Methods and devices for switching from an ambient IoT device configured as an intermediate device to another intermediate device

Abstract

The present disclosure relates to methods (40, 50) and devices for switching from a wireless device configured as an intermediate device (26) between a base station, BS (30), of a radio access network, RAN, and other wireless devices (25), for example ambient-loT devices, to another intermediate device.

Description

Methods and devices for switching from an ambient loT device configured as an intermediate device to another intermediate deviceTechnical field

[0001] The present disclosure relates to wireless communication systems and relates more specifically to methods and devices for switching from a wireless device configured as an intermediate device between a radio access network, RAN, and other wireless devices, for example ambient-loT devices, to another intermediate device.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 (LIL) amplification in the device (the device’s UL transmission is backscattered on a carrier wave provided externally), below a few hundred pW peak power consumption with energy storage, with DL and / or UL amplification in the device (the device’s UL transmission may be generated internally by the device or be backscattered on a carrier wave providedexternally).

[0005] In some cases, some A-loT devices may be located far from the RAN. In such a case, it is possible to use an intermediate device, which may be an A-loT device, which may e.g. forward downlink data from a base station, BS, of the RAN to the A-loT devices located far from the RAN and / or forward uplink data from these A-loT devices to the BS.

[0006] However, in some cases, the intermediate device may become unavailable, which may result in service interruption for the A-loT devices exchanging data with a BS of the RAN via the intermediate device.Summary

[0007] The present disclosure aims at improving the situation. In particular, the present disclosure aims at addressing at least some of the limitations of the prior art discussed above. In particular, the present disclosure aims at proposing a solution for reducing the risk of service interruption for A-loT devices which communicate with the RAN via an intermediate device.

[0008] For that purpose, it is proposed that an intermediate device, used currently by the RAN, indicates to the RAN when a new intermediate device should be selected to replace the current intermediate device. For example, the current intermediate device may evaluate an intermediate device switching criterion to determine whether such an indication should be transmitted to the RAN. For example, the intermediate device switching criterion is evaluated by the current intermediate device to determine whether there is a risk that it may become unsuitable for being used as an intermediate device between a BS of the RAN and other wireless devices. For example, the current intermediate device may become unsuitable for being used as an intermediate device if moves out of the radio coverage of the BS, and / or if the energy stored in its battery becomes too low, etc.

[0009] According to a first aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a wireless device of the wireless communication system, referred to as “intermediate device”, wherein the intermediate device comprises a communication unit configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the intermediate device is configured to forward downlink data from the RAN to other wireless devices and / or to forward uplink data from other wireless devices to the RAN, wherein the method comprises: evaluating an intermediate device switching criterion, in response to the intermediate device switching criterion being verified: transmitting an intermediate device switching indication to the RAN.

[0010] In some embodiments, the method according to the first aspect can further comprise one or more of the following optional features, considered either alone or in any technically possible combination.

[0011] In some embodiments of the method according to the first aspect, the intermediate device switching indication corresponds to a single bit.

[0012] In some embodiments of the method according to the first aspect, the intermediate device switching indication is transmitted in an L1 and / or L2 and / or L3 signaling message.

[0013] In some embodiments of the method according to the first aspect the intermediate device switching criterion is configured based on configuration information received from the RAN.

[0014] In some embodiments of the method according to the first aspect, the configuration information is received in an L1 and / or L2 and / or L3 signaling message.

[0015] In some embodiments of the method according to the first aspect, the configuration information includes at least one threshold for configuring the intermediate device switching criterion.

[0016] In some embodiments of the method according to the first aspect, evaluating the intermediate device switching criterion comprises evaluating a mobility status of the intermediate device and / or evaluating a reception level at the intermediate device and / or evaluating a battery level of the intermediate device.

[0017] In some embodiments, the method according to the first aspect comprises transmitting assistance information to the RAN, wherein the assistance information is to be used by the RAN for selecting another wireless device to be used as intermediate device.

[0018] In some embodiments of the method according to the first aspect, the assistance information is transmitted in an L3 signaling message.

[0019] 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.

[0020] 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.

[0021] According to a fourth aspect, the present disclosure relates to a method for exchanging data in a wireless communication system, the method being implemented by a base station, BS, of a radio access network, RAN, of the wireless communication system, wherein the BS is configured to exchange data with wireless devices of the wireless communication system, wherein at least one of the wireless devices is an intermediatedevice configured to forward downlink data from the BS to other wireless devices and / or to forward uplink data from other wireless devices to the BS, wherein the method comprises, in response to receiving an intermediate device switching indication from the intermediate device, selecting another wireless device to be used as intermediate device for forwarding data between the BS and other wireless devices.

