WO2019002410A1

WO2019002410A1 - Communication device for a motor vehicle, comprising a central electronic unit and a secondary electronic unit

Info

Publication number: WO2019002410A1
Application number: PCT/EP2018/067325
Authority: WO
Inventors: Laurent Petel; Christophe Gueble
Original assignee: Valeo Comfort And Driving Assistance
Priority date: 2017-06-28
Filing date: 2018-06-27
Publication date: 2019-01-03
Also published as: FR3068551A1; FR3068551B1

Abstract

The invention relates to a communication device (DISP) for a motor vehicle, comprising: - a central electronic unit (PE) designed: - to receive from a user terminal (SP) or to broadcast to the user terminal a primary advertisement frame (ADV_C1) comprising primary communication parameters (P1) for establishing a connection therewith and for connecting therewith so as to open a primary secure communication channel (CH1) therewith, to exchange data frames (DF) therewith over data channels (CD) of the primary secure communication channel (CH1); - to receive from at least one secondary electronic unit (BA) or to broadcast to the at least one secondary electronic unit a secondary advertisement frame (ADV_C2) to establish a connection therewith and to connect therewith so as to open a secondary secure communication channel (CH2) therewith, and to transmit thereto the primary communication parameters (P1) over the secondary secure communication channel (CH2); - the at least one secondary electronic unit (BA) designed to receive from the central electronic unit (PE) or to broadcast to the central electronic unit the secondary advertisement frame (ADV_C2), to receive from the central electronic unit the primary communication parameters (P1) over the secondary secure communication channel (CH2), and according to the primary communication parameters (P1), to scan the data channels (CD) used of the primary secure communication channel (CH1), and to intercept data frames (DF) exchanged between the central electronic unit and the user terminal over the thus scanned data channels (CD).

Description

COMMUNICATION DEVICE FOR A MOTOR VEHICLE COMPRISING A CENTRAL ELECTRONIC UNIT AND A UNIT

SECONDARY ELECTRONICS

DOMAI N E TECH AND I NVENTION

The present invention relates to a communication device for a motor vehicle.

It finds a particular but non-limiting application in the field of motor vehicles.

BACKGROUND TECHNOLOGY OF THE I NVE NTIO N

In the field of motor vehicles, a communication device for a motor vehicle, known to those skilled in the art, comprises:

- a central electronic unit;

- at least secondary electronic unit.

Conventionally, the communication device comprises a plurality of secondary electronic units and is used for a location application of a user terminal relative to the motor vehicle.

As part of this application,

- the central electronic unit adapted for:

- receive advertisement frames broadcast by at least one secondary electronic unit; and

transmitting said advertisement frames to a user terminal;

the secondary electronic units are adapted to broadcast said ad frames.

Subsequently, the user terminal is adapted to perform power measurements in reception of said announcement frames sent by said central electronic unit and to deduce its position relative to said motor vehicle. A disadvantage of this state of the art is that the announcement frames sent by the different secondary electronic units are sent asynchronously. Also, there is a risk of collisions between the advertisement frames sent by the different secondary electronic units, which leads to errors on the reception power measurements and consequently on the location of the user terminal relative to the motor vehicle.

In this context, the present invention aims to solve the aforementioned drawback.

GENERAL DESCRIPTIONS OF THE I NVE NTIO N

To this end, the invention proposes a communication device for a motor vehicle, according to which said communication device comprises:

- a central electronic unit adapted for:

receiving from a user terminal or broadcasting for said user terminal a primary announcement frame to establish a connection with it, said primary announcement frame comprising primary communication parameters;

- connect to said user terminal so as to open a primary secure communication channel with him;

exchanging data frames with said user terminal on data channels of said primary secure communication channel;

receiving at least one secondary electronic unit or broadcasting for said at least one secondary electronic unit a secondary announcement frame to establish a connection with it;

connecting to said at least one secondary electronic unit so as to open a secondary secure communication channel with it;

transmitting said primary communication parameters to said at least one secondary electronic unit in said secondary secure communication channel;

said at least one secondary electronic unit adapted for: receiving from said central electronic unit or broadcasting for said central electronic unit said secondary announcement frame;

receiving from said central electronic unit said primary communication parameters in said secondary secure communication channel;

according to said primary communication parameters, scanning used data channels of said primary secure communication channel;

intercepting data frames exchanged between said central electronic unit and said user terminal on said data channels thus scanned.

Said at least one secondary electronic unit is adapted to receive from said central electronic unit said primary communication parameters in said secondary secure communication channel so as to synchronize with said at least one central electronic unit.

Thus, as will be seen in detail later, it is the secondary electronic units that themselves perform power measurements in receiving data frames and no longer the user terminal. The frames which serve as a basis for the power measurements in reception are thus frames of data sent by the user terminal and no longer frames of announcement sent by the secondary electronic units. Since the frames are frames from a single transmitter there is no risk of collisions, unlike the state of the prior art where said frames are from several transmitters at a time.

According to non-limiting embodiments, the communication device may further comprise one or more additional characteristics from the following.

According to a non-limiting embodiment, said at least one secondary electronic unit is a beacon. According to a non-limiting embodiment, said at least one secondary electronic unit is further adapted to:

performing power measurements on reception of said intercepted data frames;

transmitting said power measurements in reception to said central electronic unit.

According to one nonlimiting embodiment, said primary communication parameters comprise in particular:

- a connection interval;

- a channel jump between a first data channel used and the next;

- a mapping of the data channels;

- a scanning window;

- master clock accuracy.

According to a non-limiting embodiment, said at least one secondary electronic unit is adapted to scan said data channels of said primary secure communication channel according to said scanning window.

According to a nonlimiting embodiment, if said at least one secondary electronic unit has failed to intercept a complete exchanged data frame, the scanning window is widened. Thus, if said at least one secondary electronic unit has failed to synchronize with said central electronic unit, the scanning window is enlarged.

According to a non-limiting embodiment, said central electronic unit is further adapted to:

calculating the position of the user terminal relative to the motor vehicle according to said power measurements in reception; or

transmitting said power measurements in reception to said user terminal so that the latter can calculate its position relative to said motor vehicle.

According to a nonlimiting embodiment, which said central electronic unit and said at least one beacon are adapted to communicate with each other according to the Bluetooth Low Energy ™ communication protocol.

According to a non-limiting embodiment, said at least one secondary electronic unit comprises at least two antennas.

According to a non-limiting embodiment, said central electronic unit comprises at least two antennas.

According to a non-limiting embodiment, said at least two antennas have the same radiation pattern.

According to a non-limiting embodiment, said at least two antennas have a different radiation pattern.

According to a nonlimiting embodiment, said at least two antennas are arranged relative to each other so that their radiation patterns are oriented differently relative to each other.

According to a non-limiting embodiment, said connection device comprises a plurality of secondary electronic units.

According to one nonlimiting embodiment, the beacon is configured to:

alternating the broadcasting of its secondary announcement frames via one or the other of the two antennas; or

- broadcast its secondary announcement frames via both antennas at the same time.

According to one nonlimiting embodiment, the beacon is configured to:

transmitting said power measurements in reception via one or the other of the two antennas; or

transmitting said power measurements in reception via the two antennas at the same time.

According to a nonlimiting embodiment, said communication device comprises a plurality of secondary electronic units. It is also proposed a user terminal adapted to communicate with a central electronic unit of a communication device for a motor vehicle, said user terminal being adapted to:

- Receive from a central electronic unit or broadcast for said central electronic unit a primary announcement frame to establish a connection with it, said primary announcement frame including primary communication parameters;

- connect to said central electronic unit so as to open a primary secure communication channel with it;

sending data frames to said central electronic unit on data channels of said primary secure communication channel.

