1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
& The Patent Rules, 2003
COMPLETE SPECIFICATION
1.TITLE OF THE INVENTION:
METHOD FOR GEOGRAPHICALLY LOCATING A SIGNAL-TRANSMITTING
DEVICE
2. APPLICANT:
Name: KERLINK
Nationality: France
Address: 1 rue Jacqueline Auriol, 35235 THORIGNE-FOUILLARD, France.
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it
is to be performed:
2
Technical 5 field
The invention relates to the field of the methods for geolocating a radio
signal-transmitting device, notably signal-transmitting devices belonging to the field of
the internet of things. More particularly, the invention relates to the geolocation of a
signal-transmitting device in the context of a network comprising a plurality of data
10 concentration gateways.
Technological background
The internet of things consists in allowing objects to communicate data
automatically with a wireless network. For example, a water meter equipped with a
communication module can automatically communicate a water reading to the
15 company managing the billing of water consumption.
Message concentration gateways, also called reception stations, are
designed to receive and transmit data from and to communication modules present
in their coverage zone and to relay these data to equipment responsible for
processing them, for example servers accessible on a network based on the IP
20 protocol (Internet Protocol).
A number of radio access technologies are available for implementing
networks of communication modules. Purely illustrative and nonlimiting examples of
the technologies that can be cited include LoRa™, Sigfox™ or even WM-Bus
(Wireless Meter Bus), which are based notably on different modulation types. These
25 technologies have the common feature of offering long range communications which
make it possible to reduce the number of gateways by increasing the coverage
thereof.
In some situations, it may be necessary to geolocate certain objects
transmitting radio signals. That can for example be the case for transmitters
3
associated with mobile objects such as product transport pallets or the like. It is known
practice to use, for that, satellite guidance (GPS). However, the use of components
allowing location via GPS can be complex, costly and energy-intensive for the signaltransmitting
device and is not therefore suitable for all uses or for all the signaltransmitting
5 devices.
Also known, for example from the document US2010/0138184 A1, is a
geolocation method based on triangulation using reception data of a radio signal
transmitted by a signal-transmitting device at a plurality of radio receivers. Such
reception data are, for example, the date of reception of the radio signal or even the
10 power of the radio signal received by the different receivers. However, such a
triangulation-based method offers an accuracy that is dependent on the radio access
technology used by the signal. Thus, in the case of a long range communication
technology, the geolocation accuracy is limited and does not always make it possible
to geolocate the signal-transmitting device with the requisite accuracy.
15 There is therefore a need for a method for geolocating a radio signaltransmitting
device that offers low complexity, reduced consumption and an adequate
degree of accuracy.
Summary
The invention makes it possible to meet these needs. One idea on which the
20 invention is based is to allow the geolocation of a radio signal-transmitting device with
a satisfactory degree of accuracy. One idea on which the invention is based is to
geolocate a radio signal-transmitting device using an infrastructure of a simple
communication network, of low energy consumption and offering a degree of accuracy
suited to the needs. In particular, one idea on which the invention is based is to adapt
25 the degree of accuracy of geolocation to the geographic zones in which said signaltransmitting
device is located.
For that, the invention provides a method for geolocating a signaltransmitting
device, the geolocation method comprising:
 supplying first reception data, said first reception data resulting from the
30 reception, by a plurality of first reception stations, of a first radio signal
4
transmitted at a first frequency by the signal-transmitting device, said first
reception stations defining a first geographic coverage zone,
 calculating a first geographic position of the signal-transmitting device in
the first geographic coverage zone from the first reception data,
 detecting that the geographic position of the signal-transmitting 5 device is
included in a predefined second geographic zone, the second geographic
zone being included in the first geographic coverage zone,
 transmitting a transmission instruction signal to the signal-transmitting
device, the transmission instruction signal being intended to trigger the
10 transmission of a second radio signal at a second frequency distinct from
the first frequency by the signal-transmitting device,
 supplying second reception data, said second reception data resulting
from the reception of the second radio signal by a plurality of second
reception stations, said second reception stations being able to receive
15 a radio signal at the second frequency transmitted from the second
geographic zone, and
 calculating a second geographic position of the signal-transmitting device
in the second geographic zone from the second reception data.
By virtue of these features, it is possible to adapt the degree of accuracy and
20 therefore the infrastructure allowing the geolocation of the signal-transmitting device
as a function of the geographic zones in which said signal-transmitting device is
located. Thus, when the signal-transmitting device is in a zone not requiring a high
degree of accuracy, for example traveling between two storage zones, the
geolocation by the first reception stations offers an infrastructure that is suitable both
25 from a point of view of the range and with respect to the desired level of geolocation
accuracy and, when the transmitting device enters into a zone requiring a higher
degree of accuracy, the geolocation by the second reception station allows, for this
zone, an increased degree of accuracy requiring an infrastructure suitable only for
said zone.
5
By virtue of these features, it is also possible to limit the energy consumption
of the signal-transmitting device. In fact, the transmission of the second signal by the
signal-transmitting device is activated only when the signal-transmitting device is in
the second geographic zone, that is to say in a zone in which said second signal can
be received by the second reception stations. Thus, the transmitting 5 device does not
consume energy to transmit the second radio signal as long as it is not located by
means of the first radio signal as being in the second geographic zone.
