How to deal with consistent listen-before-talk failures

Abstract

An example embodiment of the present disclosure relates to a remedy for consistent listen-before-talk (LBT) failures, in which a first terminal device determines that consistent LBT failures have been detected on a set of sidelink resources and transmits information related to the consistent LBT failures to one of a second terminal device or a network device, thereby improving reliability of sidelink communications even under the consistent LBT failure conditions.

Description

[Technical Field]

[0001] FIELD Exemplary embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to an apparatus, method, and computer-readable storage medium for addressing consistent listen-before-talk (LBT) failures. [Background technology]

[0002] The Unlicensed Radio (NR) system relies on a mechanism for user equipment (UE) to detect radio resources before starting a transmission. This technique is known as LBT. NR in the Unlicensed Band (NR-U) performs an LBT procedure before each transmission to seize the channel in order to coexist with other wireless technologies, such as Wi-Fi systems, in the unlicensed band.

[0003] Sidelink (SL) transmissions can also operate in unlicensed spectrum. The LBT mechanism of NR-U can be introduced into SL transmissions to coexist with other radio systems in unlicensed spectrum. Before each SL transmission, the SL UE performs an LBT procedure and aborts the SL transmission if the LBT fails. Enhancements to SL in unlicensed spectrum (SL-U) are still needed. Summary of the Invention

[0004] Generally, the exemplary embodiments of the present disclosure provide a solution for dealing with consistent LBT failures.

[0005] In a first aspect, a first terminal device is provided, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first terminal device to at least determine that consistent Listen-Before-Talk (LBT) failures have been detected in a set of sidelink resources; and transmit information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0006] In a second aspect, a second terminal device is provided, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second terminal device to at least receive information regarding consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and transmit at least one sidelink transmission on the at least one sidelink resource determined based on the received information.

[0007] In a third aspect, a network device is provided, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device to at least: receive, from a first terminal device, first information related to consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and transmit, to a second terminal device, second information determined based on the received first information.

[0008] In a fourth aspect, a method is provided that includes determining, at a first terminal device, that consistent Listen-Before-Talk (LBT) failures are detected on a set of sidelink resources, and transmitting information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0009] In a fifth aspect, a method is provided, comprising: receiving, at a first terminal device, information related to consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and transmitting, to the first terminal device, at least one sidelink transmission on at least one sidelink resource determined based on the received information.

[0010] In a sixth aspect, a method is provided, the method including: receiving, at a network device, first information from a first terminal device related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and transmitting, to a second terminal device, second information determined based on the first information.

[0011] In a seventh aspect, an apparatus is provided, comprising: means for determining that consistent Listen-Before-Talk (LBT) failures are detected on a set of sidelink resources; and means for transmitting information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0012] In an eighth aspect, an apparatus is provided, comprising: means for receiving information related to consistent Listen-Before-Talk (LBT) failures detected by a first terminal device on a set of sidelink resources; and means for sending, to the first terminal device, at least one sidelink transmission on the at least one sidelink resource determined based on the received information.

[0013] In a ninth aspect, an apparatus is provided, comprising: means for receiving, from a first terminal device, first information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and means for transmitting, to a second terminal device, second information determined based on the first information.

[0014] In a tenth aspect, an apparatus is provided, comprising: a determining circuit configured to determine that consistent Listen-Before-Talk (LBT) failures have been detected on a set of sidelink resources; and a transmitting circuit configured to transmit information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0015] In an eleventh aspect, an apparatus is provided, comprising: receiving circuitry configured to receive information related to consistent listen-before-talk (LBT) failures detected by a first terminal device on a set of sidelink resources; and transmitting circuitry configured to transmit, to the first terminal device, at least one sidelink transmission on the at least one sidelink resource determined based on the received information.

[0016] In a twelfth aspect, an apparatus is provided, comprising: a receiving circuit configured to receive, from a first terminal device, first information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; and a transmitting circuit configured to transmit, to a second terminal device, second information determined based on the first information.

[0017] In a thirteenth aspect, there is provided a non-transitory computer-readable storage medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform a method according to any one of the fourth to sixth aspects above.

[0018] In a fourteenth aspect, a computer program is provided that includes instructions that, when executed by a first terminal device, cause the first terminal device to at least determine that consistent Listen-Before-Talk (LBT) failures have been detected in a set of sidelink resources, and transmit information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0019] In a fifteenth aspect, a computer program is provided that includes instructions that, when executed by a second terminal device, cause the second terminal device to at least receive information related to consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources, and to transmit at least one sidelink transmission on the at least one sidelink resource determined based on the received information.

[0020] In a sixteenth aspect, a computer program is provided that includes instructions that, when executed by a network device, cause the network device to at least receive, from a first terminal device, first information regarding consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources, and transmit, to a second terminal device, second information determined based on the first information.

[0021] The Abstract is not intended to identify key features or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description. [Brief explanation of the drawings]

[0022] Some embodiments will now be described with reference to the following drawings. [Figure 1A] FIG. 1A illustrates an example of a network environment in which some embodiments of the present disclosure may be implemented. [Figure 1B]FIG. 1B illustrates an example of an SL transmission procedure with hybrid automatic repeat request (HARQ) feedback in which some embodiments of the present disclosure may be implemented. [Figure 1C] FIG. 1C illustrates an example of an SL slot in which an embodiment of the present invention may be implemented. [Figure 1D] FIG. 1D shows an example of channel mapping in SL transmission in which an embodiment of the present invention may be implemented. [Figure 1E] FIG. 1E illustrates an example of Inter-UE Coordination (IUC) information MAC CE in a first IUC scheme in which an embodiment of the present invention may be implemented. [Figure 1F] FIG. 1F illustrates an example of an IUC request MAC CE in a first IUC scheme in which an embodiment of the present invention may be implemented. [Figure 2] FIG. 2 shows a flowchart illustrating a communication process according to some embodiments of the present disclosure. [Figure 3] FIG. 3 shows a flowchart illustrating procedures in different cases for the operation of a first terminal device according to some embodiments of the present disclosure. [Figure 4] FIG. 4 shows a flowchart of an exemplary method implemented in a first terminal device according to one embodiment of the present invention. [Figure 5] FIG. 5 illustrates a flowchart of an exemplary method implemented in a second terminal device according to one embodiment of the present invention. [Figure 6] FIG. 6 illustrates a flowchart of an exemplary method implemented in a network device according to some embodiments of the present disclosure. [Figure 7] FIG. 7 shows a simplified block diagram of a device suitable for implementing some embodiments of the present disclosure. [Figure 8] 8 shows a block diagram illustrating an example of a computer-readable medium according to some embodiments of the present disclosure. Throughout the drawings, identical or similar reference numerals represent identical or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0023] The principles of the present disclosure will be explained with reference to several examples. These examples are for illustrative purposes and are intended to assist those skilled in the art in understanding and practicing the present disclosure, but are not intended to limit the scope of the disclosure. The contents described in the present disclosure can be implemented in various ways other than those described below.

[0024] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] In this disclosure, the phrases "one embodiment," "embodiment," "exemplary embodiment," and the like indicate that the embodiment has a particular function, structure, or characteristic, but do not necessarily refer to all embodiments that have the particular function, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, if a particular function, structure, or feature is described in connection with an embodiment, it is within the knowledge of a person skilled in the art that such function, structure, or feature can be applied to other embodiments even if not explicitly described therein.

[0026] When terms such as "first" and "second" are used to describe various elements, these elements are not limited by these terms. These terms are used merely to distinguish one element from another. For example, a first element could be referred to as a second element, and similarly, a second element could be referred to as a first element, without departing from the scope of the example embodiments. As used herein, the term "and / or" includes all combinations, including combinations of one or more of the listed terms.

[0027] The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the scope of the example embodiments. As used herein, singular forms such as "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Furthermore, as used herein, the terms "comprises," "comprising," "has," "having," "includes," and / or "comprising" identify the presence of stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. As used herein, "any one or more of the following: " and "at least one " and similar expressions, when a list of two or more elements is connected by "and" or "or," means at least one element, or at least two or more elements, or at least all elements.

[0028] In this application, the term "circuit" means (a) hardware-only circuit implementations (e.g., implementations using only analog and / or digital circuitry); and (b) a combination of hardware circuitry and software (where applicable); (i) a combination of analog and / or digital hardware circuitry and software / firmware; and (ii) A configuration in which a portion of a hardware processor and software (including a digital signal processor), software, and memory work together to cause a device such as a mobile phone or server to perform various functions; and (c) a hardware circuit or processor (including a microprocessor or part of a microprocessor) that requires software (e.g., firmware), including the absence of the software if it is not necessary for operation; It may refer to one or more, or all, of the following:

[0029] This definition of circuit applies to all uses of the term in this application, including the claims. By way of further example, the term "circuit" as used herein also includes a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor, and its associated software and / or firmware implementations. For example, the term "circuit," when applied to certain claim elements, also includes a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0030] As used herein, a "communication network" refers to a network conforming to an appropriate communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), or Narrowband Internet of Things (NB-IoT). Furthermore, communications between terminal devices and network devices within a communication network may be performed according to any currently known or future-developed generation of communication protocols, including, but not limited to, fourth-generation (4G), 4.5G, and fifth-generation (5G) communication protocols. Embodiments of the present disclosure are applicable to various communication systems. With the rapid development of communication technologies, there are naturally future communication technologies and systems in which the present disclosure can be implemented. The scope of the present disclosure is not limited to the above.

[0031] In this specification, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services therefrom. The term "network device" may refer to, for example, a base station (BS) or an access point (AP). Depending on the applied terminology and technology, it may refer to a Node B (Node B or NB), evolved Node B (eNode B or eNB), NR NB (also called gNB), remote radio unit (RRU), radio header (RH), remote radio head (RRH), relay, femto, pico, or other low-power node. In the following description, the terms "network device" and "network node" may be used interchangeably.

[0032] "Terminal" refers to any end device capable of wireless communication. By way of example and not limitation, a terminal may also be referred to as a communications device, user equipment (UE), subscriber station (SS), mobile subscriber station, mobile station (MS), or access terminal (AT). Terminal devices include mobile phones, cellular phones, smartphones, VoIP phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless customer premise equipment (CPEs), Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, and similar devices. In the following description, the terms "terminal device," "communications equipment," "terminal," "user equipment," and "UE" may be used interchangeably.

[0033] As mentioned above, the introduction of the LBT mechanism for sidelink transmission in NR-U enables sidelink transmission to coexist with other wireless systems in unlicensed spectrum. Before each sidelink transmission, the sidelink UE performs the LBT procedure to seize the channel, and if the LBT fails, the sidelink transmission is aborted.

