WO2022094562A2

WO2022094562A2 - Hybrid automatic repeat request (harq) feedback bundling

Info

Publication number: WO2022094562A2
Application number: PCT/US2021/072055
Authority: WO
Inventors: Konstantinos Dimou; Yan Zhou; Jing Sun; Tao Luo; Yi Huang; Peter Gaal; Wanshi Chen
Original assignee: Qualcomm Incorporated
Priority date: 2020-10-27
Filing date: 2021-10-27
Publication date: 2022-05-05
Also published as: WO2022094562A3

Abstract

Various aspects relate to providing hybrid automatic repeat request (HARQ) feedback. Some aspects more specifically relate to bundling HARQ feedback for downlink transmissions to reduce or avoid instances of collisions between the HARQ feedback and downlink transmissions. In some examples, a user equipment (UE) may receive a first downlink transmission from a base station. The UE may generate first HARQ feedback associated with the first downlink transmission. In some examples, the UE may receive a downlink control information (DCI) message from the base station indicating a second downlink transmission that conflicts with (or "overlaps" with) transmission of the first HARQ feedback to the base station. According to some aspects, the UE may defer the transmission of the first HARQ feedback until after the second downlink transmission and may subsequently bundle the first HARQ feedback with second HARQ feedback associated with the second downlink transmission.

Description

HYBRID AUTOMATIC REPEAT REQUEST (HARQ) FEEDBACK BUNDLING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Greek Patent Application No. 20200100650, entitled, “HYBRID AUTOMATIC REPEAT REQUEST (HARQ) FEEDBACK BUNDLING,” filed on October 27, 2020, which is expressly incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] Aspects of disclosure relate generally to wireless communication systems, and more particularly to providing hybrid automatic repeat request (HARQ) feedback.

DESCRIPTION OF THE RELATED TECHNOLOGY

[0003] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. A wireless multiple-access communication system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE). These systems may be capable of supporting communication with multiple UEs by sharing the available system resources (such as time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE- Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM).

[0004] In some circumstances, wireless signals in a wireless communication system are subject to noise or interference. For example, in some cases, a downlink signal transmitted by a base station to a UE may collide with an uplink signal transmitted by the UE to the base station. In such examples, the UE may fail to receive the downlink signal, and the base station may fail to receive the uplink signal, which may result in lost data or retransmission of the data, reducing throughput in the wireless communication system.

SUMMARY

[0005] One innovative aspect of the subject matter described in this disclosure can be implemented in a user equipment (UE) that includes at least one processor and at least one memory storing code that, when executed by the at least one processor, is configured to cause the UE to receive, from a base station, a first downlink transmission. The at least one processor is further configured to generate first hybrid automatic repeat request (HARQ) feedback based on the reception of the first downlink transmission and to receive, from the base station prior to transmission of the first HARQ feedback, a downlink control information (DCI) message indicating a second downlink transmission. The at least one processor is further configured to defer, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission and to receive, from the base station, the second downlink transmission in the one or more second resources. The at least one processor is further configured to generate second HARQ feedback based on the reception of the second downlink transmission and to transmit, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[0006] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication performed by UE. The method includes receiving, from a base station, a first downlink transmission, generating first HARQ feedback based on the reception of the first downlink transmission, and receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. The method further includes deferring, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission and receiving, from the base station, the second downlink transmission in the one or more second resources. The method further includes generating second HARQ feedback based on the reception of the second downlink transmission and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[0007] Another innovative aspect of the subject matter described in this disclosure can be implemented in a base station includes at least one processor and at least one memory storing code that, when executed by the at least one processor, is configured to cause the base station to transmit, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The at least one processor is further configured to transmit, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission, one or more first resources associated with the transmission of the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission. The at least one processor is further configured to transmit, to the UE, the second downlink transmission in the one or more second resources and to receive, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[0008] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication performed by a UE. The method includes receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The method further includes receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The method further includes deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The method further includes receiving, from the base station, the second downlink transmission in the one or more second resources, generating second HARQ feedback based on the reception of the second downlink transmission, and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback. [0009] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium storing instructions executable by a processor to perform operations including receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The operations further include receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The operations further include deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The operations further include receiving, from the base station, the second downlink transmission in the one or more second resources, generating second HARQ feedback based on the reception of the second downlink transmission, and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[0010] Another innovative aspect of the subject matter described in this disclosure can be implemented in a UE. The UE includes a memory and one or more processors coupled to the memory. The one or more processors are configured to receive, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The one or more processors are further configured to receive, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and to determine, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The one or more processors are further configured to defer, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The one or more processors are further configured to receive, from the base station, the second downlink transmission in the one or more second resources, to generate second HARQ feedback based on the reception of the second downlink transmission, and to transmit, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[0011] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. The apparatus includes means for receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The apparatus further includes means for receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and means for determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The apparatus further includes means for deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The apparatus further includes means for receiving, from the base station, the second downlink transmission in the one or more second resources, means for generating second HARQ feedback based on the reception of the second downlink transmission, and means for transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication performed by a base station. The method includes transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The method further includes transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The method further includes transmitting, to the UE, the second downlink transmission in the one or more second resources. The method further includes receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission. [0013] Another innovative aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium storing instructions executable by a processor to perform operations. The operations include transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The operations further include transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The operations further include transmitting, to the UE, the second downlink transmission in the one or more second resources. The operations further include receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[0014] Another innovative aspect of the subject matter described in this disclosure can be implemented in a base station. The base station includes a memory and one or more processors coupled to the memory. The one or more processors are configured to transmit, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The one or more processors are further configured to transmit, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The one or more processors are further configured to transmit, to the UE, the second downlink transmission in the one or more second resources. The one or more processors are further configured to receive, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[0015] Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. The apparatus includes means for transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The apparatus further includes means for transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The apparatus further includes means for transmitting, to the UE, the second downlink transmission in the one or more second resources. The apparatus further includes means for receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a pictorial diagram illustrating an example wireless communication system according to one or more aspects of the disclosure.

[0017] Figure 2 is a block diagram illustrating an example base station and an example user equipment (UE) according to one or more aspects of the disclosure.

[0018] Figure 3 is a block diagram illustrating an example wireless communication system that supports hybrid automatic repeat request (HARQ) feedback bundling according to one or more aspects of the disclosure.

[0019] Figure 4 is a timing diagram illustrating example timing of operations that may be performed to support HARQ feedback bundling according to some aspects of the disclosure.

[0020] Figure 5 is a flow diagram illustrating an example process that supports HARQ feedback bundling according to one or more aspects.

[0021] Figure 6 is a flow diagram illustrating an example process that supports HARQ feedback bundling according to one or more aspects.

[0022] Figure 7 is a block diagram of an example UE that supports HARQ feedback bundling according to one or more aspects.

[0023] Figure 8 is a block diagram of an example base station that supports HARQ feedback bundling according to one or more aspects.

DETAILED DESCRIPTION

[0024] Various aspects of the present disclosure relate to providing hybrid automatic repeat request (HARQ) feedback. Some aspects more specifically relate to bundling HARQ feedback for downlink transmissions to reduce or avoid instances of collisions between the HARQ feedback and downlink transmissions. In some examples, a user equipment (UE) may receive a first downlink transmission from a base station, such as a semi-persistently scheduled (SPS) downlink transmission. The UE may generate first HARQ feedback associated with the first downlink transmission. In some examples, the UE may receive a downlink control information (DCI) message from the base station indicating (or scheduling) a second downlink transmission that conflicts with (or “overlaps” with) transmission of the first HARQ feedback to the base station. In some examples, the second downlink transmission may correspond to a physical downlink shared channel (PDSCH) transmission. According to some aspects, the UE may defer the transmission of the first HARQ feedback until after the second downlink transmission and may subsequently bundle the first HARQ feedback with second HARQ feedback associated with the second downlink transmission.

[0025] In some aspects, HARQ feedback may be generated based on a HARQ codebook, such as a type-3 HARQ codebook or a modified type-3 HARQ codebook. The HARQ codebook may be indicated using the DCI message, which may exclude a new data indicator (NDI) field that may be included in some other DCI messages. By excluding the NDI field, the UE may avoid flushing one or more buffers, which may enable the UE to defer transmitting the HARQ feedback. To illustrate, upon receiving the DCI message, the UE may determine HARQ process identifiers (IDs) associated with the DCI message and may avoid flushing a buffer associated with the HARQ process IDs, which may enable the UE to defer providing HARQ feedback associated with the HARQ process IDs.

[0026] Alternatively or in addition, the DCI message may include a first bit to indicate whether the first HARQ feedback is to be bundled with the second HARQ feedback. To illustrate, the first bit may have one of a first value (such as a logic one value or a logic zero value) or a second value (such as a logic zero value or a logic one value) that are selectable by the base station. The first value may indicate that the first HARQ feedback is to be bundled with the second HARQ feedback based on a resource conflict between the first HARQ feedback and the second downlink transmission. The second value may indicate that the UE is to refrain from bundling the first HARQ feedback with the second HARQ feedback.

[0027] In some examples, the first bit may enable the base station to request selectively retransmission of HARQ feedback. For example, based on an error event (such as due to noise, interference, or another condition) associated with the second downlink transmission, the bundled HARQ feedback may indicate an acknowledgement (ACK) of the first downlink transmission and a negative-acknowledgement (NACK) of the second downlink transmission. In such examples, the base station may transmit a second DCI message indicating retransmission of the second downlink transmission and including the first bit to indicate that the UE is to avoid bundling the second HARQ feedback.

[0028] Alternatively or in addition to the first bit, the DCI message may include a second bit indicating whether the UE is to report deferred HARQ feedback for all SPS configurations associated with the HARQ ID or for a particular SPS configuration associated with the HARQ ID, such as an SPS configuration associated with the DCI message. To illustrate, in some implementations, multiple SPS configurations associated with the UE may be associated with one or more common HARQ IDs (such as due to a limited number of available HARQ IDs). The second bit may indicate whether deferred HARQ feedback is requested for all SPS configurations associated with the HARQ ID or for a particular SPS configuration associated with the HARQ ID.

[0029] Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, the described techniques can be used to reduce or avoid collision of signals that may result in lost messages or retransmission of the signals. For example, by deferring transmission of the first HARQ feedback, the UE may avoid collision between the first HARQ feedback and the second downlink transmission. Reducing or avoiding collisions may reduce or avoid instances of lost messages or signal retransmissions, improving performance as compared to some techniques that transmit HARQ feedback according to a just-in-time basis, which may result in a collision in some cases.

[0030] Further, use of the first bit may enable selective disabling of HARQ feedback bundling, which may improve performance in some cases. For example, if no resource conflict is expected to occur (such as in the case of some retransmissions), the base station may indicate, using the first bit, disabling of HARQ feedback bundling. As a result, by disabling HARQ feedback bundling using the first bit, the base station may receive HARQ feedback more quickly, which may reduce latency in some circumstances.

[0031] In some other implementations, DCI overhead may be reduced by excluding the first bit from the DCI message. For example, some wireless communication protocols may be associated with relatively high reliability, in which case error events (and retransmissions) may be relatively unlikely or infrequent, such as in the case of an ultrareliable low-latency communication (URLLC) wireless communication protocol. In one example, the DCI message excludes the first bit, and the base station and the UE operate based on a URLLC wireless communication protocol.

[0032] In some cases, the second bit may be used to determine a size or amount of HARQ feedback bundling, which may improve performance in some circumstances. For example, the second bit may indicate whether the UE is to report a first group of deferred HARQ feedback (such as deferred HARQ feedback for all semi -persistent scheduling (SPS) configurations associated with a HARQ ID) or for a second group of deferred HARQ feedback (such as a particular SPS configuration associated with the HARQ ID). In some examples, the first group may include more deferred HARQ feedback than the second group. As a result, the second bit may be used to determine an amount of HARQ feedback to be included in a message, which may enable the base station to reduce or avoid messages that include a relatively large amount of deferred HARQ feedback.

[0033] To further illustrate, aspects of the disclosure may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC- FDMA) networks, LTE networks, GSM networks, 5th Generation (5G) or new radio (NR) networks (sometimes referred to as “5G NR” networks, systems, or devices), as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

[0034] A CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, and the like. UTRA includes wideband- CDMA (W-CDMA) and low chip rate (LCR). CDMA2000 covers IS-2000, IS-95, and IS-856 standards.

[0035] A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). 3GPP defines standards for the GSM EDGE (enhanced data rates for GSM evolution) radio access network (RAN), also denoted as GERAN. GERAN is the radio component of GSM or GSM EDGE, together with the network that joins the base stations (for example, the Ater and Abis interfaces, among other examples) and the base station controllers (for example, A interfaces, among other examples). The radio access network represents a component of a GSM network, through which phone calls and packet data are routed from and to the public switched telephone network (PSTN) and Internet to and from subscriber handsets, also known as user terminals or user equipments (UEs). A mobile phone operator's network may include one or more GERANs, which may be coupled with UTRANs in the case of a UMTS or GSM network. Additionally, an operator network may include one or more LTE networks, or one or more other networks. The various different network types may use different radio access technologies (RATs) and radio access networks (RANs).

[0036] An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS). In particular, long term evolution (LTE) is a release of UMTS that uses E- UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named the “3rd Generation Partnership Project” (3GPP), and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known or are being developed. For example, the 3GPP is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3 GPP project aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure may describe certain aspects with reference to LTE, 4G, 5G, or NR technologies; however, the description is not intended to be limited to a specific technology or application, and one or more aspects described with reference to one technology may be understood to be applicable to another technology. Indeed, one or more aspects the present disclosure are related to shared access to wireless spectrum between networks using different radio access technologies or radio air interfaces.

[0037] 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. To achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (loTs) with an ultra-high density (such as ~1M nodes per km^A2), ultra-low complexity (such as ~10s of bits per sec), ultra-low energy (such as -10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (such as -99.9999% reliability), ultra-low latency (such as - 1 millisecond (ms)), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (such as - 10 Tbps per km^A2), extreme data rates (such as multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.

[0038] 5G NR devices, networks, and systems may be implemented to use optimized OFDM-based waveform features. These features may include scalable numerology and transmission time intervals (TTIs); a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD) or frequency division duplex (FDD) design; and advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD or TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80 or 100 MHz bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500MHz bandwidth.

[0039] The scalable numerology of 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink or downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive uplink or downlink that may be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet the current traffic needs.

[0040] For clarity, certain aspects of the apparatus and techniques may be described below with reference to example 5G NR implementations or in a 5G-centric way, and 5G terminology may be used as illustrative examples in portions of the description below; however, the description is not intended to be limited to 5G applications.

[0041] Moreover, it should be understood that, in operation, wireless communication networks adapted according to the concepts herein may operate with any combination of licensed or unlicensed spectrum depending on loading and availability. Accordingly, it will be apparent to a person having ordinary skill in the art that the systems, apparatus and methods described herein may be applied to other communication systems and applications than the particular examples provided.

[0042] Figure 1 is a pictorial diagram illustrating an example wireless communication system according to one or more aspects of the disclosure. The wireless communication system may include wireless network 100. The wireless network 100 may, for example, include a 5G wireless network. As appreciated by those skilled in the art, components appearing in Figure 1 are likely to have related counterparts in other network arrangements including, for example, cellular-style network arrangements and non- cellular-style-network arrangements, such as device-to-device, peer-to-peer or ad hoc network arrangements, among other examples.

[0043] The wireless network 100 illustrated in Figure 1 includes a number of base stations 105 and other network entities. A base station may be a station that communicates with the UEs and may be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each base station 105 may provide communication coverage for a particular geographic area. In 3 GPP, the term “cell” can refer to this particular geographic coverage area of a base station or a base station subsystem serving the coverage area, depending on the context in which the term is used. In implementations of the wireless network 100 herein, the base stations 105 may be associated with a same operator or different operators, such as the wireless network 100 may include a plurality of operator wireless networks. Additionally, in implementations of the wireless network 100 herein, the base stations 105 may provide wireless communications using one or more of the same frequencies, such as one or more frequency bands in licensed spectrum, unlicensed spectrum, or a combination thereof, as a neighboring cell. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In some other examples, each base station 105 and UE 115 may be operated by a single network operating entity.

[0044] A base station may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, or other types of cell. A macro cell generally covers a relatively large geographic area, such as several kilometers in radius, and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area, such as a home, and, in addition to unrestricted access, may provide restricted access by UEs having an association with the femto cell, such as UEs in a closed subscriber group (CSG), UEs for users in the home, and the like. A base station for a macro cell may be referred to as a macro base station. A base station for a small cell may be referred to as a small cell base station, a pico base station, a femto base station or a home base station. In the example shown in Figure 1, base stations 105d and 105e are regular macro base stations, while base stations 105a-105c are macro base stations enabled with one of 3 dimension (3D), full dimension (FD), or massive MEMO. Base stations 105a-105c take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. Base station 105f is a small cell base station which may be a home node or portable access point. A base station may support one or multiple cells, such as two cells, three cells, four cells, and the like.

[0045] The wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. In some scenarios, networks may be enabled or configured to handle dynamic switching between synchronous or asynchronous operations.

[0046] The UEs 115 are dispersed throughout the wireless network 100, and each UE may be stationary or mobile. It should be appreciated that, although a mobile apparatus is commonly referred to as user equipment (UE) in standards and specifications promulgated by the 3GPP, such apparatus may additionally or otherwise be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. Within the present document, a “mobile” apparatus or UE need not necessarily have a capability to move, and may be stationary. Some non-limiting examples of a mobile apparatus, such as may include implementations of one or more of the UEs 115, include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a laptop, a personal computer (PC), a notebook, a netbook, a smart book, a tablet, and a personal digital assistant (PDA). A mobile apparatus may additionally be an “Internet of things” (loT) or “Internet of everything” (loE) device such as an automotive or other transportation vehicle, a satellite radio, a global positioning system (GPS) device, a logistics controller, a drone, a multi-copter, a quad-copter, a smart energy or security device, a solar panel or solar array, municipal lighting, water, or other infrastructure; industrial automation and enterprise devices; consumer and wearable devices, such as eyewear, a wearable camera, a smart watch, a health or fitness tracker, a mammal implantable device, a gesture tracking device, a medical device, a digital audio player (such as MP3 player), a camera or a game console, among other examples; and digital home or smart home devices such as a home audio, video, and multimedia device, an appliance, a sensor, a vending machine, intelligent lighting, a home security system, or a smart meter, among other examples. In one aspect, a UE may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, UEs that do not include UICCs may be referred to as loE devices. The UEs 115a— 115d of the implementation illustrated in Figure 1 are examples of mobile smart phone-type devices accessing the wireless network 100. A UE may be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband loT (NB- loT) and the like. The UEs 115e— 115k illustrated in Figure 1 are examples of various machines configured for communication that access 5G network 100.

[0047] A mobile apparatus, such as the UEs 115, may be able to communicate with any type of the base stations, whether macro base stations, pico base stations, femto base stations, relays, and the like. In Figure 1, a communication link (represented as a lightning bolt) indicates wireless transmissions between a UE and a serving base station, which is a base station designated to serve the UE on the downlink or uplink, or desired transmission between base stations, and backhaul transmissions between base stations. Backhaul communication between base stations of the wireless network 100 may occur using wired or wireless communication links.

[0048] In operation at the 5G network 100, the base stations 105a-105c serve the UEs 115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. Macro base station 105d performs backhaul communications with the base stations 105a-105c, as well as small cell, the base station 105f. Macro base station 105d also transmits multicast services which are subscribed to and received by the UEs 115c and 115d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

[0049] The wireless network 100 of implementations supports mission critical communications with ultra-reliable and redundant links for mission critical devices, such the UE 115e, which is a drone. Redundant communication links with the UE 115e include from the macro base stations 105d and 105e, as well as small cell base station 105f. Other machine type devices, such as UE 115f (thermometer), the UE 115g (smart meter), and the UE 115h (wearable device) may communicate through the wireless network 100 either directly with base stations, such as the small cell base station 105f, and the macro base station 105e, or in multi-hop configurations by communicating with another user device which relays its information to the network, such as the UE 115f communicating temperature measurement information to the smart meter, the UE 115g, which is then reported to the network through the small cell base station 105f. The 5G network 100 may provide additional network efficiency through dynamic, low-latency TDD or FDD communications, such as in a vehi cl e-to- vehicle (V2V) mesh network between the UEs 115i— 115k communicating with the macro base station 105e.

[0050] Figure 2 is a block diagram illustrating an example base station 105 and an example UE 115 according to one or more aspects of the disclosure. The base station 105 and the UE 115 may be one of the base stations and one of the UEs in Figure 1. For a restricted association scenario (as mentioned above), the base station 105 may be the small cell base station 105f in Figure 1, and the UE 115 may be the UE 115c or 115d operating in a service area of the base station 105f, which in order to access the small cell base station 105f, would be included in a list of accessible UEs for the small cell base station 105f. Additionally, the base station 105 may be a base station of some other type. As shown in Figure 2, the base station 105 may be equipped with antennas 234a through 234t, and the UE 115 may be equipped with antennas 252a through 252r for facilitating wireless communications.