According to a non-limiting embodiment, said user terminal is further adapted to:

receiving power measurements in reception of said data frames of said central electronic unit; and

calculate its position with respect to said motor vehicle as a function of said reception power measurements; or

receiving its position relative to said motor vehicle of said central electronic unit.

According to a non-limiting embodiment, said user terminal is an identifier, a mobile phone, a tablet, a badge.

It is also proposed a communication system for a motor vehicle comprising a communication device according to any one of the preceding characteristics and a user terminal according to any one of the preceding characteristics.

BRIEF DESCRIPTION OF THE FIGURES

The invention and its various applications will be better understood by reading the following description and examining the figures that accompany it. - Figure 1 shows a motor vehicle comprising a communication device for a motor vehicle according to a non-limiting embodiment of the invention, said communication device comprising a central electronic unit and a plurality of secondary electronic units;

FIG. 2 represents the communication device of FIG. 1 and exchanges between said central electronic unit and said plurality of secondary electronic units, and between said central electronic unit and a user terminal;

FIG. 3 represents a diagram of a communication system comprising the communication device of FIGS. 1 and 2 and the user terminal of FIG. 2;

FIG. 4 represents a diagram of data channels scanned by said plurality of secondary electronic units of FIGS. 1 to 3;

FIG. 5 represents a diagram of a synchronization between the central electronic unit and a secondary electronic unit of FIGS. 1 to 4;

FIG. 6 is a timing diagram of a communication between the central electronic unit PE and a user terminal and a communication between the central electronic unit PE and a beacon BA of FIGS. 1 to 5;

FIG. 7 represents a first radiation pattern of one or two antennas in the central electronic unit or in said plurality of secondary electronic units, according to one nonlimiting embodiment;

FIG. 8 represents a second radiation pattern of one or two antennas in the central electronic unit or in said plurality of secondary electronic units, according to one nonlimiting embodiment;

FIG. 9 represents a radiation diagram corresponding to the union of two radiation patterns of FIG. 7, according to a non-limiting embodiment;

- Figure 10 shows a radiation pattern corresponding to the union of two radiation patterns of Figure 7 and Figure 8, according to a non-limiting embodiment. DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Identical elements, structure or function, appearing in different figures retain, unless otherwise specified, the same references.

The invention relates to a communication device DISP for a motor vehicle V.

Said communication device DISP is described with reference to FIGS. 1 to 6. As illustrated in FIGS. 1 and 2, the communication device DISP comprises:

- a central electronic unit PE

at least one secondary electronic unit BA.

In a non-limiting embodiment, said central electronic unit PE and said at least one secondary electronic unit BA are adapted to communicate with one another according to the Bluetooth Low Energy ™ communication protocol called BLE. BLE allows for two-way data exchange at short distances. It uses so-called RF radio waves on a 2.4GH frequency band.

In a non-limiting embodiment, said central electronic unit PE and said at least one secondary electronic unit BA are adapted to communicate with one another according to the communication protocol CAN ("Controller Area Network" in English) or LIN ("Local Interconnect Network"). " in English). For this purpose, there is a wired connection network between said central electronic unit PE and said at least one secondary electronic unit BA.

Said central electronic unit PE and said at least one secondary electronic unit BA are adapted to communicate with one another. SP user terminal. In a non-limiting embodiment, they communicate with said user terminal SP according to the BLE communication protocol.

The communication device DISP and the user terminal SP thus form a SYS communication system for a motor vehicle as illustrated in FIG.

In a nonlimiting embodiment illustrated, the communication device DISP comprises a plurality of secondary electronic units BA.

For the remainder of the description, the term device will be used to indicate a user terminal SP or a secondary electronic unit BA or a central electronic unit PE.

In a non-limiting embodiment, the secondary electronic unit BA is a beacon. In the remainder of the description, the term "secondary electronic unit" or "beacon" will be used interchangeably.

In a nonlimiting example illustrated in FIGS. 1 and 2, the communication device DISP comprises six beacons BA1 to BA6.

In a nonlimiting embodiment illustrated in FIG. 1, said central electronic unit PE is a connectable computer CAC to an NTW network of the motor vehicle V. This network is in a non-limiting example a LIN network ("Local internetwork" in English ) or CAN ("Controller Area

Network ").

The user terminal SP as well as the elements of the communication device DISP are described in detail below. · Te "rmj.naJ. ut | ljsateur jS "P

The user terminal SP is illustrated in FIGS. 2, 3 and 6.

In a non-limiting embodiment, the user terminal SP comprises a display screen E.

In non-limiting examples, the user terminal SP is an identifier, a badge, a tablet, a mobile phone such as in a non-limiting example a so-called smart phone ("Smartphone in English") used by a user of the motor vehicle V.

As illustrated in FIG. 3, the user terminal SP is adapted to be:

- in a scanning mode (scanning mode in BLE technology). For this purpose, it is adapted to perform a scan of CA announcement channels to receive ADV announcement frames broadcast by electronic units BA or PE;

- in a broadcast mode ("advertising" mode in BLE technology). For this purpose, it is adapted to broadcast an ADV announcement frame on the CA announcement channels.

For this purpose, as illustrated in FIG. 3, the user terminal SP comprises a wireless communication module MCO which thus comprises a BLE antenna in a nonlimiting example which serves as a transmitter / receiver. The wireless communication module MCO of the user terminal SP makes it possible to establish a wireless link (in this case "Bluetooth Low Energy ™") with the wireless communication module MC2 of a beacon BA of the motor vehicle V or the communication module wireless MC1 of the central electronic unit PE. The user terminal SP is thus adapted for:

- receive the advertisement frames broadcast by the electronic units BA or PE.

In particular, in non-limiting embodiments, it is suitable for:

- receive from a central electronic unit PE (function illustrated in Figure 3 RX (SP, PE, ADV_C1 (P1)) or broadcast (function shown in Figure 3 BRD (SP, PE, ADV_C1 (P1)) for said unit central electronic means PE primary announcement frame ADV_C1 for establishing a connection with said central electronic unit PE, said primary announcement frame ADV_C1 comprising primary communication parameters P1;

connecting to said central electronic unit PE so as to open a primary secure communication channel CH1 comprising CD data channels with said user terminal SP (function illustrated in FIG. Figure 3 CONNCT (SP, PE, CH1)). For this purpose, it broadcasts a connection request CONNECT_REQ on a CA announcement channel for said central electronic unit PE.

When the primary secure communication channel CH1 is open, the user terminal SP is further adapted to:

sending data frames DF to said central electronic unit PE on CD data channels of a primary secure communication channel CH1 (function illustrated in FIG. 3 TX (SP, PE, DF, CD, CH1));

receiving DF data frames from said central electronic unit PE on CD data channels of a primary secure communication channel CH1 (function illustrated in Figure 3 RX (SP, PE, DF, CD, CH1)).

A user can control the execution of a function Fct by means of the user terminal SP. In non-limiting embodiments, the function Fct is a locking / unlocking of the motor vehicle V to access said motor vehicle V or a starting of the motor vehicle V or any other function requiring or not a location of the user terminal SP. The Fct function thus allows access to the motor vehicle V, that is to say that it can open / close an opening of the vehicle (door or trunk). The procedure for access to a motor vehicle or startup via a user terminal SP is well known to those skilled in the art, it is not described here.

