WO2023036933A1 - Technique de manipulation et de prévention de défaillances de liaison latérale - Google Patents

Technique de manipulation et de prévention de défaillances de liaison latérale Download PDF

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Publication number
WO2023036933A1
WO2023036933A1 PCT/EP2022/075111 EP2022075111W WO2023036933A1 WO 2023036933 A1 WO2023036933 A1 WO 2023036933A1 EP 2022075111 W EP2022075111 W EP 2022075111W WO 2023036933 A1 WO2023036933 A1 WO 2023036933A1
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WIPO (PCT)
Prior art keywords
radio
radio device
congestion
shared spectrum
node
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PCT/EP2022/075111
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English (en)
Inventor
Min Wang
Zhang FU
Zhang Zhang
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Telefonaktiebolaget Lm Ericsson (Publ)
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Publication of WO2023036933A1 publication Critical patent/WO2023036933A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
    • H04W74/0816—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA] with collision avoidance

Definitions

  • the present disclosure relates to a technique for handling sidelink failures, for example a technique for switching of a path of a relayed radio communication. More specifically, and without limitation, methods and devices are provided for handling and recovering a radio link failure of a sidelink, for example methods and devices are provided for switching a radio communication from a source path to a target path and for assisting in the switching.
  • the present disclosure also generally relates to communication networks, and more specifically to methods and devices for distributing congestion information of sidelink (SL) transmission in unlicensed band.
  • SL sidelink
  • the Third Generation Partnership Project (3GPP) defined sidelinks (SLs) in Release 12 as an adaptation of the Long Term Evolution (LTE) radio access technology for direct communication between two radio devices, also referred to as user equipment (UE), without going through a base station.
  • SLs Such device-to- device (D2D) communications through SLs are also referred to as proximity service (ProSe) and can be used for cloud-based applications and Public Safety communications.
  • ProSe proximity service
  • 3GPP SL communications enable interworking of different public safety groups.
  • 3GPP has enriched SLs in Release 13 for public safety and commercial communication use- cases and, in Release 14, for vehicle-to-everything (V2X) scenarios.
  • V2X vehicle-to-everything
  • SL transmission on unlicensed spectrum is a new technology which is attracting strong interest from companies.
  • the channel access mechanism listen-before-talk (LBT) can be introduced for SL-U. That is, a SL- capable UE may need to perform LBT operation prior to a SL transmission.
  • LBT operation may fail. If a UE experiences consistent LBT failures, the UE would not be able to perform SL transmissions.
  • CLF consistent LBT failure
  • SL- U sidelink transmission on unlicensed spectrum
  • NR-U New Radio on unlicensed spectrum
  • LBT Listen Before Talk
  • UE may need to perform Listen Before Talk (LBT) operation prior to a SL transmission.
  • LBT Listen Before Talk
  • the UE may experience LBT failures consecutively on an unlicensed carrier. This may occur in case the band is heavily loaded.
  • a failure handling technique that handles and recovers a radio link failure of a sidelink, for example a relay technique that improves the robustness of a radio communication relayed in shared radio spectrum such as unlicensed spectrum.
  • a preemptive technique that distributes such information to radio devices which are going to access the carrier. In this way, those radio devices can avoid wasting time to access the carrier.
  • the band can be avoided to be further loaded so that it can recover from congestion quickly.
  • a method of handling a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device is provided.
  • the method is performed by the first radio device and comprises or initiates the step of determining the consistent LBT failure of the SL.
  • the method further comprises or initiates the step of transmitting at least one control message responsive to the determined consistent LBT failure.
  • the at least one control message may comprise at least one report that is transmitted to at least one node configured to serve the first radio device.
  • the at least one node may comprise another radio device serving the first radio device.
  • the other radio device may be a relay radio device that relays a relayed radio connection between first radio device and a radio access network (RAN) and/or a core network (CN), e.g. according any relay method aspect disclosed herein.
  • RAN radio access network
  • CN core network
  • a method of recovering a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device is provided.
  • the method is performed by a node or a controlling radio device.
  • the method comprises or initiates the step of receiving at least one control message indicative of a consistent LBT failure determined for the SL.
  • the method further comprises or initiates the step of transmitting a configuration message to the first radio device responsive to the received control message.
  • the method may further comprise any of the features or steps of the first failure handling method aspect.
  • a computer program product comprises program code portions for performing any one of the steps of the first failure handling method aspect and/or the second failure handling method aspect disclosed herein when the computer program product is executed by one or more computing devices.
  • the computer program product may be stored on a computer-readable recording medium.
  • the computer program product may also be provided for download, e.g., via the radio network, the RAN, the Internet and/or the host computer.
  • the method may be encoded in a Field- Programmable Gate Array (FPGA) and/or an Application-Specific Integrated Circuit (ASIC), or the functionality may be provided for download by means of a hardware description language.
  • FPGA Field- Programmable Gate Array
  • ASIC Application-Specific Integrated Circuit
  • a first radio device for handling a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between the first radio device and at least one second radio device.
  • the first radio device comprises memory operable to store instructions and processing circuitry operable to execute the instructions, such that the first radio device is operable to determine the consistent LBT failure of the SL.
  • the first radio device is further operable to transmit at least one control message responsive to the determined consistent LBT failure.
  • the first radio device (e.g., according to the first failure handling device aspect) may further comprise the features, or may be operable to perform, any one of the steps of the first method aspect.
  • a first radio device for handling a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between the first radio device and at least one second radio device.
  • the first radio device is configured to determine the consistent LBT failure of the SL.
  • the first device further is further configured to transmit at least one control message responsive to the determined consistent LBT failure.
  • the first radio device (e.g., according to the other first failure handling device aspect) may further comprise the features, or may be configured to perform, any one of the steps of the first method aspect.
  • a node for recovering a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device comprises memory operable to store instructions and processing circuitry operable to execute the instructions, such that the network node is operable to receive at least one control message indicative of a consistent LBT failure determined for the SL.
  • the node is further operable to transmit a configuration message to the first radio device responsive to the received control message.
  • the node may further comprise the features, or may be operable to perform any one of the steps of the second method aspect.
  • a node for recovering a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device is provided.
  • the node is configured to receive at least one control message indicative of a consistent LBT failure determined for the SL.
  • the node is further configured to transmit a configuration message to the first radio device responsive to the received control message.
  • the node (e.g., according to the second failure handling device aspect) may further comprise the features, or may be configured to perform, any one of the steps of the second method aspect.
  • the consistent listen-before-talk (LBT) failure of the SL may be determined if the first radio device detects occurrence of consistent LBT failures.
  • the transmission of the control message may be part of, or may trigger, actions to recover from the consistent LBT failure.
  • Embodiments of the technique can provide a mechanisms to enable the first radio device capable for SL (briefly: SL radio device or SL UE) to determine (e.g., detect) the consistent LBT failure of the SL (e.g., for SL transmissions) in its SL communication.
  • the at least one control message may comprise at least one report.
  • the first radio device may report the determined consistent LBT failure (e.g., the detected failure and/or event when the consistent LBT failure was determined) to at least one node.
  • the at least one node may comprise one or more relevant base stations (e.g., a serving base station or relevant gNBs) and/or one or more second radio devices and/or one or more other radio device (e.g. controlling UEs) other than the at least one second radio device.
  • the at least one control message from the first radio device may control (e.g., trigger), or may be part of performing, one or more actions to recover from the consistent LBT failure (e.g., the failure and/or event), optionally by itself or under the control (e.g., instruction) from the node (e.g., a gNB or one or more controlling UEs).
  • the second failure handling method aspect may further comprise any feature and/or any step disclosed in the context of the first failure handling method aspect, or a feature and/or step corresponding thereto, e.g., a receiver counterpart to a transmitter feature or step.
  • any failure handling method aspect can select a relay radio device and/or selectively perform a SL connection establishment, optionally which ensures that data to be transmitted by the first radio device is given the appropriate QoS treatment (e.g., the QoS of the traffic), e.g. according to any of the relay method aspects disclosed herein.
  • a relay radio device and/or selectively perform a SL connection establishment, optionally which ensures that data to be transmitted by the first radio device is given the appropriate QoS treatment (e.g., the QoS of the traffic), e.g. according to any of the relay method aspects disclosed herein.
  • a method of switching a radio communication involving a remote radio device from a source path to a target path is provided.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the method being performed by the remote radio device and comprises or initiates the step of receiving a control message indicative of a status of the shared spectrum link on the source path of the relayed radio communication.
  • the method further comprises or initiates the step of switching the relayed radio communication from the source path to the target path depending on the status of the shared spectrum link.
  • RATs radio access technologies
  • a method performed by at least one second radio device (or a further remote radio device) as a remote radio device comprises or initiates the step of receiving a control message indicative of a status of a shared spectrum link on a source path of a radio communication that is relayed through a first relay node on at least one of the source path and a target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises the shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs).
  • the method further comprises the step of switching the relayed radio communication from the source path to a target path depending on the status of the shared spectrum link.
  • RATs radio access technologies
  • a method of assisting in switching a radio communication involving a remote radio device from a source path to a target path is provided.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the method performed by an assisting node on the source path comprises or initiates the step of determining a status of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the method further comprises or initiates the step of transmitting, to at least one assisted node other than the assisting node, a control message indicative of the determined status of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status of the shared spectrum link.
  • a computer program product (e.g., according to claim 75).
  • the computer program product comprises program code portions for performing any one of the steps of the first relay method aspect and/or the second relay method aspect disclosed herein when the computer program product is executed by one or more computing devices.
  • the computer program product may be stored on a computer-readable recording medium.
  • the computer program product may also be provided for download, e.g., via the radio network, the RAN, the Internet and/or the host computer.
  • the method may be encoded in a Field-Programmable Gate Array (FPGA) and/or an Application-Specific Integrated Circuit (ASIC), or the functionality may be provided for download by means of a hardware description language.
  • FPGA Field-Programmable Gate Array
  • ASIC Application-Specific Integrated Circuit
  • a remote radio device for switching a radio communication involving the remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the remote radio device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the remote radio device is operable to receive a control message indicative of a status of the shared spectrum link on the source path of the relayed radio communication; and switch the relayed radio communication from the source path to the target path depending on the status of the shared spectrum link.
  • RATs radio access technologies
  • the remote radio device (e.g., according to the first relay device aspect) may further be operable to perform any of the steps of the first relay method aspects.
  • a remote radio device for switching a radio communication involving the remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the remote radio device is configured to receive a control message indicative of a status of the shared spectrum link on the source path of the relayed radio communication.
  • the remote radio device is further configured to switch the relayed radio communication from the source path to the target path depending on the status of the shared spectrum link.
  • RATs radio access technologies
  • the radio device (e.g., according to the further first relay device aspect) may be further configured to perform any of the steps of the first relay method aspect.
  • an assisting node for assisting in switching a radio communication involving a remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the assisting node comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the assisting node is operable to determine a status of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the assisting node is further operable to transmit, to at least one assisted node other than the assisting node, a control message indicative of the determined status of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status of the shared spectrum link.
  • the assisting node (e.g., according to the second relay device aspect) may further be operable to perform any one of the steps of the second relay method aspect.
  • an assisting node for assisting in switching a radio communication involving a remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the assisting node is configured to determine a status of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the assisting node is further configured to transmit, to at least one assisted node other than the assisting node, a control message indicative of the determined status of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status of the shared spectrum link.
  • the assisting node (e.g., according to the further second relay device aspect) may further be configured to perform any one of the steps of the second relay method aspect.
  • a network node implementing the assisting node of any one of the second relay device aspect is provided.
  • a relay radio device implementing the assisting node of any one of the second relay device aspect is provided.
  • a preemptive aspect of the technique includes methods and devices for distributing congestion information of SL transmission in unlicensed band to solve the above issues.
  • a method implemented by a user equipment for sidelink transmission (SL) on unlicensed band in a communication network may comprise measuring one or more congestion metrics for one or more transmission resources on the unlicensed band; generating a congestion report indicating congestion status for the one or more transmission resources based on the one or more congestion metrics; and sending the congestion report to a communication device.
  • a method implemented by a first communication device for sidelink transmission (SL) on unlicensed band in a communication network may comprise receiving a congestion report indicating congestion status for one or more transmission resources based on one or more congestion metrics from a second communication device; and distributing the congestion report to a second communication devices.
  • a network device in a communication network may comprise a processor and a memory communicatively coupled to the processor.
  • the memory may be adapted to store instructions which, when executed by the processor, cause the network device to perform steps of the method according to the above first preemptive aspect and second preemptive aspect.
  • a fourth preemptive (PR) aspect of the present disclosure there is provided a non-transitory machine-readable medium having a computer program stored thereon.
  • the computer program when executed by a set of one or more processors of a network device, causes the network device to perform steps of the method according to the above first preemptive aspect and second preemptive aspect.
  • any “radio device” may be a user equipment (UE).
  • UE user equipment
  • any one of the method aspects may be embodied by a method of handling an LBT failure for a SL transmission.
  • the SL may use radio spectrum that is shared by different radio access technologies (RATs), e.g., 3GPP New Radio (NR) and Wi-Fi.
  • RATs radio access technologies
  • the shared spectrum may also be referred to as an unlicensed band.
  • the SL using the shared spectrum may be referred to as SL-U.
  • the technique may be applied in the context of 3GPP NR. Unlike a SL according to 3GPP Long Term Evolution (LTE), a SL according to 3GPP NR can provide a wide range of QoS levels. Therefore, at least some embodiments of the technique can ensure that the first radio device can switch between paths comprising at least one SL to transmit data in fulfilment of the QoS associated with the data when the consistent LBT failure on the SL occurs.
  • LTE 3GPP Long Term Evolution
  • the technique may be implemented in accordance with a 3GPP specification, e.g., for 3GPP release 17 or later.
  • the technique may be implemented for 3GPP LTE or 3GPP NR according to or by modifying the 3GPP document TS 23.303, version 16.0.0 or for 3GPP NR according to or by modifying the 3GPP document TS 33.303, version 16.0.0.
  • the technique may be implemented according to or by modifying at least one of the 3GPP document TS 38.331, version 16.5.0; 3GPP document TS 36.331, version 16.5.0; 3GPP document TS 38.300, version 16.6.0; 3GPP document TS 36.300, version 16.6.0; 3GPP document 38.314, version 16.3.0; 3GPP document 36.314, version 16.0.0; and 3GPP document TR 32.846, version 1.1.0.
  • the technique may be implemented for SL relay selection.
  • the SL may be implemented using proximity services (ProSe), e.g. according to a 3GPP specification.
  • ProSe proximity services
  • Any radio device may be a user equipment (UE), e.g., according to a 3GPP specification.
  • the relay radio device may also be referred to as a relay UE (or briefly: relay).
  • any radio device that uses or depends on the SL may be referred to as a remote radio device or remote UE.
  • any further radio device may also be referred to as a further UE.
  • the relay radio device and the RAN may be wirelessly connected in an uplink (UL) and/or a downlink (DL) through a Uu interface.
  • the SL may enable a direct radio communication between proximal radio devices, e.g., the remote radio device and the relay radio device, optionally using a PC5 interface. Services provided using the SL or the PC5 interface may be referred to as proximity services (ProSe).
  • ProSe proximity services
  • Any radio device (e.g., the remote radio device and/or the relay radio device and/or the further radio device) supporting a SL may be referred to as ProSe-enabled radio device.
  • the relay radio device may also be referred to as ProSe UE-to- Network Relay.
  • the remote radio device and/or the relay radio device and/or the RAN and/or the further remote radio device may form, or may be part of, a radio network, e.g., according to the Third Generation Partnership Project (3GPP) or according to the standard family IEEE 802.11 (Wi-Fi).
  • the first method aspect and/or the second method aspect may be performed by one or more embodiments of the remote radio device, the relay radio device and the RAN (e.g., a base station) or the further remote radio device.
  • the RAN may comprise one or more base stations, e.g., performing the second method aspect.
  • the radio network may be a vehicular, ad hoc and/or mesh network comprising two or more radio devices, e.g., acting as the remote radio device and/or the relay radio device and/or the further remote radio device.
  • the radio devices may be a 3GPP user equipment (UE) or a Wi-Fi station (STA).
  • the radio device may be a mobile or portable station, a device for machine- type communication (MTC), a device for narrowband Internet of Things (NB-loT) or a combination thereof.
  • MTC machine- type communication
  • NB-loT narrowband Internet of Things
  • Examples for the UE and the mobile station include a mobile phone, a tablet computer and a self-driving vehicle.
  • Examples for the portable station include a laptop computer and a television set.
  • Examples for the MTC device or the NB-loT device include robots, sensors and/or actuators, e.g., in manufacturing, automotive communication and home automation.
  • the MTC device or the NB-loT device may be implemented in a manufacturing plant, household appliances and consumer electronics.
  • the RAN may be implemented by one or more network nodes (e.g., base stations).
  • network nodes e.g., base stations.
  • the remote radio device may be wirelessly connected or connectable (e.g., according to a radio resource control, RRC, state or active mode) with the relay radio device and, optionally, at least one base station of the RAN.
  • the relay radio device may be wirelessly connected or connectable (e.g., according to a radio resource control, RRC, state or active mode) with at least one base station of the RAN and/or the further remote radio device.
  • the relay radio device may be wirelessly connected or connectable (e.g., according to 3GPP ProSe) with the remote radio device.
  • the base station may encompass any station that is configured to provide radio access to any of the radio devices.
  • the base stations may also be referred to as cell, transmission and reception point (TRP), radio access node or access point (AP).
  • TRP transmission and reception point
  • AP access point
  • the base station and/or the relay radio device may provide a data link to a host computer providing user data to the remote radio device or gathering user data from the remote radio device.
  • Examples for the base stations may include a 3G base station or Node B (NB), 4G base station or eNodeB (eNB), a 5G base station or gNodeB (gNB), a Wi-Fi AP and a network controller (e.g., according to Bluetooth, ZigBee or Z-Wave).
  • NB Node B
  • eNB 4G base station or eNodeB
  • gNB 5G base station or gNodeB
  • Wi-Fi AP e.g., according to Bluetooth, ZigBee or Z-Wave.
  • the RAN may be implemented according to the Global System for Mobile Communications (GSM), the Universal Mobile Telecommunications System (UMTS), 3GPP Long Term Evolution (LTE) and/or 3GPP New Radio (NR).
  • GSM Global System for Mobile Communications
  • UMTS Universal Mobile Telecommunications System
  • LTE 3GPP Long Term Evolution
  • NR 3GPP New Radio
  • Any aspect of the technique may be implemented on a Physical Layer (PHY), a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, a packet data convergence protocol (PDCP) layer, and/or a Radio Resource Control (RRC) layer of a protocol stack for the radio communication.
  • PHY Physical Layer
  • MAC Medium Access Control
  • RLC Radio Link Control
  • PDCP packet data convergence protocol
  • RRC Radio Resource Control
  • referring to a protocol of a layer may also refer to the corresponding layer in the protocol stack.
  • referring to a layer of the protocol stack may also refer to the corresponding protocol of the layer. Any protocol may be implemented by a corresponding method.
  • a communication system including a host computer.
  • the host computer comprises a processing circuitry configured to provide user data.
  • the host computer further comprises a communication interface configured to forward the user data to a cellular network (e.g., the RAN and/or the base station) for transmission to a UE.
  • a processing circuitry of the cellular network may be configured to execute any one of the steps of any one of the first and/or second method aspects.
  • the UE comprises a radio interface and processing circuitry, which is configured to execute any one of the steps of the first and/or second method aspects.
  • the communication system may further include the UE.
  • the cellular network may further include one or more base stations configured for radio communication with the UE and/or to provide a data link between the UE and the host computer using the first and/or second method aspects.
  • the processing circuitry of the host computer may be configured to execute a host application, thereby providing data and/or any host computer functionality described herein.
  • the processing circuitry of the UE may be configured to execute a client application associated with the host application.
  • Any one of the first radio device, the UEs, the base station, the communication system or any node or station for embodying the technique may further include any feature disclosed in the context of the method aspect, and vice versa.
  • any one of the units and modules disclosed herein may be configured to perform or initiate one or more of the steps of the method aspect.
  • Fig. 1 shows a schematic block diagram of an embodiment of a device for handling a radio link failure of a sidelink
  • Fig. 2 shows a schematic block diagram of an embodiment of a device for recovering a radio link failure of a sidelink
  • FIG. 3 shows a flowchart for a method of handling a radio link failure of a sidelink, which method may be implementable by the device of Fig. 1;
  • Fig. 4 shows a flowchart for a method of recovering a radio link failure of a sidelink, which method may be implementable by the device of Fig. 2;
  • Fig. 5 schematically illustrates a first example of a communications network comprising embodiments of the devices of Figs. 1 and 2 performing the methods of Figs. 3 and 4, respectively, in radio communication;
  • Fig. 6 schematically illustrates a second example of a communications network comprising embodiments of the devices of Figs. 1 and 2 performing the methods of Figs. 3 and 4, respectively, in radio communication;
  • Fig. 7 shows a schematic block diagram of an embodiment of the method of Fig. 3;
  • Fig. 8 schematically illustrates a third example of a communications network comprising embodiments of the devices of Figs. 1 and 2 performing the methods of Figs. 3 and 4, respectively, in radio communication;
  • Fig. 9 shows a schematic block diagram of a radio device embodying the device of Fig. 1;
  • Fig. 10 shows a schematic block diagram of another radio device embodying the device of Fig. 2;
  • Fig. 11 shows a schematic block diagram of a base station embodying the device of Fig. 2;
  • Fig. 12 shows a schematic block diagram of an embodiment of a device for switching a radio communication
  • Fig. 13 shows a schematic block diagram of an embodiment of a device for assisting in switching a radio communication
  • Fig. 14 shows a flowchart for a method of switching a radio communication, which method may be implementable by the device of Fig. 12;
  • Fig. 15 shows a flowchart for a method of assisting in switching a radio communication, which method may be implementable by the device of Fig. 13;
  • Fig. 16 schematically illustrates a first example of a communications network comprising embodiments of the devices of Figs. 12 and 13 performing the methods of Figs. 14 and 15, respectively, in radio communication;
  • Fig. 17 schematically illustrates a second example of a communications network comprising embodiments of the devices of Figs. 12 and 13 performing the methods of Figs. 14 and 15, respectively, in radio communication;
  • Fig. 18 schematically illustrates a third example of a communications network comprising embodiments of the devices of Figs. 12 and 13 performing the methods of Figs. 14 and 15, respectively, in radio communication;
  • Fig. 19 schematically illustrates a third example of a communications network comprising embodiments of the devices of Figs. 12 and 13 performing the methods of Figs. 14 and 15, respectively, in radio communication;
  • Fig. 20 schematically illustrates a time domain for a first channel access mechanism in shared radio spectrum, for example on channel occupancy time (COT) sharing;
  • COT channel occupancy time
  • Fig. 21 schematically illustrates a time domain for a second channel access mechanism in shared radio spectrum, for example on channel occupancy time (COT) sharing;
  • COT channel occupancy time
  • Fig. 22 schematically illustrates a protocol stack for a user plane transport including a Layer 2 relay radio device
  • Fig. 23 schematically illustrates a protocol stack of a non-access stratum (NAS) connection for a remote radio device to NAS components;
  • NAS non-access stratum
  • Fig. 24 schematically illustrates an architecture model using a ProSe 5G UE-to- Network Relay as an example of the relay radio device
  • Fig. 25 schematically illustrates a protocol stack for a relay radio device implemented at layer 3;
  • Fig. 26 shows a schematic a first example of a signaling diagram resulting from embodiments of the devices of Figs. 12 and 13 in radio communication;
  • Fig. 27 shows a schematic a second example of a signaling diagram resulting from embodiments of the devices of Figs. 12 and 13 in radio communication;
  • Fig. 28 shows a schematic block diagram of a radio device embodying the device of Fig. 12;
  • Fig. 29 shows a schematic block diagram of another radio device embodying the device of Fig. 13;
  • Fig. 30 shows a schematic block diagram of a base station embodying the device of Fig. 13;
  • Fig. 31 illustrates an example on COT sharing according to the present disclosure.