[0051] At the base station 105, a transmit processor 220 may receive data from a data source 212 and control information from a controller 240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid-ARQ (automatic repeat request) indicator channel (PHICH), physical downlink control channel (PDCCH), enhanced physical downlink control channel (EPDCCH), or MTC physical downlink control channel (MPDCCH), among other examples. The data may be for the PDSCH, among other examples. The transmit processor 220 may process, such as encode and symbol map, the data and control information to obtain data symbols and control symbols, respectively. Additionally, the transmit processor 220 may generate reference symbols, such as for the primary synchronization signal (PSS) and secondary synchronization signal (SSS), and cellspecific reference signal. Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to modulators (MODs) 232a through 232t. For example, spatial processing performed on the data symbols, the control symbols, or the reference symbols may include precoding. Each modulator 232 may process a respective output symbol stream, such as for OFDM, among other examples, to obtain an output sample stream. Each modulator 232 may additionally or alternatively process the output sample stream to obtain a downlink signal. For example, to process the output sample stream, each modulator 232 may convert to analog, amplify, filter, and upconvert the output sample stream to obtain the downlink signal. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

[0052] At the UE 115, the antennas 252a through 252r may receive the downlink signals from the base station 105 and may provide received signals to the demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition a respective received signal to obtain input samples. For example, to condition the respective received signal, each demodulator 254 may filter, amplify, downconvert, and digitize the respective received signal to obtain the input samples. Each demodulator 254 may further process the input samples, such as for OFDM, among other examples, to obtain received symbols. MIMO detector 256 may obtain received symbols from demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 258 may process the detected symbols, provide decoded data for the UE 115 to a data sink 260, and provide decoded control information to a controller 280. For example, to process the detected symbols, the receive processor 258 may demodulate, deinterleave, and decode the detected symbols.

[0053] On the uplink, at the UE 115, a transmit processor 264 may receive and process data (such as for the physical uplink shared channel (PUSCH)) from a data source 262 and control information (such as for the physical uplink control channel (PUCCH)) from the controller 280. Additionally, the transmit processor 264 may generate reference symbols for a reference signal. The symbols from the transmit processor 264 may be precoded by TX MIMO processor 266 if applicable, further processed by the modulators 254a through 254r (such as for SC-FDM, among other examples), and transmitted to the base station 105. At base station 105, the uplink signals from the UE 115 may be received by antennas 234, processed by demodulators 232, detected by MIMO detector 236 if applicable, and further processed by receive processor 238 to obtain decoded data and control information sent by the UE 115. The receive processor 238 may provide the decoded data to data sink 239 and the decoded control information to the controller 240.

[0054] The controllers 240 and 280 may direct the operation at the base station 105 and the UE 115, respectively. The controller 240 or other processors and modules at the base station 105 or the controller 280 or other processors and modules at the UE 115 may perform or direct the execution of various processes for the techniques described herein, such as to perform or direct the execution illustrated in Figures 5 and 6, or other processes for the techniques described herein. The memories 242 and 282 may store data and program codes for the base station 105 and The UE 115, respectively. Scheduler 244 may schedule UEs for data transmission on the downlink or uplink.

[0055] In some cases, the UE 115 and the base station 105 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed, such as contention-based, frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, the UEs 115 or the base stations 105 may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, the UE 115 or base station 105 may perform a listen-before-talk or listen- before-transmitting (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available. A CCA may include an energy detection procedure to determine whether there are any other active transmissions. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. In some implementations, a CCA may include detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own back off window based on the amount of energy detected on a channel or the acknowledge or negative-acknowledge (ACK or NACK) feedback for its own transmitted packets as a proxy for collisions.

[0056] Various aspects of the present disclosure relate to providing hybrid automatic repeat request (HARQ) feedback. Some aspects more specifically relate to bundling HARQ feedback for downlink transmissions to reduce or avoid instances of collisions between the HARQ feedback and downlink transmissions. In some examples, a user equipment (UE) may receive a first downlink transmission from a base station, such as a semi-persistently scheduled (SPS) downlink transmission. The UE may generate first HARQ feedback associated with the first downlink transmission. In some examples, the UE may receive a downlink control information (DCI) message from the base station indicating a second downlink transmission that conflicts with (or “overlaps” with) transmission of the first HARQ feedback to the base station. According to some aspects, the UE may defer the transmission of the first HARQ feedback until after the second downlink transmission and may subsequently bundle the first HARQ feedback with second HARQ feedback associated with the second downlink transmission.

[0057] Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, the described techniques can be used to reduce or avoid collision of signals that may result in lost messages or retransmission of the signals. For example, by deferring transmission of the first HARQ feedback, the UE may avoid collision between the first HARQ feedback and the second downlink transmission. Reducing or avoiding collisions may reduce or avoid instances of lost messages or signal retransmissions, improving performance as compared to some techniques that transmit HARQ feedback according to a just-in-time basis, which may result in a collision in some cases.

[0058] Figure 3 is a block diagram of an example wireless communication system 300 that supports HARQ feedback bundling according to one or more aspects of the disclosure. In some examples, the wireless communication system 300 may implement aspects of the wireless network 100. The wireless communication system 300 includes the UE 115 and the base station 105. Although one UE 115 and one base station 105 are illustrated, in some other implementations, the wireless communication system 300 may generally include multiple UEs 115, and may multiple base stations 105, or both.

[0059] The UE 115 may include one or more processors 302 (hereinafter referred to collectively as “the processor 302”), one or more memory devices 304 (hereinafter referred to collectively as “the memory 304”), one or more transmitters 316 (hereinafter referred to collectively as “the transmitter 316”), and one or more receivers 318 (hereinafter referred to collectively as “the receiver 318”). The processor 302 may execute instructions stored in the memory 304 to perform one or more operations described herein. In some implementations, the processor 302 includes or corresponds to one or more of the receive processor 258, the transmit processor 264, or the controller 280, and the memory 304 includes or corresponds to the memory 282.

[0060] The transmitter 316 may transmit reference signals, control information, and data to one or more other devices, and the receiver 318 may receive references signals, synchronization signals, control information and data from one or more other devices. For example, the transmitter 316 may transmit signaling, control information, and data to the base station 105, and the receiver 318 may receive signaling, control information, and data from the base station 105. In some implementations, the transmitter 316 and the receiver 318 may be integrated in one or more transceivers. Additionally or alternatively, the transmitter 316 or the receiver 318 may include or correspond to one or more components of the UE 115 described with reference to Figure 2.

[0061] The base station 105 may include one or more processors 352 (hereinafter referred to collectively as “the processor 352”), one or more memory devices 354 (hereinafter referred to collectively as “the memory 354”), one or more transmitters 356 (hereinafter referred to collectively as “the transmitter 356”), and one or more receivers 358 (hereinafter referred to collectively as “the receiver 358”). The processor 352 may execute instructions stored in the memory 354 to perform one or more operations described herein. In some implementations, the processor 352 includes or corresponds to one or more of the receive processor 238, the transmit processor 220, and the controller 240, and the memory 354 includes or corresponds to the memory 242.

[0062] The transmitter 356 may transmit reference signals, synchronization signals, control information, and data to one or more other devices, and the receiver 358 may receive reference signals, control information, and data from one or more other devices. For example, the transmitter 356 may transmit signaling, control information, and data to the UE 115, and the receiver 358 may receive signaling, control information, and data from the UE 115. In some implementations, the transmitter 356 and the receiver 358 may be integrated in one or more transceivers. Additionally or alternatively, the transmitter 356 or the receiver 358 may include or correspond to one or more components of base station 105 described with reference to Figure 2.

[0063] In some implementations, the wireless communication system 300 implements a 5G New Radio (NR) network. For example, the wireless communication system 300 may include multiple 5G-capable UEs 115 and multiple 5G-capable base stations 105, such as UEs and base stations configured to operate in accordance with a 5G NR network protocol such as that defined by the 3 GPP.

[0064] During operation of the wireless communication system 300, the UE 115 may receive transmissions from the base station 105. For example, some transmissions from the base station 105 may be performed based on semi-persistent schedule (SPS). Some other transmissions from the base station 105 may be transmitted using a dedicated grant (DG). To further illustrate, the example of Figure 3 illustrates that the base station 105 may transit a first downlink transmission 334 and a second downlink transmission 342 to the UE 115. In some examples, the first downlink transmission 334 may be semi-persistently scheduled by the base station 105, and the second downlink transmission 342 may be scheduled by the base station 105 using a dedicated grant. In some implementations, the base station 105 may transmit a downlink control information (DCI) message 338 to the UE 115 indicating scheduling of the second downlink transmission 342. For example, prior to transmitting the second downlink transmission 342, the base station 105 may transmit the DCI message 338 to the UE 115 to indicate resources to be used by the UE 115 to receive the second downlink transmission 342. In some examples, the DCI message 338 has a DCI 1 1 format.

[0065] The UE 115 may generate first HARQ feedback 324 associated with the first downlink transmission 334 and may generate second HARQ feedback 328 associated with the second downlink transmission 342. In some examples, the first HARQ feedback 324 includes one or more acknowledgements (ACKs) associated with the first downlink transmission 334, one or more negative-acknowledgements (NACKs) associated with the first downlink transmission 334, or a combination thereof. The second HARQ feedback 328 may include one or more ACKs associated with the second downlink transmission 342, one or more NACKs associated with the second downlink transmission 342, or a combination thereof. In some examples, the first downlink transmission 334 is associated with a first number of HARQ processes 322 executed by the UE 115, the second downlink transmission is associated with a second number of HARQ processes 326 associated with the second downlink transmission 342.

[0066] In some examples, the first HARQ feedback 324 and the second HARQ feedback 328 are based on a HARQ codebook. For example, determining the first HARQ feedback 324 and the second HARQ feedback 328 may include accessing a HARQ codebook, such as a type-3 HARQ codebook or a modified type-3 HARQ codebook. The modified type-3 HARQ codebook may be indicated using a modified DCI 1 1 message, such as the DCI message 338. In some examples, the modified DCI 1 1 message may exclude a new data indicator (NDI) field, which may be included in certain other DCI 1 1 messages. By excluding the NDI field, the UE 115 may avoid flushing one or more buffers, which may enable the UE 115 to defer transmitting HARQ feedback. To illustrate, upon receiving the DCI message 338, the UE 115 may determine HARQ process identifiers (IDs) (also referred to herein as HARQ IDs) associated with the DCI message 338 and may avoid flushing a buffer associated with HARQ process identifiers (IDs), which may enable the UE 115 to defer providing HARQ feedback associated with the HARQ process IDs.

