Hybrid automatic repeat request codebook design for sidelink

Abstract

Various aspects of the disclosure generally relate to wireless communication. In some aspects, a first user equipment (UE) can receive, from a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for the sidelink. The UE can transmit, to the second UE, HARQ feedback associated with the second UE based at least in part on the trigger signal. Numerous other aspects are provided.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority to U.S. non-provisional patent application No. 17 / 247,614, filed on December 17, 2020, entitled “HYBRID AUTOMATIC REPEAT REQUEST CODEBOOK DESIGN FOR ASIDELINK,” which is expressly incorporated herein by reference. Technical Field

[0003] In summary, various aspects of this disclosure relate to wireless communications, and particularly to techniques and apparatus for designing Hybrid Automatic Repeat Request (HARQ) codebooks for side links. Background Technology

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / Improved LTE is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standard released by the 3rd Generation Partnership Project (3GPP).

[0005] A wireless network may include multiple base stations (BSs) capable of supporting communication for multiple user equipments (UEs). UEs can communicate with base stations (BSs) via downlinks and uplinks. A downlink (or forward link) refers to the communication link from the BS to the UE, and an uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, gNB, Access Point (AP), Radio Headend, Transmit / Receive Point (TRP), New Radio (NR) BS, 5G Node B, etc.

[0006] The above multiple access technologies have been adopted in various telecommunication standards to provide common protocols to communicate between user equipment (UE) and base stations, e.g., LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR, which can also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP- OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband Internet access continues to increase, there exists a need for further improvements in LTE, NR, and other radio access technologies. These improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies. SUMMARY

[0007] In some aspects, a method of wireless communication performed by a first user equipment (UE) includes receiving, from a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for a sidelink; and transmitting, to the second UE based at least in part on the trigger signal, HARQ feedback associated with the second UE.

[0008] In some aspects, a method of wireless communication performed by a first user equipment (UE) includes transmitting, to a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for a sidelink; and receiving, from the second UE based at least in part on the trigger signal, HARQ feedback associated with the first UE.

[0009] In some aspects, a first UE for wireless communication includes a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to: receive, from a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for a sidelink; and transmit, to the second UE based at least in part on the trigger signal, HARQ feedback associated with the second UE.

[0010] In some aspects, a first UE for wireless communication includes a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to: transmit, to a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink; and receive, from the second UE based at least in part on the trigger signal, HARQ feedback associated with the first UE.

[0011] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a first UE, cause the first UE to: receive, from a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink; and transmit, to the second UE based at least in part on the trigger signal, HARQ feedback associated with the second UE.

[0012] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a first UE, cause the first UE to: transmit, to a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink; and receive, from the second UE based at least in part on the trigger signal, HARQ feedback associated with the first UE.

[0013] In some aspects, an apparatus for wireless communication includes means for receiving, from a UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink; and means for transmitting, to the UE based at least in part on the trigger signal, HARQ feedback associated with the UE.

[0014] In some aspects, an apparatus for wireless communication includes means for transmitting, to a UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink; and means for receiving, from the UE based at least in part on the trigger signal, HARQ feedback associated with the apparatus.

[0015] Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and / or processing system as substantially described herein with reference to and as illustrated by the drawings.

[0016] The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows can be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples can be readily utilized as bases upon which one skilled in the art can modify or devise various structures for carrying out the same purposes of the disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The representative features of the concepts disclosed herein will be better understood from the following description with reference to the drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0017] So that the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, can be had by reference to various aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description can admit to other equally effective aspects. Like reference numerals in the various drawings can identify the same or similar elements.

[0018] Figure 1 FIG. 1 is a diagram illustrating an example of a wireless network according to various aspects of the disclosure.

[0019] Figure 2 FIG. 2 is a diagram illustrating an example of a base station in communication with a user equipment (UE) in a wireless network, in accordance with various aspects of the disclosure.

[0020] Figure 3 FIG. 3 is a diagram illustrating an example of sidelink communication according to various aspects of the disclosure.

[0021] Figure 4 FIG. 4 is a diagram illustrating an example of sidelink communication and access link communication according to various aspects of the disclosure.

[0022] Figure 5 FIG. 5 is a diagram illustrating an example of sidelink feedback channel resource determination according to various aspects of the disclosure.

[0023] Figure 6 FIG. 6 is a diagram illustrating an example of sidelink feedback for multiple sidelink component carriers according to various aspects of the disclosure.

[0024] Figure 7 FIG. 7 is a diagram illustrating an example of signaling associated with triggered sidelink feedback for multiple sidelink component carriers according to various aspects of the disclosure.

[0025] Figure 8is a diagram illustrating an example of a timing associated with a trigger signal for sidelink feedback, in accordance with various aspects of the present disclosure.

[0026] Figures 9-10 is a diagram illustrating an example process associated with a hybrid automatic repeat request (HARQ) codebook design for sidelink, in accordance with various aspects of the present disclosure.

[0027] Figures 11-12 is a block diagram of an example apparatus for wireless communication, in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION

[0028] Various aspects of the disclosure are more fully described below with reference to the figures. The disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the disclosure. For example, an apparatus can be implemented or a method can be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using, in combination, features

[0029] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0030] It should be noted that while aspects can be described herein using terminology commonly associated with a 5G or NR radio access technology (RAT), aspects of the present disclosure can be applied to other RATs, such as a 3G RAT, a 4G RAT, and / or a RAT subsequent to 5G (e.g., 6G).

[0031] Figure 1is a diagram illustrating an example of a wireless network 100, in accordance with various aspects of the present disclosure. The wireless network 100 can be or include elements of a 5G (NR) network and / or a LTE network, among other examples. The wireless network 100 can include a number of base stations 110 (shown as BS 110a, BS 110b, BS 110c, and BS 1 lOd) and other network entities. A base station (BS) is an entity that communicates with user equipment (UEs) and can also be referred to as an NR BS, a Node B, a gNB, a 5G node B (NB), an access point, a transmit receive point (TRP), or the like. Each BS can provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and / or a BS subsystem serving the coverage area, depending on the context in which the term is used.

[0032] BSs can provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell can cover a relatively large geographic area (e.g., several kilometers in radius) and can allow unrestricted access by UEs with service subscriptions appropriate for the Figure 1 In an example shown in FIG. 1, BS 110a can be a macro BS for a macro cell 102a, BS 110b can be a pico BS for a pico cell 102b, and BS 110c can be a femto BS for a femto cell 102c. A BS can support one or multiple (e.g., three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “Node B,” “5G NB,” and “cell” can be used interchangeably herein.

[0033] In some aspects, a cell can not necessarily be stationary, and the geographic area of the cell can move according to the location of a mobile BS. In some aspects, a BS can be interconnected with other BSs or network nodes (not shown) in the wireless network 100 by various types of backhaul interfaces, such as a direct physical connection or a virtual network, using any appropriate transport network.

[0034] Wireless network 100 can also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. Figure 1 In the example shown in Figure 1, relay BS 1 lOd can communicate with macro BS 110a and UE 120d in order to facilitate communication between the BS 110a and UE 120d. A relay BS can also be referred to as a relay station, a relay base station, a repeater, etc.

[0035] Wireless network 100 can be a heterogeneous network that includes BSs of different types, such as macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs can have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, macro BSs can have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs can have lower transmit power levels (e.g., 0.1 to 2 Watts).

[0036] A network controller 130 can couple to a set of BSs and can provide coordination and control for these BSs. Network controller 130 can communicate with the BSs via a backhaul. The BSs can also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.

[0037] UEs 120 (e.g., 120a, 120b, 120c) can be dispersed throughout wireless network 100, and each UE can be stationary or mobile. A UE can also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, etc. A UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet, etc.), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

[0038] Some UEs can be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, e.g., robots, drones, remote devices, sensors, meters, monitors, and / or location tags, that can communicate with a base station, another device (e.g., remote device), or some other entity. A wireless node can provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet-of-Things (IoT) devices, and / or can be implemented as NB-IoT (narrowband internet of things) devices. Some UEs can be considered Customer Premises Equipment (CPE). UE 120 can be included inside a housing that houses components of UE 120, such as processor components and / or memory components. In some aspects, the processor components and the memory components can be coupled together. For example, the processor components (e.g., one or more processors) and the memory components (e.g., a memory) can be operatively coupled, communicatively coupled, electronically coupled, and / or electrically coupled.

[0039] In general, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a particular RAT and can operate on one or more frequencies. A RAT can also be referred to as a radio technology, an air interface, and / or the like. Frequencies can also be referred to as carriers, frequency channels, and / or the like. Each frequency can support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0040] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) can communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary to communicate with one another). For example, UE 120 can perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by base station 110. Some communications can be between a UE 120 and a base station 110. Other communications can be between UEs 120. For example, one or more UEs 120 (e.g., in a vehicle-to-vehicle (V2V) or vehicle-to-everything (V2X) scenario) can communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary to communicate with one another). In this case, UE 120 can perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by base station 110.

