Combined Blind Retransmission and Feedback-Based Retransmission

Abstract

Apparatus, method, and system for combined blind and feedback-based retransmissions are disclosed. A method (500) includes determining (502) a number of blind retransmissions to perform in a blind retransmission mode for a first logical channel. The method (500) includes performing (504) the number of blind retransmissions in the blind retransmission mode by the first logical channel. The method (500) includes switching (506) the first logical channel from the blind retransmission mode to a feedback-based retransmission mode in response to performing the number of blind retransmissions in the blind retransmission mode. The method (500) includes performing (508) one or more feedback-based retransmissions in the feedback-based retransmission mode by the first logical channel.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority of U.S. Patent Application Serial No. 63 / 012,102, filed on April 18, 2020, by Prateek Basu Mallick, titled "APPARATUSES, METHODS, AND SYSTEMS FOR A MIXTURE OF BLIND RETRANSMISSION AND HARQ FEEDBACK - BASED RETRANSMISSION", which is hereby incorporated by reference in its entirety. Technical Field

[0003] The subject matter disclosed herein generally relates to wireless communication and, more particularly, to combined blind retransmission and feedback - based retransmission. Background Art

[0004] In some wireless communication networks, blind - based retransmissions may be performed. In some wireless communication networks, feedback - based retransmissions may be performed. Retransmissions may be better if performed using other methods. Summary of the Invention

[0005] Methods for combined blind retransmission and feedback - based retransmission are disclosed. Apparatuses and systems also perform the functions of these methods. One embodiment of a method includes determining, for a first logical channel, the number of blind retransmissions to be performed in a blind retransmission mode. In some embodiments, the method includes performing, via the first logical channel, the number of blind retransmissions in the blind retransmission mode. In various embodiments, the method includes switching, in response to performing the number of blind retransmissions in the blind retransmission mode, from the blind retransmission mode to a feedback - based retransmission mode for the first logical channel. In certain embodiments, the method includes performing, via the first logical channel, one or more feedback - based retransmissions in the feedback - based retransmission mode.

[0006] An apparatus for combined blind retransmission and feedback - based retransmission includes a processor that: determines, for a first logical channel, the number of blind retransmissions to be performed in a blind retransmission mode; performs, via the first logical channel, the number of blind retransmissions in the blind retransmission mode; switches, in response to performing the number of blind retransmissions in the blind retransmission mode, from the blind retransmission mode to a feedback - based retransmission mode for the first logical channel; and performs, via the first logical channel, one or more feedback - based retransmissions in the feedback - based retransmission mode.

[0007] One embodiment of a method for determining a minimum duration includes determining a minimum duration between a first resource for a hybrid automatic repeat request (HARQ) transmission of a block and a second resource for a HARQ transmission of the block, where the minimum duration includes the sum of: a first time to receive HARQ feedback; a second time to determine whether to perform a retransmission of the block; and a third time to retransmit the block.

[0008] An apparatus for determining a minimum duration includes a processor that determines a minimum duration between a first resource for a HARQ transmission of a block and a second resource for a HARQ transmission of the block, where the minimum duration includes the sum of: a first time to receive HARQ feedback; a second time to determine whether to perform a retransmission of the block; and a third time to retransmit the block. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more specific description of the embodiments briefly described above will be presented by reference to specific embodiments shown in the drawings. It should be understood that these drawings depict only some embodiments and are not to be considered limiting of the scope. The embodiments will be described and explained with additional specificity and detail by using the drawings, in which:

[0010] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for combined blind and feedback-based retransmissions;

[0011] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that can be used for combined blind and feedback-based retransmissions;

[0012] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that can be used for combined blind and feedback-based retransmissions;

[0013] Figure 4 is a diagram illustrating one embodiment of a method for hybrid feedback-based transmission;

[0014] Figure 5 is a flowchart illustrating one embodiment of a method for combined blind and feedback-based retransmissions; and

[0015] Figure 6 is a flowchart illustrating one embodiment of a method for determining a minimum duration. DETAILED DESCRIPTION

[0016] As will be appreciated by one of ordinary skill in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects that may generally be referred to herein as a "circuit," "module," or "system." Additionally, embodiments may take the form of a program product embodied in one or more computer-readable storage devices storing machine-readable code, computer-readable code, and / or program code referred to hereinafter as code. The storage device may be tangible, non-transitory, and / or non-transmissive. The storage device may not embody a signal. In certain embodiments, the storage device merely comprises a signal for accessing the code.

[0017] Certain functional units described in this specification may be labeled as modules for the purpose of more particularly emphasizing their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large scale integration ("VLSI") circuitry or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, and the like.

[0018] A module may also be implemented in code and / or software to be executed by various types of processors. The identified code modules may, for example, comprise one or more physical or logical blocks of executable code that may, for example, be organized as objects, procedures, or functions. However, the executable files of the identified modules need not physically be located together, but may comprise disparate instructions stored in different locations that, when logically connected together, comprise the module and implement the stated purpose of the module.

