Flexible HARQ Mechanism Adaptation for Sidelink Unicast and Multicast

Abstract

Embodiments of apparatuses, systems, and methods for enabling flexible acknowledgments for a user equipment (UE) and a network are presented. The UE may determine whether to request feedback (e.g., HARQ ACK / NACK) for one or more multicast transmissions. The determination may be based on factors such as the remaining time to perform the transmission and the amount of time required to perform the transmission given the time available or not available to receive and process feedback.

Description

Technical Field

[0001] This application relates to wireless devices, and more particularly to apparatuses, systems, and methods for flexible acknowledgment. Background Art

[0002] The use of wireless communication systems is growing rapidly. Additionally, wireless communication technology has evolved from voice - only communication to also include the transmission of data such as Internet and multimedia content.

[0003] Mobile electronic devices can take the form of smartphones or tablets that users typically carry. Wearable devices (also known as accessory devices) are a newer form of mobile electronic device, an example being a smartwatch. Additionally, low - cost, low - complexity wireless devices intended for static or dynamic deployment are also increasing rapidly as part of the development of the "Internet of Things". In other words, the complexity, capabilities, traffic patterns, and other characteristics of the required devices are becoming increasingly diverse.

[0004] One problem in wireless communication includes how or whether to mix transmission types in sidelink (e.g., device - to - device) operations. For example, some transmissions can be associated with blind retransmissions, while other transmissions can be associated with feedback - based retransmissions (e.g., hybrid automatic repeat request (HARQ) operations). Therefore, improvements in this field are desired. Summary of the Invention

[0005] Embodiments of systems, apparatuses, and methods for flexible acknowledgment, particularly for wireless devices and networks, are presented herein.

[0006] In some embodiments, (e.g., among various possibilities such as in a New Radio (NR) Vehicle - to - Everything (V2X) communication system or other sidelink or device - to - device communication systems) the Medium Access Control (MAC) layer may be responsible for resource reservation. The MAC layer (or other layers of the device) may reserve resources for the initial transmission of a transport block (TB) and / or any retransmission or other transmission. The MAC layer (or other layers of the device) may also indicate to the lower layer whether to request feedback (e.g., according to hybrid automatic repeat request (HARQ)) for a transmission (e.g., initial transmission and / or retransmission). In some embodiments, the initial transmission and retransmission may share the same HARQ scheme, e.g., whether HARQ feedback (ACK or NACK) is enabled or whether blind retransmission is used (e.g., no time to receive and / or process HARQ feedback between retransmissions). The methods disclosed herein may allow a UE to have the flexibility to mix two methods (e.g., HARQ feedback and blind retransmission). The UE can flexibly adapt the HARQ scheme to meet the quality - of - service or other requirements of sidelink communication.

[0007] The techniques described herein may be implemented in and / or used with several different types of devices, including but not limited to any of a cellular phone, a tablet computer, an accessory and / or a wearable computing device, a portable media player, a vehicle, an access point and other wireless local area network equipment, a cellular base station and other cellular network infrastructure equipment, a server, and various other computing devices.

[0008] This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it should be understood that the above features are merely examples and should not be construed in any way as narrowing the scope or essence of the subject matter described herein. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, the Drawings, and the Claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A better understanding of the disclosed embodiments may be obtained when the following Detailed Description is considered in conjunction with the following Drawings, in which:

[0010] Figure 1 illustrates an exemplary wireless communication system in accordance with some embodiments;

[0011] Figure 2 illustrates an exemplary wireless communication system in which two user equipment devices (UEs) may perform communication in accordance with some embodiments;

[0012] Figure 3 illustrates an exemplary block diagram of a UE in accordance with some embodiments;

[0013] Figure 4 illustrates an exemplary block diagram of a base station (BS) in accordance with some embodiments;

[0014] Figure 5 illustrates an exemplary block diagram of a cellular communication circuit in accordance with some embodiments;

[0015] Figure 6 and Figure 7 illustrates an example of a 5G NR base station (gNB) in accordance with some embodiments; and

[0016] Figure 8 and Figure 9 illustrates aspects of flexible acknowledgment in accordance with some embodiments.

[0017] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are described in detail herein. However, it should be understood that the drawings and the detailed description thereof are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternative forms falling within the spirit and scope of the invention as defined by the appended claims. Detailed Description

[0018] Terms

[0019] The following is a glossary of terms used in this patent application:

[0020] Memory medium - Any of various types of non-transitory memory devices or storage devices. The term "memory medium" is intended to include installation media such as CD-ROMs, floppy disks, or tape devices; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media such as hard disk drives or optical storage devices; registers or other similar types of memory elements, etc. The memory medium may also include other types of non-transitory memory or combinations thereof. In addition, the memory medium may be located in a first computer system that executes a program, or may be located in a different second computer system that is connected to the first computer system via a network such as the Internet. In the latter case, the second computer system may provide program instructions to the first computer for execution. The term "memory medium" may include two or more memory media located at different locations in different computer systems that are connected, for example, via a network. The memory medium may store program instructions (e.g., embodied as a computer program) executable by one or more processors.

[0021] Carrier medium - The memory medium as described above, as well as physical transmission media such as buses, networks, and / or other physical transmission media that convey signals such as electrical, electromagnetic, or digital signals.

[0022] Programmable hardware element - Includes various hardware devices that include a plurality of programmable function blocks connected via programmable interconnects. Examples include FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field Programmable Object Arrays), and CPLDs (Complex PLDs). The programmable function blocks can vary from fine-grained (combinational logic components or lookup tables) to coarse-grained (arithmetic logic units or processor cores). Programmable hardware elements may also be referred to as "configurable logic components".

[0023] Computer system - Any of various types of computing or processing systems, including personal computer systems (PCs), mainframe computer systems, workstations, network devices, Internet devices, personal digital assistants (PDAs), television systems, grid computing systems, or other devices or combinations of devices. Generally speaking, the term "computer system" can be broadly defined to cover any device (or combination of devices) having at least one processor that executes instructions from a memory medium.

[0024] User Equipment (UE) (or "UE device") - Any of various types of computer system devices that are mobile or portable and perform wireless communication. Examples of UE devices include mobile phones or smartphones (e.g., iPhone TM , Android TM -based phones), portable gaming devices (e.g., Nintendo DS TM , PlayStation Portable TM , Gameboy Advance TM , iPhone TM ), laptop computers, wearable devices (e.g., smartwatches, smart glasses), PDAs, portable Internet devices, music players, data storage devices, or other handheld devices, vehicles, automobiles, unmanned aerial vehicles (e.g., drones), and unmanned flight controllers, etc. Generally speaking, the term "UE" or "UE device" can be broadly defined to cover any electronic device, computing device, and / or telecommunications device (or combination of these devices) that is easily transportable by a user and capable of performing wireless communication.

[0025] Wireless device - Any of various types of computer system devices that perform wireless communication. A wireless device can be portable (or mobile), or can be stationary or fixed in a location. A UE is an example of a wireless device.

[0026] Communication device - Any of various types of computer systems or devices that perform communication, where the communication can be wired or wireless. A communication device can be portable (or mobile), or can be stationary or fixed in a location. A wireless device is an example of a communication device. A UE is another example of a communication device. A communication device can be referred to as a station or STA.

[0027] Base station or Access Point (AP) - The term "base station" has the full scope of its ordinary meaning and includes at least a wireless communication station that is installed in a fixed location and used for communication as part of a wireless telephone system or radio system. The term "access point" is used similarly.

[0028] Link budget limited – includes the full breadth of its ordinary meaning and at least includes the characteristics of a wireless device (e.g., UE) that exhibits limited communication capabilities or limited power relative to a device that is not link budget limited or relative to a device for which a radio access technology (RAT) standard has been developed. A link budget limited wireless device may suffer from relatively limited receive and / or transmit capabilities, which may be due to one or more factors such as device design, device size, battery size, antenna size or design, transmit power, receive power, current transmission medium conditions, and / or other factors. Such devices may be referred to herein as “link budget limited” (or “link budget constrained”) devices. A device may be inherently link budget limited due to its size, battery power, and / or transmit / receive power. For example, a smartwatch communicating with a base station via LTE or LTE-A may be inherently link budget limited due to its reduced transmit / receive power and / or reduced antenna. Wearable devices such as smartwatches are generally link budget limited devices. Alternatively, a device may not be inherently link budget limited, e.g., may have sufficient size, battery power, and / or transmit / receive power for normal communication via LTE or LTE-A, but may be temporarily link budget limited due to current communication conditions, e.g., a smartphone at the cell edge, etc. It should be noted that the term “link budget limited” includes or encompasses power limitations, and thus a link limited device may be considered a link budget limited device.

[0029] Processing element – refers to various elements or combinations of elements. Processing elements include, for example, circuits such as ASICs (application specific integrated circuits), portions or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices (such as field programmable gate arrays (FPGAs)), and / or larger portions of systems that include multiple processors.

[0030] Wi-Fi – The term “Wi-Fi” has the full scope of its ordinary meaning and at least includes a wireless communication network or RAT that is served by wireless LAN (WLAN) access points and provides connectivity to the Internet through these access points. Most modern Wi-Fi networks (or WLAN networks) are based on the IEEE 802.11 standard and are marketed under the name “Wi-Fi”. Wi-Fi (WLAN) networks are different from cellular networks. Wi-Fi or WLAN may refer to technologies based on the IEEE 802.11 wireless standard (such as 802.11a, 802.11.b, 802.11g, 802.11n, 802.11-2012, 802.11ac, 802.11ax, 802.11he, 802.11ad, 802.11ax, 802.11ay, 802.11az, and / or other IEEE 802.11 standards).

[0031] Automatically - means that an action or operation is performed by a computer system (e.g., software executed by a computer system) or a device (e.g., circuitry, programmable hardware element, ASIC, etc.) without the need for direct specification or execution by a user input. Thus, the term "automatically" is contrary to an operation being performed or specified manually by a user, where the user provides input to directly perform the operation. An automatic process may be initiated by an input provided by the user, but the subsequent actions that are "automatically" performed are not specified by the user, i.e., are not "manually" performed, where the user specifies each action to be performed. For example, a user manually fills out a spreadsheet by selecting each field and providing input to specify information (e.g., by typing information, selecting checkboxes, radio selections, etc.), even though the computer system must update the spreadsheet in response to the user's actions. The spreadsheet may be filled out automatically by the computer system, where the computer system (e.g., software executed on a computer system) analyzes the fields of the spreadsheet and fills out the spreadsheet without any user input specifying the answers to the fields. As indicated above, the user may invoke the automatic filling out of the spreadsheet but does not participate in the actual filling out of the spreadsheet (e.g., the user does not manually specify the answers to the fields but they are completed automatically). This specification provides various examples of operations that are automatically performed in response to actions taken by a user.

[0032] Configured to - various components may be described as "configured to" perform one or more tasks. In such an environment, "configured to" is a broad statement generally meaning "having" the "structure" to perform one or more tasks during operation. Thus, even when the component is not currently performing a task, the component can be configured to perform the task (e.g., a set of electrical conductors can be configured to electrically connect a module to another module even when the two modules are not connected). In some contexts, "configured to" can be a broad statement generally meaning "having" the "circuitry" to perform one or more tasks during operation. Thus, even when the component is not currently powered on, the component can be configured to perform a task. Generally, the circuitry forming the structure corresponding to "configured to" may include hardware circuitry.

[0033] For ease of description, various components may be described as performing one or more tasks. Such a description should be interpreted as including the phrase "configured to". A component described as configured to perform one or more tasks is expressly intended not to invoke the interpretation of 35 U.S.C. § 112, paragraph 6 for that component.

[0034] Figure 1 and Figure 2 — Communication system

[0035] Figure 1 FIG. shows a simplified exemplary wireless communication system in accordance with some embodiments. Note thatFigure 1 The system is merely an example of possible systems, and the features of the present disclosure can be implemented in any one of various systems as needed.

[0036] As shown, an exemplary wireless communication system includes a base station 102 that communicates with one or more user equipments 106A, user equipment 106B, up to user equipment 106N via a transmission medium. Each user equipment may be referred to herein as a "user equipment" (UE). Thus, the user equipment 106 is referred to as a UE or a UE device.

[0037] The base station (BS) 102 may be a transceiver base station (BTS) or a cell site ("cellular base station"), and may include hardware enabling wireless communication with the UEs 106A to 106N.

[0038] The communication area (or coverage area) of the base station may be referred to as a "cell". The base station 102 and the UE 106 may be configured to communicate via a transmission medium using any one of various radio access technologies (RATs), which are also referred to as wireless communication technologies or telecommunication standards, such as GSM, UMTS (associated with, for example, the WCDMA or TD-SCDMA air interfaces), LTE, Long Term Evolution-Advanced (LTE-A), 5G New Radio (5G NR), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc. Note that if the base station 102 is implemented in an LTE environment, it may alternatively be referred to as an 'eNodeB' or 'eNB'. Note that if the base station 102 is implemented in a 5G NR environment, it may alternatively be referred to as a 'gNodeB' or 'gNB'.

[0039] As shown, the base station 102 may also be equipped to communicate with a network 100 (e.g., in various possibilities, the core network of a cellular service provider, a telecommunication network such as the Public Switched Telephone Network (PSTN) and / or the Internet). Thus, the base station 102 may facilitate communication between user equipments and / or between user equipments and the network 100. In particular, the cellular base station 102 may provide the UE 106 with various telecommunication capabilities such as voice, Short Message Service (SMS), and / or data services.

[0040] Base stations 102 and other similar base stations operating according to the same or different cellular communication standards may thus provide a network as a cell, and the network of the cell may provide continuous or nearly continuous overlapping services to the UEs 106A - 106N and similar devices over a geographical area via one or more cellular communication standards.

[0041] Thus, although the base station 102 may act as Figure 1The "serving cell" of UEs 106A - 106N as shown, but each UE 106 may also be capable of receiving signals (and potentially being within its communication range) from one or more other cells (possibly provided by other base stations 102B - 102N), and such one or more other cells may be referred to as "neighboring cells". Such cells may also be capable of facilitating communication between user devices and / or between user devices and network 100. Such cells may include "macro" cells, "micro" cells, "pico" cells, and / or any other various granularities of cells providing service area sizes. Other configurations are also possible.

[0042] In some embodiments, base station 102 may be a next - generation base station, e.g., a 5G New Radio (5G NR) base station, or a "gNB". In some embodiments, a gNB may be connected to a traditional Evolved Packet Core (EPC) network and / or connected to a NR Core (NRC) network. Additionally, a gNB cell may include one or more Transmission and Reception Points (TRP). Further, a UE capable of operating according to 5G NR may be connected to one or more TRPs within one or more gNBs.

[0043] Note that UE 106 is capable of communicating using multiple wireless communication standards. For example, in addition to at least one cellular communication protocol (e.g., GSM, UMTS (associated with, e.g., WCDMA or TD - SCDMA air interfaces), LTE, LTE - A, 5G NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV - DO, HRPD, eHRPD), etc.), UE 106 may be configured to communicate using wireless networking (e.g., Wi - Fi) and / or peer - to - peer wireless communication protocols (e.g., Bluetooth, Wi - Fi peer - to - peer, etc.). If needed, UE 106 may also or alternatively be configured to communicate using one or more Global Navigation Satellite Systems (GNSS, e.g., GPS or GLONASS), one or more mobile television broadcast standards (e.g., Advanced Television Systems Committee - Mobile / Handheld (ATSC - M / H)), and / or any other wireless communication protocol. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0044] Figure 2 Illustrated are UE devices 106A and 106B communicating with each other according to some embodiments. According to some embodiments, the communication may include sidelink communication and may be facilitated by one or more BSs 102. UEs 106 may, for example, potentially use time resources and / or frequency resources scheduled by the BS to communicate with each other. Each UE 106 may be a device with cellular communication capabilities, such as a mobile phone, a handheld device, a computer or tablet computer, a vehicle, or virtually any type of wireless device.

[0045] UE 106 may include a processor configured to execute program instructions stored in a memory. UE 106 may perform any of the method embodiments described herein by executing such stored instructions. Alternatively or in addition, one or more of the UEs 106 may include programmable hardware elements such as an FPGA (Field Programmable Gate Array) configured to perform any of the method embodiments described herein or any part of any of the method embodiments described herein.

[0046] UE 106 may include one or more antennas for communicating using one or more wireless communication protocols or technologies. In some embodiments, UE 106 may be configured to communicate using, for example, CDMA2000 (1xRTT, 1xEV-DO, HRPD, eHRPD) or LTE using a single shared radio component and / or GSM or LTE using a single shared radio component. The shared radio component may be coupled to a single antenna or may be coupled to multiple antennas (e.g., for a multiple-input, multiple-output or “MIMO” antenna system) for performing wireless communication. Generally, the radio component may include any combination of a baseband processor, analog radio frequency (RF) signal processing circuitry (e.g., including filters, mixers, trackers, oscillators, amplifiers, etc.) or digital processing circuitry (e.g., for digital modulation and other digital processing). Similarly, the radio component may implement one or more receive chains and transmit chains using the foregoing hardware. For example, UE 106 may share one or more portions of a receive chain and / or a transmit chain among multiple wireless communication technologies such as those discussed above.

[0047] In some embodiments, UE 106 may include any number of antennas and may be configured to transmit and / or receive directional wireless signals (e.g., beams) using the antennas. Similarly, BS 102 may also include any number of antennas and may be configured to transmit and / or receive directional wireless signals (e.g., beams) using the antennas.

[0048] In some embodiments, the UE 106 may include separate transmit and / or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol it is configured to communicate with. As another possibility, the UE 106 may include one or more radio components shared among multiple wireless communication protocols, and one or more radio components uniquely used by a single wireless communication protocol. For example, the UE 106 may include shared radio components for communicating using either LTE or 5G NR (or LTE or 1xRTT, or LTE or GSM), and separate radio components for communicating using each of Wi-Fi and Bluetooth. Other configurations are possible.

[0049] Figure 3 —Block diagram of the UE

[0050] Figure 3 FIG. shows an exemplary simplified block diagram of the communication device 106 according to some embodiments. Note that Figure 3 the block diagram of the communication device is only one example of a possible communication device. According to embodiments, in addition to other devices, the communication device 106 may be a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop computer, notebook or portable computing device), a tablet computer, and / or a combination of devices. As shown, the communication device 106 may include a set of components 300 configured to perform core functions. For example, the set of components may be implemented as a system-on-chip (SOC), which may include portions for various purposes. Alternatively, the set of components 300 may be implemented as separate components or groups of components for various purposes. This set of components 300 may be (e.g., communicatively; directly or indirectly) coupled to various other circuits of the communication device 106.

[0051] For example, the communication device 106 may include various types of memory (e.g., including NAND flash memory 310), input / output interfaces such as connector I / F 320 (e.g., for connecting to a computer system; docking station; charging station; input devices such as microphones, cameras, keyboards; output devices such as speakers; etc.), a display 360 that may be integrated with or external to the communication device 106, and cellular communication circuits 330 such as for 5G NR, LTE, GSM, etc., and short-range to medium-range wireless communication circuits 329 (e.g., Bluetooth TM and WLAN circuits). In some embodiments, the communication device 106 may include a wired communication circuit (not shown), such as, for example, a network interface card for Ethernet.

[0052] The cellular communication circuitry 330 may be (e.g., communicatively; directly or indirectly) coupled to one or more antennas, such as the antennas 335 and 336 shown. The short-range to mid-range wireless communication circuitry 329 may also be (e.g., communicatively; directly or indirectly) coupled to one or more antennas, such as the antennas 337 and 338 shown. Alternatively, the short-range to mid-range wireless communication circuitry 329, in addition to (e.g., communicatively; directly or indirectly) being coupled to the antennas 337 and 338 or in place of, may be (e.g., communicatively; directly or indirectly) coupled to the antennas 335 and 336. The short-range to mid-range wireless communication circuitry 329 and / or the cellular communication circuitry 330 may include multiple receive chains and / or multiple transmit chains for receiving and / or transmitting multiple spatial streams, such as in a multiple-input - multiple-output (MIMO) configuration.

[0053] In some embodiments, as further described below, the cellular communication circuitry system 330 may include dedicated receive chains for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR). Such receive chains may include and / or be communicatively coupled (e.g., directly or indirectly) to dedicated processors and / or radios. Additionally, in some embodiments, the cellular communication circuitry 330 may include a single transmit chain that may switch between radio components dedicated to a particular RAT. For example, a first radio component may be dedicated to a first RAT, such as LTE, and may communicate with a dedicated receive chain as well as a transmit chain shared with additional radio components, such as a second radio component that may be dedicated to a second RAT (e.g., 5G NR) and may communicate with the dedicated receive chain as well as the shared transmit chain.

[0054] The communication device 106 may also include one or more user interface elements and / or be configured to be used with one or more user interface elements. The user interface elements may include various elements such as a display 360 (which may be a touchscreen display), a keyboard (which may be a discrete keyboard or may be implemented as part of a touchscreen display), a mouse, a microphone and / or a speaker, one or more cameras, one or more buttons, and / or any of various other elements capable of providing information to the user and / or receiving or interpreting user input.

[0055] The communication device 106 may further include one or more smart cards 345 having SIM (Subscriber Identity Module) functionality, such as one or more UICC cards (one or more Universal Integrated Circuit Cards) 345.

[0056] As shown in the figure, the SOC 300 may include a processor 302 and a display circuit 304. The processor may execute program instructions for the communication device 106, and the display circuit may perform graphics processing and provide a display signal to the display 360. The processor 302 may also be coupled to a memory management unit (MMU) 340 (the MMU 340 may be configured to receive addresses from the processor 302 and convert those addresses into locations in a memory (e.g., memory 306, read-only memory (ROM) 350, NAND flash memory 310)) and / or be coupled to other circuits or devices (such as the display circuit 304, short-range wireless communication circuit 229, cellular communication circuit 330, connector I / F 320, and / or the display 360). The MMU 340 may be configured to perform memory protection and page table translation or setup. In some embodiments, the MMU 340 may be included as part of the processor 302.

[0057] As described above, the communication device 106 may be configured to communicate using wireless and / or wired communication circuits. The communication device 106 may be configured to transmit a request attached to a first network node operating according to a first RAT and transmit an indication that the wireless device is capable of maintaining substantially concurrent connections with the first network node and a second network node operating according to a second RAT. The wireless device may also be configured to transmit a request attached to the second network node. The request may include an indication that the wireless device is capable of maintaining substantially concurrent connections with the first and second network nodes. Additionally, the wireless device may be configured to receive an indication that a dual connection (DC) with the first and second network nodes has been established.

[0058] As described herein, the communication device 106 may include hardware and software components for implementing features for performing transmissions using multiplexing according to multiple radio access technologies in the same frequency carrier (e.g., and / or multi-frequency carriers) and various other technologies described herein. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), the processor 302 of the communication device 106 may be configured to implement some or all of the features described in the present invention. Alternatively (or in addition), the processor 302 may be configured as a programmable hardware element, such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). Alternatively (or in addition), in combination with one or more of the other components 300, 304, 306, 310, 320, 329, 330, 340, 345, 350, 360, the processor 302 of the communication device 106 may be configured to implement some or all of the features described in the present invention.

[0059] In addition, as described in the present invention, the processor 302 may include one or more processing elements. Thus, the processor 302 may include one or more integrated circuits (ICs) configured to perform the functions of the processor 302. Further, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform one or more of the functions of the processor 302.

[0060] In addition, as described in the present invention, the cellular communication circuit 330 and the short-range wireless communication circuit 329 may each include one or more processing elements and / or processors. In other words, one or more processing elements / processors may be included in the cellular communication circuit 330, and similarly, one or more processing elements / processors may be included in the short-range wireless communication circuit 329. Thus, the cellular communication circuit 330 may include one or more integrated circuits (ICs) configured to perform the functions of the cellular communication circuit 330. Further, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the cellular communication circuit 330. Similarly, the short-range wireless communication circuit 329 may include one or more ICs configured to perform the functions of the short-range wireless communication circuit 329. Further, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the short-range wireless communication circuit 329.

[0061] Figure 4 — Block diagram of a base station

[0062] Figure 4 An exemplary block diagram of a base station 102 according to some embodiments is shown. Note that Figure 4 the base station shown is only one example of possible base stations. As shown, the base station 102 may include a processor 404 that may execute program instructions for the base station 102. The processor 404 may also be coupled to a memory management unit (MMU) 440 or other circuits or devices, which may be configured to receive addresses from the processor 404 and translate those addresses to locations in a memory (e.g., memory 460 and read-only memory (ROM) 450).

[0063] The base station 102 may include at least one network port 470. The network port 470 may be configured to couple to a telephone network and provide access to multiple devices such as UE devices 106 to the telephone network as described above in Figure 1 and Figure 2 .

[0064] The network port 470 (or an additional network port) may also be configured or alternatively configured to be coupled to a cellular network, such as the core network of a cellular service provider. The core network may provide mobility-related services and / or other services to a plurality of devices such as UE device 106. In some cases, the network port 470 may be coupled to a telephone network via the core network, and / or the core network may provide a telephone network (e.g., among other UE devices served by the cellular service provider).

[0065] In some embodiments, the base station 102 may be a next-generation base station, e.g., a 5G New Radio (5G NR) base station, or a "gNB". In such embodiments, the base station 102 may be connected to a legacy Evolved Packet Core (EPC) network and / or connected to an NR Core (NRC) network. Additionally, the base station 102 may be regarded as a 5G NR cell and may include one or more Transmission and Reception Points (TRPs). Further, a UE capable of operating according to 5G NR may be connected to one or more TRPs within one or more gNBs.

[0066] The base station 102 may include at least one antenna 434 and possibly multiple antennas. The radio component 430 and the at least one antenna 434 may be configured to function as a wireless transceiver and may be further configured to communicate with the UE device 106. The antenna 434 may communicate with the radio component 430 via a communication link 432. The communication link 432 may be a receive link, a transmit link, or both. The radio component 430 may be configured to communicate via various wireless communication standards, including but not limited to 5G NR, LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

[0067] The base station 102 may be configured to perform wireless communication using multiple wireless communication standards. In some cases, the base station 102 may include multiple radios that enable the base station 102 to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station 102 may include an LTE radio component for performing communication according to LTE and a 5G NR radio component for performing communication according to 5G NR. In this case, the base station 102 may be capable of operating as both an LTE base station and a 5G NR base station. As another possibility, the base station 102 may include a multi-mode radio component capable of performing communication according to any of multiple wireless communication technologies (e.g., 5G NR and Wi-Fi, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

[0068] As further described hereinbelow, BS 102 may include hardware and software components for implementing or supporting specific implementations of the features described herein. The processor 404 of the base station 102 may be configured to implement or support specific implementations of part or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, the processor 404 may be configured as a programmable hardware element such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. Alternatively (or in addition), in combination with one or more of the other components 430, component 432, component 434, component 440, component 450, component 460, component 470, the processor 404 of the base station 102 may be configured to implement or support implementations of part or all of the features described herein.

[0069] In addition, as described in the present invention, one or more processors 404 may include one or more processing elements. Thus, the processor 404 may include one or more integrated circuits (ICs) configured to perform the functions of the processor 404. In addition, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of one or more processors 404.

[0070] In addition, as described in the present invention, the radio component 430 may include one or more processing elements. Thus, the radio component 430 may include one or more integrated circuits (ICs) configured to perform the functions of the radio component 430. In addition, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the radio component 430.

[0071] Figure 5 —Block diagram of a cellular communication circuit

[0072] Figure 5 An exemplary simplified block diagram of a cellular communication circuit according to some embodiments is shown. Note that Figure 5 the block diagram of the cellular communication circuit is merely an example of a possible cellular communication circuit; other circuits, such as a circuit including or coupled to sufficient antennas for different RATs to perform uplink activities using separate antennas, are also possible. According to an embodiment, the cellular communication circuit 330 may be included in a communication device such as the communication device 106 described above. As described above, in addition to other devices, the communication device 106 may be a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop computer, notebook or portable computing device), a tablet computer, and / or a combination of devices.

[0073] The cellular communication circuitry 330 may be (e.g., communicatively; directly or indirectly) coupled to one or more antennas, such as the antennas 335a - 335b and 336 shown in Figure 3 . In some embodiments, the cellular communication circuitry 330 may include dedicated receive chains for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR). Such receive chains may include and / or be communicatively coupled (e.g., directly or indirectly) to dedicated processors and / or radios. For example, as Figure 5 shown, the cellular communication circuitry 330 may include a modem 510 and a modem 520. The modem 510 may be configured for communication according to a first RAT (e.g., such as LTE or LTE - A), and the modem 520 may be configured for communication according to a second RAT (e.g., such as 5G NR).

[0074] As shown, the modem 510 may include one or more processors 512 and a memory 516 communicative with the processors 512. The modem 510 may communicate with a radio frequency (RF) front - end 530. The RF front - end 530 may include circuitry for transmitting and receiving radio signals. For example, the RF front - end 530 may include a receive circuit (RX) 532 and a transmit circuit (TX) 534. In some embodiments, the receive circuit 532 may communicate with a downlink (DL) front - end 550, which may include circuitry for receiving radio signals via the antenna 335a.

