WO2023175105A1 - Technique de gestion d'une communication de liaison latérale - Google Patents

Technique de gestion d'une communication de liaison latérale Download PDF

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Publication number
WO2023175105A1
WO2023175105A1 PCT/EP2023/056807 EP2023056807W WO2023175105A1 WO 2023175105 A1 WO2023175105 A1 WO 2023175105A1 EP 2023056807 W EP2023056807 W EP 2023056807W WO 2023175105 A1 WO2023175105 A1 WO 2023175105A1
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WIPO (PCT)
Prior art keywords
wireless device
transmitting
resource
counter
communication
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PCT/EP2023/056807
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English (en)
Inventor
Jose Angel LEON CALVO
Hieu DO
Gustav Almquist
Nithin SRINIVASAN
Shehzad Ali ASHRAF
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Telefonaktiebolaget Lm Ericsson (Publ)
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Publication of WO2023175105A1 publication Critical patent/WO2023175105A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/14—Direct-mode setup
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1887—Scheduling and prioritising arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/18—Management of setup rejection or failure

Definitions

  • the present disclosure relates to a technique for sidelink communication. More specifically, and without limitation, methods and devices are provided for transmitting data on a sidelink between wireless devices.
  • a sidelink is a wireless interface or link used for direct wireless communication between wireless devices, also referred to as device-to-device (D2D) communications. This is in contrast to typical cellular communications in which two wireless devices communicate by means of uplink (UL) and downlink (DL) transmissions through a radio access network (RAN).
  • the sidelink interface is sometimes referred to as PC5 interface.
  • the interface for UL and DL is sometimes referred to as Uu interface.
  • the Third Generation Partnership Project (3GPP) defined SLs in Release 12 as an adaptation of the Long Term Evolution (LTE) radio access technology for direct communication between two wireless devices, also referred to as user equipment (U E), without going through a base station.
  • LTE Long Term Evolution
  • D2D device-to-device
  • ProSe proximity service
  • the SL can be used for Public Safety communications. While conventional public safety communications use different standards in different geographical regions and countries, 3GPP SL communications enable interworking of different public safety groups.
  • 3GPP has enriched SLs in Release 13 for public safety and commercial communication usecases and, in Release 14, for vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) scenarios and day-1 safety. Support was enhanced during Release 15. From the point of view of the lowest radio layers, the LTE SL uses broadcast communication. That is, transmission from a UE targets any receiver that is in range.
  • V2V vehicle-to-vehicle
  • V2X vehicle-to-everything
  • the NR SL is capable of broadcast, groupcast, and unicast communications.
  • groupcast communication the intended receivers of a message are typically a subset of the vehicles near the transmitter, whereas in unicast communication, there is a single intended receiver.
  • unicast communication there is a single intended receiver.
  • a platooning service there are certain messages that are only of interest to the members of the platoon, making the members of the platoon a natural groupcast.
  • NR sidelink not only supports broadcast as in LTE sidelink, but also groupcast and unicast transmissions.
  • 3GPP is working on improving the performance of power-limited UEs (e.g., pedestrian UEs, first responder UEs, etc.) and resource coordination.
  • Both the LTE SL and the NR SL can operate with and without network coverage and with varying degrees of interaction between the UEs and the RAN, including support for standalone or network-less operation of the SL.
  • a transmitting UE declares a radio link failure (RLF) based the number of consecutively missing hybrid automatic repeat request (HARQ) feedbacks exceeding a certain threshold.
  • RLF radio link failure
  • HARQ hybrid automatic repeat request
  • missing HARQ acknowledgement feedbacks force the transmitting UE to retransmit the data packet even though the packet has already been successfully received leading to spectral inefficiency and an excessive number of retransmissions.
  • a method performed by a transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device comprises transmitting data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the method further comprises sensing if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the first method aspect may be performed by the transmitting wireless device, e.g., a data-transmitting wireless device and/or a feedback-receiving wireless device.
  • data may comprise user data or control data (e.g., signaling).
  • a method performed by a transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device comprises sensing if a channel of the SL communication is available.
  • the method further comprises transmitting data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the method further comprises monitoring a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • Retransmitting the data or triggering a radio link failure (RLF) may depend on a combination of an availability of the channel according to the sensing and an absence of the feedback message according to the monitoring.
  • RLF radio link failure
  • the second method aspect may further comprise any feature and/or any step disclosed in the context of the first method aspect, or a feature and/or step corresponding thereto.
  • a computer program product comprises program code portions for performing any one of the steps of the first method aspect or the second 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 transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device.
  • the transmitting wireless device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the transmitting wireless device is operable to transmit data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the transmitting wireless device is further operable to sense if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the device may be configured to perform any one of the steps of the first method aspect.
  • the device comprises processing circuitry (e.g., at least one processor and a memory).
  • Said memory comprises instructions executable by said at least one processor whereby the device is operative to perform any one of the steps of the first method aspect.
  • a transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device.
  • the transmitting wireless device comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the transmitting wireless device is operable to sense if a channel of the SL communication is available.
  • the transmitting wireless device is further operable to transmit data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the transmitting wireless device is further operable to monitor a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the transmitting wireless device is further operable to retransmit the data or trigger a radio link failure (RLF) depending on a combination of an availability of the channel according to the sensing and an absence of the feedback message according to the monitoring.
  • RLF radio link failure
  • the device may be configured to perform any one of the steps of the second method aspect.
  • the device comprises processing circuitry (e.g., at least one processor and a memory).
  • Said memory comprises instructions executable by said at least one processor whereby the device is operative to perform any one of the steps of the second method aspect.
  • the transmitting wireless device may further comprise any of the features, or may be further operable to perform any one of the steps, of the first method aspect or the second method aspect.
  • a transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device.
  • the transmitting wireless device is configured to transmit data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the transmitting wireless device is further configured to sense if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • a transmitting wireless device for handling a sidelink (SL) communication with a receiving wireless device.
  • the transmitting wireless device is configured to sense if a channel of the SL communication is available.
  • the transmitting wireless device is further configured to transmit data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the transmitting wireless device is further configured to monitor a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the transmitting wireless device may be further configured to retransmit the data or trigger a radio link failure (RLF) depending on a combination of an availability of the channel according to the sensing and an absence of the feedback message according to the monitoring.
  • RLF radio link failure
  • the transmitting wireless device may further comprise any one of the features, or may be further configured to perform any one of the steps, of the first method aspect or the second method aspect.
  • a transmitting user equipment (UE) for handling a sidelink (SL) communication with a receiving UE comprises a radio interface and processing circuitry configured to transmit data using a first resource of the SL communication from the transmitting UE to the receiving UE.
  • the transmitting UE is further configured to sense if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving UE at the transmitting UE in response to the transmitting of the data.
  • a transmitting user equipment (UE) for handling a sidelink (SL) communication with a receiving UE comprising a radio interface and processing circuitry configured to sense if a channel of the SL communication is available.
  • the transmitting UE is further configured to transmit data using a first resource of the SL communication from the transmitting UE to the receiving UE.
  • the transmitting UE is further configured to monitor a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving UE at the transmitting UE in response to the transmitting of the data.
  • the processing circuitry of the transmitting UE is further configured to retransmit the data or trigger a radio link failure (RLF) depending on a combination of an availability of the channel according to the sensing and an absence of the feedback message according to the monitoring.
  • RLF radio link failure
  • the transmitting UE may further comprise any one of the features, or the processing circuitry may be further configured to perform any one of the steps, of the first method aspect or the second method aspect.
  • a communication system includes a host computer comprising processing circuitry configured to provide user data and a communication interface configured to forward user data to a (e.g., cellular or ad hoc) radio network for transmission to a receiving user equipment (UE) or configured to request user data from the cellular or ad hoc radio network for reception from a transmitting UE.
  • a host computer comprising processing circuitry configured to provide user data and a communication interface configured to forward user data to a (e.g., cellular or ad hoc) radio network for transmission to a receiving user equipment (UE) or configured to request user data from the cellular or ad hoc radio network for reception from a transmitting UE.
  • the transmitting or receiving UE may comprise a radio interface and processing circuitry, the processing circuitry of the transmitting or receiving UE may be configured to execute any one of the steps of the first method aspect and/or the second method aspect.
  • the communication system may further comprising the transmitting or receiving 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 transmitting UE.
  • the radio device (e.g., according to the system aspect) functioning as a gateway may comprise processing circuitry, which is configured to perform any one of the steps of the first method aspect or the second 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.
  • any one of the devices, the UE, 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 SL communication between a transmitting wireless device and a receiving wireless device according to a first aspect
  • Fig. 2 shows a schematic block diagram of an embodiment of a device for handling a SL communication between a transmitting wireless device and a receiving wireless device according to a second aspect
  • Fig. 3 shows a flowchart for a method of handling a SL communication, which method may be implementable by the device of Fig. 1;
  • Fig. 4 shows a flowchart for a method of handling a SL communication, which method may be implementable by the device of Fig. 2;
  • Fig. 5A schematically illustrates an example of a radio network comprising at least one embodiment of the device of Fig. 1 and/or 2 for performing the methods of Figs. 3 and/or 4, respectively;
  • Fig. 5B schematically illustrates an example of a SL communication involving at least one embodiment of the device of Fig. 1 and/or 2 for performing the methods of Figs. 3 and/or 4, respectively;
  • Fig. 6 schematically illustrates a first example of a time domain of a SL communication, which may result from an embodiment of the device of Fig. 1 and/or 2 performing the method of Fig. 3 and/or 4, respectively, in the SL communication with a receiving wireless device;
  • Fig. 7 schematically illustrates an example of a first slot in the SL communication, e.g., of Fig. 6, in more detail including Orthogonal Frequency-Division Multiplexing (OFDM) symbols, which may be used as the first resource by embodiments of the device of Fig. 1 and/or 2 performing the method of Fig. 3 and/or 4, respectively, in the SL communication;
  • OFDM Orthogonal Frequency-Division Multiplexing
  • Fig. 8 schematically illustrates an example of a second slot in the SL communication, e.g., of Fig. 6, in more detail including OFDM symbols, which may be used as the first resource and/or second resource by embodiments of the device of Fig. 1 and/or 2 performing the method of Fig. 3 and/or 4, respectively, in the SL communication;
  • Fig. 9 shows a schematic block diagram of a transmitting wireless device embodying the device of Fig. 1 and/or Fig. 2;
  • Fig. 10 schematically illustrates an example telecommunication network connected via an intermediate network to a host computer
  • Fig. 11 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. 12 and 13 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
  • Fig. 1 schematically illustrates a block diagram of an embodiment of a device for handling a sidelink (SL) communication between a transmitting wireless device and a receiving wireless device.
  • the device is generically referred to by reference sign 100.
  • the device 100 comprises a data transmission module 102 that transmits data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the device 100 further comprises a channel sense module 104 that senses if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting (302) of the data.
  • the device 100 comprises optionally a monitor module 105 that monitors the second resource associated to the first resource for receiving the feedback message on the second resource of the feedback channel of the SL from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data and/or attempting to receive the feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the device 100 comprises optionally a reception module 106 that receives the feedback message or attempts to receive the feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.
  • the device 100 may also be referred to as, or may be embodied by, the transmitting wireless device (or briefly: data transmitter or TX UE).
  • the transmitting wireless device 100 and the receiving wireless device may be in direct radio communication, e.g., at least for the data transmission and/or the feedback reception.
  • the receiving wireless device may be embodied by the device 200 described below.
  • Fig. 2 schematically illustrates a block diagram of an embodiment of a device for handling a sidelink (SL) communication between a transmitting wireless device and a receiving wireless device.
  • the device is generically referred to by reference sign 100.
  • the device 100 comprises a channel sense module 104 that senses if a channel of the SL communication is available.
  • the device 100 further comprises a data transmission module 102 that transmits data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the device 100 further comprises a monitor module 105 that monitors a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data. Retransmitting the data or triggering a radio link failure (RLF) depends on a combination of an availability of the channel according to the channel sense module 104 and an absence of the feedback message according to the monitor module 105.
  • RLF radio link failure
  • the device 100 comprises a reception module 106 that receives the feedback message or attempts to receive the feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • a reception module 106 that receives the feedback message or attempts to receive the feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.
  • the device 100 may also be referred to as, or may be embodied by, the transmitting wireless device (or briefly: data transmitter or TX UE).
  • the transmitting wireless device 100 and the receiving wireless device may be in direct radio communication, e.g., at least for the data transmission and/or the feedback reception.
  • the receiving wireless device may be embodied by the device 200 described below.
  • Fig. 3 shows an example flowchart for a method 300 according to the first method aspect.
  • the method 300 comprises the step 302 and 304 indicated in Fig. 3.
  • the method further comprises the step 305 and/or 306 indicated in Fig. 3 and/or any other step of the first method aspect.
  • the method 300 may be performed by the device 100.
  • the modules 102 and 104 may perform the steps 302 and 304, respectively.
  • Fig. 4 shows an example flowchart for a method 300 according to the second method aspect.
  • the method 300 comprises the step 302, 304, and 305 indicated in Fig. 4.
  • the method further comprises the step 306 indicated in Fig. 4 and/or any other step of the second method aspect.
  • the method 300 may be performed by the device 100.
  • the modules 102, 104, and 105 may perform the steps 302, 304, and 305, respectively.
  • the method 300 of the first method aspect is performed by a transmitting wireless device 100 for handling a sidelink (SL) communication with a receiving wireless device 200.
  • the method 300 comprises transmitting data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device.
  • the method 300 further comprises sensing if a feedback channel of the SL communication is available at a second resource associated to the first resource for receiving a feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the first method aspect 300 may be performed by the transmitting wireless device, e.g., a data-transmitting wireless device and/or a feedback-receiving wireless device.
  • data may comprise user data or control data (e.g., signaling).
  • the transmitting wireless device gains (e.g., at least approximate) knowledge of the availability of the channel from the perspective of the receiving wireless device.
  • the sensing step enables the transmitting wireless device to distinguish whether the absence of the feedback message is due to the feedback channel being not available at the second resource.
  • the sensing may determine if the feedback channel of the SL communication is available at the second resource by monitoring one or more resources of the SL communication prior to the second resource and/or after the first resource.
  • the feedback channel being available may mean or may also be referred to as, or may comprise, the feedback channel being clear, or unoccupied, or idle, or preoccupied by the SL communication, or shared for the SL communication.
  • the feedback channel being not available may mean or may also be referred to as, or may comprise, the feedback channel being occupied or busy.
  • any of the wireless devices 100 or 200 may be a user equipment (UE) for SL communication (SL UE), e.g. according to a 3GPP specification.
  • UE user equipment
  • SL UE SL communication
  • the feedback message may be a (e.g., positive) acknowledgment (ACK) or a negative acknowledgment (NACK) of receiving (e.g., successfully decoding) of the data at the receiving wireless device.
  • the feedback message may be a hybrid automatic repeat request (HARQ) feedback.
  • the data may be transmitted (or retransmitted) on a shared channel of the SL communication, e.g., a physical SL shared channel (PSSCH) of the SL communication.
  • the feedback channel may be a physical SL feedback channel (PSFCH) of the SL communication.
  • the data may comprise at least one of user data, a (e.g., common or dedicated) control message, a radio link control (RLC) message, and a non-access stratum (NAS) message.
  • the data may comprise data of Intelligent Transport Systems (ITS).
  • the data may comprise at least one of a Cooperative Awareness Messages (CAM), a Decentralized Environmental Notification Messages (DENM), and Basic Safety Message (BSM).
  • CAM Cooperative Awareness Messages
  • DENM Decentralized Environmental Notification Messages
  • BSM Basic Safety Message
  • the transmitting and receiving wireless devices may be any pair of vehicle, pedestrian, and (e.g., road) infrastructure.
  • the data may be received in one or more data packets (or briefly: packets).
  • the transmitting wireless device may be referred to as a TX wireless device or TX UE or transmitter.
  • the receiving wireless device may be referred to as a RX wireless device or RX UE receiver, e.g., according to a direction of transmitting the data.
  • Each of the transmitting and receiving wireless device may be a user equipment (UE) configured for operation of SLs, which may be referred to as SL UE.
  • UE user equipment
  • the first resource may be a resource (e.g., a radio resource) in time and/or frequency, e.g. on the shared channel of the SL communication.
  • the second resource may be a resource (e.g., a radio resource) in time and/or frequency, e.g. on the feedback channel of the SL communication.
  • the SL communication may comprise slots in the time domain. Within each slot, the SL communication may comprise a plurality of orthogonal frequency-division multiplexing (OFDM) symbols.
  • OFDM orthogonal frequency-division multiplexing
  • Each of the shared channel and/or the feedback channel may be allocated to certain slots in the time domain and/or subcarriers in the frequency domain, e.g., according to a configured grant or semi-persistent scheduling from a network node or based on autonomous resource selection (e.g. according to mode 2 in the SL communication according to 3GPP).
  • each of the shared channel and/or the feedback channel may be allocated to specific OFDM symbols within the allocated slot.
  • the first resource and the second resource associated to the first resource may be associated (i.e., related) in the time domain according to a temporal relation. At least one second resource on the feedback channel may be associated to one first resource on the shared channel.
  • the feedback message may be transmitted by the receiving wireless device multiple times using multiple second resources out of at least two resource candidates among occasions of the feedback channel. If the feedback message is absent, the sensing may be performed for each of the multiple second resources.
  • the transmitting of the data from the transmitting wireless device to the receiving wireless device may be a unicast transmission (e.g., addressed to the receiving wireless device) or a broadcast transmission (e.g., within range of reception of the receiving wireless device).
  • predefined may encompass stored in memory (e.g., in a Subscriber Identity Module, SIM) of the transmitting wireless device, or hard-coded or hardwired in the transmitting wireless device, or preconfigured or configured by a network node or radio access network (RAN) for the transmitting wireless device (e.g., preconfigured while in coverage prior to performing the method out of coverage, or configured while in coverage when performing the method).
  • SIM Subscriber Identity Module
  • RAN radio access network
  • the SL communication and/or the feedback channel may use radio spectrum shared by multiple radio access technologies (RATs).
  • RATs radio access technologies
  • the receiving wireless device may be required to sense if the feedback channel of the SL communication is available at the second resource associated to the first resource for transmitting the feedback message in the second resource from the receiving wireless device to the transmitting wireless device in response to the transmitting of the data.
  • the multiple RATs may comprise at least one RAT of the Third Generation Partnership Project (3GPP), optionally Long Term Evolution (LTE) and/or Fifth Generation (5G) New Radio (NR). More specifically, the multiple RATs may comprise LTE SL and/or NR SL.
  • the multiple RATs may further comprise Wi-Fi according to the Wi-Fi Alliance.
  • the feedback channel may be available if the SL communication is available. Alternatively or in addition, the feedback channel or the SL communication may be available (e.g., during a channel occupancy time, COT) when any wireless device configured for the SL communication has initiated the SL communication. For example, the wireless devices configured for the SL communication may share the COT.
  • the feedback channel may be not available if the feedback channel or any channel of the SL communication is not available.
  • the feedback channel or the SL communication may be not available (e.g., during the COT) when any wireless device not configured for the SL communication has initiated its communication.
  • wireless devices operating according to Wi-Fi may not share the COT with wireless devices configured for the SL communication.
  • the transmitting wireless device may have knowledge of, or may have an estimation of, a result of the sensing at the receiving wireless device without the need of additional signaling on the SL. Avoiding such additional signaling can improve resource efficiency. Alternatively or in addition, such additional signaling may be even impossible if the (e.g., feedback) channel of the SL communication is not available.
  • the radio spectrum shared by multiple RATs may be an unlicensed spectrum.
  • any of the wireless devices may be a SL UE for the unlicensed spectrum (SL-U UE), e.g. according to a 3GPP specification.
  • the method may further comprise monitoring the second resource associated to the first resource for receiving the feedback message on the second resource of the feedback channel of the SL from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the method may further comprise receiving the feedback message or attempting to receive the feedback message in the second resource from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data.
  • the first resource for the transmitting of the data (e.g., according to the first method aspect) may be on a data channel of the SL communication, optionally on a physical SL shared channel (PSSCH).