[0019] Indeed, a code module may be a single instruction or many instructions, and may even be distributed over several different code segments, different programs, and across several memory devices. Similarly, in this specification, operational data may be identified and illustrated within a module and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set or may be distributed over different locations, including on different computer-readable storage devices. Where a module or portion of a module is implemented in software, the software portion is stored on one or more computer-readable storage devices.

[0020] Any combination of one or more computer-readable media may be utilized. A computer-readable medium may be a computer-readable storage medium. A computer-readable storage medium may be a storage device that stores code. The storage device may be, by way of example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micro-mechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0021] More specific examples (a non-exhaustive list) of storage devices will include the following: an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or flash memory), a portable compact disc read-only memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0022] 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 conventional procedural programming languages such as the “C” programming language, and / or machine languages such as assembly language. The code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter case, the remote computer may be connected to the user's computer through any type of network, including a local area network (“LAN”) or a wide area network (“WAN”), or may be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0023] References in this specification to “one embodiment,” “an embodiment,” or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but rather mean “one or more but not all embodiments.” Unless expressly stated otherwise, the terms “comprises,” “comprising,” “has,” and their variants mean “including but not limited to.” Unless expressly stated otherwise, a list of items does not imply that any or all of the items are mutually exclusive. Unless expressly stated otherwise, the terms “a,” “an,” and “the” also refer to “one or more.”

[0024] In addition, the features, structures, or characteristics of the described embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of 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 with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring some aspects of the embodiments.

[0025] Aspects of the embodiments are described below with reference to the schematic flowcharts and / or schematic block diagrams of methods, apparatuses, systems, and program products according to the embodiments. It will be understood that each block of the schematic flowcharts and / or schematic block diagrams, and combinations of blocks in the schematic flowcharts 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 such that the instructions executed by the processor of the computer or other programmable data processing device create a means for implementing the functions / operations specified in the block or some blocks of the schematic flowchart and / or schematic block diagram.

[0026] The code can also be stored in a storage device that can direct a computer, other programmable data processing device, or other device to operate in a specific manner such that the instructions stored in the storage device produce an article of manufacture that includes instructions for implementing the functions / operations specified in the block or some blocks of the schematic flowchart and / or schematic block diagram.

[0027] The code can also be loaded onto a computer, other programmable data processing device, or other device such that a series of operational steps are performed on the computer, other programmable device, or other device to produce a computer-implemented process such that the code executed on the computer or other programmable device provides a process for implementing the functions / operations specified in the block or some blocks of the flowchart and / or block diagram.

[0028] The schematic flowcharts and / or schematic block diagrams in the drawings illustrate the possible architectures, functions, and operations of apparatuses, systems, methods, and program products according to different embodiments. In this regard, each block in the schematic flowcharts and / or schematic block diagrams can represent a module, segment, or portion of code that includes one or more executable instructions for implementing the specified logical function.

[0029] It should also be noted that in some alternative embodiments, the functions labeled in the blocks may not occur in the order labeled in the figures. For example, depending on the functions involved, two consecutive blocks shown may actually be executed substantially simultaneously, or these blocks may sometimes be executed in the reverse order. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks or portions of the illustrated figures.

[0030] Although various arrow types and line types may be employed in the flowcharts and / or block diagrams, it should be understood that they do not limit the scope of the corresponding embodiments. In fact, some arrows or other connectors may be used only to indicate the logical flow of the depicted embodiments. For example, an arrow may indicate a waiting or monitoring period of unspecified duration between the enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by a system based on dedicated hardware that performs a particular function or operation, or by a combination of dedicated hardware and code.

[0031] The description of the elements in each figure may refer to the elements of the foregoing figures. The same numbers refer to the same elements in all figures, including alternative embodiments of the same element.

[0032] Figure 1 Embodiments of a wireless communication system 100 for combining blind retransmission and feedback-based transmission are 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, those 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.

[0033] In one embodiment, the remote unit 102 may include a computing device such as a desktop computer, laptop computer, personal digital assistant (“PDA”), tablet computer, smart phone, smart TV (e.g., a TV connected to the Internet), set-top box, game console, security system (including surveillance cameras), in-vehicle computer, network device (e.g., router, switch, modem), airborne vehicle, drone, etc. In some embodiments, the remote unit 102 includes a wearable device such as a smart watch, fitness band, optical head-mounted display, etc. Additionally, the remote unit 102 may be referred to as a subscriber unit, mobile device, mobile station, user, terminal, mobile terminal, fixed terminal, subscriber station, UE, user terminal, 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 certain embodiments, the remote unit 102 may communicate directly with other remote units 102 via sidelink communication.