[0075] Similarly, the modem 520 may include one or more processors 522 and a memory 526 communicative with the processors 522. The modem 520 may communicate with an RF front - end 540. The RF front - end 540 may include circuitry for transmitting and receiving radio signals. For example, the RF front - end 540 may include a receive circuit 542 and a transmit circuit 544. In some embodiments, the receive circuit 542 may communicate with a DL front - end 560, which may include circuitry for receiving radio signals via the antenna 335b.

[0076] In some embodiments, switch 570 may couple transmit circuit 534 to uplink (UL) front end 572. Additionally, switch 570 may couple transmit circuit 544 to UL front end 572. UL front end 572 may include circuitry for transmitting radio signals via antenna 336. Thus, when cellular communication circuit 330 receives an instruction to transmit according to a first RAT (e.g., supported via modem 510), switch 570 may be switched to a first state that permits modem 510 to transmit signals according to the first RAT (e.g., via a transmit chain including transmit circuit 534 and UL front end 572). Similarly, when cellular communication circuit 330 receives an instruction to transmit according to a second RAT (e.g., supported via modem 520), switch 570 may be switched to a second state that permits modem 520 to transmit signals according to the second RAT (e.g., via a transmit chain including transmit circuit 544 and UL front end 572).

[0077] In some embodiments, cellular communication circuit 330 may be configured to transmit, via a first modem when the switch is in the first state, a request attached to a first network node operating according to a first RAT, and when the switch is in the first state, an indication that the wireless device is capable of maintaining substantially concurrent connections with the first network node and a second network node operating according to a second RAT. The wireless device may also be configured to transmit, via a second radio component when the switch is in the second state, a request attached to the second network node. The request may include an indication that the wireless device is capable of maintaining substantially concurrent connections with the first and second network nodes. Additionally, the wireless device may be configured to receive, via the first radio component, an indication that a dual connection with the first and second network nodes has been established.

[0078] As described herein, modem 510 may include hardware and software components for implementing features for performing transmissions using multiplexing according to multiple radio access technologies in the same frequency carrier as well as various other techniques described herein. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), processor 512 may be configured to implement some or all of the features described herein. Alternatively (or in addition), processor 512 may be configured as a programmable hardware element such as an FPGA (field programmable gate array), or as an ASIC (application specific integrated circuit). Alternatively (or in addition), in combination with one or more of the other components 530, 532, 534, 550, 570, 572, 335, and 336, processor 512 may be configured to implement some or all of the feature portions described herein.

[0079] In some embodiments, processors 512, 522, etc. may be configured to implement or support the implementation of some or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, processors 512, 522, etc. may be configured as programmable hardware elements such as field-programmable gate arrays or as application-specific integrated circuits or combinations thereof. Additionally, as described in the present invention, processors 512, 522, etc. may include one or more processing elements. Thus, processors 512, 522, etc. may include one or more integrated circuits (ICs) configured to perform the functions of processors 512, 522, etc. Additionally, each integrated circuit may include circuits (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of processors 512, 522, etc.

[0080] As described herein, modem 520 may include hardware and software components for implementing features for performing transmissions using multiplexing according to multiple radio access technologies in the same frequency carrier and various other technologies described herein. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), processor 522 may be configured to implement some or all of the features described herein. Alternatively (or in addition), processor 522 may be configured as a programmable hardware element such as an FPGA (field-programmable gate array), or as an ASIC (application-specific integrated circuit). Alternatively (or additionally), in combination with one or more of other components 540, 542, 544, 550, 570, 572, 335, and 336, processor 522 may be configured to implement some or all of the features described herein.

[0081] Figures 6 to 7 —5G NR Architecture

[0082] In some implementations, fifth-generation (5G) wireless communications will initially be deployed in parallel with other wireless communication standards (e.g., LTE). For example, Figure 6 shows a possible stand-alone (SA) implementation of a next-generation core (NGC) network 606 and a 5G NR base station (e.g., gNB 604), a dual connection between LTE and the 5G new radio (5G NR or NR), such as according to Figure 7 shown in the exemplary non-stand-alone (NSA) architecture, which has been designated as part of the initial deployment of NR. Thus, as Figure 7As shown, the evolved packet core (EPC) network 600 can continue to communicate with the current LTE base station (e.g., eNB 602). In addition, the eNB 602 can communicate with a 5G NR base station (e.g., gNB 604) and can transfer data between the core network 600 and the gNB 604. In some cases, the gNB 604 may also at least have a user plane reference point with the EPC network 600. Thus, the EPC network 600 can be used (or reused), and the gNB 604 can act as additional capacity for user equipment, such as for providing increased downlink throughput to the UE. In other words, LTE can be used for control plane signaling, and NR can be used for user plane signaling. Thus, LTE can be used to establish a connection to the network, and NR can be used for data services. It should be understood that many other non-standalone architecture variants are possible.

[0083] Figures 8 to 9 - Flexible acknowledgment

[0084] Hybrid automatic repeat request (HARQ) feedback can be used to improve the reliability of various types of wireless communications such as sidelink (SL) communications. HARQ feedback can include an affirmative acknowledgment (ACK) and / or a negative acknowledgment (NACK), for example, to indicate that the receiver has or has not successfully received the communication. For example, in multicast and / or unicast operations, various schemes for HARQ in SL (e.g., or other types of) communications can be used. Multicast can be a special case of a multicast operation. Multicast can include multi-hop operations (e.g., multicast can refer to communication from an end-to-end perspective, which can span multiple network segments). Multicast can refer to single-hop operations (e.g., direct device-to-device communication, e.g., without intermediate devices or network segments). Distance-limited or otherwise location-based groups can be examples of multicast operations. In some embodiments, in unicast operations, individual UEs can provide ACK or NACK feedback for the communication. In some embodiments, a group of UEs (e.g., for multicast) can be formed based on characteristics such as UE type (e.g., vehicle, smartphone, etc.), location / area, applications executed on the UE, etc. For V2X communications, the group participating in the multicast can be a group of vehicles moving together (e.g., a vehicle convoy) or a group of road participants related to a common purpose. For example, cars, pedestrians, bicycles, and traffic lights can coordinate with each other at an intersection. In multicast, the HARQ operation can be performed in any of various ways. HARQ feedback can also be used for SL unicast communications, where only two UEs are involved.

[0085] A first example of multicast feedback can be a location-based (e.g., distance-based) NACK-only scheme. Any group member within a specific geographical area (e.g., within a certain radius of the transmitting (TX) UE, within a defined area, etc.) can provide NACK feedback if it fails to receive or decode the communication. Among various possibilities, such a scheme can be applicable to vehicles. For example, among various possibilities, the group can be based on a geographical area. For example, a vehicle group can include all vehicle UEs within a specified geographical area, which can be defined by the size or communication range of the vehicle UEs. For example, the transmitted communication can include an indication of the area, such as the geographical coordinates of the TX UE, the radius, the area identifier, the boundaries of the area, etc. In this example, the geographical area can move over time, but static areas are also envisioned.

[0086] A second example of multicast feedback can be a location-unconstrained group-based NACK-only scheme. Any group member that fails to receive or decode the communication (e.g., at any location) can provide NACK feedback. Examples of such groups can include vehicle convoys (e.g., a group of trucks and / or cars traveling in the same direction on a road). A multicast message sent by a leading vehicle (or any vehicle near the start of the convoy) can be intended to be received by all following vehicles belonging to the convoy. There may be no distance-based constraints on the size of the convoy or the distance to which the message transmission is to reach (e.g., the distance from the transmitting vehicle in the convoy to the receiving vehicle).

[0087] A third example of multicast feedback can be an individual ACK / NACK scheme. Feedback (e.g., ACK or NACK) can be transmitted from and to individual group members. Note that this scheme can also be used for the SL unicast case. In unicast, a single receiving UE can send an ACK or NACK to the transmitting UE.

[0088] For a TX UE that supports SL unicast and multicast, in the case of enabling HARQ feedback, the UE may retransmit the transmission (e.g., media access control (MAC) protocol data unit (PDU), frame, packet, transport block (TB), SL resource block (SLRB), symbol, aggregated MAC PDU, and / or other communication) only when the feedback indicates a transmission failure (e.g., in the case of receiving a NACK, or possibly in the case of not receiving an (e.g., expected) ACK from at least one group member). If HARQ feedback is not enabled, the UE may perform a blind retransmission, e.g., the UE may retransmit the transmission regardless (e.g., regardless of whether the transmission is received). For NR SL communication, the SL TB may consist of a source address, a destination address, and a MAC PDU. The MAC PDU may multiplex data from one or more SL logical channels and may also include optional SL MAC CE (control element). From a physical layer perspective, the retransmission of the TB may be used to retransmit layer 2 MAC data, e.g., the MAC PDU. Thus, in terms of HARQ operation, the TB and the PDU may be similar.

[0089] In some embodiments, SL communication may operate according to either of two modes, but more modes may be implemented in other embodiments. In Mode 1, a base station (e.g., BS 102) may schedule (e.g., individually) SL transmissions. For example, the UE may transmit a scheduling request, and the BS may provide one or more SL authorizations for the requested transmission to allocate and / or schedule (e.g., time and / or frequency) resources.

[0090] In Mode 2, the BS may provide a resource pool for SL transmissions but may not schedule a particular SL transmission. For example, the BS may provide a resource pool, and the UE may use a contention-based method (e.g., listen before talk, reservation, etc.) to obtain resources for transmission. The resource pool may be subdivided into various types of transmissions. Figure 8 Aspects of an SL resource pool are shown in accordance with some embodiments. For example, as Figure 8 shown, a first portion of the resource pool may be allocated for the SL control and / or data channels (e.g., physical SL control channel (PSCCH) and / or physical SL shared channel (PSSCH)), and a second portion of the resource pool may be allocated for SL feedback (e.g., HARQ ACK / NACK) (e.g., physical SL feedback channel (PSFCH)). For example, among various possibilities, the PSFCH may be allocated resources at various times, e.g., once every 1, 2, 3, or 4 (or more) time slots in the SL resource pool. According to various embodiments, the PSFCH may occupy all or any portion of the bandwidth of the SL resource pool, e.g., at a first time, the PSFCH may be allocated to all subcarriers, and at a second time, the PSFCH may be allocated to a subset of subcarriers.