According to other advantageous embodiments, such a geolocation method
can have one or more of the following features.
10 According to one embodiment, prior to the transmission of the transmission
instruction signal, the second reception stations are in an inactive state in which said
second reception stations are unable to receive a radio signal at the second frequency
transmitted from the second zone, the method further comprising, prior to the
transmission of the transmission instruction signal:
15 - transmitting an activation signal for the second reception stations to
activate the second reception stations so that said second reception
stations are configured to receive a radio signal at the second frequency
transmitted from the second geographic zone.
By virtue of these features, it is possible to limit the energy consumption of
20 the second reception stations. In fact, said second reception stations are activated
and consume energy only when the signal-transmitting device is geolocated in the
second geographic zone by means of the first radio signal, that is to say in the zone
in which second reception stations are able to receive the second radio signal.
According to one embodiment,
25 - the predefined second geographic zone comprises a plurality of
geographic sub-zones,
- the plurality of second reception stations comprises a plurality of
groups of second reception stations, each group of second reception
stations being able to receive a radio signal at the second frequency
30 transmitted from one said respective geographic sub-zone,
6
and
- the step of detecting that the geographic position of the signaltransmitting
device is included in the predefined second geographic
zone comprises detecting that the geographic position of the signaltransmitting
device is included in a given geographic 5 sub-zone of the
plurality of geographic sub-zones,
- the second reception data result from the reception of the second
radio signal by a given group of second reception stations able to
receive a radio signal transmitted at the second frequency in said
10 given geographic sub-zone.
By virtue of these features, it is possible to geolocate the signal-transmitting
device in several joined geographic zones in which different groups of second
reception stations are installed. Thus, it is possible to geolocate the signal-transmitting
device by means of the several distinct groups of second stations when the signal15
transmitting device is moving in the different sub-zones of the second geographic
zone.
According to one embodiment, prior to the transmission of the transmission
instruction signal, the second reception stations are in an inactive state in which said
second reception stations are unable to receive a radio signal at the second frequency
20 transmitted from the second geographic zone, the method further comprising, prior to
the transmission of the transmission instruction signal and after the detection that the
geographic position of the signal-transmitting device is included in the given
geographic sub-zone:
- transmitting an activation signal for the second reception stations of
25 the given group of second reception stations so that said second
reception stations are configured to receive the second radio signal
at the second frequency.
By virtue of these features, only the second reception stations of the group
of second reception stations able to receive the second signal in the given geographic
30 sub-zone are activated, thus limiting the energy consumption of the infrastructure.
7
According to one embodiment, the method further comprises, after the
calculation of the second geographic position of the signal-transmitting device:
- detecting that the geographic position of the signal-transmitting
device is situated outside of said given geographic sub-zone,
- transmitting a deactivation signal for the second reception 5 stations of
the given group of second reception stations so that said second
reception stations are rendered inactive.
By virtue of these features, the second reception stations are deactivated
and therefore no longer consume energy to receive the second radio signal when said
10 second radio signal is transmitted from a sub-zone other than the sub-zone in which
said second reception stations are not able to receive the second radio signal.
According to one embodiment, the method further comprises, after the
calculation of the second geographic position of the signal-transmitting device:
- detecting that the geographic position of the signal-transmitting
15 device is situated outside of the second geographic zone,
- transmitting an end of transmission instruction signal to the signaltransmitting
device to interrupt the transmission of the second radio
signal at the second frequency by the signal-transmitting device.
By virtue of these features, the energy consumption of the signal-transmitting
20 device is reduced. In fact, when the signal-transmitting device is no longer in a zone
allowing it to be geolocated by means of the second reception stations, the signaltransmitting
device ceases to consume energy to transmit the second signal.
According to one embodiment, the method further comprises:
- detecting that the geographic position of the signal-transmitting
25 device is situated outside of the second geographic zone,
- transmitting a deactivation signal for the second reception stations so
that said second reception stations are inactive.
8
By virtue of these features, the second reception stations are deactivated
and therefore no longer consume energy to receive the second radio signal when the
signal-transmitting device is outside of said second geographic zone.
According to one embodiment, the reception data of the first signal comprise,
for each first reception station having received the first radio 5 signal, a datum of
identification of said first radio signal, a datum of date of reception of said first radio
signal and a datum of position of said first reception station.
According to one embodiment, the reception data of the first radio signal
further comprise a datum of intensity of reception of said first radio signal.
10 According to one embodiment, the reception data of the second signal
comprise, for each second reception station of the plurality of second reception
stations having received the second radio signal, a datum of identification of said
second radio signal, a datum of date of reception of said second radio signal and a
datum of position of the second reception station.
15 According to one embodiment, the reception data of the second radio signal
further comprise, for each second reception station, an angle of reception and an
intensity of reception of said second radio signal.
According to one embodiment, the first frequency is lower than the second
frequency.
20 According to one embodiment, the first radio signal is a frame of a LoRa
communication protocol.
