The present invention relates to a wireless portable device for a vehicle. Such a wireless portable device may be used, but not exclusively, in a motor vehicle.

BACKGROUND OF THE INVENTION

A wireless portable device for a vehicle, such as a Smartphone, well-known by the man skilled in the art, is used for a passive entry, passive start of said vehicle, known as PEPS function. In order to locate said wireless portable device around said vehicle for performing the PEPS related functions, received strength signal indication measurements, also called RSSI measurements, are used to range said wireless portable device around said vehicle. The RSSI measurements are performed by a Bluetooth Low Energy™ transceiver embedded in said wireless portable device.

A wireless portable device for a vehicle, such as a Smartphone, well-known by the man skilled in the art, is also used for remote parking function for said vehicle. In order to comply with safety regulations, said wireless portable device is to be ranged within the regulatory range of said vehicle. The remote parking function uses RSSI measurements performed by a Bluetooth Low Energy™ transceiver or a network of Bluetooth Low Energy™ embedded in said wireless portable device to determine the location of said wireless portable device in the vicinity of said vehicle.

Inherently to the frequency range used by the Bluetooth™ communication system, the RSSI measurement may lack accuracy, causing the PEPS system to perform erratically or the remote parking function to operate in infringement of applicable regulations.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a wireless portable device for a vehicle, which resolves the problem above-stated. To this end, there is provided a wireless portable device for a vehicle, said wireless portable device comprising a received strength signal indication measurement circuit for locating said wireless portable device relative to said vehicle, wherein said received strength signal indication measurement circuit is a wireless charging receiver circuit of said wireless portable device which:

- is configured to be put in a wireless charging mode in which it wirelessly charges a battery of said wireless portable device,

- comprises at least two low frequency antennas aligned along two axis X and Y and which are configured to receive a plurality of low frequency signals from said vehicle,

- is furthermore configured to be put in a ranging mode in which it performs received strength signal indication measurements upon said received low frequency signals when said wireless charging mode is deactivated, said received strength signal indication measurements being used for short range location.

As we will see in further details, the use of the wireless charging receiver embedded in the wireless portable device, to perform a function other than the charge of said wireless portable device, namely the RSSI measurements needed for the PEPS functions or the remote parking function, allows more accurate RSSI measurements, thanks to the low frequency signals usually used by said wireless charging receiver.

According to non-limitative embodiments of the invention, the wireless portable device for a vehicle in accordance with the invention further comprises the following characteristics. In a non-limitative embodiment, said wireless portable device is further configured to transmit said received strength signal indication measurements to said vehicle via the Bluetooth Low Energy™ communication protocol.

In a non-limitative embodiment, said wireless portable device is further configured to process said received strength signal indication measurements (RSSI) and transmit full or partial results of that processing to the vehicle via the Bluetooth Low Energy™ communication protocol. In a non-limitative embodiment, said wireless charging receiver circuit further comprises a main antenna which is configured to receive a plurality of low frequency signals from said vehicle along a Z axis orthogonal to said X and Y axis, said wireless charging receiver circuit being furthermore configured to perform received strength signal indication measurements upon said received low frequency signals when said wireless charging mode is deactivated.

In a non-limitative embodiment, said wireless portable device further comprises a gyroscope configured to define the orientation of said wireless portable device along the Z axis, said orientation. In a non-limitative embodiment, said wireless portable device is further configured to receive or compute at least one parameter based on signals transmitted by at least one transceiver, said at least one parameter being used for short range locating.

In a non-limitative embodiment, said at least one parameter is: - an angle of arrival,

- a time of flight,

- an angle of departure.

In a non-limitative embodiment, said signals are transmitted via the Bluetooth Low Energy™ communication protocol. In a non-limitative embodiment, said at least one transceiver is a centralized transceiver or a beacon.

In a non-limitative embodiment, said wireless charging receiver circuit is further configured to receive a plurality of low frequency signals from at least one low frequency antenna of said vehicle, said plurality of low frequency signals being used for short range locating by performing a triangulation.

In a non-limitative embodiment, said wireless portable device is a passive entry passive start identification device.

