Methods and apparatuses for device-to-device feedback

Abstract

Describes a wireless communication device and method related to wireless communication. For example, device-to-device feedback is described. In various aspects, a method of wireless communication may include: using a sidelink communication structure to transmit sidelink traffic communication; and using at least one feedback symbol of the sidelink communication structure to transmit an allocation for sidelink feedback. In various aspects, the method includes: a first wireless communication device using at least one feedback symbol of the sidelink communication structure to transmit sidelink feedback communication, where the sidelink feedback communication is associated with the sidelink traffic communication. Numerous other aspects are provided.

Description

[0001] This application is a divisional application of the invention patent application with the application date of October 11, 2018, application number 201880065827.7, and title "Methods and Apparatus for Device-to-Device Feedback".

[0002] Priority Claim

[0003] This patent application claims the benefit of priority from the following applications: U.S. Non-Provisional Application No. 16 / 156,646, filed on October 10, 2018, and entitled "METHODS AND APPARATUS FOR DEVICE-TO-DEVICE FEEDBACK"; and U.S. Provisional Application No. 62 / 571,037, filed on October 11, 2017, and entitled "METHODS AND APPARATUS FOR DEVICE-TO-DEVICE FEEDBACK", which are assigned to the assignee of this application and are hereby incorporated herein by reference in their entirety. Technical Field

[0004] This application relates to wireless communication systems, and more particularly, to methods and apparatus for device-to-device feedback. Background Art

[0005] Wireless communication systems have been widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ a multiple access technology that is capable of supporting communication with multiple users by sharing available system resources. 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, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems.

[0006] To provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels, these multiple access technologies have been adopted in various telecommunication standards. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution released by the Third Generation Partnership Project (3GPP) to meet new requirements and other requirements associated with latency, reliability, security, scalability (e.g., along with the Internet of Things (IoT)). Some aspects of 5G NR can be based on the 4G Long-Term Evolution (LTE) standard. An area of interest for further development of 5G NR and other communication standards (such as LTE) is device-to-device (D2D) communication, which can include vehicle-to-everything (V2X) communication and vehicle-to-vehicle (V2V) communication. In D2D, devices can communicate directly with each other via sidelink communication. Summary of the Invention

[0007] A brief overview of one or more aspects is given below to provide a basic understanding of such aspects. This overview is not an extensive generalization of all the expected aspects and is not intended to identify key or important elements of all aspects or to describe the scope of any or all aspects. Its sole purpose is to serve as a preface to the more detailed description given later and to present some concepts of one or more aspects in a simplified form.

[0008] For example, in one aspect of the present disclosure, a method for wireless communication includes: transmitting sidelink traffic communication using a sidelink communication structure; and transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In aspects, the method includes: a first wireless communication device transmitting sidelink feedback communication using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communication is associated with the sidelink traffic communication.

[0009] In another aspect of the present disclosure, a wireless communication device for wireless communication includes: a memory; and at least one processor coupled to the memory, the at least one processor configured to: transmit sidelink traffic communication using a sidelink communication structure; and transmit an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In aspects, the at least one processor is further configured to: transmit sidelink feedback communication using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communication is associated with the sidelink traffic communication.

[0010] In another aspect of the present disclosure, a non-transitory computer-readable medium stores one or more instructions for wireless communication by a wireless communication device, the one or more instructions, when executed by one or more processors of a user equipment, cause the one or more processors to perform the following operations: use a sidelink communication structure to transmit sidelink traffic communication; and use at least one feedback symbol of the sidelink communication structure to transmit an allocation for sidelink feedback. In aspects, the one or more instructions, when executed by one or more processors of a user equipment, cause the one or more processors to perform the following operations: transmit sidelink feedback communication using at least one feedback symbol of the sidelink communication structure by a first wireless communication device, wherein the sidelink feedback communication is associated with the sidelink traffic communication.

[0011] In another aspect of the present disclosure, an apparatus for wireless communication includes: a unit for using a sidelink communication structure to transmit sidelink traffic communication; and a unit for using at least one feedback symbol of the sidelink communication structure to transmit an allocation for sidelink feedback. In aspects, the apparatus further includes: a unit for transmitting sidelink feedback communication using at least one feedback symbol of the sidelink communication structure by a first wireless communication device, wherein the sidelink feedback communication is associated with the sidelink traffic communication.

[0012] Other aspects, features, and embodiments of the present disclosure will become apparent to those of ordinary skill in the art when reviewing the following description of specific exemplary embodiments in conjunction with the accompanying drawings. Although the following may discuss features with respect to certain embodiments and drawings, all embodiments may include one or more of the advantageous features discussed herein. In other words, although one or more embodiments may be discussed as having certain advantageous features, one or more of these features may also be used in accordance with the various embodiments discussed herein. In a similar manner, although the exemplary embodiments may be discussed below as device, system, or method embodiments, it should be understood that such exemplary embodiments may be implemented in various devices, systems, and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network in accordance with various aspects of the present disclosure.

[0014] Figure 2A 、 2B 、2C, and 2D are diagrams respectively illustrating examples of a DL frame structure, DL channels within the DL frame structure, a UL frame structure, and UL channels within the UL frame structure.

[0015] Figure 3FIG. is a diagram illustrating examples of a base station and a user equipment (UE) in an access network in accordance with various aspects of the present disclosure.

[0016] Figure 4 FIG. is a diagram illustrating a wireless communication system in accordance with various aspects of the present disclosure.

[0017] Figure 5 FIG. is a diagram illustrating an example sidelink communication structure in accordance with various aspects of the present disclosure.

[0018] Figure 6 FIG. is a diagram illustrating an example sidelink communication structure in accordance with various aspects of the present disclosure.

[0019] Figure 7 FIG. is a diagram illustrating a sidelink communication structure having at least one feedback symbol in accordance with various aspects of the present disclosure.

[0020] Figure 8 FIG. is a flowchart of a method for wireless communication in accordance with various aspects of the present disclosure.

[0021] Figure 9 FIG. is a diagram illustrating an example hardware implementation of an apparatus for wireless communication employing a processing system in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION

[0022] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. For the purpose of providing a thorough understanding of the various concepts, the detailed description includes specific details. It will be apparent, however, to one of ordinary skill in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0023] Certain aspects of the telecommunications systems will now be presented with reference to various apparatuses and methods. These apparatuses and methods will be described in detail below and are illustrated by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements") in the accompanying drawings. These elements may be implemented using either electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0024] For example, an element, or any portion of an element, or any combination of elements can be implemented as a "processing system" that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in the processing system can execute software. Software should be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc., regardless of whether it is referred to as software, firmware, middleware, microcode, hardware description language, or other names.

[0025] Accordingly, in one or more exemplary embodiments, the described functions can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored or encoded on a computer-readable medium as one or more instructions or code. Computer-readable media includes computer storage media. Storage media can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium capable of storing computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0026] Figure 1 FIG. is a diagram illustrating an example of a wireless communication system and an access network 100 in accordance with various aspects of the present disclosure. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, and an evolved packet core (EPC) 160. The base station 102 can include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macro cells include base stations. Small cells include femtocells, picocells, and microcells.

[0027] The base stations 102 (collectively referred to as the evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) are interfaced with the EPC 160 via a backhaul link 132 (e.g., the S1 interface). In addition to other functions, the base stations 102 may perform one or more of the following functions: transmission of user data, encryption and decryption of radio channels, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), user and device tracking, radio access network information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate directly or indirectly (e.g., via the EPC 160) with each other over a backhaul link 134 (e.g., the X2 interface). The backhaul link 134 may be wired or wireless.

