Hybrid automatic repeat request response for primary carrier assisted sidelink access

Abstract

In general, various aspects of the present disclosure relate to wireless communications. In some aspects, a first user equipment (UE) may send an indication to a second UE via a sidelink subchannel of a primary carrier identifying one or more resources on the primary carrier for sending one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and receive one or more HARQ responses for the one or more sidelink communications on the secondary carrier from the second UE on the one or more resources on the primary carrier. Many other aspects are provided.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 055,143, filed on July 22, 2020, entitled “HYBRID AUTOMATIC REPEAT REQUEST RESPONSES FOR LICENSED ASSISTED SIDELINK ACCESS,” and U.S. Non-Provisional Patent Application No. 17 / 304,426, filed on June 21, 2021, entitled “HYBRID AUTOMATIC REPEAT REQUESTRESPONSES FOR PRIMARY CARRIER ASSISTED SIDELINK ACCESS,” which are expressly incorporated herein by reference. Technical Field

[0003] Aspects of the present disclosure relate generally to wireless communications and to techniques and apparatus for hybrid automatic repeat request responses for primary carrier assisted sidelink access. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies capable of supporting 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 / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0005] A wireless network may include multiple base stations (BSs) capable of supporting communications for multiple user equipment (UEs). The UEs may communicate with the BSs via downlinks and uplinks. A "downlink" (or "forward link") refers to the communication link from the BS to the UEs, and an "uplink" (or "reverse link") refers to the communication link from the UEs to the BSs. As will be described in greater detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit receive point (TRP), new radio (NR) BS, 5G Node B, etc.

[0006] The above-mentioned multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user devices to communicate at the city, country, region, and even global levels. NR, also known as 5G, is a set of enhancements to the LTE mobile standard released by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards that use orthogonal frequency division multiplexing (CP-OFDM) with a cyclic prefix (CP) on the downlink (DL) and CP-OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. As the demand for mobile broadband access continues to grow, further improvements to LTE, NR, and other wireless access technologies remain useful. Summary of the Invention

[0007] In some aspects, a method of wireless communication performed by a first user equipment (UE) includes: sending an indication to a second UE via a sidelink subchannel of the primary carrier identifying one or more resources on the primary carrier for sending one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and receiving one or more HARQ responses for the one or more sidelink communications on the secondary carrier from the second UE on the one or more resources on the primary carrier.

[0008] In some aspects, a method of wireless communication performed by a second UE includes: receiving an indication from a first UE via a sidelink subchannel of a primary carrier on how to send one or more HARQ responses on the primary carrier for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and sending one or more HARQ responses on the primary carrier to the first UE for the one or more sidelink communications on the secondary carrier based at least in part on the indication.

[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: send an indication to a second UE via a sidelink subchannel of the primary carrier identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and receive, from the second UE on the one or more resources on the primary carrier, the one or more HARQ responses for the one or more sidelink communications on the secondary carrier.

[0010] In some aspects, a second 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 first UE via a sidelink subchannel of a primary carrier, an indication of how to send one or more HARQ responses on the primary carrier for one or more sidelink communications between the first UE and a second UE on a secondary carrier; and send, to the first UE on the primary carrier, the one or more HARQ responses for the one or more sidelink communications on the secondary carrier based at least in part on the indication.

[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: send, to a second UE via a sidelink subchannel of the primary carrier, an indication identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and receive, from the second UE on the one or more resources on the primary carrier, the one or more HARQ responses for the one or more sidelink communications on the secondary carrier.

[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 second UE, cause the second UE to: receive, from a first UE via a sidelink subchannel of a primary carrier, an indication of how to send, on the primary carrier, one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and send, to the first UE on the primary carrier, one or more HARQ responses for the one or more sidelink communications on the secondary carrier based at least in part on the indication.

[0013] In some aspects, an apparatus for wireless communication includes: means for sending, to a second UE via a sidelink subchannel of the primary carrier, an indication identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between a first UE and a second UE on a secondary carrier; and means for receiving, from the second UE on the one or more resources on the primary carrier, the one or more HARQ responses for the one or more sidelink communications on the secondary carrier.

[0014] In some aspects, an apparatus for wireless communication includes: a unit for receiving, via a sidelink subchannel of a primary carrier, an indication from a first UE of how to send one or more HARQ responses on the primary carrier for one or more sidelink communications between the first UE and a second UE on a secondary carrier; and a unit for sending, on the primary carrier, the one or more HARQ responses to the first UE for the one or more sidelink communications on the secondary carrier based at least in part on the indication.

[0015] Aspects generally include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems as generally described herein with reference to and as illustrated in the accompanying figures and description.

[0016] The foregoing has summarized the features and technical advantages of the examples according to the present disclosure in a fairly broad sense so that the following detailed description can be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples can be easily used as the basis for modifying or designing other structures for achieving the same purpose of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. When considered in conjunction with the accompanying drawings, the features of the concepts disclosed herein (their organization and method of operation) and the related advantages will be better understood from the following description. Each of the drawings is provided for the purpose of illustration and description and not as a definition of the scope of the claims.

[0017] Although aspects are described in the present disclosure by way of illustrations of some examples, it will be understood by those skilled in the art that such aspects can be implemented in many other arrangements and scenarios. The technology described herein can be implemented using different platform types, devices, systems, shapes, sizes, and / or packaging arrangements. For example, some aspects can be implemented via integrated chip embodiments or other devices based on non-module components (e.g., end-user devices, vehicles, communication devices, computing devices, industrial devices, retail / purchase devices, medical devices, or devices enabled by artificial intelligence). Aspects can be implemented in chip-level components, modular components, non-modular components, non-chip-level components, device-level components, or system-level components. The device incorporating the aspects and features may include additional components and features for the implementation and practice of the claimed and described aspects. For example, the transmission and reception of wireless signals may include multiple components for analog and digital purposes (e.g., hardware components including antennas, radio frequency (RF) chains, power amplifiers, modulators, buffers, processors, interleavers, adders, or summers). The aspects described herein are intended to be practiced in various devices, components, systems, distributed arrangements, or end-user devices of different sizes, shapes, and configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order that the features of the present disclosure described above may be understood in detail, reference may be made to the more detailed description summarized above of various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of the present disclosure and are not therefore to be considered limiting of its scope, as the description may admit of other equally valid aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0019] Figure 1 is a schematic diagram illustrating aspects of a wireless network according to the present disclosure.

[0020] Figure 2 is a schematic diagram illustrating aspects of a base station communicating with a user equipment (UE) in a wireless network according to the present disclosure.

[0021] Figure 3 is a schematic diagram illustrating aspects of sidelink communications according to the present disclosure.

[0022] Figure 4 is a schematic diagram illustrating aspects of sidelink communications and access link communications according to the present disclosure.

[0023] Figure 5 is a schematic diagram illustrating aspects of carrier aggregation according to the present disclosure.

[0024] Figure 6 is a schematic diagram illustrating aspects of physical sidelink feedback channel (PSFCH) resource determination according to the present disclosure.

[0025] Figure 7 is a diagram illustrating aspects of sidelink access with licensed and unlicensed carriers in accordance with the present disclosure.

[0026] Figure 8-13 is a diagram illustrating aspects associated with a hybrid automatic repeat request (HARQ) response for primary carrier assisted sidelink access in accordance with the present disclosure.

[0027] Figure 14-15 is a diagram illustrating aspect procedures associated with HARQ responses for primary carrier assisted sidelink access according to the present disclosure. DETAILED DESCRIPTION

[0028] The various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be implemented in different forms and should not be understood as being limited to any specific structure or function presented throughout the present disclosure. On the contrary, these aspects are provided so that the present disclosure is sufficient and complete, and the scope of the present disclosure is conveyed to those skilled in the art in a comprehensive manner. According to the teachings herein, those skilled in the art should recognize that, whether independent of any other aspects of the present disclosure or in combination with any other aspects of the present disclosure, the scope of the present disclosure is intended to cover any aspect of the disclosure disclosed herein. In some aspects, any number of aspects set forth herein can be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices and methods that are practiced using other structures, functional bodies, or structures and functional bodies in addition to or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein can be embodied by one or more elements of the claims.

[0029] Several aspects of telecommunications systems will now be presented with reference to various devices and techniques. These devices and techniques 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, "elements"). These elements can be implemented in hardware, software, or a combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0030] It should be noted that although terms generally associated with 5G or NR radio access technology (RAT) may be used herein to describe aspects, aspects of the present disclosure may be applied to other RATs, such as 3G RAT, 4G RAT, and / or RATs beyond 5G (e.g., 6G).

[0031] Figure 1 1 is a schematic diagram illustrating aspects of a wireless network 100 according to the present disclosure. The wireless network 100 may be or may include elements of a 5G (NR) network and / or an LTE network, among other things. The wireless network 100 may include a plurality of base stations 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A base station (BS) is an entity that communicates with a user equipment (UE) and may also be referred to as an NR BS, Node B, gNB, 5G Node B (NB), access point, transmit receive point (TRP), etc. Each BS may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to a coverage area of ​​a BS and / or a BS subsystem serving that coverage area, depending on the context in which the term is used.

[0032] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1 In the aspect shown in , BS 110a may be a macro BS for macrocell 102a, BS 110b may be a pico BS for picocell 102b, and BS 110c may be a femto BS for femtocell 102c. A BS may support one or more (e.g., three) cells. The terms "eNB," "base station," "NR BS," "gNB," "TRP," "AP," "Node B," "5G NB," and "cell" may be used interchangeably herein.

[0033] In some aspects, cells may not necessarily be stationary, and the geographic area of ​​a cell may move depending on the location of a mobile BS. In some aspects, BSs may interconnect with each other and / or one or more other BSs or network nodes (not shown) in wireless network 100 using any suitable transport network over various types of backhaul interfaces, such as direct physical connections or virtual networks.

[0034] The wireless network 100 may also include a relay station. A relay station is an entity that receives transmissions of data from an upstream station (e.g., a BS or a UE) and sends transmissions of data to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that can relay transmissions for other UEs. Figure 1 In the aspect shown in FIG, relay BS 110d may communicate with macro BS 110a and UE 120d to facilitate communication between BS 110a and UE 120d. A relay BS may also be referred to as a relay station, relay base station, relay, etc.

[0035] The wireless network 100 may be a heterogeneous network including different types of BSs, such as macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network 100. In some aspects, the macro BS may have a high transmit power level (e.g., 5 to 40 watts), while the pico BS, femto BS, and relay BS may have a lower transmit power level (e.g., 0.1 to 2 watts).

[0036] The network controller 130 may be coupled to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with each other directly or indirectly, for example, via a wireless or wired backhaul.

[0037] UEs 120 (e.g., 120a, 120b, 120c) may be distributed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, terminal, mobile station, user equipment, station, etc. A UE may be a cellular phone (e.g., a smartphone), 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 computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biosensor / device, a wearable device (e.g., a smart watch, smart clothing, smart glasses, a smart wristband, smart jewelry (e.g., a smart ring, a smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium.

[0038] Some UEs may be considered machine type communication (MTC) or evolved or enhanced machine type communication (eMTC) UEs. In some aspects, MTC and eMTC UEs include robots, drones, remote devices, sensors, meters, monitors, and / or location tags that can communicate with a base station, another device (e.g., a remote device), or some other entity. In some aspects, a wireless node may provide a connection to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices and / or may be implemented as NB-IoT (Narrowband Internet of Things) devices. Some UEs may be considered customer premises equipment (CPE). UE 120 may be included within a housing that houses components of UE 120, such as a processor component and / or a memory component. In some aspects, the processor component and the memory component may be coupled together. In some aspects, the processor component (e.g., one or more processors) and the memory component (e.g., memory) may 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 specific RAT and can operate on one or more frequencies. A RAT may also be referred to as a radio technology, air interface, etc. A frequency may also be referred to as a carrier, frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0040] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) can communicate directly (e.g., without using base station 110 as an intermediary) using one or more sidelink channels. In some aspects, UEs 120 can communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols or vehicle-to-infrastructure (V2I) protocols), and / or mesh networks. In this case, UE 120 can perform scheduling operations, resource selection operations, and / or other operations performed by base station 110 as described elsewhere herein.

[0041] The devices of the wireless network 100 can communicate using an electromagnetic spectrum, which can be subdivided into various categories, frequency bands, channels, etc. based on frequency or wavelength. In some aspects, the devices of the wireless network 100 can communicate using an operating frequency band having a first frequency range (FR1) (which can span 410 MHz to 7.125 GHz) and / or can communicate using an operating frequency band having a second frequency range (FR2) (which can span 24.25 GHz to 52.6 GHz). 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, although it is different from the extremely high frequency (EHF) band (30 GHz-300 GHz) identified as a "millimeter wave" band by the International Telecommunication Union (ITU). Thus, unless otherwise expressly stated, it should be understood that the terms "sub-6 GHz," etc., if used herein, may broadly refer to frequencies less than 6 GHz, frequencies within FR1, and / or mid-band frequencies (e.g., greater than 7.125 GHz). Similarly, unless otherwise expressly stated, it should be understood that the terms "millimeter wave," etc., if used herein, may broadly refer to 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 may be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0042] As pointed out above, Figure 1 Provided as aspects. Other aspects may differ from those regarding Figure 1 Aspects described.

[0043] Figure 2 is a diagram illustrating aspects 200 of a base station 110 communicating with a UE 120 in a wireless network 100 according to the present disclosure. The base station 110 may be equipped with T antennas 234a through 234t, and the UE 120 may be equipped with R antennas 252a through 252r, where, in general, T ≥ 1 and R ≥ 1.