In a non-limitative embodiment, said wireless portable device is a remote control device. In a non-limitative embodiment, said remote control device is configured to perform a park assist function. In a non-limitative embodiment, said wireless portable device is a Smartphone.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of methods and/or apparatus in accordance with embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings, in which:

- Figure 1 is a schematic diagram of a wireless portable device for a vehicle and said vehicle, said wireless portable device comprising a wireless charging receiver circuit, according to a non-limitative embodiment of the invention, - Figure 2 is a schematic diagram of said wireless portable device of figure 1 , said wireless charging receiver circuit comprises at least two low frequency antennas, according to a non-limitative embodiment of the invention,

- Figure 3 is a schematic diagram of said wireless portable device of figure 1 , the wireless charging receiver circuit further comprising a main antenna, according to a non-limitative embodiment,

- Figure 4 depicts an angle of arrival which is computed by the vehicle of figure 1 based on a signal received by a transceiver of said vehicle, said signal corresponding to a signal emitted by a transceiver of said wireless portable device, according to a non-limitative embodiment, - Figure 5 depicts an angle of departure which is computed by the wireless portable device based on a signal received by the charging receiver of said wireless portable device, said signal corresponding to a signal emitted by a transceiver of said vehicle of figure 1 , according to a non-limitative embodiment, - Figure 6 depicts a time of flight which is computed by the vehicle of figure 1 based on a signal emitted by a transceiver of said vehicle, and on a signal returned by said wireless portable device upon receiving said emitted signal, according to a non-limitative embodiment.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION In the following description, well-known functions or constructions by the man skilled in the art are not described in detail since they would obscure the invention in unnecessary detail.

The present invention relates to a wireless portable device 1 for a vehicle 2 illustrated in figure 1 and 2, according to non-limitative embodiments. In a non- limitative embodiment, said vehicle 2 is an automobile vehicle. In non-limitative examples, said automobile vehicle is a motor vehicle, or an electrical vehicle or a hybrid vehicle. Said vehicle 2 comprises:

- at least one low frequency transceiver 21 , also called LF transceiver 21 , - at least one low frequency antenna 22, also called LF antenna 22,

- at least one Bluetooth Low Energy™ transceiver 23, also called BLE transceiver 23,

- a central processing unit 24.

In a non-limitative embodiment, the vehicle 2 further comprises a wireless base station 20 for the wireless portable device 1 , said wireless base station 20 comprising a charging area.

In a non-limitative embodiment, the vehicle 2 further comprises five low frequency transceivers 21. The number of low frequency antennas 22 and their locations may vary from vehicle model to vehicle model. This set of antenna allows a coverage of vehicle vicinity within an approximate 10 meters range.

In non-limitative embodiments, said at least one BLE transceiver 23 is a centralized transceiver or a beacon. In a non-limitative variant of embodiment, the vehicle 2 comprises a plurality of beacons arranged all around said vehicle 2. In a non-limitative example (not illustrated), the vehicle 2 comprises six beacons, one arranged at the rear left, one at the rear right, one at the front left, one at the front right, and one on each side between the doors of the vehicle 2. Hence, the vehicle 2 is configured to communicate via a wireless communication protocol with the wireless portable device 1. In a first non-limitative embodiment, the wireless portable device 1 is a passive- entry passive-start identification device. Hence, the wireless portable device 1 is configured to perform a passive-entry passive-start function called PEPS function. In a second non-limitative embodiment, the wireless portable device 1 is a remote control device. In a non-limitative embodiment, said remote control device is configured to perform a park assist function. In a non-limitative variant of said first and said second embodiments, the wireless portable device 1 is a Smartphone. Hence, said Smartphone is configured to perform a PEPS function, and/or a park assist function. The wireless portable device 1 is illustrated in figure 1. It comprises:

- a received strength signal indication measurement circuit 10 for locating said wireless portable device 1 relative to said vehicle 2,

- a wireless charging receiver circuit 11 , said received strength signal indication measurement circuit 10 being within said wireless charging receiver circuit 11 ,

- a battery 12,

- a BLE transceiver 13.

As illustrated in figure 2, said wireless charging receiver circuit 11 comprises a central processing unit 110 and at least two low frequency antennas 11 x, 11 y (also called LF antennas 11 x, 11 y) aligned along two axis X and Y and which are configured to receive a plurality of low frequency signals 2x, 2y from said vehicle 2, in particular from said LF transceiver 21. The low frequency signals are also called LF signals. In a non-limitative embodiment, the LF signals are received on a LF band frequency between 120kHz and 130kHz. In a non- limitative embodiment, the LF antennas 11 x, 11 y comprises a coil.