To be used with a motor vehicle V, the user terminal SP must be paired with said motor vehicle V. The pairing is performed after the user terminal SP has been authenticated when it is close to the motor vehicle V. Such a authentication being known to those skilled in the art, it is not described here. When the user terminal SP is paired, a primary secure communication channel CH1 can subsequently be established with the motor vehicle V (via the central electronic unit PE). Moreover, for reasons of safety, the execution of a function Fct of the motor vehicle V is conditioned by the location of the user terminal SP with respect to the motor vehicle V, namely by the POS position to which it is in relation to to the motor vehicle V. In a non-limiting example, the unlocking of the motor vehicle V can be performed when the user terminal SP is close to the motor vehicle V, at a distance substantially less than or equal to 2m (meters) in the example non-limiting best practice recommended by organizations referring in the field as the British consortium "Thatcham".

Measuring a distance between the user terminal SP and the motor vehicle V is performed by means of the power measurement of a received signal whose initial power is known, namely the power at the transmission of said signal is known , which makes it possible to deduce the distance between the transmitter and the receiver by an evaluation of the signal power drop due to the free space separating the motor vehicle V from the user terminal SP. The transmitter is here a secondary electronic unit BA or central PE of the motor vehicle V and the receiver is the user terminal SP.

This method is called RSSI (Received Signal Strength Indication).

In a non-limiting embodiment, the user terminal SP is thus further adapted to:

receiving RSSI power measurements of signals received from said central electronic unit PE (function illustrated in FIG. 3 RX (SP, PE, RSSI)). In the remainder of the description, the terms power measurement in RSSI reception or RSSI measurement will be indifferently used. As will be seen below, the received signals are DF announcement frames; and

calculating its POS position relative to said motor vehicle V as a function of said RSSI receiving power measurements (function illustrated in FIG. 3 CALC (SP, POS, RSSI)). Said measures power on reception RSSI indicates the distance to which the user terminal SP is in relation to each beacon BA. Thus, the position POS is calculated from each distance to which it is in relation to each beacon BA; or

receiving its POS position with respect to said motor vehicle V of said central electronic unit PE (function illustrated in FIG. 3 RX (SP, PE, POS)).

To improve the measurement of the POS position, a plurality of secondary electronic units BA is thus used.

It should be noted that the user terminal SP can receive ADV announcement frames broadcast by the beacons BA before they are connected to the central electronic unit PE, said announcement frames ADV having no particular addressee, but in this case, the user terminal SP ignores them, it does not manage them.

· Unjected.

The central electronic unit PE is illustrated in FIGS. 1 to 6.

The central electronic unit PE is also called central transceiver or "central transceiver" in English.

In a non-limiting embodiment illustrated in FIG. 2, the central electronic unit PE is adapted to manage the supply Vcc of a beacon BA. In this case, a wire F connects the central electronic unit PE to each beacon BA. There are thus six power supply wires F in the example of the six beacons BA1 to BA6. The central electronic unit PE comprises a switching device (not shown) of the supply Vcc of each beacon BA. In a non-limiting embodiment, the switching device comprises a switch (not shown) associated with each BA tag to activate their power supply or disable their Vcc power supply. It will be noted that the central electronic unit PE is powered by a supply Vcc which is supplied by a battery of the motor vehicle V. In a nonlimiting example, the battery supplies a supply Vcc substantially equal to 12Volts. The central electronic unit PE is in a mode called connectable MODc because it can establish a connection with the user terminal SP and at least one secondary electronic unit BA.

In particular, the central electronic unit PE is adapted to

connecting to said user terminal SP so as to open a primary secure communication channel CH1 with said user terminal SP (function illustrated in FIG. 3 CONNCT (PE, SP, CH1). For this purpose it broadcasts a connection request CONNECT_REQ on a CA announcement channel for said user terminal SP.

Said connection is made following receipt of a primary announcement frame ADV_C1, also called primary connection announcement frame;

connecting to at least one secondary electronic unit BA so as to open a secondary secure communication channel CH2 with said at least one secondary electronic unit BA function illustrated in FIG. 3 CONNCT (PE, BA, CH2). For this purpose it broadcasts a connection request CONNECT_REQ on a CA announcement channel for said BA tag.

Said connection is made following the reception of a secondary announcement frame ADV_C2, also called secondary connection announcement frame, described below.

It is adapted to be in a broadcast mode or in a scan mode. For this purpose, the central electronic unit PE comprises a wireless communication module MC1 which comprises a BLE antenna in a non-limiting example which serves as transmitter / receiver.

In the broadcast mode, the central electronic unit PE is adapted to broadcast a plurality of advertisement frames ADV in specific channels, known as advertising channels (CAs) distinct from CD data channels. (in English: "data channels") used to transmit frames of exchange of application data relative to established connections. The BLE protocol provides for 3 CA announcement channels referenced channel 37, channel 38 and channel 39 according to the BLE protocol and having respective central frequencies equal to 2402 MHz, 2426 MHz, 2480 MHz, and 37 CD data channels (referenced channel 0 at channel 36). The three CA announcement channels are spread over the 2.4GHz frequency band. Thus the 3 CA announcement channels respectively have central frequencies located at the lower end, in a central region and at the upper end of the frequency band concerned (here the 2.4 GHz band). The CD data channels are spread over frequencies between 2400 MHz and 2480 MHz every 2 MHz.

For the connection with the user terminal SP, in a first nonlimiting embodiment, the central electronic unit PE is adapted to broadcast for said user terminal SP a primary announcement frame ADV_C1 to establish a connection with it, said frame of primary announcement ADV_C1 comprising primary communication parameters P1 (function illustrated in FIG. 3 BRD (PE, SP, ADV_C1 (P1)).)). In this case, the central electronic unit PE is slave SI while the user terminal SP is master Ms. It is him who will initiate the connection by sending a request CONNECT_REQ connection.

For connection with the beacon BA, in a first nonlimiting embodiment, the central electronic unit PE is adapted to broadcast for said beacon BA a secondary announcement frame ADV_C2 to establish a connection with it, said announcement frame secondary ADV_C2 comprising secondary communication parameters P2 (function illustrated in FIG. 3 BRD (PE, BA, ADV_C2 (P2)) In this case, the central electronic unit PE is slave SI while the beacon BA is master Ms. It will initiate the connection by sending a CONNECT_REQ connection request.

In the scanning mode, the central electronic unit PE is adapted to scan said CA announcement channels to receive: an ADV announcement frame broadcast by the BA beacons; or an ADV advertisement frame broadcast by the user terminal SP.

For the connection with the user terminal SP, in a second non-limiting embodiment, the central electronic unit PE is adapted to receive from said user terminal SP a primary announcement frame ADV_C1 to establish a connection with it, said frame of primary announcement ADV_C1 including P2 secondary communication parameters (function illustrated in Figure 3 RX (PE, SP, ADV_C1 (P1)). In this case, the central electronic unit PE is master Ms while the user terminal SP is slave SI It is the central electronic unit PE which will initiate the connection by sending a request in CONNECT_REQ connection For the connection with the beacon BA, in a second nonlimiting embodiment, the central electronic unit PE is adapted to receiving from said beacon BA a secondary announcement frame ADV_C2 to establish a connection with it, said secondary announcement frame ADV_C2 including communication parameters P2 secondary ion (function shown in Figure 3 RX (PE, BA, ADV_C2 (P2)). In this case, the central electronic unit PE is master Ms while the beacon BA is slave SI. It is the central electronic unit PE that will initiate the connection by sending a request in connection CONNECT_REQ. Thus, for connections with the user terminal SP or the beacon

BA, the central electronic unit PE is initialized in broadcast mode or in scan mode according to the adopted strategy (master-slave). The strategy is determined during the design of the DISP communication device.

