Method and apparatus for handling consistent LBT faults

Abstract

The invention relates to a method and apparatus for handling consistent listen before talk (LBT) faults. Embodiments of the present disclosure provide a user equipment (UE) comprising: a transceiver; and a processor coupled with the transceiver and configured to: detect a consistent LBT failure on a set of resource blocks (RBs) of an SL bandwidth portion (BWP); executing one of the following operations: triggering a resource selection program; triggering a resource pool selection program; transmitting a first indication indicating the consistent LBT failure on the RB set; determining the set of RBs to be restored in response to one or more conditions being satisfied; or a consistent LBT failure is triggered or a SL BWP failure is declared for the SL BWP.

Description

Technical Field

[0001] The present disclosure relates to wireless transmissions, and more particularly to methods and apparatus for handling consistent listen-before-talk (LBT) failures. Background Art

[0002] In the new radio unlicensed (NRU) spectrum, a large number of unlicensed bands or channels are available for wireless transmission (e.g., WiFi, Bluetooth, 3G, 4G, etc.). The LBT procedure is performed before each transmission to determine whether the unlicensed band or channel is available. If LBT fails, which means that the channel is occupied, an LBT failure indication is sent from a lower layer (e.g., a physical (PHY) layer) to a media access control (MAC) entity. The MAC entity can then count the number of LBT failure indications from the lower layer within a certain time period, and when the number of LBT failure indications exceeds a threshold (e.g., a preconfigured maximum number within the time period), a consistent LBT failure is triggered.

[0003] Sidelink (SL) is a direct link for communication between devices for several applications such as proximity services (device to device (D2D)), vehicle to vehicle (V2V), vehicle to passenger (V2P), Internet of Things (IoT), wearable devices, etc. SL transmission, which can also operate on unlicensed bands for public safety or commercial purposes, is needed to perform similar LBT procedures defined in NRU as discussed above. However, if a consistent LBT failure is detected or triggered for the SL-BWP, the SL transmission will not be initiated because only one SL-BWP is supported for the sidelink. That is, if LBT failures are counted for the SL-BWP, then after a consistent LBT failure is triggered, the entire SL-BWP is considered to be faulty and the SL transmission cannot be performed. The failure of the SL transmission may endanger public safety or commercial interests.

[0004] Therefore, triggering a consistent LBT failure for a portion of the SL-BWP (e.g., a set of RBs) rather than triggering a consistent LBT failure for the entire SL-BWP is a possible way forward. Therefore, it is desirable to provide a solution for handling consistent LBT failures per RB set in a SL-U system. Summary of the invention

[0005] An embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver; and a processor coupled to the transceiver and configured to: detect a consistent LBT failure on a set of resource blocks (RBs) of a SL bandwidth part (BWP); perform one of the following operations: trigger a resource selection procedure; trigger a resource pool selection procedure; transmit a first indication indicating the consistent LBT failure on the set of RBs; determine the set of RBs as recovered in response to one or more conditions being met; or trigger a consistent LBT failure for the SL BWP or declare a SL BWP failure.

[0006] In some embodiments, the resource selection procedure includes: performing a resource selection procedure for remaining transmissions on a set of RBs that do not have consistent LBT failures for single transmissions; performing a resource selection procedure for reserved resources on the set of RBs that do not have consistent LBT failures for multiple transmissions; or performing a resource selection procedure for remaining transmissions on the set of RBs that do not have consistent LBT failures, wherein the remaining transmissions are associated with at least one of: a specific destination, a specific logical channel (LCH), or an LCH with a specific priority level.

[0007] In some embodiments, the resource pool selection procedure includes one of: prohibiting selection of a resource pool including the RB set; or selecting the resource pool in a situation where no other resource pool is available and the resource pool including the RB set includes other RB sets that do not have consistent LBT failures.

[0008] In some embodiments, the resource pool containing the RB set is determined to have a lower priority level compared to the other resource pools that do not have consistent LBT failures on any RB set in the other resource pools.

[0009] In some embodiments, the set of RBs in the resource pool is determined to have a lower priority than other sets of RBs in the resource pool.

[0010] In some embodiments, the first indication comprises a medium access control control element (MAC CE) or a radio resource control (RRC) signaling.

[0011] In some embodiments, the one or more conditions include: expiration of a prohibition timer; the number of LBT successes associated with the RB set is higher than a first threshold; the number of LBT failures associated with the RB set is lower than a second threshold; the result of a channel busy rate (CBR) measurement of the RB set is lower than a third threshold; a second indication from the BS indicates that the RB set is restored; a third indication from the BS indicates that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured.

[0012] In some embodiments, in the event that a consistent LBT failure on each RB set of the SL BWP is detected, the processor is further configured to: trigger a consistent LBT failure for the SL BWP; or declare a SL BWP failure.

[0013] In some embodiments, the processor is further configured to: transmit a fourth indication indicating the consistent LBT failure for the SL BWP.

[0014] Another embodiment of the present disclosure provides a base station (BS), comprising: a transceiver; and a processor, which is coupled to the transceiver and configured to: receive a first indication from a UE, the first indication indicating a consistent LBT failure on a resource block (RB) set of a SL BWP; and perform one of the following operations: transmit to the UE a second indication indicating that the RB set is restored, or a third indication indicating that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured; or receive a fourth indication from the UE, the fourth indication indicating a consistent LBT failure on each RB set of the SL BWP; and indicate another SL BWP to the UE.

