Patent Application
20240004057
The present invention belongs to the general field of telecommunications. It relates, more particularly, to a method and a system for determining whether or not events which are produced at the time when sources emit data streams in a telecommunications network are correlated.
In the present document, an “event” is an event captured by a device referred to as a “source” and represented by a data stream transmitted by the source in a telecommunications network.
For example, when a source films a car which passes in front of a building and transmits live on a video stream network representing this scene, it can be considered that the video stream represents the event constituted by the passage of the car in front of the building at the time of shooting.
According to a second example, when a telephone transmits an audio stream on a mobile phone network, a sound element, for example the noise of an explosion, can be considered as representative of an event, namely that of the explosion, which would have occurred near the telephone at the time of the call.
More generally, in the context of this invention, when a source emits a data stream, it is hypothesised that this emission takes place during the course of an event defined in a spatio-temporal manner, wherein:
In other words, given a plurality of data streams emitted in a network, the invention aims to determine whether these streams are:
The invention has many applications. It can, for example, determine whether the emission of a video stream by a video-surveillance camera during a burglary (first event within the meaning of the invention) and the emission of a telephone call (second event within the meaning of the invention) by the telecommunication terminal of an individual are co-located (spatial correlation) and simultaneous (temporal correlation).
The document by R. B. Ghormade, S. Magar and B. Joshi, “Discovery of Neighbors in Wireless networks with Energy Efficient Approach” 2016 IEEE 6th International Conference on Advanced Computing (IACC), Bhimavaram, 2016, pp. 610-612” proposes mechanisms for determining whether two terminals are neighbours.
According to these mechanisms, the terminals emit a predefined beacon signal, and when one terminal detects this beacon signal emitted by another terminal, it deduces from it that this other terminal is in its vicinity.
A major disadvantage of these techniques is that they require the emission of a beacon signal and therefore an additional energy consumption by the terminals for this requirement.
The object of the present invention is to overcome all or part of the disadvantages of the prior art, in particular those set out above.
To this effect, the invention relates to a method for correlating events, said method comprising the steps of:
In conjunction, the invention relates to a system for correlating events comprising:
Thus, and in a general manner, the invention discloses determining whether data streams have been emitted substantially simultaneously and/or by neighbouring sources, by analysing markers introduced into these data streams by backscattering.
In contrast to the above-mentioned techniques from the prior art, the emitting sources of a data streams do not need to emit a beacon signal in order to signal themselves to their neighbours. They do not do any processing and therefore do not consume any resource for this purpose.
More generally and very advantageously, conforming with the mechanisms for communication by ambient backscattering, no radiofrequency signal is emitted to mark the data streams emitted by the sources, the transmitting device exploiting the signal emitted by a source in order to communicate the marker to the receiving module.
The energy required for implementing the invention is therefore substantially that required for analysing the markers in order to determine the spatial and/or temporal correlation of the events.
In a particular embodiment:
According to this embodiment, it is considered that events are spatially correlated if signals emitted by the sources during these events and backscattered, comprise identical markers.
This embodiment of the invention is advantageous because it can be implemented using transmitter devices which conform with the prior art, since these transmitting devices mark the backscattered signal with their individual identifiers.
According to a second aspect, the invention relates to a method implemented by a transmitting device configured for backscattering an ambient signal emitted by a source (SOi), said ambient signal carrying a data stream emitted by the source, said method comprising a step of marking said stream with a marker representative of the location of said transmitting device or of a time of backscattering of said data streams by said transmitting device, wherein:
In conjunction, the invention relates to a transmitting device comprising a geolocation module of this device and a clock, said device being configured for backscattering an ambient signal emitted by a source, said ambient signal carrying a data stream emitted by the source, said device comprising a module for marking said stream with a marker representative of the location of said transmitting device or of a time of backscattering of said data stream by said transmitting device, wherein:
The invention thus discloses a novel type of device capable of marking a stream with a piece of spatial and/or temporal information making it possible to date and/or locate the emission of this stream, with very low energy consumption.
