METHOD AND DEVICE FOR GENERATING A SIGNAL IN A NETWORK OF CONNECTED OBJECTS

Description

Background of the invention

[0001] The invention relates to the general field of radio communications.

[0002] It concerns more particularly communications, for example by radio, of objects or equipment connected to a communications network (also called "connected objects") and deployed in a more or less extensive geographical area.

[0003] The invention applies more particularly in the context of networks of connected objects of the IoT (for "Internet of Things" in English) or M2M (for "machine to machine" in English) type which continuously ensure the collection of data, and to the underlying dedicated infrastructure of a service provider capable of providing the data thus collected to one or more clients. This infrastructure is composed in particular of so-called digitization receiving stations or receiving equipment which allow the collection of data and their transmission in the form of packets of digital samples to an information system of a client of the service provider. The digital samples are indexed at the level of the information system in a database according to different criteria such as for example criteria of time, place, and frequency. Application EP 2728909 describes such an infrastructure.

[0004] It is therefore clear that localization in both time and space is central to networks of connected objects that use indexing according to this type of criteria. Such localization is based in particular on dating the digital samples. For the purposes of the invention, "data dating" means the association with this data of precise time stamp information, for example in the form of date (Year, Month, Day) and time (Hours: Minutes: Seconds).

[0005] In the current state of the art, data dating is carried out at the digitization receiving stations during the formation of digital sample packets. Each receiving station must be equipped for this purpose with a synchronization device capable of locally recovering a time reference (e.g. a common clock broadcast by GPS signal (for "Global Positioning System", in English), or a radio-controlled clock), of synchronizing this time reference with respect to the digital sampling clock of the digitization receiving station, of extracting and associating with the samples dating information established from the synchronized common time reference, and of integrating this information into the header of the sample packets to be transmitted to the information system.

[0006] These operations, depending on the desired dating accuracy, impose significant hardware and / or software constraints on receiving stations and can lead to significant implementation costs.

[0007] Furthermore, this complexity and costs must be borne by the receiving stations even if the dating information is not ultimately used by the service provider's customer information system.

[0008] Document US 2009 / 0173839 A1 describes a system for time-stamping temperature data acquired by sensors on board a train and transmitting this time-stamped data to a remote server. Subject matter and summary of the invention

[0009] The invention is defined in independent claims 1, 6, 8, 9, 11 and 12.

[0010] The invention aims in particular to remedy these drawbacks by proposing, according to a first aspect, a method for generating a signal according to claim 1 intended to be transmitted in a network of connected objects, this method comprising: a step of obtaining a first signal carrying a flow of data acquired by a connected object of the network; a step of receiving a second synchronization signal comprising information providing a dating of the first signal; and a step of generating a third signal by combining according to a reversible operation the first signal and the second synchronization signal, said reversible operation comprising: a frequency multiplexing of the first and second signals on two consecutive frequency bands; or a multiplexing of the first and second signals by orthogonal codes; or a steganographic multiplexing of the first and second signals; or a watermark, the third signal being obtained by superimposing the first and second signals, the second signal being a signal with high spectral density, the first signal being a low density narrowband signal.

[0011] Correlatively, the invention relates to a device for generating a signal according to claim 8.

[0012] For each of these reversible operations, there is a so-called "inverse" operation that can be applied to the third signal and which makes it possible to extract from this third signal the information conveyed by the first signal and by the second synchronization signal. It should be noted that it is not necessary to obtain via this inverse operation a reconstruction of the first and second signals that is perfectly identical to the first and second signals used to generate the third signal. A reconstruction that makes it possible to extract with sufficient quality (e.g. sufficient signal-to-noise ratio) the information (data or dating information) conveyed by the first and second signals is sufficient to be considered reversible within the meaning of the invention.In other words, the notion of reversible operation includes, within the meaning of the invention, orthogonal operations making it possible to restore the first and second signals identically, but also non-orthogonal, “quasi-reversible” operations, which do not lead to the exact restoration (i.e. reconstruction) of the first and second signals since these operations make it possible to extract the information conveyed by these signals.