[0015] In some embodiments, the first indication comprises a MAC CE or a radio resource control (RRC) signaling.

[0016] Another embodiment of the present disclosure provides a method performed by a UE, comprising: detecting a consistent LBT failure on a resource block (RB) set of a SL BWP; performing one of the following operations: triggering a resource selection procedure; triggering a resource pool selection procedure; transmitting a first indication indicating the consistent LBT failure on the RB set; determining the RB set as recovered in response to one or more conditions being met; or triggering a consistent LBT failure for the SL BWP or declaring a SL BWP failure.

[0017] Another embodiment of the present disclosure provides a method performed by a BS, comprising: receiving a first indication from a UE, the first indication indicating a consistent LBT failure on a resource block (RB) set of a SL BWP; and performing one of the following operations: transmitting to the UE a second indication indicating that the RB set is restored, or a third indication indicating that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured; or receiving a fourth indication from the UE, the fourth indication indicating a consistent LBT failure on each RB set of the SL BWP; and indicating another SL BWP to the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to describe the manner in which the advantages and features of the application can be obtained, the application is described by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the application and therefore should not be considered limiting of its scope.

[0019] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure is illustrated.

[0020] Figure 2 The diagram illustrates a method performed by a UE for handling consistent LBT failures according to some embodiments of the present disclosure.

[0021] Figure 3 The diagram illustrates a method performed by a BS for handling consistent LBT failures according to some embodiments of the present disclosure.

[0022] Figure 4 Illustrated is a simplified block diagram of an apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0023] The detailed description of the accompanying drawings is intended as a description of the currently preferred embodiments of the present invention, and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be included in the spirit and scope of the present invention.

[0024] Although the operations are depicted in a particular order in the drawings, those skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all of the illustrated operations need not be performed to achieve a desired result; one or more operations may sometimes be skipped. In addition, the drawings may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the example processes schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous.

[0025] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., cellular telephone networks, networks based on time division multiple access (TDMA), networks based on code division multiple access (CDMA), networks based on orthogonal frequency division multiple access (OFDMA), LTE networks, networks based on the third generation partnership project (3GPP), LTE, advanced LTE (LTE-A), 3GPP 4G, 3GPP 5G NR, 3GPP release 16 and higher, satellite communication networks, high altitude platform networks, etc.). Please consider that, with the development of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and in addition, the terms stated in the present disclosure may change, which should not affect the principles of the present disclosure.

[0026] The user equipment (UE) in the NR SL-U scenario may be referred to as SL UE. The SL UE transmitting data on the sidelink in the unlicensed spectrum may be referred to as a UE for transmission, a transmitting UE, a transmitting SL UE, a Tx UE, a SL Tx UE, a SL BWP Tx UE, a UE, etc. The SL UE receiving data on the sidelink in the unlicensed spectrum may be referred to as a UE for reception, a receiving UE, a receiving SL UE, a Rx UE, a SL Rx UE, a UE, etc.

[0027] SL UEs may include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart TVs (e.g., TVs connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle-mounted computers, network devices (e.g., routers, switches, and modems), Internet of Things (IoT) devices, personal computers (PCs), gaming consoles, extended reality (XR) devices, and the like.

[0028] According to some embodiments of the present disclosure, the SL UE may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of sending and receiving communication signals on a wireless network.

[0029] According to some embodiments of the present disclosure, the SL UE may include a wearable device such as a smart watch, a fitness band, an optical head-mounted display, etc. In addition, the SL UE may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal or a device, or described using other terms used in the art. The SL UE may communicate directly with the BS via communication signals.

[0030] The BS in the NR SL-U scenario may be referred to as a base unit, base, access point, access terminal, macro cell, Node B, enhanced Node B (eNB), gNB, Home Node B, relay node, device, remote unit or any other term used in the art. The BS may be distributed over a geographical area. Typically, a BS is part of a radio access network, which may include one or more controllers communicatively coupled to one or more corresponding base stations.

[0031] The BS is typically communicatively coupled to one or more packet core networks (PCNs), which may be coupled to other networks, such as a packet data network (PDN) (e.g., the Internet) and a public switched telephone network, among others. These and other elements of the radio access and core networks are not illustrated, but are generally well known to those skilled in the art. For example, one or more BSs may be communicatively coupled to a mobility management entity (MME), a serving gateway (SGW), and / or a packet data network gateway (PGW).

[0032] A BS may serve several SL UEs within a service area (eg, a cell or cell sector) via wireless communication links. A BS may communicate directly with one or more SL UEs via communication signals. For example, a BS may serve SL UEs within a macro cell.

[0033] In the NR SL-U scenario, the sidelink communication between the Tx UE and the receiving (Rx) UE includes multicast communication, unicast communication or broadcast communication.

[0034] Figure 1 A wireless communication system 100 (eg, a SL-U communication system) is illustrated in accordance with some embodiments of the present disclosure.

