Methods and devices using ue-specific thresholds for selecting a low power operating mode

Abstract

The present disclosure relates to methods and devices for saving energy on a user equipment side of a wireless communication system.

Description

Methods and devices using UE-specific thresholds for selecting a low power operating modeTechnical field

[0001] The present disclosure relates to wireless communication systems and relates more specifically to methods and devices for saving energy on a user equipment, UE, side of the wireless communication system.Background

[0002] To reduce energy consumption, extended discontinuous reception, eDRX, has been introduced in 3GPP (Third Generation Partnership Project) wireless communication systems. Basically, in eDRX, the UE periodically goes to sleep for an asleep duration during which a physical downlink control channel, PDCCH, is not monitored before waking up for an awake duration to monitor the PDCCH for possible downlink data. The amount of energy that can be saved depends on how long and how often the UE remains asleep. Of course, the longer the UE remains asleep, the greater the amount of energy saved. However, increasing the asleep duration comes with increased latency, which makes eDRX not suitable for latency-critical use cases.

[0003] To enhance energy savings without sacrificing latency in 5G or New Radio (NR) wireless communication systems, 3GPP is willing to define a new architecture for UEs (see e.g., the technical report TR 38.869).

[0004] Basically, current UEs need to periodically wake up once per eDRX cycle, which dominates the energy consumption in periods with no signaling or data traffic. If UEs were able to wake up only when they are triggered, e.g., paging, energy consumption could be dramatically reduced. As investigated by 3GPP, this is achieved by providing the UE with both a main radio, MR, unit, and a low power wake-up receiver, LP-WUR.

[0005] Basically, the MR unit corresponds to the 5G NR wireless communication unit, and the LP-WUR corresponds to a wireless communication unit that is used to monitor a wakeup signal with low power consumption. Once the wake-up signal is detected, the LP-WUR can trigger the MR unit which can transition from a low power state to an active state.

[0006] The active state corresponds to any state in which the MR unit can exchange data with a radio access network, RAN, of the wireless communication system without being triggered by the LP-WUR. Hence, a MR unit that is awake is in the active state. Also, a MR unit that is asleep but wakes-up periodically (e.g., eDRX) without being triggered by a LP- WUR is also in the active state.

[0007] The low power state corresponds to a state in which the MR unit cannot exchange data with the RAN without being triggered by the LP-WUR. For instance, the low power state corresponds to the MR unit being always asleep. However, since the MR unit doesnot have to wake-up periodically in the low power state, the MR unit may be even more deeply asleep than in current UEs and may even be turned off since the LP-WLIR can be used to turn the MR unit on.

[0008] By “low power” state, we mean that the mean power consumption of the MR unit in the low power state is lower than (and preferably significantly lower than, e.g., ten times or even a hundred times lower than) the mean power consumption of the MR unit in the active state.

[0009] By “low power” wake-up receiver, we mean that the LP-WLIR is used for receiving a wake-up signal while the MR unit is in the low power state. Of course, the monitoring of the wake-up signal should be done with a low power consumption, and the mean power consumption of the LP-WLIR should therefore be lower than (and preferably significantly lower than, e.g., ten times or even a hundred times lower than) the mean power consumption of the MR unit when it is awake.

[0010] Hence, the energy consumption is reduced by placing the MR unit in the low power state (e.g., turned off). The MR unit is not required to wake-up periodically and may wakeup only when triggered by the LP-WLIR. Since the LP-WLIR may monitor the wake-up signal continuously, or at least frequently, the MR unit can be awakened by the LP-WLIR at any time, thereby reducing latency compared to e.g., eDRX.

[0011] While the specifics of the LP-WLIR and of the wake-up signal are still to be defined, the fact that the LP-WLIR should be able to detect the wake-up signal with a low power consumption may imply that, for a given base station, BS, of the RAN, the coverage achievable for the wake-up signal, monitored by the LP-WLIR, may be smaller than the coverage (a.k.a. cell) achievable for the PDCCH, monitored by the MR unit. Hence, the LP- WUR of a UE at the border of the cell may not always be able to detect the wake-up signal transmitted by the BS.Summary

[0012] The present disclosure aims at improving the situation. In particular, the present disclosure aims at addressing at least some of the limitations of the prior art discussed above. In particular, the present disclosure aims at proposing a solution for enabling each UE to deactivate the reception of the wake-up signal when this UE might not be able to detect it.

