FR3143917A1 - Communication process in a system - Google Patents

Abstract

Communication process in a system One aspect of the invention relates to a communication method in a system comprising a first device and a second device, the first device and the second device being arranged on either side of a glazing, the method being implemented by the first device and comprising: receive a first light signal carrying a data stream via visible light communications technology, the data stream comprising a subset of data;emitting a second light signal carrying the subset of data to the second device via technology visible light communication; in which the second light signal is guided inside the glazing, from an entry point into the glazing located on a first peripheral part of the glazing towards an exit point located on a second peripheral part of the glazing, opposite the first peripheral part of the glazing. Figure to be published with the abstract: Figure 3

Description

Communication process in a system TECHNICAL FIELD OF THE INVENTION

The technical field of the invention is that of wireless optical communications, in particular wireless optical communications using the visible light domain.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

In vehicles such as trains, planes or cars, passengers do not always have access to the Internet, and therefore cannot easily retrieve, via their telephone for example, content such as multimedia data or text information. It is therefore interesting to be able to provide passengers of such vehicles with services allowing them to have access to content of their choice. By "content" is meant any information represented by a set of computer data, for example a photo, a video, music, a text (an article, a travel guide, a dictionary, etc.), etc.

In vehicles, it is difficult to provide solutions based on wired connections, which are not only expensive but also cumbersome, especially when the number of passengers is high.

Solutions based on wireless connections are therefore better suited to this type of environment.

Today, the vast majority of wireless connections use radio signals. In this wireless connection method, data is transported using radio waves (or simply "radio waves"), which are electromagnetic waves with a frequency ranging from a few Hertz to several hundred Gigahertz, for example between 3 Hz and 300 GHz. Communications networks using Wi-Fi or Bluetooth technology, and mobile telephone networks (such as 2G, 3G, 4G or 5G), are examples of networks using radio waves.

However, the use of wireless radio wave communications systems is accompanied by several problems, including the emission of radio frequencies in an enclosed environment, limited bandwidth (and therefore risks of network saturation causing slowdowns or even loss of connection) and electronic interference (which is increased in enclosed spaces such as the interior of a vehicle, due to the presence of a large number of reflective surfaces).

Another type of existing wireless communication system is based on the use of waves with frequencies located in the visible range (optical waves) of the electromagnetic spectrum, typically between 400 and 800 THz. This technology is commonly called "visible light communication" (or VLC) and therefore uses visible light as a data transmission medium. A particular type of VLC system is Li-Fi technology.

VLC systems have many advantages over radio frequency systems. For example, the associated spectral band is much wider (around 400 THz), which limits saturation, latency and instability problems. The use of this spectral band is free and is not regulated, unlike the radio frequency spectrum used in radio communication technologies. In addition, light does not interfere with radio frequencies, which guarantees compatibility between the VLC system and radio technologies (Wi-Fi, 4G, etc.). Finally, if the throughput depends a lot on the technology used by the light transmitter, throughputs of several Gigabits per second, or even several tens of Gigabits per second, can be achieved with transmitters already offered to the general public.

Another property of VLC systems is that light cannot pass through opaque obstacles, such as walls. This property may appear to be an advantage because it allows data to be partitioned within an enclosed space (which is an asset in terms of security, because it is easier to control the areas in which the data circulates than with a radiofrequency system), but it can also be a disadvantage, because the presence of an object or a person in the path of the light, between the transmitter and the photoreceiver, interrupts the communication between these two entities.

For example, it has been proposed to use Li-Fi connections in aircraft, using individual lights located above the passenger seats of the aircraft as transmitters and placing photoreceptors near the passengers' heads, for example above the headrests. A disadvantage of such a solution is that as soon as a person puts, for example, his hand or an object in front of one of the individual lights, the connection is interrupted for the passenger concerned.

The present invention improves the situation.

The invention provides a solution to the problems mentioned above, by proposing an at least partially wireless communication system, in which the data is sent from one communication device to another using visible light communication technology. The light fluxes carrying the data are advantageously guided inside a glazing arranged between two communication devices, in the thickness of this glazing. Thus, the problem of potential obstruction of the light flux, and therefore of the data flow, by an obstacle no longer arises. In the proposed system, the number of wired connections is considerably reduced, and it is possible to take full advantage of the advantages of visible light communication technologies, without suffering from the disadvantages mentioned above.

• recevoir un premier signal lumineux transportant un flux de données via une technologie de communication par lumière visible, le flux de données comprenant un sous-ensemble de données ;
• émettre un deuxième signal lumineux transportant le sous-ensemble de données vers le deuxième dispositif via une technologie de communication par lumière visible ;

dans lequel le deuxième signal lumineux est guidé depuis le premier dispositif vers le deuxième dispositif à l’intérieur du vitrage, depuis un point d’entrée dans le vitrage situé sur une première partie périphérique du vitrage vers un point de sortie situé sur une deuxième partie périphérique du vitrage, opposée à la première tranche du vitrage.A first aspect of the invention thus relates to a communication method in a system comprising a first device and a second device, the first device and the second device being arranged on either side of a glazing, the method being implemented by the first device and comprising:

• receiving a first light signal carrying a data stream via visible light communication technology, the data stream comprising a subset of data;
• transmitting a second light signal carrying the subset of data to the second device via visible light communication technology;

wherein the second light signal is guided from the first device to the second device inside the glazing, from an entry point in the glazing located on a first peripheral portion of the glazing to an exit point located on a second peripheral portion of the glazing, opposite the first edge of the glazing.

In the following, the first device and the second device are also referred to as “communication devices”.

The data subset comprises at least one data item of the data stream, and may, in some embodiments, comprise all of the data in the data stream. In other embodiments, the data stream comprises data other than the data subset, such other data being, for example, for controlling user equipment connected to the first device.

By “arranged on either side of a glazing”, we mean a relative arrangement of the first device, the glazing and the second device allowing the second light signal to be guided inside the glazing, in the thickness of the glazing, from an entry point near the first device (for example opposite a light emitter of the first device) to an exit point near the second device (for example opposite a photoreceiver of the second device).

