Configuration grant enhancements for sidelink communications in unlicensed spectrum

Abstract

Apparatuses, methods, and computer-readable media for on-demand sensing based on sidelink resource re-evaluation are disclosed herein. An example method of wireless communication performed by a user equipment includes receiving a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication over at least one sidelink channel within a configuration time period, where the plurality of resources includes a plurality of allocated slots and one or more candidate transmission slots, the one or more candidate transmission slots are associated with respective slots of the plurality of allocated slots for additional opportunities of a listen before talk (LBT) procedure on the at least one sidelink channel. The method also includes sending, to the base station, an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

Description

Background Art Technical Field

[0001] The present disclosure relates generally to communication systems and, more particularly, to configuration grant enhancements for sidelink communications in unlicensed spectrum.

[0002] introduction

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies 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.

[0004] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5GNR is part of the continued mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable low latency communications (URLLC). Various aspects of wireless communications may include direct communications between devices such as in V2X and / or other D2D communications. There is a need to further improve V2X and / or other D2D technologies. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0005] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to describe the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0006] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus is configured to receive a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configuration time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel in the plurality of allocated time slots. The apparatus is also configured to send an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel to the base station.

[0007] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus is configured to send a resource grant to a user equipment (UE), the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configuration time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of the plurality of allocated time slots for additional opportunities for an LBT procedure on the at least one sidelink channel. The apparatus is also configured to receive from the UE an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0008] To achieve the foregoing and related purposes, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some exemplary features of one or more aspects. However, these features are merely indicative of some of the various ways in which the principles of the various aspects may be employed, and this specification is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a diagram illustrating an example of a wireless communication system and access network in accordance with various aspects presented herein.

[0010] Figure 2A is a diagram illustrating an example of a first frame according to various aspects of the present disclosure.

[0011] Figure 2B is a diagram illustrating an example of DL channels within a subframe according to various aspects of the present disclosure.

[0012] Figure 2C is a diagram illustrating an example of a second frame according to various aspects of the present disclosure.

[0013] Figure 2D is a diagram illustrating an example of UL channels within a subframe according to various aspects of the present disclosure.

[0014] Figure 3 Example aspects of a sidelink timeslot structure are illustrated.

[0015] Figure 4 is a block diagram of a base station communicating with a UE in an access network.

[0016] Figure 5 An example of allocation of time slots and sub-channels in a resource pool is illustrated.

[0017] Figure 6 An example of a resource pool including resource reservation for sidelink data transmission is illustrated.

[0018] Figure 7 is a diagram illustrating examples of side link communications and access link communications according to various aspects of the present disclosure.

[0019] Figure 8 is a diagram illustrating an example of side link communications according to various aspects of the present disclosure.

[0020] Fig. 9 is a diagram illustrating an example of an acknowledgement message for a side link channel according to various aspects of the present disclosure.

[0021] Fig.10 is a diagram illustrating an example associated with listen-before-talk (LBT) reporting for a sidelink channel according to various aspects of the present disclosure.

[0022] Fig.11 An example of sidelink communication based on Mode 1 resource allocation according to various aspects of the present disclosure is illustrated.

[0023] Fig.12 Examples of sidelink communications based on Mode 1 resource allocation with configuration grant enhancements in accordance with various aspects of the present disclosure are illustrated.

[0024] Fig.13 Another example of sidelink communication based on Mode 1 resource allocation with configuration grant enhancement according to various aspects of the present disclosure is illustrated.

[0025] Fig.14 is a flow chart of a process for wireless communication according to various aspects of the present disclosure.

[0026] Fig.15 is a flow chart of a process for wireless communication according to various aspects of the present disclosure.

[0027] Fig.16 is a diagram illustrating an example of a hardware implementation for an apparatus according to various aspects of the present disclosure.

[0028] Fig.17is a diagram illustrating an example of a hardware implementation for an apparatus according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0029] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configuration with which the concepts described herein can be practiced. In order to provide a thorough understanding of the various concepts, the specific embodiments include specific details. However, it is apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid blurring these concepts.

[0030] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0031] As an example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. The example of a processor includes a microprocessor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor, a digital signal processor (DSP), a reduced instruction set computing (RISC) processor, a system on a chip (SoC), a baseband processor, a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, a gate logic piece, a discrete hardware circuit and other suitable hardware configured to perform various functionalities described throughout the present disclosure. One or more processors in a processing system can execute software. Whether it is referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be widely interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0032] The transmitter user equipment (e.g., Tx UE) may send feedback (if configured) in an uplink control channel configured after the sidelink feedback channel is associated with the last sidelink data resource allocated for each configured grant period. The feedback report may include information of the initial transmission and one or more retransmissions of the same transport block. In some aspects, the Tx UE may report a positive confirmation in the uplink control channel only if all receiver UEs (e.g., Rx UEs) correctly receive at least one of the retransmissions and the Rx UEs positively confirm the receipt of the retransmissions to the Tx UE. When the feedback report includes information of the transmission and retransmission of different transport blocks, the Tx UE may report a positive confirmation only if all Rx UEs correctly receive different transport blocks and the Rx UEs positively confirm the receipt of different transport blocks to the Tx UE. In sidelink mode 1 operation of unlicensed spectrum, a negative confirmation in the uplink control channel may not reflect whether the negative confirmation is due to a listen-before-talk (LBT) failure or a decoding failure. Some legacy techniques provide for reporting LBT failures directly to the base station by reusing uplink control channel resources allocated for feedback reporting in sidelink Mode 1 operation.

[0033] However, for unlicensed spectrum operation, sidelink transmissions are subject to the LBT state and therefore, multiple transmission opportunities for configuration grants may be required. In NR unlicensed spectrum (NR-U) operation, the mechanism for both configuration grant type 1 and configuration grant type 2 can be extended so that the number of allocated time slots after the time instance corresponding to the indicated configuration grant offset can be configured to provide additional LBT opportunities. Although the legacy sidelink operation provides up to three sidelink data resources within one configuration grant period, at least two sidelink data resources may need to be spaced apart to allow the sidelink feedback channel to be located in the middle for feedback. Therefore, for sidelink unlicensed spectrum (SL-U) operation, there is a need to introduce additional LBT opportunities.

[0034] Accordingly, in one or more examples, the described functions can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage devices, magnetic disk storage devices, other magnetic storage devices, combinations of computer-readable media of the above types, or any other media that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0035] Figure 1 1 is a diagram illustrating an example of a wireless communication system and an access network 100 that includes devices configured to perform the resource reassessment aspects described herein. Some wireless communications may be exchanged directly between wireless devices based on sidelinks. Communications may be based on vehicle-to-everything (V2X) or other device-to-device (D2D) communications, such as proximity services (ProSe), etc. For example, sidelink communications may be exchanged based on a PC5 interface.

[0036] As described above, for unlicensed spectrum operation, sidelink transmissions are subject to LBT states and, therefore, multiple transmission opportunities for configuration grants may be required. In some examples, UE 104 can be configured to manage one or more aspects of wireless communications by facilitating configuration grant enhancements for sidelink communications in unlicensed spectrum. As an example, in Figure 1 In the present invention, a UE 104, an RSU 107 and / or other device communicating based on a sidelink may include a sensing and feedback component 198, which is configured to receive a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, the plurality of resources including a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on at least one sidelink channel. The sensing and feedback component 198 is also configured to send an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel to the base station. In combination with Figures 12 to 15 Further related aspects and features are described in more detail.

[0037] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0038] Some examples of sidelink communications may include vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and / or combinations thereof, and / or vehicle-based communication devices communicating with other devices, which may be collectively referred to as vehicle-to-everything (V2X) communications. Again, referring to Figure 1, in some aspects, a UE 104 (e.g., a transmitting vehicle user equipment (VUE) or other UE) can be configured to send a message directly to another UE 104. The communication can be based on V2X or other D2D communications, such as proximity services (ProSe), etc. Communications based on V2X and / or D2D can also be sent and received by other transmitting devices and receiving devices (such as roadside units (RSU) 107, etc.). Various aspects of the communication can be based on PC5 or sidelink communications, for example, as described in conjunction with the example in Figure 2. Although the following description may provide examples of V2X / D2D communications related to 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0039] Figure 1 The wireless communication system and access network 100 (also referred to as a wireless wide area network (WWAN)) in FIG. 1 includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and a core network (e.g., 5GC) 190. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0040] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 via a backhaul link 184. Base stations 102 may perform one or more of the following functions, among other functions: transmission of user data, radio channel encryption and decryption, 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), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. Base stations 102 may communicate with each other directly or indirectly (eg, through EPC 160 or core network 190) over backhaul links 134 (eg, X2 interfaces). Backhaul links 134 may be wired or wireless.

