Triggering HARQ-ACK reports on unlicensed spectrum

Abstract

The invention relates to triggering a HARQ-ACK report on an unlicensed spectrum. A method for triggering HARQ-ACK feedback includes: receiving first downlink control information (DCI) for scheduling downlink (DL) transmission from a basic unit, wherein the first DCI includes a first indicator indicating to defer transmission of hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the DL transmission; receiving, from the base unit, a second DCI for scheduling transmission of HARQ-ACK feedback, wherein the second DCI indicates a resource for transmission of HARQ-ACK feedback; and sending HARQ-ACK feedback to the basic unit on the resource indicated by the second DCI.

Description

[0001] This application is a divisional application of the Chinese invention patent application "Triggering HARQ-ACK Report on Unlicensed Spectrum" with PCT application number PCT / CN2018 / 108406, international application date September 28, 2018, and Chinese application number 201880097537.0, which entered the Chinese national phase on March 15, 2021. Technical Field

[0002] The subject matter disclosed herein relates generally to wireless communications and, more particularly, to New Radio (NR) access on unlicensed spectrum (NR-U). Background Art

[0003] The following abbreviations are defined herein, at least some of which are referenced in the following description: 3rd Generation Partnership Project (3GPP), cyclic redundancy check (CRC), downlink (DL), evolved Node B (eNB), European Telecommunications Standards Institute (ETSI), enhanced interference management and traffic adaptation (eIMTA), frequency division duplex (FDD), frequency division multiple access (FDMA), hybrid automatic repeat request acknowledgement (HARQ-ACK), long term evolution (LTE), multiple access (MA), next generation Node B (gNB), new radio (NR), negative acknowledgement (NACK), orthogonal frequency division multiplexing (OFDM), physical resource block (PRB), physical downlink shared channel (PDSCH), physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), positive acknowledgement (ACK), radio resource Control (RRC), Reference Signal (RS), Single Carrier Frequency Division Multiple Access (SC-FDMA), System Information (SI), Signal-to-Interference and Noise Ratio (SINR), Transport Block (TB), Time Division Duplex (TDD), Time Division Multiplexing (TDM), User Entity / Equipment (Mobile Terminal) (UE), Uplink (UL), Uplink Control Information (UCI), Universal Mobile Telecommunications System (UMTS), Ultra-Reliable and Low Latency Communications (URLLC) and Worldwide Interoperability for Microwave Access (WiMAX), Downlink Control Information (DCI), Code Block (CB), Code Block Group (CBG), Downlink Assignment Index (DAI), CBG Transmission Information (CBGTI), New Data Indicator (NDI), Semi-Persistent Scheduling (SPS), Listen Before Talk (LBT), Channel Occupancy Time (COT), and Downlink Association Set (DAS).

[0004] In LTE LAA, HARQ-ACK feedback is sent on the licensed carrier via PUCCH or PUSCH. However, for NR access on unlicensed spectrum, HARQ-ACK feedback is required to be sent in dual connectivity (DC), CA or standalone deployment scenarios, which has been included in the target deployment scenarios for NR access on unlicensed spectrum (NR-U).

[0005] When HARQ-ACK feedback is to be sent on an unlicensed carrier, LBT needs to be performed first before sending the HARQ-ACK feedback. Only if LBT succeeds, the UE can start HARQ-ACK transmission. Otherwise, the UE must give up sending HARQ-ACK feedback. If the UE cannot send HARQ-ACK feedback due to LBT failure, the gNB must resend the corresponding PDSCH because it does not know the decoding result of the PDSCH at the UE end.

[0006] Additionally, the transmission of HARQ-ACK feedback on the unlicensed carrier may suffer from potential interference from other nodes where the current node is hidden. Even if the UE has successfully sent the HARQ-ACK feedback, the gNB may still not be able to decode it. From the gNB perspective, if the gNB cannot detect the HARQ-ACK feedback in the predefined HARQ-ACK feedback timing, the gNB will have to assume NACK and retransmit all corresponding PDSCHs. Both LBT failures and hidden node issues may lead to unnecessary DL retransmissions and DL performance degradation due to HARQ-ACK reception failure at the gNB end. Summary of the invention

[0007] A method and apparatus for triggering HARQ-ACK feedback are disclosed.

[0008] One aspect of the present disclosure relates to a method, comprising: receiving a first DCI for scheduling DL transmission from a base unit, wherein the first DCI includes a first indicator indicating to suspend transmission of HARQ-ACK feedback corresponding to the DL transmission; receiving a second DCI for scheduling transmission of HARQ-ACK feedback from the base unit, wherein the second DCI indicates resources for transmission of the HARQ-ACK feedback; and sending the HARQ-ACK feedback to the base unit on the resources indicated by the second DCI.

[0009] In some embodiments, the first indicator may indicate a predefined HARQ timing value for postponing the transmission of HARQ-ACK feedback, or a predefined PUCCH resource for postponing the transmission of HARQ-ACK feedback. The first indicator may include a bit for indicating the postponement of the transmission of HARQ-ACK feedback. The first indicator may also include a counter DAI and a total DAI, and the value of the total DAI may be the total number of transmissions with corresponding HARQ-ACK feedback in the same HARQ-ACK codebook as the DL transmission, and the method may further include: in response to the value of the counter DAI being less than the value of the total DAI, determining to postpone the transmission of the HARQ-ACK feedback; and in response to the value of the counter DAI being equal to the value of the total DAI, determining to send the HARQ-ACK feedback.

[0010] In some embodiments, the first DCI may include a HARQ-ACK codebook index, and the value of the HARQ-ACK codebook index may be updated based on another HARQ-ACK codebook. The bit length of the HARQ-ACK codebook index may be determined based on RRC signaling.

[0011] In some embodiments, the second DCI may include a second HARQ-ACK codebook index for scheduling transmission of a corresponding HARQ-ACK codebook.

[0012] In some embodiments, the second DCI may schedule the transmission of HARQ-ACK feedback for the HARQ process by indicating the corresponding HARQ process ID of the HARQ process in the second DCI. The second DCI may include a field for indicating the starting HARQ process ID and another field for indicating the number of consecutive HARQ processes. The second DCI may include a field for indicating the starting HARQ process ID and a plurality of consecutive HARQ processes.

[0013] In some embodiments, the HARQ-ACK feedback may be included in the first HARQ-ACK codebook, and the transmission of the first HARQ-ACK codebook may be postponed in response to the first indicator indicating that the first HARQ-ACK codebook is postponed; and the second DCI may schedule the transmission of the first HARQ-ACK codebook and the retransmission of the second HARQ-ACK codebook, wherein the previous transmission of the second HARQ-ACK codebook was not correctly received by the basic unit. The first and second HARQ-ACK codebooks may be sent in one UCI or in two separate UCIs.

[0014] In some embodiments, the first DCI may include a field for indicating an LBT type for transmission of HARQ-ACK feedback.The first DCI may include a field for indicating an LBT priority category for transmission of HARQ-ACK feedback.

[0015] In some embodiments, the second DCI may include a field for indicating an LBT type for transmission of HARQ-ACK feedback. The second DCI may include a field for indicating an LBT priority category for transmission of HARQ-ACK feedback.

[0016] Another aspect of the present disclosure relates to a method, comprising: sending a first DCI for scheduling DL transmission, wherein the first DCI includes a first indicator indicating that transmission of HARQ-ACK feedback corresponding to the DL transmission is postponed; sending a second DCI for scheduling transmission of HARQ-ACK feedback, wherein the second DCI indicates resources for transmission of HARQ-ACK feedback; and receiving HARQ-ACK feedback sent on the resources indicated by the second DCI.

[0017] Yet another aspect of the present disclosure relates to an apparatus comprising: a receiver that receives a first DCI for scheduling DL transmission, wherein the first DCI includes a first indicator indicating that transmission of HARQ-ACK feedback corresponding to the DL transmission is postponed; and receives a second DCI for scheduling transmission of HARQ-ACK feedback, wherein the second DCI indicates resources for transmission of HARQ-ACK feedback; and a transmitter that sends HARQ-ACK feedback on the resources indicated by the second DCI.

[0018] Another aspect of the present disclosure relates to an apparatus comprising: a transmitter that sends a first DCI for scheduling DL transmission, wherein the first DCI includes a first indicator indicating that transmission of HARQ-ACK feedback corresponding to the DL transmission is postponed; and sends a second DCI for scheduling transmission of HARQ-ACK feedback, wherein the second DCI indicates resources for transmitting the HARQ-ACK feedback; and a receiver that receives the HARQ-ACK feedback sent on the resources indicated by the second DCI. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] A more particular description of the embodiments briefly described above will be specified and illustrated in the accompanying drawings. Reminder that these drawings depict only some embodiments and are therefore not to limit their scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0020] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for retransmitting uplink control information;

[0021] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used to retransmit uplink control information;

[0022] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that may be used to retransmit uplink control information;

[0023] Figure 4 is a schematic block diagram illustrating one embodiment of a HARQ-ACK reporting mechanism triggered by a gNB;

[0024] Figure 5 is a schematic block diagram illustrating another embodiment of a HARQ-ACK reporting mechanism triggered by a gNB;

[0025] Figure 6 is a schematic flow chart illustrating a method for triggering HARQ-ACK feedback for data transmission.

[0026] Figure 7 is a schematic block diagram illustrating another embodiment of a HARQ-ACK reporting mechanism triggered by a gNB. DETAILED DESCRIPTION

[0027] As will be appreciated by those skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Thus, embodiments may include complete hardware, complete software (including firmware, resident software, microcode, etc.), or a mixture, which may generally be referred to herein as a "circuit," "module," or "system." Additionally, embodiments may take the form of a program product embodied in one or more computer-readable storage devices of machine-readable code, computer-readable code, and / or program code, hereinafter referred to as "code." The storage device may be tangible, non-temporary, and / or non-transmitting. The storage device may not embody a signal. In a certain embodiment, the storage device employs only a signal for accessing the code.

[0028] Certain functional units described in this specification may be labeled as "modules" in order to more specifically emphasize their implementation independence. For example, a module may be implemented as a hardware circuit including a custom very large scale integration ("VLSI") circuit or gate array, an off-the-shelf semiconductor such as a logic chip, a transistor, or other discrete components. A module may also be implemented in a programmable hardware device such as a field programmable gate array, a programmable array logic, a programmable logic device, or similar.

[0029] Modules can also be implemented in code and / or software to be executed by various types of processors. The identified code modules can, for example, include one or more physical or logical blocks of executable code, which can be organized as objects, processes or functions. However, the executable files of the identified modules do not need to be physically located together, but can include different instructions stored in different locations, which, when logically connected together, include the modules and achieve the specified purpose for the modules.

[0030] A code module can be a single or many instructions, and can even be distributed in several different code segments, among different programs, and across several memory devices. Similarly, in this article, operating data can be identified and illustrated in a module, and can be embodied in any suitable form and organized in a data structure of any suitable type. This operating data can be collected as a single data set, or can be distributed in different locations, including on different computer-readable storage devices. When a module or part of a module is implemented in software, the software portion is stored on one or more computer-readable storage devices.

[0031] Any combination of one or more computer readable media 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 code. The storage device may be, for example, but need not necessarily be, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical or semiconductor system, apparatus or device, or any suitable combination of the foregoing.

[0032] A non-exhaustive list of more specific examples of storage devices 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.

[0033] The code for performing the operation of the embodiment can be any number of lines and can be written in any combination of one or more programming languages ​​including Python, Ruby, Java, Smalltalk, C++ or similar object-oriented programming languages, and traditional procedural programming languages ​​such as "C" programming languages ​​or similar, and / or machine languages ​​such as assembly languages. The code can be executed entirely on the user's computer, or partially on the user's computer, as a separate software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can 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 can be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0034] References to "one embodiment," "embodiment," or similar language in this specification mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment. Therefore, unless otherwise expressly stated, the phrases "in one embodiment," "in an embodiment," and similar language appearing throughout the specification may, but do not necessarily, all refer to the same embodiment, but rather mean "one or more but not all embodiments." Unless otherwise expressly stated, the terms "include," "comprises," "has," and their variations mean "including but not limited to." Unless otherwise expressly stated, a list of enumerated items does not imply that any or all items are mutually exclusive. Unless otherwise expressly stated, the terms "a," "an," and "the" also mean "one or more."

[0035] In addition, the features, structures or characteristics of the described embodiments may be combined in any suitable manner. In the following description, many 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 the embodiments. However, experts will recognize that the embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring any aspect of the embodiments.

[0036] Various aspects of the embodiments are described below with reference to schematic flow charts and / or schematic block diagrams of the methods, devices, systems, and program products according to the embodiments. It will be understood that each block of the schematic flow charts and / or schematic block diagrams and the combination of blocks in the schematic flow charts and / or schematic block diagrams can be implemented by code. This code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, so that instructions executed by the processor of the computer or other programmable data processing device create a means for implementing the functions / operations specified in the schematic flow charts and / or schematic block diagram blocks or some blocks.

[0037] The code may also be stored in a storage device that is capable of instructing a computer, other programmable data processing apparatus, or other device to operate in a specific manner so that the instructions stored in the storage device produce an article of manufacture including instructions that implement the functions / operations specified in a block or some blocks of the schematic flowchart and / or schematic block diagram.

[0038] The code may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operational steps are performed on the computer, other programmable apparatus, or other device to produce a computer-implemented process, so that the code executed on the computer or other programmable apparatus provides a process for implementing the functions / operations specified in a block or blocks of the flowchart and / or block diagram.

[0039] The schematic flow charts and / or schematic block diagrams in the accompanying drawings illustrate possible implementations of the apparatus, system, method, and program product according to various embodiments, architecture, functions, and operations. In this regard, each block in the schematic flow charts 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 a specified logical function.

[0040] It should also be noted that in some alternative implementations, the functions annotated in the blocks may not occur in the order annotated in the drawings. For example, two blocks shown in succession may be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functions involved. Other steps and methods are contemplated that are equivalent in function, logic, or effect to one or more blocks or portions thereof of the illustrated drawings.

[0041] Although various arrow types and line types can be adopted in flow charts and / or block diagrams, it should be understood that they do not limit the scope of the corresponding embodiments. Some arrows or other connectors can only be used to indicate the logical flow of the depicted embodiment. For example, an arrow can indicate a waiting or monitoring period of unspecified duration between the enumeration steps of the depicted embodiment. It will also be noted that each block of the block diagram and / or flow chart and the combination of the blocks in the block diagram and / or flow chart can be realized by a system based on dedicated hardware or a combination of dedicated hardware and code that performs a specific function or operation.

[0042] The description of an element in each figure may refer to the element of the accompanying figure. In all figures, like numbers refer to like elements, including alternative embodiments of like elements.

[0043] Figure 1 An embodiment of a wireless communication system 100 for CBG-based retransmission is depicted. In one embodiment, the wireless communication system 100 includes a remote unit 102 and a base unit 104. Even if Figure 1 While a particular number of remote units 102 and base units 104 are depicted in FIG. 1 , it should be noted that any number of remote units 102 and base units 104 may also be included in the wireless communication system 100 .

[0044] In one embodiment, the remote unit 102 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant ("PDA"), a tablet computer, a smart phone, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a vehicle-mounted computer, a network device (e.g., a router, a switch, a modem), etc. In some embodiments, the remote unit 102 includes a wearable device such as a smart watch, a fitness band, an optical head-mounted display, etc. The remote unit 102 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a fixed terminal, a subscriber station, a UE, a user terminal, a device, or other terms used in the art. The remote unit 102 may communicate directly with one or more base units 104 via UL communication signals.

[0045] The base units 104 may be distributed over a geographic area. In some embodiments, the base units 104 may also be referred to as access points, access terminals, base stations, base stations, node-Bs, eNBs, gNBs, home node-Bs, relay nodes, devices, core networks, air servers, or any other terminology used in the art. The base units 104 are typically part of a radio access network that includes one or more controllers that are communicatively coupled to one or more corresponding base units 104. The radio access network is typically communicatively coupled to one or more core networks, which may be coupled to other networks, such as networks such as the Internet and a public switched telephone network. These and other elements of the radio access and core networks are not illustrated, but are generally well known to those of ordinary skill in the art.

[0046] In one embodiment, the wireless communication system 100 complies with 3GPP 5G New Radio (NR). However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocol, such as WiMAX or the like.

[0047] The base unit 104 can serve multiple remote units 102 within a service area (eg, a cell or cell sector) via wireless communication links. The base unit 104 sends DL communication signals to serve the remote units 102 in the time, frequency, and / or spatial domains.

[0048] Figure 2 An embodiment of an apparatus 200 that may be used for CBG-based retransmission is depicted. Apparatus 200 includes an embodiment of a remote unit 102. In addition, 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, input device 206 and display 208 are combined into a single device, such as a touch screen. In some embodiments, remote unit 102 may not include any input device 206 and / or display 208. In various embodiments, remote unit 102 may include one or more of processor 202, memory 204, transmitter 210, and receiver 212, and may not include input device 206 and / or display 208.

[0049] In one embodiment, the processor 202 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 a 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.

[0050] In one embodiment, memory 204 is a computer-readable storage medium. In some embodiments, memory 204 includes volatile computer storage media. For example, memory 204 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). In some embodiments, memory 204 includes non-volatile computer storage media. For example, memory 204 may include a hard drive, flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 204 stores data related to system parameters. In some embodiments, memory 204 includes both volatile computer storage media and non-volatile computer storage media. In some embodiments, memory 204 also stores program code and related data, such as an operating system or other controller algorithm operating on remote unit 102.

[0051] In one embodiment, input device 206 may include any known computer input device, including a touchpad, button, keyboard, stylus, microphone, etc. In some embodiments, input device 206 may be integrated with display 208, for example, as a touch screen or similar touch-sensitive display. In some embodiments, input device 206 includes a touch screen so that text can be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, input device 206 includes two or more different devices such as a keyboard and a touchpad.

[0052] In one embodiment, the display 208 may include any known electronically controllable display or display device. The display 208 may be designed to output visual signals, auditory signals, and / or tactile 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, an LCD display, an LED display, an OLED display, a projector, or a similar display device capable of outputting images, text, etc. to a user. As another non-limiting example, the display 208 may include a wearable display such as a smart watch, smart glasses, a head-up display, etc. In addition, the display 208 may be a component of a smart phone, a personal digital assistant, a television, a desktop computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, etc.

[0053] In some embodiments, the display 208 includes one or more speakers for producing sounds. For example, the display 208 can produce an audible alarm or notification (e.g., a beep or chime). In some embodiments, the display 208 includes one or more tactile devices for producing vibration, motion, or other tactile feedback. In some embodiments, all or part of the display 208 can be integrated with the input device 206. For example, the input device 206 and the display 208 can form a touch screen or similar touch-sensitive display. In other embodiments, the display 208 can be located near the input device 206.

[0054] The transmitter 210 is used to provide UL communication signals to the base unit 104, and the receiver 212 is used to receive DL communication signals from the base unit 104. In various embodiments, the receiver 212 can be used to receive broadcast signals. Although only one transmitter 210 and one receiver 212 are shown, the remote unit 102 can have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and the receiver 212 can be any suitable type of transmitter and receiver. In one embodiment, the transmitter 210 and the receiver 212 can be part of a transceiver.

[0055] Figure 3 One embodiment of an apparatus 300 that may be used for CBG-based retransmission is depicted. The apparatus 300 includes one embodiment of the base unit 104. In addition, the base unit 104 may include at least one of a processor 302, a memory 304, an input device 306, a display 308, a transmitter 310, and a receiver 312. It is understood that 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.

[0056] In various embodiments, the transmitter 310 is used to send signaling to the remote unit. Although only one transmitter 310 and one receiver 312 are shown, the base unit 104 can have any suitable number of transmitters 310 and receivers 312. The transmitter 310 and receiver 312 can be any suitable type of transmitter and receiver. In one embodiment, the transmitter 310 and receiver 312 can be part of a transceiver.

[0057] Figure 4 is a schematic block diagram illustrating an embodiment of a gNB-triggered HARQ-ACK reporting mechanism. In the conventional reporting mechanism, when a HARQ-ACK feedback fails to be decoded by the gNB due to LBT failure or hidden node interference, the gNB can trigger the retransmission of the HARQ-ACK feedback through a dedicated DCI or DL ​​grant / UL grant. Figure 4 In the example, the first transmission of HARQ-ACK corresponding to five DL transmissions fails, and then the gNB sends a trigger DCI in the following DL time slot to trigger the retransmission of HARQ-ACK feedback in the indicated UL time slot. However, due to the limitation of the UE's processing capability, not all DL transmissions can be responded with HARQ-ACK feedback, especially for the last several DL transmissions within the same COT. As a result, HARQ-ACK feedback corresponding to those DL transmissions may have to be sent outside the current COT.

[0058] Figure 5 is a schematic block diagram illustrating another embodiment of a gNB-triggered HARQ-ACK reporting mechanism. In this embodiment, due to limitations on the processing capabilities of the UE, the HARQ-ACK feedback corresponding to the last two DL transmissions cannot be sent at the end of the COT. At the same time, the gNB cannot predict when the next COT will start. Therefore, at the time of DL transmission, the gNB cannot schedule the transmission of the HARQ-ACK feedback corresponding to those two DL transmissions. Therefore, the gNB must postpone the transmission of the HARQ-ACK feedback from the UE for those two DL transmissions and trigger the transmission of the HARQ-ACK feedback in the following time slot by triggering the DCI. In this case, the gNB triggers the initial transmission of one HARQ-ACK codebook.

[0059] Described below is an exemplary process for retransmitting uplink control information. The gNB transmits downlink data (downlink transmission) in transport blocks (TBs) on the PDSCH. Since the corresponding HARQ-ACK feedback of multiple PDSCHs is transmitted in one UCI, multiple PDSCHs are configured in one downlink association set. In particular, one or two TBs may be transmitted in one PDSCH. In particular, in single codeword transmission, one TB is transmitted in one PDSCH, whereas in double codeword transmission, two TBs are transmitted in one PDSCH. Multiple PDSCHs may be transmitted in the time domain and / or in multiple component carriers. For example, if a downlink association set is configured with N time slots and the number of configured carriers is C, and assuming that one TB is transmitted in one PDSCH, N*C TBs will be transmitted in one downlink association set.