By "peripheral part" of the glazing is meant a part of the glazing located near an edge or inside an edge of the glazing, so that the light signal propagates inside the glazing. For example, the peripheral part can be an edge of the glazing, but the invention is not limited to this example. Different embodiments are thus shown in . In the example at the very top of the (Figure 7a), the light emitter 701 (for example a light-emitting diode) is located in front of an edge 703 of the glazing (or a sheet of glazing) 702. The light signal therefore enters through an entry point 704 located on the edge 703 and propagates in the thickness of the glazing or the sheet 702. In the example of the middle of the (Figure 7b), the light emitter 701 is located near an edge of the glazing or sheet 702, and the light signal enters the glazing or sheet 702 via an entry point 704 located on a face 705 of the glazing or sheet 702. In the example at the bottom of the (Figure 7c), the light emitter 701 is located in a cavity or directly inside (i.e. in the thickness) of the glazing 702, and the light signal enters the glazing 702 through an entry point 704 located on a surface of the cavity or directly in the thickness of the glazing 702.

The entry point may be located on a first edge of the glazing. The exit point may be located on a second edge of the glazing, opposite the first peripheral part of the glazing and preferably opposite the first edge of the glazing. By “edge” of the glazing, is meant the thickness of the glazing, i.e. the thin edge of the glazing. In other words, the second light signal propagates in the thickness of the glazing, remaining inside it from the entry point to the exit point. It does not “cross” the glazing in a direction perpendicular to the plane of the glazing, it remains confined (at least for the greater part of the light signal, because there may possibly be diffraction or diffusion inside the glazing) inside the glazing.

By "first slice" and "second slice opposite the first slice of the glazing", it is broadly understood two portions of the thickness of the glazing located on either side relative to a median axis of the glazing, separating a half-plane containing the first device and a half-plane containing the second device. Examples are shown in .

For example, as shown in Figure 6a, if the glazing is rectangular in shape, the entry point 601 may be located on one side 602 of the rectangle, in the edge of the glazing, and the exit point 603 may be located on the opposite side 604 of the rectangle, in the edge. In this example, the entry point 601 and the exit point 603 are arranged symmetrically with respect to the median axis 605 of the glazing, substantially at the same height H with respect to the base of the rectangle, but this is not obligatory. For example, as shown in Figure 6c on a glazing in the shape of a parallelogram, the entry and exit points may be located on either side of the median axis, at different heights with respect to the base of the glazing.

If the glazing is circular in shape, as shown in Figure 6b, the entry point 601 may be located on the portion of the contour of a first side relative to the median axis 605, in the edge of the glazing, and the exit point 603 may be located on the portion of the contour of the other side relative to the median axis 605, in the edge of the glazing.

It is noted that the invention is not limited to these particular forms of glazing and can be applied to any form of glazing. Furthermore, other configurations of the invention could be used, for example with an exit point located not on an opposite side of the entry point, but for example on an adjacent side.

Thus, according to the invention, the data are advantageously guided from the first device to the second device through the glazing located between the two devices. This makes it possible to benefit from the advantages of visible light communication technology, without suffering from the disadvantages, in particular the risk of obstruction of the light flux by an obstacle.

• convertir, par le photorécepteur, le premier signal lumineux en un signal électrique ;
• extraire, par le module de traitement, le sous-ensemble de données du signal électrique ;
• envoyer, par le module de traitement, le sous-ensemble de données sous forme d’un deuxième signal électrique vers le module de conversion ;
• convertir, par le module de conversion, le deuxième signal électrique en un signal lumineux qui correspond au deuxième signal lumineux ;

dans lequel le deuxième signal lumineux peut être émis par l’émetteur lumineux.In one or more embodiments, the first device may include a photoreceiver, a processing module, a conversion module adapted to convert an electrical signal into a light signal, and a light transmitter. The data stream may be received by the photoreceiver, and the emission of the second light signal may include:

• convert, by the photoreceptor, the first light signal into an electrical signal;
• extract, by the processing module, the subset of data from the electrical signal;
• sending, by the processing module, the subset of data in the form of a second electrical signal to the conversion module;
• converting, by the conversion module, the second electrical signal into a light signal which corresponds to the second light signal;

in which the second light signal can be emitted by the light transmitter.

• émettre, par le premier dispositif, le groupe de données vers un équipement utilisateur.

In one or more embodiments, the data stream further comprises a data group. The method may further comprise:

• transmit, by the first device, the data group to a user equipment.

By “data group” is meant data in the data stream other than the data subset. The data group and the data subset may be mutually exclusive or have common data. In addition, the data stream may include data that does not belong to either the data group or the data subset.

“User equipment” means an electronic device, for example a touch pad, a personal digital assistant, or any digital device capable of broadcasting data or controlling equipment configured to broadcast data (for example one or more speakers, one or more screens, etc.).

The data group may include, for example, data intended to control the user equipment to broadcast content (e.g. video, audio, multimedia content).

• extraire, par le module de traitement, le groupe de données du signal électrique ;
• émettre, par le module de traitement, le groupe de données vers l’équipement utilisateur via un canal de communication entre le module de traitement et l’équipement utilisateur.

In particular, transmitting the data group to the user equipment may comprise, in one or more embodiments:

• extract, by the processing module, the data group from the electrical signal;
• transmitting, by the processing module, the data group to the user equipment via a communication channel between the processing module and the user equipment.

For example, the transmission of the data group from the processing module to the user equipment may be performed via a communication channel between the processing module and the user equipment, the communication channel being wired or wireless by radio frequencies.

In one or more embodiments, the photoreceiver may include at least one photovoltaic cell, and electrical energy obtained from the at least one photovoltaic cell may be used to power the light emitter.

Electrical energy can also be used to power the photoreceptor, the processing module and/or the conversion module.

Thus, the first device comprises means for powering the light emitter and possibly the other elements that constitute it using photovoltaic solar energy collected by the photoreceiver, which advantageously makes it possible to obtain a “self-powered” device and thus to reduce the energy consumption coming from the electrical network. Of course, it is possible to provide a “hybrid” power supply (by the at least one photovoltaic cell and by the electrical network), so that the device can be powered even when the sunshine is insufficient.

In one or more embodiments, the system may further include a source device; and the first light signal may be received, by the first device, from the source device.

