WO2023161850A1

WO2023161850A1 - Configuring a sidelink assignment index

Info

Publication number: WO2023161850A1
Application number: PCT/IB2023/051684
Authority: WO
Inventors: Karthikeyan Ganesan; Vijay Nangia; Alexander Golitschek Edler Von Elbwart; Joachim Löhr; Ravi Kuchibhotla
Original assignee: Lenovo (Singapore) Pte. Ltd.
Priority date: 2022-02-23
Filing date: 2023-02-23
Publication date: 2023-08-31

Abstract

Apparatuses, methods, and systems are disclosed for configuring a sidelink assignment index. One method (800) includes configuring (802), at a user equipment ("UE"), a sidelink assignment index that associates a physical sidelink shared channel ("PSSCH") transmission with hybrid automatic repeat request ("HARQ") feedback reception. The method (800) includes determining (804) to update the sidelink assignment index according to a destination identifier ("ID"), a cast type, a HARQ feedback option, or some combination thereof. The method (800) includes transmitting (806) the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

Description

CONFIGURING A SIDELINK ASSIGNMENT INDEX

FIELD

[0001] The subject matter disclosed herein relates generally to wireless communications and more particularly relates to configuring a sidelink assignment index.

BACKGROUND

[0002] In certain wireless communications networks, feedback may be used. In such networks, feedback may be delayed and/or dropped.

BRIEF SUMMARY

[0003] Methods for configuring a sidelink assignment index are disclosed. Apparatuses and systems also perform the functions of the methods. One embodiment of a method includes configuring, at a user equipment (“UE”), a sidelink assignment index that associates a physical sidelink shared channel (“PSSCH”) transmission with hybrid automatic repeat request (“HARQ”) feedback reception. In some embodiments, the method includes determining to update the sidelink assignment index according to a destination identifier (“ID”), a cast type, a HARQ feedback option, or some combination thereof. In certain embodiments, the method includes transmitting the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

[0004] One apparatus for configuring a sidelink assignment index includes a user equipment. In some embodiments, the apparatus includes a processor that: configures a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception; and determines to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof. In various embodiments, the apparatus includes a transmitter that transmits the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0006] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for configuring a sidelink assignment index; [0007] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for configuring a sidelink assignment index;

[0008] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for configuring a sidelink assignment index;

[0009] Figure 4 is a schematic block diagram illustrating one embodiment of a system for mapping a sidelink assignment index counter to each layer 2 (“L2”) destination ID;

[0010] Figure 5 is a schematic block diagram illustrating one embodiment of timing for physical sidelink feedback channel (“PSFCH”)resource determination according to a first option;

[0011] Figure 6 is a schematic block diagram illustrating one embodiment of timing for PSFCH resource determination according to a second option;

[0012] Figure 7 is a schematic block diagram illustrating one embodiment of a system with mapping of a counter (e.g., C SAI) to a cast type; and

[0013] Figure 8 is a flow chart diagram illustrating one embodiment of a method for configuring a sidelink assignment index.

DETAILED DESCRIPTION

[0014] As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code.

[0015] Certain of the functional units described in this specification may be labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. [0016] Modules may also be implemented in code and/or software for execution by various types of processors. An identified module of code may, for instance, include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may include disparate instructions stored in different locations which, when joined logically together, include the module and achieve the stated purpose for the module.

[0017] Indeed, a module of code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different computer readable storage devices. Where a module or portions of a module are implemented in software, the software portions are stored on one or more computer readable storage devices.

[0018] Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0019] More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (“RAM”), a read-only memory (“ROM’), an erasable programmable read-only memory (“EPROM’ or Flash memory), a portable compact disc read-only memory (“CD- ROM’), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0020] Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (“LAN”) or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0021] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.

[0022] Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment.

[0023] Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. The code may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0024] The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0025] The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

[0026] The schematic flowchart diagrams and/or schematic block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods and program products according to various embodiments. In this regard, each block in the schematic flowchart diagrams and/or schematic block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s).

[0027] It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures.

[0028] Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code.

[0029] The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements.

[0030] Figure 1 depicts an embodiment of a wireless communication system 100 for configuring a sidelink assignment index. In one embodiment, the wireless communication system 100 includes remote units 102 and network units 104. Even though a specific number of remote units 102 and network units 104 are depicted in Figure 1, one of skill in the art will recognize that any number of remote units 102 and network units 104 may be included in the wireless communication system 100.

