Method and device for controlling signaling overhead by a ran when multiple ra procedures are initiated concurrently by ambient IoT devices

Abstract

The present disclosure relates to methods and devices for controlling signaling overhead by a radio-access network, RAN, when multiple random-access, RA, procedures are initiated concurrently by multiple wireless devices (25), such as ambient IoT devices.

Description

202406123 -1-Method and device for controlling signaling overhead by a RAN when multiple RA procedures are initiated concurrently by ambient loT devicesTechnical field

[0001] The present disclosure relates to wireless communication systems and relates more specifically to methods and devices for controlling signaling overhead by a radio access network, RAN, when multiple random-access, RA, procedures are initiated concurrently by multiple wireless devices, such as ambient loT devices.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 provided externally).

[0005] Currently, the 3GPP specifications for 5G NR define different types of random-202406123 -2- access, RA, procedures enabling a user equipment, UE, to access RA uplink resources (random-access channel, RACH). These RA procedures may be used to provide the UE with a communication identifier used when exchanging data with the RAN. In 5G NR, the communication identifier corresponds e.g. to the cell-radio network temporary identifier, C- RNTI, which is us used as an identifier of the radio resource control, RRC, connection of the UE and for scheduling communication resources for the UE.

[0006] The current specifications of 5G NR define contention-based and contention free RA procedures. A contention-based RA procedure is a true RA procedure whereby the UE randomly selects RACH uplink resources such as a RA preamble. The current 5G NR specifications define for example a 4-step contention-based RA procedure based on the exchange of four messages Msg1 (from the UE to the RAN, which uses the selected RA preamble), Msg2 (from the RAN to the UE, which includes a temporary C-RNTI, TC-RNTI, and an uplink grant), Msg3 (from the UE to the RAN, which is transmitted in the uplink resources indicated by the uplink grant) and Msg4 (from the RAN to the UE, which includes the C-RNTI set by the RAN for the UE). The contention free RA procedure avoids the need for contention resolution by allocating dedicated RA preambles to some of the UEs.

[0007] The existing contention-based RA procedures may be difficult to apply as such for A-loT devices, and it is considered to use specific contention-based RA procedures for A- loT devices. Under consideration is a 3-step RA procedure which comprises a first message from the A-loT device to the RAN, which includes a random-access identifier generated by the A-loT device. The random-access identifier is then echoed by the RAN in a second message, which may also include if needed a communication identifier (e.g. for scheduling purposes and / or for subsequent contention-free RA procedures). The A-loT device may then transmit uplink data (e.g. a unique device identifier and / or upper layer data) in a third message. An optional fourth message may also be transmitted from the RAN to the A-loT device, for example for handling a transmission failure of the third message.

[0008] In some scenarios, A-loT devices may initiate a contention-based RA procedure when triggered so by the RAN, which may lead to many RA procedures being initiated concurrently by the triggered A-loT devices.

[0009] However, the risk of collisions increases as the number of A-loT devices deployed increases. Also, with many A-loT devices initiating simultaneously RA procedures, the RAN might become overloaded. Also, with many collisions due to many A-loT devices willing to access RA uplink resources, the RAN might need to trigger retransmissions by the colliding A-loT devices, which would increase the signaling overhead for the RAN and the power consumption for the A-loT devices.

[0010] Hence, there is a need for improved RA procedures for A-loT devices.Summary202406123 -3-

[0011] 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 enabling a better control of the signaling overhead by a RAN when multiple RA procedures are initiated concurrently by wireless devices, such as A-loT devices.

[0012] For that purpose, it is proposed to enable the RAN to stop (or not) an RA procedure initiated by a wireless device by sending to said wireless device an indication of whether the RA procedure is to be continued by the wireless device. Such indication, referred to as random-access approval information in the sequel, may for example be used to stop an RA procedure initiated by a wireless device if a load level of the RAN is high, if the randomaccess identifier selected by said wireless device collides with (i.e. is the same as) a random-access identifier selected by another wireless device, etc. Hence, via the transmission of the random-access approval information, the RAN may control the number of parallel RA procedures and / or the number of collisions to be resolved, thereby reducing signaling overhead for the RAN and power consumption for the wireless devices.