  • Fig. 32 shows an example of the Frame based equipment (FBE) based channel occupancy operation.
  • FBE Frame based equipment
  • Fig. 33 illustrates an exemplary flow diagram for a method for distributing congestion information of SL transmission in unlicensed band according to one or more embodiments of the present disclosure.
  • Fig. 34 illustrates an exemplary flow diagram for another method for distributing congestion information of SL transmission in unlicensed band according to one or more embodiments of the present disclosure.
  • Fig. 35 is a block diagram illustrating a network device according to some embodiments of the present disclosure.
  • Fig. 36 schematically illustrates an example telecommunication network connected via an intermediate network to a host computer
  • Fig. 37 shows a generalized block diagram of a host computer communicating via a base station or radio device functioning as a gateway with a user equipment over a partially wireless connection;
  • Figs. 38 and 39 show flowcharts for methods implemented in a communication system including a host computer, a base station or radio device functioning as a gateway and a user equipment.
  • WLAN Wireless Local Area Network
  • 3GPP LTE e.g., LTE-Advanced or a related radio access technique such as MulteFire
  • Bluetooth according to the Bluetooth Special Interest Group (SIG), particularly Bluetooth Low Energy, Bluetooth Mesh Networking and Bluetooth broadcasting, for Z-Wave according to the Z-Wave Alliance or for ZigBee based on IEEE 802.15.4.
  • SIG Bluetooth Special Interest Group
  • Bracketed text and blocks with dashed borders may be used herein to illustrate optional operations that add additional features to embodiments of the present disclosure. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments of the present disclosure.
  • An electronic device stores and transmits (internally and/or with other electronic devices over a network) code (which is composed of software instructions and which is sometimes referred to as computer program code or a computer program) and/or data using machine-readable media (also called computer- readable media), such as machine-readable storage media (e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory) and machine-readable transmission media (also called a carrier) (e.g., electrical, optical, radio, acoustical or other form of propagated signals - such as carrier waves, infrared signals).
  • machine-readable media also called computer- readable media
  • machine-readable storage media e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory
  • machine-readable transmission media also called a carrier
  • carrier e.g., electrical, optical, radio, acoustical or other form of propagated signals - such as carrier waves, infrared signals.
  • an electronic device e.g., a computer
  • includes hardware and software such as a set of one or more processors coupled to one or more machine-readable storage media to store code for execution on the set of processors and/or to store data.
  • an electronic device may include non-volatile memory containing the code since the non-volatile memory can persist code/data even when the electronic device is turned off (when power is removed), and while the electronic device is turned on, that part of the code that is to be executed by the processor(s) of that electronic device is typically copied from the slower non-volatile memory into volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM)) of that electronic device.
  • volatile memory e.g., dynamic random access memory (DRAM), static random access memory (SRAM)
  • Typical electronic devices also include a set of or one or more physical network interfaces to establish network connections (to transmit and/or receive code and/or data using propagating signals) with other electronic devices.
  • One or more parts of an embodiment of the present disclosure may be implemented using different combinations of software, firmware, and/or hardware.
  • the term "communication device” means the electrical devices used in a communication network.
  • the communication device may be a user equipment or mobile station in any of the communication standard, such as 2G, 3G, 4G, 5G or beyond.
  • the communication device may be a base station, NodeB, eNB, or gNB in any of the communication standard, such as 2G, 3G, 4G, 5G or beyond.
  • the communication device may be a core network device, such as Authentication Management Function (AMF) or Session Management Function (SMF), etc.
  • AMF Authentication Management Function
  • SMF Session Management Function
  • a first radio device for handling a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between the first radio device and at least one second radio device.
  • the first radio device comprises memory operable to store instructions and processing circuitry operable to execute the instructions, such that the first radio device is operable to determine the consistent LBT failure of the SL.
  • the first radio device is further operable to transmit at least one control message responsive to the determined consistent LBT failure.
  • the first radio device (e.g., according to the first FH device aspect) may further comprise the features, or may be operable to perform any one of the steps of the first FH method aspect.
  • a first radio device for handling a consistent listen-before-talk (LBT) failure of a sidelink (SL) communication between the first radio device and at least one second radio device.
  • the first radio device being configured to determine the consistent LBT failure of the SL.
  • the first device further being configured to transmit at least one control message responsive to the determined consistent LBT failure.
  • the first radio device (e.g., according to the first FH device aspect) may further comprise the features, or may be configured to perform any one of the steps of the first FH method aspect.
  • Fig. 1 schematically illustrates a block diagram of an embodiment of a device for handling a consistent LBT failure of a sidelink (SL) at a first radio device or between a first radio device and at least one second radio device, e.g. according to the first failure handling (FH) aspect (e.g., the first FH device aspect).
  • the device is generically referred to by reference sign 100-FH.
  • the device 100-FH comprises a failure determination module 102-FH for that determines the consistent LBT failure of the SL at a first radio device or between the first radio device and the at least one second radio device.
  • the device 100-FH further comprises a control message transmission module 104-FH that transmits at least one control message responsive to the determined consistent LBT failure.
  • the device 100-FH may also be referred to as, or may be embodied by, the first radio device (which may also be referred to as a transmitting station or briefly transmitter).
  • the first radio device 100-FH and the at least one second radio device may be in direct radio communication, e.g., at least until the consistent LBT failure.
  • the at least one second radio device may be embodied by the device 200-FH or another radio device or a base station.
  • a node for recovering a consistent listen-before- talk (LBT) failure of a sidelink (SL), communication between a first radio device and at least one second radio device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the network node is operable to receive at least one control message indicative of a consistent LBT failure determined for the SL.
  • the node is further operable to transmit a configuration message to the first radio device responsive to the received control message.
  • the node (e.g., according to the second failure handling device aspect) may further comprise the features, or may be operable to perform any one of the steps of the second FH method aspect.
  • a node for recovering a consistent listen- before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device is provided.
  • the node being configured to receive at least one control message indicative of a consistent LBT failure determined for the SL.
  • the node is further configured to transmit a configuration message to the first radio device responsive to the received control message.
  • the node (e.g., according to the second failure handling device aspect) may further comprise the features, or may be configured to perform any one of the steps of the second FH method aspect.
  • the node (e.g., according to the second failure handling device aspect) may be a base station serving the first radio device or another radio device configured to control the first radio device.
  • Fig. 2 schematically illustrates a block diagram of an embodiment of a device for recovering a consistent LBT failure of a sidelink (SL) at a first radio device or between a first radio device and an at least one second radio device, e.g. according to the second FH aspect.
  • the device is generically referred to by reference sign 200-FH.
  • the device 200-FH comprises a control message reception module 202-FH that receives at least one control message indicative of a consistent LBT failure determined for the SL at a first radio device or between the first radio device and the at least one second radio device.
  • the device 200-FH further comprises a configuration message (e.g. a RRC message) transmission module 204-FH that transmits a configuration message to the first radio device responsive to the received control message.
  • a configuration message e.g. a RRC message
  • Any of the modules of the device 200-FH may be implemented by units configured to provide the corresponding functionality.
  • the device 200-FH may also be referred to as, or may be embodied by, a node, e.g. the at least one second radio device or another radio device or a base station serving the first radio device or a function of the core network.
  • the at least one second radio device may also be referred to as a receiving station (or briefly: receiver).
  • the first radio device and the node 200-FH may be in direct radio communication, e.g., at least for control message and/or the configuration message.
  • the first device may be embodied by the device 100-FH.
  • a method of handling a consistent listen-before-talk (LBT) failure of a sidelink (SL), communication between a first radio device and at least one second radio device is provided.
  • the method is performed by the first radio device and comprises or initiates the step of determining the consistent LBT failure of the SL.
  • the method further comprises or initiates the step of transmitting at least one control message responsive to the determined consistent LBT failure.
  • Fig. 3 shows an example flowchart for a method 300-FH of handling a consistent LBT failure of a sidelink (SL) at a first radio device or between a first radio device and an at least one second radio device, e.g. according to the first FH (method) aspect.
  • the method 300-FH is performed by the first radio device.
  • the method 300-FH comprises or initiates a step 302-FH of determining the consistent LBT failure of the SL at a first radio device or between the first radio device and the at least one second radio device.
  • the method 300-FH further comprises or initiates a step 304-FH of transmitting at least one control message responsive to the determined consistent LBT failure.
  • the method 300-FH may be performed by the device 100-FH.
  • the modules 102-FH and 104-FH may perform the steps 302-FH and 304-FH, respectively.
  • a radio link failure may be caused by one or repetitive failure events.
  • LBT failure may be used as an example of a failure event but not limiting the scope of failure event.
  • the consistent LBT failure may be a consistent and/or persistent and/or systematic radio link failure (RLF) caused by or related to a listen-before-talk (LBT) procedure on the SL.
  • RLF radio link failure
  • the determining of the consistent LBT failure may require more than a negative result of single LBT procedure on the SL.
  • the consistent LBT failure may be determined upon attempting a transmission from the first radio device.
  • a transmission on the SL may be in unicast fashion (e.g., to the at least one second radio device), groupcast fashion or broadcast fashion.
  • the consistent LBT failure may be determined upon attempting at least one of a transmission of data on the SL from the first radio device; a transmission of a physical SL shared channel (PSSCH) on the SL from the first radio device; a transmission of a physical SL control channel (PSCCH) on the SL from the first radio device; a transmission of a physical SL feedback channel (PSFCH) on the SL from the first radio device; a transmission of a SL synchronization signal (SLSS) on the SL from the first radio device; a transmission of a physical SL broadcast channel (PSBCH) on the SL from the first radio device; and a transmission of a SL discovery reference signal on the SL from the first radio device.
  • PSSCH physical SL shared channel
  • PSCCH physical SL control channel
  • PSFCH physical SL feedback channel
  • SLSS SL synchronization signal
  • PSBCH physical SL broadcast channel
  • the consistent LBT failure may be determined for at least one of a measurement object of the SL; a medium access control (MAC) destination of the SL; a resource pool of the SL; a bandwidth part (BWP) of the SL; a cell partially or completely covering the SL, optionally a physical cell identity (PCI) of the cell; a public land mobile network (PLMN) partially or completely covering the SL, optionally a mobile country code (MCC) and a mobile network code (MNC) of the PLMN; a beam of the SL; a carrier of the SL or a group of carriers including a carrier of the SL; and a frequency band of the SL.
  • MAC medium access control
  • BWP bandwidth part
  • PCI physical cell identity
  • PLMN public land mobile network
  • MCC mobile country code
  • MNC mobile network code
  • the measurement object may comprise a list of objects on which the first radio device shall perform measurements.
  • the measurement object may be indicative of the frequency and/or time location and/or subcarrier spacing.
  • the resource pool may be a set of resources assigned to the SL (i.e., to the first radio device for transmitting on the SL).
  • the resource pool may comprise radio resources of the SL and/or radio resource parameters for the radio resources, e.g., to be used when the first radio device is out of coverage.
  • the PCI may also be referred to as a physical cell identifier.
  • the consistent LBT failure of the SL may be determined if a number of consecutive listen before talk (LBT) procedures that failed to access the SL equals or exceeds a predefined LBT number limit.
  • LBT listen before talk
  • the consistent LBT failure is determined for the SL if the number of consecutive LBT procedures that fail within a predefined LBT time interval equals or exceeds the predefined LBT number limit.
  • predefined may be “configured”.
  • the first radio device may receive a configuration message that is indicative of at least one of the predefined LBT number limit (e.g., for the consecutively failed LBT procedures) and the predefined LBT time interval.
  • Each of the LBT procedures may comprise at least one of a clear channel assessment (CCA) and a backoff timer (or backoff counter).
  • CCA clear channel assessment
  • backoff timer or backoff counter
  • the determining may comprise initiating a timer when a transmission on the SL is triggered at the medium access control (MAC) layer of the first radio device.
  • the consistent LBT failure of the SL may be determined if the timer expires before the transmission is performed at the physical (PHY) layer.
  • the timer may expire after a predefined transmission time limit.
  • predefined may be “configured”.
  • the first radio device may receive a configuration message that is indicative the predefined transmission time limit.
  • Initiating the timer may be comprise setting (e.g., resetting) the timer to zero, wherein the timer is incremented with time and expires when the timer reaches a predefined transmission time limit.
  • initiating the timer may be comprise setting (e.g., resetting) the timer to a predefined transmission time limit, wherein the timer is decremented with time and expires when the timer reaches zero.
  • initiating the timer may be comprise storing a clock value, wherein the timer expires when the difference between a current clock value and the stored clock value reaches a predefined transmission time limit.
  • the consistent LBT failure of the SL may be determined if a number of transmission attempts that fails for a data packet or for a service data unit (SDU) or for a protocol data unit (PDU) or for a transport block (TB) equals or exceeds a predefined attempt number limit.
  • SDU service data unit
  • PDU protocol data unit
  • TB transport block
  • the transmission attempts may relate to the PHY layer of the first radio device.
  • the number of transmission attempts may be counted per data packet, per SDU, per PDU, per TB.
  • the consistent LBT failure of the SL may be determined if a transmission from the at least one second radio device to be received at the first radio device is outstanding for a predefined time period or if no transmission from the at least one second radio device is received at the first radio device for a predefined time period.
  • the consistent LBT failure of the SL may be determined if the at least one second radio device (or any radio device) is silent on the SL at the first radio device for the predefined time period. For example, a timer may be initiated (i.e., set, e.g., reset) whenever a transmission from the at least one second radio device is received. The consistent LBT failure may be determined if the timer expires (i.e., when the predefined time period has elapsed, e.g., when the timer reaches the predefined time period).
  • the transmission from the at least one second radio device may relate to at least one of a reference signal (RS) from the at least one second radio device; a heartbeat signal from the at least one second radio device; a SL synchronization signal (SL SS) from the at least one second radio device; and a SL broadcast channel (SL BCH) from the at least one second radio device.
  • RS reference signal
  • SL SS SL synchronization signal
  • SL BCH SL broadcast channel
  • the consistent LBT failure of the SL may be determined if a number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmissions (DTX) on the SL equals or exceeds a predefined DTX number limit.
  • HARQ hybrid automatic repeat request
  • DTX discontinuous transmissions
  • the HARQ DTX may occur on the SL when the first radio device finds (i.e., detects) no HARQ information (i.e., no HARQ feedback, e.g. no acknowledgment, or no acknowledgment and no negative acknowledgement) from the at least one second radio device on the SL (e.g., at an expected radio resource of the SL, e.g., at an expected spatial and/or time and/or frequency resource of the SL) in response to a HARQ transmission from the first radio device.
  • the HARQ DTX may occur on the SL when the first radio device finds no HARQ feedback from the at least one second radio device on the PSFCH of the SL.
  • the first radio device may measure the received energy at the expected radio resource (i.e., the radio resource of the expected HARQ information) to determine if there is energy or the HARQ DTX.
  • the first radio device e.g., at the PHY layer
  • the first radio device indicates a HARQ DTX on the SL for the corresponding HARQ transmission from the first radio device.
  • the HARQ DTX may be consecutive, if the HARQ DTX occurs for each of consecutive HARQ transmissions from the first radio device.
  • the consistent LBT failure of the SL (e.g., according to the first failure handling method aspect) may be determined if a channel occupancy of the SL equals or exceeds a predefined occupancy limit.
  • the channel occupancy may be measured, e.g., at the first radio device.
  • the channel occupancy may correspond to a fraction of occupied radio resources in the SL compared to all radio resources of the SL or compared to free (i.e., available) radio resources of the SL.
  • the free radio resources may comprise radio resources for which a CCA is positive.
  • the channel occupancy may be measured in terms of a channel busy ratio or a channel usage ratio of the SL (e.g., of a certain channel of the SL).
  • the channel occupancy may be measured by counting occupied resource elements (REs) or (e.g., at least partially occupied) resource blocks (RBs) of the SL.
  • the channel occupancy may be averaged over a predefined occupancy time period.
  • the consistent LBT failure of the SL may be determined if a radio signal quality of the at least one second radio device on the SL is less than a predefined quality threshold.
  • the radio signal quality may be measured in terms of at least one of a Received Signal Strength Indicator (RSSI), a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), a signal-to-interference and noise ratio (SINR), a signal to noise ratio (SNR), and a signal to interference ratio (SIR).
  • RSSI Received Signal Strength Indicator
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Received Quality
  • SINR signal-to-interference and noise ratio
  • SNR signal to noise ratio
  • SIR signal to interference ratio
  • the radio signal quality of the at least one second radio device on the SL at the first radio device may be averaged over a predefined measurement time period.
  • the consistent LBT failure of the SL may be determined if a number of reference signals from the at least one second radio device on the SL that are undetected at the first radio device is equal to or greater than a predefined reference signal number limit.
  • the reference signals from the at least one second radio device on the SL may comprise at least one of SL radio link monitoring (RLM) reference signals (SL RLM RSs), and discovery reference signals (DRSs).
  • RLM SL radio link monitoring
  • DRSs discovery reference signals
  • the DRSs may be examples of the SL RLM RSs.
  • the first radio device may receive a radio resource control (RRC) message from the at least one second radio device comprising an RRC information element (IE) that is indicative of a number of the SL RLM RSs transmitted by the at least one second radio device.
  • RRC radio resource control
  • the RRC message from the at least one second radio device comprising an RRC IE indicative of at least one of an in-sync (IS) quality threshold and an out-of-sync (OOS) quality threshold.
  • IS in-sync
  • OOS out-of-sync
  • a SL RLM RS transmitted from the at least one second radio device on the SL may be undetected at the first radio device if the radio signal quality measured in a SL RLM radio resource of the SL at the first radio device (e.g., in terms of any one of RSSI, RSRP, RSRQ, SI N R, SNR, and SIR) is equal to or less than the OOS quality threshold.
  • a SL RLM RS transmitted from the at least one second radio device on the SL may be detected at the first radio device if the radio signal quality measured in a SL RLM radio resource of the SL is equal to or greater than the IS quality threshold.
  • the at least one control message (e.g., according to the first failure handling method aspect) may comprise at least one report that is transmitted to at least one node configured to serve the first radio device.
  • the node may also be referred to as a serving node.
  • Serving the first radio device may comprise providing radio access to the first radio device.
  • serving the first radio device may comprise scheduling the first radio device and/or transmitting a configuration message to the first radio device and/or receiving the configuration message from the node at the first radio device.
  • any above-mentioned configuration message may be received at the first radio device from the node.
  • the configuration message from the node may be indicative of radio resources to be used by the first radio device for the SL (e.g., for transmitting and/or receiving on the SL).
  • the configuration message may be indicative of a resource pool for the SL.
  • the configuration message may be indicative of radio resources in the time domain (e.g., one or more subframes or transmission time intervals, TTIs) and/or in the frequency domain (e.g., a bandwidth part, BWP, or one or more subbands or one or more resource blocks, RBs) and/or the spatial domain (e.g., a precoder or a set of precoders or a codebook of precoders for transmit precoding at the first radio device).
  • TTIs time domain
  • the frequency domain e.g., a bandwidth part, BWP, or one or more subbands or one or more resource blocks, RBs
  • the spatial domain e.g., a precoder or a set of precoders or a codebook of precoders for transmit precoding at the first radio device.
  • the at least one report may be indicative of at least one a measurement object of the SL; a MAC destination of the SL; a resource pool of the SL; a BWP of the SL; a cell partially or completely covering the SL, optionally a PCI of the cell; a PLMN partially or completely covering the SL, optionally a MCC and a MNC of the PLMN; a beam of the SL; a carrier of the SL or a group of carriers including a carrier of the SL; and a frequency band of the SL.
  • the at least one report may comprise a separate report for each measurement object of the SL; or each MAC destination of the SL; or each resource pool of the SL; or each BWP of the SL; or each cell partially or completely covering the SL, optionally each PCI of the respective cell; or each PLMN partially or completely covering the SL, optionally a MCC and a MNC of the PLMN; or each beam of the SL; or each carrier of the SL or a group of carriers including a carrier of the SL; or each frequency band of the SL.
  • the at least one report may be indicative of at least one of an event at the first radio device when determining the consistent LBT failure; a transmission attempted by the first radio device when determining the consistent LBT failure; a cause of the consistent LBT failure; a cause for a transmission attempted by the first radio device when determining the consistent LBT failure; and a resource allocation mode associated with a transmission attempted by the first radio device when determining the consistent LBT failure.
  • the at least one report may be indicative of at least one of a channel occupancy of the SL when determining the consistent LBT failure; statistics of LBT procedures performed by the first radio device on the SL when or before determining the consistent LBT failure; a radio signal quality of the at least one second radio device on the SL at the first radio device; a quality of service (QoS) associated with data attempted to transmit on the SL from the first radio device when determining the consistent LBT failure; and a buffer status report (BSR) of the first radio device when determining the consistent LBT failure.