[0031] In one embodiment, the remote units 102 may include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), aerial vehicles, drones, or the like. In some embodiments, the remote units 102 include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units 102 may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, UE, user terminals, a device, or by other terminology used in the art. The remote units 102 may communicate directly with one or more of the network units 104 via uplink (“UL”) communication signals. In certain embodiments, the remote units 102 may communicate directly with other remote units 102 via sidelink communication.

[0032] The network units 104 may be distributed over a geographic region. In certain embodiments, a network unit 104 may also be referred to and/or may include one or more of an access point, an access terminal, a base, a base station, a location server, a core network (“CN”), a radio network entity, a Node-B, an evolved node-B (“eNB”), a 5G node-B (“gNB”), a Home Node-B, a relay node, a device, a core network, an aerial server, a radio access node, an access point (“AP”), new radio (“NR”), a network entity, an access and mobility management function (“AMF”), a unified data management (“UDM”), a unified data repository (“UDR”), a UDM/UDR, a policy control function (“PCF”), a radio access network (“RAN”), a network slice selection function (“NSSF”), an operations, administration, and management (“OAM”), a session management function (“SMF”), a user plane function (“UPF”), an application function, an authentication server function (“AUSF”), security anchor functionality (“SEAF”), trusted non-third generation partnership project (“3GPP”) gateway function (“TNGF”), or by any other terminology used in the art. The network units 104 are generally part of a radio access network that includes one or more controllers communicably coupled to one or more corresponding network units 104. The radio access network is generally communicably coupled to one or more core networks, which may be coupled to other networks, like the Internet and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art.

[0033] In one implementation, the wireless communication system 100 is compliant with NR protocols standardized in 3 GPP, wherein the network unit 104 transmits using an orthogonal frequency division multiplexing (“OFDM”) modulation scheme on the downlink (“DL”) and the remote units 102 transmit on the UL using a single-carrier frequency division multiple access (“SC- FDMA”) scheme or an OFDM scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocol, for example, WiMAX, institute of electrical and electronics engineers (“IEEE”) 802.11 variants, global system for mobile communications (“GSM’), general packet radio service (“GPRS”), universal mobile telecommunications system (“UMTS”), long term evolution (“LTE”) variants, code division multiple access 2000 (“CDMA2000”), Bluetooth®, ZigBee, Sigfoxx, among other protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0034] The network units 104 may serve a number of remote units 102 within a serving area, for example, a cell or a cell sector via a wireless communication link. The network units 104 transmit DL communication signals to serve the remote units 102 in the time, frequency, and/or spatial domain.

[0035] In various embodiments, a remote unit 102 may configure, at a user equipment, a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception. In some embodiments, the remote unit 102 may determine to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof. In certain embodiments, the remote unit 102 may transmit the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report. Accordingly, the remote unit 102 may be used for configuring a sidelink assignment index.

[0036] Figure 2 depicts one embodiment of an apparatus 200 that may be used for configuring a sidelink assignment index. The apparatus 200 includes one embodiment of the remote unit 102. Furthermore, the remote unit 102 may include a processor 202, a memory 204, an input device 206, a display 208, a transmitter 210, and a receiver 212. In some embodiments, the input device 206 and the display 208 are combined into a single device, such as a touchscreen. In certain embodiments, the remote unit 102 may not include any input device 206 and/or display 208. In various embodiments, the remote unit 102 may include one or more of the processor 202, the memory 204, the transmitter 210, and the receiver 212, and may not include the input device 206 and/or the display 208.

[0037] The processor 202, in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor 202 may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor 202 executes instructions stored in the memory 204 to perform the methods and routines described herein. The processor 202 is communicatively coupled to the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212.

[0038] The memory 204, in one embodiment, is a computer readable storage medium. In some embodiments, the memory 204 includes volatile computer storage media. For example, the memory 204 may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory 204 includes nonvolatile computer storage media. For example, the memory 204 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 204 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 204 also stores program code and related data, such as an operating system or other controller algorithms operating on the remote unit 102.

[0039] The input device 206, in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device 206 may be integrated with the display 208, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device 206 includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device 206 includes two or more different devices, such as a keyboard and a touch panel.

[0040] The display 208, in one embodiment, may include any known electronically controllable display or display device. The display 208 may be designed to output visual, audible, and/or haptic signals. In some embodiments, the display 208 includes an electronic display capable of outputting visual data to a user. For example, the display 208 may include, but is not limited to, a liquid crystal display (“LCD”), a light emitting diode (“LED”) display, an organic light emitting diode (“OLED”) display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the display 208 may include a wearable display such as a smart watch, smart glasses, a heads-up display, or the like. Further, the display 208 may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0041] In certain embodiments, the display 208 includes one or more speakers for producing sound. For example, the display 208 may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the display 208 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the display 208 may be integrated with the input device 206. For example, the input device 206 and display 208 may form a touchscreen or similar touch-sensitive display. In other embodiments, the display 208 may be located near the input device 206.

[0042] In certain embodiments, the processor 202: configures a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception; and determines to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof. In various embodiments, the transmitter 210 transmits the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

[0043] Although only one transmitter 210 and one receiver 212 are illustrated, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and the receiver 212 may be any suitable type of transmitters and receivers. In one embodiment, the transmitter 210 and the receiver 212 may be part of a transceiver.

[0044] Figure 3 depicts one embodiment of an apparatus 300 that may be used for configuring a sidelink assignment index. The apparatus 300 includes one embodiment of the network unit 104. Furthermore, the network unit 104 may include a processor 302, a memory 304, an input device 306, a display 308, a transmitter 310, and a receiver 312. As may be appreciated, the processor 302, the memory 304, the input device 306, the display 308, the transmitter 310, and the receiver 312 may be substantially similar to the processor 202, the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212 of the remote unit 102, respectively.

[0045] In certain embodiments, sidelink unlicensed operations may be used and/or a channel access mechanism for sidelink in an unlicensed band may be used.

[0046] In some embodiments, such as in new radio (“NR”), a dynamic codebook hybrid automatic repeat request (“HARQ”) feedback type may be used to count a number of physical downlink shared channel (“PDSCH”) transmissions made and a number of HARQ acknowledgement (“ACK”) (“HARQ-ACK”) and/or non-acknowledgement (“NACK”) (“HARQ-ACK/NACK”) feedback received from a UE. Any missed HARQ-ACK/NACK feedback may be detected using a counter mechanism.

[0047] In various embodiments, sidelink unlicensed operation may introduce delay and dropping of HARQ ACK/NACK feedback. In certain embodiments, dynamic codebook HARQ feedback reporting may be used to account for any missed HARQ-ACK/NACK feedback. In some embodiments, a sidelink dynamic codebook design takes into account multiple destination identifiers (“IDs”) and/or receive (“RX”) UEs, different cast types (e.g., unicast, groupcast, and broadcast), and/or a different groupcast HARQ feedback option (e.g., groupcast HARQ feedback option 1 and groupcast HARQ feedback option 2).

[0048] In certain embodiments, there may be a UE procedure for reporting HARQ-ACK on uplink. In such embodiments, a UE is provided with physical uplink control channel (“PUCCH”) resources or physical uplink shared channel (“PUSCH”) resources to report HARQ-ACK information that the UE generates based on HARQ-ACK information that the UE obtains from PSFCH receptions, or from absence of PSFCH receptions. In such embodiments, the UE reports HARQ-ACK information on a primary cell of the PUCCH group of the cell where the UE monitors a physical downlink control channel (“PDCCH”) for detection of downlink control information (“DCI”) format 3_0.

[0049] In some embodiments, for sidelink (“SL”) configured grant Type 1 or Type 2 PSSCH transmissions by a UE within a time period provided by sl-PeriodCG a UE generates one HARQ- ACK information bit in response to the PSFCH receptions to multiplex in a PUCCH transmission occasion that is after a last time resource in a set of time resources.

[0050] In various embodiments, for PSSCH transmissions scheduled by a DCI format 3 0, a UE generates HARQ-ACK information in response to PSFCH receptions to multiplex in a PUCCH transmission occasion that is after a last time resource in a set of time resources provided by the DCI format 3 0.

[0051] In certain embodiments, from a number of PSFCH reception occasions, a UE generates HARQ-ACK information to report in a PUCCH or PUSCH transmission. The UE can be indicated by a sidelink control information (“SCI”) format to perform one of the following and the UE constructs a HARQ-ACK codeword with HARQ-ACK information, if applicable: 1) for one or more PSFCH reception occasions associated with a SCIformat 2-A with a cast type indicator field value of "10"; 2) generate HARQ-ACK information with the same value as a value of HARQ-ACK information the UE determines from the last PSFCH reception from the number of PSFCH reception occasions corresponding to PSSCH transmissions or, if the UE determines that a PSFCH is not received at the last PSFCH reception occasion and ACK is not received in any of previous PSFCH reception occasions, generate NACK; 3) for one or more PSFCH reception occasions associated with SCI format 2-A with a cast type indicator field value of "01"; 4) generate ACK if the UE determines ACK from at least one PSFCH reception occasion, from the number of PSFCH reception occasions corresponding to PSSCH transmissions, in PSFCH resources corresponding to every identity M_1D of the UEs that the UE expects to receive the PSSCH, otherwise, generate NACK; 5) for one or more PSFCH reception occasions associated with SCI format 2-B or SCI format 2-A with a cast type indicator field value of "11"; and/or 6) generate ACK if the UE determines absence of PSFCH reception for the last PSFCH reception occasion from the number of PSFCH reception occasions corresponding to PSSCH transmissions, otherwise, generate NACK.

[0052] In some embodiments, after a UE transmits PSSCHs and receives PSFCHs in corresponding PSFCH resource occasions, a priority value of HARQ-ACK information is the same as the priority value of the PSSCH transmissions that are associated with the PSFCH reception occasions providing the HARQ-ACK information.

[0053] In various embodiments, a UE generates a NACK when, due to prioritization, the UE does not receive PSFCH in any PSFCH reception occasion associated with a PSSCH transmission in a resource provided by a DCI format 3 0 or, for a configured grant, in a resource provided in a single period and for which the UE is provided a PUCCH resource to report HARQ-ACK information. The priority value of the NACK is the same as the priority value of the PSSCH transmission.

[0054] In certain embodiments, a UE generates a NACK when, due to prioritization, the UE does not transmit a PSSCH in any of the resources provided by a DCI format 3 0 or, for a configured grant, in any of the resources provided in a single period and for which the UE is provided a PUCCH resource to report HARQ-ACK information. The priority value of the NACK is the same as the priority value of the PSSCH that was not transmitted due to prioritization.

[0055] In some embodiments, a UE generates an ACK if the UE does not transmit a physical sidelink control channel (“PSCCH”) with a SCI format 1-A scheduling a PSSCH in any of the resources provided by a configured grant in a single period and for which the UE is provided a PUCCH resource to report HARQ-ACK information. The priority value of the ACK is the same as the largest priority value among the possible priority values for the configured grant.

[0056] In various embodiments, a UE generates an ACK if the UE does not transmit a PSCCH with a SCI format 1-A scheduling a PSSCH in any of the resources provided by a DCI format 3 0 and for which the UE is provided a PUCCH resource to report HARQ-ACK information. The priority value of the ACK is the same as the largest priority value among the possible priority values for the dynamic grant.

[0057] In certain embodiments, for reporting HARQ-ACK information on uplink corresponding to one or multiple PSSCH transmissions with a corresponding SCI format with the field 'HARQ feedback enabled/disabled indicator' set to disabled, the UE generates HARQ-ACK information with the contents instructed by a higher layer. The priority value of the HARQ-ACK information is the same as the priority value of the PSSCH transmission.

[0058] In some embodiments, a UE does not expect to be provided PUCCH resources or PUSCH resources to report HARQ-ACK information that start earlier than T_prep = (IV + 1) ■ (2048 + 144) ■ K ■ 2^-/z ■ T_c after the end of a last symbol of a last PSFCH reception occasion, from a number of PSFCH reception occasions that the UE generates HARQ-ACK information to report in a PUCCH or PUSCH transmission.

[0059] In various embodiments, dynamic code book for sidelink may be enhanced by using a counter to determine pending HARQ feedback per L2 destination ID and cast type. In certain embodiments, a counter may be used to determine pending HARQ feedback for groupcast option 2 (e.g., dedicated ACK/NACK). [0060] In a first embodiment, there may be sidelink dynamic codebook enhancement. According to the first embodiment, a UE maintains a counter C SAI per L2 destination ID to count pending HARQ feedback (e.g., a number of PSSCHs transmitted and a number of HARQ feedback received) and transmit a signaling indication to RX UEs about the pending HARQ feedbacks.

[0061] Figure 4 is a schematic block diagram illustrating one embodiment of a system 400 for mapping a sidelink assignment index counter (e.g., C SAI) to each L2 destination ID. The system 400 includes a UE-1 402, a UE-2 404, a UE-3 406, and a UE-4 408. First communications 410 between the UE-1 402 and the UE-2 404 (e.g., destination ID-1) may use a counter C_SAI-dstl, second communications 412 between the UE-1 402 and the UE-3 406 (e.g., destination ID-2) may use a counter C_SAI-dst2, and third communications 414 between the UE-1 402 and the UE-4 408 (e.g., destination ID-3) may use a counter C_SAI-dst3.

