WO2024093349A1

WO2024093349A1 - Autonomous retransmission for sl mcst

Info

Publication number: WO2024093349A1
Application number: PCT/CN2023/106562
Authority: WO
Inventors: Jing HAN; Lianhai WU; Ran YUE
Original assignee: Lenovo (Beijing) Limited
Priority date: 2023-07-10
Filing date: 2023-07-10
Publication date: 2024-05-10

Abstract

Various aspects of the present disclosure relate to a user equipment (UE), a processor for wireless communication, a method, and a computer readable medium for autonomous retransmission for sidelink (SL) multi-consecutive slot transmission (MCSt). In an aspect, a UE determines, for a SL MCSt transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission. The TB is associated with a dropped transmission caused by at least one LBT failure. Based on determining to retransmit the TB, the UE retransmits the TB on a resource of the plurality of consecutive resources. In this way, autonomous transmission or retransmission for SL MCSt is enabled and transmission reliability is improved.

Description

AUTONOMOUS RETRANSMISSION FOR SL MCST

TECHNICAL FIELD

The present disclosure relates to wireless communications, and more specifically to a user equipment (UE) , a processor for wireless communication, a method, and a computer readable medium for autonomous retransmission for sidelink (SL) multi-consecutive slot transmission (MCSt) .

BACKGROUND

A wireless communications system may include one or multiple network communication devices, such as base stations, which may be otherwise known as an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. Each network communication devices, such as a base station may support wireless communications for one or multiple user communication devices, which may be otherwise known as user equipment (UE) , or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) . Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G) ) .

A work item (WI) is approved for sidelink enhancement for Rel-18. One objective is for sidelink (SL) transmission on unlicensed band, which is to study the unlicensed channel access mechanism impact on sidelink resource reservation scheme. UE needs to perform Listen Before Talk (LBT) to monitor and access the channel before SL transmission on unlicensed band. If LBT succeed, UE can access the channel for a time period called Channel Occupancy Time (COT) for transmission. In order to retain the channel as long as possible and to decrease or even skip the channel sensing time, multi-consecutive slot transmission (MCSt) is also introduced for SL-U transmission.

SUMMARY

The present disclosure relates to a UE, a processor for wireless communication, a method, and a computer readable medium for autonomous retransmission for sidelink (SL) multi-consecutive slot transmission (MCSt) . Embodiments of the disclosure can enable autonomous transmission or retransmission for MCSt on sidelink in case of listen before talk (LBT) failure (s) and thus can improve transmission reliability.

In a first aspect, there is provided a UE. The UE comprises a processor; and a transceiver coupled to the processor, wherein the processor is configured to: determine, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and retransmit, based on determining to retransmit the TB and via the transceiver, the TB on a resource of the plurality of consecutive resources.

In a second aspect, there is provided a processor for wireless communication. The a processor comprise at least one memory; and a controller coupled with the at least one memory and configured to cause the controller to: determine, at a user equipment (UE) and for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and retransmit, based on determining to retransmit the TB, the TB on a resource of the plurality of consecutive resources.

In a third aspect, there is provided a method performed by a UE. The method comprises: determining, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and retransmitting, based on determining to retransmit the TB, the TB on a resource of the plurality of consecutive resources.

In a fourth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed by a processor of an apparatus, causing the apparatus to perform the method according to the third aspect of the disclosure.

In some implementations of the method and the UE described herein, determining whether to retransmit the TB may comprise: determining to retransmit the TB based on determining that autonomous transmission or retransmission configuration is enabled at the UE.

In some implementations of the method and the UE described herein, determining whether to retransmit the TB may comprise: determine whether to retransmit the TB based on a remaining packet delay budget (PDB) of the TB.

In some implementations of the method and the UE described herein, determining whether to retransmit the TB based on the remaining PDB may comprise: determining to retransmit the TB based on determining that the remaining PDB of the TB is less than a threshold.

In some implementations of the method and the UE described herein, determining whether to retransmit the TB based on the remaining PDB may comprise: comparing the remaining PDB of the TB with a remaining PDB of a generated TB or data in a buffer for MCSt transmission to be dropped due to a retransmission of the TB; and based on determining that the remaining PDB of the TB is less than the remaining PDB of the generated TB or the data in the buffer, determining to retransmit the TB.

In some implementations of the method and the UE described herein, determining whether to retransmit the TB may comprise: determining to retransmit the TB based on determining that a priority of the TB is larger than a threshold.

In some implementations of the method and the UE described herein, the plurality of consecutive resources may be a plurality of configured grant (CG) resources.

In some implementations of the method and the UE described herein, the processor is further configured to: reuse a same SL process and corresponding process identity (ID) for the retransmission of the TB as for the dropped transmission.

In some implementations of the method and the UE described herein, the reusing of the same SL process and the corresponding process ID for the retransmission of the TB may be based on determining one or more of the following: an indication of the at least one LBT failure is received for a previous SL grant for the SL process; a medium access control (MAC) protocol data unit (PDU) size of the TB matches a SL grant size; or a configured grant in a next resource belongs to a list of SL allowed configured grants.

In some implementations of the method and the UE described herein, the TB is a first TB, and the processor may be further configured to: transmit, based on determining not to retransmit the first TB and via the transceiver, a second TB on the resource.

In some implementations of the method and the UE described herein, the processor may be further configured to trigger resource reselection.

In some implementations of the method and the UE described herein, the triggering of the resource reselection may be based on determining one of the following: an indication of the at least one LBT failure is received from a physical (PHY) layer of the UE; no more resources for SL MCSt transmission are reserved; a number of resources of a next SL MCSt transmission is less than the current SL MCSt transmission or a threshold; the resources of the next SL MCSt transmission are beyond a remaining PDB of a generated TB or data in a buffer for MCSt transmission; the remaining PDB of the generated TB or the data in the buffer is less than a threshold; or a number of transmissions of the generated TB does not reach a maximum of transmissions for a SL configured grant.