[0060] For each TB transmitted, the UE shall send a HARQ-ACK on the PUCCH or PUSCH back to the gNB to indicate whether the transmitted TB was successfully received at the UE. The HARQ-ACK may be a positive acknowledgement (ACK), which means that the TB was correctly received at the UE, or a negative acknowledgement (NACK), which means that the TB was erroneously (i.e., incorrectly) received at the UE. Thus, for each TB, one bit may be used as the HARQ-ACK. Multiple HARQ-ACKs may be combined into a HARQ-ACK codebook to be sent together as HARQ-ACK feedback. For example, under the condition that N*C TBs are transmitted in one downlink association set, a HARQ-ACK codebook (or HARQ-ACK feedback) having N*C bits for the downlink association set may be sent back to the gNB, where each bit indicates whether the corresponding one of the N*C TBs was successfully or erroneously received at the UE.

[0061] As described above, when the UE receives multiple TBs in the downlink association set (DAS), it sends a HARQ-ACK codebook (HARQ-ACK feedback) to the gNB to indicate whether the multiple TBs are received correctly or incorrectly at the UE. The transmission of the HARQ-ACK feedback is included in the uplink control information (UCI) transmission. The UCI transmission is made based on the HARQ-ACK timing indication and PUCCH resource indication in the DL assignment.

[0062] Upon receiving UCI, the gNB checks whether the UCI can be decoded correctly. In particular, the CRC of the UCI can be checked. If the UCI can be decoded correctly, i.e., the CRC check is passed, the gNB will further check each bit of the HARQ-ACK codebook, which is ACK or NACK. For each of the NACKs contained in the HARQ-ACK codebook, the gNB will retransmit the corresponding TB indicated by the NACK. If the UCI cannot be decoded correctly, i.e., the CRC check fails, the gNB sends signaling to the UE to indicate that the UCI cannot be decoded correctly. The signaling may include downlink control information (DCI) for scheduling the retransmission of the UCI.

[0063] Traditionally, if the UCI cannot be decoded correctly, the gNB will have to retransmit all TBs (or CBGs) in the downlink association set corresponding to the HARQ-ACK feedback. This is undesirable.

[0064] In one embodiment, if the UCI cannot be correctly decoded, the gNB initiates UCI retransmission by sending DCI so that the UCI including the HARQ-ACK feedback can be retransmitted from the UE to the gNB. A failed CRC check of the UCI only indicates that the UCI was erroneously received at the gNB, and does not necessarily indicate that all TBs (or CBGs) in the downlink association set corresponding to the HARQ-ACK feedback were erroneously received at the UE. As mentioned previously, there may be various reasons that can interfere with the transmission of UCI, which may cause the UCI to be erroneously received at the gNB. Therefore, it is extremely inefficient to retransmit all TBs (or CBGs) in the downlink association set simply because the UCI cannot be decoded at the gNB.

[0065] Figure 6 is a schematic flow diagram illustrating a process for triggering HARQ-ACK feedback for data transmission. In this process, in order to ensure that the downlink data is appropriately sent to the UE, signaling is sent by the gNB to the UE in the form of DCI for scheduling the transmission of the downlink data. The DCI may include an indicator indicating to the UE that HARQ-ACK feedback corresponding to the downlink data is to be sent, such as a HARQ-ACK codebook indicating the transmission status of each of a plurality of PDSCHs in a downlink association set. Alternatively, and more importantly, the indicator of the DCI may also indicate to the UE that HARQ-ACK feedback transmission corresponding to the downlink data, such as some or all of the plurality of PDSCHs in the downlink association set, is to be postponed.

[0066] At step 610, the UE receives a DCI including an indicator from the gNB. The UE also checks the DCI based on information included in the indicator of the received DCI to determine whether to send or postpone HARQ-ACK feedback transmission (step 620). If it is determined that the indicator of the DCI indicates to send HARQ-ACK feedback, the UE continues to send HARQ-ACK feedback for downlink data, such as some or all of the multiple PDSCHs in the downlink association set based on the information included in the DCI (step 630). If it is determined that the indicator of the DCI indicates to postpone the transmission of HARQ-ACK feedback, the UE refuses to send any HARQ-ACK feedback for the downlink data, but waits for further information from the gNB. Upon receiving the next DCI for scheduling the transmission of HARQ-ACK feedback from the gNB, the UE continues to send HARQ-ACK feedback for the downlink data based on the information included in the next DCI (step 650).

[0067] In the present disclosure, specific embodiments of gNB-triggered HARQ-ACK reporting are described for indicating a HARQ process whose corresponding HARQ-ACK feedback was not received by the gNB or was not correctly decoded by the gNB.

[0068] Pending indication for HARQ-ACK feedback

[0069] In one embodiment, a specific value of the pending indication in the K1 set can be used to indicate the postponement of the transmission of HARQ-ACK feedback. Specifically, when it is necessary for the gNB to postpone the HARQ-ACK feedback corresponding to a DL transmission from the UE, the gNB can indicate a "pending indication" in the field of the PDSCH-to-HARQ_feedback timing indicator in the DL grant sent to the UE; when it is necessary for the gNB to trigger HARQ-ACK feedback from the UE, the gNB can indicate a valid PDSCH-to-HARQ_feedback timing indicator in the DL grant sent to the UE. Upon receiving the DL grant, the UE can determine whether to postpone or send HARQ-ACK feedback based on the specific value in the field of the PDSCH-to-HARQ_feedback timing indicator. In some embodiments, the "pending indication" can be a new entry in the field of the PDSCH-to-HARQ_feedback timing indicator in the DL grant. For example, the values ​​shown in the following table can be used for this purpose:

[0070]

[0071] Table 1: Explanation of PDSCH-to-HARQ_feedback timing indicator field

[0072] In another embodiment, an invalid value of a PUCCH resource indicator for indicating a postponement of transmission of HARQ-ACK feedback may be configured in a PUCCH resource set. When it is necessary for the gNB to postpone HARQ-ACK feedback corresponding to one DL transmission by the UE, the gNB can indicate an invalid value in a field of the PUCCH resource indicator in a DL grant sent to the UE. Such an indication may be achieved by explicitly binding one or more entries to an invalid PUCCH resource to thereby indicate a postponement of HARQ-ACK feedback, which is shown in Table 2 as presented below. Alternatively, one or more of the 8 entries in the resource list as shown in Table 2 can indicate an invalid resource. When it is necessary for the gNB to trigger HARQ-ACK feedback from the UE, the gNB may indicate a valid PUCCH resource indicator in a DL grant sent to the UE. Upon receiving a DL grant, the UE may determine to postpone the transmission of HARQ-ACK feedback based on the value in the field for the PUCCH resource indicator, e.g., when the field has an invalid value. Alternatively, the UE can also determine to send HARQ-ACK feedback based on the value in the field for the PUCCH resource indicator, for example, when the field has a valid value.

[0073]

[0074] Table 2: Explanation of PUCCH resource indication field values

[0075] In another embodiment, the DCI may include a bit indicating that the transmission of HARQ-ACK feedback is postponed (e.g., a bit value of "0") or a bit indicating that the transmission of HARQ-ACK feedback is started / enabled (e.g., a bit value of "1"). When it is necessary for the gNB to postpone HARQ-ACK feedback corresponding to one DL transmission from the UE, the gNB may indicate the corresponding bit value to the UE in the DL grant. When it is necessary for the gNB to trigger HARQ-ACK feedback from the UE, the gNB may indicate the corresponding bit value in the DL grant sent to the UE. Upon receiving the DL grant, the UE may determine that the transmission of HARQ-ACK feedback is to be postponed based on a specific bit value in the received DL grant, such as a bit value of "0". Alternatively, the UE may also be able to determine that HARQ-ACK feedback is to be sent based on a different bit value in the received DL grant, such as a bit value of "1".

[0076] In yet another embodiment, the total DAI can be reinterpreted as the total number of PDCCH monitoring opportunities in which there is a PDSCH reception or SPS PDSCH release associated with DCI format 1_0 or DCI format 1_1 and their corresponding HARQ-ACK information bits are sent in the same HARQ-ACK codebook. The total DAI can be included in each DCI format 1_0 or DCI format 1_1. The value of the total DAI can be the same for all DL transmissions in which its corresponding HARQ-ACK feedback is sent in the same HARQ-ACK codebook. When the UE determines that the value of the latest counter DAI is not equal to the value of the total DAI, the UE can postpone the transmission of the HARQ-ACK feedback. When the UE determines that the value of the latest counter DAI is equal to the value of the total DAI, the UE can start the transmission of the HARQ-ACK feedback. Upon receiving a DL grant, the UE can thereby determine to postpone or send the HARQ-ACK feedback based on the values ​​of the counter DAI and the total DAI.

[0077] HARQ process with corresponding HARQ-ACK feedback

[0078] In one embodiment, a HARQ-ACK codebook index (HCI) may be included in each DL grant. The value of the HCI may be updated from one HARQ-ACK codebook to another HARQ-ACK codebook. In order for the UE to determine the bit length of the HCI, the maximum number of HARQ-ACK codebooks allowed for a UE may be configured through RRC signaling. The bit length of the HCI can be calculated accordingly via a function of ceil(log2(maximum number of HARQ-ACK codebooks). In another embodiment, the bit length of the HCI can be RRC configured or fixed. If two bits are used to indicate the HCI, four values ​​of 0, 1, 2, and 3 can be used for the HCI indication and the fifth HCI value can be reset to 0. In both alternatives, all DL transmissions sending corresponding HARQ-ACK feedback in the same HARQ-ACK codebook should be indicated with the same value of the HCI. In order to trigger the retransmission of the HARQ-ACK codebook due to LBT failure or incorrect decoding or the initial transmission of another HARQ-ACK codebook indicated to be pending, the triggering DCI can indicate the corresponding HCI value. In this way, the UE can be enabled to send the HARQ-ACK codebook in the indicated PUCCH resource.

[0079] In another embodiment, when multiple consecutive HARQ processes are sent in the same HARQ-ACK codebook, the process ID of the starting HARQ process and the number of consecutive HARQ processes may be indicated in the triggering DCI. Based on such information in the received DCI, the UE may be enabled to send or retransmit the bits of the HARQ-ACK feedback corresponding to the indicated HARQ process in some scenarios. In one embodiment, the process ID of the starting HARQ process and the number of HARQ processes may be separately indicated in the triggering DCI. Since the maximum number of HARQ processes is 16, only four bits can be used to indicate the process ID of the starting HARQ process, and the other four bits can be used to indicate the number of consecutive HARQ processes. In another embodiment, the process ID of the starting HARQ process and the number of HARQ processes are jointly encoded in the triggering DCI for indicating the HARQ process. Since the maximum number of HARQ processes is 16, eight bits will be sufficient to indicate the process ID of the starting HARQ process and the number of consecutive HARQ processes.