[0028] The base stations 102 may communicate wirelessly with the UEs 104. Each of the base stations 102 may provide communication coverage for a corresponding geographical coverage area 110. There may be overlapping geographical coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network including both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may serve a restricted group referred to as a closed subscriber group (CSG). The communication link 120 between the base stations 102 and the UEs 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, which includes spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be through one or more carriers. The base stations 102 / UEs 104 may use a spectrum of up to Yx MHz (x component carriers) in total for transmission in each direction, with each carrier having a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz), for example, in carrier aggregation. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to the DL and UL (e.g., more or fewer carriers may be allocated for the DL compared to the UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as the primary cell (PCell), and the secondary component carriers may be referred to as secondary cells (SCells).

[0029] In various aspects, a wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communicating to determine if the channel is available.

[0030] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may enhance the coverage of the access network and / or increase the capacity of the access network.

[0031] A gNodeB (gNB) 180 may operate in millimeter wave (mmW) frequencies and / or near mmW frequencies to communicate with a UE 104. When the gNB 180 operates in the mmW or near mmW spectrum, the gNB 180 may be referred to as a mmW base station. The extremely high frequency (EHF) is a part of the RF in the electromagnetic spectrum. The EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. The radio waves in the band may be referred to as millimeter waves. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as centimeter waves. Communication using the mmW / near mmW radio frequency band has extremely high path loss and a short range. The mmW base station 180 may use beamforming 184 with the UE 104 to compensate for the extremely high path loss and short range.

[0032] The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may communicate with a Home Subscriber Server (HSS) 174. The MME 162 is a control node that processes signaling between the UE 104 and the EPC 160. Generally speaking, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transported through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides IP address allocation for the UE and other functions. The PDN Gateway 172 and the BM-SC 170 are connected to an IP service 176. The IP service 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packet Switched Streaming Service (PSS), and / or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for MBMS transmissions for content providers, may be used to authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to allocate MBMS services to base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area for a particular broadcast service, and may be responsible for session management (start / stop) and for collecting charging information related to eMBMS.

[0033] A base station may also be referred to as a gNB, Node B, evolved Node B (eNB), access point, base station transceiver, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), or some other suitable term. Base station 102 provides an access point to EPC 160 for UE 104. Examples of UE 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptop computers, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electricity meters, gas pumps, ovens, or any other device with similar functionality. Some of the UEs in UE 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, etc.). UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, radio unit, remote unit, mobile device, radio device, radio communication device, remote device, mobile subscriber station, access terminal, mobile terminal, radio terminal, remote terminal, handheld device, user agent, mobile client, client, or some other suitable term.

[0034] Referring again to Figure 1 , in some aspects, UE 104 may be configured to perform sidelink communication with a second UE 104' (e.g., using a carrier 192 such as a sidelink carrier) for device-to-device (D2D) communication. In various aspects, D2D communication may include vehicle-to-everything (V2X) communication or vehicle-to-vehicle (V2V) communication. UE 104 may communicate with the second UE 104' via carrier 192 using one or more sidelink communication structures having at least one feedback symbol. In one aspect, at least a portion of the multiple frequency bands for carrier 192 corresponds to the intelligent transportation system spectrum for a sidelink carrier. In various aspects, D2D communication may include D2D feedback (e.g., D2D sidelink feedback) communication as described herein.

[0035] Figure 2A FIG. 200 is a diagram illustrating an example frame structure of one or more downlink (DL) frames in accordance with various aspects of the present disclosure. Figure 2B FIG. 230 is a diagram illustrating an example of channels within the frame structure of a DL frame in accordance with various aspects of the present disclosure. Figure 2C FIG. 250 is an example of a diagram illustrating an example frame structure of one or more uplink (UL) frames in accordance with various aspects of the present disclosure. Figure 2DFIG. 280 is an example of a diagram showing channels within a frame structure of a UL frame in accordance with various aspects of the present disclosure. Other wireless communication technologies may have different frame structures and / or different channels. A frame (e.g., a 10 ms frame) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including one or more time-concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into a plurality of resource elements (REs). For a normal cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain (e.g., for a 15 kHz subcarrier spacing) and 7 consecutive symbols in the time domain (OFDM symbols for DL; SC-FDMA symbols for UL), for a total of 84 REs. For an extended cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

[0036] As Figure 2A shown, some of the REs carry a DL reference (pilot) signal (DL-RS) for channel estimation at the UE. The DL-RS may include a cell-specific reference signal (CRS) (e.g., sometimes also referred to as a common RS), a UE-specific reference signal (UE-RS), and a channel state information reference signal (CSI-RS). Figure 2A FIG. shows the CRSs for antenna ports 0, 1, 2, and 3 (designated as R0, R1, R2, and R3, respectively), the UE-RS for antenna port 5 (designated as R5), and the CSI-RS for antenna port 15 (designated as R). Figure 2B FIG. shows an example of various channels within the DL subframe of a frame. The physical control format indicator channel (PCFICH) is in symbol 0 of time slot 0 and carries a control format indicator (CFI) for indicating whether the physical downlink control channel (PDCCH) occupies 1, 2, or 3 symbols ( Figure 2B FIG. shows a PDCCH occupying 3 symbols). The PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE including nine resource element groups (REGs), each REG including four consecutive REs in an OFDM symbol. A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs ( Figure 2BTwo resource block (RB) pairs are shown, with each subset including one RB pair). The Physical Hybrid Automatic Repeat reQuest (ARQ) (HARQ) Indicator Channel (PHICH) is also within symbol 0 of slot 0 and carries a HARQ indicator (HI), where the HI indicates HARQ acknowledgement (ACK) / negative ACK (NACK) feedback based on the Physical Uplink Shared Channel (PUSCH). The Primary Synchronization Channel (PSCH) can be within symbol 6 of slot 0 in subframes 0 and 5 of a frame. The PSCH carries the Primary Synchronization Signal (PSS) that is used by the UE to determine subframe / symbol timing and the physical layer identity. The Secondary Synchronization Channel (SSCH) can be within symbol 5 of slot 0 in subframes 0 and 5 of a frame. The SSCH carries the Secondary Synchronization Signal (SSS) that is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE is able to determine the Physical Cell Identifier (PCI). Based on the PCI, the UE is able to determine the location of the aforementioned DL-RS. The Physical Broadcast Channel (PBCH) carrying the Master Information Block (MIB) can be logically grouped with the PSCH and SSCH to form a Synchronization Signal (SS) block. The MIB provides the number of RBs in the DL system bandwidth, the PHCIH configuration, and the System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not sent via the PBCH (such as System Information Blocks (SIB)), and paging messages.

[0037] As Figure 2C shown, some of the resource elements (REs) carry Demodulation Reference Signals (DM-RS) for channel estimation at the base station. The UE can additionally transmit a Sounding Reference Signal (SRS) in the last symbol of a subframe. The SRS can have a comb structure, and the UE can transmit the SRS on one of the combs. The SRS can be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL. Figure 2D An example of various channels within the UL subframe of a frame is shown. Based on the Physical Random Access Channel (PRACH) configuration, the PRACH can be located within one or more subframes of a frame. The PRACH can include six consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. The Physical Uplink Control Channel (PUCCH) can be located at the edge of the UL system bandwidth. The PUCCH carries uplink control information (UCI), such as a scheduling request, a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indicator (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and can additionally be used to carry a Buffer Status Report (BSR), a Power Headroom Report (PHR), and / or UCI.

[0038] Figure 3It is a block diagram of the communication between the base station 310 and the UE 350 in the access network. In the DL, IP packets from the EPC 160 can be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functions. Layer 3 includes the radio resource control (RRC) layer, and layer 2 includes the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, and the media access control (MAC) layer. The controller / processor 375 provides: RRC layer functions, which are associated with: the broadcast of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions, which are associated with: header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions, which are associated with: the transfer of upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functions, which are associated with: the mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0039] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1, which includes the physical (PHY) layer, may include error detection for the transmission channel, forward error correction (FEC) encoding / decoding for the transmission channel, interleaving, rate matching, mapping onto the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). Subsequently, the encoded and modulated symbols may be divided into parallel streams. Subsequently, each stream may be mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time domain and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a stream of time-domain OFDM symbols. The OFDM stream is spatially precoded to generate multiple spatial streams. Channel estimates from the channel estimator 374 may be used to determine the encoding and modulation schemes and for spatial processing. Channel estimates may be derived from reference signals transmitted by the UE 350 and / or channel status feedback. Subsequently, each spatial stream is provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with the corresponding spatial stream for transmission.