Following the connection with said user terminal SP, the central electronic unit PE is further adapted to exchange DF data frames on CD data channels with said user terminal SP, these data channels CD being part of the communication channel secured primary CH1. So she can:

receiving DF data frames from said user terminal SP on the CD data channels of a secure communication channel CH1 primary (function shown in Figure 3 RX (PE, SP, DF, CD, CH1)

transmitting DF data frames to said user terminal SP on the CD data channels of a primary secure communication channel CH1 (function illustrated in FIG. 3 TX (PE, SP, DF, CD, CH1)). In a non-limiting embodiment, the central electronic unit PE is adapted to perform RSSI reception power measurements of the DF data frames received from the user terminal SP (function illustrated in FIG. 3 MEAS (PE, DF, RSSI) This makes it possible to take into account the environment of the motor vehicle V, in the case where for example the signal sent by the user terminal SP (namely the DF data frames) bounces on an obstacle around the motor vehicle V.

Following the connection of a BA beacon, the central electronic unit PE is furthermore adapted to exchange DF data frames on CD data channels with said BA beacon, these CD data channels being part of the secure communication channel. secondary CH2. Thus the central electronic unit PE can:

receiving DF data frames from said BA beacon on a CD data channel of a secondary secure communication channel CH2 (function illustrated in Figure 3 RX (PE, BA, DF, CD, CH2)).

transmitting DF data frames to said BA beacon on a CD data channel of a secondary secure communication channel CH2. In particular, it can transmit said primary communication parameters P1 to said at least one secondary electronic unit BA in said secondary secure communication channel CH2 (function illustrated in FIG. 3 RX (PE, BA, P1, DF, CD, CH2) ).

In a non-limiting embodiment, said primary communication parameters P1 comprise, in a manner known to those skilled in the art, in particular:

- a) the address of the transmitter Adr1 (PE or SP);

- b) the address of the recipient AdrO (PE or SP); - c) a scanning window W1:

d) a window offset Wo1;

e) a connection interval 11;

f) SL1 latency;

- g) a maximum supervision time TM1;

h) a mapping of the MP1 data channels;

i) a channel hop Hp1 between a first data channel CD used and the next CD;

j) a master clock accuracy SCA1.

The primary communication parameters P1 will allow BA beacons to synchronize with the central electronic unit PE. The synchronization will allow said BA beacons to listen to the data channel CD of the primary secure communication channel CH1 which is used at a given instant for the exchange of DF data frames between said central electronic unit PE and said user terminal SP. Thus, the BA beacons will be able to listen to the used CD data channel and intercept the DF data frames thus exchanged. It will be noted that the BA beacons will perform RSSI reception power measurements of the DF data frames thus intercepted. The purpose of synchronization is thus to open a window for receiving DF data frames at the right time and on the correct data channel CD.

Note that in a non-limiting embodiment, primary communication parameters P1 further include a CRC ("Cyclic Redundancy Check") adapted to secure the primary secure communication channel CH1.

The primary communication parameters P1 c) to j) are described in detail below.

c) The scan window W1 is the length of time a receiver waits for a DF data frame. In a non-limiting embodiment, the scanning window W1 is a multiple of 1.25ms (milliseconds) between 1.25ms and the smallest of the times between 10ms and 11 -1.25ms. So, the beacon BA will be able to listen during this period, in particular to intercept the first DF data frame sent by the user terminal SP to the central electronic unit PE. Synchronization is performed upon receipt of this first DF data frame.

d) The window offset Wo1 indicates the offset of a frame transmission with respect to the connection interval 11. This indicates when the scan window W1 begins. In a non-limiting embodiment, the window offset Wo1 is a multiple of 1.25ms between 0 and 11.

e) The connection interval 11 is a time interval between two successive connections between the transmitter and the receiver, namely between two CONNECT_REQ connection requests. In a nonlimiting example, the connection interval 11 is a multiple of 1, 25ms between 7.5ms and 4s (seconds). The connection interval 11 determines the time frequency of appointments.

f) the SL1 latency between 0 and 499 indicates a time during which the slave can ignore ADV_C connection announcement frames. In a nonlimiting embodiment, SL1 <(TM1 / 11) - 1).

g) The maximum supervision time TM1 indicates the maximum delay between two received DF data frames correctly before the primary secure communication channel CH1 is considered lost. In a non-limiting example, the maximum time interval TM1 is a multiple of 10ms between 100ms and 32s. In a nonlimiting embodiment, TM1> (1 + SL1) ^* (2 ^* 11). Thus, following the reception of a first data frame DF, after the delay TM1, if no data frame DF is received, the primary secure communication channel CH1 is considered lost.

h) The mapping of the data channels MP1 gives the list of the data channels CD which can be used during the communication between the user terminal SP and the central electronic unit PE.

i) The Hp1 channel jump gives: the number of the first data channel CD used for the exchange of the DF data frames;

- the hop to be added to the first CD data channel to obtain the next CD data channel to be used. In a non-limiting example, the jump is between 5 and 1 6.

The number of the data channel CD and the jump thus make it possible to define an appointment frequency, each data channel CD being at a certain frequency.

j) In a non-limiting embodiment, the master clock accuracy SCA1 is substantially equal to 30ms.

The master clock accuracy SCA1 allows the slave SI to synchronize with the master MS, here the central electronic unit PE in a non-limiting example. Thus, by recovering the clock accuracy SCA1 from the central electronic unit PE, the beacon BA will be able to synchronize with it. On the other hand, master clock precision SCA1 is also used when the synchronization has not succeeded to widen the scanning window W1. Note that the synchronization was not successful when the connection goes wrong, for example, each device has a time clock too different, or well there are too many radio disturbances and DF data frames do not arrive. .

In a non-limiting embodiment illustrated in FIG. 5, the widening Woff of the scanning window W1 is substantially equal to: (master clock accuracy SCA1 + slave clock accuracy SCA2 / 1000000) ^* ! 1). FIG. 5 also illustrates the inter-frame time interval TJFS ("Inter Frame Space" in English).

In the context of the application of locating the POS position of the user terminal SP, in a non-limiting embodiment, the central electronic unit PE is furthermore adapted to: receive from the beacon BA power measurements in reception RSSI DF data frames (function illustrated in Figure 3 RX (PE, BA, RSSI)).

Subsequently, in a non-limiting embodiment, the electronic unit Central PE is also suitable for:

calculating the POS position of the user terminal SP with respect to the motor vehicle according to said RSSI receiving power measurements (function illustrated in FIG. 3 CALC (PE, POS (SP)) and transmitting said POS position to said user terminal SP (function illustrated in Figure 3 TX (PE, SP, POS)) or

transmitting said RSSI reception power measurements to said user terminal SP (function illustrated in FIG. 3 TX (PE, SP, RSSI)) so that the latter can calculate its POS position relative to said automotive vehicle V.

Finally, in a non-limiting embodiment, the central electronic unit PE is further adapted to:

- Validate the authentication of the user terminal SP which allows to execute the function Fct (function not shown);

- Activate the function to be executed Fct such as locking / unlocking the motor vehicle, starting the motor vehicle etc. (function not shown).