[0041] Base station 102 can communicate wirelessly with UE 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also called a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also called a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. For each carrier allocated in the carrier aggregation for up to Yx MHz (x component carriers) in total for transmission in each direction, the base station 102 / UE 104 can use spectrum with a bandwidth of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, etc.). The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric for DL ​​and UL (e.g., more or fewer carriers may be allocated for DL ​​than for 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 a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0042] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through various wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0043] The 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) to determine whether the channel is available before communicating.

[0044] The small cell 102' can operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' can adopt NR and use the same 5GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' adopting NR in the unlicensed spectrum can improve the coverage of the access network and / or increase the capacity of the access network. The base station 102 (whether a small cell 102' or a large cell (e.g., a macro base station)) may include an eNB, a gNodeB (gNB), or other types of base stations. Some base stations, such as gNB 180, can operate in traditional sub-6GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When the gNB 180 operates at mmW or near mmW frequencies, the gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 50GHz to 500GHz and a wavelength between 1 mm and 10 mm. Radio waves in this frequency band may be referred to as millimeter waves. Near mmW may extend down to frequencies of 5 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 5 GHz and 50 GHz and is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands have extremely high path loss and short range. The mmW base station 180 may use beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0045] Devices can use beamforming to send and receive communications. For example, Figure 1It is illustrated that the base station 180 can transmit beamformed signals to the UE 104 in one or more transmission directions 182'. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182″. UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may or may not be the same. The transmit direction and receive direction of UE 104 may or may not be the same. Although the beamformed signals are shown as being between UE 104 and base station 102 / 180, UE 104 or RSU 107 may also similarly apply aspects of beamforming to communicate with another UE 104 or RSU 107 (such as based on V2X, V2V, or D2D communication).

[0046] 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 handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are passed through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service configuration and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS delivery, may be used to authorize and initiate MBMS bearer services in a public land mobile network (PLMN), and may be used to schedule MBMS delivery. 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 of ​​a broadcast specific service, and may be responsible for session management (start / stop) and for collecting eMBMS related billing information.

[0047] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Generally speaking, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0048] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other suitable term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0049] Return to reference Figure 1 , BS 102 / 180 may be configured to manage one or more aspects of wireless communications by facilitating configuration grant enhancements for sidelink communications in unlicensed spectrum. As an example, in Figure 1In the embodiment of the present invention, BS 102, base station 180, and / or other devices communicating with the sidelink device may include a configuration and feedback processing component 199 configured to send a resource grant to a user equipment (UE), the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configuration time period, the plurality of resources including a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with respective time slots of the plurality of allocated time slots for additional opportunities for the LBT procedure on the at least one sidelink channel. The configuration and feedback processing component 199 is also configured to receive from the UE an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0050] In addition, although the present disclosure may focus on vehicle-to-pedestrian (V2P) communications and pedestrian-to-vehicle (P2V) communications, the concepts and aspects described herein may be applicable to other similar areas, such as D2D communications, IoT communications, vehicle-to-everything (V2X) communications, or other standards / protocols for communications in wireless / access networks.

