Method and device for controlling the operation of a wireless communication device

Abstract

Method and Device for Controlling the Operation of a Wireless Communication Device. The invention relates to a method for controlling the operation of a wireless communication device (100) comprising a plurality of antennas (110, 120) configured to radiate spatially along distinct zones. The method comprises an alternative selection step (E40) of said antennas for emitting a communication signal. This selection is performed such that the average specific absorption rate generated by each antenna over a given period of time, and considering a given distance, referred to as the "control distance," between the communication device and the human body is less than a predetermined threshold. Figure for the abstract: Fig. 3

Description

Title of the invention: Method and device for controlling the operation of a wireless communication device Prior art

[0001] The present invention belongs to the general field of telecommunications. It relates more particularly to a method for controlling the operation of a wireless communication device, as well as a control device configured to implement said control method. It also relates to a wireless communication device equipped with said control device. The application finds a particularly advantageous, although in no way limiting, application in the case where the wireless communication device is a mobile telephone, in particular a smart mobile telephone ("smartphone").

[0002] With the aim of protecting people's health from potential harmful effects generated by exposure to radio waves (i.e. electromagnetic waves propagating by non-wireless means and whose frequencies are included in the traditional spectrum ranging from a few hertz to several hundred gigahertz), different regulations have been put in place in certain territories / countries.

[0003] Most of these regulations, particularly those in force in Europe and the United States, have in common the fact that they impose limitations on exposure to radio waves using an index known as the "specific absorption rate", even more commonly referred to by its acronym "DAS" ("SAR" in the English literature, as an acronym for the expression "Specific Absorption Rate").

[0004] In a known manner, the SAR corresponds to a measurement indicating the power of an energy flow carried by the radio waves emitted by a wireless communication device (mobile phone, tablets, connected watch for example) and absorbed by a human body, in principle the user of said device, when the device operates at a given transmission power level (typically at full transmission power).

[0005] In the International System of Units, the unit of measurement for SAR is the watt per kilogram (W / kg). The measurement of SAR is carried out in a manner known per se, namely by using, for example, a measuring bench equipped with a humanoid mannequin filled with liquid having the same dielectric properties as those of the human body.

[0006] As a general rule, the exposure limits imposed in terms of SAR are broken down according to the areas of the body concerned. For example, and with particular regard to European regulations applicable to any communication device, communication capable of transmitting at a frequency between 100 kHz and 10 GHz at a distance less than or equal to 20 cm from the human body and using a transmission power greater than or equal to 20 mW, the current exposure limits are as follows: - for the head or trunk, SAR of 2 W / kg on a 10g sample of human matter in instantaneous measurement if the emission power is stable or in average measurement over a period of time equal to 6 minutes, - for limbs (arms, legs), SAR of 4 W / kg on a 10g sample of human matter in instantaneous measurement if the emission power is stable or in average measurement over a period of time equal to 6 minutes.

[0007] It should be noted that these European exposure limits are defined for a given distance between the emitting communication device and the human body. Thus, for the limbs, the distance is 0 mm. For the head, the distance is also 0 mm (it being understood that the communication device is positioned on the mannequin very precisely with a wedge and an angle which are indicated in the standard). Finally, for the trunk, the distance considered until recently was equal to 5 mm. However, with a view to imposing a greater limitation in terms of exposure level, it was decided that the distance considered for the measurement of the SAR at the trunk will soon be zero.

[0008] Generally speaking, both in Europe and in other territories, there is a tightening of regulations relating to the level of exposure to electromagnetic fields, which therefore imposes ever stricter limitations on the level of SAR to which a user may be subjected, whether in terms of measurement distances and / or SAR limit values.

[0009] Faced with this situation, a possible solution for complying with ever more restrictive exposure limits could be to reduce the maximum transmission power of a wireless communication device.

[0010] This solution nonetheless remains problematic insofar as it causes a drop in uplink speeds, and therefore ultimately a degraded quality of service.

[0011] A possible theoretical way to at least partially compensate for these disadvantages could possibly consist of massive investments on the part of communication operators, in particular by considerably increasing the number of base stations installed. However, here again, this solution remains problematic due to its implementation cost, both in financial and material terms and in terms of pre-empted ground space. Statement of the invention

[0013] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above, by proposing a solution which makes it possible to comply with exposure limitations expressed in terms of average SAR (i.e. SAR averaged over a given period of time) more effectively than the solutions of the prior art.

[0014] By "more efficient" we refer here to a solution guaranteeing an excellent uplink rate, and therefore an excellent quality of service, and whose implementation cost (financial, material, preemption of floor space) is minimal.

[0015] To this end, and according to a first aspect, the invention relates to a method for controlling the operation of a wireless communication device comprising a plurality of antennas configured to radiate spatially in distinct zones. Said method comprises a step of alternatively selecting said antennas to emit a communication signal, said selection being carried out so that the average specific absorption rate generated by each antenna over a given period of time as well as considering a given distance, called "control distance", between the communication device and the human body is less than a determined threshold.

[0016] Thus, the control method according to the invention makes it possible to distribute the transmission power of the wireless communication device between the antennas in an alternative and spatial manner. In other words, the wireless communication device transmits a communication signal at a constant power, such as for example its maximum transmission power, which makes it possible to ensure an excellent uplink throughput, and therefore an excellent quality of service.

[0017] What is more, and this is the fundamental point of differentiation compared to the state of the art, these excellent communication performances are achieved while respecting a SAR threshold, which can for example be derived from exposure limits imposed within the framework of a regulatory constraint.

[0018] In other words, the fact of alternately using the antennas (configured to radiate spatially according to distinct zones) of the wireless communication device advantageously makes it possible to integrate the constraint of respecting exposure limits while guaranteeing excellent communication performance. Achieving this advantageous result is also inexpensive in terms of means of realization.

[0019] In particular embodiments, the control method may further comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations.

[0020] In particular embodiments, the number of antennas is strictly greater than two.

[0021] In particular embodiments, the transmission power used by a selected antenna is the maximum transmission power of the wireless communication device.

[0022] In particular embodiments, the method comprises a step of evaluating a distance between the communication device and the human body, the execution of the selection step being subsequent to the fact that said evaluated distance is less than a given threshold.

[0023] In particular embodiments, the method comprises a step of evaluating the transmission power used by an antenna currently in use to transmit said communication signal, the execution of the selection step being subsequent to the fact that said evaluated transmission power is greater than a given threshold.

[0024] In particular embodiments, the step of evaluating the transmission power comprises a set of evaluations of the transmission power by respectively considering a set of control distance values, said evaluated transmission power corresponding to the maximum transmission power obtained from said set of evaluations of the transmission power.

[0025] For example, the transmission power can be evaluated for 0mm, 1mm, 2mm, 3mm, 4mm and 5mm of the human body, the maximum transmission power value being considered as being the transmission power used to compare it to a threshold distance and depending on the comparison, implement or not implement the selection step.

[0026] In particular embodiments, the alternative selection of the antennas is carried out according to a fixed or dynamic periodicity.

[0027] In particular embodiments, the communication signal is a mobile telephone signal or a Wi-Fi signal or a Bluetooth signal.

[0028] In particular embodiments, said control distance is zero.

[0029] In particular embodiments, said time period is equal to six minutes.

[0030] In particular embodiments, the threshold of said average specific absorption rate is equal to 2 W / kg.

[0031] In particular embodiments, the maximum transmission power of the communication device is greater than or equal to 20 mW.

[0032] According to a second aspect, the invention relates to a computer program comprising instructions for implementing a control method according to the invention when said computer program is executed by a computer.

[0033] This program may use any programming language, and be in the form of source code, object code, or code intermediate between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0034] According to a third aspect, the invention relates to a computer-readable information or recording medium on which a computer program according to the invention is recorded.

[0035] The information or recording medium may be any entity or device capable of storing the program. For example, the medium may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a hard disk.

[0036] On the other hand, the information or recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention may in particular be downloaded from a network such as the Internet.

[0037] Alternatively, the information or recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

[0038] According to a fourth aspect, the invention relates to a control device comprising means configured to implement a control method according to the invention.

[0039] According to a fifth aspect, the invention relates to a wireless communication system comprising a plurality of antennas configured to radiate spatially according to distinct zones as well as a control device according to the invention.

[0040] According to a sixth aspect, the invention relates to a communication method implemented by a wireless communication device according to the invention.

[0041] Brief description of the drawings

[0042] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures:

[0043] [Fig. 1] [Fig. 1] schematically represents a particular embodiment of a wireless communication device according to the invention;

[0044] [Fig.2] [Fig.2] schematically represents an example of hardware architecture of a control device according to the invention integrated into the wireless communication device of [Fig.l];

[0045] [Fig.3] [Fig.3] represents, in the form of a flowchart, a particular mode of implementation of a communication method, called “general method”, implemented by the wireless communication device of [Fig.l], said general method including a control method according to the invention implemented by the control device of [Fig.2];

[0046] [Fig.4] [Fig.4] illustrates a specific example of application of the commu method nication of [Fig.3].

[0047]

[0048] Description of embodiments

[0049] [Fig.l] schematically represents a particular embodiment of a wireless communication device 100 according to the invention.

[0050] For the remainder of the description, the notions of “top” and “bottom” are defined relative to the vertical axis X shown in [Fig.l], it being understood that the direction in which said axis X is oriented designates “top”.

[0051] It is also considered in a non-limiting manner that the wireless communication device 100 is a smartphone belonging to a user, and that the communication device 100 is equipped with two antennas, a first antenna 110 and a second antenna 120. It is further considered that the maximum transmission power of the wireless communication device 100 (i.e. the maximum power usable on each antenna 110, 120 to transmit a communication signal) is greater than or equal to 20 mW.

[0052] More particularly, and as illustrated by [Fig.l], the antennas 110, 120 are integrated into the structure of the device 100, for example at its periphery. Furthermore, the antennas 110, 120 are configured to radiate spatially according to distinct zones of the device 100 (i.e. the first and second antennas 110, 120 are not co-located). Thus, the first antenna 110 (respectively the second antenna 120) is configured to radiate upwards (respectively the bottom) of the wireless communication device 100. It should be noted that this difference in the spatial orientation of the first and second antennas 110, 120 implies, in the embodiment considered here, that the first antenna 110 (respectively the second antenna 120) radiates primarily at the level of the user's head (respectively at the level of the user's trunk).

[0053] It should however be noted that these provisions are not limiting of the invention. In particular, no limitation is attached to the nature of the device 100 since the latter is capable of carrying out wireless communications. For example, as an alternative to a smartphone, it may be a digital tablet, a laptop, a personal assistant, a connected watch, an electronic reader, etc.

[0054] Similarly, no limitation is attached to the maximum power transmission power of the wireless communication device 100. It should be noted, however, that the maximum transmission power may have an upper limit due to the existence of a communication standard imposed locally by regulations, this upper limit depending on the frequency band used for communication. These aspects being well known to those skilled in the art, they are not detailed further here.

[0055] The number of antennas does not constitute a limitation of the invention since a plurality are capable of radiating in distinct zones. In other words, nothing excludes the possibility of considering several antennas capable of radiating at the level of identical (or substantially identical) zones of the wireless communication device 100, since, among all the antennas equipping said device 100, at least two of these antennas are capable of radiating in distinct zones. Indeed, and as described in detail later, said at least two antennas capable of radiating in distinct zones are intended to be used specifically to limit the specific absorption rate generated during the transmission of a communication signal.

[0056] Furthermore, in the present embodiment, the device 100, and therefore in particular the first and second antennas 110, 120, are configured to transmit and receive communication signals corresponding to 4G mobile telephony signals. It should however be specified that the invention remains applicable to other types of communication signals, such as for example mobile telephony signals other than 4G (for example 2G, 3G, 5G, but also 6G when it will be available), Wi-Fi signals, WiMax signals, Bluetooth signals, etc. In general, no limitation is attached to the communication signals that can be considered within the scope of the present invention as long as they are radio signals.

[0057] In addition to said first and second antennas 110, 120, the wireless communication device 100 is configured in hardware and software to transmit and receive said communication signals. For this purpose, and conventionally, the device 100 comprises at least one transmission chain and at least one reception chain (not shown in the figures). Each transmission chain comprises, for example, a digital-to-analog converter, a modulator and a power amplifier. Each reception chain, for its part, comprises, for example, a low-noise amplifier, a demodulator and an analog-to-digital converter.

[0058] The device 100 also comprises an electronic signal processing unit (not shown in the figures), commonly called a “DSP” unit (acronym for the English expression “Digital Signal Processor”), and configured to generate baseband signals intended to be routed to the antennas 110, 120 via said at least one transmission chain as well as to process signals received by the antennas 110, 120 and routed to said DSP unit via said at least one reception chain.

[0059] The wireless communication device 100 also comprises switching means 130 capable of selectively connecting the first antenna 110 or the second antenna 120 to a transmission / reception chain in order to enable the transmission / reception of a communication signal. Such switching means 130 are of a design known per se. By way of non-limiting example, it may be a duplexer or a selection switch.

[0060] Generally speaking, those skilled in the art know the conventional architecture of a wireless communication device capable of transmitting / receiving radio signals, so these aspects are not detailed further here.

[0061] The wireless communication device 100 further comprises a control device 140 implementing processing aimed at controlling the operation of the device 100 so as to limit the time-averaged SAR generated by each of said antennas 110, 120, by implementing a method for controlling the operation of said device 100.

[0062] [Fig.2] schematically represents an example of hardware architecture of the control device 140 integrated into the wireless communication device 100 of [Fig.l].

[0063] As illustrated by [Fig.2], the control device 140 has the architecture hardware of a computer. Thus, the control device 140 comprises, in particular, a processor 141, a random access memory 142, a read only memory 143 and a non-volatile memory 144. It also has communication means 145.

[0064] The read-only memory 143 of the control device 140 constitutes a recording medium in accordance with the invention, readable by the processor 141 and on which is recorded a computer program PROG in accordance with the invention, comprising instructions for the execution of steps of the control method. The program PROG defines functional modules of the control device 140, which rely on or control the hardware elements 141 to 145 of the control device 140 cited above. These functional modules are illustrated in [Fig.l] in a non-limiting manner, and are described in more detail below with reference to different modes of implementation.

[0065] The communication means 145 allow in particular the device 141 to transmit control signals to the switching means 130 in order to select the first antenna 110 or the second antenna 120 (i.e. in order to selectively connect the first antenna 110 or the second antenna 120 to a transmission / reception chain in order to allow the transmission / reception of a communication signal). To this end, the communication means 145 may for example comprise a computer data bus capable of transmitting said control signals. Alternatively, said control signals may be transmitted via a communication interface, wired or wireless, capable of implementing any suitable protocol known to those skilled in the art. Furthermore, the communication means 145 also integrate the first and second antennas 110, 120.

[0066] It should be noted that in the embodiment described here with reference to Figures 1 and 2, it is considered that the control device 140 is an element external to the general processor (not shown in the figures) of the wireless communication device 100 (such a general processor is also called a “chipset” or “SoC” (abbreviation of “System on Chip”) in the English literature). Of course, such arrangements are not limiting of the invention, and nothing excludes the possibility of considering other embodiments in which the control device 140 is integrated into said general processor.

[0067] [Fig. 3] represents, in the form of a flowchart, a particular mode of implementation of a communication method, called “general method”, implemented by the wireless communication device 100. Said general method includes the control method according to the invention implemented by the control device 140 of [Fig. 2].

[0068] As mentioned above, the SAR considered in the context of the present invention is a time-averaged SAR, also called “average SAR”. The time average of the SAR is carried out over a given period of time T_DAS. What is more, and conventionally, said average SAR is evaluated by considering a given distance, called “control distance” D_DAS, between the communication device 100 and the human body (i.e. the body of the user of said device 100).