In a non-limiting embodiment, said central electronic unit PE comprises at least two antennas. In a non-limiting embodiment variant, it comprises two antennas A1 ', A2'. Thus, as illustrated in FIG. 3, the wireless communication module MC1 of the central electronic unit PE comprises the two antennas A1 ', A2'. Each antenna Α1 ', A2' comprises a radiation pattern R. The union of the radiation patterns R of the two antennas A1 ', A2' corresponds to a radio signature of the electronic unit PE.

In a first nonlimiting embodiment, the two antennas Α1 ', A2' have the same radiation pattern R. A non-limiting example of a radiation pattern R is illustrated in FIG. 7. At point K for example, there is a RSSk measurement for a distance dK. This distance dK corresponds to -40dBm. Inside the hatched surface, for example at the point J illustrated in FIG. 5, the measurement RSSIj will be stronger than the measurement RSSI _K. Thus, the distance dj is less than the distance d ".

Outside the hatched surface, for example at the point Q illustrated in FIG. 7, the power will be lower. Thus, the distance ÔQ is greater than the distance d ".

According to this first nonlimiting embodiment, in addition to having the same radiation pattern R, the two antennas Α1 ', A2' are arranged relative to each other in the wireless communication module MC1 so that their radiation patterns R are oriented differently relative to each other. Thus, in the same directions, they do not radiate the same powers.

Thus, as shown in Figure 9, in a non-limiting example, the radiation patterns R are oriented at 90 ° relative to each other. Thus, the two antennas A1 ', A2' are rotated relative to each other by 90 °. They have a different orientation. In other non-limiting examples not shown, the radiation patterns R are oriented at 45 °, or 180 ° relative to each other.

As can be seen, the point Q is now covered by one of the two radiation patterns R. Thus, a radiation pattern R with respect to the other radiation pattern R differently covers the radiation space ε and compensates for the defects of radiation from the other radiation pattern R. Thus, at point Q, the RSSIQ measurement is larger than with a single antenna. In a second nonlimiting embodiment, the two antennas A1 ', A2' have a different radiation pattern R.

A first radiation pattern R is illustrated in FIG. 7, and a second radiation pattern R 'is illustrated in FIG. 8.

The same explanations given for the first embodiment apply for the second embodiment with respect to the points K, Q and J.

As can be seen in FIG. 10, the point Q is now covered by one of the two radiation patterns R. Thus, a radiation pattern R with respect to the other radiation pattern R 'covers the radiation space differently. ε and compensates for the radiation defects of the other radiation pattern R '.

In a non-limiting embodiment not illustrated, the two radiation patterns R, R 'may also be oriented differently relative to each other. Thus, in the same way as for the first embodiment, the two antennas Α1 ', A2' are rotated relative to each other by 90 °. They have a different orientation. In other nonlimiting examples not shown, the radiation patterns R, R 'are oriented at 45 °, or 180 ° relative to each other. Thus, for this second embodiment, either the radiation patterns R, R 'are oriented in the same way, or they are oriented differently.

Thus, the two embodiments make it possible to have two radiation patterns of the two antennas Α1 ', A2' which are complementary to one another.

Thus, thanks to the use of two or more antennas, a diversity of antennas is introduced which makes it possible to improve the communication between the central electronic unit PE and the beacon BA and between the central electronic unit PE and the user terminal. MS. In particular, this improves the transmission or reception by the central electronic unit PE of:

- primary announcement frames ADV_C1;

secondary announcement frames ADV_C2;

DF data frames; - RSSI measures;

the POS position of the user terminal SP.

• Electricity

The secondary electronic unit BA is illustrated in FIGS. 1 to 6.

As illustrated in FIGS. 1 and 2, in a nonlimiting example, the communication device DISP comprises six tags BAi (i = 1 to 6). The six BA1 to BA6 beacons are distributed around the V vehicle.

In the non-limiting example of FIG. 1, the PosB positions of the BA beacons are:

- at the front right tire;

- at the front left tire;

- at the right doors;

- at the left doors;

- at the rear right tire;

- at the rear left tire.

BA tags are used for:

the location of a user terminal SP with respect to the motor vehicle by a RSSI (Received Signal Strength Indication) receiving power measurement method of received signals, a method well known to those skilled in the art. The received signals are frames of data sent by the user terminal SP to the central electronic unit PE.

A beacon BA is adapted to be paired with said central electronic unit PE and thus to the motor vehicle V (function illustrated in FIG 3 APP (BA (ID), PE (Adr1).) It will be noted that the pairing is a BLE pairing. and is generally done in the factory once and for all when installing the BA beacon on the motor vehicle.To this end, during the BLE pairing, there is an exchange of identifier ID and Adr1 address as well as encrypted information for securing the communication channel that will be used Thus, after the BLE pairing, the beacon BA includes in memory MEM2 the address Adr1 of said central electronic unit PE, and said electronic unit The central unit PE includes in memory MEM1 the identifier ID of the beacon BA.

Thus, the central electronic unit PE comprises the identifiers ID of each beacon BA1 to BA6 in the nonlimiting example illustrated.

BLE pairing being known to those skilled in the art, it is not described here. A BA tag is adapted to be:

in a connectable mode MODc with the central electronic unit PE.

It can establish a connection with the central electronic unit PE to exchange DF data frames on a secondary secure communication channel CH2.

It will be noted that the connectable mode MODc with said central electronic unit PE is parameterized in said beacon BA before its installation on the motor vehicle. For this purpose, said beacon BA includes in memory

MEM2 address Adr1 of said central electronic unit PE.

Furthermore, a BA beacon is adapted to be in the broadcast mode or in the scan mode. For this purpose, the beacon BA comprises a wireless communication module MC2. A wireless communication module MC2 thus comprises a BLE antenna in a non-limiting example that serves as a transmitter / receiver.

The beacon BA is adapted to broadcast an advertisement frame ADV within the CA announcement channels previously seen when it is powered, namely when it is powered up by the central electronic unit PE. A BA beacon broadcasts the same ADV announcement frame sequentially on the CA announcement channels. An ADV announcement frame is thus broadcast repeatedly at a regular time interval. In a non-limiting example, this time interval is substantially equal to 100 ms (milliseconds).

Thus, the beacon BA can be connectable mode MODc combined with the broadcast mode or the scan mode.

It is initialized in connectable mode MODc (with said central electronic unit PE) combined with the diffusion mode or the scanning mode according to the adopted connection strategy (master-slave). It should be noted that as long as a user terminal SP is around the motor vehicle V, the beacon BA remains energized, either in a mode which makes it possible to seek a connection with the electronic unit PE, or in a mode connected with the electronic unit PE. When it is connected with the electronic unit PE, it no longer broadcasts an announcement frame ADV.

An ADV ad frame includes:

an identifier ID such as in a nonlimiting example a MAC address ("Media Access Control" in English). This identifier ID is unique for each BA tag installed on a motor vehicle V;

- INF information that indicates:

that the beacon BA is connectable with the central electronic unit PE;

the power on the PUtx transmission of the ADV announcement frame.

