Method and device for informing a ran of a wake-up signal monitoring status of a UE using contention-based uplink resources

Abstract

The present disclosure relates to methods and devices for enabling a user equipment, UE (20), to transmit information related to a low power wake-up signal receiver, LP-WUR (254), of a wireless device (25) of the UE.

Description

Method and device for informing a RAN of a wake-up signal monitoring status of a UE using contention-based uplink resourcesTechnical 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 powerstate corresponds to the MR unit being always asleep. However, since the MR unit does not 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] However, there is a need for new signaling methods for enabling the RAN to gather information from UEs having a LP-WUR, for example to know whether a UE has activated wake-up signal reception by its LP-WUR, preferably in a way that would limit overhead and energy consumption at the UE’s side.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 the RAN to know whether a UE has enabled wake-up signal reception by its LP-WUR, in a way that, in some cases at least, limits overhead and energy consumption at the UE’s side.

[0013] 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 unitfrom a very low power state to an active state in response to detecting a wake-up signal transmitted by the RAN, wherein the method comprises transmitting to the RAN information related to the LP-WLIR by using first contention-based uplink resources, wherein the first contention-based resources are separate from second contention-based uplink resources to be used for transmitting information unrelated to the LP-WLIR.

[0014] 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.

[0015] In some embodiments of the method according to the first aspect, the second contention-based uplink resources include random-access channel, RACH, resources to be used by the MR unit to establish a communication with the RAN.

[0016] In some embodiments of the method according to the first aspect, the second contention-based uplink resources include common configured grant, CG, uplink resources to be used by the MR to transmit information unrelated to the LP-WLIR, and the first contention-based uplink resources correspond to separate common CG uplink resources to be used by the wireless device to transmit information related to the LP-WLIR.

[0017] In some embodiments of the method according to the first aspect, the information related to the LP-WLIR is transmitted in a medium access control, MAC, control element, CE.

[0018] In some embodiments of the method according to the first aspect, the information related to the LP-WLIR in encoded in a logical channel identifier, LCID, field of the MAC CE.

[0019] In some embodiments of the method according to the first aspect, the first contention-based uplink resources are split into a plurality of subsets, and the method comprises: selecting a subset of the first contention-based uplink resources, among the plurality of subsets, transmitting the information related to the LP-WLIR by using the selected subset.

[0020] In some embodiments of the method according to the first aspect, the subset to be used is selected randomly among the plurality of subsets of the first contention-based uplink resources.

[0021] In some embodiments of the method according to the first aspect, the subset to be used is selected based on a subset identifier received from the RAN.

[0022] In some embodiments of the method according to the first aspect, the information related to the LP-WLIR, transmitted by using the first contention-based uplink resources, includes a wake-up signal monitoring status of the LP-WLIR.

[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 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 plurality of wireless devices, wherein at least some of the wireless devices are low power, LP, wireless devices, wherein each LP wireless device comprises a main radio, MR, unit and a low power wake-up receiver, LP- WUR, 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: allocating first contention-based uplink resources to the LP wireless devices, to be used by the LP wireless devices for transmitting information related to their LP-WUR, allocating second contention-based uplink resources to the wireless devices, to be used by the wireless devices for transmitting information unrelated to the LP-WUR, wherein the second contention-based uplink resources are separate from the first contention-based uplink resources.

[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 of the method according to the fourth aspect, the second contention-based uplink resources include random-access channel, RACH, resources to be used by the wireless devices to establish a communication with the BS.

[0028] In some embodiments of the method according to the fourth aspect, the second contention-based uplink resources include common configured grant, CG, uplink resources to be used by the wireless devices to transmit information unrelated to the LP-WUR, and the first contention-based uplink resources correspond to separate common CG uplink resources to be used by the LP wireless devices to transmit information related to their LP- WUR.

[0029] In some embodiments of the method according to the fourth aspect, the first contention-based uplink resources are split into a plurality of subsets.

[0030] In some embodiments, the method according to the fourth aspect comprises transmitting to the LP wireless devices a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective subset identifiers and transmitting to each LP wireless device a subset identifier of the subset of the first contention-based uplink resources to be used by said LP wireless device.