[0051] Figure 2A FIG200 is a diagram illustrating an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G NR subframe. Figure 2C FIG250 is a diagram illustrating an example of a second subframe within a 5G NR frame structure. Figure 2D FIG280 is a diagram illustrating an example of an UL channel within a 5G NR subframe. The 5G NR frame structure may be frequency division duplex (FDD) (wherein for a particular set of subcarriers (carrier system bandwidth), a subframe within the subcarrier set is dedicated to either DL or UL), or may be time division duplex (TDD) (wherein for a particular set of subcarriers (carrier system bandwidth), a subframe within the subcarrier set is dedicated to both DL and UL). Figure 2A , Figure 2CIn the example provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (most of which are DL), where D is DL, U is UL, and F is flexible between DL / UL, and subframe 5 is configured with slot format 54 (most of which are UL). Although subframes 5 and 4 are shown as having slot formats 54 and 28, respectively, any particular subframe can be configured with any of the various available slot formats 0 to 61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mix of DL, UL and flexible symbols. The slot format is configured for the UE via a received slot format indicator (SFI) (dynamically configured via DL control information (DCI) or semi-statically / statically configured via radio resource control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0052] Other wireless communication technologies may have different frame structures and / or different channels. For example, a 10 millisecond (ms) frame may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4, or 2 symbols. Each time slot may contain 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots in a subframe is based on the time slot configuration and parameter set. For slot configuration 0, different parameter sets μ0 to 4 allow 1, 2, 4, 8, and 16 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Thus, for slot configuration 0 and parameter set μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2 μ *15 kilohertz (kHz), where μ is parameter set 0 to 4. Therefore, the subcarrier spacing for parameter set μ=0 is 15 kHz, and the subcarrier spacing for parameter set μ=4 is 240 kHz. The symbol length / duration is inversely related to the subcarrier spacing. FIG. 2A to FIG. 2DAn example is provided for slot configuration 0 with 14 symbols per slot and parameter set μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs. Within a frame set, there may be one or more different bandwidth parts (BWPs) that are frequency-division multiplexed (see Figure 2B ). Each BWP can have a specific set of parameters.

[0053] A resource grid may be used to represent a frame structure. Each slot includes a resource block (RB) (also referred to as a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0054] like Figure 2A As illustrated, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) for channel estimation at the UE (indicated as R for a particular configuration). x , where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0055] Figure 2BExamples of various DL channels within a subframe of a frame are illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. The PDCCH within a BWP may be referred to as a control resource set (CORESET). Additional BWPs may be located at higher and / or lower frequencies on the channel bandwidth. The primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by UE 104 to determine subframe / symbol timing and physical layer identity. The secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS 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 may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the position of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block (also referred to as an SS block (SSB)). The MIB provides the system frame number (SFN) and the number of RBs in the system bandwidth. The physical downlink shared channel (PDSCH) carries user data, broadcast system information not sent over the PBCH such as the system information block (SIB), and paging messages.

[0056] like Figure 2C As illustrated, some of the REs carry DM-RS (indicated as R for a particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may send a DM-RS for a physical uplink control channel (PUCCH) and a DM-RS for a physical uplink shared channel (PUSCH). The PUSCH DM-RS may be sent in the first or first two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is sent and depending on the specific PUCCH format used, the PUCCH DM-RS may be sent in different configurations. The UE may send a sounding reference signal (SRS). The SRS may be sent in the last symbol of a subframe. The SRS may have a comb structure, and the UE may send the SRS on one of the teeth of the comb. The SRS may be used by the base station for channel quality estimation to achieve frequency-dependent scheduling of the UL.

[0057] Figure 2DExamples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and hybrid automatic repeat request (HARQ) acknowledgement (ACK) / negative acknowledgement (NACK) feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0058] Figure 3 An example diagram 300 is shown, which shows a non-limiting example of time and frequency resources that can be used for wireless communication based on a side link. In some examples, the time and frequency resources can be based on a time slot structure. In other examples, different structures can be used. In some examples, the time slot structure can be within a 5G / NR frame structure. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM and other wireless technologies. This is just an example, and other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) can be divided into 10 subframes (1ms) of the same size. Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4 or 2 symbols. Each time slot may contain 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. Diagram 300 illustrates a single time slot transmission, which may correspond to a transmission time interval (TTI) of 0.5 ms, for example.

[0059] A resource grid can be used to represent a frame structure. Each time slot may include a resource block (RB) (also referred to as a physical RB (PRB)) extending 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. Figure 300 also shows a plurality of subchannels, each of which may include a plurality of RBs. For example, a subchannel in a sidelink communication may include 10-100 RBs. The PSCCH may be configured (or preconfigured) to occupy 10, 12, 15, 20, 25 or other number of PRBs in a single subchannel. The PSCCH duration may also be configured (or preconfigured) to be 2, 3 or other number of symbols. In addition, a subchannel may occupy 10, 15, 20, 25, 50, 75, 100 or other number of PRBs. The number of subchannels in a resource pool (RP) may be any number including 1 to 27 subchannels or other number.