[0040] At the UE 350, each receiver 354RX receives signals via its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, the RX processor 356 may combine them into a single OFDM symbol stream. Subsequently, the RX processor 356 uses a fast Fourier transform (FFT) to transform the OFDM symbol stream from the time domain to the frequency domain. The frequency-domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on the channel estimates computed by the channel estimator 358. Subsequently, the soft decisions are decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 310 on the physical channel. Subsequently, the data and control signals are provided to the controller / processor 359, which implements layer 3 and layer 2 functions.

[0041] The controller / processor 359 may be associated with a memory 360 that stores program code and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using the ACK and / or NACK protocols to support HARQ operations.

[0042] Similar to the functions described in connection with DL transmissions performed by the base station 310, the controller / processor 359 provides: RRC layer functions that are associated with: system information (e.g., MIB, SIB) acquisition, RRC connection, and test reporting; PDCP layer functions that are associated with: header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions that are associated with: transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functions that are associated with: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0043] Channel estimates derived by the channel estimator 358 from reference signals or feedback transmitted by the base station 310 may be used by the TX processor 368 to select appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via a separate transmitter 354TX. Each transmitter 354TX may modulate an RF carrier using the respective spatial stream for transmission.

[0044] At the base station 310, UL transmissions are processed in a manner similar to that described in connection with the receiver functions at the UE 350. Each receiver 318RX receives signals via its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to the RX processor 370.

[0045] The controller / processor 375 may be associated with a memory 376 that stores program code and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for supporting HARQ operations using error detection with the ACK and / or NACK protocols.

[0046] One or more components of the UE 350 may be configured to perform methods of D2D feedback, as described in more detail elsewhere herein. For example, the controller / processor 359 and / or other processors and modules of the UE 350 may execute or direct the operation of, for example Figure 8 process 800 and / or other processes as described herein. In some aspects, one or more of the components shown in Figure 3 may be employed to perform Figure 8 the exemplary process 800 and / or other processes as described herein.

[0047] In some aspects, the UE 350 may include: a unit for transmitting sidelink traffic communications using a sidelink communication structure; and a unit for transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In some aspects, the UE 350 may include: a unit for transmitting sidelink feedback communications using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communications are associated with the sidelink traffic communications. In some aspects, such a unit may include one or more components of the UE 350 described in conjunction with Figure 3 the foregoing.

[0048] Figure 4 is a diagram of a D2D communication system 400 (e.g., which may include a V2X communication system and / or a V2V communication system). For example, the D2D communication system 400 may include a first vehicle 450' that communicates with a second vehicle 451'. In some aspects, the first vehicle 450' and / or the second vehicle 451' may be configured to communicate in a specific spectrum, such as an intelligent transportation system (ITS) spectrum. The ITS spectrum may be unlicensed, and thus a variety of different technologies may use the ITS spectrum for communication, including LTE, enhanced LTE, licensed-assisted access (LAA), dedicated short-range communications (DSRC), 5G, new radio (NR), 4G, etc. The foregoing list of technologies should be considered illustrative and not meant to be exhaustive.

[0049] The D2D communication system 400 may utilize LTE technology or another technology (e.g., 5G NR). For example, vehicles in D2D communication may incorporate UEs of LTE or 5G NR technology therein. In D2D communication (e.g., V2X communication or V2V communication), vehicles 450’, 451’ may be on networks of different mobile network operators (MNOs). Each of these networks may operate in its own spectrum. For example, the air interface (e.g., Uu interface) to the first vehicle 450’ may be on one or more frequency bands different from the air interface of the second vehicle 451’. The first vehicle 450’ and the second vehicle 451’ may communicate (e.g., via the PC5 interface) via a sidelink (e.g., using a carrier such as sidelink carrier 192). In some examples, the MNO may schedule sidelink communication between and among the vehicles 450’, 451’ in the V2X spectrum (e.g., V2V spectrum). Examples of the V2X spectrum may include the intelligent transportation system (ITS) spectrum. The ITS spectrum may be unlicensed, and thus a variety of different technologies may use the ITS spectrum for communication, including LTE, enhanced LTE, licensed assisted access (LAA), dedicated short range communications (DSRC), 5G, new radio (NR), 4G, etc. The foregoing list of technologies should be considered illustrative and not meant to be exhaustive. However, in some aspects, D2D communication (e.g., sidelink communication) between and among the vehicles 450’, 451’ is not scheduled by the MNO.

[0050] In a case where devices (e.g., vehicles) operate on networks of different MNOs and / or in different spectrums, there may be a D2D communication system 400. For example, each of the vehicles in a D2D (e.g., V2V or V2X) communication system may have a subscription from its respective corresponding MNO. The V2X spectrum may be shared with the MNO's spectrum. In some examples, a D2D (e.g., V2V or V2X) communication system 400 may be deployed in a case where the first vehicle 450’ operates on a network operated by the first MNO while the second vehicle 451’ is not on the network (e.g., the V2X spectrum may not have a deployed network).

[0051] The first vehicle 450' can perform D2D (e.g., V2V or V2X) communication with the second vehicle 451'. The first vehicle 450' incorporates the first UE 450, while the second vehicle 451' incorporates the second UE 451. The first UE 450 can operate on a first network 410 (e.g., of a first MNO). In various aspects, the D2D communication system 400 can further include a third vehicle 452' incorporating the third UE 452. For example, the third UE 452 can operate on the first network 410 (e.g., of a first MNO) or another network. The third vehicle 452' can perform D2D (e.g., V2V or V2X) communication with the first vehicle 450' and / or the second vehicle 451'.

[0052] The first network 410 operates in a first spectrum and includes a first base station 420 that communicates with at least the first UE 450, such as described in Figures 1-3 . The first base station 420 can communicate with the first UE 450 via a DL carrier 430 and / or a UL carrier 440. DL communication can be performed via the DL carrier 430 using various DL resources (e.g., DL subframes ( Figure 2A ) and / or DL channels ( Figure 2B ). UL communication can be performed via the UL carrier 440 using various UL resources (e.g., UL subframes ( Figure 2C ) and UL channels ( Figure 2D ).

[0053] In some aspects, the second UE 451 may not be on a network. In some aspects, the second UE 451 can be on a second network 411 (e.g., of a second MNO). The second network 411 can operate in a second spectrum (e.g., a second spectrum different from the first spectrum) and can include a second base station 421 that communicates with the second UE 451, such as described in Figures 1-3 .

[0054] The second base station 421 can communicate with the second UE 451 via a DL carrier 431 and a UL carrier 441. DL communication is performed via the DL carrier 431 using various DL resources (e.g., DL subframes ( Figure 2A ) and / or DL channels ( Figure 2B ). UL communication is performed via the UL carrier 441 using various UL resources (e.g., UL subframes ( Figure 2C ) and / or UL channels ( Figure 2D ).

[0055] D2D (e.g., V2V or V2X) communication can be performed via one or more sidelink carriers 470, 480. The one or more sidelink carriers 470, 480 can include one or more channels, e.g., Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Control Channel (PSCCH).

[0056] In some examples, the sidelink carriers 470, 480 can operate using the PC5 interface. The first UE 450 (e.g., incorporated in the first vehicle 450') can transmit to one or more (e.g., multiple) devices via the first sidelink carrier 470 (including transmitting to the second UE 451 (e.g., incorporated in the second vehicle 451')). The second UE 451 can transmit to one or more (e.g., multiple) devices via the second sidelink carrier 480 (including transmitting to the first UE 450 (e.g., incorporated in the vehicle 450')).

