Active management of the radiation pattern depending on the orientation

Abstract

Equipment (1) comprising: - a radiofrequency device (2) arranged to generate a radiated power which, when the equipment is installed with a nominal orientation, is less than a first threshold in the direction of a first zone and is less than a second threshold in the direction of a second zone, the second threshold being less than the first threshold; - a processing unit (4) arranged to, if the current orientation differs from the nominal orientation and is such that the power radiated in the direction of the second zone is likely to exceed the second threshold, control the device (2) to limit the power radiated in the direction of the second zone and thus ensure that the power radiated in the direction of the second zone becomes lower than the second threshold. FIGURE OF THE ABSTRACT: Fig.2

Description

Title of the invention: Active management of the radiation pattern as a function of orientation

[0001] The invention relates to the field of equipment comprising a radiofrequency device, such as access points for example.

[0002] BACKGROUND

[0003] Certain standards or regulations require equipment, which incorporates a radiofrequency device for transmitting radiofrequency signals, to emit radiated power which is lower than a first predefined power threshold in the direction of a first reference zone and which is lower than a second predefined power threshold in the direction of a second reference zone, the second predefined power threshold being lower than the first predefined power threshold.

[0004] The second reference zone is for example a vertical cone having the equipment as its apex, and the first reference zone is for example all the space around the equipment with the exception of said cone.

[0005] Thus, for example, the American Wi-Fi AFC (for Automatic Frequency Contro!) regulation requires an access point located in certain strategic geographical locations to strongly limit the power transmitted above a certain elevation angle so as not to harm telecommunications links based on protocols sharing certain specific frequency bands (Fcc 47 CFR 15.407(n)). Similarly, the Canadian Industry Canada regulation also imposes certain limitations depending on the elevation through RSS-247.

[0006] [Fig.l] illustrates an example corresponding to a 30 degree elevation limitation imposed on certain equipment in the United States in the 6 GHz band. The Equivalent Isotropic Radiated Power ("EIRP") is limited to 21 dBm above an elevation angle of 30 degrees relative to the horizon, while it is limited to 36 dBm below 30 degrees (the radiated power can therefore be 15 dB higher below the elevation angle of 30 degrees).

[0007] Manufacturers therefore design radiofrequency devices that generate limited radiated power above a certain elevation angle. This limitation can be achieved in different ways, for example: - by limiting the power transmitted by the amplifier of the radiofrequency device. This limitation is however obtained at the expense of overall coverage; - by physically distorting the radiation pattern in one direction; - using horizontal directional antennas.

[0008] However, these different methods are effective only when the equipment 0 is in its nominal position. An incorrect position of the equipment 0 results in incorrect orientation of the “deformation” and therefore regulatory non-compliance and poor coverage.

[0009] Indeed, if equipment 0 in [Fig.l] is not laid flat, its emission zone within 30 degrees with a PIRE limit of 36 dBm may overflow into the zone limited to a PIRE of 21 dBm. Equipment 0 then no longer complies with the regulations and its coverage is degraded.

[0010] OBJECT

[0011] The object of the invention is to ensure that equipment comprising a radiofrequency device remains compatible, whatever its orientation, with power limitation requirements which differ according to the directions.

[0012] SUMMARY

[0013] With a view to achieving this goal, equipment is proposed comprising:

[0014] - a radiofrequency device arranged to transmit radiofrequency signals by generating radiated power which, when the equipment is installed with a nominal orientation, is less than a first predefined power threshold towards a first reference area and is less than a second predefined power threshold towards a second reference area, the second predefined power threshold being less than the first predefined power threshold;

[0015] - a measuring device arranged to measure at least one representative quantity of a current orientation of the equipment;

[0016] - a processing unit arranged for, if the current orientation of the equipment differs from the nominal orientation and is such that the power radiated towards the second reference zone is likely to exceed the second predefined power threshold, control the radiofrequency device to limit the power radiated towards the second reference zone and thus ensure that the power radiated towards the second reference zone becomes lower than the second predefined power threshold.

[0017] The processing unit therefore acquires the measurements of the quantity or quantities representative of the current orientation of the equipment. If the current orientation is such that the power radiated in the direction of the second reference zone (a vertical cone for example) risks exceeding the second predefined power threshold due to the inclination of the equipment, the processing unit limits the power radiated in the direction of this second reference zone. This ensures that the equipment remains compliant with the regulations relating to transmission powers which differ according to the directions, regardless of the current orientation. of the equipment.