[0041] Devices of wireless network 100 can communicate using the electromagnetic spectrum, which can be subdivided, based on frequency or wavelength, into various classes, bands, channels, and so on. For example, devices of wireless network 100 can communicate using an operating band having a first frequency range (FR1), which can span, for example, from 410 MHz to 7.125 GHz, and / or can communicate using an operating band having a second frequency range (FR2), which can span, for example, from 24.25 GHz to 52.6 GHz. The frequencies between FR1 and FR2 are sometimes referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to as a “sub-6 GHz” band. Similarly, FR2 is often referred to as a “millimeter wave” band despite being different from the extremely high frequency (EHF) band, which the International Telecommunications Union (ITU) has identified as spanning from 30 GHz to 300 GHz. Thus, unless specifically stated otherwise, the term “sub-6 GHz” or like terminology, if used herein, can broadly represent frequencies less than 6 GHz, frequencies within FR1, and / or mid-band frequencies (e.g., greater than 7.125 GHz). Similarly, unless specifically stated otherwise, the term “millimeter wave” or like terminology, if used herein, can broadly represent frequencies within the EHF band, frequencies within FR2, and / or mid-band frequencies (e.g., less than 24.25 GHz). It is contemplated that the frequencies included in FR1 and FR2 can be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0042] As indicated above, Figure 1 are provided as examples. Other examples can differ from what is described with respect to at least one of the following. Figure 1

[0043] Figure 2 FIG. 1 is a diagram illustrating an example 100 of a wireless network, in accordance with various aspects of the present disclosure. The example wireless network 100 can include a number of base stations 110 (shown as BS 110A and BS 110B) and other network entities. A base station (BS) is an entity that communicates with user equipment (UE) and can also be referred to as an access point (AP), a network node, a NodeB, an eNodeB (eNB), a gNodeB (gNB), or some other similar terminology. Each BS can provide communication coverage for a particular area. In 3GPP, the term “cell” can refer to a coverage area of a BS and / or a BS subsystem serving the coverage area, depending on the context in which the term is used. A BS can be stationary, or mobile. A UE can be

[0044] ​At base station 110, a transmit processor 220 can receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS selected for the UE, and provide data symbols for all UEs. Transmit processor 220 can also process system information (e.g., for semi-static resource partitioning information (SRPI)) and control information (e.g., CQI requests, grants, and / or upper layer signaling) and provide overhead symbols and control symbols. Transmit processor 220 can also generate reference symbols for reference signals (e.g., a cell-specific reference signal (CRS) or a demodulation reference signal (DMRS)) and synchronization signals (e.g., a primary synchronization signal (PSS) or a secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and / or the reference symbols, if applicable, and can provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 can process a respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator 232 can further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t can be transmitted via T antennas 234a through 234t, respectively.

[0045] At the UE 120, the antennas 252a-252r can receive the downlink signals from the base station 110 and / or other base stations and can provide received signals to the demodulators (DEMODs) 254a-254r, respectively. Each demodulator 254 can condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 can further process the input samples (e.g., for OFDM) to obtain received symbols. A MIMO detector 256 can obtain received symbols from all R demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. The term “controller / processor” can refer to one or more controllers, one or more processors, or a combination thereof. A channel processor can determine reference signal received power (RSRP) parameters, received signal strength indicator (RSSI) parameters, reference signal received quality (RSRQ) parameters, and / or channel quality indicator (CQI) parameters, among other examples. In some aspects, one or more components of UE 120 can be included in a housing 284.

[0046] The network controller 130 can include a communication unit 294, a controller / processor 290, and a memory 292. The network controller 130 can include, for example, one or more devices in a core network. The network controller 130 can communicate with the base station 110 via the communication unit 294.

[0047] Antennas (e.g., antennas 234a-234t and / or antennas 252a-252r) can include or be included within one or more antenna panels, antenna groups, antenna element sets, and / or antenna arrays, among other examples. An antenna panel, antenna group, antenna element set, and / or antenna array can include one or more antenna elements. An antenna panel, antenna group, antenna element set, and / or antenna array can include a set of co-planar antenna elements and / or a set of non-co-planar antenna elements. An antenna panel, antenna group, antenna element set, and / or antenna array can include antenna elements within a single housing and / or antenna elements within multiple housings. An antenna panel, antenna group, antenna element set, and / or antenna array can include one or more antenna elements coupled to one or more transmit and / or receive components (such as one or more components of a transceiver 264 and / or a wireless communication and / or processing component 270). Figure 2 An antenna panel, antenna group, antenna element set, and / or antenna array can include one or more antenna elements coupled to one or more transmit and / or receive components (such as one or more components of a transceiver 264 and / or a wireless communication and / or processing component 270).

[0048] On the uplink, at UE 120, a transmit processor 264 can receive and process data from a data source 262 and control information (e.g., for reports including RSRP, RSSI, RSRQ, and / or CQI) from controller / processor 280. Transmit processor 264 can also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 can be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to base station 110. In some aspects, a modulator and a demodulator (e.g., MOD / DEMOD 254) of the UE 120 can be included in a modem of the UE 120. In some aspects, the UE 120 includes a transceiver. The transceiver can include any combination of antennas 252, modulators and / or demodulators 254, MIMO detector 256, receive processor 258, transmit processor 264, and / or TX MIMO processor 266. The transceiver can be used by a processor (e.g., controller / processor 280) and memory 282 to perform any of the methods described herein (for example, as described with reference to Figures 3-8 FIGS. 15 and 16).

[0049] At base station 110, the uplink signals from UE 120 and other UEs can be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 can provide the decoded data to a data sink 239 and the decoded control information to controller / processor 240. Base station 110 can include communication unit 244 and communicate to network controller 130 via communication unit 244. Base station 110 can include a scheduler 246 to schedule UEs 120 for downlink and / or uplink communications. In some aspects, a modulator and a demodulator (e.g., MOD / DEMOD 232) of the base station 110 can be included in a modem of the base station 110. In some aspects, the base station 110 includes a transceiver. The transceiver can include any combination of antennas 234, modulators and / or demodulators 232, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver can be used by a processor (e.g., controller / processor 240) and memory 242 to perform any of the methods described herein (for example, as described with reference to Figures 3-8 FIGS. 15 and 16).

[0050] The controller / processor 240 of base station 110, the controller / processor 280 of UE 120 and / or Figure 2 Any other components may perform one or more techniques associated with a Hybrid Automatic Repeat Request (HARQ) codebook design for sidelinks, as described in more detail elsewhere herein. For example, the controller / processor 240 of base station 110, the controller / processor 280 of UE 120, and / or Figure 2 Any other component can perform or direct, for example Figure 9 The process 900 Figure 10 The operation of process 1000 and / or other processes as described herein. Memory 242 and 282 may store data and program code for base station 110 and UE 120, respectively. In some aspects, memory 242 and / or memory 282 may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and / or program code) for wireless communication. For example, one or more instructions, when executed by one or more processors of base station 110 and / or UE 120 (e.g., directly, or after compilation, translation, and / or interpretation), may cause one or more processors, UE 120, and / or base station 110 to perform or instruct, for example... Figure 9 The process 900 Figure 10 The operation of process 1000 and / or other processes as described herein. In some aspects, execution instructions may include run instructions, transformation instructions, compilation instructions and / or interpretation instructions, and other examples.

[0051] In some aspects, the first UE includes: a unit for receiving, via a sidelink interface, a trigger signal associated with triggering HARQ feedback for the sidelink from the second UE; or a unit for transmitting, at least in part, HARQ feedback associated with the second UE to the second UE based on the trigger signal. The unit for the first UE to perform the operations described herein may include, for example, one or more of antenna 252, demodulator 254, MIMO detector 256, receiver processor 258, transmitter processor 264, TXMIMO processor 266, modulator 254, controller / processor 280, or memory 282.

[0052] In some aspects, the first UE includes: a unit for receiving information indicating at least one of single HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback.

[0053] In some aspects, the first UE includes: a unit for transmitting information indicating the number of HARQ codebooks that the first UE can generate simultaneously, wherein the HARQ feedback is at least partially based on the number of HARQ codebooks.

[0054] In some aspects, the first UE can include means for transmitting, to the second UE via the sidelink interface, a trigger signal associated with triggering HARQ feedback for the sidelink; or means for receiving, from the second UE, HARQ feedback associated with the first UE based at least in part on the trigger signal. Means for the first UE to perform operations described herein can include, for example, one or more of antenna 252, demodulator 254, MIMO detector 256, receive processor 258, transmit processor 264, TX MIMO processor 266, modulator 254, controller / processor 280, or memory 282.

[0055] In some aspects, the first UE includes means for transmitting information indicating at least one of providing single-shot HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback.

[0056] Although Figure 2 The blocks in FIG. 7 are illustrated as distinct components merely for clarity. The functions described above with respect to these blocks can be implemented in a single hardware, software, or combined component or in various combinations of components. For example, the functions described with respect to transmit processor 264, receive processor 258, and / or TX MIMO processor 266 can be performed by controller / processor 280 or under its control.

[0057] As indicated above, Figure 2 are provided as examples. Other examples can differ from what is described with respect to the examples Figure 2 described with respect to the examples

[0058] Figure 3 is a diagram illustrating an example 300 of sidelink communications, in accordance with various aspects of the present disclosure.

[0059] As Figure 3As shown, the first UE 305-1 can communicate with the second UE 305-2 (and one or more other UEs 305) via one or more sidelink channels 310. The UEs 305-1 and 305-2 can communicate using one or more sidelink channels 310 for P2P communication, D2D communication, V2X communication (which can include V2V communication, V2I communication, etc.), mesh networking, and the like. In some aspects, the UEs 305 (e.g., the UE 305-1 and / or the UE 305-2) can correspond to one or more other UEs described elsewhere herein, such as the UEs 120. In some aspects, the one or more sidelink channels 310 can use a ProSe sidelink (PC5) interface and / or can operate in a high frequency band (e.g., a 5.9 GHz band). Additionally, or alternatively, the UEs 305 can synchronize timing of transmission time intervals (TTIs) (e.g., frames, subframes, slots, symbols, etc.) using global navigation satellite system (GNSS) timing.

