Method and device for configuring a communication identifier at an ambient IoT device based on a random-access identifier

Abstract

The present disclosure relates to methods and devices for configuring a communication identifier at a wireless device (25), such as an ambient IoT device, based on a random-access identifier selected by said wireless device in a random-access procedure, when two wireless devices select concurrently the same random-access identifier.

Description

202500416 -1-Method and device for configuring a communication identifier at an ambient loT device based on a random-access identifierTechnical field

[0001] The present disclosure relates to wireless communication systems and relates more specifically to methods and devices for configuring a communication identifier at a wireless device, such as an ambient loT device, based on a random-access identifier selected by said wireless device in a random-access procedure with 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 provided externally).

[0005] Currently, the 3GPP specifications for 5G NR define different types of random-202500416 -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 includes 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] However, when a communication identifier is to be set by the RAN, the second message would then comprise both the random-access identifier and the communication identifier, which would require more memory and power at the A-loT device to process said second message, resulting in increased complexity / power consumption forthe A-loT device.Summary

[0009] 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 reducing the complexity / power consumption required for setting a communication identifier at a wireless device, such as an A-loT device.

[0010] For that purpose, it is proposed to re-use the random-access identifier as202500416 -3-communication identifier. While the random-access identifier is selected by the A-loT device, it is effectively set as communication identifier by the RAN which provides an indication of whether the random-access identifier is to be used as communication identifier. In the present case, it is proposed that the random-access identifier is used as communication identifier by the A-loT device unless no response is received from the RAN to the first message of the random-access procedure (which includes the random-access identifier). Hence, if the random-access identifier is not approved for being used as communication identifier by the RAN, the RAN does not respond to the first message of the random-access procedure. In turn, if the random-access identifier is approved for being used as communication identifier by the RAN, the RAN transmits a second message in response to the first message. Accordingly, receiving a second message in response to the first message is an indication from the RAN that the selected random-access identifier can be used as communication identifier, such that the second message does not need to include a further communication identifier, thereby reducing the complexity / power consumption. Also, not transmitting a second message to the A-loT device when the random-access identifier is not approved for being used as communication identifier (e.g. because two A-loT devices have selected the same random-access identifier) puts an early stop to a random-access procedure that would have likely failed and / or that would have likely introduced conflicts between A-loT devices, thereby reducing power consumption.

[0011] 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 by using a communication identifier set by the RAN, 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, in response to receiving a second message from the RAN which includes the selected random-access identifier: using the selected random-access identifier as communication identifier for exchanging data with the RAN and transmitting a third message to the RAN in response to the second message,in response to not receiving a second message from the RAN: initiating another random-access procedure with the RAN by transmitting a further first message to the RAN.

[0012] 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 technically202500416 -4-possible combination.

[0013] In some embodiments of the method according to the first aspect, the initiating of another random-access procedure comprises selecting another random-access identifier, which is included in the further first message transmitted to the RAN.

[0014] In some embodiments of the method according to the first aspect, the uplink resources in which the third message is to be transmitted are indicated in the second message.

[0015] 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.

[0016] In some embodiments of the method according to the first aspect, the uplink transmission triggering signal is a paging message.

[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 present disclosure.

[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 network node, NN, of a radio access network, RAN, of the wireless communication system, wherein the NN is configured to exchange data with wireless devices by using communication identifiers set by the RAN, 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,evaluating a random-access identifier disapproval criterion,in response to the random-access identifier disapproval criterion being verified: not transmitting a second message to the wireless device in response to the first message,in response to the random-access identifier disapproval criterion not being verified: transmitting a second message to the wireless device in response to the first message, wherein the second message includes the received random-access identifier.

[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 of the method according to the fourth aspect, the random-202500416 -5-access identifier disapproval criterion is verified when the NN receives a plurality of first messages, from different wireless devices, having the same random-access identifier.

[0022] In some embodiments of the method according to the fourth aspect, the randomaccess identifier disapproval criterion is verified when the random-access identifier received from the wireless device is used as communication identifier by another wireless device.

[0023] In some embodiments of the method according to the fourth aspect, the second message further includes an indication of the uplink resources to be used by the wireless device for transmitting a third message in response to said second message.

[0024] In some embodiments of the method according to the fourth aspect, the first message is received in response to an uplink transmission triggering signal transmitted by the NN to a plurality of wireless devices.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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

[0029] 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,202500416 -6-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),Figure 7: a flow chart illustrating another example of a sequence of messages exchanged between wireless devices and a network node (BS).

[0030] 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

[0031] 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.

[0032] 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.

[0033] Figure 1 represents schematically an example of wireless communication system, which may be for example a 5G NR wireless communication system. More specifically,202500416 -7-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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 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.

[0038] 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 system202500416 -8-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.

[0039] 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.

[0040] 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.

[0041] 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).

[0042] In the non-limitative example 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.

[0043] 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.

[0044] 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 may202500416 -9-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.

[0045] 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.

[0046] 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.

[0047] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0048] 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.

[0049] 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,202500416 -10-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.

[0050] 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.

[0051] 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.

[0052] As discussed above, the present disclosure aims at proposing a solution for reducing the complexity / power consumption required for setting a communication identifier at a wireless device 25, such as an A-loT device.

[0053] For that purpose, it is proposed to re-use the random-access identifier as communication identifier. While the random-access identifier is selected by the wireless device 25, it is effectively set as communication identifier by the RAN which provides an indication of whether the random-access identifier is to be used as communication identifier. In the present case, it is proposed that the random-access identifier is used as communication identifier by the wireless device 25 unless no response is received from the RAN to the first message of the random-access procedure (which includes the randomaccess identifier). Hence, if the random-access identifier is not approved for being used as communication identifier by the RAN, the RAN does not respond to the first message of the random-access procedure. In turn, if the random-access identifier is approved for being used as communication identifier by the RAN, the RAN transmits a second message in response to the first message. Accordingly, receiving a second message in response to the first message is an indication from the RAN that the selected random-access identifier can be used as communication identifier, such that the second message does not need to include a further communication identifier, thereby reducing the complexity / power consumption. Also, not transmitting a second message to the wireless device 25 when the202500416 -11-random-access identifier is not approved for being used as communication identifier (e.g. because two wireless devices have selected the same random-access identifier) puts an early stop to a random-access procedure that would have likely failed and / or that would have likely introduced conflicts between wireless devices.

[0054] In the following, we consider in a non-limitative manner that the communication identifier of a wireless device 25 is set by the RAN during a contention-based RA procedure. This communication 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.

[0055] We now present non-limitative examples of methods for exchanging data in a wireless communication system.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] In some cases, the RAN may transmit a wake-up signal that transitions the wireless202500416 -12-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 with 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.

[0062] 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.

[0063] 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 message (hereinafter “first message”) which includes the selected random-access identifier RA-ID.

[0064] As illustrated by figure 4, the method 40 for exchanging data comprises a step S42 of evaluating whether a message (hereinafter “second message”) is received from the RAN, which includes the selected random-access identifier RA-ID, or an indication of the selected random-access identifier RA-ID.

[0065] As indicated above, the transmission of a second message by the RAN corresponds to an indication that the random-access identifier RA-ID is approved for being used as communication identifier by the wireless device 25. Hence, if a second message, which includes the selected random-access identifier RA-ID (or an indication thereof), is received from the RAN (reference S42a in figure 4), this corresponds to an approval by the RAN of the selected random-access identifier RA-ID, and the method 40 for exchanging data comprises a step S43 of using the selected random-access identifier RA-ID as communication identifier (for scheduling purposes, for performing a contention-free RA procedure, for triggering by the RAN a transmission by a specific wireless device, etc.).

[0066] In turn, if no second message is received from the RAN (reference S42b in figure 4), then the method 40 for exchanging data comprises a step S44 of not using the selected random-access identifier RA-ID as communication identifier. In other words, the selected random-access identifier RA-ID cannot be used as communication identifier, and the communication identifier remains to be set. For that purpose, the wireless device 25 initiates another RA procedure with the RAN by transmitting a further first message to the RAN (not represented in figure 4). It should be noted that the wireless device 25 cannot know if the202500416 -13-fact that no second message has been received in response to the first message is due to the selected random-access identifier RA-ID not being approved by the RAN or to another reason, e.g. because the RAN has not received the first message. Hence, the wireless device 25 may decide to initiate another RA procedure with the RAN with the same randomaccess identifier RA-ID. In other examples, when no second message is received in response to the first message, the wireless device 25 preferably selects another randomaccess identifier, different from the previously selected random-access identifier RA-ID, which is included in the further first message transmitted to the RAN.

[0067] For example, during this evaluating step S42, the wireless device 25 monitors a downlink channel, for a second message responding the first message, during a predetermined monitoring window. For example, the wireless device 25 implements the monitoring window by means of a timer, referred to as random-access identifier disapproval timer in the sequel. Hence, the wireless device 25 starts the random-access identifier disapproval timer when it starts the evaluating step S42, i.e. , when it starts monitoring the downlink channel for a second message from the RAN which echoes the selected randomaccess identifier RA-ID. If the random-access identifier disapproval timer expires without the wireless device 25 receiving a second message from the RAN (reference S42b in figure 4), the selected random-access identifier RA-ID is not used as communication identifier (step S44). In turn, if a second message echoing the selected random-access identifier RAID is received before the random-access identifier disapproval timer expires, i.e., while the random-access identifier disapproval timer is still running (reference S42a in figure 4), the selected random-access identifier RA-ID is used as communication identifier (step S43).

[0068] For example, the wireless device 25 may start monitoring the downlink channel for a second message immediately after having transmitted the first message to the RAN, or at a predetermined time after having transmitted the first message to the RAN. For example, a minimum delay AT may be specified such that, if a first message is transmitted at a time To, then the second message cannot be received before a time To+ AT. In such a case, if the first message is transmitted at T0, the wireless device 25 may start monitoring the downlink channel (and start the random-access identifier disapproval timer) at To+ AT.

[0069] The duration of the random-access identifier disapproval timer is for example preconfigured, i.e., the wireless device 25 knows beforehand the duration of the randomaccess identifier disapproval timer. For example, the duration of the random-access identifier disapproval timer may be predefined (e.g., specified by a standard). According to another example, the duration of the random-access identifier disapproval timer may be preconfigured by configuration information received beforehand from the RAN. In such a case, the method 40 for exchanging data comprises a prior step (not represented in the figures) of receiving from the RAN information for configuring the duration of the random-202500416 -14-access identifier disapproval timer.

[0070] It should be noted that the configuration information may be included in any type of downlink signal, and that the choice of a specific type of downlink signal corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the configuration information may be included in an L1 or in an L2 or in an L3 signaling message. For example, the configuration information may be included e.g. in system information broadcasted by the BS 30 or in a signaling message addressed specifically to the wireless device 25 or to a group of wireless devices 25 which includes said wireless device 25.

[0071] When the wireless device 25 receives a second message from the RAN, in response to its first message, the RA procedure can continue with the wireless device 25 for example transmitting (step S45) a message (hereinafter “third message”) to the RAN in response to the second message. For example, the third message may include uplink data from the wireless device 25. In some examples, this third message may be transmitted in uplink resources allocated specifically to the wireless device 25 by the RAN (UL grant). In such a case, the uplink resources allocated to the wireless device 25 may also be indicated in the second message received from the RAN. In other examples, this third message, transmitted during step S45, may be transmitted e.g. in contention-based uplink resources, which need not to be indicated in the second message.

[0072] It should be noted that any suitable format may be used for the indication of the uplink resources, when present in the second message. The choice of a specific format for the indication of the uplink resources corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the indication of the uplink resources may correspond to an index which indicates the location, in a predetermined time-frequency grid, of the time-frequency resources to be used by the wireless device 25. In other examples, the indication of the uplink resources may correspond to an index which indicates the location, in a predetermined time frame structure, of the time slot to be used by the wireless device 25. In other examples, the indication of the uplink resources may correspond to an index which indicates the location, in a predetermined frequency band, of the frequency sub-band to be used by the wireless device 25, etc.

[0073] 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.

[0074] 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 25.202500416 -15-

[0075] As illustrated by figure 5, the method 50 for exchanging data comprises a step S51 of evaluating a random-access identifier disapproval criterion, based on the random-access identifier RA-ID. Basically, the evaluation of the random-access identifier disapproval criterion aims at determining whether the random-access identifier RA-ID selected by the wireless device 25 can be used as communication identifier by said wireless device 25.

[0076] If the random-access identifier disapproval criterion is not verified (reference S51a in figure 5), then the received random-access identifier RA-ID is approved for being used as communication identifier and the method 50 for exchanging data comprises a step S52 whereby the BS 30 transmits a second message to the wireless device 25 which includes the received random-access identifier RA-ID (or an indication thereof) to indicate that the RA procedure can continue and that the selected random-access identifier RA-ID is approved for being used as communication identifier.

[0077] In turn, if the random-access identifier disapproval criterion is verified (reference S51b in figure 5), then the received random-access identifier RA-ID is not approved for being used as communication identifier. Accordingly, the method 50 for exchanging data comprises a step S53 whereby the BS 30 puts an end to the RA procedure initiated by the wireless device 25 by not responding to the first message. Hence, no second message is transmitted in response to the first message.

[0078] It should be noted that any suitable random-access identifier disapproval criterion may be used for determining whether the random-access identifier can be used as communication identifier, and that the choice of a specific criterion corresponds to a specific but non-limitative embodiment of the present disclosure.

[0079] In preferred embodiments, the random-access identifier disapproval criterion may be verified when the BS 30 receives concurrently a plurality of first messages, from different wireless devices initiating random-access procedures, having the same random-access identifier RA-ID. By “concurrently”, we mean that these first messages are received close in time, in such a way that the wireless devices having transmitted these first messages compete for using the same random-access identifier RA-ID as communication identifier. This is the case, for example, if a wireless device expects to receive a response to its first message in a given time window after the transmission of its first message, and if its time window overlaps at least one time window of another wireless device having selected the same random-access identifier RA-ID.

[0080] Alternatively, or in combination thereof, the random-access identifier disapproval criterion may be verified if the random-access identifier RA-ID from the wireless device 25 is already used as communication identifier by another wireless device. For example, the random-access identifier disapproval criterion may be evaluated by comparing the selected random-access identifier RA-ID, received from the wireless device 25, with communication202500416 -16-identifiers being used by other wireless devices in the radio coverage of the BS 30. In such a case, if the selected random-access identifier RA-ID is different from all the communication identifiers used by other wireless devices, then the random-access identifier disapproval criterion is not verified, and the random-access identifier RA-ID selected by the wireless device 25 may be approved for being used as communication identifier. In turn, if the selected random-access identifier RA-ID is already used as communication identifier by another wireless device in the radio coverage of the BS 30, then the random-access identifier disapproval criterion is verified, and the random-access identifier RA-ID selected by the wireless device 25 is not approved for being used as communication identifier.

[0081] In the non-limitative example of figure 5, the method 50 for exchanging data may further comprise, in some cases, a step S54 of receiving a third message from the wireless device 25, which is transmitted by the wireless device 25 in response to the second message and which may include UL data from said wireless device 25.

[0082] Figure 6 represents flow charts 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 by which a communication identifier is to be configured at the wireless device 25. 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, 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, transmitted by the BS 30 to the wireless device 25, which echoes the random-access identifier RA-ID (“ACK[RA-ID]” in the figures), for example the second message MSG2 includes the random-access identifier RA-ID, a third message MSG3, 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).

[0083] In figure 6, the wireless device 25 of the UE 20 initiates the RA procedure by transmitting to the BS 30 a first message MSG1 with the selected random-access identifier RA-ID. In the non-limitative example of figure 6, it is assumed that the wireless device 25 of the UE 20 monitors a downlink channel, for a second message responding to the first message MSG1, over a monitoring window defined by a random-access identifier disapproval timer which is started shortly after having transmitted the first message MSG1.

[0084] In part a) of figure 6, the random-access identifier RA-ID is approved by the BS 30, such that the BS 30 transmits a second message MSG2 to the wireless device 25 of the UE 20, which echoes the random-access identifier RA-ID. This second message MSG2 is received by the wireless device 25 of the UE 20 before the random-access identifier202500416 -17-disapproval timer expires. Hence, the wireless device 25 of the UE 20 can use the randomaccess identifier RA-ID as communication identifier for exchanging data with the RAN, and it continues the RA procedure by transmitting a third message MSG3 to the BS 30.

[0085] In part b) of figure 6, the random-access identifier RA-ID is not approved by the BS 30, such that the BS 30 does not respond to the first message MSG1 transmitted by the wireless device 25 of the UE 20. Hence, the random-access identifier disapproval timer expires without the wireless device 25 of the UE 20 receiving a second message. Accordingly, the RA procedure is aborted, and the wireless device 25 of the UE 20 initiates another RA procedure by transmitting a further first message MSG1 to the BS 30. In this non-limitative example, this other RA procedure is initiated by using a newly selected random-access identifier RA-ID’.