In a particular embodiment:
In accordance with this embodiment, it is considered that events are temporally correlated if the signals emitted by the sources during these events and backscattered, comprise markers representing substantially simultaneous times of backscattering, for example spaced apart by a duration less than a threshold value.
In a particular embodiment:
In accordance with this embodiment, it is considered that events are spatially correlated if the signals emitted by the sources during these events and backscattered, comprise markers representing neighbouring locations, for example separated by a distance less than a threshold value.
In a particular embodiment, the system for correlating events is incorporated in a telecommunications device, for example a base station or a terminal.
In this embodiment of the invention, the sources can be terminals and the signals emitted by these terminals can be signals emitted in the uplink direction and comprising data intended for the base station.
In an embodiment of the invention, the system is distributed over a plurality of devices. This system comprises:
The telecommunication devices can be base stations receiving signals emitted by the terminals, at least some of these signals being backscattered by transmitting devices. The correlation device which analyses these markers in order to detect any correlated events can be centralised in the network.
According to a third aspect, the invention relates to a computer program comprising instructions for implementing the method for correlating events according to the invention, when said program is executed by a computer.
This program can use any programming language, and be in the form of source code, object code, or code that is intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.
According to a fourth aspect, the invention relates to a computer program comprising instructions for implementing the marking method according to invention, when said program is executed by a computer.
These programs can use any programming language, and be in the form of source code, object code, or code that is intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.
According to a third aspect, the invention relates to a computer-readable data storage or recording medium, on which a computer program according to the invention is recorded.
The data storage or recording medium can be any entity or device capable of storing the program. For example, the medium may comprise storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or even a magnetic recording means, for example a hard drive.
On the other hand, the data storage or recording medium can be a transmissible medium such as an optical or electrical signal, which can be routed via an electrical or optical cable, by radio or by other means. In particular, the program according to the invention can be downloaded on an Internet-type network.
Alternatively, the data storage or recording medium can be an integrated circuit in which the program is incorporated, the circuit being suitable for executing or for being used in the execution of the method in question.
Other features and advantages of the present invention will become apparent from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment that is in no way limiting. In the figures:
In the example of
Each emitting source SO1, SO2 is configured to emit, according to an emission frequency F_E included in a given frequency band referred to as the “emission band”, a radio signal referred to as the “ambient signal”. The emission of the ambient signal is carried out, for example, continuously for repetitively.
The term “radio signal” refers here to an electromagnetic wave propagating by wireless means, the frequencies of which are included in the conventional spectrum for radio waves (several hertz to several hundred gigahertz).
By way of non-limiting example, an ambient signal is a 4G mobile telephone signal in the emission band [811 MHz, 821 MHz]. The source SO1 or SO2 can consist of a telecommunications terminal, for example a cell phone.
It is however useful to specify that the invention remains applicable to other types of radio signals, such as a mobile telephone signal other than 4G (for example 2G, 3G, 5G), a Wi-Fi signal, a WiMax signal, a DVB-T signal, etc. In general, no limitation is attached to the ambient radio signal which can be considered within the context of the present invention. Consequently, it is useful to note that the number of antennas equipping a source SO1/SO2 does not constitute a limiting factor of the invention.
In the example of
In a manner known per se, the communication by ambient backscattering consists of the use of the ambient signal, by the transmitting device D_TX, for sending data to a receiving module M30. More particularly, the transmitting device D_TX (respectively, the receiving module M30) is configured to carry out, on the basis of the ambient signal (respectively, on the basis of the backscattered signal), processing aimed at backscattering said ambient signal (respectively, aimed at decoding said backscattered signal), by implementing a backscattering method (respectively, a decoding method).