[0034] The network unit 104 can be distributed over a geographical area. In some embodiments, the network unit 104 may also be referred to as and / or may include an access point, access terminal, base, base station, core network (“CN”), radio network entity, Node - B, evolved Node - B (“eNB”), 5G Node - B (“gNB”), home Node - B, relay node, device, core network, air server, radio access node, access point (“AP”), New Radio (“NR”), network entity, Access and Mobility Management Function (“AMF”), Unified Data Management (“UDM”), Unified Data Repository (“UDR”), UDM / UDR, Policy Control Function (“PCF”), Radio Access Network (“RAN”), Network Slice Selection Function (“NSSF”), Operations, Administration and Management (“OAM”), Session Management Function (“SMF”), User Plane Function (“UPF”), Application Function, Authentication Server Function (“AUSF”), Security Anchor Functionality (“SEAF”), Trusted non - 3GPP Gateway Function (“TNGF”), or any other term used in the art. The network unit 104 is generally part of a radio access network that includes one or more controllers communicatively coupled to one or more corresponding network units 104. The radio access network is generally communicatively coupled to one or more core networks, which may be coupled to other networks such as the Internet and the public switched telephone network and other such networks. 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.

[0035] In one implementation, the wireless communication system 100 complies with the NR protocol standardized in the Third Generation Partnership Project (“3GPP”), where the network unit 104 transmits on the downlink (“DL”) using an OFDM modulation scheme, and the remote unit 102 transmits on the uplink (“UL”) using a single - carrier frequency - division multiple access (“SC - FDMA”) scheme or an orthogonal frequency - division multiplexing (“OFDM”) scheme. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication protocols, e.g., WiMAX, Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 variants, Global System for Mobile Communications (“GSM”), General Packet Radio Service (“GPRS”), Universal Mobile Telecommunications System (“UMTS”), Long Term Evolution (“LTE”) variants, Code Division Multiple Access 2000 (“CDMA2000”), ZigBee, Sigfox, etc. protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0036] The network element 104 can serve multiple remote units 102 within a service area such as a cell or a cell sector via a wireless communication link. The network element 104 transmits DL communication signals to serve the remote units 102 in the time, frequency, and / or spatial domain.

[0037] In various embodiments, the remote unit 102 and / or the network element 104 can determine the number of blind retransmissions to be performed in the blind retransmission mode for a first logical channel. In some embodiments, the remote unit 102 and / or the network element 104 can perform the number of blind retransmissions in the blind retransmission mode via the first logical channel. In various embodiments, the remote unit 102 and / or the network element 104 can switch from the blind retransmission mode to the feedback-based retransmission mode for the first logical channel in response to performing the number of blind retransmissions in the blind retransmission mode. In certain embodiments, the remote unit 102 and / or the network element 104 can perform one or more feedback-based retransmissions in the feedback-based retransmission mode via the first logical channel. Thus, the remote unit 102 and / or the network element 104 can be used for combined blind retransmission and feedback-based retransmission.

[0038] In certain embodiments, the remote unit 102 and / or the network element 104 can determine the minimum duration between a first resource for transmitting a hybrid automatic repeat request (HARQ) transmission of a block and a second resource for transmitting the HARQ transmission of the block, where the minimum duration includes the sum of: a first time for receiving the HARQ feedback; a second time for determining whether to perform a retransmission of the block; and a third time for retransmitting the block. Thus, the remote unit 102 and / or the network element 104 can be used to determine the minimum duration.

[0039] Figure 2 An embodiment of an apparatus 200 that can be used for combined blind retransmission and feedback-based retransmission is depicted. The apparatus 200 includes an embodiment of the remote unit 102. Additionally, the remote unit 102 can 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 certain embodiments, the remote unit 102 may not include any input device 206 and / or display 208. In various embodiments, the remote unit 102 can 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.

[0040] In one embodiment, processor 202 may include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, 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, processor 202 executes instructions stored in memory 204 to perform the methods and routines described herein. Processor 202 is communicatively coupled to memory 204, input device 206, display 208, transmitter 210, and receiver 212.

[0041] 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 disk drive, a 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 and controller algorithms operating on remote unit 102 or other.

[0042] In one embodiment, input device 206 may include any known computer input device, including a touchpad, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, input device 206 may be integrated with display 208, for example, as a touchscreen or a similar touch-sensitive display. In some embodiments, input device 206 includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and / or by handwriting on the touchscreen. In some embodiments, input device 206 includes two or more different devices such as a keyboard and a touch panel.

[0043] 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, a liquid crystal display ("LCD"), a light emitting diode ("LED") display, an organic light emitting diode ("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.

[0044] 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 located near the input device 206.

[0045] In various embodiments, the processor 202 may: determine the number of blind retransmissions to be performed in a blind retransmission mode for a first logical channel; perform the number of blind retransmissions in the blind retransmission mode through the first logical channel; in response to performing the number of blind retransmissions in the blind retransmission mode, switch from the blind retransmission mode to a feedback-based retransmission mode for the first logical channel; and perform one or more feedback-based retransmissions in the feedback-based retransmission mode through the first logical channel.

[0046] In some embodiments, the processor 202 determines a minimum duration between a first resource used for hybrid automatic repeat request transmission of a transport block and a second resource used for hybrid automatic repeat request transmission of the transport block, wherein the minimum duration comprises a sum of: a first time of receiving hybrid automatic repeat request feedback; a second time of determining whether to perform a retransmission of the transport block; and a third time of retransmitting the transport block.