In some implementations of the method and the UE described herein, the resource reselection may be triggered when an indication of the at least one LBT failure is received from the PHY layer of the UE. In some implementations of the method and the UE described herein, the resource reselection may be triggered when an indication of a LBT success is received from the PHY layer of the UE. In some implementations of the method and the UE described herein, the resource reselection may be triggered after the SL MCSt transmission is completed.

In some implementations of the method and the UE described herein, the plurality of consecutive resources may be in one of the following: symbols, slots, or subframes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system in which some embodiments of the present disclosure can be implemented.

FIG. 2 illustrates an example of a process flow in accordance with some example embodiments of the present disclosure.

FIG. 3 illustrates a schematic diagram of exemplary consecutive resources for MCSt transmission in accordance with some example embodiments of the present disclosure.

FIG. 4 illustrates a schematic diagram of exemplary retransmission of transport blocks (TBs) in accordance with some example embodiments of the present disclosure.

FIG. 5 illustrates a schematic diagram of exemplary resource reselection trigger in accordance with some example embodiments of the present disclosure.

FIG. 6 illustrates a schematic diagram of timings for resource reselection trigger in accordance with some example embodiments of the present disclosure.

FIG. 7 illustrates an example of a device that is suitable for implementing some embodiments of the present disclosure.

FIG. 8 illustrates an example of a processor that is suitable for implementing some embodiments of the present disclosure.

FIG. 9 illustrates a flowchart of a method that performed by a user equipment in accordance with aspects of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below. In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an example embodiment, ” “an embodiment, ” “some embodiments, ” and the like indicate that the embodiment (s) described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment (s) . Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” or the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could also be termed as a second element, and similarly, a second element could also be termed as a first element, without departing from the scope of embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms. In some examples, values, procedures, or apparatuses are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments. As used herein, the singular forms “a, ” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises, ” “comprising, ” “has, ” “having, ” “includes” and/or “including, ” when used herein, specify the presence of stated features, elements, components and/or the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. For example, the term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “based at least in part on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The use of an expression such as “A and/or B” can mean either “only A” or “only B” or “both A and B. ” Other definitions, explicit and implicit, may be included below.

In a recent 3GPP RAN meeting, a work item (WI) was approved for sidelink enhancement for Rel-18. One objective is for sidelink (SL) transmission on unlicensed band, which is to study the unlicensed channel access mechanism impact on sidelink resource reservation schemes.

To co-exist with other radio access technology (RAT) e.g. WiFi, new radio (NR) -SL needs to perform Listen Before Talk (LBT) to monitor and access a channel before transmission on an unlicensed band. If the LBT succeeds, UE can access the channel and perform transmission. If not, UE will drop the transmission. Further, if a LBT type-1 is successful, UE can occupy the channel for a time period which is called Channel Occupancy Time (COT) . The length of COT depends on the Channel Access Priority Class (CAPC) of the transmission data and LBT duration.

Further, after a COT is initiated, in order to retain the channel as long as possible and to decrease or even skip the channel sensing time, multi-consecutive slot transmission (MCSt) is introduced for SL-U transmission. For UE with mode 2 resource allocation mode (i.e. resources are selected by UE) , UE will reserve multiple consecutive resources for MCSt transmission, and these resources can be used for the same transport block (TB) or a different TB. On the other hand, for UE with mode 1 resource allocation mode, resources used for MCSt transmission is scheduled by gNB dynamically or configured semi-statically e.g. sidelink configured grant resources.

For configured grant (CG) transmission, if there is a potential LBT failure for downlink (DL) feedback or scheduling, UE can autonomously retransmit the TB in the next CG resource with the same HARQ process, after cg-retransmission-timer is expired. When cg-retx-timer is configured, autonomous retransmission is enabled, and UE will select HARQ process id by itself for CG.

Solutions for autonomous transmission or retransmission for SL MCSt transmission has not been discussed yet and need to be further studied. According to embodiments of the present disclosure, a novel scheme for SL MCSt transmission on unlicensed band is proposed. According to embodiments of the disclosure, a UE transmits transport blocks (TBs) on consecutive resources of a SL MCSt transmission. The consecutive resources may be in granularity of symbol, slot, subframe, etc. When a LBT for the SL MCSt transmission fails, the UE may determine whether to transmit a TB associated with a dropped transmission caused by the LBT failure in the following resources. If so, the UE may retransmit the TB on one of the following resources after a LBT succeeds. In this way, autonomous transmission or retransmission for MCSt on sidelink is enabled when listen before talk (LBT) failure (s) occurs, and the reliability of SL MCSt transmission is improved. In some embodiments, the UE may further trigger resource reselection for TB (s) or data not transmitted on the resources of the MCSt transmission. In this way, the reliability of SL MCSt transmission could be further improved.

FIG. 1 illustrates an example of a wireless communications system 100 in which some embodiments of the present disclosure can be implemented. The wireless communications system 100 may include one or more network entities 102 (also referred to as network equipment (NE) ) , one or more UEs 104, a core network 106, and a packet data network 108. The wireless communications system 100 may support various radio access technologies. In some implementations, the wireless communications system 100 may be a 4G network, such as an LTE network or an LTE-Advanced (LTE-A) network. In some other implementations, the wireless communications system 100 may be a 5G network, such as an NR network. In other implementations, the wireless communications system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technology including Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20. The wireless communications system 100 may support radio access technologies beyond 5G. Additionally, the wireless communications system 100 may support technologies, such as time division multiple access (TDMA) , frequency division multiple access (FDMA) , or code division multiple access (CDMA) , etc.

The one or more network entities 102 may be dispersed throughout a geographic region to form the wireless communications system 100. One or more of the network entities 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a radio access network (RAN) , a base transceiver station, an access point, a NodeB, an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. A network entity 102 and a UE 104 may communicate via a communication link 110, which may be a wireless or wired connection. For example, a network entity 102 and a UE 104 may perform wireless communication (e.g., receive signaling, transmit signaling) over a Uu interface. In a 3GPP non-terrestrial network (NTN) , a network entity 102 in form of a satellite can directly communicate to UE 104 using NR/LTE Uu interface.

A network entity 102 may provide a geographic coverage area 112 for which the network entity 102 may support services (e.g., voice, video, packet data, messaging, broadcast, etc. ) for one or more UEs 104 within the geographic coverage area 112. For example, a network entity 102 and a UE 104 may support wireless communication of signals related to services (e.g., voice, video, packet data, messaging, broadcast, etc. ) according to one or multiple radio access technologies. In some implementations, a network entity 102 may be moveable, for example, a satellite associated with a non-terrestrial network. In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but the different geographic coverage areas 112 may be associated with different network entities 102. Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The one or more UEs 104 may be dispersed throughout a geographic region of the wireless communications system 100. A UE 104 may include or may be referred to as a mobile device, a wireless device, a remote device, a remote unit, a handheld device, or a subscriber device, or some other suitable terminology. In some implementations, the UE 104 may be referred to as a unit, a station, a terminal, or a client, among other examples. Additionally, or alternatively, the UE 104 may be referred to as an Internet-of-Things (IoT) device, an Internet-of-Everything (IoE) device, or machine-type communication (MTC) device, among other examples. In some implementations, a UE 104 may be stationary in the wireless communications system 100. In some other implementations, a UE 104 may be mobile in the wireless communications system 100.

The one or more UEs 104 may be devices in different forms or having different capabilities. Some examples of UEs 104 are illustrated in FIG. 1. A UE 104 may be capable of communicating with various types of devices, such as the network entities 102, other UEs 104, or network equipment (e.g., the core network 106, the packet data network 108, a relay device, an integrated access and backhaul (IAB) node, or another network equipment) , as shown in FIG. 1. Additionally, or alternatively, a UE 104 may support communication with other network entities 102 or UEs 104, which may act as relays in the wireless communications system 100.

A UE 104 may also be able to support wireless communication directly with other UEs 104 over a communication link 114. For example, a UE 104 may support wireless communication directly with another UE 104 over a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link 114 may be referred to as a sidelink. For example, a UE 104 may support wireless communication directly with another UE 104 over a PC5 interface.

A network entity 102 may support communications with the core network 106, or with another network entity 102, or both. For example, a network entity 102 may interface with the core network 106 through one or more backhaul links 116 (e.g., via an S1, N2, N2, or another network interface) . The network entities 102 may communicate with each other over the backhaul links 116 (e.g., via an X2, Xn, or another network interface) . In some implementations, the network entities 102 may communicate with each other directly (e.g., between the network entities 102) . In some other implementations, the network entities 102 may communicate with each other or indirectly (e.g., via the core network 106) . In some implementations, one or more network entities 102 may include subcomponents, such as an access network entity, which may be an example of an access node controller (ANC) . An ANC may communicate with the one or more UEs 104 through one or more other access network transmission entities, which may be referred to as a radio heads, smart radio heads, or transmission-reception points (TRPs) .

In some implementations, a network entity 102 may be configured in a disaggregated architecture, which may be configured to utilize a protocol stack physically or logically distributed among two or more network entities 102, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance) , or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN) ) . For example, a network entity 102 may include one or more of a central unit (CU) , a distributed unit (DU) , a radio unit (RU) , a RAN Intelligent Controller (RIC) (e.g., a Near-Real Time RIC (Near-RT RIC) , a Non-Real Time RIC (Non-RT RIC) ) , a Service Management and Orchestration (SMO) system, or any combination thereof.

An RU may also be referred to as a radio head, a smart radio head, a remote radio head (RRH) , a remote radio unit (RRU) , or a transmission reception point (TRP) . One or more components of the network entities 102 in a disaggregated RAN architecture may be co-located, or one or more components of the network entities 102 may be located in distributed locations (e.g., separate physical locations) . In some implementations, one or more network entities 102 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU) , a virtual DU (VDU) , a virtual RU (VRU) ) .

Split of functionality between a CU, a DU, and an RU may be flexible and may support different functionalities depending upon which functions (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency functions, and any combinations thereof) are performed at a CU, a DU, or an RU. For example, a functional split of a protocol stack may be employed between a CU and a DU such that the CU may support one or more layers of the protocol stack and the DU may support one or more different layers of the protocol stack. In some implementations, the CU may host upper protocol layer (e.g., a layer 3 (L3) , a layer 2 (L2) ) functionality and signaling (e.g., Radio Resource Control (RRC) , service data adaption protocol (SDAP) , Packet Data Convergence Protocol (PDCP) ) . The CU may be connected to one or more DUs or RUs, and the one or more DUs or RUs may host lower protocol layers, such as a layer 1 (L1) (e.g., physical (PHY) layer) or an L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160.

Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU and an RU such that the DU may support one or more layers of the protocol stack and the RU may support one or more different layers of the protocol stack. The DU may support one or multiple different cells (e.g., via one or more RUs) . In some implementations, a functional split between a CU and a DU, or between a DU and an RU may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU, a DU, or an RU, while other functions of the protocol layer are performed by a different one of the CU, the DU, or the RU) .

A CU may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU may be connected to one or more DUs via a midhaul communication link (e.g., F1, F1-c, F1-u) , and a DU may be connected to one or more RUs via a fronthaul communication link (e.g., open fronthaul (FH) interface) . In some implementations, a midhaul communication link or a fronthaul communication link may be implemented in accordance with an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 102 that are in communication via such communication links.

The core network 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The core network 106 may be an evolved packet core (EPC) , or a 5G core (5GC) , which may include a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management functions (AMF) ) and a user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signal bearers, etc. ) for the one or more UEs 104 served by the one or more network entities 102 associated with the core network 106.

