Method and device for performing energy saving in a ue performing a scheduling request procedure

Abstract

The present disclosure relates to methods and devices for enabling a user equipment, UE (20), having a low power wake-up signal receiver, LP-WUR (254), to reduce its energy consumption during a scheduling request procedure.

Description

Method and device for performing energy saving in a UE performing a scheduling request procedureTechnical 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, discontinuous reception, DRX, has been introduced in 3GPP (Third Generation Partnership Project) wireless communication systems. Basically, in DRX, 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 control 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.

[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 DRX 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 a state in which the MR unit can exchange data with a radio access network, RAN, of the wireless communication system. The low power state corresponds to any state in which the MR unit cannot exchange data with the RAN.

[0007] 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.

[0008] By “low power” wake-up receiver, we mean that the LP-WUR is used for receiving a wake-up signal while the MR unit is in a low power state. Of course, the monitoring of thewake-up signal should be done with a low power consumption, and the mean power consumption of the LP-WUR 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 in the active state.

[0009] 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 possibly awakened by the LP-WLIR at any time, thereby further enabling low latency.

[0010] However, there is a need for further reducing energy consumption in specific procedures, for example in the scheduling request, SR, procedure.

[0011] The SR procedure enables a UE to request uplink, UL, resources for transmitting data to the RAN. For that purpose, a UE may be allocated with SR resources which may be used by the UE to transmit an UL request (for requesting additional UL resources for an upcoming transmission). Such SR resources can for example be allocated by the RAN to a UE in a radio resource control, RRC, connected state (RRC_CONNECTED) or in an RRC inactive state (RRCJNACTIVE). Basically, the UL request is a physical layer message that can be sent by the UE, in the SR resources, to notify the RAN that it has UL data to be transmitted. In response to receiving such an SR-related UL request from the UE, the RAN may transmit a DL response to this UE via the PDCCH, which includes an UL grant indicating the UL resources granted to the UE for the upcoming transmission.

[0012] Once the UE transmits the SR-related UL request, it starts a timer (sr-ProhibitTimer) which defines a DL response period during which the DL response (containing the UL grant) can be received from the RAN. The UE does not know when the DL response will be received, so it needs to monitor continuously the PDCCH until the DL response is received. Hence, in some cases, the UE may have to monitor for almost the whole duration of the DL response period (i.e., for the whole duration of the sr-ProhibitTimer). For example, when different logical channels (LCH) having different respective priorities are defined, the UL request may use SR resources of an SR configuration mapped with a low priority LCH. In such a case, the DL response will not be prioritized by the RAN and might be transmitted only towards the end of the DL response period, while the UE starts PDCCH monitoring directly at the beginning of the DL response period.Summary

[0013] 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 discussedabove. In particular, the present disclosure aims at proposing a solution for reducing the duration during which the MR unit needs to remain in the active state within a DL response period used to transmit a DL response to an uplink request transmitted during a scheduling request procedure.

[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-WLIR, configured to monitor a wake-up signal transmitted by the RAN and to trigger a transition of the MR unit to an active state in response to detecting a wake-up signal, wherein the wireless device is configured to perform a scheduling request, SR, procedure by transmitting an uplink, UL, request via SR resources to the RAN, and by receiving a downlink, DL, response indicating granted UL resources via a physical downlink control channel, PDCCH, within a DL response period, wherein the DL response period comprises an inactive subperiod followed by an active subperiod and the method comprises, during the DL response period: performing wake-up signal monitoring by the LP-WUR during the inactive subperiod, with the MR unit in a low power state, in response to detecting a wake-up signal during the inactive subperiod: triggering a transition of the MR unit to the active state and performing PDCCH monitoring during the active subperiod.

[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, in response to not detecting a wake-up signal during the inactive subperiod, the MR unit is maintained in the low power state during the active subperiod.

[0017] In some embodiments of the method according to the first aspect, in response to not detecting a wake-up signal during the inactive subperiod, the LP-WUR does not perform wake-up signal monitoring during the active period.

[0018] In some embodiments, the method according to the first aspect comprises receiving a DL response period configuration defining the inactive subperiod and the active subperiod within the DL response period.

[0019] In some embodiments of the method according to the first aspect, the DL response period configuration is received in system information broadcasted by the RAN and / or theDL response period configuration is received in a radio resource control, RRC, message transmitted by the RAN.