[0013] According to a first aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a wireless device of the wireless communication system, wherein the wireless device comprises a communication unit configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the method comprises: selecting a random-access identifier, initiating a random-access procedure by transmitting a first message to the RAN, wherein the first message includes the selected random-access identifier, receiving a second message from the RAN, wherein the second message includes the selected random-access identifier and random-access approval information, in response to the random-access approval information indicating that the randomaccess procedure is not approved: stopping the random-access procedure, in response to the random-access approval information indicating that the randomaccess procedure is approved: continuing the random-access procedure.

[0014] In some embodiments, the method according to the first aspect can further comprise one or more of the following optional features, considered either alone or in any technically possible combination.

[0015] In some embodiments of the method according to the first aspect, the continuing of the random-access procedure comprises transmitting a third message to the RAN in response to the second message, wherein the third message includes uplink data.

[0016] In some embodiments, the method according to the first aspect comprises, in response to the random-access approval information indicating that the random-access202406123 -4- procedure is not approved: selecting another random-access identifier and initiating another random-access procedure.

[0017] In some embodiments of the method according to the first aspect, the randomaccess approval information corresponds to a single bit.

[0018] In some embodiments of the method according to the first aspect, a value 0 of the random-access approval information indicates that the random-access procedure is approved and a value 1 of the random-access approval information indicates that the random-access procedure is not approved.

[0019] In some embodiments of the method according to the first aspect, the wireless device being configured to exchange data with the RAN by using a communication identifier set by the RAN, the method comprises, in response to the random-access approval information indicating that the random-access procedure is approved, using the selected random-access identifier as communication identifier.

[0020] In some embodiments of the method according to the first aspect, the randomaccess procedure is initiated in response to receiving an uplink transmission triggering signal from the RAN.

[0021] In some embodiments of the method according to the first aspect, the uplink transmission triggering signal is a paging message.

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

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

[0024] According to a fourth aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a network node, NN, of a radio access network, RAN, of the wireless communication system, wherein the method comprises: receiving from a wireless device a first message of a random-access procedure, wherein the first message includes a random-access identifier, transmitting a second message to the wireless device in response to the first message, wherein the second message includes the received random-access identifier and random-access approval information indicating whether the randomaccess procedure is to be continued by the wireless device.

[0025] In some embodiments, the method according to the fourth aspect can further comprise one or more of the following optional features, considered either alone or in any technically possible combination.202406123 -5-

[0026] In some embodiments, the method according to the fourth aspect comprises, when the transmitted random-access approval information indicates that the random-access procedure is to be continued, receiving a third message from the wireless device, wherein the third message includes uplink data.

[0027] In some embodiments, the method according to the fourth aspect comprises determining the random-access approval information by evaluating a random-access approval criterion.

[0028] In some embodiments of the method according to the fourth aspect, the randomaccess approval criterion is evaluated by using a load level of the NN.

[0029] In some embodiments of the method according to the fourth aspect, the randomaccess approval criterion is evaluated by comparing the random-access identifier received from the wireless device with random-access identifiers received from other wireless devices.

[0030] In some embodiments of the method according to the fourth aspect, the randomaccess approval information corresponds to a single bit.

[0031] In some embodiments of the method according to the fourth aspect, a value 0 of the random-access approval information indicates that the random-access procedure is approved and a value 1 of the random-access approval information indicates that the random-access procedure is not approved.

[0032] In some embodiments of the method according to the fourth aspect, the wireless device being configured to exchange data with the RAN by using a communication identifier set by the RAN, a random-access approval information indicating that the random-access procedure is approved further indicates that the received random-access identifier is to be used by the wireless device as communication identifier.

[0033] According to a fifth aspect, the present disclosure relates to a network node, NN, 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. In some embodiments, the NN is a base station or an intermediate device between a base station and wireless devices.

[0034] According to a sixth aspect, the present disclosure relates to a wireless communication system comprising at least one network node (e.g. base station or intermediate device) according to any one of the embodiments of the present disclosure and at least one user equipment according to any one of the embodiments of the present disclosure.

[0035] According to a seventh aspect, the present disclosure relates to a computer program product comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method for exchanging data according to any one of the embodiments of the present disclosure. The computer program product can use any202406123 -6- programming language, and can be in the form of source code, object code, or in any intermediate form between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0036] According to an eighth aspect, the present disclosure relates to a (non-transitory) computer-readable storage medium comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method for exchanging data according to any one of the embodiments of the present disclosure.Brief description of figures

[0037] The invention will be better understood upon reading the following description, given as an example that is in no way limiting, and made in reference to the figures which show:Figure 1: 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 data implemented by a wireless device of a UE and a BS, respectively,Figure 6: a flow chart illustrating examples of a sequence of messages exchanged between a wireless device and a network node (BS).

[0038] In these figures, references identical from one figure to another designate identical or analogous elements. For reasons of clarity, the elements shown are not to scale, unless explicitly stated otherwise.Detailed description

[0039] The detailed description set forth below, with reference to the figures, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. For instance, although 3GPP terminology, from e.g., 5G NR, may be used in this disclosure to exemplify embodiments herein, this should not be seen as limiting the scope of the present disclosure.

[0040] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. Also, the order of steps of any methods disclosed herein, in particular in the figures, is provided only for illustration purposes and is not meant to limit the present202406123 -7- 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.

[0041] Figure 1 represents schematically an example of wireless communication system, which may be for example a 5G NR wireless communication system. More specifically, figure 1 represents a RAN of the wireless communication system, which is used exchange data with UEs 20 via radio signals. For example, the RAN may send data to the UEs 20 (downlink, DL), for instance data received from a core network (CN, not represented in the figures). The RAN may also receive data from the UEs 20 (uplink, UL), which data may be forwarded to the CN.

[0042] In the example illustrated by figure 1 , the RAN comprises one base station, BS, 30. Of course, the RAN may comprise more than one BS 30 to increase the coverage of the wireless communication system. Each of these BSs may be referred to as NB, eNodeB (or eNB), gNodeB (or gNB, in the case of a 5G NR wireless communication system), an access point or the like, depending on the wireless communication standard(s) implemented.

[0043] In the example illustrated by figure 1 , 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 devices 31 (referred to as Topology 2 in TR 38.848 V18.0.0). Each intermediate device 31 may be e.g., a relay, an integrated access and backhaul (I AB) node, another UE 20 / wireless device 25, a repeater, a reconfigurable intelligent surface (RIS), etc. TR 38.848 V18.0.0 defines also other topologies, in particular a Topology 3 which also uses an intermediate device (referred to as “assisting node” in TR 38.848 V18.0.0) but only in the uplink or in the downlink.

[0044] In the sequel, we designate by network node, NN, any device via which a UE 20 may communicate with the RAN. A NN may for example correspond to a BS 30 or to an intermediate device 31 , depending on the topology considered.

[0045] Figure 2 represents schematically an example of a wireless device 25 suitable for202406123 -8- implementing any method, discussed in the present disclosure, performed at a UE 20 or at an intermediate device 31 . 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.

[0046] 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, a radio-frequency identification (RFID) tag or the like, etc., or any other equipment that may run applications that need to exchange data with remote recipients, via the wireless device 25.

[0047] 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.

[0048] As illustrated by figure 2, the wireless device 25 comprises also a (wireless) communication unit 253 adapted to exchange data (directly or indirectly) with BSs 30 of the RAN using radio signals and, in some cases (e.g. intermediate device 31), with other wireless devices 25. 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, for example with A-loT capabilities.

[0049] 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).

[0050] In the non-limitative example illustrated by figure 2, the wireless device 25 comprises202406123 -9- also an energy harvesting unit 254 and an energy storage unit 255 of the wireless device.

[0051] 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.

[0052] 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.

[0053] 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 signals which 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.

[0054] In some examples, the electrical energy collected by the energy harvesting unit 254 may be provided directly to the other equipment of the wireless device 25, in which case the energy storage unit 255 is optional and needs not to be included in the wireless device.

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

[0056] As illustrated by figure 3, the BS 30 comprises one or more processors 300 and one or more memories 301. The one or more processors 300 may include for instance a central processing unit (CPU), a digital signal processor (DSP), a field-programmable gate array202406123 -10-(FPGA), an application specific integrated circuit (ASIC), etc. The one or more memories 301 may include any type of computer readable volatile and non-volatile memories (magnetic hard disk, solid-state disk, optical disk, electronic memory, etc.). The one or more memories 301 may store a computer program product 302, in the form of a set of programcode instructions to be executed by the one or more processors 300 to implement all or part of the steps of a method for exchanging data, performed at the RAN’s side, according to any one of the embodiments disclosed herein.

[0057] As illustrated by figure 3, the BS 30 comprises also a wireless communication unit 303, configured to exchange data with UEs 20 using radio signals, and more specifically with (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, for example with A-loT capabilities. In some examples, the wireless communication unit 303 may also transmit carrier waves to the wireless devices 25 which perform uplink backscattering transmissions.

[0058] 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.

[0059] 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.

[0060] As discussed above, the present disclosure aims at proposing a solution enabling a better control of the signaling overhead by a RAN when multiple RA procedures are initiated concurrently by wireless devices 25, such as A-loT devices.

[0061] For that purpose, it is proposed to enable the RAN to stop (or not) an RA procedure initiated by a wireless device 25 by sending to said wireless device 25 a random-access approval information indicating whether the RA procedure is to be continued by the wireless device 25. For example, the RAN may decide to stop an RA procedure initiated by a wireless device 25 if a load level of the RAN is high, if the random-access identifier selected by said202406123 -11- wireless device 25 collides with (i.e. is the same as) a random-access identifier selected by another wireless device, etc. Hence, via the transmission of the random-access approval information, the RAN may control the number of parallel RA procedures and / or the number of collisions to be resolved, thereby reducing signaling overhead for the RAN and power consumption for the wireless devices 25.

[0062] In the following, we consider in a non-limitative the case of contention-based RA procedures concurrently initiated by multiple wireless devices 25.

[0063] We now present non-limitative examples of methods for exchanging data in a wireless communication system.

[0064] Figure 4 represents a diagram showing the main steps 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 the main steps of a method 50 for exchanging data, which is implemented by a NN of the RAN, e.g. by a BS 30 or by an intermediate device 31 forwarding data between wireless devices 25 and a BS 30. In the following, we consider in a non-limitative manner that the NN is a BS 30.

[0065] As illustrated by figure 4, the method 40 for exchanging data comprises a step S40 of selecting, by the wireless device 25, a random-access identifier for initiating a RA procedure with the RAN. In the figures, the selected random-access identifier is designated by RA-ID. For example, the random-access identifier RA-ID is randomly generated by the wireless device 25 and / or it is generated by using some input information which may include e.g. an identifier of the wireless device 25 which may be specific to said wireless device 25 or to a group of wireless devices which includes said wireless device 25.

[0066] It should be noted that any suitable format may be used for the random-access identifier RA-ID, and that the choice of a specific format corresponds to a specific but non- limitative embodiment of the present disclosure. For example, the random-access identifier RA-ID may be composed of 16 bits or 32 bits.

[0067] In some examples, the wireless device 25 may initiate the RA procedure (and the selection of the random-access identifier RA-ID) in response to receiving an uplink transmission triggering signal from the RAN.

[0068] 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 corresponds to a specific but non- limitative embodiment of the present disclosure. For example, the uplink transmission triggering signal may correspond to a paging signal.

[0069] In some cases, the RAN may transmit a wake-up signal that transitions the wireless device 25 from a sleep mode to an active mode. Indeed, to reduce its electrical power 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 exchange data with202406123 -12- the RAN. 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. Using a same signal for the wake-up signal and the uplink transmission triggering signal reduces the signaling overhead for the RAN, compared to using separate signals.

[0070] In other examples, the wireless device 25 may initiate the RA procedure (and the selection of the random-access identifier) without being triggered by the RAN. For example, the wireless device 25 may initiate the RA procedure in response to determining that it has received data from an upper layer that needs to be transmitted to the RAN, etc.

[0071] As illustrated by figure 4, the method 40 for exchanging data comprises a step S41 of initiating the RA procedure by transmitting to the RAN a first message which includes the selected random-access identifier RA-ID.

[0072] As illustrated by figure 4, the method 40 for exchanging data comprises a step S42 of receiving, during the RA procedure, a second message which includes random-access approval information from the RAN. In the figures, the random-access approval information is designated by RA-INFO. As indicated above, the random-access approval information RA-INFO indicates whether the initiated (contention-based) RA procedure is approved for being continued. Hence, if the random-access approval information RA-INFO indicates that the initiated RA procedure is approved (“RA-INFO = OK” in the figures), then the method 40 for exchanging data comprises a step S43 of continuing the RA procedure. In some examples, the continuing of the RA procedure comprises transmitting a third message to the RAN in response to the initiated RA procedure being approved. For example, the third may include uplink data (e.g. a unique device identifier and / or upper layer data).

[0073] In turn, if the random-access approval information RA-INFO indicates that the initiated RA procedure is not approved (“RA-INFO = NOK” in the figures), then the method 40 for exchanging data comprises a step S44 of stopping the RA procedure. In some examples, the RA procedure may be completely stopped, such that the wireless device 25 may for example have to initiate another RA procedure by selecting another random-access identifier and by sending the newly selected random-access identifier in a first message transmitted to the RAN. In other examples, the RA procedure may be temporarily stopped, such that the wireless device 25 may for example interrupt the RA procedure for some time, e.g. until it receives a further second message having random-access approval information RA-INFO indicating that the initiated RA procedure is approved.

[0074] As indicated above, a contention-based RA procedure may be used in some cases for setting a communication identifier for the wireless device 25. This communication202406123 -13- identifier may then be used when data is to be exchanged between the wireless device 25 and the RAN, for example for scheduling purposes, for performing a contention-free RA procedure, for triggering by the RAN a transmission by a specific wireless device, etc.

[0075] In some examples, the random-access approval information may further be used for setting a communication identifier for the wireless device 25 based on the random-access identifier RA-ID. For example, a random-access approval information indicating that the random-access procedure is approved (“RA-INFO = OK”) further indicates that the selected random-access identifier RA-ID is to be used by the wireless device 25 as communication identifier. In such examples, when the random-access approval information indicates that the RA procedure is approved, the wireless device 25 sets the communication identifier to be used to the random-access identifier RA-ID.

[0076] As discussed above, figure 5 represents a diagram showing the main steps of the method 50 for exchanging data, which may be implemented by a NN (i.e. a BS 30 or an intermediate device 31) when the wireless device 25 implements the method 40 for exchanging data illustrated by figure 4. As discussed above, in the following, we consider in a non-limitative manner that the NN is a BS 30.

[0077] As illustrated by figure 5, the method 50 for exchanging data comprises a step S50 of receiving from the wireless device 25 the first message initiating the RA procedure (which includes the random-access identifier RA-ID selected by the wireless device 25).

[0078] As illustrated by figure 5, the method 50 for exchanging data comprises a step S51 of determining random-access approval information RA-INFO by evaluating a randomaccess approval criterion. Basically, the evaluation of the random-access approval criterion aims at determining whether the RA procedure initiated by the wireless device 25 can be continued by said wireless device 25. If the random-access approval criterion is verified (reference S51a in figure 5), then the random-access approval information is set to “OK” (step S52) indicating that the RA procedure is approved for being continued by the wireless device 25. In turn, if the random-access approval criterion is not verified (reference S51b in figure 5), then the random-access approval information is set to “NOK” (step S53) indicating that the RA procedure is not approved for being continued by the wireless device 25.

[0079] It should be noted that any suitable format may be used for the random-access approval information RA-INFO, and that the choice of a specific format corresponds to a specific but non-limitative embodiment of the present disclosure. In preferred embodiments, a single bit is used for encoding the random-access approval information RA-INFO. For example, a value ‘0’ of the random-access approval information RA-INFO indicates that the initiated RA procedure is approved and a value ‘1’ of the random-access approval information RA-INFO indicates that the initiated RA procedure is not approved.

[0080] Also, it should be noted that any suitable random-access approval criterion may be202406123 -14- used for determining the random-access approval information RA-INFO, and that the choice of a specific random-access approval criterion corresponds to a specific but non-limitative embodiment of the present disclosure.

[0081] In some examples, the random-access approval criterion may be evaluated by comparing the selected random-access identifier RA-ID, received from the wireless device 25, with random-access identifiers received from other wireless devices in the radio coverage of the BS 30. For example, if the selected random-access identifier RA-ID is different from all the random-access identifiers selected by other wireless devices, then no collision is detected. In such a case, the random-access approval criterion is verified, and the RA procedure initiated by the wireless device 25 is approved for being continued. In turn, if the selected random-access identifier RA-ID has also been selected by another wireless device in the radio coverage of the BS 30, then a collision is detected. In such a case, the random-access approval criterion is not verified, and the RA procedure initiated by the wireless device 25 is not approved for being continued.

[0082] Alternatively, or in combination thereof, the random-access approval criterion may be evaluated in some examples by using a load level of the BS 30. For example, if the load level of the BS 30 is low (e.g. lower than a predetermined first threshold), then the randomaccess approval criterion is verified, and the RA procedure initiated by the wireless device 25 is approved for being continued. In turn, if the load level of the BS 30 is high (e.g. greater than a predetermined second threshold, greater than or equal to the first threshold), then the random-access approval criterion is not verified, and the RA procedure initiated by the wireless device 25 is not approved for being continued.

[0083] It should be noted that any suitable method may be used for estimating the load level of the BS 30, and that the choice of a specific load level estimation method corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the load level of the BS 30 may correspond to any one of the following parameters, or any combination of two or more of the following parameters: number of wireless devices 25 connected to the BS 30, number of wireless devices 25 that successfully attempted to access the RAN or BS 30 within a predefined time period, number of wireless devices 25 that were blocked from accessing the RAN or BS 30 within a predefined time period, number of first messages of RA procedures received by the BS 30 within a predefined time period, packet buffer status of the BS 30, average time during which packets remain in the packet buffer, ratio of connected A-loT devices / non-A-loT devices,202406123 -15- parameter representative of the utilization of the communication resources (e.g., a ratio of used communication resources / total communication resources), etc.

[0084] As illustrated by figure 5, the method 50 for exchanging data comprises a step S54 of transmitting the determined random-access approval information RA-INFO to the wireless device 25, during the RA procedure.

[0085] Figure 6 represents a flow chart illustrating examples of sequences of messages exchanged between a wireless device 25 of a UE 20 and a network node (BS 30 in these examples), during a RA procedure. These examples assume in a non-limitative manner the 3-step RA procedure discussed above in relation with A-loT devices. As discussed above, this 3-step RA procedure comprises: a first message (“MSG1” in the figures), transmitted by the wireless device 25 to the BS 30 (step S41), which includes a random-access identifier RA-ID generated by the wireless device 25 (step S40), a second message (“MSG2” in the figures), transmitted by the BS 30 to the wireless device 25, which echoes the random-access identifier RA-ID (“ACK[RA-ID]” in the figures), a third message (“MSG3” in the figures), transmitted by the wireless device 25 to the BS 30, which includes uplink data (e.g. a unique device identifier and / or upper layer data).

[0086] As discussed above, the RA procedure may optionally comprise a fourth message (“ACK[MSG3]” in the figures). If present, the fourth message may for example be used for handling a transmission failure of the third message MSG3.

[0087] In the example of figure 6, the random-access approval information RA-INFO is included in the second message MSG2 and is transmitted by the BS 30 together with the random-access identifier RA-ID received from the wireless device 25.

[0088] In part a) of figure 6, the RA procedure is approved by the BS 30 and the randomaccess approval information RA-INFO indicates that the RA procedure initiated by the wireless device 25 is approved for being continued (“RA-INFO = OK”). Hence, the wireless device 25 continues the RA procedure by transmitting a third message MSG3 (and the BS 30 optionally responds by transmitting a fourth message ACK[MSG3]).

[0089] In part b) of figure 6, a first RA procedure is not approved by the BS 30 and the random-access approval information RA-INFO indicates that the first RA procedure initiated by the wireless device 25 is not approved for being continued (“RA-INFO = NOK”). Hence, the wireless device 25 stops the first RA procedure and does not transmit a third message MSG3 in response to the second message MSG2 received from the BS 30.