In these embodiments, the source device has a structure similar to the first device, in the sense that it is configured to emit light signals carrying data, by a visible light communication technology. The source device and the first device are then on either side of another glazing, the light signals exchanged between the source device and the first device being guided inside this other glazing.

Alternatively, the source device may be connected, for example by wire, to another communication device having a structure similar to the first device, and it is this other communication device which receives the data stream by wire from the source device, and which transmits it by visible light communication to the first device, via a light signal guided inside a glazing arranged between this other communication device and the first device.

• recevoir un premier signal lumineux préliminaire transportant des données correspondant à une demande d’un contenu numérique depuis le deuxième dispositif via une technologie de communication par lumière visible ;
• émettre les données correspondant à la demande du contenu numérique vers le dispositif source sous forme d’un deuxième signal lumineux préliminaire ;

dans lequel le sous-ensemble de données peut comprendre des données associées au contenu numérique, et dans lequel le premier signal lumineux peut être reçu depuis le dispositif source en réponse à l’émission des données correspondant à la demande du contenu numérique sous forme du deuxième signal préliminaire.When the first light signal is received, by the first device, from the source device, the method may further comprise, at the first device, and before receiving the first light signal:

• receiving a first preliminary light signal carrying data corresponding to a request for digital content from the second device via visible light communication technology;
• transmit the data corresponding to the digital content request to the source device in the form of a second preliminary light signal;

wherein the data subset may include data associated with the digital content, and wherein the first light signal may be received from the source device in response to the transmission of data corresponding to the request for the digital content as the second preliminary signal.

By “digital content”, or simply “content”, we mean any type of data in digital form, for example a photo, a video, music, text (an article, a travel guide, a dictionary, etc.), etc.

For example, computer content may be text, video, audio or multimedia content.

Thus, according to these embodiments, a content request is sent from the second device to the first device, which transmits this content request to the source device. In response, the source device returns the data associated with the content (also called “content data”) to the first device, which retransmits them to the second device. A communication chain is thus obtained, in which the data is sent at least partially by light (“at least partially”, because within the communication devices, the data can be transported between the photoreceiver and the light emitter by another type of communication, for example by wire) between the different devices. This makes it possible to centralize the management of content requests with a single entity (the source device), which can for example have access to a memory storing the content data.

In one or more embodiments, the first device may further include a second light emitter, and the second preliminary light signal may be emitted by the second light emitter.

Thus, according to these embodiments, the first device comprises two light emitters: one for sending data to the second device, and another for sending data to the source device. This makes it possible to place the light emitters as close as possible to the respective entry points of the light signals, and thus to limit the effects of light diffusion, and therefore data losses or distortions.

Further, the first device may include a second photoreceiver, wherein the first preliminary light signal is received by the second photoreceiver.

Thus, the first device comprises two photoreceivers: one to receive data from the source device and another to receive data from the second device. Again, this makes it possible to place the photoreceivers as close as possible to the respective output points of the light signals, and thus to limit the effects of light diffusion, and therefore data losses or distortions.

• un photorécepteur pour recevoir un premier signal lumineux transportant un flux de données via une technologie de communication par lumière visible, le flux de données comprenant un sous-ensemble de données ;
• un émetteur lumineux pour émettre un deuxième signal lumineux transportant le sous-ensemble de données vers le deuxième dispositif via une technologie de communication par lumière visible ;

dans lequel le deuxième signal lumineux peut être guidé depuis le premier dispositif vers le deuxième dispositif à l’intérieur du vitrage, depuis un point d’entrée dans le vitrage situé sur une première partie périphérique du vitrage vers un point de sortie situé sur une deuxième partie périphérique du vitrage, opposée à la première partie périphérique du vitrage. Le deuxième dispositif peut comprendre un photorécepteur pour recevoir le deuxième signal lumineux et extraire le sous-ensemble de données du deuxième signal lumineuxAnother aspect of the invention relates to a communication system comprising a first device, a second device and a glazing, the first device and the second device being arranged on either side of the glazing. The first device may comprise:

• a photoreceiver for receiving a first light signal carrying a data stream via visible light communication technology, the data stream comprising a subset of data;
• a light transmitter for emitting a second light signal carrying the subset of data to the second device via visible light communication technology;

wherein the second light signal can be guided from the first device to the second device inside the glazing, from an entry point in the glazing located on a first peripheral portion of the glazing to an exit point located on a second peripheral portion of the glazing, opposite the first peripheral portion of the glazing. The second device can comprise a photoreceiver for receiving the second light signal and extracting the data subset of the second light signal

• un module de traitement configuré pour extraire le sous-ensemble de données du signal électrique et pour envoyer le sous-ensemble de données sous forme d’un deuxième signal électrique ;
• un module de conversion configuré pour recevoir le deuxième signal électrique et convertir le deuxième signal électrique en un signal lumineux qui correspond au deuxième signal lumineux.

The photoreceiver of the first device may further be configured to convert the first light signal into an electrical signal, and the first device may further comprise:

• a processing module configured to extract the data subset from the electrical signal and to send the data subset as a second electrical signal;
• a conversion module configured to receive the second electrical signal and convert the second electrical signal into a light signal that corresponds to the second light signal.

In one or more embodiments, the above system may be incorporated into a vehicle. Thus, another aspect of the invention relates to a vehicle comprising the above system. For example, the glazing may correspond to a side window of the vehicle. The vehicle may be a car, a train, an airplane or any other means of transportation equipped with glazing.