[0020] In some embodiments of the method according to the first aspect, the DL response period comprises a plurality of active subperiods and / or the DL response period comprises a plurality of inactive subperiods.

[0021] In some embodiments, the method according to the first aspect comprises receiving from the RAN an indication of whether the DL response period starts with an active subperiod or with an inactive subperiod.

[0022] In some embodiments of the method according to the first aspect, the indication is received in system information broadcasted by the RAN and / or the indication is received in a radio resource control, RRC, message transmitted by the RAN.

[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 wireless device, wherein the wireless device comprises a main radio, MR, unit and a low power wake-up receiver, LP-WUR, wherein the LP-WUR is configured to detect a wake-up signal transmitted by the BS and to trigger a transition of the MR unit to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the BS is configured to perform a scheduling request, SR, procedure by monitoring SR resources for receiving an uplink, UL, request from the wireless device and, in response to detecting an UL request from the wireless device, by transmitting a downlink, DL, response indicating granted UL resources via a physical downlink control channel, PDCCH, within a DL response period, wherein the DL response period comprises at least on inactive subperiod and at least one active subperiod, and wherein the BS is configured to transmit the DL response to the wireless device, via the PDCCH, only in the at least one active subperiod of the DL response period.

[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, in response to determining that the DL response is to be transmitted in an active subperiod which follows an inactive subperiod of the DL response period: transmitting a wake-up signal to the wireless device in said inactive subperiod.

[0028] In some embodiments, the method according to the fourth aspect comprises transmitting a DL response period configuration to the wireless device, wherein the DL response period configuration defines the at least one inactive subperiod and the at least one active subperiod within the DL response period.

[0029] In some embodiments of the method according to the fourth aspect, the DL response period configuration is transmitted in system information broadcasted by the RAN and / or the DL response period configuration is transmitted in a radio resource control, RRC, message transmitted to the wireless device.

[0030] In some embodiments, the method according to the fourth aspect comprises transmitting to the wireless device an indication of whether the DL response period starts with an active subperiod or with an inactive subperiod.

[0031] In some embodiments of the method according to the fourth aspect, the indication is transmitted in system information broadcasted by the RAN and / or the indication is transmitted in a radio resource control, RRC, message transmitted by the RAN.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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 fortransmitting control messages according to any one of the embodiments of the present disclosure.Brief description of figures

[0036] 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,Figure 4: schematic representations of examples of different DL response period configurations,Figure 5: a schematic representation illustrating the operation of a wireless device during a DL response period,Figures 6 and 7: flow charts illustrating examples of methods for exchanging data implemented by a BS and a wireless device of a UE, respectively.

[0037] 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

[0038] 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.

[0039] 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 / orwith 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.

[0040] 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.

[0041] 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.

[0042] 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 for example to the area in which UEs can decode a PDCCH transmitted by the BS 30.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The LP-WUR 254 corresponds to a secondary wireless communication unit of the wireless device 25, that is used to monitor a wake-up signal, transmitted by BSs 30 of the RAN, with low power consumption. The wake-up signal may take any form enabling it to be detected with low power consumption. Non-limitative examples for the wake-up signal and the LP-WUR 254 are provided in the technical report TR 38.869. It should be noted that, in some examples, the wake-up signal can even be a specific 5G NR signal, for instance using a low-level modulation and coding scheme, MCS, in which case the LP-WUR 254 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.

[0049] As discussed above, the purpose of the LP-WUR 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-WUR 254 may be only unidirectional, i.e. , with only receiving capabilities (DL) and no transmitting capabilities (UL). However, in some examples, the LP-WUR 254 may also have transmitting capabilities, such that it can also transmit (UL) data to the RAN.

[0050] 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-WLIR 254 is configured to trigger a transition to the normal operating mode in response to detecting a wake-up signal transmitted by the RAN.

[0051] 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-WLIR.

[0052] 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 example, 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. Also, it should be noted that it is possible to consider different low power states for the MR unit 253, having different respective mean power consumptions. For example, it is possible to consider a very low power state, having the lowest mean power consumption, and one or more intermediate low power states having a mean power consumption greater than the mean power consumption of the very low power state. For example, the very low power state may correspond to the MR unit 253 being turned off, and an intermediate low power state may correspond to the MR unit 253 being asleep without being turned off.

[0053] 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-WLIR254 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 a low power state over long periods.