[0060] As shown, the first UE 305-1 can communicate with the second UE 305-2 (and one or more other UEs 305) via one or more sidelink channels 310. The UEs 305-1 and 305-2 can communicate using one or more sidelink channels 310 for P2P communication, D2D communication, V2X communication (which can include V2V communication, V2I communication, etc.), mesh networking, and the like. In some aspects, the UEs 305 (e.g., the UE 305-1 and / or the UE 305-2) can correspond to one or more other UEs described elsewhere herein, such as the UEs 120. In some aspects, the one or more sidelink channels 310 can use a ProSe sidelink (PC5) interface and / or can operate in a high frequency band (e.g., a 5.9 GHz band). Additionally, or alternatively, the UEs 305 can synchronize timing of transmission time intervals (TTIs) (e.g., frames, subframes, slots, symbols, etc.) using global navigation satellite system (GNSS) timing. Figure 3 Further shown, the one or more sidelink channels 310 can include a physical sidelink control channel (PSCCH) 315, a physical sidelink shared channel (PSSCH) 320, and / or a physical sidelink feedback channel (PSFCH) 325. Similar to a physical downlink control channel (PDCCH) and / or a physical uplink control channel (PUCCH) used for cellular communications with base stations 110 via access links or access channels, the PSCCH 315 can be used to convey control information. Similar to a physical downlink shared channel (PDSCH) and / or a physical uplink shared channel (PUSCH) used for cellular communications with base stations 110 via access links or access channels, the PSSCH 320 can be used to convey data. For example, the PSCCH 315 can carry sidelink control information (SCI) 330, which can indicate various control information for sidelink communications, such as one or more resources (e.g., time resources, frequency resources, spatial resources, etc.) in which a transport block (TB) 335 can be carried on the PSSCH 320. The TB 335 can include data. The PSFCH 325 can be used to convey sidelink feedback 340, such as HARQ feedback (e.g., acknowledgement or negative-acknowledgement (ACK / NACK) information), transmit power control (TPC), scheduling requests (SRs), and the like.

[0061] In some aspects, one or more of the sidelink channels 310 can use resource pools. For example, scheduling assignments (e.g., included in SCI 330) can be transmitted in a subchannel using specific resource blocks (RBs) across time. In some aspects, data transmissions associated with a scheduling assignment (e.g., on PSSCH 320) can occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and associated data transmission are not transmitted on adjacent RBs.

[0062] In some aspects, the UE 305 can operate using a transmission mode in which resource selection and / or scheduling is performed by the UE 305 (e.g., rather than a base station 110). In some aspects, the UE 305 can perform resource selection and / or scheduling by sensing channel availability for transmissions. For example, the UE 305 can measure a received signal strength indicator (RSSI) parameter (e.g., a sidelink-RSSI (S-RSSI) parameter) associated with various sidelink channels, can measure a reference signal received power (RSRP) parameter (e.g., a PSSCH-RSRP parameter) associated with various sidelink channels, can measure a reference signal received quality (RSRQ) parameter (e.g., a PSSCH-RSRQ parameter) associated with various sidelink channels, etc., and can select a channel for transmission of a sidelink communication based at least in part on the measurements.

[0063] Additionally, or alternatively, the UE 305 can perform resource selection and / or scheduling using SCI 330 received in PSCCH 315, which can indicate occupied resources, channel parameters, etc. Additionally, or alternatively, the UE 305 can perform resource selection and / or scheduling by determining a channel busy ratio (CBR) associated with various sidelink channels, which can be used for rate control (e.g., by indicating a maximum number of resource blocks that the UE 305 can use for a particular set of subframes).

[0064] In a transmission mode in which resource selection and / or scheduling is performed by the UE 305, the UE 305 can generate a sidelink grant and can transmit the grant in SCI 330. The sidelink grant can indicate, for example, one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks to be used for an upcoming sidelink transmission (e.g., for a TB 335) on a PSSCH 320, one or more subframes to be used for an upcoming sidelink transmission, a modulation and coding scheme (MCS) to be used for an upcoming sidelink transmission, and / or the like. In some aspects, the UE 305 can generate a sidelink grant indicating one or more parameters for a semi-persistent scheduling (SPS), such as a periodicity of sidelink transmissions. Additionally, or alternatively, the UE 305 can generate a sidelink grant for event-driven scheduling (e.g., for on-demand sidelink messages).

[0065] As indicated above, Figure 3 are provided as examples. Other examples can differ from what is described with respect to at least one of the described examples. Figure 3

[0066] Figure 4 FIG. 4 is a diagram illustrating an example 400 of sidelink communications and access link communications, in accordance with various aspects of the present disclosure.

[0067] As Figure 4 illustrated, a transmitter (Tx) / receiver (Rx) UE 405 and an Rx / Tx UE 410 can communicate with one another via a sidelink, as described above in connection with Figure 3 As further illustrated, in some sidelink modes, a base station 110 can communicate with the Tx / Rx UE 405 via a first access link. Additionally, or alternatively, in some sidelink modes, the base station 110 can communicate with the Rx / Tx UE 410 via a second access link. The Tx / Rx UE 405 and / or the Rx / Tx UE 410 can correspond to one or more UEs described elsewhere herein, such as the UEs 120 of Figure 1 FIG. 1. Thus, a direct link between UEs 120 (e.g., via a PC5 interface) can be referred to as a sidelink, and a direct link between a base station 110 and a UE 120 (e.g., via a Uu interface) can be referred to as an access link. Sidelink communications can be transmitted via a sidelink, and access link communications can be transmitted via an access link. An access link communication can be a downlink communication (from a base station 110 to a UE 120) or an uplink communication (from a UE 120 to a base station 110).

[0068] As indicated above, Figure 4 ​This is provided as an example. Other examples may differ from the one provided. Figure 4 The example described.

[0069] Figure 5 This is a diagram illustrating example 500 of the determination of sidelink feedback channel resources according to various aspects of this disclosure. Figure 5 Resource pool 505 is shown. Resource pool 505 includes 10 sub-channels (N subch =10), showing four sub-channels. A sub-channel is a frequency-domain subset of the resource pool. A resource pool can be configured with one or more sub-channels. In Example 500, the resource pool is configured with a Physical Side Link Feedback Channel (PSFCH) period of 4. The resource pool can be configured with a PSFCH period, which indicates the period of PSFCH transmissions associated with the resource pool. The PSFCH resource 510 indicated by the PSFCH period is in the fourth time slot of resource pool 505.

[0070] The UE can allocate a configured number of Physical Resource Blocks (PRBs) for PSFCH resource 510. In Example 500, the UE can allocate 80 PRBs for PSFCH resource 510. A PRB is a group of subcarriers and can include up to 12 subcarriers. This is because each PSFCH resource (due to...) ) and 10 sub-channels in the resource pool (due to N subch There are 4 time slots between them, so each subchannel is associated with 2 PSFCH PRBs out of 80 PSFCH PRBs (e.g., 80 PRBs / (4 time slots * 10 subchannels) = 2 PRBs). In this case, sidelink feedback for the subchannel and time slot can be transmitted on 1 of the 2 corresponding PSFCH PRBs. Referencing time slot i and subchannel j, as... Figure 5 As shown, the UE can Among the PRBs One PRB is allocated to time slot i and sub-channel j, where And 0≤j≤N subch .

[0071] As mentioned above, the PSFCH resources 510 can be used to transmit HARQ feedback regarding PSSCHs received in the resource pool 505. Sidelink HARQ can be sequence-based and can carry a single bit for each PSSCH. Sidelink HARQ can be transmitted over two consecutive symbols (e.g., symbols 11 and 12 of a slot). In some cases, one symbol before and one symbol after the PSFCH occasion is assigned to a gap. A parameter (e.g., periodPSFCHresource) can indicate a PSFCH periodicity (in number of slots) for the resource pool. For example, the PSFCH periodicity can be set to {0, 1, 2, 4}. If the PSFCH periodicity is set to 0, PSFCH transmissions from UEs in the resource pool are disabled. In example 500, the PSFCH periodicity is set to 4, so PSFCH transmissions are performed in every fourth slot. A UE can transmit a PSFCH in a first slot that includes PSFCH resources and is at least a number of slots (provided by a parameter (e.g., MinTimeGapPSFCH)) after a last slot in which a PSSCH is received in the resource pool. A parameter (e.g., rbSetPSFCH) can indicate a set and / or number of PRBs in the resource pool for PSFCH transmissions. A parameter (e.g., numSubchannel) can indicate a number of subchannels for the resource pool. subch A number of PSSCH slots associated with a PSFCH slot can be indicated, which can be determined based at least in part on the parameter periodPSFCHresource described above. In some aspects, and

[0072] As indicated above, Figure 5 are provided as examples. Other examples can differ from what is described with respect to at least one of the Figure 5 described examples.

[0073] ​​Sidelink deployments can support carrier aggregation (CA). In CA, multiple frequency blocks, referred to as component carriers (CCs) or cells, are assigned to a single user. Sidelink CA can improve sidelink throughput relative to a single carrier configuration. For example, in sidelink CA, a first UE and a second UE can communicate with each other using multiple CCs. In some examples, sidelink CA can be implemented using multiple resource pools. For example, each CC of a sidelink CA configuration can include one or more bandwidth parts (BWPs), and each BWP can include one or more resource pools. In this way, each CC of a sidelink CA configuration can be associated with a respective one or more resource pools. The techniques and apparatuses described herein are not limited to techniques and apparatuses involving respective resource pools for each CC, and can apply to scenarios in which multiple CCs are configured on a single resource pool, multiple BWPs are configured on a single resource pool, multiple resource pools are configured on a single CC, and / or multiple resource pools are configured on a single BWP, among other examples.

[0074] HARQ feedback provides a mechanism for indicating to a sender of a communication whether the communication was successfully received. For example, a sender can transmit scheduling information for a communication. A receiver of the scheduling information can monitor resources indicated by the scheduling information in order to receive the communication. If the receiver successfully receives the communication, the receiver can transmit an ACK in HARQ feedback. If the receiver fails to receive the communication, the receiver can transmit a NACK in HARQ feedback. Thus, based at least in part on HARQ feedback, the sender can determine whether the communication should be retransmitted. HARQ feedback is typically implemented using a single bit, where a first value of the bit indicates an ACK and a second value of the bit indicates a NACK. Such a bit can be referred to as a HARQ-ACK bit. HARQ-ACK feedback can be conveyed in a HARQ codebook, which can include one or more bits indicating an ACK or a NACK corresponding to one or more communications.