[0013] For this purpose, the present disclosure proposes to use a minimum reception level threshold above which the expected reception level of the wake-up signal should be to keep monitoring the wake-up signal. In turn, reception of the wake-up signal should be deactivated if the expected reception level of the wake-up signal falls below the minimum reception level threshold. More specifically, it is proposed to adjust the minimum reception level threshold to each UE, to account for the specific wake-up signal detection capabilitiesof the LP-WUR of each UE.

[0014] According to a first aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a wireless device of the wireless communication system, wherein the wireless device comprises a main radio, MR, unit, configured to exchange data with a radio access network, RAN, of the wireless communication system, and a low-power wake-up receiver, LP-WUR, configured to detect a wake-up signal transmitted by the RAN, wherein the wireless device comprises at least two operating modes which include a normal operating mode and a low-power operating mode, wherein: in the normal operating mode, the MR unit is in an active state, in the low-power operating mode, the MR unit is in a very low power state and the LP-WUR is configured to trigger a transition to the normal operating mode in response to detecting a wake-up signal transmitted by the RAN, wherein the method comprises: receiving, from the RAN, an indication of a minimum reception level threshold, estimating a reception level representative of an expected reception level, by the LP-WUR, of the wake-up signal transmitted by the RAN, selecting an operating mode of the wireless device by comparing the estimated reception level with the minimum reception level threshold.

[0015] In some embodiments, the method according to the first aspect can further comprise one or more of the following optional features, considered either alone or in any technically possible combination.

[0016] In some embodiments of the method according to the first aspect, the indication of the minimum reception level threshold is received by the wireless device in a radio resource control, RRC, connected state, with an indication to transition from the RRC connected state to an RRC inactive state.

[0017] In some embodiments of the method according to the first aspect, the indication of the minimum reception level threshold is received in an RRC release message.

[0018] In some embodiments of the method according to the first aspect, the low-power operating mode is selected in response to the estimated reception level being greater than the minimum reception level threshold.

[0019] In some embodiments of the method according to the first aspect, the normal operating mode is selected in response to the estimated reception level being lower than the minimum reception level threshold.

[0020] In some embodiments, the method according to the first aspect comprises informing the RAN that the reception of the wake-up signal is not possible at the wireless device inresponse to the estimated reception level being lower than the minimum reception level threshold.

[0021] In some embodiments of the method according to the first aspect, the informing the RAN that the reception of the wake-up signal is not possible at the wireless device is done by using assistance information, for example by using a small data transmission, SDT, procedure.

[0022] According to a second aspect, the present disclosure relates to a wireless device comprising at least one memory and at least one processor configured to carry out a method according to any one of the embodiments of the first aspect.

[0023] According to a third aspect, the present disclosure relates to a user equipment, UE, comprising a wireless device according to any one of the embodiments of the present disclosure.

[0024] According to a fourth aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a base station, BS, of a radio access network, RAN, of the wireless communication system, wherein the BS is configured to exchange data with a wireless device which comprises a main radio, MR, unit and a low-power wake-up receiver, LP-WLIR, wherein the LP-WLIR is configured to detect a wake-up signal transmitted by the BS and to trigger a transition of the MR unit from a very low power state to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the method comprises: determining a minimum reception level threshold for the wireless device, transmitting an indication of the minimum reception level threshold to the wireless device.

[0025] In some embodiments, the method according to the fourth aspect can further comprise one or more of the following optional features, considered either alone or in any technically possible combination.

[0026] In some embodiments of the method according to the fourth aspect, the minimum reception level threshold is determined based on information received from the wireless device.

[0027] In some embodiments of the method according to the fourth aspect, the minimum reception level threshold is determined based on information representative of a receiver sensitivity of the wireless device.

[0028] In some embodiments of the method according to the fourth aspect, the indication of the minimum reception level threshold is included in a radio resource control, RRC, release message.

[0029] In some embodiments, the method according to the fourth aspect comprises deactivating the transmission of the wake-up signal to the wireless device in response toreceiving, from the wireless device, an indication that the reception of the wake-up signal is not possible.