[0067] In some examples, the base station 105 may use a particular bit (such as a second bit 341) to indicate whether the network requests feedback for all SPS configurations associated with a HARQ ID or for a particular SPS configuration associated with the HARQ ID, such as an SPS configuration associated with the DCI message 338. To illustrate, in some implementations, multiple SPS configurations associated with the UE 115 may be associated with one or more common HARQ IDs (such as due to a limited number of available HARQ IDs). In some such examples, the second bit 341 may indicate whether the UE 115 is to report deferred HARQ feedback associated with the one or more common HARQ IDs for all SPS configurations or for the particular SPS configuration associated with the DCI message 338. As an illustrative example, a first SPS configuration associated with the first downlink transmission 334 may be associated with one or more common HARQ IDs as a second SPS configuration associated with another downlink transmission. In such examples, the second bit 341 may indicate whether the bundled HARQ feedback message 344 is to include deferred HARQ feedback associated with only the first SPS configuration (such as the first HARQ feedback 324) or deferred HARQ feedback associated with both the first SPS configuration and the second SPS configuration. In some implementations, a particular window may be used to determine which HARQ feedback for multiple SPS configurations is to be included in the bundled HARQ feedback message 344 (where deferred HARQ feedback generated within the window is included in the bundled HARQ feedback message 344 and where deferred HARQ feedback generated outside the window is excluded from the bundled HARQ feedback message 344). In such examples, the second bit 341 may indicate whether the bundled HARQ feedback message 344 is to include, for multiple SPS configurations or for an SPS configuration associated with the DCI message 338, HARQ feedback generated within the particular window. Further, in some examples, a particular HARQ ID may include bits associated with multiple SPS configurations, and the DCI message 338 may indicate the number M of the SPS configurations per HARQ ID that are to be reported via the bundled HARQ feedback message 344 (where M indicates a positive integer). [0068] In some circumstances, transmission of the first HARQ feedback 324 to the base station 105 may conflict with the second downlink transmission 342. For example, transmission of the first HARQ feedback 324 may be associated with first resources (such as where the first resources are based on a processing time of the UE 115 to generate the first HARQ feedback 324). If the DCI message 338 indicates that the second downlink transmission 342 is associated with second resources that overlap with the first resources (such as if the second resources include at least one of the first resources), then the UE 115 may detect a resource conflict between the transmission of the first HARQ feedback 324 and the second downlink transmission 342. In some other examples, if the first resources are distinct from (and do not overlap with) the second resources, then the UE 115 may determine that no resource conflict is present between the transmission of the first HARQ feedback 324 and the second downlink transmission 342.

[0069] In some aspects of the disclosure, based on detecting a resource conflict between the transmission of the first HARQ feedback 324 and the second downlink transmission 342, the UE 115 may defer the transmission of the first HARQ feedback 324 until after the second downlink transmission 342. For example, after receiving the second downlink transmission 342, the UE 115 may transmit a bundled HARQ feedback message 344 that includes the first HARQ feedback 324 and the second HARQ feedback 328. The UE 115 may transmit the bundled HARQ feedback message 344 at least X milliseconds (ms) (where X indicates a positive number) after receiving the second downlink transmission 342. In some examples, X indicates a processing time for the UE 115 to determine the second HARQ feedback 328) and to prepare the bundled HARQ feedback message 344. In some implementations, X may correspond to T_proc2, where T_proc2 indicates the time difference between arrival of the second downlink transmission 342 and transmission of the bundled HARQ feedback message 344.

[0070] In some examples, the UE 115 transmits the bundled HARQ feedback message 344 based on third resources that are distinct from the first resources and the second resources. In some implementations, the third resources are based on a processing time of the UE 115 to generate the second HARQ feedback 328. In some examples, the bundled HARQ feedback message 344 includes a third number of bits that corresponds to a sum of the first number of the HARQ processes 322 and the second number of the HARQ processes 326. In some examples, the DCI message 338 includes an indication of the third resources.

[0071] In some examples, bundling of HARQ feedback messages (such as via the bundled HARQ feedback message 344) may be enabled or disabled within the wireless communication system 300, such as via a configuration message 330. In some examples, the configuration message 330 has a radio resource control (RRC) format. The configuration message 330 may include a HARQ feedback bundling indication that indicates that the first HARQ feedback 324 is to be bundled with the second HARQ feedback 328 based on one or more the first resources overlapping one or more of the second resources. In some examples, the base station 105 may transmit the configuration message 330 prior to transmitting the DCI message 338 (and the second downlink transmission 342).

[0072] As described above, the number of SPS configurations for which HARQ feedback is to be bundled may be specified in the DCI message 338. Further, the DCI message 338 may include the second bit 341 indicating whether feedback for all SPS configurations, or only for the deferred SPS configurations, is to be transmitted in the bundled HARQ feedback message 344.

[0073] In some implementations, after receiving the configuration message 330, the UE 115 automatically bundles the first HARQ feedback 324 and the second HARQ feedback 328 based on a resource conflict between the transmission of the first HARQ feedback 324 and the second downlink transmission 342. The UE 115 may perform automatic bundling based on the first HARQ feedback 324 being generated at least X ms prior to generating the second HARQ feedback 328. Further, the UE 115 may automatically bundle the first HARQ feedback 324 and the second HARQ feedback 328 within the bundled HARQ feedback message 344 based on failing to receive, within a threshold time interval prior to transmitting the bundled HARQ feedback message 344 (such as X ms prior to transmitting the bundled HARQ feedback message 344), an indication of third deferred HARQ feedback (such as another DCI message or another downlink transmission that may be associated with deferred HARQ feedback). Alternatively, if the UE 115 receives such an indication, the UE 115 may further defer transmission of the bundled HARQ feedback message 344 until X ms after receiving the indication (to enable bundling of the third deferred HARQ feedback with the first HARQ feedback 324 and with the second HARQ feedback 328). In such examples, the DCI message 338 may exclude an explicit indication (such as a first bit 340) of whether the first HARQ feedback 324 is to be bundled with the second HARQ feedback 328 (because the UE 115 may perform bundling automatically).

[0074] In some other implementations, the DCI message 338 incudes the first bit 340 to indicate whether the first HARQ feedback 324 is to be bundled with the second HARQ feedback 328. To illustrate, the first bit 340 may have one of a first value (such as a logic one value or a logic zero value) or a second value (such as a logic zero value or a logic one value) that are selectable by the base station 105. The first value may indicate that the first HARQ feedback 324 is to be bundled with the second HARQ feedback 328 based on a resource conflict between the first HARQ feedback 324 and the second downlink transmission 342. The second value may indicate that the UE 115 is to refrain from bundling the first HARQ feedback 324 with the second HARQ feedback 328. In some examples, the first bit 340 may enable the base station 105 to request selectively retransmission of HARQ feedback, such as described further with reference to one or more aspects of Figure 4.

[0075] Figure 4 is a timing diagram illustrating example timing of operations that may be performed to support HARQ feedback bundling according to some aspects of the disclosure. In Figure 4, a first available time for transmitting the first HARQ feedback 324 (which may be based on a processing time of the UE 115 to generate the first HARQ feedback 324) may correspond to first resources 402 (such as a first set of symbols). The first resources 402 may be included in or may overlap with second resources 404 (such as a second set of symbols) associated with the second downlink transmission 342. The UE 115 may defer transmission of the first HARQ feedback 324 (instead of transmitting the first HARQ feedback 324 based on the first resources 402) and may transmit the first HARQ feedback 324 using the bundled HARQ feedback message 344 based on third resources 408 (such as third set of symbols). Various communications illustrated in Figure 4 may be transmitted using a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), one or more other channels, or a combination thereof. For example, the first downlink transmission 334 and the second downlink transmission 342 may be performed via the PDSCH, and the bundled HARQ feedback message 344 may be transmitted via the PUCCH. [0076] Figure 4 depicts certain illustrative examples of cycles (such as a cycle 450) and slots (such as a slot 452). In some examples, a cycle may include a number of symbols (such as 112 symbols), and a slot may include another number of symbols (such as fourteen symbols). In some examples, a cycle has a duration corresponding to one millisecond and to one-hundred and twelve symbols and may include eight slots each including fourteen symbols. In some implementations, the first downlink transmission 334 may occupy a mini-slot of two symbols, and the second downlink transmission 342 may occupy a mini-slot of seven symbols. In some examples, a slot may include one or more downlink symbols (such as three downlink symbols), one or more uplink symbols (such as three uplink symbols), and one or more “flexible” symbols (such as eight flexible symbols) that can be configured for uplink or downlink communications. In some circumstances, conversation of slots from uplink to downlink communications (or vice versa) may create a resource conflict, such as any of the resource conflicts described herein. As an example, conversion of a flexible slot from an SPS PUCCH HARQ feedback format to a DG PDSCH format may create a resource conflict between the between the first HARQ feedback 324 and the second downlink transmission 342, as described above. In this case, the UE 115 may perform bundling of the first HARQ feedback 324 and the second downlink transmission 342 to avoid a collision of the first HARQ feedback 324 and the second downlink transmission 342.

[0077] Further, in some circumstances, an error event may occur that causes a device to fail to receive one or more communications. As an example, in some circumstances, the UE 115 may receive, from the base station 105, a third downlink transmission and may generate third HARQ feedback based on the reception of the third downlink transmission. If the UE 115 fails to receive, from the base station 105, a second DCI message indicating a fourth downlink transmission associated with time resources that overlap time resources associated with transmission of the third HARQ feedback, then the UE may transmit, to the base station 105, the third HARQ feedback during the fourth downlink transmission (instead of deferring the transmission of the third HARQ feedback), resulting in an error event. Further, due to transmitting the third HARQ feedback during the fourth downlink transmission, the UE 115 may fail to receive the fourth downlink transmission from the base station 105, and the base station 105 may fail to receive the third HARQ feedback. In some aspects, the base station 105 may transmit a third DCI message scheduling a retransmission of the fourth downlink transmission. In some examples, the second DCI message includes the first bit 340 having the second value indicating that the third HARQ feedback is not to be bundled. The UE 115 may receive, from the base station 105 based on the second DCI message, the retransmission of the fourth downlink transmission and may generate fourth HARQ feedback based on the reception of the fourth downlink transmission. The UE 115 may transmit, to the base station 105, the fourth HARQ feedback based on the retransmission of the fourth downlink transmission.

[0078] Further, the base station 105 may separately schedule retransmission of the third HARQ feedback. For example, the base station 105 may transmit a fourth DCI message requesting the third HARQ feedback. Based on the fourth DCI message, the UE 115 may retransmit the third HARQ feedback to the base station 105. In some implementations, the UE 115 may store HARQ feedback for a threshold time interval prior to discarding the HARQ feedback. In this case, if the base station 105 requests retransmission of the third HARQ feedback prior to expiration of the threshold time interval, the UE 115 may access the stored third HARQ feedback for the retransmission. The threshold time interval may correspond to or may be based on an expiration time associated with the third downlink transmission. To illustrate, the UE 115 may store the third HARQ feedback until an expiration time associated with the third downlink transmission. Based on receiving, prior to the expiration time, the fourth DCI message requesting retransmission the third HARQ feedback, the UE 115 may access the stored third HARQ feedback and may retransmit the third HARQ feedback to the base station 105.

[0079] As another example of an error event, in some circumstances, the base station 105 may fail to receive the bundled HARQ feedback message 344, such as due to noise, interference, or another condition that may be present in the wireless communication system 300. In some such examples, the base station 105 may transmit a second DCI message requesting retransmission of the second downlink transmission 342. The second DCI may include the first bit 340 having the second value indicating that the first HARQ feedback 324 is not to be bundled (such as with the second HARQ feedback 328 or with another HARQ feedback message). Based on the second DCI message, the UE 115 may receive the retransmission of the second downlink transmission 342 from the base station 105 and may retransmit the second HARQ feedback 328 to the base station 105 based on the retransmission of the second downlink transmission 342. [0080] Further, the base station 105 may separately schedule retransmission of the first HARQ feedback 324. For example, the base station 105 may transmit a third DCI message requesting the first HARQ feedback 324. Based on the third DCI message, the UE 115 may retransmit the first HARQ feedback 324 to the base station 105. In some implementations, the UE 115 may store HARQ feedback for a threshold time interval prior to discarding the HARQ feedback. In this case, if the base station 105 requests retransmission of the first HARQ feedback 324 prior to expiration of the threshold time interval, the UE 115 may access the stored first HARQ feedback 324 for the retransmission. The threshold time interval may correspond to or may be based on an expiration time associated with the first downlink transmission 334. To illustrate, the UE 115 may store the first HARQ feedback 324 until an expiration time associated with the first downlink transmission 334. Based on receiving, prior to the expiration time, the third DCI message requesting retransmission the first HARQ feedback 324, the UE 115 may access the stored first HARQ feedback 324 and may retransmit the first HARQ feedback 324 to the base station 105.

[0081] In some examples, inclusion of the first bit 340 and the second bit 341 in DCI messages (such as the DCI message 338) may be determined based on the particular application. In some implementations, inclusion of the first bit 340 may increase flexibility by enabling separate retransmission of different HARQ feedbacks in the case of an error event, such as separate retransmission of the first HARQ feedback 324 and the second HARQ feedback 328. In some other implementations, one or both of the first bit 340 or the second bit 341 may be omitted from DCI messages (such as the DCI message 338) to reduce DCI overhead. Further, a DCI message (such as the DCI message 338) may include an indication of a number of SPS configurations per HARQ ID to be reported with a bundled HARQ feedback message (such as the bundled HARQ feedback message 344), or such an indication may be omitted. Additionally, a DCI message (such as the DCI message 338) may include an indication of whether HARQ feedback is to be reported for all SPS configurations or for SPS configurations associated with the DCI message, or such an indication may be omitted.

[0082] To further illustrate, some wireless communication protocols may be associated with relatively high reliability, in which case error events may be relatively unlikely, such as in the case of a wireless communication protocol that complies with an ultrareliable low-latency communication (URLLC) technique. In one example, the DCI message 338 excludes the first bit 340, and the base station 105 and the UE 115 operate based on a wireless communication protocol that complies with a URLLC technique.

[0083] In some circumstances, the UE 115 may determine that the third resources 408 occur at least X ms after receiving the second downlink transmission 342. In this case, the UE 115 may bundle the second HARQ feedback 328 with the first HARQ feedback 324 (such as using the bundled HARQ feedback message 344). In some examples, the UE 115 may determine that other resources 406 do not occur at least X ms after receiving the second downlink transmission 342 (in which case the second HARQ feedback 328 may not yet be available for transmission). In this case, the UE 115 may defer transmission of the first HARQ feedback 324 until the second HARQ feedback 328 is available for bundling with the first HARQ feedback 324.

[0084] Figure 5 is a flow diagram illustrating an example process 500 that supports HARQ feedback bundling according to one or more aspects. Operations of the process 500 (also referred to as “blocks”) may be performed by a UE, such as the UE 115.

[0085] In block 502, the UE receives, from a base station, a first downlink transmission. For example, the UE 115 may receive the first downlink transmission 334 from the base station 105.

[0086] In block 504, the UE generates first HARQ feedback based on the reception of the first downlink transmission. For example, the UE 115 may generate the first HARQ feedback 324 based on reception of the first downlink transmission 334.

[0087] In block 506, the UE receives, from the base station prior to transmission of the first feedback, a DCI message indicating a second downlink transmission. For example, the UE 115 may receive the DCI message 338 indicating the second downlink transmission 342.

[0088] In block 508, the UE may determine, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. For example, the UE 115 may determine, based on the DCI message 338, that one or more of the first resources 402 overlap one or more of the second resources 404.

[0089] In block 510, the UE defers, based on the one or more first resources overlapping the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. For example, based on determining that one or more of the first resources 402 overlap one or more of the second resources 404, the UE 115 may defer transmission of the first HARQ feedback 324 until after the second downlink transmission 342.

[0090] In block 512, the UE receives, from the base station, the second downlink transmission in the one or more second resources. For example, the UE 115 may receive, from the base station 105, the second downlink transmission 342 in the second resources 404.

[0091] In block 514, the UE generates second HARQ feedback based on the reception of the second downlink transmission. For example, the UE 115 may generate the second HARQ feedback 328 based on the reception of the second downlink transmission 342.

[0092] In block 516, the UE transmits, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback. For example, the UE 115 may transmit, to the base station 105 in the third resources 408, the bundled HARQ feedback message 344 including the first HARQ feedback 324 and the second HARQ feedback 328.

[0093] Figure 6 is a flow diagram illustrating an example process 600 that supports HARQ feedback bundling according to one or more aspects. Operations of the process 600 (also referred to as “blocks”) may be performed by a base station, such as the base station 105.

[0094] In block 602, the base station transmits, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. For example, the base station 105 may transmit the first downlink transmission 334 to the UE 115, and the UE 115 may generate the first HARQ feedback 324 based on reception of the first downlink transmission 334.

[0095] In block 604, the base station transmits, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. For example, the base station 105 may transmit, to the UE 115 prior to transmission of the first HARQ feedback 324, the DCI message 338 indicating the second downlink transmission 342. One or more of the first resources 402 associated with the first downlink transmission 334 may overlap one or more of the second resources 404 associated with the second downlink transmission 342.

[0096] In block 606, the base station transmits, to the UE, the second downlink transmission in the one or more second resources. For example, the base station 105 may transmit the second downlink transmission 342 to the UE 115 in the second resources 404.

[0097] In block 608, the base station receives, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission. For example, the base station 105 may receive, from the UE 115 in the third resources 408, the bundled HARQ feedback message 344 including the first HARQ feedback 324 and the second HARQ feedback 328.

[0098] Figure 7 is a block diagram of an example UE 115 that supports HARQ feedback bundling according to one or more aspects. The UE 115 may be configured to perform operations, including the blocks of the process 500 described with reference to Figure 5. In some implementations, the UE 115 includes the structure, hardware, and components shown and described with reference to the UE 115 of Figures 2 or 3. For example, the UE 115 includes the controller 280, which operates to execute logic or computer instructions stored in the memory 282, as well as controlling the components of the UE 115 that provide the features and functionality of the UE 115. The UE 115, under control of the controller 280, transmits and receives signals via wireless radios 701a-r and the antennas 252a-r. The wireless radios 701a-r may include various components and hardware, as illustrated in Figure 2 for the UE 115, such as one or more of the modulator and demodulators 254a-r, the MIMO detector 256, the receive processor 258, the transmit processor 264, or the TX MIMO processor 266.

[0099] The memory 282 may store resource overlap detection instructions 702. The controller 280 may execute the resource overlap detection instructions 702 to detect an overlap between resources of transmissions indicating a resource conflict, such as to detect that one or more of the first resources 402 overlap one or more of the second resources 404. The memory 282 may store HARQ feedback bundling instructions 704. The controller 280 may execute the HARQ feedback bundling instructions 704 to defer transmission of the first HARQ feedback 324 and to bundle the first HARQ feedback 324 with the second HARQ feedback 328 in a message, such as the bundled HARQ feedback message 344.

[00100] Figure 8 is a block diagram of an example base station 105 that supports HARQ feedback bundling according to one or more aspects. The base station 105 may be configured to perform operations, including the blocks of the process 600 described with reference to Figure 6. In some implementations, the base station 105 includes the structure, hardware, and components shown and described with reference to the base station 105 of Figures 1-3. For example, the base station 105 may include the controller 240, which operates to execute logic or computer instructions stored in the memory 242, as well as controlling the components of the base station 105 that provide the features and functionality of the base station 105. The base station 105, under control of the controller 240, transmits and receives signals via wireless radios 801a-t and the antennas 234a-t. The wireless radios 801a-t may include various components and hardware, as illustrated in Figure 2 for the base station 105, such as one or more of the modulator and demodulators 232a-t, the transmit processor 220, the TX MIMO processor 230, the MIMO detector 236, or the receive processor 238.

[00101] The memory 242 may store HARQ bundling configuration instructions 802. The controller 240 may execute the HARQ bundling configuration instructions 802 to initiate transmission of the configuration message 330 to the UE 115. In some implementations, the memory 242 may store HARQ bundling activation instructions 804, and the controller 240 may execute the HARQ bundling activation instructions 804 to determine a value of the first bit 340.

[00102] In a first aspect, a method for wireless communication performed by a UE includes receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The method further includes receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The method further includes deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The method further includes receiving, from the base station, the second downlink transmission in the one or more second resources, generating second HARQ feedback based on the reception of the second downlink transmission, and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00103] In a second aspect, alone or in combination with the first aspect, the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

[00104] In a third aspect, alone or in combination with one or more of the first aspect or second aspects, the method includes, prior to receiving the DCI message, receiving a configuration message from the base station including a HARQ feedback bundling indication.

[00105] In a fourth aspect, alone or in combination with one or more of the first aspect through third aspects, the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00106] In a fifth aspect, alone or in combination with one or more of the first aspect through fourth aspects, the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

[00107] In a sixth aspect, alone or in combination with one or more of the first aspect through fifth aspects, the base station and the UE operate based on a wireless communication protocol that complies with a URLLC technique.