[0031] In some embodiments, the method according to the fourth aspect comprises transmitting to the LP wireless devices a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective ranges of values to be used by each LP wireless device to select a subset of the first contention-based uplink resources.

[0032] In some embodiments of the method according to the fourth aspect, the information related to the LP-WUR, transmitted by using the first contention-based uplink resources, includes a wake-up signal monitoring status of the LP-WUR.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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

[0037] 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,Figures 6 and 7: flow charts illustrating other examples of methods for exchanging data implemented by a BS and a wireless device of a UE, respectively.

[0038] 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

[0039] 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.

[0040] 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 theenclosed embodiments will be apparent from the following description.

[0041] 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 20 via radio signals. For example, the RAN may send data to the UEs 20 (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 20 (uplink, UL), which data may be forwarded to the CN.

[0042] 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.

[0043] In the example illustrated by figure 1 , two UEs 20 are represented. The UEs 20 are located in a coverage 31 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.

[0044] 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 20. 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.

[0045] 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.

[0046] 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 ofa 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.

[0047] 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-WLIR, 254.

[0048] 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.

[0049] The LP-WLIR 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-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.

[0050] 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.

[0051] 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.

[0052] As discussed above, the active state corresponds to any state in which the MR unit 253 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 activestate.

[0053] 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-WLIR 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-WLIR 254 can be used to turn the MR unit 253 on.

[0054] It should be noted that, in some examples, the LP-WLIR 254 may also be configured to trigger the MR unit 253 when other conditions are verified. For example, the LP-WLIR 254 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.

[0055] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0056] 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.

[0057] 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.

[0058] 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 whichincludes 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.

[0059] 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.

[0060] 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.

[0061] As discussed above, the present disclosure aims at enabling a BS 30 to gather information about the LP-WURs 254 of the wireless devices 25 in its coverage, for instance to know whether a wireless device 25 in its coverage has enabled its LP-WUR 254 and can detect a wake-up signal transmitted by the BS 30. For example, if a wireless device 25 is willing to transition to the low power operating mode, then it needs to inform the BS 30 that said wireless device 25 starts monitoring the downlink for wake-up signals with its LP-WUR 254. In other words, the wireless device 25 may need to send to the BS 30 a wake-up signal monitoring status of its LP-WUR 254. For example, the wake-up signal monitoring status may indicate that the LP-WUR 254 is activated and ready to detect wake-up signals (e.g., if the wireless device 25 transitions to the low-power operating mode), or that the LP-WUR 254 is disactivated and cannot detect wake-up signals (e.g., if the wireless device 25 transitions to the normal operating mode). The BS 30, upon receiving such a wake-up signal monitoring status received from a wireless device 25, may enable the transmission of wakeup signals to this wireless device 25 (if the wake-up signal monitoring status indicates that the LP-WUR 254 is activated), or disable the transmission of wake-up signals to this wireless device 25 (if the wake-up signal monitoring status indicates that the LP-WUR 254 is disactivated).

[0062] We now present examples of signaling strategies that may be implemented to enable a wireless device 25 equipped with a LP-WUR 254 to transmit information related to its LP-WUR 254 to a BS 30. The present disclosure relates mainly to wireless devices 25 as represented in figure 2, i.e., equipped with a LP-WUR 254 that may transition a MR-unit253 from a low-power state to an active state. Of course, the BS 30 may also have in its coverage 31 UEs 20 having conventional wireless devices, i.e., wireless devices without LP-WURs. In the following, wireless devices 25 equipped with LP-WURs 254 may be referred to as LP wireless devices 25 when required to differentiate from conventional wireless devices which are not equipped with LP-WURs.

[0063] We now provide non-limitative examples of how a (LP) wireless device 25 may provide a BS 30 with information related to its LP-WUR 254.

[0064] Contention-based uplink resources

[0065] 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 LP wireless device 25 of a UE 20.