[0069] Also, for the description of this mode of implementation of the communication method, and therefore a fortiori of the control method, we consider in a non-limiting manner an emission of a 4G communication signal in a specific context of regulatory constraint, for example a regulatory constraint derived from national legislation. This regulatory constraint imposes on the two antennas 110, 120 exposure limits in terms of average SAR. More particularly, these exposure limits are expressed here in the following manner: - the time period T_DAS considered for the average DAS is equal to six minutes, - the maximum threshold S_DAS (i.e. the threshold not to be exceeded) in terms of average DAS is equal to 2 W / kg for 10g of human matter, - the control distance D_DAS is zero. It should be noted that having a control distance D_DAS of zero amounts to considering the strictest possible regulation in terms of distance, thus comparable to what is practiced by example in Europe now for what concerns the head and trunk.

[0070] It is important to note, however, that the values ​​of the parameters taken into account to define the exposure limits constitute only one implementation variant of the invention, and nothing excludes the possibility of considering other values, whether in terms of time period and / or maximum threshold and / or control distance. In particular, it is understood that this or these values ​​may come from a communication standard imposed by regulation in a given geographical area (example: in the United States, the time period considered is equal to 1 minute and 30 seconds). According to another example, the control distance may have a value between 0 and 5 mm.

[0071] Furthermore, the parameters which are taken into account in this embodiment are applicable to all the antennas of the wireless communication device 100, therefore in particular to the first and second antennas 110, 120, in order to define exposure limits common to all said antennas. However, here again, such provisions are not limiting of the invention, and nothing excludes considering different values ​​of time period and / or maximum threshold and / or control distance so as to define exposure limitations specific to each antenna (example: a threshold of 2 W / kg can be set for the antenna(s) radiating in the direction of the trunk and the head, and another threshold of 4 W / kg for the antenna(s) radiating in the direction of the limbs).

[0072] Finally, it is further considered that when the communication method begins, the switching means 130 are initially configured to connect the second antenna 120 to a transmission chain of the wireless communication device 100.

[0073] As illustrated by [Fig. 3], the communication method firstly comprises a step E10 of generating a communication signal SIG_COM. Said step E10 is implemented by the wireless communication device 100, more particularly by the DSP unit described above.

[0074] This generation of the communication signal SIG_COM follows, for example, the dialing of a telephone number by the user of the device 100, in order to enter into communication with the user of another smartphone to which said telephone number is assigned.

[0075] Insofar as the switching means 130 connect the second antenna 120 to a transmission chain when the SIG_COM signal is generated, it is this second antenna 120 which is intended to be used first to carry out the transmission of said SIG_COM signal.

[0076] In the embodiment described here with reference to [Fig. 3], the communication method also comprises a step E20 of evaluating a distance D_BODY between the wireless communication device 100 and the user's body. said device 100. Said step E20 is implemented by a module M0D_EVAL equipping the control device 140, and is part of the control method.

[0077] It is understood that when the user of the device 100 dials the number to be called, the device 100 is moved away from the body of said user. Once the number has been dialed, the user wears the device 100 at the level of his ear or another part of the body, so that the distance D_BODY decreases until it becomes zero.

[0078] Also, during the execution of step E30, the communication method also comprises a step E30 of comparing the distance D_BODY with a given threshold S_BODY. Said step E30 is implemented by a module M0D_C0MP equipping the control device 140, and is part of the control method.

[0079] No limitation is attached to the value of said threshold S_BODY, which can for example be of the order of ten centimeters or centimeters (eg 20 cm, 10 cm, 5 cm), or even of the order of ten millimeters or millimeters (eg 20 mm, 10 mm, 5 mm).

[0080] As illustrated by [Fig.3], said steps E20 and E30 are iterated as long as the distance D_BODY remains greater than the threshold S_BODY. Also, and as mentioned above, the user brings the device 100 to his ear, so that the distance D_BODY becomes zero from a moment, and therefore less than (or equal to) the threshold S_BODY, which triggers the execution of a step E40 of alternative selection of the first and second antennas 110, 120 to transmit the communication signal SIG_COM. Said step E40 is implemented by a selection module MOD_SELECT equipping the control device 140, and is part of the control method.