[00108] In a seventh aspect, alone or in combination with one or more of the first aspect through the sixth aspects, the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00109] In an eighth aspect, alone or in combination with one or more of the first through the seventh aspects, the method includes receiving, from a base station, a third downlink transmission; generating third HARQ feedback based on the reception of the third downlink transmission; failing to receive, from the base station, a second DCI message indicating a fourth downlink transmission; transmitting, to the base station, the third HARQ feedback during the fourth downlink transmission; based on the transmission of the third HARQ feedback, failing to receive, from the base station, the fourth downlink transmission; receiving, from the base station, a third DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including the first bit, the first bit having a second value indicating that the third HARQ feedback is not to be bundled; receiving, from the base station based on the second DCI message, the retransmission of the fourth downlink transmission; generating fourth HARQ feedback based on the reception of the fourth downlink transmission; and transmitting, to the base station, the fourth HARQ feedback based on the retransmission of the fourth downlink transmission.

[00110] In a ninth aspect, alone or in combination with one or more of the first through the eighth aspects, the method includes storing the third HARQ feedback; receiving, from the base station prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback; and retransmitting, to the base station based on the fourth DCI message, the third HARQ feedback.

[00111] In a tenth aspect, alone or in combination with one or more of the first through the ninth aspects, the method includes, based on failure of the base station to receive the message, receiving, from the base station, a second DCI message requesting retransmission of the second downlink transmission, the second DCI message including the first bit, the first bit having a second value indicating that the second HARQ feedback is not to be bundled; receiving, from the base station based on the second DCI message, the retransmission of the second downlink transmission; and retransmitting, to the base station, the second HARQ feedback based on the retransmission of the second downlink transmission.

[00112] In an eleventh aspect, alone or in combination with one or more of the first through the tenth aspects, the method includes storing the first HARQ feedback; receiving, from the base station prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback; and retransmitting, to the base station based on the third DCI message, the first HARQ feedback.

[00113] In a twelfth aspect, alone or in combination with one or more of the first through the eleventh aspect, the DCI message has a DCI 1 1 format. [00114] In a thirteenth aspect, alone or in combination with one or more of the first through the twelfth aspects, the DCI message further includes an indication of the one or more third resources.

[00115] In a fourteenth aspect, alone or in combination with one or more of the first through the thirteenth aspects, the first downlink transmission is semi-persistently scheduled by the base station.

[00116] In a fifteenth aspect, alone or in combination with one or more of the first through the fourteenth aspects, the second downlink transmission is scheduled by the base station using a dedicated grant.

[00117] In a sixteenth aspect, alone or in combination with one or more of the first through the fifteenth aspects, determining the first HARQ feedback and the second HARQ feedback includes accessing a HARQ codebook.

[00118] In a seventeenth aspect, alone or in combination with one or more of the first through the sixteenth aspects, the first downlink transmission occupies a mini-slot of two symbols and is transmitted via a PDSCH, the second downlink transmission is occupies a mini-slot of seven symbols and is transmitted via the PDSCH, and the message is transmitted via a PUCCH.

[00119] In an eighteenth aspect alternatively or in addition to any of the first through seventeenth aspects, the first downlink transmission, the second downlink transmission, and the message are transmitted during a cycle having a duration corresponding to one millisecond and to one-hundred and twelve symbols, the cycle is associated with eight slots each including fourteen symbols, and the fourteen symbols include three downlink symbols, three uplink symbols, and eight flexible symbols.

[00120] In a nineteenth aspect alternatively or in addition to any of the first through eighteenth aspects, the one or more first resources include a flexible symbol, and modification of the flexible symbol by the base station from a SPS PUCCH HARQ feedback format to a DG PDSCH) format is associated with a resource conflict between the first HARQ feedback and the second downlink transmission.

[00121] In a twentieth aspect alternatively or in addition to any of the first through nineteenth aspects, the DCI message excludes an NDI field.

[00122] In a twenty-first aspect alternatively or in addition to any of the first through twentieth aspects, the DCI message includes a second bit indicating whether the message is to include, for multiple SPS configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window.

[00123] In a twenty-second aspect alternatively or in addition to any of the first through twenty-first aspects, the DCI message indicates a number of SPS configurations per HARQ ID to be included in the message.

[00124] In a twenty-third aspect alternatively or in addition to any of the first through twenty-second aspects, the UE automatically bundles the first HARQ feedback and the second HARQ feedback within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback.

[00125] In a twenty-fourth aspect alternatively or in addition to any of the first through twenty-third aspects, a non-transitory computer-readable medium stores instructions executable by a processor to perform operations including receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The operations further include receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The operations further include deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The operations further include receiving, from the base station, the second downlink transmission in the one or more second resources, generating second HARQ feedback based on the reception of the second downlink transmission, and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00126] In a twenty-fifth aspect alternatively or in addition to any of the first through twenty-fourth aspects, a UE includes a memory and one or more processors coupled to the memory. The one or more processors are configured to receive, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The one or more processors are further configured to receive, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and to determine, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The one or more processors are further configured to defer, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The one or more processors are further configured to receive, from the base station, the second downlink transmission in the one or more second resources, to generate second HARQ feedback based on the reception of the second downlink transmission, and to transmit, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00127] In a twenty-sixth aspect alternatively or in addition to any of the first through twenty-fifth aspects, an apparatus includes means for receiving, from a base station, a first downlink transmission and generating first HARQ feedback based on the reception of the first downlink transmission. The apparatus further includes means for receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission and means for determining, based on the DCI message, that one or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The apparatus further includes means for deferring, based on the determination that the one or more first resources overlap the one or more second resources, the transmission of the first HARQ feedback until after the second downlink transmission. The apparatus further includes means for receiving, from the base station, the second downlink transmission in the one or more second resources, means for generating second HARQ feedback based on the reception of the second downlink transmission, and means for transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00128] In a twenty-seventh aspect alternatively or in addition to any of the first through twenty-sixth aspects, a method for wireless communication performed by a base station includes transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The method further includes transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The method further includes transmitting, to the UE, the second downlink transmission in the one or more second resources. The method further includes receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[00129] In a twenty-eighth aspect alternatively or in addition to any of the first through twenty-seventh aspects, the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

[00130] In a twenty-ninth aspect alternatively or in addition to any of the first through twenty-eighth aspects, the method includes, prior to transmitting the DCI message, transmitting a configuration message to the UE including a HARQ feedback bundling indication.

[00131] In a thirtieth aspect alternatively or in addition to any of the first through twentyninth aspects, the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00132] In a thirty-first aspect alternatively or in addition to any of the first through thirtieth aspects, the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

[00133] In a thirty-second aspect alternatively or in addition to any of the first through thirty-first aspects, the base station and the UE operate based on a wireless communication protocol that complies with an URLLC technique.

[00134] In a thirty-third aspect alternatively or in addition to any of the first through thirty-second aspects, the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00135] In a thirty-fourth aspect alternatively or in addition to any of the first through thirty-third aspects, the method includes transmitting, to the UE, a third downlink transmission, where the UE generates third HARQ feedback based on the reception of the third downlink transmission; transmitting, to the UE, a second DCI message indicating a fourth downlink transmission, where the UE fails to receive the second DCI message; transmitting, to the UE, the fourth downlink transmission, where the base station fails to receive, from the UE, a transmission of the third HARQ feedback during the fourth downlink transmission; transmitting, to UE, a third DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including the first bit, the first bit having a second value indicating that the third HARQ feedback is not to be bundled; transmitting, to the UE, the retransmission of the fourth downlink transmission; and receiving, from the UE, fourth HARQ feedback based on the reception of the fourth downlink transmission.

[00136] In a thirty-fifth aspect alternatively or in addition to any of the first through thirty-fourth aspects, the method includes transmitting, to the UE prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback; and receiving, from the UE, the third HARQ feedback.

[00137] In a thirty-sixth aspect alternatively or in addition to any of the first through thirty-fifth aspects, the method includes, based on failure of the base station to receive the message, transmitting, to the UE, a second DCI message requesting retransmission of the second downlink transmission, the second DCI message including the first bit, the first bit having a second value indicating that the second HARQ feedback is not to be bundled; transmitting, to the UE, the retransmission of the second downlink transmission; and receiving, from the UE, the second HARQ feedback based on the retransmission of the second downlink transmission.

[00138] In a thirty-seventh aspect alternatively or in addition to any of the first through thirty-sixth aspects, the method includes transmitting, to the UE prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback; and receiving, from the UE, the first HARQ feedback.

[00139] In a thirty-eighth aspect alternatively or in addition to any of the first through thirty-seventh aspects, the DCI message has a DCI 1 1 format.

[00140] In a thirty-ninth aspect alternatively or in addition to any of the first through thirty-eighth aspects, the DCI message further includes an indication of the one or more third resources. [00141] In a fortieth aspect alternatively or in addition to any of the first through thirtyninth aspects, the first downlink transmission is semi-persistently scheduled by the base station.

[00142] In a forty-first aspect alternatively or in addition to any of the first through fortieth aspects, the second downlink transmission is scheduled by the base station using a dedicated grant.

[00143] In a forty-second aspect alternatively or in addition to any of the first through forty-first aspects, the first HARQ feedback and the second HARQ feedback are based on a HARQ codebook.

[00144] In a forty-third aspect alternatively or in addition to any of the first through forty-second aspects, the first downlink transmission occupies a mini-slot of two symbols and is transmitted via a PDSCH, the second downlink transmission occupies a mini-slot of seven symbols and is transmitted via the PDSCH, and the message is transmitted via a PUCCH.

[00145] In a forty-fourth aspect alternatively or in addition to any of the first through forty-third aspects, the first downlink transmission, the second downlink transmission, and the message are transmitted during a cycle having a duration corresponding to one millisecond and to one-hundred and twelve symbols, the cycle is associated with eight slots each including fourteen symbols, the fourteen symbols include three downlink symbols, three uplink symbols, and eight flexible symbols.

[00146] In a forty-fifth aspect alternatively or in addition to any of the first through fortyfourth aspects, the one or more first resources include a flexible symbol, and modification of the flexible symbol by the base station from a SPS PUCCH HARQ feedback format to a DG PDSCH format is associated with a resource conflict between the first HARQ feedback and the second downlink transmission.

[00147] In a forty-sixth aspect alternatively or in addition to any of the first through forty-fifth aspects, the DCI message excludes an NDI field.