[0013] It should also be noted that such a generation device according to the invention can be indifferently embedded in various entities of the network of connected objects, such as for example in a digitization receiving station or in a connected object at the origin of the data (e.g. sensor). The processing device according to the invention can be embedded in an information system of a client of the operator of the network of connected objects using the data collected by this network.

[0014] The invention therefore makes it possible to easily associate with data obtained by a connected object, precise dating information for this data, via the third signal, this information being able to be easily extracted from the third signal, on demand. In other words, the first signal conveying the data acquired by the connected object is "marked" in accordance with the invention by dating information. This information is intrinsically contained in the second synchronization signal and is combined in a raw manner with the data acquired by the connected object, that is to say as is without prior processing. The freedom is thus left to the devices receiving the third signal in accordance with the invention to extract if necessary and to exploit this dating information.

[0015] The invention therefore advantageously makes it possible to transfer the task of actually dating the data of the first signal acquired by the connected object, from the receiving equipment / digital receiving station to the entity which needs to date this signal (e.g. the information system hosting the database in which this data is stored).

[0016] In other words, it is no longer a question of dating the acquired data, systematically and locally on the digitization receiving station as in the state of the art, but of carrying out this dating on demand, in a centralized manner, for example at the level of the client's information system which is generally subject to less significant implementation and complexity constraints than the receiving stations.

[0017] Furthermore, the invention makes it possible to improve the accuracy of the dating of the data. The second signal is for example received from a satellite navigation system (e.g. GPS (Global Positioning System), GLONASS, Galileo, etc.). Such a system provides precise and reliable dating information in a known manner. The dating according to the invention directly uses the information included in the second signal without requiring transformation of this information or the operations of the prior art consisting of determining dating information after synchronization between the digitizing receiving station and a common reference, and which can lead to inaccuracies in the dating information obtained. Thus, the solution of the invention improves the accuracy of the dating of the first signal while simplifying the design of the digitizing receiving station.

[0018] By combining the two signals in a reversible manner, the dating information from the data can be easily extracted at low cost.

[0019] A reversible operation considered is a steganographic multiplexing of the first and second signals.

[0020] Such multiplexing consists in a known manner of considering the data carried by the first signal and modifying them as discreetly as possible in order to conceal the information carried by the second signal. In the context of the invention, one way of carrying out such multiplexing may thus consist, for example, in using a few low-order bits of the samples of the first signal to carry bits of the second synchronization signal.

[0021] As mentioned previously, the generation method can be implemented at the level of the connected object or a scanning receiving station of the network of connected objects.

[0022] Thus, when this method is implemented at the level of the connected object, the third signal is an analog signal. In this embodiment, the method then comprises a step of transmission by the connected object of the third signal to a digitization receiving station of the network of connected objects, for example by radio.

[0023] When this method is implemented at a receiving station for digitizing the network of connected objects, the method according to the invention further comprises a step of digitizing the third signal, a step of cutting the third digitized signal into packets and a step of transmitting the packets to an information system via a communications network.

[0024] Alternatively, when this method is implemented at a digitization receiving station of the network of connected objects, the method according to the invention further comprises a step of digitizing the first signal and the second synchronization signal before the generation step, a step of cutting the third digitized signal into packets and a step of transmitting the packets to an information system via a communications network.

[0025] The invention therefore offers great flexibility of implementation.

[0026] According to a second aspect, the invention relates to a method for processing a signal transmitted in a network of connected objects and generated according to a generation method of the invention, this processing method being in accordance with claim 6.

[0027] In a particular embodiment, this processing method comprises a step of obtaining a dating of the data conveyed by the first signal and / or a location of the connected object having acquired this data, using the information included in the second synchronization signal.