[0034] In RAN2#119bis-e, it was agreed that SL-U will support a consistent LBT failure detection procedure. In the consistent LBT failure detection procedure, a device may count the number of LBT failures. If this count exceeds a threshold (specified in device, NW, or resource-specific configuration), a consistent LBT failure is triggered. This counting is performed during a monitoring period or window that may be initiated based on device decision, network trigger, or a moving window. The duration of the monitoring window may be NW configuration, resource-specific configuration, or left to device decision. SL-specific consistent LBT failure detection (and recovery procedure) is a device-centric phenomenon and therefore affects procedures where two or more devices interact. For example, if a transmitting (Tx) UE does not experience consistent LBT failures in a particular resource block (RB) set (or resource pool), the Tx UE can access resources in the RB set (or resource pool), i.e., successfully perform LBT, and can perform PSCCH / PSSCH transmissions whose associated sidelink control information (SCI) requests HARQ feedback via PSFCH resources mapped to PSCCH / PSSCH resources. However, an Rx UE may experience consistent LBT failures in the RB set (or resource pool) to which a PSFCH is mapped, and therefore cannot access the mapped PSFCH resources and cannot provide HARQ feedback. In such a case, the Tx UE cannot determine whether to perform HARQ retransmissions, and communication reliability is not guaranteed.

[0035] There is a need to enhance sidelink transmissions. Therefore, embodiments of the present disclosure provide a solution to address consistent LBT failures in sidelink communications.

[0036] 1A illustrates an example network environment 100 in which example embodiments of the present disclosure may be implemented. In describing example embodiments of the present disclosure, the network environment 100 may also be referred to as a communications system 100 (e.g., a portion of a communications network). For purposes of explanation only, some aspects of the exemplary embodiments are described in the context of one or more terminal devices and network devices communicating with each other. However, it should be understood that the description is also applicable to other types of devices or similar devices that may be referred to using other terminology.

[0037] As shown in FIG. 1A, the communication environment 100 includes a network device 110 (hereinafter also referred to as gNB 110), a first terminal device 120-1, and a second terminal device 120-2. The network device 110 is associated with one or more service regions, or land areas, referred to as "cells." As shown in FIG. 1A, the network device 110 manages a cell 105 and provides service to a first terminal device 120-1 and a second terminal device 120-2 (collectively referred to as terminal devices 120) within the cell 105. The number of network devices, terminal devices, and / or cells shown is for illustrative purposes and does not limit the scope of the present disclosure. The communication system 100 may include any number of network devices, terminal devices, and / or cells suitable for implementing the present disclosure.

[0038] To transmit data and / or control information, terminal devices 120-1 and 120-2 each communicate with network device 110. In particular, in the exemplary scenario of Figure 1A, first terminal device 120-1 communicates with network device 110 via communication link 115-1, and second terminal device 120-2 communicates with network device 110 via communication channel 115-2. When transmitting from network device 110 to terminal device 120-1 or 120-2, communication link 115-1 or 115-2 may be referred to as a downlink, while when transmitting from terminal device 120-1 or 120-2 to network device 110, communication link 115-1 or 115-2 may be referred to as an uplink.

[0039] In addition to the communication links 115-1 and 115-2, the first terminal device 120-1 and the second terminal device 120-2 may perform sidelink transmissions (also referred to as device-to-device communication (D2D)) via a sidelink 125 between the first terminal device 120-1 and the second terminal device 120-2. For example, in the exemplary scenario of FIG. 1A , the second terminal device 120-2 (hereinafter also referred to as the Tx UE 120-2, the SLTx UE 120-2, or the initiating terminal device 120-2) performs a sidelink transmission 125-1 to the first terminal device 120-1 via the sidelink 125. The second terminal device 120-2 (hereinafter also referred to as the Rx UE 120-1, the SL Rx UE 120-1, or the responding terminal device 120-1) performs a sidelink transmission 125-1 to the first terminal device 120-1 via the sidelink 125. In some demonstrative embodiments, the sidelink transmission 125-1 is performed in an unlicensed band where various wireless devices based on different wireless technologies share the same wireless spectrum.

[0040] As used herein, the term "sidelink transmission" generally refers to a transmission from one terminal device to another. A sidelink transmission is used to transmit data or control information related to sidelink communication, such as sidelink data, sidelink control information, sidelink feedback information, or the like. As used herein, the term "sidelink channel" refers to any channel used for sidelink communication, such as the Physical Sidelink Shared Channel (PSSCH), the Physical Sidelink Control Channel (PSCCH), the Physical Sidelink Discovery Channel (PSDCH), the Physical Sidelink Broadcast Channel (PSBCH), the Physical Sidelink Feedback Channel (PSFCH), and any existing or future sidelink channels.

[0041] Channel access in the sidelink may rely on a so-called LBT function, where, before making a sidelink transmission 125-1, the second terminal device 120-2 first "senses" the communication channel to ensure that there is no communication on it before transmitting on it. For example, the "channel sensing" procedure may be achieved by detecting the energy level on the communication channel. LBT parameters (type / duration, clear channel assessment parameters, etc.) may be configured in the second terminal device 120-2 by, for example, the network device 110.

[0042] In some embodiments, network device 110 may not be present in communication environment 100. For example, one or more of terminal devices 120-1 and 120-2, as well as other terminal devices not shown, may be located outside the coverage range of network device 110 (i.e., outside cell 105). In such cases, only sidelink communication may exist between one or more of terminal devices 120-1, 120-2 and other terminal devices not shown in FIG. 1A that may be outside cell 105.

[0043] Although the communication environment 100 of FIG. 1A depicts a network device 110 and terminal devices 120-1 and 120-2, embodiments of the present disclosure are equally applicable to other suitable communication devices capable of communicating with each other. That is, examples of the present disclosure are not limited to the exemplary scenario of FIG. 1A. In this regard, while FIG. 1A schematically depicts the network device 110 as a base station and the terminal device 120 as an in-vehicle terminal device, these illustrations are exemplary and do not imply any limitations. In other examples, the network device 110 and the terminal device 120 may be any communication devices, including other communication devices, for example, other wireless communication devices.

[0044] When the terminal devices 120-1 and 120-2 are vehicle-mounted terminal devices, the communications associated therewith may be referred to as V2X communications. More generally, although not shown in FIG. 1A, the V2X communications associated with the terminal device 120 may include communication channels between the first or second terminal device 120-1 or 120-2, respectively, and other communications devices, such as, but not limited to, infrastructure devices, other vehicle-mounted terminal devices, pedestrian devices, roadside units, or other communications devices. Furthermore, although not shown in FIG. 1A, all of the communications links shown in FIG. 1A may be performed via one or more relays.

[0045] Communications in the network environment 100 may be conducted in accordance with appropriate communications protocol(s), including, but not limited to, wireless local network communications protocols (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc.), including, but not limited to, fourth-generation (4G) and fifth-generation (5G) cellular communications protocols, and / or other protocols now known or developed in the future. Further, communications may utilize any suitable wireless communications technology, including, but not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or other technologies now known or developed in the future.

[0046] In 3GPP Rel-16, NR SL is designed to enable UEs to communicate with other nearby UEs via direct / SL communication. Two resource allocation modes are specified, one of which an SL Tx UE can select for NR SL transmission. These modes are denoted NR SL Mode 1 and NR SL Mode 2. In NR SL Mode 1, the network device can assign or schedule sidelink transmission resources to the terminal device, while in NR SL Mode 2, the terminal device can autonomously select SL transmission resources.

[0047] In the sub-7 GHz unlicensed bands, coexistence of New Radio (NR) with other systems such as IEEE 802.11 is ensured by the Listen-Before-Talk (LBT) channel access mechanism. Similarly, a terminal device intending to perform a sidelink (SL) transmission must first successfully complete an LBT check before commencing its transmission.

[0048] To pass the LBT check, the terminal device must confirm that the channel is available for consecutive Clear Channel Assessment (CCA) slots. In the sub-7 GHz band, these slots last 9 μs. The UE determines that a channel is available for a CCA slot if the measured power or collected energy during the CCA slot is below a regulatory-specified threshold that depends on the operating band and geographic region.

[0049] In some embodiments, when Tx UE 120-2 initiates sidelink communication, it must obtain the "right" to access the channel for a certain period of time, denoted in the rules as the channel occupation time (COT). This right is obtained by applying an "extended" LBT procedure, where the channel is considered free for the entire contention window (CW). This "extended" LBT procedure is referred to as LBT Type 1. The duration of the COT and CW depends on the channel access priority class (CAPC) assigned to the traffic of Rx UE 120-1. In some example embodiments, after successfully completing LBT Type 1, Tx UE 120-2, which transmits SL transmissions to Rx UE 120-1 on the PSCCH and PSSCH, obtains a COT1 with a duration associated with the corresponding CAPC. The obtained COT1 remains valid even if Tx UE 120-2 pauses transmission, unless Tx UE 120-2 wants to perform a new transmission (within the COT). It is still necessary to implement the "abbreviated" LBT procedure, which is named LBT Type 2 according to 3GPP® specification TS37.213 and has the following variations:

[0050] Type 2A (25 μs LBT) applies to an SL transmission within the COT acquired by the initiating device, and also applies to an SL transmission that follows another SL transmission, if the gap between two SL transmissions is 25 μs or more.

[0051] Type 2B (16 μs LBT) applies to SL transmissions within the COT acquired by the initiator and can only be used if the interval between SL transmissions is exactly 16 μs.

[0052] Type 2C (without LBT) can only be used for SL transmissions following other SL transmissions if the gap between SL transmissions is less than 16 μs and the allowed duration of the SL transmission is less than or equal to 584 μs.

[0053] 1B illustrates an example of an SL transmission procedure 130, including HARQ feedback, in which an embodiment of the present disclosure may be implemented. For illustrative purposes, the SL transmission procedure 130 is described with reference to FIG. 1A. The SL transmission procedure 130 may include a Tx UE 120-2 and an Rx UE 120-1, as shown in FIG. 1A. It should be noted that although the communication process 130 is described with reference to the network environment 100 of FIG. 1A, the communication process 130 is equally applicable to other similar communication scenarios.

