN104868952A (en) * 2015-06-18 2015-08-26 北京邮电大学 Solar cell and light-emitting diode-based function-symmetric passive full-duplex transmit-receive device in visible light communication system
CN105471502A (en) * 2015-12-08 2016-04-06 武汉邮电科学研究院 Communication system and method based on visible light and solar panel
CN108242955A (en) * 2017-03-14 2018-07-03 中国矿业大学 A kind of point-to-point visible light communication system and its energy efficiency analysis method for air

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012195692A (en) * 2011-03-15 2012-10-11 Outstanding Technology:Kk Visible light communication device
CN103346834A (en) * 2013-06-26 2013-10-09 上海无线通信研究中心 Visible-light energy-carrying communication system and method
CN104868952A (en) * 2015-06-18 2015-08-26 北京邮电大学 Solar cell and light-emitting diode-based function-symmetric passive full-duplex transmit-receive device in visible light communication system
CN105471502A (en) * 2015-12-08 2016-04-06 武汉邮电科学研究院 Communication system and method based on visible light and solar panel
CN108242955A (en) * 2017-03-14 2018-07-03 中国矿业大学 A kind of point-to-point visible light communication system and its energy efficiency analysis method for air

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Energy Efficiency of SISO and MISO in Visible Light Communication Systems;Shuai Ma,etal.;《JOURNAL OF LIGHTWAVE TECHNOLOGY》;20180615;第2499-2509页 *
Simultaneous Lightwave Information and Power Transfer:Policies,Techniques,and Future Directions;GAOFENG PAN,etal;《IEEE Access》;20190226;第28250-28257页 *

Also Published As

Publication number Publication date
CN109951229A (en) 2019-06-28

Similar Documents

Publication Publication Date Title
CN109951229B (en) Method for jointly transmitting information and energy in visible light communication system
CN109660888B (en) Optimization method of visible light communication network
Ma et al. Simultaneous lightwave information and power transfer in visible light communication systems
Rakia et al. Optimal design of dual-hop VLC/RF communication system with energy harvesting
Morsi et al. On the performance of wireless powered communication with non-linear energy harvesting
Pejoski et al. Optimal power and time allocation for WPCNs with piece-wise linear EH model
Butala et al. SVD-VLC: A novel capacity maximizing VLC MIMO system architecture under illumination constraints
Diamantoulakis et al. Simultaneous lightwave information and power transfer (SLIPT) for indoor IoT applications
CN109286426B (en) Transmission method of wireless energy-carrying cooperative precoding spatial modulation system
Chen Energy harvesting communications: principles and theories
Sharma et al. Optimal LED deployment for mobile indoor visible light communication system: Performance analysis
Rakia et al. Dual-hop VLC/RF transmission system with energy harvesting relay under delay constraint
CN110708716B (en) Short packet communication transmission performance analysis method based on multi-antenna energy capture
Shi et al. Profit maximization in wireless powered communications with improved non-linear energy conversion and storage efficiencies
Chen et al. BER analysis for interfering visible light communication systems
Kazmi et al. Optimization of full-duplex relaying system with non-linear energy harvester
Sansoy et al. Empowering wireless sensor networks with RF energy harvesting
Zargari et al. Resource allocation of hybrid VLC/RF systems with light energy harvesting
Morapitiya et al. A SLIPT-assisted visible light communication scheme
Das et al. Effect of sunlight on photovoltaics as optical wireless communication receivers
Sharda et al. Diversity-multiplexing tradeoff for indoor visible light communication
CN111884688B (en) OPS structure-based R-E domain optimization method for multi-node multi-antenna SWIPT network
CN108337024B (en) Large-scale MIMO system energy efficiency optimization method based on energy collection
Shen et al. LMMSE-based SIMO receiver for ultraviolet scattering communication with nonlinear conversion
Contreras et al. A rectenna as energy source for wireless sensor nodes

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant