Responding to new data indicator for hybrid automatic repeat request process

Abstract

The invention relates to responding to a new data indicator for a hybrid automatic repeat request process. Apparatuses, methods, and systems are disclosed for responding to a new data indicator for a hybrid automatic repeat request process. A method (1200) includes determining (1202) whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. The method (1200) includes, in response to determining that the current new data indicator does not match the last received new data indicator, determining (1204) whether a negative acknowledgement has been transmitted in response to the last received sidelink grant.

Description

[0001] This application is a divisional application of an application which entered the Chinese national phase on December 7, 2021, with PCT application number PCT / IB2020 / 000471, international application date June 11, 2020, Chinese application number 202080042105.7, and invention name “RESPONDING TO A NEW DATA INDICATOR FOR A HYBRID AUTOMATIC REPEAT REQUEST PROCESS”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Patent Application Serial No. 62 / 860,689, filed on June 12, 2019, for Karthikeyan Ganesan, entitled “APPARATUSES, METHODS, AND SYSTEMS FOR SIDELINK MODE 1 HARQ OPERATION FOR A TRANSMITTER UE,” which is incorporated herein by reference in its entirety. Technical Field

[0004] The subject matter disclosed herein relates generally to wireless communications and, more particularly, to responding to new data indicators for a hybrid automatic repeat request process. Background Art

[0005] The following abbreviations are defined herein, at least some of which are referenced in the following description: 3rd Generation Partnership Project ("3GPP"), Fifth Generation ("5G"), NRQoS for V2X communications (“5QI / PQI”), authentication, authorization and accounting (“AAA”), positive acknowledgement (“ACK”), application function (“AF”), authentication and key agreement (“AKA”), aggregation level (“AL”), access and mobility management function (“AMF”), angle of arrival (“AoA”), angle of departure (“AoD”), access point (“AP”), access layer (“AS”), application service provider (“ASP”), autonomous uplink (“AUL”), authentication server function (“AUSF”), authentication token (“AUTN”), background data (“BD”), background data transfer (“BDT”), beam failure detection (“BF”). D”), Beam Failure Recovery (“BFR”), Binary Phase Shift Keying (“BPSK”), Base Station (“BS”), Buffer Status Report (“BSR”), Bandwidth (“BW”), Bandwidth Part (“BWP”), Cell RNTI (“C-RNTI”), Carrier Aggregation (“CA”), Channel Access Priority Class (“CAPC”), Contention-Based Random Access (“CBRA”), Clear Channel Assessment (“CCA”), Common Control Channel (“CCCH”), Control Channel Element (“CCE”), Cyclic Delay Diversity (“CDD”), Code Division Multiple Access (“CDMA”), Control Element (“CE”), Contention-Free Random Access (“CFRA”), Configured Grant ("CG"), Closed Loop ("CL"), Coordinated Multipoint ("CoMP"), Channel Occupancy Time ("COT"), Cyclic Prefix ("CP"), Cyclic Redundancy Check ("CRC"), Channel State Information ("CSI"), Channel State Information-Reference Signal ("CSI-RS"), Common Search Space ("CSS"), Control Resource Set ("CORESET"), Discrete Fourier Transform Spread ("DFTS"), Dual Connectivity ("DC"), Downlink Control Information ("DCI"), Downlink Feedback Information ("DFI"), Downlink ("DL"), Demodulation Reference Signal ("DMRS"), Data Network Name ("DNN"), Data Radio bearer (“DRB”), discontinuous reception (“DRX”), dedicated short range communication (“DSRC”), discontinuous transmission (“DTX”), downlink pilot time slot (“DwPTS”), enhanced clear channel assessment (“eCCA”), enhanced mobile broadband (“eMBB”), evolved Node B (“eNB”), extensible authentication protocol (“EAP”), effective isotropic radiated power (“EIRP”), European Telecommunications Standards Institute (“ETSI”), framework based equipment (“FBE”), frequency division duplexing (“FDD”), frequency division multiplexing (“FDM”), frequency division multiple access (“FDMA”), frequency division orthogonal cover codes (“FD-OCC”), frequency range 1–6 GHz and / or sub-410MHz to 7125MHz (“FR1”), Frequency Range 2–24.25 GHz to 52.6 GHz (“FR2”), Generic Geographic Area Description (“GAD”), Guaranteed Bit Rate (“GBR”), Group Leader (“GL”), 5G Node B or Next Generation Node B (“gNB”), Global Navigation Satellite System (“GNSS”), General Packet Radio Service (“GPRS”), Guard Period (“GP”), Global Positioning System (“GPS”), Global System for Mobile Communications (“GSM”), Globally Unique Temporary UE Identifier (“GUTI”), Home AMF (“hAMF”), Hybrid Automatic Repeat Request (“HARQ”), HARQ Process ID (“HPID”) ), Home Location Register (“HLR”), Handover (“HO”), Home PLMN (“HPLMN”), Home Subscriber Server (“HSS”), Hashed Expected Response (“HXRES”), Identity or Identifier (“ID”), Information Element (“IE”), International Mobile Equipment Identity (“IMEI”), International Mobile Subscriber Identity (“IMSI”), International Mobile Telecommunications (“IMT”), Internet of Things (“IoT”), Layer 1 (“L1”), Layer 2 (“L2”), Layer 3 (“L3”), License Assisted Access (“LAA”), Local Area Data Network (“LA DN”), Local Area Network (“LAN”), Load Based Equipment (“LBE”), Listen Before Talk (“LBT”), Logical Channel (“LCH”), Logical Channel Group (“LCG”), Logical Channel Priority (“LCP”), Log Likelihood Ratio (“LLR”), Long Term Evolution (“LTE”), Multiple Access (“MA”), Medium Access Control (“MAC”), Multimedia Broadcast Multicast Service (“MBMS”), Maximum Bit Rate (“MBR”), Minimum Communication Range (“MCR”), Modulation and Coding Scheme (“MCS”), Master Information Block (“MIB”), Multiple Input Multiple Output (“MIB”), MIMO), Mobility Management (“MM”), Mobility Management Entity (“MME”), Mobile Network Operator (“MNO”), Mobile Originated (“MO”), Massive MTC (“mMTC”), Maximum Power Reduction (“MPR”), Machine Type Communication (“MTC”), Multi-User Shared Access (“MUSA”), Non-Access Stratum (“NAS”), Narrowband (“NB”), Negative Acknowledgement (“NACK”) or (“NAK”), New Data Indicator (“NDI”), Network Entity (“NE”), Network Function (“NF”), Next Generation (“NG”), NG5G S-TMSI (“NG-5G-S-TMSI”), Non-Orthogonal Multiple Access (“NOMA”), New Radio (“NR”), Unlicensed NR (“NR-U”), Network Repository Function (“NRF”), Network Scheduling Mode (“NS Mode”) (e.g., Network Scheduling Mode for V2X Communication Resource Allocation—NRMode-1 in V2X and Mode-3 in LTE V2X), Network Slice Instance ("NSI"), Network Slice Selection Assistance Information ("NSSAI"), Network Slice Selection Function ("NSSF"), Network Slice Selection Policy ("NSSP"), Operation, Administration and Maintenance System or Operation and Maintenance Center ("OAM"), Orthogonal Frequency Division Multiplexing ("OFDM"), Open Loop ("OL"), Other System Information ("OSI"), Power Angular Spectrum ("PAS"), Physical Broadcast Channel ("PBCH"), Power Control ("PC"), UE to UE Interface ("PC5"), Policy and Charging Control ("PCC"), Primary Small area ("PCell"), Policy Control Function ("PCF"), Physical Cell Identity ("PCI"), Physical Downlink Control Channel ("PDCCH"), Packet Data Convergence Protocol ("PDCP"), Packet Data Network Gateway ("PGW"), Physical Downlink Shared Channel ("PDSCH"), Mode Division Multiple Access ("PDMA"), Packet Data Unit ("PDU"), Physical Hybrid ARQ Indicator Channel ("PHICH"), Power Headroom ("PH"), Power Headroom Report ("PHR"), Physical Layer ("PHY"), Public Land Mobile Network ("PLMN"), PC5 QoS Class Identifier ("PQI"), Physical Random Access Channel ("PRACH"), Physical Resource Block ("PRB"), Positioning Reference Signal ("PRS"), Physical Sidelink Control Channel ("PSCCH"), Primary and Secondary Cell ("PSCell"), Physical Sidelink Feedback Control Channel ("PSFCH"), Physical Uplink Control Channel ("PUCCH"), Physical Uplink Shared Channel ("PUSCH"), QoS Class Identifier ("QCI"), Quasi Co-location ("QCL"), Quality of Service ("QoS"), Quadrature Phase Shift Keying ("QPSK"), Registration Area ("RA"), RARNTI ("RA-RNTI"), Radio Access Network ("RAN"), Random ("RAND"), Radio Access Technology ("RAT"), Serving RAT ("RAT-1") (serving Uu), Other RAT ("RAT-2") (not serving Uu), Random Access Procedure ("RACH"), Random Access Preamble Identifier ("RAPID"), Random Access Response ("RAR"), Resource Block Assignment ("RBA"), Resource Element Group ("REG"), Radio Link Control ("RLC"), RLC Acknowledged Mode ("RLC-AM"), RLC Unacknowledged Mode / Transparent Mode ("RLC-UM / TM"), Radio Link Failure ("RLF"), Radio Link Monitoring ("RLM"), Radio Network Temporary Identifier ("RNTI"), Reference Signal ("RS"), Remaining Minimum System Information ("RMSI"), Radio Resource Control ("RRC"), Radio Resource Management ("RRM"), Resource Extended Multiple Access ("RSMA"), Reference Signal Received Power ("RSRP"), Received Signal Strength Indicator ("RSSI"), Round Trip Time ("RTT"), Reception ("RX"), Sparse Code Multiple Access ("SCMA"), Scheduling Request ("SR"), Sounding Reference Signal Signal ("SRS"), Single Carrier Frequency Division Multiple Access ("SC-FDMA"), Secondary Cell ("SCell"), Secondary Cell Group ("SCG"), Shared Channel ("SCH"), Sidelink Control Information ("SCI"), Subcarrier Spacing ("SCS"), Service Data Unit ("SDU"), Security Anchor Function ("SEAF"), Sidelink Feedback Content Information ("SFCI"), Serving Gateway ("SGW"), System Information Block ("SIB"), SystemInformationBlockType1 ("SIB1"), SystemInformationBlockTy pe2 ("SIB2"), Subscriber Identity / Identification Module ("SIM"), Signal-to-Interference-plus-Noise Ratio ("SINR"), Sidelink ("SL"), Service Level Agreement ("SLA"), Sidelink Synchronization Signal ("SLSS"), Session Management ("SM"), Session Management Function ("SMF"), Special Cell ("SpCell"), Single Network Slice Selection Assistance Information ("S-NSSAI"), Scheduling Request ("SR"), Signaling Radio Bearer ("SRB"), Shortened TMSI ("S-TMSI"), Shortened TTI ("sTTI"), Synchronization Signal ("SS"), Sidelink CSI RS ("S-CSI, Sidelink PRS ("S-PRS"), Sidelink SSB ("S-SSB"), Synchronization Signal Block ("SSB"), Subscription Hidden Identifier ("SUCI"), Scheduled User Equipment ("SUE"), Supplementary Uplink ("SUL"), Subscriber Permanent Identifier ("SUPI"), Tracking Area ("TA"), TA Identifier ("TAI"), TA Update ("TAU"), Timing Alignment Timer ("TAT"), Transport Block ("TB"), Transport Block Size ("TBS"), Time Division Duplex (" TDD”), Time Division Multiplexing (“TDM”), Time Division Orthogonal Cover Code (“TD-OCC”), Temporary Mobile Subscriber Identity (“TMSI”), Time of Flight (“ToF”), Transmit Power Control (“TPC”), Transmit Reception Point (“TRP”), Transmission Time Interval (“TTI”), Transmit (“TX”), Uplink Control Information (“UCI”), Unified Data Management Function (“UDM”), Unified Data Repository (“UDR”), User Entity / Equipment (Mobile Terminal) (“UE”) (e.g., V2X UE), UE autonomous modes (UE autonomously selects V2X communication resources - for example, Mode 2 in NR V2X and Mode 4 in LTE V2X. The UE autonomous selection may or may not be based on resource sensing operation), Uplink ("UL"), UL SCH ("UL-SCH"), Universal Mobile Telecommunications System ("UMTS"), User Plane ("UP"), UP Function ("UPF"), Uplink Pilot Time Slot ("UpPTS"), Ultra-Reliable and Low Latency Communication ("URLLC"), UE Routing Selection Policy ("URSP"), Vehicle-to-Vehicle ("V2V"), ​​Vehicle-to-Everything ("V2X"), V2X UE (e.g., UE capable of vehicular communications using 3GPP protocols), Access AMF ("vAMF"), Access NSSF ("vNSSF"), Access PLMN ("VPLMN"), Wide Area Network ("WAN"), and Worldwide Interoperability for Microwave Access ("WiMAX").

[0006] In certain wireless communication networks, a new data indicator may be used. Summary of the invention

[0007] A method for responding to a new data indicator of a hybrid automatic repeat request process is disclosed. Apparatus and systems also perform the functions of the method. One embodiment of the method includes determining whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, the method includes, in response to determining that the current new data indicator does not match the last received new data indicator, determining whether a negative acknowledgement has been transmitted in response to the last received sidelink grant.

[0008] An apparatus for responding to a new data indicator for a hybrid automatic repeat request process includes a processor that: determines whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator does not match the last received new data indicator, determines whether a negative acknowledgement has been transmitted in response to the last received side link grant.

[0009] Another embodiment of a method for responding to a new data indicator for a hybrid automatic repeat request process includes determining whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, the method includes, in response to determining that the current new data indicator matches the last received new data indicator, determining whether a positive acknowledgement has been transmitted in response to the last received sidelink grant.

[0010] Another apparatus for responding to a new data indicator for a hybrid automatic repeat request process includes a processor that: determines whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator matches the last received new data indicator, determines whether a positive acknowledgement has been transmitted in response to the last received side link grant. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments illustrated in the accompanying drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0012] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for responding to a new data indicator for a hybrid automatic repeat request process;

[0013] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used to respond to a new data indicator for a hybrid automatic repeat request process;

[0014] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that may be used to transmit and / or receive data;

[0015] Figure 4is a schematic diagram illustrating one embodiment of a method for HARQ operation of sidelink mode 1;

[0016] Figure 5 is a schematic diagram illustrating one embodiment of communications including a NACK to ACK error;

[0017] Figure 6 is a schematic diagram illustrating another embodiment of communications including a NACK to ACK error;

[0018] Figure 7 is a schematic diagram illustrating one embodiment of communications including lost DCI;

[0019] Figure 8 is a schematic diagram illustrating another embodiment of communications including lost DCI;

[0020] Fig. 9 is a schematic diagram illustrating yet another embodiment of communications including lost DCI;

[0021] Fig.10 is a schematic diagram illustrating yet another embodiment of communications including lost DCI;

[0022] Fig.11 is a block diagram illustrating one embodiment of a system including a TX UE;

[0023] Fig.12 is a flow chart illustrating one embodiment of a method for responding to a new data indicator for a hybrid automatic repeat request process; and

[0024] Fig.13 is a flow chart illustrating another embodiment of a method for responding to a new data indicator of a hybrid automatic repeat request process. DETAILED DESCRIPTION

[0025] 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, the embodiments may take the form of a fully hardware embodiment, a fully software embodiment (including firmware, resident software, microcode, etc.), or a combination of software and hardware aspects, which may all be generally referred to herein as "circuits," "modules," or "systems." In addition, the embodiments may take the form of a program product embodied in one or more computer-readable storage devices stored in 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.

[0026] Certain 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 a custom very large scale integrated ("VLSI") circuit or gate array, off-the-shelf semiconductor such as a logic chip, transistor or other discrete component. A module may also be implemented in a programmable hardware device such as a field programmable gate array, programmable array logic, a programmable logic device, etc.

[0027] Modules may also be implemented in code and / or software to be executed by various types of processors. The identified modules of code may, for example, include one or more physical or logical blocks of executable code, which may, for example, be organized as objects, procedures, or functions. However, the executable files of the identified modules need not be physically located together, but may include unrelated instructions stored in different locations, which, when logically combined together, comprise the module and achieve the stated purpose of the module.