[0080] Triggering HARQ-ACK feedback beyond the current COT

[0081] In some embodiments, there may be a situation where a self-contained HARQ-ACK codebook for most DL transmissions (i.e., DL transmissions and corresponding HARQ-ACK feedback are sent in the same COT) is not sent because LBT failed or was not correctly decoded at the gNB side and the last several DL transmissions within a COT cannot be acknowledged in the same COT and have been indicated in the previous DCI to postpone the transmission of the corresponding HARQ-ACK feedback. An exemplary situation is illustrated in detail in Figure 7 middle, Figure 7 Another embodiment of a gNB-triggered HARQ-ACK reporting mechanism is shown. In this exemplary scenario, the gNB triggers retransmission of a failed HARQ-ACK codebook and initial transmission of a pending HARQ-ACK codebook. Specifically, the first six DL transmissions in a COT can be confirmed by UL transmissions in the same COT, but it is not possible to confirm two DL transmissions marked as "pending" within the same COT. If the HARQ-ACK codebook for the first six DL transmissions also fails to be sent via a self-contained UL transmission in the COT due to LBT failure or incorrect decoding on the gNB side, the gNB is able to send a triggering DCI not only for requesting retransmission of the HARQ-ACK codebook for the first six DL transmissions, but also for triggering HARQ-ACK feedback via another HARQ-ACK codebook for the two pending DL transmissions whose HARQ-ACK feedback could not be sent in the same COT.

[0082] In one embodiment, two HARQ-ACK codebooks for the first six DL transmissions and the last two pending DL transmissions, respectively, may be concatenated and sent in one UCI. The retransmitted self-contained HARQ-ACK codebook may be placed first, followed by the pending HARQ-ACK codebook. In this case, the retransmitted HARQ-ACK codebook for the first six DL transmissions is recoded together with the pending HARQ-ACK codebook for the trailing two DL transmissions in the same COT.

[0083] In another embodiment, two HARQ-ACK codebooks may be sent in two separate PUCCHs. In this case, the triggering DCI may include separate PUCCH resource indicators for the two HARQ-ACK codebooks. As a result, the retransmitted HARQ-ACK codebook does not have to be re-encoded with the pending HARQ-ACK codebook.

[0084] By the above method of triggering HARQ-ACK feedback beyond the same COT, the UE and the gNB are able to synchronize the HARQ processes that require retransmission of one HARQ-ACK codebook and / or initial transmission of another HARQ-ACK codebook.

[0085] LBT indication for transmission of HARQ-ACK feedback

[0086] In some embodiments, the LBT type can be indicated in the DL grant sent by the UE, i.e., one shot LBT with at least 25us sensing interval (also known as Type 2 UL channel access procedure in 3GPP Rel-14 TS36.213) or LBT Cat.4 with a random backoff counter selected from a variable contention window (also known as Type 1 UL channel access procedure in 3GPP Rel-14 TS36.213). In one embodiment, the UE may expect the LBT type to be the same for all DL transmissions whose corresponding HARQ-ACK feedback is sent in the same HARQ-ACK codebook. In another embodiment, the LBT type in the latest DL grant can be used to perform LBT for HARQ-ACK transmission.

[0087] In some embodiments, the LBT priority category can be indicated in the DL grant. An example of the LBT priority category is shown in Table 1 below. Each LBT priority category defines a contention window for a certain COT. In one embodiment, the UE may expect the LBT priority category to be the same for all DL transmissions for which its corresponding HARQ-ACK feedback is sent in the same HARQ-ACK codebook. In another embodiment, the LBT priority category in the latest DL grant can be used to perform LBT for transmission of HARQ-ACK feedback.

[0088]

[0089] Table 3: UL channel access priority categories

[0090] Feedback, an exemplary method may include: receiving a DCI for scheduling a data transmission, wherein the DCI includes a field for indicating an LBT type for transmission of HARQ-ACK feedback; performing LBT for sending HARQ-ACK feedback for the data transmission using the LBT type indicated in the received DCI. The LBT type indicated in the DCI may be the same for all DL transmissions of the data transmission, or may be the LBT type in the most recent DL transmission of the data transmission.

[0091] Another exemplary method may include: receiving a DCI for scheduling a data transmission, wherein the DCI includes a field for indicating an LBT priority category for transmission of HARQ-ACK feedback; performing LBT for sending HARQ-ACK feedback for the data transmission using the LBT type indicated in the received DCI. The LBT priority category indicated in the DCI may be the same for all DL transmissions of the data transmission, or may be an LBT priority category in the most recent DL transmission of the data transmission.

[0092] Embodiments may be practiced in other specific forms. The described embodiments should be considered in all respects as merely illustrative and not restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than the preceding description. All changes within the meaning and equivalent range of the claims are included within their scope.

Claims

1. A method, include: receiving first downlink control information (DCI) from a base unit for scheduling downlink (DL) transmission, wherein the first DCI includes a first indicator indicating to defer transmission of a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the DL transmission; receiving, from the base unit, a second DCI for scheduling transmission of HARQ-ACK feedback, wherein the second DCI indicates resources used for transmission of the HARQ-ACK feedback; as well as sending the HARQ-ACK feedback to the base unit on resources indicated by the second DCI, The first indicator indicates that an invalid "pending indication" HARQ timing value is used to postpone the transmission of the HARQ-ACK feedback, and indicates that a valid HARQ timing value is used to trigger the HARQ-ACK feedback.

2. The method according to claim 1, in, The first DCI includes a HARQ-ACK codebook index.

3. The method according to claim 2, in, A bit length of the HARQ-ACK codebook index is determined based on radio resource control (RRC) signaling.

4. The method according to claim 2, in, The second DCI includes the HARQ-ACK codebook index used to schedule transmission of the corresponding HARQ-ACK codebook.

5. The method according to claim 1, in, The second DCI schedules transmission of HARQ-ACK feedback for the HARQ process by indicating the corresponding HARQ process ID of the HARQ process in the second DCI.