[0028] Correlatively, the invention relates to a device for processing a signal transmitted in a network of connected objects, this device being in accordance with claim 9.

[0029] According to a third aspect, the invention relates to a communication system comprising: at least one connected object and at least one digitization receiving station of a network of connected objects; and an information system comprising a processing device according to the invention; in which at least one piece of equipment of the network of connected objects among said at least one connected object and said at least one digitization receiving station comprises a generation device according to the invention.

[0030] The particular advantages and characteristics of the signal generation device, the signal processing device, and the communication system according to the invention are identical to those of the methods described above and will not be repeated here.

[0031] It may also be envisaged, in other embodiments, that the signal generation method, the signal processing method, the signal generation device, the signal processing device and the communication system according to the invention have in combination all or part of the aforementioned characteristics.

[0032] In a particular embodiment, the different steps of the signal generation method and / or the signal processing method are determined by computer program instructions.

[0033] Consequently, the invention also relates to a computer program on an information medium, this program being capable of being implemented in a computer, for implementing the steps of the methods according to the invention, as briefly described above.

[0034] This program may use any programming language, and may be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0035] The invention also relates to an information medium readable by a computer, and comprising instructions of the computer program as mentioned above.

[0036] The information carrier may be any entity or device capable of storing the program. For example, the carrier may include a storage medium, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a floppy disk, a hard disk, or a USB key.

[0037] On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The programs according to the invention may in particular be downloaded from a network such as the Internet.

[0038] Alternatively, the information carrier may consist of integrated circuits in which the program is incorporated, the circuits being adapted to carry out or to be used in carrying out the method in question. Brief description of the drawings

[0039] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures: there figure 1 represents a communication system according to the invention in a particular embodiment of the invention; the figure 2 represents the hardware architecture of a generation device according to the invention in a particular embodiment; the figure 3 represents the hardware architecture of a processing device according to the invention in a particular embodiment; the figure 4 represents, in the form of a flowchart, the main stages of the process implemented by the generation device figure 2 in a particular embodiment of the invention; the Figure 5represents, in the form of a flowchart, the main stages of the process implemented by the processing device figure 3 in a particular embodiment of the invention. Detailed description of the invention

[0040] There figure 1 represents, in its environment, a communication system SC according to the invention, in a particular embodiment of the invention. This system SC here comprises a plurality of receiving stations ER and a plurality of connected objects OC (e.g. water consumption sensors) forming a network of connected objects of a service provider, as well as an information system SI of a client entity of this service provider.

[0041] In the embodiment described here, each receiving station ER is provided with a DG generation device according to the invention, and the information system SI is provided with a DD processing device according to the invention. Alternatively, all or some of the receiving stations ER are provided with a DG generation device, and / or all or some of the connected objects OC are also provided with a DG generation device.

[0042] In the example considered in the figure 1, the system SC makes it possible to associate with an application signal S1 carrying data acquired by a connected object OC precise dating information provided by a radio synchronization signal S2 transmitted continuously by an external “universal” synchronization device SS. This synchronization device SS is for example here a satellite navigation system such as a GPS system, GLONASS (for “Global Navigation Satellite System”, in English), Galileo, DORIS (for “Doppler Orbitography and Radiopositioning Integrated by Satellite”, in English), Beidou... or a radio-controlled clock device. S denotes the signal resulting from the combination of the signals S1 and S2 carried out by the generation device DG.

[0043] According to the invention, the generation of the signal S by the generation device DG integrated in the receiving station ER is based on a reversible operation applied to the application signal S1 and to the synchronization signal S2.

[0044] This reversible operation includes: a frequency multiplexing of the first and second signals S1, S2 on two consecutive frequency bands; or a multiplexing of the first and second signals S1, S2 by orthogonal codes; or a steganographic multiplexing of the first and second signals S1, S2, or a watermark, the third signal being obtained by superimposing the first and second signals, the second signal being a signal with high spectral density, the first signal being a low density narrowband signal.