[0030] According to a fifth aspect, the present disclosure relates to a base station, BS, comprising at least one memory and at least one processor configured to carry out a method according to any one of the embodiments of the fourth aspect.

[0031] According to a sixth aspect, the present disclosure relates to a wireless communication system comprising at least one base station according to any one of the embodiments of the present disclosure and at least one user equipment according to any one of the embodiments of the present disclosure.

[0032] According to a seventh aspect, the present disclosure relates to a computer program product comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method for exchanging data according to any one of the embodiments of the present disclosure. The computer program product can use any programming language, and can be in the form of source code, object code, or in any intermediate form between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0033] According to an eighth aspect, the present disclosure relates to a (non-transitory) computer-readable storage medium comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method for transmitting control messages according to any one of the embodiments of the present disclosure.Brief description of figures

[0034] The invention will be better understood upon reading the following description, given as an example that is in no way limiting, and made in reference to the figures which show:Figure 1 : a schematic representation of an example of wireless communication system comprising a BS and UEs,Figure 2: a schematic representation of an example of a wireless device, Figure 3: a schematic representation of an example of a BS,Figures 4 and 5: flow charts illustrating examples of methods for exchanging data implemented by a BS and a wireless device of a UE, respectively.

[0035] In these figures, references identical from one figure to another designate identical or analogous elements. For reasons of clarity, the elements shown are not to scale, unless explicitly stated otherwise.Detailed description

[0036] The detailed description set forth below, with reference to the figures, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. For instance, although 3GPP terminology, from e.g., 5G NR, may be used in this disclosure to exemplify embodiments herein, this should not be seen as limiting the scope of the present disclosure.

[0037] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. Also, the order of steps of any methods disclosed herein, in particular in the figures, is provided only for illustration purposes and is not meant to limit the present disclosure which may be applied with the same steps executed in a different order and / or with all or part of the steps executed in parallel or jointly, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Also, in a figure, steps represented surrounded by a dashed line are to be considered as optional for the embodiment represented in this figure. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0038] Figure 1 represents schematically an example of wireless communication system, which may be for example a 5G NR wireless communication system. More specifically, figure 1 represents a RAN of the wireless communication system, which is used exchange data with UEs via radio signals. For example, the RAN may send data to the UEs (downlink, DL), for instance data received from a core network (CN, not represented in the figures). The RAN may also receive data from the UEs (uplink, UL), which data may be forwarded to the CN.

[0039] In the example illustrated by figure 1 , the RAN comprises one base station, BS, 30. Of course, the RAN may comprise more than one BS 30 to increase the coverage of the wireless communication system. Each of these BSs may be referred to as NB, eNodeB (or eNB), gNodeB (or gNB, in the case of a 5G NR wireless communication system), an access point or the like, depending on the wireless communication standard(s) implemented.

[0040] In the example illustrated by figure 1 , two UEs 20-1 and 20-2 are represented. The UEs 20-1 and 20-2 are located in a coverage 31 (a.k.a. cell) of the BS 30. The coverage 31 of the BS 30 corresponds basically to the area in which UEs can decode a PDCCH transmitted by the BS 30.

[0041] Figure 2 represents schematically an example of a wireless device 25 suitable for implementing any method, discussed in the present disclosure, performed at a UE. Basically, the wireless device 25 corresponds to an apparatus that provides wireless connectivity with the RAN of the wireless communication system, and that can be used to exchange data with said RAN.

[0042] Such a wireless device 25 may be included in a UE 20, as illustrated by figure 2. The UE 20 may for instance be a cellular phone, a wireless modem, a wireless communication device, a handheld device, a laptop computer, or the like. The UE 20 may also be an Internet of Things (loT) equipment, like a wireless camera, a smart sensor, a smart meter, smart glasses, a vehicle (manned or unmanned), a global positioning system device, etc., or any other equipment that may run applications that need to exchange data with remote recipients, via the wireless device 25.

[0043] As illustrated by figure 2, the wireless device 25 comprises one or more processors 250 and one or more memories 251. The one or more processors 250 may include for instance a central processing unit (CPU), a digital signal processor (DSP), a field- programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc. The one or more memories 251 may include any type of computer readable volatile and nonvolatile memories (magnetic hard disk, solid-state disk, optical disk, electronic memory, etc.). The one or more memories 251 may store a computer program product 252, in the form of a set of program-code instructions to be executed by the one or more processors 250 to implement all or part of the steps of a method for exchanging data, performed at a UE’s side, according to any one of the embodiments disclosed herein.