[0091] In some embodiments, the SL control information (SCI) may have two parts. The first part (e.g., level 1) can and may include information broadcast to each UE (e.g., in a geographical area). In other words, level 1 may be destination-agnostic. UEs receiving level 1 SCI may consider the information. The second part of the SCI (e.g., level 2) can be a destination-specific part, e.g., it may be addressed to one or more UEs. Thus, UEs matching the destination address may process the second part. In some embodiments, two level 2 SCI formats may be available, e.g., SCI format A and B. SCI format A may be used for location-based multicast. Location-based parameters such as “zone ID” and / or “range” may be included. RX UEs outside the zone or range may determine that they are not the intended recipients and may determine not to provide feedback (e.g., ACK / NACK). The transmission may also include one or more indications of which UEs are being targeted, e.g., group ID, UE ID, etc.

[0092] SCI format B may be shared among multicast, unicast, and broadcast communications. In some embodiments, SCI format B may not include location-based parameters, but may include an indication of which UEs are being targeted, e.g., group ID, UE ID, etc.

[0093] In some embodiments, the SL grant may separate data from “feedback (FB)-disabled” logical channels (LCHs) and “FB-enabled” LCHs (e.g., may not mix them). This may be done via the LCP (Logical Channel Prioritization) procedure to create a transmission (e.g., TB, MAC PDU, etc.) for SL transmission. However, even though the LCP procedure may (e.g., to a large extent or possibly completely) separate different LCHs into different transmissions, the transmission (retransmission) of such transmissions may be flexible (e.g., according to the techniques disclosed herein). “FB-disabled” LCHs multiplexed in a particular TB may (e.g., by default) use blind retransmission. In other words, PSFCH resources may be provided for “FB-disabled” LCHs. In some embodiments, according to some embodiments, “FB-enabled” LCHs (e.g., may be multiplexed in a particular TB, MAC PDU, or other transmission) may switch between using and not using PSFCH. In other words, as disclosed herein, even when PSFCH resources are configured for transmission (e.g., the TB is based on the LCP mapping of transmissions in an SL resource pool that includes PSFCH), the UE may dynamically determine whether to trigger the receiving UE to use PSFCH. In other embodiments, “FB-enabled” LCHs may not switch, e.g., they may (e.g., consistently) use PSFCH.

[0094] Various UE retransmission behaviors can be possible. According to some embodiments, the UE can be configured to retransmit a transmission (e.g., MAC PDU) up to 31 times. For example, the parameter sl-MaxTxTransNumPSSCH-r16 can be configured (e.g., in Radio Resource Control (RRC)) to be between 1 and 32 (e.g., including the original transmission and retries, but other ranges are also envisioned). The actual transmission (retransmission) can be bounded by the Packet Delay Budget (PDB) or other time available for transmission. The available time can be related to the amount of time that the transmission is useful to the receiver. For example, data related to the movement of the vehicle can be updated periodically, and thus the transmission may only be useful until the update time. The available time can be the period (e.g., several ms, etc.) from when the transmission is first generated (e.g., and received by a lower layer of the device for transmission) until additional transmissions (retransmissions) of the transmission will no longer be useful.

[0095] One issue in wireless communication system design can include whether to support a mixture of blind retransmissions of transmissions and feedback-based HARQ retransmissions in SL HARQ operations. Among the various possibilities, the various embodiments discussed herein can address the following issues. Embodiments can include techniques for UE transmissions (retransmissions) of logical channels that contain "feedback-enabled" to indicate whether their transmissions request PSFCH feedback. Additionally, for example, by assuming that no PSFCH feedback is needed or expected, embodiments can include techniques for the UE to reserve retransmission resources in a "blind" manner for the next attempt.

[0096] In some cases, the feedback for SL transmissions (e.g., associated with a feedback-enabled LCH) may not be relevant (e.g., helpful). For example, if the SL transmission is the last available transmission before reaching the maximum retry limit (e.g., configured by RRC), then no additional retransmissions of the SL transmission may be performed. Thus, the feedback may not be relevant because the feedback will not change the retransmission decision. Similarly, if the SL transmission is the last transmission before reaching the Packet Delay Budget (PDB) associated with the transmission, then no additional retransmissions can be performed and the feedback may not be relevant. For example, the transmission can be time-sensitive such that retransmissions will not serve any useful purpose (e.g., because the retransmissions will be outside the time window associated with the transmission). Thus, allowing the UE to indicate that some (e.g., feedback-enabled) SL transmissions do not require (e.g., PSFCH transmission) feedback can provide some benefits. Such benefits can include saving PSFCH resources (e.g., which can be used for other purposes) and / or reducing PSFCH collisions.

[0097] When determining whether to enable HARQ feedback for various transmissions, Quality of Service (QoS) may be considered. According to some embodiments, transmissions may be mapped to LCHs based on QoS requirements and / or other factors. For example, the LCH configuration for each QoS flow mapped to a sidelink resource block (SLRB) may be based on the reliability requirement of QoS (e.g., block, bit, or packet error rate, etc.) to determine whether to use HARQ feedback.

[0098] In some embodiments, the LCHs with HARQ feedback enabled may be associated with higher reliability expected in QoS. The LCHs with HARQ feedback disabled may be associated with a lower reliability level.

[0099] Different feedback methods may be associated with different scheduling techniques. For example, depending on whether HARQ feedback is enabled, different timeline considerations may apply to resource selection. For example, the UE may consider the transmission time requirements (e.g., packet delay budget (PDB)) associated with the latency criteria or other QoS criteria, e.g., regardless of whether HARQ feedback is enabled. If HARQ feedback is enabled, the UE may further consider the time allowed for HARQ feedback between transmissions.

[0100] In some embodiments, if HARQ feedback is disabled, the UE may select TX resources to meet the transmission timing requirements of the transmission.

[0101] In some embodiments, if HARQ feedback is enabled, then in addition to the transmission time requirements, for example, the UE may ensure a minimum time gap between any two selected resources for transmission. This time gap may allow HARQ feedback for the transmission on the first of these selected resources. This time gap may be represented as Z, where: Z = a + b. In this equation, 'a' may be the time gap between the end of the last symbol of the transmission on the first resource (e.g., PSSCH) and the start of the first symbol of the corresponding feedback (e.g., PSFCH) reception. 'a' may be determined by the resource pool configuration and higher layer parameters (e.g., MinTimeGapPSFCH, periodPSFCHresource, and / or other parameters). In addition, 'b' may be the time for PSFCH reception and processing plus the time for (e.g., SL) retransmission preparation, including the time for multiplexing physical channels and any handover time (e.g., TX - RX and / or RX - TX). Therefore, 'b' may be UE - specific and may be determined by UE implementation.

[0102] As described above, according to some embodiments, the PSFCH can be as sparse as once every 1, 2, or 4 time slots in the SL resource pool (e.g., periodPSFCHresource can be 1, 2, or 4 time slots, etc.). The minimum time between transmission and feedback can be set by a higher layer parameter (e.g., MinTimeGapPSFCH). In some embodiments, among various possibilities, this minimum time can be 2 or 3 time slots. The UE can also use additional time to process the feedback (e.g., PSFCH) and perform Rx / Tx switching.

[0103] Therefore, the minimum time gap between transmission and retransmission can depend on whether feedback is enabled. For example, if feedback is enabled, the minimum time gap can be multiple time slots. If feedback is not enabled, the minimum time gap may not be required (e.g., the minimum time gap can be zero).

[0104] This minimum time gap can be related to how many retransmissions can be scheduled within the transmission time requirement. For example, a fixed PDB value or other transmission time requirements may only accommodate two (e.g., feedback-based) retransmissions in the case where feedback is enabled, but among various possibilities, can accommodate four (e.g., blind) retransmissions in the case where feedback is disabled. For example, in the case where feedback is disabled, retransmissions can be transmitted without a delay between them (e.g., they can be transmitted continuously without time to receive and process feedback). Therefore, by allowing reservation for blind retransmissions, the UE can transmit (retransmit) more times and achieve higher reliability than an alternative with HARQ feedback enabled. According to some embodiments, blind retransmissions can be transmitted without time to receive and / or process feedback. Due to the time gap requirements for the above HARQ feedback retransmissions, if the required reliability is very high and / or the latency (e.g., transmission time requirement or remaining packet delay budget) is not sufficient to allow feedback-based retransmissions, blind retransmissions can be flexibly used. Therefore, some blind transmissions can be transmitted based on previously received negative feedback. Similarly, if PSFCH resources are available, feedback can be requested for some transmissions that can (e.g., initially be assumed to) use blind transmissions (e.g., and received and processed). In some embodiments, the UE can adapt the resource reservation and adaptively select whether / how to request feedback, for example, based on the timeline requirement and / or other considerations, as Figure 9 Further shown.

[0105] It should be understood that the above examples of transmission timing have been presented in terms of time slots, but any unit (e.g., symbols, subframes, etc.) can be used as needed.

[0106] Figure 9 An exemplary technique for performing flexible acknowledgment according to some embodiments is shown. Figure 9Aspects of the method may be implemented by a wireless device such as UE 106, which communicates with network 100 and one or more base stations 102 as shown in and with reference to the accompanying drawings, or more generally, in combination with any of the following as needed: a computer system or device shown in the accompanying drawings in addition to other circuitry; a system, device, element, or component shown in the accompanying drawings in addition to other devices. For example, one or more processors (or processing elements) (e.g., in various possibilities, processor 302, 404, 512, 522, a baseband processor, a processor associated with communication circuitry 329 or 330, a processor associated with various core network elements, etc.) may cause the UE, network element, and / or BS to perform some or all of the method elements shown. Note that although at least some elements of the method are described in a manner involving the use of communication technologies and / or features associated with 3GPP specification documents, such description is not intended to limit the present disclosure, and aspects of the method may be used in any suitable wireless communication system as needed. In various embodiments, some of the elements of the method shown may be performed simultaneously in a different order than shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be performed as needed. As shown, the method may operate as follows.