[0028] In fact, code module can be a single instruction or many instructions, and can even be distributed on several different code segments, among different programs and across several memory devices.Similarly, in this article, operating data can be identified and illustrated in the module, and can be embodied and organized in the data structure of any appropriate type in any appropriate form.Operational data can be collected as a single data set, or can be distributed in different locations, which are included on different computer-readable storage devices.When a module or a part of a module is implemented in software, the software part is stored on one or more computer-readable storage devices.

[0029] 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 not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical or semiconductor system, apparatus or device, or any suitable combination of the foregoing.

[0030] More specific examples of storage devices (a non-exhaustive list) would include the following: an electrical connection with one or more cables, 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 disk 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.

[0031] The code for performing the operations of the embodiments may be any number of lines and may be written in any combination of one or more programming languages ​​including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, C++, and the like, and commonly used procedural programming languages ​​such as the "C" programming language, and / or machine languages ​​such as assembly languages. The code may be executed entirely on the user's computer, 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 scenario, the remote computer may be connected to the user's computer via any type of network including a local area network ("LAN") or a wide area network ("WAN"), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0032] 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, throughout the specification, the occurrences of the phrases "in one embodiment," "in an embodiment," and similar language may, but 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 "one," "an," and "the" also refer to "one or more."

[0033] In addition, the features, structures or characteristics of the described embodiments may be combined in any appropriate 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, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific details, or using other methods, components, materials, etc. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid blurring aspects of the embodiments.

[0034] 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 frame of the schematic flow charts and / or schematic block diagrams and the combination of frames in the schematic flow charts and / or schematic block diagrams can be implemented by code. The 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 device for implementing the functions / operations specified in the schematic flow charts and / or schematic block diagram frames or multiple frames.

[0035] 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 the schematic flowchart and / or schematic block diagram box or multiple boxes.

[0036] The code may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other device to produce a computer-implemented process, such that the code executed on the computer or other programmable apparatus provides a process for implementing the functions / operations specified in the flowchart and / or block diagram block or multiple blocks.

[0037] The schematic flow charts and / or schematic block diagrams in the accompanying drawings illustrate the architecture, functions and operations of possible implementations of the apparatus, system, method and program product according to different embodiments. In this regard, each box in the schematic flow chart and / or schematic block diagram may represent a module, a fragment or a portion of a code, which includes one or more executable instructions of the code for implementing (multiple) specified logical functions.

[0038] It should also be noted that in some alternative embodiments, the functions annotated in the blocks may not occur in the order annotated in the drawings. For example, depending on the functions involved, two blocks shown in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. It is conceivable that other steps and methods are equivalent in function, logic or effect to one or more blocks or portions thereof of the illustrated drawings.

[0039] Although various arrow types and line types can be adopted in flow charts and / or block diagrams, it is understood that they do not limit the scope of the corresponding embodiments. In fact, 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 steps of the enumeration of the depicted embodiment. It will also be noted that each frame of the block diagram and / or flow chart and the combination of the frames in the block diagram and / or flow chart can be realized by a system based on dedicated hardware that performs a specific function or operation, or by a combination of dedicated hardware and code.

[0040] The description of an element in each figure may refer to an element of the previous figure. In all figures, the same numerals refer to the same elements, including alternative embodiments of the same elements.

[0041] Figure 1 An embodiment of a wireless communication system 100 for responding to a new data indicator of a hybrid automatic repeat request process is depicted. In one embodiment, the wireless communication system 100 includes a remote unit 102 and a network unit 104. Although Figure 1 A specific number of remote units 102 and network units 104 are depicted in FIG. 1 , but one skilled 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.

[0042] 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 car computer, a network device (e.g., a router, a switch, a modem), an aerial vehicle, a drone, 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. In addition, 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 network units 104 via UL communication signals. In some embodiments, the remote unit 102 may communicate directly with other remote units 102 via sidelink communication.

[0043] The network elements 104 may be distributed over a geographic area. In some embodiments, the network elements 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, wireless access nodes, APs, NRs, network entities, AMFs, UDMs, UDRs, UDM / UDRs, PCFs, RANs, NSSFs, or any other terminology used in the art. The network elements 104 are typically part of a radio access network that includes one or more controllers that are communicatively coupled to one or more corresponding network elements 104. The radio access network is typically communicatively coupled to one or more core networks, which may be coupled to other networks, such as the Internet and public switched telephone networks, and the like. 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.

[0044] In one embodiment, the wireless communication system 100 complies with the NR protocol standardized in 3GPP, wherein the network unit 104 transmits on the DL using an OFDM modulation scheme, and the remote unit 102 transmits on the UL using an SC-FDMA scheme or an OFDM scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, such as WiMAX, IEEE 802.11 variants, GSM, GPRS, UMTS, LTE variants, CDMA2000, Bluetooth®, ZigBee, Sigfoxx, and other protocols. The present disclosure is not intended to be limited to implementations of any particular wireless communication system architecture or protocol.

[0045] The network unit 104 may serve multiple remote units 102 within a service area, such as a cell or cell sector, via wireless communication links. The network unit 104 transmits DL communication signals to serve the remote units 102 in the time, frequency, and / or spatial domains.

[0046] In various embodiments, remote unit 102 may determine whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, in response to determining that the current new data indicator does not match the last received new data indicator, remote unit 102 may determine whether a negative acknowledgement has been transmitted in response to the last received sidelink grant. Thus, remote unit 102 may be configured to respond to a new data indicator for a hybrid automatic repeat request process.

[0047] In some embodiments, remote unit 102 may determine whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, remote unit 102 may determine whether a positive acknowledgment has been transmitted in response to a last received sidelink grant in response to determining that the current new data indicator matches the last received new data indicator. Thus, remote unit 102 may be configured to respond to a new data indicator for a hybrid automatic repeat request process.

[0048] Figure 2 An embodiment of an apparatus 200 that can be used to respond to a new data indicator for a hybrid automatic repeat request process is depicted. The apparatus 200 includes an embodiment of a remote unit 102. In addition, 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 touch screen. In some 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.

[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 includes both volatile and non-volatile computer storage media. In some embodiments, memory 204 also stores program code and associated data, such as an operating system or other controller algorithms 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 touch panel.

[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, auditory 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 generating sounds. For example, the display 208 can generate an audible alarm or notification (e.g., a buzzer or beep). In some embodiments, the display 208 includes one or more tactile devices for generating 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 positioned near the input device 206.

[0054] Transmitter 210 is used to provide UL communication signals to Network element 104, and receiver 212 is used to receive DL communication signals from Network element 104, as described herein.

[0055] In some embodiments, the processor 202 may: determine whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator does not match the last received new data indicator, determine whether a negative acknowledgement has been transmitted in response to the last received side link grant.

[0056] In various embodiments, the processor 202 may: determine whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator matches the last received new data indicator, determine whether a positive acknowledgement has been transmitted in response to the last received side link grant.

[0057] Although only one transmitter 210 and one receiver 212 are shown, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and receiver 212 may be any suitable type of transmitter and receiver. In one embodiment, the transmitter 210 and receiver 212 may be part of a transceiver.

[0058] Figure 3One embodiment of an apparatus 300 that may be used to transmit and / or receive data is depicted. The apparatus 300 includes one embodiment of the network unit 104. In addition, 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. 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.

[0059] In some embodiments, the transmitter 310 and / or the receiver 312 may transmit and / or receive the information described herein. Although only one transmitter 310 and one receiver 312 are illustrated, the network unit 104 may have any suitable number of transmitters 310 and receivers 312. The transmitter 310 and the receiver 312 may be any suitable type of transmitter and receiver. In one embodiment, the transmitter 310 and the receiver 312 may be part of a transceiver.

[0060] In various embodiments, HARQ feedback error detection and handling mechanisms may be used for sidelink NR Mode 1 operation. In such embodiments, the gNB may allocate transmission and retransmission resources for sidelink transmissions.

[0061] In various embodiments, the TX UE transmits ACK / NACK regarding sidelink transmission and reception to the gNB, and the gNB may not receive ACK / NACK from the TX UE.

[0062] As used herein, the terms eNB and / or gNB may be used for a base station, but may also be replaced by any other radio access node (e.g., BS, eNB, gNB, AP, NR, etc.). In addition, various embodiments described herein may be in the context of 5G NR; however, such embodiments may be applicable to other mobile communication systems supporting a serving cell and / or carrier configured for sidelink communication via a PC5 interface.

[0063] In some embodiments, scheduling enhancements can be used for unicast and / or multicast transmissions by detecting errors (e.g., protocol errors due to NACK to ACK, DTX errors due to erroneous physical layer decoding). In some embodiments, packet losses due to erroneous control channel decoding can be reduced.

[0064] Figure 4is a schematic diagram illustrating one embodiment of a method 400 for sidelink Mode 1 HARQ operation. The method 400 includes detecting 402 an error and performing 404 a configuration in response to detecting the error.

[0065] Table 1 shows a summary of various HARQ error handling embodiments for NR Mode 1.

[0066] Table 1: Summary of various HARQ error handling embodiments for Mode 1

[0067]

[0068]

[0069] The embodiments of Table 1 are described in additional detail as found in the following Examples, which are also described with respect to Figures 5 to 10 Described.

[0070] In the first embodiment, there is a NACK to ACK error. Specifically, in the first embodiment, in NR mode 1, if the transmitter UE reports NACK to the BS to request retransmission resources after receiving NACK for groupcast or unicast transmission from the RX UE, and if the BS decodes the NACK as ACK, the TX UE can detect the error to prevent packet loss. In the first embodiment, the TX UE expects a retransmission grant from the BS, but the BS transmits DCI with a switched NDI (e.g., indicating resources for new initial transmission instead of retransmission). In such an embodiment, the TX UE detects an error from whether the switched NDI and / or TB size in the DCI is different. Figure 5 An example of a protocol error scenario that occurs in the first example is shown.

[0071] Figure 5 is a schematic diagram illustrating one embodiment of a communication 500 including a NACK to ACK error. The communication 500 includes communications between a BS 502, a TX UE 504, and a RX UE 506. As can be appreciated, each communication 500 described herein may include one or more messages.

[0072] In a first communication 508 transmitted from BS 502 to TX UE 504, BS 502 transmits a Mode 1 SL grant in a DCI to TX UE 504. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0073] In a second communication 510 transmitted from the TX UE 504 to the RX UE 506 , the TX UE 504 transmits an SCI (eg, a first TB) to the RX UE 506 .

[0074] In a third communication 512 transmitted from the RX UE 506 to the TX UE 504 , the RX UE 506 transmits a NACK to the TX UE 504 (eg, a NACK indicating that the first TB was not correctly received).

[0075] In a fourth communication 514 transmitted from the TX UE 504 to the BS 502, the TX UE 504 transmits a NACK indicator to the BS 502. The BS 502 misinterprets the NACK as an ACK.

[0076] In a fifth communication 516 transmitted from the BS 502 to the TX UE 504, the BS 502 transmits a Mode 1 SL grant in a DCI to the TX UE 504. In this embodiment, the Mode 1 SL grant includes information indicating a second TB (e.g., TB2, the size of the second TB), HPID = 1, and NDI = 1. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0077] The TX UE 504 detects 518 a protocol error because a switched NDI and / or a second TB is indicated (e.g., because the second TB has a different size than the first TB). As a result of detecting the error, the TX UE 504 may: 1) perform adaptive retransmission on the allocated resources by selecting another more appropriate MCS to adjust the code rate if the granted size is different from the previous granted size for the same TB; and / or 2) retransmit the pending transport block (e.g., TB1) for the HARQ process (e.g., 1) using NR Mode 2 operation; and a) perform a new transmission internally using a different SL HARQ process ID (e.g., HPID=2) based on the allocated resources in the received DCI; or b) ignore or skip the DCI grant and transmit an ACK to the base station.

[0078] In various embodiments, the TX UE 504 determines whether a NACK has been transmitted in response to a last received sidelink grant (e.g., in a third communication 512). In some embodiments, the TX UE 504 generates an autonomous HARQ retransmission for a first TB generated based on a last received sidelink grant in response to determining that a NACK has been transmitted in response to a last received sidelink grant (e.g., in a third communication 512) and that the current NDI does not match the last received NDI for the HARQ process. In certain embodiments, the TX UE 504 selects a second HARQ process, generates a second TB, stores the second TB in a HARQ buffer corresponding to the second HARQ process, and transmits the second TB in the second HARQ process in response to determining that a NACK has been transmitted in response to a last received sidelink grant (e.g., in a third communication 512) and that the current NDI does not match the last received NDI for the HARQ process.

[0079] In the second embodiment, there is an ACK to NACK error. Specifically, in the second embodiment, in NR Mode 1, if the transmitter UE reports an ACK to the BS when receiving an ACK for groupcast or unicast transmission from the RX UE to request transmission resources, and if the BS decodes the ACK as a NACK, the TX UE can detect an error. In the second embodiment, the TX UE expects a new transmission grant from the BS, but the BS transmits the DCI with an unswitched NDI (e.g., indicating resources for retransmission rather than for new transmission). In such an embodiment, the TX UE detects an error from the unswitched NDI in the DCI and the SL HARQ feedback received from the RX UE. Figure 6 An example of a protocol error scenario occurring in the second embodiment is shown.

[0080] Figure 6 6 is a schematic diagram illustrating another embodiment of a communication 600 including a NACK to ACK error. The communication 600 includes communications between a BS 602, a TX UE 604, and a RX UE 606. As can be appreciated, each communication 600 described herein may include one or more messages.

[0081] In a first communication 608 transmitted from BS 602 to TX UE 604, BS 602 transmits a Mode 1 SL grant in DCI to TX UE 604. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0082] In a second communication 610 transmitted from the TX UE 604 to the RX UE 606 , the TX UE 604 transmits an SCI (eg, a first TB) to the RX UE 606 .

[0083] In a third communication 612 transmitted from the RX UE 606 to the TX UE 604 , the RX UE 606 transmits an ACK to the TX UE 604 (eg, an ACK indicating that the first TB was correctly received).

[0084] In a fourth communication 614 transmitted from the TX UE 604 to the BS 602, the TX UE 604 transmits an ACK indicator to the BS 602. The BS 602 erroneously interprets the ACK as a NACK.

[0085] In a fifth communication 616 transmitted from the BS 602 to the TX UE 604, the BS 602 transmits a Mode 1 SL grant in a DCI to the TX UE 604. In this embodiment, the Mode 1 SL grant includes information indicating the first TB, HPID = 1, and NDI = 0. Therefore, the next DCI is transmitted, and the NDI is not switched for the same HARQ process ID.

[0086] TX UE 604 detects 618 a protocol error due to the unswitched NDI and the knowledge that TX UE 604 transmitted an ACK to BS 602. As a result of detecting the error, TX UE 604 may: 1) generate a new transmission according to the resources allocated in the DCI; 2) ignore or skip the DCI and transmit an ACK to BS 602 in feedback corresponding to a Mode 1 SL grant; and / or 3) trigger a SL BSR report.

[0087] In a third embodiment, the TX UE may lose the DCI (e.g., with a switched NDI compared to a previous transmission) and the TX UE may transmit a DTX to the BS, but the BS may interpret the DTX as an ACK. Specifically, in the third embodiment, in NR Mode 1, if the TX UE loses the DCI grant from the BS and the lost DCI contains a switched NDI compared to its previous transmission (e.g., with the same or different TB size), and the BS detects the DTX as an ACK, then, in such an embodiment, the BS's DCI transmission may contain a switched NDI indicating the new transmission, and the NDI is not switched from the TX UE's perspective because the TX UE lost the previous DCI from the base station. Figure 7 An example of a protocol error scenario occurring in the third embodiment is shown.

[0088] Figure 7is a schematic diagram illustrating one embodiment of a communication 700 including lost DCI. The communication 700 includes communications between a BS 702, a TX UE 704, and a RX UE 706. As can be appreciated, each communication 700 described herein may include one or more messages.

[0089] In a first communication 708 transmitted from BS 702 to TX UE 704, BS 702 transmits a Mode 1 SL grant in DCI to TX UE 704. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0090] In a second communication 710 transmitted from the TX UE 704 to the RX UE 706 , the TX UE 704 transmits an SCI (eg, a first TB) to the RX UE 706 .

[0091] In a third communication 712 transmitted from the RX UE 706 to the TX UE 704 , the RX UE 706 transmits an ACK to the TX UE 704 (eg, an ACK indicating that the first TB was correctly received).

[0092] In a fourth communication 714 transmitted from the TX UE 704 to the BS 702 , the TX UE 704 transmits an ACK indicator to the BS 702 .