[0054] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0055] 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 CPU, a DSP, an FPGA, an 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 program-code instructions to be executed by the one or more processors 300 to implement all or part of the steps of a method forexchanging data, performed at the RAN’s side, according to any one of the embodiments disclosed herein.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] As discussed above, the present disclosure aims at further reducing the energy consumption of the wireless device 25 when performing a SR procedure.

[0061] As discussed above, during a SR procedure, the wireless device 25 typically uses SR resources to transmit an uplink, UL, request to the RAN (for requesting UL resources for an upcoming transmission), and the RAN may transmit a downlink, DL, response to the wireless device 25, via the PDCCH, during a DL response period (e.g., defined by the sr- ProhibitTimer). The DL response includes an indication of the granted UL resources, if any. Such SR resources can for example be allocated by the RAN to a wireless device 25 in RRC_CON NESTED state or in an RRCJNACTIVE state.

[0062] For example, the SR-related UL request is transmitted by the MR unit 253 in the active state. However, in other examples, the UL request may be transmitted by the LP-WUR 254 (provided the LP-WLIR 254 has transmitting capabilities), in which case the MR unit 253 may be in a low power state when the LP-WLIR 254 transmits the UL request.

[0063] To reduce the need for maintaining the MR unit 253 in the active state during a DL response period of a SR procedure, it is proposed to split the DL response period (e.g., defined by the sr-ProhibitTimer) into a plurality of subperiods which include: one or more inactive subperiods during which the RAN cannot transmit a DL response to the wireless device 25, and one or more active subperiods during which the RAN may transmit a DL response to the wireless device 25.

[0064] Since no DL response can be received during an inactive subperiod of the DL response period, the MR unit 253 of the wireless device 25 may be put in a low power state during each inactive subperiod of the DL response period, such that the MR unit 253 no longer needs to be in the active state during the whole duration of the DL response period. Also, and as will be discussed below, if the DL response period includes an active subperiod which follows an inactive subperiod, the RAN may use said inactive subperiod to indicate whether said RAN intends to send the DL response during the following active subperiod. For instance, such an indication may be sent as a wake-up signal to be detected by the LP- WUR 254 of the wireless device 25. Hence, if a wake-up signal is detected during an inactive subperiod of the DL response period, the MR unit 253 may transition to the active state for the following active subperiod of the DL response period. In turn, if no wake-up signal is detected during an inactive subperiod, the MR unit 253 may remain in a low power state during the following active subperiod. Also, in some cases, if no wake-up signal is detected by the LP-WUR 254 during an inactive subperiod of the DL response period, then the LP-WUR 254 may also transition to a low-power state (e.g., turned off) for the duration of the following active subperiod of the DL response period, to further reduce energy consumption during the DL response period. In some examples, the LP-WUR 254 may also be placed in a low power state (e.g., turned off) during all active subperiods of the DL response period.

[0065] As discussed above, the DL response period may comprise one or more active subperiods and one or more inactive subperiods, arranged such that the DL response period is composed of an alternation of active subperiod(s) and inactive subperiod(s). In other words, an active subperiod cannot be immediately followed or preceded by another active subperiod, and an inactive subperiod cannot be immediately followed or preceded by another inactive subperiod. Preferably, an inactive subperiod is always followed by an active subperiod, to be able to indicate to the wireless device 25 whether its MR unit 253 needs tobe put in the active state for said following active subperiod.

[0066] Figure 4 represents schematically different examples of DL response period configurations.

[0067] In the example illustrated by part a) of Figure 4, the DL response period comprises a single inactive subperiod followed by a single active subperiod.

[0068] In the example illustrated by part b) of Figure 4, the DL response period comprises three subperiods. More specifically, the DL response period starts with a first active subperiod, followed by an inactive subperiod, followed by a second active subperiod.

[0069] In the example illustrated by part c) of Figure 4, the DL response period comprises four subperiods. More specifically, the DL response period starts with a first inactive subperiod, followed by a first active subperiod, followed by a second inactive subperiod, followed by a second active subperiod.

[0070] In the example illustrated by part d) of Figure 4, the DL response period comprises five subperiods. More specifically, the DL response period starts with a first active subperiod, followed by a first inactive subperiod, followed by a second active subperiod, followed by a second inactive subperiod, followed by a third active subperiod.