[0035] like Figure 1 As shown in , the wireless communication system 100 includes a base station (e.g., BS102) and some UEs (e.g., UE101-A, UE 101-B, UE 101-C, and UE 101-D). UE 101-A and UE 101-B are within the coverage of BS102, and UE 101-C and UE 101-D are outside the coverage of BS102. UE 101-A, UE 101-B, UE 101-C, and UE 101-D may perform sidelink unicast transmission, sidelink multicast transmission, or sidelink broadcast transmission in an unlicensed spectrum (e.g., SL BWP). UE 101-A, UE 101-B, UE 101-C, and UE 101-D may be referred to as SL UEs. Please consider that according to some other embodiments of the present disclosure, the SL-U communication system may include more BSs and more or fewer SL UEs.

[0036] In addition, although Figure 1 The SL UE shown in the figure is illustrated in the shape of a mobile phone, but please consider that according to some other embodiments of the present disclosure, the SL communication system may include any type of UE (e.g., a roadmap device, a mobile phone, a computer, a laptop, an IoT device, or other types of devices).

[0037] according to Figure 1 In some embodiments, UE 101-A may be used as a Tx UE, and UE 101-B, UE 101-C, and UE 101-D may be used as Rx UEs. UE 101-A may exchange SL messages with UE 101-B or UE 101-C via a sidelink using, for example, NR technology or LTE technology via a PC5 interface as defined in a 3GPP document. UE 101-A may transmit information or data to other UEs within the SL-U communication system via sidelink unicast, sidelink multicast, or sidelink broadcast. For example, UE 101-A may transmit data to UE 101-B in a sidelink unicast session. UE 101-A may transmit data to UE 101-B and UE 101-C in a multicast group via a sidelink multicast transmission session. In addition, UE 101-A may transmit data to UE 101-B and UE 101-C via a sidelink broadcast transmission session.

[0038] Alternatively, according to Figure 1 In some other embodiments, UE 101-B or UE 101-C may function as a Tx UE and transmit information or data, and UE 101-A may function as a Rx UE and receive information or data from UE 101-B or UE 101-C.

[0039] Figure 1 Both UE 101-A and UE 101-B in the embodiment of the present invention can transmit information to BS 102 and receive control information from BS 102, for example, via a Uu interface. BS 102 can define one or more cells, and each cell can have a coverage area. Figure 1 As shown in FIG. 1 , both UE 101 -A and UE 101 -B are within the coverage of BS 102, while UE 101 -C and UE 101 -D are not within the coverage.

[0040] like Figure 1BS102 illustrated and shown in the figure may not be a specific base station, but may be any base station in the SL-U communication system. For example, assuming that the SL-U communication system includes two BSs, a situation where UE 101-A is within the coverage area of ​​either of the two BSs may be referred to as a situation where UE 101-A is within the coverage area of ​​the BS in the SL-U communication system; and a situation where UE 101-A is only outside the coverage areas of the two BSs may be referred to as a situation where UE 101-A is outside the coverage area of ​​the BS in the SL-U communication system.

[0041] The UE may operate in different modes. At least the following two sidelink resource allocation modes are defined for sidelink communication: Resource allocation mode 1: the BS may schedule sidelink resources for use by the UE for sidelink transmission; and Resource allocation mode 2: the UE may determine the sidelink transmission resources within the sidelink resources configured by the BS or the network or the pre-configured sidelink resources. In resource allocation mode 2, the BS may not schedule sidelink resources for the UE. Figure 1 In some embodiments, UE 101-A and UE 101-B may be in resource allocation mode 1, and UE 101-C and UE 101-D may be in resource allocation mode 2. In some other cases, UE 101-A and UE 101-B may also operate in resource allocation mode 2. In the following of the present disclosure, "mode 1" may refer to resource allocation mode 1, and "mode 2" may refer to resource allocation mode 2.

[0042] Consistent LBT failure can be detected for BWP. For NR sidelink, only one carrier can be configured and only one SL BWP is supported for one carrier. Therefore, consistent LBT failure based on per RB set, rather than per SL BWP, is a possible way forward.

[0043] The SL BWP may include one or more RB sets, and each RB set may include the same number of RBs or a different number of RBs based on the configuration. In some embodiments, one RB may occupy 20 MHz in the frequency domain. In some embodiments, the expression "RB set" may also be referred to as a subband, a subchannel, a group of RBs, etc. In the following of the present disclosure, "RB set", "subband", "subchannel" or "a group of RBs" may be used interchangeably where appropriate.

[0044] A counter (which may be different from the counter for BWP) may be configured and accumulated for each received LBT failure indication for an RB set. When the value of the counter for an RB set reaches or exceeds a threshold within a certain time period, a consistent LBT failure is triggered on the RB set. A consistent LBT failure for an RB set may also be referred to as "consistent LBT failure per RB set", "consistent LBT failure for RB sets", etc.

[0045] This disclosure proposes some solutions for handling consistent LBT failures on a set of RBs.

[0046] Solution 1:

[0047] Solution 1 involves a SL UE operating in resource allocation mode 2. Specifically, a consistent LBT failure on a set of RBs is triggered, and the UE may determine whether to trigger a resource (re)selection procedure. In the event that the UE determines to trigger a resource (re)selection procedure, the UE may further determine how to perform the resource (re)selection.