[0054] As shown in FIG. 1B, at 131, unicast is established between Tx UE 120-2 and Rx UE 120-1. At 132, Tx UE 120-2 performs an initial transmission to Rx UE 120-1. The initial transmission includes an SCI and a TB, each of which includes one or more MAC protocol data units (PDUs). The SCI employs a two-level SCI structure and indicates a source ID, a destination ID, a unicast type, a HARQ feedback enable / disable indicator, and HARQ parameters (e.g., HARQ process number, new data indicator (NDI), redundancy version (RV)). For example, the SCI can indicate that HARQ feedback is enabled using the HARQ feedback enable / disable indicator. At 133, Rx UE 120-1 decodes the SCI. At 134, Rx UE 120-1 attempts to decode the TB. At 135, if decoding of the TB fails, Rx UE 120-1 notifies Tx UE 120-2 of the failure of the data transmission. For example, this notification may be represented as a "NACK." At 136, Tx UE 120-2 retransmits the SCI and TB. At 137, Rx UE 120-1 decodes the retransmitted SCI. At 134, Rx UE 120-1 attempts to decode the retransmitted TB. At 138, if decoding of the TB is successful, Rx UE 120-1 sends a notification to Tx UE 120-2 indicating the success of the data transmission. For example, this notification may be represented as an "ACK."

[0055] The PSFCH was introduced in Rel-16 to enable HARQ feedback over the sidelink from the Rx UE 120-1, the intended recipient of a PSSCH transmission, to the Tx UE 120-2 that transmitted it. Within the PSFCH, a Zadoff-Chu sequence within one physical resource block (PRB) is transmitted repeatedly across two OFDM symbols, the first of which may be used for AGC near the end of the SL resources within the slot. Figure 1C illustrates an example SL slot in which some embodiments of the present disclosure are implemented. The Zadoff-Chu sequence as a base sequence is pre-configured for each sidelink resource pool.

[0056] The time resource for the PSFCH is preconfigured to occur once every 0, 1, 2, or 4 slots according to 3GPP TS 38.331. The HARQ feedback resource within the PSFCH is derived from the resource position of the PSCCH / PSSCH. A slot-wise configuration parameter K is configured for the timing of the PSSCH to HARQ. The timing of the PSFCH occurrence is determined from K. If the last symbol in a PSSCH transmission is in slot n, the HARQ feedback occurs in slot n+a, where a is the smallest integer greater than or equal to K, provided that slot n+a contains the PSFCH resource. The time interval of K or more slots is to account for the processing delay of the Rx UE 120-1 in PSCCH decoding and HARQ feedback generation. K can be equal to 2 or 3, and a single value of K can be preconfigured per resource pool. This allows multiple Rx UEs using the same resource pool to utilize the same mapping of PSFCH resources for HARQ feedback. The parameter K determines the N PSSCH slots associated with the slot containing the PSFCH.

[0057] 1D shows an example of a channel mapping in which some embodiments of the present disclosure may be implemented. The duration of the PSFCH resource is set to N=4, there are four PSSCH slots associated with the PSFCH, and K or sl-MinTimeGapPSFCH is set to 2. If there are L subchannels in the resource pool and N PSSCH slots associated with the slot containing the PSFCH, there are N*L subchannels associated with the PSFCH symbol. If there are M PRBs available for the PSFCH within the PSFCH symbol, M PRBs are available for HARQ feedback for transmissions on the N*L subchannels.

[0058] If M is set to a multiple of N*L, the M unique sets of PRBs allocated to HARQ feedback for each subchannel within the PSFCH period are calculated as M / (N*L). Of the M PRBs available for the PSFCH, the first M sets of PRBs are allocated to HARQ feedback for transmissions in the first slot of the first subchannel. The second set of M PRBs is associated with HARQ feedback for transmissions in the first subchannel in the second slot, and so on.

[0059] In some example embodiments, N=4 and L=3 in FIG. 1D, showing the case where all PRBs in a PSFCH symbol are available for the PSFCH. In this example, HARQ feedback for a transmission in PSSCHx is based on the M PRBs in the corresponding PSFCH symbol. set A set of PRBs x is sent, where x=1,...,12.

[0060] In some embodiments, M associated with a subchannel setA set of PRBs may be shared among multiple Rx UEs for ACK / NACK feedback in groupcast communication or for different PSSCH transmissions in the same subchannel. For each PRB available for the PSFCH, Q cyclic shift pairs are available to support ACK or NACK feedback for Q Rx UEs. In the resource pool, the number of Q cyclic shift pairs is pre-configured and can be 1, 2, 3, or 6.

[0061] In some embodiments, the number of PSFCH resources F available to support HARQ feedback for a particular transmission can be calculated. In 3GPP TS 38.213, F is defined as:

number

[0062] In some demonstrative embodiments, the F PSFCH resources (available for multiplexing HARQ feedback for PSSCH) are determined based on the following two options:

[0063] Option 1: F is determined based on the L PSSCH subchannels used in the PSSCH, and F is given by F=LPSSCH*M set *QPSFCHs, which are associated with L PSSCH subchannels of the PSSCH. The PSSCH has L PSSCH subchannels, each with M PSSCHs for the PSFCH. set PRBs are associated with each PRB, and Q period shift pairs are available for each PRB.

[0064] Option 2: F is calculated based only on the starting subchannel used by the PSSCH, or only on one subchannel if L PSSCH > 1. F = M set *Q PSFCHs, which are associated with the starting subchannel of the PSSCH. Each subchannel has M set PRBs for PSFCH are allocated, and Q cyclic shift pairs are available for each PRB.

[0065] In some embodiments, the F available PSFCH resources may be indexed based on a PRB index in the frequency domain and a cyclic shift pair index in the code domain. The method of mapping PSFCH index i (i=1, 2, ..., F) to PRBs and Q cyclic shift pairs is such that PSFCH index i first increases with the PRB index and continues until it reaches the number of available PRBs for the PSFCH. It then increases with the cyclic shift pair index, then increases with the PRB index again, and so on.

[0066] From the F PSFCHs available for HARQ feedback for a particular transmission, the Rx UE selects the index i of the PSFCH for HARQ feedback. This selection is made as follows:

[0067]

number

[0068] where T ID is the Layer 1 identifier of the Rx UE, indicated by the SCI in the second stage. For unicast ACK / NACK feedback and groupcast NACK only feedback, R ID = 0. Groupcast NACK only feedback is Groupcast option 1.

[0069] For Groupcast ACK / NACK feedback or Groupcast option 2, R ID is equal to the Rx UE identifier in the group, which is signaled by higher layers. For the number X of Rx UEs in the group, the Rx UE identifier is an integer between 0 and X-1. The Rx UE determines the PRB and cyclic shift pair to use for its HARQ feedback transmission based on the PSFCH index i. The Rx UE transmits a NACK or ACK using the first or second cyclic shift of the cyclic shift pair associated with the selected PSFCH index i, respectively.

[0070] By selecting the PSFCH with index i, the Rx UE can distinguish HARQ feedbacks of different Rx UEs via the Rx UE identifier, e.g., groupcast option 2, and distinguish HARQ feedbacks addressed to the Tx UE via the Layer 1 ID of the Tx UE (e.g., unicast). ID = 0, the Rx UE uses the Layer 1 ID Tx UE identifier T ID Based only on the PSFCH index i, we select the same PSFCH index i for NACK-only feedback.

[0071] In some embodiments, the SL UE supports Inter-UE Coordination (IUC) in Mode 2, where UE-A transmits coordination information about resources to UE-B, which then uses the coordination information for resource (re)selection. Two modes of Inter-UE Coordination are supported: In the first IUC mode, the coordination information transmitted from UE-A to UE-B is the preferred or non-preferred resources for UE-B's transmission; in the second IUC mode, the coordination information transmitted from UE-A to UE-B is the presence or absence of expected / potential resource contention for the resources indicated in UE-B's SCI.

[0072] In the first IUC method, IUC is triggered by an explicit request from UE-B or by a condition in UE-A. UE-A, as the intended recipient of UE-B, determines a set of resources or slots reserved by other UEs where SL reception from UE-B is not expected due to half-duplex communication. UE-A uses these resources as a set of non-preferred resources or excludes these resources to determine a set of preferred resources and transmits the preferred / non-preferred resources to UE-B. UE-B's resource selection (reselection) can be based on UE-B's sensing results (if available) and the adjustment information received from UE-A, or based solely on the adjustment information received from UE-A. In the first IUC method, IUC transmission can use either the MAC CE and the second-stage SCI, or only the MAC CE. Explicit IUC requests and reports in the unicast method are supported. TS38.331 specifies that the trigger condition for sending an IUC method 1 prioritized / non-prioritized resource message or an IUC method 1 request message is either dependent on the implementation of UE-A or when UE-A has data to transmit.

[0073] In the second IUC scheme, UE-A identifies expected / potential resource conflicts within the resources indicated in UE-B's SCI as resources reserved by other UEs that fully / partially overlap with the resources indicated in UE-B's SCI by UE-A, or slots where UE-A is the intended recipient of UE-B and does not perform SL reception in those slots due to half-duplex operation. UE-B uses the conflicting resources to determine which resources to reselect and excludes the conflicting resources from the reselected resources. In the second IUC scheme, the PSFCH is used to transmit the IUC.

[0074] FIG. 1E shows an example of IUC information MAC CE in a first IUC scheme in which some embodiments of the present disclosure may be implemented. The IUC information MAC CE is identified by a MAC subheader with an LCID as specified in Table 6.2.4-1. The priority of the IUC information MAC CE is fixed to "1". The size is variable and includes RT (resource set type, i.e., preferred or non-preferred resource set), RSL (reference slot position), LSI i (Lowest subchannel index of the first resource position of each TRIV), RC i (resource combination), first resource position i-1 (first resource position) and R (reserved bit) fields.

[0075] 1F shows an example of an IUC Request MAC CE in a first IUC scheme in which some embodiments of the present disclosure may be implemented. The IUC Request MAC CE is identified by a MAC subheader with an LCID as specified in Table 6.2.4-1. The priority of the IUC Request MAC CE is fixed at "1". It is of variable size and includes the following fields: RT (resource set type, i.e., preferred or non-preferred resource set), RP (resource reservation period), priority, RSWL (resource selection window position), number of subchannels (number of subchannels), and R (reserved bit).

[0076] As mentioned above, in RAN2#119bis-e, it was agreed that SL-U will support a consistent LBT failure detection procedure. The SL-specific consistent LBT failure detection (and recovery procedure) is device-centric and therefore affects any procedure where two or more devices interact. For example, SL-specific consistent LBT failures may affect the HARQ feedback procedure, which can be illustrated by the following use case:

[0077] In use case (a), a Tx UE experiences consistent LBT failures on specific RB sets (or resource pools), resulting in the loss of access to those specific RB sets (or resource pools). In sub-use case (ai), an Rx UE experiences consistent LBT failures on the same RB sets (or resource pools) as a Tx UE. In sub-use case (a.ii), an Rx UE does not experience consistent LBT failures on the same RB sets (or resource pools) as a Tx UE.