[0075] For sidelink CA, HARQ feedback can be related to communications on multiple sidelink CCs. For example, a first UE can transmit HARQ feedback to a second UE regarding multiple PSSCHs on different CCs. As another example, a first UE can transmit HARQ feedback to multiple different UEs regarding PSSCHs received from multiple different UEs on different CCs.

[0076] For example, due to a congested sidelink network, a low priority level of the sidelink UE, and / or the like, there are scenarios in which the UE can have difficulty ensuring channel access. If the UE is unable to ensure channel access, the UE’s communications can be negatively impacted. For example, the UE can experience delays in transmitting communications, cancelled communications, failure to meet quality of service (QoS) requirements, and / or the like. One type of communication that can be impacted by delays and cancellation is HARQ feedback. If the receiving UE is unable to transmit HARQ feedback in a timely manner, the transmitting UE can have difficulty determining whether the transmitting UE’s communications were successfully received. This can result in inefficient network resource utilization, unnecessary retransmissions, and negatively impact user experience.

[0077] Some techniques and apparatuses described herein provide triggered HARQ feedback for sidelink UEs configured with sidelink CA. For example, some techniques and apparatuses described herein use a trigger signal to provide a trigger for a HARQ feedback transmission. The trigger signal can be generated by a transmitting UE or a gNB (and relayed by the transmitting UE, or transmitted by the transmitting UE based at least in part on a trigger signal generated by the gNB). Based at least in part on the trigger signal, a receiving UE can generate and transmit HARQ feedback for the transmitting UE associated with the trigger signal. Some techniques and apparatuses described herein provide for configuration or selection between a triggered HARQ feedback scheme (also referred to as a one-shot HARQ feedback mechanism), a semi-static HARQ feedback scheme, and a dynamic HARQ feedback scheme, as described in more detail elsewhere herein. In this way, for example, a transmitting UE can trigger HARQ feedback when channel conditions are favorable, or when the transmitting UE fails to receive a previous HARQ feedback, which improves network resource utilization, reduces occurrences of unnecessary retransmissions, and improves user experience.

[0078] While many aspects described herein are described with respect to carrier aggregation, these aspects can also be applied to single carrier deployments.

[0079] Figure 6 is a diagram illustrating an example 600 of sidelink feedback for multiple sidelink component carriers, in accordance with various aspects of the present disclosure. Example 600 shows a first CC (CC0) and a second CC (CC1) that are sidelink CCs between a first UE (e.g., a receiving UE) and a second UE (e.g., a transmitting UE). In Figure 6 The receiving UE and the transmitting UE are not shown in

[0080] As shown, the first UE can receive multiple PSSCHs from the second UE. For example, the first UE can receive one or more PSSCHs on the first CC and one or more PSSCHs on the second CC. As indicated by the arrows from the PSSCHs, the UE can provide HARQ feedback for the multiple PSSCHs on the PSFCH transmitted via the designated set of CCs. In example 500, the designated set of CCs includes only CC0, but other examples can include a different CC (e.g., CC1) or multiple CCs (e.g., CC0 and CC1). The HARQ feedback can include a HARQ codebook. In example 600, the HARQ codebook can include four bits: one bit for each of the PSSCHs in example 600. The techniques and apparatuses described herein provide for triggered HARQ feedback and selection between triggered HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback.

[0081] As noted above, Figure 6 are provided as examples. Other examples can differ from what is described Figure 6 with respect to the examples described.

[0082] Figure 7 is a diagram illustrating an example 700 of signaling associated with triggered sidelink feedback for multiple sidelink component carriers, in accordance with various aspects of the present disclosure. As shown, example 700 includes a first UE (e.g., UE 120, UE 305, UE 405 / 410) and a second UE (e.g., UE 120, UE 305, UE 405 / 410). In example 700, the first UE is a receiver UE that receives a sidelink channel from the second UE. For clarity, example 700 is described with respect to a single first UE and a single second UE. However, there are aspects of the disclosure that involve multiple different first UEs and / or multiple different second UEs, and these aspects are described in connection with Figures 7-8 While the techniques described herein are primarily described with respect to CA configurations for sidelink communications, these techniques can also be applied to sidelink deployments that include a single carrier.

[0083] As shown by reference number 705, the first UE and the second UE can be associated with a first CC. As shown by reference number 710, the first UE and the second UE can be associated with a second CC. For example, the first CC and the second CC can be part of a CA configuration of the first UE and the second UE. The first CC and the second CC can be sidelink CCs. A sidelink CC is a CC used for communication between UEs (e.g., via a sidelink). In some aspects, the first CC and the second CC can be implemented using respective resource pools. In some aspects, the first CC and the second CC can be implemented on a single resource pool. The first UE can be associated with a destination UE identifier and the second UE can be associated with a source UE identifier. In some aspects, the first CC and the second CC can be associated with unicast communication. In some aspects, the first CC and the second CC can be associated with groupcast communication. In some aspects, the first CC and the second CC can be associated with multicast communication. A “traffic cast type” of a link between the first UE and the second UE can indicate whether the link is associated with unicast communication, multicast communication, or groupcast communication. Further, the first UE and the second UE can be referred to as being associated with a session. The session can include the first CC and the second CC and can be identified at least by the source UE identifier and the destination UE identifier.

[0084] As shown by reference number 715, the first UE can receive one or more first sidelink channels from the second UE on the first CC. As shown by reference number 720, the first UE can receive one or more second sidelink channels from the second UE on the second CC. In some aspects, the one or more first sidelink channels and / or the one or more second sidelink channels can be PSSCHs. In some aspects, the first UE can receive a sidelink channel only on one of the first CC and the second CC. In some aspects, the first UE can fail to receive one or more of the sidelink channels shown in example 700.

[0085] As shown by reference number 725, the first UE can receive the trigger signal from the second UE. The first UE can receive the trigger signal via a sidelink interface. The trigger signal can trigger the first UE to generate HARQ feedback for the sidelink between the first UE and the second UE. For example, the trigger signal can trigger the HARQ feedback. In some aspects, the second UE can trigger the HARQ feedback for a particular UE (in this case, the first UE). In some aspects, the second UE can relay the trigger signal from a gNB. For example, the gNB can transmit a DCI that causes the second UE to transmit the trigger signal using a downlink control information (DCI) format, such as a DCI format that is specific to triggering the second UE to transmit the trigger signal (e.g., a DCI format 3_X, where X is an integer). In some aspects, the second UE can transmit the trigger signal via a sidelink control information (SCI). For example, the SCI can include a bit that indicates that the SCI includes or is the trigger signal. In some aspects, the SCI can use a format that is specific to the trigger signal.

[0086] In some aspects, the second UE can schedule a data transmission associated with the trigger signal. For example, a PSCCH that carries the SCI that conveys the trigger signal can also schedule a data transmission in a PSSCH that corresponds to the PSCCH. If the PSCCH does not schedule a data transmission, and if the trigger is conveyed in SCI-2, then the entire slot in which the SCI-2 is received can be dedicated to the SCI-2.

[0087] In some aspects, the second UE can indicate a PSFCH resource for the HARQ feedback. For example, the second UE can indicate the PSFCH resource via information included in the trigger signal, by configuring the UE, by configuring a resource pool associated with the trigger signal, and / or the like. In some aspects, the indication of the PSFCH resource can be associated with a timeline. For example, the first UE can be expected to comply with the indication of the PSFCH resource only if there is at least a threshold length of time (defined in terms of slots, symbols, and / or the like) between the trigger signal and the PSFCH resource. The threshold length of time can be based at least in part on a network configuration, a capability of the first UE (which can be signaled by the first UE in capability information), a wireless communication specification, a pre-configuration (e.g., according to the wireless communication specification), and / or the like.

[0088] In some aspects, the first UE can transmit HARQ feedback to the second UE on the PSSCH. In such cases, the first UE can include a flag in the transmission on the PSSCH indicating whether the PSSCH includes HARQ feedback. This can be advantageous for the triggering UE (e.g., the second UE) because there are cases where the triggering UE can not be certain whether the PSSCH includes HARQ feedback. For example, the first UE can transmit the PSSCH to the second UE before the first UE has decoded the PSCCH or PSSCH that triggered the HARQ feedback. As another example, the first UE can have a higher priority packet (e.g., a more important packet) to transmit before the HARQ feedback.

[0089] As shown by reference number 730, the first UE can determine HARQ feedback for one or more first sidelink channels and one or more second sidelink channels based at least in part on the trigger signal. For example, the first UE can generate HARQ feedback for all sidelink HARQ processes associated with a source UE identifier associated with the trigger signal. For example, the first UE can generate HARQ feedback for all sidelink HARQ processes associated with a second UE (e.g., the UE that triggered the HARQ report) for each sidelink CC between the first UE and the second UE. For example, UE1 can have sidelink communications with UE2 on CC0 and CC1 and sidelink communications with UE3 on CC2 and CC3 (not shown in FIG. 7). If UE2 triggers a report for UE1, then UE1 can generate HARQ feedback for sidelink HARQ processes with UE2 and for CC0 and CC1 only. Figure 7

[0090] In some aspects, the trigger signal can apply to a subset of CCs. For example, the trigger can indicate an index corresponding to a subset of CCs. As another example, the first UE can determine a subset of CCs. For example, if UE1 and UE2 have aggregated 4 SL CCs, and CC0 is used as a SL HARQ CC for CC0 and CC1, and CC2 is used as a SL HARQ CC for CC2 and CC3, then if the trigger is received on CC0 or CC1, then HARQ-ACK can be reported for all HARQ processes associated with these two carriers only.

[0091] ​A HARQ process can correspond to a PSSCH or another communication for which HARQ feedback is to be provided. The HARQ identifier can indicate a sidelink HARQ process associated with the PSSCH or another communication and can enable the first UE and the second UE to identify the communication to which the HARQ-ACK bits correspond. When the transmitting UE transmits a communication, the transmitting UE can cycle through a plurality of HARQ process identifiers corresponding to a plurality of HARQ processes. The first UE can track and report HARQ feedback for the plurality of HARQ process identifiers.

[0092] As shown by reference number 735, the first UE can transmit the HARQ feedback. For example, the first UE can transmit the HARQ feedback on PSFCH resources indicated by the second UE, on the PSSCH, on a dedicated set of CCs, and / or the like. Thus, the second UE can trigger the HARQ feedback (e.g., a one-shot HARQ feedback), and the first UE can provide the triggered HARQ feedback (e.g., a one-shot HARQ feedback).

[0093] In some aspects, the first UE and / or the second UE can be capable of generating and / or interpreting a number of different types of HARQ feedback, such as triggered HARQ feedback, semi-static HARQ feedback, dynamic HARQ feedback, and / or the like. A semi-static HARQ codebook includes HARQ-ACK bits corresponding to “potential” PSSCH occasions of each slot. For example, if a PSFCH is to be transmitted in slot n, the UE can generate HARQ-ACK bits for a set of past slots of slot N for a slot offset (e.g., K1). The slot offset K1 can indicate a number of slots between a PSSCH and a PSFCH carrying HARQ feedback related to the PSSCH. Since different PSSCHs can be associated with different slot offsets (in some aspects), a PSFCH can carry HARQ feedback for multiple PSSCHs.

[0094] The following pseudo code is provided by way of example only for determining a semi-static HARQ codebook:

[0095]

[0096]

[0097] In some aspects, in sidelink, the first UE can only receive a single PSSCH from one other UE in a given slot. Thus, the first part of the pseudo code (e.g., 1> If UE can only receive 1 PSSCH in a slot; 2> Determine 1 PSSCH occasion per slot; Add PSSCH occasion j to set M A,c ) can be used to determine the HARQ codebook.

[0098] A dynamic HARQ codebook is a HARQ codebook determined based at least in part on a PSCCH monitoring occasion and / or a sidelink assignment indicator (SAI). A PSCCH monitoring occasion is a set of resources in which a UE can monitor for a PSSCH. A PSSCH monitoring occasion can be determined based at least in part on a slot offset between a PSSCH and a corresponding PSFCH (e.g., K1) and a slot offset between a PSCCH and a corresponding PSSCH (e.g., K0). PSSCH monitoring occasions are only counted in the time domain, which means that a PSSCH monitoring occasion can span multiple CCs if PSSCH monitoring resources on multiple CCs are aligned with one another in time. An SAI can be conveyed via SCI. An SAI can include a counter SAI (sometimes abbreviated as cSAI) and a total SAI (sometimes abbreviated as tSAI). Generally, a cSAI and a tSAI can be used to determine how many SCIs (and thus how many scheduled PSSCHs) are sent to a first UE. The first UE can use the SAI conveyed from a second UE via SCI to determine how many HARQ-ACK bits should be included in a PSFCH.

[0099] In some aspects, the first UE can receive an information indication about whether to provide triggered HARQ feedback (e.g., using a Type 3 HARQ codebook), semi-static HARQ feedback (e.g., using a Type 1 HARQ codebook), or dynamic HARQ feedback (e.g., using a Type 2 HARQ codebook). For example, the first UE can be configured to report HARQ feedback based at least in part on a semi-static HARQ feedback scheme or a dynamic HARQ feedback scheme. In some aspects, the first UE can be configured to report triggered HARQ feedback upon receiving a trigger signal in addition to being configured to provide semi-static HARQ feedback or dynamic HARQ feedback (e.g., according to a PSFCH periodicity). In other words, a Type 3 codebook need not be a standalone mode of operation and can be supported in conjunction with other HARQ-ACK codebook types.

[0100] In some aspects, the first UE can be configured to provide different HARQ codebook types (e.g., triggered HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback). For example, the HARQ codebook type can be configured for a resource pool (e.g., each resource pool), a sidelink carrier (e.g., each sidelink carrier for a sidelink bandwidth part), a BWP, a traffic cast type (e.g., each traffic cast type), or a zone identifier (e.g., each zone identifier). The zone identifier can indicate a location of the first UE or a zone in which the first UE is located. In some aspects, the HARQ codebook type can be preconfigured for a resource pool (e.g., each resource pool), a sidelink carrier (e.g., each sidelink carrier for a sidelink bandwidth part), a BWP, a traffic cast type (e.g., each traffic cast type), or a zone identifier (e.g., each zone identifier).

[0101] In some aspects, the first UE can generate multiple HARQ codebooks (e.g., in response to a trigger signal or independently of a trigger signal). For example, the first UE can independently generate one HARQ codebook per unicast link and one HARQ codebook per groupcast link (equivalently, one HARQ codebook per source UE identifier). For example, UE1 can have unicast links with UE2 and UE3. In a case that transmissions are based on HARQ, UE1 can generate one codebook for PSSCHs received from UE2 and one codebook for PSSCHs received from UE3. As another example, a UE can be capable of generating 2 codebooks at a time, and the UE can be participating in one unicast session and one groupcast session, both of which require HARQ feedback. If there is a request from another UE for PC5 link setup for traffic requiring feedback, the UE can refrain from setting up the link (e.g., because the UE can only generate 2 codebooks at a time and the UE is already associated with 2 sessions). The number of sidelink codebooks that a UE can generate at a time can be reported as a UE capability to, for example, a peer UE in a sidelink network and / or a network or gNB.

[0102] As indicated above, Figure 7 are provided by way of example. Other examples can differ from those described Figure 7 without departing from the spirit of the disclosure.

[0103] Figure 8is a diagram illustrating example 800 of timing associated with trigger signals for sidelink feedback, in accordance with various aspects of the present disclosure. In example 800, a first UE receives communications in a first slot associated with HARQ identifiers 0, 1, and 2. The HARQ identifiers can indicate HARQ processes associated with PSSCH or another transmission, and can enable the first UE and a second UE to identify communications corresponding to HARQ-ACK bits. The transmitting UE can cycle through multiple HARQ process identifiers. The first UE can track and report HARQ feedback for the multiple HARQ process identifiers.

[0104] In example 800, each block represents a slot, and the vertical stacking of blocks represents multiple receptions in a slot. As shown, in a second slot, the second UE can trigger HARQ feedback, e.g., by sending a trigger signal to the first UE. As shown, the first UE can decode the PSCCH in the third slot or the fourth slot. Subsequently, in a fifth slot, the second UE can send another TB associated with HARQ identifier 1. Thus, the UE receives the TB after the HARQ feedback has been triggered and before the HARQ feedback has been sent. After the PSCCH has been decoded, the first UE can identify the PSSCH to be indicated in the report, and can send the report on the PSSCH (or in the PSFCH) in a seventh slot.

[0105] In some aspects, the first UE can only report HARQ feedback that considers the status of each HARQ process up to a given slot in which the trigger signal is received (in example 800, the second slot), e.g., before and including the given slot. In this example, the first UE can ignore the transmission in the fifth slot for purposes of generating the HARQ feedback. In this case, even though the second UE sends another communication (e.g., the TB in the fifth slot), the second UE can realize that if the communication occurs after the trigger signal is received, the first UE will not update the HARQ-ACK bit for the HARQ process corresponding to the communication, and thus there is no ambiguity.

[0106] In some aspects, in the case that the first UE receives a new transmission for a given HARQ process after the HARQ feedback is triggered, then the first UE can update the HARQ value for the given HARQ process. However, to ensure that the first UE has sufficient time to process the PSCCH / PSSCH and update the HARQ codebook, a cutoff time (e.g., in terms of slots, etc.) can be defined before the transmission of the HARQ codebook. Once the second UE knows the cutoff time, the second UE can determine whether the HARQ codebook was updated with respect to transmissions after the trigger signal. Thus, there will be no ambiguity.

[0107] As pointed out above, Figure 8 This is provided as an example. Other examples may differ from the one provided. Figure 8 The example described.

[0108] Figure 9 This is a diagram illustrating, for example, an example process 900 performed by a first UE according to various aspects of this disclosure. Example process 900 is an example in which a UE (e.g., UE 120, UE 305, UE 405 / 410) performs operations associated with a HARQ codebook design.

[0109] like Figure 9 As shown, in some aspects, process 900 may include: receiving a trigger signal (block 910) from a second UE via a sidelink interface associated with triggering HARQ feedback for the sidelink. For example, the UE (e.g., using...) Figure 11 The receiving component 1102 described herein can receive, via the side link interface, a trigger signal associated with triggering HARQ feedback for the side link from the second UE, as described above.

[0110] like Figure 9 As further shown, in some aspects, process 900 may include: sending HARQ feedback associated with the second UE to the second UE (block 920) at least in part based on a trigger signal. For example, the UE (e.g., using...) Figure 11 The transmitting component 1104 described herein can transmit HARQ feedback associated with the second UE to the second UE, at least in part, based on a trigger signal, as described above.

[0111] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in conjunction with one or more other processes described elsewhere herein.

[0112] In the first aspect, the first UE and the second UE are associated with a carrier aggregation configuration, and the HARQ feedback involves multiple carriers of the carrier aggregation configuration.

[0113] In the second aspect, either alone or in combination with the first aspect, the trigger signal includes side link control information.