[0090] In the non-limitative example illustrated by part b) of figure 6, when the first RA202406123 -16- procedure is stopped, the wireless device 25 initiates a second RA procedure by selecting a new random-access identifier RA-ID’ and by transmitting a first message which includes the new random-access identifier RA-ID’ to the BS 30. This second RA procedure may for example be initiated by the wireless device 25 immediately after the first RA procedure has been stopped, or after having waited for a predefined time period, or in response to a further uplink transmission triggering signal transmitted by the BS 30, etc. The second RA procedure is approved by the BS 30 and the random-access approval information RA-INFO indicates that the second RA procedure initiated by the wireless device 25 is approved for being continued (“RA-INFO = OK”). Hence, the wireless device 25 continues the second RA procedure by transmitting a third message MSG3 (and the BS 30 optionally responds by transmitting a fourth message ACK[MSG3]).

[0091] 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.

[0092] For example, the present disclosure has been made by considering mainly the case of A-loT devices. However, the present disclosure can also be used for non-A-loT devices.

[0093] It should also be noted that there can be a coexistence in the wireless communication system between wireless devices 25 which apply the present disclosure and wireless devices which do not apply the present disclosure. For example, the present disclosure may apply e.g. only to A-loT devices and not to non-A-loT devices.

Claims

202406123 -17-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 a communication unit configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the method comprises:(540) selecting a random-access identifier,(541) initiating a random-access procedure by transmitting a first message to the RAN, wherein the first message includes the selected random-access identifier,(542) receiving a second message from the RAN, wherein the second message includes the selected random-access identifier and random-access approval information, in response to the random-access approval information indicating that the randomaccess procedure is not approved: (S44) stopping the random-access procedure, in response to the random-access approval information indicating that the randomaccess procedure is approved: (S43) continuing the random-access procedure.

2. The method (40) according to claim 1 , wherein the continuing of the randomaccess procedure comprises transmitting a third message to the RAN in response to the second message, wherein the third message includes uplink data.

3. The method (40) according to any one of the preceding claims, comprising, in response to the random-access approval information indicating that the random-access procedure is not approved: selecting another random-access identifier and initiating another random-access procedure.

4. The method (40) according to any one of the preceding claims, wherein the random-access approval information corresponds to a single bit.

5. The method (40) according to claim 4, wherein a value 0 of the random-access approval information indicates that the random-access procedure is approved and a value 1 of the random-access approval information indicates that the random-access procedure is not approved.

6. 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.

7. A user equipment, UE (20), comprising a wireless device according to claim 6.

8. A method (50) for exchanging data in a wireless communication system, the method being implemented by a network node, NN (30), of a radio access network, RAN, of the wireless communication system, wherein the method comprises:(S50) receiving from a wireless device a first message of a random-access procedure, wherein the first message includes a random-access identifier,202406123 -18-(S54) transmitting a second message to the wireless device in response to the first message, wherein the second message includes the received random-access identifier and random-access approval information indicating whether the randomaccess procedure is to be continued by the wireless device.

9. The method (50) according to claim 8, comprising, when the transmitted randomaccess approval information indicates that the random-access procedure is to be continued, receiving a third message from the wireless device, wherein the third message includes uplink data.

10. The method (50) according to any one of claims 8 to 9, comprising (S51) determining the random-access approval information by evaluating a random-access approval criterion.

11. The method (50) according to claim 10, wherein the random-access approval criterion is evaluated by using a load level of the NN.

12. The method (50) according to any one of claims 10 to 11 , wherein the randomaccess approval criterion is evaluated by comparing the random-access identifier received from the wireless device with random-access identifiers received from other wireless devices.

13. The method (50) according to any one of claims 8 to 12, wherein the randomaccess approval information corresponds to a single bit.

14. The method (50) according to claim 13, wherein a value 0 of the random-access approval information indicates that the random-access procedure is approved and a value 1 of the random-access approval information indicates that the random-access procedure is not approved.

15. A network node, NN (30), comprising at least one memory and at least one processor configured to carry out a method (50) according to any one of claims 8 to 14.

16. A wireless communication system comprising at least one network node (30) according to claim 15 and at least one user equipment (20) according to claim 7.

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