  • QoS quality of service
  • BSR buffer status report
  • the at least one report may be transmitted in the SL using at least one of an RRC signaling; a MAC control element (MAC CE); a control PDU of a service data adaptation protocol (SDAP); a control PDU of a packet data convergence protocol (PDCP); and a control PDU of a radio link control (RLC) protocol; a PHY layer signaling.
  • RRC radio link control
  • the PHY layer signaling may comprise a PSSCH, a PSCCH and/or a PSFCH.
  • the method may further comprise or initiate the step of storing the at least one report until the first radio device is in radio communication range with the at least one node for transmitting the at least one report to the at least one node.
  • the at least one control message may comprise a random access preamble that is transmitted to at least one node for a handover procedure and/or a path switch procedure and/or for changing to the node that is able to configure SL resources for the first radio device.
  • the at least one control message (e.g., according to the first failure handling method aspect) may comprise a reference signal that is transmitted to at least one node for a discovery procedure.
  • the at least one node may comprise at least one of a base station of a radio access network (RAN), serving the first radio device; a cell of a RAN serving the first radio device; and a beam of a RAN serving the first radio device.
  • RAN radio access network
  • the at least one node may comprise at least one of an access and mobility function (AMF) of a core network (CN); and a session management function (SMF), of a CN.
  • AMF access and mobility function
  • CN core network
  • SMF session management function
  • the method may further comprise or initiate a step of establishing a communication session between the first radio device and the CN.
  • the AMF may also be referred to as access and mobility management function.
  • the at least one node may comprise another radio device serving the first radio device.
  • the other radio device may be a relay radio device that relays a relayed radio connection between first radio device and the RAN and/or the CN.
  • the other radio device may be a neighboring radio device relative to the first radio device and/or relative to the at least one second radio device.
  • the at least one control message is transmitted from the first radio device (e.g., according to the first failure handling method aspect) in a cell in which the consistent LBT failure occurred, or to a base station providing a cell in which the consistent LBT failure occurred, or in a BWP in which the consistent LBT failure occurred, or in a resource pool in which the consistent LBT failure occurred, or to a MAC destination for which the consistent LBT failure occurred, or on the SL for which the consistent LBT failure occurred.
  • the first radio device e.g., according to the first failure handling method aspect
  • the at least one control message may be transmitted from the first radio device in a cell other than the cell in which the consistent LBT failure occurred, or to a base station other than the base station providing a cell in which the consistent LBT failure occurred, or in a BWP other than the BWP in which the consistent LBT failure occurred, or in a resource pool other than the resource pool in which the consistent LBT failure occurred, or to a MAC destination other than the MAC destination for which the consistent LBT failure occurred, or on a SL other than the SL for which the consistent LBT failure occurred.
  • the method may further comprise or initiate, or the at least one control message may initiate or indicate or trigger, at least one of changing a resource allocation mode of the first radio device for the SL; changing a resource pool of the SL; changing a carrier of the SL; changing to a serving cell that is able to configure SL resources for the SL; changing a bandwidth part (BWP) of a cell that is able to configure SL resources for the SL; and changing to a base station that is able to configure SL resources for the SL.
  • Any one of the changing steps may use at least one of the following procedures.
  • the method may further comprise or initiate, or the at least one control message may initiate or indicate or trigger, at least one of a discovery procedure; a procedure for selecting or reselection a relay radio device as the at least one second radio device or as the node; a procedure for selecting or reselection a base station or a cell as the node; a handover procedure for changing a base station or a cell as the node; and a path switch procedure for changing a relay radio device as the at least one second radio device.
  • the method may further comprise or initiate the step of indicating to the node or broadcasting a radio device capability information that is indicative of whether or not the first radio device is capable of performing the determining of the consistent LBT failure of the SL and/or the transmitting of the at least one control message responsive to the determined consistent LBT failure.
  • a method of recovering a consistent listen- before-talk (LBT) failure of a sidelink (SL) communication between a first radio device and at least one second radio device is provided.
  • the method is performed by a node or a controlling radio device.
  • the method comprises or initiates the step of receiving at least one control message indicative of a consistent LBT failure determined for the SL.
  • the method further comprises or initiates the step of transmitting a configuration message to the first radio device responsive to the received control message.
  • Fig. 4 shows an example flowchart for a method 400-FH of recovering a consistent LBT failure of a sidelink (SL) at a first radio device or between a first radio device and an at least one second radio device, e.g. according to the second FH (method) aspect.
  • the method 400-FH is performed by a node.
  • the method 400-FH comprises or initiates a step 402-FH of receiving at least one control message indicative of a consistent LBT failure determined for the SL at a first radio device or between the first radio device and the at least one second radio device.
  • the method 400-FH further comprises or initiates a step 404-FH of transmitting a configuration message to the first radio device responsive to the received control message.
  • the method 400-FH may be performed by the device 200-FH.
  • the modules 202-FH and 204-FH may perform the steps 402-FH and 404-FH, respectively.
  • Each of the device 100-FH and node 200-FH may be a radio device or a base station.
  • the node may be a base station serving the first radio device or another radio device (e.g., acting as a relay for the first radio device when the first radio device is out of coverage) and/or a controlling radio device configured to control the first radio device (e.g., via the SL).
  • a base station serving the first radio device or another radio device (e.g., acting as a relay for the first radio device when the first radio device is out of coverage) and/or a controlling radio device configured to control the first radio device (e.g., via the SL).
  • the configuration message may be indicative of another resource pool for reestablishing the SL between the first radio device and the at least one second radio device using the other resource pool.
  • the configuration message may be indicative of a discovery reference signal and/or another resource pool for establishing the SL between the first radio device and the other radio device using the other resource pool.
  • the method may further comprise any of the features or steps of the first FH method aspect, or corresponding steps of features.
  • a communication system including a host computer comprising processing circuitry configured to provide user data; and a communication interface configured to forward user data to a cellular or ad hoc radio network for transmission to a user equipment (UE) is provided.
  • the UE comprises a radio interface and processing circuitry, the processing circuitry of the UE being configured to execute any one of the steps of the first failure handling method aspect.
  • the communication system may further include the UE.
  • the radio network may further comprise a base station, or a radio device functioning as a gateway, which is configured to communicate with the UE.
  • the base station may comprise processing circuitry, which is configured to execute any one of the steps of the second failure handling method aspect.
  • the processing circuitry of the host computer may be configured to execute a host application, thereby providing the user data.
  • the processing circuitry of the UE may be configured to execute a client application associated with the host application.
  • the technique may be applied to an uplink (UL) and/or downlink (DL) between the first radio device 100-FH and the node 200-FH and/or direct communications between radio devices, e.g., device-to-device (D2D) communications or sidelink (SL) communications, between the first radio device 100-FH and the at least one second radio device or between the first radio device 100-FH and the other radio device or between the first radio device and the node 200-FH.
  • radio devices e.g., device-to-device (D2D) communications or sidelink (SL) communications
  • any radio device may be a mobile or portable station and/or any radio device wirelessly connectable to a base station or RAN, or to another radio device.
  • the radio device may be a user equipment (UE), a device for machine-type communication (MTC) or a device for (e.g., narrowband) Internet of Things (loT).
  • MTC machine-type communication
  • LoT narrowband Internet of Things
  • Two or more radio devices may be configured to wirelessly connect to each other, e.g., in an ad hoc radio network or via a 3GPP SL connection.
  • any base station may be a station providing radio access, may be part of a radio access network (RAN) and/or may be a node connected to the RAN for controlling the radio access.
  • the base station may be an access point, for example a Wi-Fi access point.
  • FIG. 5 schematically illustrates a first example of a communications network 500- FH comprising embodiments of the devices 100-FH and 200-FH performing the methods 300-FH and 400-FH, respectively, in radio communication.
  • the first radio device 100-FH may be in coverage by a base station 1100 of a RAN 502-FH of the communications network 500-FH. Using the SL 510-FH, the first radio device 100-FH may function as a relay radio device for the at least one second radio device 110-FH and/or a further remote radio device 120-FH.
  • the first radio device may establish a SL with another radio device 1000-FH in the step 304-FH, e.g., by virtue of the control message to the other radio device 1000-FH.
  • the connectivity between the further remote radio device 120- FH and the base station 1100-FH can be re-established using the SL between the first radio device 100-FH and the other radio device 1000-FH.
  • the base station 1100-FH may embody the node 200-FH.
  • the first radio device 100-FH may transmit 304-FH a request (as one of the at least one control message) for another resource pool for the SL between the first radio device 100- FH and the other radio device 1000-FH.
  • the other radio device 1000-FH may embody the node 200-FH by establishing the SL with the first radio device 100-FH in response to a control message (of the at least one control message) transmitted to the other radio device 1000-FH.
  • Fig. 6 schematically illustrates a second example of the communications network 500-FH comprising embodiments of the devices 100-FH and 200-FH.
  • the first radio device 100-FH may be a remote radio device that is connected to the RAN 502-FH via the at least one second radio device 110-FH functioning as a relay radio device between the base station 1100-FH of the RAN 502-FH and the first radio device 100-FH using the SL 510-FH.
  • the first radio device 100-FH switches the relayed radio communication to the RAN 502-FH to another path including the other radio device 1000-FH as the relay radio device.
  • the other radio device 1000-FH may embody the node 200-FH by establishing the SL with the first radio device 100-FH in response to a control message (of the at least one control message) transmitted in the step 304-FH to the other radio device 1000-FH.
  • the at least one second radio device 110-FH may also be an embodiment of the device 100-FH.
  • the base station 1100-FH may embody the node 200-FH.
  • the at least one second radio device 110-FH may transmit 304-FH a request (as one of the at least one control message) for another resource pool for the SL 510-FH between the first radio device 100-FH and the at least one second radio device 110-FH.
  • any embodiment of the technique may use NR-based access to unlicensed (i.e., shared) spectrum. That is, the SL and/or the at least one control message and/or the configuration message may use an LBT procedure to access the unlicensed spectrum.
  • Next generation systems i.e., NG or NR or 5G systems
  • NG or NR or 5G systems are support a wide range of use cases with varying requirements, e.g., ranging from fully mobile devices to stationary Internet of Things (loT) or fixed wireless broadband devices.
  • the traffic pattern i.e., the data and the need to transmit the data
  • LAA license-assisted access
  • standalone unlicensed operation are specified by 3GPP.
  • NR-U may use both licensed and unlicensed spectrum.
  • NR-U Compared to the LTE LAA, NR-U supports dual connectivity (DC) and standalone implementations, in which the MAC procedures including random access channel (RACH) and scheduling procedure on unlicensed spectrum are subject to the LBT failures, while there was no such restriction in LTE LAA, since there was licensed spectrum in LAA scenario so the RACH and scheduling related signaling can be transmitted on the licensed spectrum instead of unlicensed spectrum.
  • DC dual connectivity
  • RACH random access channel
  • DRS discovery reference signal
  • PSS primary synchronization signal
  • SSS secondary synchronization signal
  • PBCH physical broadcast channel
  • CSI-RS channel state information reference signal
  • a control channel e.g., a physical uplink control channel (PUCCH) or a physical downlink control channel (PDCCH) or a physical SL control channel (PSCCH)
  • PUSCH physical uplink shared channel
  • PDSCH physical downlink shared channel
  • PSSCH physical SL shared channel
  • SRS uplink or sidelink sounding reference signal
  • channel sensing should be applied to determine the channel availability before the physical signal is transmitted using the channel.
  • the channel sensing is referred to as a clear channel assessment (CCA).
  • CCA clear channel assessment
  • the channel access mechanism is referred to as listen-before- talk (LBT) procedure.
  • the CCA may be, or may be part of, the LBT procedure.
  • Radio Resource Management (RRM) procedures in NR-U may be generally similar to LAA, since NR-U is aiming to reuse technologies such as LAA and/or enhanced (eLAA) and/or further eLAA (feLAA) as much as possible to handle the coexistence between NR-U and other legacy RATs.
  • RRM measurements and report comprising special configuration procedure with respect the channel sensing and channel availability.
  • Channel access (optionally including channel selection) for LAA may be considered an important aspect for co-existence between different RATs such as 3GPP NR and Wi-Fi.
  • LAA according to 3GPP has aimed to use carriers that are congested with Wi-Fi.
  • any of the UEs may measure Reference Signal Received Power (RSRP), and Reference Signal Received Quality (RSRQ) of the downlink radio channel (e.g. SSB, CSI-RS), and provides the measurement reports to its serving base station (e.g., eNB or gNB).
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Received Quality
  • the base station may be referred to as an eNB or gNB for concreteness and not limitation.
  • any radio device may be referred to as a UE for concreteness and not limitation.
  • RSSI Received Signal Strength Indicator
  • 3GPP has defined for LTE LAA measurements of averaged RSSI (as an example of a measure for channel occupancy), e.g., in measurement reports.
  • the channel occupancy is defined as percentage of time that RSSI was measured above a configured threshold.
  • a RSSI measurement timing configuration includes a measurement duration (e.g. 1 ms to 5 ms) and a period between measurements, e.g. 40 ms, 80 ms, 160 ms, 320 ms, or 640 ms.
  • Any of the embodiments may use a channel access procedure as specified for NR- U and/or using at least one of the features or steps as described below.
  • Listen-before-talk is designed for unlicensed spectrum co-existence with other RATs.
  • a radio device applies a clear channel assessment (CCA) check (i.e. channel sensing) before any transmission.
  • CCA clear channel assessment
  • the transmitter involves energy detection (ED) over a time period compared to a certain energy detection threshold (ED threshold) in order to determine if a channel is idle. In case the channel is determined to be occupied, the transmitter performs a random back-off within a contention window before next CCA attempt.
  • an (e.g., positive or negative) acknowledgment i.e., ACK or NACK
  • the transmitter must defer a period after each busy CCA slot prior to resuming back-off.
  • MCOT maximum channel occupancy time
  • a channel access priority based on a service type may be applied. Any embodiment may use at least one of four LBT priority classes, e.g., defined for differentiation of channel access priorities between services using contention window size (CWS) and MCOT duration.
  • CWS contention window size
  • the channel access schemes for NR-based access for unlicensed spectrum can be classified into the categories 1 to 4 (e.g., as described herein further below). For different transmissions in a COT, and/or different channels or signals to be transmitted, different categories of channel access schemes can be used.
  • Any embodiment may apply any UL LBT failure handling for the SL.
  • the RLM RSs may be subject to LBT failures. Therefore, a UE may miss one or several RS receptions, which would impact on triggering of the consistent LBT failure 512-FH.
  • a UE may need to perform an LBT operation. The transmission would be dropped if the LBT operation fails. This can affect how to manage the counters of different MAC procedures such as preamble counter or scheduling request (SR) counter. If the preamble counter is not incremented, the UE 100-FH may delay determining the consistent LBT failure and/or a recovery procedure (e.g., a radio link failure, RLF, procedure), which is certainly not desired.
  • SR scheduling request
  • the MAC entity may be configured by RRC with a consistent LBT failure recovery procedure. Consistent LBT failure is detected per UL BWP by counting LBT failure indications, for all UL transmissions, from the lower layers to the MAC entity.
  • the group RAN2 at 3GPP has agreed to define a UE capability for consistent UL LBT failure detection and recovery. The feature will be optional for the UE.
  • RRC configures the following parameters in the Ibt-FailureRecoveryConfig-. -Ibt-FailurelnstanceMaxCount for the consistent LBT failure detection; -Ibt-FailureDetectionTimer for the consistent LBT failure detection;
  • any of the following UE variables may be used for the consistent LBT failure detection procedure:
  • -LBT_COUNTER-. counter for LBT failure indication which is initially set to 0.
  • Ibt-FailureRecoveryConfig For each activated Serving Cell configured with Ibt-FailureRecoveryConfig, a simplified MAC procedure is described an example. The detailed procedure would be different depending on whether consistent UL LBT failures are detected in the primary cell (PCell or PSCell) or in an SCell.
  • Ibt-FailureDetectionTimer or Ibt-FailurelnstanceMaxCount is reconfigured by upper layers:
  • Any of the UEs described herein may be configured with several BWPs.
  • SL LBT and/or UL LBT failure handling may be operated per BWP.
  • the UE may maintain a timer and a counter for the active BWP. Whenever the UE switches to a different BWP. The UE shall reset the timer and the counter in the new active BWP for detection of SL and/or UL LBT failures. At the same time, the UE resets the timer and the counter in the de-activated BWP. If the active BWP comprises several LBT subbands, it is enough for the UE to keep a common counter across LBT subbands with the same BWP. In other words, an SL and/or UL LBT problem is only declared in case the number of LBT failures from any LBT subbands has reached a predefined counter. Any embodiment may use any one of the recovery actions described below, or specified by 3GPP upon detection of consistent UL LBT failures, in the step 304-FH responsive to the determining 302-FH of the consistent LBT failure of the SL.
  • the first UE 100-FH experiences LBT problems in its current active BWP, it is beneficial for the UE to switch to another BWP prior to triggering of a consistent LBT failure.
  • the first UE 100-FH initiates a random access (RA) on an inactive BWP which has PRACH resource configured.
  • RA random access
  • the gNB can decide if the UE needs to switch to another BWP.
  • the gNB can reply with a DCI or an RRC reconfiguration indicating the new BWP which may be a different one from which the UE has transmitted the RA in.
  • the UE can reset the counter for LBT problem detection.
  • the UE 100-FH may declare a consistent LBT failure for the cell and trigger RRC connection reestablishment.
  • the UE 100-FH may follow an RRC connection reestablishment procedure to recover from the failure, e.g., triggered by the step 304-FH.
  • the UE For a UE configured with SCells, if the UE has detected consistent UL LBT failures in an SCell, the UE informs the gNB of the occurrence of the LBT failures, so the gNB takes appropriate recovery actions, for example, to order the UE to switch to another BWP in the SCell, or to inactivate or de-configure the cell where the UL LBT failures have been detected.
  • a new MAC CE to report this to the network node where SCell belongs to is defined.
  • the new MAC CE (i.e., named as UL LBT failure MAC CE) can indicate the serving cell in which consistent UL LBT failures has been detected.
  • the gNB knows in which BWP the UE is currently active and as a UE only have one active BWP per cell, upon reception of the MAC CE, the gNB can understand that the UE has experienced consistent UL LBT failures in its current active BWP in the indicated cell.
  • the MAC CE format carries a bitmap field to indicate all the cells in which the UE has declared consistent UL LBT failures.
  • the MAC entity When consistent UL LBT failures are detected in a BWP of an SCel I, the MAC entity will trigger a UL LBT failure MAC CE. If there is available UL grant in any serving cell for a new transmission, the UE will indicate to the Multiplexing and assembly entity to include a UL LBT failure MAC CE in the subsequent uplink transmission. If there is no UL grant available, the UE shall trigger a scheduling request for requesting new UL resource for the MAC CE.
  • the MAC CE is also applicable to the primary cell (PCell or PSCell).
  • the UE switches to another BWP and initiates RACH upon declaration of consistent LBT failures.
  • the UE can include the MAC CE (e.g., UL LBT failure MAC CE) in Msg3 so that the gNB can identify the purpose why the RA has been triggered by the UE.
  • the UE informs MN via the SCG failure information procedure after detecting consistent UL LBT failures in all configured BWPs.
  • any implementation of the method 300-FH performing a recovery procedure in the step 304-FH is illustrated in the flow chart of Fig. 7, e.g., when the consistent LBT failure is determined while the first UE 100-FH is in connected mode with a serving cell (option "No" in the step 304-FH) or when the consistent LBT failure is determined while the first UE 100-FH is in connected mode with the second UE 110-FH acting as a relay UE for the first UE 100-FH (option "Yes" in the step 304- FH).
  • any embodiment of any aspect may transmit on the SL (e.g., the SL 510-FH) according to 3GPP NR and/or using any one of the features or steps described herein below.
  • At least one of the following enhancements may be used in any embodiment for a NR sidelink transmissions:
  • - Support for unicast and groupcast transmissions are added in NR sidelink.
  • the physical sidelink feedback channel (PSFCH) is introduced for a receiver UE to reply the decoding status to a transmitter UE.
  • PFCH physical sidelink feedback channel
  • - Grant-free transmissions which are adopted in NR uplink transmissions, are also provided in NR sidelink transmissions, to improve the latency performance.
  • any embodiment of any aspect may use at least one of the physical channels and reference signals mentioned below:
  • PSSCH Physical Sidelink Shared Channel, SL version of PDSCH
  • the PSSCH is transmitted by a sidelink transmitter UE, which conveys sidelink transmission data, system information blocks (SIBs) for radio resource control (RRC) configuration, and a part of the sidelink control information (SCI).
  • SIBs system information blocks
  • RRC radio resource control
  • SCI sidelink control information
  • the PSFCH is transmitted by a sidelink receiver UE for unicast and groupcast, which conveys 1 bit information over 1 RB for the HARQ acknowledgement (ACK) and the negative ACK (NACK).
  • ACK HARQ acknowledgement
  • NACK negative ACK
  • CSI channel state information
  • MAC medium access control
  • CE control element
  • PSCCH Physical Sidelink Common Control Channel, SL version of PDCCH
  • S-PSS/S-SSS Similar to downlink transmissions in NR, in sidelink transmissions, primary and secondary synchronization signals (called S-PSS and S-SSS, respectively) are supported. Through detecting the S-PSS and S-SSS, a UE is able to identify the sidelink synchronization identity (SSID) from the UE sending the S-PSS/S-SSS. Through detecting the S-PSS/S-SSS, a UE is therefore able to know the characteristics of the UE transmitter the S-PSS/S-SSS. A series of process of acquiring timing and frequency synchronization together with SSIDs of UEs is called initial cell search.
  • initial cell search A series of process of acquiring timing and frequency synchronization together with SSIDs of UEs is called initial cell search.
  • the UE sending the S-PSS/S-SSS may not be necessarily involved in sidelink transmissions, and a node (UE/eNB/gNB) sending the S-PSS/S-SSS is called a synchronization source.
  • a node UE/eNB/gNB
  • PSBCH Physical Sidelink Broadcast Channel
  • the PSBCH is transmitted along with the S-PSS/S-SSS as a synchronization signal/PSBCH block (SSB).
  • the SSB has the same numerology as PSCCH/PSSCH on that carrier, and an SSB should be transmitted within the bandwidth of the configured BWP.
  • the PSBCH conveys information related to synchronization, such as the direct frame number (DFN), indication of the slot and symbol level time resources for sidelink transmissions, in-coverage indicator, etc.
  • the SSB is transmitted periodically at every 160 ms.
