EP3398265A1 - Récepteur photovoltaïque optimisé pour la communication par lumière codée - Google Patents
Récepteur photovoltaïque optimisé pour la communication par lumière codéeInfo
- Publication number
- EP3398265A1 EP3398265A1 EP16826370.5A EP16826370A EP3398265A1 EP 3398265 A1 EP3398265 A1 EP 3398265A1 EP 16826370 A EP16826370 A EP 16826370A EP 3398265 A1 EP3398265 A1 EP 3398265A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- light
- communication
- photoreceptor
- coded
- coded light
- 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.)
- Withdrawn
Links
Classifications
-
- 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
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07953—Monitoring or measuring OSNR, BER or Q
Definitions
- the present invention relates to communication devices by coded light type VLC (acronym for "Visible Light Communication”) also known under the name of LiFi (acronym for "Light-Fidelity” in English terminology) and more particularly relating to with the performance of the optical receiver which participates inter alia in the flow of the communication.
- VLC coded light type
- LiFi acronym for "Light-Fidelity” in English terminology
- a coded light communication system is generally composed of a light source comprising at least one light emitting diode (commonly referred to by its acronym "LED") and a photoreceptor light receiver.
- the LED or LEDs may have a dual function, both lighting and coded information communication.
- the LEDs can be:
- LEDs emitting a white light composed of a blue chip and associated with a luminophore
- LEDs emitting a specific color composed of one or more color chips
- LEDs emitting in the infra-red or ultraviolet imperceptibly to the eye.
- LEDs emit a luminous flux with a characteristic emission spectrum, different from the spectrum of natural light. Luminous flux is measured in Lux, but to distinguish it from natural light, the luminous flux of the LEDs whose light is coded is called Lux LiFi.
- the Lux LiFi is therefore the unit of measure of the luminous flux measured from a luxmeter when the light used is modulated and generated by LEDs.
- the levels of illumination that are used for LiFi communications are generally of three types: The "low LiFi flux” which is a luminous flux less than 400 Lux LiFi. The "average LiFi flux” which is a luminous flux between 400 and 10,000 Lux LiFi. The "strong LiFi flux” which is a luminous flux greater than 10,000 Lux LiFi.
- the LEDs provide a light signal in the wavelength ranges of visible (LiFi), infrared (IR) and ultraviolet (UV), the intensity of which is modulated according to the information to be transmitted. .
- the emission of LEDs in the visible spectrum (LiFi) has the advantage of allowing a dual function of both lighting and data transmission, and the physical characteristics of the LEDs make it possible to envisage flow rates of the order of a few hundred megabits per second for dedicated systems.
- the LiFi reception systems receive the lights from all directions of the space without distinction, whether it is the ambient light or the modulated light emitted by the LEDs of a LiFi transmitter .
- a technical problem arises because most known photoreceptors are very sensitive to ambient light and saturate rapidly in the presence of a strong ambient light flux. As a result, they no longer make it possible to retranscribe the variation of the luminous intensity of the LiFi signal when the saturation is installed.
- a solution to this problem is, at the detector, to "discriminate” the light from LiF LEDs from other sources of ambient light in order to increase the signal / noise ratio of the LiFi signal and consequently to increase and stabilize the transmission rate.
- "Discrimination” solutions exist that use lenses, possibly Fresnel lenses or optical diffractive elements, which focus the coded light from the LEDs on the photoreceptor to increase the signal-to-noise ratio of the LiFi signal. But these solutions “with lenses” require the photoreceptor to receive the coded signal from a single direction, which limits applications to devices that remain fixed.
- the main purpose of the invention is to improve the signal-to-noise ratio of a LiFi communication, even when the photoreceptor receives at the same time an uncoded ambient light which positions said receiver in a brightness range well above 5000 Lux. Despite this reception of intense light, said photoreceptor will have to keep the SNR (signal / noise ratio) substantially constant even in the case of large variations in the ambient luminosity.
- the device embodying the invention will then be compatible with mobile communication means such as mobile phones, GPS, tablet computers and generally with LiFi communication devices placed in all types of vehicles. transport.
- the word “noise” is defined by an electronic noise associated with the reception system including the intrinsic electrical noise of the photoreceptor. This noise exists in the absence of uncoded light.
- the noise "shot” or noise shot present in any electrical circuit where the energy transfer is described by quantum phenomena
- the noise related to the current in a diode that is due to the random emission of electrons by thermo-ionic effect and which is particularly born in the charge resistance
- the photonic noise due to the corpuscular nature of the electromagnetic radiation
- the Johnson noise or thermal noise due to the random movements of the charges generated by the temperature.
