Methods and devices for selecting, by a user equipment, a repeating pattern for a low power wake-up signal in a wireless communication system

Abstract

The present disclosure relates to methods and devices for saving energy on a user equipment, UE (20), side of a wireless communication system.

Description

Methods and devices for selecting, by a user equipment, a repeating pattern for a low power wake-up signal in a wireless communication systemTechnical 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 be able to always detect the wake-up signal transmitted by the BS. Accordingly, if it is determined that a reception level of the wake-up signal by a UE will be too low, then it is not possible to use the wake-up signal to trigger the MR unit. In such a case, it is not possible to e.g., turn off the MR unit.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 enhancing the coverage of the wake-up signal.

[0013] For this purpose, the present disclosure proposes that a BS of the wireless communication system may use different repetition patterns for the transmission of the wake-up signal. Different repetition patterns differ at least by the number of times the BS transmits the wake-up signal to a UE. For example, a first repetition pattern may consist in transmitting the wake-up signal only once (i.e., the wake-up signal is not repeated) and asecond repetition pattern may consist in transmitting the wake-up signal twice or more (i.e. , the wake-up signal is repeated once or more). Increasing the number of times the BS transmits the wake-up signal increases the probability that the LP-WUR of this UE will be able to detect the wake-up signal, therefore increasing the coverage of the wake-up signal for this 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 and to trigger a transition of the MR unit from a low power state to an active state in response to detecting a wake-up signal transmitted by the RAN, wherein, the RAN being adapted to transmit the wake-up signal by using a plurality of repetition patterns, the method comprises: selecting a repetition pattern, among the plurality of repetition patterns, transmitting, to the RAN, an indication of the selected repetition pattern.

[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 selected repetition pattern is transmitted to the RAN by using a small data transmission, SDT, procedure, for example a preconfigured SDT, CG-SDT, or a random access SDT, RA- SDT procedure.

[0017] In some embodiments of the method according to the first aspect, the indication of the selected repetition pattern is transmitted via a physical uplink control channel, PUCCH, or via a medium access control, MAC, control element, CE, or as assistance information.

[0018] In some embodiments, the method according to the first aspect comprises estimating a reception level representative of an expected reception level, by the LP-WUR, of the wake-up signal, wherein the selecting of the repetition pattern uses the estimated reception level.

[0019] In some embodiments of the method according to the first aspect, if the estimated reception level verifies an out-of-range criterion, the method comprises informing the RAN that the reception of the wake-up signal is not possible at the wireless device.

[0020] In some embodiments of the method according to the first aspect, the information that the reception of the wake-up signal is not possible is transmitted as assistance information to the RAN.

[0021] In some embodiments of the method according to the first aspect, the selecting of the repetition pattern uses a preconfigured mapping between the plurality of repetition patterns and respective associated reception levels.

[0022] In some embodiments of the method according to the first aspect, the mapping between the plurality of repetition patterns and their respective associated reception levels is predefined or received in system information broadcasted by the RAN or received in a radio resource control, RRC, message.

[0023] 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.

[0024] 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.

[0025] According to a fourth aspect, the present disclosure relates to 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 low power state to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the method comprises: receiving, from the wireless device, an indication of a repetition pattern selected among a plurality of repetition patterns, transmitting the wake-up signal to the wireless device based on the indication received from said wireless device.

[0026] 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.

[0027] 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 to receiving, from the wireless device, an indication that the reception of the wake-up signal is not possible.

[0028] In some embodiments, the method according to the fourth aspect comprises transmitting to the wireless device a mapping between the plurality of repetition patterns and respective associated reception levels for the wake-up signal.

[0029] In some embodiments of the method according to the fourth aspect, the mapping between the plurality of repetition patterns and their respective associated reception levelsfor the wake-up signal is included in system information broadcasted by the RAN or in a radio resource control, RRC, message transmitted to the wireless device.

[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 suitable for implementing one or more methods for exchanging data with a BS,Figure 3: a schematic representation of an example of a BS suitable for implementing one or more methods for exchanging data with a wireless device, Figures 4 and 5: flow charts illustrating examples of methods for exchanging data implemented by a BS and a wireless device, respectively,Figures 6 and 7: flow charts illustrating other examples of methods for exchanging data implemented by a BS and a wireless device, respectively,Figures 8 and 9: flow charts illustrating other examples of methods for transmitting control messages implemented by a wireless device and a BS, respectively.

[0035] In these figures, references identical from one figure to another designate identicalor 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 detailed description 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 (oreNB), 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 thewireless 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-WLIR 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-WLIR 254 can consist 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 besufficiently 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 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] The WUT 304 of the BS 30 is adapted to use different repetition patterns for the transmission of the wake-up signal to a wireless device 25.