The core network 106 may communicate with the packet data network 108 over one or more backhaul links 116 (e.g., via an S1, N2, N2, or another network interface) . The packet data network 108 may include an application server 118. In some implementations, one or more UEs 104 may communicate with the application server 118. A UE 104 may establish a session (e.g., a protocol data unit (PDU) session, or the like) with the core network 106 via a network entity 102. The core network 106 may route traffic (e.g., control information, data, and the like) between the UE 104 and the application server 118 using the established session (e.g., the established PDU session) . The PDU session may be an example of a logical connection between the UE 104 and the core network 106 (e.g., one or more network functions of the core network 106) .

In the wireless communications system 100, the network entities 102 and the UEs 104 may use resources of the wireless communications system 100 (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) ) to perform various operations (e.g., wireless communications) . In some implementations, the network entities 102 and the UEs 104 may support different resource structures. For example, the network entities 102 and the UEs 104 may support different frame structures. In some implementations, such as in 4G, the network entities 102 and the UEs 104 may support a single frame structure. In some other implementations, such as in 5G and among other suitable radio access technologies, the network entities 102 and the UEs 104 may support various frame structures (i.e., multiple frame structures) . The network entities 102 and the UEs 104 may support various frame structures based on one or more numerologies.

One or more numerologies may be supported in the wireless communications system 100, and a numerology may include a subcarrier spacing and a cyclic prefix. A first numerology (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first numerology (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one slot per subframe. A second numerology (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. A third numerology (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth numerology (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth numerology (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a normal cyclic prefix.

A time interval of a resource (e.g., a communication resource) may be organized according to frames (also referred to as radio frames) . Each frame may have a duration, for example, a 10 millisecond (ms) duration. In some implementations, each frame may include multiple subframes. For example, each frame may include 10 subframes, and each subframe may have a duration, for example, a 1 ms duration. In some implementations, each frame may have the same duration. In some implementations, each subframe of a frame may have the same duration.

Additionally or alternatively, a time interval of a resource (e.g., a communication resource) may be organized according to slots. For example, a subframe may include a number (e.g., quantity) of slots. The number of slots in each subframe may also depend on the one or more numerologies supported in the wireless communications system 100. For instance, the first, second, third, fourth, and fifth numerologies (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with respective subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize a single slot per subframe, two slots per subframe, four slots per subframe, eight slots per subframe, and 16 slots per subframe, respectively. Each slot may include a number (e.g., quantity) of symbols (e.g., OFDM symbols) . In some implementations, the number (e.g., quantity) of slots for a subframe may depend on a numerology. For a normal cyclic prefix, a slot may include 14 symbols. For an extended cyclic prefix (e.g., applicable for 60 kHz subcarrier spacing) , a slot may include 12 symbols. The relationship between the number of symbols per slot, the number of slots per subframe, and the number of slots per frame for a normal cyclic prefix and an extended cyclic prefix may depend on a numerology. It should be understood that reference to a first numerology (e.g., μ=0) associated with a first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and slots.

In the wireless communications system 100, an electromagnetic (EM) spectrum may be split, based on frequency or wavelength, into various classes, frequency bands, frequency channels, etc. By way of example, the wireless communications system 100 may support one or multiple operating frequency bands, such as frequency range designations FR1 (410 MHz –7.125 GHz) , FR2 (24.25 GHz –52.6 GHz) , FR3 (7.125 GHz –24.25 GHz) , FR4 (52.6 GHz –114.25 GHz) , FR4a or FR4-1 (52.6 GHz –71 GHz) , and FR5 (114.25 GHz –300 GHz) . In some implementations, the network entities 102 and the UEs 104 may perform wireless communications over one or more of the operating frequency bands. In some implementations, FR1 may be used by the network entities 102 and the UEs 104, among other equipment or devices for cellular communications traffic (e.g., control information, data) . In some implementations, FR2 may be used by the network entities 102 and the UEs 104, among other equipment or devices for short-range, high data rate capabilities.

FR1 may be associated with one or multiple numerologies (e.g., at least three numerologies) . For example, FR1 may be associated with a first numerology (e.g., μ=0) , which includes 15 kHz subcarrier spacing; a second numerology (e.g., μ=1) , which includes 30 kHz subcarrier spacing; and a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing. FR2 may be associated with one or multiple numerologies (e.g., at least 2 numerologies) . For example, FR2 may be associated with a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing; and a fourth numerology (e.g., μ=3) , which includes 120 kHz subcarrier spacing.

FIG. 2 illustrates an example of a process flow in accordance with some example embodiments of the present disclosure. The process flow 200 may involve a user equipment (UE) 201 and a base station 202. The process flow 200 may be applied to the wireless communications system 100 with reference to FIG. 1, for example, the UE 201 and the UE 202 may be UEs 104 which communicate over the sidelink 114. It would be appreciated that the process flow 200 may be applied to other communication scenarios, which will not be described in detail.

The UE 201 may be configured to perform SL transmission on an unlicensed band, using mode 2 i.e. UE autonomous resource selection mode, or Mode 1 i.e.gNB scheduled resource mode. The UE 201 is required to perform a LBT before each sidelink transmission, and obtain channel occupy time (COT) . The UE 201 is configured or enabled multi-consecutive slots transmission (MCSt) transmission, and reserved (in Mode 2) or scheduled (in Mode 1) or configured (in Mode 1 CG) multiple consecutive resources for MCSt (re) transmission.

The UE 201 determines 201, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission. The TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure.

The UE 201 retransmits 220, based on determining to retransmit the TB 225 and via the transceiver, the TB 225 on a resource of the plurality of consecutive resource. Accordingly, the UE 202 receives 230 the TB 225 on the SL channel between UE 201 and UE 202.