[0066] As illustrated by figure 4, the method 40 for exchanging data comprises: a step S40 of allocating first contention-based uplink resources to the LP wireless devices 25, to be used by the LP wireless devices 25 for transmitting information related to their LP-WUR 254, a step S41 of allocating second contention-based uplink resources to the wireless devices, i.e., to be used by the wireless devices for transmitting information unrelated to the LP-WUR, wherein the second contention-based uplink resources are separate from the first contention-based uplink resources.

[0067] By “contention-based uplink resources”, we mean uplink resources which are shared by a plurality of wireless devices, on which each of these wireless devices can decide on its own to transmit messages, which messages may therefore collide with messages from other wireless devices with which these uplink resources are shared.

[0068] The first contention-based uplink resources are allocated to the LP wireless devices and may be used by these LP wireless devices 25 to transmit information related to their LP-WURs 254, such as a wake-up signal monitoring status. In some examples, the first contention-based resources may be used only to transmit a wake-up signal monitoring status. In other examples, the first contention-based uplink resources may also be used to transmit, alternatively or in combination thereof, other types of information related to the LP- WURs 254 of the LP wireless devices 25.

[0069] The second contention-based uplink resources are allocated to the wireless devices in general, i.e., to the both the LP wireless devices 25 and the conventional wireless devices in the coverage 31 of the BS 30. The second contention-based uplink resources are used to transmit information that is not related to LP-WURs and are separate from the firstcontention-based resources.

[0070] Hence, the first contention-based uplink resources can be used only by LP wireless devices 25, while the second contention-based uplink resources can be used by both LP wireless devices 25 (e.g., in the normal operating mode) and conventional wireless devices. Accordingly, the first contention-based uplink resources are shared by fewer wireless devices than the second contention-based resources, which reduces the collision probability since only LP wireless devices 25 compete for the first contention-based uplink resources. Reducing the collision probability for transmitting by the LP wireless devices 25 information related to their LP-WURs 254 reduces the need for retransmissions, which therefore reduces also the associated signaling overhead and the associated energy consumption for the LP wireless devices 25.

[0071] Examples of contention-based uplink resources in e.g., a 5G NR wireless communication system include random access channel, RACH, resources, which are used by the wireless devices to establish a communication with the BS 30. Such RACH resources are allocated to the wireless devices regardless their radio resource control, RRC, state. In some examples, the second contention-based uplink resources correspond to the RACH resources allocated by the BS 30 to enable each wireless device (either LP or conventional) in its coverage to initiate a communication with said BS 30. In such a case, the first contention-based uplink resources are separate from the RACH resources shared by all wireless devices and correspond to contention-based uplink resources which can be used only by LP wireless devices 25 to transmit information related to their LP-WURs 254. In some examples, the first contention-based uplink resources may be allocated to all the LP wireless devices 25 regardless their RRC state (e.g., RRC connected (RRC_CONNECTED), RRC idle (RRCJDLE), or RRC inactive (RRCJNACTIVE) state) and may be seen as LP RACH resources to be used by the LP wireless devices 25.

[0072] Other examples of contention-based uplink resources in e.g., a 5G NR wireless communication system include common configured grant, CG, uplink resources. Such common CG uplink resources are for example allocated to wireless devices in RRC_CONNECTED state. By “common”, we mean that these CG uplink resources can be shared by a plurality of wireless devices. In turn, a 5G NR wireless communication system may also allocate dedicated CG uplink resources to a specific wireless device in RRC_CONNECTED state, which are to be used only by this specific wireless device and are therefore not contention-based uplink resources. In some examples, the second contention-based uplink resources correspond to common CG uplink resources and the first contention-based uplink resources correspond for example to separate common CG uplinkresources to be used only by LP wireless device 25 to transmit information related to their LP-WURs 254.