[0059] As discussed above, repetition patterns differ at least by the number of times the WUT 304 transmits the wake-up signal to a wireless device 25. Hence, the different repetition patterns include at least a first repetition pattern and a second repetition pattern, with the wake-up signal being transmitted fewer times with the first repetition pattern than with the second repetition pattern. For example, the first repetition pattern may consist in transmitting the wake-up signal only once (i.e. , the wake-up signal is not repeated) and the second repetition pattern may consist in transmitting the wake-up signal twice or more (i.e., the wake-up signal is repeated once or more). It should be noted that the present disclosure is not limited to a specific method for repeating the wake-up signal, and any method for repeating the wake-up signal falls in the scope of the present disclosure. For example, the different occurrences of the wake-up signal may be transmitted at different times and / or on different frequency channels and / or on different resource blocks, etc.

[0060] As discussed above, increasing the number of times the BS 30 transmits the wakeup signal increases the probability that the LP-WUR 254 will be able to detect the wake-up signal (by e.g., using signal processing techniques known to the skilled person such as maximum ratio combining, MRC, etc.).

[0061] Figure 1 represents schematically the coverage 32-1 of the wake-up signal when using the first repetition pattern and the coverage 32-2 of the wake-up signal when using the second repetition pattern. In this example, the wake-up signal is transmitted fewer times with the first repetition pattern than with the second repetition pattern, such that the coverage 32-2 is broader than the coverage 32-1. The UE 20-2, which is in the coverage 32-2 but not in the coverage 32-1 , cannot use its LP-WLIR 254 to trigger its MR unit 253 if the first repetition pattern is used. In turn, the UE 20-1 , which is in both the coverage 32-1 and the coverage 32-2, can use its LP-WUR 254 to trigger its MR unit 253 with either the first repetition pattern or the second repetition pattern.

[0062] Hence, the BS 30, by increasing the number of times it transmits the wake-up signal, enables more UEs to use their LP-WURs 254 to trigger their MR units 253.

[0063] Such a plurality of repetition patterns may be used in a variety of ways, some of which will be described hereinbelow. For example, a BS 30 may decide to use the same repetition pattern, among the plurality of possible repetition patterns, for all UEs in its PDCCH coverage 31 , or to selectively adapt the repetition pattern used to each UE or group of UEs. Also, the repetition pattern used for a UE (or group of UEs) may be selected by the BS 30 and / or by the considered UE (or group of UEs).

[0064] 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.

[0065] As illustrated by figure 4, the method 40 for exchanging data comprises a step S40 of selecting, by the BS 30, a repetition pattern for the transmission of the wake-up signal, among the plurality of possible repetition patterns. In this example, we consider in a non- limitative manner that the same selected repetition pattern is used for all UEs 20 in the coverage 31 of the BS 30. However, it is also possible, in other examples (some of which will be discussed hereinbelow), to select a repetition pattern that is specific to a given UE 20 or to a given group of UEs 20. It is emphasized that the fact that the same repetition pattern is used for all UEs 20 does not mean that the same wake-up signal is used for all UEs 20. Indeed, the BS 30 may need to wake-up specifically a given UE 20 or group of UEs, such that the wake-up signal transmitted shall be ignored by other UEs that are not meant to be awakened. Using the same repetition pattern implies only that the wake-up signal is repeated the same number of times regardless which UE 20 is to be awakened.

[0066] When the BS 30 needs to wake-up a UE 20 (or group of UEs 20) having a wireless device 25 in the low power operating mode, said BS 30 transmits (step S41) the wake-up signal to this specific UE 20 (or group of UEs 20) by using the selected repetition pattern.

[0067] The BS 30 may for instance select the repetition pattern, among the plurality of repetitions patterns, based on one or more parameters. Since increasing the number of times the wake-up signal is transmitted increases the number of UEs 20 that may be able to rely on their LP-WUR 254 to wake-up their MR units 253, it might be advantageous in some cases to select a repetition number having a great number of repetitions of the wakeup signal whenever possible.

[0068] In the example considered herein of a same selected repetition pattern used for all UEs 20 in the coverage 31 of the BS 30, the selection may use parameters that can be evaluated by the BS 30 without requiring receiving information from the UEs 20. However, it is also possible, in other examples, to consider information received from the UEs 20 in the repetition pattern selection process.

[0069] For example, the repetition pattern may be selected based on a load level of the BS 30. The load level of the BS 30 may be any parameter representative of the amount of data that the BS 30 may have to handle due to the UEs 20 in its coverage 31. For example, the BS 30 may decide to select a repetition pattern having a great number of repetitions of the wake-up signal if its load level is low, and to select a repetition pattern having a low number of repetitions (or no repetitions at all) if its load level is high. For example, the load level of the BS 30 may correspond to the total number of UEs 20 in the coverage 31 of the BS 30, or to the total amount of data to be transmitted to UEs in its coverage 31 , or to the number of high priority UEs 20 in its coverage 31 , or to the total amount of resources that need to be scheduled for high priority UEs 20 in its coverage 31 , etc. For example, if the plurality of possible repetition patterns consists in a first repetition pattern with no repetitions (i.e. , thewake-up signal is transmitted only once) and a second repetition pattern is which the wakeup signal is repeated at least once (i.e., the wake-up signal is transmitted at least twice), then the BS 30 may select the first repetition pattern if the load level is high (e.g., above a predetermined threshold), or it may enable repetitions by selecting the second repetition pattern if the load level is low (e.g., below the predetermined threshold).