[0093] In a fifth communication 716 transmitted from the BS 702 to the TX UE 704, the BS 702 transmits a Mode 1 SL grant in a DCI to the TX UE 704. In this embodiment, the Mode 1 SL grant includes information indicating a second TB (e.g., TB2, the size of the second TB), HPID = 1, and NDI = 1. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0094] The TX UE 704 does not detect 718 the DCI.

[0095] In a sixth communication 720 transmitted from the TX UE 704 to the BS 702, the TX UE 704 transmits a DTX indicator to the BS 702. The BS 702 interprets the DTX error as an ACK.

[0096] In a seventh communication 722 transmitted from the BS 702 to the TX UE 704, the BS 702 transmits a Mode 1 SL grant in a DCI to the TX UE 704. In this embodiment, the Mode 1 SL grant includes information indicating a third TB (e.g., TB3, the size of the third TB), HPID = 1, and NDI = 0. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0097] TX UE 704 detects 724 a protocol error because the NDI is not switched from the perspective of TX UE 704 and / or the third TB is indicated (e.g., because the third TB has a different size than the first TB). As a result of detecting the error, TX UE 704 may: 1) generate a new transmission according to the resources allocated in the DCI; 2) ignore or skip the DCI and transmit an ACK to BS 702 in feedback corresponding to a Mode 1 SL grant; and / or 3) trigger an SL BSR report. As can be appreciated, the protocol error may be caused by a combination of two errors (e.g., TX UE 704 missed the DCI and BS 702 interpreted the DTX as an ACK).

[0098] In a fourth embodiment, the TX UE may lose the DCI (e.g., with a switched NDI compared to a previous transmission) and the TX UE may transmit a DTX to the BS, but the BS may interpret the DTX as a NACK. Specifically, in the fourth embodiment, in NR Mode 1, if the TX UE loses a DCI grant from the BS and the lost DCI contains a switched NDI compared to its previous transmission (e.g., with the same or different TB size), and the BS detects the DTX as a NACK, then, in such an embodiment, the BS's DCI transmission may contain a non-switched NDI indicating resources for retransmission and the NDI is switched from the perspective of the TX UE because the TX UE lost the previous DCI from the BS. Figure 8 An example of a protocol error scenario occurring in the fourth embodiment is shown.

[0099] Figure 8 8 is a schematic diagram illustrating another embodiment of a communication 800 including lost DCI. The communication 800 includes communications between a BS 802, a TX UE 804, and a RX UE 806. As can be appreciated, each communication 800 described herein may include one or more messages.

[0100] In a first communication 808 transmitted from BS 802 to TX UE 804, BS 802 transmits a Mode 1 SL grant in a DCI to TX UE 804. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0101] In a second communication 810 transmitted from the TX UE 804 to the RX UE 806, the TX UE 804 transmits an SCI (e.g., a first TB) to the RX UE 806. In addition, in the second communication 810, the TX UE 804 may transmit the first TB to the RX UE 806 in a physical layer sidelink shared channel according to the Mode 1 SL grant received in the first communication 808.

[0102] In a third communication 812 transmitted from the RX UE 806 to the TX UE 804 , the RX UE 806 transmits an ACK to the TX UE 804 (eg, an ACK indicating that the first TB was correctly received).

[0103] In a fourth communication 814 transmitted from the TX UE 804 to the BS 802 , the TX UE 804 transmits an ACK indicator to the BS 802 .

[0104] In a fifth communication 816 transmitted from the BS 802 to the TX UE 804, the BS 802 transmits a Mode 1 SL grant in a DCI to the TX UE 804. In this embodiment, the Mode 1 SL grant includes information indicating a second TB (e.g., TB2, the size of the second TB), HPID = 1, and NDI = 1. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0105] The TX UE 804 does not detect 818 the DCI.

[0106] In a sixth communication 820 transmitted from the TX UE 804 to the BS 802, the TX UE 804 transmits a DTX indicator to the BS 802. As used herein, DTX may mean that a UE (e.g., a TX UE) does not transmit any information (e.g., ACK and / or NACK) in a PUCCH resource. The BS 802 interprets the DTX error as a NACK.

[0107] In a seventh communication 822 transmitted from the BS 802 to the TX UE 804, the BS 802 transmits a Mode 1 SL grant in a DCI to the TX UE 804. In this embodiment, the Mode 1 SL grant includes information indicating a second TB (e.g., TB2, the size of the second TB), HPID = 1, and NDI = 1. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0108] The TX UE 804 detects 824 that there is no protocol error because the NDI is switched from the perspective of the TX UE 804. Therefore, the TX UE 804 can operate as if no error has occurred.

[0109] In a fifth embodiment, the TX UE may lose the DCI (e.g., having an unswitched NDI compared to a previous transmission) and the TX UE may transmit a DTX to the BS, but the BS may interpret the DTX as an ACK. Specifically, in the fifth embodiment, in NR Mode 1, if the TX UE loses the DCI grant from the BS and the lost DCI contains an unswitched NDI compared to its previous transmission (e.g., having the same or different TB size), and the BS detects the DTX as an ACK, then, in such an embodiment, the BS's DCI transmission may contain a switched NDI indicating the new transmission, and the NDI is also switched from the perspective of the TX UE because the TX UE lost the previous DCI from the BS. Fig. 9 An example of a protocol error scenario occurring in the fifth embodiment is shown.

[0110] Fig. 9 9 is a schematic diagram illustrating yet another embodiment of a communication 900 including lost DCI. The communication 900 includes communications between a BS 902, a TX UE 904, and an RX UE 906. As can be appreciated, each communication 900 described herein may include one or more messages.

[0111] In a first communication 908 transmitted from BS 902 to TX UE 904, BS 902 transmits a Mode 1 SL grant in a DCI to TX UE 904. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0112] In a second communication 910 transmitted from the TX UE 904 to the RX UE 906, the TX UE 904 transmits an SCI (e.g., a first TB) to the RX UE 906. In addition, in the second communication 910, the TX UE 904 may transmit the first TB to the RX UE 906 in a physical layer sidelink shared channel according to the Mode 1 SL grant received in the first communication 908.

[0113] In a third communication 912 transmitted from the RX UE 906 to the TX UE 904 , the RX UE 906 transmits a NACK to the TX UE 904 (eg, a NACK indicating that the first TB was not correctly received).

[0114] In a fourth communication 914 transmitted from the TX UE 904 to the BS 902 , the TX UE 904 transmits a NACK indicator to the BS 902 .

[0115] In a fifth communication 916 transmitted from the BS 902 to the TX UE 904, the BS 902 transmits a Mode 1 SL grant in a DCI to the TX UE 904. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (e.g., TB1, the size of the first TB), HPID = 1, and NDI = 0. Therefore, the next DCI is transmitted, and the NDI is not switched for the same HARQ process ID.

[0116] The TX UE 904 does not detect 918 the DCI.

[0117] In a sixth communication 920 transmitted from the TX UE 904 to the BS 902, the TX UE 904 transmits a DTX indicator to the BS 902. The BS 902 interprets the DTX error as an ACK.

[0118] In a seventh communication 922 transmitted from the BS 902 to the TX UE 904, the BS 902 transmits a Mode 1 SL grant in a DCI to the TX UE 904. In this embodiment, the Mode 1 SL grant includes information indicating a second TB (e.g., TB2, the size of the second TB), HPID = 1, and NDI = 1. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0119] The TX UE 904 detects 924 a protocol error because the NDI is not switched from the perspective of the TX UE 904 and / or the third TB is indicated (e.g., because the third TB has a different size than the first TB). As a result of detecting the error, the TX UE 904 may: 1) perform adaptive retransmission on the allocated resources by selecting another more appropriate MCS to adjust the code rate if the grant size is different from the previous grant size of the same TB; and / or 2) retransmit the pending transport block (e.g., TB1) using NR Mode 2 for the HARQ process (e.g., 1); a) perform a new transmission internally using a different SL HARQ process ID (e.g., HPID=2) based on the allocated resources in the received DCI; or b) ignore or skip the DCI grant and transmit an ACK to the base station. As can be appreciated, the protocol error may be caused by a combination of two errors (e.g., the TX UE 904 loses the DCI and the BS 902 interprets the DTX as an ACK).