• un émetteur lumineux pour envoyer au premier dispositif un premier signal lumineux transportant un flux de données via une technologie de communication par lumière visible, le flux de données comprenant un sous-ensemble de données, le premier signal lumineux étant guidé depuis le dispositif source vers le premier dispositif à l’intérieur du premier vitrage, depuis un point d’entrée dans le premier vitrage situé sur une première partie périphérique du premier vitrage vers un point de sortie situé sur une deuxième partie périphérique du premier vitrage, opposée à la première partie périphérique du premier vitrage ;

le premier dispositif peut comprendre :

• un photorécepteur pour recevoir le premier signal lumineux transportant le flux de données ;
• un émetteur lumineux pour envoyer un deuxième signal lumineux transportant le sous-ensemble de données parmi le flux de données vers le deuxième dispositif via une technologie de communication par lumière visible, le deuxième signal lumineux étant guidé depuis le premier dispositif vers le deuxième dispositif à l’intérieur du deuxième vitrage, depuis un point d’entrée dans le deuxième vitrage situé sur une première partie périphérique du deuxième vitrage vers un point de sortie situé sur une deuxième partie périphérique du deuxième vitrage, opposée à la première partie périphérique du deuxième vitrage ;

et le deuxième dispositif peut comprendre un photorécepteur pour recevoir le deuxième signal lumineux et extraire le sous-ensemble de données du deuxième signal lumineux.Another aspect of the invention relates to a communication system comprising a source device, a first device and a second device, and a first glazing and a second glazing, wherein the source device and the first device are located on either side of a first glazing, and the first device and the second device are located on either side of a second glazing. The source device may comprise:

• a light transmitter for sending to the first device a first light signal carrying a data stream via visible light communication technology, the data stream comprising a subset of data, the first light signal being guided from the source device to the first device within the first glazing, from an entry point in the first glazing located on a first peripheral portion of the first glazing to an exit point located on a second peripheral portion of the first glazing, opposite the first peripheral portion of the first glazing;

the first device may include:

• a photoreceiver for receiving the first light signal carrying the data stream;
• a light transmitter for sending a second light signal carrying the subset of data among the data stream to the second device via visible light communication technology, the second light signal being guided from the first device to the second device within the second glazing, from an entry point in the second glazing located on a first peripheral portion of the second glazing to an exit point located on a second peripheral portion of the second glazing, opposite the first peripheral portion of the second glazing;

and the second device may include a photoreceiver for receiving the second light signal and extracting the data subset from the second light signal.

The first device may further include a second photoreceiver and a second light emitter, the second photoreceiver configured to receive a light signal emitted from the second device to the first device, the second light emitter configured to emit a light signal from the first device to the source device.

In one or more embodiments, at least one glazing among the first glazing and the second glazing may be a laminated glazing.

This type of glazing advantageously allows specific techniques to be implemented to guide light waves inside the glazing, from a given entry point to a given exit point. Of course, other types of glazing can be used.

The laminated glazing may comprise a first glass sheet, a second glass sheet and an interlayer separating the first glass sheet and the second glass sheet. A light signal, in particular the second light signal, may be guided from the first device to the second device by at least one glass sheet selected from the first glass sheet and the second glass sheet, in particular by total internal reflection. The first glass sheet and/or the second glass sheet may be formed by a glass having an absorption coefficient of less than 0.5 cm ^-1 and preferably less than 0.1
cm ^-1 , for a wavelength of the light signal included in the visible spectrum or in the infrared spectrum.

A light signal, in particular the second light signal, may be guided by an optical fibre of the glazing. The optical fibre may be laminated and/or bonded between two sheets of glass of the glazing so as to connect the entry point to the exit point.

In one or more embodiments, the above system may be integrated into a vehicle. Another aspect of the invention thus relates to a vehicle comprising the above system. For example, the first glazing and the second glazing may correspond to side windows of the vehicle. The vehicle may be a car, a train, an airplane or any other means of transport equipped with glazing.

As mentioned above, the invention is particularly advantageous in environments such as vehicles, in which wired communications pose space problems and in which radio frequency communications are difficult to implement. Of course, the present invention applies to other environments comprising glazing, for example as an alternative to radio frequency communication systems.

In one or more embodiments, the first device may be located less than a predetermined threshold distance from a first seat of the vehicle, the second device may be located less than the predetermined threshold distance from a second seat of the vehicle, the first seat and the second seat being located in two separate rows of the vehicle.

In other words, in these embodiments, the devices may be arranged relative to rows of the vehicle, thereby minimizing wired connections to user equipment, which may be arranged at passenger seats.

A computer program, implementing all or part of the process described above, installed on pre-existing equipment, is in itself advantageous.

Thus, the present invention also relates to a computer program comprising instructions for implementing certain steps of the method described above, when this program is executed by a processor.

This program may use any programming language (e.g., an object language or otherwise), and may be in the form of interpretable source code, partially compiled code, or fully compiled code.

There described in detail below can form the flowchart of the general algorithm of such a computer program.

The invention and its various applications will be better understood by reading the description which follows and by examining the figures which accompany it.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent upon reading the description, which can be read in conjunction with the figures. These figures are provided for information purposes only and are in no way limiting of the invention.

There represents an example of an environment integrating a system according to an embodiment of the invention.

There represents two possible embodiments for communication devices according to the invention.

There represents an exemplary flowchart of a communication method according to an embodiment of the invention.

There represents steps of a method of communication between different entities of a communication system according to an embodiment of the invention.

There represents an example of a communication device according to an embodiment of the invention.

There represents examples of glazing according to several embodiments of the invention.

There represents examples of light signal input points according to several embodiments of the invention.

DETAILED DESCRIPTION

There represents an example of an environment integrating a system according to an embodiment of the invention.

In the example shown in the , the environment is the interior of a train. Of course, the invention is not limited to such an environment, and can be implemented whenever the environment includes glazing.

On the , four seats 101a, 101b, 101c, 101d are shown, and are assumed, for this example, to be arranged in four separate rows of the train. Between the seats 101a and 101b is shown a first side window 102a, and between the seats 101c and 101d is shown a second side window 102b. Between the two windows 102a, 102b is located a communication device (D1) 103. At the other end of the first window 102a (relative to the communication device 103) is shown a communication device called "source device" 104, and at the other end of the second window 102b (relative to the communication device 103) is shown a communication device (D2) 105.

The communication devices (D1, D2) 103, 105 and the source device 104 each comprise at least one light emitter, for example a light-emitting diode (LED) or a laser diode, and at least one photoreceiver (or photodetector), for example a PIN-type silicon photodiode or a photovoltaic module (i.e. a module comprising at least one photovoltaic cell), configured to receive light and convert it into an electrical signal. The devices may also each comprise at least one processing module for processing the received data and a conversion module for converting electrical signals into light signals (and therefore generating light signals carrying data).