  • PSSCH physical SL shared channel
  • the feedback channel of the SL communication may be a physical SL feedback channel (PSFCH).
  • the first resource for the data transmission may be in a data channel of the SL communication, e.g. a physical SL shared channel (PSSCH).
  • PSSCH physical SL shared channel
  • Monitoring the second resource for receiving the feedback message and attempting to receive the feedback message may be synonymous.
  • the method may further comprise determining that an absence of the feedback message at the second resource is due to a channel condition of the SL communication if the feedback channel is available at the second resource according to the sensing.
  • the method may further comprise determining that an absence of the feedback message at the second resource is due to the feedback channel being not available at second resource according to the sensing.
  • the channel condition may cause that the feedback message is absent (i.e., not received, e.g., not decodable) at the transmitting wireless device.
  • the channel condition causing the absence of the feedback channel may comprise a path loss and/or interference, which is greater than a predefined threshold or beyond a capability of the involved wireless devices, and/or a signal to interference and noise ratio (SINR), which is less than a predefined threshold or beyond a capability of the involved wireless devices.
  • SINR signal to interference and noise ratio
  • the transmitting wireless device may have knowledge of, or may have an estimation of, the result of a sensing performed at the receiving wireless device when the receiving wireless device attempts to transmit the feedback message, so that the transmitting wireless device determines that the absence of the feedback message at the second resource is due to the feedback channel being not available at second resource also according to the sensing performed at the receiving wireless device.
  • the method may further comprise triggering a radio link failure (RLF) event depending on an absence of the feedback message at the second resource, or the feedback channel being available at the second resource according to the sensing, or a combination of an absence of the feedback message at the second resource and the feedback channel being available at the second resource according to the sensing.
  • RLF radio link failure
  • the RLF event may be triggered after the absence of the feedback message has been monitored (e.g., observed) multiple times (e.g., for multiple transmissions of data and/or retransmissions of data). For example, the RLF event may be triggered if a (e.g. conventional) counter for the absence of the feedback message is equal to or greater than a predefined threshold and the SL or the feedback channel is (e.g., currently) not available according to the sensing (e.g., without using a second or third counter that depends on a result of the sensing).
  • a (e.g. conventional) counter for the absence of the feedback message is equal to or greater than a predefined threshold and the SL or the feedback channel is (e.g., currently) not available according to the sensing (e.g., without using a second or third counter that depends on a result of the sensing).
  • the method may further comprise, responsive to an absence of the feedback message at the second resource, refraining from or suspending retransmitting the data from the transmitting wireless device to the receiving wireless device if the feedback channel is not available at the second resource according to the sensing.
  • the retransmitting of the data may be suspended until a next occasion of the feedback channel for receiving the feedback message.
  • a resource of the SL for the retransmitting of the data after the next occasion of the feedback channel for receiving the feedback message is selected.
  • Suspending the retransmitting may comprise postponing the retransmitting until after the next occasion of the feedback channel (e.g., the next instance of the second resource for receiving the feedback message on the feedback channel) if no feedback message is received in this next occasion. If the feedback channel is still not available at the next occasion, the retransmitting of the data may be further suspended, e.g., until a predefined maximum number of occasions. After the predefined maximum number of occasions, the data may be retransmitted or an RLF event may be triggered.
  • the retransmitting of the data may refer to the same HARQ-based transmission or the same HARQ. process underlying the transmitting of data.
  • Resources of the SL reserved for the retransmitting of the data prior to the next occasion of the feedback channel for receiving the feedback message may be dropped.
  • all resources of the SL reserved for the retransmitting of the data may be dropped, optionally including performing a resource reselection procedure for selecting other resources for the retransmitting of the data.
  • the transmitting wireless device may perform multiple times at least one of the transmitting of data and the associated sensing.
  • the method may further comprise at least one of maintaining a first counter for a first number of absent feedback messages among all feedback messages expected to be received at the transmitting wireless device from the receiving wireless device in response to the transmitting of data or the respective transmitting of data; maintaining a second counter for a second number of absent feedback messages among the first number of absent feedback messages for which the feedback channel is not available at the respective second resource according to the sensing; and maintaining a third counter for a third number of absent feedback messages among the first number of absent feedback messages for which the feedback channel is available at the respective second resource according to the sensing.
  • Transmitting data multiple times may comprise transmitting different data packets and/or retransmitting the same data packet (e.g., the same data unit or the same transport block, TB) or at least one data packet.
  • the same data packet e.g., the same data unit or the same transport block, TB
  • the associated sensing may comprise sensing if the feedback channel of the SL communication is available at the respective second resource associated to the respective first resource of the transmitting of data (i.e., the transmitting of data to which the sensing is "associated").
  • the first number may also be referred to as a total number of absent feedback messages among all the expected feedback messages.
  • the first number, the second number, and/or the third number may be counted (e.g., the first counter, the second counter, and/or the third counter may be incremented after initializing or resetting) for consecutively absent feedback messages and/or for a predefined duration (e.g., within any one of the below at least one predefined time interval).
  • initializing or resetting the first counter, the second counter, and/or the third counter may also be referred to as Step 0.
  • the second counter may be equal to or less than the first counter.
  • the unavailability e.g., as a result of the sensing
  • the absence of the feedback message e.g., as a result of the monitoring
  • maintaining (e.g., updating or incrementing) the first counter may also be referred to as Step 1.
  • maintaining (e.g., updating or incrementing) the second counter and/or maintaining the third counter and/or performing the sensing may also be referred to as Step 2.
  • a list of the form A, B, and/or C may correspond to at least one or each of A, B, and C, i.e., A and/or B and/or C.
  • Maintaining the first counter, the second counter, and/or the third counter may comprise updating the first counter, the second counter, and/or the third counter for every occasion of the feedback channel. Alternatively or in addition, it may comprise updating the first counter, the second counter, and/or the third counter every K-th occasion of the feedback channel, wherein K>1 is an integer.
  • the first resource (e.g., according to the first method aspect) may be associated to multiple second resources among occasions of the feedback channel.
  • the first counter, the second counter, and/or the third counter may be updated once after all the multiple second resources associated to the first resource have passed.
  • the second counter may be updated if, optionally only if, the feedback channel is not available for each of the multiple second resources.
  • the transmitting wireless device may perform the transmitting of data multiple times including an initial transmission and at least one retransmission of the data.
  • the first counter, the second counter, and/or the third counter may be updated once for each of the multiple transmissions.
  • the retransmission (i.e., the retransmitting) of the data may be performed responsive to a negative acknowledgment in the feedback message associated with the initial transmission or a previous retransmission of the data.
  • the method may further comprise triggering an RLF event depending on a comparison between the first counter and the second counter or depending on a comparison between the first counter and the third counter.
  • the comparison comprises an absolute difference or a relative difference between the first counter and the second counter or between the first counter and the third counter.
  • the method may further comprise triggering an RLF event if a triggering condition is fulfilled.
  • the triggering condition may be that the first counter is greater than the second counter, and a relative or absolute difference between the first counter and the second counter is greater than a predefined threshold N.
  • N may be a positive integer.
  • the triggering condition may be that the third counter may be greater than a predefined threshold N (optionally wherein I is a positive integer).
  • the triggering condition may be that the difference between the first counter and the second counter multiplied by a predefined factor p may be greater than a predefined threshold K (optionally wherein K is a positive integer and/or wherein p is a real number between zero and one).
  • the triggering condition may be that the third counter multiplied by a predefined factor p may be greater than a predefined threshold K (optionally wherein K is a positive integer and/or wherein p is a real number between zero and one).
  • the triggering condition may be that the second counter multiplied by a predefined factor q may be greater than a predefined threshold S (optionally wherein S is a positive integer and/or wherein q is a real number between zero and one).
  • the triggering condition may be that the first counter may be greater than a predefined threshold X and/or the second counter may be greater than a predefined threshold Y (optionally wherein X and Y are positive integers).
  • the triggering condition may be that the first counter may be greater than a predefined threshold X and/or the third counter is greater than a predefined threshold Z (optionally wherein X and Z are positive integers).
  • the retransmitting and/or the triggering of the RLF may also be referred to as the Step 3.
  • the maintaining of the first counter may comprise resetting the first counter when the feedback message is received at the transmitting wireless device from the receiving wireless device in response to the respective transmitting of data; and/or incrementing the first counter when the feedback message expected to be received at the transmitting wireless device from the receiving wireless device in response the respective transmitting of data is absent.
  • the maintaining of the second counter may comprise resetting the second counter when the feedback message is received at the transmitting wireless device from the receiving wireless device in response to the respective transmitting of data; and/or incrementing the second counter when the feedback messages is absent and the feedback channel is not available at the second resource according to the sensing.
  • a third counter may be implemented (alternatively or in addition to the second counter).
  • the third counter may be incremented when the feedback messages is absent and the feedback channel is available at the second resource according to the sensing.
  • the second counter (or the second number) may be replaced by the difference between the first counter (or the first number) and the third counter (or the third number).
  • the maintaining of the third counter may comprise resetting the third counter when the feedback message is received at the transmitting wireless device from the receiving wireless device in response to the respective transmitting of data; and/or incrementing the third counter when the feedback messages is absent and the feedback channel is available at the second resource according to the sensing.
  • the incrementing of the first counter and/or the incrementing of the second counter and/or the incrementing of the third counter may include increasing the first counter and/or the second counter and/or the third counter by 1 or a value depending on at least one transmission parameter of the data or the transmitting of the data.
  • the at least one transmission parameter comprises at least one of a priority; a quality of service (QoS); a limit on latency or jitter; and a packet delay budget.
  • the value may depend on one or a combination of the at least one transmission parameter.
  • the at least one transmission parameter may comprise any one or a combination of: a priority of the data or a service underlying the data; the SL communication between the transmitting wireless device and the receiving wireless device or the pair of the transmitting and receiving wireless devices; the first resource or the time when the data becomes available at the transmitting wireless device; the transmitting wireless device from which the data is transmitted; the receiving wireless device at which the data is received; a remaining time of a packet delay budget (PDB) of the data or a service underlying the data; and a number of remaining resource candidates that are associated with the first resource.
  • PDB packet delay budget
  • the method may further comprise receiving a control message from the receiving wireless device.