[0120] In a sixth embodiment, the TX UE may lose the DCI (e.g., have an unswitched NDI compared to a previous transmission) and the TX UE may transmit a DTX to the BS, but the BS may interpret the DTX as a NACK. Specifically, in the sixth embodiment, in NR Mode 1, if the TX UE loses a DCI grant from the BS, and the lost DCI contains an unswitched NDI compared to its previous transmission (e.g., with the same or different TB size), and the BS detects the DTX as a NACK, then, in such an embodiment, the BS's DCI transmission may contain an unswitched NDI indicating a new transmission, and the NDI is not switched from the perspective of the TX UE because the TX UE lost the previous DCI from the BS. Fig.10 An example of a protocol error scenario occurring in the sixth embodiment is shown.

[0121] Fig.10 1 is a schematic diagram illustrating yet another embodiment of a communication 1000 including lost DCI. The communication 1000 includes communications between a BS 1002, a TX UE 1004, and a RX UE 1006. As can be appreciated, each communication 1000 described herein may include one or more messages.

[0122] In a first communication 1008 transmitted from BS 1002 to TX UE 1004, BS 1002 transmits a Mode 1 SL grant in DCI to TX UE 1004. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (eg, TB1, the size of the first TB), HPID=1, and NDI=0.

[0123] In a second communication 1010 transmitted from the TX UE 1004 to the RX UE 1006, the TX UE 1004 transmits an SCI (e.g., a first TB) to the RX UE 1006. In addition, in the second communication 1010, the TX UE 1004 may transmit the first TB to the RX UE 1006 in a physical layer sidelink shared channel according to the Mode 1 SL grant received in the first communication 1008.

[0124] In a third communication 1012 transmitted from the RX UE 1006 to the TX UE 1004 , the RX UE 1006 transmits a NACK to the TX UE 1004 (eg, a NACK indicating that the first TB was not correctly received).

[0125] In a fourth communication 1014 transmitted from the TX UE 1004 to the BS 1002 , the TX UE 1004 transmits a NACK indicator to the BS 1002 .

[0126] In a fifth communication 1016 transmitted from BS 1002 to TX UE 1004, BS 1002 transmits a Mode 1 SL grant in DCI to TX UE 1004. In this embodiment, the Mode 1 SL grant includes information indicating a first TB (e.g., TB1, the size of the first TB), HPID = 1, and NDI = 0. Therefore, the next DCI is transmitted, and the NDI is switched for the same HARQ process ID.

[0127] The TX UE 1004 does not detect 1018 the DCI.

[0128] In a sixth communication 1020 transmitted from the TX UE 1004 to the BS 1002, the TX UE 1004 transmits a DTX indicator to the BS 1002. The BS 1002 interprets the DTX error as a NACK.

[0129] In a seventh communication 1022 transmitted from the BS 1002 to the TX UE 1004, the BS 1002 transmits a Mode 1 SL grant in a DCI to the TX UE 1004. In this embodiment, the Mode 1 SL grant includes information indicating a first TB for retransmission (e.g., TB1, the size of the first TB), HPID = 1, and NDI = 0. Therefore, the next DCI is transmitted, and the NDI is not switched for the same HARQ process ID.

[0130] The TX UE 1004 detects 1024 that there is no protocol error because the NDI is not switched from the perspective of the TX UE 1004. Therefore, the TX UE 1004 can operate as if no error has occurred.

[0131] In one embodiment, for NR Mode 1, if the TX UE reports a NACK to the BS when it has received a NACK for a groupcast or unicast transmission from the RX UE to request retransmission resources and instead the TX UE receives a DCI from the BS with a switched NDI compared to its current NDI state for the same HARQ process ID, the TX UE may behave in one of the following ways: 1) if the TX UE expects a retransmission grant, and if the TX UE can perform adaptive retransmission (e.g., by changing the code rate by appropriately selecting the MCS according to the resources allocated in the received DCI), once the TX UE considers that the NDI in the received DCI is switched, the received DCI grant can still be used for the retransmission of the pending transport block stored in the HARQ buffer for the HARQ process ID (e.g., if the TX UE reported a NACK for the previous SL transmission); or 2) the TX UE may retransmit the pending transport block (e.g., if it is stored for retransmission in the HARQ process) instead of using NR Mode 2 operation, in which the TX UE The UE may autonomously select a suitable resource for transmission from the set of candidate resources using a sensing method and set a selection window based on the remaining packet delay budget, and if the TX UE selects to use NR Mode 2 operation for retransmission, it may further select one of the following sub-embodiments to handle receiving a DCI grant from the base station: a) if the TX UE may use a different HARQ process ID internally for transmission to the receiver UE for sidelink transmission (e.g., by indicating a HARQ process ID within the SCI that is different from the HARQ process ID indicated within the DCI from the gNB); or b) the TX UE may decide to skip or ignore the received DCI grant and transmit an ACK to the BS as an enhancement.

[0132] In another embodiment, for NR mode 1, if the TX UE reports an ACK to the BS to request new transmission resources when an ACK for groupcast or unicast transmission has been received from the RX UE, but if the TX UE receives a DCI containing an NDI from the BS, for the same HARQ process ID, the TX UE believes that the NDI has not switched compared to its current state, then the TX UE behaves in one of the following ways: 1) if the TX UE can use a different HARQ process ID for sidelink transmission (e.g., indicated in the SCI), the TX UE follows the DCI grant received from the BS for the new sidelink transmission, and the HARQ process ID is indicated in the DCI from the BS; 2); the TX UE may decide to skip or ignore the received DCI grant and transmit an ACK to the BS; and / or 3) the TX UE may trigger a sidelink BSR report to the BS.

[0133] In one example, the embodiments described herein may be implemented in a MAC specification as shown in Table 2.

[0134] Table 2

[0135]

[0136] In certain embodiments, in NR Mode 1, the TX UE starts a timer after transmitting a NACK for a groupcast or unicast HARQ transmission (or retransmission) to the BS, and before the timer expires, the TX UE expects a retransmission grant from the BS. In such embodiments, while the timer is running, if the TX UE does not detect a DCI with the same HARQ ID for the process in which it transmitted the HARQ-NACK to the gNB, the TX UE may, upon detecting an error (e.g., when the timer expires and no DCI indicating retransmission resources is received), perform a retransmission of the previously pending transport block for which the NACK was sent to the BS by switching to NR Mode 2 operation for that HARQ process ID. In various embodiments, the TX UE may drop packets from its buffer and signal one or more RX UEs to clear the soft buffer for that HARQ process ID using the switched NDI within the SCI. In such an embodiment, the TX UE may choose to drop the packet or perform a retransmission in NR Mode 2 operation (e.g., if the packet delay budget still allows for the retransmission to be performed, based on the QoS priority of the packet to be transmitted and / or the congestion metric, the packet delay budget), then the UE may transition to Mode 2 and perform an autonomous retransmission. In some embodiments, the configuration of the timer may be set based on the packet delay budget. In some embodiments, the BS does not schedule a retransmission for the pending data packet because the PDB has been exceeded.

[0137] In various embodiments, there are misaligned counters between the gNB and the TX UE. In such embodiments, if there are errors between the gNB and the TX UE (e.g., lost DCI and DTX interpreted as ACK, NACK interpreted as ACK, ACK interpreted as NACK), the actual number of retransmissions (or redundancy version) signaled in the DCI between the TX UE and the gNB may be different from that used in the SCI transmitted between the TX UE and the RX UE. In one embodiment, if there is a mismatch between the number of retransmissions, the TX UE may ignore the redundancy version indicated by the gNB in ​​the DCI and transmit another redundancy version (e.g., the correct redundancy version) in the SCI. In another embodiment, the TX UE may indicate in uplink signaling to the BS (in L1, L2, and / or L3 signaling corresponding to the physical layer, MAC layer, or RRC signaling to the BS) about the redundancy version of the actual transmission between the TX UE and the RX UE via the signaled HARQ retransmission counter, one or more transmission parameters, and / or one or more HARQ parameters from the BS in the DCI and / or via the SCI.

[0138] In certain embodiments, if the gNB configures the TX UE with resources for "k" blind repetitions, and if the TX UE receives an ACK from the RX UE before the end period of the scheduled "k" repetitions, the TX UE may transmit an ACK to the gNB to release the SL resources for other SL transmissions. In such embodiments, the time domain configuration of the UL feedback resources (e.g., in terms of slots, mini-slots, or symbols) may be indicated dynamically or semi-statically via signaling.