[0070] Alternatively, or in combination thereof, the repetition pattern may be selected based on an energy consumption of the BS 30. For example, if the BS 30 wants to reduce temporarily its energy consumption, it may select a repetition pattern having a low number of repetitions (or no repetitions at all). In turn, if there is no constraint on the energy consumption of the BS 30, it may select a repetition pattern having a great number of repetitions of the wake-up signal.

[0071] It should be noted that that BS 30 does not necessarily need to notify the selected repetition pattern to the UEs 20. For example, each UE 20 may search for a wake-up signal by assuming that it is transmitted by using the repetition pattern, among the plurality of possible repetition patterns, having the greatest number of repetitions.

[0072] However, in some examples, and as illustrated in the non-limitative example of figure 4, the method 40 for exchanging data may comprise a step S42 of transmitting an indication of the selected repetition pattern to each UE 20. In the non-limitative example considered herein of a same selected repetition pattern used for all UEs 20 in the coverage of the BS 30, the indication may for instance be included in system information broadcasted to all UEs 20. Including the indication in system information broadcasted to all UEs 20 is advantageous in that it can be received by all UEs 20 regardless their radio resource control, RRC, state (including by UEs 20 in the RRC idle / inactive states). However, other types of messages may be used for transmitting the indication of the selected repetition pattern to a UE 20. For example, the indication of the selected repetition pattern may be transmitted by using the wireless communication unit 303 of the BS 30 and is therefore received by UEs 20 having their wireless devices 25 using the normal operating mode (MR units 253 in the active state), before transitioning to the low power operating mode. However, in other examples, the indication of the selected repetition pattern may be transmitted by using the WUT 304 of the BS 30 and may therefore be received even by the LP-WURs 254 of the UEs 20 having their wireless devices 25 in the low power operating mode.

[0073] The indication of the selected repetition pattern may use any suitable format. For instance, it may correspond to a bit vector which indicates an identifier of the selected repetition pattern, or which indicates the number of repetitions of the wake-up signal. For example, if the plurality of possible repetition patterns consists in a first repetition pattern with no repetitions and a second repetition pattern is which the wake-up signal is repeated at least once, then the indication may consist in a bit vector having a single bit used toindicate whether repetitions of the wake-up signal are enabled. According to another non- limitative example, if the BS 30 selects the repetition pattern based on its load level, then the indication transmitted may be representative of the load level of the BS 30, from which the UE 20 may determine the repetition pattern selected by the BS 30 by applying the same selection process as the BS 30.

[0074] 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.

[0075] As illustrated by figure 5, the method 50 for exchanging data comprises a step S50 of determining the repetition pattern used by the BS 30 to transmit the wake-up signal. As discussed above, the wireless device 25 may for example determine the repetition pattern used by the BS 30, based on an indication received from said BS 30.

[0076] As illustrated by figure 5, the method 50 for exchanging data comprises also, when the wireless device 25 of the UE 20 is in the low power operating mode, a step S53 of searching for a wake-up signal transmitted by the BS 30, based on the repetition pattern determined during step S50.

[0077] However, the non-limitative example illustrated by figure 5 focuses on how the wireless device 25 may decide whether it can go into the low power operating mode. Indeed, as discussed above, the coverage of the wake-up signal may be smaller than the PDCCH coverage 31 of the BS 30, and therefore the wireless device 25 should not be placed in the low power operating mode if it is not in the coverage of the wake-up signal. Also, the repetition pattern used by the BS 30 modifies the coverage of the wake-up signal, so the wireless device 25 may use the repetition pattern determined during step S50 to adjust its behavior with regards to the monitoring of the wake-up signal.

[0078] As illustrated in the non-limitative example of figure 5, the method 50 comprises a step S51 of estimating a reception level representative of an expected reception level, by the LP-WUR 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, for each possible repetition pattern, if the wireless device 25 will likely be in the coverage of the wake-up signal transmitted by the BS 30 using the considered repetition pattern. 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-WUR 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-WUR 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 bedetermined by measuring a reference signal transmitted by the wireless communication unit 303 of the BS 30 (measured by the MR unit 253), or by the WUT 304 of the BS 30 (measured by the MR unit 253 or by the LP-WLIR 254). 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 based on the determined repetition pattern (in step S50) and based on the estimated reception level (in step S51). Indeed, since the wireless device 25 knows the repetition pattern used by the BS 30 for transmitting the wake-up signal and the expected reception level of this wake-up signal, it can evaluate whether it is in the coverage of the wake-up signal. If, based on the determined repetition pattern and the estimated reception level, the wireless device 25 determines that it is likely outside the coverage of the wake-up signal (reference S52b in figure 5), then it selects the normal operating mode. In turn, if the wireless device 25 determines that it is likely inside the coverage of the wake-up signal (reference S52a in figure 5), then it selects the low power operating mode.