[0071] In some examples, it is possible to consider an identical duration for all inactive subperiods and for all active subperiods. However, it is also possible to consider a duration for the inactive subperiods that is different from the duration of the active subperiods. Also, the inactive subperiods may have all the same duration, or the duration may vary from one inactive subperiod to another. Similarly, the active subperiods may have all the same duration, or the duration may vary from one active subperiod to another.

[0072] Other DL response period configurations can be considered, for example comprising additional active subperiods and / or additional inactive subperiods compared to the examples provided in figure 4. The choice of a specific DL response period configuration corresponds to a specific but non-limitative embodiment of the present disclosure.

[0073] In some examples, the DL response period configuration may be predefined. In other examples, the DL response period configuration may be set by the wireless device 25, or by the RAN. In the latter case, the DL response period configuration to be used by the wireless device 25 is for instance received by the wireless device 25 in system information broadcasted by a BS 30 of the RAN and / or received in a radio resource control, RRC, message transmitted by a BS 30 of the RAN (for example a RRC reconfiguration message). Of course, other control messages can be used by the RAN to transmit a DL response period configuration to the wireless device 25.

[0074] In some cases, the RAN may also transmit to the wireless device 25, included in theDL response period configuration, or separately from the DL response period configuration, an indication of whether the DL response period starts with an active subperiod or with an inactive subperiod. If such an indication (of whether the DL response period starts with an active subperiod or with an inactive subperiod) is transmitted separately from the DL response period configuration, the structure of the DL response period can be dynamically adapted by modifying only the type of subperiod which starts the DL response period, i.e. , either an inactive subperiod or an active subperiod. Such an indication may for example be included in system information broadcasted by the RAN and / or in a radio resource control, RRC, message transmitted by the RAN. Such an indication may for instance consist in a single bit. For example, a value of ‘0’ may be used to indicate that the DL response period starts with an inactive subperiod while a value of T may be used to indicate that the DL response period starts with an active subperiod.

[0075] It should be noted that a BS 30 may set the same DL response period configuration for all the UEs 20 in its coverage 31 , or it can set different DL response period configurations to all or part of the UEs 20 in its coverage 31. For example, the BS 31 may set UE-specific DL response period configurations. In some cases, the BS 30 may also modify the DL response period configuration(s) based on its current or predicted load / traffic.

[0076] Figure 5 represents schematically a non-limitative example of how the wireless device 25 may reduce its energy consumption, by assuming in a non-limitative manner the DL response period configuration represented in part d) of figure 4.

[0077] As illustrated by figure 5, the wireless device 25 transmits an UL request at a time TO. This UL request is for example transmitted by the MR unit 253 in the active state.

[0078] Accordingly, the wireless device 25 considers that it might receive a DL response (including an UL grant) during a subsequent DL response period.

[0079] If the DL response period is defined by a timer (e.g., sr-ProhibitTimer), it may start immediately after the transmission of the UL request. In the non-limitative example of figure 5, the DL response period is however slightly delayed with respect to TO. Of course, in other examples, the DL response period may start directly at TO.

[0080] Since the DL response period starts with a first active subperiod, the MR unit 253 is in the active state for the duration of the first active subperiod, during which the wireless device 25 may receive a DL response via the PDCCH. However, in the non-limitative example illustrated by figure 5, no DL response is received during the first active subperiod.

[0081] Since no DL response is to be received during the first inactive subperiod, the MR unit 253 may be put in a low power state for the duration of the first inactive subperiod. However, the LP-WUR 254 performs wake-up signal monitoring during the first inactivesubperiod. In the example illustrated by figure 5, no wake-up signal is detected during the first inactive subperiod, which means that the RAN does not intend to transmit a DL response during the following subperiod, i.e. , the second active subperiod. Accordingly, the MR unit 253 does not need to perform PDCCH monitoring and may be kept in a low power state during the second active subperiod. Also, the LP-WLIR 254 does not need to perform wake-up signal monitoring during the second active subperiod. Accordingly, the LP-WLIR 254 may be placed in a low power state during the second active subperiod. For example, the LP-WLIR 254 may be turned off during the second active subperiod. In some examples, and as illustrated in a non-limitative manner in figure 5, the LP-WLIR 254 may also be placed in a low power state (e.g., turned off) during all active subperiods of the DL response period.