[0078] In use case (b), the Tx UE does not experience consistent LBT failures in a particular RB set (or resource pool) and can access the resources of that RB set (or resource pool). For example, it successfully performs Type 1 or Type 2 LBT (depending on whether COT is enabled) and transmits a PSCCH / PSSCH transmission for which the associated SCI requests HARQ feedback via the PSFCH resources mapped to the PSCCH / PSSCH. In sub-use case (bi), the Rx UE does not experience consistent LBT failures in the RB set (or resource pool) to which the PSFCH is mapped and can provide HARQ feedback using the mapped PSFCH resources. In sub-use case (b.ii), the Rx UE experiences consistent LBT failures in the RB set (or resource pool) to which the PSFCH is mapped and therefore cannot access the mapped PSFCH resources and cannot provide HARQ feedback.

[0079] From these use cases, it can be seen that whenever use case (b.ii) occurs, the Tx UE cannot determine whether to perform HARQ retransmission, and therefore communication reliability cannot be guaranteed. This disclosure provides a solution for dealing with the consistent LBT failure scenario, which will be described in conjunction with Figures 2 to 8.

[0080] 2 is a flowchart illustrating a communication process 200 in one embodiment of the present disclosure. For purposes of explanation, the communication process 200 is described with reference to FIG. 1A. Although the communication process 200 is described with reference to the network environment 100 of FIG. 1A, it should be understood that the communication process 200 is equally applicable to other similar communication scenarios.

[0081] In the communication process 200, the first terminal device 120-1 determines that a consistent (LBT) failure has been detected in a set of sidelink resources (202). The first terminal device 120-1 transmits information 206 related to the consistent LBT failure to at least one of the second terminal device 120-2 or the network device 110.

[0082] In some embodiments, the first terminal device 120-1 transmits (204) information 206 related to the consistent LBT failures to the network device 110. The network device receives (208) the information 206 from the first terminal device 120-1 and transmits (210) second information 212 determined based on the information 206 to the second terminal device 120-2. The second terminal device 120-2 receives (214) the second information 212 from the network device 110. The second terminal device 120-2 transmits (220) at least one sidelink transmission 222 on at least one sidelink resource determined based on the received second information 212.

[0083] Alternatively or additionally, the first terminal device 120-1 transmits (216) information 206 related to the consistent LBT failures to the second terminal device 120-2. The second terminal device 120-2 receives (218) the information 206 from the first terminal device 120-1. The second terminal device 120-2 transmits (220) at least one sidelink transmission 222 on at least one sidelink resource determined based on the received information 206.

[0084] In some embodiments, the information 206 may include information indicating that consistent LBT failures have been detected on a set of sidelink resources. That is, the second terminal device 120-2 or the network device 110 receiving the information 206 recognizes that consistent LBT failures have occurred on the first terminal device 120-1. Alternatively or additionally, the information 206 may include information indicating the duration of the consistent LBT failures. That is, the second terminal device 120-2 or the network device 110 receiving the information 206 can recognize how long the consistent LBT failures have lasted on the first terminal device 120-1. Alternatively or additionally, the information 206 may include notification of a set of sidelink resources. That is, the second terminal device 120-2 or the network device 110 receiving the information 206 recognizes the sidelink resources on which the consistent LBT failures occur.

[0085] In some demonstrative embodiments, the set of sidelink resources includes at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources includes at least one resource pool. Alternatively or additionally, the set of sidelink resources includes at least one bandwidth portion (BWP).

[0086] In some embodiments, the first terminal device 120-1 transmits information 206 to the network device 110 based on determining that the first terminal device 120-1 is within the coverage of the network device 110. In some embodiments, the network device 110 transmits second information 212 to the second terminal device 120-2 based on determining that the second terminal device 120-2 is within the coverage of the network device 110.

[0087] In some embodiments, the second information 212 may include information indicating that consistent LBT failures have been detected on a set of sidelink resources. Alternatively or additionally, the second information 212 may include information indicating the duration of the consistent LBT failures. Alternatively or additionally, the second information 212 may include information indicating the set of sidelink resources. In other words, the network device 110 forwards the contents of the information 206 to the second terminal device 120-2. In some embodiments, the network device 110 transmits the second information 212 to the second terminal device 120-2 based on determining that the second terminal device 120-2 is in the second resource allocation mode. In this way, the second terminal device 120-2 is aware of information related to the consistent LBT failures occurring in the first terminal device 120-1 and can therefore determine at least one sidelink resource for at least one sidelink transmission 222.

[0088] In some demonstrative embodiments, the second information 212 includes an indication of at least one sidelink resource allocated for at least one sidelink transmission 222 from the second terminal device 120-2 to the first terminal device 120-1. In some demonstrative embodiments, based on determining that the second terminal device 120-2 is in the first resource allocation mode prior to receiving the second information 212 from the network device 110, the second terminal device 120-2 transmits a request to the network device 110 for allocation of resources for the at least one sidelink transmission 222. Upon receiving the request, the network device 110 determines the at least one sidelink resource allocated for the at least one sidelink transmission 222.

[0089] In some embodiments, the first terminal device 120-1 transmits information 206 to the second terminal device 120-2 based on determining that the first terminal device 120-1 is outside the coverage of the network device 110. In other words, the first terminal device 120-1 transmits information 206 to the second terminal device 120-2 when the first terminal device 120-1 is outside the network's control. In some embodiments, the first terminal device 120-1 transmits information 206 to the second terminal device 120-2 when the first terminal device 120-1 is within the coverage of the network device 110. In other words, the first terminal device 120-1 always transmits information 206 to the second terminal device 120-2, regardless of whether it is under network control or not. In this manner, the second terminal device 120-2 can recognize information about consistent LBT failures occurring in the first terminal device 120-1, thereby determining at least one sidelink resource for at least one sidelink transmission 222.

[0090] In some demonstrative embodiments, when transmitting information 206 to the second terminal device 120-2, the first terminal device 120-1 transmits an IUC message including the information based on determining that an IUC exists between the first terminal device 120-1 and the second terminal device 120-2. In some embodiments, the IUC message may include a notification of non-preferred resources, including the set of sidelink resources. Alternatively, or additionally, the IUC message may include a notification of recommended resources excluding the set of sidelink resources.

[0091] In some embodiments, when transmitting the information 206 to the second terminal device 120-2, the first terminal device 120-1 transmits a PC5 radio resource control (PC5-RRC) UE assistance information (UAI) including information based on determining that an IUC does not exist between the first terminal device 120-1 and the second terminal device 120-2. Alternatively, or additionally, the first terminal device 120-1 transmits a medium access control (MAC) control element (CE) including information based on determining that an IUC does not exist between the first terminal device 120-1 and the second terminal device 120-2. For example, the first terminal device 120-1 transmits a PC5-RRC including the information based on determining that a unicast link is established between the first terminal device 120-1 and the second terminal device 120-2. Alternatively or additionally, the first terminal device 120-1 may transmit a MAC CE including the information based on determining that a unicast link has been established between the first terminal device 120-1 and the second terminal device 120-2. Alternatively or additionally, the first terminal device 120-1 may transmit a MAC CE including the information based on determining that a groupcast link has been established between the first terminal device 120-1 and the second terminal device 120-2.

[0092] In some embodiments, the set of sidelink resources may be a first resource pool, and the information 206 may be transmitted to a second terminal device 120-2 that belongs to a second resource pool different from the first resource pool, and the information 206 may include an indication of the first resource pool.

[0093] In some embodiments, the at least one sidelink resource determined by the second terminal device 120-2 or assigned by the network device 110 is mapped to at least one PSFCH resource different from the set of sidelink resources. In some embodiments, if the at least one sidelink resource was assigned by the network device 110, the second information 212 may include information indicating enabling HARQ feedback for at least one sidelink transmission 222 from the first terminal device 120-1 to the second terminal device 120-2. In some embodiments, the second terminal device 120-2 transmits a notification to the first terminal device 120-1 to enable HARQ feedback for the at least one sidelink transmission 222. In some embodiments, the first terminal device 120-1 receives 224 the at least one sidelink transmission 222 from the second terminal device 120-2 on at least one sidelink resource and transmits HARQ feedback to the second terminal device 120-2 for the at least one sidelink transmission.

[0094] In some embodiments, at least one sidelink resource determined by the second terminal device 120-2 or allocated by the network device 110 is mapped to at least one PSFCH resource in the set of sidelink resources. In some embodiments, if at least one sidelink resource is allocated by the network device 110, the second information 212 may include a notification of disabling HARQ feedback from the first terminal device 120-1 to the second terminal device 120-2 for at least one sidelink transmission 222. In some embodiments, the second terminal device 120-2 transmits a notification of disabling HARQ feedback for at least one sidelink transmission 222 to the first terminal device 120-1. In some embodiments, the first terminal device 120-1 receives 224 at least one sidelink transmission 222 from the second terminal device 120-2 on at least one sidelink resource and skips transmitting HARQ feedback to the second terminal device 120-2 for at least one sidelink transmission.

[0095] In some embodiments, the second terminal device 120-2 reduces the modulation and coding scheme (MCS) of the at least one sidelink transmission 222 when transmitting the at least one sidelink transmission 222 on at least one PSFCH resource in the set of sidelink resources mapped to the at least one sidelink resource. Alternatively or additionally, the second terminal device 120-2 enables repetition of the at least one sidelink transmission 222. In some embodiments, the second information 212 includes a notification indicating a reduction in the MCS of the at least one sidelink transmission 222. Alternatively or additionally, the second information 212 includes a notification indicating a repetition of the at least one sidelink transmission.

[0096] Through process flow 200, the second terminal device 120-2 can recognize information related to consistent LBT failures on the first terminal device 120-1, thereby enabling the second terminal device 120-2 to respond to consistent LBT failures during sidelink transmissions to the first terminal device 120-1.

[0097] For example, the second terminal device 120-2 may transmit a sidelink transmission to the first terminal device 120-1 on a resource mapped to at least one PSFCH resource for which the first terminal device 120-1 has not experienced consistent LBT failures. In such a case, the second terminal device 120-2 may provide HARQ feedback using the mapped PSFCH resource, and the first terminal device 120-1 may determine whether to perform a HARQ retransmission.

[0098] Alternatively, the second terminal device 120-2 transmits sidelink transmissions to the first terminal device 120-1 on resources mapped to at least one PSFCH resource for which the first terminal device 120-1 has not experienced consistent LBT failures. In such a case, the second terminal device 120-2 does not need to request HARQ feedback from the first terminal device 120-1, and the second terminal device 120-2 can improve the reception probability by, for example, reducing the MCS of the sidelink transmission or enabling repetition to improve the robustness of the transmission.