[0022] 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.

[0023] In some embodiments of the method according to the fourth aspect, the intermediate device switching indication corresponds to a single bit.

[0024] In some embodiments of the method according to the fourth aspect, the intermediate device switching indication is received in an L1 and / or L2 and / or L3 signaling message.

[0025] In some embodiments, the method according to the fourth aspect comprises transmitting configuration information to the intermediate device to be used by said intermediate device for configuring an intermediate device switching criterion.

[0026] In some embodiments of the method according to the fourth aspect, the configuration information is transmitted in an L1 and / or L2 and / or L3 signaling message.

[0027] In some embodiments of the method according to the fourth aspect, the configuration information includes at least one threshold for configuring the intermediate device switching criterion.

[0028] In some embodiments of the method according to the fourth aspect, the at least one threshold includes at least one among:- a speed threshold, a reception level variation threshold,- a reception level threshold,- a battery level.

[0029] In some embodiments, the method according to the fourth aspect comprises receiving assistance information from the intermediate device, wherein the assistance information is used by the BS for selecting another wireless device to be used as intermediate device.

[0030] In some embodiments of the method according to the fourth aspect, the assistance information is received in an L3 signaling message.

[0031] According to a fifth aspect, the present disclosure relates to a base station, BS, comprising at least one memory and at least one processor configured to carry out a method according to any one of the embodiments of the fourth aspect.

[0032] According to a sixth aspect, the present disclosure relates to a wireless communication system comprising at least one base station according to any one of the embodiments of the present disclosure and at least one wireless device according to any one of the embodiments of the present disclosure.

[0033] 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.

[0034] 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

[0035] 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,Figure 4: a flow chart illustrating an example of a sequence of messages exchanged between a BS and an intermediate device,- Figure 5: a flow chart illustrating another example of a sequence of messages exchanged between a BS and an intermediate device,- Figure 6: a flow chart illustrating another example of a sequence of messages exchanged between a BS and an intermediate device.

[0036] 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

[0037] 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 detaileddescription 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.

[0038] 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.

[0039] 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 (ON, not represented in the figures). The RAN may also receive data from the UEs 20 (uplink, UL), which data may be forwarded to the ON.

[0040] 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 radio 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.

[0041] 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 thewireless 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 26 (referred to as Topology 2 in TR 38.848 V18.0.0). Each intermediate device 26 may be e.g., a relay, an integrated access and backhaul (IAB) device, another UE 20, 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 only in the downlink.

[0042] Figure 2 represents schematically an example of a wireless device 25 suitable for implementing any method, discussed in the present disclosure, performed at a UE 20. Basically, the wireless device 25 corresponds to an apparatus that provides wireless connectivity with the RAN of the wireless communication system, and that can be used to exchange data with said RAN. The wireless device 25 is for example an A-loT device, i.e., a wireless device having a peak power consumption lower than 1 mW, or even lower than 100 |JW, or even lower than 10 pW.

[0043] Such a wireless device 25 may be included in a UE 20, as illustrated by figure 2. The UE 20 may for instance be a cellular phone, a wireless modem, a wireless communication device, a handheld device, a laptop computer, or the like. In preferred examples, the UE 20 may also be an Internet of Things (loT) equipment, like a wireless camera, a smart sensor, a smart meter, smart glasses, a vehicle (manned or unmanned), a global positioning system device, etc., or any other equipment that may run applications that need to exchange data with remote recipients, via the wireless device 25.

[0044] 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.

[0045] 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 also, in some cases, 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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, forexample from BSs 30 of the RAN which may transmit an energy harvesting (RF) signal to (A-loT) wireless devices 25 in their radio 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.

[0051] 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.

[0052] Figure 3 represents schematically an example of a BS 30 suitable to implement any method, discussed in the present disclosure, performed by the RAN.

[0053] 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.

[0054] 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.

[0055] 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 GN. The network communication unit 305 may support one or more suitable communication protocols, which may be wired (including optical) and / or wireless.

[0056] 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 whichenable wireless devices 25 in its radio 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.