[0057] In some aspects, the UL carrier 440 and the first sidelink carrier 470 can be aggregated to increase the bandwidth. In some aspects, the first sidelink carrier 470 and / or the second sidelink carrier 480 can share the first spectrum (with the first network 410) and / or share the second spectrum (with the second network 411). In some aspects, the sidelink carriers 470, 480 can operate in unlicensed spectrum.

[0058] The exemplary methods and apparatuses discussed below are applicable to any of a variety of wireless D2D (e.g., V2V or V2X) communication systems. For simplicity of discussion, these exemplary methods and apparatuses are discussed in the context of LTE. However, those of ordinary skill in the art will understand that these exemplary methods and apparatuses are more generally applicable to a variety of other wireless D2D (e.g., V2V or V2X) communication systems including 5G.

[0059] In various aspects, sidelink communication on a sidelink carrier can occur between a first UE 450 (e.g., incorporated in a first vehicle 450') and a second UE 451 (e.g., incorporated in a second vehicle 451'). In one aspect, the first UE 450 (e.g., incorporated in the first vehicle 450') can perform sidelink communication (including sidelink communication to the second UE 451 (e.g., incorporated in the second vehicle 451')) with one or more (e.g., multiple) devices via a first sidelink carrier 470. For example, the first UE 450 can send a broadcast transmission to multiple devices (e.g., the second UE 451 and a third UE 452) via the first sidelink carrier 470. The second UE 451 (among other UEs) can receive such a broadcast transmission. Additionally or alternatively, the first UE 450 can send a multicast transmission to multiple devices via the first sidelink carrier 470. The second UE 451 (among other UEs) can receive such a multicast transmission. Further, additionally or alternatively, the first UE 450 can send a unicast transmission to a device such as the second UE 451 via the first sidelink carrier 470. The second UE 451 (among other UEs) can receive such a unicast transmission. Additionally or alternatively, in one aspect, the second UE 451 (e.g., incorporated in the second vehicle 451') can perform sidelink communication with one or more (e.g., multiple) devices (including the first UE 450 (e.g., incorporated in the first vehicle 450')) via a second sidelink carrier 480. For example, the second UE 451 can send a broadcast transmission to multiple devices via the second sidelink carrier 480. The first UE 450 (among other UEs) can receive such a broadcast transmission. Additionally or alternatively, the second UE 451 can send a multicast transmission to multiple devices (e.g., the first UE 450 and the third UE 452) via the second sidelink carrier 480. The first UE 450 (among other UEs) can receive such a multicast transmission. Further, additionally or alternatively, the second UE 451 can send a unicast transmission to a device such as the first UE 450 via the second sidelink carrier 480. The first UE 450 (among other UEs) can receive such a unicast transmission. The third UE 452 can communicate in a similar manner.

[0060] In various aspects, for example, such sidelink communication on a sidelink carrier between a first UE 450 and a second UE 451 can occur without the need for an MNO to allocate resources for such communication (e.g., one or more portions of a resource block (RB), time slot, frequency band, and / or channel associated with sidelink carriers 470, 480) and / or without the need for scheduling such communication. In various aspects, sidelink communication can include traffic communication (e.g., data communication, control communication, paging communication, and / or system information communication). Additionally, in various aspects, sidelink communication can include sidelink feedback communication associated with traffic communication (e.g., transmission of feedback information for a previously received traffic communication). In various aspects, sidelink communication can employ at least one sidelink communication structure having at least one feedback symbol. The feedback symbol of the sidelink communication structure can be allocated for any sidelink feedback information that can be transmitted in a device-to-device (D2D) communication system 400 between devices (e.g., a first vehicle 450' and a second vehicle 451').

[0061] In various aspects, sidelink traffic communication and / or sidelink feedback communication can be associated with one or more transmission time intervals (TTIs). In various aspects, the TTI can be 0.5 ms, but larger or smaller values can be employed. In various aspects, the TTI can be associated with and / or correspond to a communication structure time slot. However, the TTI can be associated with a larger or smaller and / or different communication structure size and / or time unit (e.g., one or more time slots, subframes, or frames). In various aspects of the methods and apparatuses herein, sidelink communication (e.g., sidelink traffic communication and / or sidelink feedback communication) in a D2D communication system 400 can include at least one sidelink communication structure having a sidelink feedback symbol (e.g., to be allocated for transmitting feedback information). For example, during a first TTI, a device (e.g., a first vehicle 450') that uses a sidelink communication structure having a sidelink feedback symbol to transmit sidelink traffic communication in a D2D communication system 400 can avoid transmitting traffic information in one or more portions of the sidelink feedback symbol. In various aspects, the sidelink traffic communication can be transmitted by a first vehicle 450' to one or more of any remaining devices in a D2D communication system 400 (e.g., a second vehicle 451'). Additionally, during the first TTI, another device (e.g., a second vehicle 451') that is using a wireless communication structure having a sidelink feedback symbol to transmit sidelink feedback communication in a D2D communication system 400 can transmit feedback information in one or more portions of the sidelink feedback symbol. In this way, sidelink communication (e.g., including sidelink traffic communication and sidelink feedback communication) can occur efficiently without the need for an MNO to allocate resources for such communication and / or without the need for an MNO to schedule such communication.

[0062] Figure 5 FIG. is a diagram illustrating an example sidelink communication structure 500 in accordance with various aspects of the present disclosure. The sidelink communication structure 500 can be defined by resources in the frequency domain and the time domain. For example, the sidelink communication structure 500 can represent a time slot 502 and / or correspond to a TTI 504 (e.g., 0.5 ms). A resource grid can be used to represent the time slot 502 including one or more time-concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into a plurality of resource elements (REs). In various aspects, an RB 506 includes 12 consecutive subcarriers in the frequency domain (e.g., having a 30 kHz subcarrier spacing) 508 and 14 consecutive symbols 510 in the time domain, for a total of 168 REs. In various aspects, an RB includes 12 consecutive subcarriers in the frequency domain and 12 consecutive symbols in the time domain, for a total of 144 REs. In various aspects, a device (e.g., a first vehicle 450') can employ multiple resource blocks (e.g., N RBs) for sidelink communication (e.g., a sidelink transmission) 509 in a D2D communication system 400. The sidelink communication 509 can correspond to a single TTI.

[0063] In various aspects, one or more symbols 510 of the wireless communication structure 500 (e.g., one or more of the first three symbols 511) can be used to transmit a listen-before-talk (LBT) sequence in sidelink communication. Transmissions of a device for sidelink communication can be based on the LBT sequence. In various aspects, one or more symbols of the wireless communication structure 500 (e.g., the fourth symbol 512) can be used to transmit control information in sidelink communication. In various aspects, one or more symbols 510 of the wireless communication structure 500 (e.g., the fifth symbol 514 and the thirteenth symbol 516) can be used to transmit reference signals (e.g., demodulation reference signals (DM-RS) associated with ports 0-7) in sidelink communication, as shown. In various aspects, one or more symbols 510 of the wireless communication structure 500 (e.g., the sixth through twelfth symbols 518) can be used to transmit data in sidelink communication. In various aspects, one or more symbols 510 of the wireless communication structure 500 (e.g., the fourteenth symbol 520) can be configured as a guard period to accommodate uplink-downlink switching (e.g., turn-around) time.

[0064] In various aspects, for example, the sidelink communication structure 500 can be used for broadcasting sidelink communication. For example, the sidelink communication structure 500 can be used for broadcasting sidelink transmissions from a device (e.g., the first vehicle 450') in the D2D communication system 400 to a plurality of other devices (e.g., including the second vehicle 451') in the D2D communication system 400. The sidelink communication structure 500 described above is exemplary and can be defined in different ways in the time domain and / or the frequency domain. Additionally or alternatively, the sidelink communication structure 500 can be associated with the TTI in different ways (e.g., corresponding to one or more parts of the TTI).