[0099] In other words, the second terminal device 120-2 may be able to respond to the lack of HARQ feedback by considering whether the first terminal device 120-1 experiences consistent LBT failures in the target RB set (or resource pool), thereby improving the reliability of sidelink communication even under consistent LBT failure conditions.

[0100] 3 shows a flowchart illustrating a procedure 300 for operation of the first terminal device 120-1 in different cases, according to one embodiment of the present disclosure. For illustrative purposes, the embodiment of FIG. 3 will be described with reference to FIG. 1A.

[0101] As an example, in procedure 300, Rx UE 120-1 may experience and report consistent LBT failures at 301. For example, if consistent LBT failures are experienced, Rx UE 120-1 may indicate to its peers that it is experiencing consistent LBT failures. At 302, it is determined whether Rx UE 120-1 is within the coverage of gNB 110. If Rx UE 120-1 is outside the coverage of gNB 110 (NO at 302), procedure 300 proceeds to block 303, where Rx UE 120-1 notifies Tx UE 120-2 that consistent LBT failures have occurred. At 303, it is determined whether an IUC exists between Rx UE 120-1 and Tx-UE 120-2. If an IUC does not exist between Rx UE 120-1 and Tx-UE 120-2 (NO at 303), procedure 300 may proceed to block 304. At 304, it is determined whether a unicast or broadcast link is established between Rx UE 120-1 and Tx-UE 120-2.

[0102] In some embodiments, if a unicast link is established between Rx UE 120-1 and Tx-UE 120-2, procedure 300 proceeds to block 305. In block 305, Rx UE 120-1 notifies Tx UE 120-2 of the consistent LBT failure status and its duration occurring in a specific RB via a PC5-RRC UAI or MAC CE. That is, if Rx UE 120-1 is in a non-network-controlled configuration (i.e., out of coverage and using Mode 2) and there is no inter-UE coordination, Rx UE 120-1 may notify Tx UE 120-2 via a PC5-RRC UAI message or MAC CE in unicast that consistent LBT failures have occurred in a specific RB set (and resource pool) and their duration (or estimated duration). The MAC CE may be transmitted, for example, outside the affected RB set and may occur in a different resource pool. If a consistent LBT failure is declared at the resource pool level, we assume that in the context of the SL-U MAC specification, the restriction that the MAC CE must be transmitted in the same resource pool is relaxed. In other words, this MAC CE must contain information specifying the resource pool to which the information in the MAC CE relates.

[0103] In some demonstrative embodiments, if a groupcast link is established between Rx UE 120-1 and Tx UE 120-2, procedure 300 may proceed to block 306. In block 306, Rx UE 120-1 may use MAC-CE to notify Tx UE 120-2 of consistent LBT failures occurring in a particular RB and their duration. In other words, when Rx UE 120-1 is in a non-network-controlled configuration (i.e., out of coverage and using Mode 2) and there is no inter-UE coordination, Rx UE 120-1 uses MAC-CE to notify Tx UE 120-2 in groupcast that consistent LBT failures are occurring in a particular RB set (and resource pool) and their duration (or an estimate of the duration). The MAC-CE may be transmitted, for example, outside the affected RB set (potentially in a different resource pool). As in the unicast case, if a consistent LBT failure is declared at the resource pool level, then in the context of the SL-U MAC specification, the restriction that a MAC CE must be transmitted on the same resource pool may be relaxed. In other words, this MAC CE must contain information specifying the resource pool to which the information in the MAC CE relates.

[0104] In some embodiments, if IUC exists between Rx UE 120-1 and Tx-UE 120-2 (YES in 303), procedure 300 proceeds to block 307. In 307, Rx UE 120-1 uses an IUC message to indicate a preferred or non-preferred RB set to prevent Rx UE 120-1 from experiencing consistent LBT failures. In other words, in a non-network-controlled environment where Rx UE 120-1 uses IUC (i.e., when using Mode 2 out of coverage and implementing inter-UE cooperation), if Rx UE 120-1 plays the role of UE-A in the IUC framework, Rx UE 120-1 can indicate all RB sets that are currently experiencing consistent LBT failures as non-preferred resources. Alternatively, Rx UE 120-1 can indicate all RB sets that are not currently experiencing consistent LBT failures as preferred resources.

[0105] In some example embodiments, the IUC message exchange may be performed on resources for which consistent LBT failures are not declared, and the IUC message may indicate an RB set as a non-prioritized PSCCH / PSSCH resource, as a resource associated with a PSFCH that belongs to an RB set for which consistent LBT failures are being performed.

[0106] In some example embodiments, if a consistent LBT failure is declared at the resource pool level, the IUC framework is extended to assume that transmission is possible on resource pools other than the resource pool associated with the non-preferred resources. In other words, an IUC message associated with resource pool A may be transmitted using resources of resource pool B. The implication of this extension is that an IUC message must include the resource pool ID associated with its payload.

[0107] In some embodiments, if Rx UE 120-1 is within the coverage of gNB 110 (YES at 302), procedure 300 may proceed to block 308. At 308, Rx UE 120-1 sends a consistent LBT failure notification to gNB 110 (e.g., via an RRC message or a MAC CE in a PUSCH). At 309, it may be determined whether Tx-UE 120-2 is within the coverage of gNB 110. If Tx-UE 120-2 is within the coverage of gNB 110 (YES at 309), it may be determined at 310 whether Tx-UE 120-2 is in mode 1 or mode 2. If Tx-UE 120-2 is in mode 2, gNB 110 may forward the notification received from Rx UE 120-1 to Tx-UE 120-2.

[0108] In other words, in an environment where Tx UE 120-2 is not NW controlled, if Rx UE 120-1 and Tx UE 120-2 are both in coverage but Tx UE 120-2 is using mode 2, when Rx UE 120-1 detects a consistent LBT failure, it may send a notification of the consistent LBT failure to gNB 110 (e.g., via an RRC message or MAC-CE in a PUSCH), and then gNB 110 may forward the notification to Tx UE 120-2.

[0109] Alternatively or additionally, if Rx UE 120-1 is in NW coverage, Rx UE 120-1 may send the notification directly to Tx UE 120-2. In some exemplary embodiments, the embodiments in which Rx UE 120-1 is out of coverage in a non-NW controlled setting are also applicable to embodiments in which Rx UE 120-1 is in coverage. This is particularly useful when only Rx UE 120-1 is in NW coverage while Tx UEs are out of NW coverage (i.e., NO at 309).

[0110] In some embodiments, when Tx-UE 120-2 is in mode 1, in response to a resource request from Tx UE 120-2 at 312, gNB 110 allocates PSSCH / PSCCH resources mapped to PSFCH resources for which Rx UE 120-1 has not experienced consistent LBT failures. Alternatively, gNB 110 may indicate that HARQ feedback will be disabled for PSSCH / PSCCH resources mapped to PSFCH resources for which Rx UE 120-1 has experienced consistent LBT failures.

[0111] In other words, when Tx-UE 120-2 is in a NW-controlled environment (i.e., within NW coverage and using Mode 1), in unicast and groupcast, when Tx UE 120-2 requests resources for transmission to Rx UE 120-1, gNB 110 (if it receives notification of consistent LBT failure from Rx UE 120-1) may allocate resources mapped to PSFCH positions where Rx UE 120-1 has not experienced consistent LBT failure. Alternatively or additionally, gNB 110 may disable HARQ feedback for transmissions allocated to resources mapped to PSFCH positions affected by consistent LBT failure.

[0112] In some embodiments, Rx UE 120-1 may send a notification of the experienced consistent LBT failure to gNB 110 via the Uu interface (e.g., an RRC message or a MAC-CE in a PUSCH). Alternatively, Rx UE 120-1 may notify Tx UE 120-2 of the occurrence of the consistent LBT failure via an SL resource (e.g., an RB set or a resource pool) on which the consistent LBT failure has not occurred.

[0113] From the perspective of Tx UE 120-2, if it obtains information that a consistent LBT failure has occurred in RX UE 120-1, Tx UE 120-2 may send a sidelink transmission to Rx UE 120-1 based on the obtained information.

[0114] In some demonstrative embodiments, when Tx UE 120-2 is in a non-NW control mode (i.e., mode 2) or when Rx UE 120-1 is out of NW coverage, Tx UE 120-2 may determine PSCCH / PSSCH resources that are mapped to a PSFCH located within an RB set (or resource pool) that is affected by consistent LBT failures. In some embodiments, Tx UE 120-2 may exclude the determined PSCCH / PSSCH resources from the resource selection procedure. That is, Tx UE 120-2 does not use these determined PSCCH / PSSCH resources for transmission, otherwise it would be unable to determine whether Rx UE 120-1 received the transmission.

[0115] In some demonstrative embodiments, Tx UE 120-2 may disable HARQ feedback when using the determined PSCCH / PSSCH resources. Additionally, Tx UE 120-2 may improve transmission robustness and increase reception probability by, for example, lowering the MCS or enabling repetitions in transmissions to Rx UE 120-1.

[0116] In some embodiments, when Tx UE 120-2 is in the NW-controlled mode (i.e., mode 1), Tx UE 120-2 may follow the resource allocation provided by gNB 110. For example, Tx UE 120-2 utilizes the resources allocated by gNB 110 (mapped to PSFCH locations where Rx UE 110 has not experienced consistent LBT failures) for sidelink transmissions to Rx UE 110. Because Rx UE 110 has not experienced consistent LBT failures at the mapped PSFCH locations, Rx UE 110 provides HARQ feedback to Tx UE 120-2, allowing Tx UE 120-2 to know whether HARQ retransmissions are necessary. Alternatively, based on the notification received from gNB110, Tx UE120-2 may disable HARQ feedback for transmissions on resources assigned to PSFCH positions that are subject to consistent LBT failures and improve the robustness of transmissions, e.g., by lowering the MCS or enabling repetitions for transmissions to its RX UEs, thereby improving reception probability.

[0117] In other words, Tx UE 120-2 may be able to respond to the lack of HARQ feedback by considering whether Rx UE 120-1 is experiencing consistent LBT failures in the target RB set (or resource pool), thereby improving the reliability of sidelink communication even under consistent LBT failure conditions.

[0118] 4 illustrates a flowchart of an exemplary method 400 implemented at a first terminal device in accordance with one embodiment of the present disclosure. For illustrative purposes, the method 400 will be described from the perspective of the first terminal device 120 with reference to FIG. 1A.