[0114] In the third aspect, either alone or in combination with one or more of the first and second aspects, the trigger signal is received via a side link control channel, wherein the side link control channel schedules data transmission in the corresponding side link shared channel.

[0115] In a fourth aspect, alone or in combination with one or more of the first through third aspects, the trigger signal is received via a sidelink control channel, wherein the sidelink control channel does not schedule a data transmission in a corresponding sidelink shared channel, and wherein a slot including the sidelink control channel is fully allocated for the sidelink control channel.

[0116] In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the trigger signal is associated with information indicating a feedback resource for HARQ feedback, and wherein the HARQ feedback is transmitted on the feedback resource.

[0117] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the HARQ feedback is transmitted via a sidelink shared channel.

[0118] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the HARQ feedback relates to each sidelink HARQ process associated with a source identifier of the second UE and each carrier between the first UE and the second UE.

[0119] In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the trigger signal is received in a given slot, and wherein the HARQ feedback includes feedback only about slots before the given slot and the given slot.

[0120] In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the trigger signal is received in a given slot, and wherein the HARQ feedback includes feedback about slots after the given slot based at least in part on a feedback cutoff time.

[0121] In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the HARQ feedback is provided in a communication that includes a flag indicating that the communication includes the HARQ feedback.

[0122] In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, the HARQ feedback is based at least in part on the trigger signal, wherein the HARQ feedback is a single-shot HARQ feedback, and wherein the method further includes receiving information indicating at least one of providing a single-shot HARQ feedback, a semi-static HARQ feedback, or a dynamic HARQ feedback.

[0123] In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the received information is specific to at least one of: a resource pool, a sidelink carrier, a sidelink BWP, a traffic broadcast type, or a zone identifier.

[0124] In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the HARQ feedback includes one HARQ codebook per unicast link of the first UE and one HARQ codebook per groupcast link of the first UE.

[0125] In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the HARQ feedback includes one HARQ codebook per source identifier of the first UE.

[0126] In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the process 900 includes transmitting information indicating a number of HARQ codebooks that the first UE is capable of generating simultaneously, wherein the HARQ feedback is based at least in part on the number of HARQ codebooks.

[0127] Although Figure 9 Example blocks of the process 900 are illustrated, but in some aspects, the process 900 can include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Figure 9 Additionally or alternatively, two or more of the blocks of the process 900 can be performed in parallel.

[0128] Figure 10 FIG. 10 is a diagram illustrating an example process 1000 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 1000 is an example where a UE (e.g., UE 120) performs operations associated with hybrid automatic repeat request codebook design.

[0129] As Figure 10 shown, in some aspects, the process 1000 can include transmitting, to a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink (block 1010). For example, the UE (e.g., using transmission component 1204, depicted in FIG. 12) can transmit, to a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for a sidelink, as described above. Figure 12

[0130] As Figure 10 ​Further, in some aspects, process 1000 can include receiving, from the second UE, HARQ feedback associated with the first UE based at least in part on the trigger signal (block 1020). For example, the UE (e.g., using reception component 1202, depicted in FIG. 12) can receive, from the second UE, HARQ feedback associated with the first UE based at least in part on the trigger signal, as described above. Figure 12 Further, in some aspects, process 1000 can include receiving, from the second UE, HARQ feedback associated with the first UE based at least in part on the trigger signal (block 1020). For example, the UE (e.g., using reception component 1202, depicted in FIG. 12) can receive, from the second UE, HARQ feedback associated with the first UE based at least in part on the trigger signal, as described above.

[0131] Process 1000 can include additional aspects, such as any single aspect or any combination of aspects described below and / or in connection with one or more other processes described elsewhere herein.

[0132] In a first aspect, the first UE and the second UE are associated with a carrier aggregation configuration, and wherein the HARQ feedback relates to multiple carriers of the carrier aggregation configuration.

[0133] In a second aspect, alone or in combination with the first aspect, the trigger signal is relayed from a base station via the first UE.

[0134] In a third aspect, alone or in combination with one or more of the first and second aspects, the trigger signal is transmitted via a sidelink control channel, wherein the sidelink control channel does not schedule a data transmission in a corresponding sidelink shared channel, and wherein a slot including the sidelink control channel is fully allocated for the sidelink control channel.

[0135] In a fourth aspect, alone or in combination with one or more of the first through third aspects, the trigger signal is associated with information indicating feedback resources for the HARQ feedback, and wherein the HARQ feedback is transmitted on the feedback resources.

[0136] In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the HARQ feedback relates to each sidelink HARQ process associated with a source identifier of the first UE and each carrier between the first UE and the second UE.

[0137] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the trigger signal is transmitted in a given slot, and wherein the HARQ feedback includes feedback regarding only slots prior to the given slot and the given slot.

[0138] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the trigger signal is transmitted in a given slot, and wherein the HARQ feedback includes feedback regarding slots after the given slot based at least in part on a feedback cutoff time.

[0139] In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the HARQ feedback is received in a communication that includes a flag indicating that the communication includes HARQ feedback.

[0140] In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the HARQ feedback is based at least in part on the trigger signal, wherein the HARQ feedback is a one-shot HARQ feedback, and wherein the method further comprises transmitting information indicating at least one of providing a one-shot HARQ feedback, a semi-static HARQ feedback, or a dynamic HARQ feedback.

[0141] In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the HARQ feedback includes one HARQ codebook per unicast link of the first UE and one HARQ codebook per groupcast link of the first UE.

[0142] Although Figure 10 Example blocks of the process 1000 are shown, but in some aspects, the process 1000 can include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Figure 10 In some aspects, two or more of the blocks of process 1000 can be performed in parallel, in series, or in some order.

[0143] Figure 11 is a block diagram of an example apparatus 1100 for wireless communication. The apparatus 1100 can be a first UE, or a first UE can include the apparatus 1100. In some aspects, the apparatus 1100 includes a reception component 1102 and a transmission component 1104, which can be in communication with one another (for example, via one or more buses and / or one or more other components). As shown, the apparatus 1100 can communicate with another apparatus 1106 (such as a UE, a base station, or another wireless communication device) using the reception component 1102 and the transmission component 1104. As further shown, the apparatus 1100 can include a HARQ component 1108, among other examples.

[0144] In some aspects, the apparatus 1100 can be configured to perform one or more operations described herein with reference to Figures 3-8 one or more processes described herein. Additionally, or alternatively, the apparatus 1100 can be configured to perform one or more processes described herein, such as process 900 of Figure 9 or a combination thereof. In some aspects, the apparatus 1100 and / or one or more components shown in Figure 11 may include one or more components of the first UE described above with reference to Figure 2 In some aspects, one or more components shown in Figure 11 may be one or more components of the first UE described above with reference toFigure 2 One or more components described can be implemented within one or more circuits. Additionally or alternatively, one or more components of a set of components can be implemented at least partially as software stored in a memory. For example, a component (or a portion of a component) can be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

[0145] The reception component 1102 can receive communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus 1106. The reception component 1102 can provide received communications to one or more other components of the apparatus 1100. In some aspects, the reception component 1102 can perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and can provide the processed signals to the one or more other components of the apparatus 1106. In some aspects, the reception component 1102 can include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller / processor, a memory, or a combination thereof, of the first UE described above. Figure 2 The reception component 1102 can receive communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus 1106. The reception component 1102 can provide received communications to one or more other components of the apparatus 1100. In some aspects, the reception component 1102 can perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and can provide the processed signals to the one or more other components of the apparatus 1106. In some aspects, the reception component 1102 can include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller / processor, a memory, or a combination thereof, of the first UE described above.

[0146] The transmission component 1104 can transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1106. In some aspects, one or more other components of the apparatus 1106 can generate communications and can provide the generated communications to the transmission component 1104 for transmission to the apparatus 1106. In some aspects, the transmission component 1104 can perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and can transmit the processed signals to the apparatus 1106. In some aspects, the transmission component 1104 can include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller / processor, a memory, or a combination thereof, of the first UE described above. Figure 2 The transmission component 1104 can transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1106. In some aspects, one or more other components of the apparatus 1106 can generate communications and can provide the generated communications to the transmission component 1104 for transmission to the apparatus 1106. In some aspects, the transmission component 1104 can perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and can transmit the processed signals to the apparatus 1106. In some aspects, the transmission component 1104 can include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller / processor, a memory, or a combination thereof, of the first UE described above.

[0147] The reception component 1102 can receive, from a second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for the sidelink. The transmission component 1104 can transmit, to the second UE, HARQ feedback associated with the second UE based at least in part on the trigger signal. The HARQ component 1108 can generate the HARQ feedback associated with the second UE.

[0148] The transmitting component 1104 can transmit information indicating the number of HARQ codebooks that the first UE can generate simultaneously, wherein the HARQ feedback is at least partially based on the number of HARQ codebooks.

[0149] exist Figure 11 The number and arrangement of components shown are provided as an example. In reality, they can exist in... Figure 11 The components shown are compared to additional components, fewer components, different components, or components arranged in a different manner. Furthermore, in Figure 11 The two or more components shown can be implemented within a single component, or in Figure 11 The single component shown can be implemented as multiple distributed components. Alternatively, in Figure 11 The set (one or more) components shown can perform actions described by [the following]: Figure 11 The other set of components shown performs one or more functions.

[0150] Figure 12 This is a block diagram of an example device 1200 for wireless communication. Device 1200 may be a first UE, or a first UE may include device 1200. In some aspects, device 1200 includes a receiving component 1202 and a transmitting component 1204, which can communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, device 1200 can use the receiving component 1202 and the transmitting component 1204 to communicate with another device 1206 (such as a UE, a base station, or another wireless communication device). As further shown, device 1200 may include a HARQ component 1208 and other examples.