  • phase tracking reference signal PT-RS
  • channel state information reference signal CSIRS
  • any embodiment of any aspect may use a two-stage sidelink control information (SCI).
  • This a version of the downlink control information (DCI) for the SL 510-FH.
  • DCI downlink control information
  • This part is used for channel sensing purposes (including the reserved time-frequency resources for transmissions, demodulation reference signal (DMRS) pattern and antenna port, etc.) and can be read by all UEs while the remaining (second stage) scheduling and control information such as an 8-bits source identity (ID) and a 16-bits destination ID, new data indicator (NDI), redundancy version (RV) and/or HARQ.
  • ID 8-bits source identity
  • NDI new data indicator
  • RV redundancy version
  • process ID is transmitted on the PSSCH to be decoded by the receiver UE.
  • NR sidelink transmissions have the following two modes of resource allocations:
  • Mode 2 The UE autonomously selects sidelink resources from a (pre-)configured sidelink resource pool(s) based on the channel sensing mechanism.
  • a gNB can be configured to adopt Mode 1 or Mode 2.
  • Mode 2 For the out-of-coverage UE, only Mode 2 can be adopted.
  • Mode 1 supports the two kinds of grants including dynamic grant and configured grant.
  • Dynamic grant When the traffic to be sent over sidelink arrives at a transmitter UE, this UE should launch the four-message exchange procedure to request sidelink resources from a gNB (SR on UL, grant, BSR on UL, grant for data on SL sent to UE).
  • a gNB may allocate a sidelink radio network temporary identifier (SL-RNTI) to the transmitter UE. If this sidelink resource request is granted by a gNB, then a gNB indicates the resource allocation for the PSCCH and the PSSCH in the downlink control information (DCI) conveyed by PDCCH with CRC scrambled with the SL-RNTI.
  • DCI downlink control information
  • a transmitter UE When a transmitter UE receives such a DCI, a transmitter UE can obtain the grant only if the scrambled CRC of DCI can be successfully solved by the assigned SL-RNTI. A transmitter UE then indicates the time-frequency resources and the transmission scheme of the allocated PSSCH in the PSCCH, and launches the PSCCH and the PSSCH on the allocated resources for sidelink transmissions.
  • a grant is obtained from a gNB, a transmitter UE can only transmit a single TB. As a result, this kind of grant is suitable for traffic with a loose latency requirement.
  • Configured grant For the traffic with a strict latency requirement, performing the four-message exchange procedure to request sidelink resources may induce unacceptable latency. In this case, prior to the traffic arrival, a transmitter UE may perform the four-message exchange procedure and request a set of resources. If a grant can be obtained from a gNB, then the requested resources are reserved in a periodic manner. Upon traffic arriving at a transmitter UE, this UE can launch the PSCCH and the PSSCH on the upcoming resource occasion. In fact, this kind of grant is also known as grant-free transmissions.
  • a sidelink receiver UE In both dynamic grant and configured grant, a sidelink receiver UE cannot receive the DCI (since it is addressed to the transmitter UE), and therefore a receiver UE should perform blind decoding to identify the presence of PSCCH and find the resources for the PSSCH through the SCI.
  • CRC is also inserted in the SCI without any scrambling.
  • this transmitter UE when traffic arrives at a transmitter UE, this transmitter UE should autonomously select resources for the PSCCH and the PSSCH. To further minimize the latency of the feedback HARQ. ACK/NACK transmissions and subsequently retransmissions, a transmitter UE may also reserve resources for PSCCH/PSSCH for retransmissions. To further enhance the probability of successful TB decoding at one shot and thus suppress the probability to perform retransmissions, a transmitter UE may repeat the TB transmission along with the initial TB transmission. This mechanism is also known as blind retransmission.
  • this transmitter UE should select resources for the following transmissions:
  • Mode 2 Since each transmitter UE in sidelink transmissions should autonomously select resources for above transmissions, how to prevent different transmitter UEs from selecting the same resources turns out to be a critical issue in Mode 2. A particular resource selection procedure is therefore imposed to Mode 2 based on channel sensing.
  • the channel sensing algorithm involves measuring RSRP on different subchannels and requires knowledge of the different UEs power levels of DMRS on the PSSCH or the DMRS on the PSCCH depending on the configuration. This information is known only after receiver SCI launched by (all) other UEs.
  • the sensing and selection algorithm is rather complex.
  • the communications network 500-FH may comprise a core network (CN) 800-FH, e.g., as schematically illustrated in Fig. 8.
  • the CN 800-FH may comprise an access mobility function (AMF) 802-FH and/or a session management function (SMF) 804-FH, at least one of which may embody the node 200-FH and/or perform the method 400-FH.
  • AMF access mobility function
  • SMF session management function
  • the method 300-FH and/or 400-FH may be performed under the control of an application server 810-FH connected via gateway to the CN 800-FH.
  • NR i.e., two or more SL UEs are deployed in a same or different NR cell.
  • the same principle may be applied to LTE or any other technology that enables the direct connection of two (or more) nearby devices.
  • the detailed embodiments are also applicable to relay scenarios including UE-to-network relay or UE-to-UE relay, e.g., wherein the remote UE and the relay UE may be based on LTE sidelink or NR sidelink, the Uu connection between the relay UE and the base station may be LTE Uu or NR Uu.
  • the method 300-FH and/or 400-FH may be applicable to SL unlicensed operations (i.e., SL transmission on unlicensed band).
  • LBT may also interchangeably called as clear channel assessment (CCA), shared spectrum access procedure, etc.
  • a carrier on which the LBT is applied may belong to a shared spectrum or an unlicensed band or band with contention based access, etc.
  • any embodiment of any aspect may use at least one of the following LBT categories or the categories described in the 3GPP document TR 38.889, version 16.0.0 (which channel access schemes for NR-based access for unlicensed spectrum can be classified into the following categories).
  • the LBT category used by the first UE 100-FH is changed in the step 304-FH responsive to the consistent LBT failure 512-FH.
  • configurable LBT categories comprise at least one of the below LBT categories, but not limited to the below examples.
  • the switching gap from reception to transmission is to accommodate the transceiver turnaround time and is no longer than 16 ps.
  • Category 2 LBT without random back-off
  • the duration of time that the channel is sensed to be idle before the transmitting entity transmits is deterministic.
  • the LBT procedure has the following procedure as one of its components.
  • the transmitting entity draws a random number N within a contention window.
  • the size of the contention window is specified by the minimum and maximum value of N.
  • the size of the contention window is fixed.
  • the random number N is used in the LBT procedure to determine the duration of time that the channel is sensed to be idle before the transmitting entity transmits on the channel.
  • the LBT procedure has the following as one of its components.
  • the transmitting entity draws a random number N within a contention window.
  • the size of contention window is specified by the minimum and maximum value of N.
  • the transmitting entity can vary the size of the contention window when drawing the random number N.
  • the random number N is used in the LBT procedure to determine the duration of time that the channel is sensed to be idle before the transmitting entity transmits on the channel.
  • LBT schemes such as directional LBT, omni directional LBT, or receiver assisted LBT are also applicable and/or combinable with any one of the Categories.
  • LBE Load Based Equipment
  • FBE frame based equipment
  • the LBT schemes may be also referred to as other terms e.g., Type 1 or Type 2 channel access procedures as specified in the 3GPP document TS 37.213, version 16.6.0.
  • the gap from the end of a first transmission in one direction e.g., from UE1 to UE2 to the beginning of a second transmission in the other direction (e.g., from UE2 to UE1) is not more than a fixed period (e.g., 16 ps or 25 ps).
  • a fixed period e.g. 16 ps or 25 ps.
  • Either Category 1 or Category 2 LBT can be chosen prior to the second transmission to avoid latency incurred by usage of Category 4 LBT operations.
  • similar gap periods may be also introduced. However, the value of the gap period may be different from the ones used in the existing unlicensed operation technologies.
  • the term "consistent" LBT failure may be used to indicate that the first UE 100- FH has detected LBT failure consistently according to the step 302-FH, e.g., for a configured time period, or the number of consistently detected LBT failures has reached a configured threshold.
  • the first UE 100-FH Upon declaring consistent LBT failure in the step 302-FH, the first UE 100-FH performs or initiates one or more recovery actions to recover from the consistent LBT failure 512-FH by means of the at least one control message in the step 304-FH.
  • a mechanism to monitor (according to the step 302-FH) and handle (according to the step 304-FH) LBT failures is provided, e.g., based on which, the UE 100-FH is able to trigger an event indicating that the UE 100-FH is experiencing high congestion and/or collision in the current SL link and/or L2 destination and/or resource pool and/or BWP and/or cell and/or carrier and/or frequency band.
  • the event may be for example referred to as consistent LBT failure.
  • the SL transmissions may be performed by the first UE 100-FH in unicast, groupcast, or broadcast. So, LBT failures may occur for any SL transmission in any cast type.
  • the first UE 100-FH may monitor and detect the failure event (e.g., consistent LBT failure) in the step 302-FH by counting LBT failures for any SL transmission in any cast type.
  • the UE may monitor and detect the failure event (e.g., consistent LBT failure) by counting LBT failures for SL transmission per cast type in the step 302-FH.
  • different counters and/or timers may be configured to the first UE 100-FH per cast type for monitoring and detection of the failure event.
  • the failure event may be only detected (i.e., determined in the step 302-FH) for SL transmissions in specific cast type.
  • the first UE 100-FH may determine 302-FH (e.g., declare) a Radio Link failure (RLF) for a SL 510-FH in case:
  • RLF Radio Link failure
  • the first UE 100-FH has determined (e.g., detected) the failure event (e.g., consistent LBT failure) on all resource pools configured and/or preconfigured for the SL 510-FH; and/or
  • the failure event e.g., consistent LBT failure
  • the first UE 100-FH has determined (e.g., detected) the failure event (e.g., consistent LBT failure) on all BWPs of the SL 510-FH.
  • the failure event e.g., consistent LBT failure
  • the event (i.e., the consistent LBT failure 512-FH) may be triggered when at least one of the following conditions is fulfilled.
  • LBT failure may be also caused by any other SL transmission e.g., SL discovery reference signal, etc.
  • a maximum time period since the UE detects the last transmission from a peer UE is reached. In this case, the UE could not receive any SL transmission from the peer UE during this time period.
  • a maximum time period during which the UE has not received any SL synchronization signal (SS) and/or SL broadcast channel (BCH) i.e., a SL synchronization signal block or SL SSB) has been reached from a link UE on the SL or a peer UE of the first UE on the SL.
  • a maximum number of consecutive HARQ. DTX (e.g., no HARQ acknowledgement detected on PSFCH reception occasions by the UE after a HARQ TB transmission) within a configured time period has been detected by the UE in a link and/or resource pool and/or L2 destination.
  • the measured channel occupancy/channel busy ratio/channel usage ratio has exceeded a configured threshold (the condition may be fulfilled for a configured time period).
  • the measured channel quality in terms of RSSI, RSRP, SINR, and/or SIR is above a configured threshold, which condition may be fulfilled for a configured time period.
  • the number of undetected (e.g., misdetected or not detected) radio link monitoring (RLM) reference signals (RSs) transmitted from the second UE is greater than a predefined (e.g., configured) threshold.
  • the consistent LBT failure may be determined if this condition is fulfilled for a predefined (e.g., configured) time period.
  • the first UE 100-FH transmits a report message (briefly: report, as an example of one of the at least one control message) to at least one node 200-FH in the step 304-FH.
  • a report message (briefly: report, as an example of one of the at least one control message)
  • the at least one node 200-FH may comprise one or multiple network nodes 1100- FH including its serving gNBs 1100-FH, and/or its neighbor UEs 1000-FH, entities of the CN 800-FH (e.g., AMF 802-FH and/or SMF 804-FH, etc.) controlling UEs.
  • the report message indicates at least one of the following information.
  • the below information may be transmitted using a single or multiple report messages.
  • any of below information may be reported for a measurement object, a carrier, for a group of carriers, for a certain PLMN, for a cell, per PCI, per BWP, per resource pool, per L2 destination, etc.):
  • Channel occupancy e.g., based on RSSI, Channel busy ratio, or channel usage ratio
  • LBT statistics e.g. number of LBT failures and/or successes, LBT failure/success ratio (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT failure rate (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT types (i.e., Category 1, 2, 3 or 4, directional LBT or omni LBT, receiver assisted LBT etc.) with which the UE has detected LBT failures. Either of these could be reported per LBT type or per CAPC, or per service/LCH/LCG.
  • Radio quality indicators such as RSRP, RSRQ, RSSI, SNR, SINR.
  • Resource allocation mode i.e., Mode 1 or Mode 2 associated with the SL transmissions for which the UE has detected LBT failures
  • Service QoS indicators such as latency, packet loss, priority, jitter, etc.
  • any above report message 512-FH it may be transmitted 304-FH in the same cell and/or gNB, in which failure events or LBT failures (i.e., the consistent LBT failure 512-FH) are being triggered or in a different serving cell and/or gNB.
  • failure events or LBT failures i.e., the consistent LBT failure 512-FH
  • the report may be transmitted in the same resource pool and/or BWP and/or PC5 link (i.e., the SL 510-FH) and/or L2 destination (i.e., MAC destination), in which failure events or LBT failures (i.e., the consistent LBT failure 512-FH) are being triggered or in a different resource pool and/or BWP and/or PC5 link and/or L2 destination.
  • failure events or LBT failures i.e., the consistent LBT failure 512-FH
  • the first UE 100-FH may apply at least one of the below signaling options in the Uu interface (e.g., to the base station 1100-FH embodying the node 200-FH) to transmit 304-FH the report message: RRC signaling (i.e., Uu RRC); a MAC CE; a Control PDU of a protocol layer, e.g., SDAP, PDCP, RLC; and/or LI signaling on physical channels, e.g. PRACH, PUCCH, PDCCH.
  • RRC signaling i.e., Uu RRC
  • a MAC CE i.e., MAC CE
  • Control PDU of a protocol layer e.g., SDAP, PDCP, RLC
  • LI signaling e.g. PRACH, PUCCH, PDCCH.
  • the first UE 100-FH may apply at least one of the below signaling options in the SL 510-FH (i.e., the SL interface) to transmit the report message: RRC signaling (i.e., PC5-RRC); a MAC CE; a control PDU of a protocol layer (e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay); and/or LI signaling on physical channels including PSSCH, PSCCH, PSFCH.
  • RRC signaling i.e., PC5-RRC
  • a MAC CE e.g., MAC CE
  • a control PDU of a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • LI signaling e.g., LI signaling on physical channels including PSSCH, PSCCH, PSFCH.
  • the first UE 100-FH may store the report message and transmit the report to the gNB 1100-FH when the connection to the gNB has resumed.
  • the UE 100-FH may send the report message via a relay UE to the gNB in case of SL relay.
  • the first UE 100-FH may also take at least one of the following actions in the step 304-FH.
  • a first action includes changing to a different resource allocation mode (e.g., changes from Mode 1 to Mode 2, or from Mode 2 to Mode 1).
  • a second action includes changing to a different resource pool to continue SL transmissions.
  • a third action includes changing to a different SL carrier for the SL 510-FH.
  • a fourth action includes changing to a different cell 1102-FH which is SL capable, i.e., able to provide and/or configure the first UE 100-FH with SL resources for the SL 510-FH.
  • a fifth action includes changing to a different BWP of a cell which is SL capable, i.e., able to provide and/or configure SL resources.
  • a sixth action includes changing to a different SL relay UE 1000-FH in case of the second UE 110-FH being a SL relay.
  • a sixth action includes changing to a different gNB (e.g., a different serving base station 1100-FH) which is SL capable, i.e., able to provide and/or configure SL resources to the first UE 100-FH for the SL 510-FH.
  • a different gNB e.g., a different serving base station 1100-FH
  • the first UE 100-FH may trigger at least one of the following procedures in order to detect other carriers and/or BWPs and/or cells and/or resource pools and/or relay UEs and/or gNBs.
  • a first procedure comprises a discovery procedure.
  • a second procedure comprises relay UE selection procedure and/or a relay UE reselection procedure.
  • a third procedure comprises a cell selection procedure and/or a cell reselection procedure.
  • a fourth procedure comprises a handover procedure.
  • a fifth procedure comprises a path switch procedure.
  • the UE 100- FH may be able to recover from the determined consistent LBT failure 512-FH (e.g., the detected event, i.e., consistent LBT failure).
  • the determined consistent LBT failure 512-FH e.g., the detected event, i.e., consistent LBT failure.
  • the BWP may contain multiple bandwidth segments referred to as e.g., channel, subband, BWP segment, etc.
  • the first UE 100-FH may be configured with at least one of the following parameters (e.g., different parameters for different segments): subcarrier spacing (SCS), OFDM symbol duration, and cyclic prefix (CP) length.
  • SCS subcarrier spacing
  • CP cyclic prefix
  • the first UE 100-FH may perform the LBT procedure (i.e., the LBT operation) per channel and/or subband and/or BWP segment.
  • the first UE 100- FH may monitor (in the step 302-FH) and recover (in the step 304-FH) from the consistent LBT failure 510-FH (e.g., the consistent LBT failure) per channel and/or per subband and/or per BWP segment.
  • the node 200-FH [for example the (e.g., serving) gNB 1100-FH and/or a controlling UE 1000-FH] replies with a configuration message according to the step 404-FH upon reception of at least one of the at least one control messages received in the step 402-FH (e.g., the report message) indicating the consistent LBT failure (e.g., detection of the event of the consistent LBT failure) from a first UE 100-FH.
  • the consistent LBT failure e.g., detection of the event of the consistent LBT failure
  • the configuration message may also be referred to as a response message.
  • the configuration message in the step 404-FH may be indicated via at least one of the below signaling means: An RRC signaling (i.e., PC5-RRC), a MAC CE, a control PDU of a protocol layer (e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay), and an LI (i.e. PHY) signaling on physical channels.
  • RRC signaling i.e., PC5-RRC
  • a MAC CE i.e., MAC CE
  • a control PDU of a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • LI i.e. PHY
  • the configuration message in the step 404-FH may provide further signaling to the first UE 100-FH, e.g., to at least one of:
  • one or multiple UE capabilities may be indicate (e.g., signaled) from the first UE 100-FH to the node 200-FH.
  • the one or multiple UE capabilities may be indicative of whether or not the first UE 100-FH supports at least one of the step 302-FH (e.g., LBT failure monitoring) and the step 304-FH (e.g., one or more recovery actions).
  • Fig. 9 shows a schematic block diagram for an embodiment of the device 100-FH.
  • the device 100-FH comprises processing circuitry, e.g., one or more processors 904-FH for performing the method 300-FH and memory 906-FH coupled to the processors 904-FH.
  • the memory 906-FH may be encoded with instructions that implement at least one of the modules 102-FH and 104-FH.
  • the one or more processors 904-FH may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 100-FH, such as the memory 906-FH, radio device functionality.
  • the one or more processors 904- FH may execute instructions stored in the memory 906-FH.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action" may denote the device 100-FH being configured to perform the action.
  • the device 100-FH may be embodied by a radio device 900-FH, e.g., functioning as a transmitting UE.
  • the radio device 900- FH comprises a radio interface 902-FH coupled to the device 100-FH for radio communication with one or more receiving stations, e.g., functioning as a receiving base station or a receiving UE.
  • Fig. 10 shows a schematic block diagram for an embodiment of the device 200-FH (or node 200-FH).
  • the device 200-FH comprises processing circuitry, e.g., one or more processors 1004-FH for performing the method 400-FH and memory 1006- FH coupled to the processors 1004-FH.
  • the memory 1006-FH may be encoded with instructions that implement at least one of the modules 202-FH and 204-FH.
  • the one or more processors 1004-FH may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 100-FH, such as the memory 1006-FH, radio device functionality.
  • the one or more processors 1004-FH may execute instructions stored in the memory 1006-FH.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action” may denote the device 200-FH being configured to perform the action.
  • the device 100-FH may be embodied by another radio device 1000-FH, e.g., functioning as another UE, other than the at least one second radio device 110-FH.
  • the other radio device 1000-FH comprises a radio interface 1002-FH coupled to the device 100-FH for radio communication with the first radio device 100-FH and/or a base station 1100-FH and/or a further remote radio device 120-FH.
  • Fig. 11 shows a schematic block diagram for an embodiment of the device 200-FH (or node 200-FH).
  • the device 200-FH comprises processing circuitry, e.g., one or more processors 1104-FH for performing the method 400-FH and memory 1106- FH coupled to the processors 1104-FH.
  • the memory 1106-FH may be encoded with instructions that implement at least one of the modules 202-FH and 204-FH.
  • the one or more processors 1104-FH may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 200-FH, such as the memory 1106-FH, base station functionality.
  • the one or more processors 1104-FH may execute instructions stored in the memory 1106-FH.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action” may denote the device 200-FH being configured to perform the action.
  • the device 200-FH may be embodied by a base station 1100-FH (e.g., a receiving station), e.g., functioning as a gNB or eNB, optionally serving the first radio device 100-FH.
  • the base station 1100-FH comprises a radio interface 1102-FH coupled to the device 200-FH for radio communication with at least one of the first radio device 100-FH (e.g., functioning as a transmitting UE) and the other radio device 110-FH.
  • a remote radio device for switching a radio communication involving the remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs)
  • the remote radio device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the remote radio device is operable to receive a control message indicative of a status 512-FH of the shared spectrum link on the source path of the relayed radio communication; and switch the relayed radio communication from the source path to the target path depending on the status 512-FH of the shared spectrum link.
  • RATs radio access technologies
  • the remote radio device (e.g., according to the first relay device aspect) may further be operable to perform any of the steps of the first relay method aspects.
  • a remote radio device for switching a radio communication involving the remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the remote radio device is configured to receive a control message indicative of a status 512-FH of the shared spectrum link on the source path of the relayed radio communication.
  • the remote radio device is further configured to switch the relayed radio communication from the source path to the target path depending on the status 512-FH of the shared spectrum link.
  • RATs radio access technologies
  • the radio device (e.g., according to the further first relay device aspect) may be further configured to perform any of the steps of the first relay method aspect.
  • Fig. 12 schematically illustrates a block diagram of an embodiment of a device according to the first relay (RL) aspect, which is generically referred to by reference sign 100-RL.
  • the device 100-RL comprises a modules 104-RL and 106-RL performing the respective steps 304-RL and 306-RL of the first RL method aspect. Any of the modules of the device 100-RL may be implemented by units configured to provide the corresponding functionality.
  • the device 100-RL may also be referred to as, or may be embodied by, the remote radio device.
  • an assisting node for assisting in switching a radio communication involving a remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the assisting node comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the assisting node is operable to determine a status 512-FH of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the assisting node is further operable to transmit, to at least one assisted node other than the assisting node, a control message indicative of the determined status 512-FH of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status 512-FH of the shared spectrum link.
  • the assisting node (e.g., according to the second relay device aspect) may further be operable to perform any one of the steps of the second relay method aspect.
  • an assisting node for assisting in switching a radio communication involving a remote radio device from a source path to a target path.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the assisting node is configured to determine a status 512-FH of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the assisting node is further configured to transmit, to at least one assisted node other than the assisting node, a control message indicative of the determined status 512-FH of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status 512-FH of the shared spectrum link.
  • the assisting node (e.g., according to the further second relay device aspect) may further be configured to perform any one of the steps of the second relay method aspect.
  • Fig. 13 schematically illustrates a block diagram of an embodiment of a device according to the second relay (RL) device aspect, which is generically referred to by reference sign 200-RL, e.g., a relay radio device or a network node (which is referred to by the reference sign 200-NN as a special case of the device 200-RL).
  • RL relay
  • the device 200-RL comprises modules 202-RL and 204-RL performing the respective steps 402-RL and 404-RL of the second RL method aspect.
  • Any of the modules of the device 200-RL may be implemented by units configured to provide the corresponding functionality.
  • the device 200-RL may also be referred to as, or may be embodied by, the assisting node, e.g., any relay node, relay radio device, and/or (e.g., relay) network node.
  • the assisting node e.g., any relay node, relay radio device, and/or (e.g., relay) network node.
  • a network node implementing the assisting node of any one of the second relay device aspect is provided.
  • a relay radio device implementing the assisting node of any one of the second relay device aspect is provided.
  • Fig. 14 shows an example flowchart for a method 300-RL of the first RL method aspect.
  • the method 300-RL of switching a radio communication involving a remote radio device from a source path to a target path is provided.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the method being performed by the remote radio device and comprises or initiates the step 304-RL of receiving a control message indicative of a status 512-FH of the shared spectrum link on the source path of the relayed radio communication.
  • the method further comprises or initiates the step 306-RL of switching the relayed radio communication from the source path to the target path depending on the status 512-FH of the shared spectrum link.
  • RATs radio access technologies
  • the method 300-RL may be performed by the device 100-RL.
  • the modules 104-RL and 106-RL may perform the steps 304-RL and 306-RL, respectively.
  • the radio spectrum shared among multiple RATs may be, or may refer to, unlicensed spectrum.
  • the shared spectrum link (e.g., according to the first relay method aspect) may be subject to a clear channel assessment (CCA) optionally a listen-before-talk (LBT) procedure.
  • CCA clear channel assessment
  • LBT listen-before-talk
  • the first relay node may be a first relay radio device, optionally a relay user equipment, or a first relay network node, optionally a relay base station.
  • the relay network node may be a relay gNB, e.g., a gNB configured to relay the radio communication to another gNB or UE.
  • a relay gNB e.g., a gNB configured to relay the radio communication to another gNB or UE.
  • the direct radio link (e.g., according to the first relay method aspect) may be or may comprise a sidelink (SL), and/or wherein the direct radio link may comprise a PC5 interface.
  • SL sidelink
  • the direct radio link (e.g., according to the first relay method aspect) may comprise at least one of an uplink (UL) and a downlink (DL) and/or wherein the direct radio link may comprise a Uu interface.
  • UL uplink
  • DL downlink
  • the radio communication may be terminated at and/or by the remote radio device.
  • the radio communication may be a radio communication of the remote radio device.
  • the shared spectrum link on the source path may be a link other than the direct radio link between the remote radio device and the relay radio device on the source path.
  • the shared spectrum link and the direct radio link between the remote radio device and the relay radio device may be arranged in series along the source path and/or the target path.
  • the shared spectrum link and the direct radio link between the remote radio device and the relay radio device may be consecutive links on the source path and/or the target path.
  • the direct radio link between the remote radio device and the relay radio device may be a first link or a first hop of the source path (e.g., counting from the remote radio device).
  • the shared spectrum link may be a second link or a second hop of the source path.
  • the direct radio link between the remote radio device and the relay radio device may be a first link or a first hop of the target path (e.g., counting from the remote radio device).
  • the shared spectrum link may be a second link or a second hop of the target path.
  • the direct radio link between the remote radio device and the relay radio device may be a further shared spectrum link.
  • the direct radio link between the remote radio device and the relay radio device may also be subject to a CCA, e.g., an LBT procedure.
  • the shared spectrum link may be a further direct radio link, optionally between the first relay node or a further relay node and a second relay node on the source path or the target path.
  • the shared spectrum link may comprise a PC5 interface, optionally between the first relay node or a further relay node and a second relay node on the source path or the target path.
  • any relay node e.g., the first, second, or further relay node
  • may be a respective relay radio device e.g., the first, second, or further relay radio device, respectively.
  • the second relay node may serve at least one of the remote radio device, the first relay node, and the further relay node, e.g., before and/or after the switching.
  • the shared spectrum link (e.g., according to the first relay method aspect) may comprise at least one of an uplink (UL) and a downlink (DL) optionally between a network node and the first relay node or a further relay node on the source path or the target path.
  • the shared spectrum link may comprise a Uu interface, optionally between a or the network node and the first relay node or a further relay node on the source path or the target path.
  • the network node may serve at least one of the remote radio device, the first relay node, and the further relay node, e.g., before and/or after the switching.
  • the source path (e.g., according to the first relay method aspect) may comprise the first relay node and a or the second relay node.
  • the radio communication may be further relayed on the source path through the second relay node using a direct radio link between the first relay node and the second relay node as the shared spectrum link before the switching.
  • the target path (e.g., according to the first relay method aspect) may comprise the first relay node and a or the second relay node.
  • the radio communication may be further relayed on the target path through the second relay node using a direct radio link between the first relay node and the second relay node as the shared spectrum link after the switching.
  • the radio communication may be relayed on the target path through the first relay node and a or the second relay node using the direct radio link between the remote radio device and the first relay node and using a or the direct radio link between the first relay node and the second relay node after the switching.
  • the source path (e.g., according to the first relay method aspect) may comprise the first relay node.
  • the target path may include a second relay node that is different from the first relay node and not included in the source path.
  • the target path may comprise the first relay node.
  • the radio communication may be relayed through the first relay node on the target path after the switching.
  • the target path may not comprise the first relay node.
  • the first relay node may be replaced by the second radio device on the target path in or after the switching.
  • the radio communication (e.g., according to the first relay method aspect) may be relayed on the target path through a or the second relay node using a or the direct radio link between the remote radio device and the second relay node after the switching.
  • the source path may include a first network node.
  • at least one of the first relay node and the second relay node may be served by the first network node before the switching.
  • the first network node may terminate the relayed radio communication on the source path.
  • the target path may include a or the first network node.
  • at least one of the first relay node and the second relay node may be served by the first network node after the switching.
  • the first network node may also terminate the relayed radio communication on the second path.
  • the target path may include a second network node that is different from the first network node.
  • at least one or each of the first relay node and the second relay node may be served by the second network node after the switching.
  • the second network node may terminate the relayed radio communication on the second path.
  • the first network node may be replaced by the second network node in or after the switching.
  • the control message (e.g., according to the first relay method aspect) may be received from an assisting node.
  • a relay radio device or a network node on the source path or on the target path.
  • the assisting node may be any node (e.g., any relay radio device or any network node) on the source path or the target path.
  • the control message (e.g., according to the first relay method aspect) may be received from at least one of the first relay node, the second relay node, the first network node, and the second network node.
  • the status 512-FH of the shared spectrum link may comprise at least one of a congestion of the shared spectrum link; a channel occupancy for the shared spectrum link; a channel busy ratio for the shared spectrum link; a channel usage ratio for the shared spectrum link; CCA statistics for the shared spectrum link; a number or rate of failures of a CCA of the shared spectrum link; a number or rate of successes of a CCA of the shared spectrum link; LBT statistics for the shared spectrum link; a number or rate of failures of an LBT procedure of the shared spectrum link; a number or rate of successes of an LBT procedure of the shared spectrum link; an LBT type performed on the shared spectrum link, optionally by the assisting node and/or wherein the LBT type is at least one of LBT category 1, LBT category 2, LBT category 3, LBT category 4, directional LBT, omni-directional LBT, and receiver-assisted LBT; a consistent LBT failure (CLF) on the shared spectrum link; and a radio
  • the CLF may be indicative of (e.g., triggered if) a number of consecutive failures of an LBT procedure on the shared spectrum link exceeding a predefined threshold number.
  • the CLF may be indicative of (e.g., triggered if) a time since data has become available for transmission on the shared spectrum link without a successful LBT procedure exceeding a predefined threshold time.
  • the status 512-FH (e.g., according to the first relay method aspect) may be reported per LBT type and/or per channel access priority classes (CAPC) and/or per service using the shared spectrum link and/or per logical channel (LCH) and/or per logical channel group (LCG).
  • CAC channel access priority classes
  • LCH logical channel
  • LCG logical channel group
  • the node e.g., radio device or network node
  • the node on the source path from which the control message is received may be the assisting node.
  • Any node on the source path and/or any node on the target path receiving the control message e.g., the remote radio device
  • the status 512-FH may be based on monitoring the shared spectrum link, optionally by the assisting node.
  • the status 512-FH may be based on statistics of a CCA, optionally an LBT procedure, optionally performed by the assisting node, on the shared spectrum link.
  • the status 512-FH may be based on measuring one or more radio quality indicators for the shared spectrum link, optionally comprising at least one of a received signal strength indicator (RSSI); a reference signal received power (RSRP); a reference signal received quality (RSRQ); a signal-to-noise ratio (SNR); a signal-to-interference ratio (SIR); and a signal-to- interference-and-noise ratio (SINR).
  • RSSI received signal strength indicator
  • RSRP reference signal received power
  • RSRQ reference signal received quality
  • SNR signal-to-noise ratio
  • SIR signal-to-interference ratio
  • SINR signal-to- interference-and-noise ratio
  • the control message may be a report.
  • the control message may comprise a result based on one or more combinations of at least two of the values indicated in the claims 43 to 46.
  • the radio quality indicators may be indicative of a radio link quality of the shared spectrum link.
  • the shared spectrum link (e.g., according to the first relay method aspect) may use radio spectrum that is shared among different radio access technologies (RATs).
  • RATs radio access technologies
  • the shared radio spectrum may be an unlicensed radio spectrum.
  • the relayed radio communication (e.g., according to the first relay method aspect) may be switched from the source path to the target path responsive to the received control message, optionally if at least one of:
  • the status 512-FH is indicative of a CLF and/or a congestion on the shared spectrum link
  • the status 512-FH is indicative a radio quality indicator of the shared spectrum link being less than a predefined threshold quality
  • the status 512-FH is indicative a radio quality indicator of the shared spectrum link being less than a radio quality indicator of a further shared spectrum link.
  • the further shared spectrum link on the target path may replace the shared spectrum link on the source path in or after the switching;
  • the status 512-FH is indicative a congestion of the shared spectrum link on the source path being less than a congestion of a further shared spectrum link on the target path.
  • the further shared spectrum link on the target path may replace the shared spectrum link on the source path in or after the switching.
  • the receiving of the control message may comprise receiving the status 512-FH of two or more shared spectrum links associated with respective two or more target paths or the status 512-FH of two or more target nodes associated with respective two or more target paths or the status 512-FH of two or more target paths.
  • the relayed radio communication may be switched from the source path to the target path for which the received status 512-FH may be indicative of least congestion and/or greatest radio quality indicator.
  • the switching of the relayed radio communication comprising reducing a data transmission rate on the source path and/or increasing a data transmission rate on the target path and/or diverting a data transmission rate from the source path to the target path depending on the status 512-FH of the shared spectrum link on the source path and/or the status 512-FH of a or the further shared spectrum link on the target path.
  • the receiving of the control message may comprise receiving the status 512-FH of a relay radio device on the source path or the target path and the status 512-FH of a network node on the source path or the target path.
  • the relayed radio communication may be selectively switched from the source path to the target path for which the received status 512-FH is indicative of least congestion and/or greatest radio quality indicator.
  • the status 512-FH of relay radio device and the status 512-FH of a network node are shifted relative to each other by an offset for determining the least congestion and/or the greatest radio quality indicator.
  • the receiving of the control message comprises receiving the status 512-FH of a network node on the target path. The relayed radio communication is always switched from the source path to the target path involving the network node for which the status 512-FH is received.
  • the receiving of the control message may comprise receiving the status 512-FH of a relay radio device on the target path.
  • the relayed radio communication is always switched from the source path to the target path involving the relay radio device for which the status 512-FH is received.
  • the remote radio device may refrain from switching from the source path to the target path if the received control message or a subsequent message, optionally received from the assisting node, may be indicative of a recovery of the shared spectrum link and/or of establishing a further shared spectrum link other than the shared spectrum link.
  • Fig. 15 shows an example flowchart for a method 400-RL of the second method aspect.
  • a method 400-RL of assisting in switching a radio communication involving a remote radio device from a source path to a target path is provided.
  • the radio communication is relayed through a first relay node on at least one of the source path and the target path using a direct radio link between the remote radio device and the first relay node.
  • the source path comprises a shared spectrum link using radio spectrum shared among multiple radio access technologies (RATs) the method being performed by an assisting node on the source path and comprises or initiates the step 402-RL of determining a status 512-FH of the shared spectrum link on the source path of the relayed radio communication.
  • RATs radio access technologies
  • the method 400-RL further comprises or initiates the step 404-RL of transmitting, to at least one assisted node other than the assisting node, a control message indicative of the determined status 512-FH of the shared spectrum link for assisting in the switching of the relayed radio communication from the source path to the target path depending on the determined status 512- FH of the shared spectrum link.
  • the method 400-RL may be performed by the device 200-RL (e.g., a network node 200-NN or a relay radio device 200-RL).
  • the modules 202-RL and 204- RL may perform the steps 402-RL and 404-RL, respectively.
  • the determining 402-RL of the status 512-FH may comprise at least one of:
  • BWP bandwidth part
  • the status 512-FH is indicative of a radio link failure (RLF) for the shared spectrum link or for the source path;
  • RLF radio link failure
  • the status 512-FH is indicative of an RLF for the shared spectrum link or for the source path; and switching or performing a handover to at least one of a different cell serving the assisting node, a different network node serving the assisting node, a different carrier for the shared spectrum link or for a further shared spectrum link replacing the shared spectrum link, and different frequency band for the shared spectrum link or for a further shared spectrum link replacing the shared spectrum link or another relay radio device to replace the shared spectrum link for which the status 512-FH is indicative of a congestion or LBT failure.
  • the at least one or each of the at least one assisted node may be on the source path or the target path.
  • At least one or each of the at least one assisted node may be on the source path or the target path.
  • the at least one assisted node (e.g., according to the second relay method aspect) may be or may comprise the remote radio device.
  • the assisting node may be relaying or attempting to relay the radio communication through the shared spectrum link on the source path prior to the switching of the radio communication.
  • the assisting node may be relaying or attempting to relay the radio communication through a or the further shared spectrum link on the target path after the switching of the radio communication.
  • the assisting node e.g., according to the second relay method aspect
  • the shared spectrum link may comprise a Uu interface of the network node.
  • the control message indicative of the status 512-FH may be transmitted periodically and/or event-triggered, optionally to a subset of the at least one assisted node.
  • the event for the event-triggered transmission may comprise any of the quantities (e.g., indicated in claims 43 to 46) exceeding a predefined value.
  • predefined may be configured (e.g., by a network node) or specified by a technical standard.
  • the assisting node may be a relay radio device and the control message may be transmitted using at least one of dedicated radio resource control (RRC) signaling, optionally PC5-RRC signaling; a discovery message, optionally a discovery message for the SL; a PC5-S signaling; a medium access control (MAC) control element (CE); a control protocol data unit (PDU) of a protocol layer of at least one of the radio communication, the source path, the target path, the SL, a service data adaptation protocol (SDAP) a packet data convergence protocol (PDCP) a radio link control (RLC) and an adaptation layer; and a physical layer (L1) signaling, optionally on at least one of a physical SL channels, physical SL shared channel (PSSCH) a physical SL control channel (PSCCH) and a physical sidelink feedback channel (PSFCH).
  • RRC dedicated radio resource control
  • PSSCH physical SL shared channel
  • PSCCH physical SL control channel
  • PSFCH physical sidelink feedback channel
  • the assisting node may be a network node and the control message may be transmitted using at least one of system information (SII; dedicated RRC signaling, optionally Uu-RRC signaling; a paging message; a MAC CE; a control PDU of a protocol layer of at least one of the radio communication, the source path, the target path, the SL, a service data adaptation protocol (SDAP) a packet data convergence protocol (PDCP) a radio link control (RLC) and an adaptation layer; and a physical layer (LI) signaling, optionally on at least one of a physical DL channels, a physical DL shared channel (PDSCH) and a physical DL control channel (PDCCH).
  • SII system information
  • dedicated RRC signaling optionally Uu-RRC signaling
  • a paging message e.g., paging message
  • a MAC CE e.g., a control PDU of a protocol layer of at least one of the radio communication, the source path, the target path,
  • the determining of the status 512-FH of the shared spectrum link may comprise at least one of determining a congestion of the shared spectrum link; determining a channel occupancy for the shared spectrum link; determining a channel busy ratio for the shared spectrum link; determining a channel usage ratio for the shared spectrum link; determining CCA statistics for the shared spectrum link; determining a number or rate of failures of a CCA of the shared spectrum link; determining a number or rate of successes of a CCA of the shared spectrum link; determining LBT statistics for the shared spectrum link; determining a number or rate of failures of an LBT procedure of the shared spectrum link; determining a number or rate of successes of an LBT procedure of the shared spectrum link; determining an LBT type performed on the shared spectrum link, optionally by the assisting node and/or wherein the LBT type is at least one of LBT category 1, LBT category 2, LBT category 3, LBT category 4, directional LBT, omni-directional LBT, and receiver-
  • the CLF may be determined if a number of consecutive failures of an LBT procedure on the shared spectrum link exceeds a predefined threshold number. Alternatively or in addition, the CLF may be determined if a time since data has become available for transmission on the shared spectrum link without a successful LBT procedure exceeds a predefined threshold time.
  • the status 512-FH (e.g., according to the second relay method aspect) may be determined and/or transmitted per at least one of LBT type; channel access priority classes (CAPC); service using the shared spectrum link; logical channel (LCH);
  • LBT type LBT type
  • CAC channel access priority classes
  • LCH logical channel
  • the node e.g., radio device or network node
  • the node on the source path from which the control message is received may be the assisting node.
  • Any node on the source path and/or any node on the target path receiving the control message e.g., the remote radio device
  • the determining of the status 512-FH may comprise at least one of monitoring the shared spectrum link, optionally by the assisting node; and computing statistics of a CCA, optionally an LBT procedure, optionally performed by the assisting node, on the shared spectrum link; measuring, for the shared spectrum link, a received signal strength indicator (RSSI) or a reference signal received power (RSRP) or a reference signal received quality (RSRQ) or a signal-to-noise ratio (SNR) or a signal-to-interference ratio (SIR) or a signal-to-interference-and-noise ratio (SINR).
  • RSSI received signal strength indicator
  • RSRP reference signal received power
  • RSRQ reference signal received quality
  • SNR signal-to-noise ratio
  • SIR signal-to-interference ratio
  • SINR signal-to-interference-and-noise ratio
  • the status 512-FH of the shared spectrum link used by the at least one assisted node may be determined, optionally received from the at least one assisted node.
  • the status 512-FH of the direct radio link as a shared spectrum link used by the remote radio device may be determined, optionally received from the remote radio device.
  • the method may further comprise or initiate the step of receiving, from the at least one assisted node, a status 512-FH of a shared spectrum link used by the at least one assisted node and/or receiving, from the remote radio device, a status 512-FH of a shared spectrum link used by the remote radio device.
  • the status 512-FH of a shared spectrum link may be indicative of the status 512-FH of the direct radio link (e.g., a SL) as a shared spectrum link (e.g., on unlicensed spectrum) between the remote radio device and the first relay node.
  • the status 512-FH of a shared spectrum link may be indicative using any quantity mentioned for the claims 43 to 46 measured channel.
  • the assisting node performing the method may be a network node.
  • transmitting of the status 512-FH may comprise exchanging the determined status 512-FH, optionally the received status 512-FH (e.g., the status 512-FH of the shared spectrum link used by the at least one assisted node), with another network node.
  • Each of the device 100-RL and 200-RL may be a radio device or a network node (e.g., a base station).
  • the technique may be applied to an uplink (UL) and/or downlink (DL) between the remote radio device 100-RL and the node 200-RL and/or direct communications between radio devices, e.g., device-to-device (D2D) communications or sidelink (SL) communications, between the remote radio device 100-RL and the relay radio device or between the remote radio device 100- RL and the other nodes 200-RL.
  • radio devices e.g., device-to-device (D2D) communications or sidelink (SL) communications
  • any radio device may be a mobile or portable station and/or any radio device wirelessly connectable to a base station or RAN, or to another radio device.
  • the radio device may be a user equipment (UE), a device for machine-type communication (MTC) or a device for (e.g., narrowband) Internet of Things (loT).
  • MTC machine-type communication
  • LoT narrowband Internet of Things
  • Two or more radio devices may be configured to wirelessly connect to each other, e.g., in an ad hoc radio network or via a 3GPP SL connection.
  • any base station may be a station providing radio access, may be part of a radio access network (RAN) and/or may be a node connected to the RAN for controlling the radio access.
  • the base station may be an access point, for example a Wi-Fi access point.
  • noise or a signal-to-noise ratio SNR
  • SINR signal-to-noise ratio
  • a corresponding step, feature or effect is also disclosed for noise and/or interference or a signal-to-interference-and-noise ratio (SINR).
  • Embodiments of the technique can be implemented for sidelink transmission on unlicensed spectrum according to next 3GPP releases.
  • Each of the shared spectrum link and/or direct radio link may be a sidelink (SL) on unlicensed spectrum (SL-U).
  • Each of the shared spectrum links may require a channel access mechanism (e.g., as in new radio for unlicensed spectrum, NR-U), which is generically referred to as clear channel assessment (CCA).
  • CCA clear channel assessment
  • a SL-capable radio device and/or a network node may need to perform a listen-before-talk (LBT) operation (also: procedure) prior to a transmission of the shared spectrum link.
  • LBT listen-before-talk
  • the node may experience one or more LBT failures consecutively on the shared radio spectrum (e.g., on an unlicensed carrier).
  • the technique may use, according to 3GPP New Radio (NR) Release 16, SL UE to network (U2N) relay, e.g., in any relay node (e.g., in any relay radio device).
  • SL UE to network (U2N) relay e.g., in any relay node (e.g., in any relay radio device).
  • U2N 3GPP New Radio
  • U2U UE to UE
  • the technique may use, e.g., according to a future 3GPP NR Release 18, a UE to UE (U2U) relay, e.g., in any relay node (e.g., in any relay radio device).
  • Embodiments of the technique can support SL relay in unlicensed band.
  • the status 512-FH may be indicative of a SL relay in unlicensed band, wherein the radio device (e.g., the remote radio device or a relay radio device) experience a consistent LBT failure (CLF).
  • the status 512-FH may be indicative of the network node (e.g., a gNB) as a node on the source path, which may experience consistent LBT failure if a Uu interface is deployed on the shared radio spectrum (e.g., unlicensed band) as an example of the shared radio link.
  • Embodiments of the technique can enable a relay radio device (e.g., an intermediate radio device) as an assisting node on the source path (also referred to as a relay path) to inform about the determined status 512-FH (e.g., a detected failure) to other nodes on the relay path.
  • a relay radio device e.g., an intermediate radio device
  • the determined status 512-FH e.g., a detected failure
  • Same or further embodiments can enable the remote radio device to select the target path (also referred to as a new path) considering the status 512-FH (e.g., as to the failure) received from a relay node (e.g., a relay radio device).
  • a relay node e.g., a relay radio device
  • Same or further embodiments can enable a network node (e.g., a gNB) to determine (e.g., receive and/or detects) a status 512-FH (e.g., an LBT failure) and assist (e.g., control) the remote radio device and/or any relay node (e.g., relay radio device) for the switching of the relayed radio communication.
  • a network node e.g., a gNB
  • determine e.g., receive and/or detects
  • a status 512-FH e.g., an LBT failure
  • assist e.g., control
  • At least one control message may be received from one or more relay nodes on the source and/or target path.
  • the control message may comprise at least one report for one or more nodes.
  • the second relay method aspect may further comprise any feature and/or any step disclosed in the context of the first relay method aspect, or a feature and/or step corresponding thereto, e.g., a receiver counterpart to a transmitter feature or step.
  • the methods which are disclosed herein may comprise at least one of the following features and/or nodes and/or steps.
  • An (e.g., assisting) node (e.g., UE or gNB) on a relay path (e.g., the source path) may monitor (e.g., determine) a congestion or LBT failures on a hop (e.g., the shared spectrum link), which is deployed on shared radio spectrum (e.g., an unlicensed band).
  • the node may transmit signaling (e.g., the control message) to other nodes on the relay path (e.g., the source path or target path).
  • a remote UE may consider (e.g., receive) the information (e.g., the control message) of congestion status 512-FH (e.g., in terms of metrics as described in a first detailed RL embodiment) of a current serving node (e.g., any of the nodes in the source path) and/or target nodes (e.g., any of the nodes in the target path) during the switching (i.e., a path switch procedure).
  • the current serving node may be a gNB or a relay UE.
  • the target nodes may comprise gNBs or relay UEs.
  • any intermediate node on the respective path may be referred to as a serving node, e.g., for the (e.g., source) remote radio device.
  • a serving node may be a gNB or a UE.
  • the remote radio device may select multiple target nodes to setup a new relay path (i.e., switch to the target path). These selected target nodes may be connected between each other to form a relay path (e.g., the target path). Each selected target node may have lowest congestion among all candidate target nodes when the selection is being performed by the remote UE.
  • the first selected target node is the relay node directly connecting to the remote radio device in the first hop (e.g., the direct radio link), while the second selected target node is the next relay node connecting to the first relay node in the second hop etc.
  • the remote UE may determine to keep the current path since the remote UE knows that concerned nodes are performing recovery actions so that it is likely that the path can be recovered soon. After a while if the remote radio device may receive further signaling indicating whether or not high congestion or consistent LBT failure has been recovered, if the recovery was not successful, the remote radio device may determine to trigger a path switch.
  • the remote radio device has determined to trigger a path switch if measured congestion of current serving node fulfils a threshold indicating occurrence of high congestion or consistent LBT failure.
  • a time to trigger may be also defined.
  • the remote UE determines to trigger a path switch if measured congestion of current serving node fulfils the threshold for the configured time to trigger.
  • the remote radio device selects (e.g., in the step of switching) the target node with lowest measured congestion status 512-FH (i.e., with lowest channel occupancy, or LBT failure ratio) among all detected target nodes.
  • the remote radio device is able to switch to a most reliable path on which the remote radio device would be expected to experience less LBT failures.
  • the selected target node shall have lower congestion compared to the current serving node.
  • the remote radio device may also determine to slow down transmission on the path due to occurrence of high congestion or consistent LBT failure. After a while, the remote UE may determine to speed up transmission on the path if the path has recovered from high congestion or consistent LBT failure.
  • the serving gNB may determine to select a target node for the remote radio device considering measured channel congestion.
  • the serving gNB may select a target node with lowest channel congestion for the remote radio device.
  • the technique may be implemented as a method of handling congestion and/or LBT failures for SL relay on the shared radio spectrum (e.g., on an unlicensed band).
  • any relay radio device may be implemented according to the 3GPP Technical Report (TR) 23.752, version 17.0.0, or an extension thereof.
  • Any direct radio link may be a device-to-device (D2D) and/or sidelink.
  • Any relay radio device may be a UE-to-Network relay, Any SL and or any relay radio device may use Proximity- Based Services (ProSe) and/or an lnter-5G Direct Discovery Name Management Function (5G DDNMF).
  • ProSe Proximity- Based Services
  • 5G DDNMF lnter-5G Direct Discovery Name Management Function
  • a communication system including a host computer.
  • the host computer comprises a processing circuitry configured to provide user data.
  • the host computer further comprises a communication interface configured to forward the user data to a cellular network (e.g., the RAN and/or the base station) for transmission to a UE.
  • a processing circuitry of the cellular network is configured to execute any one of the steps of the first and/or second relay method aspects.
  • the UE comprises a radio interface and processing circuitry, which is configured to execute any one of the steps of the first and/or second relay method aspects.
  • the communication system may further include the UE.
  • the cellular network may further include one or more base stations configured for radio communication with the UE and/or to provide a data link between the UE and the host computer using the first and/or second relay method aspects.
  • the processing circuitry of the host computer may be configured to execute a host application, thereby providing data and/or any host computer functionality described herein.
  • the processing circuitry of the UE may be configured to execute a client application associated with the host application.
  • Fig. 16 schematically illustrates a first example of a communications network 500-RL comprising embodiments of the devices 100-RL and 200-RL performing the methods 300-RL and 400-RL, respectively, in radio communication.
  • the remote radio device 100-RL (or remote UE) performs the first method aspect.
  • the remote radio device 100-RL is using the source path 502-RL before the switching 306-RL and the target path 504-RL after the switching.
  • the direct radio link 510-RL is a SL between the remote radio device 100-RL and the first relay radio device 200-RL on the source path 502-RL.
  • the source path further comprises the shared spectrum link 520-RL, for which a status 512-FH (e.g., CLF) is reported in the control message by the network node 200-NN (e.g., via the second radio device 200-RL) and/or the first radio device 200-RL.
  • a status 512-FH e.g., CLF
  • the first radio device 200-RL may be in coverage by the network node 200-NN (e.g., a base station) of a RAN of the communications network 500-RL.
  • the network node 200-NN e.g., a base station
  • the first radio device may transmit 404-RL the control message.
  • CLF consistent LBT failure
  • the term "consistent" LBT failure may be used to indicate that the respective shared spectrum link (e.g., 520-RL) has detected LBT failure consistently according to the step 402-RL, e.g., for a configured time period, or the number of consistently detected LBT failures has reached a configured threshold.
  • the assisting node 200-RL i.e., a relay radio device 200-RL or a network node 200-NN
  • Fig. 17 schematically illustrates a second example of the communications network 500-RL, wherein the SL 510-RL is kept when switching to the target path 504-RL.
  • Figs. 18 and 19 schematically illustrates a third and fourth example of the communications network 500-RL, wherein like reference signs indicate functionally equal or exchangeable features.
  • the paths 502-RL and 504-RL share a common Uu interface between a third relay radio device 200-RL and the serving network node 200-NN.
  • Any node on the source or target path may perform (e.g., NR-based) access to the shared radio spectrum (e.g., unlicensed spectrum), e.g., according to 3GPP NR-U.
  • the shared radio spectrum e.g., unlicensed spectrum
  • Next generation systems are expected to support a wide range of use cases with varying requirements ranging from fully mobile devices to stationary loT or fixed wireless broadband devices.
  • the traffic pattern associated with many use cases is expected to consist of short or long bursts of data traffic with varying length of waiting period in between (here called inactive state).
  • both license assisted access and standalone unlicensed operation are to be supported in 3GPP.
  • the procedure of PRACH transmission and/or SR transmission in unlicensed spectrum shall be investigated in 3GPP.
  • NR-U and channel access procedure for an unlicensed channel based on LBT is introduced.
  • Any embodiment may implement NR-U by at least one of the following features.
  • NR-U In order to tackle with the ever increasing data demanding, NR is supported on both licensed and unlicensed spectrum (i.e., referred to as NR-U). Compared to the LTE LAA, NR-U supports DC and standalone scenarios, where the MAC procedures including RACH and scheduling procedure on unlicensed spectrum are subject to the LBT failures, while there was no such restriction in LTE LAA, since there was licensed spectrum in LAA scenario so the RACH and scheduling related signaling can be transmitted on the licensed spectrum instead of unlicensed spectrum.
  • DRS discovery reference signal
  • PSS/SSS PSS/SSS
  • PBCH PBCH
  • CSI-RS control channel transmission
  • PUCCH/PDCCH physical data channel
  • PUSCH/PDSCH physical data channel
  • uplink sounding reference signal such as SRS transmission
  • the Radio Resource Management (RRM) procedures in NR-U may be similar to RRM procedures in LAA, since NR-U is aiming to reuse Licensed-Assisted Access (LAA) and/or enhanced LAA (eLAA) and/or further enhanced LAA (feLAA) technologies as much as possible to handle the coexistence between NR-U and other legacy radio access technologies (RATs).
  • RRM measurements and report comprising special configuration procedure with respect the channel sensing and channel availability.
  • LAA channel access/selection for LAA was one of important aspects for co- existence with other RATs such as Wi-Fi.
  • LAA has aimed to use carriers that are congested with Wi-Fi.
  • UE measures Reference Signal Received Power (RSRP), and Reference Signal Received Quality (RSRQ) of the downlink radio channel (e.g. SSB, CSI-RS), and provides the measurement reports to its serving eNB/gNB.
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Received Quality
  • RSSI Received Signal Strength Indicator
  • RSSI measurements can assist the gNB/eNB to detect the hidden node. Additionally, the gNB/eNB can measure the load situation of the carrier which is useful for the network to prioritize some channels for load balance and channel access failure avoidance purposes.
  • LTE LAA has defined to support measurements of averaged RSSI and/or channel occupancy for measurement reports.
  • the channel occupancy is defined as a percentage of time when the measured RSSI is above a predefined (e.g., configured) threshold.
  • a RSSI measurement timing configuration includes a measurement duration and a period between measurements.
  • the measurement duration may be in the range of 1 ms to 5 ms.
  • the period between measurements may be 40, 80, 160, 320, 640 ms.
  • LBT Listen-Before-Talk
  • the LBT mechanism mandates a device to sense for the presence of other users' transmissions in the channel before attempting to transmit.
  • the device performs clear channel assessment (CCA) checks on the channel using energy detection (ED) before transmitting. If the channel is found to be idle, i.e. energy detected is below a certain threshold, the device is allowed to transmit. Otherwise, if the channel is found to be occupied, the device must defer from transmitting.
  • CCA clear channel assessment
  • ED energy detection
  • any embodiment of any aspect may use a channel access scheme described in the 3GPP Technical Report (TR) 38.889, version 16.0.0.
  • TR Technical Report
  • the channel access schemes for NR-based access for unlicensed spectrum can be classified into the following Categories 1 to 4 mentioned above (e.g., in the context of the FH aspect).
  • NR-U supports two different LBT modes, dynamic and semi-static channel occupancy for two types of equipment; Load based Equipment (LBE) and Frame based equipment (FBE), respectively.
  • LBE Load based Equipment
  • FBE Frame based equipment
  • the COT may be shared (e.g., in NR unlicensed spectrum), e.g., as illustrated in Fig. 21 and/or 31, e.g. as opposed to the unshared COT illustrated schematically in Fig. 20.
  • a node e.g., NR-U gNB/UE, LTE-LAA eNB/UE, or Wi-Fi AP/STA
  • a clear channel assessment CCA
  • This procedure typically includes sensing the medium to be idle for a number of time intervals. Sensing the medium to be idle can be done in different ways, e.g. using energy detection, preamble detection or using virtual carrier sensing. Where the latter implies that the node reads control information from other transmitting nodes informing when a transmission ends.
  • TXOP transmission opportunity
  • COT Channel Occupancy Time
  • ACKs data reception acknowledgements
  • CCA clear channel assessment
  • the SIFS duration is used to accommodate for the hardware delay to switch the direction from reception to transmission.
  • Fig. 20 und Fig. 21 schematically illustrate a transmission opportunities (TXOP) both with and without COT sharing, wherein CCA is performed by the initiating node (e.g., gNB).
  • TXOP transmission opportunities
  • the gap between DL and UL transmission is less than a predefined threshold, e.g., 16 us.
  • a predefined threshold e.g. 16 us.
  • Any of the embodiment may use for the direct radio link a sidelink (SL, also: SL transmission) in NR, e.g., using at least some of the features described below.
  • Any relay radio device may implement a Layer 2 (L2) UE-to-Network relay, e.g., comprising at least some of the below described features.
  • L2 Layer 2
  • the protocol architecture supporting a L2 UE-to-Network Relay UE is provided.
  • the L2 UE-to-Network Relay UE provides forwarding functionality that can relay any type of traffic over the PC5 link.
  • the L2 UE-to-Network Relay UE provides the functionality to support connectivity to the 5GS for Remote UEs.
  • a UE is considered to be a Remote UE if it has successfully established a PC5 link to the L2 UE-to-Network Relay UE.
  • a Remote UE can be located within NG-RAN coverage or outside of NG-RAN coverage.
  • Fig. 22 illustrates the protocol stack for the user plane transport, related to a PDU Session, including a Layer 2 UE-to-Network Relay UE.
  • the PDU layer corresponds to the PDU carried between the Remote UE and the Data Network (DN) over the PDU session.
  • the PDU layer corresponds to the PDU carried between the Remote UE and the Data Network (DN) over the PDU session.
  • DN Data Network
  • the two endpoints of the PDCP link are the Remote UE and the gNB.
  • the relay function is performed below PDCP. This means that data security is ensured between the Remote UE and the gNB without exposing raw data at the UE-to-Network Relay UE.
  • Fig. 22 and/or the Figure A.2.1-1 in the 3GPP document TR 23.752, e.g., version 17.0.0, illustrates a User Plane Stack for L2 UE-to-Network Relay UE.
  • the adaptation rely layer within the UE-to-Network Relay UE can differentiate between signaling radio bearers (SRBs) and data radio bearers (DRBs) for a particular Remote UE.
  • SRBs signaling radio bearers
  • DRBs data radio bearers
  • the adaption relay layer is also responsible for mapping PC5 traffic to one or more DRBs of the Uu.
  • the definition of the adaptation relay layer is under the responsibility of RAN WG2.
  • Fig. 23 illustrates the protocol stack of the NAS connection for the Remote UE to the NAS-MM and NAS-SM components.
  • the NAS messages are transparently transferred between the Remote UE and 5G-AN over the Layer 2 UE-to-Network Relay UE using:
  • the role of the UE-to-Network Relay UE is to relay the PDUs from the signaling radio bearer without any modifications.
  • the radio access network is indicated at reference sign 820-RL.
  • the core network is indicated at reference sign 810-RL.
  • any relay radio device may implement a Layer 3 (L3) UE-to-Network relay, e.g., comprising at least some of the features or steps described below and/or according to the 3GPP document TR 23.752, clause 6.6, in which a layer-3 based UE-to-Network relay is described.
  • L3 Layer 3
  • the ProSe 5G UE-to-Network Relay entity provides the functionality to support connectivity to the network for Remote UEs (see Fig. 24). It can be used for both public safety services and commercial services (e.g. interactive service).
  • a UE is considered to be a Remote UE for a certain ProSe UE-to-Network relay if it has successfully established a PC5 link to this ProSe 5G UE-to-Network Relay.
  • a Remote UE can be located within NG-RAN coverage or outside of NG-RAN coverage.
  • Fig. 24 and/or Figure 6.6.1-1 in the in 3GPP document TR 23.752 illustrates an architecture model using a ProSe 5G UE-to-Network Relay.
  • the ProSe 5G UE-to-Network Relay shall relay unicast traffic (UL and DL) between the Remote UE and the network.
  • the ProSe UE-to-Network Relay shall provide generic function that can relay any IP traffic.
  • a one-to-one Direct Communication may be used between the remote radio device and any of the relay radio device (e.g., ProSe 5G UE-to-Network Relays) for unicast traffic, e.g., as specified in solutions for Key Issue #2 in the 3GPP document TR 23.752.
  • the relay radio device e.g., ProSe 5G UE-to-Network Relays
  • the protocol stack for Layer-3 UE-to-Network Relays is shown in Fig. 25.
  • Fig. 25 and/or Figure 6.6.1-2 in the 3GPP document TR 23.752 schematically illustrate Protocol stack for ProSe 5G UE-to- Network Relay.
  • Hop-by-hop security is supported in the PC5 link and Uu link. If there are requirements beyond hop-by-hop security for protection of Remote UE's traffic, security over IP layer needs to be applied.
  • the embodiments are described in the context of NR, i.e., two or more SL UEs are deployed in a same or different NR cell. However, the same principle may be applied to LTE or any other technology that enables the direct connection of two (or more) nearby devices.
  • the embodiments are also applicable to relay scenarios including UE to network relay or UE to UE relay where the remote UE and the relay UE may be based on LTE sidelink or NR sidelink, the Uu connection between the relay UE and the base station may be LTE Uu or NR Uu.
  • LBT may also interchangeably called as clear channel assessment (CCA), shared spectrum access procedure etc.
  • CCA clear channel assessment
  • the carrier on which the LBT is applied may belong to a shared spectrum or an unlicensed band or band with contention based access etc.
  • the configurable LBT schemes comprise at least one of the 4 LBT categories and/or types mentioned above, but not limited to the below examples.
  • the embodiments disclosed herein are applicable to SL transmissions on unlicensed band with any cast type including unicast, groupcast and broadcast.
  • the BWP may contain multiple bandwidth segments referred to as e.g., channel, sub-band, BWP segment etc., for each segment, it may be configured with at least one of the following parameters: subcarrier spacing (SCS), symbol duration, and cyclic prefix (CP) length.
  • SCS subcarrier spacing
  • CP cyclic prefix
  • the UE may perform LBT operation per channel and/or subband and/or BWP segment.
  • the embodiments are applicable to both L2 based relay scenarios and L3 based relay scenarios.
  • a relay scenario may be a U2N relay or U2U relay, or a mixed of U2N and U2U, meaning that a relay path between a source remote UE and a destination node (e.g., gNB or UE) may comprise multiple intermediate nodes which may be gNB or UE.
  • a relay path may contain at least 2 hops.
  • the nodes e.g., UE or gNB
  • the nodes is configured to monitor congestion status 512-FH of the hop in terms of metrics including at least one of the following
  • Channel occupancy e.g., based on RSSI, Channel busy ratio, or channel usage ratio
  • LBT statistics e.g., number of LBT failures and/or successes, LBT failure/success ratio (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT failure rate (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT types (i.e., Category 1, 2, 3 or 4, directional LBT or omni-directional LBT, receiver assisted LBT, etc.) with which the UE has detected LBT failures. Either of these could be reported per LBT type or per CAPC, or per service/LCH/LCG.
  • Radio quality indicators such as RSRP, RSRQ, RSSI, SNR, SIR, SINR, etc.
  • the nodes may further formulate a report signaling including measurement results of one or more or combination of above metrics, and send the report to the other nodes on the relay path.
  • the report may be also sent to gNB or the core network entities (e.g., AMF, SMF, etc.).
  • the report may be sent to other nodes in a periodical fashion or Event trigger fashion, in addition, another node may send a request message to the nodes of the hop on unlicensed band for requesting a report message. After reception of the request message, the nodes send a corresponding report message back to the requesting node.
  • the gNB may experience high congestion or consistent LBT failure, in this case, the gNB may send a signaling to other nodes on the relay path and informing them of occurrence of high congestion or consistent LBT failure on the Uu hop.
  • the concerned node may also perform at least one of the following recovery actions: 1) If high congestion or consistent LBT failure is being detected in the current BWP, the node changes to a different BWP 2) If high congestion or consistent LBT failure is being detected in a resource pool, the node changes to a different resource pool for further transmission and/or reception 3) If the node has detected high congestion or consistent LBT failure in all BWPs, or at least a configured number of BWPs, the node may declare RLF for the hop.
  • the node may declare RLF for the hop 5)
  • the node may declare RLF for the relay path 6)
  • the node may switch or handover to a different cell / gNB / carrier / frequency band.
  • the node may send signaling to the other nodes on the relay path indicating at least one of the following - Occurrence of high congestion or consistent LBT failure on a hop or multiple hops - the detected high congestion or consistent LBT failure on a hop or multiple hops is being under recovery - whether the one or multiple hops where high congestion or consistent LBT failure occurs have been recovered
  • the report or signaling is sent by a UE to another UE via at least one of the following signaling alternatives - Dedicated RRC signaling (e.g., PC5-RRC signaling) - Discovery message - PC5-S signaling - MAC CE - Control PDU of a protocol layer (e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay) - L1 signaling on channels (e.g., PSSCH, PSCCH, PSFCH, etc.)