[0048] Solution 1-1:

[0049] Solution 1-1 involves a single-shot transmission, such as a single media access control protocol data unit (MAC PDU) transmission, which may be configured with an initial transmission and a certain number of retransmissions. In other words, the UE may first perform an initial transmission of the MAC PDU, and then perform the number of retransmissions of the MAC PDU. The SL UE may have selected and reserved resources for the initial transmission and retransmissions for the SL grant on a specific RB set. When a consistent LBT failure is triggered on a specific RB set (or the UE detects a consistent LBT failure on a specific RB set), the UE may determine the transmission status of the single-shot transmission, such as whether to perform an initial transmission, or how many retransmissions are left, etc.

[0050] In the case that a transmission of a single-shot transmission has not been performed (i.e., the initial transmission or the number of retransmissions has not been performed) and the SLUE still needs to transmit a single-shot transmission, the SL UE may be triggered to perform a resource selection procedure (or a resource reselection procedure). The SL UE may clear the SL grant and remove all reserved resources (since no transmission has been performed yet), and trigger a resource (re)selection procedure to select new resources for the initial transmission and the number of retransmissions.

[0051] In the case where at least one transmission of a single-shot transmission has been performed, the initial transmission and at least one transmission among the number of retransmissions have been performed. Therefore, the initial transmission of the single-shot transmission has been performed, and there may be some retransmissions of the single-shot transmission that have not been performed. In the case where the SL UE still needs to perform retransmissions of the single-shot transmission, the SL UE may be triggered to perform a resource selection procedure (or a resource reselection procedure). The SL UE may clear the SL grant and remove the remaining reserved resources (which are reserved for performing the remaining retransmissions of the MAC PDU), and trigger the resource (re)selection procedure to select new resources for the remaining retransmissions.

[0052] In the case where all transmissions of a single-shot transmission have been performed, there may be no need to trigger the resource selection procedure (or resource reselection procedure).

[0053] In some embodiments, the SL UE may have selected three resources for a specific SL grant to perform a single MAC PDU transmission, where one resource is used for the initial transmission of the single MAC PDU transmission and two resources are used for retransmissions of the single MAC PDU transmission. After the initial transmission of the single MAC PDU transmission, the SL UE may detect that a consistent LBT failure is triggered for the RB set, and the SL UE may clear the SL grant and remove the two resources used for the retransmission of the single MAC PDU transmission. In the case where the SL UE still needs to perform the remainder of the single MAC PDU transmission (i.e., perform two retransmissions of the single MAC PDU transmission), the UE may trigger a resource selection procedure (or a resource reselection procedure) to select two new resources for the two retransmissions of the single MAC PDU transmission on the RB set that does not have a consistent LBT failure.

[0054] Solution 1-2:

[0055] Solution 1-2 involves multiple transmissions, such as transmission of multiple MAC PDUs. The transmission of multiple MAC PDUs may be transmitted periodically, and the SL UE may have selected and reserved a series of resources for the periodic transmission of multiple MAC PDUs for the SL grant on a specific RB set. When a consistent LBT failure is triggered on a specific RB set, the UE can, for example, determine the transmission status of the multiple transmissions, or how many retransmissions are left, etc.

[0056] When a certain number of transmissions of a plurality of MAC PDUs has not been performed (the number may be in the range from 0 to the total number of transmissions of the plurality of MAC PDUs) and the SL UE still needs to perform a certain number of transmissions of the plurality of MAC PDUs, the SL UE may be triggered to perform a resource selection procedure (or a resource reselection procedure). That is, the SL UE may clear the SL grant and remove the remaining reserved resources (the number of the remaining reserved resources may be in the range from 0 to the total number of transmissions of the plurality of MAC PDUs), and trigger resource (re)selection to select new resources for the said number of transmissions of the plurality of MAC PDUs on the RB set that does not have a consistent LBT failure.

[0057] For example, the SL UE may have selected and reserved 30 resources on a RB set for a specific SL grant to perform multiple transmissions, and after the 10th transmission, the RB set may have had a consistent LBT failure. In other words, when performing the first ten transmissions, the SL UE may clear the SL grant and remove the remaining 20 resources for multiple transmissions, and trigger resource (re)selection to select 20 new resources for the remaining 20 transmissions of the multiple transmissions on the RB set that does not have a consistent LBT failure.

[0058] In the case where all transmissions of a multiple transmission have been performed, there may be no need to trigger the resource selection procedure (or resource reselection procedure).

[0059] Solutions 1-3:

[0060] Solutions 1-3 involve transmissions associated with a specific layer 2 (L2) destination or a specific LCH or an LCH with a specific priority level.

[0061] In some embodiments, the reselected resources for SL transmission are enabled only for data of a specific layer 2 (L2) destination or a specific LCH or an LCH with a specific priority level.

[0062] For example, in a situation where a single-transmission is associated with a specific LCH and an initial transmission of the single-transmission and at least one of the number of retransmissions have not been performed, the SL UE may trigger a resource selection procedure or a resource reselection procedure to perform the initial transmission of the single-transmission and the remaining transmissions of the number of retransmissions. In another example, in a situation where multiple transmissions are for a specific L2 destination and at least one of the multiple transmissions has not been performed, the SL UE may trigger a resource selection procedure or a resource reselection procedure to perform the remaining transmissions of the multiple transmissions. In another example, in a situation where any SL transmission is associated with an LCH with a specific priority level and a consistent LBT failure occurs on a set of RBs, when a consistent LBT failure is triggered on a specific set of RBs, the UE may trigger a resource selection procedure or a resource reselection procedure to perform the remaining part of the SL transmission.