[0047] Although only one transmitter 210 and one receiver 212 are illustrated, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitters 210 and receivers 212 may be of any suitable type of transmitter and receiver. In one embodiment, the transmitters 210 and receivers 212 may be part of a transceiver.

[0048] Figure 3 An embodiment of an apparatus 300 that can be used for combined blind retransmission and feedback-based retransmission is depicted. The apparatus 300 includes an embodiment of a network unit 104. Additionally, 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 can be 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.

[0049] In various embodiments, the processor 302 may: determine the number of blind retransmissions to be performed in the blind retransmission mode for a first logical channel; perform that number of blind retransmissions in the blind retransmission mode via the first logical channel; switch from the blind retransmission mode to the feedback-based retransmission mode for the first logical channel in response to performing that number of blind retransmissions in the blind retransmission mode; and perform one or more feedback-based retransmissions in the feedback-based retransmission mode via the first logical channel.

[0050] In certain embodiments, the processor 302 determines the minimum duration between a first resource for transmitting a hybrid automatic repeat request (HARQ) transmission of a block and a second resource for transmitting a HARQ transmission of the block, where the minimum duration includes the sum of: a first time to receive HARQ feedback; a second time to determine whether to perform a retransmission of the transmitted block; and a third time to retransmit the transmitted block.

[0051] In various embodiments, such as in a new radio (“NR”) vehicle-to-everything (“V2X”), a transmitting user equipment (“UE”) may pick to look for hybrid automatic repeat request (“HARQ”) feedback to determine whether further retransmissions are needed, or whether multiple blind retransmissions can be performed (e.g., retransmissions without seeking HARQ feedback).

[0052] In some embodiments, such as in sidelink (“SL”) V2X, retransmissions may use a hybrid of blind retransmissions and feedback-based retransmissions of the same transport block (“TB”) to achieve sidelink performance advantages. In such embodiments, while it is possible to dynamically enable and / or disable (e.g., seek and / or not seek) SL HARQ feedback in the SL physical layer (“PHY”) using sidelink control information, this can lead to a number of problems (e.g., if feedback is expected, the media access control (“MAC”) layer may not be sure why it did not receive feedback and may make an incorrect decision (e.g., decide to perform a retransmission); or the MAC layer may receive feedback that is not expected because feedback was not sought. Additionally, radio resource control (“RRC”) configurations that enable and / or disable HARQ feedback for each logical channel may not support a hybrid of blind retransmissions and HARQ feedback-based retransmissions.

[0053] In some embodiments, a hybrid of blind retransmissions and HARQ feedback-based transmissions for a TB if a logical channel (“LCH”) is RRC-configured for SL HARQ enablement and / or disablement.

[0054] Figure 4 FIG. is a diagram illustrating one embodiment of method 400 for hybrid feedback-based transmission. Method 400 includes receiving 402 a sidelink grant and selecting 404 a destination. Method 400 also includes determining 406 whether a transmission based on hybrid feedback (e.g., a combination of blind retransmissions and feedback-based retransmissions) is needed. If a transmission based on hybrid feedback is needed, method 400 includes determining 408 x’. x’ is the number of blind retransmissions to be performed. Method 400 then includes performing 410 x’ blind retransmissions. In response to completing the x’ blind retransmissions, method 400 switches 412 to HARQ feedback-based retransmissions, and method 400 ends 414. If a transmission based on hybrid feedback is not needed, method 400 includes performing 416 HARQ feedback-based retransmissions, and method 400 ends 414.

[0055] In some embodiments, there is a new RRC configuration that enables some LCHs to operate in a hybrid feedback mode (e.g., a mode with a combination of blind retransmissions and feedback-based retransmissions) or a no-feedback mode is used by using new code points in the RRC LCH SL HARQ configuration. No-feedback mode transmissions (e.g., blind retransmissions) can be performed for a predetermined or variable number of transmissions. After a predetermined or variable number (x’) of transmissions, the transmitter can switch to and can remain in a mode with HARQ feedback. The number x’ can be pre-configured or can be determined using various methods, such as those described herein. The variability in the number of no-feedback transmissions can be based on changing channel conditions, etc.

[0056] In various embodiments, an LCH operating in a hybrid feedback mode can be considered for resource allocation together with other logical channels with HARQ feedback enabled or disabled.

[0057] In some embodiments, an LCH operating in a hybrid feedback mode can be considered for resource allocation only with other logical channels having the same HARQ feedback mode (e.g., logical channels in a hybrid feedback mode).

[0058] In a first example, feedback can be enabled for a first LCH, and a second LCH can be in a hybrid feedback mode. In this example, the first and second LCHs included in the same transport block can perform a certain number of blind retransmissions ("BR") (e.g., x'), and then perform one feedback ("FB")-based HARQ retransmission seeking HARQ feedback ("HF"). This can ensure that each intended receiver that has not successfully received a Physical SideLink Shared Channel ("PSSCH") transmission can provide negative acknowledgment ("NACK") feedback, and can also avoid decoding PSSCH transmissions and feedback transmissions that have been successfully received by other intended receivers.