For this purpose, the transmitting device D_TX (respectively, the receiving module M30) comprises, for example, one or more processors and storage means (magnetic hard disc, electronic memory, optical disc, etc.) in which data and a computer program are stored, in the form of a set of program code instructions to be executed in order to implement the backscattering method (respectively, the decoding method).
Alternatively or in addition, the transmitting device D_TX (respectively the receiving module M30) also comprises one or more programmable logic circuits, of type FPGA, PLD, etc., and/or specialised integrated circuits (ASIC), and/or a set of discrete electronic components, etc., suitable for implementing the backscattering method (respectively, the decoding method).
In other words, the transmitting device D_TX (respectively, the receiving module M30) comprises a set of means configured as software (specific computer program) and/or hardware (FPGA, PLD, ASIC, etc.) for implementing the backscattering method (respectively, the decoding method).
The specific aspects concerning the emitting of data by backscattering to the receiving module M30, as well as those concerning the decoding techniques implemented by the latter, are known to a person skilled in the art and are outside the scope of the present invention. Consequently, they are not detailed further here.
In the present embodiment, the transmitting device D_TX is equipped with an antenna (not shown in the figures) configured, in known manner per se, to receive the ambient signal but also to backscatter it to the telecommunications device BS. It is useful to note that no limitation is attached to the number of antennas which can equip the transmitting device D_TX.
In practice, the transmitting device D_TX is associated with a frequency band, referred to as the “band of influence”, which corresponds to the frequency band in which the antenna is able to receive/backscatter signals. When said band of influence is included in the emission band associated with the source S01, S02 of the ambient signal, it is qualified as the “working band”. The term “working band” refers here to the fact that the transmitting device D_TX is compatible with the source SO1 or SO2 of the ambient signal, namely therefore that the backscattering can be carried out for any frequency included in said working band.
Nothing, however, excludes considering a band of influence which is not included in the emission band. It is nevertheless implicit in order that the transmitting device D_TX is able to backscatter the ambient signal, said band of influence and said emission band must have a non-empty intersection, the working band corresponding therefore to this intersection.
The transmitting device D_TX is likewise associated with operating states, namely at least one state referred to as “backscattering” (the transmitting device backscatters the ambient signal) as well as a contrary state referred to as “non-backscattering»(the transmitting device does not backscatter the ambient signal, or, put another way, is “transparent” to the ambient signal). These states corresponded to configurations in which said antenna is connected to distinct impedances. This typically involves a positive, or even zero, impedance for a backscattering state and, by contrast, a theoretically infinite impedance for the non-backscattering state.
For the rest of the description, it is considered, in a non-limiting manner, that the transmitting device D_TX is associated with a single backscattering state as well as with a single non-backscattering state. Nevertheless, the invention remains applicable in the case of a transmitting device D_TX associated with a plurality of backscattering states, these states being distinct from one another in that they are implemented using respective impedances which are distinct from one another (the non-backscattering state remains unique). The developments which follow can be generalised, without difficulty, by a person skilled in the art, to the case where a plurality of backscattering states is considered.
In an embodiment, the transmitting device D_TX comprises a geolocation module configured for obtaining a current location LOC_i of this device.
In an embodiment, the transmitting device D_TX comprises a clock configured for obtaining a current date and time.
In the present embodiment, the telecommunications device BS is equipped with a receiving antenna (not shown in the figures) configured for receiving signals in said working band.
It is however useful to note that no limitation is attached to the number of antennas that can equip the telecommunications device BS.
The receiving module 30 of the telecommunications device BS receives non-backscattered signals as emitted by the source SO1, SO2 and signals emitted by the sources SO1, SO2 and backscattered by the transmitting device D_TX.
The following notation is adopted in the present description:
In the rest of the description, and by way of simplification, the same notation SDi will be used to designate the signal SDi emitted by the source SOi and the data streams carried by the signal SDi.
Similarly, the same notation SRi is used to designate the signal backscattered by the transmitting device D_TX and the data streams carried by this signal.