[0151] In some respects, device 1200 can be configured to perform the functions described herein. Figures 3-8 One or more operations described herein. Alternatively or concurrently, the apparatus 1200 may be configured to perform one or more processes described herein, such as... Figure 10 The process 1000 or a combination thereof. In some aspects, in Figure 12 The device 1200 and / or one or more components shown may include the above-described components. Figure 2 One or more components of the first UE described. Alternatively or concurrently, in Figure 12 One or more components shown can be combined with the above. Figure 2 Implementation within one or more components described. Alternatively, one or more of the components in a set may be implemented at least partially as software stored in memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or processor to perform the function or operation of the component.

[0152] The reception component 1202 can receive communications, such as reference signals, control information, data communications, or any combination thereof, from the apparatus 1206. The reception component 1202 can provide received communications to one or more other components of the apparatus 1200. In some aspects, the reception component 1202 can perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and can provide the processed signals to the one or more other components of the apparatus 1206. In some aspects, the reception component 1202 can include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller / processor, a memory, or any combination thereof, of the first UE as described above in connection with FIG. 12. Figure 2 The reception component 1202 can receive communications, such as reference signals, control information, data communications, or any combination thereof, from the apparatus 1206. The reception component 1202 can provide received communications to one or more other components of the apparatus 1200. In some aspects, the reception component 1202 can perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and can provide the processed signals to the one or more other components of the apparatus 1206. In some aspects, the reception component 1202 can include one or more antennas, a demodulator, a MIMO detector, a receive processor, a controller / processor, a memory, or any combination thereof, of the first UE as described above in connection with FIG. 12.

[0153] The transmission component 1204 can transmit communications, such as reference signals, control information, data communications, or any combination thereof, to the apparatus 1206. In some aspects, one or more other components of the apparatus 1206 can generate communications and can provide the generated communications to the transmission component 1204 for transmission to the apparatus 1206. In some aspects, the transmission component 1204 can perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and can transmit the processed signals to the apparatus 1206. In some aspects, the transmission component 1204 can include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller / processor, a memory, or any combination thereof, of the first UE as described above in connection with FIG. 12. In some aspects, the transmission component 1204 can be co-located with the reception component 1202 in a transceiver. Figure 2 The transmission component 1204 can transmit communications, such as reference signals, control information, data communications, or any combination thereof, to the apparatus 1206. In some aspects, one or more other components of the apparatus 1206 can generate communications and can provide the generated communications to the transmission component 1204 for transmission to the apparatus 1206. In some aspects, the transmission component 1204 can perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and can transmit the processed signals to the apparatus 1206. In some aspects, the transmission component 1204 can include one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller / processor, a memory, or any combination thereof, of the first UE as described above in connection with FIG. 12. In some aspects, the transmission component 1204 can be co-located with the reception component 1202 in a transceiver.

[0154] The transmission component 1204 can transmit, to the second UE via a sidelink interface, a trigger signal associated with triggering HARQ feedback for the sidelink. The reception component 1202 can receive, from the second UE, the HARQ feedback associated with the first UE based at least in part on the trigger signal. The HARQ component 1208 can cause the apparatus 1200 to transmit the trigger signal and / or can interpret the HARQ feedback associated with the first UE.

[0155] The number and arrangement of components shown in FIG. 12 are provided as an example. In practice, there can be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 12. Additionally, or alternatively, two or more components shown in FIG. 12 can be implemented within a single component, or a component shown as a single component can be implemented as multiple, distributed components. Further, it will be appreciated that one or more components of the apparatus 1200 can be combined with one or more components of the apparatus 1206. Figure 12 The number and arrangement of components shown in FIG. 12 are provided as an example. In practice, there can be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 12. Additionally, or alternatively, two or more components shown in FIG. 12 can be implemented within a single component, or a component shown as a single component can be implemented as multiple, distributed components. Further, it will be appreciated that one or more components of the apparatus 1200 can be combined with one or more components of the apparatus 1206. Figure 12 The number and arrangement of components shown in FIG. 12 are provided as an example. In practice, there can be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 12. Additionally, or alternatively, two or more components shown in FIG. 12 can be implemented within a single component, or a component shown as a single component can be implemented as multiple, distributed components. Further, it will be appreciated that one or more components of the apparatus 1200 can be combined with one or more components of the apparatus 1206. Figure 12 The number and arrangement of components shown in FIG. 12 are provided as an example. In practice, there can be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 12. Additionally, or alternatively, two or more components shown in FIG. 12 can be implemented within a single component, or a component shown as a single component can be implemented as multiple, distributed components. Further, it will be appreciated that one or more components of the apparatus 1200 can be combined with one or more components of the apparatus 1206. Figure 12The individual components illustrated in Figure 12 The set of one or more components illustrated in Figure 12 may perform one or more functions described as being performed by another set of components illustrated in

[0156] SUMMARY

[0157] Aspect 1 : A method of wireless communication performed by a first user equipment (UE), comprising: receiving, from a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for a sidelink; and transmitting, to the second UE based at least in part on the trigger signal, HARQ feedback associated with the second UE.

[0158] Aspect 2: The method of aspect 1, wherein the first UE and the second UE are associated with a carrier aggregation configuration, and wherein the HARQ feedback relates to multiple carriers of the carrier aggregation configuration.

[0159] Aspect 3: The method of any one of aspects 1-2, wherein the trigger signal comprises sidelink control information.

[0160] Aspect 4: The method of any one of aspects 1-3, wherein the trigger signal is received via a sidelink control channel, and wherein the sidelink control channel schedules a data transmission in a corresponding sidelink shared channel.

[0161] Aspect 5: The method of any one of aspects 1-3, wherein the trigger signal is received via a sidelink control channel, wherein the sidelink control channel does not schedule a data transmission in a corresponding sidelink shared channel, and wherein a slot comprising the sidelink control channel is entirely allocated for the sidelink control channel.

[0162] Aspect 6: The method of any one of aspects 1-5, wherein the trigger signal is associated with information indicating feedback resources for the HARQ feedback, and wherein the HARQ feedback is transmitted on the feedback resources.

[0163] Aspect 7: The method of any one of aspects 1-6, wherein the HARQ feedback is transmitted via a sidelink shared channel.

[0164] Aspect 8: The method of any one of aspects 1-7, wherein the HARQ feedback relates to each sidelink HARQ process associated with a source identifier of the second UE and each carrier between the first UE and the second UE.

[0165] Aspect 9: The method of any one of aspects 1-8, wherein the trigger signal is received in a given slot, and wherein the HARQ feedback includes feedback only about slots prior to the given slot and the given slot.

[0166] Aspect 10: The method of any one of aspects 1-8, wherein the trigger signal is received in a given slot, and wherein the HARQ feedback includes feedback about slots after the given slot based at least in part on a feedback cutoff time.

[0167] Aspect 11: The method of any one of aspects 1-10, wherein the HARQ feedback is provided in a communication that includes a flag indicating that the communication includes the HARQ feedback.

[0168] Aspect 12: The method of any one of aspects 1-11, wherein the HARQ feedback is based at least in part on the trigger signal, wherein the HARQ feedback is a single-shot HARQ feedback, and wherein the method further comprises: receiving information indicating at least one of that the single-shot HARQ feedback is provided, semi-static HARQ feedback is provided, or dynamic HARQ feedback is provided.

[0169] Aspect 13: The method of any one of aspects 1-12, wherein the received information is specific to at least one of: a resource pool, a sidelink carrier, a sidelink BWP, a traffic cast type, or a zone identifier.

[0170] Aspect 14: The method of any one of aspects 1-13, wherein the HARQ feedback includes one HARQ codebook per unicast link of the first UE and one HARQ codebook per groupcast link of the first UE.

[0171] Aspect 15: The method of any one of aspects 1-14, wherein the HARQ feedback includes one HARQ codebook per source identifier of the first UE.

[0172] Aspect 16: The method of any one of aspects 1-16, further comprising: transmitting information indicating a number of HARQ codebooks that the first UE is capable of generating simultaneously, wherein the HARQ feedback is based at least in part on the number of HARQ codebooks.

[0173] Aspect 17: A method of wireless communication performed by a first user equipment (UE), comprising: transmitting, to a second UE via a sidelink interface, a trigger signal associated with triggering hybrid automatic repeat request (HARQ) feedback for a sidelink; and receiving, from the second UE based at least in part on the trigger signal, HARQ feedback associated with the first UE.

[0174] Aspect 18: The method of aspect 17, wherein the first UE and the second UE are associated with a carrier aggregation configuration, and wherein the HARQ feedback relates to multiple carriers of the carrier aggregation configuration.

[0175] Aspect 19: The method of any one of aspects 17-18, wherein the trigger signal is relayed from a base station via the first UE.

[0176] Aspect 20: The method of any one of aspects 17-19, wherein the trigger signal is transmitted via a sidelink control channel, wherein the sidelink control channel does not schedule a data transmission in a corresponding sidelink shared channel, and wherein a slot including the sidelink control channel is fully allocated for the sidelink control channel.

[0177] Aspect 21: The method of any one of aspects 17-20, wherein the trigger signal is associated with information indicating feedback resources for the HARQ feedback, and wherein the HARQ feedback is transmitted on the feedback resources.

[0178] Aspect 22: The method of any one of aspects 17-21, wherein the HARQ feedback relates to each sidelink HARQ process associated with a source identifier of the first UE and each carrier between the first UE and the second UE.

[0179] Aspect 23: The method of any one of aspects 17-22, wherein the trigger signal is transmitted in a given slot, and wherein the HARQ feedback includes feedback only about slots preceding the given slot and the given slot.

[0180] Aspect 24: The method of any one of aspects 17-22, wherein the trigger signal is transmitted in a given slot, and wherein the HARQ feedback includes feedback about slots following the given slot based at least in part on a feedback cutoff time.

[0181] Aspect 25: The method of any one of aspects 17-24, wherein the HARQ feedback is received in a communication that includes a flag indicating that the communication includes the HARQ feedback.