[0045] As mentioned previously, for each of these reversible operations there is a so-called "inverse" operation that can be applied to the third signal and which makes it possible to reconstruct the first and second signals S1 and S2, or at least to extract from the signal S, the information conveyed by the first signal S1 and by the second synchronization signal S2. Examples of such operations are described later.

[0046] In the embodiment described here, the connected object OC, the receiving station ER and the synchronization device SS communicate with each other by radio. However, no limitation is attached to the nature of the communication link between the connected object OC and the receiving station ER. It may be a radio, wired, optical, etc. communication link.

[0047] The receiving station ER and the information system SI communicate with each other via the NW communications network. There is no limitation on the nature of the NW communications network. It can be a fixed, mobile, wireless, wired, etc. telecommunications network.

[0048] In the embodiment described herein, the DG generation device and the DD processing device have the hardware architecture of a computer, as schematically represented in FIG. figure 2 and to the figure 3 respectively.

[0049] In relation to the figure 2 , the DG generation device comprises in particular a processor 10, a rewritable non-volatile memory 11, a ROM type read-only memory (for “Read-only memory” in English) 12, a RAM type random access memory (for “Random-access memory” in English) 13 and a COM communication module.

[0050] The communication module COM is equipped with different interfaces which allow it to communicate by radio with the synchronization device SS to receive the synchronization signal S2 and with the connected object OC to receive the application signal S1, and via the communications network NW with the information system SI to transmit to it the signal S generated in accordance with the invention. These interfaces may include in particular radio frequency RF modules, a network card, etc. adapted to the different communications networks considered.

[0051] The read-only memory 12 of the DG generation device constitutes a recording medium in accordance with the invention, readable by the processor 10 and on which is recorded a computer program PG in accordance with the invention comprising instructions for executing the steps of a generation method according to the invention as implemented by the DG generation device and the steps of which are detailed later with reference to the figure 4 .

[0052] This computer program PG defines in an equivalent manner functional modules of the generation device DG (software modules here), and in particular here a module MO for obtaining the application signal S1 and a module MR for receiving the synchronization signal S2 which are based here on the communication module COM, as well as a generation module MG.

[0053] The functions of these software modules are detailed further later with reference to the steps of the generation method according to the invention.

[0054] In relation to the figure 3 and similarly, the DD processing device comprises in particular a processor 20, a rewritable non-volatile memory 21, a ROM type read-only memory 22, a RAM type random access memory 23.

[0055] The dating device DD also comprises a communication module COM adapted to receive from the receiving station ER the signal S generated in accordance with the invention.

[0056] The read-only memory 22 of the DD generation device constitutes a recording medium in accordance with the invention, readable by the processor 20 and on which is recorded a computer program in accordance with the invention comprising instructions for executing the steps of a processing method according to the invention as implemented by the DD processing device and the steps of which are detailed later with reference to the Figure 5 .

[0057] This computer program defines in an equivalent manner a functional module of the DD processing device (software modules here), and in particular here an MR module for receiving the signal generated by the DG generation device which is based here on the COM communication module, as well as an ME extraction module.

[0058] The functions of the MS and MD modules are detailed further later with reference to the steps of the processing method according to the invention.

[0059] In reference to the figure 4 , We will now describe the main steps of the process implemented by an ER receiving station of the figure 2 and more precisely by the DG generation device of this station in accordance with the invention, in a particular embodiment.

[0060] It is assumed that a connected object OC continuously acquires data and transmits them by radio in the form of an application signal S1 to the receiving station ER. These data can be acquired by the connected object OC from a sensor or a measuring device equipping the connected object for example, or be generated by the connected object itself.

[0061] This application signal S1 here occupies a frequency band BD1 (for example [863 MHz, 870 MHz]). The signal S1 received by the receiving station ER via its RF modules is transmitted via its communication COM module to its obtaining MO module (G10).