[0018] We further propose equipment as previously described, in which, to limit the power radiated in the direction of the second reference zone, the processing unit is arranged to limit an electrical power of at least one electrical signal applied between terminals of at least one antenna of the radiofrequency device.

[0019] We further propose equipment as previously described, the radiofrequency device comprising a beam steering system comprising a matrix of a plurality of antennas, the processing unit being arranged, to limit the radiated power, to control phases of electrical signals applied between terminals of the antennas of the beam steering system so as to modify a direction of emission of an electromagnetic beam generated by the beam steering system.

[0020] We further propose equipment as previously described, the processing unit being arranged to select, from a predefined table, for all the antennas, phase values ​​associated with the current orientation of the equipment and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, and to control the beam steering system so that the latter allocates said phase values ​​to the electrical signals applied to the terminals of the antennas.

[0021] We further propose equipment as previously described, in which, if the predefined table does not include phase values ​​associated with the current orientation and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, the processing unit selects the phase values ​​associated with the current orientation and with the lowest value of power radiated in the direction of the second reference zone, and further limits an electrical power of at least one electrical signal applied between terminals of at least one antenna.

[0022] We further propose equipment as previously described, in which the current orientation is defined by an Azimuth angle and an Elevation angle, the predefined table having been obtained from measurements of radiation patterns according to the Azimuth angle and the Elevation angle, carried out for the different phase values.

[0023] We further propose equipment as previously described, the radiofrequency device comprising antennas, a radiofrequency transmission chain arranged to produce electrical signals, and at least one switch arranged to implement configurable connections between the antennas and the radiofrequency transmission chain, the processing unit being arranged to limit the radiated power, to control the at least one switch to reconfigure the configurable connections.

[0024] We further propose equipment as previously described, in which the at least one quantity representative of the current orientation of the equipment comprises at least one acceleration of the equipment along a predefined axis.

[0025] We further propose equipment as previously described, the processing unit being arranged to convert the at least one acceleration into at least one angle relative to at least one reference direction or a reference plane.

[0026] We further propose equipment as previously described, in which the processing unit is also arranged to produce a notification intended for a user of the equipment and requesting the latter to reposition the equipment to reinstall it with the nominal orientation.

[0027] We further propose equipment as previously described, in which the second reference zone is a vertical angular cone having the equipment as its apex.

[0028] We further propose equipment as previously described, the equipment being an access point.

[0029] We further propose a method for transmitting radiofrequency signals, implemented in the processing unit of equipment such as previously described, and comprising the steps of:

[0030] - acquire measurements of at least one quantity representative of the orientation current equipment;

[0031] - if the current orientation of the equipment is such that the radiated power in direction of the second reference zone is likely to exceed the second predefined power threshold, control the radiofrequency device to limit the power radiated in the direction of the second reference zone and thus ensure that the power radiated in the direction of the second reference zone becomes lower than the second predefined power threshold.

[0032] A computer program is further provided comprising instructions which cause the processing unit of the equipment as previously described to execute the steps of the method of transmitting radiofrequency signals as previously described.

[0033] A computer-readable recording medium is further provided, on which the computer program as previously described is recorded.

[0034] The invention will be better understood in light of the following description of particular non-limiting embodiments of the invention. Brief description of the drawings

[0035] Reference will be made to the attached drawings, among which:

[0036] [Fig-1] [Fig.l] represents the PIRE limits as a function of the elevation for a prior art equipment;

[0037] [Fig.2] [Fig.2] represents equipment according to a first embodiment;

[0038] [Fig.3] [Fig.3] represents a 3-axis accelerometer;

[0039] [Fig.4] [Fig.4] represents steps of a transmission method;

[0040] [Fig.5] [Fig.5] represents equipment according to a second embodiment, as well as electromagnetic beams;

[0041] [Fig.6] [Fig.6] also represents the equipment according to the second mode of rea lization, ;

[0042] [Fig.7] [Fig.7] is a view similar to that of [Fig.5], when the equipment is inclined;

[0043] [Fig.8] [Fig.8] represents the vertical cone, a reference mark defined by a nominal position of the equipment and a reference mark defined by an inclined position of the equipment;

[0044] [Fig.9] [Fig.9] represents the vertical cone in a radiation diagram while the equipment is in its nominal position;

[0045] [Fig. 10] [Fig. 10] represents the vertical cone in a radiation pattern while the equipment is in an inclined position;

[0046] [Fig. 11] [Fig. 11] represents equipment according to a third embodiment;

[0047] [Fig. 12] [Fig. 12] represents radiation patterns of the equipment positioned in different orientations;

[0048] [Fig. 13] [Fig. 13] represents equipment according to a fourth embodiment. DETAILED DESCRIPTION

[0049] With reference to [Fig.2], the equipment according to a first embodiment is here a Wi-Fi access point 1 which integrates a radiofrequency device 2, a measuring device 3 and a processing unit 4.