According to one embodiment, the first frequency is included in the 433 MHz,
868 MHz and 915 MHz group of frequencies.
According to one embodiment, the second radio signal is a frame of a UWB
25 communication protocol.
According to one embodiment, the second frequency is included between
3 GHz and 10 GHz, preferably between 6 Ghz and 8 GHz.
According to one embodiment, the invention also provides a system for
geolocating a signal-transmitting device, the geolocation system comprising:
9
- a plurality of first reception stations, said first reception stations
defining a first geographic coverage zone, said first reception stations
being configured to receive a first radio signal transmitted by the
signal-transmitting device at a first frequency and from the first
geographic coverage zone, the first reception 5 stations being
configured to generate first reception data resulting from the
reception of said first radio signal,
- a plurality of second reception stations, said second reception
stations being configured to receive a second radio signal transmitted
10 by the signal-transmitting device at a second frequency distinct from
the first frequency and from a predefined second geographic zone,
the second geographic zone being included in the first geographic
coverage zone, the second reception stations being configured to
generate second reception data resulting from the reception of the
15 second radio signal,
- a communication network, the first reception stations being
connected to said communication network and configured to transmit
the first reception data to a remote server via the communication
network, the second reception stations being connected to said
20 communication network and configured to transmit the second
reception data to said remote server via the communication network,
wherein, the remote server is configured to:
- calculate a first geographic position of the signal-transmitting device
in the first geographic coverage zone from the first reception data,
25 - detect that the geographic position of the signal-transmitting device
is included in the predefined second geographic zone,
- transmit a transmission instruction signal to the signal-transmitting
device, the transmission instruction signal being intended to trigger
the transmission of the second radio signal by the signal-transmitting
30 device,
10
- calculate a second geographic position of the signal-transmitting
device in the second geographic zone from the second reception
data.
According to one embodiment, the second reception stations are configured
to be able to assume an inactive state in which said second reception 5 stations are
unable to receive a radio signal at the second frequency transmitted from the second
zone or an active state in which said second reception stations are configured to
receive a radio signal at the second frequency transmitted from the second
geographic zone.
10 According to one embodiment, the remote server is configured to, prior to the
transmission of the transmission instruction signal, transmit an activation signal for
the second reception stations.
According to one embodiment, the predefined second geographic zone
comprises a plurality of geographic sub-zones, the plurality of second reception
15 stations comprising a plurality of groups of second reception stations, each group of
second reception stations being able to receive a radio signal at the second frequency
transmitted from a said respective geographic sub-zone.
According to one embodiment, the remote server is configured to detect that
the geographic position of the signal-transmitting device is included in a given
20 geographic sub-zone of the plurality of geographic sub-zones and transmit an
activation signal for the second reception stations of the group of second reception
stations associated with said given geographic sub-zone.
According to one embodiment, the remote server is configured to detect that
the geographic position of the signal-transmitting device is situated outside of said
25 given geographic sub-zone and to transmit a deactivation signal for the second
reception state of said given group of second reception stations.
According to one embodiment, the remote server is configured to detect that
the geographic position of the signal-transmitting device is situated outside of the
second geographic zone, and to transmit an end of transmission instruction signal to
11
the signal-transmitting device to interrupt the transmission of the second radio signal
at the second frequency by the signal-transmitting device.
According to one embodiment, the remote server is configured to detect that
the geographic position of the signal-transmitting device is situated outside of the
second geographic zone, and to transmit a deactivation signal 5 for the second
reception stations.
According to one embodiment, the invention also provides a signaltransmitting
device comprising:
- a first communication module able to transmit a first radio signal at a
10 first frequency,
- a second communication module able to transmit a second radio
signal at a second frequency distinct from the first frequency, said
second communication module being able to be configured to
assume an inactive state in which the signal-transmitting device is
15 able to transmit only the first radio signal or an active state in which
the signal-transmitting device is able to transmit the first radio signal
and the second radio signal,
- a reception module able to receive a signal instructing transmission
of the second radio signal and configured to, on reception of said
20 transmission instruction signal, switch the second communication
module from the inactive state to the active state.
According to one embodiment, the reception module is able to receive an
end of transmission instruction signal and configured to, on reception of said end of
transmission instruction signal, switch the second communication module from the
25 active state to the inactive state.
Brief description of the figures
The invention will be better understood, and other aims, details, features and
advantages thereof will become more clearly apparent from the following description
of several particular embodiments of the invention, given purely in an illustrative and
30 nonlimiting manner, with reference to the attached drawings.
12
- Figure 1 is a schematic representation of a radio signal-transmitting
object in a wide area communication network comprising a plurality of first reception
stations, the coverage zone of said wide area communication network comprising a
second geographic zone in which a plurality of second reception stations are
5 arranged;
- Figure 2 is a diagram illustrating the successive steps of a method for
geolocating the signal-transmitting device of figure 1;
- Figure 3 is a schematic representation of the signal-transmitting device
of figure 1 circulating in a second geographic zone subdivided into a plurality of
10 geographic sub-zones, a group of second stations being arranged in each of said
geographic sub-zones;
- Figure 4 is a diagram illustrating the successive steps implemented by
the signal-transmitting device during the geolocation thereof;
15 Detailed description of embodiments
Figure 1 illustrates a radio signal-transmitting device 1 to be geolocated.