[0081] The alternative selection of the antennas 110, 120 for the transmission of the SIG_COM signal (i.e. their respective connection to a transmission chain using the switching means 130) is carried out so that the average DAS generated by each antenna 110, 120 over the time period T_DAS as well as considering the control distance D_DAS is lower than the threshold S_DAS.

[0082] As mentioned above, the selection of the antennas 110, 120 in accordance with step E40 comprises sending appropriate control signals to the switching means 130, so as to selectively connect said antennas 110, 120 to a transmission chain.

[0083] In the present embodiment, the transmission power used by a selected antenna 110, 120 (i.e. an antenna 110, 120 connected to a transmission chain by means of the switching means 130) is the maximum transmission power of the wireless communication device 100.

[0084] However, considering a maximum transmission power by each selected antenna only constitutes a variant of implementation of the invention. Nothing in fact excludes considering other variants in which the power emission of one or more antennas can be modulated during the different selections of said antenna(s), provided that the average DAS remains below the S_DAS threshold for said antenna(s).

[0085] Furthermore, in the present embodiment, the alternative selection of the antennas 110, 120 is carried out according to a fixed periodicity.

[0086] No limitation is attached to the value of this fixed periodicity as long as the average DAS remains below the S_DAS threshold for said antenna(s).

[0087] Alternatively, nothing precludes considering that the alternative selection of the antennas 110, 120 is implemented according to a dynamic periodicity (i.e. variable over time) as long as the average DAS remains below the threshold S_DAS for said antenna(s). For example, the alternative selection can be implemented according to a dynamic periodicity as a function of blocks of information to be transmitted, for example as a function of elements of radio signals to be transmitted still commonly called “bursts”, it being understood that the switching of the antennas is preferably carried out between two bursts in order to limit the loss of information to be transmitted.

[0088] It should be noted that the periods (or times) of selection of the antennas, as well as the powers used by each antenna can in particular be predetermined following laboratory test campaigns. These periods (or times) and powers are then recorded in a memory of the control device 140 (eg the non-volatile memory 144) to be used during the implementation of the control method.

[0089] [Fig.4] illustrates a specific example of application of the communication method of [Fig.3].

[0090] More particularly, [Fig.4] comprises two sub-figures 4a, 4b. Sub-figure 4a is a graph representing the temporal evolution (time t on the abscissa) of the average DAS (continuous line with crosses) as well as the instantaneous DAS (continuous line with circles) for the first antenna 110.

[0091] Sub-figure 4b, for its part, is a graph representing the temporal evolution (time t on the abscissa) of the average DAS (continuous line with crosses) as well as the instantaneous DAS (continuous line with circles) for the second antenna 120.

[0092] In the example of [Fig.4], the periodicity of selection of the first and second antennas 110, 120 is fixed and equal to 30 seconds (the second antenna 120 transmits during the first 30 seconds, then the first antenna 110 transmits during the following 30 seconds, and so on). Furthermore, said first and second antennas 110, 120, when selected, use the maximum transmission power of the wireless communication device 100 to transmit the SIG_COM signal.

[0093] As can be seen in each of the sub-figures 4a, 4b, the average DAS generated by each of the antennas 110, 120 is less than S_DAS (= 2 W / kg) after the T_DAS period (= 6 minutes). In other words, the alternative selection of the first and second antennas 110, 120 advantageously makes it possible to comply with the exposure limits while exploiting the maximum power of the wireless communication device 100, which makes it possible to ensure an excellent uplink rate, and therefore an excellent quality of service.

[0094] It should be noted that the communication method, and therefore a fortiori the control method, have been described considering that the wireless communication device 100 is equipped with two antennas 110, 120. However, and as already mentioned above, this number of antennas is not limiting of the invention, and nothing excludes considering more than two antennas, and therefore an alternative selection (step E40) between more than two antennas, as long as the average DAS generated by an antenna remains lower than the threshold S_DAS. In this case, the alternative selection is preferably carried out sequentially between the different antennas.