[0119] In block 410, the first terminal device 120-1 determines that consistent LBT failures have been detected on the set of sidelink resources. In block 420, the first terminal device 120-1 transmits information about the consistent LBT failures to the network device 110. Alternatively or additionally, the first terminal device 120-1 transmits information about the consistent LBT failures to the second terminal device 120-2.

[0120] In some embodiments, the first terminal device 120-1 may transmit information to the second terminal device 120-2 based on determining that the first terminal device 120-1 is out of coverage of the network device 110. In some embodiments, the first terminal device 120-1 may transmit an IUC message including information based on determining that an IUC exists between the first terminal device 120-1 and the second terminal device 120-2. In some embodiments, the information includes an indication of non-preferred resources, including the set of sidelink resources. Alternatively or additionally, the information may include an indication of preferred resources excluding the set of sidelink resources.

[0121] In some exemplary embodiments, based on determining that an IUC does not exist between the first terminal device 120-1 and the second terminal device 120-2, the first terminal device 120-1 may transmit a PC5-RRC UAI including the information. Alternatively, or additionally, based on determining that an IUC does not exist between the first terminal device 120-1 and the second terminal device 120-2, the first terminal device 120-1 may transmit a MAC CE including the information.

[0122] In some embodiments, the first terminal device 120-1 may transmit a PC5-RRC UAI based on determining that a unicast link has been established between the first terminal device 120-1 and the second terminal device 120-2. Alternatively, or additionally, the first terminal device 120-1 may transmit a MAC CE based on determining that a unicast link has been established between the first terminal device 120-1 and the second terminal device 120-2. In some exemplary embodiments, the first terminal device 120-1 may transmit a MAC CE based on determining that a group link has been established between the first terminal device 120-1 and the second terminal device 120-2.

[0123] In some demonstrative embodiments, the set of sidelink resources may be a first resource pool, and the information is transmitted to the second terminal device 120-2 via a second resource pool different from the first resource pool, the information including an indication of the first resource pool.

[0124] In some embodiments, first terminal device 120-1 may transmit information to network device 110 based on determining that first terminal device 120-1 is within the coverage of network device 110.

[0125] In some embodiments, the information may include information indicating that consistent LBT failures have been detected on a set of sidelink resources. Alternatively or additionally, the information may include information indicating a duration of the consistent LBT failures. Alternatively or additionally, the information may include information indicating the set of sidelink resources.

[0126] In some demonstrative embodiments, the first terminal device 120-1 may receive, from the second terminal device 120-2, at least one sidelink transmission on at least one sidelink resource determined based on the information.

[0127] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource that is different from the set of sidelink resources. The first terminal device 120-1 may further transmit HARQ feedback for the at least one sidelink transmission to the second terminal device 120-2.

[0128] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource in the set of sidelink resources. The first terminal device 120-1 may receive from the second terminal device 120-2 a notification to disable HARQ feedback from the first terminal device 120-1 to the second terminal device 120-2 for at least one sidelink transmission.

[0129] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources may include at least one resource pool. Alternatively or additionally, the set of sidelink resources may include at least one bandwidth portion.

[0130] 5 shows another flowchart of an exemplary method 500 implemented in a network device according to one embodiment of the present disclosure. For illustrative purposes, the method 500 will be described from the perspective of the second terminal device 120-2 with reference to FIG. 1A.

[0131] At block 510, the second terminal device 120-2 may receive information related to consistent LBT failures detected by the first terminal device 120-1 on a set of sidelink resources. At block 520, the second terminal device 120-2 may transmit at least one sidelink transmission to the first terminal device 120-1 on at least one sidelink resource determined based on the received information.

[0132] In some embodiments, the information may include a notification indicating that a consistent LBT failure has been detected on a set of sidelink resources. Alternatively or additionally, the information may include a notification indicating a duration of the consistent LBT failure. Alternatively or additionally, the information may include a notification of the set of sidelink resources. Alternatively or additionally, the information may include a notification of non-recommended resources that include the set of sidelink resources. Alternatively or additionally, the information may include a notification of recommended resources excluding the set of sidelink resources.

[0133] In some demonstrative embodiments, the information may be received from first terminal device 120-1. Alternatively, or additionally, the information may be received from network device 110. In some embodiments, the information may be received from network device 110 if first terminal device 120-1 and second terminal device 120-2 are within the coverage of network device 110. In some embodiments, the information may be received from first terminal device 120-1 if at least one of first terminal device 120-1 and second terminal device 120-2 is outside the coverage of network device 110.

[0134] In some embodiments, the information may be received from the first terminal device 120-1 via a PC5-RRC UAI. Alternatively or additionally, the information may be received from the first terminal device 120-1 via a MAC CE. Alternatively or additionally, the information may be received from the first terminal device 120-1 via an IUC message.

[0135] In some embodiments, the information may include an indication of at least one sidelink resource and may be received from the network device 110. In some embodiments, based on determining that the second terminal device 120-2 is in the first resource allocation mode, the second terminal device 120-2 may request a resource allocation for at least one sidelink transmission from the network device 110 before receiving the information from the network device 110.

[0136] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource that is different from the set of sidelink resources. The second terminal device 120-2 may further transmit a notification to the first terminal device 120-1 indicating that HARQ feedback is enabled for at least one sidelink transmission from the first terminal device 120-1 to the second terminal device 120-2.

[0137] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource in the set of sidelink resources. The second terminal device 120-2 may further transmit a notification to the first terminal device 120-1 to disable HARQ feedback from the first terminal device 120-1 to the second terminal device 120-2 for at least one sidelink transmission.

[0138] In some embodiments, the second terminal device 120-2 may be configured to transmit at least one sidelink transmission by reducing the modulation and coding scheme (MCS) of the at least one sidelink transmission. Alternatively or additionally, the second terminal device 120-2 may be configured to transmit at least one sidelink transmission by enabling repetition of the at least one sidelink transmission.

[0139] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources may include at least one resource pool. Alternatively or additionally, the set of sidelink resources may include at least one bandwidth portion.

[0140] In some demonstrative embodiments, the set of sidelink resources may be a first resource pool, and the information may be received from the first terminal device 120-1 on a second resource pool different from the first resource pool, and the information may include an indication of the first resource pool.

[0141] 6 shows another flowchart of an example method 600 implemented in a network device in accordance with some embodiments of the present disclosure. For purposes of explanation, the method 600 will be described from the perspective of the network device 110 with reference to FIG. 1A.

[0142] In block 610, the network device 110 may receive, from the first terminal device 120-1, first information related to consistent LBT failures detected by the first terminal device 120-1 on a set of sidelink resources. In block 620, the network device 110 may transmit, to the second terminal device 120-2, second information determined based on the first information.

[0143] In some embodiments, the information may include information indicating that consistent LBT failures have been detected on a set of sidelink resources. Alternatively or additionally, the information may include information indicating a duration of the consistent LBT failures. Alternatively or additionally, the information may include information indicating the set of sidelink resources.

[0144] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources may include at least one resource pool. Alternatively or additionally, the set of sidelink resources may include at least one bandwidth portion. In some embodiments, the first information may be received from the first terminal device 120-1 if the first terminal device 120-1 is within the coverage of the network device 110.

[0145] In some embodiments, when transmitting the second information to the second terminal device 120-2, the network device 110 may transmit the second information to the second terminal device 120-2 based on determining that the second terminal device 120-2 is within the coverage of the network device 110.

[0146] In some embodiments, the second information may include a notification indicating that a consistent LBT failure has been detected on a set of sidelink resources. Alternatively or additionally, the second information may include a notification indicating a duration of the consistent LBT failure. Alternatively or additionally, the second information may include a notification indicating a set of sidelink resources.

[0147] In some embodiments, the network device 110 may transmit the second information to the second terminal device 120-2 based on determining that the second terminal device 120-2 is in the second resource allocation mode.

[0148] In some embodiments, the second information may include information indicating at least one sidelink resource allocated for at least one sidelink transmission to be transmitted from the second terminal device 120-2 to the first terminal device 120-1. In some embodiments, when receiving a resource request for the transmission of at least one sidelink transmission, the network device 110 may determine the at least one sidelink resource allocated for the at least one sidelink transmission. In some embodiments, the at least one sidelink resource may be mapped to at least one PSFCH resource different from the set of sidelink resources.

[0149] In some embodiments, at least one sidelink resource is mapped to at least one PSFCH resource in the set of sidelink resources, and the second information may further comprise a notification of disabling HARQ feedback from the first terminal device 120-1 to the second terminal device 120-2 for at least one sidelink transmission. In some embodiments, the second information may further comprise a notification indicating that the MCS of at least one sidelink transmission has been reduced. Alternatively or additionally, the second information may comprise a notification indicating a repetition of at least one sidelink transmission.

[0150] In some embodiments, an apparatus capable of executing method 400 (e.g., first terminal device 120) may comprise means for performing each step of method 400. The means may be implemented in any suitable form, for example, as a circuit or a software module.

[0151] In some embodiments, the apparatus may comprise means for determining that consistent Listen-Before-Talk (LBT) failures on a set of sidelink resources have been detected, and means for transmitting information related to the consistent LBT failures to at least one of a second terminal device or a network device.

[0152] In some embodiments, the means for transmitting the information to the second terminal device may comprise means for transmitting the information to the second terminal device based on determining that the first terminal device is out of coverage of the network device. In some embodiments, the device may further comprise means for transmitting an IUC message including the information based on determining that an IUC exists between the first terminal device and the second terminal device.

[0153] In some embodiments, the information may include indication of non-preferred resources including the set of sidelink resources. Alternatively or additionally, the information may include indication of preferred resources excluding the set of sidelink resources.

[0154] In some examples, the apparatus may further comprise means for transmitting at least one of a PC5-RRC UAI or a MAC CE, where at least one of the PC5-RRC UAI or the MAC CE may include the information. In some exemplary embodiments, the apparatus may further comprise means for transmitting at least one of a PC5-RRC UAI or a MAC CE based on determining that a unicast link has been established between the first terminal device and the second terminal device. In some exemplary embodiments, the apparatus may further comprise means for transmitting a MAC CE based on determining that a groupcast link has been established between the first terminal device and the second terminal device.

[0155] In some example embodiments, the set of sidelink resources may be a first resource pool, and the means for transmitting the information may include means for transmitting the information to the second terminal device in a second resource pool different from the first resource pool, the information including an indication of the first resource pool.

[0156] In some embodiments, the means for transmitting information to the network device may comprise means for transmitting information to the network device based on determining that the first terminal device is within coverage of the network device.

[0157] In some embodiments, the information may include a notification indicating that a consistent LBT failure has been detected on a set of sidelink resources. Alternatively or additionally, the information may include a notification indicating the duration of the consistent LBT failure. Alternatively or additionally, the information may include a notification indicating the set of sidelink resources.