For the connection with the central electronic unit PE, in a first nonlimiting embodiment, the beacon BA is thus adapted to broadcast said secondary announcement frame ADV_C2 (function illustrated in FIG. 3 BRD (BA, PE, ADV_C2 ( P2)) It subsequently receives a connection request CONNECT_REQ from the central electronic unit PE In this case only the central electronic unit PE is adapted to receive this secondary announcement frame ADV_C2.

the advertisement frame ADV thus comprises the address of the transmitting BA beacon and the address of the addressee which is the address Adr1 of the central electronic unit PE;

the announcement frame ADV indicates that the beacon BA is connectable to the central electronic unit PE, namely the beacon BA will accept only a connection coming solely from said central electronic unit PE and not from other devices;

For the connection with the central electronic unit PE, in a second nonlimiting embodiment, the beacon BA is adapted to:

receiving said secondary announcement frame ADV_C2 (function illustrated in FIG. 3 RX (BA, PE, ADV_C2 (P2)); - Connect to said central electronic unit PE (function shown in Figure 3 CONNCT (BA, PE, CH2)) so as to open the secondary communication channel CH2 with said central electronic unit PE. It therefore initiates the connection and thus broadcasts a connection request CONENCT_REQ for said central electronic unit PE on a CA announcement channel.

After its connection with said central electronic unit PE, the beacon BA is adapted to:

receiving the primary data parameters P1 previously described on said secondary secure communication channel CH2 so as to synchronize with said central electronic unit PE (function illustrated in FIG. 3 RX (BA, PE, P1, CH2));

according to said primary communication parameters P1, scanning the data channels CD of said primary secure communication channel CH1 used for said communication between said central electronic unit PE and said user terminal SP (function illustrated in FIG. 3 SCN (BA, CD , CH1));

intercepting data frames DF exchanged between said central electronic unit PE and said user terminal SP on said scanned CD data channel (function illustrated in FIG. 3 RECVR (BA, DF,

CD, CH1)).

The beacon BA is adapted to scan said CD data channels of said primary secure communication channel CH1 according to said scanning window W1. In a non-limiting embodiment, if said beacon BA has failed to synchronize with said central electronic unit PE, the scanning window W1 is enlarged Woff enlargement on both sides as shown in FIG. 5. This allows the beacon BA to have a better chance of synchronizing with said central electronic unit PE. The beacon BA failed to synchronize when it did not see a complete exchanged DF data frame from the user terminal SP or the electronic central unit PE. When the BA tag has intercepted a DF data frame, the BA tag is adapted to:

performing RSSI reception power measurements of said intercepted DF data frames (function illustrated in FIG. 3 MEAS (BA, DF, RSSI));

transmitting said RSSI reception power measurements to said central electronic unit PE (function illustrated in FIG. 3 TX (BA, PE, RSSI)).

Thus, what has been described for a BA beacon applies to the six beacons BA1 to BA6 of the nonlimiting example illustrated in FIG. The six BA beacons thus receive the same DF data frame sent by the user terminal SP at a given instant, and thus perform the RSSI reception power measurement on a single DF data frame. Thus, even if the user terminal SP moves, in particular when it rotates 180 ° and thus has a very different antenna gain, for example, RSSI power measurements are not obsolete. They reflect well the distance of the user terminal SP with respect to each beacon BA and thus its positioning POS relative to the motor vehicle V, unlike the prior art where each beacon BA sends at different times (all in less than 100ms classically) announcement frames and where the user terminal SP itself performs the power measurements in reception of said received announcement frames. Indeed, in this case, it is possible that the user terminal SP has made a sufficient rotation so that the first announcement frames and the last announcement frames sent from the different BA tags are viewed from a different angle and leads to RSSI reception power measurements that do not reflect this rotation and therefore leads to errors in the location of the user terminal SP with respect to the motor vehicle.

In a non-limiting embodiment, the beacon BA comprises at least two antennas. In a non-limiting embodiment, it comprises two antennas A1, A2. Thus, as illustrated in FIG. 7, the wireless communication module MC2 of the beacon BA comprises the two antennas A1, A2. Each antenna A1, A2 comprises a radiation pattern R. The radiation pattern R provides distance information for a given RSSI measurement at which the user terminal SP is located when it approaches the BA beacon and when at an angle to an antenna A1, or A2. Thus, the union of the radiation patterns R of the two antennas A1, A2 corresponds to a radio signature of the beacon BA.

It will be noted that for the sake of simplification, and for purely illustrative purposes, the same radiation patterns R, R 'have been taken for the antennas A1, A2 and the antennas A1, A2'. Of course, the antennas A1, A2 may have radiation patterns R, R 'different from those of the antennas A1' and A2 '. Likewise, the antennas A1, A2 of each BA beacon may have different radiation patterns from the antennas A1, A2 of the other beacons BA.

In a first nonlimiting embodiment, the two antennas A1, A2 have the same radiation pattern R. A non-limiting example of a radiation pattern R is illustrated in FIG. 7. If the user terminal SP is at the point K by For example, the beacon BA measures an RSSIK power and thus knows that the user terminal SP is at a distance d _K from the beacon BA. This distance d _K corresponds to -40dBm.

Inside the hatched surface, for example at the point J illustrated in FIG. 7, the measurement RSSIj will be stronger than the measurement RSSIK. Thus, if the user terminal SP is at point J, the beacon BA measures a stronger power RSSIj and the distance dj is less than the distance d _K.

Outside the hatched surface, for example at the point Q illustrated in FIG. 7, the power will be lower. Thus, if the user terminal SP is at point Q, the beacon BA measures a lower power RSSIQ and the distance do is greater than distance d.

According to this first nonlimiting embodiment, in addition to having the same radiation pattern R, the two antennas A1, A2 are arranged relative to each other in the wireless communication module MC2 so that that their radiation patterns R are oriented differently relative to each other. So, in the same directions, they may not radiate the same powers.

Thus, as shown in Figure 9, in a non-limiting example, the radiation patterns R are oriented at 90 ° relative to each other. Thus, the two antennas A1, A2 are rotated relative to each other by 90 °. They have a different orientation. In other non-limiting examples not shown, the radiation patterns R are oriented at 45 °, or 180 ° relative to each other.

As can be seen, the point Q is now covered by one of the two radiation patterns R. Thus, a radiation pattern R with respect to the other radiation pattern R differently covers the radiation space ε and compensates for the defects of radiation of the other radiation pattern R. Thus, if the user terminal SP is at point Q, the beacon BA measures a RSSIQ power greater than with a single antenna.

In a second non-limiting embodiment, the two antennas A1, A2 have a different radiation pattern R.

A first radiation pattern R is illustrated in FIG. 7, and a second radiation pattern R 'is illustrated in FIG. 8. The same explanations given for the first embodiment apply for the second embodiment as regards relates to the points K, Q and J.

As can be seen in Figure 10, point Q is now covered by one of two radiation patterns R. Thus, a graph of radiation R with respect to the other radiation pattern R 'differently covers the radiation space ε and compensates for the radiation defects of the other radiation pattern R'. Thus, if the user terminal is at point Q, the RSSIQ measurement will be larger than with a single antenna.

In a non-limiting embodiment not illustrated, the two radiation patterns R, R 'may also be oriented differently relative to each other. Thus, in the same way as for the first embodiment, the two antennas A1, A2 are rotated relative to each other by 90 °. They have a different orientation. In other nonlimiting examples not shown, the radiation patterns R, R 'are oriented at 45 °, or 180 ° relative to each other.

Thus, for this second embodiment, either the radiation patterns R, R 'are oriented in the same way, or they are oriented differently.