[0095] The control method has furthermore been described up to now by considering the implementation of steps E20 and E30 to evaluate the distance D_BODY and compare it to the threshold S_BODY, so as to condition the triggering of step E40 of alternative selection of the antennas 110, 120. Also, and on the one hand, it is understood that if the distance D_BODY becomes greater than the threshold S_BODY at a given moment, this can interrupt the alternative selection of the antennas 110, 120. Alternatively, the alternative selection is not interrupted even if the distance D_BODY becomes greater than the threshold S_BODY, for example for security reasons.

[0096] Furthermore, it is important to note that the implementation of steps E20 and E30 is optional within the meaning of the invention. In other words, the invention covers modes of implementation in which the alternative selection of the antennas is carried out independently of the value of the distance D_BODY.

[0097] Nothing also excludes considering modes of implementation in which the triggering of the alternative selection of the antennas is conditioned differently. For example, the control method may comprise a step of evaluating the transmission power used by an antenna currently in use to transmit the communication signal (eg the second antenna 120 in the example of [Fig. 3], given that it is the antenna connected to a transmission chain before the implementation of the control method). Therefore, the execution of the selection step is consecutive to the fact that said evaluated transmission power is greater than a given threshold.

[0098] Furthermore, although the evaluation of the distance D_BODY and that of the transmission power used by an antenna in use have been described above as two implementation alternatives, nothing excludes the possibility of considering still other modes in which these two aspects are combined. By way of example, in no way limiting, alternative antenna selection can be triggered if not only D_BODY is lower than the S_BODY threshold, but also if the current transmit power exceeds a given threshold.

[0099] Finally, the invention has been described up to now by considering that the alternative selection of the antennas notably comprises the generation of commands by the control device 140 and the transmission of these commands to the switching means 130. However, the selection can also consist of an identification of an antenna in a list of antennas, and the transmission of this identification information to means distinct from the control device 140 and capable of generating (on the basis of said identification information) an appropriate command intended for the switching means 130.

Claims

Claims

1. Method for controlling the operation of a wireless communication device (100) comprising a plurality of antennas (110, 120) configured to radiate spatially in distinct zones, said method comprising a step of alternative selection (E40) of said antennas to emit a communication signal, said selection being carried out so that the average specific absorption rate generated by each antenna over a given period of time as well as considering a given distance, called "control distance", between the communication device and the human body is less than a determined threshold.

2. Method according to claim 1, in which the number of antennas is strictly greater than two.

3. A method according to any one of claims 1 to 2, wherein the transmission power used by a selected antenna is the maximum transmission power of the wireless communication device.

4. Method according to any one of claims 1 to 3, said method comprising a step of evaluating (E20) a distance between the communication device and the human body, the execution of the selection step being subsequent to the fact that said evaluated distance is less than a given threshold.

5. Method according to any one of claims 1 to 4, said method comprising a step of evaluating the transmission power used by an antenna in use to transmit said communication signal, the execution of the selection step (E40) being subsequent to the fact that said evaluated transmission power is greater than a given threshold.

6. The method of claim 5, wherein the step of evaluating the transmission power comprises a set of evaluations of the transmission power by respectively considering a set of control distance values, said evaluated transmission power corresponding to the maximum transmission power obtained from said set of evaluations of the transmission power.

7. A method according to any one of claims 1 to 6, wherein the alternative selection of the antennas is carried out according to a fixed or dynamic periodicity.

8. A method according to any one of claims 1 to 7, wherein said control distance is zero.

9. A method according to any one of claims 1 to 8, wherein said time period is six minutes.

10. A method according to any one of claims 1 to 9, wherein the threshold of said average specific absorption rate is equal to 2 W / kg.

11. The method of any one of claims 1 to 10, wherein the maximum transmission power of the communication device is greater than or equal to 20 mW.

12. Computer program comprising instructions for implementing a control method according to any one of claims 1 to 11 when said program is executed by a computer.

13. A computer-readable recording medium having a computer program recorded thereon according to claim 12.

14. Control device (140) comprising means configured to implement a control method according to any one of claims 1 to 11.

15. A wireless communication device (100) comprising a plurality of antennas configured to radiate spatially in distinct areas and a control device according to claim 14.

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