[0073] As illustrated by figure 4, the method 40 for exchanging data comprises a step S42 of transmitting to the LP wireless devices 25 information describing the allocated first contention-based uplink resources. For example, the transmission by the BS 30 of this information describing the allocated first contention-based uplink resources may be a broadcast transmission (for example in the case of LP RACH resources) or it may be a multicast transmission (for example in the case of common CG uplink resources). Also, the method 40 comprises also a step S43 of transmitting to the wireless devices (LP wireless devices 25 and conventional wireless devices) information describing the allocated second contention-based uplink resources. For example, the transmission by the BS 30 of this information describing the allocated second contention-based uplink resources may be a broadcast transmission (for example in the case of RACH resources) or it may be a multicast transmission (for example in the case of common CG uplink resources).

[0074] As illustrated by figure 4, the method 40 for exchanging data comprises then a step S44 of receiving information related to the LP-WURs 254 of the LP wireless devices 25 in the first contention-based uplink resources.

[0075] For example, each LP wireless device 25 may transmit in these first contentionbased uplink resources the wake-up signal monitoring status of its LP-WUR 254, and the BS 30 may use the received wake-up signal monitoring status to control the transmission of a wake-up signal to the LP wireless device 25 from which the wake-up monitoring status has been received. In some examples, the information related to the LP-WUR 254 of an LP wireless device 25 may also include an identifier of this LP wireless device 25 if the identity of the transmitting LP wireless device 25 is not implicit for the BS 30, in order to let the BS 30 know which LP wireless device 25 has e.g., activated or disactivated its LP-WUR 254.

[0076] In some examples, the first contention-based uplink resources are split into a plurality of subsets. Such subsets, which are separate, can be used by different LP wireless devices 25 such that the number of LP wireless devices 25 competing for a specific subset is lower than the total number of LP wireless devices 25 in the coverage 31 of the BS 30, which further reduces collision probability and the need for retransmissions.

[0077] In some examples, the subset of the first contention-based uplink resources to be used by a specific LP wireless device 25 may be selected by the BS 30. In such a case, the BS 30 may transmit a message, to each specific LP wireless device 25 in its coverage 31 , which contains an identifier of the specific subset of the first contention-based uplink resources to be used by this specific LP wireless device 25. For example, an LP wirelessdevice 25 in RRC_CONNECTED state may receive such a subset identifier in a dedicated message.

[0078] In some examples, the BS 30 may transmit beforehand, for example in a broadcast transmission, a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective subset identifiers. Hence, when receiving its subset identifier from the BS 30, a LP wireless device 25 can determine the correspond subset of the first contention-based uplink resources that it can use. Table 1 represents an example of mapping, between the plurality of subsets of the first contention-based uplink resources and the plurality of respective subset identifiers, that can be transmitted by the BS 30 to the LP wireless devices 25 in its coverage 31. In the example of Table 1 , the first contentionbased uplink resources are split into three subsets denoted respectively by R1 , R2 and R3. The identifier of the subset R1 corresponds to ID1 , the identifier of the subset R2 corresponds to ID2 and the identifier of the subset R3 corresponds to ID3. Hence, for each subset identifier, the BS 30 transmits a description of the corresponding subset of first contention-based uplink resources.Table 1

[0079] Table 2 represents an example of subsets identifiers transmitted to five LP wireless devices 25 denoted respectively UE1 , UE2, UE3, UE4 and UE5.Table 2

[0080] Hence, in the example of Table 2:- the LP wireless devices UE1 and UE4 shall use the subset R1 of the first contentionbased uplink resources (subset identifier ID1), the LP wireless devices UE2 and UE5 shall use the subset R2 of the first contentionbased uplink resources (subset identifier ID2), the LP wireless device UE5 shall use the subset R3 of the first contention-based uplink resources (subset identifier ID3).

[0081] In other examples, the subset of the first contention-based uplink resources to be used by a specific LP wireless device 25 may be selected directly by this specific LPwireless device 25. For example, a LP wireless device 25 having received from the BS 30 the description of the plurality of subsets of the first contention-based uplink resources (for example in a broadcast transmission by the BS 30) may select randomly one of the subsets when it needs to transmit information related to its LP-WLIR 254. Such a random selection, based on a previously received description of the subsets of the first contention-based uplink resources, may be carried out in any RRC state of the LP wireless device 25, including when the LP wireless device 25 is in RRC DLE state.