[0062] This application signal S1 carries the flow of data acquired by the OC object.

[0063] Simultaneously, the receiving station ER also receives (G20) continuously via its RF module a synchronization signal S2 occupying a frequency band BD2 (for example [1575.42-Δ MHz, 1575.42+Δ MHz]) and coming from the satellite navigation system SS. The synchronization signal S2 is for example here a GPS signal. In a known manner, this synchronization signal S2 comprises raw information I (for example an atomic clock) providing a dating of the application signal S1 received at the same time, that is to say information I indicating the precise instant (date and time) of obtaining the application signal S1.

[0064] The receiving station ER then generates (G30) via its generation module MG, a signal S by combining, according to a reversible operation, the application signal S1 and the synchronization signal S2.

[0065] In the embodiment described here, this reversible operation consists of a frequency multiplexing of the signals S1 and S2 in two consecutive frequency bands. For this purpose, the generation module MG transposes for example the signal S2 occupying the band BD2 onto a frequency band BD2' (e.g. [870 MHz, 870+2Δ MHz]) consecutive to the frequency band BD1 (e.g. [863 MHz, 870 MHz]). The signal S is then obtained by concatenating the application signal S1 occupying the frequency band BD1 and the signal S2 transposed into the band BD2'. It occupies a frequency band BD = [B1, B2], i.e. in the example [863 MHz, 870+2Δ MHz].

[0066] According to this embodiment, the signals S1 and S2 are analog signals and are combined in the analog domain. The implemented frequency multiplexing operation is orthogonal and reversible, i.e. the application signal S1 and the synchronization signal S2 can be easily separated using a bandpass filter known per se.

[0067] In the embodiment described here, the receiving station ER then proceeds (G40) to digitize the signal S into digital samples, using an analog-to-digital converter. It then cuts (G50) the samples obtained, for example, into packets in accordance with the IP protocol. It then sends (G60) the packets thus cut to the information system SI via the communications network NW.

[0068] Alternatively, the received signals S1 and S2 are digitized (G40) by the receiving station ER before generating the signal S. This digitization is carried out in a manner known per se by means of an analog-to-digital converter. It should be noted that the two signals can be sampled at the same sampling frequency or with different sampling frequencies. In this case, the receiving station ER adjusts the rhythms of the two digitized signals (for example by means of interpolation) before combining them so as to make their rhythms identical. The signal S then generated is in the form of digital samples.

[0069] Other reversible operations than frequency multiplexing can of course be considered to combine the signals S1 and S2. These operations can be orthogonal or not.

[0070] For example, the reversible operation can consist of multiplexing by orthogonal codes. According to this operation, the signals S1 and S2 can be brought back to baseband and then spread respectively using codes C1 and C2 (e.g. Walsh sequences) orthogonal to each other before being summed.

[0071] According to another variant, the reversible operation may consist of steganographic multiplexing. The least significant bits of the samples of the application signal S1 may be used in particular to convey the bits of the synchronization signal S2. For example, 8 bits of the synchronization signal S2 use the last two bits of the application signal S1 on 4 successive samples of the application signal S1.

[0072] In yet another variant, the reversible operation consists of a so-called "watermarking" operation. In this variant, the signal S2 is a signal with high spectral density (e.g., a spread spectrum signal) while the signal S1 is a low-density narrowband signal. The signal S is obtained by superimposing the signals S1 and S2. The two signals S1 and S2 can then be separated at reception using simple filtering.