[0182] Aspect 26: The method according to any one of Aspects 17-25, wherein the HARQ feedback is at least partially based on the trigger signal, wherein the HARQ feedback is a single HARQ feedback, and wherein the method further comprises: sending information indicating that at least one of the single HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback is provided.

[0183] Aspect 27: The method according to any one of Aspects 17-26, wherein the HARQ feedback includes a HARQ codebook for each unicast link of the first UE and a HARQ codebook for each multicast link of the first UE.

[0184] Aspect 28: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to one or more of aspects 1-27.

[0185] Aspect 29: An apparatus for wireless communication, comprising a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to perform the method according to one or more of aspects 1-27.

[0186] Aspect 30: An apparatus for wireless communication, comprising at least one unit for performing the method according to one or more of aspects 1-27.

[0187] Aspect 31: A non-transitory computer-readable medium storing code for wireless communication, said code including instructions executable by a processor to perform the methods described in one or more of aspects 1-27.

[0188] Aspect 32: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform the method according to one or more aspects of aspects 1-27.

[0189] The foregoing disclosure provides explanations and descriptions, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made based on the foregoing disclosure, or modifications and variations may be derived from practice in the aspects.

[0190] As used herein, the term “component” is intended to be broadly interpreted to include hardware and / or a combination of hardware and software. “Software” shall be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, and / or functions, among other examples, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. As used herein, a processor is implemented in hardware and / or a combination of hardware and software. It will be apparent that systems and / or methods described herein can be implemented in different forms of hardware and / or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and / or methods were described herein without reference to specific software code — it is understood that software and hardware can be designed to implement the systems and / or methods based, at least in part, on the description herein.

[0191] As used herein, depending on the context, satisfying a threshold can refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and / or the like.

[0192] Even if a particular combination is not recited in the claims and / or disclosed in the specification, the combination can still be claimed and / or disclosed in the specification. Although each dependent claim listed below can only directly depend from one claim, the disclosure of each aspect includes combinations of each dependent claim with every other claim in the set of claims. As used herein, a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination of items from among a, b, and c (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

[0193] No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and can be used interchangeably with “one or more.” Furthermore, as used herein, the article “the” is intended to include one or more items, and can be used interchangeably with “the one or more.” Also, as used herein, the terms “set” and “group” are intended to include one or more items (for example, related items, unrelated items, or a combination of related and unrelated items), and can be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series of items (for example, “a, b, or c” or “a, b, and c”) unless explicitly stated otherwise (for example, if used in the context of “one of a, b, or c,” then “or” is used in the exclusive sense).

Claims

1. A first user equipment (UE) for wireless communication, comprising: Memory; as well as One or more processors are operatively coupled to the memory, and the memory and the one or more processors are configured to: Receives from the second UE via the sidelink interface a trigger signal associated with triggering Hybrid Automatic Repeat Request (HARQ) feedback for the sidelink; and At least in part, based on the trigger signal, HARQ feedback associated with the second UE is sent to the second UE; The trigger signal is received in the physical link control channel (PSCCH) on the physical side. Wherein, when the PSCCH does not schedule data transmission in the sidelink shared channel corresponding to the PSCCH, the entire time slot in which the sidelink control information (SCI) conveying the trigger signal and carried by the PSCCH is received is dedicated to the SCI, and The HARQ feedback includes feedback only regarding the time slots preceding the entire time slot and the entire time slot.

2. The first UE according to claim 1, wherein, The first UE and the second UE are associated with a carrier aggregation configuration, and the HARQ feedback involves multiple carriers of the carrier aggregation configuration.

3. The first UE according to claim 1, wherein, The SCI includes bits indicating that the SCI includes the trigger signal or that the SCI is the trigger signal.

4. The first UE according to claim 1, wherein, The one or more processors are further configured to: The PSCCH is decoded in the time slot following the entire time slot.

5. The first UE according to claim 1, wherein, The one or more processors are further configured to: The transport block (TB) is received after the HARQ feedback is triggered and before the HARQ feedback is sent.

6. The first UE according to claim 1, wherein, The trigger signal is associated with information indicating a feedback resource for the HARQ feedback, wherein the HARQ feedback is sent on the feedback resource.

7. The first UE according to claim 1, wherein, The HARQ feedback is transmitted via the side link shared channel.

8. The first UE according to claim 1, wherein, The HARQ feedback involves each sidelink HARQ process associated with the source identifier of the second UE and each carrier between the first UE and the second UE.

9. The first UE according to claim 1, wherein, The trigger signal includes information indicating the physical side link feedback channel (PSFCH) resources used for the HARQ feedback.

10. The first UE according to claim 1, wherein, The side link shared channel is the Physical Side Link Shared Channel (PSSCH).

11. The first UE according to claim 1, wherein, The HARQ feedback is provided in a communication that includes a flag indicating that the communication includes the HARQ feedback.

12. The first UE according to claim 1, wherein, The HARQ feedback is at least partially based on the trigger signal, wherein the HARQ feedback is a single HARQ feedback, and wherein the first UE is configured to: The receiving instruction provides information on at least one of the single HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback.

13. The first UE according to claim 12, wherein, The received information is specific to at least one of the following: Resource pool Side link carrier, Side link bandwidth portion, Service broadcast type, or Region identifier.

14. The first UE according to claim 1, wherein, The HARQ feedback includes a HARQ codebook for each unicast link of the first UE and a HARQ codebook for each multicast link of the first UE.

15. The first UE according to claim 1, wherein, The HARQ feedback includes a HARQ codebook for each source identifier of the first UE.

16. The first UE according to claim 1, wherein, The one or more processors are further configured to: Information indicating the number of HARQ codebooks that the first UE can generate simultaneously is sent, wherein the HARQ feedback is at least partially based on the number of HARQ codebooks.

17. A first user equipment (UE) for wireless communication, comprising: Memory; as well as One or more processors are operatively coupled to the memory, and the memory and the one or more processors are configured to: Sending a trigger signal associated with triggering Hybrid Automatic Repeat Request (HARQ) feedback for the sidelink to the second UE via the sidelink interface; and The HARQ feedback associated with the first UE is received from the second UE at least in part based on the trigger signal; The trigger signal is sent in the physical link control channel (PSCCH) on the physical side. Specifically, when the PSCCH does not schedule data transmission in the sidelink shared channel corresponding to the PSCCH, the entire time slot in which the sidelink control information (SCI) conveying the trigger signal and carried by the PSCCH is transmitted is dedicated to the SCI, and The HARQ feedback includes feedback only regarding the time slots preceding the entire time slot and the entire time slot.

18. The first UE according to claim 17, wherein, The first UE and the second UE are associated with a carrier aggregation configuration, and the HARQ feedback involves multiple carriers of the carrier aggregation configuration.

19. The first UE according to claim 17, wherein, The trigger signal is relayed from the base station via the first UE.

20. The first UE according to claim 17, wherein, The trigger signal is associated with information indicating a feedback resource for the HARQ feedback, wherein the HARQ feedback is sent on the feedback resource.

21. The first UE according to claim 17, wherein, The HARQ feedback involves each sidelink HARQ process associated with the source identifier of the first UE and each carrier between the first UE and the second UE.

22. The first UE according to claim 17, wherein, The SCI includes bits indicating that the SCI includes the trigger signal or that the SCI is the trigger signal.

23. The first UE according to claim 17, wherein, The side link shared channel is the Physical Side Link Shared Channel (PSSCH).

24. The first UE according to claim 17, wherein, The HARQ feedback is received in a communication that includes a flag indicating that the communication includes the HARQ feedback.

25. The first UE according to claim 17, wherein, The HARQ feedback is at least partially based on the trigger signal, wherein the HARQ feedback is a single HARQ feedback, and wherein the first UE is configured to: The sending instruction provides information on at least one of the single HARQ feedback, semi-static HARQ feedback, or dynamic HARQ feedback.

26. The first UE according to claim 17, wherein, The HARQ feedback includes a HARQ codebook for each unicast link of the first UE and a HARQ codebook for each multicast link of the first UE.

27. A method for wireless communication performed by a first user equipment (UE), comprising: Receives a trigger signal from the second UE via the sidelink interface, which is associated with triggering the Hybrid Automatic Repeat Request (HARQ) feedback for the sidelink. as well as At least in part, based on the trigger signal, HARQ feedback associated with the second UE is sent to the second UE; The trigger signal is received in the physical link control channel (PSCCH) on the physical side. Wherein, when the PSCCH does not schedule data transmission in the sidelink shared channel corresponding to the PSCCH, the entire time slot in which the sidelink control information (SCI) conveying the trigger signal and carried by the PSCCH is received is dedicated to the SCI, and The HARQ feedback includes feedback only regarding the time slots preceding the entire time slot and the entire time slot.

28. The method according to claim 27, wherein, The SCI includes bits indicating that the SCI includes the trigger signal or that the SCI is the trigger signal.

29. A method for wireless communication performed by a first user equipment (UE), comprising: Send a trigger signal associated with triggering Hybrid Automatic Repeat Request (HARQ) feedback for the side link to the second UE via the side link interface; as well as The HARQ feedback associated with the first UE is received from the second UE at least in part based on the trigger signal; The trigger signal is sent in the physical link control channel (PSCCH) on the physical side. Specifically, when the PSCCH does not schedule data transmission in the sidelink shared channel corresponding to the PSCCH, the entire time slot in which the sidelink control information (SCI) conveying the trigger signal and carried by the PSCCH is transmitted is dedicated to the SCI, and The HARQ feedback includes feedback only regarding the time slots preceding the entire time slot and the entire time slot.

30. The method according to claim 29, wherein, The SCI includes bits indicating that the SCI includes the trigger signal or that the SCI is the trigger signal.

Images