6. The method according to claim 5, in, The second DCI includes one field for indicating a starting HARQ process ID and another field for indicating the number of consecutive HARQ processes.

7. The method according to claim 5, in, The second DCI includes a field for indicating a starting HARQ process ID and the number of consecutive HARQ processes.

8. The method according to claim 1, in, The HARQ-ACK feedback is included in a first HARQ-ACK codebook, and in response to the first indicator indicating to postpone the first HARQ-ACK codebook, transmission of the first HARQ-ACK codebook is postponed; and The second DCI schedules transmission of the first HARQ-ACK codebook and retransmission of a second HARQ-ACK codebook, wherein a previous transmission of the second HARQ-ACK codebook was not correctly received by the basic unit.

9. The method according to claim 8, in, The first HARQ-ACK codebook and the second HARQ-ACK codebook are sent in one UCI.

10. The method according to claim 8, in, The first HARQ-ACK codebook and the second HARQ-ACK codebook are transmitted in two separate uplink control information (UCI).

11. The method according to claim 1, in, The first DCI includes a field for indicating a listen-before-talk (LBT) type of transmission of the HARQ-ACK feedback.

12. The method according to claim 1, in, The first DCI includes a field for indicating an LBT priority category for transmission of the HARQ-ACK feedback.

13. The method according to claim 1, in, The second DCI includes a field for indicating an LBT type for transmission of the HARQ-ACK feedback.

14. The method according to claim 1, in, The second DCI includes a field for indicating an LBT priority category for transmission of the HARQ-ACK feedback.

15. A method, include: transmitting first downlink control information (DCI) for scheduling a downlink (DL) transmission, wherein the first DCI includes a first indicator indicating to defer transmission of a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the DL transmission; sending a second DCI for scheduling transmission of the HARQ-ACK feedback, wherein the second DCI indicates resources used for transmission of the HARQ-ACK feedback; as well as receiving the HARQ-ACK feedback sent on resources indicated by the second DCI, The first indicator indicates that an invalid "pending indication" HARQ timing value is used to postpone the transmission of the HARQ-ACK feedback, and indicates that a valid HARQ timing value is used to trigger the HARQ-ACK feedback.

16. The method according to claim 15, in, The first DCI includes a HARQ-ACK codebook index.

17. The method according to claim 16, in, A bit length of the HARQ-ACK codebook index is determined based on radio resource control (RRC) signaling.

18. The method according to claim 16, in, The second DCI includes the HARQ-ACK codebook index used to schedule transmission of the corresponding HARQ-ACK codebook.

19. The method according to claim 15, in, The second DCI schedules transmission of HARQ-ACK feedback for the HARQ process by indicating the corresponding HARQ process ID of the HARQ process in the second DCI.

20. The method according to claim 19, in, The second DCI includes one field for indicating a starting HARQ process ID and another field for indicating the number of consecutive HARQ processes.

21. The method according to claim 19, in, The second DCI includes a field for indicating a starting HARQ process ID and the number of consecutive HARQ processes.

22. The method according to claim 15, in, The HARQ-ACK feedback is included in a first HARQ-ACK codebook, and in response to the first indicator indicating to postpone the first HARQ-ACK codebook, transmission of the first HARQ-ACK codebook is postponed; and The second DCI schedules transmission of the first HARQ-ACK codebook and retransmission of a second HARQ-ACK codebook, wherein a previous transmission of the second HARQ-ACK codebook was not correctly received by the basic unit.

23. The method according to claim 22, in, The first HARQ-ACK codebook and the second HARQ-ACK codebook are transmitted in one uplink control information (UCI).

24. The method according to claim 22, in, The first HARQ-ACK codebook and the second HARQ-ACK codebook are sent in two separate UCIs.

25. The method according to claim 15, in, The first DCI includes a field for indicating a listen-before-talk (LBT) type of transmission of the HARQ-ACK feedback.

26. The method according to claim 15, in, The first DCI includes a field for indicating an LBT priority category for transmission of the HARQ-ACK feedback.

27. The method according to claim 15, in, The second DCI includes a field for indicating an LBT type for transmission of the HARQ-ACK feedback.

28. The method according to claim 15, in, The second DCI includes a field for indicating an LBT priority category for transmission of the HARQ-ACK feedback.

29. A device, include: A receiver, the receiver: receiving first downlink control information (DCI) for scheduling a downlink (DL) transmission, wherein the first DCI includes a first indicator indicating to defer transmission of a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the DL transmission; as well as receiving a second DCI for scheduling transmission of the HARQ-ACK feedback, wherein the second DCI indicates resources used for transmission of the HARQ-ACK feedback; as well as a transmitter, the transmitter sending the HARQ-ACK feedback on resources indicated by the second DCI, The first indicator indicates that an invalid "pending indication" HARQ timing value is used to postpone the transmission of the HARQ-ACK feedback, and indicates that a valid HARQ timing value is used to trigger the HARQ-ACK feedback.

30. A device, include: A transmitter, the transmitter: transmitting first downlink control information (DCI) for scheduling a downlink (DL) transmission, wherein the first DCI includes a first indicator indicating to defer transmission of a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the DL transmission; and sending a second DCI for scheduling transmission of the HARQ-ACK feedback, wherein the second DCI indicates resources used for transmission of the HARQ-ACK feedback; as well as a receiver, the receiver receiving the HARQ-ACK feedback sent on the resource indicated by the second DCI, The first indicator indicates that an invalid "pending indication" HARQ timing value is used to postpone the transmission of the HARQ-ACK feedback, and indicates that a valid HARQ timing value is used to trigger the HARQ-ACK feedback.

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