As illustrated in Figure 3, the wireless charging receiver circuit 11 further comprises a main antenna 11 z (also called LF antenna 11 z) align along a Z axis, and which is configured to receive a plurality of low frequency signals 2z from said vehicle 2 along the Z axis orthogonal to said X and Y axis. The plurality of low frequency signals 2z correspond to a plurality of signals 21a sent by the LF transceiver 21 of the vehicle 2. In a non-limitative embodiment, the LF antenna 11 z comprises a coil.

The wireless charging receiver circuit 11 is configured to be put in a wireless charging mode M1 , and in ranging mode M2. In the wireless charging mode M1 , when set on the wireless charging base station 20, the wireless charging receiver circuit 11 is configured to wirelessly charges the battery 12 (function illustrated f 1 (11 , M1, 12)). The central processing unit 110 recovers the energy of the LF signal received by the low frequency antenna 11 z and uses it to charge the battery 12. The low frequency antennas 11 x and 11y are used by the central processing unit 110 to evaluate the relative alignment of the antenna 11z to the LF transceiver 21 of the vehicle 2 located in the wireless charging base station 20 and, if required, to notify the wireless portable device 1 to realign on the wireless charging base station 20. If the wireless portable device 1 is not correctly aligned on the charging area the energy transfer efficiency is decreased potentially significantly. In a non- limitative embodiment, the energy of the LF transceiver signals 21a may comply with the Qi standard, well-known by the man skilled in the art, created by the Wireless Power Consortium to manage wireless energy transfers.

In the ranging mode M2, the charging receiver circuit 11 is configured to: - receive the plurality of low frequency signals 2x, 2y via its at least two low frequency antennas 11 x, 11 y (function illustrated f2(11 , M2, 11x(2x),

Hy(2y))),

- perform received strength signal indication measurements, also called RSSI measurements, upon said received low frequency signals 2x, 2y (function illustrated f3(11 , M2, RSSI(2x), RSSI(2y)).

In the ranging mode M2, the charging receiver circuit 11 is further configured to receive the plurality of low frequency signals 2z via its low frequency antenna 11 z (function illustrated in figure 3 f5(11 , M2, 11z(2z))). It is to be noted that when measuring in X-Y only, the 11 x-11 y plane needs to be located in space for correct conversion of RSSI measurements into a distance. In a non-limitative embodiment, it is performed with the main antenna 11 z. It defines the orientation D1 of said wireless portable device 1 along the Z axis. The 11 x-11 y plane is defined by the orientation of the coils within the LF antennas 11x, 11 y. The 11 x-11 y plane is the plane of the wireless portable device 1 which is parallel to its thickness. Hence, the main antenna 11 z is configured to define the orientation of the wireless portable device 1 along the Z axis.

In a non-limitative embodiment, the wireless portable device 1 further comprises a gyroscope 14 illustrated in figures 2 and 3. It is to be noted that when measuring in X-Y only, the 11 x-11 y plane needs to be located in space for correct conversion of RSSI measurements into a distance. Hence, the gyroscope 14 is configured to define the orientation D1 of said wireless portable device 1 along the Z axis (function f8(1 , D1)). In a non-limitative embodiment, the gyroscope 14 is replaced by a 3D accelerometer.

Hence, one way or another, three dimensional data from three LF signals 2x, 2y, 2z are required, using the LF antennas 11 x and 11 y and 11 z, or using the

LF antennas 11 x and 11y and the gyroscope 14 or 3D accelerometer.

In the ranging mode M2, the at least one transceiver 21 of the vehicle 2 is configured to emit LF signals 21b in a polling or trigger mode to perform the PEPS functions or park assist function. Said signals 21b are received by the two LF antennas 11 x, 11 y. It is to be reminded that the LF signal 21b is a challenge frame aimed to the vehicle identifier of the traditional PEPS system. The vehicle identifiers which understand the challenge will respond to vehicle with an authentication frame. The central processing unit 110 is unable to decode the signal using the antenna 11 x and 11 y but it can measure its RSSI. It is to be noted that the antenna 11 z may be sensitive enough to decode the challenge.