  • the report or signaling is sent by a UE to gNB via at least one of the following signaling alternatives -
  • the UE or the gNB may measure congestion of neighbor cells, carriers, band or neighbor UEs in terms of metrics as described in the first embodiment.
  • the UE or the gNB may also send report message or signaling to other nodes using similar signaling alternatives as described in the first embodiment.
  • a remote UE considers information of congestion status 512-FH (in terms of metrics as described in the first embodiment) of current serving node and/or target nodes during path switch procedure.
  • the current serving node may be a gNB or a relay UE.
  • the target nodes may contain gNBs or relay UEs.
  • the remote UE may determine to keep the current path since the remote UE knows that concerned nodes are performing recovery actions so that it is likely that the path can be recovered soon. After a while if the remote UE may receive further signaling indicating whether or not high congestion or consistent LBT failure has been recovered, if the recovery was not successful, the remote UE may determine to trigger a path switch.
  • the remote UE has determined to trigger a path switch if measured congestion of current serving node fulfils a threshold indicating occurrence of high congestion or consistent LBT failure.
  • a time to trigger may be also defined. In this case, the remote UE determines to trigger a path switch if measured congestion of current serving node fulfils the threshold for the configured time to trigger.
  • the remote UE selects the target node with lowest measured congestion status 512-FH (i.e., with lowest channel occupancy, or LBT failure ratio) among all detected target nodes. In this case, the remote UE is able to switch to a most reliable path on which the remote UE would be expected to experience less LBT failures. In addition, the selected target node shall have lower congestion compared to the current serving node.
  • lowest measured congestion status 512-FH i.e., with lowest channel occupancy, or LBT failure ratio
  • the remote UE may also determine to slow down transmission on the path due to occurrence of high congestion or consistent LBT failure. After a while, the remote UE may determine to speed up transmission on the path if the path has recovered from high congestion or consistent LBT failure.
  • the remote UE may apply one of the following options to determine whether the target gNB or the target relay UE shall be chosen.
  • Option 1 the measured channel congestion (in terms of metrics as described in the first embodiment) of the gNB is compared to that of the relay UE directly. In this option, the remote UE selects the one with lower channel congestion.
  • Option 2 always select gNB if there is any.
  • Option 3 always select relay UE if there is any
  • an offset is introduced in order to compare channel congestion between a target gNB or a relay UE.
  • the offset may be a positive or negative value.
  • the offset may be added to the measured channel congestion of the target gNB.
  • the offset may be added to the measured channel congestion of the relay UE.
  • Fig.26 schematically illustrates a radio device 100-RL (labeled UE1) as the remote radio device receiving in the step 304-RL an indication (i.e., the control message) that the relay radio device 200-RL (i.e., UE2) has detected a consistent LBT failure on the Uu interface as an example of a shared spectrum link.
  • the remote radio device 100-RL i.e., UE1 triggers a path switch, i.e., switches to the target path in the step 306-RL.
  • Fig.27 schematically illustrates a radio device 100-RL (i.e., UE1) as the remote radio device receiving indication (i.e., the control message) in the step 304-RL that the relay radio device 200-RL (i.e., UE2) has detected a consistent LBT failure (CLF) on the Uu interface 512-FH.
  • CLF LBT failure
  • the remote radio device 100-RL (i.e., UE1) keeps the current path, i.e., refrains from switching in the step 306-RL. Transmitting and receiving steps associated to the different instances of the control message are indicated by appending "A" and "B" to the respective reference signs.
  • the serving gNB may determine to select a target node for the remote UE considering measured channel congestion. The serving gNB may select a target node with lowest channel congestion for the remote UE. For a target node, the serving gNB may not obtain the measured channel congestion from the remote UE.
  • the serving gNB may obtain the measured channel congestion from the target node by itself via at least one of the following alternatives.
  • Alternative 1 the serving gNB may send a request message to the target node. After reception of the request message, the target node sends a response message containing the measured congestion to the serving gNB. If the target node is another gNB, the request message and the response message are exchanged between the serving gNB and the target gNB via inter-gNB signaling interface. If the target node is another relay UE. The request message and the response message are exchanged between the serving gNB and the target relay UE via the Uu interface.
  • gNBs exchange measured channel congestion between each other.
  • a gNB may signal its measured channel congestion to another gNB periodically or when certain condition fulfils.
  • a gNB may signal its measured channel congestion to another gNB if the measured channel congestion is above a threshold (optionally the condition is fulfilled for a configured time period).
  • a gNB may signal its measured channel congestion to another gNB if the measured channel congestion is below a threshold (optionally the condition is fulfilled for a configured time period).
  • a gNB may signal its measured channel congestion to another gNB if the variation of the measured channel congestion is above a threshold (optionally the condition is fulfilled for a configured time period).
  • a gNB may signal its measured channel congestion to another gNB every X ms/slots/OFDM symbols.
  • the measured channel congestion may be signaled by a gNB to a central unit (CU).
  • the CU may further distribute the measurement results among other distributed units (DUs) or gNBs.
  • DUs distributed units
  • gNBs distributed node
  • Fig. 28 shows a schematic block diagram for an embodiment of the device 100-RL.
  • the device 100-RL comprises processing circuitry, e.g., one or more processors 1304-RL for performing the method 300-RL and memory 1306-RL coupled to the processors 1304-RL.
  • the memory 1306-RL may be encoded with instructions that implement at least one of the modules 104-RL and 106-RL.
  • the one or more processors 1304-RL may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 100-RL, such as the memory 1306-RL, remote radio device functionality.
  • the one or more processors 1304-RL may execute instructions stored in the memory 1306-RL.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action” may denote the device 100-RL being configured to perform the action.
  • the device 100-RL may be embodied by a remote radio device (also referred to by 1300-RL), e.g., functioning as a remote UE.
  • the remote radio device 1300-RL comprises a radio interface 1302-RL coupled to the device 100-RL for radio communication with one or more other radio devices o network nodes, e.g., functioning as a relay nodes.
  • Fig. 29 shows a schematic block diagram for an embodiment of the device 200-RL, also referred to by 1400-RL.
  • the device 200-RL comprises processing circuitry, e.g., one or more processors 1404-RL for performing the method 400-RL and memory 1406-RL coupled to the processors 1404-RL.
  • the memory 1406-RL may be encoded with instructions that implement at least one of the modules 202- RL and 204-RL.
  • the one or more processors 1404-RL may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 200-RL, such as the memory 1406-RL, (e.g., relay) network node functionality and/or relay radio device functionality.
  • the one or more processors 1404-RL may execute instructions stored in the memory 1406-RL.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action” may denote the device 200-RL being configured to perform the action.
  • the device 200-RL may be embodied by a relay radio device station 1400-RL, e.g., functioning as a relay UE.
  • the relay radio device 1400-RL comprises a radio interface 1402-RL coupled to the device 200-RL for radio communication with one or more receiving stations, e.g., functioning as a receiving base station or a receiving UE.
  • Fig. 30 shows a schematic block diagram for an embodiment of the device 200-NN, also referred to by 1500-RL.
  • the device 200-NN comprises processing circuitry, e.g., one or more processors 1504-RL for performing the method 400-RL and memory 1506-RL coupled to the processors 1504-RL.
  • the memory 1506-RL may be encoded with instructions that implement at least one of the modules 202-RL and 204-RL.
  • the one or more processors 1504-RL may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and/or encoded logic operable to provide, either alone or in conjunction with other components of the device 200-NN, such as the memory 1506-RL, network node functionality.
  • the one or more processors 1504-RL may execute instructions stored in the memory 1506-RL.
  • Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein.
  • the expression "the device being operative to perform an action” may denote the device 200-NN being configured to perform the action.
  • the device 200-NN may be embodied by a (e.g., relay) network node 1500-RL, e.g., functioning as a (e.g., relay) base station.
  • the network node 1500-RL comprises a radio interface 1502-RL coupled to the device 200-NN for radio communication with one or more radio devices and/or network nodes, e.g., functioning as the remote radio device and/or the relay radio device.
  • Figs. 20 and 21 illustrates an example on COT sharing, which may be used for any embodiment according to the preemptive (PR) aspect, e.g., as described above in the context of the RL aspect.
  • Fig. 31 illustrates an example on COT sharing, which may be used for any embodiment according to the PR aspect.
  • a radio device e.g., a UE
  • accesses a medium via Cat-4 LBT with a configured grant outside of a gNB COT it is also possible for UE and gNB to share the UE acquired COT to schedule DL data to the same UE.
  • UE COT information can be indicated in UCI such as CG-UCI for configured grant PUSCH resources.
  • Any embodiment of the PR aspect may use Dynamic Channel Occupancy by load based LBE.
  • a work item (Wl) of 3GPP Release 16 for NR-U specifies a dynamic channel access mechanism for an LBE type device.
  • This procedure is designed to randomize the start of transmissions from different nodes that want to access the channel at the same time.
  • category 4 LBT This procedure is commonly known as category 4 (CAT4) LBT, the detailed procedure for category 4 LBT (also named as Type 1 channel access in the 3GPP document TS 37.213, version 16.6.0) is described as below.
  • a UE may transmit the transmission using Type 1 channel access procedure after first sensing the channel to be idle during the slot durations of a defer duration T d , and after the counter N is zero in step 4.
  • the counter N is adjusted by sensing the channel for additional slot duration(s) according to the steps described below.
  • N init N init , where N init is a random number uniformly distributed between 0 and CW p , and go to step 4;
  • step 3 sense the channel for an additional slot duration, and if the additional slot duration is idle, go to step 4; else, go to step 5;
  • the UE may transmit a transmission on the channel, if the channel is sensed to be idle at least in a sensing slot duration T sl when the UE is ready to transmit the transmission and if the channel has been sensed to be idle during all the slot durations of a defer duration T d immediately before the transmission.
  • the UE proceeds to step 1 after sensing the channel to be idle during the slot durations of a defer duration T d .
  • CW p adjustment is described in clause 4.2.2.
  • CW min,p and CW max,p are chosen before step 1 of the procedure above.
  • m p , CW min,p , and CW max,p are based on a channel access priority class p as shown in below Table 1 and/or Table 4.2.1-1 in the 3GPP TS 37.213, version 16.6.0.
  • Any embodiment of the PR aspect may use semi-static channel occupancy by FBE.
  • the semi-static channel occupancy allows an FBE to perform a clear channel assessment per fixed frame period for a duration of single 9us observation slot. If the channel is found to be busy after CCA operation, the equipment shall not transmit during this fixed frame period.
  • the fixed frame period can be set to a value between l and 10 ms and can be adjusted once every 200ms. If the channel is found to be idle, the equipment can transmit immediately up to a duration referred to as channel occupancy time, after which the equipment shall remain silent for at least 5% of said channel occupancy time. At the end of the required idle period, the equipment can resume CCA for channel access.
  • Fig. 32 shows an example of the FBE based channel occupancy operation.
  • the Semi-static channel occupancy generally has difficulty competing with devices that use dynamic channel occupancy (such as LAA or NR-U) for channel access.
  • Dynamic channel occupancy device has the flexibility to access the channel at any time after a successful LBT procedure, while the semi-static channel occupancy devices has one chance for grabbing the channel every fixed frame period. The problems become more exacerbated with longer fixed frame period and higher traffic load.
  • the frame based LBT can be rather inflexible for coordinating channel access between networks. If all the nodes are synchronized, then all nodes will find the channel available and transmit simultaneously and cause interference. If the nodes are not synchronized, then some nodes may have definitive advantages in getting access to the channel over some other nodes.
  • semi-static channel occupancy can be good choice for controlled environments, where a network owner can guarantee absence of dynamic channel occupancy devices and is in control of the behavior of all devices competing to access the channel.
  • semi- static channel occupancy is an attractive solution because access latencies can be reduced to the minimum and lower complexity is required for channel access due to lack of necessity to perform random backoff.
  • FBE operation for the scenario in which it is guaranteed that LBE nodes are absent on a long-term basis (e.g., by level of regulation) and FBE gNBs are synchronized, can achieve at least one of the following: - Ability to use frequency reuse factor 1; and - Lower complexity for channel access due to lack of necessity to perform random backoff.
  • the gNBs need to be time aligned. All gNBs will perform the one-shot 9us LBT at the same time.
  • the UE follows the mechanism whereby one 9 microsecond slot is measured within a 25- microsecond interval.
  • the fixed frame period (FFP) is restricted to values of ⁇ 1ms, 2ms, 2.5ms, 4ms, 5ms, 10ms ⁇ (this is including the idle period).
  • FBE channel sensing is performed at fixed time instants. If the channel is determined busy, the base station adopts a fixed back-off and perform LBT again after the fixed backoff.
  • LBE channel sensing can be performed at any time instance, and random back-off is adopted when the channel is determined to be busy.
  • FBE operation for the scenario where it is guaranteed that LBE nodes are absent on a long term basis (e.g., by level of regulation) and FBE gNBs are synchronized can achieve the following: Ability to use frequency reuse factor 1; Lower complexity for channel access due to lack of necessity to perform random backoff. It is noted that this does not imply that LBE does not have benefits in similar scenarios although there are differences between the two modes of operation. It is also noted that FBE may also have some disadvantages compared to other modes of operation such as LBE, e.g., a fixed overhead for idle time during a frame.
  • a UE may transmit UL transmission burst(s) after DL transmission within a gNB initiated COT.
  • UE transmissions within a fixed frame period can occur if DL transmission for the serving gNB within the fixed frame period are detected.
  • the detection of any DL transmission confirms that the gNB has initiated the COT.
  • the UE should be aware of the start and end of every FFP cycle. Such UE behaviors are not optimum for URLLC like services which require critical latency requirements.
  • UE initiated COT by FBE would be a complementary solution for URLLC.
  • SL-U sidelink transmission on unlicensed spectrum
  • NR-U unlicensed spectrum
  • similar channel access mechanism as in NR-U need to be introduced for SL-U.
  • a SL capable UE may need to perform LBT operation prior to a SL transmission.
  • the UE may experience LBT failures consecutively on an unlicensed carrier. This may occur in case the band is heavily loaded. In this case, it would be beneficial to distribute such information to UEs who are going to access the carrier. In this way, those UEs can avoid wasting time to access the carrier.
  • the band can be avoided to be further loaded so that it can recover from congestion quickly.
  • a UE is able to monitor congestion status (e.g., 512-FH) or failure status (e.g., 512-FH) for an unlicensed resource pool, BWP, link, cell, or carrier. Based on detection of congestion or failure event, the UE reports the information to relevant nodes including neighbor UEs, gNBs, or core network entities.
  • congestion status e.g., 512-FH
  • failure status e.g., 512-FH
  • the UE which detects congestion or failure event may perform actions to recover detected congestion or failure event by itself. Or perform recovery actions following instructions from the gNB or core network entities.
  • the UEs, gNBs, or core network entities which receive reporting message on congestion or failure event may further spread information to neighbor UEs, gNBs, or other network entities, devices, or nodes.
  • Any UE which receives information on congestion or failure event in an unlicensed resource pool, BWP, link, cell, or carrier may perform actions to avoid accessing the resource pool, BWP, link, cell, or carrier where congestion or failure event is being detected.
  • Congestion or failure event in an unlicensed resource pool, BWP, link, cell, or carrier is able to be detected by a UE timely and the information is distributed to other UEs.
  • QoS satisfaction is improved for UE by avoiding accessing congested resource pools, BWPs, links cells, or carriers which are deployed on unlicensed band.
  • the embodiments are described in the context of NR, i.e., two or more SL UEs are deployed in a same or different NR cell. However, the same principle may be applied to LTE or any other technology that enables the direct connection of two (or more) nearby devices.
  • the embodiments are also applicable to relay scenarios including UE to network relay or UE to UE relay where the remote UE and the relay UE may be based on LTE sidelink or NR sidelink, the Uu connection between the relay UE and the base station may be LTE Uu or NR Uu.
  • LBT may also interchangeably called as clear channel assessment (CCA), shared spectrum access procedure etc.
  • CCA clear channel assessment
  • the carrier on which the LBT is applied may belong to a shared spectrum or an unlicensed band or band with contention based access etc.
  • the configurable LBT schemes comprise at least one of the above-mentioned LBT categories or types, but not limited to the below examples.
  • the BWP may contain multiple bandwidth segments referred to as e.g., channel, sub-band, BWP segment etc., for each segment, it may be configured with the following different parameters
  • the UE may perform LBT operation per channel/subband/BWP segment.
  • the UE is configured or preconfigured to monitor congestion status 512-FH of one or multiple resource pool/BWP segment/BWP/PC5 I ink/L2 Destination/cell/carrier/band which are deployed on unlicensed band in terms of metrics including at least one of the following:
  • Channel occupancy e.g., based on RSSI, Channel busy ratio, or channel usage ratio
  • LBT statistics e.g., number of LBT failures and/or successes, LBT failure/success ratio (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT failure rate (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT types (i.e., Category 1, 2, 3 or 4, directional LBT or omni-directional LBT, receiver assisted LBT etc) with which the UE has detected LBT failures. Either of these could be reported per LBT type or per CAPC, or per service/LCH/LCG.
  • Radio quality indicators such as RSRP, RSRQ, RSSI, SNR, SIR, SINR etc.
  • the UE may further formulate a report signaling including measurement results of one or more or combination of above metrics, and send the report to the concerned nodes including the gNB, UEs, core network entities such as AMF, SMF etc.
  • the UE sends the measurement results in terms of the metrics as described in the first embodiment, in at least one of the following fashions:
  • Periodical fashion In this case, one or multiple periodical timers may be defined accordingly; 2) Event trigger fashion. In this case, one or multiple events may be defined accordingly.
  • an event is triggered if the measurement in terms of a metric (e.g., any one of the metrics as described in the first embodiment) is below a given threshold (optionally for a configured time period).
  • a metric e.g., any one of the metrics as described in the first embodiment
  • an event is triggered if the measurement in terms of a metric (e.g., any one of the metrics as described in the first embodiment) is above a given threshold (optionally for a configured time period). In an example, an event is triggered if the measurement in terms of a metric (e.g., any one of the metrics as described in the first embodiment) is above a first threshold (optionally for a configured time period) and below a second threshold (optionally for a configured time period).
  • a metric e.g., any one of the metrics as described in the first embodiment
  • an event is triggered if the measurement in terms of a first metric (e.g., any one of the metrics as described in the first embodiment) is below a first threshold (optionally for a configured time period) and the measurement in terms of a second metric (e.g., any one of the metrics as described in the first embodiment) is below a second threshold (optionally for a configured time period)
  • a first metric e.g., any one of the metrics as described in the first embodiment
  • a second threshold optionally for a configured time period
  • any event may be triggered when one or multiple metrics (e.g., any one or multiple combined metrics as described in the first embodiment) fulfil one or multiple conditions.
  • LBT failure may be also caused by any other SL transmission e.g., transmission of SL discovery reference signal etc.
  • a maximum time period since the UE detects the last transmission from a peer UE is reached. In this case, the UE could not receive any SL transmission from the peer UE during this time period.
  • a maximum number of consecutive HARQ DTX (e.g., no HARQ acknowledgement detected on PSFCH reception occasions by the UE after a HARQ TB transmission) within a configured time period has been detected by the UE in a link/resource pool/L2 destination.
  • the measured channel occupancy/channel busy ratio/channel usage ratio has exceeded a configured threshold (the condition may be fulfilled for a configured time period).
  • the measured channel quality in terms of RSSI, RSRP, SINR, SIR is above a configured threshold (the condition may be fulfilled for a configured time period).
  • the number of mis-detected SL RLM RS (e.g., SL discovery reference signal) transmissions from a link/peer UE is above a configured threshold (the condition may be fulfilled for a configured time period).
  • the UE may declare congestion (e.g., low congestion, medium congestion or high congestion) or failure event (e.g., consistent LBT failure, or RLF) at different granularities, i.e., per resource pool/PC5 link/L2 Destination ID/a group of PC5 links/a group of L2 destination ID/BWP/cell/carrier/a group of carriers/band etc.
  • the UE may declare congestion or failure event according to the following granularities:
  • the UE may first declare congestion/failure event per resource pool.
  • the UE may declare congestion or failure event in that BWP.
  • the UE declares/detects congestion/failure event in all BWPs or in above a configured number of BWPs of a PC5 link, the UE declares congestion or failure event for that link.
  • the UE may declare congestion or failure event for that cell or carrier.
  • the UE declares/detects congestion/failure event in all cel Is/carriers or in above a configured number of cel Is/carriers of a band, the UE declares congestion/failure event in that band.
  • the UE may send reporting signaling to the concerned nodes (e.g., the other UEs, the gNB or the core network entities, e.g., AMF or SMF etc) indicating occurrence of congestion or failure event at different granularities respectively.
  • the concerned nodes e.g., the other UEs, the gNB or the core network entities, e.g., AMF or SMF etc.
  • the signaling indicates at least one of the following information.
  • the below information may be transmitted using a single or multiple messages.
  • any of below information may be reported for a measurement object, a carrier, for a group of carriers, a band, a spectrum, for a certain PLMN, for a cell, per PCI, per BWP, per resource pool, per L2 destination etc.):
  • Channel occupancy e.g., based on RSSI, Channel busy ratio, or channel usage ratio.
  • LBT statistics e.g. number of LBT failures and/or successes, LBT failure/success ratio (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT failure rate (e.g. calculated over a certain time period or using exponential averaging of successive time periods), LBT types (i.e., Category 1, 2, 3 or 4, directional LBT or omni-directional LBT, receiver assisted LBT etc) with which the UE has detected LBT failures. Either of these could be reported per LBT type or per CAPC, or per service/LCH/LCG.
  • Radio quality indicators such as RSRP, RSRQ, RSSI, SNR, SINR, etc.
  • Resource allocation mode i.e., Mode 1 or Mode 2 associated with the SL transmissions for which the UE has detected LBT failures.
  • Service QoS indicators such as latency, packet loss, priority, jitter, etc.
  • ID of the reporting UE e.g. source L2 ID.
  • the UE may not be able to transmit the signaling in the same resource pool/BWP/link/L2 Destination/cell/carrier/band due to congestion or failure event. In this case, the UE may send the signaling in another resource pool/BWP/link/L2 Destination/cell/carrier/band where congestion or failure event is not detected.
  • a serious congestion e.g., high congestion
  • failure event e.g., consistent LBT failure or RLF
  • the UE, the gNB or the core network entity may further distribute the information to its surrounding UEs, gNBs, core network entities, gateways, routers, networks, other neighbor devices or nodes.
  • the UE may only do the distribution if it is in the proximity of the UE from which it receives the signaling, the proximity could be determined based on the location info in the signaling and its own location.