[0063] During the resource (re)selection procedure for selecting new resources, the SL UE may be prohibited from selecting resources on a RB set on which a consistent LBT failure has occurred until the RB set is restored. That is, the UE may only select resources on a RB set that does not have a consistent LBT failure.

[0064] Solution 2

[0065] Solution 2 involves SL UEs operating in resource allocation mode 2. When a consistent failure on a set of RBs is triggered (or when the UE detects a consistent LBT failure on a specific set of RBs), the SL UE may perform a resource pool selection procedure. The set of RBs with consistent failures may be referred to as a "problematic RB set", "a set of RBs with a lower priority", etc.

[0066] In some embodiments, during the resource pool selection process, several rules may be applied:

[0067] Rule 1: In the case where a resource pool contains only one RB set (which is a problematic RB set), selection of the resource pool may be prohibited until the RB set in the resource pool is restored or until the RB set is available. In the case where a resource pool contains two or more RB sets and all RB sets in the resource pool are problematic RB sets, selection of the resource pool may be prohibited.

[0068] Rule 2: In addition to the problematic RB set, the resource pool may also contain another RB set, in other words, one or more RB sets in the resource pool are not problematic, and in this case, the resource pool may be prohibited from being selected.

[0069] Alternatively, the resource pool may be determined to be associated with a lower priority level than another resource pool having a non-problematic RB set. For example, a resource pool having a non-problematic RB set may have a higher priority level, such as "0"; a resource pool having both a problematic RB set and a normal RB set (i.e., a RB set that does not have consistent LBT failures) may have a lower priority level, such as "1". In some cases, a resource pool having both a problematic RB set and a normal RB set may be marked as "problematic" and considered as a problematic resource pool; a resource pool without a problematic RB set may not be marked.

[0070] During the resource pool selection procedure, the SL UE may prefer a resource pool with a higher priority level (e.g., "0") over a resource pool with a lower priority level (e.g., "1"). In the event that a resource pool with a higher priority level has not been selected, the SL UE may then select a resource pool with a lower priority level.

[0071] In a resource pool with a lower priority level (i.e., a problematic resource pool), a set of RBs with consistent LBT failures may be marked as problematic, i.e., the set of RBs may be considered as a problematic set of RBs, and may be determined to be associated with a lower priority level (e.g., "low") compared to another set of RBs in the problematic resource pool that do not have consistent LBT failures (e.g., "high"). Therefore, when the SL UE selects a resource pool with a lower priority level, the SL UE may select a set of RBs with a higher priority level (e.g., "high") in the resource pool.

[0072] Solution 3

[0073] Solution 3 involves SL UEs operating in resource allocation mode 1. For UEs in mode 1 (e.g. Figure 1 In the UE 101-A), when a consistent LBT failure of a specific RB set is triggered, the SL UE may transmit an indication to the BS or to the network to indicate the consistent LBT failure on the RB set. The indication may be MAC CE or RRC signaling, and the indication may be transmitted on the Uu interface between the BS and the UE.

[0074] In some embodiments, the indication may include consistent LBT failure information and the corresponding RB set, such as the number of LBT failure indications, an identifier of the RB set, and the like.

[0075] In some embodiments, the SL UE may receive an indication from a peer UE (for example, another SL UE), which may include a consistent LBT failure report. The consistent LBT failure report from the peer UE may include the number of LBT failure indications, an identifier of an RB set, etc. The peer UE may operate in resource allocation mode 1 or in resource allocation mode 2. After receiving the indication, the SL UE may be triggered to transmit a report on the consistent LBT failure information and the corresponding RB set of the peer UE to the BS.

[0076] Since the BS can schedule sidelink resources for use by the UE in resource allocation mode 1 for sidelink transmission, after receiving an indication (or report) from the UE, the BS can instruct the UE to use the additional sidelink resources.

[0077] Solution 4:

[0078] Solution 4 involves recovery from consistent LBT failure on a set of RBs and involves SL UEs operating in resource allocation mode 1 or mode 2.

[0079] Solution 4-1:

[0080] Solution 4-1 involves a SL UE operating in resource allocation mode 1 or resource allocation mode 2. When a consistent LBT failure is triggered for a specific set of RBs, the SL UE may start a timer, which may be referred to as a prohibit timer. The length of the timer may be indicated by the network, for example, via an indication from the BS, or may be preconfigured or configured.

[0081] While the timer is running (i.e., during the time period of the timer), the SL UE may be prohibited from selecting the specific RB set during a resource selection procedure or a resource reselection procedure. Resources in the specific RB set are prohibited from being used for SL communication. When the timer expires, the SL UE may consider that the specific RB set is restored, i.e., the specific RB set may be selected by the SL UE during a resource selection procedure or a resource reselection procedure, or may be used for SL communication. When the timer expires, the specific RB set may also be referred to as available.