[0082] In some examples, the BS 30 may transmit a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective ranges of values to be used by each LP wireless device 25 to select a subset of the first contentionbased uplink resources. In such a case, a LP wireless device 25 may select randomly a value, and it may select the subset of the first contention-based uplink resources associated to the range to which the selected value belongs. Such features may be used e.g., to introduce ranges of different sizes such that the subset having the greatest range of values associated thereto has a greater probability to be selected than the other subsets. For example, the sizes of the ranges of values may be set according to the respective sizes of the different subsets of the first contention-based uplink resources. For example, the size of a range of values set for a given subset may be proportional to the size of this subset (i.e. , proportional to the number of uplink resources composing this subset).

[0083] Table 3 represents an example of mapping, between the plurality of ranges of values and the plurality of respective subsets R1 , R2 and R3 of the first contention-based uplink resources, that can be transmitted by the BS 30 to the LP wireless devices 25 in its coverage 31. In the example of Table 3, the different ranges and defined by different values V1, V2 and V3 which are such that 0 < V1 < V2 < V3. Hence, if the LP wireless device 25 selects a value between V1 and V2, it will use the subset R2 of the first contention-based resources to transmit the information related to its LP-WUR 254.Table 3

[0084] 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 LP wireless device 25 when the BS 30 implements the method 40 for exchanging data illustrated by figure 4.

[0085] As illustrated by figure 5, the method 50 for exchanging data comprises a step S50of receiving, by the LP wireless device 25, the description of the allocated first contentionbased resources (transmitted by the BS during step S42) and a step S51 of receiving, by the LP wireless device 25, the description of the second contention-based uplink resources (transmitted by the BS during step S43).

[0086] As illustrated by figure 5, when the LP wireless device 25 needs to transmit information related to its LP-WUR 254 to the BS 30, the method 50 for exchanging data comprises a step S52 of transmitting to the BS 30 a message which includes this information related to its LP-WUR 254 by using the first contention-based uplink resources. For example, this information related to its LP-WUR 254 may be transmitted by the LP-WUR 254 (provided that the LP-WUR 254 has transmitting capabilities) or by the MR unit 253.

[0087] As discussed above, the information related to its LP-WUR may consist in a wakeup signal monitoring status indicating whether monitoring of the wake-up signal is activated or disactivated at the LP wireless device 25. The transmission of the information related to the LP-WUR 254 may use any suitable format. In some examples, the information related to the LP-WUR may be transmitted in a medium access control, MAC, control element, CE, e.g., when the LP wireless device 25 is in the RRC_CONNECTED state. For example, the information related to the LP-WUR may be included in a payload of the MAC CE, or it may be encoded in a logical channel identifier, LCID, field of the MAC CE. Indeed, the LCID field may take different values, some of which are currently reserved for future use. Accordingly, it is possible to use some of these reserved LCID values to encode the information related to the LP-WUR 254. For example, one LCID value may be used to indicate that the monitoring of the wake-up signal is activated at the LP wireless device 25, and another different LCID value may be used to indicate that the monitoring of the wake-up signal is disactivated at the LP wireless device 25. As discussed above, the MAC CE may also include an identifier of the LP wireless device 25, for example the cell radio network temporary identifier, C-RNTI, of this LP wireless device 25.

[0088] In the example of figure 5, it is assumed in a non-limitative manner that the first contention-based resources are split into a plurality of subsets. Accordingly, the method 50 for exchanging data comprises a step S53 of selecting a subset of the first contention-based uplink resources, among the plurality of subsets, and the step S52 of transmitting the information related to the LP-WUR uses the selected subset of the first contention-based uplink resources.

[0089] As discussed above, the LP wireless device 25 may for example select the subset to be used based on a subset identifier previously received from the BS 30, or it can select the subset randomly (possibly based on a mapping between the plurality of subsets of thefirst contention-based uplink resources and a plurality of respective ranges of values, previously configured, for instance previously received from the BS 30).

[0090] Scheduling request resources

[0091] 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.