  • the control message being indicative of an absence of the feedback message may be due to the feedback channel being not available at the receiving wireless device.
  • the maintaining of the second counter comprises incrementing the second counter responsive to the control message and/or wherein the maintaining of the third counter comprises refraining from incrementing the third counter responsive to the control message.
  • the control message may be a later feedback message or a message on the shared channel of the SL communication.
  • the sensing e.g., according to the first method aspect
  • the sensing may be based on detecting sidelink control information (SCI) from the receiving wireless device and/or another wireless device and/or based on detecting downlink control information (DCI) from a network node to determine if the feedback channel is available at the second resource.
  • the feedback channel may be available according to the sensing if the SCI or the DCI is detected in a slot comprising the second resource and/or wherein the feedback channel is not available according to the sensing if the SCI or the DCI is not detected in a slot comprising the second resource.
  • the network node may serve at least one of the transmitting wireless device, the receiving wireless device, and the other wireless device.
  • the other wireless device may be a (or any) wireless device configured for the SL communication and/or participating in the SL communication, optionally in the shared radio spectrum.
  • the second resource may be occupied by SL the communication and/or shared by the other wireless device.
  • the feedback channel e.g., one or more PSFCH symbols configured at the end of the second resource, e.g., at the end of the respective slot
  • the SCI may be or may comprise a reservation message or booking message, e.g. for the second resource.
  • the result of the sensing may be indicative of the feedback channel being available or not available at the second resource according to an indication in the booking message for the second resource and/or for the feedback channel.
  • the transmitting wireless device and the receiving wireless device may perform the sensing independently.
  • the transmitting wireless device may perform the sensing based on decoding SCI from the receiving wireless device (e.g., as a peer wireless device) or another wireless device to determine if the feedback channel (i.e., resources of the feedback channel) in the second resource (e.g., PSFCH resources) is (or are) available.
  • the sensing based on decoding may comprise at least one of the following substeps.
  • the feedback channel e.g., PSFCH symbols
  • the second resource e.g., the respective PSFCH slot
  • the transmitting wireless device e.g., the RX UE
  • the transmitting wireless device detects an SCI in the respective second resource (e.g., the respective slot)
  • the transmitting wireless device deduces that the first resource (e.g., the respective slot) is occupied by the receiving wireless device (e.g., a peer SL UE) or the other wireless device.
  • the feedback channel at the respective second resource e.g., the PSFCH symbols in the respective slot
  • the end of the respective second resource e.g., the respective slot
  • a channel occupancy time may be shared between the receiving and transmitting wireless devices or between the other wireless device and the transmitting wireless device, e.g., as indicated above.
  • the receiving wireless device or the other wireless device may (e.g., implicit or explicitly) share the COT (e.g., initiated by transmitting data in a further resource, optionally between the first resource and the second resource) with other wireless devices (e.g., the transmitting and/or receiving wireless devices) that want to transmit the feedback message on the feedback channels (e.g., PSFCHs) as the receiving radio device and/or that are expecting the feedback message on the feedback channels (e.g., PSFCHs).
  • the feedback channels e.g., PSFCHs
  • the sensing may comprise performing a clear channel assessment (CCA) of the feedback channel for the second resource.
  • CCA clear channel assessment
  • the CCA may be based on detecting energy in the second resource or in the feedback channel of the SL communication prior to the second resource.
  • the CCA may be part of a listen-before-talk (LBT) procedure.
  • the LBT procedure may comprise a random backoff mechanism.
  • the receiving wireless device may comprise a backoff timer that is initiated by a random time duration (e.g., within a contention window, which may have a fixed or variable size).
  • the backoff timer may be reduced if or while the respective second resource is unoccupied (e.g., after a successful CCA).
  • the feedback message may be transmitted from the receiving wireless device to the transmitting wireless device if the backoff timer expires prior to or at the time of the feedback channel in the respective second resource.
  • the sensing (e.g., according to the first method aspect) may be performed prior to a slot comprising the second resource associated to the first resource.
  • the sensing may be performed within a slot comprising the second radio resource associated to the first resource, optionally prior to at least one orthogonal frequency-division multiplexing (OFDM) symbol comprising the second resource associated to the first radio resource.
  • OFDM orthogonal frequency-division multiplexing
  • At least one of the steps (e.g., according to the first method aspect) of transmitting the data, sensing if the feedback channel is available, maintaining the first counter, maintaining the second counter, maintaining the third counter, performing the retransmitting of the data, and triggering the RLF for the SL communication may be performed in at least one predefined time interval, optionally while at least one timer corresponding to the at least one predefined time interval is running.
  • the wireless device may further perform sensing a channel of the SL communication prior to and/or as a basis of the transmitting of the data.
  • the at least one predefined time interval may comprise a transmission time interval that is initiated upon sensing that a channel for the transmitting of the data or any unicast transmission in the SL communication is available.
  • the transmission time interval comprises multiple occasions of the feedback channel of the SL communication on which the feedback message associated to the transmitting of the data is expected.
  • the transmission time interval may be measured using a transmission timer initiated at the transmitting wireless device upon sensing that a channel for the transmitting of the data or any other transmission in the SL communication (e.g., in a unicast manner) is available.
  • the transmission time interval or the transmission timer may also be referred to as THARQ.
  • THARQ (e.g., in ms) may be the timing between data transmission (i.e., the step of transmitting the data) in the SL communication and acknowledgement (i.e., the step of receiving the feedback or attempting to receive the feedback, or monitoring the second resource for receiving the feedback), e.g. as specified in the 3GPP document TS 38.213, version 17.0.0
  • the at least one predefined time interval may comprise a failure time interval that is initiated when the feedback channel is not available according to the sensing and/or when the feedback message is absent in the second resource, and/or wherein the failure time interval ends or is reset when a further sensing for the SL communication indicates that the feedback channel is available and/or when the feedback message is received.
  • the failure time interval may expire after a predefined duration.
  • the RLF (e.g., according to the first method aspect) may be triggered if the failure time interval expires and/or based on at least one of the first counter, the second counter and the third counter, and/or if the feedback channel is not available according to the sensing at a point in time when the remaining time before the failure time interval expires is less than that a channel occupancy time (COT) for the shared radio spectrum.
  • COT channel occupancy time
  • the failure time interval may also be referred to as TRLF.
  • TRLF failure time interval
  • the transmitting wireless device may trigger the RLF in combination with the first counter, the second counter, and expiry of TRLF, e.g., according to any criterion based on the first and second counters and when the TRLF expires.
  • triggering the RLF may also be referred to as declaring the RLF.
  • the method may further comprise transmitting a report to a network node, the report being indicative of at least one of the first counter; the second counter; the third counter; and the refraining from retransmitting the data or the suspending of retransmitting the data; and the triggering of the RLF event, optionally wherein the report is stored until the transmitting wireless device is in coverage of the network node.
  • the triggering of the RLF i.e., the RLF declaration
  • the method may further comprise receiving a control message from the network or network node.
  • the control message may be indicative of scheduled resources for the SL communication (e.g., according to 3GPP SL mode 1) and/or an allocation of resources for the SL communication (e.g., according to 3GPP SL mode 2).
  • a method 300 performed by a transmitting wireless device 100 for handling a sidelink (SL) communication with a receiving wireless device 200 comprises sensing if a channel of the SL communication is available. The method further comprises transmitting data using a first resource of the SL communication from the transmitting wireless device to the receiving wireless device. The method further comprises monitoring a second resource associated to the first resource for receiving a feedback message on the second resource of a feedback channel of the SL communication from the receiving wireless device at the transmitting wireless device in response to the transmitting of the data. Retransmitting the data or triggering a radio link failure (RLF) may depend on a combination of an availability of the channel according to the sensing and an absence of the feedback message according to the monitoring.
  • RLF radio link failure
  • the sensing may be performed prior to and/or as a basis of the transmitting of the data. For example, the sensing may be performed prior to each transmitting of data. Alternatively or in addition, the sensing may be performed after the transmitting of the data, e.g. for accessing the channel for control signaling.
  • the sensed channel may comprise at least one of a data channel or shared channel of the SL communication, optionally a physical SL shared channel (PSSCH); a control channel of the SL communication, optionally a physical SL control channel (PSCCH); a SL synchronization signal block (S-SSB) or a synchronization and physical broadcast channel (PBCH) block, or a synchronization signal; and a feedback transmitted or to be transmitted by the transmitting wireless device in response to data previously received in the SL communication.
  • PSSCH physical SL shared channel
  • PSCCH physical SL control channel
  • S-SSB SL synchronization signal block
  • PBCH synchronization and physical broadcast channel
  • the data channel may be sensed prior to any transmission of the transmitting wireless device, e.g., prior to each transmitting of the data.
  • the transmitting wireless device may perform sensing on all types of channels of the SL communication and/or whenever the transmitting wireless device has something to transmit.
  • the transmitting wireless device may deduce the availability of the feedback channel of the SL communication.
  • the sensed channel (e.g., according to the second method aspect) may be the feedback channel of the SL communication.
  • the sensing may comprise sensing if the feedback channel is available at the second resource for receiving the feedback message.
  • the second method aspect may be performed by the transmitting wireless device, e.g., a data-transmitting wireless device and/or a feedback-receiving wireless device.
  • data may comprise user data or control data (e.g., signaling).
  • the second method aspect may further comprise any feature and/or any step disclosed in the context of the first method aspect, or a feature and/or step corresponding thereto.
  • the transmitting wireless device can trigger the RLF (i.e., trigger a RLF event or declare the RLF) and/or perform retransmission more accurately, e.g., avoiding a RLF or a retransmission that is caused by a busy (i.e., not available) channel for the SL communication.
  • the RLF i.e., trigger a RLF event or declare the RLF
  • the transmitting wireless device may perform the transmitting of data multiple times including an initial transmission and at least one retransmission of the data (e.g., according to claim 10).
  • the first counter, the second counter, and/or the third counter may be updated once for each of the multiple transmissions.
  • a RLF may be triggered if the difference between the first counter and the second counter multiplied by a predefined factor p is greater than a predefined threshold K and/or if the third counter multiplied by a predefined factor p is greater than a predefined threshold K.
  • the threshold K may be a positive integer and/or wherein p may be a real number between zero and one.