[0044] At the base station 110, a transmit processor 220 may receive data for one or more UEs from a data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indicator (CQI) 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. The transmit processor 220 may 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. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS) or demodulation reference signals (DMRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). If applicable, a transmit (TX) multiple-input, multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator 232 may further process the output sample stream (e.g., convert to analog, amplify, filter, and frequency upconvert) to obtain a downlink signal. The T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

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

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

[0047] The antennas (e.g., antennas 234a to 234t and / or antennas 252a to 252r) may include, or may be included within, one or more antenna panels, antenna groups, collections of antenna elements, and / or antenna arrays, etc. The antenna panels, antenna groups, collections of antenna elements, and / or antenna arrays may include one or more antenna elements. The antenna panels, antenna groups, collections of antenna elements, and / or antenna arrays may include a collection of coplanar antenna elements or a collection of non-coplanar antenna elements. The antenna panels, antenna groups, collections of antenna elements, and / or antenna arrays may include antenna elements within a single housing and / or antenna elements within multiple housings. The antenna panels, antenna groups, collections of antenna elements, and / or antenna arrays may include antenna elements coupled to one or more transmit and / or receive components (e.g., Figure 2 One or more antenna elements of one or more components in.

[0048] On the uplink, at the UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports including RSRP, RSSI, RSRQ, and / or CQI) from the controller / processor 280. The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may 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 the base station 110. In some aspects, the modulator and demodulator (e.g., MOD / DEMOD 254) of the UE 120 may be included in a modem of the UE 120. In some aspects, the UE 120 includes a transceiver. The transceiver may include any combination of antenna(s) 252, modulator and / or demodulator 254, MIMO detector 256, receive processor 258, transmit processor 264, and / or TX MIMO processor 266. The transceiver may be used by a processor (e.g., controller / processor 280) and memory 282 to perform aspects of any of the methods described herein (e.g., as described with reference to FIG. Figure 8-15 described).

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

[0050] As described in greater detail elsewhere herein, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other components of FIG. 2 may perform one or more techniques associated with a hybrid automatic repeat request (HARQ) response for primary carrier assisted sidelink access. In some aspects, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other components of FIG. 2 may perform or direct (in some aspects) Figure 14 The process of 1400 Figure 15 1500 and / or other processes described herein. Memories 242 and 282 may store data and program codes 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 communications. In some aspects, the 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, conversion, and / or interpretation), may cause the one or more processors, UE 120, and / or base station 110 to perform or direct (in some aspects) Figure 14 The process of 1400 Figure 15 The operations of process 1500 and / or other processes described herein may be performed. In some aspects, executing instructions may include running instructions, converting instructions, compiling instructions, and / or interpreting instructions.

[0051] In some aspects, UE 120 may include: a unit for sending an indication to a second UE via a sidelink subchannel of the primary carrier identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on the secondary carrier; and / or a unit for receiving one or more HARQ responses for one or more sidelink communications on the secondary carrier from the second UE on one or more resources on the primary carrier. Additionally or alternatively, UE 120 may include: a unit for receiving from the first UE via a sidelink subchannel of the primary carrier an indication of how to send one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on the secondary carrier on the primary carrier; and / or a unit for sending one or more HARQ responses for one or more sidelink communications on the secondary carrier to the first UE on the primary carrier based at least in part on the indication. In some aspects, such a unit may include a unit in combination with Figure 2One or more components of UE 120 are depicted, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, and / or receive processor 258.

[0052] Although Figure 2 The blocks in FIG. 2 are shown as distinct components, but the functionality described above with reference to the blocks may be implemented in a single hardware, software, or combined component or in various combinations of components. In some aspects, the functionality described with reference to the transmit processor 264, the receive processor 258, and / or the TX MIMO processor 266 may be performed by or under the control of the controller / processor 280.

[0053] As pointed out above, Figure 2 Provided as aspects. Other aspects may differ from those regarding Figure 2 Aspects described.

[0054] Figure 3 is a schematic diagram illustrating aspects 300 of sidelink communications according to the present disclosure.

[0055] like Figure 3 As shown in FIG, a first UE 305-1 can communicate with a second UE 305-2 (and one or more other UEs 305) via one or more sidelink channels 310. UEs 305-1 and 305-2 can communicate using one or more sidelink channels 310 for P2P communication, D2D communication, V2X communication (e.g., which can include V2V communication, V2I communication, and / or vehicle-to-pedestrian (V2P) communication), and / or mesh networking, among others. In some aspects, UEs 305 (e.g., UE 305-1 and / or UE 305-2) can correspond to one or more other UEs described elsewhere herein (e.g., UE 120). In some aspects, one or more sidelink channels 310 can use a PC5 interface and / or can operate in a high frequency band (e.g., a 5.9 GHz band). Additionally or alternatively, the UE 305 can synchronize the timing of transmission time intervals (TTIs) (eg, frames, subframes, slots, and / or symbols) using Global Navigation Satellite System (GNSS) timing.

[0056] like Figure 3As further shown in FIG, one or more sidelink channels 310 may include a physical sidelink control channel (PSCCH) 315, a physical sidelink shared channel (PSSCH) 320, and / or a physical sidelink feedback channel (PSFCH) 325. The PSCCH 315 may be used to transmit control information, similar to the physical downlink control channel (PDCCH) and / or physical uplink control channel (PUCCH) used for cellular communication with the base station 110 via an access link or access channel. The PSSCH 320 may be used to transmit data, similar to the physical downlink shared channel (PDSCH) and / or physical uplink shared channel (PUSCH) used for cellular communication with the base station 110 via an access link or access channel. In some aspects, the PSCCH 315 may carry sidelink control information (SCI) 330, which may indicate various control information for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, and / or space resources), wherein a transport block (TB) 335 may be carried on the PSSCH 320. The TB 335 may include data. The PSFCH 325 may be used to transmit sidelink feedback 340, such as HARQ feedback (eg, acknowledgement or negative acknowledgement (ACK / NACK) information), transmit power control (TPC), and / or scheduling requests (SRs).

[0057] In some aspects, one or more sidelink channels 310 may utilize a resource pool. In some aspects, a scheduling assignment (e.g., included in SCI 330) may be transmitted in a subchannel using specific resource blocks (RBs) across time. In some aspects, a data transmission associated with a scheduling assignment (e.g., on PSSCH 320) may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and the associated data transmission are not transmitted on adjacent RBs.

[0058] In some aspects, the UE 305 may operate using a transmission mode in which resource selection and / or scheduling is performed by the UE 305 (e.g., rather than the base station 110). In some aspects, the UE 305 may perform resource selection and / or scheduling by sensing channel availability for transmission. In some aspects, the UE 305 may measure an RSSI parameter associated with various sidelink channels (e.g., a Sidelink-RSSI (S-RSSI) parameter), may measure an RSRP parameter associated with various sidelink channels (e.g., a PSSCH-RSRP parameter), may measure an RSRQ parameter associated with various sidelink channels (e.g., a PSSCH-RSRQ parameter), and may select a channel for transmission of sidelink communications based at least in part on the measurements.

[0059] Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling using the SCI 330 received in the PSCCH 315, which may indicate occupied resources and / or channel parameters. Additionally or alternatively, the UE 305 may perform resource selection and / or scheduling by determining a channel busy rate (CBR) associated with each sidelink channel, which may be used for rate control (e.g., by indicating a maximum number of resource blocks that the UE 305 may use for a particular set of subframes).

[0060] In a transmission mode in which resource selection and / or scheduling is performed by the UE 305, the UE 305 may generate a sidelink grant and may send the grant in the SCI 330. In some aspects, the sidelink grant may indicate 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 on the PSSCH 320 (e.g., for TB 335), one or more subframes to be used for the upcoming sidelink transmission, and an MCS to be used for the upcoming sidelink transmission. In some aspects, the UE 305 may generate a sidelink grant that indicates one or more parameters for semi-persistent scheduling (SPS), such as the periodicity of the sidelink transmission. Additionally or alternatively, the UE 305 may generate a sidelink grant for event-driven scheduling, such as for an on-demand sidelink message.

[0061] As pointed out above, Figure 3 Provided as aspects. Other aspects may differ from those regarding Figure 3 Aspects described.

[0062] Figure 4 is a schematic diagram illustrating aspects 400 of sidelink and access link communications in accordance with the present disclosure.

[0063] like Figure 4 As shown in FIG, the transmitting (Tx) / receiving (Rx) UE 405 and the Rx / Tx UE 410 can communicate with each other via a side link, as described above in conjunction with Figure 3 As further shown, in some sidelink modes, the 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 communicate with one or more UEs described elsewhere herein, such as Figure 1120). Therefore, a direct link between UEs 120 (e.g., via a PC5 interface) may be referred to as a sidelink, and a direct link between base station 110 and UE 120 (e.g., via a Uu interface) may be referred to as an access link. Sidelink communications may be sent via a sidelink, and access link communications may be sent via an access link. Access link communications may be downlink communications (from base station 110 to UE 120) or uplink communications (from UE 120 to base station 110).

[0064] As pointed out above, Figure 4 Provided as aspects. Other aspects may differ from those regarding Figure 4 Aspects described.

[0065] Figure 5 is a schematic diagram illustrating aspects 500 of carrier aggregation according to the present disclosure.

[0066] Carrier aggregation is a technique that enables two or more component carriers (CCs, sometimes referred to as carriers) to be combined (e.g., into a single channel) for use with a single UE 120, thereby increasing data capacity. As shown, the carriers can be combined in the same or different frequency bands. Additionally or alternatively, contiguous or non-contiguous carriers can be combined. Base station 110 can configure carrier aggregation for UE 120, such as in an RRC message and / or downlink control information (DCI).

[0067] As indicated by reference numeral 505, in some aspects, carrier aggregation may be configured in an intra-band contiguous mode, where the aggregated carriers are contiguous with each other and in the same frequency band. As indicated by reference numeral 510, in some aspects, carrier aggregation may be configured in an intra-band non-contiguous mode, where the aggregated carriers are non-contiguous with each other and in the same frequency band. As indicated by reference numeral 515, in some aspects, carrier aggregation may be configured in an inter-band non-contiguous mode, where the aggregated carriers are non-contiguous with each other and in different frequency bands.

[0068] In carrier aggregation, a UE 120 may be configured with a primary carrier and one or more secondary carriers. In some aspects, the primary carrier may carry control information (e.g., DCI and / or scheduling information) for scheduling data communications on one or more secondary carriers, which may be referred to as cross-carrier scheduling. In some aspects, a carrier (e.g., a primary carrier or a secondary carrier) may carry control information for scheduling data communications on the carrier, which may be referred to as self-carrier scheduling or carrier self-scheduling.

[0069] As pointed out above, Figure 5Provided as aspects. Other aspects may differ from those regarding Figure 5 Aspects described.

[0070] Figure 6 is a diagram illustrating aspects 600 of PSFCH resource determination according to the present disclosure.

[0071] like Figure 6 As shown in , the Tx UE may send PSSCH communications to the RX UE via a sidelink subchannel. To ensure the reliability of the sidelink communications, the Rx UE may send a one-bit HARQ response for the PSSCH communications to the Tx UE on the PSFCH. The Tx UE and / or the Rx UE may communicate with one or more UEs described elsewhere herein (such as Figure 1 corresponding to UE 120).

[0072] In some aspects, the Rx UE may use an implicit resource determination mechanism to determine the resources in the PSFCH for sending the HARQ response. The PSFCH resources for the HARQ response may be arranged at regular time slot intervals. In some aspects, the PSFCH resources may be arranged every one, two, or four time slots in the time domain. Figure 6 In the aspect shown in , a PSFCH opportunity may be allocated every two time slots. A corresponding frequency-division multiplexed PSFCH resource group may be allocated for PSSCHs transmitted on the same subchannel index but at different time slots. Figure 6 As shown in , Z physical resource blocks (PRBs) can be allocated for PSSCH communication transmitted at a particular time slot. Y cyclic shifts can be configured for each PRB. Accordingly, the Z PRBs include (Z*Y) resources for transmitting HARQ responses.

[0073] The Rx UE may use a hash function to select a resource that may be used to send a HARQ response for a PSSCH communication from among (Z*Y) possible resources. In some aspects, the Rx UE may select a resource having an index determined as (K+M) modulo (Z*Y) for sending a HARQ response for a PSSCH communication, where K is a layer 1 (L1) source identifier (ID) of the PSSCH and M is 0 for a unicast PSSCH or a member ID for a groupcast PSSCH.

[0074] As pointed out above, Figure 6 Provided as aspects. Other aspects may differ from those regarding Figure 6 Aspects described.

[0075] Figure 7is a diagram illustrating aspects 700 of sidelink access with a licensed carrier 705 and an unlicensed carrier 710 according to the present disclosure. Figure 7 , UEs 715 (e.g., UE 715-1, UE 715-2, UE 715-3, and UE 715-4) can communicate with each other at various times via a licensed carrier 705 using sidelink communications (also referred to as sidelink access or simply sidelink). Such sidelink communications may occur in the presence of an unlicensed carrier 710 (which may coexist with other RATs). In some aspects, one of the RATs in the unlicensed carrier 710 may be a WiFi network, and the WiFi network may have devices operating in the unlicensed carrier 710, such as WiFi devices 720.

[0076] At various times, certain UE devices may be communicating with each other via sidelinks. In some aspects, during a given time as shown, UE 715-1 may be in sidelink communication with UE 715-2, and UE 715-3 may be in sidelink communication with UE 715-4. Such sidelink communications may occur without involving a base station. In some aspects, such UEs may be in radio resource allocation (RRA) Mode 2 sidelink communication, which allows for independent deployment of UEs, wherein the UEs may sense to occupy and reserve channel access (as opposed to RRA Mode 1 sidelink communication, wherein network control is used and the UE receives a grant for channel access from, for example, a gNB).

[0077] Today, sidelink communications are primarily used in the V2X domain. As sidelink use cases evolve in the vertical domain rather than the V2X domain, the ever-increasing amount of data transmission will place an ever-increasing burden on the licensed spectrum (e.g., licensed carrier 705). Offloading of data to unlicensed spectrum (e.g., unlicensed carrier 710) is seen as a way to address the data bandwidth limitations of the licensed spectrum. However, the transmission of HARQ responses for sidelink communications in the unlicensed spectrum is not as efficient as the transmission of HARQ responses for sidelink communications in the licensed spectrum. This may result in poor reliability of sidelink communications in the unlicensed spectrum. The terms licensed spectrum and licensed frequency band may be used interchangeably. Similarly, the terms unlicensed spectrum and unlicensed frequency band may be used interchangeably.

[0078] Some techniques and apparatus described herein may enable a first UE to send an indication to a second UE via a primary carrier identifying resources on the primary carrier for sending a HARQ response for sidelink communications on a secondary carrier. The second UE may use the identified resources on the primary carrier to send a HARQ response for sidelink communications on the secondary carrier. In some aspects, the primary carrier may be a licensed carrier and the secondary carrier may be an unlicensed carrier. As a result, the reliability of sidelink communications on the unlicensed carrier may be increased. In addition, some techniques and apparatus described herein may enable clustering of HARQ responses for sidelink communications on a secondary carrier (such as an unlicensed carrier). This may result in reduced power consumption, reduced peak-to-average power ratio, and / or reduced interference in the time-frequency domain.

[0079] As pointed out above, Figure 7 Provided as aspects. Other aspects may differ from those regarding Figure 7 Aspects described.

[0080] Figure 8 8 is a diagram illustrating aspects 800 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure. Figure 8 , a first UE may send a sidelink communication to a second UE via a sidelink subchannel (e.g., subchannel 815-1) of primary carrier 805. The first UE and / or the second UE may correspond to one or more other UEs (such as UE 120) described elsewhere herein. The sidelink subchannel may provide sidelink communications between UEs as described elsewhere herein, such as the sidelink access described with respect to UEs 305-1 and 305-2. Primary carrier 805 may be a licensed carrier. For example, primary carrier 805 may include a licensed spectrum as described elsewhere herein, such as licensed carrier 705.

[0081] The first UE may send an indication of multiple data channels 820 (e.g., channel 820-1, channel 820-2, channel 820-3, and / or channel 820-4) of a secondary carrier 810 to a second UE. Such multiple data channels 820 may be used to attempt one or more sidelink communications between the first UE and the second UE. The multiple data channels 820 may include a PSSCH, such as PSSCH 320 described elsewhere herein. In some aspects, the secondary carrier 810 may be an unlicensed carrier. For example, the secondary carrier may include an unlicensed spectrum as described elsewhere herein, such as unlicensed carrier 710. One or more of the multiple data channels 820 may be used to attempt one or more sidelink communications between the first UE and the second UE. The multiple data channels 820 may be contiguous, or share a common boundary immediately in time. By using contiguous data channels 820, overall latency may be minimized.

[0082] When attempting sidelink communication, the UE (e.g., the first UE, the second UE, and / or another UE) may perform a listen-before-talk (LBT) procedure to determine the availability of a data channel and transmit via the data channel if available, or perform another LBT procedure on another data channel if the data channel is not available. When attempting sidelink communication, the UE (e.g., the first UE or the second UE) may monitor communications on the data channel and, if detected, decode such communications. To monitor communications, the UE may perform blind decoding in situations where SCI may not be available.

[0083] In some aspects, a primary (e.g., licensed) carrier 805 can be used for quality of service (QoS)-sensitive data and / or control, while a secondary (e.g., unlicensed) carrier 810 can be used, when appropriate, to provide a larger data delivery pipeline, which can include relaxed QoS. In this way, licensed secondary QoS and / or congestion control for channel access can be provided on the unlicensed carrier.

[0084] The data channel 820 may occupy a time slot. Figure 8 As shown in , such time slots can have a larger duration (such as PSSCH2 820-3) or a smaller duration (such as PSSCH0 820-1). Time slots of smaller duration can be referred to as mini-slots. Multiple data channels 820 can start from one or more mini-slots, such as PSSCH0 820-1 and PSSCH1 820-2. Providing such mini-slots at the beginning of a series of multiple data channels 820 can reduce latency, such as in the case where an initial LBT process is unable to access the data channel, perhaps due to congestion and / or interference, and another LBT process is to be attempted.

[0085] The indication sent from the first UE to the second UE may identify one or more resources of the primary carrier 805 to be used for the HARQ response 825 corresponding to the data channel 820 of the secondary carrier 810. Providing the HARQ response 825 via the primary carrier 805 (as opposed to the secondary (e.g., unlicensed) carrier 810) may result in improved reliability. Providing the HARQ response 825 via the primary carrier 805 (as opposed to the secondary (e.g., unlicensed) carrier 810) may enable highly reliable control signaling.

[0086] In some aspects, the indication may include identifying a configuration of resources of the primary carrier 805 to be used by the second UE for a HARQ response 825 for sidelink communications on the data channel 820 of the secondary carrier 810, and further indicating how the second UE is to perform resource selection for the identified resources. In some aspects, the set of resources identified for the second UE to use for sending the HARQ response 825 may be defined as having a non-zero time gap (at the end of the data channel 820) with the last data channel (e.g., PSSCH3 820-4) on the secondary carrier 810. Figure 8 ” in the figure) to allow the second UE to access the identified resources.

[0087] In some aspects, the indication may include an SCI for polling for a HARQ response 825 from the second UE. The SCI may identify a dynamic resource pool on the primary carrier 805 to be used by the second UE to send a HARQ response 825 for sidelink communications on the data channel 820 of the secondary carrier 810. In some aspects, the indication may instruct the second UE to store the HARQ response 825 and wait for another indication including an SCI for polling for a HARQ response 825 from the second UE.

[0088] In some aspects, the indication may identify a secondary PSFCH resource pool on the primary carrier that is allocated for HARQ responses 825 for sidelink communications on the data channel 820 of the secondary carrier 810. The secondary PSFCH resource pool may be orthogonal to the PSFCH resource pool allocated for HARQ responses for sidelink communications on the primary carrier 805 (referred to herein as the "primary PSFCH resource pool"). In some aspects, the indication may indicate to the second UE to use implicit resource determination to select resources from the secondary PSFCH resource pool to send the HARQ response 825. In some aspects, the indication may explicitly allocate resources in the secondary PSFCH resource pool for the second UE to use to send the HARQ response 825.

[0089] In some aspects, the indication may be used to configure the second UE to multiplex one or more HARQ responses 825 for sidelink communications on the data channel 820 of the secondary carrier 810 into the primary PSFCH resource pool used for HARQ responses for sidelink communications on the primary carrier 805. In some aspects, the indication may instruct the second UE to use implicit resource determination to select resources from the primary PSFCH resource pool to send the HARQ responses 825. In some aspects, the indication may explicitly allocate resources in the primary PSFCH resource pool for the second UE to use to send the HARQ responses 825.

[0090] In some aspects, the indication sent from the first UE to the second UE may be included in an SCI, a medium access control (MAC) control element (CE) (MAC-CE), a radio resource control configuration (RRC) message, or a combination thereof.

[0091] The second UE may receive an indication from the first UE via a sidelink subchannel (e.g., subchannel 815-1) of the primary carrier 805 identifying resources on the primary carrier 805 for transmitting a HARQ response 825 for sidelink communications on the data channel 820 of the secondary carrier 810. The second UE may monitor the data channel 820 of the secondary carrier 810. When the second UE receives the sidelink communications from the first UE via the data channel 820 of the secondary carrier 810, the second UE may use the identified resources on the primary carrier 805 to transmit a HARQ response 825 for the sidelink communications on the data channel 820 of the secondary carrier 810.

[0092] As above combined Figure 8 As described, the first UE may send an indication to the second UE via the primary carrier 805, identifying resources on the primary carrier 805 for sending a HARQ response 825 for sidelink communication on the secondary carrier 810. The second UE may use the identified resources on the primary carrier 805 to send the HARQ response 825 for the sidelink communication on the secondary carrier 810. As a result, the reliability of the sidelink communication on the secondary (e.g., unlicensed) carrier 810 may be increased.

[0093] As pointed out above, Figure 8 Provided as aspects. Other aspects may differ from those regarding Figure 8 Aspects described.

[0094] Figure 9 is a diagram illustrating aspects 900 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure. Figure 9As shown in , aspect 900 includes communication between a first UE 120-1 and a second UE 120-2. In some aspects, the first UE 120-1 and the second UE 120-2 may be included in a wireless network (such as the wireless network 100). The first UE 120-1 and the second UE 120-2 may communicate via one or more sidelink channels described elsewhere herein, such as the sidelink communication described with respect to UEs 305-1 and 305-2. In aspect 900, the first UE 120-1 may be a Tx UE and the second UE 120-2 may be a Rx UE, or the first UE 120-1 may be a Rx UE and the second UE 120-2 may be a Tx UE.

[0095] like Figure 9 As shown in FIG905 , the first UE 120-1 may transmit an indication including a polling SCI to the second UE 120-2 via a sidelink subchannel of the primary carrier. The polling SCI may be used to poll the second UE 120-2 for one or more HARQ responses corresponding to one or more sidelink communications between the first UE 120-1 and the second UE 120-2 on a secondary carrier. In some aspects, the primary carrier may be a licensed carrier, and the secondary carrier may be an unlicensed carrier. In some aspects, the polling SCI may be used to collect multiple HARQ responses corresponding to multiple sidelink communications on the secondary carrier as a HARQ codebook transmitted on the primary carrier.

[0096] In some aspects, the polled SCI may identify a dynamic resource pool that includes one or more resources on the primary carrier that are allocated for sending HARQ responses for sidelink communications on the secondary carrier. The dynamic resource pool may be orthogonal to the primary PSFCH resource pool that is allocated for sending HARQ responses for sidelink communications on the primary carrier. The dynamic resource pool may include orthogonal resources for collecting sequence-based control information (e.g., HARQ responses). In some aspects, the HARQ response may occupy 1 PRB×1 OFDM symbol in the dynamic resource pool. In some aspects, the time domain resource allocation of the dynamic resource pool may be defined to have a non-zero time gap (e.g., a time gap) with the last data channel of the one or more data channels of the secondary carrier to be used for sidelink communications between the first UE 120-1 and the second UE 120-2. Figure 8 T in ).

[0097] In some aspects, the first UE 120-1 may send a polling SCI via the PSSCH or outside the PSSCH. In other words, the first UE 120-1 may send a polling SCI having a portion (e.g., a phase two SCI) that allocates a dynamic resource pool and a portion (e.g., another phase two SCI) associated with PSSCH communication. In some aspects, the polling SCI may include a first portion (e.g., a phase one SCI) and a second portion (e.g., a phase two SCI). In some aspects, the polling SCI may include SCI for the dynamically allocated resource pool within the first portion, the second portion, or both. In some aspects, the phase one SCI may be omitted, and the polling SCI may only include the phase two SCI.

[0098] In some aspects, the indication including the polling SCI may also include an indication of one or more data channels of a secondary carrier to be used for sidelink communications between the first UE 120-1 and the second UE 120-2.

[0099] In some aspects, an indication of one or more data channels of a secondary carrier to be used for sidelink communications between a first UE 120-1 and a second UE 120-2 may indicate to the second UE 120-2 to store HARQ responses for sidelink communications on the secondary carrier and wait for a second indication including a polling SCI. In this case, the first UE 120-1 then transmits a second indication including a polling SCI, which allocates a dynamic resource pool for use by the second UE 120-2 in transmitting HARQ responses for sidelink communications on the secondary carrier. The second indication may be used to aggregate HARQ responses for multiple sidelink communications on the secondary carrier, which may result in improved efficiency, saving computing, communication, network, and / or power resources that might otherwise be consumed by the additional transmission of HARQ responses.

[0100] In some aspects, the polling SCI may be sent to the second UE 120-2 in a UE-specific communication (e.g., a PSSCH communication) on a subcarrier of a primary channel. In some aspects, the polling SCI may be sent in a communication sent to the second UE 120-2 and one or more other UEs. Accordingly, the polling SCI may be used to collect HARQ responses from multiple UEs (e.g., the second UE 120-2 and / or one or more other UEs). In this case, the polling SCI may include an indication of which UE(s) are being polled and an SCI for dynamically allocating a dynamic resource pool for sending HARQ responses.

[0101] In some aspects, the polling SCI may be used to poll for other sequence-based control information in addition to HARQ responses. In some aspects, the polling SCI may be used to poll for one or more HARQ responses, and one or more scheduling requests and / or one or more buffer status reports from the second UE 120-2 and / or one or more other UEs.

[0102] like Figure 9 As further shown by reference numeral 910, the second UE 120-2 may receive one or more sidelink communications on the secondary carrier. The second UE 120-2 may monitor the sidelink communications on one or more data channels (e.g., PSSCH) of the secondary carrier and, if detected, decode such sidelink communications.

[0103] like Figure 9 As further shown by reference numeral 915, the second UE 120-2 may transmit one or more HARQ responses for one or more sidelink communications on the secondary carrier to the first UE 120-1 on the primary carrier based at least in part on the polled SCI. As described above, the polled SCI may identify a dynamic resource pool including one or more resources on the primary carrier. The second UE 120-2 may transmit one or more HARQ responses to the first UE 120-1 using one or more resources on the primary carrier included in the dynamic resource pool. In some aspects, the second UE 120-2 may store multiple HARQ responses for multiple sidelink communications on the secondary carrier and transmit a HARQ codebook including the aggregated multiple HARQ responses using one or more resources on the primary carrier included in the dynamic resource pool.

[0104] As pointed out above, Figure 9 Provided as aspects. Other aspects may differ from those regarding Figure 9 Aspects described.

[0105] Figure 10 1 is a diagram illustrating aspects 1000 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure. Figure 10As shown in , aspect 1000 includes communications between a first UE 120-1 and a second UE 120-2. In some aspects, the first UE 120-1 and the second UE 120-2 may be included in a wireless network, such as wireless network 100. The first UE 120-1 and the second UE 120-2 may communicate via one or more sidelink channels described elsewhere herein, such as the sidelink communications described with respect to UEs 305-1 and 305-2. In aspect 1000, the first UE 120-1 may be a Tx UE and the second UE 120-2 may be a Rx UE, or the first UE 120-1 may be a Rx UE and the second UE 120-2 may be a Tx UE.

[0106] like Figure 10 As shown in FIG1005 , first UE 120-1 may transmit an indication to second UE 120-2 via a sidelink subchannel of a primary carrier, identifying a secondary PSFCH resource pool for transmitting one or more HARQ responses for one or more sidelink communications on a secondary carrier. In some aspects, the primary carrier may be a licensed carrier, and the secondary carrier may be an unlicensed carrier. The secondary PSFCH resource pool may include one or more resources on the primary carrier allocated for transmitting HARQ responses for sidelink communications on the secondary carrier. The indication may be included in an RRC message, a MAC-CE, an SCI, or a combination thereof.

[0107] The secondary PSFCH resource pool may be orthogonal to the primary PSFCH resource pool allocated for HARQ responses for sidelink communications on the primary carrier. In some aspects, the secondary PSFCH resource pool may be frequency division multiplexed to the primary PSFCH resource pool. Additionally and / or alternatively, in the case where opportunities in the primary PSFCH are configured for more than one sidelink timeslot, the secondary PSFCH resource pool may be time division multiplexed to the primary PSFCH resource pool.

[0108] In some aspects, the indication may indicate to the second UE 120-2 to use implicit resource determination to select one or more resources from the secondary PSFCH resource pool to transmit a HARQ response for sidelink communication on the secondary carrier. The implicit resource determination may be based at least in part on a pseudo subchannel index and a pseudo slot index used for sidelink communication on the data channel of the secondary carrier. For PSSCH communication on the secondary carrier, the pseudo subchannel index may be an index of a subchannel of the primary carrier in which a cross-carrier indication associated with the PSSCH communication is transmitted. The pseudo slot index used for PSSCH communication on the secondary carrier may be an index of a slot in the primary carrier to which a starting OFDM symbol in the PSSCH communication points.

[0109] In some aspects, implicit resource determination may also be based at least in part on multiple PSSCH offset values ​​associated with sidelink communications on a data channel of the secondary carrier. When there are multiple PSSCH communications with the same pseudo slot index, the multiple PSSCH offset values ​​associated with the PSSCH communications may be: i In some aspects, for the first PSSCH communication in a slot, the plurality of offset values ​​I0=0, and the plurality of offset values ​​I i (i≠0) is a predetermined value for the subsequent PSSCH in the time slot. In some aspects, multiple offset values ​​I may be obtained from pre-configuration and / or RRC messages (e.g., via the PC5 interface). i .

[0110] In some aspects, the indication may explicitly allocate one or more resources in the secondary PSFCH resource pool for use by the second UE 120-2 in transmitting a HARQ response for a sidelink communication in the secondary carrier. In some aspects, the indication may allocate resources in the secondary PSFCH pool by specifying an explicit pseudo subchannel index and / or an explicit pseudo slot index for a data channel in the secondary carrier and / or a sidelink communication on the data channel. The explicit pseudo subchannel index may be different from the index corresponding to the subcarrier in the primary carrier in which the cross-carrier indication associated with the sidelink communication is transmitted. The explicit pseudo slot index may be different from the index of the slot in the primary carrier to which the starting OFDM symbol in the sidelink communication points.

[0111] Additionally and / or alternatively, the indication may specify explicit and dynamic values ​​for multiple PSSCH offsets for multiple sidelink communications in the same time slot.Additionally and / or alternatively, the indication may specify an explicit base sequence for a sequence-based PSFCH waveform.

[0112] Explicit resource allocation may be used to configure the second UE 120-2 to transmit a cluster of multiple HARQ responses using allocated resources in the secondary PSFCH resource pool. In some aspects, explicit resource allocation may be used to cluster the multiple HARQ responses in the time domain. In some aspects, clustering the HARQ responses in the time domain may provide power savings benefits by causing the radio on the primary (e.g., licensed) carrier (e.g., in the first UE 120-1 and / or the second UE 120-2) to sleep before the time at which the clustered resources are to be transmitted. Clustering the HARQ responses in the time domain may also reduce interference coverage when appropriate code division multiplexing (CDM) is employed at the time at which the clustered resources are to be transmitted.

[0113] In some aspects, explicit resource allocation may be used to cluster multiple HARQ responses in the frequency domain. Clustering HARQ responses in the frequency domain may reduce the peak-to-average power ratio and may cause less interference in the time-frequency domain.

[0114] When explicit resource determination is used to cluster HARQ responses (e.g., in the time domain and / or frequency domain), there is a risk of collision between multiple HARQ codebooks sent from different UEs. In some aspects, to reduce the risk of collision, the first UE 120-1 may monitor for a previous indication with explicit resource allocations for HARQ responses to avoid allocating a pseudo subchannel index and / or pseudo time slot index that has already been reserved by the other sidelink UE. In some aspects, the first UE 120-1 may reserve future PSSCH communications for indexing into a secondary PSFCH resource pool for use by the second UE 120-2 in sending clustered HARQ responses. In this case, the indication may specify, for the cluster of HARQ responses, a pseudo subchannel index corresponding to a subchannel of the future PSSCH communication and a pseudo time slot index corresponding to a time slot of the future PSSCH communication.

[0115] like Figure 10 As further shown by reference numeral 1010, the second UE 120-2 may receive one or more sidelink communications on the secondary carrier. The second UE 120-2 may monitor the sidelink communications on one or more data channels (e.g., PSSCH) of the secondary carrier and, if detected, decode such sidelink communications.

[0116] like Figure 10 As further shown by reference numeral 1015, the second UE 120-2 may select one or more resources from the secondary PSFCH resource pool for one or more HARQ responses for one or more sidelink communications on the secondary carrier. As described above, the secondary PSFCH resource pool includes resources on the primary carrier that are allocated for HARQ responses for sidelink communications on the secondary carrier.

[0117] like Figure 10 As shown in , in some aspects, the second UE 120-2 can use implicit resource determination to select resources from the secondary PSFCH resource pool. The implicit resource determination can be based at least in part on a pseudo subchannel index and a pseudo slot index used for sidelink communication on the data channel of the secondary carrier. For PSSCH communication on the secondary carrier, the pseudo subchannel index can be an index of a subchannel of the primary carrier in which a cross-carrier indication associated with the PSSCH communication is transmitted. The pseudo slot index used for PSSCH communication on the secondary carrier can be an index of a slot in the primary carrier to which a starting OFDM symbol in the PSSCH communication points.

[0118] For a HARQ response to a sidelink communication (e.g., a PSSCH communication) on the secondary carrier, the second UE 120-2 may select a resource from the secondary PSFCH resource pool that corresponds to the pseudo subchannel index and pseudo slot index associated with the sidelink communication. Figure 10 In the aspect shown in , the pseudo subchannel index for PSSCH2 corresponds to subchannel 1 in the primary carrier, and the pseudo slot index for PSSCH2 corresponds to slot n+3. Figure 10 In the aspect shown in , the pseudo subchannel index for PSSCH3 corresponds to subchannel 1 in the primary carrier, and the pseudo slot index for PSSCH2 corresponds to slot n+4.

[0119] exist Figure 10 In the aspect shown in , both PSSCH0 and PSSCH1 have pseudo subchannel indices corresponding to subchannel 1 in the primary carrier, and both have pseudo slot indices corresponding to slot n+2. For multiple sidelink communications having the same pseudo subchannel index and the same pseudo slot index, the second UE 120-2 may select a channel for each of the sidelink communications based in part on the multiple PSSCH offsets 1 for the sidelink communications. i , using a hash function to select resources for the corresponding HARQ response. In some aspects, for a HARQ response to the i-th sidelink communication with the same pseudo time slot index, the second UE 120-2 may select a resource with (K+M+I i ) modulo (Z*Y). In this case, Z is the number of PRBs, Y is the number of cyclic shifts, K is the L1 source ID of the PSSCH corresponding to the pseudo subchannel index and pseudo slot index, and M is 0 for unicast PSSCH or the member ID for groupcast PSSCH. The multiple offset values ​​I0 for the first sidelink communication (e.g., PSSCH0) with the same pseudo slot index can be 0. The multiple offset values ​​I0 for subsequent sidelink communications (e.g., PSSCH1) can be i (i≠0) may be a predetermined value configured through an indication or another configuration for second UE 120-2.

[0120] In some aspects, the second UE 120-2 may select resources in the secondary PSFCH resource pool that have been explicitly allocated for sending the HARQ response. In some aspects, for the HARQ response for the sidelink communication on the secondary carrier, the second UE 120-2 may select resources from the secondary PSFCH resource pool based at least in part on an explicit pseudo subchannel index specified by the indication, an explicit pseudo slot index specified by the indication, an explicit multiple PSSCH offset values, an explicit base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0121] like Figure 10 As further shown by reference numeral 1020, second UE 120-2 may send one or more HARQ responses on the primary carrier to first UE 120-1 for one or more sidelink communications on the secondary carrier. Second UE 120-2 may send the one or more HARQ responses to first UE 120-1 using one or more resources selected from the secondary PSFCH resource pool.

[0122] As pointed out above, Figure 10 Provided as aspects. Other aspects may differ from those regarding Figure 10 Aspects described.

[0123] Figure 11 1 is a diagram illustrating aspects 1100 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure. Figure 11 As shown in , aspect 1100 includes communication between a first UE 120-1 and a second UE 120-2. In some aspects, the first UE 120-1 and the second UE 120-2 may be included in a wireless network (such as wireless network 100). The first UE 120-1 and the second UE 120-2 may communicate via one or more sidelink channels described elsewhere herein, such as the sidelink communication described with respect to UEs 305-1 and 305-2. In aspect 1100, the first UE 120-1 may be a Tx UE and the second UE 120-2 may be a Rx UE, or the first UE 120-1 may be a Rx UE and the second UE 120-2 may be a Tx UE.

[0124] like Figure 11 As shown in FIG105 , first UE 120-1 may send an indication to second UE 120-2 via a sidelink subchannel of a primary carrier to multiplex one or more HARQ responses for one or more sidelink communications on a secondary carrier into a primary PSFCH resource pool. In some aspects, the primary carrier may be a licensed carrier and the secondary carrier may be an unlicensed carrier. The primary PSFCH resource pool is a resource pool allocated for HARQ responses for sidelink communications on a primary (e.g., licensed) carrier. The indication may be included in an RRC message, a MAC-CE, an SCI, or a combination thereof.

[0125] In some aspects, the indication may indicate to the second UE 120-2 to use implicit resource determination to select one or more resources from the primary PSFCH resource pool to send a HARQ response for sidelink communications on a secondary (e.g., unlicensed) carrier. The implicit resource determination may be based at least in part on a secondary carrier index U. For example, the secondary carrier index U may be an unlicensed carrier index. The secondary carrier index U (e.g., an unlicensed carrier index) modifies the hash function used for resource determination to avoid confusion with a HARQ response for sidelink communications on a primary carrier (e.g., a licensed carrier). The secondary carrier index U may be a predetermined value specified by indication or via preconfiguration. In some aspects, the secondary carrier index U may be set via a group-common configuration message or via a UE-specific (e.g., PC5-RRC) configuration message between the first UE 120-1 and the second UE 120-2.

[0126] Implicit resource determination may also be based, at least in part, on a pseudo subchannel index and a pseudo slot index used for sidelink communications on the data channel of the secondary carrier. For PSSCH communications on the secondary carrier, the pseudo subchannel index may be the index of the subchannel of the primary carrier in which the cross-carrier indication associated with the PSSCH communication is transmitted. The pseudo slot index used for PSSCH communications on the secondary carrier may be the index of the slot in the primary carrier to which the starting OFDM symbol in the PSSCH communication points.

[0127] In some aspects, implicit resource determination may also be based at least in part on a plurality of PSSCH offset values ​​associated with sidelink communications on a data channel of the secondary carrier. i In some aspects, for the first PSSCH communication in a time slot, the plurality of offset values ​​I0=0, and the plurality of offset values ​​I i (i≠0) is a predetermined value for the subsequent PSSCH in the time slot. In some aspects, multiple offset values ​​I may be obtained from pre-configuration and / or RRC messages (e.g., PC5-RRC). i .

[0128] In some aspects, the indication may explicitly allocate one or more resources in the primary PSFCH resource pool for use by the second UE 120-2 in transmitting a HARQ response for a sidelink communication in the secondary carrier. In some aspects, the indication may dynamically specify a value for the secondary carrier index U. In some aspects, the indication may specify an explicit pseudo subchannel index and / or an explicit pseudo slot index for a data channel in the secondary carrier and / or a sidelink communication on the data channel. The explicit pseudo subchannel index may be different from an index corresponding to a subcarrier in the primary carrier in which a cross-carrier indication associated with the sidelink communication is transmitted. The explicit pseudo slot index may be different from an index of a slot in the primary carrier to which a starting OFDM symbol in the sidelink communication points.

[0129] Additionally and / or alternatively, the indication may specify explicit and dynamic values ​​for multiple PSSCH offsets for multiple sidelink communications in the same time slot.Additionally and / or alternatively, the indication may specify an explicit base sequence for a sequence-based PSFCH waveform.

[0130] Explicit resource allocation may be used to configure the second UE 120-2 to transmit a cluster of multiple HARQ responses using allocated resources in the primary PSFCH resource pool. In some aspects, explicit resource allocation may be used to cluster the multiple HARQ responses in the time domain. In some aspects, clustering the HARQ responses in the time domain may provide power savings benefits by causing the radio on the primary carrier (e.g., in the first UE 120-1 and / or the second UE 120-2) to sleep before the time at which the clustered resources are to be transmitted. Clustering the HARQ responses in the time domain may also reduce interference coverage when appropriate CDM is employed at the time at which the clustered resources are to be transmitted.

[0131] In some aspects, explicit resource allocation may be used to cluster multiple HARQ responses in the frequency domain. Clustering HARQ responses in the frequency domain may reduce the peak-to-average power ratio and may cause less interference in the time-frequency domain.

[0132] like Figure 11 As further shown by reference numeral 1110, the second UE 120-2 may receive one or more sidelink communications on the secondary carrier. The second UE 120-2 may monitor the sidelink communications on one or more data channels (e.g., PSSCH) of the secondary carrier and, if detected, decode such sidelink communications.

[0133] like Figure 11As further indicated by reference numeral 1115, the second UE 120-2 may select one or more resources from the primary PSFCH resource pool for one or more HARQ responses for one or more sidelink communications on the secondary carrier.

[0134] In some aspects, the second UE 120-2 may use implicit resource determination to select resources from the primary PSFCH resource pool. The implicit resource determination may be based at least in part on a secondary carrier index U (e.g., an unlicensed carrier index), a pseudo subchannel index for sidelink communication on the data channel of the secondary carrier, and a pseudo time slot index for sidelink communication on the data channel of the secondary carrier. For PSSCH communication on the secondary carrier, the pseudo subchannel index may be an index of a subchannel of the primary carrier in which a cross-carrier indication associated with the PSSCH communication is transmitted. The pseudo time slot index for PSSCH communication on the secondary carrier may be an index of a time slot in the primary carrier to which a starting OFDM symbol in the PSSCH communication points.

[0135] Implicit resource determination may also be based at least in part on a plurality of PSSCH offset values ​​I used for sidelink communication. i The multiple offset values ​​I0 for the first sidelink communication with the same pseudo slot index may be 0. The multiple PSSCH offset values ​​I0 for subsequent sidelink communications may be i (i≠0) may be a predetermined value configured via an indication or another configuration message. In some aspects, the second UE 120-2 may select a resource with (K+M+I i + U) modulo (Z*Y). In this case, Z is the number of PRBs, Y is the number of cyclic shifts, K is the L1 source ID of the PSSCH corresponding to the pseudo subchannel index and pseudo slot index, and M is 0 for unicast PSSCH or the member ID for groupcast PSSCH.

[0136] In some aspects, the second UE 120-2 may select resources in the primary PSFCH resource pool that have been explicitly allocated for sending the HARQ response. In some aspects, for a HARQ response for sidelink communication on a secondary carrier, the second UE 120-2 may select resources from the primary PSFCH resource pool based at least in part on an explicit secondary carrier index U (e.g., an unlicensed carrier index), an explicit pseudo subchannel index specified by the indication, an explicit pseudo slot index specified by the indication, an explicit multiple PSSCH offset values, an explicit base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0137] like Figure 11As further shown by reference numeral 1120, second UE 120-2 may send one or more HARQ responses on the primary carrier to first UE 120-1 for one or more sidelink communications on the secondary carrier. Second UE 120-2 may send the one or more HARQ responses to first UE 120-1 using one or more resources selected from the primary PSFCH resource pool.

[0138] As pointed out above, Figure 11 Provided as aspects. Other aspects may differ from those regarding Figure 11 Aspects described.

[0139] Figure 9 、 10 The aspects of aspects 1 and 11 may be used in combination in any combination. In some aspects, the polled SCI may be a HARQ response used instead of a HARQ response sent using resources in the secondary PSFCH resource pool and / or the primary PSFCH resource pool. In this case, the polled SCI may be used to collect HARQ responses that were lost and / or ambiguous due to the use of resources in the secondary PSFCH resource pool and / or the primary PSFCH resource pool.

[0140] Figure 12 is a diagram illustrating aspects 1200 and 1210 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure.

[0141] like Figure 12 As shown in , in aspect 1200, HARQ responses for sidelink communications (PSSCH0, PSSCH1, PSSCH2, and PSSCH3) are sent in resources selected from a PSFCH resource pool (e.g., a secondary PSFCH resource pool or a primary PSFCH resource pool) using implicit resource determination. In aspect 1210, HARQ responses are clustered in the time domain by manipulating pseudo-slot indices using explicit resource determination. In some aspects, clustering the HARQ responses in the time domain can provide power saving benefits by causing the radio on the primary (e.g., licensed) carrier (e.g., in a first UE and / or a second UE) to sleep before the time at which the clustered resources are to be transmitted. Clustering the HARQ responses in the time domain can also reduce interference coverage when appropriate CDM is employed at the time at which the clustered resources are to be transmitted.

[0142] As pointed out above, Figure 12 Provided as aspects. Other aspects may differ from those regarding Figure 12 Aspects described.

[0143] Figure 13is a diagram illustrating aspects 1300 and 1310 associated with a HARQ response for primary carrier assisted sidelink access according to the present disclosure.

[0144] like Figure 13 As shown in , a first UE (e.g., UE 120) uses subchannel 1 and subchannel 2 on a primary carrier to schedule sidelink communications (PSSCCH0, PSSCH1, PSSCH2, and PSSCH3) with two other UEs (e.g., UE 120) on a secondary carrier. In some aspects, the primary carrier can be a licensed carrier and the secondary carrier can be an unlicensed carrier. In aspect 1300, HARQ responses from the other UEs for sidelink communications are sent in resources selected from a PSFCH resource pool (e.g., a secondary PSFCH resource pool or a primary PSFCH resource pool) using implicit resource determination. In aspect 1310, the HARQ responses from the other UEs are clustered in frequency using explicit resource determination. Clustering the HARQ responses in the frequency domain can reduce the peak-to-average power ratio and can cause less interference in the time-frequency domain.

[0145] As pointed out above, Figure 13 Provided as aspects. Other aspects may differ from those regarding Figure 13 Aspects described.

[0146] Figure 14 is a diagram illustrating an example process 1400 performed by a first UE (in some aspects) in accordance with the present disclosure. Example process 1400 is an aspect in which a first UE (e.g., UE 120) performs operations associated with a HARQ response for a primary carrier assisted sidelink access.

[0147] like Figure 14 As shown in , in some aspects, process 1400 may include sending, to a second UE via a sidelink subchannel of the primary carrier, an indication identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on the secondary carrier (block 1410). As described above, in some aspects, the first UE (e.g., using the receive processor 258, the transmit processor 264, the controller / processor 280, and / or the memory 282) may send, to the second UE via a sidelink subchannel of the primary carrier, an indication identifying one or more resources on the primary carrier for sending one or more HARQ responses for one or more sidelink communications between the first UE and the second UE on the secondary carrier.

[0148] like Figure 14As further shown in FIG14 , in some aspects, process 1400 may include receiving, from a second UE on one or more resources on the primary carrier, one or more HARQ responses for one or more sidelink communications on the secondary carrier (block 1420). As described above, in some aspects, a first UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, and / or memory 282) may receive, from a second UE on one or more resources on the primary carrier, one or more HARQ responses for one or more sidelink communications on the secondary carrier.

[0149] Process 1400 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in combination with one or more other processes described elsewhere herein.

[0150] In a first aspect, process 1400 includes transmitting one or more sidelink communications on a secondary carrier.

[0151] In a second aspect, alone or in combination with the first aspect, a plurality of data channels identifying a secondary carrier to be used for attempting one or more sidelink communications between a first UE and a second UE is indicated.

[0152] In a third aspect, alone or in combination with one or more of the first and second aspects, the indication comprises sidelink control information for polling for one or more HARQ responses from the second UE.

[0153] In a fourth aspect, alone or in combination with one or more of the first to third aspects, the sidelink control information for polling for one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook.

[0154] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, the sidelink control information allocates a dynamic resource pool comprising one or more resources on a primary carrier for the second UE to send one or more HARQ responses.

[0155] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the dynamic resource pool is orthogonal to the physical sidelink feedback channel resource pool.

[0156] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, the dynamic resource pool includes orthogonal resources for sending one or more HARQ responses.

[0157] In an eighth aspect, either alone or in combination with one or more of the first to seventh aspects, the sidelink control information uses time domain resource allocation to allocate a dynamic resource pool that has a gap with the last data of one or more data channels of the auxiliary carrier to be used for one or more sidelink communications.

[0158] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, receiving one or more HARQ responses includes receiving one or more HARQ responses on one or more resources on a primary carrier included in a dynamic resource pool.

[0159] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the sidelink control information is included in a physical sidelink shared channel communication.

[0160] In the eleventh aspect, alone or in combination with one or more of the first to tenth aspects, an instruction is given to the second UE to store one or more HARQ responses and wait for side link control information for polling one or more HARQ responses from the second UE.

[0161] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the process 1400 includes sending sidelink control information to a second UE for polling for one or more HARQ responses from the second UE.

[0162] In a thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, the one or more HARQ responses are received based at least in part on sidelink control information used to poll for the one or more HARQ responses from the second UE.

[0163] In a fourteenth aspect, alone or in combination with one or more of aspects one to thirteen, receiving one or more HARQ responses comprises receiving, from the second UE on the primary carrier, an aggregated HARQ response for multiple sidelink communications between the first UE and the second UE on the secondary carrier based at least in part on the sidelink control information.

[0164] In the fifteenth aspect, alone or in combination with one or more of the first to fourteenth aspects, sidelink control information is sent to the second UE and one or more other UEs to poll one or more HARQ responses from the second UE, and to poll one or more HARQ responses from one or more other UEs.

[0165] In a sixteenth aspect, alone or in combination with one or more of the first to fifteenth aspects, the sidelink control information polls for one or more HARQ responses and other control information from the second UE.

[0166] In a seventeenth aspect, alone or in combination with one or more of the first to sixteenth aspects, the other control information includes at least one of a scheduling request or a buffer status report.

[0167] In an eighteenth aspect, alone or in combination with one or more of the first to seventeenth aspects, an indication is provided for identifying a secondary PSFCH resource pool including resources on a primary carrier allocated for one or more HARQ responses for one or more sidelink communications between a first UE and a second UE on a secondary carrier.

[0168] In a nineteenth aspect, alone or in combination with one or more of the first to eighteenth aspects, the secondary PSFCH resource pool is orthogonal to the primary PSFCH resource pool used for HARQ responses for sidelink communications on the primary carrier.

[0169] In a twentieth aspect, alone or in combination with one or more of the first to nineteenth aspects, the secondary PSFCH resource pool is frequency division multiplexed to the primary PSFCH resource pool.

[0170] In a twenty-first aspect, alone or in combination with one or more of the first to twentieth aspects, the secondary PSFCH resource pool is time-division multiplexed to the primary PSFCH resource pool.

[0171] In a twenty-second aspect, alone or in combination with one or more of aspects one to twenty-first, instructions are provided to indicate to a second UE to use implicit resource determination to select one or more resources from a secondary PSFCH resource pool for sending one or more HARQ responses.

[0172] In aspect 23, either alone or in combination with one or more of aspects 1 to 22, implicit resource determination selects resources from a secondary PSFCH resource pool based at least in part on a pseudo subchannel index of a sidelink communication and a pseudo time slot index of the sidelink communication in one or more sidelink communications on the secondary carrier to send a HARQ response for the sidelink communication, the pseudo subchannel index of the sidelink communication corresponding to the sidelink subchannel of the primary carrier on which the transmission is indicated, and the pseudo time slot index of the sidelink communication corresponding to the time slot in the primary carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0173] In aspect 24, alone or in combination with one or more of aspects 1 to 23, when multiple sidelink communications in one or more sidelink communications have the same pseudo time slot index, implicit resource determination selects resources from a secondary PSFCH resource pool based at least in part on corresponding multiple physical sidelink shared channel offset values ​​associated with each of the multiple sidelink communications to send corresponding HARQ responses for each of the multiple sidelink communications.

[0174] In a twenty-fifth aspect, alone or in combination with one or more of the first to twenty-fourth aspects, an indication is given of explicitly allocating one or more resources in a secondary PSFCH resource pool for sending one or more HARQ responses.

[0175] In aspect twenty-six, alone or in combination with one or more of aspects one to twenty-fifth, an indication is given of a pseudo subchannel index for sidelink communication, a pseudo time slot index for sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof, for sidelink communication in one or more sidelink communications on an auxiliary carrier.

[0176] In a twenty-seventh aspect, either alone or in combination with one or more of aspects one to twenty-six, the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of a main carrier that is different from the sidelink subchannel of the main carrier on which the transmission is indicated.

[0177] In aspect twenty-eight, either alone or in combination with one or more of aspects one to twenty-seven, the pseudo time slot index designated for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0178] In aspect 29, alone or in combination with one or more of aspects 1 to 28, the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and indicate that one or more resources in the secondary PSFCH resource pool are explicitly allocated to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0179] In a thirtieth aspect, alone or in combination with one or more of aspects one to twenty-ninth, process 1400 includes monitoring one or more other indications sent by one or more other UEs to avoid allocating one or more resources in a secondary PSFCH resource pool corresponding to a pseudo subchannel index or pseudo time slot index already reserved by one or more other UEs to a cluster of HARQ responses.

[0180] In the thirty-first aspect, alone or in combination with one or more of the first to thirtieth aspects, process 1400 includes reserving a secondary PSFCH resource pool for indexing into a cluster for HARQ response for future physical sidelink shared channel communications, wherein an indication is given that a subchannel index of the future physical sidelink shared channel communication is being designated as a pseudo subchannel index of the cluster for HARQ response, and a time slot index of the future physical sidelink shared channel communication is designated as a pseudo time slot index of the cluster for HARQ response.

[0181] In aspect 32, receiving one or more HARQ responses, alone or in combination with one or more of aspects 1 to 31, includes receiving one or more HARQ responses for one or more sidelink communications on a secondary carrier from a second UE on one or more resources of a secondary PSFCH resource pool.

[0182] In aspect thirty-third, alone or in combination with one or more of aspects one to thirty-second, process 1400 includes sending side link control information to a second UE for polling for one or more HARQ responses other than one or more HARQ responses received on one or more resources in the resources of the secondary PSFCH resource pool.

[0183] In aspect 34, either alone or in combination with one or more of aspects 1 to 33, indication is provided for configuring a second UE to multiplex one or more HARQ responses for one or more sidelink communications on a secondary carrier into a PSFCH resource pool for HARQ responses for sidelink communications on a primary carrier.

[0184] In a thirty-fifth aspect, alone or in combination with one or more of the first to thirty-fourth aspects, instructions are provided for indicating to a second UE to use implicit resource determination to select one or more resources from a PSFCH resource pool for sending one or more HARQ responses.