[0059] In a second example, feedback can be disabled for a first LCH, and a second LCH can be in a hybrid feedback mode. In one implementation of this example, the first and second LCHs included in the same transport block can perform only BR. In another implementation of this example, a certain number of blind retransmissions can be performed, and then one FB-based HARQ retransmission can be performed by the first and second LCHs included in the same transport block.

[0060] In a third example, two LCHs can be in a hybrid feedback mode. In this example, the two LCHs included in the same transport block can perform a certain number of BR (e.g., x'), and then perform one FB-based HARQ retransmission seeking HF.

[0061] Various examples are shown in Table 1.

[0062] Table 1

[0063] LCH1 LCH2 Transmission + Retransmission Hybrid Enabled n Blind Transmissions + 1 or More Feedback - Based Retransmissions Hybrid Enabled Feedback - Based Retransmissions Only Hybrid Disabled Blind Retransmissions Only Hybrid Disabled n Blind Transmissions + 1 or More Feedback - Based Retransmissions

[0064] In some embodiments, there may not be a new RRC configuration that allows some LCHs to operate in a hybrid feedback mode (or equivalently, a no-feedback mode). In such embodiments, only two scenarios occur: 1) TBs that only contain feedback-enabled LCHs, where a certain number of BRs (e.g., x’) are generated, and one FB-based HARQ retransmission is performed to seek HF; 2) TBs that only contain feedback-disabled LCHs: In one implementation, only BRs may be performed - In another implementation, a certain number of blind retransmissions may be performed, followed by one FB-based HARQ retransmission.

[0065] In various embodiments, if the requested feedback option is the HF option 2, the transmitting or transmitter (“TX”) UE counts the number of NACK and / or discontinuous transmission (“DTX”) feedbacks (e.g., total_failures). If total_failures exceeds a threshold (e.g., threshold_total_failures), the TX UE performs “x” blind retransmissions.

[0066] In certain embodiments, the hybrid HARQ operation mode is implemented as HARQ-enabled transmission, where the UE autonomously triggers retransmissions in the absence of receiving HARQ feedback from the RX UE.

[0067] In some embodiments, if the MAC layer has determined that a TB only contains LCHs with HF enabled as a result of logical channel prioritization (“LCP”), the MAC layer delivers the TB to the PHY layer and the PHY layer may further decide to transmit the TB in “hybrid mode” based on the current channel conditions (e.g., the priority of the TB, etc.). In one example, in hybrid mode, the first x HARQ transmissions of the TB do not request HARQ feedback in the sidelink control information (“SCI”), and for the X+1 transmission, the UE may request HARQ feedback from the receiving UE in the SCI. For the first “X” retransmissions, the PHY layer will trigger some autonomous retransmissions from the MAC layer - by internally indicating to the MAC layer a “NACK” for the determined number of BRs (e.g., x’ transmissions) - without receiving HARQ feedback from any receiver or receiving (“RX”) UE on the physical sidelink feedback channel (“PSFCH”).

[0068] In such embodiments, from the perspective of the MAC layer, “hybrid mode” operation is considered similar to standard HARQ-enabled transmission. Thus, the MAC layer is not aware of whether the HARQ feedback delivered from the PHY layer is internally triggered and / or autonomously triggered, or derived based on HARQ feedback received from the receiving UE on the PSFCH.

[0069] In some embodiments, if the MAC layer has determined, as a result of LCP, that the TB only contains LCHs with disabled HF, the MAC layer delivers the TB to the PHY layer, and the PHY layer may further decide to transmit the TB in "hybrid mode" based on the current channel conditions, the priority of the TB, etc. In one example, in the hybrid feedback mode, the first x HARQ transmissions of the TB do not request HARQ feedback in the SCI, and for the X+1-th transmission (and subsequent retransmissions), HARQ feedback from the receiving UE is requested in the SCI. For the first X+1 retransmissions (and subsequent retransmissions), the PHY layer may initiate HARQ feedback-based retransmissions. Retransmissions may be performed when "NACK" feedback or DTX is received from one or more receivers, otherwise (e.g., all received HARQ feedback is acknowledgement ("ACK") feedback), no further retransmissions are performed. From the perspective of the MAC layer, the "hybrid mode" is considered a normal HARQ-enabled transmission.

[0070] In various embodiments, a minimum duration may be defined to represent the minimum time period between two HARQ transmissions of a transport block, and may be considered by the TX UE during SL resource selection.

[0071] In certain embodiments, the SL resources for all HARQ transmissions (or retransmissions) of the TB may be picked by the TX UE such that there is sufficient time in the time domain for the TX UE to receive HARQ feedback for the HARQ transmission of the TB on the PSFCH from the RX UE and decide whether to perform a further HARQ transmission (or retransmission) for the TB and perform the HARQ retransmission. As can be appreciated, the new minimum duration parameter may be beneficial for scenarios where the MAC layer of the TX UE selects SL resources for x' blind HARQ transmissions of the TB and after the y-th transmission, the PHY layer of the TX UE decides to ask for HARQ feedback from the receiving UE to determine whether a further HARQ transmission is necessary, where y is less than x.