[0044] As illustrated by figure 2, the wireless device 25 comprises also a main radio, MR, unit 253, and a low power wake-up signal receiver, LP-WUR, 254.

[0045] As discussed above, the MR unit 253 corresponds to a main wireless communication unit of the wireless device 25, used for exchanging data with BSs 30 of the RAN using radio signals. The MR unit 253 may implement one or more wireless communication protocols, and may for instance be a 3G, 4G, 5G, NR, WiFi, WiMax, etc. transceiver or the like. In preferred embodiments, the MR unit 253 corresponds to a 5G NR wireless communication unit.

[0046] The LP-WUR 254 corresponds to a secondary wireless communication unit of the wireless device 25, that is used to monitor a wake-up signal, transmitted by BSs 30 of the RAN, with low power consumption. The wake-up signal may take any form enabling it to be detected with low power consumption. Non-limitative examples for the wake-up signal and the LP-WUR 254 are provided in the technical report TR 38.869. It should be noted that, in some examples, the wake-up signal can even be a specific 5G NR signal, for instance using a low-level modulation and coding scheme, MCS, in which case the LP-WUR 254 canconsist in the components of a 5G NR wireless communication unit strictly required to be able to detect such a specific 5G NR signal.

[0047] As discussed above, the purpose of the LP-WLIR 254 is mainly to monitor and detect a (DL) wake-up signal transmitted by the RAN of the wireless communication system. As such, the LP-WLIR 254 may be only unidirectional, i.e. , with only receiving capabilities (DL) and no transmitting capabilities (UL). However, in some examples, the LP-WLIR 254 may also have transmitting capabilities, such that it can also transmit (UL) data to the RAN.

[0048] The wireless device 25 is adapted to be operated in at least two operating modes which include a normal operating mode and a low power operating mode: in the normal operating mode, the MR unit 253 is in an active state, in the low power operating mode, the MR unit 253 is in a low power state and the LP-WUR 254 is configured to trigger a transition to the normal operating mode in response to detecting a wake-up signal transmitted by the RAN.

[0049] As discussed above, the active state corresponds to any state in which the MR unit253 can exchange data with the RAN without being triggered by the LP-WUR. Hence, a MR unit 253 that is awake is in the active state. Also, a MR unit 253 that is asleep but wakesup periodically (e.g., eDRX) without being triggered by a LP-WUR 254 is also in the active state.

[0050] The low power state corresponds to a state in which the MR unit 253 cannot exchange data with the RAN without being triggered by the LP-WUR 254. For instance, the low power state corresponds to the MR unit 253 being always asleep. However, since the MR unit 253 does not have to wake-up periodically in the low power state, thanks to the LP- WUR 254, the MR unit 253 may be ultra-deeply asleep and may even be turned off since the LP-WUR 254 can be used to turn the MR unit 253 on.

[0051] It should be noted that, in some examples, the LP-WUR 254 may also be configured to trigger the MR unit 253 when other conditions are verified. For example, the LP-WUR254 may be configured to trigger the MR unit 253 if a predetermined timer has expired without detecting a wake-up signal. Such a timer may be used to ensure that the wireless device 25 can return to the active state when e.g., the wireless device 25 has moved out of the coverage of the wake-up signal. Of course, the duration of this timer should be sufficiently high to ensure that the MR unit 253 can remain in the low power state over long periods.

[0052] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0053] As illustrated by figure 3, the BS 30 comprises one or more processors 300 and one or more memories 301. The one or more processors 300 may include for instance a central processing unit (CPU), a digital signal processor (DSP), a field-programmable gate array(FPGA), an application specific integrated circuit (ASIC), etc. The one or more memories 301 may include any type of computer readable volatile and non-volatile memories (magnetic hard disk, solid-state disk, optical disk, electronic memory, etc.). The one or more memories 301 may store a computer program product 302, in the form of a set of programcode instructions to be executed by the one or more processors 300 to implement all or part of the steps of a method for exchanging data, performed at the RAN’s side, according to any one of the embodiments disclosed herein.