[0158] In some embodiments, the apparatus may further comprise means for receiving, from the second terminal device, at least one sidelink transmission on at least one sidelink resource determined based on the information. In some embodiments, the at least one sidelink resource may be mapped to at least one PSFCH resource different from the set of sidelink resources. The apparatus may further comprise means for transmitting HARQ feedback for the at least one sidelink transmission to the second terminal device.

[0159] In some example embodiments, the at least one sidelink resource may be mapped to at least one PSFCH resource in the set of sidelink resources. The apparatus may further comprise means for receiving, from the second terminal device, a notification of disabling HARQ feedback from the first terminal device to the second terminal device for the at least one sidelink transmission.

[0160] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources may include at least one resource pool. Alternatively or additionally, the set of sidelink resources may include at least one bandwidth portion.

[0161] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of method 400. In some embodiments, the means may include at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code configured to cause the at least one processor to perform the operations of the apparatus.

[0162] In some embodiments, an apparatus capable of executing method 500 (e.g., second terminal device 120-2) may comprise means for performing each step of method 500. The means may be implemented in any suitable form. For example, the means may be implemented as a circuit or a software module.

[0163] In some embodiments, the apparatus may comprise: means for receiving information regarding consistent listen-before-talk (LBT) failures detected on a set of sidelink resources by a first terminal device; and means for sending, to the first terminal device, at least one sidelink transmission on at least one sidelink resource based on the received information.

[0164] In some embodiments, the information may include a notification indicating that a consistent LBT failure has been detected on a set of sidelink resources. Alternatively or additionally, the information may include a notification indicating a duration of the consistent LBT failure. Alternatively or additionally, the information may include a notification of the set of sidelink resources. Alternatively or additionally, the information may include a notification of non-recommended resources that include the set of sidelink resources. Alternatively or additionally, the information may include a notification of recommended resources excluding the set of sidelink resources.

[0165] In some embodiments, the means for receiving information may comprise means for receiving information from at least one of a first terminal device or a network device. In some embodiments, the means for receiving information from a network device may comprise means for receiving information from the network device when the first terminal device and the second terminal device are within coverage of the network device. In some embodiments, the means for receiving information from the first terminal device may comprise means for receiving information from the first terminal device when at least one of the first terminal device and the second terminal device is outside coverage of the network device.

[0166] In some embodiments, the means for receiving information from the first terminal device may comprise means for receiving information from the first terminal device via at least one of a PC5-RRC UAI, a MAC CE, or an IUC message.

[0167] In some embodiments, the information may include notification of at least one sidelink resource, and the means for receiving the information may comprise means for receiving the information from the network device. In some embodiments, the apparatus may further comprise means for, based on determining that the second terminal device is in the first resource allocation mode, transmitting a signal to the network device requesting allocation of at least one resource for sidelink transmission before receiving the information from the network device.

[0168] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource different from the set of sidelink resources. The apparatus may further comprise means for transmitting a notification to the first terminal device, indicating enabling HARQ feedback from the first terminal device to the second terminal device for the at least one sidelink transmission.

[0169] In some embodiments, at least one sidelink resource may be mapped to at least one PSFCH resource in the set of sidelink resources, and the apparatus may further comprise means for transmitting a notification to the first terminal device disabling HARQ feedback from the first terminal device to the second terminal device for the at least one sidelink transmission.

[0170] In some embodiments, the means for transmitting at least one sidelink transmission may comprise means for transmitting the at least one sidelink transmission by at least one of reducing a modulation and coding scheme (MCS) of the at least one sidelink transmission or enabling repetition of the at least one sidelink transmission.

[0171] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set, at least one resource pool, or at least one bandwidth portion.

[0172] In some embodiments, the set of sidelink resources may be a first resource pool, and the means for receiving information may include means for receiving information from the first terminal device on a second resource pool different from the first resource pool, the information including an indication of the first resource pool.

[0173] In some exemplary embodiments, the apparatus may further comprise means for performing other steps in the exemplary embodiment of method 500. In some exemplary embodiments, the means may comprise at least one processor and at least one memory containing computer program code configured to cause the at least one processor to perform the operations of the apparatus.

[0174] In some exemplary embodiments, an apparatus capable of performing method 600 (e.g., network device 110) may comprise means for performing each step of method 600. The means may be implemented in any suitable form. For example, the means may be implemented as a circuit or a software module.

[0175] In some embodiments, the apparatus may comprise means for receiving, from a first terminal device, first information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources, and means for transmitting, to a second terminal device, second information determined based on the first information.

[0176] In some embodiments, the information may include a notification indicating that a consistent LBT failure has been detected on a set of sidelink resources. Alternatively or additionally, the information may include a notification indicating the duration of the consistent LBT failure. Alternatively or additionally, the information may include a notification indicating the set of sidelink resources.

[0177] In some embodiments, the set of sidelink resources may include at least one resource block (RB) set. Alternatively or additionally, the set of sidelink resources may include at least one resource pool. Alternatively or additionally, the set of sidelink resources may include at least one bandwidth portion. In some embodiments, the means for receiving the first information may comprise means for receiving the first information from the first terminal device when the first terminal device is within coverage of the network device.

[0178] In some demonstrative embodiments, the means for transmitting the second information to the second terminal device may comprise means for transmitting the second information to the second terminal device based on determining that the second terminal device is within coverage of the network device.

[0179] In some embodiments, the second information may include a notification indicating that consistent LBT failures have been detected on a set of sidelink resources. Alternatively or additionally, the second information may include a notification indicating the duration of the consistent LBT failures. Alternatively or additionally, the second information may include a notification indicating the set of sidelink resources.

[0180] In some embodiments, the means for transmitting the second information to the second terminal device may comprise means for transmitting the second information to the second terminal device based on determining that the second terminal device is in the second resource allocation mode.

[0181] In some embodiments, the second information may include information indicating at least one sidelink resource allocated to at least one sidelink transmission transmitted from the second terminal device to the first terminal device. In some embodiments, the apparatus may further comprise means for determining the at least one sidelink resource allocated to the at least one sidelink transmission based on receiving a resource request for the at least one sidelink transmission. In some embodiments, the at least one sidelink resource may be mapped to at least one PSFCH resource different from the set of sidelink resources.

[0182] In some exemplary embodiments, at least one sidelink resource is mapped to at least one PSFCH resource in the set of sidelink resources, and the second information may further comprise a notification of disabling HARQ feedback from the first terminal device to the second terminal device for at least one sidelink transmission. In some embodiments, the second information may further comprise a notification indicating that the MCS of the at least one sidelink transmission is degraded. Alternatively or additionally, the second information may further comprise a notification indicating a repetition of the at least one sidelink transmission.

[0183] In some example embodiments, the apparatus further includes means for performing other steps in example embodiments of method 600. In some example embodiments, the means includes at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code configured to cause the at least one processor to perform the operations of the apparatus.

[0184] 7 shows a simplified block diagram of an apparatus 700 suitable for implementing some embodiments of the present disclosure. The apparatus 700 may be provided to implement a communication apparatus such as the network apparatus 110, the first terminal device 120-1, or the second terminal device 120-2 shown in FIG. 1A. As shown in the figure, the apparatus 700 includes one or more processors 710, one or more memories 720 coupled to the processors 710, and one or more communication modules 740 coupled to the processors 710.

[0185] The communication module 740 is designed for two-way communication. The communication module 740 includes at least one antenna to enable communication. The communication interface can represent any interface required for communication with other network elements.

[0186] The processor 710 may be of any type suitable for a local technology network and may include one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture (as non-limiting examples). The device 700 may have multiple processors including application-specific integrated circuit chips time-synchronized with a clock that is synchronous with the main processor.

[0187] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memory include, but are not limited to, read-only memory (ROM) 724, electrically programmable read-only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), and other magnetic and / or optical storage devices. Examples of volatile memory include, but are not limited to, random access memory (RAM) 722 and other volatile memories that do not retain data during periods of power loss.

[0188] The computer program 730 includes computer-executable instructions that are executed by the associated processor 710. The program 730 may be stored in the ROM 724. The processor 710 can load the program 730 into the RAM 722 to perform appropriate operations and processes.

[0189] The embodiments of the present disclosure are realized by a program 730 that enables the device 700 to perform any of the processes of the present disclosure described with reference to Figure 2. The embodiments of the present disclosure may be realized by hardware or a combination of software and hardware.

[0190] In some demonstrative embodiments, the program 730 is physically stored on a computer-readable medium included in the device 700 (e.g., memory 720) or other storage accessible to the device 700. The device 700 loads the program 730 from the computer-readable medium into RAM 722 for execution. The computer-readable medium may include any type of tangible non-volatile storage device, such as a ROM, an EPROM, a flash memory, a hard disk, a CD, a DVD, etc.

[0191] 8 illustrates a block diagram of a computer-readable medium 1000 according to one embodiment of the present disclosure. The computer-readable medium 800 stores the program 730. Although the computer-readable medium 800 is shown in the form of a CD or DVD in FIG. 8, the computer-readable medium 800 may be in any other form suitable for storing or retaining the program 730.

[0192] In general, various embodiments of the present disclosure may be implemented in either hardware or special purpose circuits, software, logic, or a combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software executable by a controller, microprocessor, or other computing device. Although various aspects of embodiments of the present disclosure may be described and illustrated using block diagrams, flowcharts, or other graphical representations, the blocks, devices, systems, techniques, or methods described herein may be implemented as, by way of non-limiting example, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller, or other computing device, or a combination thereof.

[0193] The present disclosure also provides at least one computer program product physically stored on a non-transitory computer-readable recording medium. The computer program product includes computer-executable instructions, such as those included in program modules, that execute on a target real or virtual processor device to perform the methods 400, 500, or 600 described above with reference to Figures 4, 5, or 6. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or divided among program modules as desired in various embodiments. The machine-executable instructions for the program modules may be executed in local or distributed devices. In distributed devices, program modules may be located in both local and remote storage media.

[0194] Program code for implementing the methods of the present disclosure may be written in any combination of one or more programming languages. Such program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, and when executed by the processor or controller, may perform the functions / operations specified in the flowcharts and / or block diagrams. The program code may be executed entirely on the machine, on a portion of the machine, as a standalone software package, on a portion of the machine and a remote machine, or on a remote machine or server, or entirely on the remote machine or server.

[0195] In the context of the present disclosure, computer program code or associated data is transmitted by a suitable carrier to enable a device, apparatus, or processor to perform various processes and operations as described above. Examples of carriers include signals, computer-readable media, and the like.