When the at least one photoreceiver is a photovoltaic module, it is possible to power the light emitter with the electrical energy recovered by the photovoltaic module. Thus, the energy consumption of the communication device is advantageously reduced.

On the example of the , the source device 104 is connected to a user equipment (UE1) 106a, the communication device 103 is connected to two user equipments (UE2 and UE3) 106b and 106c, and the communication device 105 is connected to a user equipment (UE4) 106d. Each user equipment 106a, 106b, 106c, 106d is, in this illustrative example, respectively associated with a seat 101a, 101b, 101c, 101d. Of course, the invention is not limited to this example.

On the example of the , the user equipment 106a associated with the seat 101a is connected directly to the source device 104. Other configurations are possible. For example, the user equipment 106a may be connected to a communication device other than the source device 104, this communication device being configured to communicate, directly (for example by wire) or indirectly (for example via other communication devices) with the source device 104.

The connection between a communication device 103, 105/the source device 104 and the user equipment(s) 106a, 106b, 106c, 106d to which it is connected may be any type of connection, for example a Bluetooth, BLE, Zigbee, Z-wave, Wi-Fi wireless connection or a wired connection. Preferably, since environments such as the interior of a train are not suitable for radio frequency communications, the connection is wired.

The user equipments 106a, 106b, 106c, 106d can be, for example, any device integrating a processor, for example a computer or a tablet, configured to send control signals to computing devices, for example a personal telephone, one or more loudspeakers, one or more microphones, a game console, etc. Each user equipment 106a, 106b, 106c, 106d can control several devices, for example a touch pad, one or more microphones and one or more loudspeakers. By means of the user equipments 106a, 106b, 106c, 106d, the passengers of the train (for the example of the ) can access various types of content, such as text (e.g. viewing a web page or an e-book), audio content (e.g. music or an audio book), video content (e.g. photos or movies) or any multimedia content (e.g. a video game). Typically, a passenger can request content via the user equipment 106a, 106b, 106c, 106d associated with his seat 101a, 101b, 101c, 101d and receive this content either directly on the user equipment 106a, 106b, 106c, 106d (when it is a tablet for example), or on the devices controlled by the user equipment 106a, 106b, 106c, 106d. For example, the passenger can request, via his user equipment 106a, 106b, 106c, 106d, to listen to music, and in return for this request the user equipment 106a, 106b, 106c, 106d receives data corresponding to the requested music and sends them to one or more speakers integrated into his seat 101a, 101b, 101c, 101d, at head level.

Preferably, the data corresponding to the different contents are stored at the source device 104. Thus, when a passenger requests content via his user equipment 106a, 106b, 106c, 106d, the content request must be sent to the source device 104 which returns, in response to this request, data corresponding to the requested content.

In a vehicle such as a train, providing wired connections from each user equipment 106a, 106b, 106c, 106d to the source device 104 would be too bulky and complex to install. Furthermore, as mentioned before, a solution using radio frequency communication is not suitable for this type of environment. Thus, according to the invention, it is proposed to use the glazings 102a, 102b as partial supports for the transport of information.

More specifically, when a content request is made, for example, on the user equipment (UE4) 106d, this content request is transmitted to the communication device (D2) 105 to which the user equipment (UE4) 106d is connected. As mentioned previously, this transmission can advantageously be made via a wired link between the user equipment (UE4) 106d and the communication device (D2) 105 associated with it. However, any other communication link can be used. At the communication device (D2) 105, the content request is converted into a light signal (S1p) 107, and this light signal is transmitted to the communication device (D1) 103 via the window 102b located between the two communication devices 105 and 103. The light signal (S1p) 107 is received by the communication device (D1) 103, which retransmits it to the source device 104 via the window 102a. More specifically, the communication device (D1) 103 receives the light signal, converts it into an electrical signal, reconverts it into a new light signal (S2p) 108 and sends it to the source device 104 via the window 102a located between the communication device (D1) 103 and the source device 104. The new light signal (S2p) 108 carries the data associated with the initially sent content request, and can also carry other data, for example a content request sent by one of the equipment (UE2, UE3) 106b, 106c connected to the device (D1) 103.

The source device 104 receives the light signal (S2p) 108, extracts therefrom the data corresponding to the content request emitted by the user equipment (UE4) 106d, and retrieves, for example from a storage device connected to or integrated into the source device 104, data – called content data – corresponding to the requested content. Then, the source device 104 converts this content data, as well as possibly other data, into a light signal (S1) 109 and emits this light signal (S1) 109 towards the communication device (D1) 103, using the window 102a as transmission medium. Then, as before, the communication device (D1) 103 converts this light signal (S1) 109 into an electrical signal, extracts therefrom the content data which correspond to the requested content, and converts this content data – possibly with other data – into a light signal (S2) 110. The communication device (D1) 103 then transmits the obtained light signal (S2) 110 to the communication device (D2) 105 via the window 102b.

Another possible application of the system shown in relates to the generation of "bubbles of silence". By "bubble of silence" is meant an area, preferably located near the head of a user, in which active noise control is performed. For example, the user equipment 106a, 106b, 106c, 106d can control at least one microphone and at least one loudspeaker integrated into the seat 101a, 101b, 101c, 101d of the passenger, and the passenger can request, via the user equipment 106a, 106b, 106c, 106d dedicated to him, that a bubble of silence be created around him. The user equipment 106a, 106b, 106c, 106d can then control the at least one microphone to retrieve the ambient sound data and send this data to the source device 104. The source device 104 can then either process this data itself or send it to a computer, to generate noise reduction audio data (generation of a signal that “opposes” the ambient noise, according to known techniques). This audio data is then sent to the user equipment 106a, 106b, 106c, 106d, which can control the at least one loudspeaker to broadcast said data.

The generation of light signals from the data to be transmitted and the reception of these light signals can be carried out using any wireless communication technique using light, in particular visible light. For example, Li-Fi technology can be used.

The main steps of visible light wireless communication techniques are recalled here. These techniques are well known and are not detailed further here. First, the digital data to be transmitted are encoded, then converted into a light signal using an electronic circuit controlling one or more light emitters, for example one or more LEDs. The light signal is received by a photoreceiver (or photodetector), for example a photodiode, which converts it into an electrical signal. This electrical signal is processed, then demodulated and decoded to recover the digital data.