The wireless charging mode M1 and the ranging mode M2 are exclusive. The wireless charging mode M1 is activated when the ranging mode M2 is deactivated, and the ranging mode M2 is re-activated when the charging mode M1 is deactivated. Therefore, the charging receiver circuit 11 is configured to perform RSSI measurements when the charging mode M1 is deactivated. The RSSI measurements are used for short range location of said wireless portable device 1. Hence, the LF antennas 11 x and 11 y are designed to do RSSI measurements in mode M1 and M2. In the charging mode M1, it is used to refine the energy transmitting coil 21 location. In the ranging mode M2, it is to locate the wireless portable device relative to the vehicle. By short range location, one means a location within a distance inferior to 3 meters from said vehicle 2. It is to be noted that this short range location is compatible with the Thatcham regulations well-known by the man skilled in the art. In a non-limitative embodiment, the charging mode M1 is activated when the wireless portable device 1 is arranged on said wireless base station 20 of said vehicle 2. In a non-limitative embodiment, when the wireless portable device 1 is arranged on said wireless base station 20, the wireless base station 20 emits a ping message 20a (illustrated in figures 1 and 2) to the central processing unit 110 of the charging receiver circuit 11 , which therefore triggers the charging mode M1 for charging the battery 12. In a non-limitative embodiment, the charging mode M1 may never be activated when the vehicle 2 is not equipped with a wireless base station 20. Therefore, the wireless portable device 1 may only be used with the ranging mode M2. In a non-limitative embodiment, the ranging mode M2 is activated when a short range location is needed, in other words when a PEPS function or a park assist function is to be executed in a non-limitative example. In a non-limitative embodiment, the ranging mode M2 is activated when there is a Bluetooth Low Energy™ pairing between the wireless portable device 1 and the vehicle 2, that is to say there is a BLE connection between the wireless portable device 1 and the vehicle 2. It is to be noted that the BLE pairing may occur when the wireless portable device 1 is between twenty meters to one hundred and fifty meters from the vehicle 2. As a BLE connection is well-known by the man skilled in the art, it is not described here. In a non-limitative embodiment, in the ranging mode M2, the wireless portable device 1 is further configured to:

- transmit said RSSI measurements to said vehicle 2 via the BLE communication protocol (function f4(1 , M2, 2, RSSI)), or - process said RSSI measurements and transmit full or partial results r1 of that processing to the vehicle 2 via the BLE communication protocol (function f4’(1 , M2, 2, (RSSI))).

The process is the conversion of the RSSI measurements into a distance to the target, which is the vehicle 2, or to a relative location coordinates relative to the vehicle. The vehicle LF transceivers 21 are emitting LF signals with a known power from a known location. Natural signal propagation attenuation will then give the distance, either through 11 x-11 y-11 z or 11 x-11y-gyroscope or 3D accelerometers. This computation being well-known by the man skilled in the art, it is not described in details here. This computation can be performed in the wireless portable device 1 , partially in the wireless portable device 1 or in the vehicle 2. The RSSI measurements or the results r1 of the processing on said RSSI measurements are transmitted by the wireless portable device 1 by means of its BLE transceiver 13, and are received by the vehicle 2 by means of its at least one BLE transceiver 23. The latest transmits these data to the central processing unit 24 of the vehicle 2, which performs the PEPS function or the park assist function according to the received data.

The wireless charging receiver circuit 11 is furthermore configured to perform RSSI measurements upon said received low frequency signals 2z when said wireless charging mode M1 is deactivated (function illustrated f6(11 , M2, RSSI(2z)).

In a non-limitative embodiment, in the ranging mode M2, the wireless portable device 1 is further configured to :

- transmit said RSSI measurements to said vehicle 2 via the BLE communication protocol (function f7(1 , M2, 2, RSSI)), or - process said RSSI measurements and to transmit full or partial results of that processing to the vehicle 2 via the BLE communication protocol (function f7’(1 , M2, 2, RSSI)).

It is to be noted that, as the different RSSI measurements are base on low frequency signals 2x, 2y and optionally 2z, there are more precise than RSSI measurements based on BLE signals. The precision is about ten centimeters, whereas the precision of the RSSI measurements based on BLE signals is about fifty centimeters to one meter.