[0054] As illustrated by figure 3, the BS 30 comprises also a wireless communication unit 303, configured to exchange data with UEs 20 using radio signals, and more specifically with MR units 253 of wireless devices 25 included in these UEs 20. The wireless communication unit 303 may for instance be a 3G, 4G, 5G, NR, WiFi, WiMax, etc. transceiver or the like. In preferred embodiments, the wireless communication unit 303 of the BS 30 corresponds to a 5G NR transceiver.

[0055] As illustrated by figure 3, the BS 30 comprises also a wake-up signal transmitter, WUT, 304, configured to transmit wake-up signals to UEs having a wireless device 25 which includes a LP-WUR 254. In the example illustrated by figure 3, the WUT 304 is represented as separate from the wireless communication unit 303. However, the WUT 304 may also be included in the wireless communication unit 303, e.g., if the wireless communication unit 303 is a 5G NR transceiver and if the wake-up signal is a specific 5G NR signal.

[0056] As discussed above for the LP-WUR 254, the purpose of the WUT 304, if separate from the wireless communication unit 30, is mainly to transmit a (DL) wake-up signal. As such, the WUT 304 may be only unidirectional, i.e. , with only transmitting capabilities (DL) and no receiving capabilities (UL). However, in some examples, the WUT 304 may also have receiving capabilities, such that it can also receive (UL) data from a LP-WUR 254 of a UE 20.

[0057] As illustrated by figure 3, the BS 30 may comprise also a network communication unit 305, configured to exchange data with other base stations of the RAN and / or with the CN. The network communication unit 305 may support one or more suitable communication protocols, which may be wired (including optical) and / or wireless.

[0058] As discussed above, the coverage 31 of the BS 30 may be broader than the coverage achievable for a wake-up signal transmitted by this BS 30. Hence, a wireless device 25 should be able to evaluate whether it will be out-of-coverage of the wake-up signal and, if it is out-of-coverage, it should avoid transitioning to the low power operating mode.

[0059] Figure 4 represents a diagram showing steps of an exemplary embodiment of a method 40 for exchanging data, which is implemented by a BS 30. Figure 5 represents a diagram showing corresponding steps of an exemplary embodiment of a method 50 for exchanging data, which is implemented by a wireless device 25 of a UE 20.

[0060] As illustrated by figure 4, the method 40 for exchanging data comprises a step S40 of determining a minimum reception level threshold for a given wireless device 25 and a step S41 of transmitting an indication of the determined minimum reception level threshold to this given wireless device 25.

[0061] As indicated above, the minimum reception level threshold is determined specifically for the considered wireless device 25 and is for instance selected among a plurality of possible minimum reception level thresholds, or in a range of possible minimum reception thresholds.

[0062] As will be discussed hereinbelow, the minimum reception level threshold will be used by the wireless device 25 to determine whether the expected reception level of the wakeup signal makes it detectable by the LP-WUR 254. If the expected reception level of the wake-up signal makes it detectable by the LP-WUR 254, then the wireless device 25 can transition to the low power operating mode, if required to save energy. In turn, if the expected reception level of the wake-up signal makes it undetectable by the LP-WLIR 254, then the wireless device 25 should avoid transitioning to the low power operating mode and should therefore remain in the normal operating mode.

[0063] It is advantageous to use a wireless device 25 specific minimum reception level threshold instead of using a same minimum reception level threshold for all wireless devices 25 (and UEs 20), because the respective LP-WURs 254 of the wireless devices 25 in the PDCCH coverage 31 of the BS 30 may have e.g., different receiver sensitivities, such that a wake-up received with a given reception level might be both detectable by some LP- WURs 254 having good receiver sensitivities and undetectable by some LP-WURs 254 having poor receiver sensitivities. Hence, adapting the minimum reception level threshold to each wireless device 25 makes it possible to increase the number of wireless devices 25 that can benefit from the low power operating mode compared to using a same minimum reception level threshold for all the wireless devices 25.

[0064] In order to determine a minimum reception level threshold specific to wireless device 25, the BS 30 may use information relative to this wireless device 25. In some examples, such information relative to the specific wireless device 25 may be retrieved from a database that can be accessed by the BS 30. In other examples, and as illustrated in a non-limitative manner by figure 4, the method 40 for exchanging data comprises a step S42 of receiving information from the wireless device 25, and the minimum reception level threshold for this wireless device 25 is determined at least based on the information received from this wireless device 25.

