Energy saving method and device for equipment capable of using at least two radio frequency bands

Abstract

Energy saving method and device for equipment capable of using at least two radio frequency bands The invention relates to an energy saving method for communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, the equipment comprising a first set of components necessary for transmission-reception in a first frequency band and a second set of components necessary for transmission-reception in a second frequency band, the method being implemented in the equipment and comprising: a partial or total reduction (E5) of an energy supply of at least one component of the first set, as a function of a measurement (E1) of a first value of the occupancy rate of the radio channel (AT5) of the first frequency band, and of a measurement (E2) of a second value of the occupancy rate of the radio channel (AT24) of the second frequency band.Figure for abstract: Figure 1.

Description

Title of the invention: Energy saving method and device for equipment capable of using at least two radio frequency bands 1. Field of the invention

[0001] The invention lies in the field of radio frequency communication equipment. In particular, it lies in the field of wireless local area networks or WLAN networks (for "Wireless Local Area Network" in English). Such WLAN networks typically use wireless transmission technology based on the IEEE 802.11 radio network standard and its evolutions, more commonly referred to as Wi-Fi (for "Wireless Fidelity" in English). 2. State of the prior art

[0002] With recent generations of Wi-Fi, in order to increase the available useful throughput, wireless LAN access equipment transmits and receives on several frequency bands. For example, an 802.1 lax generation Wi-Fi access point, also known as Wi-Fi 6, uses the 2.4 GHz and 5 GHz frequency bands. Compared to older generations that only used a single band (the 2.4 GHz band, in 802.11g, or the 5 GHz band in 802.1 lac), the energy consumption of such an access point is increased because the components necessary for each of the frequency bands must be powered. These components are, among others, the specialized integrated circuit, also called the Wi-Fi "chipset", the FEM amplification and filtering module, as well as the antenna(s), and may be specific to a frequency band.

[0003] Leaving the components of all frequency bands switched on represents a source of energy waste, when those of a single band are sufficient to ensure the transport of the flow rate actually required.

[0004] It is known to turn off certain components, in particular certain antennas, of a Wi-Fi access point when the flow rate measured on several bands falls below certain thresholds. For example, the antennas of band A will be turned off when the flow rate on this band falls below a threshold ThA, on the condition that there remains sufficient flow rate available on band B (flow rate measured below a threshold ThB) to switch the traffic from band A there.

[0005] Determining the ThA and ThB extinction thresholds is a difficult compromise between, on the one hand, ensuring permanent connectivity with a satisfactory flow rate, and on the other hand, not consuming energy unnecessarily.

[0006] It is also known to turn on the switched off antennas again when the flow rate measured on the band left active exceeds a certain threshold. For example, the antennas in band A will be turned back on when the throughput on band B exceeds a ThC threshold.

[0007] Determining the ThC re-ignition threshold is also a difficult compromise. With a threshold that is too high, there is a risk of saturating the on band and under-utilizing the off band. With a threshold that is too low, there is a risk of alternating too frequently between the on and off state of the antennas in this band, which is detrimental to the proper functioning of the access point and deteriorates the quality of service for the user.

[0008] Adjusting these throughput thresholds is also difficult due to many factors that differ from one user environment to another, such as residual throughput (throughput generated by sources other than the user himself), or interference. Leaving the user of an access point the responsibility of adjusting these thresholds himself is a solution that would only be suitable for a few expert users, and which is not suitable for the vast majority of users who are generally general public customers.

[0009] One of the aims of the invention is to remedy drawbacks of the state of the art. 3. Statement of the invention

[0010] The invention improves the situation by means of an energy-saving method for communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, the equipment comprising a first set of components necessary for transmission-reception in a first frequency band and a second set of components necessary for transmission-reception in a second frequency band, the method being implemented in the equipment and comprising:

[0011] a partial or total reduction of an energy supply of at least one component of the first set,

[0012] as a function of a measurement of a first value of the occupancy rate of the radio channel of the first frequency band, and of a measurement of a second value of the occupancy rate of the radio channel of the second frequency band.

[0013] The proposed solution is not based as in the prior art on a throughput measurement, but on a radio channel occupancy measurement. The radio channel occupancy, also called "airtime" in the Wi-Fi field, represents the time spent transmitting and receiving data, including the time taken by interference. A given radio channel occupancy value does not necessarily correspond to a single throughput value, because these two measurements do not represent the same thing. An advantage of using a radio channel occupancy rate measurement is that this parameter provides information on the time during which no resources are used on a radio interface, and therefore on the remaining available resources. The occupancy rate is therefore also information on a potential interface saturation. A radio interface is saturated when the quality of service is degraded and becomes unacceptable.