[0082] For instance, we assume in a non-limitative manner that the plurality of possible repetition patterns consists in a first repetition pattern and a second repetition pattern, wherein the first repetition pattern comprises fewer repetitions of the wake-up signal than the second repetition pattern. In such a case, if the wireless device 25 has determined that the BS 30 uses the first repetition pattern, it may evaluate whether the estimated reception level verifies a predetermined first selection criterion. If the first selection criterion is verified (resp. not verified) the wireless device 25 selects the low power operating mode (resp. the normal operating mode). If the wireless device 25 has determined that the BS 30 uses the second repetition pattern, it may evaluate whether the estimated reception level verifies a predetermined second selection criterion, different from the first selection criterion. If thesecond selection criterion is verified (resp. not verified) the wireless device 25 selects the low power operating mode (resp. the normal operating mode).

[0083] For example, the first selection criterion is verified if the estimated reception level is greater than a first threshold and / or the second selection criterion is verified if the estimated reception level is greater than a second threshold, different from the first threshold. Basically, the first threshold is representative of a first minimum reception level above which the wakeup signal can be detected when using the first repetition pattern and the second threshold is representative of a second minimum reception level above which the wake-up signal can be detected when using the second repetition pattern. Since the second repetition pattern comprises more repetitions of the wake-signal than the first repetition pattern, the wake-up signal can be detected with a lower reception level when using the second repetition pattern than when using the first repetition pattern, such that the first threshold is typically greater than the second threshold. The respective values of the first threshold and the second threshold may for instance be predefined (e.g., specified by a standard or by calibration of the wireless device), or they may be e.g., received from the BS 30 (e.g., included in system information broadcasted by the BS 30 or in a message dedicated to this wireless device 25).

[0084] Figure 6 represents a diagram showing steps of an exemplary embodiment of a method 60 for exchanging data, which is implemented by a BS 30. Figure 7 represents a diagram showing corresponding steps of an exemplary embodiment of a method 70 for exchanging data, which is implemented by a wireless device 25 of a UE 20.

[0085] As illustrated by figure 6, the method 60 for exchanging data comprises a step S60 of selecting, by the BS 30, a repetition pattern for the transmission of the wake-up signal, among the plurality of possible repetition patterns. In this example, we consider in a non- limitative manner that the BS 30 can adjust the repetition pattern for each UE 20 or group of UEs 20. In other words, the BS 30 can use different repetition patterns, among the plurality of possible repetition patterns, for different UEs 20.

[0086] When the BS 30 needs to wake-up a UE 20 (or group of UEs 20) having a wireless device 25 in the low power operating mode, said BS 30 transmits (step S61) the wake-up signal to this specific UE 20 (or group of UEs 20) by using the repetition pattern selected for this UE 20 (or group of UEs 20).

[0087] As discussed above in relation with step S42, the BS 30 does not necessarily need to notify the selected repetition pattern to the UEs 20 (or group of UEs 20). However, in some examples, and as illustrated in the non-limitative example of figure 6, the method 60 for exchanging data may comprise a step S62 of transmitting, to a specific UE 20 (or group of UEs 20), an indication of the repetition pattern selected for this UE 20 (or group of UEs 20). All that has been said hereinabove for the indication, in relation with e.g., step S42, applies similarly to the examples illustrated by figures 6 and 7.

[0088] The BS 30 may for instance select the repetition pattern, among the plurality of repetitions patterns, based on one or more parameters. In the example considered herein of a repetition pattern tailored to each UE 20 (or group of UEs 20), the repetition pattern can be selected based on information received from this UE 20 (or group of UEs 20). We discuss below non-limitative examples of information, received from a UE 20, that can be used in the repetition pattern selection process.

[0089] In the non-limitative example of figure 6, the method 60 for exchanging data comprises a step S63 of receiving an estimated reception level from the wireless device 25 of a UE 20 and the repetition pattern for this UE 20 is selected, during step S60, based on the received estimated reception level. All that has been said hereinabove for the estimated reception level, in relation with e.g., step S51 , applies similarly to the examples illustrated by figures 6 and 7. For example, the received estimated reception level may correspond to an RSRP and / or RSRQ.

[0090] By using the estimated reception level provided by a UE 20, which is representative of the expected reception level, by the LP-WUR 254 of this UE 20, of the wake-up signal transmitted by the BS 30, said BS 30 can evaluate the coverage required for the wake-up signal to enable the LP-WUR 254 of this UE 20 to detect the wake-up signal. If the estimated reception level is high, then the BS 30 may reduce the number of times the wake-up signal is transmitted for this UE 20 (and possibly disabling repetition for this UE 20). In turn, if the estimated reception level is low, then the BS 30 can increase the number of times the wakeup signal is transmitted for this UE 20 to increase the coverage of the wake-up signal. In some cases, the estimated reception level may verify a predetermined out-of-range criterion, i.e. , it may be too low for the LP-WUR 254 of this UE 20 to detect the wake signal. In such a case, the BS 30 can decide, during the selecting step S60, to deactivate the transmission of the wake-up signal for this specific UE 20, the wireless device 25 of which should therefore remain in the normal operating mode.