[0139] In some embodiments, the gNB configures sidelink common feedback resources for each beam, spatial direction, or panel of the TX UE, and the TX UE may repeatedly transmit the same TB or perform multi-beam operation of the TB using beam scanning in different spatial directions and / or time domain. In such an embodiment, if the RX UE fails to decode a multicast or broadcast transport block in a certain slot, mini-slot, and / or symbol and in a certain spatial direction, the RX UE may choose to transmit a NACK through the sidelink feedback resources assigned for that specific beam, spatial direction, or panel.

[0140] In various embodiments, the TX UE may associate the received NACK with a specific beam, beam spatial direction, or panel based on the NACK received per beam, beam spatial direction, or panel. In such an embodiment, the TX UE may selectively retransmit in the specific beam, spatial direction, or panel. In addition, in such an embodiment, the resource configuration of the common NACK resource set may depend on the configuration of multiple beams or panels in the TX UE. In certain embodiments, the SL common feedback resources configured for each beam, spatial direction, or panel may be different in time, frequency, or code resource sets, and may be indicated via L1, L2, or L3 signaling.

[0141] Fig.11 11 is a block diagram illustrating one embodiment of a system 1100 including a TX UE 1102 that may be used in embodiments described herein. The TX UE 1102 includes a first common NACK resource 1104, a second common NACK resource 1106, a third common NACK resource 1108, and a fourth common NACK resource 1110.

[0142] Fig.12 1 is a flow chart illustrating one embodiment of a method 1200 for responding to a new data indicator for a hybrid automatic repeat request process. In some embodiments, the method 1200 is performed by an apparatus, such as a remote unit 102. In certain embodiments, the method 1200 may be performed by a processor executing program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0143] In various embodiments, the method 1200 includes determining 1202 whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, the method 1200 includes, in response to determining that the current new data indicator does not match the last received new data indicator, determining 1204 whether a negative acknowledgement has been transmitted in response to the last received sidelink grant. It should be noted that the negative acknowledgement is based on a negative acknowledgement received in the PSFCH from a RX UE (e.g., at least one RX UE from a multicast transmission).

[0144] In some embodiments, the method 1200 further includes, in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and the current new data indicator does not match the last received new data indicator of the first hybrid automatic repeat request process; switching from the first mode to the second mode for the first hybrid automatic repeat request process. In some embodiments, the method 1200 further includes, in response to determining: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and the current new data indicator does not match the last received new data indicator of the first hybrid automatic repeat request process; generating an autonomous hybrid automatic repeat request retransmission for a first transport block transmitted based on the last received sidelink grant.

[0145] In various embodiments, the method 1200 further includes, in response to determining that: a negative acknowledgement has been transmitted in response to the last received sidelink grant; and the current new data indicator does not match the last received new data indicator of the first hybrid automatic repeat request process; selecting a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; generating a second transport block corresponding to the current sidelink grant; storing the second transport block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process; and transmitting the second transport block in the second hybrid automatic repeat request process. In one embodiment, the method 1200 further includes, in response to determining: a negative acknowledgement has been transmitted in response to the last received sidelink grant; and the current new data indicator does not match the last received new data indicator of the first hybrid automatic repeat request process; ignoring or skipping the current sidelink grant and transmitting a positive acknowledgement to the base station.

[0146] In some embodiments, the method 1200 further includes, in response to determining that a positive acknowledgement has been transmitted in response to a last received sidelink grant: generating a second transport block corresponding to the current sidelink grant; and transmitting the second transport block in the first hybrid automatic repeat request process. In some embodiments, the method 1200 further includes, in response to the current new data indicator matching the last received new data indicator, determining whether a positive acknowledgement has been transmitted in response to a last received sidelink grant.

[0147] In various embodiments, the method 1200 further includes, in response to determining that a positive acknowledgement has been transmitted in response to the last received sidelink grant: considering the new data indicator to be toggled; generating a second transport block for the first hybrid automatic repeat request process according to the current sidelink grant; and transmitting the second transport block in the first hybrid automatic repeat request process. In one embodiment, the method 1200 further includes, in response to determining that a negative acknowledgement has been transmitted in response to the last received sidelink grant: performing a hybrid automatic repeat request retransmission of the first transport block stored in the hybrid automatic repeat request buffer for the first hybrid automatic repeat request process.

[0148] Fig.13 1 is a flow chart illustrating another embodiment of a method 1300 for responding to a new data indicator for a hybrid automatic repeat request process. In some embodiments, the method 1300 is performed by an apparatus, such as a remote unit 102. In certain embodiments, the method 1300 may be performed by a processor executing program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0149] In various embodiments, the method 1300 includes determining 1302 whether a current new data indicator in a current sidelink grant matches a last received new data indicator in a last received sidelink grant for a first hybrid automatic repeat request process. In some embodiments, the method 1300 includes, in response to determining that the current new data indicator matches the last received new data indicator, determining 1304 whether a positive acknowledgement has been transmitted in response to the last received sidelink grant.

[0150] In some embodiments, the method 1300 further includes, in response to determining that: a positive acknowledgement has been transmitted in response to a last received sidelink grant; and the current new data indicator matches the last received new data indicator for the first hybrid automatic repeat request process; deeming the new data indicator to be toggled. In some embodiments, the method 1300 further includes generating a second transport block for the first hybrid automatic repeat request process based on the current sidelink grant.

[0151] In various embodiments, the method 1300 further includes transmitting the second transport block in the first hybrid automatic repeat request process. In one embodiment, the method 1300 further includes, in response to determining that a negative acknowledgement has been transmitted in response to the last received sidelink grant: performing a hybrid automatic repeat request retransmission of the first transport block stored in the hybrid automatic repeat request buffer for the first hybrid automatic repeat request process.

[0152] In some embodiments, the method 1300 further includes, in response to the current new data indicator not matching the last received new data indicator, determining whether a negative acknowledgement has been transmitted in response to a last received sidelink grant. In some embodiments, the method 1300 further includes, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant: switching from a first mode to a second mode for a first hybrid automatic repeat request process; generating an autonomous hybrid automatic repeat request retransmission for a first transport block transmitted based on the last received sidelink grant; selecting a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; generating a second transport block corresponding to the current sidelink grant; storing the second transport block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process; and transmitting the second transport block in the second hybrid automatic repeat request process.

[0153] In various embodiments, the method 1300 further includes, in response to determining that a positive acknowledgement has been transmitted in response to the last received sidelink grant: generating a second transport block corresponding to the current sidelink grant; and transmitting the second transport block in the first hybrid automatic repeat request process.

[0154] In one embodiment, a method includes: determining whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator does not match the last received new data indicator, determining whether a negative acknowledgement has been transmitted in response to the last received side link grant.

[0155] In some embodiments, the method further includes, in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process; switching from a first mode to a second mode for the first hybrid automatic repeat request process.

[0156] In some embodiments, the method further includes, in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process; generating an autonomous hybrid automatic repeat request retransmission for a first transport block transmitted based on the last received sidelink grant.

[0157] In various embodiments, the method further includes, in response to determining: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process; selecting a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; generating a second transmit block corresponding to the current sidelink grant; storing the second transmit block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process; and transmitting the second transmit block in the second hybrid automatic repeat request process.

[0158] In one embodiment, the method further includes, in response to determining: a negative acknowledgment has been transmitted in response to a last received sidelink grant; and the current new data indicator does not match the last received new data indicator for the first hybrid automatic repeat request process; ignoring or skipping the current sidelink grant and transmitting a positive acknowledgment to the base station.

[0159] In some embodiments, the method further comprises: in response to determining that a positive acknowledgement has been transmitted in response to the last received sidelink grant: generating a second transport block corresponding to the current sidelink grant; and transmitting the second transport block in the first hybrid automatic repeat request process.

[0160] In some embodiments, the method further comprises, in response to the current new data indicator matching the last received new data indicator, determining whether a positive acknowledgement has been transmitted in response to a last received sidelink grant.

[0161] In various embodiments, the method further includes: in response to determining that a positive confirmation has been transmitted in response to the last received sidelink grant: deeming the new data indicator to be switched; generating a second transmission block for the first hybrid automatic repeat request process based on the current sidelink grant; and transmitting the second transmission block in the first hybrid automatic repeat request process.

[0162] In one embodiment, the method further comprises, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant: performing a hybrid automatic repeat request retransmission of the first transport block stored in a hybrid automatic repeat request buffer for the first hybrid automatic repeat request process.