- the subject of the invention is a coded-light communication device whose communication has an initial SNR1 signal-to-noise ratio which varies according to the lighting conditions, this device comprising at least one photoreceptor-type light receiver comprising an anode and a cathode and having an initial shunt resistance Rsh1 value, this receiver being capable of being simultaneously exposed to a coded light source carrying a signal and an uncoded light source, characterized in that said anode and cathode are short-circuited by at least one short-circuit resistance Rp arranged inside the photoreceptor, of value Rsh2 chosen so that the new value of the shunt resistance of said photoreceptor denoted Rsh3 and resulting from the connection of the resistance of initial shunt Rsh1 and the short-circuit resistance Rp confers on the communication device a new resulting signal-to-noise ratio SNR2 which remains substantially independent of the intensity of said uncoded light.
- the invention provides for selecting a shunt resistor Rp so that the shunt resistance equivalent Rsh3 (consisting of resistors Rsh1 and Rsh2 in parallel) is less than a predetermined threshold value.
- the predetermined threshold value of the equivalent shunt resistor Rsh3 taking into account the active surface of the photodetector and the percentage of photovoltaic area (in the case of a square photo-detector based on photovoltaic material) is less than a value of the order of 1000 Q.cm 2 .
- the photo detector was a square photovoltaic cell with an area of 1 cm 2 , it should have a shunt resistance equivalent less than 1000 ⁇ .
- the target shunt resistance threshold can therefore be calculated for a given photovoltaic cell, as a function of its surface area and its percentage of photovoltaic material coverage.
- the coded light source may be coded either in amplitude or in phase in the case of a coherent source, or by the variation of its luminous intensity in the case of an incoherent source.
- the device according to the invention comprises a photoreceptor which can be a module composed of at least one photovoltaic cell which generates a significant electrical voltage from a light radiation, and which makes it possible to receive a LiFi signal even in a strong environment. ambient light flux, and this without the aforementioned saturation phenomenon is installed.
- Said photovoltaic module is able to receive a LiFi signal from a LiFi source placed outside in the presence of solar radiation without causing disturbance at the reception, unlike other photoreceptors.
- said device has a particular characteristic which is that for a given level of illumination LiFi, there exists an internal resistance value (shunt resistor Rsh2) of said module which stabilizes the SNR and renders the photo-detection insensitive to the increase. the ambient luminous flux.
- the photoreceptor according to the invention has the characteristic of a stable signal-to-noise ratio (SNR1 substantially equal to SNR2).
- SNR1 stable signal-to-noise ratio
- the SNR varies little according to the useful frequency band, ie that is to say that the variations of the SNR level in the given frequency band remain below 5%.
- the photovoltaic optical receiver which is part of the invention, makes it possible to optimize the optical communication independently of the ambient light environment.
- Said photovoltaic receiver operates without deterioration of the communication, that is to say without a drop in flow, when working in low ambient light (this is the case of an indoor environment for example of the order of 400 Lux LiFi) or in strong ambient light (external environment, for example of the order of 50 000 Lux).
- the stability of the SNR of the device facilitates the implementation of the information processing means, eliminates the need for recurrent automatic calibration and therefore channel learning techniques and channel adaptation.
- the information processing means can then be freed from the channel adaptation step.
- the photoreceptor is a cell photovoltaic of any type such as a crystalline silicon type cell, or amorphous silicon or a stack of thin photosensitive layers.
- the internal structure of the photovoltaic cell can be very diverse, but in all cases the internal shunt resistance (Rsh1) remains an intrinsic characteristic of each cell. It is this initial shunt resistor (Rsh1) that is lowered to a new lower value (Rsh3) by a shunt (Rsh2) as provided by the present invention.
- said photoreceptor is semi-transparent and is composed of an array of photovoltaic cells according to the characteristics of the invention, these cells being spaced apart from one another by zones of transparency.
- the size of said cells may be less than 100 microns which makes said receptor semitransparent and uniform appearance without the separating power of the eye does not distinguish cells individually.
- all the photovoltaic cells have their shunt resistor Rsh1 which has been lowered by an Rsh2 shunt in order to optimize the reception and transmission speed performance of the LiFi information, in particular in intense light.
- Rsh1 which has been lowered by an Rsh2 shunt in order to optimize the reception and transmission speed performance of the LiFi information, in particular in intense light.
- the short-circuit resistance Rp is positioned only on a proportion P% of photovoltaic cells of said cell network so that the overall shunt resistance (Rsh3) of the photoreceptor will be related to this said proportion of P%.
- said short circuit of value Rp between the cathode and the anode of the cells can be done in different ways, depending on the types of cells used, in particular this electrical junction can be of wire type or printed surface type, and can be composed of all types of conductive or semiconductor materials.