FIG. 3 illustrates a schematic diagram of exemplary consecutive resources for MCSt transmission in accordance with some example embodiments of the present disclosure. In FIG. 3, 8 resources are reserved, in which the first four consecutive resources (resource #1, #2, #3, #4) are for the initial transmission of different TBs (e.g. TB #1, #2, #3, #4) and next four consecutive resources (resource #5, #6, #7, #8) are for the retransmission of different TBs (e.g. TB #1, #2, #3, #4) . The reserved resources could be in granularity of symbol, slot, subframe, etc., which could also be called next transmission resource/unit/occasion/slot (s) .

FIG. 4 illustrates a schematic diagram of exemplary retransmission of transport blocks (TBs) in accordance with some example embodiments of the present disclosure. The UE 201 may perform LBT before the transmission. If the LBT succeed, UE 201 may generate and transmit TBs #1, #2, #3, and #4 on the reserved consecutive resources #1, #2, #3, and #4. If the LBT fails, for example, the medium access control (MAC) layer of the UE 201 receives an LBT failure indication from the physical (PHY) layer, the UE 201 may drop the transmission on resource #1 and continue to perform LBT.

The UE 201 may determine to transmit the TB associated with dropped transmission as shown in FIG. 4. This means the UE 201 will autonomously retransmit the TB of the dropped transmission. In this case, if the LBT succeed and if UE determines to retransmit TB #1, UE will transmit TB #1, #2, and #3 on reserved resources #2, #3, and #4. The TB #4 is not transmitted on the MCSt resources #1 to #4. If LBT fails, the UE 201 may drop the next transmission and continue to perform LBT. The same procedure continues for next reserved resources if available. In other hand, if the UE 201 determines or prefers to transmit a new TB (e.g. TB #2) , UE attempts to transmit TB #2, #3 and #4 in reserved resource #2, #3 and #4. If the next LBT succeeds, TB #2, #3 and #4 are transmitted, and TB #1 is not transmitted on the MCSt resources #1 to #4.

For autonomous retransmission, it is not excluded that the dropped TB is retransmitted in the resource after next reserved resource. For example, if TB #1 transmission in the first reserved resource #1 is dropped, the UE 201 may retransmit TB #1 in any of the reserved resources #2 or #3 or #4.

Referring back to FIG. 2 in combination with FIG. 4, in determining 210, UE 201 may determine to retransmit the TB (e.g. TB #1) based on determining that autonomous transmission or retransmission configuration is enabled at the UE 201. For example, the UE 201 may be (pre) configured with a parameter to enable the autonomous (re) transmission of the dropped TB caused by LBT failure. For example, a parameter e.g. sl-autonomousTx or sl-autonomousReTx is (pre) configured for the UE 201. The parameter may be (pre) configured together with MCSt transmission for SL UE. The parameter can be 1 bit, in which value 1 means the UE 201 will perform autonomous retransmission of dropped TB caused by LBT failure in following reserved resource.

In FIG. 4, if LBT fails before the first reserved resource and the UE 201 dropped transmission for the associated TB #1, the UE 201 will retransmit TB #1 in reserved resource #2. On the other hand, value 0 means UE 201 will not perform autonomous retransmission of dropped TB caused by LBT failure. In FIG. 4, if LBT fails before the first reserved resource and UE 201 dropped transmission for TB #1, the UE 201 will transmit a new TB, e.g. TB #2, in reserved resource #2. Alternatively or additionally, autonomous transmission or retransmission configuration may be preconfigured or specified as being enabled by default.

Alternatively or additionally, the UE 201 may determine whether to retransmit the TB (e.g. TB #1) based on a remaining packet delay budget (PDB) of the TB or data in a buffer for MCSt transmission. In some embodiments, if the remaining PDB of the TB associated with the dropped transmission is less than a (pre) configured threshold, autonomous retransmission may be determined as being enabled and the first TB will be retransmitted in next resource if available. For example, in FIG. 4, if LBT fails before the first reserved resource and the UE 201 dropped transmission for TB #1, and if the remaining PDB of TB #1 is less than a threshold_value, the UE 201 may retransmit TB #1 in reserved resource #2. Otherwise, the UE 201 may transmit a new TB (e.g. TB #2) in the reserved resource #2.

In some embodiments, the UE 201 may compare the remaining PDB of the TB (e.g. TB #1) associated with the dropped transmission e.g. PDB_remain_droppedTB, and the remaining PDB of the generated TB (e.g. TB #4) that will not be transmitted e.g. PDB_remain_untransmitTB, or the remaining PDB of the data in the buffer e.g. PDB_remain_bufferreddata. If PDB_remain_droppedTB < PDB_remain_untransmitTB, or if PDB_remain_droppedTB < PDB_remain_bufferreddata, the UE may determine to retransmit TB #1 in reserved resource #2 as shown in FIG. 4. Otherwise, the UE 201 may determine not to transmit TB #1, and to transmit a new TB (e.g. TB #2) in reserved resource #2.

Alternatively or additionally, the UE 201 may determine whether to retransmit the TB (e.g. TB #1) based on a priority of the TB. If the priority of the TB associated with the dropped transmission is larger than a (pre) configured threshold, the UE 201 may determine that autonomous retransmission is enabled and determine to retransmit the TB. Therefore, TB #1 will be retransmitted in next resource if available. For example, in FIG. 4, if LBT fails before the first reserved resource #1 and the UE 201 drops the transmission for TB #1 on that resource, and if the priority of TB #1 is larger than a threshold_value, the UE 201 may retransmit TB #1 in the reserved resource #2 if available after a successful LBT. Otherwise, the UE 201 may transmit a new TB (e.g. TB #2) in the reserved resource #2.

As mentioned, in Mode 1, the resources for the MCSt transmission may be configured grant (CG) resources. That is, the consecutive resources are scheduled or configured by a base station (e.g. gNB) for SL MCSt transmission. In some embodiments, the CG resources may be allowed for retransmission in SL MCSt.