[0163] In one embodiment, an apparatus includes: a processor that: determines whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator does not match the last received new data indicator, determines whether a negative acknowledgement has been transmitted in response to the last received side link grant.

[0164] In certain embodiments, the processor switches from a first mode to a second mode for the first hybrid automatic repeat request process in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process.

[0165] In some embodiments, the processor generates an autonomous hybrid automatic repeat request retransmission for a first transport block transmitted based on the last received sidelink grant in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process.

[0166] In various embodiments, the apparatus further includes a transmitter, wherein, in response to determining that: a negative acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process; the processor selects a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; the processor generates a second transmit block corresponding to the current sidelink grant; the processor stores the second transmit block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process, and the transmitter transmits the second transmit block in the second hybrid automatic repeat request process.

[0167] In one embodiment, the processor is responsive to determining that: a negative acknowledgment has been transmitted in response to a last received sidelink grant; and a current new data indicator does not match a last received new data indicator for a first hybrid automatic repeat request process; ignoring or skipping the current sidelink grant and transmitting a positive acknowledgment to the base station.

[0168] In certain embodiments, the apparatus further comprises a transmitter, wherein, in response to determining that a positive acknowledgement has been transmitted in response to a last received sidelink grant: the processor generates a second transport block corresponding to the current sidelink grant; and the transmitter transmits the second transport block in the first hybrid automatic repeat request process.

[0169] In some embodiments, in response to the current new data indicator matching the last received new data indicator, the processor determines whether a positive acknowledgement has been transmitted in response to a last received sidelink grant.

[0170] In various embodiments, the apparatus further includes a transmitter, wherein, in response to determining that a positive acknowledgement has been transmitted in response to a last received sidelink grant: the processor deems the new data indicator to be switched; the processor generates a second transport block for the first hybrid automatic repeat request process based on the current sidelink grant; and the transmitter transmits the second transport block in the first hybrid automatic repeat request process.

[0171] In one embodiment, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant: the processor performs a hybrid automatic repeat request retransmission of a first transport block stored in a hybrid automatic repeat request buffer for a first hybrid automatic repeat request process.

[0172] In one embodiment, a method includes: determining whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator matches the last received new data indicator, determining whether a positive acknowledgement has been transmitted in response to the last received side link grant.

[0173] In certain embodiments, the method further includes, in response to determining that: a positive acknowledgement has been transmitted in response to a last received sidelink grant; and the current new data indicator matches a last received new data indicator for the first hybrid automatic repeat request process; deeming the new data indicator to be toggled.

[0174] In some embodiments, the method further comprises generating a second transport block for the first hybrid automatic repeat request process according to the current sidelink grant.

[0175] In various embodiments, the method further includes transmitting the second transport block in the first hybrid automatic repeat request process.

[0176] In one embodiment, the method further comprises, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant: performing a hybrid automatic repeat request retransmission of the first transport block stored in a hybrid automatic repeat request buffer for the first hybrid automatic repeat request process.

[0177] In certain embodiments, the method further comprises, in response to the current new data indicator not matching the last received new data indicator, determining whether a negative acknowledgement has been transmitted in response to a last received sidelink grant.

[0178] In some embodiments, the method further includes, in response to determining that a negative acknowledgement has been transmitted in response to the last received sidelink grant: switching from a first mode to a second mode for a first hybrid automatic repeat request process; generating an autonomous hybrid automatic repeat request retransmission for a first transmit block transmitted based on the last received sidelink grant; selecting a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; generating a second transmit block corresponding to the current sidelink grant; storing the second transmit block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process; and transmitting the second transmit block in the second hybrid automatic repeat request process.

[0179] In various embodiments, the method further includes: in response to determining that a positive acknowledgement has been transmitted in response to the last received sidelink grant: generating a second transport block corresponding to the current sidelink grant; and transmitting the second transport block in the first hybrid automatic repeat request process.

[0180] In one embodiment, an apparatus includes: a processor that: determines whether a current new data indicator in a current side link grant matches a last received new data indicator in a last received side link grant for a first hybrid automatic repeat request process; and, in response to determining that the current new data indicator matches the last received new data indicator, determines whether a positive acknowledgement has been transmitted in response to the last received side link grant.

[0181] In certain embodiments, the processor considers the new data indicator to be toggled in response to determining that: a positive acknowledgement has been transmitted in response to a last received sidelink grant; and a current new data indicator matches a last received new data indicator for a first hybrid automatic repeat request process.

[0182] In some embodiments, the processor generates a second transport block for the first hybrid automatic repeat request process based on the current sidelink grant.

[0183] In various embodiments, the apparatus further includes a transmitter that transmits the second transport block in the first hybrid automatic repeat request process.

[0184] In one embodiment, the processor, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant, performs a hybrid automatic repeat request retransmission of a first transport block stored in a hybrid automatic repeat request buffer for a first hybrid automatic repeat request process.

[0185] In certain embodiments, the processor determines whether a negative acknowledgement has been transmitted in response to a last received sidelink grant in response to the current new data indicator not matching the last received new data indicator.

[0186] In some embodiments, the device further includes a transmitter, wherein, in response to determining that a negative acknowledgement has been transmitted in response to a last received sidelink grant: the processor switches from a first mode to a second mode for a first hybrid automatic repeat request process; the processor generates an autonomous hybrid automatic repeat request retransmission for a first transmit block transmitted based on the last received sidelink grant; the processor selects a second hybrid automatic repeat request process from a plurality of available hybrid automatic repeat request processes; the processor generates a second transmit block corresponding to the current sidelink grant; and the processor stores the second transmit block in a hybrid automatic repeat request buffer corresponding to the second hybrid automatic repeat request process; and the transmitter transmits the second transmit block in the second hybrid automatic repeat request process.

[0187] In various embodiments, the apparatus further comprises a transmitter, wherein, in response to determining that a positive acknowledgement has been transmitted in response to a last received sidelink grant: the processor generates a second transport block corresponding to the current sidelink grant; and the transmitter transmits the second transport block in a first hybrid automatic repeat request process.

[0188] Embodiments may be practiced in other specific forms. The described embodiments are considered in all respects to be illustrative only 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 base station for wireless communication, comprising: at least one memory; as well as at least one processor, the at least one processor being coupled to the at least one memory and configured to cause the base station to: transmitting a current sidelink grant to a user equipment (UE); as well as Responsive to a last transmitted sidelink grant and a current new data indicator (NDI) in a current sidelink grant transmitted for a first hybrid automatic repeat request (HARQ) process not matching a last transmitted NDI in the last transmitted sidelink grant, a positive acknowledgement is received from the UE.

2. The base station according to claim 1, wherein: To transmit the current sidelink grant, the at least one processor is configured to cause the NE to: Downlink control information (DCI) including the current sidelink grant is transmitted.

3. The base station according to claim 2, wherein: The transmitted current sidelink grant indicates the current NDI.

4. The base station according to claim 2, wherein: The transmitted current sidelink grant indicates the current HARQ process identifier.

5. The base station according to claim 1, wherein: The at least one processor is configured to cause the NE to: A final downlink control information (DCI) including the final sidelink grant is transmitted.

6. The base station according to claim 5, wherein: The last transmitted sidelink grant indicates the last transmitted NDI.

7. The base station according to claim 5, wherein: The last transmitted sidelink grant indicates the last HARQ process identifier.

8. A method for wireless communication, performed or executable by a base station, comprising: transmitting a current sidelink grant to a user equipment (UE); Responsive to a last transmitted sidelink grant and a current new data indicator (NDI) in a current sidelink grant transmitted for a first hybrid automatic repeat request (HARQ) process not matching a last transmitted NDI in the last transmitted sidelink grant, a positive acknowledgement is received from the UE.

9. The method according to claim 8, further comprising: Downlink control information (DCI) including the current sidelink grant is transmitted.

10. The method according to claim 9, wherein: The transmitted current sidelink grant indicates the current NDI.

11. The method according to claim 9, wherein: The transmitted current sidelink grant indicates the current HARQ process identifier.

12. The method according to claim 8, further comprising: A final downlink control information (DCI) including the final sidelink grant is transmitted.

13. The method according to claim 12, wherein: The last transmitted sidelink grant indicates the last transmitted NDI.

14. The method according to claim 12, wherein: The last transmitted sidelink grant indicates the last HARQ process identifier.

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