[0092] As illustrated by figure 6, the method 60 for exchanging data comprises a step S60 of allocating scheduling request, SR, resources to a wireless device 25.

[0093] Such SR resources are resources which are dedicated to a given wireless device, which therefore cannot be used by other wireless devices. Such SR resources can for example be allocated by the BS 30 to a wireless device 25 in an RRC_CONNECTED state or in an RRCJNACTIVE state. Basically, a SR message is a physical layer message that can be sent by the wireless device 25, in the SR resources, to notify the BS 30 that it has UL data to be transmitted. In response to receiving a SR message from the wireless device 25, the BS 30 may transmit an UL grant to the wireless device 25.

[0094] As illustrated by figure 6, the method 60 for exchanging data comprises then a step561 of transmitting, to the wireless device 25, a description of the SR resources allocated by the BS 30 to this wireless device 25.

[0095] As illustrated by figure 6, the method 60 for exchanging data comprises then a step562 of receiving, from the wireless device 25 and in the SR resources allocated to said first wireless device 25, a SR message which includes information related the LP-WUR 25 of said wireless device 25. A BS 30 which receives a SR message from a wireless device 25 can determine which specific wireless device 25 has transmitted it based e.g., on the SR dedicated resources used, and therefore can identify the specific wireless device 25 to which the received LP-WUR-related information applies.

[0096] Hence, the information related to the LP-WUR 254 is received by using pre-allocated resources for transmitting SR messages, such that no specific signaling overhead is required to obtain resources for transmitting such LP-WUR-related information, thereby also limiting the energy consumption of the wireless device 25.

[0097] As discussed above, the BS 30 may then control the transmission of the wake-up signal to this wireless device 25 based on the received information related to the LP-WUR 254 of this wireless device 25. For example, if the wireless device 25 indicates that it has activated the monitoring of the wake-up signal (e.g., due to a transition to the low-power operating mode), the BS 30 may enable the transmission of the wake-up signal if neededto wake-up the MR unit 253 of this wireless device 25.

[0098] 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 when the BS 30 implements the method 60 for exchanging data illustrated by figure 6.

[0099] As illustrated by figure 7, the method 70 for exchanging data comprises a step S70 of receiving, by the wireless device 25, the description of the allocated SR resources, transmitted by the BS 30 during step S61.

[0100] As illustrated by figure 7, when the wireless device 25 needs to transmit information related to its LP-WLIR 254 to the BS 30, the method 70 for exchanging data comprises a step S71 of transmitting to the BS 30 a SR message which includes this information related to its LP-WLIR 254 by using the allocated SR resources. For example, this information related to its LP-WLIR 254 may be transmitted by the LP-WLIR 254 (provided that the LP- WUR 254 has transmitting capabilities) or by the MR unit 253.

[0101] As discussed above, the information related to its LP-WLIR may consist in a wakeup signal monitoring status indicated whether monitoring of the wake-up signal is activated or disactivated at the wireless device 25. The transmission of the information related to the LP-WLIR 254 may use any suitable format. For example, it is possible to add one bit to the SR message, that can be used to encode e.g., the wake-up signal monitoring status of the LP-WLIR 254 of the wireless device 25. For example, a bit value T may be used to indicate that the monitoring of the wake-up signal is activated at the LP wireless device 25, and a bit value ‘0’ may be used to indicate that the monitoring of the wake-up signal is disactivated at the LP wireless device 25. Hence, in some examples, the LP-WUR-related information may consist in a single bit, which therefore limits the signaling overhead and limits the energy consumption of the wireless device 25.

[0102] It is emphasized that the present disclosure is not limited to the above exemplary embodiments. Variants of the above exemplary embodiments are also within the scope of the present disclosure.

[0103] For example, the invention has been described by considering mainly LP-WUR- related information consisting in a wake-up signal monitoring status of the LP-WUR 254. In other examples, it is also possible to consider, alternatively or in combination thereof, other types of LP-WUR-related information. For example, it is possible to transmit an information representative of a duration during which the monitoring of the wake-up signal will be activated, an information representative of a reception level of the wake-up signal, etc.