[0082] Solution 4-2

[0083] Solution 4-2 involves a SL UE operating in resource allocation mode 1 or resource allocation mode 2. When a consistent LBT failure is triggered for a specific set of RBs, the SL UE may continuously perform the LBT procedure on the set of RBs. For example, the SL UE may perform the LBT procedure on the set of RBs in a periodic manner. The LBT procedure may be any type of LBT procedure, such as LBT Type 1, LBT Type 2a, LBT Type b, LBT Category 1 (Cat. 1), LBT Cat. 2, LBT Cat. 4, etc. The periodicity for performing the LBT procedure may be indicated by the BS, the network, or may be configured or pre-configured.

[0084] In some embodiments, a first threshold and a time period may be used to determine whether the RB set is restored. The first threshold may be associated with the accumulated number of LBT successes. The value of the first threshold and / or the time period may be indicated by the BS, the network, or may be configured or preconfigured. In the case where the accumulated number of LBT successes during the time period is greater than the first threshold, the RB set is considered restored or available and can be used for SL transmission.

[0085] In some embodiments, a second threshold and a time period may be used to determine whether the RB set is restored. The second threshold may be associated with the accumulated number of LBT failures. The value of the second threshold and / or the time period may be indicated by the BS, the network, or may be configured or preconfigured. In the case where the accumulated number of LBT failures during the time period is less than the second threshold, the RB set is deemed to be restored or available and may be used for SL transmission.

[0086] Solution 4-3

[0087] Solution 4-3 involves a SL UE operating in resource allocation mode 1 or resource allocation mode 2. When a consistent LBT failure is triggered for a specific RB set, the SL UE may continuously (e.g., in a periodic manner) perform CBR measurement on the specific RB set. The threshold associated with the CBR measurement may be indicated by the BS, the network, or may be configured or preconfigured. When the CBR measurement result is lower than the threshold (i.e., the load of the specific RB set is lower than the threshold), the RB set is deemed recovered or available and can be used for SL transmission.

[0088] Solution 4-4

[0089] Solution 4-4 involves a SL UE operating in resource allocation mode 1. When a consistent LBT failure is triggered for a specific RB set, the SL UE in mode 1 may receive an indication from the BS, which may indicate that the specific RB set is recovered or available. The UE may then regard the specific RB set as recovered or available. The BS may determine whether the specific RB set is recovered or available by collecting other SL-U UE transmission information about the specific RB set.

[0090] Solutions 4-5

[0091] Solution 4-5 involves a SL UE operating in resource allocation mode 1. When a consistent LBT failure is triggered for a specific RB set, the SL UE in mode 1 may receive an indication from the BS, which may indicate at least one of the following:

[0092] a) reconfiguring the specific RB set;

[0093] b) reconfiguring the resource pool including the specific RB set; or

[0094] c) Reconfiguring the LBT subchannel (or LBT BWP) including the specific RB set.

[0095] Based on this indication, the UE may consider that the specific RB set is recovered or available.

[0096] When RB sets are restored, in situations where the UE may have marked a particular RB set as problematic or determined that the RB set is associated with a lower priority level (e.g., "low"), after the particular RB set is restored, the UE may remove the problematic label or determine that the RB set is associated with a higher priority level (e.g., "high").

[0097] Similarly, when a resource pool is restored, in a situation where the UE may have marked the resource pool as problematic or determined that the resource pool is associated with a lower priority level (e.g., "1") compared to other resource pools, after the resource pool is restored, the UE may remove the problematic label or determine that the resource pool is associated with a higher priority level (e.g., "0").

[0098] Solution 5:

[0099] Solution 5 involves SL UE operating in resource allocation mode 1.

[0100] In some embodiments, a consistent LBT failure is triggered for each RB set of all RB sets of the SL BWP.

[0101] In this case, the UE may trigger a consistent LBT failure for the SL BWP. Alternatively, the UE may declare a SL BWP failure, that is, the UE may consider that the SL BWP cannot be used any more.

[0102] In one embodiment, in one option, if a consistent LBT failure is triggered for all RB sets on a configured SL-BWP or SL carrier, a consistent LBT failure for the configured SL BWP is triggered. In another option, if a consistent LBT failure is triggered for all RB sets on a configured SL-BWP or SL carrier, the UE may declare that the SL carrier is a failure, i.e., the SL carrier cannot be used any more. The UE may report to a higher layer and report to the BS to request a new SL carrier for SL communication.

[0103] Figure 2 The diagram illustrates a method performed by a UE for handling consistent LBT failures according to some embodiments of the present disclosure.

[0104] In operation 201, the UE may detect a consistent LBT failure on a set of RBs of a SL BWP. In operation 202, the UE may perform one of the following operations: trigger a resource selection procedure; trigger a resource pool selection procedure; transmit a first indication indicating a consistent LBT failure on the set of RBs; determine the set of RBs as recovered in response to one or more conditions being met; or trigger a consistent LBT failure for the SL BWP or declare a SL BWP failure.