[0185] In aspect thirty-six, alone or in combination with one or more of aspects one to thirty-five, implicit resource determination is based at least in part on a secondary carrier index associated with a sidelink communication in one or more sidelink communications on the secondary carrier and at least in part on a pseudo subchannel index of the sidelink communication, a pseudo time slot index of the sidelink communication, a plurality of physical sidelink shared channel offset values ​​associated with the sidelink communication, or a combination thereof to select resources from a PSFCH resource pool to send a HARQ response for the sidelink communication.

[0186] In aspect thirty-seven, either alone or in combination with one or more of aspects one to thirty-six, the pseudo subchannel index of the sidelink communication corresponds to the sidelink subchannel on which the main carrier being transmitted is indicated, and the pseudo time slot index of the sidelink communication corresponds to the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0187] In aspect 38, alone or in combination with one or more of aspects 1 to 37, an indication is given of explicitly allocating one or more resources in a PSFCH resource pool for sending one or more HARQ responses.

[0188] In aspect thirty-ninth aspect, alone or in combination with one or more of aspects one to thirty-eight, an indication is given of a sidelink communication in one or more sidelink communications on an auxiliary carrier, specifying an auxiliary carrier index associated with the sidelink communication, a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0189] In a fortieth aspect, either alone or in combination with one or more of aspects one to thirty-ninth, the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of a main carrier that is different from the sidelink subchannel of the main carrier on which the transmission is indicated.

[0190] In the forty-first aspect, either alone or in combination with one or more of the first to fortieth aspects, the pseudo time slot index designated for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0191] In aspect 42, alone or in combination with one or more of aspects 1 to 41, the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and indicate that one or more resources in the PSFCH resource pool are explicitly allocated to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0192] In aspect 43, receiving one or more HARQ responses, alone or in combination with one or more of aspects 1 to 42, includes receiving one or more HARQ responses for one or more sidelink communications on a secondary carrier from a second UE on one or more resources of a PSFCH resource pool.

[0193] In aspect 44, alone or in combination with one or more of aspects 1 to 43, process 1400 includes sending sidelink control information to a second UE for polling HARQ responses other than one or more HARQ responses received on one or more resources of a PSFCH resource pool.

[0194] In a 45th aspect, alone or in combination with one or more of aspects 1 to 44, the primary carrier is a licensed carrier and the secondary carrier is an unlicensed carrier.

[0195] although Figure 14 Example blocks of process 1400 are shown, but in some aspects, process 1400 may include Figure 14 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than the blocks shown in . Additionally or alternatively, two or more of the blocks in process 1400 may be executed in parallel.

[0196] Figure 15 1 is a diagram illustrating an example process 1500 performed by a second UE (in some aspects) in accordance with various aspects of the present disclosure. Example process 1500 is an aspect in which a second UE (e.g., UE 120) performs operations associated with a HARQ response for a primary carrier assisted sidelink access.

[0197] like Figure 15 As shown in , in some aspects, process 1500 may include receiving, from a first UE via a sidelink subchannel of a primary carrier, an indication of how to transmit one or more HARQ responses on the primary carrier for one or more sidelink communications between the first UE and a second UE on a secondary carrier (block 1510). As described above, in some aspects, the second UE (e.g., using the receive processor 258, the transmit processor 264, the controller / processor 280, and / or the memory 282) may receive, from the first UE via a sidelink subchannel of the primary carrier, an indication of how to transmit one or more HARQ responses on the primary carrier for one or more sidelink communications between the first UE and the second UE on the secondary carrier.

[0198] like Figure 15As further shown in FIG, in some aspects, process 1500 may include, based at least in part on the indication, sending, to the first UE, on the primary carrier, one or more HARQ responses for one or more sidelink communications on the secondary carrier (block 1520). As described above, in some aspects, the second UE (e.g., using the receive processor 258, the transmit processor 264, the controller / processor 280, and / or the memory 282) may send, to the first UE, on the primary carrier, one or more HARQ responses for one or more sidelink communications on the secondary carrier based at least in part on the indication.

[0199] Process 1500 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in combination with one or more other processes described elsewhere herein.

[0200] In a first aspect, process 1500 includes receiving one or more sidelink communications on a secondary carrier.

[0201] In a second aspect, alone or in combination with the first aspect, a plurality of data channels identifying a secondary carrier to be used for attempting one or more sidelink communications between a first UE and a second UE is indicated.

[0202] In a third aspect, alone or in combination with one or more of the first and second aspects, the indication comprises sidelink control information for polling for one or more HARQ responses from the second UE.

[0203] In a fourth aspect, alone or in combination with one or more of the first to third aspects, the sidelink control information for polling for one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook.

[0204] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, the sidelink control information allocates a dynamic resource pool comprising one or more resources on a primary carrier for the second UE to send one or more HARQ responses.

[0205] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the dynamic resource pool is orthogonal to the physical sidelink feedback channel resource pool.

[0206] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, the dynamic resource pool includes orthogonal resources for sending one or more HARQ responses.

[0207] In an eighth aspect, either alone or in combination with one or more of the first to seventh aspects, the sidelink control information uses time domain resource allocation to allocate a dynamic resource pool that has a gap with the last data of one or more data channels of the auxiliary carrier to be used for one or more sidelink communications.

[0208] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, sending one or more HARQ responses includes sending one or more HARQ responses on one or more resources on a primary carrier included in a dynamic resource pool.

[0209] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the sidelink control information is included in a physical sidelink shared channel communication.

[0210] In the eleventh aspect, alone or in combination with one or more of the first to tenth aspects, an instruction is given to the second UE to store one or more HARQ responses and wait for side link control information for polling one or more HARQ responses from the second UE.

[0211] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the process 1500 includes receiving sidelink control information for polling for one or more HARQ responses from a second UE.

[0212] In a thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, the one or more HARQ responses are sent based at least in part on sidelink control information used to poll for the one or more HARQ responses from the second UE.

[0213] In a fourteenth aspect, alone or in combination with one or more of aspects one to thirteen, sending one or more HARQ responses comprises sending, to the first UE on a primary carrier, an aggregated HARQ response for multiple sidelink communications between the first UE and a second UE on a secondary carrier based at least in part on sidelink control information.

[0214] In the fifteenth aspect, alone or in combination with one or more of the first to fourteenth aspects, sidelink control information is sent to the second UE and one or more other UEs to poll one or more HARQ responses from the second UE, and to poll one or more HARQ responses from one or more other UEs.

[0215] In a sixteenth aspect, alone or in combination with one or more of the first to fifteenth aspects, the sidelink control information polls for one or more HARQ responses and other control information from the second UE.

[0216] In a seventeenth aspect, alone or in combination with one or more of the first to sixteenth aspects, the other control information includes at least one of a scheduling request or a buffer status report.

[0217] In an eighteenth aspect, alone or in combination with one or more of the first to seventeenth aspects, an indication is provided for identifying a secondary PSFCH resource pool including resources on a primary carrier allocated for one or more HARQ responses for one or more sidelink communications between a first UE and a second UE on a secondary carrier.

[0218] In a nineteenth aspect, alone or in combination with one or more of the first to eighteenth aspects, the secondary PSFCH resource pool is orthogonal to the primary PSFCH resource pool used for HARQ responses for sidelink communications on the primary carrier.

[0219] In a twentieth aspect, alone or in combination with one or more of the first to nineteenth aspects, the secondary PSFCH resource pool is frequency division multiplexed to the primary PSFCH resource pool.

[0220] In a twenty-first aspect, alone or in combination with one or more of the first to twentieth aspects, the secondary PSFCH resource pool is time-division multiplexed to the primary PSFCH resource pool.

[0221] In a twenty-second aspect, alone or in combination with one or more of aspects one to twenty-first, instructions are provided to indicate to a second UE to use implicit resource determination to select one or more resources from a secondary PSFCH resource pool for sending one or more HARQ responses.

[0222] In aspect 23, alone or in combination with one or more of aspects 1 to 22, process 1500 comprises selecting resources from a secondary PSFCH resource pool to send a HARQ response for the sidelink communication based at least in part on a pseudo subchannel index of the sidelink communication and a pseudo time slot index of the sidelink communication in one or more sidelink communications on the secondary carrier, wherein the pseudo subchannel index of the sidelink communication corresponds to a sidelink subchannel of the primary carrier on which the communication is being transmitted and the pseudo time slot index of the sidelink communication corresponds to a time slot in the primary carrier indicated by a start orthogonal frequency division multiplexing symbol of the sidelink communication.

[0223] In aspect 24, either alone or in combination with one or more of aspects 1 to 23, selecting resources from the secondary PSFCH resource pool includes selecting resources from the secondary PSFCH resource pool to send corresponding HARQ responses for each of the multiple sidelink communications when multiple sidelink communications in one or more sidelink communications have the same pseudo time slot index, at least in part based on corresponding multiple physical sidelink shared channel offset values ​​associated with each of the multiple sidelink communications.

[0224] In a twenty-fifth aspect, alone or in combination with one or more of the first to twenty-fourth aspects, an indication is given of explicitly allocating one or more resources in a secondary PSFCH resource pool for sending one or more HARQ responses.

[0225] In aspect twenty-six, alone or in combination with one or more of aspects one to twenty-fifth, an indication is given of a pseudo subchannel index for sidelink communication, a pseudo time slot index for sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof, for sidelink communication in one or more sidelink communications on an auxiliary carrier.

[0226] In a twenty-seventh aspect, either alone or in combination with one or more of aspects one to twenty-six, the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of a main carrier that is different from the sidelink subchannel of the main carrier on which the transmission is indicated.

[0227] In aspect twenty-eight, either alone or in combination with one or more of aspects one to twenty-seven, the pseudo time slot index designated for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0228] In aspect 29, alone or in combination with one or more of aspects 1 to 28, the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and indicate that one or more resources in the secondary PSFCH resource pool are explicitly allocated to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0229] In the thirtieth aspect, alone or in combination with one or more of aspects one to twenty-ninth, sending one or more HARQ responses includes sending one or more HARQ responses for one or more sidelink communications on a secondary carrier to the first UE on one or more resources of a secondary PSFCH resource pool.

[0230] In the thirty-first aspect, alone or in combination with one or more of aspects 1 to 30, process 1500 includes: receiving side link control information from the first UE for polling one or more HARQ responses other than one or more HARQ responses sent on one or more resources in the resources of the secondary PSFCH resource pool.

[0231] In aspect 32, either alone or in combination with one or more of aspects 1 to 31, indication is provided for configuring a second UE to multiplex one or more HARQ responses for one or more sidelink communications on a secondary carrier into a PSFCH resource pool for HARQ responses for sidelink communications on a primary carrier.

[0232] In a thirty-third aspect, alone or in combination with one or more of aspects one to thirty-second, instructions are provided for indicating to a second UE to use implicit resource determination to select one or more resources from a PSFCH resource pool for sending one or more HARQ responses.

[0233] In aspect thirty-four, alone or in combination with one or more of aspects one to thirty-three, process 1500 comprises selecting resources from a PSFCH resource pool to send a HARQ response for a sidelink communication based at least in part on a secondary carrier index associated with a sidelink communication in one or more sidelink communications on the secondary carrier and based at least in part on a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, a plurality of physical sidelink shared channel offset values ​​associated with the sidelink communication, or a combination thereof.

[0234] In aspect thirty-fifth, alone or in combination with one or more of aspects one to thirty-fourth, the pseudo subchannel index of the sidelink communication corresponds to the sidelink subchannel on which the main carrier being transmitted is indicated, and the pseudo time slot index of the sidelink communication corresponds to the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0235] In a thirty-sixth aspect, alone or in combination with one or more of the first to thirty-fifth aspects, it is indicated that one or more resources in a PSFCH resource pool for sending one or more HARQ responses are explicitly allocated.

[0236] In aspect thirty-seven, alone or in combination with one or more of aspects one to thirty-six, an indication is given of a sidelink communication in one or more sidelink communications on an auxiliary carrier, specifying an auxiliary carrier index associated with the sidelink communication, a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0237] In aspect thirty-eight, either alone or in combination with one or more of aspects one to thirty-seven, the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of a main carrier that is different from the sidelink subchannel of the main carrier on which the transmission is indicated.

[0238] In aspect thirty-ninth, alone or in combination with one or more of aspects one to thirty-eight, the pseudo time slot index designated for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0239] In the fortieth aspect, alone or in combination with one or more of the first to thirty-ninth aspects, the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and indicate that one or more resources in the PSFCH resource pool are explicitly allocated to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0240] In the forty-first aspect, sending one or more HARQ responses, alone or in combination with one or more of the first to fortieth aspects, includes sending one or more HARQ responses to the first UE on one or more resources of the PSFCH resource pool for one or more sidelink communications on the secondary carrier.

[0241] In aspect 42, alone or in combination with one or more of aspects 1 to 41, process 1500 includes: receiving side link control information from the first UE for polling HARQ responses other than one or more HARQ responses received on one or more resources of the PSFCH resource pool.

[0242] In a 43rd aspect, alone or in combination with one or more of aspects 1 to 42, the primary carrier is a licensed carrier and the secondary carrier is an unlicensed carrier.

[0243] although Figure 15 Example blocks of process 1500 are shown, but in some aspects, process 1500 may include Figure 15Additional blocks, fewer blocks, different blocks, or differently arranged blocks than the blocks shown in . Additionally or alternatively, two or more of the blocks in process 1500 may be executed in parallel.

[0244] The following provides a summary of some aspects of the disclosure:

[0245] Aspect 1: A method of wireless communication performed by a first user equipment (UE), comprising: sending an indication to a second UE via a sidelink subchannel of a primary carrier identifying one or more resources on the primary carrier for sending one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and receiving the one or more HARQ responses for the one or more sidelink communications on the secondary carrier from the second UE on the one or more resources on the primary carrier.

[0246] Aspect 2: The method according to aspect 1, wherein the primary carrier is a licensed carrier and the secondary carrier is an unlicensed carrier.

[0247] Aspect 3: The method according to any one of aspects 1-2, further comprising: transmitting the one or more sidelink communications on the secondary carrier.

[0248] Aspect 4: The method according to any one of aspects 1-3, wherein the indication identifies a plurality of data channels of the secondary carrier to be used for attempting the one or more sidelink communications between the first UE and the second UE.

[0249] Aspect 5: The method according to any one of aspects 1-4, wherein the indication includes sidelink control information for polling the one or more HARQ responses from the second UE.

[0250] Aspect 6: The method according to aspect 5, wherein the sidelink control information used to poll the one or more HARQ responses from the second UE instructs the second UE to send the one or more HARQ responses as a HARQ codebook.

[0251] Aspect 7: The method according to any one of aspects 5-6, wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier to the second UE to send the one or more HARQ responses.

[0252] Aspect 8: The method according to aspect 7, wherein the dynamic resource pool is orthogonal to the physical sidelink feedback channel resource pool.

[0253] Aspect 9: The method according to any one of aspects 7-8, wherein the dynamic resource pool includes orthogonal resources for sending the one or more HARQ responses.

[0254] Aspect 10: A method according to any one of Aspects 7-9, wherein the sidelink control information uses time domain resource allocation to allocate the dynamic resource pool, which has a gap with the last data of one or more data channels of the auxiliary carrier to be used for the one or more sidelink communications.

[0255] Aspect 11: The method according to any one of aspects 7-10, wherein receiving the one or more HARQ responses includes: receiving the one or more HARQ responses on the one or more resources on the primary carrier included in the dynamic resource pool.

[0256] Aspect 12: The method according to any one of aspects 5-11, wherein the sidelink control information is included in a physical sidelink shared channel communication.

[0257] Aspect 13: A method according to any one of aspects 1-4, wherein the indication indicates to the second UE to store the one or more HARQ responses and wait for sidelink control information for polling the one or more HARQ responses from the second UE.

[0258] Aspect 14: The method according to aspect 13 further includes: sending the sidelink control information for polling the one or more HARQ responses from the second UE to the second UE.

[0259] Aspect 15: The method of aspect 14, wherein the one or more HARQ responses are received based at least in part on the sidelink control information used to poll for the one or more HARQ responses from the second UE.

[0260] Aspect 16: A method according to any one of Aspects 14-15, wherein receiving the one or more HARQ responses includes: receiving an aggregated HARQ response for multiple sidelink communications between the first UE and the second UE on the secondary carrier from the second UE on the primary carrier based at least in part on the sidelink control information.

[0261] Aspect 17: A method according to any one of Aspects 14-16, wherein the sidelink control information is sent to the second UE and one or more other UEs to poll the one or more HARQ responses from the second UE, and to poll one or more HARQ responses from the one or more other UEs.

[0262] Aspect 18: The method according to any one of aspects 14-17, wherein the sidelink control information polls the one or more HARQ responses and other control information from the second UE.

[0263] Aspect 19: The method according to aspect 18, wherein the other control information includes at least one of a scheduling request or a buffer status report.

[0264] Aspect 20: A method according to any one of Aspects 1-4, wherein the indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

[0265] Aspect 21: The method according to aspect 20, wherein the secondary PSFCH resource pool is orthogonal to a primary PSFCH resource pool used for HARQ responses for sidelink communications on the licensed carrier.

[0266] Aspect 22: The method according to aspect 21, wherein the secondary PSFCH resource pool is frequency division multiplexed to the primary PSFCH resource pool.

[0267] Aspect 23: The method according to any one of aspects 21-22, wherein the secondary PSFCH resource pool is time-division multiplexed to the primary PSFCH resource pool.

[0268] Aspect 24: The method according to any one of aspects 20-23, wherein the indication instructs the second UE to use implicit resource determination to select one or more of the resources from the secondary PSFCH resource pool to send the one or more HARQ responses.

[0269] Aspect 25: A method according to Aspect 24, wherein the implicit resource determination selects resources from the secondary PSFCH resource pool to send a HARQ response for the sidelink communication based at least in part on a pseudo-subchannel index of the sidelink communication in the one or more sidelink communications on the secondary carrier and a pseudo-time slot index of the sidelink communication, wherein the pseudo-subchannel index of the sidelink communication corresponds to the sidelink subchannel of the licensed carrier on which the indication is sent, and the pseudo-time slot index of the sidelink communication corresponds to a time slot in the main carrier indicated by a starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0270] Aspect 26: A method according to Aspect 25, wherein, when multiple sidelink communications in the one or more sidelink communications have the same pseudo time slot index, the implicit resource determination selects resources from the secondary PSFCH resource pool based at least in part on corresponding multiple physical sidelink shared channel offset values ​​associated with each of the multiple sidelink communications to send corresponding HARQ responses for each of the multiple sidelink communications.

[0271] Aspect 27: The method according to any one of aspects 20-23, wherein the indication explicitly allocates one or more of the resources in the secondary PSFCH resource pool to send the one or more HARQ responses.

[0272] Aspect 28: A method according to Aspect 27, wherein the indication specifies a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof for the sidelink communication among the one or more sidelink communications on the auxiliary carrier.

[0273] Aspect 29: The method of aspect 28, wherein the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of the licensed carrier that is different from the sidelink subchannel of the primary carrier on which the indication is sent.

[0274] Aspect 30: A method according to any one of Aspects 28-29, wherein the pseudo time slot index specified for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0275] Aspect 31: A method according to any one of Aspects 27-30, wherein the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and the indication explicitly allocates the one or more resources of the resources in the secondary PSFCH resource pool to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0276] Aspect 32: The method according to Aspect 31 further includes: monitoring one or more other indications sent by one or more other UEs to avoid allocating one or more resources in the secondary PSFCH resource pool corresponding to a pseudo subchannel index or pseudo time slot index that has been reserved by the one or more other UEs to the cluster of HARQ responses.

[0277] Aspect 33: The method according to any one of Aspects 31-32 further includes: reserving future physical sidelink shared channel communications in the secondary PSFCH resource pool for indexing to the cluster for HARQ response, wherein the indication specifies the subchannel index of the future physical sidelink shared channel communication as a pseudo subchannel index of the cluster for the HARQ response, and specifies the time slot index of the future physical sidelink shared channel communication as a pseudo time slot index of the cluster for the HARQ response.

[0278] Aspect 34: A method according to any one of Aspects 20-33, wherein receiving the one or more HARQ responses includes: receiving the one or more HARQ responses for the one or more sidelink communications on the secondary carrier from the second UE on one or more resources of the resources of the secondary PSFCH resource pool.

[0279] Aspect 35: The method according to aspect 34 also includes: sending sidelink control information to the second UE for polling HARQ responses other than the one or more HARQ responses received on the one or more resources in the resources of the secondary PSFCH resource pool.

[0280] Aspect 36: A method according to any one of Aspects 1-4, wherein the indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

[0281] Aspect 37: The method according to aspect 36, wherein the indication instructs the second UE to use implicit resource determination to select one or more resources from the PSFCH resource pool to send the one or more HARQ responses.

[0282] Aspect 38: A method according to Aspect 37, wherein the implicit resource determination is based at least in part on a secondary carrier index associated with a sidelink communication in the one or more sidelink communications on the secondary carrier and at least in part on a pseudo subchannel index of the sidelink communication, a pseudo time slot index of the sidelink communication, a plurality of physical sidelink shared channel offset values ​​associated with the sidelink communication, or a combination thereof to select resources from the PSFCH resource pool to send a HARQ response for the sidelink communication.

[0283] Aspect 39: A method according to Aspect 38, wherein the pseudo subchannel index of the sidelink communication corresponds to the sidelink subchannel of the main carrier on which the indication is sent, and the pseudo time slot index of the sidelink communication corresponds to the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0284] Aspect 40: The method according to aspect 36, wherein the indication explicitly allocates one or more of the resources in the PSFCH resource pool to send the one or more HARQ responses.

[0285] Aspect 41: A method according to Aspect 40, wherein the indication specifies, for the sidelink communication among the one or more sidelink communications on the auxiliary carrier, an auxiliary carrier index associated with the sidelink communication, a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0286] Aspect 42: The method of aspect 41, wherein the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of the primary carrier that is different from the sidelink subchannel of the primary carrier on which the indication is sent.

[0287] Aspect 43: A method according to any one of Aspects 41-42, wherein the pseudo time slot index specified for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0288] Aspect 44: A method according to any one of Aspects 40-43, wherein the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and the indication explicitly allocates the one or more resources of the resources in the PSFCH resource pool to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0289] Aspect 45: A method according to any one of Aspects 36-44, wherein receiving the one or more HARQ responses includes: receiving the one or more HARQ responses for the one or more sidelink communications on the secondary carrier from the second UE on one or more resources of the PSFCH resource pool.

[0290] Aspect 46: The method according to aspect 45 also includes: sending sidelink control information to the second UE for polling HARQ responses other than the one or more HARQ responses received on the one or more resources of the PSFCH resource pool.

[0291] Aspect 47: A method of wireless communication performed by a second user equipment (UE), comprising: receiving an indication from a first UE via a sidelink subchannel of a primary carrier on how to send one or more hybrid automatic repeat request (HARQ) responses on the primary carrier for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and sending the one or more HARQ responses to the first UE on the primary carrier for the one or more sidelink communications on the secondary carrier based at least in part on the indication.

[0292] Aspect 48: The method of aspect 47, wherein the primary carrier is a licensed carrier and the secondary carrier is an unlicensed carrier.

[0293] Aspect 49: The method according to any one of aspects 47-48, further comprising: receiving the one or more sidelink communications on the secondary carrier.

[0294] Aspect 50: The method of any one of aspects 47-49, wherein the indication identifies a plurality of data channels of the secondary carrier to be used for attempting the one or more sidelink communications between the first UE and the second UE.

[0295] Aspect 51: The method according to any one of aspects 47-50, wherein the indication includes sidelink control information for polling the one or more HARQ responses from the second UE.

[0296] Aspect 52: The method according to aspect 51, wherein the sidelink control information used to poll the one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook.

[0297] Aspect 53: The method according to any one of aspects 51-52, wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier to the second UE to send the one or more HARQ responses.

[0298] Aspect 54: The method according to Aspect 53, wherein the dynamic resource pool is orthogonal to the physical sidelink feedback channel resource pool.

[0299] Aspect 55: The method according to any one of aspects 53-54, wherein the dynamic resource pool includes orthogonal resources for sending the one or more HARQ responses.

[0300] Aspect 56: A method according to any one of Aspects 53-55, wherein the sidelink control information uses time domain resource allocation to allocate the dynamic resource pool, which has a gap with the last data of one or more data channels of the auxiliary carrier to be used for the one or more sidelink communications.

[0301] Aspect 57: The method according to any one of aspects 53-56, wherein sending the one or more HARQ responses includes: sending the one or more HARQ responses on the one or more resources on the primary carrier included in the dynamic resource pool.

[0302] Aspect 58: The method according to any one of aspects 51-57, wherein the sidelink control information is included in a physical sidelink shared channel communication.

[0303] Aspect 59: A method according to any one of aspects 47-50, wherein the indication indicates to the second UE to store the one or more HARQ responses and wait for sidelink control information for polling the one or more HARQ responses from the second UE.

[0304] Aspect 60: The method according to aspect 59 further includes: receiving the sidelink control information for polling the one or more HARQ responses from the second UE.

[0305] Aspect 61: The method of aspect 60, wherein the one or more HARQ responses are sent based at least in part on the sidelink control information used to poll for the one or more HARQ responses from the second UE.

[0306] Aspect 62: A method according to any one of Aspects 60-61, wherein sending the one or more HARQ responses includes: sending an aggregated HARQ response for multiple sidelink communications between the first UE and the second UE on the secondary carrier to the first UE on the primary carrier based at least in part on the sidelink control information.

[0307] Aspect 63: A method according to any one of Aspects 60-62, wherein the sidelink control information is sent to the second UE and one or more other UEs to poll the one or more HARQ responses from the second UE and to poll one or more HARQ responses from the one or more other UEs.

[0308] Aspect 64: The method according to any one of aspects 60-63, wherein the sidelink control information polls the one or more HARQ responses and other control information from the second UE.

[0309] Aspect 65: The method according to aspect 64, wherein the other control information includes at least one of a scheduling request or a buffer status report.

[0310] Aspect 66: A method according to any one of Aspects 47-50, wherein the indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

[0311] Aspect 67: The method of aspect 66, wherein the secondary PSFCH resource pool is orthogonal to a primary PSFCH resource pool used for HARQ responses for sidelink communications on the primary carrier.

[0312] Aspect 68: The method according to aspect 67, wherein the secondary PSFCH resource pool is frequency division multiplexed to the primary PSFCH resource pool.

[0313] Aspect 69: The method according to any one of aspects 67-68, wherein the secondary PSFCH resource pool is time-division multiplexed to the primary PSFCH resource pool.

[0314] Aspect 70: The method according to any one of aspects 66-69, wherein the indication instructs the second UE to use implicit resource determination to select one or more of the resources from the secondary PSFCH resource pool to send the one or more HARQ responses.

[0315] Aspect 71: The method according to Aspect 70 further includes: selecting resources from the secondary PSFCH resource pool to send a HARQ response for the sidelink communication based at least in part on a pseudo subchannel index of the sidelink communication in the one or more sidelink communications on the secondary carrier and a pseudo time slot index of the sidelink communication, wherein the pseudo subchannel index of the sidelink communication corresponds to the sidelink subchannel of the secondary carrier on which the indication is sent, and the pseudo time slot index of the sidelink communication corresponds to the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0316] Aspect 72: A method according to Aspect 71, wherein selecting the resources from the secondary PSFCH resource pool includes: when multiple sidelink communications in the one or more sidelink communications have the same pseudo time slot index, selecting the resources from the secondary PSFCH resource pool at least in part based on the corresponding multiple physical sidelink shared channel offset values ​​associated with each of the multiple sidelink communications to send a corresponding HARQ response for each of the multiple sidelink communications.