[0050] The radiofrequency device 2 comprises one or more antennas 5 (here several) and a radiofrequency transmission chain 6 connected to the antennas 5 and comprising one or more amplifiers 7 (here several). The amplifiers 7 produce electrical signals which are applied between the terminals of the antennas 5 so that the latter emit radiofrequency signals so that the access point 1 implements a Wi-Fi network. The antennas 5 also receive radiofrequency signals.

[0051] The radiofrequency device 2 is designed to transmit radiofrequency signals of a certain frequency band (here the UNII5 band) by generating a radiated power which, when the access point 1 is installed with a nominal orientation, is less than a first predefined power threshold in the direction of a first reference area and is less than a second predefined power threshold in the direction of a second reference area, the second predefined power threshold being less than the first predefined power threshold. The first reference area and the second reference area are defined with respect to one or more reference axes or planes (e.g. vertical axis, horizontal plane, vertical plane, etc.) and are therefore defined independently of the current orientation of the access point 1.

[0052] Here, the second predefined zone is a vertical angular cone having as its vertex the access point 1 and defined by a minimum elevation angle. This minimum elevation angle is here equal to 30° (relative to a horizontal plane), as in [Fig. 1].

[0053] The first reference zone corresponds to the entire space around the access point 1 with the exception of said cone.

[0054] The nominal orientation of the access point 1 is the orientation defined in the user manual. When the access point 1 is installed with its nominal orientation, it is placed “right side up”, for example vertically, on a support itself substantially parallel to a horizontal plane.

[0055] Access point 1 therefore generates radiated power which differs depending on the direction.

[0056] Access point 1 thus complies with the American Wi-Fi AFC regulation which requires, as we have seen, if the active channel is in the UNII5 band, to limit the power transmitted above this 30° elevation with a PIRE limit of 21 dBm, while the PIRE limit is 36 dBm in the other directions.

[0057] The measuring device 3 produces measurements of at least one quantity representative of the current orientation of the access point 1. The at least one quantity comprises, for example, at least one acceleration of the access point 1 along a predefined axis.

[0058] The measuring device 3 here comprises a three-axis accelerometer 8, which is for example a MEMS type component (for Micro Electro-Mechanical System, or micro-electromechanical system).

[0059] This is for example the LIS2HH12 component from STMicroelectronics. Its small size (4 mm2) and the fact that it can communicate with a processor or with a microcontroller using the I2C or SPI protocols, make this component very easy to integrate into equipment such as the access point 1.

[0060] With reference to [Fig.3], the accelerometer 8 typically gives the following values, when the access point 1 is installed with a nominal orientation:

[0061] X-axis accelerometer (m / s2): 0

[0062] Y-axis accelerometer (m / s2): 0

[0063] Z-axis accelerometer (m / s2): -9.81

[0064] The processing unit 4 is an electronic and software unit. The processing unit 4 comprises at least one processing component 10, which is for example a “generalist” processor, a processor specialized in signal processing (or DSP, for Digital Signal Processor), a processor specialized for artificial intelligence algorithms (of the NPU type, for Neural Processing Unit), a microcontroller, or a programmable logic circuit such as an FPGA (for Field Programmable Gate Arrays) or an ASIC (for Application Specific Integrated Circuit).

[0065] The processing unit 4 also comprises one or more memories 11, connected to or integrated in the processing component 10. At least one of these memories 11 forms a computer-readable recording medium, on which is recorded at least one computer program comprising instructions which cause the processing unit 4 to execute at least some of the steps of the method for transmitting radiofrequency signals which will be described.

[0066] We will now describe the manner in which the radiofrequency device 2, the measuring device 3 and the processing unit 4 cooperate so that the emissions made by the access point 1 remain compliant with the American Wi-Fi AFC regulations, even when the access point 1 is poorly installed: placed upside down, inclined, placed straight but on an inclined support, etc.