[0086] Figure 7 represents a flow chart illustrating an example of a sequence of messages exchanged between wireless devices 25 of user equipment UE1 and UE2 and a network node (BS 30 in this example), during RA procedures by which a communication identifier is to be configured at each user equipment UE1, UE2.

[0087] In the example illustrated by figure 7, the wireless device 25 of UE1 and the wireless device 25 of UE2 concurrently initiate RA procedures, each transmitting a first message MSG1 to the BS30. The wireless device 25 of UE1 selects a random-access identifier RAID and transmits its first message MSG1. The wireless device 25 of UE2 selects the same random-access identifier RA-ID and transmits its first message MSG1.

[0088] The BS 30 determines that the wireless device 25 of UE1 and the wireless device 25 of UE2 are competing for using the same random-access identifier RA-ID, such that the latter cannot be used as communication identifier by both the wireless device 25 of UE1 and the wireless device 25 of UE2. Hence, the BS 30 does not respond to the first messages MSG1 from the wireless device 25 of UE1 and from the wireless device of UE2.

[0089] In response to not receiving any response to their first messages MSG1, the wireless device 25 of UE1 and the wireless device 25 of UE2 initiate another RA procedure by transmitting a further first message MSG1 to the BS 30. In the non-limitative example of figure 7, the wireless device 25 of UE1 selects for that purpose a new random-access identifier RA-ID1 and the wireless device 25 of UE2 selects a new random-access identifier RA-ID2, different from the random-access identifier RA-ID1.

[0090] The BS 30 determines that the wireless device 25 of UE1 and the wireless device 25 of UE2 are not competing for using the same random-access identifier, and the randomaccess identifiers RA-ID1 and RA-ID2 are both approved for being used as communication identifiers. Accordingly, the BS 30 transmits a second message MSG2 to the wireless device 25 of UE1, which echoes the random-access identifier RA-ID1, thereby notifying the wireless device 25 of UE1 that it can use RA-ID1 as communication identifier. Similarly, the202500416 -18-BS 30 transmits a second message MSG2 to the wireless device 25 of UE2, which echoes the random-access identifier RA-ID2, thereby notifying the wireless device 25 of UE2 that it can use RA-ID2 as communication identifier.

[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

202500416 -19-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 by using a communication identifier set by the RAN, 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, in response to receiving a second message from the RAN which includes the selected random-access identifier: (S43) using the selected random-access identifier as communication identifier for exchanging data with the RAN and (S45) transmitting a third message to the RAN in response to the second message, in response to not receiving a second message from the RAN: initiating another random-access procedure with the RAN by transmitting a further first message to the RAN.

2. The method (40) according to claim 1, wherein the initiating of another randomaccess procedure comprises selecting another random-access identifier, which is included in the further first message transmitted to the RAN.

3. The method (40) according to any one of the preceding claims, wherein the uplink resources in which the third message is to be transmitted are indicated in the second message.

4. The method (40) according to any one of the preceding claims, wherein the random-access procedure is initiated in response to receiving an uplink transmission triggering signal from the RAN.

5. The method (40) according to claim 4, wherein the uplink transmission triggering signal is a paging message.

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 NN is configured to exchange data with wireless devices by using communication identifiers set by the RAN, 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,202500416 -20-(551) evaluating a random-access identifier disapproval criterion,in response to the random-access identifier disapproval criterion being verified: (S53) not transmitting a second message to the wireless device in response to the first message,in response to the random-access identifier disapproval criterion not being verified: (552) transmitting a second message to the wireless device in response to the first message, wherein the second message includes the received random-access identifier.

9. The method (50) according to claim 8, wherein the random-access identifier disapproval criterion is verified when the NN receives a plurality of first messages, from different wireless devices, having the same random-access identifier.

10. The method (50) according to any one of claims 8 to 9, wherein the random-access identifier disapproval criterion is verified when the random-access identifier received from the wireless device is used as communication identifier by another wireless device.

11. The method (50) according to any one of claims 8 to 10, wherein the second message further includes an indication of the uplink resources to be used by the wireless device for transmitting a third message in response to said second message.

12. The method (50) according to any one of claims 8 to 11 , wherein the first message is received in response to an uplink transmission triggering signal transmitted by the NN to a plurality of wireless devices.

13. 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 12.

14. A wireless communication system comprising at least one network node (30) according to claim 13 and at least one user equipment (20) according to claim 7.

Images