[0065] For example, the information received (and / or retrieved from a database) may be representative of the receiver sensitivity of the LP-WUR 254 of the wireless device 25 or may be used to estimate the receiver sensitivity of the LP-WUR 254 of the wireless device25. Such information representative of the receiver sensitivity of the LP-WLIR 254 of the wireless device 25 may be used by the BS 30 to adjust the minimum reception level threshold for the expected reception level of the wake-up signal.

[0066] For example, information representative of the receiver sensitivity of the LP-WLIR 254 may be received from the wireless device 25 in UE assistance information and / or in a UE capability message.

[0067] According to another example, the BS 30 may use information received from the wireless device 25 to estimate the receiver sensitivity of the LP-WLIR 254. Such information may be received as a measurement report from the wireless device 25, wherein the wireless device 25 reports a measurement of a reference signal related to the wake-up signal.

[0068] In some examples, the information representative of the receiver sensitivity may correspond to the actual receiver sensitivity of the LP-WLIR 254, for example expressed in dBm.

[0069] In other examples, it is possible that different types of LP-WLIR are predefined, each having different predefined receiver sensitivities. In such a case, the information representative of the receiver sensitivity may correspond to an identifier of the type of the LP-WLIR 254 of the considered wireless device 25, which may be used by the BS 30 to retrieve the corresponding predefined receiver sensitivity and to determine a suitable minimum reception level threshold.

[0070] In other examples, the BS 30 may use information received from the wireless device 25 during a calibration phase. For example, such a calibration phase may comprise repeating, by the BS 30, a calibration signal (which may be the wake-up signal or a reference signal) to be detected by the LP-WLIR 254 of the wireless device 25. The BS 30 may start transmitting the calibration signal with a low transmit power and may progressively increase the transmit power at each repetition. The LP-WLIR 254 attempts to detect the calibration signal and, once detected, measures its reception level. This measured reception level of the calibration signal is transmitted to the BS 30, which may use this measured reception level to select the minimum reception level threshold for this wireless device 25.

[0071] Of course, other types of information may be used by the BS 30 to determine a minimum reception threshold specifically for the considered wireless device 25, and the choice of a specific type of information corresponds to a specific and non-limitative embodiment of the present disclosure.

[0072] During step S41 , the BS 30 indicates the minimum reception level threshold to the wireless device 25 by using any suitable signaling message.

[0073] For example, the minimum reception level threshold may be transmitted in a radio resource control, RRC, message. For example, the indication of the minimum receptionlevel threshold is transmitted with the wireless device 25 in a RRC connected state. The RRC message used is for example a RRC release message, when indicating the wireless device 25 to transition to a RRC inactive state.

[0074] The indication of the minimum reception level threshold may correspond to the actual value of the minimum reception level threshold selected by the BS 30. In other examples, the indication may correspond to an identifier of the minimum reception level threshold. In such a case, a mapping between different possible minimum reception levels thresholds and their respective identifiers may be preconfigured at the wireless device 25. For example, such a mapping may be predefined (e.g., specified by a standard), or it may be e.g., transmitted to the wireless device 25 by the BS 30 (e.g., included in system information broadcasted by the BS 30 or in a message dedicated to this wireless device 25).

[0075] As discussed above, figure 5 represents a diagram showing corresponding steps of an exemplary embodiment of a method 50 for exchanging data, which may be implemented by a wireless device 25 of a UE 20 when the BS 30 implements the method 40 for exchanging data illustrated by figure 4.

[0076] As illustrated by figure 5, the method 50 for exchanging data comprises a step S50 of receiving, from the BS 30, the indication of the minimum reception level threshold determined specifically for this wireless device 25. As discussed above, this indication may be received via any suitable message. For example, this indication is received in a RRC message while the wireless device 25 in the RRC connected state, for instance via a RRC release message.

[0077] As discussed above, in some examples, the minimum reception level threshold may be determined, by the BS 30, based on information transmitted by the wireless device 25. In the non-limitative example of figure 5, the method 50 for exchanging data comprises a step S53 of transmitting such information to the BS 30.