[0107] According to some embodiments, UE 106 may establish communication (902) with one or more other UEs 106 and / or BS 102. The communication may include uplink, downlink, and / or sidelink (SL) communication. For example, UE 106 may send and / or receive data and / or control information from one or more other UEs and / or BS. The communication may include UE transmission and / or reception of unicast (e.g., one device to one device), multicast (e.g., one device to a specified group of devices), and / or broadcast (e.g., one device to all devices within range) communication. UE 106 may join one or more groups or be part of a group for (e.g., SL) multicast communication.

[0108] In some embodiments, in various possibilities, UE 106 may be a vehicle and / or the communication may be vehicle-to-everything (V2X) communication. For example, UE 106 may be one of a group of vehicles in an area (e.g., a road, an intersection, etc.) that exchanges information about its movement (e.g., accelerating, braking, steering, etc.). Such communication may be or include ultra-reliable low-latency communication (URLLC) communication and / or may be associated with standards for latency, transmission time, and / or reliability. However, according to some embodiments, UE may not be a vehicle and / or the communication may not be V2X communication. For example, embodiments may include other types of UEs that perform other types of communication.

[0109] In some embodiments, the UE 106 may receive control information (e.g., from the BS 102) to configure a flexible feedback scheme. Such configuration may be semi-static (e.g., indicated in the RRC) and / or dynamic (e.g., indicated in the SL control information (SCI)). The control information may specify whether the flexible feedback scheme is enabled, the maximum number of blind retransmissions that may be performed for a transmission (e.g., N), under what conditions a transmission may (or may not) meet the conditions of the flexible feedback scheme, etc. In the case of semi-static configuration, among various possibilities, the configuration may be provided in one or more of the following ways:

[0110] Per UE (e.g., via SL-PSSCH-TxConfig and / or similar parameters),

[0111] Per SL resource pool (e.g., for a pool with PSFCH resources, flexible feedback may be selectively enabled (in certain configurations) or disabled (note that for a pool without PSFCH resources, blind retransmissions may be used, e.g., HARQ feedback may be disabled)), and / or

[0112] Per transmission characteristic (e.g., QoS flow configuration, LCH, SLRB, etc.) (e.g., for some or any flow / LCH / SLRB in the case where feedback is enabled, flexible feedback may be selectively enabled (in certain configurations) or disabled).

[0113] To account for dynamic channel conditions, the network and / or the BS may also (or alternatively) provide parameters indicating that flexible feedback is enabled under certain conditions or that the flexible feedback configuration may vary according to conditions. Such conditions may include congestion and / or other metrics of channel conditions measured by the channel occupancy ratio (CR) and / or channel busy ratio (CBR) taking into account the UE's own usage. Any combination of dynamic and / or static configurations may be used. For example, the configured maximum number of blind transmissions may vary based on (e.g., according to) congestion and / or for different resource pools, etc. In other words, the network may provide configuration information including different maximum blind retransmission numbers based on the congestion level of the pool (e.g., CR, CBR), and the UE may determine the current or recent congestion level to determine the currently applicable maximum blind retransmission number for the pool.

[0114] In some embodiments, in a flexible feedback scheme, the UE may be configured to potentially reserve a certain number of "blind" retransmissions, for example, without waiting for HARQ feedback. The number may be bounded by a threshold N, which may be configured as control information. According to some embodiments, N may be 0. N may be less than the retransmission parameter (e.g., configured by a higher layer (e.g., RRC) or dynamically (e.g., via SCI)), such as sl-MaxTxTransNumPSSCH-r16–1.

[0115] In some embodiments, the blind retransmission in the flexible feedback scheme can be, for example, a "Boolean" of allowed or not allowed as indicated in the control information. Whether blind retransmission is allowed can be configured by a higher layer (e.g., RRC) or dynamically (e.g., via SCI). In some embodiments, whether blind retransmission is allowed can be configured per UE, per pool, per LCH, per SLRB, and / or per QoS flow, etc., as described above.

[0116] In some embodiments, if blind retransmission in the flexible feedback scheme is allowed, it can be the default behavior, for example, and can be used when the remaining transmission time does not allow the desired number of (e.g., feedback-based) retransmissions, for example, in order to meet the reliability requirements.

[0117] In some embodiments, BS 102 may provide transmission-specific control information. For example, a transmitting (TX) UE 106 may operate in a network-scheduled mode and request resource allocation from the BS. Thus, the BS may directly control how the UE performs the SL HARQ process for a particular transmission (e.g., MAC PDU, TB, etc.). UE 106 may receive DCI (downlink control information) in the PDCCH (physical downlink control channel) from its serving base station (e.g., from BS 102) to allocate dynamic grants that provide resources for one or more SL transmissions (e.g., transmissions such as MAC PDU, TB, etc.). BS 102 may indicate whether blind retransmission is allowed (e.g., an explicit indicator in the DCI for a particular transmission). Alternatively, without using an explicit indicator, BS 102 may implicitly indicate whether blind transmission is allowed. For example, by having two consecutive SL resources that are closely spaced in the time domain (e.g., a first transmission (retransmission) and a second transmission (retransmission) for a particular transmission), BS may indicate that blind transmission may be used. In other words, in the absence of sufficient time to make a HARQ feedback-based decision on whether to perform a retransmission, BS may implicitly indicate that blind transmission may be used by scheduling resources. In this case, UE 106 (e.g., by following the BS 102 instructions or implicit indication in the DCI) may perform a blind retransmission only in the second resource and may not be able to request HARQ feedback corresponding to the transmission scheduled in the first resource. As an alternative to implicit indication, BS may use uplink grants (e.g., or the lack thereof) to indicate whether blind transmission may be used. For example, if PUCCH resources are not provided in the dynamic grant allocation for the HARQ process, TX UE 106 may not have uplink resources to send HARQ feedback to request a new SL grant for retransmission. Then, UE 106 may rely on the SL BSR (buffer status report) to BS 102 and use the SL grant allocated by BS 102 for blind retransmission. As an example, if no PUCCH grant is provided, the UE may lack resources to share SL feedback with the BS. Thus, the UE may not reserve resources for feedback-based transmissions in response to any negative feedback. Instead, the UE may use the SL BSR to indicate to the BS that it still has data to send (e.g., number of retransmissions, number of bits for retransmission, etc.). In response to the BSR, the BS may provide an SL grant to the UE. The UE may use the resources of the SL grant to perform a blind retransmission.

[0118] In some embodiments, control or configuration information may indicate how or whether to allow a UE to hybrid blind retransmissions of transport blocks (TBs) marked for HARQ feedback retransmissions. For example, the SCI may indicate whether some transmissions of enabled feedback streams, LCHs, SLRBs, etc. can be transmitted as blind retransmissions (e.g., without responding to negative feedback of the immediately preceding transmission). For example, the SCI may indicate whether flexible feedback is enabled. For example, the SCI may indicate whether a UE can perform HARQ-enabled retransmissions for TBs (transport blocks) marked for blind retransmissions.

[0119] In some embodiments, UE 106 may provide information to BS 102 (and / or network 100 and / or other UEs 106) regarding its capabilities in terms of flexible feedback schemes. For example, the UE may indicate whether it supports such a scheme, the time of the UE for processing certain messages (e.g., receiving and processing feedback) and / or the transition between RX and TX, etc.

[0120] According to some embodiments, UE 106 may generate a transmission (904). For example, among various possibilities, the transmission may be an SL multicast or unicast transmission. The transmission may be a first transmission (e.g., the first time the UE has transmitted a particular transmission) or may be a retransmission (e.g., a retransmission of a previously transmitted transmission). The transmission may be associated with one or more quality of service (QoS) parameters, e.g., related to latency, transmission time, reliability, etc. For example, the transmission may be a URLLC type communication.

[0121] According to some embodiments, UE 106 may determine whether to request feedback for a transmission (906). Additionally, according to some embodiments, the UE may determine the number of (e.g., remaining) blind retransmissions. The UE may consider various factors in determining whether to request feedback and / or how many blind retransmissions to perform. For example, the UE may consider factors related to the transmission (e.g., the mapping of the transmission to a logical channel, reliability, the remaining potential number of retransmissions, the remaining time for retransmissions, other QoS parameters, etc.), factors related to radio medium conditions (e.g., congestion, signal strength, etc.), and / or other factors.

[0122] In some embodiments, reliability may be considered in grouping transmissions into logical channels (e.g., based on the QoS of the transmission). For example, reliability may be considered in the QoS flow to SLRB mapping. In other words, some QoS flows and / or some transmissions may be associated with a flexible feedback scheme, and other flows / transmissions may be associated with a non-flexible feedback scheme.

[0123] In some embodiments, to determine whether a transmission meets the conditions of a flexible feedback scheme, the UE may consider static and / or dynamic configuration information (as described above with respect to 902) regarding the characteristics of the transmission. For example, the UE may consider LCH / SLRB or QoS flows, etc. For example, for a QoS flow configured to allow flexible HARQ adaptation (e.g., to maximize the reliability of SL transmissions), the transmission may be mapped to an "HARQ FB-enabled" SLRB. Thus, transmissions associated with such a flow may meet the conditions for flexible feedback. This eligibility may be static (e.g., based on LCH, SLRB, or flow) or dynamic, e.g., given current conditions (e.g., congestion level). The UE may perform one or more measurements and / or receive information about the current conditions from another device (e.g., BS 102, other UE 106, etc.) to determine the current conditions.