[0014] The flow rate, for its part, reflects a quantity of data transmitted or received over the measured period, for example an average over 3 adjacent periods of 10 seconds. The same flow rate can occupy the radio channel more or less depending on several parameters. These parameters are the attenuation of the radio signal between the equipment and the terminal, for example between the access point and the station in a Wi-Fi environment, and the physical characteristics such as the number of antennas, the type of radio technology, by the Wi-Fi version or generation, the channel width, etc.

[0015] The flow rate therefore does not give a good indication of the remaining available resources on a radio interface, unlike the occupancy rate of the radio channel.

[0016] A Wi-Fi access point, for example, includes components that continuously or repeatedly measure the occupancy rate in each of their frequency bands.

[0017] According to one aspect of the invention, the energy saving method also comprises a step of translating the first value into a translated value in the second frequency band, and where the reduction is triggered when the sum of the second value and the translated value is less than or equal to a first threshold.

[0018] Before switching traffic from a first frequency band to a second band, it is useful to predict the occupancy rate in the second band that this traffic would have. This avoids switching this traffic if the arrival band does not have sufficient capacity. The arrival band may also already have its own traffic and its own occupancy rate, to which the predicted occupancy rate would be added.

[0019] It is possible to translate the occupancy rate of the radio channel in one frequency band into an occupancy rate in another frequency band. This makes it possible to predict the effect, on the occupancy rate of the second band, of adding traffic from the first frequency band to the second frequency band.

[0020] Studies have made it possible to define radio channel occupancy thresholds from which an interface is said to be saturated, i.e. from which the quality of Wi-Fi service is degraded.

[0021] It is understood that the total occupancy rate predicted for the situation after switching must therefore be lower than the saturation threshold of the second frequency band.

[0022] According to one aspect of the energy saving method, the translated value is obtained by a function producing an occupancy rate value in the second frequency band from an occupancy rate value in the first frequency band.

[0023] Such a function may be a mathematical function, for example a function constant by interval, that is, a table or abacus matching occupancy rate values ​​or ranges of values ​​in the first band, with values ​​in the second frequency band.

[0024] According to one aspect of the energy saving method, the function uses an association between a value of a first plurality of values ​​in the first band and a value of a second plurality of values ​​in the second band, these pluralities of values ​​being stored in the equipment.

[0025] Thus, a simple correspondence table is previously stored in the equipment, for example a Wi-Fi access point, and the stored value which is closest to the measured value of the occupancy rate in the first frequency band is used to find its translation in the second frequency band.

[0026] This table is initially created theoretically, or empirically using laboratory tests. In both cases, it can be updated by downloading during a remote update of the local management software embedded in the equipment, for example the software called "firmware" in a Wi-Fi access point.

[0027] According to one aspect of the energy saving method, the first set of components comprises at least one element from among: • one or more antennas used for transmission and / or reception in the first frequency band, • an integrated circuit specialized in managing transmission-reception on the first frequency band.

[0028] To take an example in Wi-Fi, when a frequency band is made unavailable, for example after the switching off of the antenna(s) of this band on a Wi-Fi access point, the access point and the station(s) connected to it adapt and automatically concentrate their traffic on a remaining frequency band, according to their respective generation of Wi-Fi technology.

[0029] When traffic on the first frequency band is switched to the second frequency band, it is advantageous to turn off the antenna(s) of the first frequency band, or to reduce their energy consumption. Energy savings are thus achieved without disrupting the quality of service as perceived by the user of the access device.

[0030] If no antenna of the first frequency band is necessary, it may be advantageous, when possible, to reduce or eliminate the power supply of the integrated circuit, also called "chipset", specialized in the management of transmission-reception on the first frequency band.

[0031] For dual-band 2.4 GHz and 5 GHz Wi-Fi access points, for example, the expected gains on a Wi-Fi router for a typical home, compared to existing solutions based on a flow measurement, are a switching off of the 5 GHz interface sup additional hours per day. This corresponds to a few Wh, which must be multiplied by the number of domestic routers across a country, i.e. several million routers and therefore several million Wh which are not consumed.

[0032] According to one aspect of the invention, the energy saving method further comprises triggering a restoration of the energy supply to the first set of components, when a measurement of a third value of the occupancy rate of the radio channel of the second frequency band is greater than or equal to a second threshold.