[0067] Since the power radiated towards the first reference area may be greater than the second power threshold when the access point 1 is correctly installed, there is a risk, if the access point 1 is incorrectly installed, that the power radiated towards the second reference area may become greater than the second predefined power threshold.

[0068] The different stages of the transmission process, visible in [Fig.4], are implemented in the processing unit 4.

[0069] Access point 1 selects a channel subject to regulation according to the elevation: step EL Access point 1 is therefore about to transmit radio frequency signals in the UNII5 band.

[0070] The measuring device 3 produces the measurements of the accelerations along the three axes. The processing unit 4 acquires these measurements (but here only uses the acceleration along the Z axis): step E2.

[0071] The processing unit 4 compares the acceleration along the Z axis with a predefined acceleration threshold, which is for example equal to - 8 m / s2, which corresponds to an inclination of approximately 10° relative to the horizon: step E3.

[0072] As long as the acceleration along the Z axis remains lower than this predefined acceleration threshold (here lower than or equal), the processing unit 4 considers that the attitude of the access point 1 corresponds to its nominal attitude and therefore that it is installed with a nominal orientation. Accelerometer data is for example (0, 0, - 9.81) m / s2.

[0073] The radiated power is therefore in accordance with the regulations. The radiation pattern is therefore “ideal”, and the access point 1 therefore emits 36 dBm PIRE at most below 30° above the horizon and 21 dBm PIRE at most above 30° above the horizon. The processing unit 4 therefore does not modify the setting of the radiofrequency device 2 which therefore emits the radiofrequency signals in the UNII5 band in a nominal manner: step E4.

[0074] The process returns to step EL

[0075] It is possible that the current orientation of the access point 1 is modified, for example due to an impact, which also modifies the acceleration along the Z axis. The current orientation of the access point 1 therefore differs from the nominal orientation and is therefore such that the power radiated in the direction of the second reference zone is likely to exceed the second predefined power threshold.

[0076] In this case, the accelerometer data switches, for example to (-1, -6, -5) m / s2. At step E3, the acceleration along the Z axis therefore becomes equal to -5 m / s2 and therefore greater than the predefined acceleration threshold.

[0077] This has the consequence that the power radiated in the vertical cone mentioned above risks becoming higher than the second predefined power threshold. Access point 1 therefore no longer operates in accordance with the regulations.

[0078] The processing unit 4 controls the radiofrequency device 2 to limit the power radiated in the direction of the second reference zone and thus ensure that the power radiated in the direction of the second reference zone becomes lower than the second predefined power threshold.

[0079] For this, the processing unit 4 limits the electrical power of at least one electrical signal applied by at least one of the amplifiers 7 of the radiofrequency device 2 between the terminals of at least one of the antennas 5 of the radiofrequency device 2: step E5. The limitation is done at any point in the radiofrequency transmission chain 6 connected to the antenna (upstream or downstream or at the level of the amplifier(s) 7, at the level of the antenna connector, etc.).

[0080] At the same time, the processing unit 4 generates and transmits a notification to the user of the access point 1, for example by transmitting a message to the user's smartphone. This notification asks the user to reposition the access point 1 to reinstall it with the nominal orientation.

[0081] The method then moves to step E4.

[0082] The power limitation is maintained as long as the acceleration along the z axis remains higher than the predefined acceleration threshold (here strictly higher). Normally, following receipt of the notification, the user will quickly repo-

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[0097] locate access point 1 and the acceleration along the Z axis returns to approximately -9.81 m / s2 and therefore becomes lower than the predefined acceleration threshold. Access point 1 therefore retransmits at “high” power. It can be seen that only acceleration along the Z axis is considered, so a single-axis accelerometer could be used. Note that in step E3, the comparison can be made with several predefined acceleration thresholds. It is the modulus of the acceleration that can be compared with one or more thresholds, rather than the acceleration value itself. The acceleration being compared can be an average of several acceleration measurements taken over a predefined period. In an alternative embodiment, the processing unit 4 compares not an acceleration along a single axis, but several accelerations along several axes, which is easy to achieve because the accelerometer 8 is a 3-axis accelerometer. In another alternative embodiment, the processing unit 4 acquires the acceleration measurements and converts them into at least one angular value relative to at least one reference direction or at least one reference plane. The processing unit 4 can for example obtain the angular values ​​0, % q> (visible in [Fig.3]) using the following formulas: where Ax is the acceleration measured along the X axis by accelerometer 8, Ay is the acceleration measured along the Y axis, and Az is the acceleration measured along the Z axis. The processing unit 4 can be satisfied with the angular value q> (inclination relative to the vertical). In step E3 of the method of [Fig.3], the processing unit 4 therefore compares the current orientation with at least one predefined angular threshold. The current orientation is therefore estimated here by evaluating the angular value q>. The predefined angular threshold is here, for example, equal to ± 5°. As long as the attitude is nominal, that is to say as long as -5° < <t>< +5°, the processing unit 4 does not modify the configuration of the radiofrequency device 2 which therefore emits the radiofrequency signals in the UNII5 band in a nominal manner. If the attitude is not nominal, that is to say if:

[0098] O >5° or <î> < -5°,

[0099] then the processing unit 4 limits the radiated power to ensure that the power radiated in the direction of the second reference zone becomes lower than the second predefined power threshold.

[0100] With reference to figures 5 to 7, we are now interested in an access point 1 according to a second embodiment.

[0101] The radiofrequency device 2 comprises a beam steering system 20.

[0102] The beam steering system 20 comprises a matrix 21 of a plurality antennas 5 and the radiofrequency transmission chain 6.

[0103] This antenna matrix 21 forms a global antenna consisting of several sub-antennas (the antennas 5) whose phase is controllable, which makes it possible to control the orientation of the electromagnetic beam 22 (beam) emitted by the system. We speak of Beamsteering to designate this technique, which is a specific case of Beamforming.

[0104] As can be seen in [Fig.6], the antenna matrix 21 here comprises four antennas 5 which extend vertically. The beam 22 is therefore vertically controllable.

[0105] The processing unit 4 can control the transmission chain 6 and control the phase of each electrical signal applied between the terminals of each antenna 5, so as to control the direction of transmission of the electromagnetic beam 22 generated by the beam steering system. Different beams 22b 222,..., 22n oriented differently can therefore be generated by the radiofrequency device 2.

[0106] When the current orientation of the access point 1 differs from the nominal orientation, the processing unit 4 will, in order to limit the power radiated in the direction of the vertical cone, control the phases of the electrical signals applied between the terminals of the antennas 5 of the beam steering system 20 so as to modify the direction of emission of the electromagnetic beam generated by the beam steering system 20.

[0107] As can be seen in [Fig.7], when the access point 1 is inclined at an angle of X° relative to a vertical axis, the processing unit 4 typically imparts an equivalent angle to the beam 22 to ensure that the radiated power remains in accordance with the directional requirements.

[0108] To modify the direction of emission of the beam, the processing unit 4 uses a predefined table 23.

[0109] The predefined table 23 is filled in by the manufacturer of the access point 1 during a calibration phase carried out for example following the assembly of the access point 1 and prior to its delivery. The predefined table 23 is for example stored in one of the memories 11 of the processing unit 4. The values ​​that it contains can possibly be updated and / or configured, possibly remotely or by the user.

[0110] The processing unit 4 selects, from the predefined table 23, for all the antennas 5, phase values ​​associated with the current orientation of the access point 1 and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, then controls the beam steering system 20 so that the latter allocates said phase values ​​to the electrical signals applied to the terminals of the antennas 5.

[0111] Here, with reference to [Fig.8], the current orientation is defined by an Azimuth angle 0 and an Elevation angle q> (in spherical coordinates). These angles are either measured by the measuring device 3, or are evaluated by the processing unit 4 from other quantities measured by the measuring device 3 (accelerations for example).

[0112] Note that this time, the vertical cone 24 is defined by an angle q> less than 60°.

[0113] The predefined table 23 was obtained from measurements of diagrams of radiation according to the Azimuth angle and the Elevation angle, carried out for different phase values.

[0114] The manufacturer of the access point 1, during the calibration phase, measured all the possible combinations of radiation patterns as a function of the phase values ​​allocated to the electrical signals applied to the terminals of each of the four antennas 5 of the antenna matrix 21.

[0115] It is possible to limit oneself for example to controlling the phase of the antennas 5 in steps of 90° to have 360 / 90 = 4 possible values ​​per antenna 5. The phase values ​​are therefore 0°, 90°, 180°, 270°.

[0116] Each radiation pattern was therefore measured as a function of the Azimuth and Elevation angles, with angular steps of 5° for example. The manufacturer obtained radiated power values ​​from the radiation patterns and associated with the different combinations of phase values.