[0091] For example, during the selecting step S60, the BS 30 can use a predetermined mapping between the plurality of possible repetition patterns and respective associated reception levels. Table 1 below provides a non-limitative example of such a mapping.Table 1

[0092] In the example of table 1 , the reception levels are considered to correspond to an RSRP or an RSRQ, and the reception levels RL1 to RL5 are such that:RL1 > RL2 > RL3 > RL4 > RL5

[0093] The repetition patterns RP1 to RP5 are such that: the repetition pattern RP1 has the fewest number of repetitions (possibly none with the wake-up signal being transmitted only once), the repetition pattern RP2 has a greater number of repetitions (and a greater coverage) than the repetition pattern RP1 , the repetition pattern RP3 has a greater number of repetitions (and a greater coverage) than the repetition pattern RP2, the repetition pattern RP4 has a greater number of repetitions (and a greater coverage) than the repetition pattern RP3, the repetition pattern RP5 has a greater number of repetitions (and a greater coverage) than the repetition pattern RP4.

[0094] For example, the wake-up signal may be transmitted: only once (no repetition) with the repetition pattern RP1 , twice (one repetition) with the repetition pattern RP2, four times (three repetitions) with the repetition pattern RP3, six times (five repetitions) with the repetition pattern RP4, eight times (seven repetitions) with the repetition pattern RP5.

[0095] In the example of table 1 , if the estimated reception level, received from the UE 20, is greater than RL1 , then the BS 30 selects the repetition pattern RP1. If the estimated reception level is lower than RL1 and greater than RL2, then the BS 30 selects the repetition pattern RP2. If the estimated reception level is lower than RL2 and greater than RL3, then the BS 30 selects the repetition pattern RP3. If the estimated reception level is lower than RL3 and greater than RL4, then the BS 30 selects the repetition pattern RP4. If the estimated reception level is lower than RL4 and greater than RL5, then the BS 30 selects the repetition pattern RP5. If the estimated reception level is lower than RL5, then the out- of-range criterion is verified and the BS 30 deactivates the transmission of the wake-up signal for this specific UE 20, the wireless device 25 of which should therefore remain in the normal operating mode.

[0096] The BS 30 may also use other parameters, alternatively or in combination with the estimated reception level, during the selecting step S60.

[0097] In the non-limitative example of figure 6, the method 60 for exchanging data comprises a step S64 of receiving assistance information from the wireless device 25 of a UE 20 and the repetition pattern for this UE 20 is selected, during step S60, based on the received assistance information. The assistance information may be any information that can be relevant for selecting a repetition pattern for the wireless device 25 of this UE 20. For example, the BS 30 may receive a mobility status from the wireless device 25, representative of whether the UE 20 is non-stationary (mobile) or stationary (immobile). Forexample, if the UE 20 is non-stationary, the BS 30 may decide to deactivate the transmission of the wake-up signal for this UE 20, or it may decide to use the repetition pattern having the greatest number of repetitions of the wake-up signal (i.e. , the repetition pattern having the broadest coverage) to account for the fact that, even if the UE 20 is currently close to the BS 30, it may move away from this BS 30. Also, the BS 30 may decide to deactivate the transmission of the wake-up signal for a UE 20 for which the mobility status indicates that the UE 20 is moving away from the BS 30, etc. Alternatively, or in combination thereof, the wireless device 25 may transmit assistance information which comprises information of future UL traffic characteristics of the UE 20. For example, the BS 30 may decide to deactivate the transmission of the wake-up signal for a UE 20 for which the future UL traffic characteristics received indicate that the UL traffic of this UE 20 might be important in the short term, etc.

[0098] It should be noted that, in other examples, the BS 30 can also use other parameters, in addition to information received from the UEs 20. For example, the BS 30 may also select the repetition pattern based on its load level and / or based on its energy consumption. For example, the BS 30 may decide to tailor the repetition patterns to the UEs 20 in its coverage 31 only if its load level is low and / or if its energy consumption is low. If its load level is high and / or if its energy consumption is high, the BS 30 may decide to select the same repetition pattern (for example the one having the fewest repetitions) for all UEs 20.

[0099] As indicated above, the BS 30 may also select a repetition pattern for a group of UEs 20. For example, a group of UEs 20 may correspond to UEs 20 that need to be awakened simultaneously, for which a same wake-up signal can be transmitted as a multicast signal. In such a case, the BS 30 may for example select the repetition pattern that, according to e.g., the estimated reception levels received from these UEs 20, enables all the UEs 20 to detect the wake-up signal. According to another example, the BS 30 may divide the group in subgroups of UEs 20 having similar estimated reception levels, and it may adjust the repetition pattern for each subgroup of UEs (such that the wake-up signal can be transmitted as a multicast signal to each subgroup, if required to wake-up simultaneously the UEs 20 of a subgroup, by using the corresponding repetition pattern).

[0100] During the transmitting step S62, the indication transmitted to a UE 20 may for example include the identifier of the of the repetition pattern selected for this UE 20, or the number of repetitions or occurrences of the wake-up signal.