[0062] In a first option of the first embodiment, a UE maintains a counter (e.g., C SAI) per L2 destination ID and at the end of each PSFCH period, PSFCH occasion, and/or PSFCH symbol, the UE updates the counter only with pending HARQ feedback for the corresponding transmitted N PSSCHs (e.g., where the PSFCH symbol and/or occasion is associated with N PSSCH slots). After the UE transmits an updated counter containing pending HARQ feedback from the previous PSFCH period, symbol, and/or occasion in a next sidelink control information (SCI) scheduling PSSCH to the same L2 destination ID, then the UE resets the counter to zero. The UE then updates the counter only at the end of that PSFCH period, symbol, and/or occasion considering a sum of: 1) a number of PSSCHs transmitted in the current PSFCH period; 2) any pending HARQ feedback it signaled to the destination from the previous PSFCH period; and/or 3) how many HARQ feedbacks it received from the RX UEs at the end of the current PSFCH period, symbol, and/or occasion. This process is then repeated in certain embodiments.

[0063] Figure 5 is a schematic block diagram illustrating one embodiment of timing 500 for PSFCH resource determination according to the first option. A first timing 502 indicates the timing if N=4 PSSCH slots associated with a PSFCH symbol, a second timing 504 also indicates the timing if N=4 PSSCH slots associated a PSFCH symbol, and a third timing 506 indicates a PSFCH period of N=4. A first PSFCH symbol 508 is received and includes HARQ feedback corresponding to PSSCH symbols transmitted during the first timing 502. The first PSFCH symbol 508 includes a NACK for PSSCH 2 corresponding to DST-1 and an ACK for PSSCH 3 corresponding to DST-1. Thus, after the first PSFCH symbol 508 is received, the C SAI counter corresponding to DST-1 is updated to a value of 1 (e.g., 2 PSSCH sent minus 1 HARQ ACK received). Moreover, a second PSFCH symbol 510 is received and includes HARQ feedback corresponding to PSSCH symbols transmitted during the second timing 504. The second PSFCH symbol 510 includes an ACK for PSSCH 6 corresponding to DST-1 and an ACK for PSSCH 7 corresponding to DST-1. Thus, after the second PSFCH symbol 510 is received, the C SAI counter corresponding to DST-1 remains at a value of 1 (e.g., 2 PSSCH sent minus 2 HARQ ACK received plus the 1 from the prior C SAI counter carryover).

[0064] In a second option of the first embodiment, the transmit (“TX”) UE may maintain and signal a counter sidelink assignment index (e.g., C SAI) per L2 destination ID to count and/or increment if a number of PSSCH transmission made to a L2 destination ID enabled with HARQ feedback and decrement if corresponding number of HARQ feedback received using PSFCH from that L2 destination ID at the end of each PSFCH period, PSFCH occasion, and/or PSFCH symbol. Thus, C_SAI>0 provides pending HARQ feedback from a L2 destination ID at the end of each PSFCH period, PSFCH occasion, and/or PSFCH symbol. Whenever SCI is scheduling PSSCH transmission with HARQ enabled in SCI, C SAI is signaled as part of the 2nd SCI indicating pending HARQ feedback for that L2 destination ID. In this option, the UE may choose to transmit HARQ feedback using a PSFCH format other than PSFCH format 0. The PSFCH resource for the new PSFCH format may occupy the N*Mset physical resource blocks (“PRBs”) within the subchannel of PSSCH transmission and N denotes number of PSSCH transmitted to the destination ID within the PSFCH period. The PSFCH resource allocation starts from the ascending order of the time slot of PSSCH transmission. The UE may choose the PSFCH format depending on the HARQ ACK/NACK size to the destination ID.

[0065] Figure 6 is a schematic block diagram illustrating one embodiment of timing for PSFCH resource determination according to the second option. A first timing 602 indicates the timing if N=4 PSSCH slots associated with a PSFCH symbol, a second timing 604 also indicates the timing if N=4 PSSCH slots associated a PSFCH symbol, and a third timing 606 indicates a PSFCH period of N=4. A first PSFCH symbol 608 is received and includes HARQ feedback corresponding to PSSCH symbols transmitted during the first timing 602 (e.g., in this figure one of the HARQ feedback symbols is lost). Moreover, a second PSFCH symbol 610 is received and includes HARQ feedback corresponding to PSSCH symbols transmitted during the second timing 604.

[0066] In above two options the C SAI may be signaled in a SCI scheduling PSSCH transmission even with HARQ disabled in SCI. In such case, the C SAI indicates the pending HARQ feedback for previous PSSCH transmission for the same L2 destination ID, which can be from a previous COT. In such case, a PSFCH resource determination may be made according to the PSSCH slot where C SAI was transmitted within the current PSFCH period even though the corresponding PSSCH is not enabled with HARQ. In this case, HARQ ACK/NACK bits transmission to a sourcedestination ID (or TX UE) in a PSFCH resource may be allocated according to frequency first and code second. The number of code domain cyclic shift pairs may be configured (e.g., preconfigured) in a resource pool.