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 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 RAN, wherein the method comprises (S52) transmitting to the RAN information related to the LP-WLIR by using first contention-based uplink resources, wherein the first contention-based resources are separate from second contention-based uplink resources to be used for transmitting information unrelated to the LP-WLIR.

2. The method (50) according to claim 1 , wherein the second contention-based uplink resources include random-access channel, RACH, resources to be used by the MR unit to establish a communication with the RAN.

3. The method (50) according to any one of the preceding claims, wherein the second contention-based uplink resources include common configured grant, CG, uplink resources to be used by the MR to transmit information unrelated to the LP-WLIR, and the first contention-based uplink resources correspond to separate common CG uplink resources to be used by the wireless device to transmit information related to the LP-WLIR.

4. The method (50) according to claim 3, wherein the information related to the LP- WUR is transmitted in a medium access control, MAC, control element, CE.

5. The method (50) according to claim 4, wherein the information related to the LP- WUR in encoded in a logical channel identifier, LCID, field of the MAC CE.

6. The method (50) according to any one of the preceding claims, wherein the first contention-based uplink resources are split into a plurality of subsets, and the method comprises:(S53) selecting a subset of the first contention-based uplink resources, among the plurality of subsets,(S52) transmitting the information related to the LP-WLIR by using the selected subset.

7. The method (50) according to claim 6, wherein the subset to be used is selected randomly among the plurality of subsets of the first contention-based uplink resources.

8. The method (50) according to claim 6, wherein the subset to be used is selected based on a subset identifier received from the RAN.

9. The method (50) according to any one of the preceding claims, wherein the information related to the LP-WUR, transmitted by using the first contention-based uplink resources, includes a wake-up signal monitoring status of the LP-WUR.

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

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

12. 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 plurality of wireless devices, wherein at least some of the wireless devices are low power, LP, wireless devices (25), wherein each LP wireless device (25) comprises a main radio, MR, unit (253) and a low power wake-up 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:(540) allocating first contention-based uplink resources to the LP wireless devices, to be used by the LP wireless devices for transmitting information related to their LP-WUR,(541 ) allocating second contention-based uplink resources to the wireless devices, to be used by the wireless devices for transmitting information unrelated to the LP- WUR, wherein the second contention-based uplink resources are separate from the first contention-based uplink resources.

13. The method (40) according to claim 12, wherein the second contention-based uplink resources include random-access channel, RACH, resources to be used by the wireless devices to establish a communication with the BS.

14. The method (40) according to any one of claims 12 to 13, wherein the second contention-based uplink resources include common configured grant, CG, uplink resources to be used by the wireless devices to transmit information unrelated to the LP-WUR, and the first contention-based uplink resources correspond to separate common CG uplink resources to be used by the LP wireless devices to transmit information related to their LP- WUR.

15. The method (40) according to any one of claims 12 to 14, wherein the first contention-based uplink resources are split into a plurality of subsets.

16. The method (40) according to claim 15, comprising transmitting to the LP wirelessdevices a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective subset identifiers, and transmitting to each LP wireless device a subset identifier of the subset of the first contention-based uplink resources to be used by said LP wireless device.

17. The method (40) according to claim 15, comprising transmitting to the LP wireless devices a mapping between the plurality of subsets of the first contention-based uplink resources and a plurality of respective ranges of values to be used by each LP wireless device to select a subset of the first contention-based uplink resources.

18. The method (40) according to any one of claims 12 to 17, wherein the information related to the LP-WUR, transmitted by using the first contention-based uplink resources, includes a wake-up signal monitoring status of the LP-WUR.

19. 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 12 to 18.

20. A wireless communication system comprising at least one base station (30) according to claim 19 and at least one user equipment (20) according to claim 11 .

21. A computer program product (252, 302) comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method (50) according to any one of claims 1 to 9 or a method (40) according to any one of claims 12 to 18.

22. 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 (50) according to any one of claims 1 to 9 or a method (40) according to any one of claims 12 to 18.

Images