[0105] In some embodiments, the resource selection procedure may include at least one of the following: performing a resource selection procedure for the remaining transmissions on the RB set without consistent LBT failures for single transmissions; performing a resource selection procedure for the reserved resources on the RB set without consistent LBT failures for multiple transmissions; or performing a resource selection procedure for the remaining transmissions on the RB set without consistent LBT failures, wherein the remaining transmissions are associated with at least one of the following: a specific destination, a specific LCH, or an LCH with a specific priority level. For example, the UE may perform a resource selection procedure for the remaining transmissions (or remaining retransmissions) of a single MAC PDU transmission, and the UE may perform a resource selection procedure on the RB set without consistent LBT failures. Similarly, the UE may perform a resource selection procedure for the remaining transmissions of multiple MAC PDU transmissions (i.e., periodic MAC PDU transmissions) on the RB set without consistent LBT failures. In some embodiments, when the single MAC PDU transmission or the multiple MAC PDU transmissions are associated with a specific priority level (e.g., above a priority threshold), the UE may perform a resource selection procedure for the remaining transmissions.

[0106] In some embodiments, the resource pool selection procedure includes one of: prohibiting selection of a resource pool including the RB set; or selecting the resource pool in a situation where no other resource pool is available and the resource pool including the RB set includes other RB sets that do not have consistent LBT failures.

[0107] In some embodiments, the resource pool containing the RB set is determined to have a lower priority level compared to other resource pools that do not have consistent LBT failures on any RB sets in other resource pools.

[0108] In some embodiments, the set of RBs in the resource pool is determined to have a lower priority than other sets of RBs in the resource pool.

[0109] In some embodiments, the first indication includes MAC CE or RRC signaling.

[0110] In some embodiments, one or more conditions include: expiration of a prohibition timer (for example, solution 4-1); the number of LBT successes associated with an RB set is higher than a first threshold (for example, solution 4-2); the number of LBT failures associated with an RB set is lower than a second threshold (for example, solution 4-2); the result of a CBR measurement of the RB set is lower than a third threshold (for example, solution 4-3); a second indication from the BS indicates that the RB set is restored (for example, solution 4-4); a third indication from the BS indicates that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured (for example, solution 4-5).

[0111] In some embodiments, in the event that a consistent LBT failure on each RB set of the SL BWP is detected, the processor is further configured to: trigger a consistent LBT failure for the SL BWP; or declare a SL BWP failure.

[0112] In some embodiments, the UE may transmit a fourth indication indicating a consistent LBT failure for the SL BWP.

[0113] Figure 3 The diagram illustrates a method performed by a BS for handling consistent LBT failures according to some embodiments of the present disclosure.

[0114] In operation 301, the BS may receive a first indication from the UE, wherein the first indication indicates a consistent LBT failure on the RB set of the SL BWP; and perform one of the following operations: transmit to the UE a second indication indicating that the RB set is restored, or a third indication indicating that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured; or receive a fourth indication from the UE, wherein the fourth indication indicates a consistent LBT failure on each RB set of the SL BWP; and indicate another SL BWP to the UE.

[0115] Figure 4 Illustrated is a simplified block diagram of an exemplary apparatus according to some embodiments of the present disclosure.

[0116] like Figure 4 , an example of an apparatus 400 may include at least one processor 404 and at least one transceiver 402 coupled to the processor 404. The apparatus 400 may be a UE, a BS, a RAN node, a source node, a target node, a third node, or any other device having similar functionality.

[0117] Although in this figure, elements such as at least one transceiver 402 and processor 404 are described in the singular, plural forms are also contemplated unless it is explicitly stated that they are limited to the singular form. In some embodiments of the present disclosure, transceiver 402 can be divided into two devices, such as a receiving circuit system and a transmitting circuit system. In some embodiments of the present disclosure, device 400 may further include an input device, a memory and / or other components.

[0118] In some embodiments of the present disclosure, the device 400 may be a UE. The transceiver 402 and the processor 404 may interact with each other to perform Figures 1 to 4 In some embodiments of the present disclosure, the device 400 may be a node. The transceiver 402 and the processor 404 may interact with each other to perform the operations of the UE described in any one of the embodiments. Figures 1 to 3 The operation of a node described in any of .

[0119] In some embodiments of the present disclosure, the apparatus 400 may further include at least one non-transitory computer-readable medium.

[0120] For example, in some embodiments of the present disclosure, a non-transitory computer-readable medium may store computer-executable instructions thereon to cause the processor 404 to implement the method for the UE as described above. For example, when the computer-executable instructions are executed, the processor 404 interacting with the transceiver 402 executes Figures 1 to 3 Operation of the UE described in any one of .

[0121] In some embodiments of the present disclosure, a non-transitory computer-readable medium may store thereon computer-executable instructions to cause the processor 404 to implement the method for a node as described above. For example, when the computer-executable instructions are executed, the processor 404 interacting with the transceiver 402 executes Figures 1 to 3 The operation of a node described in any of .

[0122] The method of the present disclosure can be implemented on a programmed processor. However, the controller, flow chart and module can also be implemented on a general or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit components, an integrated circuit, a hardware electronic or logic circuit (such as a discrete component circuit, a programmable logic device), etc. In general, any device with a finite state machine capable of implementing the flow chart shown in the figure can be used to implement the processing functions of the present disclosure.