In the embodiment described here, the transmitting device D_TX comprises a module M20 for marking the backscattered data streams SRi with a marker TAGi representative of this backscattering.
In the embodiment of
As mentioned above, the receiving module M30 is configured to decode the signal backscattered by the transmitting device D_TX. For this purpose, it is known that the decoding of the backscattered signal can only be implemented if the electromagnetic power variation, referred to as “power deviation” E_P, received by the receiving module M30 according to whether the transmitting device D_TX is in a backscattering or non-backscattering state, is, in absolute value, greater than a predetermined threshold value, referred to as the “power threshold” S_P. In other words, said power threshold S_P determines the value of the power deviation E_P from which the receiving module M30 is able to decode a signal emitted by a source SO1, SO2 and backscattered by the transmitting device D_TX.
Said power threshold S_P is, for example, defined from a signal-to-noise ratio “SNR” on the receiver device side D_RX or even, according to an alternative, from a signal to interference plus noise ratio “SINK” on the receiver device side D_RX. However, there is nothing to exclude considering yet other metrics for defining said power threshold, such as a bit error rate “BER” , for example. With regard to these aspects, a person skilled in the art could refer to the document: “Real-Time Ambient Backscatter Demonstration”, K. Rachedi, D. T. Phan-Huy, N. Selmene, A. Ourir, M. Gautier, A. Gati, A. Galindo-Serrano, R. Fara, J. De Rosny, IEEE INFOCOM 2019 Posters and Demos, 1st May 2019, Paris, France.
In accordance with the invention, it is considered that the signal emitted by a source SO1, SO2 is emitted during an event defined in a spatio-temporal manner, wherein:
In the embodiment of
In the embodiment described here, if the marker TAGi of the stream SRi backscattered by a transmitting device D_TX comprises the identifier of this transmitting device D_TX, the correlation module M70 determines that the events EVi, EVj are spatially correlated if signals emitted by the sources during these events and backscattered, comprise identical markers TAGi, TAGj.
In the embodiment described here, if the marker TAGi of the stream SRi backscattered by a transmitting device D_TX comprises a time of backscattering of the signal SRi by the transmitting device D_TX, the correlation module M70 determines that the events EVi, EVj are temporally correlated if the signals emitted by the sources during these events and backscattered, comprise markers TAGi, TAGj representing substantially simultaneous times of backscattering, for example separated by a duration less than a threshold value.
In the embodiment described here, if the marker TAGi of the stream SRi backscattered by a transmitting device D_TX comprises the identifier of this transmitting device D_TX, the correlation module M70 determines that the events EVi, EVj are spatially correlated if signals emitted by the sources during these events and backscattered, comprise markers TAGi, TAGj representing neighbouring locations, for example separated by a distance less than a threshold value.
In the embodiment described here, if the marker TAGi of the stream SRi backscattered by a transmitting device D_TX comprises a combination of the time of backscattering of the signal SRi by the transmitting device D_TX with the identifier of the transmitting device D_TX, the correlation module M70 determines that the events EVi, EVj are spatially and temporally correlated if the signals emitted by the sources during these events and backscattered, comprise markers TAGi, TAGj representing the same identifier and substantially simultaneous times of backscattering, for example separated by a duration less than a threshold value.
In the embodiment described here, if the marker TAGi of the stream SRi backscattered by a transmitting device D_TX comprises a combination of the time of backscattering of the signal SRi by the transmitting device D_TX with the location of the transmitting device D_TX, the correlation module M70 determines that the events EVi, EVj are spatially and temporally correlated if the signals emitted by the sources during these events and backscattered, comprise markers TAGi, TAGj representing neighbouring locations and substantially simultaneous times of backscattering.
In the embodiment described here, the transmitting device D_TX has the hardware architecture of a computer. It comprises, in particular, a processor 11, a RAM memory 12, a ROM memory 13 and a non-volatile memory 14.