In a first non-limitative embodiment, the RSSI measurements, based on the LF signals 2x, 2y and 2z when there is the main antenna 2z, are used to perform short range location of the wireless portable device 1 relative to the vehicle 2, either by computing a distance d1 , or coordinates based on said RSSI measurements. This short range location is also called primary short range location in the following. Such computations based on RSSI measurements are well-known by the man skilled in the art. Therefore, they are not described here. In a second non-limitative embodiment, the RSSI measurements based on the LF signals 2x, 2y and 2z are used to correct short range location performed with the different following non-limitative embodiments. These short range locations are also called secondary short range locations in the following. It is to be noted that the different following non-limitative embodiments can be combined together (two altogether or the three altogether).

In a first non-limitative embodiment, the wireless portable device 1 is further configured to receive some BLE signals from the BLE transceiver 23 of the vehicle 2. Upon said BLE signals, the wireless charging receiver circuit 11 is further configured to compute some RSSI measurements. From the RSSI measurements, a distance d2 is computed, which permits to acknowledge the presence of the wireless portable device 1 inside or outside the vehicle 2 (function f11 (1 , 23, d2)). As there is an environment uncertainty associated to the BLE measurements, in particular because of the BLE signals bouncing phenomenon, the RSSI measurements based on the LF signals 2x, 2y and 2z are used as refinement for the distance d2 of the wireless portable device 1 to the vehicle 2.

In a second non-limitative embodiment, the wireless portable device 1 is further configured to receive a plurality of low frequency signals 22a from said at least one low frequency antenna 22 of said vehicle 2, said plurality of low frequency signals 22a being used for short range locating. In a non-limitative example, the five LF antennas 22 of the vehicle 2 are used. A triangulation is performed based on the LF signals 22a of said five LF antennas 22. The result is a distance d2 which permits to acknowledge the presence of the wireless portable device 1 inside or outside the vehicle 2 (function f9(1 , 22a, d2)). The set of LF antennas 22 is sequentially emitting. That allows the triangulation. This distance d2 is refined with the RSSI measurements based on the LF signals 2x, 2y and 2z.

In a third non-limitative embodiment, the wireless portable device 1 is further configured to receive at least one parameter P21 or compute at least one parameter P21 based on signals 21c transmitted by the at least one BLE transceiver 23 arranged in said vehicle 2, or by the BLE transceiver 13 arranged in said wireless portable device 1 , said at least one parameter P21 being used for correcting said received strength signal indication measurements RSSI (function f 10(1 , P21 (AOA, TOF, AOD), 21c)). A distance d2 is computed based on this parameter P21. The RSSI measurements based on the LF signals 2x, 2y and 2z are used as refinement for the distance d2 of the wireless portable device 1 to the vehicle 2. In a non-limitative embodiment, said signals 21c are transmitted via the Bluetooth Low Energy™ communication protocol. Hence, the BLE transceiver 13 of the wireless portable device 1 is configured to receive said signals 21c emitted by the BLE transceiver 23 of said vehicle 2. In non- limitative embodiments, said at least one parameter P21 is :

- an angle of arrival AOA,

- a time of flight TOF, or - an angle of departure AOD. These three non-limitative embodiments are described hereinafter.

In a first non-limitative embodiment, the parameter P21 is an angle of arrival AOA. It is to be noted that an angle of arrival AOA is more accurate than a RSSI measurement. Said first non-limitative variant of said embodiment is described hereinafter in reference to figure 4.

In a first non-limitative variant of said embodiment, the vehicle 2 is configured to compute said angle of arrival AOA. To compute said angle of arrival AOA, one uses at least one planar antenna 230 of said BLE transceiver 23. As illustrated in figure 4, in a non-limitative embodiment, the dipoles 2300 of a planar antenna 230 are arranged in line at a constant distance d from each other, along an axis

Ax passing through the base of said dipoles 2300, and each at a respective distance d’ from the wireless portable device 1. Therefore, they will each receive a signal 21c’ corresponding to the signal 21c emitted by the wireless portable device 1 , in more particular by its BLE transceiver 13. It is to be noted that the phase difference F is constant if the dipole 2300 are arranged along a line at a constant distant d from each other.