  • the feedback channel on the SL may be a physical SL feedback channel (PSFCH).
  • the data channel may be a physical SL shared channel (PSSCH).
  • the second resource may be comprised in a slot, optionally a slot of the PSFCH or PSFCH occasion.
  • the feedback channel may comprise in the respective second resource (and/or in each of the at least two resource candidates) one or two or few OFDM symbols, optionally consecutive OFDM symbols at the end of the respective slot.
  • a communication system may include a host computer comprising processing circuitry configured to provide user data and a communication interface configured to forward user data to a (e.g., cellular or ad hoc) radio network for transmission to a receiving user equipment (UE) or configured to request user data from the cellular or ad hoc radio network for reception from a transmitting UE.
  • the transmitting or receiving UE may comprise a radio interface and processing circuitry, the processing circuitry of the transmitting or receiving UE may be configured to execute any one of the steps of the first method aspect and/or the second method aspect.
  • the communication system may further comprising the transmitting or receiving 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 transmitting UE.
  • the radio device functioning as a gateway may comprise processing circuitry, which is configured to perform any one of the steps of the first method aspect or the second 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 comprise, or may be implemented by, a RLF procedure for sidelink in unlicensed spectrum.
  • the technique may be embodied for New Radio (NR) SL or any device-to-device (D2D) communication, which is generically referred to as SL communication.
  • NR New Radio
  • D2D device-to-device
  • the SL communication may require a resource allocation and/or partial sensing mechanism.
  • Embodiments of the technique can reduce power consumption, e.g., at the transmitting wireless device.
  • the feedback message may be a hybrid automatic repeat request (HARQ) feedback (HARQ FB).
  • HARQ hybrid automatic repeat request
  • the technique may be implemented in accordance with a 3GPP specification, e.g., for 3GPP release 17 or a future release 18. Alternatively or in addition, the technique may be implemented for any radio access technology (RAT) supporting SL, e.g. according to 3GPP LTE or 3GPP NR.
  • RAT radio access technology
  • Any wireless device may be a user equipment (UE), e.g., according to a 3GPP specification.
  • the receiving wireless device may also be referred to as a receiving UE (or briefly: RX UE or receiver) or UE wherein the context allows for the role of the RX UE.
  • the transmitting wireless device may also be referred to as a transmitting UE (or briefly TX UE or transmitter) or UE wherein the context allows for the role of the TX UE.
  • at least one wireless device may embody the functionality of both the transmitting wireless device and the receiving wireless device.
  • the transmitting and/or receiving wireless devices may be wirelessly connected or connectable to a radio access network (RAN) and/or a network node (e.g., of the RAN) in an uplink (UL) and/or a downlink (DL) through a Uu interface.
  • the SL communication may comprise a direct wireless (e.g., radio) communication between proximal wireless devices, e.g., the transmitting and receiving wireless devices, optionally using a PC5 interface.
  • the SL communication between the transmitting and receiving wireless devices may include one or more intermediate wireless device (also referred to as hops or relays). Services provided using the SL or the PC5 interface may be referred to as proximity services (ProSe). Any wireless device supporting a SL may be referred to as ProSe-enabled radio device.
  • the transmitting wireless device and/or the receiving wireless device and/or the RAN 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).
  • 3GPP Third Generation Partnership Project
  • Wi-Fi standard family IEEE 802.11
  • the first method aspect and/or the second method aspect may be performed by one or more embodiments of the transmitting wireless device.
  • the RAN may comprise one or more base stations (e.g., network nodes), e.g., controlling or (e.g., pre-) configuring the first and/or second method aspects.
  • the radio network may be a vehicular, ad hoc and/or mesh network comprising two or more wireless device devices, e.g., acting as the transmitting wireless device and/or the receiving wireless 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 machinetype communication (MTC), a device for narrowband Internet of Things (NB-loT) or a combination thereof.
  • MTC machinetype 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 base stations (e.g., network nodes).
  • base stations e.g., network nodes
  • the base station or network node may encompass any station that is configured to provide wireless (e.g., radio) access to any of the wireless 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 a relay radio device may provide a data link to a host computer providing the user data to the remote radio device or gathering user data from the remote radio device.
  • Examples for the network node 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., Wi-Fi AP
  • 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.
  • Fig. 5A schematically illustrates an example of a radio network 500 comprising at least one embodiment of the wireless device 100 for performing the method 300 according to the first and/or second aspect.
  • the radio network 500 further comprises an embodiment of the receiving wireless device 200 that is in the SL communication 520 with the transmitting wireless device 100.
  • At least one of the transmitting wireless device 100 and the receiving wireless device 200 is in coverage of a (e.g. terrestrial) radio access network comprising one or more network nodes 510, each providing radio access in one or more cells 511.
  • a radio access network comprising one or more network nodes 510, each providing radio access in one or more cells 511.
  • Fig. 5A schematically illustrates the case of the TX UE 100 being served by a network node 510, i.e., the TX UE 100 is in the coverage of a cell 511 of the network node 510.
  • the roles of the TX UE 100 and the RX UE 200 relative to the network node 510 may be interchanged.
  • UEs e.g., the TX UE 100 and/or the RX UE 200
  • UEs that are out of network coverage but participate in the SL communication may be provided the corresponding parameters by means of a pre-configuration (e.g., stored in the subscriber identity module, SIM).
  • SIM subscriber identity module
  • configuration pre-configuration, or configuration may denote both ways of providing the corresponding configuration/parameters to a UE.
  • the TX UE declares a RLF based on three conditions. One of them relates to the number of consecutive DTX for HARQ feedback (i.e., the number of consecutive missing HARQ feedbacks) exceeding a certain threshold.
  • a missing (i.e., absent) feedback message e.g., a HARQ FB
  • the absence of the feedback message (e.g., a missing HARQ FB) at the TX UE 100 also happens if the RX UE 200 fails to access the channel (e.g., feedback channel) for transmitting the feedback message (e.g., the HARQ FB), which may be referred to as LBT failure, e.g. due to an on-going Wi-Fi and/or NR- U SL transmission on the same channel.
  • LBT failure e.g. due to an on-going Wi-Fi and/or NR- U SL transmission on the same channel.
  • legacy NR SL RLF procedures do not apply straightforwardly in an unlicensed spectrum since it does not take this issue into account.
  • Another problem with legacy NR SL RLF procedures caused by the LBT failure for PSFCH is that, if the PSFCH is about to convey an acknowledgment (ACK) in the feedback message, the failure to access the feedback channel in the second resource may force the TX UE 100 to retransmit the data (e.g., a data packet) even though the data has already been successfully received leading to an excessive number of retransmissions.
  • ACK acknowledgment
  • Embodiments of the device 100 and the method 300 can deal with absent feedback message (e.g., the missing HARQ FB) due to busy channel (e.g., the channel being not available), e.g., in shared radio spectrum and/or the SL communication in unlicensed spectrum (SL-U), e.g. for RLF triggering and (re-)transmission procedures.
  • a preferred embodiment uses a channel sensing mechanism in the step 304 (briefly: sensing, e.g., performed in the unlicensed spectrum).
  • the sensing may comprise (e.g., may be based on) performing a clear channel assessment (CCA) based on energy detection (e.g., a listen-before-talk (LBT) procedure).
  • CCA clear channel assessment
  • LBT listen-before-talk
  • the sensing 304 may comprise (e.g., may be based on) decoding sidelink control information (SCI) at the TX UE 100.
  • SCI sidelink control information
  • the TX UE 100 may at least one of:
  • a retransmission strategy e.g., perform a retransmission or refrain from transmitting the data
  • the channel e.g., the feedback channel
  • not availability e.g., to account for an LBT failure at the RX UE 200.
  • Embodiments of the technique enable the TX UE 100 to differentiate whether the absence of an expected feedback message (e.g., HARQ FB) is due to bad channel conditions or due to a busy channel.
  • an expected feedback message e.g., HARQ FB
  • a preferred embodiment comprises a channel sensing mechanism that the TX UE 100 uses to deduce according to the step 304 that a missing HARQ FB from the RX UE 200 is due to a busy channel thereby preventing the RX UE 200 to send the feedback message (FB), rather than due to poor channel conditions (e.g., large pathloss or strong interference).
  • This information may assist the TX UE 100 to determine when and/or how to trigger a RLF event and/or perform a retransmission.
  • CCA clear channel assessment
  • the method 300 enables the TX UE 100 to identify whether the absence of an expected HARQ FB is due to poor channel conditions (e.g., due to large pathloss or strong interference) or due the RX UE 200 failing to access the channel (i.e., channel busy) to transmit the HARQ FB.
  • poor channel conditions e.g., due to large pathloss or strong interference
  • RX UE 200 failing to access the channel (i.e., channel busy) to transmit the HARQ FB.
  • the corresponding UE behaviors upon identifying a missing HARQ FB due to channel access failure may include any of the behaviors (e.g., postponing RLF or postponing retransmission) described herein.
  • This method 300 may be divided into different steps to be performed by the TX UE 100 and the RX UE 200, which are involved in a SL communication (e.g., a SL unicast transmission) or other transmission whenever HARQ FB is enabled.
  • a SL communication e.g., a SL unicast transmission
  • Fig. 5B schematically illustrates a unicast scenario for SL HARQ-based transmission 302 of data 502 from the TX UE 100 to the RX UE 200 in the SL communication 520 in a first resource.
  • the feedback message 504 (e.g., a SL HARQ feedback) is transmitted from the RX UE 200, and thus, received or absent at the TX UE 100.
  • the TX UE 100 maintains two counters.
  • a first counter Cl is configured to count the total number (i.e., the "first number") of missing (i.e., absent) PSFCHs (e.g., among the PSFCHs which the TX UE 100 expected to receive).
  • a second counter C2 is configured to count the number (i.e., the "second number") of missing PSFCHs which the TX UE 100 assumes are due to a failed channel access at the RX UE 200 (e.g., due to busy channel as defined by the CCA mechanism).
  • the TX UE 100 may declare an RLF procedure (i.e., trigger an RLF event).
  • each of the transmitting wireless device 100 and receiving wireless device 200 may use light (e.g., infra-red light) for the SL communication 520 or may be a radio device.
  • 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.