[0060] like Figure 3 As shown, the first symbol of a subframe may be a symbol for automatic gain control (AGC). Some REs may include control information, for example, together with PSCCH and / or PSSCH. The control information may include sidelink control information (SCI). For example, PSCCH may include SCI for the first phase. PSCCH resources may start at the first symbol of a timeslot and may occupy 1, 2, or 5 symbols. PSCCH may occupy at most one subchannel with the lowest subcarrier index. Figure 3 Also shown are symbols that may include the PSSCH. Figure 3 The symbols indicated for PSCCH or PSSCH in the , include PSCCH or PSSCH REs. Such symbols corresponding to PSSCH may also include REs containing second stage SCI and / or data. At least one symbol may be used for feedback (e.g., PSFCH), as described herein. Figure 3 As shown, symbols 12 and 13 are indicated for PSFCH, indicating that these symbols include PSFCH REs. In some aspects, symbol 12 of PSFCH may be a repetition of symbol 13. The gap symbols before and / or after the feedback may be used for turnaround between receiving data and sending feedback. Figure 3 As shown, symbol 10 includes a gap symbol to enable turnaround for feedback in symbol 11. Another symbol (e.g., at the end of the time slot) (symbol 14) can be used as a gap. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device, for example, in a subsequent time slot. As illustrated, data can be sent in the remaining REs. The data can include data messages as described herein. The location of any of the PSCCH, PSSCH, PSFCH, and gap symbols can be different from Figure 3 Example shown.

[0061] Resource allocation for sidelink transmission can be performed in different modes. In one mode (mode 1 resource allocation), the base station can provide a DCI that assigns resources for sidelink communication to the Tx UE. For example, the DCI can have DCI format 3_0. In another mode (mode 2 resource allocation), the Tx UE autonomously determines the resources for sidelink communication. In either mode, the Rx UE can similarly receive sidelink communication from the Tx UE in the configuration resource allocation.

[0062] In mode 1 resource allocation, DCI format 3_0 may indicate resource allocation for sidelink data transmission by one or more parameters. For example, the DCI may include a resource pool index that identifies a resource pool for sidelink data transmission. The resource pool index field may have a number of bits that depends on the number of resource pools configured by the base station (e.g., with parameter sl-TxPoolScheduling or some other name). The DCI may also include a time gap indicating the number of time slots after receiving the DCI that the Tx UE waits before transmitting the sidelink data transmission (e.g., to allow the Rx UE to have enough time to decode the DCI). The time gap field may have a fixed number of bits and a value that may be configured by the base station (e.g., with parameter sl-DCI-ToSL-Trans or some other name). The DCI may also include other parameters, including but not limited to: HARQ process #, NDI indicating whether the sidelink data transmission is the first transmission or a retransmission, SCI-1-A format field indicating the time / frequency resources used for the sidelink data transmission (for example, TDRA, FDRA, and the lowest subchannel index for allocation in the frequency domain), PSFCH to HARQ feedback timing between when the Tx UE receives PSFCH feedback from the Rx UE and transmits to the base station a PUCCH indicating whether the Rx UE successfully received the sidelink data transmission, a PUCCH resource indicator (PRI) for the PUCCH to the base station, and a configuration index for periodic resource grants indicating the configured resources applied to the sidelink transmission when the DCI is not a dynamic (single-trigger) grant but a configured grant.

[0063] Figure 44 is a block diagram of a base station 410 communicating with a UE 450 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 475. The controller / processor 475 implements layer 4 and layer 2 functionality. Layer 4 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 475 provides RRC layer functionality associated with broadcasting 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 functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with 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 through HARQ, priority handling, and logical channel prioritization.

[0064] The transmit (TX) processor 416 and the receive (RX) processor 470 implement layer 1 functionality associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 416 handles 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-quadrature amplitude modulation (M-QAM)). The decoded and modulated symbols can then be divided into parallel streams. Subsequently, each stream can be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) 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 time domain OFDM symbol stream. The OFDM stream is spatially pre-decoded to produce multiple spatial streams. Channel estimates from channel estimator 474 can be used to determine the coding and modulation schemes, as well as for spatial processing. Channel estimates can be derived from reference signals and / or channel condition feedback sent by device 450. Each spatial stream can then be provided to a different antenna 420 via a separate transmitter 418TX. Each transmitter 418TX can modulate an RF carrier with a corresponding spatial stream for transmission.