[0065] Figure 6 FIG. is a diagram showing an example sidelink communication structure 600 according to various aspects of the present disclosure. In various aspects, the sidelink communication 602 can be associated with and / or correspond to a plurality of TTIs. For example, in various aspects, the sidelink communication 602 can employ TTI bundling, where the data portion of the sidelink communication can span multiple TTIs (e.g., the first TTI 604 and the second TTI 606). In various aspects, the sidelink communication 602 can employ a plurality of sidelink communication structures (e.g., the first sidelink communication structure 608 and the second sidelink communication structure 610). The first sidelink communication structure 608 and the second sidelink communication structure 610 can be similar to the sidelink communication structure 500. However, the first sidelink communication structure 608 and / or the second sidelink communication structure 610 can be adapted for TTI bundling. In various aspects, for each sidelink communication structure associated with sidelink communication employing TTI bundling, one or more portions of the overhead associated with the sidelink communication structure (e.g., the LBT portion, the control portion, and / or the guard period portion) may not be employed. For example, the last symbol 612 of the first sidelink communication structure 608 can be used for data instead of being used as a guard period for the uplink-downlink handover time. Similarly, the first four symbols of the second sidelink communication structure 610 can be used for reference signals and / or data instead of being used for the LBT sequence and / or control information. For example, the first symbol 614 of the second sidelink communication structure 610 can be used for a reference signal (e.g., a DM-RS signal), and the next three symbols 616 can be used for data.

[0066] However, in Figure 5 and 6 the sidelink communication structures 500 and 600 shown may not allocate for feedback communication. Thus, a device (e.g., the first vehicle 450') using (e.g., only) such structures 500, 600 in the D2D communication system 400 may not be able to transmit feedback information without adversely affecting the transmission and / or reception of other types of communication (e.g., traffic communication).

[0067] Device-to-Device Feedback

[0068] In various aspects of the methods and apparatuses herein, sidelink communication (e.g., sidelink traffic communication and / or sidelink feedback communication) in a D2D communication system 400 can include at least one wireless communication structure having sidelink feedback symbols (e.g., to be allocated for transmitting sidelink feedback information). In this way, sidelink communication (e.g., including sidelink traffic communication and sidelink feedback communication) can occur efficiently without the need for an MNO to allocate resources for such communication and / or without the need for an MNO to schedule such communication.

[0069] Figure 7FIG. is a diagram illustrating a sidelink communication structure 700 having at least one feedback symbol 702 in accordance with various aspects of the present disclosure. For example, sidelink communication 704 may be associated with and / or correspond to multiple TTIs. In aspects, sidelink communication 704 may employ TTI bundling, such as where the data portion of the sidelink communication may span multiple TTIs (e.g., first TTI 706, second TTI 708, and third TTI 710). In aspects, sidelink communication 704 may employ multiple sidelink communication structures (e.g., first sidelink communication structure 700, second sidelink communication structure 712, and third sidelink communication structure 714). In aspects, the first sidelink communication structure 700 may serve as the first communication structure, the second sidelink communication structure 712 may serve as an intermediate communication structure, and the third sidelink communication structure 714 may serve as the final communication structure for sidelink communication with TTI bundling. The first sidelink communication structure 700 may be similar to sidelink communication structure 500. However, compared to sidelink communication structure 500, sidelink communication structure 700 includes at least one feedback symbol 702 (e.g., sidelink feedback symbol). In aspects, at least one feedback symbol 702 may be the last symbol of wireless communication structure 700. However, in aspects, at least one feedback symbol 702 may be a different symbol of wireless communication structure 700. In aspects, at least one feedback symbol 702 may be multiple symbols in wireless communication structure 700. In aspects, the intermediate and final communication structures (such as the second sidelink communication structure 712 and the third sidelink communication structure 714) may be similar to sidelink communication structure 500, respectively. However, the second sidelink communication structure 712 and / or the third sidelink communication structure 714 may be adapted for TTI bundling. In aspects, for each sidelink communication structure associated with sidelink communication employing TTI bundling, one or more portions of the overhead associated with the sidelink communication structure may not be employed (e.g., LBT portion, control portion, and / or guard period portion). For example, the first symbol 716 of the second sidelink communication structure 712 may be used for a reference signal (e.g., DM-RS signal), and the next three symbols 718 may be used for data. Additionally, the last symbol 720 of the second sidelink communication structure 712 may be used for data. Similarly, the first symbol 722 of the third sidelink communication structure 714 may be used for a reference signal (e.g., DM-RS signal), and the next three symbols 724 may be used for data. The last symbol 726 of the third sidelink communication structure 714 may serve as a guard period to accommodate the uplink-downlink switching time.

[0070] By adopting a sidelink communication structure having at least one feedback symbol (such as the sidelink communication structure 700 for sidelink communication by a device), the TTI structure is modified to facilitate sidelink communication with feedback (e.g., having an allocation for feedback to be sent by another device during a TTI and / or having an allocation for a device receiving a transmission to use a feedback symbol in a subsequent TTI using the TTI structure to send feedback). Thus, in various aspects, the methods and devices herein facilitate feedback on received transmissions in a non-self - contained manner. That is, feedback on data is sent by the receiving device at m TTIs after the device has received the data, where m is an integer (e.g., 1, 2, 3, etc.).

[0071] Although the sidelink communication structure 700 having at least one feedback symbol 702 was described above in the context of TTI bundling, the methods and apparatus herein include any sidelink communication structure having at least one feedback symbol 702. For example, the methods and apparatus herein include wireless communication structures similar to one or more of the wireless communication structures 500, 608, 610, 712, 714, which are adapted to include at least one feedback symbol 702 in place of one or more portions of the existing symbols described above.

[0072] The sidelink communication structure with at least one feedback symbol of the method and apparatus of this disclosure can be used for device-to-device communication. In various aspects, a device (such as the first UE 450) transmitting sidelink communication (e.g., sidelink traffic communication) can employ rate matching and / or puncturing techniques to construct at least one feedback symbol 702. If the first UE 450 transmits sidelink communication within N TTIs, the symbol (e.g., the identified symbol, such as the last symbol) of each sidelink communication structure included in or corresponding to a subset of the sidelink communication structures within the N TTIs can be the at least one feedback symbol 702, where N is an integer (e.g., 1, 2, 3, etc.). For example, the identified symbol (e.g., the last symbol) associated with the first TTI subset A of a set of TTIs {1, …, N} for an N-TTI transmission serves as the feedback symbol. In various aspects, for example, the first subset A can include {1}, {1, N}, {1, …, N}. However, different subsets can be employed. In various aspects, the sidelink communication transmitted by the first UE 450 can include an indication 728 of a subset B of the above first subset A for one or more devices (e.g., the second UE 451) that receive the sidelink communication. The subset B can be used to determine the TTI and / or sidelink communication structure in which the feedback is to be transmitted that is associated with the subset B. In various aspects, for example, the indication 728 can be indicated by or included in the control part 730, or can be included in the data part 732 (e.g., included in a medium access control (MAC) control element (CE) in the sidelink communication transmitted by the first UE 450). In this way, one or more devices (e.g., the second UE 451) can determine when to transmit feedback information (e.g., associated with the received sidelink communication or another communication) in subsequent TTIs based on the received sidelink communication. In various aspects, the first subset can be based on RRC configuration or pre-configuration (e.g., an RRC configuration provided for the second UE 451).

[0073] In various aspects, a device such as UE 450 or 451 can convey sidelink traffic communication by transmitting sidelink traffic communication to one or more UEs. Such a device can convey sidelink feedback communication in one or more portions of at least one feedback symbol by receiving sidelink feedback communication. Additionally or alternatively, in various aspects, a device such as UE 450 or 451 can convey sidelink traffic communication by receiving sidelink traffic communication from one or more UEs. Such a device can convey sidelink feedback communication in one or more portions of at least one feedback symbol by transmitting sidelink feedback communication.