  • Any aspect and embodiment may implement the SL using SL resource pool, e.g., according to a resource pool configuration.
  • Radio resources for SL communication are organized into a SL resource pool.
  • An NR SL resource pool may comprise radio resources spanning both time and frequency domain.
  • the SL resource pool comprises NR slots indexed in an ascending order, starting from index 0 up to a maximum index value. Once this maximum index is reached, the slot indexing is started again from index 0, and so on.
  • Any aspect and embodiment may implement the feedback message or the feedback channel according to Hybrid Automatic Repeat reQuest (HARQ) feedback, e.g., in NR SL.
  • HARQ Hybrid Automatic Repeat reQuest
  • the Hybrid Automatic Repeat reQuest can be used to improve the reliability of communication.
  • the receiver UE (RX UE) of a data packet sends back to the transmitter UE (TX UE) a positive acknowledgement (ACK) if the RX UE 200 has decoded the packet correctly. Otherwise, the RX UE 200 transmits a negative acknowledgement (NACK), which acts as a request for the TX UE to retransmit the packet.
  • NACK negative acknowledgement
  • the TX UE will transmit a new packet in case of receiving an ACK and retransmit either the same version or a different version of the initial packet in case of receiving a NACK.
  • NR SL specifies a new physical channel, termed Physical Sidelink Feedback Channel (PSFCH), to convey the HARQ feedback (i.e., the ACK and/or the NACK) from the RX UE 200 to the TX UE 100.
  • the PSFCH in NR SL may comprise at least one of the following features: -
  • a SL resource pool has dedicated slots in which the PSFCH can be transmitted, often referred to as PSFCH occasions or PSFCH slots.
  • a PSFCH may comprise two identical OFDM symbols transmitted near the end of a PSFCH slot (i.e., the preceding OFDM symbols in the same slot can be used for data transmission). Examples of the first and second resources 602 and 604 of the feedback channel are illustrated in Figs. 6 to 8.
  • PSSCH Physical Sidelink Shared Channel
  • Each PSFCH transmission uses one physical resource block (PRB) and uses a certain code (namely, a certain cyclic shift to be applied on a base sequence).
  • PSFCH for different PSSCH are multiplexed in a PSFCH slot in both the PRB domain and the code domain.
  • the consecutive OFDM symbols of the feedback channel may be at the end of the respective slot and/or at the end of each of the at least two resource candidates up to an empty symbol or a guard period, e.g., for switching between downlink (DL) and uplink (UL) in time-division duplexing.
  • a guard period e.g., for switching between downlink (DL) and uplink (UL) in time-division duplexing.
  • An example of the guard period is illustrated in Fig. 8 below.
  • Fig. 7 schematically illustrates a slot 700 in the SL communication 520.
  • the slot 700 comprises no occasion of the feedback channel (e.g., no PSFCH occasion).
  • the first resource 602 may comprise at least one of the resources (e.g., OFDM symbols) for a shared channel of the SL communication 520 (e.g., a physical SL shared channel, PSSCH) and/or for a control channel of the SL communication 520 (e.g., a physical SL control channel, PSCCH).
  • resources e.g., OFDM symbols
  • PSSCH physical SL shared channel
  • PSCCH physical SL control channel
  • Fig. 8 schematically illustrates a slot 800 in the SL communication 520.
  • the slot 800 comprises an occasion of the feedback channel (e.g., a PSFCH occasion).
  • the second resource 604 may comprise at least one of the resources (e.g., one or more OFDM symbols) for the feedback channel (e.g., the physical SL feedback channel, PSFCH).
  • the feedback channel e.g., the physical SL feedback channel, PSFCH.
  • a slot 800 including an occasion of the feedback channel may also comprise the first resource 602, e.g., as indicated in Fig. 6 at "n+4".
  • the second resource 604 associated to such a first resource 604 may be typically not in the same slot due to the processing time T P .
  • the transmitting wireless device (TX UE) 100 may trigger a radio link failure (RLF) in the SL communication.
  • RLF radio link failure
  • an embodiment of the device 100 and the method 300 may improve the RLF behavior of the TX UE.
  • an RLF event is declared (i.e., triggered) at the TX UE (i.e., the UE replaced by the TX UE 100 transmitting the data, e.g. a data unit, in the step 302 and expecting the HARQ. FB for that data in the step 305) based on at least one of the following RLF criteria.
  • a first RLF criterion is fulfilled if the number of retransmissions at the Radio Link Control (RLC) layer has reached the maximum limit.
  • a second RLF criterion is fulfilled if the number of consecutive missing HARQ FB (also known as DTX) exceeds a certain threshold. Note that, since there are dedicated PSFCH occasions for transmitting HARQ FB and thanks to a deterministic timing relation between a PSSCH and the corresponding PSFCH, the TX UE 100 knows precisely when an expected PSFCH is missing.
  • a third RLF criterion is fulfilled if a timer T400 expires.
  • the timer T400 may be a timer started when the TX UE 100 transmits a control message (i.e., RRCReconfigurationSidelink) in the step 302 over the SL to the RX UE 200 to setup a corresponding unicast configuration.
  • a control message i.e., RRCReconfigurationSidelink
  • Embodiments of the technique may modify at least one of the criteria, e.g., by reducing the respective number by the second counter (i.e., by the second number of the second counter).
  • any aspect and embodiment may operate in radio spectrum shared by multiple radio access technologies (RATs) and/or unlicensed spectrum, e.g., according to a NR operation in unlicensed spectrum (NR-U), which is also referred to as SL-U for the SL communication.
  • RATs radio access technologies
  • NR-U unlicensed spectrum
  • the 5G NR supports performing uplink and downlink transmissions in unlicensed spectrum since Release 16.
  • the unlicensed spectrum can be used by any device as long as certain rules for using the channel is met, which are collectively referred to as sensing if the respective channel is available according to the step 204. These rules may be required by regulatory bodies in different parts of the world. In the following, we describe some technical components for operation in unlicensed spectrum, i.e., examples of the sensing 304.
  • Any aspect and embodiment may implement a channel access and/or channel occupancy time (COT) sharing.
  • COT channel occupancy time
  • the transmission medium i.e., the channel
  • multiple equipments e.g., any combination of wireless devices 100 and 200, network nodes 510, etc.
  • channel access procedures are defined, which may also be referred to as procedures for shared spectrum access.
  • the channel access procedure typically involves the following steps:
  • CCA clear channel assessment
  • the transmitter e.g., the transmitting wireless device 100 in the step 302 or the receiving wireless device 200 transmitting the feedback message
  • the transmitter does not transmit.
  • the transmitter makes use of the channel (e.g., transmits the information or signals, etc.), optionally subject to a random backoff time.
  • the channel is utilized for a certain time, which is referred to as the channel occupancy time (COT).
  • COT channel occupancy time
  • the maximum duration that a device is allowed to utilize the channel is known as the maximum COT i.e., MCOT.
  • different equipments may share a COT, e.g., for the data transmission in the step 302 and the feedback message in the step 306.
  • An equipment B e.g. the transmitting wireless device 100 performs CCA and gains access to the channel (i.e., a data channel is available, e.g. CCA is successful), and performs some transmission, e.g., according to the step 302.
  • the equipment B e.g. the transmitting wireless device 100 informs an equipment A (e.g. the receiving wireless device 200) that the COT is shared by equipment B (e.g. the transmitting wireless device 100).
  • the COT shared by equipment B gives equipment A (e.g. the receiving wireless device 200) access to the channel.
  • Equipment A e.g. the receiving wireless device 200
  • Equipment A performs some transmission, e.g., the feedback message in the step 306. This may end the COT or the COT may be shared back to the equipment B (e.g. the transmitting wireless device 100).
  • a transmitter 100 or 200 may be allowed to transmit (e.g., in the step 302 and/or 306) without performing CCA.
  • NR nodes e.g., UEs, base stations, etc. as examples of the above equipment
  • devices using other technologies e.g., Wi-Fi
  • the SL communication may be implemented in unlicensed spectrum (SL-U).
  • SL-U unlicensed spectrum
  • 3GPP may be expected to specify mechanisms that enable the operation of SL communications in unlicensed spectrum, sometimes referred to as SL-U. It is expected that SL-U design will take NR SL and NR-U designs as baseline.
  • any of the parameters discussed herein, e.g. for the temporal relation between the first and second resources and/or the transmission parameters controlling the increment of the first and/or second counters, may be controlled by means of configuration and/or pre-configuration.
  • the network typically configures some parameters used by the UEs.
  • This configuration is typically signaled by a NW node (e.g., a gNB) to the UE (e.g., using RRC signaling, broadcast signaling such as MIB or SIB, or some other type of signaling).
  • a NW node e.g., a gNB
  • RRC signaling e.g., RRC signaling
  • broadcast signaling such as MIB or SIB, or some other type of signaling.
  • TX UE 100 may denote a UE which transmits data (e.g., a data unit) according to the step 302 and expects (i.e., monitors in the step 305) a feedback message (e.g., a HARQ FB) for that data.
  • RX UE 200 denotes the UE which receives the data unit and transmits the HARQ FB.
  • the TX UE 100 may perform at least one of the following steps and/or sub-steps:
  • Step 0 Initialize a first counter, Cl, to zero and a second counter, C2, to zero.
  • Step 1 Maintain or update the first counter Cl by
  • Step 2 Maintain or update the second counter C2 by at least one of the following procedures:
  • Step 2-1 Perform a sensing procedure 304 (e.g., CCA or decoding of SCI, optionally as described below), which may comprise of one or more of the following Options-.
  • a sensing procedure 304 e.g., CCA or decoding of SCI, optionally as described below
  • Option 1 (e.g., the first method aspect): A clear channel assessment (CCA) operation triggered by the TX UE 100 based on energy detection indicates whether the channel is BUSY (i.e., not available) or IDLE (i.e., available) for an expected reception of PSFCH from the RX UE 200, i.e., at the second resource 604.
  • the energy detection is done without the intention of transmitting (i.e., only to assess and/or monitor the channel or channel conditions or channel availability) and is performed by the TX UE 100, e.g., in at least one of the following situations:
  • the HARQ FB for transmissions 302 of the TX UE 100 can be or is expected to be received in the step 306.