[0033] When the first frequency band is unused or underused, the occupancy rate of the radio channel on the second frequency band may increase to the point of approaching the saturation threshold, if for example the traffic increases too much. In order to avoid this, an occupancy rate threshold lower than the saturation threshold is set. Beyond this threshold, the power supply to the components of the first frequency band is restored. In Wi-Fi for example, the access point and the station(s) connected to it then adapt and automatically distribute their traffic over the available frequency bands, according to their respective generation of Wi-Fi technology. With this return to the initial situation where both frequency bands are used, the quality of service is no longer likely to deteriorate.

[0034] Thus, if one or more antennas of the first frequency band were switched off to save energy, they are switched back on in order to avoid a degradation of QoS following too great an increase in the occupancy rate in the second frequency band.

[0035] According to one aspect of the energy saving method, the first threshold is strictly lower than the second threshold.

[0036] Thus, it is possible to avoid too rapid an alternation between reduction and increase, in other words between switching off and switching on the antennas of the first frequency band, also known as the "ping-pong effect", which would harm the operation of the equipment, for example the Wi-Fi access point, as well as the operation of the terminals, for example Wi-Fi stations, which are connected to it, sometimes on the first frequency band, sometimes on the second, with times of passage from one to the other band which may be significant and have a negative impact for the user(s) of the terminals. The greater the difference delta between the two thresholds, the more this danger is avoided. But this delta must not be too large, at the risk of preventing any reduction or switching off of power supply and therefore any energy saving.

[0037] The different aspects of the energy saving method which have just been described can be implemented independently of one another or in combination with one another.

[0038] The invention also relates to an energy saving device in equipment communication device capable of using at least two radio frequency bands to exchange data with at least one terminal, comprising a first set of components necessary for transmission-reception in a first frequency band and a second set of components necessary for transmission-reception in a second frequency band, the device further comprising a processor and a memory coupled to the processor with instructions intended to be executed by the processor for:

[0039] a partial or total reduction of a power supply of at least one component of the first assembly, as a function of a measurement of a first value of the occupancy rate of the radio channel of the first frequency band, and of a measurement of a second value of the occupancy rate of the radio channel of the second frequency band.

[0040] This device, capable of implementing in all its embodiments the energy saving method which has just been described, is intended to be implemented in a Wi-Fi access point, or in a base station of a cellular network.

[0041] The invention also relates to a computer program comprising instructions which, when these instructions are executed by a processor, cause the latter to implement the steps of the energy saving method, which has just been described.

[0042] The invention also relates to an information medium readable by communication equipment capable of using at least two radio frequency bands, and comprising instructions of a computer program as mentioned above.

[0043] The above-mentioned program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0044] The above-mentioned information carrier may be any entity or device capable of storing the program. For example, a carrier may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means.

[0045] Such a storage means may for example be a hard disk, a flash memory, etc. On the other hand, an information carrier may be a transmissible carrier such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. A program according to the invention may in particular be downloaded from a network such as the Internet.

[0046] Alternatively, an information carrier may be an integrated circuit in which a program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question. 4. Presentation of figures

[0047] Other advantages and characteristics of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given as a simple illustrative and non-limiting example, and the appended drawings, among which:

[0048] [Fig-1] [Fig. 1] presents an example of implementation of the energy saving method, according to an embodiment of the invention,

[0049] [Fig.2] [Fig.2] shows an example of the structure of an energy saving device, according to one aspect of the invention.

[0050] 5. Detailed description of at least one embodiment of the invention

[0051] In the remainder of the description, examples of several embodiments of the invention are presented based on the IEEE 802.11ax standard also called Wi-Fi 6, which allows the use of two frequency bands, one around 5GHz and the other around 2.4 GHz, called 5 GHz bands and 2.4 GHz band respectively.

[0052] The invention, however, also applies to equipment based on other versions of the IEEE 802.11 standards, particularly those allowing the use of at least two distinct frequency bands. The invention also applies to any wireless technology other than Wi-Fi allowing the use of at least two distinct frequency bands, such as, for example, the radio technologies of 4G or 5G cellular networks.

[0053] [Fig.l] presents an example of implementation of the energy saving method, according to one embodiment of the invention.

[0054] In this embodiment, the 5 GHz band is called the first frequency band, and the 2.4 GHz band is called the second frequency band. The device implementing the method is for example a Wi-Fi access point, to which one or more terminals can be connected, called Wi-Fi stations. The data traffic in question designates the traffic exchanged, in transmission or reception, by the access point with the station(s).