[0117] The predefined table 23 includes: - first combinations between all the angular steps of the Azimuth angle and the Elevation angle; - second combinations between all phase values ​​for all antennas; - each first combination is associated with all the second combinations to form third combinations; - each third combination is associated with a value of power radiated towards the second reference zone.

[0118] We therefore have: - 4 phase values ​​for each antenna, i.e. 4x4x4x4 = 256 combinations of phase values; - if the radiation pattern is measured in angular steps of 5° in Azimuth and Elevation, we have (180 / 5+1) * (360 / 5 +1) = 2701 angle values ​​in total.

[0119] We therefore obtain 256 * 2701 « 700,000 third combinations of phase values ​​ / angular steps / antennas.

[0120] This large number should be put into perspective. It typically takes 10 ms to measure one phase per position, or about 3 seconds to measure the 256 phases per position.

[0121] The predefined table 23 can also indicate, for each third combination, the phase values ​​which make it possible to obtain the minimum (and / or maximum) of PIRE for each cone of 2*60 degrees describing the sphere (the angle q> of 60° degrees corresponds here to the cone defined by the Fcc at 6 GHz but the same principle can be applied for any angular restriction).

[0122] Table 23 is for example similar to the table in the Appendix.

[0123] In the case where the access point 1 undergoes an inclination, it is therefore necessary to calculate the area of ​​the radiation pattern that is subject to the EIRP restriction.

[0124] The processing unit 4 therefore acquires the acceleration measurements, converts them into Azimuth 0 and Elevation q> angles, then scans table 23 to find the zone corresponding to the 60° cone.

[0125] The processing unit 4 finds the area of ​​the 60° cone by shifting the center of the cone by 0 in Azimuth and by q> in Elevation.

[0126] With reference to [Fig.9], when the access point 1 is in its nominal position (q> = 0°), the vertical cone corresponds in the radiation diagram to the North Pole and therefore to the entire zone 25 located below 60° elevation.

[0127] With reference to [Fig. 10], when access point 1 is inclined by (0, q>), the vertical cone can be traversed discretely starting from 0 and q> and adding 60° on each side. The vertical cone is seen on the radiation pattern as a circle represented discretely: zone 26. The highest value of the EIRP within this zone is noted, as well as the lowest.

[0128] The predefined table 23 therefore contains all the cones with axes described by the inclination angles 0 and q>.

[0129] In the example of the table in the Appendix, we therefore see that if the access point 1 undergoes an inclination of (0, q>) = (145°, 70°), then the processing unit 4 selects the phase values ​​(90°, 270°, 90°, 90°), which makes it possible to obtain a radiated power with a PIRE of 15 dBm in the vertical cone.

[0130] The processing unit 4 therefore calculates the inclination angles 0 and q>, defining the current orientation of access point 1.

[0131] If the current orientation of the access point 1 requires a limitation, the processing unit 4 checks in the predefined table 23 that there is indeed a combination of phase values ​​for which the power radiated in the direction of the second reference zone is lower than the second predefined power threshold (i.e. here for which the EIRP in the cone is lower than the limitation of 21 dBm).

[0132] If this is the case, the processing unit 4 selects these phase values ​​and controls the beam steering system 20 so that the latter allocates said phase values ​​to the electrical signals applied to the terminals of the antennas 5.

[0133] If the predefined table 23 does not include phase values ​​associated with the current orientation and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, the processing unit 4 selects the phase values ​​associated with the current orientation and with the lowest value of power radiated in the direction of the second reference zone, and further limits the electrical power of at least one electrical signal applied between terminals of at least one antenna 5.

[0134] The processing unit 4 therefore selects the combination which gives the smallest EIRP and, in addition, lowers the emitted power to return to the value of 21 dBm. For example, if in the cone area there is a maximum EIRP of 24 dBm, then the processing unit 4 can lower the power of the electrical signal by 3 dB (at the antenna connector for example).

[0135] In both cases, the beam steering system 20 produces a beam that allows the access point to remain compliant with regulations.

[0136] This example is of course not exhaustive. It is possible to increase or reduce the number of phase values, angular steps, the number of steerable elements (antennas), etc.

[0137] Alternatively, the processing unit 4 uses a mathematical formula describing the vertical cone exactly. This solution is advantageous if the number of values ​​is increased (reduced angular steps, more phase values, etc.).

[0138] We are now interested in a third embodiment, with reference to figures 11 and 12.

[0139] In this embodiment, the radiofrequency device 2 comprises antennas 5a, 5b, a transmission chain 6 comprising one or more amplifiers 7, and at least one switch 30 arranged to implement configurable connections between the antennas 5 and the transmission chain 6.