[0067] In a third option, there may be unicast plus groupcast HARQ feedback option 2 (e.g., dedicated ACK/NACK feedback resource). In a first implementation of the third option, the TX UE may maintain and signal a ’counter sidelink assignment index - C SAI’ per L2 destination ID and/or cast type (e.g., unicast and groupcast). For groupcast feedback option 2, providing a dedicated ACK/NACK resource for each group member, the counter is incremented once if a PSSCH groupcast transmission is made to a L2 destination ID enabled with HARQ feedback option 2 and then the counter is decremented if the TX UE determines an ACK value from at least one PSFCH reception occasion from the number of PSFCH reception occasions in PSFCH resources corresponding to every identity M 'TD" of UEs, otherwise the TX UE determines as NACK. In this option, the counter is decremented only if an ACK value is received from all group members, otherwise the counter is not decremented.

[0068] Figure 7 is a schematic block diagram illustrating one embodiment of a system 700 with mapping of a counter (e.g., C_SAI) to a cast type. The system 700 includes a UE-1 702 and a UE-2 704. First communications 706 between the UE-1 702 and the UE-2 704 (e.g., destination ID- 1) may use a counter C SAI-unicast, and second communications 708 between the UE-1 702 and the UE-2 704 (e.g., destination ID-1) may use a counter C_S Al -groupcast.

[0069] In a second implementation of the third option, a TX UE may maintain and signal a ’counter sidelink assignment index - C SAI’ per L2 destination ID and/or cast type (e.g., unicast and groupcast) and a ‘total member counter sidelink assignment index’ per destination id which may be indicating the total number of group members in the groupcast HARQ feedback option 2.

[0070] For groupcast, feedback option 2 provides dedicated ACK/NACK resource for each group member, a counter sidelink assignment index (e.g., C SAI) is incremented once if a PSSCH groupcast transmission is made to a L2 destination ID enabled with HARQ feedback option 2 and then the counter is decremented if the TX UE determines an ACK value from at least one PSFCH reception occasion from the number of PSFCH reception occasions in PSFCH resources corresponding to every identity M_"ID” of UEs or if T SAI becomes zero, otherwise the TX UE determines as NACK and the counter is not decremented.

[0071] In certain embodiments, for a total member counter sidelink assignment index (“T SAI”), the counter is set according to a maximum number of the group members in that destination ID, and the counter is decremented only if an ACK value is received from at least one PSFCH reception occasion from the number of PSFCH reception occasions in PSFCH resources from every M 'TD” of UEs. If T SAI = 0, then all group member UEs transmitted HARQ feedback report and if T SAI > 0 means there is pending HARQ feedback from at least one group member UEs. For example, C SAI = 1, and T SAI = 2 indicates HARQ feedback is pending from two group member UEs corresponding to the previous groupcast PSSCH transmission. T SAI is reset to zero if HARQ feedback is received from all group member UEs.

[0072] In some embodiments, a TX UE signals pending HARQ feedback to each of the group member UEs separately. In one example, the SCI scheduling unicast PSSCH for the same destination may also signal the pending HARQ feedback for the groupcast.

[0073] In various embodiments, a TX UE may maintain and signal different counters of C SAI for unicast and groupcast PSSCH transmission even for the same destination ID and/or for different destination IDs.

[0074] In certain embodiments, T SAI may be set to zero for unicast and groupcast HARQ feedback option-1 (e.g., common NACK feedback resource).

[0075] In some embodiments, if C SAI = 0 and T_ SAI > 0, then a UE may ignore the T SAI and does not transmit any pending HARQ feedback. In other words, the UE is not expected to receive C SAI = 0 and T_ SAI > 0 if requested to transmit any pending HARQ feedback.

[0076] In various embodiments, for groupcast HARQ feedback option-1 (e.g., common NACK feedback resource): a TX UE may count and/or increment C SAI if a number of PSSCH transmissions made to a L2 destination ID is enabled with HARQ feedback option- 1 and decrement if no HARQ feedback is received (or absence of PSFCH reception for the PSFCH reception occasion), otherwise C SAI is not decremented which implies there is a pending HARQ ACK/NACK feedback.