Typically, the received signal 21c’ of a dipole 2300 will be a delayed version of the signal of another dipole 2300. The arrival angle AOA (referenced Q1 in figure 4) is calculated on a dipole 2300 according to the formula next: AOA = arcsin (lF) / (2pd) with l the wavelength of the frequency used in the BLE protocol. The angle of arrival AOA computation being well-known by the man skilled in the art it is not described in more detail here. It should be noted that the same principle also applies if a planar antenna 230 comprises more than two dipoles 2300 and if the BLE transceiver 23 comprise two planar antennas 230 or more.

It is to be noted that the angle of arrival AOA being different according to the location (right front, left front, right rear, left rear etc.) of the wireless portable device 1 with respect to the vehicle 2, the BLE transceiver 23 can thus determine if said wireless portable device 1 is close to it or not. According to its own position and the angle of arrival AOA, the BLE transceiver 23 can thus determine if it is close to it. In a non-limiting embodiment, the BLE transceiver 23 transmits the computed angle of arrival AOA to the central processing unit 24. The latter is configured to determine the parameter P21 based on said angle of arrival AOA, and subsequently to send said parameter P21 to said wireless portable device 1. In a non-limiting embodiment, the BLE transceiver 13 may emit a plurality of signal 21c at different intervals. Thus, a plurality of angles of arrival AOA is obtained. This allows confirmation of the value of the angle of arrival AOA.

In a second non-limitative variant of said first embodiment, the wireless portable device 1 is configured to compute said angle of arrival AOA. The same description held for the first non-limitative variant of embodiment applied for this second non-limitative variant of embodiment by swapping the BLE transceiver 13 of the wireless portable device 1 and the BLE transceiver 23. In this second non-limitative variant, the signals 21c are transmitted by the BLE transceiver 23 of said vehicle 2.

In a second non-limitative embodiment, the parameter P21 is a time of flight TOF. Said second non-limitative variant of said embodiment is described hereinafter in reference to figure 5. In a non-limitative embodiment, the BLE transceiver 23 is configured to compute said time of flight TOF. For the flight time TOF, the computation of the parameter P21 is relative to the received signal 21c ' corresponding to the signal 21c transmitted by the wireless portable device 1 , in more particular by its BLE transceiver 13, said signal 21c transmitted which is a feedback signal in response to the signal 21c” emitted by the BLE transceiver 23. As illustrated in figure 5, the computation of the time of flight TOF by the BLE transceiver 23 is thus a measure of the time between:

- the emission by the BLE transceiver 23 of the signal 21c”and the reception by the wireless portable device 1 of the signal (not illustrated) corresponding to said emitted signal 21c”, and

- the emission by the wireless portable device 1 of the signal 21c, called feedback signal, in response to the emitted signal 21c”, and the reception by the BLE transceiver 23 of the received signal 21c’ corresponding to the signal 21 c emitted by the wireless portable device 1.

Said parameter P21 is thus relative to said received signal 21c ' and also to said signal 21 c which is in this case a feedback signal. The computation of the time of flight TOF being well-known by the man skilled in the art, it is not described in more detail. Thus, when said parameter P21 is a time of flight TOF, it is possible to determine whether the wireless portable device 1 is located on the rear, front or middle side, and on the left or right side of the vehicle 2 and consequently in proximity to the BLE transceiver 23. In fact, according to the position of BLE transceiver 23, the feedback signal 21 c emitted by said wireless portable device 1 takes more or less time to arrive to the BLE transceiver 23. The time of flight TOF is thus more or less high.