[0073] It should be noted that it is not necessary for a combination operation to be considered “reversible” within the meaning of the invention to obtain a reconstruction of the first and second signals that is perfectly identical to the signals S1 and S2 used to generate the signal S. A reconstruction that makes it possible to extract with sufficient quality (or signal-to-noise ratio) the information (data and / or dating information) conveyed by the signals S1 and S2 is sufficient to be considered reversible within the meaning of the invention. This is the case, for example, for a watermarking type operation as described above. In other words, the notion of reversible operation includes, within the meaning of the invention, orthogonal operations that make it possible to restore the first and second signals identically, but also non-orthogonal, “quasi-reversible” operations, which do not lead to the exact restoration (i.e.reconstruction) of the first and second signals since these operations make it possible to extract the information conveyed by these signals. In other words, there is an inverse operation making it possible to restore (i.e. extract) the application signal S1 and the synchronization signal S2 from the signal S.

[0074] It is understood that depending on the reversible operation considered, the signals (S1, S2, S) are digitized before or after combination.

[0075] In another embodiment of the invention, the generation device DG is embedded in the connected object OC which acquires the data carried by the application signal S1. In this case, the connected object OC generates in the analog domain the combined signal S from the analog signals S1 and S2 and transmits directly by radio the analog signal S thus generated to the receiving station ER. The receiving station ER digitizes and cuts into packets the sampled signal S, then transmits the packets to the information system SI via the communications network NW.

[0076] In reference to the Figure 5 , we will now describe the main steps of the method implemented by the information server SI (and more particularly by its processing device DD) on reception of the packets of digital samples sent by the receiving station ER in a particular embodiment of the invention.

[0077] The information system SI receives (H10) via its reception module MR the packets of digital samples coming from the receiving station ER via the communication network NW. The information system SI assembles the packets to obtain a series of digital samples of the signal S generated according to a reversible operation by the generation method according to the invention.

[0078] The information system SI then extracts (H20) here via its MS extraction module, two series of digital samples E1 and E2 corresponding respectively to the digitized versions of the application signal S1 and the synchronization signal S2. This extraction is carried out here, in the case of a reversible operation based on orthogonal frequency multiplexing, thanks to digital filtering known per se.

[0079] In the embodiment described here, the information system SI uses the raw dating information I carried by the synchronization signal S2 to precisely date the digital samples carried by the signal S1 and store these samples according to a time criterion in a database.

[0080] Alternatively, the information system SI can store the samples without processing the information contained in the synchronization signal S2.

[0081] Alternatively, the information system SI can obtain from the dating information I of the synchronization signal S2 the location of the connected object OC in a manner known per se, for example by calculating the time of flight using the information I.

[0082] In the embodiment described here, the DD processing device is implemented in the information system SI. Alternatively, in another embodiment, the DD processing device is implemented in another equipment of the client entity.

Claims

1. Method for generating a signal (S) intended to be transmitted through a network of connected objects, said method comprising: - a step (G10) of obtaining a first signal (S1) conveying a stream of data which are acquired by a connected object (OC) of the network, said method being such that it comprises: - a step (G20) of receiving a second synchronization signal (S2) comprising information (I) providing a dating of the first signal (S1); and - a step (G30) of generating a third signal (S) by combining, in a reversible operation, the first signal (S1) and the second synchronization signal (S2), said method being characterized in that said reversible operation comprises: - frequency multiplexing the first signal and second signal (S1, S2) over two consecutive frequency bands; or - multiplexing the first signal and second signal (S1, S2) by orthogonal codes; or - steganographically multiplexing the first signal and second signal (S1, S2); or - watermarking, the third signal being obtained by superposing the first signal and second signal, the second signal being a high-spectral-density signal, the first signal being a low-density narrowband signal.

2. Method according to Claim 1, wherein said second synchronization signal (S2) is received from a satellite navigation system (SS).

3. Method according to Claim 1 or 2, wherein the steps of obtaining (G10), receiving (G20) and generating (G30) are implemented by said connected object (OC) and said third signal (S) is an analogue signal, said method further comprising a step of the connected object (OC) transmitting the third signal (S) to a digitizing receiving station (ER) of the network of connected objects.