Thus, according to the invention, the windows 102a, 102b are used as a transmission medium for the light signals carrying the information (i.e. the data). More precisely, the windows are used to guide the light signals from an entry point located for example on the peripheral part of a window to an exit point located on the opposite peripheral part of the window. The entry point may be located on a first edge of the glazing. The exit point may be located on a second edge of the glazing, opposite the first peripheral part of the glazing and preferably opposite the first edge of the glazing. By “edge” is meant one of the thin edges of the window. In other words, the light signal is transported within the thickness of the window, in the plane of the window (and not substantially perpendicular to the window, as is the case, for example, when a light source is placed behind a non-opaque window and the light signal “passes through” the window, so that an individual located on the other side can see the light signal).

Preferably, the light emitter is located near the edge of the window where the entry point is located, to avoid excessive dispersion and distortion of the signal. Indeed, at the output of the light emitter, the light signal has the shape of a light cone, the section of which increases with the distance from the light emitter. Similarly, the photoreceptor is located near the exit point of the light signal, again to avoid excessive dispersion and distortion of the signal.

Possible embodiments for communication devices 103, 104, 105 according to the invention are shown in FIG. .

In the first embodiment shown at the top of the , the communication device (D1) 103 comprises a photoreceiver 201, and two light emitters 202, 203. The first light emitter 202 is used to emit light signals to transport information to the source device 104. The second light emitter 203 is used to emit light signals to transport information to the communication device (D2) 105. According to this embodiment, it is assumed that the photoreceiver 201 of the communication device (D1) 103 is located “centrally”, which allows it to detect the light signals emitted from the source device 104 (for example the signal S1) as well as the light signals emitted from a neighboring communication device (D2) 105 (for example the signal S1p).

The source device 104 is, in the example shown, assumed to communicate directly (i.e. receive light signals from or emit light signals to) only with the communication device (D1) 103. Thus, the source device 104 may comprise a single light emitter 204 for emitting light signals carrying information to the communication device (D1) 103. The source device 104 may also comprise a photoreceiver 205 for receiving the light signals emitted by the communication device (D1) 103 (e.g. S2p).

The communication device (D2) 105 is, in the example shown, assumed to communicate directly only with the communication device (D1) 103. Thus, the communication device (D2) 105 may comprise a single light emitter 206 for emitting light signals carrying information to the communication device (D1) 103. The communication device (D2) 105 may also comprise a photoreceiver 207 for receiving the light signals emitted by the communication device (D1) 103 (for example S2).

Of course, the communication device (D2) 105 may comprise at least one other light emitter, for sending light signals to another communication device. Similarly, the source device 104 may comprise at least one other light emitter, for sending light signals to another communication device.

In the example at the top of the , the photoreceptors 205, 207 of the source device 104 and of the communication device (D2) 105 are centrally arranged in the device, in a manner similar to the communication device (D1) 103, but this arrangement is not mandatory. For example, the photoreceptors 205, 207 may be located near the output points of the light signals received by the devices (in the example of the Figure, the output points of the signals S2 and S2p), as is the case in the example at the bottom of the . In the case where the source device 104 and/or the communication device (D2) 105 is at the “end” of the device chain (i.e. it communicates with only one other device), this configuration is preferable, because it makes it possible to detect the light signal as close as possible to its output point, and thus to minimize losses and distortions of information.

As mentioned above, the photoreceivers 201, 205, 207 are configured to receive light signals and convert them into electrical signals. These electrical signals can be sent to a processing module to process the received data. In particular, the processing module is configured to demodulate and decode the electrical signals, extract the data from the signals, send, if necessary, certain data to one or more user devices, and generate new electrical signals containing the data to be transmitted to another communication device 103, 105 or to the source device 104. The processing module can typically be configured to “route” the data transported by the light signals to the communication device 103, 104, 105 or the user equipment 106a, 106b, 106c, 106d for which they are intended. For example, this routing can be implemented from a field associated with a data packet indicating the recipient of this data packet.

The new electrical signals generated can be sent to a conversion module in order to be converted into light signals intended to be emitted by the light emitter 202, 203, 204, 206 of the device 103, 104, 105 concerned.

Thus, the devices 103, 104, 105 can each further comprise a processing module and a conversion module (not shown in the ). For each device 103, 104, 105, the connections between the photoreceiver, the processing module, the conversion module and the light emitter may be, for example, wired connections.

In the example shown at the bottom of the , the source device 104 and the communication device (D2) 105 have structures similar to the previous example – except for the photoreceivers 205, 207, arranged near the output points of the signals coming from the communication device (D1) 103 (in the Figure, the signals S2p and S2). The main difference with the previous embodiment is that the communication device (D1) 103 comprises two separate photoreceivers 201a, 201b, for receiving the light signals coming from the source device 104 and coming from the other communication device (D2) 105, respectively. When the distance between the two glazings 102a, 102b is large, this configuration is preferable, to avoid significant losses and/or distortions of the information to be transmitted.

Referring again to the , in one or more embodiments, each communication device 103 located between two glazings 102a, 102b can be completely integrated into the portion of the train body corresponding to the area between the two glazings 102a, 102b. For example, the light flux 109 (S1) can exit through an exit point located on an edge 111 of the window 102a, and a photoreceptor 201, 201a can be arranged inside the part of the body located between the two glazings 102a, 102b, opposite this exit point. Similarly, the light emitter 203 can be inside the body, so that the light flux enters through an entry point located on an edge 112 of the window 102b.

To guide the light flux inside the glazing from an entry point located, for example, on a first edge 112 of a window 102b to an exit point located, for example, on the opposite edge 113, any method known from the state of the art can be used, for example a method disclosed in document WO2018/178591 or in document WO2015/118279. Thus, in some embodiments, the glazings 102a, 102b can be laminated glazings. Other embodiments are possible, for example the glazings 102a, 102b can be single glazings in which the light signals are guided from an entry point to an exit point by means of an optical fiber.

There represents an example of a flowchart of a communication method according to an embodiment of the invention. The method can be implemented, for example by the communication device (D1) 103 of the .