[0072] In some embodiments, the PHY layer of the TX UE indicates to the MAC layer that there should be sufficient time between transmissions of the TB for SL resource selection to allow for the collection of HARQ feedback. The minimum time distance between HARQ transmissions of the TB may be signaled from the PHY layer to the MAC layer as a new input parameter for the SL resource selection process. In one example, the minimum processing time may represent the minimum time between two HARQ transmissions, similar to the HARQ round-trip time ("RTT") value or K3 value for the Uu interface. In various embodiments, the new parameter minimum time distance between HARQ transmissions of the TB may be a fixed predefined value or may be defined according to UE capabilities.

[0073] In some embodiments, if the LCP results in a TB with an LCH configured for the hybrid mode, the PHY layer may be allowed to use only the hybrid operation mode. In such embodiments, the RRC may configure some LCHs with a "hybrid feedback mode".

[0074] In various embodiments, x' may be determined as follows: 1) The total number of transmissions may depend on one or more of the following: link budget requirements that can be determined and / or mapped from the minimum communication range ("MCR"), SL path loss (e.g., for unicast), allowed MCS (e.g., code rate), transmit power of the TX UE (e.g., for MCR "a" and MCR "b", the total number of transmissions may vary; for multicast communication, the worst path loss is used if available); 2) The total number of BRs and feedback-based HARQ transmissions ("HFBT") may depend on the total reliability to be achieved for a given latency bound (e.g., packet delay budget ("PDB")).

[0075] In one example, the first UE determines the number of BRs to perform for a given PDB, and then the UE decides to enable retransmissions with HARQ feedback.

[0076] In another example, the PDB or the remaining PDB may be used to determine how many feedback-based transmissions can be used given the RTT between the transmission and reception of the corresponding HARQ feedback. If this would be less than the value required to achieve a given reliability for a given MCR, the TX UE may save time by making certain blind transmissions (or retransmissions). As can be appreciated, the terms transmission and retransmission may be used interchangeably herein. A transmission may be the first transmission or a retransmission, and a retransmission may refer to the first transmission.

[0077] Table 2 illustrates an example of the above embodiments.

[0078] Table 2

[0079] Reliability (LCH Priority) MCR#1 MCR#2 99%, 5ms PDB 3BT 5BT 99.9%, 10ms PDB 4BT 6BT 99.999%, 10ms PDB 4BT, 1HFBT 5BT, 1HFBT 99.999%, 5ms PDB 5BT, 1HFBT 6BT, 1HFBT

[0080] In some embodiments, x' may be determined as the floor value of the HARQ operating point. The floor value may mean the largest integer value less than (or equal to) the HARQ operating point. The HARQ operating point itself may be determined using statistical observations on the PC5 link for the same destination or other destinations of the same or different playback types.

[0081] Figure 5FIG. is a flowchart of one embodiment of method 500 for combining blind retransmission and feedback-based retransmission. In some embodiments, method 500 is performed by a device such as remote unit 102 and / or network unit 104. In certain embodiments, method 500 may be performed by a processor executing program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0082] In various embodiments, method 500 includes determining 502 the number of blind retransmissions to perform in the blind retransmission mode for a first logical channel. In some embodiments, method 500 includes performing 504 that number of blind retransmissions in the blind retransmission mode via the first logical channel. In various embodiments, method 500 includes switching 506 from the blind retransmission mode to the feedback-based retransmission mode for the first logical channel in response to performing that number of blind retransmissions in the blind retransmission mode. In certain embodiments, method 500 includes performing 508 one or more feedback-based retransmissions in the feedback-based retransmission mode via the first logical channel.

[0083] In certain embodiments, the first logical channel is part of a plurality of logical channels, and the plurality of logical channels includes a second logical channel that operates only in the feedback-based retransmission mode. In some embodiments, the second logical channel operates with feedback enabled. In various embodiments, the second logical channel operates with feedback disabled.

[0084] In one embodiment, one or more feedback-based retransmissions in the feedback-based retransmission mode include only one feedback-based retransmission. In certain embodiments, the number of blind retransmissions is pre-determined, variable, calculated, or some combination thereof. In some embodiments, the first logical channel is part of a plurality of logical channels, the plurality of logical channels is used for resource allocation of the first logical channel, and the plurality of logical channels includes at least one channel that operates only in the feedback-based retransmission mode.

[0085] In various embodiments, the first logical channel is part of a plurality of logical channels, the plurality of logical channels is used for resource allocation of the first logical channel, and the plurality of logical channels includes only channels that operate in both the blind retransmission mode and the feedback-based retransmission mode. In one embodiment, method 500 further includes determining whether to operate in a hybrid mode that includes the blind retransmission mode and the feedback-based retransmission mode. In certain embodiments, determining whether to operate in the hybrid mode includes: determining whether to operate in the hybrid mode based on channel conditions, the priority of the transport block, or a combination thereof.