[0055] The access point includes components such as antennas, chipsets, firmware. A chipset is an integrated circuit specialized in certain functions of the access point, such as managing transmission and reception on a frequency band. Firmware is software stored in the access point, often modifiable remotely, the purpose of which is to control certain components.

[0056] Some of these components are dedicated to one of the frequency bands, such as the antennas and the chipset, and are a source of energy consumption.

[0057] The components dedicated to the first band form a first set of components, and those dedicated to the second band form a second set of components.

[0058] During a step E1 of the method illustrated in [Fig.l], the airtime AT5, i.e. the occupancy rate of the radio channel on the first 5 GHz frequency band, is calculated, for example by the chipset of the access point dedicated to 5 GHz.

[0059] At the same time, during a step E2, the airtime AT24, i.e. the occupancy rate of the radio channel on the second 2.4 GHz frequency band, is calculated, for example by the chipset of the access point dedicated to 2.4 GHz.

[0060] The airtime of a frequency band is the percentage of time the radio channel is occupied. This channel occupation is the sum of the times spent transmitting and / or receiving data packets and / or spent listening to non-decodable signals (for example, signals whose intensity does not allow transmission, also called interference). In one embodiment, the following types are measured periodically by the access point on this frequency band, for example every 100 ms (called beacon time in the IEEE 802.11 standard): • tx: percentage of time taken by Wi-Fi packets emitted by the access point • inbss: percentage taken by received Wi-Fi packets intended for the access point • obss: percentage taken by Wi-Fi packets received but not intended for the access point • nothandled: percentage taken by undecodable Wi-Fi packets or taken by unidentifiable packets or by a signal level that is too high • txop: percentage of time remaining available for the transmission or reception of Wi-Fi packets by the access point; txop is deduced from the above

[0061] It is understood that with the obss and nothandled types, the airtime takes into account interference in the frequency band, and does not only measure the resulting occupation of useful traffic, i.e. that transmitted by, or intended for, the access point.

[0062] During a step E3, the airtime AT5, measured in the 5 GHz band, is translated into a new TR5 value in the 2.4 GHz band. Several techniques are possible for performing this translation: by a mathematical formula representing a continuous function, or using charts. If the translation uses charts, they can be filled with values ​​in several ways: by determining the translated values ​​theoretically, or empirically. An chart is also a mathematical function but it is not necessarily continuous. It is, for example, a constant function per interval, i.e. matching ranges of occupancy rate values ​​between the two frequency bands.

[0063] In the case of a theoretical abacus, the signal-to-noise ratio or SNR can be assumed to be either identical or different across the two frequency bands.

[0064] When the assumption is made that the SNR is identical on the two frequency bands, the theoretical physical throughput PhyRate24 in the 2.4 GHz band is obtained as a function of the SNR measured in the 5 GHz band. More precisely, the useful throughput PhyPL5 in 5 GHz band is obtained by means of a first theoretical abacus in 5 GHz, as a function of the SNR. Similarly, the useful rate PhyRate24 in 2.4 GHz band is obtained by means of a second theoretical abacus in 2.4 GHz, as a function of the same SNR. Then the value of the translated airtime TR5 is obtained according to the following formula:

[0065] TR5 = PhyPL5 * coeff / PhyRate24

[0066] where coeff is a correction coefficient depending on the Wi-Fi version of the access point. For example, for Wi-Fi generation 6, coeff = 1.3.

[0067] When the assumption is made that the SNR is different on the two frequency bands, the formula for obtaining the airtime TR5 remains the same, but the theoretical physical throughput PhyRate24 in the 2.4 GHz band is obtained as a function of the estimated SNR in the 2.4 GHz band. Different estimation methods are possible. For example, in the case of stationary white Gaussian noise, random signal theory stipulates that the noise power density is identical at all frequencies. Consequently, this density is proportional to the bandwidth over which the power is calculated. With a bandwidth in 2.4 GHz being half that of 5 GHz, it is sufficient to subtract approximately 3 dB from the SNR measured in 5 GHz.

[0068] With an empirical chart, airtime measurements must be carried out beforehand with different types of stations, different distances from the access point (attenuations), different useful rates, both on the 5 GHz band and on the 2.4 GHz band. Unlike theoretical charts, such empirical charts require test measurements to be carried out before deploying a Wi-Fi access point, but they are more precise. The greater the number and diversity of test measurements, the greater this precision.