When the LBT fails, e.g. the MAC layer of the UE 201 receives an indication of LBT failure from a lower layer (e.g. physical layer) for the MCSt transmission, the UE 201 may drop transmission of the TB (e.g. TB #1) on the approaching resource (e.g. resource #1) . Then optionally, the UE 201 may consider an SL process for Hybrid Automatic Repeat request (HARQ) associated with dropped transmission is pending (an SL process may also be referred as a sidelink (SL) HARQ process) , which means no new TB can be transmitted in this SL process.

If a following reserved resource for MCSt is used for retransmission, the UE 201 may reuse the same SL process and corresponding process identity (ID) for the retransmission of the TB as for the dropped transmission. The UE 201 further (re) transmits the TB on the same SL process on the following MCSt resources, or in other words, the following reserved resources for MCSt transmission, even it is reserved for initial transmission, or even it is SL-CG resources for MCSt.

In some embodiments, the reusing of SL process and the corresponding ID for retransmission may happens when one or more following conditions are fulfilled: an indication of the at least one LBT failure is received for a previous SL grant for the SL process; or a medium access control (MAC) protocol data unit (PDU) size of the TB matches (e.g. equal to or less than) a SL grant size. Alternatively or additionally, when the resources are CG resources, the conditions may require that a configured grant in a next resource belongs to a list of SL allowed configured grants (e.g. sl-AllowedCG-List) of logical channels in the TB.

With reference to FIG. 2, the UE 201 may optionally trigger 240 resource reselection. When the LBT fails before the MCSt transmission and the UE 201 dropped transmission on one or more reserved resources for MCSt transmission, the UE 201 may further trigger resource reselection for data in the buffer or generated TB (s) that is supposed to be but not transmitted on the resources of the MCSt transmission. Herein a generated TB may be in form of MAC PDU and comprise multiplexed data from multiple logical channels obtained from the buffer. Therefore, a generated TB may also be referred as a multiplexed TB.

FIG. 5 illustrates a schematic diagram of exemplary resource reselection trigger in accordance with some example embodiments of the present disclosure. As shown, a generated TB #4 or data in the buffer is not transmitted because of the retransmission of the TB #1 on the resource #2. The UE 201 may trigger resource reselection for the generated TB #4 or the data in the buffer. If the TB #1 is not retransmitted, the UE 201 may trigger resource reselection for the TB #1.

In some embodiments, the UE 201 may trigger resource reselection when one or more following conditions are fulfilled: an indication of at least one LBT failure is received from a physical (PHY) layer; no more resources for SL MCSt transmission are reserved; a number of slots of the next MCSt resource is not enough, e.g. less than current MCSt resource, or less than a threshold; the next MCSt resource is too far, e.g. beyond or larger than the remaining PDB of the generated TB or data in the buffer; the remaining PDB of the generated TB or the data in the buffer is less than a threshold; or not reach sl-CG-MaxTransNum for a specific SL process. The sl-CG-MaxTransNum denotes a maximum of transmissions for a SL configured grant.

FIG. 6 illustrates a schematic diagram of timings for resource reselection trigger in accordance with some example embodiments of the present disclosure. As shown, for Case 1, the resource reselection may be triggered whenever an indication of the at least one LBT failure is received from the PHY layer of the UE. Alternatively, the resource reselection may be triggered when an indication of a LBT success is received from the PHY layer of the UE. Alternatively, the resource reselection is triggered after the SL MCSt transmission is completed.

According to some embodiments discussed with reference to FIGS. 2 to 6, a UE may perform autonomous retransmission for sidelink MCSt transmission on unlicensed band with LBT enabled. When a LBT failure occurs, the UE may determine whether to retransmit a TB associated with a dropped transmission by the LBT failure. If so, the UE may retransmit the TB on a following available resource after LBT succeeds. As such, the reliability of SL MCSt transmission is improved.

FIG. 7 illustrates another example of a device that is suitable for implementing some embodiments of the present disclosure. The device 700 may be an example of a UE 104 as described herein. The device 700 may support wireless communication with one or more network entities 102, UEs 104, or any combination thereof. The device 700 may include components for bi-directional communications including components for transmitting and receiving communications, such as a processor 702, a memory 704, a transceiver 706, and, optionally, an I/O controller 708. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 702, the memory 704, the transceiver 706, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. For example, the processor 702, the memory 704, the transceiver 706, or various combinations or components thereof may support a method for performing one or more of the operations described herein.

In some implementations, the processor 702, the memory 704, the transceiver 706, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry) . The hardware may include a processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some implementations, the processor 702 and the memory 704 coupled with the processor 702 may be configured to perform one or more of the functions described herein (e.g., executing, by the processor 702, instructions stored in the memory 704) .

For example, the processor 702 may support wireless communication at the device 700 in accordance with examples as disclosed herein. The processor 702 may be configured to operable to support means for determining, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure, and means for retransmitting, based on determining to retransmit the TB and via the transceiver 706, the TB on a resource of the plurality of consecutive resources.

The processor 702 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some implementations, the processor 702 may be configured to operate a memory array using a memory controller. In some other implementations, a memory controller may be integrated into the processor 702. The processor 702 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 704) to cause the device 700 to perform various functions of the present disclosure.

The memory 704 may include random access memory (RAM) and read-only memory (ROM) . The memory 704 may store computer-readable, computer-executable code including instructions that, when executed by the processor 702 cause the device 700 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some implementations, the code may not be directly executable by the processor 702 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some implementations, the memory 704 may include, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The I/O controller 708 may manage input and output signals for the device 700. The I/O controller 708 may also manage peripherals not integrated into the device 700. In some implementations, the I/O controller 708 may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller 708 may utilize an operating system such as or another known operating system. In some implementations, the I/O controller 708 may be implemented as part of a processor, such as the processor 702. In some implementations, a user may interact with the device 700 via the I/O controller 708 or via hardware components controlled by the I/O controller 708.