[0101] For example, if the BS 30 has selected the repetition pattern RP3, the indication may include the identifier RP3. The identifier transmitted may correspond for example to an index of the selected repetition pattern among the plurality of repetitions patterns. For example, the index of the repetition pattern RP1 may be ‘O’, the index of the repetition pattern RP2 may be T, the index of the repetition pattern RP3 may be ‘2’, the index of the repetitionpattern RP4 may be ‘3’ and the index of the repetition pattern RP5 may be ‘4’. Based on the repetition pattern identifier received, the wireless device 25 of the UE 20 may for example determine the corresponding number of times the wake-up signal is transmitted by using a preconfigured mapping between the plurality of repetition pattern identifiers and their respective numbers of repetitions or occurrences of the wake-up signal. Table 2 below provides a non-limitative example of a mapping between the plurality of repetition pattern identifiers and their respective numbers of repetitions of the wake-up signal, for the repetition patterns RP1 to RP5 discussed above:Table 2

[0102] The mapping between the plurality of repetition pattern identifiers and their respective numbers of repetitions or occurrences of the wake-up signal is preconfigured at the wireless device 25. Such a mapping can for instance be predefined (e.g., specified by a standard or by calibration of the wireless device), or it may be e.g., transmitted by the BS 30. In the latter case, the mapping may be e.g., included in system information broadcasted by the BS 30 or included in a message dedicated to this wireless device 25, such as an RRC message (e.g., RRC reconfiguration message).

[0103] According to another example, if the BS 30 has selected the repetition pattern RP3, the indication may include the number of repetitions of the wake-up signal in the selected repetition pattern (i.e., three repetitions for RP3) or, equivalently, the number of occurrences of the wake-up signal in the selected repetition pattern (i.e., four occurrences for RP3).

[0104] The indication of the selected repetition pattern (which may be an indication that the transmission of the wake-up signal is deactivated), transmitted to the corresponding specific UE 20, may use any type of suitable signaling. For example, the indication may be included a RRC message transmitted to the specific UE 20, such as a RRC reconfiguration message (if e.g., the wireless device 25 is in the RRC connected mode), or it may be transmitted to the specific UE 20 via L1 signaling and / or L2 signaling. For example, L1 signaling corresponds to using a physical downlink control channel, PDCCH. For example, L2 signaling corresponds to using a medium access control, MAC, control element, CE.

[0105] In some cases, the transmitting of the indication, to the wireless device 25 of the considered UE 20, may comprise transmitting a configuration message, with the indication or in a separate message, which includes a more detailed description of the repetition pattern that will be used by the BS 30 for this UE 20. For example, the more detailed description may include a description of physical parameters of the repetition pattern, suchas e.g., the temporal separation(s) between two successive occurrences of the wake-up signal in the repetition pattern, the frequency channels used for the respective occurrences, etc. Such a more detailed description, if any, may be used to facilitate the search of the wake-up signal by the wireless device 25 of the UE 20. However, it should be noted that such a description of the physical parameters may not be required to enable the UE 20 to search for the wake-up signal. For example, knowing the number of times the wake-up signal is transmitted may be sufficient for the wireless device 25 to search for it. According to another example, the physical parameters (e.g., the temporal separation(s) between two successive occurrences) for each possible repetition pattern may be preconfigured at the wireless device 25, e.g., predefined (e.g., specified by a standard or by calibration of the wireless device) or broadcasted in system information by the BS 30.

[0106] In some cases, the method 60 for exchanging data may comprise also one or more of the following: transmitting an activation message to the UE 20, for example via L1 / L2 signaling, notifying that the use of the repetition pattern indicated is activated by the BS 30: this can be used for example if the repetition pattern is not activated immediately once selected, and can be used to notify the wireless device 25 that it can go to the low power operating mode, transmitting a deactivation message to the UE 20, for example via L1 / L2 signaling, notifying that the use of the repetition pattern indicated is deactivated by the BS 30: this can be used for example if the load level and / or the energy consumption of the BS 30 has increased, or as a confirmation message sent to a UE 20 that has notified the BS 30 that it has transitioned from the low power operating mode to the normal operating mode, transmitting a low power deactivation message to the UE 20, for example via L1 / L2 signaling, notifying that the transmission of the wake-up signal by the RAN is deactivated for the UE 20: this can be used for example if the load level and / or the energy consumption of the BS 30 has increased.

[0107] As discussed above, figure 7 represents a diagram showing corresponding steps of an exemplary embodiment of a method 70 for exchanging data, which may be implemented by a wireless device 25 of a UE 20 when the BS 30 implements the method 60 for exchanging data illustrated by figure 6.

[0108] As illustrated by figure 7, the method 50 for exchanging data comprises a step S70 of determining the repetition pattern selected by the BS 30 to transmit the wake-up signal for this wireless device 25 (selected during step S60). As discussed above, the wireless device 25 may for example determine the repetition pattern used by the BS 30, based on the indication received from said BS 30.

[0109] As illustrated by figure 7, the method 50 for exchanging data comprises also, when the wireless device 25 of the UE 20 is in the low power operating mode, a step S71 of searching for a wake-up signal transmitted by the BS 30, based on the repetition pattern determined during step S70.