At a step 310, a first light signal (S1) 109 can be received by the communication device (D1) 103. This first light signal (S1) 109 can typically transport data transmitted by the source device 104. For example, part of this data can be intended for the communication device (D1) 103, to control one or more user equipments 106b, 106c, and another part of the data can be intended for one or more other communication devices, in particular the communication device (D2) 105.

As described in detail above, this signal can then be converted into an electrical signal by at least one photoreceiver 201, 201a of the communication device (D1) 103 in a step 320, and the data of the electrical signal can be processed (for example, demodulated and decoded, then routed – with on the one hand the data which must be transmitted to another communication device 105 and on the other hand the data for controlling the user equipments 106b, 106, and finally encoded – at least for the data which must be transmitted to another communication device 105) by a processing module in a step 330.

A second light signal carrying the data to be transmitted to another communication device 105 is then generated during a step 340. For example, an electrical signal containing this data can be converted into a second light signal by the processing module of the communication device (D1) 103. The communication device (D1) 103 then emits this second light signal (step 350) using a light emitter 203.

The data for controlling one or more user devices 106b, 106c may be processed to generate (step 360) and transmit (step 370) a control signal (step 360) to the user device(s) 106b, 106c concerned. For example, the control signal may be a control signal of a loudspeaker carrying audio data.

Of course, the other communication device (D2) 105 to which the second light signal was sent during step 350 can in turn implement the steps of the , to route certain data to another communication device and generate control signals from other data. Thus, the invention advantageously makes it possible to create a partly wireless communication network, by placing in series a plurality of communication devices connected two by two by glazing, the glazing making it possible to transport the information from one communication device to the other. This results in a "chain" of connected communication devices, at least one of which is connected "directly" to the source device (either by wire or by a single glazing). This source device can advantageously centralize all the content and/or the most costly processing in terms of computing resources (for example to create a bubble of silence for a passenger). The network obtained is suitable for an environment such as a vehicle, in which radiofrequency communication is difficult to implement, because it limits the number of wired connections, and makes it possible to use the glazing present effectively to transport the data. Of course, the invention is not limited to vehicle interiors, it can be used in any environment provided with glazing, for example as an alternative to radio frequency communication.

There represents steps of a method of communication between different entities of a communication system according to an embodiment of the invention.

First, a content request may be sent from a user equipment (A2) to the communication device (D2) to which it is connected. This content request may be sent, for example, via a human-machine interface. A light signal (S1p) containing data corresponding to this content request may then be generated by the communication device (D2). This signal (S1p) may then be sent to a communication device (D1) located between the communication device (D2) and the source device. The communication device (D1) receives the light signal (S1p), converts it into an electrical signal, then generates a new light signal (S2p) which it emits to the source device. It is noted that the new light signal (S2p) may carry other data, for example data corresponding to a content request from one of the user equipment (A2, A3) to which it is connected, and/or data corresponding to a content request from another user equipment connected to yet another communication device.

The source device then converts the light signal (S2p) into an electrical signal, and processes the data contained in the electrical signal obtained. In particular, the source device extracts the data corresponding to the initial content request, and generates a new light signal (S1) comprising the data relating to the requested content. Of course, the new light signal (S1) may comprise other data, for example intended for other communication devices than the one (D2) which made the initial content request.

This new light signal (S1) is emitted to the communication device (D1). Upon receipt of this light signal (S1), the communication device (D1) processes the received data, extracts the data intended to be sent to the communication device (D2), and transmits them to it via a final light signal (S2). The communication device (D2) can then process the received signal to extract data corresponding to the requested content and send them to the user equipment (A2), for example in the form of a control signal, as detailed above.

There represents an example of a communication device according to an embodiment of the invention.

In this embodiment, the communication device 500 comprises a computer 501, comprising a memory 502 for storing instructions allowing the implementation of the method described with reference to the , and temporary data to carry out different steps of this process.

The computer 501 further comprises a circuit 503. This circuit may be, for example, a processor capable of interpreting instructions in the form of a computer program, an electronic card whose steps of the method of the invention are described in the silicon, or even a programmable electronic chip such as an FPGA chip (for “Field-Programmable Gate Array” in English). This circuit may comprise the processing module and/or the conversion module described above. The computer 501 may further comprise an output interface 506 for delivering control signals to user equipment to which the device 500 is connected.

The device 500 comprises a set 504 of at least one photoreceiver for receiving light signals and converting them into electrical signals. The set 504 of at least one photoreceiver is configured to send said electrical signals to the circuit 503. The computer 501 also comprises a set 505 of at least two light emitters for emitting light signals generated by the circuit 503.

The device 500 shown in the may be, in some embodiments, one of the communication devices 103, 105 of the . The source device 104 has, in embodiments, a structure similar to that of the device 500 shown in , and may further include access to an external memory or data server, the external memory or server being able, for example, to store content data intended for the various user devices.

Furthermore, the functional diagram presented on the is a typical example of a program some of whose instructions can be carried out on the device described. As such, the may correspond to the flowchart of the general algorithm of a computer program within the meaning of the invention.

Of course, the present invention is not limited to the embodiments described above as examples. It extends to other variants. For example, as mentioned above, the implementation of the invention is not limited to an environment corresponding to the interior of a vehicle, but can be extended to any environment comprising glazing. Furthermore, if the invention has been described in the context of a chain (similar to a topology called "daisy chain" in English) of three communication devices (including a source device), it can be extended to any network topology, and to any number of communication devices. Furthermore, some of these devices can be connected via a wired link, while others can be, according to the invention, connected by a VLC link using glazing as an information transport vector.