[0077] In certain embodiments, a dynamic codebook enable and/or disable may be configured (or preconfigured) in a resource pool. In some embodiments, C SAI and T SAI may be signaled in a 2nd SCI. In various embodiments, C SAI may be signaled in a 2nd SCI; however, T SAI may be signaled in a medium access control (“MAC”) control element (“CE”). MAC CE and SCI are transmitted in the same slot, in some embodiments.

[0078] In a second embodiment, non-numerical HARQ feedback and one shot HARQ feedback may be used. According to the second embodiment, C-SAI and T SAI may account for PSSCHs allocated with a non-numerical feedback value and, if a trigger is transmitted by a TX UE to request a HARQ feedback report for PSSCHs previously allocated with non-numerical HARQ feedback, the C SAI and T SAI may provide the pending HARQ feedback report according to a destination ID, a cast type, and/or a HARQ feedback option.

[0079] In various embodiments, C SAI and T SAI may be reset to zero after receiving a one shot HARQ feedback report or after transmitting a one shot HARQ feedback request.

[0080] Figure 8 is a flow chart diagram illustrating one embodiment of a method 800 for configuring a sidelink assignment index. In some embodiments, the method 800 is performed by an apparatus, such as the remote unit 102. In certain embodiments, the method 800 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0081] In various embodiments, the method 800 includes configuring 802, at a user equipment, a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception. In some embodiments, the method 800 includes determining 804 to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof. In certain embodiments, the method 800 includes transmitting 806 the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

[0082] In certain embodiments, the method 800 further comprises receiving the HARQ feedback report. In some embodiments, the method 800 further comprises updating the sidelink assignment index after a PSFCH period based on the HARQ feedback report. In various embodiments, the method 800 further comprises incrementing the sidelink assignment index after a HARQ feedback enabled PSSCH transmission and decrementing the sidelink assignment index based on the HARQ feedback report.

[0083] In one embodiment, the method 800 further comprises determining that the sidelink assignment index is to be incremented after a HARQ feedback enabled PSSCH transmission and decremented after the HARQ feedback report is received from all group member UEs. In certain embodiments, the method 800 further comprises configuring a total sidelink assignment index according to all group member UEs in a destination, wherein the total sidelink assignment index is decremented in response to the HARQ feedback report being received from all group member UEs. In some embodiments, the method 800 further comprises setting a total sidelink assignment index to zero for unicast and for a first groupcast HARQ feedback option.

[0084] In various embodiments, the method 800 further comprises signaling a total sidelink assignment index for pending groupcast HARQ feedback to each member UE of a group of member UEs separately. In one embodiment, the method 800 further comprises signaling a total sidelink assignment index for pending groupcast HARQ feedback separately from pending unicast HARQ feedback for a particular destination. In certain embodiments, the method 800 further comprises resetting the sidelink assignment index after signaling the HARQ feedback value in a next SCI scheduling PSSCH and updating the sidelink assignment index at the end of a PSFCH period with missed HARQ feedback from a previous period.

[0085] In one embodiment, an apparatus comprises a UE. The apparatus further comprises: a processor that: configures a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception; and determines to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof; and a transmitter that transmits the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

[0086] In certain embodiments, the apparatus further comprises a receiver that receives the HARQ feedback report.

[0087] In some embodiments, the processor updates the sidelink assignment index after a PSFCH period based on the HARQ feedback report.

[0088] In various embodiments, the processor increments the sidelink assignment index after a HARQ feedback enabled PSSCH transmission and decrementing the sidelink assignment index based on the HARQ feedback report.

[0089] In one embodiment, the processor determines that the sidelink assignment index is to be incremented after a HARQ feedback enabled PSSCH transmission and decremented after the HARQ feedback report is received from all group member UEs.

[0090] In certain embodiments, the processor configures a total sidelink assignment index according to all group member UEs in a destination, wherein the total sidelink assignment index is decremented in response to the HARQ feedback report being received from all group member UEs. [0091] In some embodiments, the processor sets a total sidelink assignment index to zero for unicast and for a first groupcast HARQ feedback option.

[0092] In various embodiments, the processor signals a total sidelink assignment index for pending groupcast HARQ feedback to each member UE of a group of member UEs separately.

[0093] In one embodiment, the processor signals a total sidelink assignment index for pending groupcast HARQ feedback separately from pending unicast HARQ feedback for a particular destination.

[0094] In certain embodiments, the processor resets the sidelink assignment index after signaling the HARQ feedback value in a next SCI scheduling PSSCH and updating the sidelink assignment index at the end of a PSFCH period with missed HARQ feedback from a previous period.

