Method and device for efficient uplink resource allocation for an ambient-iot device based on a predicted buffer status report

Abstract

The present disclosure relates to methods and devices for enabling an efficient allocation of uplink resources to a user equipment, UE (20), having a wireless device (25) comprising an energy harvesting unit (254) for collecting ambient energy, by providing a radio access network, RAN, with a predicted buffer status report, PBSR.

Description

Method and device for efficient uplink resource allocation for an ambient-loT device based on a predicted buffer status reportTechnical field

[0001] The present disclosure relates to wireless communication systems and relates more specifically to methods and devices for enabling an efficient allocation of uplink resources to a wireless device having ultra-low power consumption, by transmitting a predicted buffer status report to a radio access network, RAN.Background

[0002] The internet of things (loT) allows various devices to connect to the internet to send data, receive instructions, or both. Tens of billions of loT devices are already deployed and the global number of loT devices is expected to increase rapidly. Thus, massive connectivity is needed. However, powering these billions of loT devices is a critical challenge, and deploying power cables or regularly replacing / recharging batteries is not a viable solution.

[0003] 3GPP (Third Generation Partnership Project) is investigating new loT technologies to open new markets within 3GPP systems, whose number of connections and / or device density can be orders of magnitude higher than existing 3GPP loT technologies, and which can provide complexity and power consumption orders-of-magnitude lower than existing 3GPP technologies such as narrow-band-loT (NB-loT) and long-term evolution-machine- type communications (LTE-MTC). More specifically, 3GPP is currently defining Ambient- loT (A-loT) technologies (see e.g., the technical report TR 38.848 V18.0.0) aiming at enabling ultra-low power consumption loT devices, which could be either batteryless devices with no energy storage capability (performing backscattering transmission) or devices with energy storage that do not need to be replaced or recharged manually (performing wire-free energy harvesting (EH) from one or more energy sources).

[0004] By “ultra-low power consumption” devices, or “A-loT” devices, we mean devices having a peak power consumption lower than 1 mW, or even lower than 100 pW or lower than 10 pW. For instance, Ambient-loT currently aims at enabling A-loT devices having the following characteristics: around 1 pW peak power consumption with energy storage, with neither downlink (DL) nor uplink (UL) amplification in the device (the device’s UL transmission is backscattered on a carrier wave provided externally), below a few hundred pW peak power consumption with energy storage, with DL and / or UL amplification in the device (the device’s UL transmission may be generated internally by the device or be backscattered on a carrier wave providedexternally).

[0005] Currently, a user equipment, UE, willing to obtain the dynamic allocation of uplink resources may rely on the buffer status reporting procedure defined in TS 38.321 V18.0.0. The buffer status reporting procedure (BSR) is used to provide the serving base station (gNB) with information about an uplink data volume present at the UE, that the UE would like to transmit to the gNB. This enables the gNB to make informed decisions regarding scheduling of uplink resources to efficiently manage the uplink transmissions.

[0006] The BSR procedure requires the UE to trigger a random-access channel, RACH, procedure and / or a scheduling request, SR, procedure. This requires the exchange of several signaling messages between the UE and the gNB. The exchange of several signaling messages, before the UE is allocated with the desired uplink resources, has an impact on the electrical energy consumption and is not suitable for A-loT devices.Summary

[0007] 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 an efficient dynamic allocation of uplink resources to a wireless device, such as an A-loT device, requiring the exchange of fewer signaling messages while allocating an amount of uplink resources that is fitted to the needs of the wireless device.

[0008] For that purpose, it is proposed that the wireless device transmits a predicted buffer status report, referred to as PBSR in the following, to the radio access network, RAN, before the wireless device has uplink data to transmit. This PBSR is determined by the wireless device, based e.g. on the uplink transmission context of the wireless device, and represents a volume of uplink data that the wireless device expects to transmit in the future. For a wireless device with ultra-low power consumption, such as an A-loT device, the RAN typically triggers recurrently the uplink transmissions by the wireless device. When triggering an uplink transmission, the RAN may then directly allocate uplink resources to the wireless device, with an amount of uplink resources allocated determined based on the PBSR previously received from this wireless device, without having to exchange further signaling messages between the RAN and this wireless device.

[0009] 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 an energy harvesting unit configured to convert ambient energy into electrical energy that is stored in an energy storage unit of the wireless device, the wireless device furthercomprising a communication unit configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the method comprises: transmitting to the RAN a predicted buffer status report, PBSR, which includes an indication of a volume of uplink data that the wireless device may have to transmit to the RAN, wherein the PBSR is transmitted before the wireless device has the uplink data to transmit to the RAN, receiving an uplink transmission triggering signal from the RAN, wherein the uplink transmission triggering signal includes an allocation of uplink resources to the wireless device.

[0010] 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.

[0011] In some embodiments, the method according to the first aspect comprises transmitting uplink data by using the uplink resources allocated to the wireless device.

[0012] In some embodiments, the method according to the first aspect comprises determining the PBSR based on at least one characteristic of uplink data to be transmitted by the wireless device.

[0013] In some embodiments of the method according to the first aspect, the indication of the volume of uplink data that the wireless device may have to transmit corresponds to a maximum volume of uplink data that the wireless device may have to transmit in response to receiving an uplink transmission triggering signal.

[0014] In some embodiments of the method according to the first aspect, the PBSR is transmitted in a user equipment, UE, capability message.

[0015] In some embodiments of the method according to the first aspect, the uplink transmission triggering signal is received without the wireless device transmitting a prior uplink resource allocation request to the RAN.

[0016] In some embodiments of the method according to the first aspect, the uplink transmission triggering signal is a wake-up signal from the RAN that transitions the wireless device from a sleep mode to an active mode or is a signaling message received after receiving a wake-up signal from the RAN.

[0017] 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.

[0018] 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 presentdisclosure.

[0019] According to a fourth aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a base station, BS, of a radio access network, RAN, of the wireless communication system, wherein the BS is configured to exchange data with a wireless device which comprises an energy harvesting unit configured to convert ambient energy into electrical energy that is stored in an energy storage unit of the wireless device, wherein the method comprises: receiving from the wireless device a predicted buffer status report, PBSR, which includes an indication of a volume of uplink data that the wireless device may have to transmit, wherein the PBSR is received before the wireless device has the uplink data to transmit to the RAN, transmitting an uplink transmission triggering signal to the wireless device, wherein the uplink transmission triggering signal includes an allocation of uplink resources to the wireless device determined based on the PBSR.

[0020] 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.

[0021] In some embodiments, the method according to the fourth aspect comprises receiving uplink data in the uplink resources allocated to the wireless device.

[0022] In some embodiments, the method according to the fourth aspect comprises evaluating an uplink transmission triggering criterion and, in response to the uplink transmission triggering criterion being verified: allocating uplink resources to the wireless device based on the PBSR and transmitting the uplink transmission triggering signal to the wireless device.

[0023] In some embodiments of the method according to the fourth aspect, the uplink transmission triggering criterion is verified without having to receive a prior uplink resource allocation request from the wireless device.

[0024] In some embodiments of the method according to the fourth aspect, the indication of the volume of uplink data that the wireless device may have to transmit corresponds to a maximum volume of uplink data that the wireless device may have to transmit in response to receiving an uplink transmission triggering signal.

[0025] In some embodiments of the method according to the fourth aspect, the PBSR is received in a user equipment, UE, capability message.

[0026] In some embodiments of the method according to the fourth aspect, the uplink transmission triggering signal is a wake-up signal that transitions the wireless device froma sleep mode to an active mode or is a signaling message transmitted after transmitting a wake-up signal to the wireless device.

[0027] In some embodiments of the method according to the fourth aspect, wherein the uplink transmission triggering signal is a signaling message addressed specifically to the wireless device.

[0028] In some embodiments, the method according to the fourth aspect comprises starting to transmit an energy harvesting signal to the wireless device before transmitting the uplink transmission triggering signal to said wireless device.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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

[0033] 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 : schematic representations of different possible topologies of a wireless communication system,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 dataimplemented by a wireless device of a UE and a BS, respectively.

[0034] 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

[0035] 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.

[0036] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. Also, the order of steps of any methods disclosed herein, in particular in the figures, is provided only for illustration purposes and is not meant to limit the present disclosure which may be applied with the same steps executed in a different order and / or with all or part of the steps executed in parallel or jointly, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Also, in a figure, steps represented surrounded by a dashed line are to be considered as optional for the embodiment represented in this figure. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0037] 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 beforwarded to the CN.

[0038] 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.

[0039] In the example illustrated by figure 1 , only one UE 20 is represented, which includes a wireless device 25 that provides the UE 20 with wireless connectivity to the RAN of the wireless communication system. Part a) of figure 1 represents schematically an example in which the UE 20 exchanges data (useful data and control data) directly with a BS 30 of the RAN (referred to as Topology 1 in TR 38.848 V18.0.0). Part b) of figure 1 represents schematically an example in which the UE 20 exchanges data (useful data and control data) indirectly with a BS 30 of the RAN, via one or more intermediate nodes 31 (referred to as Topology 2 in TR 38.848 V18.0.0). Each intermediate node 31 may be e.g., a relay, an integrated access and backhaul (I AB) node, another UE 20, a repeater, a reconfigurable intelligent surface (RIS), etc.

[0040] 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. The wireless device 25 is for example an A-loT device, i.e. , a wireless device having a peak power consumption lower than 1 mW, or even lower than 100 pW, or even lower than 10 pW.

[0041] 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. In preferred examples, 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.

[0042] 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 non-volatile 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.

[0043] As illustrated by figure 2, the wireless device 25 comprises also a (wireless) communication unit 253 configured to exchange data (directly or indirectly) with BSs 30 of the RAN using radio signals. The communication 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 (wireless) communication unit 253 comprises a 5G NR wireless communication unit.

[0044] As discussed above, the communication unit 253 may comprise in some examples neither downlink (DL) nor uplink (UL) amplification capabilities (the UL transmission is backscattered on a carrier wave provided externally). In other examples, the communication unit 253 may comprise DL and / or UL amplification (the UL transmission may be generated internally by the wireless device or be backscattered on a carrier wave provided externally).

[0045] As illustrated by figure 2, the wireless device 25 comprises also an energy harvesting unit 254 and an energy storage unit 255 of the wireless device.

[0046] The energy storage unit 255 may be any type of electrical energy accumulator, and may comprise e.g., one or more capacitors, one or more batteries, etc. The energy storage unit 255 is used to provide electrical energy to the other equipment of the wireless device 25 which require electrical energy, such as the one or more processors 250, the one or more memories 251 and, in some examples, the (wireless) communication unit 253.

[0047] The energy harvesting unit 254 is configured to convert ambient energy into electrical energy that is stored in the energy storage unit 255. By “ambient energy” we mean energy from energy sources that are external to the wireless device 25, which is received at the wireless device 25 without any wires between the energy sources and the wireless device 25. Hence, the energy harvesting unit 254 is such that the wireless device 25 may operate in an autonomous manner, without having to replace or recharge manually the energy storage unit 255. The energy harvesting unit 254 may for example collect energy from various energy sources including solar, thermal, motion or vibration, radiofrequency (RF), etc.

[0048] In preferred embodiments, the energy harvesting unit 254 comprises at least a radio unit configured to convert RF signals into electrical energy that is stored in the energy storage unit 255. These RF signals may for instance be external RF signals, i.e., RF signalswhich do not originate from within the wireless communication system itself but from RF sources which are external to the wireless communication system. For example, external RF signals may originate from external 3G, 4G, 5G, NR, WiFi, WiMax, Bluetooth, DAB, etc., devices located in the vicinity of the wireless device 25. Alternatively, or in combination thereof, the RF signals may originate from within the wireless communication system, for example from BSs 30 of the RAN which may transmit an energy harvesting (RF) signal to (A-loT) wireless devices 25 in their coverage, and / or from equipment separate from the BSs 30 but deployed to enable energy harvesting at the (A-loT) wireless devices 25 of the wireless communication system. In some examples, when RF signals are used to collect electrical energy into the energy storage unit 255, the energy harvesting unit 254 may be included in the (wireless) communication unit 253.

[0049] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0050] 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.

[0051] 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 (wireless) communication 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 comprises a 5G NR transceiver. In some examples, the wireless communication unit 303 may also transmit carrier waves to the wireless devices 25 which perform uplink backscattering transmissions.

[0052] As illustrated by figure 3, the BS 30 may comprise also, in some examples, a network communication unit 304, 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.

[0053] As illustrated by figure 3, the BS 30 may comprise also, in some examples, an energy harvesting signal generator 305, which generates energy harvesting (RF) signals which enable wireless devices 25 in its coverage to collect electrical energy in their energy storage units 255, via their energy harvesting units 254. The energy harvesting (RF) signals may take any suitable form enabling the energy harvesting units 254 to store electrical energy in the energy storage units 255 of the wireless devices 25. The choice of a specific energy harvesting (RF) signal format consists in a specific and non-limitative embodiment of the present disclosure. As mentioned above, when present, such energy harvesting (RF) signals may alternatively, or in combination thereof, be generated by other equipment separate from BSs 30 of the RAN.

[0054] As discussed above, the present disclosure aims at enabling an efficient dynamic allocation of uplink resources to a wireless device 25, requiring the exchange of fewer signaling messages while allocating an amount of uplink resources that is fitted to the needs of the wireless device 25.

[0055] For that purpose, it is proposed that the wireless device 25 transmits a predicted buffer status report, referred to as PBSR in the following, to the radio access network, RAN, before the wireless device 25 has uplink data to transmit. This PBSR represents a volume of uplink data that the wireless device 25 expects to transmit to the RAN in the future. When triggering an uplink transmission, the RAN may then directly allocate uplink resources to the wireless device 25, the amount uplink resources being determined by the RAN based on the PBSR previously received from this wireless device 25, without necessarily having to exchange further signaling messages between the RAN and the wireless device 25.

[0056] Figure 4 represents a diagram showing steps of an exemplary embodiment of a method 40 for exchanging data, which is implemented by a wireless device 25 of a UE 20. Figure 5 represents a diagram showing corresponding steps of an exemplary embodiment of a method 50 for exchanging data, which is implemented by a BS 30 of the RAN.

[0057] As illustrated by figure 4, the method 40 for exchanging data comprises a step S40 of transmitting to the RAN a predicted buffer status report, PBSR, which corresponds to an indication of a volume of uplink data that the wireless device 25 expects to have to transmit to the RAN in the future. By “predicted”, we mean that the PBSR corresponds to an a priori estimation of the volume of uplink data that the wireless device 25 may have to transmit during the next uplink transmission that will be triggered by the RAN, before the estimated volume of uplink data has actually arrived at the wireless device’s uplink buffer(s).

[0058] For example, the PBSR is determined by the wireless device 25 based on at least one characteristic of uplink data to be transmitted by the wireless device 25.

[0059] For example, the at least one characteristic of the uplink data to be transmitted may comprise a traffic class (priority level, latency requirement, etc.) and / or a category of UE 20 and / or a type of service running on the UE 20, etc. For example, based on the type of service running on the UE, the wireless device 25 may predict the volume of uplink data that it may have to transmit at each uplink transmission triggered by the RAN.

[0060] Alternatively, or in combination therefor, the wireless device 25 may use an history of past uplink transmissions to predict the volume of uplink data it may have to transmit during the next uplink transmission. Alternatively, or in combination thereof, if the UE 20 generates periodically uplink data to be transmitted having a predetermined size, the wireless device 25 may predict the volume of uplink data that it may have to transmit during the next uplink transmission based on the approximate time gap between uplink transmissions triggered by the RAN (which approximate time gap may be estimated, or previously agreed with the RAN, or it may be determined as the mean or maximum time gap observed between past uplink transmissions triggered by the RAN).