[0123] Although the present disclosure has been described using its specific embodiments, it is apparent that many alternatives, modifications and variations will be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added or replaced in other embodiments. In addition, not all elements shown in each figure are necessary for the operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent technical solutions. Therefore, the embodiments of the present disclosure as set forth herein are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0124] In the present disclosure, for example, "first", "second" or the like relational terms can be used only to distinguish an entity or action from another entity or action, and may not necessarily require or imply any actual this relationship or order between such entities or actions. The term "comprises", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements do not only comprise those elements, but may comprise other elements that are not clearly listed or inherent to this process, method, article or equipment. Without having more constraints, the elements starting with "a, an" or the like do not exclude the existence of additional identical elements in the process, method, article or equipment comprising the elements. In addition, the term "another" is defined as at least the second or more. The term "including", "having" or the like as used herein is defined as "comprising".

Claims

1. A user equipment UE, comprising: Transceiver; as well as a processor coupled to the transceiver and configured to: A consistent listen-before-talk (LBT) failure is detected on the set of resource blocks (RBs) of the sidelink (SL) bandwidth part (BWP); Do one of the following: triggering the resource selection process; Triggering the resource pool selection process; transmitting a first indication indicating the consistent LBT failure on the set of RBs; determining the set of RBs as being restored in response to one or more conditions being satisfied; or A consistent LBT fault for the SL BWP is triggered or a SL BWP fault is declared.

2. The UE of claim 1, wherein the resource selection procedure comprises at least one of the following: performing a resource selection procedure for the remaining transmissions on the RB set without consistent LBT failures for the single-shot transmission; performing a resource selection procedure on the reserved resources on the set of RBs not having consistent LBT failures for multiple transmissions; or A resource selection procedure is performed for remaining transmissions on the set of RBs that do not have consistent LBT failures, wherein the remaining transmissions are associated with at least one of: a specific destination, a specific logical channel LCH, or an LCH with a specific priority level.

3. The UE of claim 1 , wherein the resource pool selection procedure comprises one of the following: prohibiting selection of a resource pool containing the RB set; or In the case where no other resource pool is available and the resource pool that includes the RB set includes other RB sets that do not have consistent LBT failures, the resource pool is selected.

4. The UE of claim 3, wherein the resource pool including the RB set is determined to have a lower priority level compared to the other resource pools that do not have consistent LBT failures on any RB set in the other resource pools. 5 . The UE of claim 4 , wherein the set of RBs in the resource pool is determined to have a lower priority level than other sets of RBs in the resource pool. 6 . The UE according to claim 1 , wherein the first indication comprises a medium access control element (MAC CE) or a radio resource control (RRC) signaling.

7. The UE of claim 1, wherein the one or more conditions include: The prohibit timer expires; The number of LBT successes associated with the RB set is higher than a first threshold; The number of LBT failures associated with the RB set is lower than a second threshold; A result of measuring a channel busy rate CBR of the RB set is lower than a third threshold; A second indication from the BS indicates that the RB set is restored; The third indication from the BS indicates that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured.

8. The UE of claim 1 , wherein in case a consistent LBT failure on each RB set of the SL BWP is detected, the processor is further configured to: triggering a consistent LBT fault for the SL BWP; or Declare SL BWP failure.

9. The UE of claim 8, wherein the processor is further configured to: A fourth indication is transmitted, the fourth indication indicating the consistent LBT failure for the SL BWP.

10. A base station BS, comprising: Transceiver; as well as a processor coupled to the transceiver and configured to: receiving a first indication from a user equipment UE, the first indication indicating a consistent listen-before-talk (LBT) failure on a set of resource blocks (RBs) of a sidelink (SL) bandwidth part (BWP); and Do one of the following: transmitting to the UE a second indication indicating that the RB set is restored, or a third indication indicating that at least one of the RB set, the resource pool of the RB set, or the SL BWP is reconfigured; or A fourth indication is received from the UE, the fourth indication indicating a consistent LBT failure on each set of RBs of the SL BWP; and another SL BWP is indicated to the UE. 11 . The BS according to claim 10 , wherein the first indication comprises a medium access control element (MAC CE) or a radio resource control (RRC) signaling.

12. A method performed by a user equipment UE, comprising: A consistent listen-before-talk (LBT) failure is detected on the set of resource blocks (RBs) of the sidelink (SL) bandwidth part (BWP); Do one of the following: triggering the resource selection process; Triggering the resource pool selection process; transmitting a first indication indicating the consistent LBT failure on the set of RBs; determining the set of RBs as being restored in response to one or more conditions being satisfied; or A consistent LBT fault for the SL BWP is triggered or a SL BWP fault is declared.

13. The method of claim 12, further comprising at least one of the following: performing a resource selection procedure for remaining transmissions on the set of RBs without consistent LBT failures for a single-shot transmission; performing a resource selection procedure on reserved resources on the set of RBs not having consistent LBT failures for multiple transmissions; or A resource selection procedure is performed for remaining transmissions on the set of RBs that do not have consistent LBT failures, wherein the remaining transmissions are associated with at least one of: a specific destination, a specific logical channel LCH, or an LCH with a specific priority level.

14. The method according to claim 12, further comprising: Prohibiting selection of a resource pool containing the RB set; or In the case where no other resource pool is available and the resource pool that includes the RB set includes other RB sets that do not have consistent LBT failures, the resource pool is selected.

15. The method of claim 14, wherein the resource pool containing the RB set is determined to have a lower priority level compared to the other resource pools that do not have consistent LBT failures on any RB set in the other resource pools.

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