[0069] The charts giving TR5 as a function of AT5 are stored in memory in the access point, and can be updated remotely as needed, for example when changing the Wi-Fi version of the access point, or to increase the accuracy of the charts after running additional tests.

[0070] During a step E4, the sum of the translated airtime TR5 and the airtime AT24 is compared to a threshold SL. This sum represents the total airtime that the 2.4 GHz band must be able to support if the traffic in the 5 GHz band is added to the existing traffic in the 2.4 GHz band. This airtime must not get too close to a so-called saturation threshold on the 2.4 GHz band. A communication channel is said to be saturated, or congested, when the traffic it supports becomes excessive for its capacities and encounters slowdowns or blockages. The quality of service, or QoS, then becomes unacceptable. The threshold SI is therefore strictly lower than this saturation threshold in order to avoid reaching an unacceptable QoS.

[0071] If TR5 + AT24 < S1,

[0072] this means that it is possible to ensure that the traffic in the 5 GHz band switches to the 2.4 GHz band, without harming the QoS. Step E4 is then followed by step E5. Otherwise, this means that such a switch is not possible without harming the QoS, and the method returns to steps E1 and E2. The frequency of this cycle is for example 10 or 20 seconds, which makes it possible to smooth the calculation of TR5 over this same period, and to obtain a more reliable result because it eliminates unrepresentative extreme point values.

[0073] During a step E5, the power supply of one or more components necessary for transmission-reception in the 5 GHz band is reduced (illustrated by DWN5 in [Fig.l]). For example, it is particularly advantageous to completely switch off the antenna(s) dedicated to the 5 GHz band, since their consumption can exceed 2 W / h. The action of switching off these antennas has the effect of triggering the switch to the 2.4 GHz band of the traffic which was transmitted on the 5 GHz band, both in the access point and in the station(s) connected to it. As long as this situation persists, the energy consumed by the 5 GHz antennas is saved.

[0074] This energy saving situation can last as long as the 2.4 GHz band is not saturated or does not approach saturation. In order to verify this, during a step E6, the airtime AT24, i.e. the traffic occupancy rate on the second 2.4 GHz frequency band, is calculated, in a similar manner to step E2.

[0075] During a step E7, the airtime AT24 is compared to a threshold S2. S2 is a threshold close to the saturation threshold but lower than it, so as not to reach it.

[0076] If AT24 > S2,

[0077] this means that the 2.4 GHz band is dangerously close to saturation and that the resources of the 5 GHz band must be restored to deal with a possible increase in the AT24 airtime. Step E7 is then followed by step E8. Otherwise, this means the situation described above, where the energy required by the components of the 5 GHz band is saved, can continue, and the method returns to step E6. The frequency of this cycle can be the same as above, or be a little more reduced, for example 5 or 10 seconds, which allows responsiveness to peaks.

[0078] During a step E8, the power supply of one or more components necessary for transmission-reception in the 5 GHz band is restored (illustrated by UP5 in [Fig.l]). For example, if the antenna(s) dedicated to the 5 GHz band were switched off, they are then switched back on. The action of switching these antennas back on is accompanied by the switching to the 5 GHz band of part of the traffic which was transmitted by the access point on the 2.4 GHz band, in order to rebalance its load on the two bands. The stations connected to it readjust and also transmit again on the 5 GHz band.

[0079] The method then returns to steps E1 and E2. It is understood that the thresholds S1 and S2 must be set so as not to too frequently alternate between the two situations, 5 GHz antennas on and off, which would also harm QoS, without achieving substantial energy savings. In order to avoid this so-called ping-pong effect, for example for the embodiment described above based on Wi-Fi 6, a value of SI could be 15 points below the congestion threshold of the occupancy rate of the radio channel of the 2.4 GHz frequency band, and a value of S2 could be 5 points below this congestion threshold. The difference between SI and S2 is therefore 10 percentage points in this example.

[0080] [Fig.2] shows an example of the structure of an energy saving device for communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, according to one aspect of the invention.

[0081] The device 100 implements the energy saving method for communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, different embodiments of which have just been described.

[0082] Such a device 100 can for example be implemented in a Wi-Fi access point, or in a base station of a cellular network.

[0083] For example, the device 100 comprises at least two sets of components necessary for transmission-reception in a respective frequency band, for example a first Comp5GHz set for the 5GHz band and a second Comp24GHz set for the 2.4GHz band. Each set of Comp5GHz or Comp24GHz components comprises for example one or more antennas and a chipset.