The closer the wireless portable device 1 to a BLE transceiver 23 is, the lower the time of flight TOF will be. The farthest the identifier 1 is, the longer the time of flight TOF will be. In a non-limitative embodiment, the BLE transceiver 23 transmits the computed time of flight TOF to the central processing unit 24. The latter is configured to determine the parameter P21 based on said time of flight TOF, and subsequently to send said parameter P21 to said wireless portable device 1. In a third non-limitative embodiment, the parameter P21 is an angle of departure AOD. Said third non-limitative variant of said embodiment is described hereinafter in reference to figure 6. In a non-limitative embodiment, the wireless portable device 1 is configured to compute said angle of departure AOD. To compute an angle of departure AOD, the planar antenna or planar antennas 230 of said BLE transceiver 23 are used. The dipoles 2300 of a planar antenna 230 are configured to transmit composite signals otherwise called pure constant carriers which form the signal 21c”. As illustrated in figure 6, in a non-limitative embodiment, the dipoles 2300 of a planar antenna 230 are arranged in line at a constant distance d from each other along an axis Ax passing through the base of said dipoles 2300. The angle of departure AOD referenced Q2 in figure 6 relating to the signal 21c" is determined relative to the normal of said axis Ax. Considering that the distance between the wireless portable device 1 and the BLE transceiver 23 is greater than d, there is a difference of d ^* sin02 between the length of the path of a dipole 2300 to the antenna of the BLE transceiver 13 of the wireless portable device 1 , and that of another adjacent dipole 2300 to the antenna of the BLE transceiver 13 of the wireless portable device 1. There is therefore a phase difference F between the two composite signals received by the antenna of the BLE transceiver 13 of the wireless portable device 1 , respectively corresponding to the two composite signals emitted by the dipoles 2300. A measurement of this phase difference F is carried out by the wireless portable device 1. Based on this measurement and the distance d, the angle of departure AOD between the two composite signals of the two dipoles 2300 is computed. Since the angle of departure AOD computation is well-known by the man skilled in the art, it is not described in detail here. It should be noted that the same principle also applies if a planar antenna 230 comprises more than two dipoles 2300 and if the BLE transceiver 23 comprise two planar antennas 230 or more.

It is to be noted that the angle of departure AOD being different according to the location (right front, left front, right rear, left rear etc.) of the wireless portable device 1 with respect to the vehicle 2, the BLE transceiver 23 can thus determine if said wireless portable device 1 is close to it or not. According to its own position and the angle of departure AOD, the BLE transceiver 23 can thus determine if it is close to it. In a non-limiting embodiment, the BLE transceiver 23 transmits the computed angle of departure AOD to the central processing unit 24. The latter is configured to determine the parameter P21 based on said angle of departure AOD, and subsequently to send said parameter P21 to said wireless portable device 1.

Hence, when a secondary short range location is performed using one or a combination of the three non-limitative embodiments above-described, in order to correct this secondary short range location with the primary short range location based on the RSSI measurements of the LF signals 2x, 2y and 2z, one performs the following in a non-limitative embodiment.

If the distance d2 from the secondary short range location is below a determined distance d3, and the distance d1 from the primary short range location matches the distance d2, the distance d1 is taken as the distance of the wireless portable device 1 to the vehicle 2.

If the distance d2 is below the determined distance d3, but doesn’t match the distance d1 from the primary short range location, the distance d1 is taken as the distance of the wireless portable device 1 to the vehicle 2. In a non-limitative embodiment, the primary distance d3 is inferior to three meters. This d3 range is primarily aimed at increasing the portable device accuracy at close range to the vehicle for the passive entry function. In some systems, in a non-limitative embodiment, this distance d3 might be increased to 6~10meters for the remote parking function. If the distance d2 is greater than the primary distance d3, no RSSI measurements based on the LF signals 2x, 2y and 2z is performed. The distance d2 is assumed to be the distance of the wireless portable device 1 to the vehicle 2. At this range, it is used for a welcoming function that doesn’t require any sharp accuracy. It is to be reminded that the accuracy of the distance d2 is about fifty centimeters to one meter (when using the BLE transceivers), whereas the accuracy of the distance d1 is about 10 centimeters. Flence, by distances matching, one means the same distance within fifty centimeters to one meter. Flence, one obtains a primary short range location of the wireless portable device 1 which is accurate.

It is to be understood that the present invention is not limited to the aforementioned embodiments and variations and modifications may be made without departing from the scope of the invention. In the respect, the following remarks are made. It is to be understood that the present invention is not limited to the aforementioned embodiments.

Hence, some embodiments of the invention may comprise one or a plurality of the following advantages: - It reuses existing hardware, here the wireless charging receiver circuit, that is generally available in nowadays wireless portable device, for another function than the charging, here the PEPS function or the park assist function in non-limitative examples,

- it avoids implementing a costly dedicated embedded low frequency receiver or a costly embedded ultra wide band frequency receiver for the PEPS function or the park assist function in a wireless portable device. Therefore, no additional cost is required,

- it allows accurate distance measurements for the PEPS function or the park assist function.