Such a device 1 is of any type capable of communicating data via a radio signal, such
as, for example, a device 1 belonging to the internet of things. Such a device 1 is
equipped with a wireless communication module and can thus communicate
20 measured or calculated data, depending on its characteristics. Such a device 1
belonging to the internet of things has the particular feature of consuming little energy,
being commonly qualified as “low consumption”, and of using very low bit rate
communication means, for example less than 2 Kbps.
The device 1 illustrated in figure 1 is geographically mobile. The device 1 is,
25 for example, an identifying device of a container transporting goods. Thus, figure 1
illustrates this device 1 moving from a first position 2 to a second position 3. In order
to track the movements of the mobile device 1, the latter is geolocated.
In order to limit the complexity and the energy consumption of the signaltransmitting
device 1, for example by avoiding the use of a satellite guiding system, it
13
is preferable to geolocate the device 1 by using the radio signals transmitted by said
device 1.
Regularly and/or occasionally, the device 1 transmits a first radio signal 4 in
order to allow it to be geolocated. This first radio signal 4 is received by a plurality of
first stations 5 situated in the region of the device 1, as illustrated 5 by the arrows 6 in
figure 1. These first stations 5 are connected to a network 7, such as a wide-area
communication network of internet or similar type in order to transmit data relating to
the first radio signal 4 received to a remote device that is the recipient of said first
radio signal 4. In the context of a geolocation system, these first stations 5 are
10 connected via the network 7 to a remote server 8 making it possible to calculate the
geographic position of the device 1.
For that, the remote server 8 comprises a location application (for example
of LBS type, LBS being the acronym for “Location-Based Service”). The location
application makes it possible, when the first radio signal 4 is received by a plurality of
15 first stations 5, to geolocate the signal-transmitting device 1 having transmitted the
first radio signal 4. This geolocation can be performed in many ways, for example by
a triangulation-based geolocation method based on the time of arrival of the signal at
the different stations of TDoA type (TDoA being the acronym for “Time Differential of
Arrival”), on the signal quality RSSI (from the acronym “Received Signal Strength
20 Indication”) and/or SNR (from the acronym “Signal to Noise Ratio”), on the angle of
arrival of the signal at the different stations AoA (“Angle of Arrival”) or the like.
Thus, when it receives the first radio signal 4, each first station 5 transmits,
to the remote server 8, first reception data of said first radio signal 4. These first
reception data of the first signal 4 are, for example, an identifier of the first radio
25 signal 4, a date of reception of the first radio signal 4, information on quality of
reception of the first radio signal 4, an angle of reception of the first radio signal 4, an
identifier and/or a geographic position of the first station 5 etc. These reception data
of the first radio signal 4 thus allow the remote server 8 to calculate the geographic
position of the device 1.
30 Several radio access technologies are available for implementing networks
of communication modules. Purely illustrative and nonlimiting examples of
14
technologies that can be cited include LoRa™, Sigfox™ or even WM-Bus (“Wireless
Meter Bus”), which rely notably on different modulation types. These technologies
have the common feature of offering long range communications which make it
possible to reduce the number of stations by increasing the coverage thereof.
Figure 1 illustrates three first stations 5 using a long 5 range reception
technology, the LoraWan technology by way of example hereinafter in the description.
Similarly, the signal-transmitting device 1 comprises a first communication module
which is configured to transmit the first radio signal 4 according to characteristics
suited to the LoraWan technology such the first stations 5 can receive said first radio
10 signal 4. Likewise, the device 1 is able to receive a signal according to characteristics
suited to the LoraWan technology by means of the first communication module or of
a distinct reception module. Thus, the first stations 5 as illustrated in figure 1 using
these technologies together define a first geographic coverage zone in which the first
radio signal 4 can be received by these first stations 5.
15 However, the geolocation of the device 1 may require a different degree of
accuracy depending on the location of the signal-transmitting device. Thus, the
accuracy of geolocation of the device 1 required is different when said device 1 is
outside, for example in transit between two countries or remote regions, and when
said device 1 is situated inside a building or in a particular zone, for example in a
20 storage depot or at a goods loading dock or of a commercial port.
The degree of accuracy in the geolocation of the device 1 depends, among
other things, on the communication technology used between the device 1 and the
first stations 5. In fact, the long range communication technologies offer a limited level
of accuracy in the geolocation applications. Thus, for example, the LoraWan
25 technology allows a coverage over a distance of fifteen or so kilometers around each
station and allows for a geolocation accuracy of the order of fifty or so meters.
Conversely, some technologies allow a significantly higher degree of
accuracy but offer a coverage range around the stations that is much more reduced.
Thus, for example, the UWB (Ultra WideBand) technology allows a geolocation
30 accuracy of the order of 50 centimeters, but the communication range between a
15
signal-transmitting device and a reception station using this technology is reduced to
10 to 20 meters.