Thus, thanks to the use of two or more antennas, a diversity of antennas is introduced which makes it possible to improve the RSSI measurements by the BA tag and:

the reception or transmission by the beacon BA of the secondary announcement frames ADV_C2;

the reception by the beacon BA of the primary data parameters P1;

- the issuance by the BA tag of the RSSI measures. In a non-limiting embodiment, the beacon BA is configured to:

alternating the broadcasting of its secondary announcement frames ADV_C2 via one or other of the two antennas A1, A2; or

broadcasting its secondary announcement frames ADV_C2 via the two antennas A1, A2 at the same time. Similarly, in a non-limiting embodiment, the BA tag is configured to:

transmitting said RSSI power measurements via either of the two antennas A1, A2; or

transmitting said RSSI power measurements via the two antennas A1, A2 at the same time.

Thus, the number of information is duplicated with respect to the use of a single antenna in the wireless communication module MC2.

These two embodiments apply for all the BA beacons of the motor vehicle V, namely the six beacons BA1 to BA6 described above. Thus, depending on the position of the user terminal SP with respect to the motor vehicle V and therefore with respect to each of the six beacons BA, and as a function of the angle at which the user terminal SP is located with respect to each beacon BA, will have two RSSI measurement information and distance d relative to the two antennas A1, A2 of each BA tag. Each beacon BA thus has its own radio signature which is determined by the two radiation diagrams of its two antennas A1, A2. Thus, it is possible to precisely locate the user terminal SP and to know at which level of the motor vehicle it is located (right front, left front, right doors, left doors, rear right, left rear in the non-limiting example taken).

It should be noted that in order to know in operation what is the distance d corresponding to the RSSI measurement received from the announcement frames ADV transmitted by the two antennas A1, A2, the user terminal SP or the central electronic unit PE includes in memory the measurement information RSSI and distance d corresponding to each of the two antennas A1, A2 for each of the six given positions (right front, left front, right doors, left doors, right rear, left rear) in the non-limiting example taken. This information was initially collected during a calibration phase before putting into operation the user terminal SP. In In operation, the user terminal SP or the central electronic unit PE compares the RSSI measurement acquired by the beacon BA with those saved in memory to retrieve the corresponding distance d.

FIG. 6 illustrates a time diagram of a communication method carried out by the communication device DISP, namely between the central electronic unit PE and a beacon BA. Moreover, FIG. 6 also illustrates a communication between the central electronic unit PE and the user terminal SP.

In the nonlimiting embodiment illustrated:

the central electronic unit PE initiates the connection with the user terminal SP, that is, it sends a request in connection CONNECT_REQ;

the central electronic unit PE initiates the connection with the beacon BA;

for the localization application of the user terminal SP, the central electronic unit PE calculates itself the POS position of the user terminal SP with respect to the motor vehicle V;

the hop Hp1 is equal to 6 and the first data channel used CD for the exchange between the user terminal SP and the central electronic unit PE is the data channel 6.

The central electronic unit PE is in connectable mode MODc with the user terminal SP and the beacon BA. The beacon is in MODc connectable mode only with the central electronic unit PE.

The electronic unit PE is initialized in broadcast mode to receive ADV announcement frames.

Thus, in step 1), the user terminal SP broadcasts a primary announcement frame ADV_C1 to connect with the central electronic unit PE which receives it in step 2). The primary announcement frame ADV_C1 comprises the primary communication parameters P1 seen previously. The primary announcement frame ADV_C1 is broadcast on the announcement channels CA 37, 38 and 39.

In step 3), the central electronic unit PE connects to the terminal SP user to open a primary secure communication channel CH1 with him. For this purpose, it sends a CONNECT_REQ connection request to the user terminal SP which in response indicates whether it accepts the connection or not.

If so, the primary secure communication channel CH1 is open and the central electronic unit PE can thus receive DF data frames (step 5) sent by the user terminal SP (step 4) on the data channels CD of the CH1 primary secure communication channel, DF data frames that are intended for it, and vice versa. These DF data frames are not intended for the BA tag.

When the connection is established, the announcement channels CA 37, 38 and 39 are no longer used.

In step 6), the beacon BA broadcasts a secondary announcement frame ADV_C2 to connect with the central electronic unit PE which receives it in step 7. This secondary announcement frame ADV_C2 includes secondary communication parameters P2. The secondary announcement frame ADV_C2 is broadcast on the announcement channels CA 37, 38 and 39.

In step 8), the central electronic unit PE connects to the beacon BA so as to open a secondary secure communication channel CH2 with it. For this purpose, it sends a CONNECT_REQ connection request to the BA tag which in response indicates whether it accepts the connection or not. If so, the secondary secure communication channel CH2 is open and the central electronic unit PE can send DF data frames to the BA tag on the CD data channels of the secondary secure communication channel CH2 and vice versa. These DF data frames are not intended for the user terminal SP.

Of course, these three steps 6 to 8 are performed independently of steps 1 to 5, so can be performed before or during or after.

In step 9), the central electronic unit PE transmits the parameters of P1 primary communication to the BA beacon via a DF data frame on the CD data channels of the secondary secure communication channel CH2.

In step 10), the beacon BA receives these primary communication parameters P1 so that the beacon BA synchronizes with the central electronic unit PE. Thus, the BA beacon can listen to the exchanges between the central electronic unit PE and the user terminal SP. She is spying on the primary communication channel CH1. Synchronization is thus a continuous result of scanning CD data channels. At each reception of a DF data frame, the BA beacon synchronizes with the central electronic unit PE for the next reception.

In step 1 1), according to said primary communication parameters P1, the beacon BA scans the data channels CD of said primary secure communication channel CH1 used for said communication between said central electronic unit PE and said user terminal SP.

Thus, as can be seen in the nonlimiting example of FIG. 4, the beacon BA begins to scan the data channel CD6 then successively the data channels CD12, CD18, CD24, CD30, CD36 and continues with the data channel. data CD5, CD1 1 etc. Since the jump Hp1 is equal to 6, the data channel CD36 is changed to CD5 by skipping the data channels CD0 to CD4. It should be noted that the advertisement channels CA 37, 38 and 39 are not counted.

In step 12), the beacon BA intercepts the DF data frames exchanged between said central electronic unit PE and said user terminal SP on said scanned CD data channels.

In step 13), the beacon BA executes at least one function Fb dependent on the intercepted data frames DF.

In the nonlimiting application of the location of the POS position of the user terminal SP, in a non-limiting example, the function Fb executed is a RSSI reception power measurement of said DF data frames. In step 14), the beacon BA transmits said RSSI receive power measurements to the central electronic unit PE.

Thus, as can be seen in the nonlimiting example illustrated in FIG. 4, each BA beacon performs RSSI reception power measurement for each DF data frame it has intercepted on the different spy CD data channels. and returns said RSSI receive power measurements to the central electronic unit PE.

In step 15), the central electronic unit PE calculates the POS position of the user terminal SP with respect to the motor vehicle according to said RSSI reception power measurements.

For this purpose, the distance D0 at which the user terminal SP of the motor vehicle V is located can be determined for each beacon BA as a function of the RSSI reception power measurements. It is thus known how far D0 is the user terminal SP of the beacon BA1, how far D0 is from the beacon BA2 and how far D0 is from the beacon BA3 etc. This determination is made according to a calibration curve which indicates for a given distance value what is the power on the transmission PUtx and what is the power measurement in the corresponding RSSI reception. Such a curve being known to those skilled in the art, it is not described here.

The POS position of the user terminal SP with respect to the motor vehicle V is determined according to the determined distances D0 of each beacon BA. In a non-limiting embodiment, the POS position is determined according to a location method well known to those skilled in the art.