4. Method according to Claim 1 or 2, wherein the steps of obtaining (G10), receiving (G20) and generating (G30) are implemented by a digitizing receiving station (ER) of the network of connected objects, said method further comprising: - a step (G40) of digitizing the third signal (S); - a step (G50) of dividing the digitized third signal into packets; and - a step (G60) of transmitting the packets to an information system (SI) via a communications network (NW).

5. Method according to Claim 1 or 2, wherein the steps of obtaining (G10), receiving (G20) and generating (G30) are implemented by a digitizing receiving station (ER) of the network of connected objects, said method further comprising: - a step of digitizing the first signal (S1) and the second synchronization signal (S2) before the step of generating the third signal; - a step of dividing the third signal (S) into packets; and - a step (G60) of transmitting the packets to an information system (SI) via a communications network (NW).

6. Method for processing a signal (S) transmitted through a network of connected objects and generated according to a generation method according to any one of Claims 1 to 5, the processing method comprising: - a step of receiving said signal (S); - a step (H20) of extracting, from the received signal, data conveyed by a first signal (S1) and dating information (I) contained in a second synchronization signal (S2), the first signal (S1) and the second signal (S2) being obtained using an operation which is the reverse of the reversible operation used during the generation method.

7. Processing method according to Claim 6, comprising a step of obtaining a dating of the data conveyed by the first signal (S1) and / or a location of a connected object (OC) having acquired these data, using the dating information (I) contained in the second synchronization signal (S2).

8. Device (DG) for generating a signal (S) intended to be transmitted through a network of connected objects, said device (DG) comprising: - a module (MO) for obtaining a first signal (S1) conveying a stream of data which are acquired by a connected object (OC) of the network, said device being such that it comprises: - a module (MR) for receiving a second synchronization signal (S2) comprising information (I) providing a dating of the first signal (S1); - a signal generation module (MG) configured to generate a third signal (S) by combining, in a reversible operation, the first signal (S1) and the second synchronization signal (s2), said device being characterized in that said reversible operation comprises: - frequency multiplexing the first signal and second signal (S1, S2) over two consecutive frequency bands; or - multiplexing the first signal and second signal (S1, S2) by orthogonal codes; or - steganographically multiplexing the first signal and second signal (S1, S2); or - watermarking, the third signal being obtained by superposing the first signal and second signal, the second signal being a high-spectral-density signal, the first signal being a low-density narrowband signal.

9. Device (DD) for processing a signal (S) transmitted through a network of connected objects, said device (DD) comprising: - a module (MR) for receiving, via a communications network (NW), a signal (S) generated by a signal generation method (DG) according to any one of Claims 1 to 5; - an extraction module (ME) configured to extract, from the received signal (S), data conveyed by a first signal (S1) and dating information (I) contained in a second synchronization signal (S2), the first signal (S1) and the second signal (S2) being obtained using an operation which is the reverse of the reversible operation used during the generation method, the device being characterized in that the reversible operation used during the generation method comprises: - frequency multiplexing the first signal and second signal (S1, S2) over two consecutive frequency bands; or - multiplexing the first signal and second signal (S1, S2) by orthogonal codes; or - steganographically multiplexing the first signal and second signal (S1, S2); or - watermarking, the third signal being obtained by superposing the first signal and second signal, the second signal being a high-spectral-density signal, the first signal being a low-density narrowband signal.

10. Communication system (SC), comprising: - at least one connected object (OC) and at least one digitizing receiving station (ER) of a network of connected objects; and - an information system (SI) comprising a processing device (DD) according to Claim 9; at least one equipment of the network of connected objects from among said at least one connected object (OC) and said at least one receiving station (ER) comprising a generation device (DG) according to Claim 8.

11. Computer program comprising instructions for executing the steps of a signal generation method according to any one of Claims 1 to 5, or of a signal processing method according to Claim 6 or 7, when said program is executed by a processor.

12. Computer-readable storage medium on which a computer program according to Claim 11 is stored.