  • Option 2 (e.g., the first method aspect):
  • the TX UE 100 detects a SL control information (SCI) in a PSFCH slot (i.e., an occasion of the feedback channel) in which the TX UE 100 expects to receive a PSFCH (i.e., the feedback message) from the RX UE 200.
  • the feedback channel may be considered BUSY (i.e., not available) by the TX UE 100 during the said PSFCH slot (i.e., for the second resource 604 of the feedback channel).
  • the feedback may be considered available at the second resource 604.
  • a PSFCH slot can be any slot within a certain time after the transmission 302 of the data (e.g., a data unit).
  • Option 3 (e.g., the second method aspect): A clear channel assessment (CCA) operation triggered by the TX UE 100 (i.e., in preparation of a transmission from the TX UE 100) and/or performed by the TX UE 100 based on energy detection, which indicates whether a channel of the SL communication 520 is BUSY (i.e., not available) or IDLE (i.e., available) for a transmission from the TX UE 100.
  • CCA clear channel assessment
  • the transmission triggering (e.g., requiring) the CCA operation may comprise at least one or more of the following cases (each of which may be an example of the first resource 602).
  • a first case comprises a transmission on a control channel of the SL communication 520, e.g., a physical SL control channel (PSCCH) and/or on a shared channel of the SL communication 520, e.g., physical SL shared channel (PSSCH).
  • a second case comprises a transmission of a SL synchronization block (S-SSB) and/or a synchronization signal.
  • a third case comprises a transmission of hybrid automatic repeat request (HARQ) feedback to a previously received SL data unit (e.g., from the RX UE 200).
  • HARQ hybrid automatic repeat request
  • Step 2-2
  • the TX UE 100 increments the second counter C2 by 1.
  • the TX UE 100 may combine the sensing operations 304 performed according to Option 1 and/or Option 2 in Step 2-1 with detecting a HARQ 504 FB targeting the TX UE 100 in the said PSFCH slots 604.
  • the value of the second counter C2 is increased only if Option 1 and/or Option 2 determines that the channel is BUSY (i.e., not available) and no PSFCH is detected (i.e., the feedback message is absent) by the TX UE 100.
  • Step 3 the knowledge of the channel of the SL communication 520 (e.g., the feedback channel) being available or not may be used for the operation of the TX UE 100. For example, at least one of the following two mechanisms based on the sensing 304 (e.g., the procedures defined in Step 2) may be performed.
  • the first mechanism (referred to as Step 3-1) can optimize the number of (re-)transmissions to be performed by the TX UE 100.
  • Step 3-2 allows for RLF declaration (i.e., triggering a RLF event) by the TX UE 100 based on the first and second counters, i.e., Cl and C2, maintained in Step 2.
  • Step 3-1 re-transmission optimization: Based on the previously defined operation in Step 2, it is possible to optimize the number of (re-)transmissions to be performed by the TX UE 100 taking into consideration the potential channel access failures at the RX UE 200.
  • the RX UE 200 has received the HARQ-based transmission 302 from the TX UE 100 successfully, but the HARQ-ACK feedback 504 conveyed in the PSFCH (i.e., the second resource 604) cannot be transmitted by the RX UE 200 due to the feedback channel being not available (e.g., a failed LBT) on the side of the RX UE 200.
  • the TX UE 100 is expecting a PSFCH transmission from the RX UE 200, i.e., HARQ-ACK or HARQ-NACK, depending on the outcome at the RX UE 200. Therefore,
  • the TX UE 100 performs the energy detection operation, e.g., CCA, as described in Option 1 of Step 2.
  • the TX UE 100 If energy detection at the TX UE 100 shows the (e.g., feedback) channel to be BUSY and the TX UE 100 fails to receive the PSFCH, i.e., the PSFCH comprising the feedback message 504 is absent, the TX UE 100 assumes that the PSFCH (i.e., the feedback message 504 on the second resource 604) was never transmitted due to the feedback channel being not available, e.g., a channel access failure on the RX UE 200.
  • the PSFCH i.e., the feedback message 504 on the second resource 604
  • the TX UE 100 drops the (re-)transmission occasions of the same HARQ-based transmission that occur before the next (re-)transmission attempt of PSFCH and selects new resources for (re-)transmission. o Alternatively, the TX UE 100 may drop (e.g., up to) all retransmit occasions before selecting new resources.
  • the TX UE 100 may perform the sensing procedure 304 in Step 2 on the PSFCH occasions in which HARQ FB for the new (re)transmission occur, i.e., the method 300 is performed for the retransmission being the transmission 302 and/or the sending 304 on the new second resource 604.
  • o Step 3-2 (RLF procedure): Based on the previously defined Steps 0 to 2, the TX UE 100 may trigger (i.e., declare) an RLF based on the values of the first counter Cl and the second counter C2 using one or more of the following rules: o RLF is declared if C1>C2 and Cl - C2 > N, wherein I is a (pre-)configured integer number.
  • o RLF is declared if Cl - p - C2 > K, where p is a (pre-)configured value between 0 and 1, and K is a (pre-)configured integer number.
  • o RLF is declared if q • C2 > S where q is a (pre-)configured value between 0 and 1, and S is a (pre-)configured integer number.
  • o RLF is declared if C2 >Xand/or Cl > Y, wherein Xand Tare (pre)configured numbers.
  • the parameter p may be a weight that relates a rate of expected feedback messages to a rate of channel accesses (e.g., transmission) performed by the transmitting wireless device 100 in the SL communication.
  • At least one or each of the Steps 0 to 3 above occur in and/or during a pre-defined or (pre-)configured time interval.
  • a timer measuring T H ARQ can be triggered in the TX UE 100 upon a successful CCA operation (i.e., one that indicates the channel is free) for a sidelink transmission in unicast manner.
  • This timer can include multiple PSFCH occasions on which HARQ feedback associated to the sidelink transmission is expected.
  • Another timer T RL F can be triggered upon an unsuccessful CCA operation (i.e., one that indicates the channel is busy) and/or upon an absence of a SL HARQ feedback.
  • This timer is stopped or reset if the UE detects an indication of a successful channel access attempt or receives an expected HARQ feedback (ACK/NACK).
  • the TX UE 100 declares RLF in combination with Cl, C2 and expiry of T RLF .
  • an early RLF (before T RL F expires) is declared if channel access failure is detected at a point such that the channel busy time is larger than the remaining T RL F.
  • the first counter Cl and/or the second counter C2 is updated for every PSFCH occasion.
  • the first and second counters are updated every K PSFCH occasions.
  • the first counter Cl and/or the second counter C2 is updated once after all the said PSFCH occasions (e.g., resource candidates) have passed.
  • the second counter C2 is updated only if CCA is unsuccessful (e.g., the channel is not available) for all the said PSFCH occasions.
  • a transport block has multiple PSSCH transmissions (i.e., an initial transmission and one or more retransmissions)
  • Cl and/or C2 is updated once for each TB.
  • the RX UE 200 indicates to the TX UE 100 (e.g., via a PSSCH or a later PSFCH) that a previously missing PSFCH was due to a failed channel access at the RX UE 200, and the TX UE 100 uses this indication to update its second counter C2.
  • detailed embodiments may augment or modify the sensing 304 and/or Step 2.
  • the first and second counters are increased by a value dependent of the SL transmission parameter (briefly: transmission parameter), e.g., priority of the transmission 302.
  • the SL transmission e.g., triggering the sensing 304 in Option 3 has the same destination as the successful SL HARQ-based transmission 302, e.g., PSSCH/PSCCH.
  • the SL transmission (e.g., triggering the sensing 304) in Option 3 has a different destination than the successful SL HARQ-based transmission 302, e.g., PSSCH/PSCCH or S-SSB transmission.
  • the SL transmission (e.g., triggering the sensing 304) in Option 3 is a response to a previous transmission from the destination of the successful SL HARQ-based transmission, e.g., PSFCH transmission.
  • the TX UE 100 counts the number of consecutive failed clear channel assessments, i.e., the channel is considered BUSY, based on performing energy detection based on expected transmissions from the RX UE 200 or other UE(s).
  • the TX UE 100 counts the number of failed clear channel assessments, i.e., the channel is considered BUSY, without any associated upcoming transmission or expected transmission from other UEs.
  • the predefined timer THARQ is extended.
  • a length of the extension may be at least equal to the next HARQ feedback occasion (i.e., the extension may encompass the next occasion of the feedback channel) for the TX UE 100, e.g., a further occasion in which the TX UE 100 may receive a HARQ feedback from the RX UE 200.
  • the TX UE 100 reports the number of failed clear channel assessments, i.e., the channel is considered BUSY, and/or the number of absent HARQ feedbacks to a network (e.g., the network node 200 or the RAN 500), e.g. including a gNB 200 and/or a core network (CN).
  • a network e.g., the network node 200 or the RAN 500
  • CN core network
  • At least some embodiments of the technique can be based on, or by augmenting, the 3GPP document TS 38.213, version 17.0.0, and/or the 3GPP document TS 38.331, version 16.7.0, and/or the 3GPP document TS 38.321, version 16.7.0.
  • the technique may be implemented to meet an SL enhancement defined in a 3GPP work item (Wl) for Release 18 and/or in the 3GPP document RP-213678.
  • Wl 3GPP work item
  • Fig. 9 shows a schematic block diagram for an embodiment of the device 100.
  • the device 100 comprises processing circuitry, e.g., one or more processors 904 for performing the method 300 and memory 906 coupled to the processors 904.
  • the memory 906 may be encoded with instructions that implement at least one of the modules 102, 104, 105, and/or 106.
  • the one or more processors 904 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, such as the memory 906, transmitter functionality.
  • the one or more processors 904 may execute instructions stored in the memory 906.
  • 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 being configured to perform the action.
  • the device 100 may be embodied by a transmitting wireless device 900, e.g., functioning as a transmitting UE.
  • the transmitting wireless device 900 comprises a radio interface 902 coupled to the device 100 for radio communication with one or more transmitting stations, e.g., functioning as a transmitting base station or a transmitting UE.
  • a communication system 1000 includes a telecommunication network 1010, such as a 3GPP-type cellular network, which comprises an access network 1011, such as a radio access network, and a core network 1014.