[0140] We speak of smart antenna to designate this system, or of reconfigurable antenna, or of beam switching.

[0141] In the example of [Fig. 11], the radiofrequency device 2 comprises two antennas 5a, 5b (e.g. two radiating strands). Switch 30 is a one-input, two-output switch. Each output of switch 30 is connected to a separate radiating strand 5a, 5b.

[0142] An electrical signal produced by chain 6 is applied to the input of switch 30 and is selectively transmitted to one or both radiating strands 5a, 5b (or to none).

[0143] The footprint accommodating the switch 30 is positioned inside a ground plane 31 on a printed circuit 32 of an electrical card of the access point, and the electrical signal at the input and output of the switch 30 travels on tracks defined inside this ground plane 31.

[0144] With reference to [Fig. 12], in this example with two radiating elements, the two radiating strands are oriented at 90° to each other and therefore have a complementary antenna pattern: pattern 35 for radiating strand 5a and pattern 36 for radiating strand 5b. The radiation patterns 35, 36, when the access point 1 is rotated parallel to the plane of the pattern shown, are also rotated by the same angle.

[0145] In the left diagram of [Fig. 12], the access point has not rotated. It is the radiating strand 5a which is active in the direction of the vertical cone.

[0146] In the central diagram of [Fig.12], access point 1 has rotated through an angle of approximately 30°. Radiating strand 5a is active but with a reduction in power.

[0147] In the right diagram of [Fig. 12], the access point has rotated through an angle of approximately 85°. Radiating strand 5b is active.

[0148] We can therefore delimit three zones in the radiation diagram according to the inclination of access point 1:

[0149] Zone 1: Active radiating strand 5a;

[0150] Zone 2: Active 5b radiating strand;

[0151] Zone 3: power reduction zone, with either active (default the most pupil).

[0152] In [Fig. 12], the second reference area is area 37.

[0153] In the central diagram, it is constant that the resulting gain is always high in the limited area. It is therefore appropriate to reduce the radiated power to reach the limit.

[0154] To limit the power radiated towards the second reference zone, the processing unit 4 controls the switch 30 so as to reconfigure the reconfigurable connections (here, the connections between the radiating strands 5a, 5b and the chain 6).

[0155] When the current orientation of the access point 1 differs from the nominal orientation and is such that the power radiated in the direction of the second reference zone can exceed the second predefined power threshold, the processing unit 4 can control the switch 30 so that the radiated power is at the minimum level for that, whatever the gain of the antennas, the limitation on high elevation is always respected.

[0156] Alternatively, if the processing unit 4 knows the tilt and gain according to the tilt of the antennas 5a, 5b, the processing unit 4 can configure the configurable connections so as to reduce the power while being close to the limit.

[0157] For example, if the antenna gain is 5 dBi max in the restricted area, and this restricted area is at 23 dBm PIRE, the processing unit 4 lowers the power, for example at the antenna connector, to 23 - 5 = 18 dBm.

[0158] There are only two radiating elements in Figures 11 and 12, but what has just been said obviously applies to a system comprising a higher number of switchable elements and therefore more different diagrams and therefore fewer areas where the power must be reduced.

[0159] In a fourth embodiment, with reference to [Fig. 13], the radiofrequency device 2 integrates an antenna 5 mounted on a rotating mechanical support 40. The support comprises a rotating base 41 driven in rotation by a first motor 42 and an antenna support 43 driven in rotation by a second motor 44.

[0160] The two motors 42, 44 are for example two servomotors or stepper motors, which therefore control two axes XI, X2.

[0161] The processing unit pivots the antenna 5 so that it remains in its initial vertical position.

[0162] To limit the power radiated towards the second reference zone, the processing unit controls the two motors 42, 44 to control the angle of the antenna 5 and thus correct the radiation to compensate for the inclination of the equipment. This control is carried out by the processing unit using for example the PWM (Pulse Width Modulation) technique.

[0163] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention.

[0164] The equipment in which the invention is implemented is not necessarily an access point; it can be any equipment emitting radiofrequency signals.

[0165] The second reference area is not necessarily a vertical cone, it could for example be an area defined between a positive elevation angle and a negative elevation angle defined relative to a horizontal plane.