Figure 1 illustrates a second geographic zone 9 included in the first
geographic zone. This second geographic zone 9 is of reduced size compared to the
first geographic zone and corresponds to a zone in which the requirements 5 in terms
of accuracy of geolocation of the device 1 are greater than in the rest of the first
geographic zone. As an example, this second geographic zone can correspond to a
zone situated inside a building 10 such as a warehouse or else a predefined outside
zone such as the port storage zone.
10 A plurality of second reception stations 11 are configured to receive a radio
signal transmitted from this second geographic zone 9 according to a technology
offering the desired degree of geolocation accuracy. In other words, the second
geographic zone 9 corresponds to a zone of coverage of a plurality of second stations
11 having a reduced coverage range but allowing for a better geolocation accuracy
15 compared to the first stations 5. For example, the second stations 11 are UWB
stations configured to receive a radio signal transmitted from the second geographic
zone 9 by using the UWB technology. It is clear that these second reception stations
could use another similar technology allowing a suitable degree of accuracy, that is
to say greater than the degree of accuracy offered by the first stations 5. Other high20
accuracy and low-accuracy wireless location technologies that can be used are
described, for example, in the document “A Survey of Indoor Localization Systems
and Technologies” by Faheem Zafari, Athanasios Gkelias and Kin K. Leung,
published on 4 September 2017 under the reference arXiv:1909.01015v1.
The device 1 advantageously comprises a second communication module
25 which is configured to transmit a second radio signal 21 according to characteristics
suited to the UWB technology such that the second stations 11 can receive said
second radio signal 21. However, this second communication module can assume an
inactive state, in which the device 1 does not transmit the second radio signal 21, or
an active state, in which the device 1 transmits the second radio signal 21. In this
30 active state, the second radio signal 21 can be transmitted occasionally or regularly
depending on the requirements and the desired configuration of the device 1.
16
Preferably, in order to limit the energy consumption of the device 1, the second
module is by default in an inactive state in which it consumes no or little energy.
Figure 2 is a diagram illustrating the successive steps of a geolocation
method making it possible to geolocate the signal-transmitting device 1 simply and
economically with a degree of accuracy suited to the requirements. 5 When the device
is in the first position 2 as illustrated in figure 1 in which it is situated in the first
geographic zone and outside of the second geographic zone 9, the device 1 transmits
the first radio signal 4. As explained above, the first radio signal 4 transmitted from
this first position 2 is received by the three first stations 5 (step 13). The reception
10 data relating to the reception of the first radio signal 4 by the first stations 5 are
transmitted to the remote server (step 14). The remote server 8 then calculates the
position of the device 1 from said first radio signal 4 (step 15).
The remote server 8 then compares the calculation position of the device 1
to the coordinates of the second geographic zone 9 (step 16). In other words, the
15 remote server 8 analyzes the calculated position of the device 1 to determine whether
the device 1 is situated in the second geographic zone 9 or outside of the second
geographic zone 9. For that, the remote server 8 can include or consult a database
storing the information relating to the coordinates defining the second geographic
zone 9.
20 If the remote server detects that the device 1 is outside of a zone requiring a
high degree of accuracy (step 17), for example, in the case of the first position 2, the
remote server 8 continues to await first reception data corresponding to the reception
of another first radio signal 4 to analyze whether the device 1 has moved in the second
geographic 9 or not. The remote server 8 possibly transmits the calculated position of
25 the device 1 to a third-party device that may require information on the position of the
device 1.
If, on the other hand, the device 1 has moved and has entered into the
second geographic zone 9, as illustrated by the arrow 18 in figure 1, the first radio
signal 4 is transmitted from the second geographic zone 9, illustrated by the second
30 position 3 in figure 1. Thus, when the remote server compares the calculated position
of the device 1 to the coordinates of the second geographic zone 9 (step 16), the
17
remote server 8 detects that the device 1 in this second position 3 is located in the
second geographic zone 9 (step 19). Consequently, the remote server 8 transmits an
instruction signal to the device 1 commanding the transmission of a UWB signal by
the device 1 (step 20).
This instruction signal is advantageously relayed by the first 5 stations 5 to the
device 1. Thus, the instruction signal is relayed by the first stations 5 to the device 1,
that is to say from its first communication module or from its distinct reception module
depending on the radio characteristics corresponding to the technology of the first
stations 5, for example the LoraWan technology. The reception by the device 1 of the
10 instruction signal relayed via the first stations 5 does not therefore require the prior
activation of the second communication module of said device 1. The second
communication module of the device 1 can thus remain inactive until this instruction
signal is received, which limits the consumption of the device 1.
When the device 1 receives the instruction signal it activates its UWB radio
15 transmitter, that is to say its second communication module, to transmit a second
radio signal 21 conforming to the characteristics of the UWB technology. The
activation of the second communication module to transmit the second radio signal
21 according to the UWB technology after the reception of the corresponding
instruction signal allows for energy saving in the device 1, the second communication
20 module not consuming energy to transmit the second radio signal 21 as long as it
does not receive said instruction signal.