- said communication device also receives uncoded ambient light that may be natural light (solar) or artificial light from all types of lamps such as LEDs ("Light Emissive Diode”). "), Fluorescent tubes, incandescent lamps or Sodium vapor lamps.
- a particular embodiment comprises convergent optical lenses or diffractive elements for example for focusing the light between the source of the coded light and the active surface of said photoreceptor.
- the lenses or diffractive optical elements are positioned between the photovoltaic cells and an electronic image placed behind the photoreceptor which is semi-transparent.
- the lenses in this particular embodiment, concentrate the light of the electronic images through the transparency spaces between the cells, which makes the image visible through said photoreceptor.
- the present invention also relates to all types of mobile devices that integrate the communication device according to the invention, such as for example mobile phones or GPS (Sigle of "Global Positioning System”).
- the subject of the present invention is also any type of semitransparent surface that integrates the communication device according to the invention, such as, for example, glass panes. all types of buildings, windows for all types of transport vehicles or for all types of screens with electronic displays. detailed description
- FIG. 1 shows the various components of the communication device
- FIG. 2 is a modeled representation in the form of an equivalent electrical diagram of the behavior of a conventional photoreceptor.
- FIG. 3 is a model representation in the form of an equivalent electrical diagram of the behavior of the photoreceptor according to the invention.
- Fig. 4 is a graph showing the attenuation of the LiFi signal of a conventional photoreceptor in the presence of intense ambient light.
- Fig. 5 is a graph which shows the SNR decrease of a conventional photoreceptor in the presence of intense light.
- FIG. 6 is a graph which shows the stability of the SNR even in the presence of various intense ambient lights in the case of a photoreceptor according to the invention.
- Figure 7 is a schematic three-dimensional representation of a crystalline silicon photovoltaic cell and the position of a short circuit according to the invention.
- FIG. 8 is a schematic three-dimensional representation of a photovoltaic cell made of amorphous silicon (thin layer) and the position of a short circuit according to the invention.
- the coded light communication device comprises:
- a photoreceptor type light receiver (2) whose value of its shunt resistance is reduced by the installation of a non-zero resistance short circuit (6) between its anode (5) and its cathode (4).
- this uncoded light (3) can be natural sunlight or artificial light.
- the photoreceptor (2) therefore receives both coded light (1) and uncoded light (3). It can be shown that the quality of signal reception depends on several factors the ratio of the signal intensity to the intensity of the uncoded light (3), and more generally between the signal strength and the intensity of the background "noise" which may be of a nature electronic and / or optical.
- the SNR of a communication (signal-to-noise ratio) is representative of the quality of the communication and its limits, particularly in terms of transmission rate.
- Figures 2 and 3 are modeled representations of a photoreceptor.
- FIG. 2 represents the equivalent electrical block diagram modeling of a conventional photoreceptor which behaves like the paralleling of an electricity generator (7), a diode (8) and a shunt resistor (Rsh1) which is intrinsic to the component.
- a series resistor (Rs) puts said photoreceptor in connection with an external resistive load (Rc) across which a potential difference (U) appears which is proportional to the overall light intensity (1 and 3) received by the photoreceptor ( 2).
- FIG. 3 shows the equivalent electrical diagram of a photoreceptor according to the invention, which comprises, in addition to conventional elements of a photoreceptor (FIG. 2), a non-zero resistance Rp short-circuit (Rsh2) positioned. in parallel with the shunt resistor (Rsh1) of the photoreceptor.
- Rsh2 non-zero resistance Rp short-circuit
- FIG. 4 represents the variation of the intensity of a signal received by a conventional photoreceptor as a function of its emission frequency (up to 1.4 Mega Hertz) in the case (curve 9) of a reception of a light LiFi emitted at 6600 Lux, without uncoded light, and in the case (curve 10) of a reception of the same LiFi coded light at 6600 Lux but with in addition an uncoded light of 36000 Lux. Note a general attenuation of the LiFi signal due to the presence (complementary reception) of an uncoded ambient light (3).
- FIG. 5 shows the same operating mode as that of FIG. 4, that is to say a 6600 Lux LiFi reception (curve 1 1) and a 6600 Lux LiFi reception plus an ambient light of 36000 lux (curve 12 ) on a conventional photoreceptor.
- the two curves 1 1 and 12 represent the variation of the SNR (dB) as a function of the transmission frequency (up to 1 .4 megahertz).
- dB the transmission frequency
- Figure 6 contains four curves (13,14,15,16) representative of the evolution of the SNR
- the curves 13, 14, 15 and 16 have substantially the same shape and the same amplitude, which means that there is in the presence of a stable SNR regardless of the intensity of the uncoded light (3) which is added to the coded light Lifi.
- FIG. 7 represents a photovoltaic cell (C1) used as a photoreceptor (2) in the communication device according to the invention.