[0166] The predefined table could be different from the one described here. For example, it could contain acceleration steps rather than angular steps. APPENDIX

[0167] Example of a predefined table: e° 9° EIRP (in dBm) Max or Min Phase 1 (in °) Phase 2 (in °) Phase 3 (in °) Phase 4 (in °) 145 70 24 Max 0 90 0 270 145 70 15 Min 90 270 90 90< / t>

Claims

Claims

1. Equipment (1) comprising: - a radiofrequency device (2) arranged to transmit radiofrequency signals by generating a radiated power which, when the equipment is installed with a nominal orientation, is less than a first predefined power threshold in the direction of a first reference zone and is less than a second predefined power threshold in the direction of a second reference zone (24), the second predefined power threshold being less than the first predefined power threshold; - a measuring device (3) arranged to measure at least one quantity representative of a current orientation of the equipment;- a processing unit (4) arranged to, if the current orientation of the equipment differs from the nominal orientation and is such that the power radiated in the direction of the second reference zone is likely to exceed the second predefined power threshold, control the radiofrequency device (2) to limit the power radiated in the direction of the second reference zone and thus ensure that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold.;

2. Equipment according to claim 1, wherein, to limit the power radiated towards the second reference zone (24), the processing unit (4) is arranged to limit an electrical power of at least one electrical signal applied between terminals of at least one antenna (5) of the radiofrequency device (2).

3. Equipment according to claim 1, the radiofrequency device comprising a beam steering system (20) comprising an array (21) of a plurality of antennas (5), the processing unit (4) being arranged, to limit the radiated power, to control phases of electrical signals applied between terminals of the antennas of the beam steering system so as to modify a direction of emission of an electromagnetic beam (22) generated by the beam steering system.

4. Equipment according to claim 3, the processing unit (4) being arranged to select, from a predefined table (23), for all the antennas (5), phase values ​​associated with the current orientation of the equipment (1) and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, and to control the beam steering system (20) so that the latter allocates said phase values ​​to the electrical signals applied to the terminals of the antennas.

5. Equipment according to claim 4, wherein, if the predefined table (23) does not include phase values ​​associated with the current orientation and such that the power radiated in the direction of the second reference zone is lower than the second predefined power threshold, the processing unit (4) selects the phase values ​​associated with the current orientation and with the lowest value of power radiated in the direction of the second reference zone, and further limits an electrical power of at least one electrical signal applied between terminals of at least one antenna (5).

6. Equipment according to one of claims 4 or 5, in which the current orientation is defined by an Azimuth angle and an Elevation angle, the predefined table (23) having been obtained from measurements of radiation patterns according to the Azimuth angle and the Elevation angle, carried out for the different phase values.

7. Equipment according to claim 1, the radiofrequency device (3) comprising antennas (5a, 5b), a radiofrequency transmission chain (6) arranged to produce electrical signals, and at least one switch (30) arranged to implement configurable connections between the antennas and the radiofrequency transmission chain (6), the processing unit being arranged, to limit the radiated power, to control the at least one switch (30) so as to reconfigure the configurable connections.

8. Equipment according to one of the preceding claims, in which the at least one quantity representative of the current orientation of the equipment (1) comprises at least one acceleration of the equipment (1) along a predefined axis.

9. Equipment according to claim 8, the processing unit (4) being arranged to convert the at least one acceleration into at least one angle relative to at least one reference direction or reference plane.

10. Equipment according to one of the preceding claims, in which the processing unit (4) is also arranged to produce a notification intended for a user of the equipment (1) and requesting the latter to reposition the equipment to reinstall it with the orientation nominal.

11. Equipment according to one of the preceding claims, in which the second reference zone is a vertical angular cone (24) having the equipment as its apex.

12. Equipment according to one of the preceding claims, the equipment being an access point.

13. Method for transmitting radiofrequency signals, implemented in the processing unit (4) of equipment (1) according to one of the preceding claims, and comprising the steps of: - acquiring measurements of the at least one quantity representative of the current orientation of the equipment (1); - if the current orientation of the equipment is such that the power radiated in the direction of the second reference zone is likely to exceed the second predefined power threshold, controlling the radiofrequency device (2) to limit the power radiated in the direction of the second reference zone and thus ensure that the power radiated in the direction of the second reference zone becomes lower than the second predefined power threshold.

14. Computer program comprising instructions which cause the processing unit (4) of the equipment according to one of claims 1 to 12 to execute the steps of the method of transmitting radiofrequency signals according to claim 13.

15. A computer-readable recording medium on which the computer program according to claim 14 is recorded.

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