This second radio signal 21 is received by the different second stations 11
(step 22), as illustrated by the arrows 23 in figure 1. In a way similar to the first stations
5, the second stations 11 transmit, via the communication network 7, second
25 reception data to the remote server 8 (step 24). These second reception data
comprise, for example, a date of reception of the second radio signal 21, an angle of
reception of said second radio signal 21, a quality of reception of the second radio
signal 21, geographic coordinates of the second station 11, etc. These second
reception data are used by the remote server 8 to calculate an accurate position of
30 the signal-transmitting device 1 (step 25), that is to say with a degree of accuracy
greater than the position calculated from the first radio signal 4. This accurate position
is possibly transmitted or used by the remote server depending on the requirements.
18
For example, the accurate position of the device 1 is transmitted to a stock
management application to retrieve, in a sorting center depot, the signal-transmitting
device from among a plurality of other objects.
When the device 1 transmits the second radio signal 21, it also continues to
transmit, regularly or occasionally, the first radio signal 4. The 5 remote server 8
continues to calculate the position of the device 1 from the first reception data and to
compare the position thus calculated from the first reception data to the coordinates
of the second geographic zone 9 (step 26). This check on the position of the device 1
via the first reception data (step 26) allows the remote server 8 to check the movement
10 of the device 1 and, in particular, to detect when the device 1 moves out of the second
geographic zone 9. As long as the remote server does not detect that the device 1
has left the second geographic zone 9, it continues to check the position of the
device 1 via the first reception data in parallel to its calculating of the accurate position
of the device 1 via the second reception data (step 27).
15 When the remote server 8 detects that the device 1 has moved into a position
situated outside of the second geographic zone 9 (step 28), the remote server 8
transmits a UWB instruction signal to stop transmission to the device 1 (step 29), this
stop instruction signal being, for example, relayed by the first stations 5. In fact, since
the device 1 has left the second geographic zone 9, it is no longer located in the
20 coverage zone of the second stations 11 such that said second stations 11 can no
longer receive the second radio signal 21 and transmit, to the remote server 8, second
reception data allowing a calculation of the accurate position of the device 1. On
reception of the UWB instruction signal to stop transmission, the device 1 deactivates
its second communication module transmitting in UWB mode and stops transmitting
25 the second radio signal 21 in order to save energy on said device 1.
In a preferential embodiment, in a way similar to the second communication
module transmitting in UWB mode of the device 1, the second stations 11 can assume
an active state in which they are able to receive a UWB radio signal or an inactive
state in which they are unable to receive such a radio signal in UWB mode and
30 therefore consume less energy. Thus, the second stations 11 are, by default, in the
state in order to reduce their energy consumption. The second stations 11 are,
19
however, in this inactive state, listening for the radio signals using the communication
technology of the first stations 5 with the device 1, typically the Lora technology.
When the remote server detects that the device 1 is in the second geographic
zone (step 19), it sends an activation signal to the second stations 11 (step 31). This
activation signal can be sent prior to or simultaneously with the 5 UWB transmission
instruction signal to the device 1. This signal can even be a signal in common with the
UWB mode transmission instruction signal to the device 1, transmitted via the first
stations 5.
When they receive this activation signal, the second stations 11 switch to a
10 UWB active listening state allowing them to pick up the second signal 21 transmitted
in the second geographic zone 9.
Conversely, when the remote server 8 detects that the device 1 leaves the
second geographic zone 9 (step 28), it then sends a deactivation signal to the second
stations 11 (step 33). On reception of this deactivation signal, the second stations 11
15 switch from the active state to the inactive state in order to reduce their energy
consumption.
Figure 3 illustrates a variant embodiment in which the second geographic
zone is divided into a plurality of sub-zones 32. These sub-zones 32 are joined
pairwise, possibly with a common coverage portion. Each sub-zone 32 is associated
20 with a given group of second stations 11 of the plurality of second stations 11 covering
the second geographic zone 9. The second stations 11 of the different groups of
second stations 11 are by default in an inactive state. When the remote server 8
detects that the device 1 is in the second geographic zone 9 (step 19), it compares
the position of the device 1 calculated from the first reception data to the geographic
25 coordinates of the different sub-zones 32. In a way similar to the coordinates of the
second geographic zone 9, the coordinates of the different sub-zones 32 which make
up the second geographic zone 9 are stored in a database. The remote server 8 then
determines the given sub-zone 32 in which the device 1 is located. The activation
signal of the second stations 11 (step 31) is sent to only the second stations 11
30 associated with the determined sub-zone 32.
20
When the remote server 8 checks the position of the device 1 (step 26), the
remote server checks whether the device 1 has moved or not into a new sub-zone
32. If the remote server 8 detects that the device has entered into a new sub-zone 32,
it then sends an activation signal to the second stations 11 associated with this new
sub-zone 32. Likewise, when the remote server 8 detects that the 5 device 1 has moved
out of a sub-zone 32 in which the associated group of second stations 11 was
previously activated, the remote server 8 sends a deactivation signal to said group of
second stations 11.