[0061] Any estimation method may be used for predicting the volume of uplink data that may be transmitted in the next uplink transmission triggered, and the choice of a specific method corresponds to a specific but non-limitative embodiment of the present disclosure.

[0062] In preferred embodiments, the PBSR may be conservative i.e. it may correspond to a maximum volume of uplink data that the wireless device 25 may have to transmit during the next uplink transmission triggered by the RAN. However, the PBSR may also correspond in other examples to e.g. a mean or minimum volume of uplink data that the wireless device 25 may have to transmit at each uplink transmission triggered by the RAN.

[0063] It should be noted that the PBSR transmitted may correspond to a static configuration or to a dynamic configuration.

[0064] By “static configuration”, we mean that the PBSR remains valid for all subsequent uplink transmissions triggered by the RAN unless overwritten by a new static configuration transmitted by the same wireless device 25. With a static configuration, the PBSR needs not to be transmitted before each future uplink transmission triggered by the RAN and can even be transmitted only once to the RAN (or at least once per serving BS 30).

[0065] By “dynamic configuration”, we mean that the PBSR remains valid only for a predetermined number of subsequent uplink transmissions and may remain valid only for a single subsequent uplink transmission in some cases.

[0066] The PBSR may be transmitted in any type of signaling message and the choice of a specific type of signaling message corresponds to a specific but non-limitative embodiment of the present disclosure.

[0067] For example, the signaling message with the PBSR may be transmitted shortly after an authentication of the wireless device 25 by the RAN. For example, the PBSR may be a UE capability message (RRC message) sent by the wireless device 25. Including the PBSR in a UE capability message can be used for example for a static configuration of the PBSR.

[0068] According to another example, the wireless device 25 may transmit a PBSR during an ongoing uplink transmission, or at the end of an ongoing uplink transmission e.g. before the wireless device 25 transitions to a sleep mode. Such a PBSR, transmitted during or at the end of an ongoing uplink transmission, is to be used for the next uplink transmission triggered by the RAN. Such a PBSR transmission scheme can be used for example for a dynamic configuration of the PBSR, but also for a static configuration thereof if the transmitted PBSR is to remain valid for all subsequent uplink transmissions (unless overwritten by a new static configuration).

[0069] It should be noted that both approaches, static and dynamic configuration of the PBSR, can also be combined in some embodiments. For example, the wireless device 25 may transmit a static configuration of the PBSR, to be used by default, e.g., in a UE capability message. Subsequently, the wireless device 25 may transmit a dynamic configuration of the PBSR, e.g., during or at the end of an ongoing uplink transmission, which replaces temporarily the static configuration (e.g., for only a predetermined number of triggered uplink transmissions).

[0070] The PBSR may use any suitable format and the choice of a specific format consists in a specific but non-limitative embodiment of the present disclosure. The format may, in some cases, depend on whether it corresponds to a static configuration or a dynamic configuration. For example, the format of the PBSR may be based on the format of the BSR medium access control, MAC, control element, CE.

[0071] As illustrated by figure 4, the method 40 for exchanging data comprises a step S41 of receiving an uplink transmission triggering signal from the RAN. The purpose of the uplink transmission triggering signal is to indicate to the wireless device 25 that it can initiate an uplink transmission on uplink resources allocated to the wireless device 25.

[0072] To reduce its electrical energy consumption, the wireless device 25 may be placed in a sleep mode. In such a case, the wireless device 25 needs to transition to an active mode to be able to perform the uplink data transmission. Such a transition may be triggered by the RAN, by sending a wake-up signal to the wireless device 25. In such a case, the uplink transmission triggering signal may correspond to the wake-up signal which transitions the wireless device 25 from a sleep mode to an active mode, or it may be transmitted by the RAN after it has transmitted a wake-up signal to the wireless device 25.

[0073] In the present case, the uplink transmission triggering signal includes an indication of uplink resources which are dynamically allocated to the wireless device 25, wherein the volume of allocated uplink resources is determined by the RAN based on the PBSR previously transmitted by the wireless device 25.

[0074] It should be noted that the uplink transmission can be initiated unilaterally by the RAN, without the wireless device 25 having to transmit a prior uplink resource dynamic allocation request to the RAN, e.g., without the wireless device 25 having to send a scheduling request, SR, or without performing a random-access channel, RACH, access. As discussed above, in some cases, the wireless device 25 is in a sleep mode and transitions to an active mode only upon receiving the uplink transmission triggering signal (or a wake-up signal transmitted shortly before the uplink transmission triggering signal).

[0075] In the non-limitative example illustrated by figure 4, the method 40 for exchanging data comprises a step S42 of transmitting uplink data by using all or part the uplink resources allocated to the wireless device 25.

[0076] It should be noted that, since the uplink resources are allocated for the uplink transmission triggered by the RAN without being explicitly requested beforehand by the wireless device 25, it may happen that the amount of uplink resources allocated by the RAN does not match the volume of uplink data that the wireless device 25 really needs to transmit during the triggered uplink transmission.

[0077] For example, it may happen that the wireless device 25 has no uplink data to transmit. In such a case, the wireless device 25 may skip step S42 (which is not executed) or it may use only a part of the allocated uplink resources to notify the RAN that it has no uplink data in its uplink buffer(s), or it may use all the allocated uplink resources by e.g. padding the uplink data with dummy data.

[0078] According to another example, the wireless device 25 may have a volume of uplink data to transmit that is smaller than the amount of uplink resources allocated by the RAN. This might be the most frequent situation if the PBSR corresponds to a predicted maximum volume of uplink data. In such a case, the wireless device 25 may use only a part of the allocated uplink resources, or it may use all the allocated uplink resources by e.g. padding the uplink data with dummy data.

[0079] According to yet another example, the wireless device 25 may have a volume of uplink data that is greater than the amount of uplink resources allocated by the RAN. In such a case, the wireless device 25 may for example discard the uplink data in excess (if possible), or it may keep the excess data for the next uplink transmission that will be triggered by the RAN (if possible), or it may request, during the ongoing uplink transmission,additional uplink resources in a conventional manner (e.g. by sending a BSR), etc.

[0080] 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 BS 30 when the wireless device 25 implements the method 40 for exchanging data illustrated by figure 4.

[0081] As illustrated by figure 5, the method 50 for exchanging data comprises a step S50 of receiving a PBSR from the wireless device 25. As discussed above, the PBSR may be received e.g. with a UE capability message from the wireless device 25, in a signaling message transmitted by the wireless device 25 before it transitions to a sleep mode, etc.

[0082] As illustrated by figure 5, the method 50 for exchanging data comprises a step S51 of transmitting an uplink transmission triggering signal to the wireless device 25 as an indication that uplink data is to be transmitted to the BS 30.

[0083] It should be noted that any suitable format may be used for the uplink transmission triggering signal, and that the choice of a specific format for the uplink transmission triggering signal corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the uplink transmission triggering signal may correspond to a signaling message addressed specifically to the wireless device 25. For example, the uplink transmission triggering signal may include an identifier of the wireless device 25, to enable the wireless device 25 to detect that it is the recipient of this information.

[0084] Also, in some cases, the uplink transmission triggering signal may correspond to a wake-up signal that transitions the wireless device 25 from a sleep mode to an active mode or is a signaling message transmitted after transmitting a wake-up signal to the wireless device 25 (to transition the wireless device 25 to an active mode before transmitting the uplink transmission triggering signal).

[0085] As discussed above, the uplink transmission triggering signal includes a dynamic allocation of uplink resources to the wireless device 25, and the amount of uplink resources allocated to the wireless device 25 is determined by the BS 30 based on the PBSR previously received from said wireless device 25.

[0086] For example, the BS 30 may allocate an amount of uplink resources that is identical to the predicted volume of uplink data indicated in the PBSR. In other examples, the BS 30 may allocate an amount of uplink resources that is different from the predicted volume of uplink data indicated in the PBSR, for example lower than said predicted volume. For example, if the load level of the BS 30 is important, then the BS 30 may allocate fewer uplink resources than what is strictly required to transmit the predicted volume of uplink data indicated by the PBSR. This can be also the case when the PBSR corresponds to apredicted maximum volume of uplink data that the wireless device 25 may have to transmit, since the wireless device 25 may have a smaller volume of uplink data to transmit than the predicted maximum volume. Also, if the load level of the BS 30 is low, then the BS 30 may decide to allocate more uplink resources than what is strictly required to transmit the predicted volume of uplink data indicated by the PBSR, especially if the PBSR corresponds to a predicted mean or minimum volume of uplink data to be transmitted.

[0087] In the non-limitative example illustrated by figure 5, the method 50 for exchanging data comprises a step S52 of receiving uplink data from the wireless device 25, in all or part the uplink resources allocated to the wireless device 25. As discussed above, since the uplink resources are allocated without being explicitly requested beforehand by the wireless device 25, it may happen that the wireless device 25 has no uplink data to transmit. In such a case, the wireless device 25 may skip step S42 (which is not executed) and the BS 30 may not receive uplink data during step S52 (which consists then in searching for uplink data in the allocated uplink resources and determining that the no uplink data has been transmitted by the wireless device 25).

[0088] As discussed above, the BS 30 triggers the uplink transmission without having to receive a prior uplink resource allocation request from the wireless device 25. In fact, in some cases, a wireless device 25 may be in sleep mode when the BS 30 decides to trigger an uplink transmission from this wireless device 25.

[0089] In some examples, and as illustrated by figure 5, the method 50 for exchanging data comprises a step S53 of evaluating an uplink transmission triggering criterion for the wireless device 25. If the uplink transmission triggering criterion is satisfied (reference S53a in figure 5), the BS 30 allocates uplink resources to the wireless device based on the PBSR received from the wireless device 25 and transmits the uplink transmission triggering signal to the wireless device 25 with an indication of the allocated uplink resources. In turn, if the uplink transmission triggering criterion is not satisfied (reference S53b in figure 5), the uplink transmission triggering signal is not transmitted. For example, and as illustrated by figure 5, the step S53 of evaluating the uplink transmission triggering criterion is executed recurrently by the BS 30, until it detects that the uplink transmission triggering criterion is verified.

[0090] Diverse types of uplink transmission triggering criteria can be considered, and the choice of a specific uplink transmission triggering criterion corresponds to a specific but non-limitative embodiment of the present disclosure.

[0091] For example, the uplink transmission triggering criterion is verified when the BS 30 considers that the wireless device 25 may have uplink data to transmit. For example, the BS 30 may decide to transmit an uplink transmission triggering signal recurrently, forexample periodically, based on predetermined time gap or periodicity between uplink transmissions triggered by the BS. Such a time gap or periodicity may for example be previously agreed with the wireless device 25 or with a user / proprietor of the UE 20, or it may be predetermined based on the uplink transmission context of the wireless device (traffic class, UE category, service type, etc.), etc. Alternatively, or in combination thereof, the uplink transmission triggering criterion is verified when the BS 30 receives a trigger command via the CN, for example from a proprietor of the UE 20 who wants to receive uplink data from the UE 20.

[0092] In examples where the BS 30 comprises an energy harvesting signal generator 305, the BS 30 may for example start transmitting an energy harvesting (RF) signal to the wireless device 25 before transmitting the uplink transmission triggering signal to said wireless device 25. In some cases, the energy harvesting (RF) signal may be used as a wake-up signal that transitions the wireless device 25 to an active mode.

[0093] 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.

[0094] For example, the present disclosure has been made by considering mainly a wireless device 25 comprising an energy harvesting unit 254 configured to convert ambient energy into electrical energy that is stored in an energy storage unit 255. However, in some cases, the present disclosure may also be applied with wireless devices 25 which do not comprise such an energy harvesting unit, and which operate only with an energy storage unit 255 (which may rechargeable or not).