In some implementations, the device 700 may include a single antenna 710. However, in some other implementations, the device 700 may have more than one antenna 710 (i.e., multiple antennas) , including multiple antenna panels or antenna arrays, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 706 may communicate bi-directionally, via the one or more antennas 710, wired, or wireless links as described herein. For example, the transceiver 706 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 706 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 710 for transmission, and to demodulate packets received from the one or more antennas 710. The transceiver 706 may include one or more transmit chains, one or more receive chains, or a combination thereof.

A transmit chain may be configured to generate and transmit signals (e.g., control information, data, packets) . The transmit chain may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM) , frequency modulation (FM) , or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM) . The transmit chain may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmit chain may also include one or more antennas 710 for transmitting the amplified signal into the air or wireless medium.

A receive chain may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receive chain may include one or more antennas 710 for receive the signal over the air or wireless medium. The receive chain may include at least one amplifier (e.g., a low-noise amplifier (LNA) ) configured to amplify the received signal. The receive chain may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receive chain may include at least one decoder for decoding the processing the demodulated signal to receive the transmitted data.

FIG. 8 illustrates an example of a processor 800 is suitable for implementing some embodiments of the present disclosure. The processor 800 may be an example of a processor configured to perform various operations in accordance with examples as described herein. The processor 800 may include a controller 802 configured to perform various operations in accordance with examples as described herein. The processor 800 may optionally include at least one memory 804. Additionally, or alternatively, the processor 800 may optionally include one or more arithmetic-logic units (ALUs) 800. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 800 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 800) or other memory (e.g., random access memory (RAM) , read-only memory (ROM) , dynamic RAM (DRAM) , synchronous dynamic RAM (SDRAM) , static RAM (SRAM) , ferroelectric RAM (FeRAM) , magnetic RAM (MRAM) , resistive RAM (RRAM) , flash memory, phase change memory (PCM) , and others) .

The controller 802 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 800 to cause the processor 800 to support various operations in accordance with examples as described herein. For example, the controller 802 may operate as a control unit of the processor 800, generating control signals that manage the operation of various components of the processor 800. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

The controller 802 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 804 and determine subsequent instruction (s) to be executed to cause the processor 800 to support various operations in accordance with examples as described herein. The controller 802 may be configured to track memory address of instructions associated with the memory 804. The controller 802 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 802 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 800 to cause the processor 800 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 802 may be configured to manage flow of data within the processor 800. The controller 802 may be configured to control transfer of data between registers, arithmetic logic units (ALUs) , and other functional units of the processor 800.

The memory 804 may include one or more caches (e.g., memory local to or included in the processor 800 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementation, the memory 804 may reside within or on a processor chipset (e.g., local to the processor 800) . In some other implementations, the memory 804 may reside external to the processor chipset (e.g., remote to the processor 800) .

The memory 804 may store computer-readable, computer-executable code including instructions that, when executed by the processor 800, cause the processor 800 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. The controller 802 and/or the processor 800 may be configured to execute computer-readable instructions stored in the memory 804 to cause the processor 800 to perform various functions (e.g., functions or tasks supporting transmit power prioritization) . For example, the processor 800 and/or the controller 802 may be coupled with or to the memory 804, the processor 800, the controller 802, and the memory 804 may be configured to perform various functions described herein. In some examples, the processor 800 may include multiple processors and the memory 804 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

The one or more ALUs 806 may be configured to support various operations in accordance with examples as described herein. In some implementation, the one or more ALUs 806 may reside within or on a processor chipset (e.g., the processor 800) . In some other implementations, the one or more ALUs 806 may reside external to the processor chipset (e.g., the processor 800) . One or more ALUs 806 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 806 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 806 be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Additionally, or alternatively, the one or more ALUs 806 may support logical operations such as AND, OR, exclusive-OR (XOR) , not-OR (NOR) , and not-AND (NAND) , enabling the one or more ALUs 806 to handle conditional operations, comparisons, and bitwise operations.

The processor 800 may support wireless communication in accordance with examples as disclosed herein. The processor 802 may be configured to operable to support means for determining, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and means for retransmitting, based on determining to retransmit the TB and via the transceiver, the TB on a resource of the plurality of consecutive resources.

FIG. 9 illustrates a flowchart of a method 900 performed by a UE in accordance with aspects of the present disclosure. The operations of the method 900 may be implemented by a device or its components as described herein. For example, the operations of the method 900 may be performed by a UE 104 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 910, the method may include determining, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure. The operations of 910 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 910 may be performed by a UE 104 as described with reference to FIG. 1.

At 920, the method may include retransmitting, based on determining to retransmit the TB, the TB on a resource of the plurality of consecutive resources. The operations of 920 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 920 may be performed by a UE 104 as described with reference to FIG. 1.

In some embodiments, determining whether to retransmit the TB may comprise: determining to retransmit the TB based on determining that autonomous transmission or retransmission configuration is enabled at the UE.

In some embodiments, determining whether to retransmit the TB may comprise: determine whether to retransmit the TB based on a remaining packet delay budget (PDB) of the TB.

In some embodiments, determining whether to retransmit the TB based on the remaining PDB may comprise: determining to retransmit the TB based on determining that the remaining PDB of the TB is less than a threshold.

In some embodiments, determining whether to retransmit the TB based on the remaining PDB may comprise: comparing the remaining PDB of the TB with a remaining PDB of a generated TB or data in a buffer for MCSt transmission to be dropped due to a retransmission of the TB; and based on determining that the remaining PDB of the TB is less than the remaining PDB of the generated TB or the data in the buffer, determining to retransmit the TB.

In some embodiments, determining whether to retransmit the TB may comprise: determining to retransmit the TB based on determining that a priority of the TB is larger than a threshold.

In some embodiments, the plurality of consecutive resources may be a plurality of configured grant (CG) resources.