The ROM memory 13 constitutes a recording medium in accordance with the invention, which can be read by the processor 11 and on which is recorded a computer program PROGM in accordance with the invention, comprising instructions for the execution of the steps of the marking method according to the invention. The program PROGM defines functional modules of the transmitting device D_TX, which rely on or control the hardware elements 12 to 14 of the transmitting device D_TX cited above and, in particular, a module for marking a data stream with a marker TAGi as described above.
In the embodiment described here, the telecommunications device BS has the hardware architecture of a computer. It comprises, in particular, a processor 21, a RAM memory 22, a ROM memory 23 and a non-volatile memory 24.
The ROM memory 23 constitutes a recording medium in accordance with the invention, that can be read by the processor 21 and on which is recorded a computer program PROGC in accordance with the invention, comprising instructions for the execution of the steps of the method for correlating events according to the invention. The program PROGC defines functional modules of the telecommunications device BS, which rely on or control the hardware elements 22 to 24 of the telecommunications device BS cited above, and in particular:
As illustrated by
During a step E20, a transmitting device D_TX backscatters this stream while marking the backscattered stream Sri with a marker TAGi representative of the backscattering of this stream by this transmitting device.
In the embodiment described here, the marker TAGi comprises at least one element from:
A receiving module M30 is configured for receiving, during a step E30, the stream SRi backscattered by the transmitting device D_TX.
In the embodiment described here, during a step E40, the receiving module M30 records, in a database BD, a record comprising the marker TAGi and at least one piece of information from:
The database BD comprises such records for various backscattered data streams SRi, SRj.
During a step E50, a correlation module M70 obtains the markers TAGi, TAGj corresponding to various backscattered data streams SRi, SRj.
During a step E60, the correlation module M70 compares the markers TAGi, TAGj in order to determine whether or not there is a spatial correlation and/or a temporal correlation between the events EVi, EVj during which these streams have been emitted by their respective sources.
In the embodiment described here:
In the contrary case, the correlation module M70 determines during a step E80 that the events EVi, EVj are not correlated either spatially or temporally.
In the example of
As mentioned above, the invention can be implemented with transmitting devices D_TX configured for marking the backscattered signal with their individual identifier.
In particular, the invention can be implemented with transmitting devices D_TX in accordance with the prior art and configured for marking the backscattered signal with their individual identifier.
In this embodiment, and as shown for example in
The correlation system of
Hence, in this embodiment, the database BD can be supplied by a plurality of base stations, the records of the database BD being analysed by the same correlation device DCO in order to determine whether or not the events are correlated.
In this embodiment, in particular, the telecommunication devices (base stations) can add, in the record of the database, the time at which they receive a backscattered data stream.
Hence, if the transmitting device D_TX marks the backscattered signal with its identifier or with its location information, but without marking the stream with a piece of temporal information, the correlation device can use the time of reception of the backscattered stream by the base station in order to correlate the events temporally, if the base stations are synchronised with one another.
The correlation system of
The correlation system of
The telecommunications device BS (for example a base station) receives backscattered signals from transmitting devices D_TXi, D_TXj, for example the signals SR1, SR2 from D_TXi and the signals SR3, SR4 from D_TXj.
If the transmitting devices D_TXi, D_TXj mark the streams that they backscatter with a piece of spatial information representative of their location, the telecommunications device can determine whether the events during which these streams have been broadcast by their sources are spatially correlated.
If the transmitting devices D_TXi, D_TXj mark the streams that they backscatter with a piece of temporal information representative of the time at which they have backscattered the stream, the telecommunications device can determine whether the events during which these streams have been broadcast by their sources are temporally correlated. For this, it is necessary that the transmitting devices D_TXi, D_TXj are synchronised with one another.
The system of
As in the case of
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2012461 | Dec 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2021/052146 | 11/30/2021 | WO |