[0082] Since no DL response is to be received during the second inactive subperiod, the MR unit 253 may remain in a low power state for the duration of the second inactive subperiod. However, the LP-WUR 254 performs wake-up signal monitoring during the second inactive subperiod. In the example illustrated by figure 5, the LP-WUR 254 detects a wake-up signal at a time T1 within the second inactive subperiod, which means that the RAN may transmit the DL response during the following active subperiod, i.e., the third active subperiod. Accordingly, the LP-WUR 254 transitions the MR unit 253 to the active state for the duration of the third active subperiod, during which the wireless device 25 may receive a DL response to its UL request. In the non-limitative example illustrated by figure 5, the MR unit 253 receives the DL response (including an UL grant) at a time T2.

[0083] 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. It should be noted that figures 6 and 7 show only a single inactive subperiod and a single active subperiod, but the corresponding steps can also be repeated if the DL response period comprises more than one inactive subperiod and / or more than one active subperiod.

[0084] As discussed above, the DL response period comprises one or more inactive subperiods and one or more active subperiods, and the BS 30 is configured to transmit a DL response to an UL request to the wireless device 25 of a UE 20 only in active subperiod(s). In other words, no DL response can be transmitted to the wireless device 25 during inactive subperiods of the DL response period.

[0085] In the non-limitative example illustrated by figure 6, the method 60 for exchanging data comprises, during an inactive subperiod of the DL response period, a step S60 of evaluating whether a DL response (including an UL grant) is to be transmitted via thePDCCH to the wireless device 25 in the following active subperiod. If DL response is to be transmitted via the PDCCH in the following active subperiod (reference S60a in figure 6), the method 60 for exchanging data comprises a step S61 of transmitting a wake-up signal to the wireless device 25 in the current inactive subperiod and a step S62 of transmitting the DL response to the wireless device 25 during the following active subperiod, via the PDCCH. In turn (reference S60b in figure 6), no wake-up signal is transmitted during the current inactive subperiod (and no DL response is transmitted to the wireless device 25 during the following active subperiod).

[0086] As discussed above, the DL response period is typically triggered by the wireless device 25 transmitting an UL request by using SR resources. As illustrated by figure 6, the method 60 for exchanging data comprises a step S63 of monitoring the SR resources for an UL request. If an UL request is detected (reference S63a in figure 6), a DL response period is triggered. In turn (reference S63b in figure 6), no DL response period is triggered.

[0087] In some examples, and as illustrated in the non-limitative example of figure 6, the method 60 for exchanging data comprises a step S64 of transmitting a DL response period configuration to the wireless device 25. As discussed above, the DL response period configuration may be transmitted e.g., in system information broadcasted by the BS 30 and / or in a radio resource control, RRC, message transmitted to the wireless device 25. As discussed above an indication of whether the DL response period starts by an inactive period or by an active period may also be transmitted to the wireless device 25.

[0088] 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.

[0089] As illustrated by figure 7, the method 70 for exchanging data comprises, during a DL response period, a step S70 of performing wake-signal monitoring during an inactive subperiod, by the LP-WUR 254 (while the MR unit 253 is in a low power state). If no wakeup signal is detected during the current inactive subperiod (reference S70b in figure 7) no PDCCH monitoring is performed during the following active subperiod, and the MR unit 253 may be maintained in a low power state for the duration of the following active subperiod (and, in some examples, the LP-WUR 254 does not perform wake-up signal monitoring during the following active subperiod and may be placed in a low power state). In turn (reference S70a in figure 7), the method 70 for exchanging data comprises a step S71 of triggering a transition of the MR unit 253 to the active state and a step S72 of performing PDCCH monitoring during the following active subperiod, for receiving the DL responseindicating the granted UL resources.

[0090] As discussed above, the DL response period is typically triggered by the wireless device 25 transmitting an UL request via SR resources. As illustrated by figure 7, the method 70 for exchanging data comprises a step S73 of evaluating whether an UL request is to be transmitted to the RAN. If an UL request is to be transmitted (reference S73a in figure 7), the method 70 for exchanging data comprises a step S74 of transmitting the UL request by using the SR resources, which triggers a DL response period. In turn (reference S73b in figure 7), no DL response period is triggered.

[0091] In some examples, and as illustrated by the figure 7, the method 70 for exchanging data comprises a step S75 of receiving a DL response period configuration from the RAN, to be used during the DL response period(s). As discussed above, the DL response period configuration is for example received in system information broadcasted by the RAN and / or in a radio resource control, RRC, message transmitted by the RAN. As discussed above, the wireless device 25 may also receive from the RAN an indication of whether the DL response period starts by an inactive period or by an active period.