[0078] As illustrated in the non-limitative example of figure 5, the method 50 for exchanging data comprises a step S51 of estimating a reception level representative of an expected reception level, by the LP-WLIR 254, of the wake-up signal transmitted by the BS 30.

[0079] Basically, the estimated reception level corresponds to any parameter that can be used to predict if the wireless device 25 will likely be able to detect a wake-up signal transmitted by the BS 30 to this wireless device 25. In practice, any measurement which includes a measurement of a pathloss between the BS 30 and the wireless device 25 can be considered to be representative of the expected reception level, by the LP-WLIR 254 of the wake-up signal transmitted by the BS 30, since the pathloss depends on the distance between the BS 30 and the LP-WLIR 254. Hence, the estimated reception level can for instance be determined by measuring any radio signal transmitted by the BS 30. For example, the estimated reception level may be determined by measuring a reference signaltransmitted by the wireless communication unit 303 of the BS 30 (measured by the MR unit253), or by the WUT 304 of the BS 30 (measured by the MR unit 253 or by the LP-WLIR254). It is also possible, in other examples, to determine the estimated reception level based on a measurement of a wake-up signal transmitted by the BS 30. For instance, the estimated reception level may be determined based on: the reception level measured by the LP-WLIR 254 of the wireless device 25 for a wake-up signal transmitted by the BS 30 to another wireless device, and / or the reception level measured by the LP-WLIR 254 of the wireless device 25 for a wake-up signal addressed to said wireless device 25, received during a previous period during which the wireless device 25 was in the low power operating mode.

[0080] For instance, the estimated reception level, determined based on the measurement of a reference signal transmitted by the BS 30, may be correspond to a reference signal receive power, RSRP, of the reference signal and / or to a reference signal receive quality, RSRQ, of the reference signal, as defined by the 3GPP specifications.

[0081] As illustrated by the non-limitative example of figure 5, the method 50 for exchanging data comprises a step S52 of selecting an operating mode of the wireless device 25 by comparing the estimated reception level (determined during step S51) with the minimum reception level threshold (received in step S50).

[0082] For example, if the wireless device 25 determines that the estimated reception level is greater than the minimum reception level threshold received from the BS 30 (reference S52a in figure 5), then the wireless device 25 considers that it can transition to the low power operating mode, if required to save energy.

[0083] In turn, if the wireless device 25 determines that the estimated reception level is lower than the minimum reception level threshold received from the BS 30 (reference S52b in figure 5), then the wireless device 25 considers that the reception of the wake-up signal is not possible, and it shall not transition to the low power operating mode. Optionally, and as illustrated in the non-limitative example of figure 5, the wireless device 25 may in such a case inform the BS 30 the reception of the wake-up signal is not possible at the wireless device 25, by transmitting a corresponding message to the BS 30 during a step S54. Informing the BS 30 that the reception of the wake-up signal is not possible at the wireless device 25 may be done by using any suitable signaling message. For example, the wireless device 25 may use assistance information and / or a small data transmission, SDT, procedure to inform the BS 30 that the reception of the wake-up signal is not possible.

[0084] As illustrated in the non-limitative example of figure 4, in such a case, the method 40 for exchanging data comprises a step S43 of receiving, from this wireless device 25, the indication that it cannot receive the wake-up signal. In response to receiving such anindication from the wireless device 25, the BS 30 may for example deactivate the transmission of the wake-up signal for this specific wireless device 25.

[0085] Hence, the present disclosure proposes to increase the number of UEs 20 that can put their respective wireless devices 25 in the low power operating mode by setting UE- specific minimum reception level thresholds for authorizing the use of the low power operating mode. In the example illustrated by figure 1 , the UE 20-2 has a better receiver sensitivity than the UE 20-1 . Accordingly, the UE 20-2 is configured by the RAN with a lower minimum reception level threshold than the minimum reception level threshold of the UE 20-1. As a result, the UE 20-2 can use the low power operating mode of its wireless device 25 in a broader coverage 32-2 than the coverage 32-1 in which the UE 20-1 can use the low power operating mode of its wireless device 25.