The geolocation system described above allows for the geolocation on a
10 large scale, that is to say at a great distance but with reduced accuracy via the first
stations 5, and on a reduced scale, that is to say at short range but with increased
accuracy, via the second stations 11 depending on the degrees of geolocation
accuracy required. Such a system makes it possible to achieve the desired degree of
geolocation accuracy with an inexpensive infrastructure that is simple to install and of
15 low consumption. In particular, this system allows for great geolocation accuracy in
predetermined zones without requiring a satellite guidance system (GPS)
incorporated in the signal-transmitting device 1.
Figure 4 illustrates a diagram illustrating the successive steps implemented
by the signal-transmitting device during its geolocation.
20 As indicated above, the signal-transmitting device 1 comprises a first
communication module configured to transmit the first radio signal 4 at a first
frequency and a second communication module configured to transmit the second
radio signal 21 at a second frequency distinct from the first frequency. In order to save
energy, the second communication module is inactive by default.
25 The device 1 transmits, regularly or on request, the first radio signal 4 (step
34). As explained above, this first radio signal makes it possible to geolocate the
device 1.
The first communication module or a reception module independent of the
first communication module is also configured to continuously listen for the instruction
30 radio signals intended for the device 1 (step 35).
21
When the device 1 receives the transmission instruction signal (step 36), the
device 1 activates the second communication module (step 37). Consequently, the
device 1 transmits, occasionally or regularly, the second radio signal 21 (step 38)
while continuing to transmit the first radio signal 4 (step 34).
Likewise, when the device 1 receives an end transmission 5 instruction signal
(step 39), the device 1 deactivates the second communication module (step 40) and
ceases transmitting the second radio signal 21 (step 41) and continues to transmit the
first radio signal (4) alone.
Although the invention has been described in relation to several particular
10 embodiments, it is clearly obvious that it is in no way limited thereto and that it
encompasses all the technical equivalents of the means described and their
combinations provided the latter fall within the framework of the invention.
Some of the elements represented, notably the components of the gateway
or the communication and/or reception modules of the signal-transmitting device, can
15 be produced in different forms, individually or distributed, by means of hardware
and/or software components. Hardware components that can be used are the
application-specific integrated circuits ASIC, the programmable logic arrays FPGA or
microprocessors. Software components can be written in various programming
languages, for example C, C++, Java or VHDL. This list is not exhaustive.
20 Use of the verb “comprise”, or “include” and its conjugated forms does not
preclude the presence of elements or steps other than those stated in a claim.
In the claims, any reference symbol between brackets should not be
interpreted as a limitation on that claim.
22
WE CLAIM:
1. A method for geolocating a signal-transmitting device (1), the
geolocation method comprising:
 supplying first reception data (14), said first reception data 5 resulting from
the reception (13) by a plurality of first reception stations (5) of a first radio
signal (4) transmitted at a first frequency by the signal-transmitting device
(1), said first reception stations (5) defining a first geographic coverage
zone,
10  calculating (15) a first geographic position of the signal-transmitting
device (1) in the first geographic coverage zone from the first reception
data,
 detecting (19) that the geographic position of the signal-transmitting
device (1) is included in a predefined second geographic zone (9) by
15 comparing (16) the first geographic position of the signal-transmitting
device calculated at the coordinates of the second geographic zone (9),
the second geographic zone (9) being included in the first geographic
coverage zone,
 transmitting (20) a transmission instruction signal to the signal20
transmitting device (1) in response to the detection that the geographic
position of the signal-transmitting device is in the second geographic
zone, the transmission instruction signal being intended to trigger the
transmission of a second radio signal (21) at a second frequency distinct
from the first frequency by the signal-transmitting device (1), said first
25 frequency being lower than the second frequency,
 supplying second reception data (24), said second reception data
resulting from the reception (22) of the second radio signal (21) by a
plurality of second reception stations (11), said second reception stations
(11) being able to receive a radio signal at the second frequency
30 transmitted from the second geographic zone (9), and
23
 calculating (25) a second geographic position of the signal-transmitting
device (1) in the second geographic zone (9) from the second reception
data.
2. The geolocation method as claimed in claim 1, wherein, prior to the
transmission (20) of the transmission instruction signal, the second 5 reception stations
(11) are in an inactive state in which said second reception stations (11) are unable
to receive a radio signal at the second frequency transmitted from the second zone
(9), the method further comprising, prior to the transmission (20) of the transmission
instruction signal:
10 - transmitting (31) an activation signal for the second reception stations
(11) to activate the second reception stations (11) so that said second
reception stations (11) are configured to receive a radio signal at the
second frequency transmitted from the second geographic zone (9).
3. The geolocation method as claimed in claim 1, wherein:
15 - the predefined second geographic zone (9) comprises a plurality of
geographic sub-zones (32),
- the plurality of second reception stations (11) comprises a plurality of
groups of second reception stations (11), each group of second
reception stations (11) being able to receive a radio signal at the
20 second frequency transmitted from one said respective geographic
sub-zone (32),
and wherein
- the step of detecting (19) that the geographic position of the signaltransmitting
device (1) is included in the predefined second
25 geographic zone (9) comprises detecting that the geographic position
of the signal-transmitting device (1) is included in a given geographic
sub-zone (32) of the plurality of geographic sub-zones (32),
- the second reception data result from the reception of the second
radio signal (21) by a given group of second reception stations (11)
24
able to receive a radio signal transmitted at the second frequency in
said given geographic sub-zone (32).