[0110] In the non-limitative example illustrated by figure 7, the wireless device 25 of the UE 20 transmits to the BS 30 information enabling said BS 30 to adjust the repetition pattern. As discussed above, this information may include for example an estimated reception level and / or assistance information.

[0111] In the non-limitative example illustrated by figure 7, the information includes an estimated reception level, and the method 70 for exchanging data comprises: a step S72 of estimating a reception level representative of an expected reception level, by the LP-WUR 254, of the wake-up signal, a step S73 of transmitting the estimated reception level to the BS 30.

[0112] All that has been said hereinabove for the estimated reception level, in relation with e.g., step S51 , applies similarly to step S72. For example, the estimated reception level may correspond to an RSRP and / or RSRQ and may be transmitted in a measurement report.

[0113] In the non-limitative example illustrated by figure 7, the information also includes assistance information (e.g., mobility status, future UL traffic characteristics, etc.), and the method 70 for exchanging data comprises a step S74 of transmitting assistance information to the BS 30.

[0114] Figure 8 represents a diagram showing steps of an exemplary embodiment of a method 80 for exchanging data, which is implemented by a wireless device 25 of a UE 20. Figure 9 represents a diagram showing corresponding steps of an exemplary embodiment of a method 90 for exchanging data, which is implemented by a BS 30.

[0115] In the examples illustrated by figures 8 and 9, the repetition pattern used for transmitting the wake-up signal to specific UE 20 (or group of UEs 20) is adjusted to this specific UE 20 (or group of UEs 20). However, in these examples, it is the UE 20 that selects the repetition pattern that the BS 30 is to use for transmitting wake-up signals to this UE 20.

[0116] As illustrated by figure 8, the method 80 for exchanging data comprises: a step S80 of selecting, by the wireless device 25 of the UE 20, a repetition pattern for the transmission of the wake-up signal, among the plurality of possible repetition patterns, and a step S81 of transmitting, to the BS 30, an indication of the selected repetition pattern, to be used by the BS 30 to transmit the wake-up signal to this UE 20.

[0117] The wireless device 25 may for instance select the repetition pattern, among the plurality of repetitions patterns, based on one or more parameters. For example, the wireless device 25 may select the repetition pattern based on a mobility status. For example,if the UE 20 is non-stationary, the wireless device 25 may decide to deactivate the monitoring of the wake-up signal, or it may decide to select the repetition pattern having the greatest number of repetitions of the wake-up signal to account for the fact that, even if the UE 20 is currently close to the BS 30, it may move away from this BS 30. Also, the wireless device 25 may decide to deactivate the monitoring of the wake-up signal if the UE 20 is moving away from the BS 30, etc.

[0118] In the non-limitative example of figure 8, the method 80 for exchanging data comprises a step S82 of estimating, by the wireless device 25, a reception level representative of an expected reception level, by the LP-WUR 254, of the wake-up signal, and the selecting of the repetition pattern uses the estimated reception level. All that has been said hereinabove for the estimated reception level, in relation with e.g., step S51 , applies similarly to step S82. For example, the estimated reception level may correspond to an RSRP and / or RSRQ.

[0119] By using the estimated reception level, which is representative of the expected reception level, by the LP-WUR 254 of this UE 20, of the wake-up signal transmitted by the BS 30, the wireless device 25 can evaluate the coverage required for the wake-up signal to enable its LP-WUR 254 to detect the wake-up signal. If the estimated reception level is high, then the wireless device 25 may reduce the number of times the wake-up signal should be transmitted for this UE 20 (and possibly disabling repetition for this UE 20). In turn, if the estimated reception level is low, then the wireless device can increase the number of times the wake-up signal should be transmitted for this UE 20 to increase the coverage of the wake-up signal. In some cases, the estimated reception level may verify a predetermined out-of-range criterion, i.e., it may be too low for the LP-WUR 254 of this UE 20 to detect the wake signal. In such a case, the wireless device 25 can decide, during the selecting step S80, to deactivate the monitoring of the wake-up signal for this specific U E 20 (and to remain in the normal operating mode), and can inform the BS 30, e.g., in the indication transmitted during step S81 , that the reception of the wake-up signal is not possible at the wireless device.

[0120] For example, during the selecting step S80, the wireless device can use a predetermined mapping between the plurality of possible repetition patterns and respective associated reception levels. Table 1 above provides a non-limitative example of such a mapping, that can be used by the wireless device 25, and the selection process described in relation with table 1 can be applied similarly by the wireless device 25. Such a mapping between the plurality of repetition patterns and their respective associated reception levels, if used is preconfigured at the wireless device 25. For example, this mapping can be predefined (e.g., specified by a standard or by calibration of the wireless device 25), or it may be e.g., received from the BS 30. In the latter case, the mapping may be e.g., includedin system information broadcasted by the BS 30 or received in a message dedicated to this wireless device 25, such as an RRC message (e.g., RRC release message).

[0121] The indication of the selected repetition pattern (which may be an indication that the monitoring of the wake-up signal is deactivated e.g., because the out-of-range criterion is verified), transmitted to the BS 30 during step S81 , may use any type of suitable signaling.