[0092] 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.

Claims

Claims1. A method (70) 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 monitor a wake-up signal transmitted by the RAN and to trigger a transition of the MR unit to an active state in response to detecting a wake-up signal, wherein the wireless device (25) is configured to perform a scheduling request, SR, procedure by transmitting an uplink, UL, request via SR resources to the RAN, and by receiving a downlink, DL, response indicating granted UL resources via a physical downlink control channel, PDCCH, within a DL response period, wherein the DL response period comprises an inactive subperiod followed by an active subperiod and the method comprises, during the DL response period:(S70) performing wake-up signal monitoring by the LP-WUR (254) during the inactive subperiod, with the MR unit in a low power state, in response to detecting a wake-up signal during the inactive subperiod: (S71) triggering a transition of the MR unit to the active state and (S72) performing PDCCH monitoring during the active subperiod.

2. The method (70) according to claim 1 , wherein, in response to not detecting a wake-up signal during the inactive subperiod, the MR unit is maintained in the low power state during the active subperiod.

3. The method (70) according to claim 2, wherein, in response to not detecting a wake-up signal during the inactive subperiod, the LP-WUR does not perform wake-up signal monitoring during the active period.

4. The method (70) according to any one of the preceding claims, comprising (S75) receiving a DL response period configuration defining the inactive subperiod and the active subperiod within the DL response period.

5. The method (70) according to claim 4, wherein the DL response period configuration is received in system information broadcasted by the RAN and / or the DL response period configuration is received in a radio resource control, RRC, message transmitted by the RAN.

6. The method (70) according to any one of the preceding claims, wherein the DL response period comprises a plurality of active subperiods and / or the DL response period comprises a plurality of inactive subperiods.

7. The method (70) according to any one of the preceding claims, comprisingreceiving from the RAN an indication of whether the DL response period starts with an active subperiod or with an inactive subperiod.

8. The method (70) according to claim 7, wherein the indication is received in system information broadcasted by the RAN and / or the indication is received in a radio resource control, RRC, message transmitted by the RAN.

9. A wireless device (25) comprising at least one memory (251) and at least one processor (250) configured to carry out a method (70) 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 (60) 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), wherein the wireless device 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 to an active state in response to detecting a wake-up signal transmitted by the BS, wherein the BS (30) is configured to perform a scheduling request, SR, procedure by monitoring SR resources for receiving an uplink, UL, request from the wireless device and, in response to detecting an UL request from the wireless device, by transmitting a downlink, DL, response indicating granted UL resources via a physical downlink control channel, PDCCH, within a DL response period, wherein the DL response period comprises at least on inactive subperiod and at least one active subperiod, and wherein the BS is configured to transmit the DL response to the wireless device, via the PDCCH, only in the at least one active subperiod of the DL response period.

12. The method (60) according to claim 11 , comprising, in response to determining that the DL response is to be transmitted in an active subperiod which follows an inactive subperiod of the DL response period: (S61) transmitting a wake-up signal to the wireless device in said inactive subperiod.

13. The method (60) according to any one of claims 11 to 12, comprising (S64) transmitting a DL response period configuration to the wireless device, wherein the DL response period configuration defines the at least one inactive subperiod and the at least one active subperiod within the DL response period.

14. The method (60) according to claim 13, wherein the DL response period configuration is transmitted in system information broadcasted by the RAN and / or the DL response period configuration is transmitted in a radio resource control, RRC, messagetransmitted to the wireless device.

15. The method (60) according to any one of claims 11 to 14, comprising transmitting to the wireless device an indication of whether the DL response period starts with an active subperiod or with an inactive subperiod.

16. The method (60) according to claim 15, wherein the indication is transmitted in system information broadcasted by the RAN and / or the indication is transmitted in a radio resource control, RRC, message transmitted by the RAN.

17. A base station, BS (30), comprising at least one memory (301) and at least one processor (300) configured to carry out a method (60) according to any one of claims 11 to 16.

18. A wireless communication system comprising at least one base station (30) according to claim 17 and at least one user equipment (20) according to claim 10.

19. 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 (70) according to any one of claims 1 to 8 or a method (60) according to any one of claims 11 to 16.

20. 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 (70) according to any one of claims 1 to 8 or a method (60) according to any one of claims 11 to 16.

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