[0057] As discussed above, the present disclosure aims at proposing a solution for reducing the risk of service interruption for wireless devices 25, for example A-loT devices, which communicate with a BS 30 of the RAN via an intermediate device 26. Hence, the present disclosure relates to using the Topology 2 (or possibly the Topology 3), for at least some of the wireless devices 25 (located in the radio coverage of the intermediate device 26). However, the BS 30 may remain in communication according to the Topology 1 with some wireless devices 25 in its radio coverage, for example with the intermediate device 26 which may be a wireless device 25 configured to further act as an intermediate device.

[0058] For that purpose, it is proposed that an intermediate device 26, used currently by a BS 30, indicates to the BS 30 when a new intermediate device should be selected to replace the current intermediate device 26. For example, the current intermediate device 26 may evaluate an intermediate device switching criterion to determine whether such an indication should be transmitted to the BS 30. For example, the intermediate device switching criterion is evaluated by the current intermediate device 26 to determine whether there is a risk that it may become unsuitable for being used as intermediate device between the BS 30 and other wireless devices 25. For example, the current intermediate device 26 may become unsuitable for being used as an intermediate device if moves out of the radio coverage of the BS 30, and / or if the energy stored in its battery becomes too low, etc.

[0059] We now present examples of signaling strategies that may be implemented between a BS 30 and an intermediate device 26, wherein the intermediate device 26 is configured to forward downlink data from the BS 30 to other wireless devices 25 and / or to forward downlink data from other wireless devices 25 to the BS 30.

[0060] Figure 4 represents an example of a sequence of messages exchanged between a BS 30 and a wireless device 25 configured as an intermediate device 26 for other wireless devices 25. Figure 4 also represents the steps of a method 40 for exchanging data which is implemented by the BS 30 and the steps of a method 50 for exchanging data which is implemented by the intermediate device 26.

[0061] As illustrated by figure 4, the method 50 for exchanging data, implemented by the intermediate device 26, comprises a step S50 of evaluating a preconfigured intermediate device switching criterion. Basically, as discussed above, the evaluation of the intermediate device switching criterion aims at determining whether the intermediate device 26 should notify the BS 30 that it should switch to using another wireless device 25 as intermediate device. Hence, if the intermediate device switching criterion is verified (reference S50a in figure 4), the method 50 for exchanging data comprises a step S51 of transmitting an intermediate device switching indication to the BS 30. In turn, if the intermediate device switching criterion is not verified (reference S50b in figure 4), no intermediate device switching indication is transmitted to the BS 30, and the intermediate device 26 continues to operate as intermediate device between the BS 30 and other wireless devices 25.

[0062] It should be noted that any suitable format may be used for the intermediate device switching indication, and that the choice of a specific format corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the intermediate device switching indication may correspond to a single bit. For example, a value ‘0’ corresponds to “no intermediate device switching indication”, i.e., “no switching required” and a value ‘1’ corresponds to “intermediate device switching indication”, i.e., “switching required”.

[0063] Also, it should be noted that the intermediate device switching indication may be included in any type of uplink signal, and that the choice of a specific type of uplink signal corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the intermediate device switching indication may be included in an L1 (layer 1 , i.e., PHY) or in an L2 (layer 2, e.g., MAC) or in an L3 (layer 3, e.g., RRC) signaling message.

[0064] As illustrated by figure 4, the method 40 for exchanging data, implemented by the BS 30, comprises a step S40 of receiving the intermediate device switching indication from the intermediate device 26. In response to receiving such an intermediate device switching indication, the BS 30 selects another wireless device 25 to be used as new intermediate device for forwarding data between the BS 30 and other wireless devices 25, during a step S41 . Hence, the BS 30 may configure the selected wireless device 25 as a new intermediate device which may replace the previously used intermediate device 26 from which the intermediate device switching indication has been received during step S40. Once a new intermediate device is selected (and, if needed, configured), the BS 30 may for example stop using the previous intermediate device 26, from which the intermediate device switching indication has been received during step S40, for forwarding data between the BS 30 and other wireless devices 25. In some examples, the BS 30 may notify said previous intermediate device 26 that it can stop forwarding data from / to other wireless devices 25.

[0065] As indicated above, the intermediate device 26 evaluates the intermediate device switching criterion to determine whether there is a risk that it may become unsuitable for being used as an intermediate device between the BS 30 and other wireless devices 25. Hence, the BS 30 may be notified in a timely manner, and it may try and configure another wireless device 25 as a replacement intermediate device before service interruption occurs.