[0122] For example, such an indication may be transmitted to the BS 30 by using a small data transmission, SDT, procedure, for example a preconfigured SDT, CG-SDT, or a random access SDT, RA-SDT procedure. Alternatively, or in combination thereof (depending on e.g., the RRC state of the wireless device 25), the indication of the selected repetition pattern (which may be an indication that the monitoring of the wake-up signal is deactivated) may be transmitted via a physical uplink control channel, PLICCH, or via a MAC CE, or as assistance information.

[0123] As discussed above, figure 9 represents a diagram showing corresponding steps of an exemplary embodiment of a method 90 for exchanging data, which may be implemented by a BS 30 when the wireless device 25 of a UE 20 implements the method 80 for exchanging data illustrated by figure 8.

[0124] As illustrated by figure 9, the method 90 for exchanging data comprises a step S90 of receiving, from the wireless device 25, an indication of the repetition pattern selected by this wireless device 25 among a plurality of repetition patterns.

[0125] The method 90 for exchanging data comprises also a step S91 of transmitting, by the BS 30 and when the wireless device 25 is in the low power operating mode, the wakeup signal to this wireless device 25 by using the repetition pattern selected by this wireless device 25. Of course, if the indication received from the wireless device 25 is an indication that the reception of the wake-up signal is not possible, then the transmission of the wakeup signal is deactivated for this wireless device 25.

[0126] In some examples, and as illustrated by the non-limitative example of figure 9, the BS 30 may use the received selected repetition pattern without any further verification. However, in other examples, the BS 30 may evaluate other parameters to determine if it can use the received selected repetition pattern to transmit the wake-up signal to this wireless device 25. For example, the BS 30 may take into account its load level and / or its energy consumption in this evaluation. If its load level and / or its energy consumption is low, then the BS 30 may apply the repetition pattern selected by the wireless device 25. However, if its load level and / or its energy consumption is high, the BS 30 may decide to ignore the indication received from the wireless device 25. In such a case, the BS 30 may for example select another repetition pattern or deactivate the transmission of the wake-up signal for the wireless device 25, and it transmits a corresponding indication to this wireless device 25.

Claims

Claims1. A method (80) 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 and to trigger a transition of the MR unit from a low power state to an active state in response to detecting a wake-up signal transmitted by the RAN, wherein, the RAN being adapted to transmit the wake-up signal by using a plurality of repetition patterns, the method comprises:(580) selecting a repetition pattern, among the plurality of repetition patterns,(581) transmitting, to the RAN, an indication of the selected repetition pattern.

2. The method (80) according to claim 1 , wherein the indication of the selected repetition pattern is transmitted to the RAN by using a small data transmission, SDT, procedure, for example a preconfigured SDT, CG-SDT, or a random access SDT, RA-SDT procedure.

3. The method (80) according to any one of the preceding claims, wherein the indication of the selected repetition pattern is transmitted via a physical uplink control channel, PLICCH, or via a medium access control, MAC, control element, CE, or as assistance information.

4. The method (80) according to any one of the preceding claims, comprising estimating (S82) a reception level representative of an expected reception level, by the LP- WUR, of the wake-up signal, wherein the selecting (S80) of the repetition pattern uses the estimated reception level.

5. The method (80) according to claim 4, wherein, if the estimated reception level verifies an out-of-range criterion, the method comprises informing the RAN that the reception of the wake-up signal is not possible at the wireless device.

6. The method (80) according to claim 5, wherein the information that the reception of the wake-up signal is not possible is transmitted as assistance information to the RAN.

7. The method (80) according to any one of the preceding claims, wherein the selecting of the repetition pattern uses a preconfigured mapping between the plurality of repetition patterns and respective associated reception levels.

8. The method (80) according to claim 7, wherein the mapping between the plurality of repetition patterns and their respective associated reception levels is predefined or received in system information broadcasted by the RAN or received in a radio resource control, RRC, message.

9. A wireless device (25) comprising at least one memory (251) and at least oneprocessor (250) configured to carry out a method (80) according to any one of the preceding claims.

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

11. A method (90) 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 low power state to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the method comprises:(590) receiving, from the wireless device, an indication of a repetition pattern selected among a plurality of repetition patterns,(591) transmitting the wake-up signal to the wireless device based on the indication received from said wireless device.

12. The method (90) according to claim 11 , 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.

13. The method (90) according to any one of claims 11 to 12, comprising transmitting to the wireless device a mapping between the plurality of repetition patterns and respective associated reception levels for the wake-up signal.

14. The method (90) according to claim 13, wherein the mapping between the plurality of repetition patterns and their respective associated reception levels for the wake-up signal is included in system information broadcasted by the RAN or in a radio resource control, RRC, message transmitted to the wireless device.

15. A base station, BS (30), comprising at least one memory and at least one processor configured to carry out a method (90) according to any one of claims 11 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 10.

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 8 or a method according to any one of claims 11 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 8 or a method according to any one of claims 11 to 14.

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