Claims (20)

A method of communication in a system comprising a first device (103) and a second device (105), the first device (103) and the second device (105) being arranged on either side of a glazing (102b), the method being implemented by the first device (103) and comprising:

• receiving (310) a first light signal (109) carrying a data stream via visible light communication technology, the data stream comprising a subset of data;
• transmitting (350) a second light signal (110) carrying the subset of data to the second device via visible light communication technology;

wherein the second light signal (110) is guided from the first device (103) to the second device (105) inside the glazing (102b), from an entry point in the glazing located on a first peripheral part of the glazing to an exit point located on a second peripheral part of the glazing, opposite the first peripheral part of the glazing. The method of claim 1, wherein the first device (103) comprises a photoreceiver (201, 201a), a processing module, a conversion module adapted to convert an electrical signal into a light signal, and a light emitter (203); wherein the data stream is received by the photoreceiver (201, 201a); wherein the emission of the second light signal comprises:

• convert (320), by the photoreceptor, the first light signal into an electrical signal;
• extracting (330), by the processing module, the subset of data from the electrical signal;
• sending (330), by the processing module, the subset of data in the form of a second electrical signal to the conversion module;
• converting (340), by the conversion module, the second electrical signal into a light signal which corresponds to the second light signal;

in which the second light signal is emitted by the light transmitter. A method according to any preceding claim, wherein the data stream further comprises a data group; the method further comprising:

• transmitting (370), by the first device, the data group to a user equipment (106b, 106c).

The method of claim 3 in combination with claim 2, wherein transmitting the data group to the user equipment (106b, 106c) comprises:

• extract, by the processing module, the data group from the electrical signal;
• transmitting, by the processing module, the data group to the user equipment via a communication channel between the processing module and the user equipment.

The method of claim 4, wherein the transmission of the data group from the processing module to the user equipment is performed via a communication channel between the processing module and the user equipment, the communication channel being wired or wireless by radio frequencies. Method according to one of claims 2, 4 and 5, in which the photoreceiver (201, 201a) comprises at least one photovoltaic cell, in which electrical energy obtained from the at least one photovoltaic cell is used to power the light emitter (203). A method according to one of the preceding claims, wherein the system further comprises a source device (104); wherein the first light signal (109) is received, by the first device (103), from the source device (104). The method of claim 7, further comprising, at the first device (103), and before receiving (310) the first light signal (109):

• receiving a first preliminary light signal (107) carrying data corresponding to a request for digital content from the second device (105) via visible light communication technology;
• transmitting the data corresponding to the request for the digital content to the source device (104) in the form of a second preliminary light signal (108);

wherein the data subset comprises data associated with the digital content, and wherein the first light signal (109) is received from the source device (104) in response to the transmission of data corresponding to the request for the digital content in the form of the second preliminary signal (108). The method of claim 8, wherein the digital content is text, video, audio or multimedia content. A method according to one of claims 8 and 9, in combination with claim 2, wherein the first device (103) further comprises a second light emitter (202), and wherein the second preliminary light signal (108) is emitted by the second light emitter (202). The method of claim 10, wherein the first device (103) further comprises a second photoreceiver (201b), wherein the first preliminary light signal (107) is received by the second photoreceiver (201b). Communication system comprising a first device (103), a second device (105) and a glazing (102b), the first device (103) and the second device (105) being arranged on either side of the glazing (102b), the first device (103) comprising:

• a photoreceiver (201, 201a) for receiving (310) a first light signal (109) carrying a data stream via visible light communication technology, the data stream comprising a subset of data;
• a light transmitter (203) for transmitting (350) a second light signal (110) carrying the subset of data to the second device (105) via visible light communication technology;

wherein the second light signal (110) is guided from the first device (103) to the second device (105) inside the glazing (102b), from an entry point in the glazing (102b) located on a first peripheral part of the glazing to an exit point located on a second peripheral part of the glazing, opposite the first peripheral part of the glazing;
wherein the second device (105) comprises a photoreceiver (207) for receiving the second light signal (110) and extracting the data subset from the second light signal (110). The system of claim 12, wherein the photoreceiver (201, 201a) of the first device (103) is further configured to convert (320) the first light signal (109) into an electrical signal, the first device (103) further comprising:

• a processing module configured to extract (330) the data subset from the electrical signal and to send the data subset as a second electrical signal;
• a conversion module configured to receive the second electrical signal and convert the second electrical signal into a light signal that corresponds to the second light signal (110).

A communication system comprising a source device (104), a first device (103) and a second device (105), and a first glazing (102a) and a second glazing (102b), wherein the source device (104) and the first device (103) are located on either side of the first glazing (102a), and the first device (103) and the second device (105) are located on either side of the second glazing (102b);
wherein the source device (104) comprises:

• a light transmitter (204) for sending to the first device a first light signal (109) carrying a data stream via visible light communication technology, the data stream comprising a subset of data, the first light signal (109) being guided from the source device (104) to the first device (103) inside the first glazing (102a), from an entry point in the first glazing (102a) located on a first peripheral portion of the first glazing to an exit point located on a second peripheral portion of the first glazing, opposite the first peripheral portion of the first glazing;

wherein the first device (103) comprises:

• a photoreceiver (201, 201a) for receiving (310) the first light signal (109) carrying the data stream;
• a light transmitter (203) for sending (350) a second light signal (110) carrying the subset of data among the data stream to the second device (105) via visible light communication technology, the second light signal (110) being guided from the first device (103) to the second device (105) inside the second glazing (102b), from an entry point in the second glazing located on a first peripheral portion of the second glazing to an exit point located on a second peripheral portion of the second glazing, opposite the first peripheral portion of the second glazing;

wherein the second device (105) comprises a photoreceiver (207) for receiving the second light signal (110) and extracting the data subset from the second light signal (110). The system of claim 14, wherein the first device (103) further comprises a second photoreceiver (201b) and a second light emitter (202), the second photoreceiver (201b) being configured to receive a light signal emitted from the second device (105) to the first device (103), the second light emitter (202) being configured to emit a light signal from the first device (103) to the source device (104). System according to one of claims 14 and 15, in which at least one glazing among the first glazing (102a) and the second glazing (102b) is a laminated glazing. Vehicle comprising a system according to one of claims 14 to 16. Vehicle according to claim 17, wherein the first glazing (102a) and the second glazing (102b) correspond to side windows of the vehicle. System according to one of claims 16 and 17, wherein the first device (103) is located at a distance less than a predetermined threshold from a first seat (101b, 101c) of the vehicle, wherein the second device (105) is located at a distance less than the predetermined threshold from a second seat (101d) of the vehicle, the first seat and the second seat being located on two separate rows of the vehicle. Computer program product comprising instructions for implementing the method according to one of claims 1 to 11 when this program is executed by a processor.