[0084] The device 100 also comprises a processing unit 130, equipped for example with a microprocessor pP, and controlled by a computer program 110, stored in a memory 120 and implementing the energy saving method according to the invention. At initialization, the code instructions of the computer program 110 are for example loaded into a RAM memory, before being executed by the processor of the processing unit 130.

[0085] Such a memory 120 and such a processor of the processing unit 130 are capable of, and configured to: • a partial or total reduction of a power supply of at least one component of the first Comp5GHz assembly, based on a measurement of a first value of the occupancy rate of the radio channel of the first frequency band, and a measurement of a second value of the occupancy rate of the radio channel of the second frequency band.

[0086] The entities described and included in the devices described in relation to [Fig.2] may be hardware or software. [Fig.2] illustrates only one way by particular, among several possible, to carry out the method detailed above, in relation to [Fig.l]. Indeed, the technique of the invention is carried out indifferently on a reprogrammable computing machine (a PC computer, a DSP processor or a microcontroller) executing a program comprising a sequence of instructions, or on a dedicated computing machine (for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module), or on a virtual container or a virtual machine, hosted in a reprogrammable computing machine or in a computing cloud.

[0087] In the case where the invention is implemented on a reprogrammable computing machine, the corresponding program (i.e. the sequence of instructions) may be stored in a removable storage medium (such as for example a USB key, a floppy disk, a CD-ROM or a DVD-ROM) or not, this storage medium being partially or totally readable by a computer or a processor.

[0088] The exemplary embodiments of the invention which have just been presented are only some of the possible embodiments. In particular, in the case of communication equipment operating on a single frequency band, the method can also be applied to divisions of this band, the roles of first and second frequency bands being played by sub-bands of reduced width within this single frequency band.

Claims

Claims

1. Energy saving method for communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, the equipment comprising a first set of components (Comp5GHz) necessary for transmission-reception in a first frequency band and a second set of components (Comp24GHz) necessary for transmission-reception in a second frequency band, the method being implemented in the equipment and comprising: a partial or total reduction (E5) of a power supply of at least one component of the first set, as a function of a measurement (El) of a first value of the occupancy rate of the radio channel (AT5) of the first frequency band, and of a measurement (E2) of a second value of the occupancy rate of the radio channel (AT24) of the second frequency band.

2. Energy saving method according to claim 1, comprising a step of translating (E3) the first value (AT5) into a translated value (TR5) in the second frequency band, and where the reduction (E5) is triggered (E4) when the sum of the second value (AT24) and the translated value (TR5) is less than or equal to a first threshold (SI).

3. An energy saving method according to claim 2, wherein the translated value (TR5) is obtained by a function producing an occupancy rate value in the second frequency band from an occupancy rate value in the first frequency band.

4. A method of saving energy according to claim 3, wherein the function uses an association between a value of a first plurality of values ​​in the first band and a value of a second plurality of values ​​in the second band, these pluralities of values ​​being stored in the communication equipment.

5. Energy saving method according to claim 1, where the first set of components comprises at least one element from: • one or more antennas used for transmission and / or reception in the first frequency band, • an integrated circuit specialized in the management of transmission-reception on the first frequency band.

6. Energy saving method according to claim 2, further comprising a triggering (E7) of a restoration (E8) of the power supply of the first set of components, when a measurement (E6) of a third value of the occupancy rate of the radio channel (AT24) of the second frequency band is greater than or equal to a second threshold (S2).

7. Energy saving method according to claim 6, where the first threshold (SI) is strictly lower than the second threshold (S2).

8. Device (100) for energy saving in communication equipment capable of using at least two radio frequency bands to exchange data with at least one terminal, comprising a first set of components (Comp5GHz) necessary for transmission-reception in a first frequency band and a second set of components (Comp24GHz) necessary for transmission-reception in a second frequency band, the device further comprising a processor (130) and a memory (120) coupled to the processor with instructions intended to be executed by the processor for: a partial or total reduction of a power supply of at least one component of the first set, as a function of a measurement of a first value of the occupancy rate of the radio channel (AT5) of the first frequency band, and a measurement of a second value of the occupancy rate of the radio channel (AT24) of the second frequency band.

9. A computer program (110), comprising instructions which, when these instructions are executed by a processor, cause the latter to implement the steps of the energy saving method according to claim 1.

10. Information medium readable by communication equipment capable of using at least two radio frequency bands, and comprising instructions of a computer program (110) according to claim 9.

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