[0086] In some embodiments, performing the number of blind retransmissions in the blind retransmission mode includes the physical layer indicating a negative acknowledgment to the media access control layer for each blind retransmission of the number of blind retransmissions. In various embodiments, the number of blind retransmissions is based on link budget requirements, sidelink path loss, code rate, transmit power, reliability, packet delay budget, remaining packet delay budget, or a combination thereof.

[0087] Figure 6 FIG. 4 is a flowchart illustrating an embodiment of a method 600 for determining a minimum duration. In some embodiments, method 600 is performed by a device such as remote unit 102 and / or network unit 104. In certain embodiments, method 600 may be performed by a processor executing program code such as a microcontroller, microprocessor, CPU, GPU, auxiliary processing unit, FPGA, etc.

[0088] In various embodiments, method 600 includes determining 602 a minimum duration between a first resource for a hybrid automatic repeat request transmission of a block and a second resource for a hybrid automatic repeat request transmission of the block, where the minimum duration includes the sum of: a first time to receive hybrid automatic repeat request feedback; a second time to determine whether to perform a retransmission of the block; and a third time to retransmit the block.

[0089] In certain embodiments, method 600 further includes sending the minimum duration from the physical layer to the media access control layer. In some embodiments, method 600 further includes selecting the first resource and the second resource based on the minimum duration. In various embodiments, the media access control layer selects the first resource and the second resource.

[0090] In one embodiment, a method includes: determining, for a first logical channel, a number of blind retransmissions to perform in a blind retransmission mode; performing, via the first logical channel, the number of blind retransmissions in the blind retransmission mode; in response to performing the number of blind retransmissions in the blind retransmission mode, switching, for the first logical channel, from the blind retransmission mode to a feedback-based retransmission mode; and performing, via the first logical channel, one or more feedback-based retransmissions in the feedback-based retransmission mode.

[0091] In certain embodiments, the first logical channel is part of a plurality of logical channels, and the plurality of logical channels includes a second logical channel that operates only in a feedback-based retransmission mode.

[0092] In some embodiments, the second logical channel operates with feedback enabled.

[0093] In various embodiments, the second logical channel operates with feedback disabled.

[0094] In one embodiment, one or more feedback-based retransmissions in a feedback-based retransmission mode include only one feedback-based retransmission.

[0095] In certain embodiments, the number of blind retransmissions is predetermined, variable, calculated, or some combination thereof.

[0096] In some embodiments, the first logical channel is part of a plurality of logical channels used for resource allocation of the first logical channel, and the plurality of logical channels includes at least one channel that operates only in a feedback-based retransmission mode.

[0097] In various embodiments, the first logical channel is part of a plurality of logical channels used for resource allocation of the first logical channel, and the plurality of logical channels includes only channels that operate in both a blind retransmission mode and a feedback-based retransmission mode.

[0098] In one embodiment, the method further includes determining whether to operate in a hybrid mode that includes a blind retransmission mode and a feedback-based retransmission mode.

[0099] In certain embodiments, determining whether to operate in a hybrid mode includes: determining whether to operate in a hybrid mode based on channel conditions, the priority of the transport block, or a combination thereof.

[0100] In some embodiments, performing the number of blind retransmissions in a blind retransmission mode includes: the physical layer indicating a negative acknowledgment to the media access control layer for each of the number of blind retransmissions.

[0101] In various embodiments, the number of blind retransmissions is based on link budget requirements, sidelink path loss, code rate, transmit power, reliability, packet delay budget, remaining packet delay budget, or a combination thereof.

[0102] In one embodiment, an apparatus includes: a processor that: determines the number of blind retransmissions to perform in a blind retransmission mode for a first logical channel; performs the number of blind retransmissions in the blind retransmission mode via the first logical channel; switches from the blind retransmission mode to a feedback-based retransmission mode for the first logical channel in response to performing the number of blind retransmissions in the blind retransmission mode; and performs one or more feedback-based retransmissions in the feedback-based retransmission mode via the first logical channel.

[0103] In certain embodiments, the first logical channel is part of a plurality of logical channels, and the plurality of logical channels includes a second logical channel that operates only in a feedback-based retransmission mode.

[0104] In some embodiments, the second logical channel operates with feedback enabled.

[0105] In various embodiments, the second logical channel operates without feedback.

[0106] In one embodiment, one or more feedback-based retransmissions in a feedback-based retransmission mode include only one feedback-based retransmission.

[0107] In certain embodiments, the number of blind retransmissions is predetermined, variable, calculated, or some combination thereof.

[0108] In some embodiments, the first logical channel is part of a plurality of logical channels for resource allocation of the first logical channel, and the plurality of logical channels includes at least one channel that operates only in a feedback-based retransmission mode.

[0109] In various embodiments, the first logical channel is part of a plurality of logical channels for resource allocation of the first logical channel, and the plurality of logical channels includes only channels that operate in both a blind retransmission mode and a feedback-based retransmission mode.