In some embodiments, the method further comprise reusing a same SL process and corresponding process identity (ID) for the retransmission of the TB as for the dropped transmission.

In some embodiments, the reusing of the same SL process and the corresponding process ID for the retransmission of the TB may be based on determining one or more of the following: an indication of the at least one LBT failure is received for a previous SL grant for the HARQ and SL process; a medium access control (MAC) protocol data unit (PDU) size of the TB matches a SL grant size; or a configured grant in a next resource belongs to a list of SL allowed configured grants.

In some embodiments, the TB is a first TB, and the processor may be further configured to: transmit, based on determining not to retransmit the first TB and via the transceiver, a second TB on the resource.

In some embodiments, the method may comprise triggering resource reselection.

In some embodiments, the triggering of the resource reselection may be based on determining one of the following: an indication of the at least one LBT failure is received from a physical (PHY) layer of the UE; no more resources for SL MCSt transmission are reserved; a number of resources of a next SL MCSt transmission is less than the current SL MCSt transmission or a threshold; the resources of the next SL MCSt transmission are beyond a remaining PDB of a generated TB or data in a buffer for MCSt transmission; the remaining PDB of the generated TB or the data in the buffer is less than a threshold; or a number of transmissions of the generated TB does not reach a maximum of transmissions for a SL configured grant.

In some embodiments, the resource reselection may be triggered when an indication of the at least one LBT failure is received from the PHY layer of the UE. In some implementations of the method and the UE described herein, the resource reselection may be triggered when an indication of a LBT success is received from the PHY layer of the UE. In some implementations of the method and the UE described herein, the resource reselection may be triggered after the SL MCSt transmission is completed.

In some embodiments, the plurality of consecutive resources may be in one of the following: symbols, slots, or subframes.

It should be noted that the methods described herein describes possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. By way of example, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

As used herein, including in the claims, an article “a” before an element is unrestricted and understood to refer to “at least one” of those elements or “one or more” of those elements. The terms “a, ” “at least one, ” “one or more, ” and “at least one of one or more” may be interchangeable. As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” or “one or both of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. Further, as used herein, including in the claims, a “set” may include one or more elements.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A user equipment (UE) comprising:

a processor; and

a transceiver coupled to the processor,

wherein the processor is configured to:

determine, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and

retransmit, based on determining to retransmit the TB and via the transceiver, the TB on a resource of the plurality of consecutive resources.
The UE of claim 1, wherein determining whether to retransmit the TB comprises:

determining to retransmit the TB based on determining that autonomous transmission or retransmission configuration is enabled at the UE.
The UE of claim 1, wherein determining whether to retransmit the TB comprises:

determine whether to retransmit the TB based on a remaining packet delay budget (PDB) of the TB.
The UE of claim 3, wherein determining whether to retransmit the TB based on the remaining PDB comprises:

determining to retransmit the TB based on determining that the remaining PDB of the TB is less than a threshold.
The UE of claim 3, wherein determining whether to retransmit the TB based on the remaining PDB comprises:

comparing the remaining PDB of the TB with a remaining PDB of a generated TB or data in a buffer for MCSt transmission to be dropped due to a retransmission of the TB; and

based on determining that the remaining PDB of the TB is less than the remaining PDB of the generated TB or the data in the buffer, determining to retransmit the TB.
The UE of claim 1, wherein determining whether to retransmit the TB comprises:

determining to retransmit the TB based on determining that a priority of the TB is larger than a threshold.
The UE of claim 1, wherein the processor is further configured to:

reuse a same SL process and corresponding process identity (ID) for the retransmission of the TB as for the dropped transmission.
The UE of claim 7, wherein the reusing of the same SL process and the corresponding process ID for the retransmission of the TB is based on determining one or more of the following:

an indication of the at least one LBT failure is received for a previous SL grant for the SL process;

a medium access control (MAC) protocol data unit (PDU) size of the TB matches a SL grant size; or

a configured grant in a next resource belongs to a list of SL allowed configured grants.
The UE of claim 1, wherein the TB is a first TB, and the processor is further configured to:

transmit, based on determining not to retransmit the first TB and via the transceiver, a second TB on the resource.
The UE of claim 1, wherein the processor is further configured to trigger resource reselection.
The UE of claim 10, wherein the triggering of the resource reselection is based on determining one of the following:

an indication of the at least one LBT failure is received from a physical (PHY) layer of the UE;

no more resources for SL MCSt transmission are reserved;

a number of resources of a next SL MCSt transmission is less than the current SL MCSt transmission or a threshold;

the resources of the next SL MCSt transmission are beyond a remaining PDB of a generated TB or data in a buffer for MCSt transmission;

the remaining PDB of the generated TB or the data in the buffer is less than a threshold; or

a number of transmissions of the generated TB does not reach a maximum of transmissions for a SL configured grant.
The UE of claim 11, wherein:

the resource reselection is triggered when an indication of the at least one LBT failure is received from the PHY layer of the UE;

the resource reselection is triggered when an indication of a LBT success is received from the PHY layer of the UE; or

the resource reselection is triggered after the SL MCSt transmission is completed.
A processor for wireless communication, comprising:

at least one memory; and

a controller coupled with the at least one memory and configured to cause the controller to:

determine, at a user equipment (UE) and for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and

retransmit, based on determining to retransmit the TB, the TB on a resource of the plurality of consecutive resources.
A method performed by a user equipment, the method comprising:

determining, for a sidelink (SL) multi-consecutive slot transmission (MCSt) transmission, whether to retransmit a transport block (TB) on a plurality of consecutive resources for the SL MCSt transmission, wherein the TB is associated with a dropped transmission caused by at least one listen before talk (LBT) failure; and

retransmitting, based on determining to retransmit the TB, the TB on a resource of the plurality of consecutive resources.
A computer readable medium having instructions stored thereon, the instructions, when executed by a processor of an apparatus, causing the apparatus to perform the method of claim 14.