[00148] In a forty-seventh aspect alternatively or in addition to any of the first through forty-sixth aspects, the DCI message includes a second bit indicating whether the message is to include, for multiple SPS configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window. [00149] In a forty-eighth aspect alternatively or in addition to any of the first through forty-seventh aspects, the DCI message indicates a number of SPS configurations per HARQ ID to be included in the message.

[00150] In a forty-ninth aspect alternatively or in addition to any of the first through forty-eighth aspects, the UE automatically bundles the first HARQ feedback and the second HARQ feedback within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback.

[00151] In a fiftieth aspect alternatively or in addition to any of the first through fortyninth aspects, a non-transitory computer-readable medium stores instructions executable by a processor to perform operations. The operations include transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The operations further include transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The operations further include transmitting, to the UE, the second downlink transmission in the one or more second resources. The operations further include receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[00152] In a fifty-first aspect alternatively or in addition to any of the first through fiftieth aspects, a base station includes a memory and one or more processors coupled to the memory. The one or more processors are configured to transmit, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The one or more processors are further configured to transmit, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The one or more processors are further configured to transmit, to the UE, the second downlink transmission in the one or more second resources. The one or more processors are further configured to receive, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[00153] In a fifty-second aspect alternatively or in addition to any of the first through fifty-first aspects, an apparatus includes means for transmitting, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The apparatus further includes means for transmitting, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. One or more first resources associated with the transmission of the first HARQ feedback overlap one or more second resources associated with the second downlink transmission. The apparatus further includes means for transmitting, to the UE, the second downlink transmission in the one or more second resources. The apparatus further includes means for receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[00154] In a fifty-third aspect, a UE includes at least one processor and at least one memory storing code that, when executed by the at least one processor, is configured to cause the UE to receive, from a base station, a first downlink transmission, to generate first HARQ feedback based on the reception of the first downlink transmission, and to receive, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. The at least one processor is further configured to defer, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission and to receive, from the base station, the second downlink transmission in the one or more second resources. The at least one processor is further configured to generate second HARQ feedback based on the reception of the second downlink transmission and to transmit, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00155] In a fifty-fourth aspect alternatively or in addition to the fifty-third aspect, the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

[00156] In a fifty-fifth aspect alternatively or in addition to one or more of the fifty-third through fifty-fourth aspects, the at least one processor is further configured to receive, prior to receiving the DCI message, a configuration message from the base station including a HARQ feedback bundling indication, and the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled based on the one or more first resources overlapping the one or more second resources.

[00157] In a fifty-sixth aspect alternatively or in addition to one or more of the fifty-third through fifty-fifth aspects, the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

[00158] In a fifty-seventh aspect alternatively or in addition to one or more of the fifty- third through fifty-sixth aspects, the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00159] In a fifty-eighth aspect alternatively or in addition to one or more of the fifty- third through fifty-seventh aspects, the at least one processor is further configured to receive, from a base station, a third downlink transmission, to generate third HARQ feedback based on the reception of the third downlink transmission, and to transmit, to the base station, the third HARQ feedback during a fourth downlink transmission. The at least one processor is further configured to receive, from the base station, a second DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including a first bit having a second value indicating that the third HARQ feedback is not to be bundled, and to receive, from the base station, the retransmission of the fourth downlink transmission. The at least one processor is further configured to generate fourth HARQ feedback based on the reception of the fourth downlink transmission and to transmit, to the base station, a message in one or more fourth resources that includes the fourth HARQ feedback and that does not include the third HARQ feedback based on the second value indicating that the third HARQ feedback is not to be bundled.

[00160] In a fifty-ninth aspect alternatively or in addition to one or more of the fifty -third through fifty-eighth aspects, the at least one processor is further configured to store the third HARQ feedback, to receive, from the base station prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback, and to transmit, to the base station based on the fourth DCI message, the third HARQ feedback.

[00161] In a sixtieth aspect alternatively or in addition to one or more of the fifty-third through fifty-ninth aspects, the at least one processor is further configured to, based on failure of the base station to receive the message, receive, from the base station, a second DCI message scheduling retransmission of the second downlink transmission, the second DCI message including a first bit having a second value indicating that the second HARQ feedback is not to be bundled. The at least one processor is further configured to receive, from the base station based on the second DCI message, the retransmission of the second downlink transmission and to retransmit, to the base station, a message including the second HARQ feedback and excluding the first HARQ feedback based on the retransmission of the second downlink transmission.

[00162] In a sixty-first aspect alternatively or in addition to one or more of the fifty-third through sixtieth aspects, the at least one processor is further configured to store, after generating the first HARQ feedback and prior to receiving the second DCI message, the first HARQ feedback, to receive, from the base station after retransmitting the message and prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback, and to retransmit, to the base station based on the third DCI message, the first HARQ feedback.

[00163] In a sixty-second aspect alternatively or in addition to one or more of the fifty- third through sixty-first aspects, the DCI message further includes an indication of the one or more third resources.

[00164] In a sixty -third aspect alternatively or in addition to one or more of the fifty -third through sixty-second aspects, the first downlink transmission is semi-persistently scheduled by the base station.

[00165] In a sixty-fourth aspect alternatively or in addition to one or more of the fifty- third through sixty-third aspects, the second downlink transmission is scheduled by the base station using a dedicated grant.

[00166] In a sixty-fifth aspect alternatively or in addition to one or more of the fifty-third through sixty-fourth aspects, the DCI message includes a second bit indicating whether the message is to include, for multiple SPS configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window, and the at least one processor is further configured to transmit the message based on receiving the first HARQ feedback and the second HARQ feedback within the particular window.

[00167] In a sixty-sixth aspect alternatively or in addition to one or more of the fifty- third through sixty-fifth aspects, the DCI message indicates a number of SPS configurations per HARQ ID to be included in the message.

[00168] In a sixty-seventh aspect alternatively or in addition to one or more of the fifty- third through sixty-sixth aspects, the at least one processor is further configured to bundle the first HARQ feedback and the second HARQ feedback within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback that is to be bundled with one or more of the first HARQ feedback or the second HARQ feedback.

[00169] In a sixty-eighth aspect, a method for wireless communication performed by UE includes receiving, from a base station, a first downlink transmission, generating first HARQ feedback based on the reception of the first downlink transmission, and receiving, from the base station prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission. The method further includes deferring, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission and receiving, from the base station, the second downlink transmission in the one or more second resources. The method further includes generating second HARQ feedback based on the reception of the second downlink transmission and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

[00170] In a sixty-ninth aspect alternatively or in addition to the sixty-eighth aspect, the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

[00171] In a seventieth aspect alternatively or in addition to one or more of the sixtyeighth through sixty-ninth aspects, the method further includes receiving, prior to receiving the DCI message, a configuration message from the base station including a HARQ feedback bundling indication, and the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled based on the one or more first resources overlapping the one or more second resources.

[00172] In a seventy-first aspect alternatively or in addition to one or more of the sixtyeighth through seventieth aspects, the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

[00173] In a seventy-second aspect alternatively or in addition to one or more of the sixty-eighth through seventy -first aspects, the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

[00174] In a seventy-third aspect alternatively or in addition to one or more of the sixtyeighth through seventy-second aspects, the method further includes receiving, from a base station, a third downlink transmission, generating third HARQ feedback based on the reception of the third downlink transmission, and transmitting, to the base station, the third HARQ feedback during a fourth downlink transmission. The method further includes receiving, from the base station, a second DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including a first bit having a second value indicating that the third HARQ feedback is not to be bundled and receiving, from the base station, the retransmission of the fourth downlink transmission. The method further includes generating fourth HARQ feedback based on the reception of the fourth downlink transmission and transmitting, to the base station, a message in one or more fourth resources that includes the fourth HARQ feedback and that does not include the third HARQ feedback based on the second value indicating that the third HARQ feedback is not to be bundled.

[00175] In a seventy -fourth aspect alternatively or in addition to one or more of the sixtyeighth through seventy-third aspects, the method further includes storing the third HARQ feedback, receiving, from the base station prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback, and transmitting, to the base station based on the fourth DCI message, the third HARQ feedback. [00176] In a seventy-fifth aspect alternatively or in addition to one or more of the sixtyeighth through seventy-fourth aspects, the method further includes, based on failure of the base station to receive the message, receiving, from the base station, a second DCI message scheduling retransmission of the second downlink transmission, the second DCI message including a first bit having a second value indicating that the second HARQ feedback is not to be bundled. The method further includes receiving, from the base station based on the second DCI message, the retransmission of the second downlink transmission and retransmitting, to the base station, a message including the second HARQ feedback and excluding the first HARQ feedback based on the retransmission of the second downlink transmission.

[00177] In a seventy-sixth aspect alternatively or in addition to one or more of the sixtyeighth through seventy-fifth aspects, the method further includes storing, after generating the first HARQ feedback and prior to receiving the second DCI message, the first HARQ feedback, receiving, from the base station after retransmitting the message and prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback, and retransmitting, to the base station based on the third DCI message, the first HARQ feedback.

[00178] In a seventy-seventh aspect alternatively or in addition to one or more of the sixty-eighth through seventy-sixth aspects, the DCI message further includes an indication of the one or more third resources, the first downlink transmission is semi- persistently scheduled by the base station, and the second downlink transmission is scheduled by the base station using a dedicated grant.

[00179] In a seventy-eighth aspect alternatively or in addition to one or more of the sixty-eighth through seventy-seventh aspects, the DCI message includes a second bit indicating whether the message is to include, for multiple SPS configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window, and further comprising transmitting the message based on receiving the first HARQ feedback and the second HARQ feedback within the particular window.

[00180] In a seventy-ninth aspect alternatively or in addition to one or more of the sixtyeighth through seventy-eighth aspects, the DCI message indicates a number of SPS configurations per HARQ ID to be included in the message. [00181] In an eightieth aspect alternatively or in addition to one or more of the sixtyeighth through seventy-ninth aspects, the first HARQ feedback and the second HARQ feedback are bundled within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback that is to be bundled with one or more of the first HARQ feedback or the second HARQ feedback.

[00182] In an eighty-first aspect alternatively or in addition to one or more of the first through eightieth aspects, a base station includes at least one processor and at least one memory storing code that, when executed by the at least one processor, is configured to cause the base station to transmit, to a UE, a first downlink transmission. The UE generates first HARQ feedback based on reception of the first downlink transmission. The at least one processor is further configured to transmit, to the UE prior to transmission of the first HARQ feedback, a DCI message indicating a second downlink transmission, one or more first resources associated with the transmission of the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission. The at least one processor is further configured to transmit, to the UE, the second downlink transmission in the one or more second resources and to receive, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

[00183] Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[00184] One or more components, functional blocks, or the devices described herein may include processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, among other examples, or any combination thereof. In addition, features discussed herein may be implemented via specialized processor circuitry, via executable instructions, or combinations thereof.