[0095] In one embodiment, a method of a UE comprises: configuring a sidelink assignment index that associates a PSSCH transmission with HARQ feedback reception; determining to update the sidelink assignment index according to a destination ID, a cast type, a HARQ feedback option, or some combination thereof; and transmitting the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report.

[0096] In certain embodiments, the method further comprises receiving the HARQ feedback report.

[0097] In some embodiments, the method further comprises updating the sidelink assignment index after a PSFCH period based on the HARQ feedback report.

[0098] In various embodiments, the method further comprises incrementing the sidelink assignment index after a HARQ feedback enabled PSSCH transmission and decrementing the sidelink assignment index based on the HARQ feedback report.

[0099] In one embodiment, the method further comprises determining that the sidelink assignment index is to be incremented after a HARQ feedback enabled PSSCH transmission and decremented after the HARQ feedback report is received from all group member UEs.

[0100] In certain embodiments, the method further comprises configuring a total sidelink assignment index according to all group member UEs in a destination, wherein the total sidelink assignment index is decremented in response to the HARQ feedback report being received from all group member UEs.

[0101] In some embodiments, the method further comprises setting a total sidelink assignment index to zero for unicast and for a first groupcast HARQ feedback option. [0102] In various embodiments, the method further comprises signaling a total sidelink assignment index for pending groupcast HARQ feedback to each member UE of a group of member UEs separately.

[0103] In one embodiment, the method further comprises signaling a total sidelink assignment index for pending groupcast HARQ feedback separately from pending unicast HARQ feedback for a particular destination.

[0104] In certain embodiments, the method further comprises resetting the sidelink assignment index after signaling the HARQ feedback value in a next sidelink control information (SCI) scheduling PSSCH and updating the sidelink assignment index at the end of a PSFCH period with missed HARQ feedback from a previous period.

[0105] Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An apparatus comprising: a processor; and a memory coupled to the processor, the memory comprising instructions executable by the processor to cause the apparatus to: configure a sidelink assignment index that associates a physical sidelink shared channel (PSSCH) transmission with hybrid automatic repeat request (HARQ) feedback reception; determine to update the sidelink assignment index according to a destination identifier (ID), a cast type, a HARQ feedback option, or a combination thereof; and transmit the sidelink assignment index to a receiver user equipment (UE) to request transmission of a HARQ feedback report.

2. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to receive the HARQ feedback report.

3. The apparatus of claim 2, wherein the instructions are further executable by the processor to cause the apparatus to update the sidelink assignment index after a physical sidelink feedback channel (PSFCH) period based on the HARQ feedback report.

4. The apparatus of claim 2, wherein the instructions are further executable by the processor to cause the apparatus to increment the sidelink assignment index after a HARQ feedback enabled PSSCH transmission and decrementing the sidelink assignment index based on the HARQ feedback report.

5. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to determine that the sidelink assignment index is to be incremented after a HARQ feedback enabled PSSCH transmission and decremented after the HARQ feedback report is received from all group member UEs. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to configure a total sidelink assignment index according to all group member UEs in a destination, wherein the total sidelink assignment index is decremented in response to the HARQ feedback report being received from all group member UEs. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to set a total sidelink assignment index to zero for unicast and for a first groupcast HARQ feedback option. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to signal a total sidelink assignment index for pending groupcast HARQ feedback to each member UE of a group of member UEs separately. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to signal a total sidelink assignment index for pending groupcast HARQ feedback separately from pending unicast HARQ feedback for a particular destination. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to reset the sidelink assignment index after signaling the HARQ feedback value in a next sidelink control information (SCI) scheduling PSSCH and updating the sidelink assignment index at an end of a PSFCH period with missed HARQ feedback from a previous period. A method of a user equipment (UE), the method comprising: configuring a sidelink assignment index that associates a physical sidelink shared channel (PSSCH) transmission with hybrid automatic repeat request (HARQ) feedback reception; determining to update the sidelink assignment index according to a destination identifier (ID), a cast type, a HARQ feedback option, or some combination thereof; and transmitting the sidelink assignment index to a receiver UE to request transmission of a HARQ feedback report. The method of claim 11, further comprising receiving the HARQ feedback report. The method of claim 12, further comprising updating the sidelink assignment index after a physical sidelink feedback channel (PSFCH) period based on the HARQ feedback report. The method of claim 12, further comprising incrementing the sidelink assignment index after a HARQ feedback enabled PSSCH transmission and decrementing the sidelink assignment index based on the HARQ feedback report. The method of claim 11, further comprising determining that the sidelink assignment index is to be incremented after a HARQ feedback enabled PSSCH transmission and decremented after the HARQ feedback report is received from all group member UEs.