[0074] In various aspects, for the TTI nFor traffic (e.g., data) of sidelink traffic communication received from, e.g., a second UE 451, a first UE 450 may send feedback information in a feedback symbol 702 associated with a subsequent TTI, where the TTI n+m appears at m TTIs after the TTI n where n and m are integers. In various aspects, m = 1. That is, the first UE 450 may send feedback information in the TTI that is consecutive and after (e.g., immediately after) the TTI n In various aspects, the value of m may be based on subset B. For example, in various aspects, the first UE 450 may determine or assume that a similar pattern may be used for sidelink communication in subsequent TTIs. Thus, the first UE 450 may determine subsequent TTIs in which to send sidelink feedback communication based on subset B.

[0075] In various aspects, the frequency resources used to send sidelink feedback information in the feedback symbol 702 may be based on the frequency resources used for sidelink traffic (e.g., data) communication. In various aspects, for traffic of sidelink traffic communication received by the first UE 450 using a set of frequency resources (e.g., 120 subcarriers) from, e.g., a second UE 451, the first UE 450 may use the set of frequency resources (e.g., all frequency resources used for data transmission) to send sidelink feedback information in the feedback symbol 702. In various aspects, for traffic of sidelink traffic communication received by the first UE 450 using a set of frequency resources (e.g., 120 subcarriers) from, e.g., a second UE 451, the first UE 450 may use a subset of the set of frequency resources to send sidelink feedback information in the feedback symbol 702. For example, in various aspects, the first UE 450 may adopt a subset of a set of frequency resources used for sidelink traffic transmission by adopting at least a first subchannel among multiple subchannels used for traffic transmission for sidelink feedback transmission. In various aspects, a subchannel and / or multiple subchannels may be a frequency range based on, e.g., the number of resource blocks used for sidelink traffic communication. In various aspects, the first UE 450 may adopt a subset of a set of frequency resources used for sidelink traffic transmission by adopting at least a first subchannel used for traffic (e.g., data) transmission. In various aspects, the first UE 450 may adopt a subchannel for sidelink feedback transmission based on at least one of a measurement of signal strength, power, or quality associated with transmitting sidelink traffic communication on the frequency resources of sidelink traffic communication, so as to adopt a subset of a set of frequency resources used for sidelink traffic transmission. For example, the subset may be based on or include at least the subchannel with the lowest energy, and the subchannel with the lowest energy is based on past sensing of sidelink traffic communication resources.

[0076] In various aspects, the first UE 450 may employ a first subcarrier spacing (e.g., 15 kHz) for data service communication. To facilitate automatic gain control (AGC), the first UE 450 may use a subcarrier spacing associated with sidelink feedback communication to transmit feedback information in feedback symbol 702, which is double the subcarrier spacing associated with sidelink service communication (e.g., twice the subcarrier spacing used for data transmission). For example, the subcarrier spacing associated with sidelink feedback communication may be an integer multiple of the subcarrier spacing associated with data service communication. Such sidelink feedback communication may include a repeated transmission of sidelink feedback information in one or more portions of at least two feedback symbols (e.g., the same feedback symbol repeated two or more times) of a sidelink communication structure having at least one feedback symbol. In this way, the second UE 451 may reduce and / or avoid adverse effects (e.g., saturation and / or clipping) associated with inappropriate AGC while receiving sidelink feedback communication. For example, the second UE 451 may perform AGC based on the first feedback symbol of such two feedback symbols so that the second feedback symbol of such two feedback symbols can be successfully processed to determine the feedback information.

[0077] In various aspects, for sidelink service communication received by the first UE 450 (e.g., from the second UE 451), the first UE 450 may scramble the feedback information bits before transmitting the feedback information in feedback symbol 702. In various aspects, the first UE 450 may employ an identifier (ID) associated with the first UE 450 to scramble the feedback information bits. In various aspects, the ID may be assigned or configured. In this way, if the sidelink service communication transmitted by the second UE 451 is a multicast or broadcast transmission, the second UE 451 may determine (e.g., based on the ID) the source of the sidelink feedback communication received for a previously transmitted sidelink service communication.

[0078] In various aspects, for sidelink service communication received by the first UE 450 (e.g., from the second UE 451), the first UE 450 may use a predetermined value or based on measurements performed by the first UE 450 on one or more reference signals to determine the power for sidelink feedback communication (e.g., sidelink feedback transmission) with the second UE 451. For example, the first UE 450 may determine the transmit power for sidelink feedback information based on the received data power (e.g., a function of the RSRP measurement performed on the DMRS) or based on fixing the transmit power for the feedback information to a value (e.g., a maximum value). The first UE 450 may use the power so determined for sidelink feedback communication.

[0079] In various aspects, for sidelink traffic communications received (e.g., from a second UE 451), a first UE 450 may send feedback information communications to the second UE 451, the feedback information communications including at least one of the following: acknowledgement / negative acknowledgement (ACK / NACK) information, channel quality indicator (CQI) information, rank indicator (RI) information, precoding matrix indicator (PMI) information, buffer status information (e.g., buffer status report), or timing information for a subsequent transmission by the source of the feedback information (e.g., the first UE 450). In various aspects, such sidelink feedback information (e.g., timing information for a subsequent sidelink transmission) may facilitate sidelink communication coordination among devices (e.g., the first UE 450, the second UE 451, and the third UE 452) in a D2D communication system 400, because in various aspects, D2D communications (e.g., sidelink communications) between and among vehicles 450’, 451’, 452’ are not scheduled by an MNO.

[0080] Figure 8 is a flowchart of a method for wireless communication in accordance with various aspects of the present disclosure. The steps of method 800 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of a wireless communication device such as UEs 104, 104’, 350, 450, and 451. As shown, while method 800 for wireless communication includes a plurality of enumerated steps, embodiments of method 800 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0081] At step 810, method 800 includes: transmitting sidelink traffic communications using a sidelink communication structure. At step 820, method 800 includes: transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In some aspects, at step 830, method 800 includes: transmitting, by a first wireless communication device, sidelink feedback communications using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communications are associated with the sidelink traffic communications. In various aspects, the sidelink feedback may be included in one or more portions of the at least one feedback symbol. For example, in this manner, the methods and apparatuses herein may facilitate feedback transmission for NR sidelink communication. In various aspects, the feedback is sent by a device in a non-self-contained manner (e.g., not within the same TTI in which such a device receives data). In various aspects, the methods and apparatuses herein may be employed in an NR V2X context or system.

[0082] In various aspects, sidelink traffic communication uses at least one of the sidelink communication structures. In various aspects, transmitting sidelink traffic communication includes transmitting sidelink traffic communication in a first set of one or more transmission time intervals (TTIs), and a subset of the first set of one or more TTIs respectively corresponds to one or more sidelink communication structures each having at least one feedback symbol. In such an aspect, the subset of the first set of TTIs is based on radio resource control configuration or pre-configuration. In such an aspect, the sidelink traffic communication indicates a subset of the subset. Further, in such an aspect, transmitting sidelink feedback communication by a first wireless communication device includes: the first wireless communication device transmitting sidelink feedback communication based on the subset of the subset, using one or more portions of the feedback symbols of the sidelink communication structure in a TTI after the first set of TTIs. In such a further aspect, the sidelink traffic communication uses a control portion or a media access control control element associated with a data portion of the sidelink traffic communication to indicate the subset.

[0083] In various aspects, transmitting sidelink traffic communication includes: transmitting sidelink traffic communication in a first set of one or more TTIs, the sidelink traffic communication indicating at least one TTI in which sidelink feedback communication can be transmitted, and transmitting sidelink feedback communication by a first wireless communication device includes: the first wireless communication device transmitting sidelink feedback communication in the indicated at least one TTI. In various aspects, transmitting sidelink feedback communication by a first wireless communication device includes: the first wireless communication device transmitting sidelink feedback communication successively in TTIs after the first set of one or more TTIs.