In step 1 6), the central electronic unit PE transmits its POS position to the user terminal SP which receives it in step 17.

Depending on the POS position of the user terminal SP and the requested function Fct, the latter is executed or not by the motor vehicle V. Thus, in non-limiting examples:

- if the user terminal SP is outside the motor vehicle V, start Fct function is not allowed.

if the user terminal SP is outside the motor vehicle V equipped with the automatic parking function, the start function Fct is authorized.

if the user terminal SP is inside the motor vehicle V, the function Fct for locking the external openings is not allowed;

if the user terminal SP is on the left side of the motor vehicle V, the opening function Fct of the right-hand door of the motor vehicle V is not authorized;

if the user terminal SP is in the safe, the start function Fct is allowed;

if the user terminal SP is at a distance of less than 2 meters from the motor vehicle V, as recommended by the Thatcham consortium, then the function Fct for unlocking the doors is authorized.

Of course, the description of the invention is not limited to the application, the embodiments and the examples described above.

Thus, in a non-limiting embodiment where the BA beacons are positioned in the tires, they can be used for a TPMS application called "Tire Pressure Monitoring System" which gives information on the pressure of the tire.

Thus, in another non-limiting embodiment, the function Fct executed is an automatic parking of the motor vehicle V. Thus, the described invention has the following advantages in particular:

- it is simple to implement;

- it makes it possible to use user terminals SP which do not have

necessarily the primary announcement frame broadcast function ADV_C1 or initialization of a connection with another device; it allows to use only one connection with the user terminal SP, namely that between him and said central electronic unit PE. Note that some user terminals are limited in number of connections and a connection is consuming bandwidth; it makes it possible to have no problem of collisions between announcement frames sent by different transmitters, since here only the user terminal SP sends frames of data DF which will be used for its location;

it makes it possible to take into account the reality of the physical positioning of the user terminal SP at a given instant. RSSI receive power measurements are not obsolete;

it allows a central electronic unit PE to allow several BA beacons to synchronize with it and thus listen to the data channels CD of the primary communication channel CH1.

Claims

1. A communication device (DISP) for a motor vehicle (V), wherein said communication device (DISP) comprises:

a central electronic unit (PE) adapted to:

- receive from a user terminal (SP) or broadcast for said user terminal (SP) a primary announcement frame (ADV_C1) to establish a connection with it, said primary announcement frame (ADV_C1) comprising primary communication parameters (P1);

- connect to said user terminal (SP) so as to open a primary secure communication channel (CH1) with him;

- exchanging data frames (DF) with said user terminal (SP) over data channels (CD) of said primary secure communication channel (CH1);

receiving at least one secondary electronic unit (BA) or broadcasting for said at least one secondary electronic unit (BA) a secondary announcement frame (ADV_C2) for establishing a connection with it;

connecting to said at least one secondary electronic unit (BA) so as to open a secondary secure communication channel (CH2) with it;

transmitting said primary communication parameters (P1) to said at least one secondary electronic unit

(BA) in said secondary secure communication channel (CH2);

said at least one secondary electronic unit (BA) adapted to:

receiving from said central electronic unit (PE) or broadcasting for said central electronic unit (PE) said frame secondary ad (ADV_C2);

- receiving from said central electronic unit (PE) said primary communication parameters (P1) in said secondary secure communication channel (CH2);

- according to said primary communication parameters (P1), scanning data channels (CD) used of said primary secure communication channel (CH1);

- Intercept data frames (DF) exchanged between said central electronic unit (PE) and said user terminal (SP) on said data channels (CD) and scanned.

The communication device (DISP) according to claim 1, wherein said at least one secondary electronic unit (BA) is a beacon.

A communication device (DISP) according to claim 1 or claim 2, wherein said at least one secondary electronic unit (BA) is further adapted for:

- performing reception power measurements (RSSI) of said intercepted data frames (DF);

transmitting said reception power measurements (RSSI) to said central electronic unit (PE).

A communication device (DISP) according to any one of the preceding claims 1 to 3, wherein said primary communication parameters (P1) comprise in particular:

a connection interval (11);

- a channel hop (Hp1) between a first data channel (CD) used and the next (CD);

- data channel mapping (MP1);

a scanning window (W1);

- master clock precision (SCA1).

The communication device (DISP) according to any one of the preceding claims 1 to 4, wherein said at least one secondary electronic unit (BA) is adapted to scan said data channels (CD) of said primary secure communication channel ( CH1) according to said scanning window (W1).

6. A communication device (DISP) according to claim 5, wherein said at least one secondary electronic unit (BA) failed to intercept a complete exchanged data frame (DF), the scanning window (W1 ) is enlarged.

The communication device (DISP) according to any one of the preceding claims 1 to 6, wherein said central electronic unit (PE) is further adapted to:

calculating the position (POS) of the user terminal (SP) relative to the motor vehicle as a function of said receiving power measurements (RSSI); or

transmitting said reception power measurements (RSSI) to said user terminal (SP) so that the latter can calculate its position (POS) with respect to said motor vehicle (V).

8. Communication device (DISP) according to any one of the preceding claims 1 to 7, wherein said central electronic unit (PE) and said at least one beacon (BA) are adapted to communicate with each other according to the Bluetooth communication protocol. Low Energy ™ (BLE).

9. Communication device (DISP) according to any one of the preceding claims 1 to 8, wherein said at least one secondary electronic unit (BA) comprises at least two antennas (A1, A2).

10. Communication device (DISP) according to any one of the preceding claims 1 to 9, wherein said central electronic unit (PE) comprises at least two antennas (A1 ', A2'). 1 1. A communication device (DISP) according to claim 9 or claim 10, wherein said at least two antennas (A1, A2, A1 ', A2') have the same radiation pattern (R).

12. A communication device (DISP) according to claim 9 or claim 10, wherein said at least two antennas (A1, A2, A1 ', A2') have a different radiation pattern (R).

13. Communication device (DISP) according to any one of the preceding claims 9 to 12, wherein said at least two antennas (A1, A2, Α1 ', A2') are arranged relative to one another. so that their radiation patterns (R) are oriented differently relative to each other.

The communication device (DISP) according to any one of the preceding claims 1 to 13, wherein said communication device (DISP) comprises a plurality of secondary electronic units (BA). 15. User terminal (SP) adapted to communicate with a central electronic unit (PE) of a communication device (DISP) for a motor vehicle (V), said user terminal (SP) being adapted to:

receiving from a central electronic unit (PE) or broadcasting for said central electronic unit (PE) a primary announcement frame (ADV_C1) for establishing a connection with it, said primary announcement frame (ADV_C1) comprising parameters of primary communication (P1); - connect to said central electronic unit (PE) so as to open a primary secure communication channel (CH1) with it;

sending data frames (DF) to said central electronic unit (PE) on data channels (CD) of said one primary secure communication channel (CH1).

The user terminal (SP) according to claim 15, wherein said user terminal (SP) is further adapted to:

receiving receive power measurements (RSSI) of said data frames (DF) from said central electronic unit (PE); and

calculating its position (POS) with respect to said motor vehicle (V) as a function of said receiving power measurements (RSSI); or

- Receive its position (POS) relative to said motor vehicle (V) of said central electronic unit (PE).

17. A communication system (SYS) for a motor vehicle (V) comprising a communication device (DISP) according to any one of the preceding claims 1 to 14 and a user terminal (SP) according to the preceding claim 15 or 16.