  • the gNB or the core network entity may only distribute the signaling to the neighbor nodes in the proximity of the UE from which it receives the signaling.
  • the gNB may take at least one of the following actions:
  • a gNB may forward the information to another gNB via the inter-gNB interface.
  • the gNB may also indicate the updated access control settings or RRM settings on concerned SL resource pool/BWP/link/L2 Destination/cell/carrier/band.
  • the concerned one or multiple SL resource pool/BWP/link/L2 Destination/carrier/band may be barred for SL access. All SL accesses are barred, or only specific SL access categories or access classes are barred.
  • SL resource allocation related configuration may be updated accordingly considering detected congestion or failure event by the reporting UE.
  • the selection and reselection related configuration may be updated for the concerned SL resource pool/BWP/link/L2 Destination/carrier/band to indicate to the UE to avoid select or reselect the concerned SL resource pool/BWP/link/L2 Destination/carrier/band where congestion or failure event is being detected.
  • the other UEs may also avoid to select or reselect relay UEs which are operated in/with the concerned SL resource pool/BWP/link/L2 Destination/ carrier/band.
  • the other UEs may also avoid handing over or path switching to the concerned SL BWP/link/L2 Destination/ carrier/band.
  • a UE may avoid accessing the concerned one or multiple SL resource pool/BWP segment/BWP/link/L2 Destination/cell/carrier/band.
  • the UE may further switch to other SL resource pool/BWP segment/BWP/link/L2 Destination/cell/carrier/band via a selection and/or reselection procedure, a handover procedure etc.
  • a UE may consider the information during the selection and/or reselection procedure, the handover procedure, the path switch procedure so that the UE determines to select one or multiple SL resource pool/BWP segment/BWP/link/L2 Destination/cell/carrier/band with lowest load /congestion/LBT failure ratio. In this way, the UE can avoid or mitigate occurrence of congestion or LBT failures.
  • the UE may only perform such action if it is in the proximity of the location where congestion or failure event is detected, the proximity could be determined based on the location info in the received information and its own location.
  • the UE who detects the congestion or failure by itself can perform similar actions as described in this embodiment for the receiving UE to recover from the failure or congestion.
  • gNB may conduct information aggregation before sending to the Core Network, e.g. AMF.
  • AMF may send assistance information to gNBs in order to let gNB to do better SL controlling, e.g. control spectrum selection, or offload to WIFI, or to licensed band.
  • AMF may also send assistance information to UEs to use non-3GPP RAT, e.g. WIFI.
  • the assisted information include: SSIS, security keys, etc.
  • RRC signaling e.g., PC5-RRC signaling
  • Control PDU of a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • L1 signaling on channels e.g., PSSCH, PSCCH, PSFCH etc
  • the signaling alternatives are as follows:
  • RRC signaling e.g., Uu-RRC signaling
  • Control PDU of a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • a protocol layer e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay
  • L1 signaling on channels e.g., PRACH, PUCCH, PUSCH etc
  • the signaling is transmitted on the Uu interface
  • the signaling alternative is non-access stratum (NAS) signaling.
  • NAS non-access stratum
  • Fig. 33 illustrates an exemplary flow diagram 400-PR for a method for distributing congestion information of SL transmission in unlicensed band according to one or more embodiments of the first preemptive (PR) aspect.
  • a method implemented by a user equipment for sidelink (SL) transmission on unlicensed band in a communication network comprises measuring one or more congestion metrics for one or more transmission resources on the unlicensed band.
  • the method further comprises generating a congestion report indicating congestion status for the one or more transmission resources based on the one or more congestion metrics.
  • the method further comprises sending the congestion report to a communication device.
  • step 401-PR one or more congestion metrics for one or more transmission resources on the unlicensed band may be measured.
  • a congestion report may be generated based on the one or more congestion metrics, which indicating congestion status 512-FH for the one or more transmission resources.
  • the congestion report may be sent to a communication device.
  • the one or more congestion metrics may include channel occupancy, Listen Before Talk (LBT) statistics, or radio quality indicator.
  • LBT Listen Before Talk
  • the one or more transmission resources may include one or multiple resource pools, BWP segments, BWP or PC5 links, L2 Destinations, cells, carriers or bands.
  • the congestion report may include measurement results of the one or more congestion metrics for the one or more transmission resources.
  • the congestion report 512-FH may include at least one of the following information: resource allocation mode, service QoS indicators, buffer status report or power headroom report.
  • the congestion status 512-FH may include no congestion, low congestion, medium congestion or high congestion.
  • the one or more congestion metrics may be measured periodically.
  • the one or more congestion metrics may be measured in event trigger fashion.
  • the congestion report may include the triggered event and trigging reasons.
  • the one or more congestion metrics may be measured when one or more conditions are fulfilled.
  • the method may further comprise detecting a congestion event or failure event for the one or more transmission resources.
  • detecting a congestion or failure event for the one or more transmission resources may include detecting a congestion or failure event at different granularities.
  • detecting a congestion or failure event for the one or more transmission resources at different granularities may include detecting the congestion or failure event at a first granularity, if the number of transmission resources for which are detected the congestion or failure event at a second granularity is above a configured number, wherein the first granularity may be coarser than the second granularity.
  • the congestion report may include the detected congestion event or failure event for the one or more transmission resources.
  • the congestion report may include location information on where the congestion event or failure event is detected.
  • sending the congestion report to a communication device may include sending the congestion report to the communication device in another transmission resource where the congestion or failure event is not detected, if the congestion report cannot be sent in the one or more transmission resources indicated in the congestion report due to a detected high congestion event or failure event for the one or more transmission resources.
  • the method may further comprise recovering SL transmissions from the detected congestion event or failure event for the one or more transmission resources.
  • the recovering may include selecting or reselecting one or more other transmission resources on the unlicensed band for SL transmission.
  • the communication device may include a user equipment, a NodeB station, an eNodeB station, a gNodeB station, or a core network device.
  • the congestion report may be sent via at least one of radio resource control (RRC) signaling, discovery message, PC5-S signaling, medium access control (MAC) control element (CE), control packet data unit (PDU) of a protocol layer, layer 1 (L1) signaling or non-access stratum (NAS) signaling.
  • RRC radio resource control
  • discovery message eNodeB station
  • PC5-S medium access control
  • CE control element
  • PDU control packet data unit
  • L1 layer 1
  • NAS non-access stratum
  • Fig.34 illustrates an exemplary flow diagram 500-PR for a method for distributing congestion information of SL transmission in unlicensed band according to one or more embodiments of the second PR aspect.
  • a method implemented by a first communication device for sidelink (SL) transmission on unlicensed band in a communication network comprises receiving a congestion report indicating congestion status for one or more transmission resources based on one or more congestion metrics from a second communication device.
  • the method further comprises distributing the congestion report to one or more third communication devices.
  • a congestion report may be received, which indicating congestion status 512-FH for one or more transmission resources based on one or more congestion metrics from a second communication device.
  • the congestion report may be distributed to one or more third communication devices.
  • the one or more congestion metrics may include channel occupancy, Listen Before Talk (LBT) statistics, or radio quality indicator.
  • LBT Listen Before Talk
  • the one or more transmission resources may include one or multiple resource pools, BWP segments, BWP or PC5 links, L2 Destinations, cells, carriers or bands.
  • the congestion report may include measurement results of the one or more congestion metrics for the one or more transmission resources.
  • the congestion report 512-FH may include at least one of the following information: resource allocation mode, service QoS indicators, buffer status report or power headroom report.
  • the congestion status 512-FH may include no congestion, low congestion, medium congestion or high congestion.
  • the congestion report may include a congestion event or failure event for the one or more transmission resources.
  • the congestion report may include location information on where the congestion event or failure event is detected.
  • the method may further comprise if high congestion event or serious failure event for the one or more transmission resources is included in the congestion report, the one or more transmission resources are barred for SL access. In an embodiment, the method may further comprise deactivating or reconfiguring the one or more transmission resources for which the congestion event or failure event is detected.
  • the method may further comprise switching a user equipment served by the first communication device to other transmission resources for which the congestion event or failure event is not detected from the one or more transmission resources for which the congestion event or failure event is detected.
  • the method may further comprise aggregating information received in the congestion report before sending to a core network device.
  • the method may further comprise recovering SL transmissions from the detected congestion event or failure event for the one or more transmission resources.
  • the recovering may include selecting or reselecting one or more other transmission resources on the unlicensed band for SL transmission.
  • the recovering may be performed by a UE in the proximity of the location where the congestion event or failure event is detected.
  • the proximity may be determined based on location information included in the congestion report and the location of the UE's own location.
  • the first communication device may include a user equipment, a NodeB station, an eNodeB station, a gNodeB station, or a core network device.
  • the second communication device may include a user equipment, a NodeB station, an eNodeB station, a gNodeB station, or a core network device.
  • Fig.35 is a block diagram illustrating a network device 600-PR according to some embodiments of the PR aspect. It should be appreciated that the network device 600-PR may be implemented using components other than those illustrated in Fig.35. With reference to Fig.35, the network device 600-PR may comprise at least a processor 601-PR, a memory 602-PR, an interface and a communication medium.
  • RRC radio resource control
  • MAC medium access control
  • CE control element
  • PDU packet data unit
  • L1 layer 1
  • NAS non-access stratum
  • the processor 601-PR, the memory 602-PR and the interface are communicatively coupled to each other via the communication medium.
  • the processor 601-PR includes one or more processing units.
  • a processing unit may be a physical device or article of manufacture comprising one or more integrated circuits that read data and instructions from computer readable media, such as the memory 602-PR, and selectively execute the instructions.
  • the processor 601-PR is implemented in various ways.
  • the processor 601-PR may be implemented as one or more processing cores.
  • the processor 601-PR may comprise one or more separate microprocessors.
  • the processor 601-PR may comprise an application-specific integrated circuit (ASIC) that provides specific functionality.
  • ASIC application-specific integrated circuit
  • the processor 601-PR provides specific functionality by using an ASIC and by executing computer-executable instructions.
  • the memory 602-PR includes one or more computer-usable or computer- readable storage medium capable of storing data and/or computer-executable instructions. It should be appreciated that the storage medium is preferably a non-transitory storage medium.
  • the communication medium facilitates communication among the processor 601-PR, the memory 602-PR and the interface. The communication medium may be implemented in various ways.
  • the communication medium may comprise a Peripheral Component Interconnect (PCI) bus, a PCI Express bus, an accelerated graphics port (AGP) bus, a serial Advanced Technology Attachment (ATA) interconnect, a parallel ATA interconnect, a Fiber Channel interconnect, a USB bus, a Small Computing System Interface (SCSI) interface, or another type of communications medium.
  • PCI Peripheral Component Interconnect
  • AGP accelerated graphics port
  • ATA serial Advanced Technology Attachment
  • ATA parallel ATA interconnect
  • Fiber Channel interconnect a USB bus
  • SCSI Small Computing System Interface
  • the instructions stored in the memory 602-PR may include those that, when executed by the processor 601-PR, cause the network device 600-PR to implement the methods described with respect to Figs. 33 and 34.
  • a network device in a communication network comprises a processor; and a memory communicatively coupled to the processor and adapted to store instructions which, when executed by the processor, cause the network device to perform any one of the steps of the first preemptive method aspect and the second preemptive method aspect.
  • a non-transitory machine-readable medium having a computer program stored thereon is provided.
  • the non- transitory machine-readable executed by a set of one or more processors of a network device, causes the network device to perform any one of the steps of the first preemptive method aspect and the second preemptive method aspect.
  • An embodiment of the present disclosure may be an article of manufacture in which a non-transitory machine-readable medium (such as microelectronic memory) has stored thereon instructions (e.g., computer code) which program one or more data processing components (generically referred to here as a "processor") to perform the operations described above.
  • a non-transitory machine-readable medium such as microelectronic memory
  • instructions e.g., computer code
  • data processing components program one or more data processing components (generically referred to here as a "processor") to perform the operations described above.
  • some of these operations might be performed by specific hardware components that contain hardwired logic (e.g., dedicated digital filter blocks and state machines). Those operations might alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components.
  • a communication system 3600 includes a telecommunication network 3610, such as a 3GPP-type cellular network, which comprises an access network 3611, such as a radio access network, and a core network 3614.
  • the access network 3611 comprises a plurality of base stations 3612a, 3612b, 3612c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 3613a, 3613b, 3613c.
  • Each base station 3612a, 3612b, 3612c is connectable to the core network 3614 over a wired or wireless connection 3615.
  • a first user equipment (UE) 3691 located in coverage area 3613c is configured to wirelessly connect to, or be paged by, the corresponding base station 3612c.
  • a second UE 3692 in coverage area 3613a is wirelessly connectable to the corresponding base station 3612a. While a plurality of UEs 3691, 3692 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 3612.
  • any of the base stations 3612 and the UEs 3691, 3692 may embody the device 100-FH and the device 200-FH, respectively.
  • any of the base stations 3612 and the UEs 3691, 3692 may embody the device 200-NN and the device 200-RL or 100-RL, respectively.
  • the telecommunication network 3610 is itself connected to a host computer 3630, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm.
  • the host computer 3630 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider.
  • the connections 3621, 3622 between the telecommunication network 3610 and the host computer 3630 may extend directly from the core network 3614 to the host computer 3630 or may go via an optional intermediate network 3620.
  • the intermediate network 3620 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 3620, if any, may be a backbone network or the Internet; in particular, the intermediate network 3620 may comprise two or more sub-networks (not shown).
  • the communication system 3600 of Fig. 36 as a whole enables connectivity between one of the connected UEs 3691, 3692 and the host computer 3630.
  • the connectivity may be described as an over-the-top (OTT) connection 3650.
  • the host computer 3630 and the connected UEs 3691, 3692 are configured to communicate data and/or signaling via the OTT connection 3650, using the access network 3611, the core network 3614, any intermediate network 3620 and possible further infrastructure (not shown) as intermediaries.
  • the OTT connection 3650 may be transparent in the sense that the participating communication devices through which the OTT connection 3650 passes are unaware of routing of uplink and downlink communications.
  • a base station 3612 need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 3630 to be forwarded (e.g., handed over) to a connected UE 3691. Similarly, the base station 3612 need not be aware of the future routing of an outgoing uplink communication originating from the UE 3691 towards the host computer 3630.
  • the performance or range of the OTT connection 3650 can be improved, e.g., in terms of increased throughput and/or reliability.
  • the host computer 3630 may indicate to the RAN 502-FH or the base station or the node 200-FH or the device 100-FH (e.g., on an application layer) the QoS of the data (i.e., traffic), which may trigger or control any of the actions for recovering the SL 510-FH (e.g., including establishing another RL 510-FH) according to the step 304-FH and/or 404-FH.
  • the QoS of the data i.e., traffic
  • the performance or range of the OTT connection 3650 can be improved, e.g., in terms of increased throughput and/or reduced latency and/or greater reliability.
  • the host computer 3630 may indicate to the RAN 820- RL or the relay radio device 200-RL or the remote radio device 100-RL (e.g., on an application layer) the QoS of the traffic, which may influence at least one of the determining of the status 512-FH and the switching of the paths 502-RL and 504- RL.
  • a host computer 3710 comprises hardware 3715 including a communication interface 3716 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 3700.
  • the host computer 3710 further comprises processing circuitry 3718, which may have storage and/or processing capabilities.
  • the processing circuitry 3718 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the host computer 3710 further comprises software 3711, which is stored in or accessible by the host computer 3710 and executable by the processing circuitry 3718.
  • the software 3711 includes a host application 3712.
  • the host application 3712 may be operable to provide a service to a remote user, such as a UE 3730 connecting via an OTT connection 3750 terminating at the UE 3730 and the host computer 3710.
  • the host application 3712 may provide user data, which is transmitted using the OTT connection 3750.
  • the user data may depend on the location of the UE 3730.
  • the user data may comprise auxiliary information or precision advertisements (also: ads) delivered to the UE 3730.
  • the location may be reported by the UE 3730 to the host computer, e.g., using the OTT connection 3750, and/or by the base station 3720, e.g., using a connection 3760.
  • the communication system 3700 further includes a base station 3720 provided in a telecommunication system and comprising hardware 3725 enabling it to communicate with the host computer 3710 and with the UE 3730.
  • the hardware 3725 may include a communication interface 3726 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 3700, as well as a radio interface 3727 for setting up and maintaining at least a wireless connection 3770 with a UE 3730 located in a coverage area (not shown in Fig. 37) served by the base station 3720.
  • the communication interface 3726 may be configured to facilitate a connection 3760 to the host computer 3710.
  • the connection 3760 may be direct, or it may pass through a core network (not shown in Fig.
  • the hardware 3725 of the base station 3720 further includes processing circuitry 3728, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the base station 3720 further has software 3721 stored internally or accessible via an external connection.
  • the communication system 3700 further includes the UE 3730 already referred to. Its hardware 3735 may include a radio interface 3737 configured to set up and maintain a wireless connection 3770 with a base station serving a coverage area in which the UE 3730 is currently located.
  • the hardware 3735 of the UE 3730 further includes processing circuitry 3738, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions.
  • the UE 3730 further comprises software 3731, which is stored in or accessible by the UE 3730 and executable by the processing circuitry 3738.
  • the software 3731 includes a client application 3732.
  • the client application 3732 may be operable to provide a service to a human or non-human user via the UE 3730, with the support of the host computer 3710.
  • an executing host application 3712 may communicate with the executing client application 3732 via the OTT connection 3750 terminating at the UE 3730 and the host computer 3710.
  • the client application 3732 may receive request data from the host application 3712 and provide user data in response to the request data.
  • the OTT connection 3750 may transfer both the request data and the user data.
  • the client application 3732 may interact with the user to generate the user data that it provides.
  • the host computer 3710, base station 3720 and UE 3730 illustrated in Fig. 37 may be identical to the host computer 3630, one of the base stations 3612a, 3612b, 3612c and one of the UEs 3691, 3692 of Fig. 36, respectively.
  • the inner workings of these entities may be as shown in Fig. 37, and, independently, the surrounding network topology may be that of Fig. 36.
  • the OTT connection 3750 has been drawn abstractly to illustrate the communication between the host computer 3710 and the UE 3730 via the base station 3720, without explicit reference to any intermediary devices and the precise routing of messages via these devices.
  • Network infrastructure may determine the routing, which it may be configured to hide from the UE 3730 or from the service provider operating the host computer 3710, or both. While the OTT connection 3750 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).
  • the wireless connection 3770 between the UE 3730 and the base station 3720 is in accordance with the teachings of the embodiments described throughout this disclosure.
  • One or more of the various embodiments improve the performance of OTT services provided to the UE 3730 using the OTT connection 3750, in which the wireless connection 3770 forms the last segment. More precisely, the teachings of these embodiments may reduce the latency and improve the data rate and thereby provide benefits such as better responsiveness and improved QoS.
  • a measurement procedure may be provided for the purpose of monitoring data rate, latency, QoS and other factors on which the one or more embodiments improve.
  • the measurement procedure and/or the network functionality for reconfiguring the OTT connection 3750 may be implemented in the software 3711 of the host computer 3710 or in the software 3731 of the UE 3730, or both.
  • sensors may be deployed in or in association with communication devices through which the OTT connection 3750 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 3711, 3731 may compute or estimate the monitored quantities.
  • the reconfiguring of the OTT connection 3750 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 3720, and it may be unknown or imperceptible to the base station 3720. Such procedures and functionalities may be known and practiced in the art.
  • measurements may involve proprietary UE signaling facilitating the host computer's 3710 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 3711, 3731 causes messages to be transmitted, in particular empty or "dummy" messages, using the OTT connection 3750 while it monitors propagation times, errors etc.
  • Fig. 38 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figs. 36 and 37. For simplicity of the present disclosure, only drawing references to Fig. 38 will be included in this paragraph.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE.
  • the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE executes a client application associated with the host application executed by the host computer.
  • Fig. 39 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment.
  • the communication system includes a host computer, a base station and a UE which may be those described with reference to Figs. 36 and 37. For simplicity of the present disclosure, only drawing references to Fig. 39 will be included in this paragraph.
  • the host computer provides user data.
  • the host computer provides the user data by executing a host application.
  • the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure.
  • the UE receives the user data carried in the transmission.
  • the failure handling (FH) technique can improve a user experience (e.g., at the first radio device).
  • Same or further embodiments of the FH technique can assist the communications network (e.g., the base station, e.g., a gNB) or the first radio device (e.g., a UE) to balance traffic load between different SLs and/or different MAC (i.e., L2) destinations and/or different resource pools and/or BWP segments and/or BWPs and/or cells and/or carriers and/or frequency bands.
  • the FH technique can at least one of reduce the latency (or interruption) for service providing.
  • Same or further embodiments of the technique can improve QoS satisfaction of services.
  • the relay (RL) technique can, e.g. in case of SL relay, inform by means of the control information as to the status 512- FH (e.g., a congestion or failure event) a shared spectrum link, e.g., in an unlicensed resource pool, BWP, link, cell, or carrier.
  • the information i.e., the control message
  • the information may be, e.g., upon determining the status 512-FH, timely transmitted (e.g., distributed) to other nodes on the source and/or target path (e.g., UEs and/or gNBs).
  • Same or further embodiment can improve QoS satisfaction for UE by avoiding accessing congested resource pools, BWPs, links cells, or carriers which are deployed on unlicensed band.

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Abstract

L'invention concerne une technique de manipulation et de prévention d'une défaillance d'écoute avant de parler (LBT) cohérente (512-FH) d'une liaison latérale (SL) (510-FH), une communication entre un premier dispositif radio (100-FH) et au moins un deuxième dispositif radio (110-FH). Selon un aspect de procédé réalisé par le premier dispositif radio (100-FH), la défaillance LBT cohérente (512-FH) de la SL (510-FH) est déterminée. Au moins un message de commande est transmis en réponse à la défaillance LBT cohérente (512-FH) déterminée.
PCT/EP2022/075111 2021-09-10 2022-09-09 Technique de manipulation et de prévention de défaillances de liaison latérale WO2023036933A1 (fr)

Applications Claiming Priority (8)

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US202163242549P 2021-09-10 2021-09-10
US63/242,549 2021-09-10
EPPCT/EP2021/074923 2021-09-10
EP2021074923 2021-09-10
CNPCT/CN2021/122403 2021-09-30
CN2021122403 2021-09-30
US202163256509P 2021-10-15 2021-10-15
US63/256,509 2021-10-15

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