Claims

Claims1. A method (40) 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 an energy harvesting unit (254) configured to convert ambient energy into electrical energy that is stored in an energy storage unit (255) of the wireless device, the wireless device further comprising a communication unit (253) configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the method comprises:(540) transmitting to the RAN a predicted buffer status report, PBSR, which includes an indication of a volume of uplink data that the wireless device may have to transmit to the RAN, wherein the PBSR is transmitted before the wireless device has the uplink data to transmit to the RAN,(541) receiving an uplink transmission triggering signal from the RAN, wherein the uplink transmission triggering signal includes an allocation of uplink resources to the wireless device.

2. The method (40) according to claim 1 , comprising determining the PBSR based on at least one characteristic of uplink data to be transmitted by the wireless device.

3. The method (40) according to any one of the preceding claims, wherein the indication of the volume of uplink data that the wireless device may have to transmit corresponds to a maximum volume of uplink data that the wireless device may have to transmit in response to receiving an uplink transmission triggering signal.

4. The method (40) according to any one of the preceding claims, wherein the PBSR is transmitted in a user equipment, UE, capability message.

5. The method (40) according to any one of the preceding claims, wherein the uplink transmission triggering signal is received without the wireless device transmitting a prior uplink resource allocation request to the RAN.

6. The method (40) according to any one of the preceding claims, wherein the uplink transmission triggering signal is a wake-up signal from the RAN that transitions the wireless device from a sleep mode to an active mode or is a signaling message received after receiving a wake-up signal from the RAN.

7. A wireless device (25) comprising at least one memory and at least one processor configured to carry out a method (40) according to any one of the preceding claims.

8. A user equipment, UE (20), comprising a wireless device according to claim 7.

9. A method (50) for exchanging data in a wireless communication system, the method being implemented by a base station, BS (30), of a radio access network, RAN, ofthe wireless communication system, wherein the BS is configured to exchange data with a wireless device (25) which comprises an energy harvesting unit (254) configured to convert ambient energy into electrical energy that is stored in an energy storage unit (255) of the wireless device, wherein the method comprises:(550) receiving from the wireless device a predicted buffer status report, PBSR, which includes an indication of a volume of uplink data that the wireless device may have to transmit, wherein the PBSR is received before the wireless device has the uplink data to transmit to the RAN,(551) transmitting an uplink transmission triggering signal to the wireless device, wherein the uplink transmission triggering signal includes an allocation of uplink resources to the wireless device determined based on the PBSR.

10. The method (50) according to claim 9, comprising (S53) evaluating an uplink transmission triggering criterion and, in response to the uplink transmission triggering criterion being verified: allocating uplink resources to the wireless device based on the PBSR and (S51) transmitting the uplink transmission triggering signal to the wireless device.

11. The method (50) according to claim 10, wherein the uplink transmission triggering criterion is verified without having to receive a prior uplink resource allocation request from the wireless device.

12. The method (50) according to any one of claims 9 to 11 , wherein the indication of the volume of uplink data that the wireless device may have to transmit corresponds to a maximum volume of uplink data that the wireless device may have to transmit in response to receiving an uplink transmission triggering signal.

13. The method (50) according to any one of claims 9 to 12, wherein the PBSR is received in a user equipment, UE, capability message.

14. The method (50) according to any one of claims 9 to 13, wherein the uplink transmission triggering signal is a wake-up signal that transitions the wireless device from a sleep mode to an active mode or is a signaling message transmitted after transmitting a wake-up signal to the wireless device.

15. The method (50) according to any one of claims 9 to 14, comprising starting to transmit an energy harvesting signal to the wireless device (25) before transmitting the uplink transmission triggering signal to said wireless device.

16. A base station, BS (30), comprising at least one memory and at least one processor configured to carry out a method (50) according to any one of claims 9 to 15.

17. A wireless communication system comprising at least one base station (30) according to claim 16 and at least one user equipment (20) according to claim 8.

18. 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 (40) according to any one of claims 1 to 6 or a method (50) according to any one of claims 9 to 15.

19. 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 (40) according to any one of claims 1 to 6 or a method (50) according to any one of claims 9 to 15.

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