[0124] For example, in a non-flexible feedback scheme, some flows / transmissions may be designated to request feedback, while other flows / transmissions may be designated to not request feedback (and possibly have a specific number or level of blind retransmissions). For example, if a transmission is mapped to an LCH or SLRB (or otherwise associated) in which feedback is enabled (e.g., non-flexibly), then according to some embodiments, the UE may trigger a retransmission based on the feedback (e.g., PSFCH). Similarly, if a transmission is mapped to an LCH or SLRB (or otherwise associated) in which feedback is disabled (e.g., non-flexibly), then the UE may determine the number of blind retransmissions (e.g., possibly zero or any number greater than zero), and may perform the determined number of blind retransmissions without feedback (e.g., PSFCH). In the case of a transmission / flow associated with a flexible feedback scheme, the UE may determine for each transmission whether to request feedback for the transmission, e.g., as further described below.

[0125] In some embodiments, for a flexible feedback scheme, when determining whether to request feedback for a transmission, the UE may consider timing information associated with retransmissions (e.g., how much time is needed to perform retransmissions with and / or without feedback) with respect to any limitations on how many retransmissions can be performed and / or any transmission time requirements of the transmission (e.g., PDB, latency, etc.). For example, the UE may determine how many retransmissions can be performed with feedback enabled before a target number of blind retransmissions can be transmitted within the transmission time requirements of the transmission. Similarly, the UE may consider whether any time gaps in the resources provided (e.g., in control information) allow the UE time to receive and process the feedback. Similarly, the UE may consider whether any resources provided (e.g., in control information) allow the UE to receive and process the feedback, and then request additional sidelink resources for additional (e.g., feedback-based) retransmissions.

[0126] As a possibility, the UE may determine a threshold retransmission count. The threshold retransmission count may be the (e.g., minimum) number of retransmissions expected to meet a reliability goal (e.g., error rate at the receiver of another UE, e.g., given channel conditions, code rate, etc.). The threshold retransmission count may be configured by the network (e.g., for a specific QoS, etc.) and indicated by an SCI or other configuration information.

[0127] The UE may determine the amount of time to perform the threshold retransmission count with feedback enabled and may compare this amount of time with any transmission time requirement. Configuration information (such as feedback scheduling information, e.g., how and / or when the PSFCH may be scheduled) may be considered to determine the amount of time to perform a certain number of retransmissions to meet the reliability goal. Additionally, the UE may consider the minimum time gap between transmissions, e.g., as described above. If the transmission time requirement provides sufficient time for a certain number of transmissions expected to meet the reliability goal (e.g., including time for receiving and processing feedback), the UE may determine to request feedback. If not, (e.g., if the remaining time is less than or equal to the amount of time to perform the threshold transmission count with feedback), the UE may determine to perform blind retransmissions, e.g., without requesting feedback.

[0128] For example, the UE may compare any transmission time requirement with the amount of time to perform one or more retransmissions with and / or without requesting feedback. For example, for data with certain QoS requirements (e.g., strict transmission time, such as a latency of 10 ms, etc.), the UE may determine not to request feedback (e.g., perform retransmissions without relying on HARQ feedback). For example, if feedback is requested, the strict latency requirement may compromise the UE's ability to meet the reliability requirement (e.g., by performing a certain number of retransmissions expected to meet the reliability requirement). Thus, the UE may not request feedback and may instead select a certain number of blind retransmissions that may be used in this case, e.g., a certain number of transmissions expected to meet the reliability requirement. Alternatively and / or additionally, the UE may select the number of blind retransmissions based on a maximum number of blind retransmissions (e.g., N). For example, the selected number of blind transmissions may not exceed the configured maximum. Similarly, the UE may reserve resources to perform the maximum number of blind retransmissions. To reserve resources for performing blind retransmissions, the UE may reserve resources for transmitting the desired (e.g., maximum or less) number of retransmissions without allowing time to receive or process feedback between retransmissions. In other words, the reservation may be to transmit the time required for each corresponding transmission continuously (e.g., without time to receive feedback for one retransmission before transmitting the next retransmission).

[0129] In some embodiments, the UE may determine to request feedback for one or more transmissions and also determine to perform a certain number of blind retransmissions. In the case of receiving an affirmative acknowledgment for at least one of the one or more transmissions (e.g., from all UEs in the group that are intended transmission recipients), the blind retransmissions may be stopped (e.g., before performing all the number of blind retransmissions).

[0130] As another example, the UE may determine not to request HARQ feedback based on a comparison of the latency associated with HARQ feedback (e.g., considering the configuration of PSFCH resources, such as every 1, 2, or 4 time slots, etc.) with the timing requirement. For example, if the latency associated with HARQ feedback does not allow for a threshold (e.g., minimum) number of retransmissions within the timing requirement, blind retransmissions may be used.

[0131] As a second possibility, the UE may consider the remaining number of available transmissions (retransmissions). If the transmission is the last transmission among the configured maximum number of transmissions (e.g., the remaining number of available transmissions (retransmissions) is 1), the UE may determine not to request feedback.

[0132] In some embodiments, the UE may compare the number of remaining available transmissions (retransmissions) with the number of retransmissions expected to meet the reliability goal (e.g., or other threshold number of retransmissions). For example, if the remaining number of retransmissions is less than or equal to the threshold number of transmissions, the UE may perform blind retransmissions.

[0133] In some embodiments, according to some embodiments, the threshold number of retransmissions to be performed and / or the number of blind retransmissions may be based on the reliability requirement, the number of previous transmissions, and / or the channel condition. For example, if the reliability requirement is high (e.g., the error rate of the QoS of the transmission is low), the threshold number and / or the number of blind retransmissions may be relatively high. Similarly, if the number of previous retransmissions for which negative feedback (NACK) has been received is high, the threshold number and / or the number of blind retransmissions may be relatively high. Similarly, if the channel condition (e.g., signal-to-noise ratio, etc.) is poor, the threshold number and / or the number of blind retransmissions may be relatively high.

[0134] As a third possibility, the UE may consider whether any resources provided by the BS (e.g., in the control information) allow time for feedback. For example, the UE may consider whether the time gap between transmission times allows for receiving and processing feedback. Similarly, the UE may consider whether a gap is provided. Thus, if no gap is provided (or an insufficient gap is provided), for example, for resources that do not include sufficient gaps, the UE may determine to perform blind transmissions (retransmissions). Note that this resource analysis may include determining to perform some transmissions with feedback (e.g., at times with sufficient gaps) and some transmissions without feedback (e.g., at times without sufficient gaps).

[0135] As a fourth possibility, the UE may consider whether any resources provided by the BS (e.g., in control information) allow the UE to request resources for additional retransmissions. For example, if the control information includes an uplink grant (e.g., at an appropriate time), the UL may determine that uplink resources are available. The UE may use such uplink resources to request additional SL resources for additional retransmissions, e.g., by forwarding a negative feedback to the BS in case a negative feedback is received from a peer UE. Similarly, if the resources provided in the control information do not include appropriate uplink resources, the UE may recognize that it is not feasible to request additional SL resources for further retransmissions within the available time (e.g., within the transmission time requirement). The UE may determine to perform a blind retransmission.

[0136] In some embodiments, for a flexible feedback scheme, when determining whether to feedback for a transmission request, the UE may consider the configured maximum number of blind retransmissions (e.g., N, where N may be configured in the control information as discussed in 902). Compared with the maximum total number of retransmissions, the UE may consider the maximum number of blind retransmissions. In other words, the UE may blindly reserve for a limited number of retransmissions (e.g., only the last N retransmissions). In some embodiments, the UE may reserve (e.g., for blind retransmissions) flexibly (e.g., without a network configuration limit on the number of retransmissions N).

[0137] In some embodiments, for a flexible feedback scheme, when determining whether to feedback for a transmission request, the UE may (e.g., further) consider channel conditions such as congestion level. For example, if the congestion level (e.g., the evaluated CR) is high or above a threshold, feedback may be requested (e.g., blind retransmissions may not be triggered). This may potentially reduce the total number of retransmissions of the transmission and thus may limit the contribution of the transmission and retransmissions to channel occupancy. If the evaluated CR is low, blind retransmissions may be triggered (e.g., feedback may not be requested). As discussed above, this may allow for more retransmissions within the time constraint (e.g., PDB).

[0138] In some embodiments, some LCHs, SLRBs, or streams may be associated with a non-flexible resource scheme (e.g., indicating that HARQ feedback is disabled and blind transmission should be used). However, some aspects of the flexible feedback scheme may be applied to such transmissions, e.g., after multiplexing those LCHs in a TB. For example, if a transmission of an LCH configured with "HARQ feedback disabled" is selected in a TX pool configured with PSFCH resources, the UE may selectively determine to enable feedback. In other words, the UE can adapt and enable feedback for the transmission and / or one or more retransmissions (e.g., blind or feedback-based). For example, if the channel is busy (e.g., CBR and / or CR is high), the UE may enable feedback for this transmission. This may potentially improve reliability. Additionally, PSFCH resources may be available (e.g., considered free to use). Then, if positive feedback is received (e.g., ACK from each peer device in a group / area), the UE may (e.g., at the MAC layer) cancel the blind retransmission. If negative feedback (NACK) is received (e.g., or if positive feedback is not received from all expected peer devices), the UE may not cancel the blind retransmission and may continue to perform blind transmissions until positive feedback is received or the planned number of blind retransmissions is completed. The total number of transmissions (retransmissions) may be bounded by a condition-specific (e.g., CBR-adapted) maximum number of transmissions (retransmissions). Thus, this method can reduce the use of channel resources while still maintaining the desired reliability level.

[0139] In some embodiments, determining not to request feedback may cause the UE to avoid the need to request additional resources (e.g., for feedback-based retransmissions). For example, a mode 1 TX UE may not share feedback with the BS to request retransmission resources. Instead, the UE may (e.g., based on determining not to request feedback for a transmission) acquire resources (e.g., via contention or scheduling requests, etc.), acquire resources for the transmission and for retransmissions in the plan. According to some embodiments, such resource acquisition may be performed in one go.