[0066] It should be noted that any intermediate device switching criterion (enabling the intermediate device 26 to detect that it may become unsuitable for being used as intermediate device) may be considered, and the choice of specific intermediate device switching criterion corresponds to a specific but non-limitative embodiment of the present disclosure.

[0067] For example, evaluating the intermediate device switching criterion may comprise evaluating a mobility status of the intermediate device 26. In such a case the intermediate device switching criterion may be considered verified if the intermediate device 26 is determined to be moving with respect to the BS 30. Indeed, a mobile intermediate device 26 may e.g. move out of the radio coverage of the BS 30, in which case it can no longer be used to forward data between the BS 30 and other wireless devices 25. For example, evaluating the mobility status of the intermediate device 26 may comprise estimating a speed of the intermediate device 26 relative to the BS 30 and comparing the estimated speed to a preconfigured speed threshold (which may be e.g. 0 m / s), in which case the intermediate device switching criterion may be considered verified if the estimated speed is greater than said speed threshold. According to another example, evaluating the mobility status of the intermediate device 26 may comprise measuring a reception (power) level of downlink transmissions from the BS 30 and evaluating the variations of the measured reception level. Indeed, if the measured reception level varies, this might mean that the intermediate device 26 is moving with respect to the BS 30, in which case the intermediate device switching criterion may be considered verified if the variation of the measured reception level is greater than a preconfigured reception level variation threshold.

[0068] Alternatively, or in combination thereof, evaluating the intermediate device switching criterion may comprise evaluating a reception (power) level at the intermediate device 26 of downlink transmissions from the BS 30. In such a case the intermediate device switching criterion may be considered verified if the reception level becomes low. Indeed, an intermediate device 26 with a low reception level may not be suitable for forwarding data between the BS 30 and other wireless devices 25 in a power efficient manner. The reception level at the intermediate device 26 may become low because e.g. the propagation channel between the BS 30 and the intermediate device 26 has changed. For example, evaluatingthe reception level at the intermediate device 26 may comprise measuring a reception (power) level of downlink transmissions from the BS 30 and comparing the measured reception level to a preconfigured reception level threshold, in which case the intermediate device switching criterion may be considered verified if the estimated reception level is lower than said reception level threshold.

[0069] The present disclosure may use any type of reception level measurement and the choice of a specific type of reception level measurement corresponds to a specific but non- limitative embodiment of the present disclosure. For example, the reception level measurement corresponds to a received signal strength indicator (RSS I ), a reference signal received power (RSRP), a reference signal received quality (RSRQ), etc.

[0070] Alternatively, or in combination thereof, evaluating the intermediate device switching criterion may comprise evaluating a battery level of the intermediate device 26. In such a case the intermediate device switching criterion may be considered verified if the intermediate device 26 is determined to have a low battery level. Indeed, an intermediate device 26 with a low battery level may not be able to amplify (UL and / or DL) signals and / or it may have to transition to a sleep mode (possibly turned OFF), in which case it can no longer be used to forward data between the BS 30 and other wireless devices 25. For example, evaluating the battery level of the intermediate device 26 may comprise estimating a battery level of the intermediate device 26 and comparing the estimated battery level to a preconfigured battery level threshold, in which case the intermediate device switching criterion may be considered verified if the estimated battery level is lower than said battery level threshold.

[0071] As indicated above, the intermediate device switching criterion is preconfigured, i.e., the intermediate device 26 knows beforehand e.g. what type of evaluation needs to be carried out (e.g., mobility status, reception level, battery level, etc.), the value(s) of the threshold(s) to be used if any (e.g., speed threshold, reception level variation threshold, reception level threshold, battery level threshold, etc.), etc.

[0072] For example, the intermediate device switching criterion is preconfigured based on configuration information which may be predefined (e.g., specified by a standard).

[0073] Figure 5 represents another example of a sequence of messages exchanged between a BS 30 and a wireless device 25 configured as intermediate device 26 for other wireless devices 25. In addition to the steps discussed in relation with figure 4, the method 40 for exchanging data, implemented by the BS 30, further comprises a prior step S42 of transmitting configuration information to the intermediate device 26. It should be noted that the configuration information may be included in any type of downlink signal, and that thechoice of a specific type of downlink signal corresponds to a specific but non-l imitative 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 intermediate device 26 or to a group of wireless devices 25 which includes said intermediate device 26.