[0317] Aspect 73: The method according to any one of aspects 66-69, wherein the indication explicitly allocates one or more of the resources in the secondary PSFCH resource pool to transmit the one or more HARQ responses.

[0318] Aspect 74: A method according to Aspect 73, wherein the indication specifies a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof for the sidelink communication among the one or more sidelink communications on the auxiliary carrier.

[0319] Aspect 75: The method of aspect 74, wherein the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of the primary carrier that is different from the sidelink subchannel of the primary carrier on which the indication is sent.

[0320] Aspect 76: A method according to any one of Aspects 74-75, wherein the pseudo time slot index specified for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0321] Aspect 77: A method according to any one of Aspects 73-76, wherein the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and the indication explicitly allocates the one or more resources of the resources in the secondary PSFCH resource pool to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0322] Aspect 78: A method according to any one of Aspects 66-77, wherein sending the one or more HARQ responses includes: sending the one or more HARQ responses for the one or more sidelink communications on the secondary carrier to the first UE on one or more resources of the resources of the secondary PSFCH resource pool.

[0323] Aspect 79: The method according to Aspect 78 also includes: receiving sidelink control information from the first UE for polling HARQ responses other than the one or more HARQ responses sent on the one or more resources in the resources of the secondary PSFCH resource pool.

[0324] Aspect 80: A method according to any one of Aspects 47-50, wherein the indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

[0325] Aspect 81: The method of aspect 80, wherein the indication instructs the second UE to use implicit resource determination to select one or more resources from the PSFCH resource pool to send the one or more HARQ responses.

[0326] Aspect 82: The method according to Aspect 81 also includes: selecting resources from the PSFCH resource pool to send a HARQ response for the sidelink communication based at least in part on a secondary carrier index associated with the sidelink communication of the one or more sidelink communications on the secondary carrier and at least in part on a pseudo subchannel index of the sidelink communication, a pseudo time slot index of the sidelink communication, a plurality of physical sidelink shared channel offset values ​​associated with the sidelink communication, or a combination thereof.

[0327] Aspect 83: A method according to Aspect 82, wherein the pseudo subchannel index of the sidelink communication corresponds to the sidelink subchannel of the main carrier on which the indication is sent, and the pseudo time slot index of the sidelink communication corresponds to the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0328] Aspect 84: The method of aspect 80, wherein the indication explicitly allocates one or more of the resources in the PSFCH resource pool to transmit the one or more HARQ responses.

[0329] Aspect 85: A method according to Aspect 84, wherein the indication specifies, for the sidelink communication among the one or more sidelink communications on the auxiliary carrier, an auxiliary carrier index associated with the sidelink communication, a pseudo subchannel index for the sidelink communication, a pseudo time slot index for the sidelink communication, values ​​for multiple physical sidelink shared channel offsets associated with the sidelink communication, a base sequence for a sequence-based PSFCH waveform, or a combination thereof.

[0330] Aspect 86: The method of aspect 85, wherein the pseudo subchannel index designated for the sidelink communication corresponds to a sidelink subchannel of the primary carrier that is different from the sidelink subchannel of the primary carrier on which the indication is sent.

[0331] Aspect 87: A method according to any one of Aspects 85-86, wherein the pseudo time slot index specified for the sidelink communication corresponds to a time slot in the main carrier that is different from the time slot in the main carrier indicated by the starting orthogonal frequency division multiplexing symbol of the sidelink communication.

[0332] Aspect 88: A method according to any one of Aspects 84-87, wherein the one or more sidelink communications on the secondary carrier include multiple sidelink communications on the secondary carrier, and the indication explicitly allocates the one or more resources of the resources in the PSFCH resource pool to cluster multiple HARQ responses for the multiple sidelink communications in the time domain, the frequency domain, or a combination thereof.

[0333] Aspect 89: A method according to any one of Aspects 84-88, wherein sending the one or more HARQ responses includes: sending the one or more HARQ responses for the one or more sidelink communications on the secondary carrier to the first UE on one or more resources of the PSFCH resource pool.

[0334] Aspect 90: The method according to aspect 89 further includes: receiving sidelink control information from the first UE for polling HARQ responses other than the one or more HARQ responses received on the one or more resources of the PSFCH resource pool.

[0335] Aspect 91: 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 one or more of the methods described in aspects 1-46.

[0336] Aspect 92: 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 47-90.

[0337] Aspect 93: An apparatus for wireless communication, comprising: a memory and one or more processors coupled to the memory, the one or more processors configured to perform the method according to one or more of aspects 1-46.

[0338] Aspect 94: An apparatus for wireless communication, comprising: a memory and one or more processors coupled to the memory, the one or more processors configured to perform the method according to one or more of aspects 47-90.

[0339] Aspect 95: An apparatus for wireless communication, comprising: at least one means for performing the method according to one or more of aspects 1-46.

[0340] Aspect 96: An apparatus for wireless communication, comprising: at least one means for performing the method according to one or more of aspects 47-90.

[0341] Aspect 97: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method according to one or more of aspects 1-46.

[0342] Aspect 98: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method according to one or more of aspects 47-90.

[0343] Aspect 99: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising: one or more instructions that, when executed by one or more processors of a device, cause the device to perform one or more of the methods described in aspects 1-46.

[0344] Aspect 100: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising: one or more instructions that, when executed by one or more processors of a device, cause the device to perform one or more of the methods described in aspects 47-90.

[0345] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the various aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the various aspects.

[0346] As used herein, the term "component" is intended to be broadly interpreted as hardware and / or a combination of hardware and software. Whether referred to as software, firmware, middleware, microcode, hardware description language or other, software should be broadly interpreted as instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes and / or functions, etc. As used herein, a processor is implemented in hardware and / or a combination of hardware and software. It will be apparent that the 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 and software code used to implement these systems and / or methods are not limitations of various aspects. Therefore, the operation and behavior of the systems and / or methods are not described herein with reference to specific software codes-it is to be understood that software and hardware can be designed to implement the systems and / or methods based at least in part on the description herein.

[0347] As used herein, satisfying a threshold may refer to a value that is greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc., depending on the context.

[0348] Although specific feature combination is recorded in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features can be combined in a manner not recorded in the claims and / or disclosed in the specification. Although each dependent claim as listed below can directly quote only one claim, the disclosure of various aspects includes the combination of each dependent claim and any other claim in the claim set. As used herein, the phrase of "at least one of" quoting item list refers to any combination of those items, including single members. For example, "at least one of a, b or c" is intended to encompass a, b, c, ab, ac, bc and abc, and any combination with the multiple of the same element (for example, aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc and ccc, or any other sorting of a, b and c).

[0349] Elements, actions or instructions used herein should not be interpreted as being critical or necessary unless clearly described. Moreover, as used herein, the articles "a" and "an" are intended to include one or more projects and can be used interchangeably with "one or more". In addition, as used herein, the article "the" is intended to include one or more projects cited in conjunction with the article "the", and can be used interchangeably with "one or more". In addition, as used herein, the terms "set" and "group" are intended to include one or more projects (for example, related projects, unrelated projects, or a combination of related projects and unrelated projects), and can be used interchangeably with "one or more". In the case where only one project is expected, phrase "only one" or similar language is used. Moreover, as used herein, the terms "have", "possess", "have" etc. are intended to be open terms. In addition, the phrase "based on" is intended to represent "at least partially based on", unless otherwise clearly stated. Furthermore, as used herein, the term "or" when used in a serial form is intended to be inclusive and can be used interchangeably with "and / or" unless expressly stated otherwise (e.g., if used in combination with "either" or "only one of").

Claims

1. A method of wireless communication performed by a first user equipment (UE), comprising: transmitting, to a second UE via a sidelink subchannel of a primary carrier, an indication identifying one or more resources on the primary carrier for transmitting one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; as well as The one or more HARQ responses for the one or more sidelink communications on the secondary carrier are received from the second UE on the one or more resources on the primary carrier.

2. The method according to claim 1, wherein The primary carrier is a licensed carrier, and the secondary carrier is an unlicensed carrier.

3. The method according to claim 1, wherein The indication includes sidelink control information for polling the one or more HARQ responses from the second UE, wherein the sidelink control information for polling the one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook, and wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier for the second UE to send the one or more HARQ responses.

4. The method according to claim 1, wherein The indication instructs the second UE to store the one or more HARQ responses and wait for sidelink control information for polling the one or more HARQ responses from the second UE, and the method further includes: The sidelink control information for polling for the one or more HARQ responses from the second UE is sent to the second UE.

5. The method according to claim 1, wherein The indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

6. The method according to claim 1, wherein The indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

7. A method of wireless communication performed by a second user equipment (UE), comprising: receiving, from a first UE via a sidelink subchannel of a primary carrier, an indication of how to transmit, on the primary carrier, one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and The one or more HARQ responses for the one or more sidelink communications on the secondary carrier are sent to the first UE on the primary carrier based at least in part on the indication.

8. The method according to claim 7, wherein: The primary carrier is a licensed carrier, and the secondary carrier is an unlicensed carrier.

9. The method according to claim 7, wherein: The indication includes sidelink control information for polling the one or more HARQ responses from the second UE, wherein the sidelink control information for polling the one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook, and wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier for the second UE to send the one or more HARQ responses.

10. The method according to claim 7, wherein: The indication instructs the second UE to store the one or more HARQ responses and wait for sidelink control information for polling the one or more HARQ responses from the second UE, and the method further includes: Receive the sidelink control information for polling the one or more HARQ responses from the second UE, wherein the one or more HARQ responses are sent based at least in part on the sidelink control information for polling the one or more HARQ responses from the second UE.

11. The method according to claim 7, wherein: The indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

12. The method according to claim 7, wherein: The indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

13. A first user equipment (UE) for wireless communication, comprising: Memory; as well as one or more processors coupled to the memory, the one or more processors configured to: transmitting, to a second UE via a sidelink subchannel of a primary carrier, an indication identifying one or more resources on the primary carrier for transmitting one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; as well as The one or more HARQ responses for the one or more sidelink communications on the secondary carrier are received from the second UE on the one or more resources on the primary carrier.

14. The first UE according to claim 13, wherein: The primary carrier is a licensed carrier, and the secondary carrier is an unlicensed carrier.

15. The first UE according to claim 13, wherein: The indication includes sidelink control information for polling the one or more HARQ responses from the second UE, wherein the sidelink control information for polling the one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook, and wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier for the second UE to send the one or more HARQ responses. The first UE according to claim 13 , wherein: The indication instructs the second UE to store the one or more HARQ responses and wait for sidelink control information for polling for the one or more HARQ responses from the second UE, and the one or more processors are further configured to: The sidelink control information for polling for the one or more HARQ responses from the second UE is sent to the second UE.

17. The first UE according to claim 13, wherein: The indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

18. The first UE according to claim 17, wherein: The indication instructs the second UE to select one or more of the resources from the secondary PSFCH resource pool for sending the one or more HARQ responses using implicit resource determination. The first UE according to claim 17 , wherein: The indication explicitly allocates one or more of the resources in the secondary PSFCH resource pool for sending the one or more HARQ responses.

20. The first UE according to claim 13, wherein: The indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

21. The first UE according to claim 20, wherein: The indication instructs the second UE to select one or more resources from the PSFCH resource pool for sending the one or more HARQ responses using implicit resource determination.

22. The first UE according to claim 20, wherein: The indication explicitly allocates one or more of the resources in the PSFCH resource pool for sending the one or more HARQ responses.

23. A second user equipment (UE) for wireless communication, comprising: Memory; as well as one or more processors coupled to the memory, the one or more processors configured to: receiving, from a first UE via a sidelink subchannel of a primary carrier, an indication of how to transmit, on the primary carrier, one or more hybrid automatic repeat request (HARQ) responses for one or more sidelink communications between the first UE and the second UE on a secondary carrier; and The one or more HARQ responses for the one or more sidelink communications on the secondary carrier are sent to the first UE on the primary carrier based at least in part on the indication.

24. The second UE according to claim 23, wherein: The primary carrier is a licensed carrier, and the secondary carrier is an unlicensed carrier.

25. The second UE according to claim 23, wherein: The indication includes sidelink control information for polling the one or more HARQ responses from the second UE, wherein the sidelink control information for polling the one or more HARQ responses from the second UE indicates to the second UE to send the one or more HARQ responses as a HARQ codebook, and wherein the sidelink control information allocates a dynamic resource pool including one or more resources on the primary carrier for the second UE to send the one or more HARQ responses.

26. The second UE according to claim 23, wherein: The indication instructs the second UE to store the one or more HARQ responses and wait for sidelink control information for polling for the one or more HARQ responses from the second UE, and the one or more processors are further configured to: Receive the sidelink control information for polling the one or more HARQ responses from the second UE, wherein the one or more HARQ responses are sent based at least in part on the sidelink control information for polling the one or more HARQ responses from the second UE.

27. The second UE according to claim 23, wherein: The indication identifies a secondary physical sidelink feedback channel (PSFCH) resource pool including resources on the primary carrier allocated for the one or more HARQ responses for the one or more sidelink communications between the first UE and the second UE on the secondary carrier.

28. The second UE according to claim 27, wherein: The indication instructs the second UE to use implicit resource determination to select one or more of the resources from the secondary PSFCH resource pool for sending the one or more HARQ responses, or the indication explicitly allocates one or more of the resources in the secondary PSFCH resource pool for sending the one or more HARQ responses.

29. The second UE according to claim 23, wherein: The indication is used to configure the second UE to multiplex the one or more HARQ responses for the one or more sidelink communications on the secondary carrier into a physical sidelink feedback channel (PSFCH) resource pool for HARQ responses for sidelink communications on the primary carrier.

30. The second UE according to claim 29, wherein: The indication instructs the second UE to use implicit resource determination to select one or more resources from the PSFCH resource pool for sending the one or more HARQ responses, or the indication explicitly allocates one or more resources in the PSFCH resource pool for sending the one or more HARQ responses.

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