4. The geolocation method as claimed in claim 3, wherein, prior to the
transmission (20) of the transmission instruction signal, the second reception stations
(11) are in an inactive state in which said second reception stations 5 (11) are unable
to receive a radio signal at the second frequency transmitted from the second
geographic zone (9), the method further comprising, prior to the transmission (19) of
the transmission instruction signal and after the detection that the geographic position
of the signal-transmitting device (1) is included in the given geographic sub-zone (32):
10 - transmitting an activation signal for the second reception stations (11)
of the given group of second reception stations (11) so that said
second reception stations (11) are configured to receive the second
radio signal (21) at the second frequency.
5. The geolocation method as claimed in claim 4, further comprising,
15 after the calculation of the second geographic position of the signal-transmitting
device (1):
- detecting that the geographic position of the signal-transmitting
device (1) is situated outside of said given geographic sub-zone (32),
- transmitting a deactivation signal for the second reception stations
20 (11) of the given group of second reception stations (11) so that said
second reception stations (11) are rendered inactive.
6. The geolocation method as claimed in one of claims 1 to 5, further
comprising, after the calculation (25) of the second geographic position of the signaltransmitting
device (1):
25 - detecting (28) that the geographic position of the signal-transmitting
device (1) is situated outside of the second geographic zone (9),
- transmitting (29) an end of transmission instruction signal to the
signal-transmitting device (1) to interrupt the transmission of the
second radio signal (21) at the second frequency by the signal30
transmitting device (1).
25
7. The geolocation method as claimed in one of claims 1 to 6, further
comprising:
- detecting (28) that the geographic position of the signal-transmitting
device (1) is situated outside of the second geographic zone (9),
- transmitting (33) a deactivation signal for the 5 second reception
stations (11) so that said second reception stations (11) are inactive.
8. The geolocation method as claimed in one of claims 1 to 7, wherein
the reception data of the first signal comprise, for each first reception station (5) having
received the first radio signal, a datum of identification of said first radio signal (4), a
10 datum of date of reception of said first radio signal (4) and a datum of position of said
first reception station (5).
9. The geolocation method as claimed in claim 8, wherein the
reception data of the first radio signal (4) further comprise a datum of intensity of
reception of said first radio signal (4).
15 10. The geolocation method as claimed in one of claims 1 to 9, wherein
the reception data of the second signal comprise, for each second reception station
(11) of the plurality of second reception stations (11) having received the second radio
signal (21), a datum of identification of said second radio signal (21), a datum of date
of reception of said second radio signal (21) and a datum of position of the second
20 reception station (11).
11. The geolocation method as claimed in claim 10, wherein the
reception data of the second radio signal (21) further comprise, for each second
reception station (11), an angle of reception and an intensity of reception of said
second radio signal (21).
25 12. The geolocation method as claimed in one of claims 1 to 12, wherein
the first radio signal (4) is a frame of a LoRaWan communication protocol.
13. The geolocation method as claimed in one of claims 1 to 13, wherein
the second radio signal (21) is a frame of a UWB communication protocol.
26
14. A system for geolocating a signal-transmitting device (1), the
geolocation system comprising:
- a plurality of first reception stations (5), said first reception stations
(5) defining a first geographic coverage zone, said first reception
stations (5) being configured to receive a first 5 radio signal (4)
transmitted by the signal-transmitting device (1) at a first frequency
and from the first geographic coverage zone, the first reception
stations (5) being configured to generate the first reception data
resulting from the reception of said first radio signal (4),
10 - a plurality of second reception stations (11), said second reception
stations (11) being configured to receive a second radio signal (21)
transmitted by the signal-transmitting device (1) at a second
frequency distinct from the first frequency and from a predefined
second geographic zone (9), the second geographic zone (9) being
15 included in the first geographic coverage zone, the second reception
stations (11) being configured to generate second reception data
resulting from the reception of the second radio signal (21),
- a communication network (7), the first reception stations (5) being
connected to said communication network (7) and configured to
20 transmit the first reception data to a remote server (8) via the
communication network (7), the second reception stations (11) being
connected to said communication network (7) and configured to
transmit the second reception data to said remote server (8) via the
communication network (7),
25 wherein, the remote server (8) is configured to:
- calculate a first geographic position of the signal-transmitting device
(1) in the first geographic coverage zone from the first reception data,
- detect that the geographic position of the signal-transmitting device
(1) is included in the predefined second geographic zone (9) by
30 comparing (16) the first geographic position of the signal-transmitting
27
device calculated at the coordinates of the second geographic zone
(9),
- transmit a transmission instruction signal to the signal-transmitting
device (1) in response to the detection that the geographic position
of the signal-transmitting device is in the second 5 geographic zone,
the transmission instruction signal being intended to trigger the
transmission of the second radio signal (21) by the signal-transmitting
device (1),
- calculate a second geographic position of the signal-transmitting
10 device (1) in the second geographic zone (9) from the second
reception data.