- the photovoltaic cell (C1) is composed of a doped crystalline silicon sheet (17) on one side of which is deposited an electronic collection grid (anode, 18) and on the other side of which is deposited a thin layer of aluminum (19) which acts as a cathode for the cell (C1). Between the two faces (18 and 19) is created a resistive short-circuit (20) which lowers the value of the shunt resistance of the photovoltaic cell (C1).
- This short-circuit (20) can be realized in various ways, such as for example: making one or more small-diameter wire junctions between the anode and the cathode at the periphery of the cell (on the edges), or performing the drilling one or more holes or vias (20b) through the cell by a laser process which makes it possible to deposit on the walls of the hole a conductive material which creates an electrical conduction between the anode and the cathode.
- FIG. 8 represents a photovoltaic module (C2) used as a photoreceptor (2) in the communication device according to the invention.
- Said photovoltaic module C2 is composed of a transparent substrate (25), preferably made of glass, on which is deposited a transparent conductive ZnO thin layer (22), then on it an active thin layer of amorphous silicon (23). , then finally on it a thin layer of aluminum (24).
- Said module is structured by a laser beam so as to create by ablation a network of transparent zones (21 a, 21 b) and an array of cells (S1, S2, S3) electrically interconnected with each other in series mode by separations.
- the shunt resistance of said module is the sum of the shunt resistances of all the individual cells and the fact of lowering the shunt resistance of a certain percentage of said cells, decreases the shunt resistance of said module of the same percentage.
- the short circuits can be made for example by locally melting the thin aluminum layer (24) at a number of separations between cathodes (P3) for example using the properties of a thermal laser beam.
- the invention responds well to the goals set by stabilizing the signal-to-noise ratio (SNR) of a coded light communication device (LiFi), even when the photoreceptor of this device receives at the same time a non-ambient light.
- SNR signal-to-noise ratio
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1502752A FR3046512B1 (fr) | 2015-12-31 | 2015-12-31 | Recepteur photovoltaique optimise pour la communication par lumiere codee |
PCT/FR2016/000219 WO2017115024A1 (fr) | 2015-12-31 | 2016-12-30 | Récepteur photovoltaïque optimisé pour la communication par lumière codée |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3398265A1 true EP3398265A1 (fr) | 2018-11-07 |
Family
ID=55542725
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16826370.5A Withdrawn EP3398265A1 (fr) | 2015-12-31 | 2016-12-30 | Récepteur photovoltaïque optimisé pour la communication par lumière codée |
Country Status (5)
Country | Link |
---|---|
US (1) | US10461861B2 (fr) |
EP (1) | EP3398265A1 (fr) |
CN (1) | CN108702210A (fr) |
FR (1) | FR3046512B1 (fr) |
WO (1) | WO2017115024A1 (fr) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN111835416B (zh) | 2019-04-15 | 2022-07-12 | Oppo广东移动通信有限公司 | 电子设备之间的通信系统、方法以及电子设备 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006041486A1 (fr) * | 2004-10-01 | 2006-04-20 | Franklin Philip G | Procede et appareil permettant la transmission zonale de donnees au moyen des installations d'eclairage de batiments |
US6915083B1 (en) * | 1998-12-15 | 2005-07-05 | Zilog, Inc. | Signal receiver having wide band amplification capability |
KR100970034B1 (ko) * | 2002-10-24 | 2010-07-16 | 가부시키가이샤 나카가와 겐큐쇼 | 조명광통신장치 |
WO2011061965A1 (fr) * | 2009-11-18 | 2011-05-26 | 太陽誘電株式会社 | Circuit récepteur de lumière visible |
WO2014026601A1 (fr) * | 2012-08-13 | 2014-02-20 | 深圳光启创新技术有限公司 | Appareil de traitement de signal optique et procédé de décodage pour un dispositif de commande de réception de signal optique |
-
2015
- 2015-12-31 FR FR1502752A patent/FR3046512B1/fr active Active
-
2016
- 2016-12-30 CN CN201680082928.6A patent/CN108702210A/zh active Pending
- 2016-12-30 EP EP16826370.5A patent/EP3398265A1/fr not_active Withdrawn
- 2016-12-30 WO PCT/FR2016/000219 patent/WO2017115024A1/fr active Application Filing
- 2016-12-30 US US16/067,242 patent/US10461861B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
FR3046512A1 (fr) | 2017-07-07 |
WO2017115024A1 (fr) | 2017-07-06 |
CN108702210A (zh) | 2018-10-23 |
FR3046512B1 (fr) | 2019-02-01 |
US10461861B2 (en) | 2019-10-29 |
US20190028194A1 (en) | 2019-01-24 |
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