[0084] In various aspects, the frequency resources for transmitting sidelink feedback communication are based on the frequency resources for transmitting sidelink traffic communication. In such an aspect, the frequency resources for transmitting sidelink feedback communication correspond to all the frequency resources for transmitting sidelink traffic communication. In such an aspect, the frequency resources for transmitting sidelink feedback communication are a subset of the frequency resources for transmitting sidelink traffic communication. In such a further aspect, the subset of frequency resources includes a first portion of the frequency resources for transmitting sidelink traffic communication. In such a further aspect, the subset of frequency resources is based on the first wireless communication device measuring at least one of the following: signal strength, power, or quality associated with transmitting sidelink traffic communication on the frequency resources.

[0085] In various aspects, a subcarrier spacing associated with sidelink feedback communication is an integer multiple of a subcarrier spacing associated with sidelink data communication, and transmitting the sidelink feedback communication includes: repetitively transmitting sidelink feedback information in one or more portions of at least two feedback symbols of a sidelink communication structure having at least one feedback symbol. In various aspects, transmitting the sidelink feedback communication by a first wireless communication device includes: the first wireless communication device sending the sidelink feedback communication, and the first wireless communication device scrambling the sidelink feedback information of the communication based on an identifier associated with the first wireless communication device. In various aspects, transmitting the sidelink feedback communication by a first wireless communication device includes: the first wireless communication device sending the sidelink feedback communication using a power that is a predetermined value or based on measurements performed by the first wireless communication device on one or more reference signals. In various aspects, the sidelink feedback communication includes at least one of the following: acknowledgement / negative acknowledgement information, channel quality indicator information, rank indicator information, precoding matrix indicator information, buffer status information, or timing information for a subsequent transmission by a source of the feedback information. In various aspects, the traffic communication and the feedback communication are device-to-device (D2D) communication. In such aspects, the traffic communication and the feedback communication are vehicle-to-everything (V2X) communication.

[0086] In various aspects, the sidelink traffic communication includes unicast communication, multicast communication, or broadcast communication. In various aspects, the sidelink traffic communication is associated with a first transmission time interval (TTI), and the sidelink feedback communication is associated with a second TTI different from the first TTI. In various aspects, the first wireless communication device is a user equipment, and transmitting the sidelink feedback communication includes sending the sidelink feedback communication. In various aspects, the first wireless communication device is a user equipment, and transmitting the sidelink feedback communication includes receiving the sidelink feedback communication. In various aspects, the sidelink communication can be an NR sidelink communication.

[0087] In various aspects, using a sidelink communication structure to transmit sidelink traffic communication and using at least one feedback symbol of the sidelink communication structure to transmit an allocation for sidelink feedback includes: UE 104, 104’, 350, 450, and 451 receiving sidelink traffic communication using the sidelink communication structure, and transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In such aspects, receiving sidelink feedback communication using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communication is associated with the sidelink traffic communication, includes: UE 104, 104’, 350, 450, and 451 sending sidelink feedback communication using at least one feedback symbol of the sidelink communication structure, wherein the sidelink feedback communication is associated with the sidelink traffic communication.

[0088] In various aspects, using a sidelink communication structure to convey sidelink traffic communication and using at least one feedback symbol of the sidelink communication structure to convey an allocation for sidelink feedback includes: transmitting sidelink traffic communication by UEs 104, 104', 350, 450, and 451 using the sidelink communication structure, and transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. In such aspects, using at least one feedback symbol of the sidelink communication structure to convey sidelink feedback communication, where the sidelink feedback communication is associated with the sidelink traffic communication, includes: receiving sidelink feedback communication by UEs 104, 104', 350, 450, and 451 using at least one feedback symbol of the sidelink communication structure, where the sidelink feedback communication is associated with the sidelink traffic communication.

[0089] Figure 9 FIG. 900 is an example illustration of a hardware implementation for a device 902 for wireless communication employing a processing system 904 in accordance with various aspects of the present disclosure. In various aspects, the apparatus 902 for wireless communication can be, for example, UEs 104, 104', 350, 450, 451, 452. The processing system 904 can be implemented utilizing a bus architecture, generally represented by bus 906. The bus 906 can include any number of interconnected buses and bridges depending on the specific application of the processing system 904 and overall design constraints. In various aspects, the apparatus 902 can include a sidelink traffic communication component 910 that conveys (e.g., transmits and / or receives) sidelink traffic communication using a sidelink communication structure. In one aspect, the sidelink traffic communication component 910 can be configured to convey sidelink traffic communication in a first set of one or more transmission time intervals (TTIs) or a subset of the first set of TTIs respectively corresponding to one or more sidelink communication structures, each of the one or more sidelink communication structures having at least one feedback symbol. In one aspect, the sidelink traffic communication component 910 uses a control portion or a media access control control element associated with a data portion of the sidelink traffic communication to indicate the subset. In one aspect, the sidelink traffic communication component 910 can be configured to employ the first set of TTIs based on radio resource control configuration or pre-configuration. In one aspect, the sidelink traffic communication component 910 can be configured to indicate a subset of a subset of the first set of TTIs in the sidelink traffic communication. In one aspect, the sidelink traffic communication component 910 can be configured to convey sidelink traffic communication in the first set of one or more TTIs, and the sidelink traffic communication indicates at least one TTI in which sidelink feedback communication can be conveyed.

[0090] In various aspects, apparatus 902 may include an allocation component 912 for sidelink feedback communication that uses at least one feedback symbol of a sidelink communication structure to convey (e.g., transmit and / or receive) an allocation for sidelink feedback. In one aspect, the allocation component 912 for sidelink feedback communication may be configured to convey in sidelink traffic communication at least one feedback symbol allocated for conveying feedback information (e.g., by employing processing techniques associated with rate matching and / or puncturing).

[0091] In various aspects, apparatus 902 may include a sidelink feedback communication component 914 that uses at least one feedback symbol of a sidelink communication structure to convey (e.g., transmit and / or receive) sidelink feedback communication, where the sidelink feedback communication is associated with sidelink traffic communication. In various aspects, the sidelink feedback communication component 914 may be configured to convey sidelink feedback communication in one or more portions of feedback symbols of the sidelink communication structure in at least one TTI indicated in the sidelink traffic communication. In various aspects, the sidelink feedback communication component 914 may be configured to convey sidelink feedback communication using one or more portions of feedback symbols of the sidelink communication structure in a TTI after a first set of TTIs indicated in the sidelink traffic communication, based on a subset of the subset of the first set of TTIs. In various aspects, the sidelink feedback communication component 914 may be configured to convey sidelink feedback communication in one or more portions of feedback symbols of the sidelink communication structure in a TTI in at least one of the cases of after or immediately after a first set of TTIs of the sidelink traffic communication. In various aspects, the sidelink feedback communication component 914 may be configured to employ a subcarrier spacing associated with the sidelink feedback communication that is an integer multiple of a subcarrier spacing associated with sidelink data communication, and the sidelink feedback communication component 914 being configured to convey sidelink feedback communication includes repeatedly conveying sidelink feedback information in one or more portions of at least two feedback symbols of the sidelink communication structure having at least one feedback symbol.

[0092] In various aspects, the sidelink feedback communication component 914 may be configured to transmit sidelink feedback communication via a first wireless communication device and be configured to scramble the sidelink feedback information of the communication based on an identifier associated with the first wireless communication device. In various aspects, the sidelink feedback communication component 914 may be configured to transmit sidelink feedback communication via the first wireless communication device using a power that is a predetermined value or based on measurements performed by the first wireless communication device on one or more reference signals.