[0140] According to some embodiments, the UE 106 may transmit a transmission (908). According to some embodiments, the UE 106 may also transmit an indication of whether feedback is requested. The indication may be transmitted simultaneously with the transmission (e.g., possibly as part of that transmission), and / or the indication may be transmitted separately. The UE may also transmit any number of (e.g., blind) retransmissions, e.g., as determined in 906 or otherwise. The UE may also transmit an indication of whether feedback is requested for any retransmission. One indication may be used to indicate whether feedback is requested for a single transmission (retransmission) and / or multiple transmissions (retransmissions).

[0141] According to some embodiments, a UE may use layer 1 (L1) signaling to indicate whether feedback is requested. Among various possibilities, the L1 signaling may use SCI format A or B. Any format may be used to indicate requested or unrequested feedback.

[0142] For SCI format A, if the TX UE determines not to request feedback (e.g., suppress any physical shared feedback channel (PSFCH) transmission of a receiving (RX) UE), it may use a location parameter or other parameter in SCI format A to indicate the request. For example, the TX UE may include “0” in the range parameter. Similarly, a region ID value may be specified to indicate unrequested feedback. In addition, different parameters of SCI format A (or new parameters may be added) may be used to indicate that feedback is not requested for a transmission. Thus, any RX UE detecting an indication of unrequested feedback may determine not to transmit ACK / NACK feedback. The RX UE may decode the transmission.

[0143] In some embodiments, the network may configure (e.g., and / or a wireless communication standard may specify) the UE to decode a message having a range parameter equal to 0. In other words, layer 2 (L2) signaling may be used to configure the UE to correctly interpret the layer 1 indication. For example, the radio resource control (RRC) configuration may be modified to allow “range = 0” to be added as a code point and / or indicate that a message having range = 0 should be decoded.

[0144] SCI format B may include a field indicating “no feedback”. Thus, the TX UE may use this field to indicate whether feedback is requested.

[0145] Thus, SCI format A or B may be used to indicate whether feedback is requested (or not requested). According to some embodiments, other formats may also (or alternatively) be used.

[0146] In some embodiments, the same SCI format as the first transmission may be used for retransmission. For example, if SCI format A is used for the first transmission (e.g., the first transmission of a transport block (TB) etc.), then SCI format A may also be used for any retransmission of the transmission (e.g., the transmission of a TB). In other words, the UE may use the same SCI format for any retransmission of a transmission. In some embodiments, the UE may switch to a different format.

[0147] In some embodiments, UE 106 may receive feedback (e.g., ACK and / or NACK, e.g., on the PSFCH) from one or more peer UEs (e.g., members of an intended transmission of a group).

[0148] If feedback (and / or lack of feedback) indicates that all or a group of peer UEs have successfully received a transmission (e.g., positive feedback and / or lack of negative feedback, such as in a NACK-only scenario), the UE may stop further retransmissions of the transmission. For example, the UE may determine that the peer UE has received the transmission based on receiving sufficient ACKs and / or not receiving NACKs and may stop any remaining retransmissions. In some embodiments, the UE may continue with retransmissions.

[0149] If the feedback is negative (e.g., at least one peer UE has not successfully received the transmission, e.g., which may be indicated by a NACK or lack of ACK), the UE may determine to transmit one or more (e.g., additional) retransmissions and / or continue with the planned retransmissions.

[0150] Additional Information and Examples

[0151] In one example, the UE may transmit a transmission and determine (e.g., based on a criterion such as the remaining time associated with the transmission compared to the amount of time required to receive feedback and transmit a certain number of retransmissions; maximum blind retransmission count; maximum total transmission count; etc.) to request feedback for that transmission. The UE may receive negative feedback, e.g., at least one NACK. In response to the negative feedback, the UE may determine to retransmit the transmission. The UE may further determine whether to request feedback for the next transmission (retransmission) (e.g., based on a similar criterion and updated information). The UE may repeat this process of receiving (e.g., negative) feedback and determining to retransmit (e.g., and request feedback) any number of times. If the remaining time associated with the transmission does not allow for sufficient retransmissions with feedback to reach a minimum total transmission count (e.g., a minimum number based on a reliability criterion), the UE may determine not to request feedback for additional retransmissions. Thus, the UE may reserve resources for multiple (e.g., consecutive) retransmissions to reach the minimum total transmission count. In some embodiments, the UE may request feedback for one or more of the retransmissions (e.g., even when there is not enough time to receive and / or process feedback before transmitting the next retransmission). Then, if the feedback is positive (e.g., or no negative feedback is received in a NACK-only scenario), the UE may stop further retransmissions after processing the feedback.

[0152] In some embodiments, the UE may use feedback-based transmission for a first number of retransmissions and may use consecutive (e.g., blind, non-feedback-based) retransmissions for the remaining number of retransmissions. When the UE approaches a limit (e.g., transmission time requirement and / or maximum retry limit), the UE may switch from feedback-based retransmissions to consecutive retransmissions. For example, within the retry limit, the UE may not request feedback for the last transmission.

[0153] In a set of embodiments, for each transmission attempt of a packet, the UE may indicate to a peer UE whether HARQ feedback is requested. The indication of whether feedback is requested may or may not be the same as the last attempt or any other previous attempt.

[0154] In some embodiments, if the transmission will be the last transmission according to the configured maximum number of transmissions (retransmissions), the UE may indicate "no feedback".

[0155] In some embodiments, if the transmission is the last transmission allowed before the packet delay budget is met, the UE may indicate "no feedback".

[0156] In another set of embodiments, the system may be configured to allow a flexible mix of blind retries and feedback-based retries.

[0157] In another set of embodiments, the UE may be configured with an upper limit on retransmissions that can be performed blindly.

[0158] In some embodiments, when the UE is configured to allow blind retransmissions, in cases where the time gap requirement for resource selection is not possible, the UE may reserve resources for blind retransmissions.

[0159] In some embodiments, when the UE is configured to allow blind retransmissions, the UE may apply blind retransmissions only to the last few retransmission attempts that can be available before the UE hits the packet delay budget or the maximum transmission limit.

[0160] In some embodiments, the configuration may be performed by: a standard specification (e.g., flexible feedback and / or blind retransmissions may always be allowed), an NW configuration, or a pre-configuration in the RRC protocol. The configuration may be on a per-UE, per-pool, per-flow / SLRB, per-CR / CBR basis.

[0161] In some embodiments, a user equipment device (UE) may include radio components; and a processor operably connected to the radio components and configured to cause the UE: receive configuration information from a base station, the configuration information including a maximum number of blind retransmissions; generate a first multicast transmission; determine to request feedback for the first multicast transmission; transmit the first multicast transmission and an indication of the request for feedback for the first multicast transmission; reserve resources to transmit a certain number of retransmissions of the first multicast transmission, where the number of retransmissions is less than or equal to the maximum number of blind retransmissions; and transmit at least one of the number of retransmissions.

[0162] Embodiments of the present disclosure may be implemented in any of a variety of forms. For example, some embodiments may be implemented as a computer-implemented method, a computer-readable memory medium, or a computer system. Other embodiments may be implemented using one or more custom-designed hardware devices such as an ASIC. Still other embodiments may be implemented using one or more programmable hardware elements such as an FPGA.

[0163] According to some embodiments, any method among the methods described herein for operating a user equipment (UE) can form the basis for a corresponding method for operating a base station by interpreting each message / signal X received by the UE in the downlink as a message / signal X transmitted by the base station, and interpreting each message / signal Y transmitted by the UE in the uplink as a message / signal Y received by the base station.

[0164] In some embodiments, a non-transitory computer-readable memory medium may be configured such that it stores program instructions and / or data, where if the program instructions are executed by a computer system, the computer system is caused to execute a method, such as any of the method embodiments described herein, or any combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets.

[0165] In some embodiments, a device (e.g., a UE) may be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, and where the program instructions are executable to implement any of the various method embodiments described herein (or any combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets). The device may be implemented in any of a variety of forms.

[0166] It is well known that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of the authorized use should be clearly explained to the user.

[0167] Although the above embodiments have been described in considerable detail, many variations and modifications will become apparent to those skilled in the art once the above disclosure is fully understood. The present disclosure is intended that the following claims be construed to cover all such variations and modifications.

Claims

1. A method for wireless communication, comprising: Receiving sidelink control information (SCI) and a first multicast transmission from a transmitting user equipment (UE), wherein the first multicast transmission is associated with a first location-based parameter indicated in the SCI; Determining whether to enable feedback based on a first field in the SCI, wherein the first field in the SCI is different from the first location-based parameter; Attempting to decode the first multicast transmission, wherein the first multicast transmission is decoded when the first location-based parameter indicates a first range equal to 0, and not decoded when the first location-based parameter indicates a second range not equal to 0; And When feedback is requested according to the first field in the SCI, determining whether to provide feedback in response to the first multicast transmission based on the first location-based parameter.

2. The method according to claim 1, wherein the first location-based parameter indicates a first range equal to 0.

3. The method according to claim 1, further comprising: Receiving a second multicast transmission from the transmitting UE, wherein the second multicast transmission is associated with a second location-based parameter, and wherein the second location-based parameter indicates a second range greater than 0; Determining a range to the transmitting UE; Determining that the range to the transmitting UE is greater than the second range; And Based on the determination that the range to the transmitting UE is greater than the second range, determining not to decode the second multicast transmission.

4. The method according to claim 1, further comprising: Receiving an indication of whether feedback is requested for the first multicast transmission.

5. The method according to claim 1, further comprising: Receiving a blind retransmission of the first multicast transmission.

6. The method according to claim 1, wherein the first field in the SCI indicates dynamic eligibility for a flexible feedback scheme, wherein according to the flexible feedback scheme, information about current conditions from another device is used to dynamically determine eligibility.

7. An apparatus comprising a processor configured to cause a user equipment (UE) to perform the method according to any one of claims 1 to 6.

8. The apparatus according to claim 7, further comprising radio components operatively coupled to the processor.

9. A non-transitory computer-readable medium comprising program instructions configured to cause a user equipment UE to perform the method according to any one of claims 1 to 6.

10. A computer program product configured to cause a user equipment UE to perform the method according to any one of claims 1 to 6.

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