[0074] The method 50 for exchanging data, implemented by the intermediate device 26, comprises a step S52 of receiving the configuration information which is used for configuring the intermediate device switching criterion before it is evaluated during step S50.

[0075] As indicated above, the configuration information may comprise for example information related to the type of evaluation that needs to be carried out (e.g., mobility status, reception level, battery level, etc.), and / or to the value(s) of the threshold(s) to be used if any (e.g., speed threshold, reception level variation threshold, reception level threshold, battery level threshold, etc.), etc.

[0076] Figure 6 represents another example of a sequence of messages exchanged between a BS 30 and a wireless device 25 configured as intermediate device 26 for other wireless devices 25. In addition to the steps discussed in relation with figure 5, the method 50 for exchanging data, implemented by the intermediate device 26, further comprises a step S53 of transmitting assistance information to the BS 30, to be used by the BS 30 for selecting another wireless device 25 to be used as a replacement intermediate device for forwarding data between the BS 30 and other wireless devices 25.

[0077] It should be noted that the assistance information may be included in any type of uplink signal, and that the choice of a specific type of uplink signal corresponds to a specific but non-limitative embodiment of the present disclosure. For example, the assistance information transmitted by the intermediate device 26 may be included in an L1 or in an L2 signaling message or, preferably, in an L3 signaling message.

[0078] In the non-limitative example of figure 6, the step S53 of transmitting the assistance information is executed after the step S51 of transmitting the intermediate device switching indication, in response to the intermediate device switching criterion being verified. In other examples, the assistance information may be transmitted together with the intermediate device switching indication, i.e., in a same signaling message. In yet other examples, the assistance information may be transmitted before the intermediate device switching indication, and optionally independently from the evaluation of the intermediate device switching criterion. Indeed, the intermediate device 26 may be configured to report recurrently, to the BS 30, information on the wireless devices 25 in its radio coverage, thatthe BS 30 may decide to use as assistance information when it receives an intermediate device switching indication from the intermediate device 26.

[0079] The assistance information may include any type of information that may assist the BS 30 in the selection of a new wireless device 25 for replacing the intermediate device 26. For example, the assistance information may be determined by the intermediate device 26 based on measurements carried out by the intermediate device 26 and / or based on data received by the intermediate device 26 from the wireless devices 25 in its radio coverage. For example, the data used to determine assistance information may be received by the intermediate device 26 via device to device, D2D, communications, for example sidelink communications, with the wireless devices 25 in its radio coverage.

[0080] For example, the assistance information may include identifiers of all or part of the wireless devices 25 in the radio coverage of the intermediate device 26, for which the intermediate device 26 forwards uplink data to the BS 30. These identifiers may be used by the BS 30 to contact directly the one or more of the candidate wireless devices 25.

[0081] Alternatively, or in combination thereof, the assistance information may include reception levels for the wireless devices 25 in its radio coverage, for example measured by the intermediate device 26 for uplink transmissions of said wireless devices 25, or measured by the wireless devices 25 for downlink transmissions of the intermediate device 26 and received by the intermediate device 26 from said wireless devices 25. Indeed, the measured reception level for a given wireless device 25 is representative of the distance between the intermediate device 26 and this wireless device 25. Hence, the measured reception levels may be used for determining for example which wireless device 25 is the closest to the intermediate device 26. Indeed, the wireless device 25 that is the closest to the intermediate device 26 may be seen as a good candidate for replacing the intermediate device 26 since it might have substantially the same radio coverage as the intermediate device 26. In other examples, the measured reception levels for the wireless devices 25 in the radio coverage of the intermediate device 26 are not transmitted as assistance information and are used by the intermediate device 26 to transmit as assistance information a list of identifiers of all or part of the wireless devices 25 in its radio coverage, ranked according to their respective estimated distances to the intermediate device 26, e.g. from the closest to the farthest.

[0082] Alternatively, or in combination thereof, the assistance information may include battery levels for the wireless devices 25 in its radio coverage, for example received from said wireless devices 25. Indeed, a wireless device 25 having a low battery level may not be a good candidate for replacing the intermediate device 26, and the battery levels may be used for determining for example which wireless device 25 has the highest battery level.Indeed, the wireless device 25 that has the highest battery level may be seen as a good candidate for replacing the intermediate device 26. In other examples, the battery levels of the wireless devices 25 in the radio coverage of the intermediate device 26 are not transmitted as assistance information and are used by the intermediate device 26 to transmit a list of identifiers of all or part of the wireless devices 25 in its radio coverage, ranked according to their respective battery levels, e.g., from the highest battery level to the lowest battery level.