[0093] Bus 906 links together various circuits including one or more processors and / or hardware components (represented by processor 908, components 910, 912, 914, and computer-readable medium / memory 916). Bus 906 can also link various other circuits such as a timing source, peripherals, a voltage regulator, and a power management circuit, which are well known in the art and thus will not be described further.

[0094] Processing system 904 can be coupled to transceiver 918. Transceiver 918 is coupled to one or more antennas 920. Transceiver 918 provides a unit for communicating with various other devices over a transmission medium. Transceiver 918 receives signals from one or more antennas 920, extracts information from the received signals, and provides the extracted information to processing system 904 (e.g., sidelink traffic communication component 910, allocation component 912 for sidelink feedback communication, and / or sidelink feedback communication component 914). Additionally, transceiver 918 receives information from processing system 904 (e.g., sidelink traffic communication component 910, allocation component 912 for sidelink feedback communication, and / or sidelink feedback communication component 914) and generates signals to be applied to one or more antennas 920 based on the received information. Processing system 904 includes processor 908 coupled to computer-readable medium / memory 916. Processor 904 is responsible for general processing, including the execution of software stored on computer-readable medium / memory 916. The software, when executed by processor 908, causes processing system 904 to perform the various functions described above for any particular device. Computer-readable medium / memory 908 can also be used to store data manipulated by processor 908 when executing the software. Components 910, 912, 914 can be software components running in processor 908, one or more hardware components coupled to processor 908, or some combination thereof, located / stored in computer-readable medium / memory 916. Processing system 904 can be a component of UE 350 and can include at least one of TX processor 368, RX processor 356, and controller / processor 359 and / or memory 360.

[0095] In one configuration, a device 902 for wireless communication includes: a unit for transmitting sidelink traffic communication using a sidelink communication structure. Device 902 can also include: a unit for transmitting an allocation for sidelink feedback using at least one feedback symbol of the sidelink communication structure. Device 902 can also include: a unit for transmitting sidelink feedback communication using at least one feedback symbol of the sidelink communication structure, where the sidelink feedback communication is associated with the sidelink traffic communication.

[0096] The above unit may be one or more of the above components of apparatus 902 and / or a processing system 904 of apparatus 902 configured to perform the functions recited by the above unit. As described above, the processing system 904 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Thus, in one configuration, the above unit may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the above unit.

[0097] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is illustrative of an exemplary method. It should be understood that based on design preferences, the specific order or hierarchy of the blocks in the process / flowchart may be rearranged. Additionally, some blocks may be combined or omitted. The appended method claims show the elements of the various blocks in an example order and are not intended to be limited to the specific order or hierarchy given.

[0098] A previous description is provided to enable any person skilled in the art to implement the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the literal claims, where a reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more". The word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. Unless otherwise explicitly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "any combination of A, B, C, or thereof" include any combination of A, B, and / or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "any combination of A, B, C, or thereof" can be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combination can include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are known or later become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Further, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is explicitly recited in the claims. The words "module", "mechanism", "element", "device", etc. are not necessarily intended as substitutes for the word "unit". Thus, no claim element is to be construed as a unit plus function unless the element is expressly recited using the phrase "means for...".

Claims

1. A method for wireless communication, comprising: Receiving sidelink traffic communication in a set of one or more transmission time intervals (TTIs), wherein a subset of the set of one or more TTIs corresponds to a sidelink communication structure having at least one feedback symbol; and Using the at least one feedback symbol to transmit sidelink feedback communication.

2. The method according to claim 1, further comprising: Receiving an indication that the sidelink communication structure has the at least one feedback symbol.

3. The method according to claim 1, wherein, The subset of the set of one or more TTIs is based on radio resource control configuration or pre-configuration.

4. The method according to claim 1, wherein, The sidelink traffic communication indicates a subset of the subset.

5. The method according to claim 4, wherein, The at least one feedback symbol is in a TTI after the subset of the subset in the set of one or more TTIs.

6. The method according to claim 4, wherein, The sidelink traffic communication uses a control part or a media access control control element associated with a data part of the sidelink traffic communication to indicate the subset of the subset.

7. The method according to claim 1, wherein The frequency resource for transmitting the sidelink feedback communication is based on the frequency resource for receiving the sidelink traffic communication.

8. The method according to claim 7, wherein The frequency resource for transmitting the sidelink feedback communication corresponds to all frequency resources for receiving the sidelink traffic communication.

9. The method according to claim 7, wherein, The frequency resource for transmitting the sidelink feedback communication is a subset of the frequency resource for receiving the sidelink traffic communication.

10. The method according to claim 1, wherein: The subcarrier spacing associated with the sidelink feedback communication is an integer multiple of the subcarrier spacing associated with the sidelink traffic communication; And Transmitting the sidelink feedback communication includes: Repeatedly transmitting sidelink feedback information in one or more parts of at least two feedback symbols of the sidelink communication structure having at least one feedback symbol.

11. The method according to claim 1, wherein, The sidelink feedback communication is transmitted by a first wireless communication device, and the method further comprises: Scrambling the information of the sidelink feedback communication by the first wireless communication device based on an identifier associated with the first wireless communication device.

12. The method according to claim 1, wherein, The sidelink feedback communication includes at least one of the following: acknowledgement / negative acknowledgement information, channel quality indicator information, rank indicator information, precoding matrix indicator information, buffer status information, or timing information of a subsequent transmission by a source of the feedback information.

13. A method for wireless communication, comprising: Transmitting sidelink traffic communication in a set of one or more transmission time intervals (TTIs), wherein a subset of the set of one or more TTIs corresponds to a sidelink communication structure having at least one feedback symbol; and Receiving sidelink feedback communication in the at least one feedback symbol.

14. The method according to claim 13, further comprising: Transmitting an indication that the sidelink communication structure has the at least one feedback symbol.

15. The method according to claim 13, wherein The subset of the set of one or more TTIs is based on radio resource control configuration or pre-configuration.

16. The method according to claim 13, wherein, The sidelink traffic communication indicates a subset of the subset.

17. The method according to claim 16, wherein, The at least one feedback symbol is in a TTI after the subset of the subset in the set of one or more TTIs.

18. The method according to claim 16, wherein, The sidelink service communication indicates the subset using a control part or a media access control control element associated with a data part of the sidelink service communication.

19. The method according to claim 13, wherein, The frequency resource for receiving the sidelink feedback communication is based on the frequency resource for transmitting the sidelink service communication.

20. The method according to claim 19, wherein, The frequency resource for receiving the sidelink feedback communication corresponds to all the frequency resources for transmitting the sidelink service communication.

21. The method according to claim 19, wherein, The frequency resource for receiving the sidelink feedback communication is a subset of the frequency resources for transmitting the sidelink service communication.

22. The method according to claim 13, wherein, The sidelink feedback communication includes at least one of the following: acknowledgement / negative acknowledgement information, channel quality indicator information, rank indicator information, precoding matrix indicator information, buffer status information, or timing information for a subsequent transmission by a source of the feedback information.

23. A wireless communication device for wireless communication, comprising: a memory; and at least one processor coupled to the memory, the at least one processor being configured to: receive sidelink service communication in a set of one or more transmission time intervals (TTIs), wherein a subset of the set of one or more TTIs corresponds to a sidelink communication structure having at least one feedback symbol; and use the at least one feedback symbol to transmit sidelink feedback communication.

24. The wireless communication device according to claim 23, wherein, The at least one processor is further configured to: receive an indication that the sidelink communication structure has the at least one feedback symbol.

25. A wireless communication device for wireless communication, comprising: a memory; and at least one processor coupled to the memory, the at least one processor being configured to: transmit sidelink service communication in a set of one or more transmission time intervals (TTIs), wherein a subset of the set of one or more TTIs corresponds to a sidelink communication structure having at least one feedback symbol; and receive sidelink feedback communication in the at least one feedback symbol.

26. The wireless communication device according to claim 25, wherein, The at least one processor is further configured to: transmit an indication that the sidelink communication structure has the at least one feedback symbol.

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