  • the access network 1011 comprises a plurality of base stations 1012a, 1012b, 1012c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 1013a, 1013b, 1013c.
  • Each base station 1012a, 1012b, 1012c is connectable to the core network 1014 over a wired or wireless connection 1015.
  • a first user equipment (UE) 1091 located in coverage area 1013c is configured to wirelessly connect to, or be paged by, the corresponding base station 1012c.
  • a second UE 1092 in coverage area 1013a is wirelessly connectable to the corresponding base station 1012a. While a plurality of UEs 1091, 1092 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 1012.
  • Any one of the UEs 1091 and 1092 may embody the device 100.
  • the telecommunication network 1010 is itself connected to a host computer 1030, 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 1030 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 1021, 1022 between the telecommunication network 1010 and the host computer 1030 may extend directly from the core network 1014 to the host computer 1030 or may go via an optional intermediate network 1020.
  • the intermediate network 1020 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 1020, if any, may be a backbone network or the Internet; in particular, the intermediate network 1020 may comprise two or more sub-networks (not shown).
  • the communication system 1000 of Fig. 10 as a whole enables connectivity between one of the connected UEs 1091, 1092 and the host computer 1030.
  • the connectivity may be described as an over-the-top (OTT) connection 1050.
  • the host computer 1030 and the connected UEs 1091, 1092 are configured to communicate data and/or signaling via the OTT connection 1050, using the access network 1011, the core network 1014, any intermediate network 1020 and possible further infrastructure (not shown) as intermediaries.
  • the OTT connection 1050 may be transparent in the sense that the participating communication devices through which the OTT connection 1050 passes are unaware of routing of uplink and downlink communications.
  • a base station 1012 need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 1030 to be forwarded (e.g., handed over) to a connected UE 1091. Similarly, the base station 1012 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1091 towards the host computer 1030.
  • the performance or range of the OTT connection 1050 can be improved, e.g., in terms of increased spectral efficiency, energy consumption, throughput and/or reduced latency.
  • the host computer 1030 may indicate to the RAN 500 or the wireless device 100 (e.g., on an application layer) the QoS of the traffic or any one or more of the transmission parameters disclosed herein or any other trigger for performing or controlling the method 300.
  • a host computer 1110 comprises hardware 1115 including a communication interface 1116 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 1100.
  • the host computer 1110 further comprises processing circuitry 1118, which may have storage and/or processing capabilities.
  • the processing circuitry 1118 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 1110 further comprises software 1111, which is stored in or accessible by the host computer 1110 and executable by the processing circuitry 1118.
  • the software 1111 includes a host application 1112.
  • the host application 1112 may be operable to provide a service to a remote user, such as a UE 1130 connecting via an OTT connection 1150 terminating at the UE 1130 and the host computer 1110.
  • the host application 1112 may provide user data, which is transmitted using the OTT connection 1150.
  • the user data may depend on the location of the UE 1130.
  • the user data may comprise auxiliary information or precision advertisements (also: ads) delivered to the UE 1130.
  • the location may be reported by the UE 1130 to the host computer, e.g., using the OTT connection 1150, and/or by the base station 1120, e.g., using a connection 1160.
  • the communication system 1100 further includes a base station 1120 provided in a telecommunication system and comprising hardware 1125 enabling it to communicate with the host computer 1110 and with the UE 1130.
  • the hardware 1125 may include a communication interface 1126 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 1100 7 as well as a radio interface 1127 for setting up and maintaining at least a wireless connection 1170 with a UE 1130 located in a coverage area (not shown in Fig. 11) served by the base station 1120.
  • the communication interface 1126 may be configured to facilitate a connection 1160 to the host computer 1110.
  • the connection 1160 may be direct, or it may pass through a core network (not shown in Fig. 11) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system.
  • the hardware 1125 of the base station 1120 further includes processing circuitry 1128, 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 1120 further has software 1121 stored internally or accessible via an external connection.
  • the communication system 1100 further includes the UE 1130 already referred to.
  • Its hardware 1135 may include a radio interface 1137 configured to set up and maintain a wireless connection 1170 with a base station serving a coverage area in which the UE 1130 is currently located.
  • the hardware 1135 of the UE 1130 further includes processing circuitry 1138, 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 1130 further comprises software 1131, which is stored in or accessible by the UE 1130 and executable by the processing circuitry 1138.
  • the software 1131 includes a client application 1132.
  • the client application 1132 may be operable to provide a service to a human or non-human user via the UE 1130, with the support of the host computer 1110.
  • an executing host application 1112 may communicate with the executing client application 1132 via the OTT connection 1150 terminating at the UE 1130 and the host computer 1110.
  • the client application 1132 may receive request data from the host application 1112 and provide user data in response to the request data.
  • the OTT connection 1150 may transfer both the request data and the user data.
  • the client application 1132 may interact with the user to generate the user data that it provides.
  • the host computer 1110, base station 1120 and UE 1130 illustrated in Fig. 11 may be identical to the host computer 1030, one of the base stations 1012a, 1012b, 1012c and one of the UEs 1091, 1092 of Fig. 10, respectively.
  • the inner workings of these entities may be as shown in Fig. 11, and, independently, the surrounding network topology may be that of Fig. 10.
  • the OTT connection 1150 has been drawn abstractly to illustrate the communication between the host computer 1110 and the UE 1130 via the base station 1120, 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 1130 or from the service provider operating the host computer 1110, or both. While the OTT connection 1150 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 1170 between the UE 1130 and the base station 1120 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 1130 using the OTT connection 1150, in which the wireless connection 1170 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 1150 may be implemented in the software 1111 of the host computer 1110 or in the software 1131 of the UE 1130, or both.
  • sensors may be deployed in or in association with communication devices through which the OTT connection 1150 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 1111, 1131 may compute or estimate the monitored quantities.
  • the reconfiguring of the OTT connection 1150 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 1120, and it may be unknown or imperceptible to the base station 1120. Such procedures and functionalities may be known and practiced in the art.
  • measurements may involve proprietary UE signaling facilitating the host computer's 1110 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 1111, 1131 causes messages to be transmitted, in particular empty or "dummy" messages, using the OTT connection 1150 while it monitors propagation times, errors etc.
  • Fig. 12 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. 10 and 11. For simplicity of the present disclosure, only drawing references to Fig. 12 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. 13 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. 10 and 11. For simplicity of the present disclosure, only drawing references to Fig. 13 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.
  • At least some embodiments of the technique can, e.g. in addition to a missing HARQ feedback, use the sensing (e.g., a list-before-talk, LBT, mechanism) for a radio link failure (RLF) procedure in the SL communication at the transmitting wireless device (TX UE) to avoid declaring and/or triggering the RLF too early or wrongly due to missing transmissions of the feedback message.
  • RLF radio link failure
  • Same or further embodiments enable differentiation between absence of expected feedback messages (e.g., SL HARQ transmissions) due to bad channel conditions and/or due to the channel being not available (e.g., an LBT failure at the receiving wireless device).
  • Same or still further embodiments can reduce the number of unnecessary retransmissions due to a busy channel (e.g., LBT failure).

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Une technique de gestion d'une communication de liaison latérale (SL) avec un dispositif sans fil de réception (200) est décrite. Selon un aspect de procédé de la technique effectuée par un dispositif sans fil émetteur (100 ; 900 ; 1091 ; 1092 ; 1130), des données sont transmises (302) du dispositif sans fil émetteur (100 ; 900 ; 1091 ; 1092 ; 1130) au dispositif sans fil récepteur (200) à l'aide d'une première ressource (602) de la SL. Le dispositif sans fil de transmission (100 ; 900 ; 1091 ; 1092 ; 1130) détecte (304) si un canal de rétroaction de la SL est disponible au niveau d'une seconde ressource (604) associée à la première ressource (602) pour recevoir (306) un message de rétroaction dans la seconde ressource (604) depuis le dispositif sans fil de réception (200) au niveau du dispositif sans fil de transmission (100 ; 900 ; 1091 ; 1092 ; 1130) en réponse à la transmission (302) des données.
PCT/EP2023/056807 2022-03-18 2023-03-16 Technique de gestion d'une communication de liaison latérale WO2023175105A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020226408A1 (fr) * 2019-05-03 2020-11-12 엘지전자 주식회사 Informations relatives à une ressource pour transmission en liaison latérale
WO2021091294A1 (fr) * 2019-11-07 2021-05-14 Lg Electronics Inc. Procédé et appareil pour indiquer une défaillance de liaison radio de liaison latérale dans un système de communication sans fil
WO2021230672A1 (fr) * 2020-05-13 2021-11-18 엘지전자 주식회사 Procédé et appareil pour effectuer une opération rlf basée sur une dxt dans nr v2x.
WO2022021314A1 (fr) * 2020-07-31 2022-02-03 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Équipement utilisateur et procédé de communication de liaison latérale dans un spectre de fréquences sans licence

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020226408A1 (fr) * 2019-05-03 2020-11-12 엘지전자 주식회사 Informations relatives à une ressource pour transmission en liaison latérale
US20220217697A1 (en) * 2019-05-03 2022-07-07 Lg Electronics Inc. Information relating to resource for sidelink transmission
WO2021091294A1 (fr) * 2019-11-07 2021-05-14 Lg Electronics Inc. Procédé et appareil pour indiquer une défaillance de liaison radio de liaison latérale dans un système de communication sans fil
US11483885B2 (en) * 2019-11-07 2022-10-25 Lg Electronics Inc. Method and apparatus for indicating sidelink radio link failure in a wireless communication system
WO2021230672A1 (fr) * 2020-05-13 2021-11-18 엘지전자 주식회사 Procédé et appareil pour effectuer une opération rlf basée sur une dxt dans nr v2x.
EP4124158A1 (fr) * 2020-05-13 2023-01-25 LG Electronics Inc. Procédé et appareil pour effectuer une opération rlf basée sur une dxt dans nr v2x
WO2022021314A1 (fr) * 2020-07-31 2022-02-03 Guangdong Oppo Mobile Telecommunications Corp., Ltd. Équipement utilisateur et procédé de communication de liaison latérale dans un spectre de fréquences sans licence

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
3GPP DOCUMENT TS 38.213
3GPP DOCUMENT TS 38.321
3GPP DOCUMENT TS 38.331

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