[0196] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. Computer-readable media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the above. More specific examples of computer-readable storage media include an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. The term "non-transitory" as used herein refers to the medium itself (i.e., tangible, not a signal), and not to the permanence of data storage (e.g., RAM vs. ROM).

[0197] Furthermore, even if operations are shown in a particular order, they do not necessarily have to be performed in that order, or even that all of the shown operations need be performed. Multitasking or parallel processing may be advantageous to achieve desirable results. Similarly, while the above discussion includes details of several specific embodiments, these should not be construed as limiting the scope of the disclosure, but rather as descriptions of features specific to particular embodiments. Certain features described in separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0198] Although the present disclosure has been described in language specific to structural features and / or methodological acts, the present disclosure, as defined by the appended claims, is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first terminal device, at least one processor; When executed by the at least one processor, the method causes the first terminal device to determining that consistent listen-before-talk (LBT) failures are detected in a set of sidelink resources; sending information related to the consistent LBT failure to at least one of a second terminal device or a network device; at least one memory storing instructions for executing the A first terminal device comprising:

2. The first terminal device transmitting the information to the second terminal device based on determining that the first terminal device is outside the coverage of the network device; 2. The first terminal device according to claim 1, wherein the first terminal device is configured to transmit the information to the second terminal device by

3. The first terminal device further transmitting an Inter-UE Coordination (IUC) message including the information based on determining that Inter-UE Coordination (IUC) exists between the first terminal device and the second terminal device; The first terminal device according to claim 2 .

4. The information - signalling non-prioritised resources comprising said set of sidelink resources, or signaling preferred resources other than said set of sidelink resources; The first terminal device according to claim 3 , comprising at least one of:

5. The first terminal device further transmitting at least one of a PC5-Radio Resource Control (PC5-RRC) User Equipment Assistance Information (UAI) or a Medium Access Control (MAC) Control Element (CE) based on determining that an IUC does not exist between the first terminal device and the second terminal device, wherein the at least one of the PC5-RRC UAI or the MAC CE includes the information; 3. The first terminal device of claim 2, adapted to execute the following:

6. The first terminal device further transmitting at least one of the PC5-RRC UAI or the MAC CE based on determining that a unicast link has been established between the first terminal device and the second terminal device; The first terminal device according to claim 5 .

7. The first terminal device further transmitting the MAC CE based on the determination that a groupcast link has been established between the first terminal device and the second terminal device; The first terminal device according to claim 5 .

8. 8. The first terminal device according to claim 2, wherein the set of sidelink resources is a first resource pool, and the information is transmitted to the second terminal device in a second resource pool different from the first resource pool, and the information includes a notification of the first resource pool.

9. The first terminal device transmitting the information to the network device when determining that the first terminal device is within the coverage of the network device; 2. The first terminal device of claim 1, adapted to transmit said information to said network device by

10. The information is Indicating that the consistent LBT failures have been detected on the set of sidelink resources. Notification of the duration of the consistent LBT failure; or notification of said set of sidelink resources; 10. The first terminal device according to claim 5, further comprising at least one of:

11. The first terminal device further receiving, from the second terminal device, at least one sidelink transmission on at least one sidelink resource determined based on the information; 11. The first terminal device according to claim 1, wherein the first terminal device is configured to:

12. The at least one sidelink resource is mapped to at least one physical sidelink feedback channel (PSFCH) resource different from the set of sidelink resources, and the first terminal device further transmitting hybrid automatic repeat request (HARQ) feedback to the second terminal device for the at least one sidelink transmission. The first terminal device according to claim 11 .

13. The at least one sidelink resource is mapped to at least one PSFCH resource in the set of sidelink resources, and the first terminal device further receiving, from the second terminal device, a notification to disable HARQ feedback from the first terminal device to the second terminal device for the at least one sidelink transmission; The first terminal device according to claim 11 .

14. The set of sidelink resources comprises: at least one resource block (RB) set; At least one resource pool, or at least one bandwidth portion; 14. The first terminal device according to claim 1, comprising at least one of:

15. a second terminal device, at least one processor; When executed by the at least one processor, the method causes the second terminal device to receiving information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; transmitting to the first terminal device at least one sidelink transmission on at least one sidelink resource determined based on the received information; at least one memory storing instructions for executing the A second terminal device comprising:

16. The information is a notification that the consistent LBT failures have been detected on the set of sidelink resources; notification of the duration of said consistent LBT failures; notification of said set of sidelink resources; - signalling non-prioritised resources comprising said set of sidelink resources, or signaling preferred resources other than said set of sidelink resources; The second terminal device according to claim 15, comprising at least one of:

17. 17. The second terminal device according to claim 15 or 16, wherein the information is received from at least one of the first terminal device or a network device.

18. 18. The second terminal device of claim 17, wherein the information is received from the network device if the first terminal device and the second terminal device are within the coverage of the network device.

19. 18. The second terminal device of claim 17, wherein the information is received from the first terminal device when at least one of the first terminal device and the second terminal device is outside the coverage of the network device.

20. The information is transmitted from the first terminal device to: PC5 Radio Resource Control (PC5-RRC) User Equipment Support Information (UAI); a Medium Access Control (MAC) Control Element (CE), or Inter-UE Coordination (IUC) messages; 18. The second terminal device according to claim 17, wherein the signal is received via one of the following:

21. 16. The second terminal device of claim 15, wherein the information comprises a notification of the at least one sidelink resource, the information being received from a network device.

22. The second terminal device further transmitting, to the network device, a request to allocate resources for the at least one sidelink transmission based on determining that the second terminal device is in a first resource allocation mode before receiving the information from the network device. The second terminal device according to claim 21,

23. The at least one sidelink resource is mapped to at least one physical sidelink feedback channel (PSFCH) resource different from the set of sidelink resources, and the second terminal device further sending a notification to the first terminal device to enable Hybrid Automatic Repeat Request (HARQ) feedback from the first terminal device to the second terminal device for at least one sidelink transmission; 23. The second terminal device according to claim 15, wherein the second terminal device is adapted to:

24. The at least one sidelink resource is mapped to at least one PSFCH resource in the set of sidelink resources, and the second terminal device further sending, to the first terminal device, a notification to disable HARQ feedback from the first terminal device to the second terminal device for the at least one sidelink transmission; 23. The second terminal device according to claim 15, wherein the second terminal device is adapted to:

25. The second terminal device reducing a modulation and coding scheme (MCS) of the at least one sidelink transmission; or enabling repetition of the at least one sidelink transmission.

25. The second terminal device of claim 24, wherein the second terminal device is adapted to transmit the at least one sidelink transmission by at least one of:

26. The set of sidelink resources comprises: at least one resource block (RB) set; At least one resource pool, or at least one bandwidth portion; 26. The second terminal device according to claim 1, comprising at least one of:

27. 27. The second terminal device according to claim 1 , wherein the set of sidelink resources is a first resource pool, and the information is received from the first terminal device in a second resource pool different from the first resource pool, and the information includes a notification of the first resource pool.

28. A network device, at least one processor; When executed by the at least one processor, the network device is configured to: receiving, from a first terminal device, first information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; transmitting second information determined based on the first information to a second terminal device; at least one memory storing instructions for executing the A network device comprising:

29. The first information is Indicating that the consistent LBT failure has been detected on the set of sidelink resources. Notification of the duration of the consistent LBT failure; or notification of said set of sidelink resources; 30. The network device of claim 28, comprising at least one of:

30. The set of sidelink resources comprises: at least one resource block (RB) set; At least one resource pool, or at least one bandwidth portion; 30. A network device according to claim 28 or 29, comprising at least one of:

31. 31. A network device according to any one of claims 28 to 30, wherein the first information is received from the first terminal device if the first terminal device is within the coverage of the network device.

32. The network device comprises: transmitting the second information to the second terminal device based on determining that the second terminal device is within the coverage of the network device; 32. A network device according to any one of claims 28 to 31, adapted to transmit the second information to the second terminal device by

33. The second information is notification that the consistent LBT failures have been detected on the set of sidelink resources; Notification of the duration of the consistent LBT failure; or notification of said set of sidelink resources; 33. A network device according to any one of claims 28 to 32, comprising at least one of:

34. The network device comprises: transmitting the second information to the second terminal device based on determining that the second terminal device is in a second resource allocation mode; 34. The network device of claim 33, adapted to transmit the second information to the second terminal device by

35. 33. The network device of claim 28, wherein the second information comprises an indication of at least one sidelink resource allocated for at least one sidelink transmission to be sent from the second terminal device to the first terminal device.

36. The network device further comprises: determining the at least one sidelink resource allocated to the at least one sidelink transmission based on receiving a request for resources for transmitting the at least one sidelink transmission.

36. The network device of claim 35, wherein

37. 37. The network device of claim 35 or 36, wherein the at least one sidelink resource is mapped to at least one Physical Sidelink Feedback Channel (PSFCH) resource that is different from the set of sidelink resources.

38. the at least one sidelink resource is mapped to at least one PSFCH resource in the set of sidelink resources, and the second information further comprises: a notification from the first terminal device to the second terminal device of disabling Hybrid Automatic Repeat Request (HARQ) feedback for the at least one sidelink transmission; 37. A network device according to claim 35 or 36, comprising:

39. The second information further includes: - signalling a reduction in the modulation and coding scheme (MCS) of the at least one sidelink transmission; or signaling a repetition of the at least one sidelink transmission; 39. The network device of claim 38, comprising at least one of:

40. determining, at a first terminal device, that consistent listen-before-talk (LBT) failures in a set of sidelink resources are detected; sending information related to the consistent LBT failure to at least one of a second terminal device or a network device; A method comprising:

41. receiving, at a first terminal device, information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; transmitting to the first terminal device at least one sidelink transmission on at least one sidelink resource determined based on the received information; A method comprising:

42. receiving, in a network device, from a first terminal device, first information related to consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources; transmitting second information determined based on the first information to a second terminal device; A method comprising:

43. means for determining that consistent listen-before-talk (LBT) failures have been detected on a set of sidelink resources; means for transmitting information related to the consistent LBT failure to at least one of a second terminal device or a network device; An apparatus comprising:

44. means for receiving information related to consistent listen-before-talk (LBT) failures detected by the first terminal device on a set of sidelink resources; means for transmitting, to the first terminal device, at least one sidelink transmission on at least one sidelink resource determined based on the received information; An apparatus comprising:

45. means for receiving, from a first terminal device, first information related to consistent Listen-Before-Talk (LBT) failures detected by the first terminal device on a set of sidelink resources; means for transmitting second information determined based on the first information to a second terminal device; An apparatus comprising:

46. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform the method of any of claims 40 to 42.

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