[00185] Those of skill would further appreciate that the various illustrative logical blocks, devices, circuits, and operations described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Skilled artisans will also readily recognize that the order or combination of components, methods, or interactions that are described herein are merely examples and that the components, methods, or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those illustrated and described herein.

[00186] The various illustrative logics, logical blocks, modules, circuits, and operations described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.

[00187] The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. In some implementations, a processor may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes and methods may be performed by circuitry that is specific to a given function.

[00188] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Implementations of the subject matter described in this specification also can be implemented as one or more computer programs, that is one or more modules of computer program instructions, encoded on a computer storage media for execution by, or to control the operation of, data processing apparatus.

[00189] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The operations of a method or process disclosed herein may be implemented in a processor-executable software module which may reside on a computer-readable medium. Computer- readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program from one place to another. A storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. Additionally, the operations of a method or process may reside as one or any combination or set of codes and instructions on a machine readable medium and computer-readable medium, which may be incorporated into a computer program product.

[00190] Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to some other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

[00191] Additionally, a person having ordinary skill in the art will readily appreciate, the terms “upper” and “lower” are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of any device as implemented.

[00192] Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[00193] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, some other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.

[00194] As used herein, including in the claims, the term “or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of’ indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (that is A and B and C) or any of these in any combination thereof. The term “substantially” is defined as largely but not necessarily wholly what is specified (and includes what is specified; for example, substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. In any disclosed implementations, the term “substantially” may be substituted with “within [a percentage] of’ what is specified, where the percentage includes 0.1, 1, 5, or 10 percent.

[00195] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

54 CLAIMSWHAT IS CLAIMED IS:

1. A user equipment (UE) comprising: at least one processor; and at least one memory storing code that, when executed by the at least one processor, is configured to cause the UE to: receive, from a base station, a first downlink transmission; generate first hybrid automatic repeat request (HARQ) feedback based on the reception of the first downlink transmission; receive, from the base station prior to transmission of the first HARQ feedback, a downlink control information (DCI) message indicating a second downlink transmission; defer, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission; receive, from the base station, the second downlink transmission in the one or more second resources; generate second HARQ feedback based on the reception of the second downlink transmission; and transmit, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

2. The UE of claim 1, wherein the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

3. The UE of claim 1, wherein the at least one processor is further configured to receive, prior to receiving the DCI message, a configuration message from the base station including a HARQ feedback bundling indication, and wherein the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled based on the one or more first resources overlapping the one or more second resources. 55

4. The UE of claim 1, wherein the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

5. The UE of claim 1, wherein the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

6. The UE of claim 1, wherein the at least one processor is further configured to: receive, from a base station, a third downlink transmission; generate third HARQ feedback based on the reception of the third downlink transmission; transmit, to the base station, the third HARQ feedback during a fourth downlink transmission; receive, from the base station, a second DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including a first bit having a second value indicating that the third HARQ feedback is not to be bundled; receive, from the base station, the retransmission of the fourth downlink transmission; generate fourth HARQ feedback based on the reception of the fourth downlink transmission; and transmit, to the base station, a message in one or more fourth resources that includes the fourth HARQ feedback and that does not include the third HARQ feedback based on the second value indicating that the third HARQ feedback is not to be bundled.

7. The UE of claim 6, wherein the at least one processor is further configured to: store the third HARQ feedback; 56 receive, from the base station prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback; and transmit, to the base station based on the fourth DCI message, the third HARQ feedback.

8. The UE of claim 1, wherein the at least one processor is further configured to: based on failure of the base station to receive the message, receive, from the base station, a second DCI message scheduling retransmission of the second downlink transmission, the second DCI message including a first bit having a second value indicating that the second HARQ feedback is not to be bundled; receive, from the base station based on the second DCI message, the retransmission of the second downlink transmission; and retransmit, to the base station, a message including the second HARQ feedback and excluding the first HARQ feedback based on the retransmission of the second downlink transmission.

9. The UE of claim 8, wherein the at least one processor is further configured to: store, after generating the first HARQ feedback and prior to receiving the second DCI message, the first HARQ feedback; receive, from the base station after retransmitting the message and prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback; and retransmit, to the base station based on the third DCI message, the first HARQ feedback.

10. The UE of claim 1, wherein the DCI message further includes an indication of the one or more third resources.

11. The UE of claim 1, wherein the first downlink transmission is semi- persistently scheduled by the base station. 57

12. The UE of claim 1, wherein the second downlink transmission is scheduled by the base station using a dedicated grant.

13. The UE of claim 1, wherein the DCI message includes a second bit indicating whether the message is to include, for multiple semi-persistent scheduling (SPS) configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window, and wherein the at least one processor is further configured to transmit the message based on receiving the first HARQ feedback and the second HARQ feedback within the particular window.

14. The UE of claim 1, wherein the DCI message indicates a number of semi- persistent scheduling (SPS) configurations per HARQ identifier (ID) to be included in the message.

15. The UE of claim 1, wherein the at least one processor is further configured to bundle the first HARQ feedback and the second HARQ feedback within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback that is to be bundled with one or more of the first HARQ feedback or the second HARQ feedback.

16. A method for wireless communication performed by a user equipment (UE), the method comprising: receiving, from a base station, a first downlink transmission; generating first hybrid automatic repeat request (HARQ) feedback based on the reception of the first downlink transmission; receiving, from the base station prior to transmission of the first HARQ feedback, a downlink control information (DCI) message indicating a second downlink transmission; deferring, based on one or more first resources associated with the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission, transmission of the first HARQ feedback until after the second downlink transmission; receiving, from the base station, the second downlink transmission in the one or more second resources; generating second HARQ feedback based on the reception of the second downlink transmission; and transmitting, to the base station, a message in one or more third resources that includes the first HARQ feedback and the second HARQ feedback.

17. The method of claim 16, wherein the first downlink transmission is associated with a first number of HARQ processes, the second downlink transmission is associated with a second number of HARQ processes, and the message includes a third number of bits, the third number corresponding to a sum of the first number and the second number.

18. The method of claim 16, further comprising receiving, prior to receiving the DCI message, a configuration message from the base station including a HARQ feedback bundling indication, and wherein the HARQ feedback bundling indication indicates that the first HARQ feedback is to be bundled based on the one or more first resources overlapping the one or more second resources.

19. The method of claim 16, wherein the DCI message excludes an explicit indication of whether the first HARQ feedback is to be bundled with the second HARQ feedback.

20. The method of claim 16, wherein the DCI message includes a first bit having a first value that indicates that the first HARQ feedback is to be bundled with the second HARQ feedback based on the one or more first resources overlapping the one or more second resources.

21. The method of claim 16, further comprising: receiving, from a base station, a third downlink transmission; generating third HARQ feedback based on the reception of the third downlink transmission; transmitting, to the base station, the third HARQ feedback during a fourth downlink transmission; receiving, from the base station, a second DCI message scheduling a retransmission of the fourth downlink transmission, the second DCI message including a first bit having a second value indicating that the third HARQ feedback is not to be bundled; receiving, from the base station, the retransmission of the fourth downlink transmission; generating fourth HARQ feedback based on the reception of the fourth downlink transmission; and transmitting, to the base station, a message in one or more fourth resources that includes the fourth HARQ feedback and that does not include the third HARQ feedback based on the second value indicating that the third HARQ feedback is not to be bundled.

22. The method of claim 21, further comprising: storing the third HARQ feedback; receiving, from the base station prior to an expiration time associated with the third downlink transmission, a fourth DCI message requesting the third HARQ feedback; and transmitting, to the base station based on the fourth DCI message, the third HARQ feedback.

23. The method of claim 16, further comprising: based on failure of the base station to receive the message, receiving, from the base station, a second DCI message scheduling retransmission of the second downlink transmission, the second DCI message including a first bit having a second value indicating that the second HARQ feedback is not to be bundled; receiving, from the base station based on the second DCI message, the retransmission of the second downlink transmission; and retransmitting, to the base station, a message including the second HARQ feedback and excluding the first HARQ feedback based on the retransmission of the second downlink transmission.

24. The method of claim 23, further comprising: storing, after generating the first HARQ feedback and prior to receiving the second DCI message, the first HARQ feedback; receiving, from the base station after retransmitting the message and prior to an expiration time associated with the first downlink transmission, a third DCI message requesting the first HARQ feedback; and retransmitting, to the base station based on the third DCI message, the first HARQ feedback.

25. The method of claim 16, wherein the DCI message further includes an indication of the one or more third resources, the first downlink transmission is semi- persistently scheduled by the base station, and the second downlink transmission is scheduled by the base station using a dedicated grant.

26. The method of claim 16, wherein the DCI message includes a second bit indicating whether the message is to include, for multiple semi-persistent scheduling (SPS) configurations or for an SPS configuration associated with the DCI message, HARQ feedback generated within a particular window, and further comprising transmitting the message based on receiving the first HARQ feedback and the second HARQ feedback within the particular window.

27. The method of claim 16, wherein the DCI message indicates a number of semi-persistent scheduling (SPS) configurations per HARQ identifier (ID) to be included in the message.

28. The method of claim 16, wherein the first HARQ feedback and the second HARQ feedback are bundled within the message based on failing to receive, within a threshold time interval prior to transmitting the message, an indication of third deferred HARQ feedback that is to be bundled with one or more of the first HARQ feedback or the second HARQ feedback.

29. A base station comprising: at least one processor; and 61 at least one memory storing code that, when executed by the at least one processor, is configured to cause the base station to: transmit, to a user equipment (UE), a first downlink transmission, the UE generating first hybrid automatic repeat request (HARQ) feedback based on reception of the first downlink transmission; transmit, to the UE prior to transmission of the first HARQ feedback, a downlink control information (DCI) message indicating a second downlink transmission, one or more first resources associated with the transmission of the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission; transmit, to the UE, the second downlink transmission in the one or more second resources; and receive, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.

30. A method for wireless communication performed by a base station, the method comprising: transmitting, to a user equipment (UE), a first downlink transmission, the UE generating first hybrid automatic repeat request (HARQ) feedback based on reception of the first downlink transmission; transmitting, to the UE prior to transmission of the first HARQ feedback, a downlink control information (DCI) message indicating a second downlink transmission, one or more first resources associated with the transmission of the first HARQ feedback overlapping one or more second resources associated with the second downlink transmission; transmitting, to the UE, the second downlink transmission in the one or more second resources; and receiving, from the UE, a message in one or more third resources that includes the first HARQ feedback and second HARQ feedback that is based on the reception of the second downlink transmission.