[0083] As illustrated by figure 6, the method 40 for exchanging data, implemented by the BS 30, comprises a step S43 of receiving the assistance information transmitted by the intermediate device 26, and the received assistance information is used for selecting another wireless device 25 for replacing the intermediate device 26, during step S41 .

[0084] 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.

[0085] 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.

[0086] 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

Claims1. A method (50) for exchanging data in a wireless communication system, the method being implemented by a wireless device (25) of the wireless communication system, referred to as “intermediate device” (26), wherein the intermediate device comprises a communication unit configured to exchange data with a radio access network, RAN, of the wireless communication system, wherein the intermediate device is configured to forward downlink data from the RAN to other wireless devices (25) and / or to forward uplink data from other wireless devices (25) to the RAN, wherein the method comprises:- (S50) evaluating an intermediate device switching criterion, in response to the intermediate device switching criterion being verified: (S51 ) transmitting an intermediate device switching indication to the RAN.

2. The method (50) according to claim 1 , wherein the intermediate device switching indication corresponds to a single bit.

3. The method (50) according to any one of the preceding claims, wherein the intermediate device switching indication is transmitted in an L1 and / or L2 and / or L3 signaling message.

4. The method (50) according to any one of the preceding claims, wherein the intermediate device switching criterion is configured based on configuration information received from the RAN.

5. The method (50) according to claim 4, wherein the configuration information is received in an L1 and / or L2 and / or L3 signaling message.

6. The method (50) according to any one of claims 4 to 5, wherein the configuration information includes at least one threshold for configuring the intermediate device switching criterion.

7. The method (50) according to any one of the preceding claims, wherein evaluating the intermediate device switching criterion comprises evaluating a mobility status of the intermediate device (26) and / or evaluating a reception level at the intermediate device (26) and / or evaluating a battery level of the intermediate device (26).

8. The method (50) according to any one of the preceding claims, comprising (S53) transmitting assistance information to the RAN, wherein the assistance information is to be used by the RAN for selecting another wireless device to be used as intermediate device.

9. The method (50) according to claim 8, wherein the assistance information is transmitted in an L3 signaling message.

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

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

12. A method (40) for exchanging data in a wireless communication system, the method being implemented by a base station, BS (30), of a radio access network, RAN, of the wireless communication system, wherein the BS is configured to exchange data with wireless devices (25) of the wireless communication system, wherein at least one of the wireless devices is an intermediate device (26) configured to forward downlink data from the BS (30) to other wireless devices (25) and / or to forward uplink data from other wireless devices (25) to the BS (30), wherein the method (40) comprises, in response to (S40) receiving an intermediate device switching indication from the intermediate device, (S41 ) selecting another wireless device to be used as intermediate device for forwarding data between the BS (30) and other wireless devices (25).

13. The method (40) according to claim 12, wherein the intermediate device switching indication corresponds to a single bit.

14. The method (40) according to any one of claims 12 to 13, wherein the intermediate device switching indication is received in an L1 and / or L2 and / or L3 signaling message.

15. The method (40) according to any one of claims 12 to 14, comprising (S42) transmitting configuration information to the intermediate device to be used by said intermediate device for configuring an intermediate device switching criterion.

16. The method (40) according to claim 15, wherein the configuration information is transmitted in an L1 and / or L2 and / or L3 signaling message.

17. The method (40) according to any one of claims 15 to 16, wherein the configuration information includes at least one threshold for configuring the intermediate device switching criterion.

18. The method (40) according to claim 17, wherein the at least one threshold includes at least one among:- a speed threshold,- a reception level variation threshold,- a reception level threshold,- a battery level.

19. The method (40) according to any one of claims 12 to 18, comprising (S43) receiving assistance information from the intermediate device (26), wherein the assistance information is used by the BS (30) for selecting another wireless device to be used as intermediate device.

20. The method (50) according to claim 19, wherein the assistance information is received in an L3 signaling message.

21. A base station, BS (30), comprising at least one memory and at least one processor configured to carry out a method (40) according to any one of claims 12 to 20.

22. A wireless communication system comprising at least one base station (30) according to claim 21 and at least one wireless device (25) according to claim 10.

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