[0110] In one embodiment, the processor determines whether to operate in a hybrid mode that includes a blind retransmission mode and a feedback-based retransmission mode.

[0111] In certain embodiments, the processor's determination of whether to operate in a hybrid mode includes the processor determining whether to operate in a hybrid mode based on channel conditions, the priority of the transport block, or a combination thereof.

[0112] In some embodiments, the processor's execution of that number of blind retransmissions in the blind retransmission mode includes: the physical layer indicating a negative acknowledgment to the media access control layer for each of that number of blind retransmissions.

[0113] In various embodiments, the number of blind retransmissions is based on link budget requirements, sidelink path loss, code rate, transmit power, reliability, packet delay budget, remaining packet delay budget, or a combination thereof.

[0114] In one embodiment, a method includes: determining a minimum duration between a first resource for hybrid automatic repeat request transmission of a transport block and a second resource for hybrid automatic repeat request transmission of the transport block, where the minimum duration includes the sum of: a first time to receive hybrid automatic repeat request feedback; a second time to determine whether to perform a retransmission of the transport block; and a third time to retransmit the transport block.

[0115] In certain embodiments, the method further includes sending the minimum duration from the physical layer to the media access control layer.

[0116] In some embodiments, the method further includes selecting the first resource and the second resource based on the minimum duration.

[0117] In various embodiments, the media access control layer selects a first resource and a second resource.

[0118] In one embodiment, an apparatus includes: a processor that determines a minimum duration between a first resource for a hybrid automatic repeat request transmission of a block and a second resource for a hybrid automatic repeat request transmission of the block, wherein the minimum duration includes a sum of: a first time to receive a hybrid automatic repeat request feedback; a second time to determine whether to perform a retransmission of the block; and a third time to retransmit the block.

[0119] In certain embodiments, the processor sends the minimum duration from the physical layer to the media access control layer.

[0120] In some embodiments, the processor selects the first resource and the second resource based on the minimum duration.

[0121] In various embodiments, the media access control layer selects a first resource and a second resource.

[0122] The embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only illustrative and not restrictive. Thus, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalency of the claims are embraced within their scope.

Claims

1. A method for combined blind retransmission and feedback - based retransmission, comprising: Determining, for a first logical channel, the number of blind retransmissions to be performed in a blind retransmission mode; Performing, via the first logical channel, the number of blind retransmissions in the blind retransmission mode; In response to performing the number of blind retransmissions in the blind retransmission mode, switching, for the first logical channel, from the blind retransmission mode to a feedback - based retransmission mode; And Performing, via the first logical channel, one or more feedback - based retransmissions in the feedback - based retransmission mode.

2. The method according to claim 1, wherein The first logical channel is part of a plurality of logical channels, and the plurality of logical channels includes a second logical channel that operates only in the feedback - based retransmission mode.

3. The method according to claim 2, wherein The second logical channel operates with feedback enabled.

4. The method according to claim 2, wherein The second logical channel operates with feedback disabled.

5. The method according to claim 1, wherein The one or more feedback - based retransmissions in the feedback - based retransmission mode include only one feedback - based retransmission.

6. The method according to claim 1, wherein, The number of blind retransmissions is predetermined, variable, calculated, or some combination thereof.

7. The method according to claim 1, wherein The first logical channel is part of a plurality of logical channels that are used for resource allocation for the first logical channel, and the plurality of logical channels includes at least one channel that operates only in the feedback - based retransmission mode.

8. The method according to claim 1, wherein The first logical channel is part of a plurality of logical channels that are used for resource allocation for the first logical channel, and the plurality of logical channels includes only channels that operate in both the blind retransmission mode and the feedback - based retransmission mode.

9. The method according to claim 1, further comprising determining whether to operate in a hybrid mode that includes the blind retransmission mode and the feedback - based retransmission mode.

10. The method according to claim 9, wherein, Determining whether to operate in the hybrid mode includes: determining whether to operate in the hybrid mode based on channel conditions, the priority of the transport block, or a combination thereof.

11. The method according to claim 1, wherein, Performing the number of blind retransmissions in the blind retransmission mode includes: the physical layer indicating a negative acknowledgment to the media access control layer for each of the number of blind retransmissions.

12. The method according to claim 1, wherein, The number of blind retransmissions is based on link - budget requirements, sidelink path loss, code rate, transmit power, reliability, packet delay budget, remaining packet delay budget, or a combination thereof.

13. An apparatus for combined blind retransmission and feedback - based retransmission, comprising: A processor, the processor: Determining, for a first logical channel, the number of blind retransmissions to be performed in a blind retransmission mode; Performing, via the first logical channel, the number of blind retransmissions in the blind retransmission mode; In response to performing the number of blind retransmissions in the blind retransmission mode, switching, for the first logical channel, from the blind retransmission mode to a feedback - based retransmission mode; And Performing, via the first logical channel, one or more feedback - based retransmissions in the feedback - based retransmission mode.

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