[0086] If a same minimum reception level threshold was used for all UEs 20, then this same minimum reception level threshold would correspond substantially to the minimum reception level threshold required for preventing the UE 20-1 to use the low power operating mode where it cannot receive the wake-up signal, resulting in all UEs 20 being forced to use the low power operating mode only in the coverage 32-1 . In turn, the present disclosure enables the UE 20-2 to use the low power operating mode of its wireless device 25 in a broader coverage 32-2, resulting in increased energy savings for the UE 20-2.

Claims

Claims1. A method (50) for exchanging data in a wireless communication system, the method being implemented by a wireless device (25) of the wireless communication system, wherein the wireless device comprises a main radio, MR, unit (253), configured to exchange data with a radio access network, RAN, of the wireless communication system, and a low- power wake-up receiver, LP-WLIR (254), configured to detect a wake-up signal transmitted by the RAN, wherein the wireless device comprises at least two operating modes which include a normal operating mode and a low-power operating mode, wherein: in the normal operating mode, the MR unit is in an active state, in the low-power operating mode, the MR unit is in a very low power state and the LP-WLIR is configured to trigger a transition to the normal operating mode in response to detecting a wake-up signal transmitted by the RAN, wherein the method comprises:(550) receiving, from the RAN, an indication of a minimum reception level threshold,(551) estimating a reception level representative of an expected reception level, by the LP-WLIR, of the wake-up signal transmitted by the RAN,(552) selecting an operating mode of the wireless device by comparing the estimated reception level with the minimum reception level threshold.

2. The method (50) according to claim 1 , wherein the indication of the minimum reception level threshold is received by the wireless device in a radio resource control, RRC, connected state, with an indication to transition from the RRC connected state to an RRC inactive state.

3. The method (50) according to claim 2, wherein the indication of the minimum reception level threshold is received in an RRC release message.

4. The method (50) according to any one of the preceding claims, wherein the low- power operating mode is selected in response to the estimated reception level being greater than the minimum reception level threshold.

5. The method (50) according to any one of the preceding claims, wherein the normal operating mode is selected in response to the estimated reception level being lower than the minimum reception level threshold.

6. The method (50) according to claim 5, comprising informing the RAN that the reception of the wake-up signal is not possible at the wireless device in response to the estimated reception level being lower than the minimum reception level threshold.

7. The method (50) according to claim 6, wherein the informing the RAN that the reception of the wake-up signal is not possible at the wireless device is done by using assistance information, for example by using a small data transmission, SDT, procedure.

8. A wireless device (25) comprising at least one memory (251) and at least oneprocessor (250) configured to carry out a method (50) according to any one of the preceding claims.

9. A user equipment, UE (20), comprising a wireless device (25) according to claim 8.

10. A method (40) for exchanging data in a wireless communication system, the method being implemented by a base station, BS (30), of a radio access network, RAN, of the wireless communication system, wherein the BS is configured to exchange data with a wireless device (25) which comprises a main radio, MR, unit (253) and a low-power wakeup receiver, LP-WLIR (254), wherein the LP-WLIR is configured to detect a wake-up signal transmitted by the BS and to trigger a transition of the MR unit from a very low power state to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the method comprises:(540) determining a minimum reception level threshold for the wireless device,(541) transmitting an indication of the minimum reception level threshold to the wireless device.

11. The method (40) according to claim 10, wherein the minimum reception level threshold is determined based on information received from the wireless device.

12. The method (40) according to any one of claims 10 to 11 , wherein the minimum reception level threshold is determined based on information representative of a receiver sensitivity of the wireless device.

13. The method (40) according to any one of claims 10 to 12, wherein the indication of the minimum reception level threshold is included in a radio resource control, RRC, release message.

14. The method (40) according to any one of claims 10 to 13, comprising deactivating the transmission of the wake-up signal to the wireless device in response to receiving, from the wireless device, an indication that the reception of the wake-up signal is not possible.

15. A base station, BS (30), comprising at least one memory (301) and at least one processor (300) configured to carry out a method (40) according to any one of claims 10 to 14.

16. A wireless communication system comprising at least one base station (30) according to claim 15 and at least one user equipment (20) according to claim 9.

17. A computer program product comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method according to any one of claims 1 to 7 or a method according to any one of claims 10 to 14.

18. A computer-readable storage medium comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method according to any one of claims 1 to 7 or a method according to any one of claims10 to 14.

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