[0065] At the device 450, each receiver 454RX receives a signal through its corresponding antenna 452. Each receiver 454RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 456. The TX processor 468 and the RX processor 456 implement layer 1 functionality associated with various signal processing functions. The RX processor 456 can perform spatial processing on the information to recover any spatial stream destined for the device 450. If the destination of multiple spatial streams is the device 450, the RX processor 456 can combine them into a single OFDM symbol stream. The RX processor 456 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the device 410. These soft decisions can be based on channel estimates calculated by the channel estimator 458. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by device 410. The data and control signals are then provided to controller / processor 459, which implements layer 4 and layer 2 functionality.

[0066] The controller / processor 459 may be associated with a memory 460 that stores program codes and data. The memory 460 may be referred to as a computer-readable medium. The controller / processor 459 may provide demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between transport channels and logical channels. The controller / processor 459 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0067] Similar to the functions described in conjunction with the transmission performed by the device 410, the controller / processor 459 can provide RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality 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 through HARQ, priority handling, and logical channel prioritization.

[0068] Channel estimates derived by the channel estimator 458 from a reference signal or feedback transmitted by the device 410 may be used by the TX processor 468 to select appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 468 may be provided to different antennas 452 via corresponding transmitters 454TX. Each transmitter 454TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0069] UL transmissions are handled at device 410 in a manner similar to that described in conjunction with the receiver functionality at device 450. Each receiver 418RX receives a signal through its respective antenna 420. Each receiver 418RX recovers information modulated onto an RF carrier and provides the information to a RX processor 470.

[0070] The controller / processor 475 may be associated with a memory 476 that stores program codes and data. The memory 476 may be referred to as a computer readable medium. The controller / processor 475 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 550. The IP packets from the controller / processor 575 may be provided to the EPC 160. The controller / processor 475 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0071] At least one of the TX processor 468, the RX processor 456, and the controller / processor 459 may be configured to combine Figure 1 The 198 came to execute all aspects.

[0072] At least one of the TX processor 416, the RX processor 470, and the controller / processor 475 may be configured to combine Figure 1 199 to perform all aspects.

[0073] In other specific implementations, the first wireless communication device 480 is in communication with the second wireless communication device 450, for example, via V2X or other D2D communication. The communication can be, for example, based on a side link using a PC5 interface. Each of the first wireless communication device 480 and the second wireless communication device 450 may include a UE, an RSU, etc.

[0074] Typically, in sidelink communication, a first wireless communication device 480 (e.g., a Tx UE) initially achieves sidelink synchronization with a second wireless communication device 450 (e.g., an Rx UE). After synchronization, the Tx UE may obtain an allocation of time-frequency resources (e.g., one or more time slots, RBs, or subchannels in a resource pool) in which to send sidelink data to the Rx UE. A subchannel includes at least 10 or some other number of consecutive, non-overlapping RBs. Typically, resource allocations may be scheduled by a base station in downlink control information (DCI) (in mode 1 resource allocation), or resource allocations may be determined by a sensing procedure performed autonomously by the Tx UE (in mode 2 resource allocation). After determining the resources, the Tx UE may transmit sidelink control information (SCI) including resource allocations to the Rx UE in a physical sidelink control channel (PSCCH). The Tx UE may send SCI in two phases, including a first phase SCI (also referred to as SCI-1) carried on the PSCCH and a second phase SCI (also referred to as SCI-2) carried on the physical sidelink shared channel (PSSCH). SCI-1 may contain information about resource allocation, while SCI-2 may carry information for identifying and decoding sidelink data (e.g., modulation and coding scheme (MCS)). The Tx UE may send sidelink data in the PSSCH to the Rx UE in the allocated resources.

[0075] After receiving the sidelink transmission, the Rx UE may attempt to blindly decode the PSCCH in all allocated subchannels of the resource pool. Typically, the number of allocated subchannels in the resource pool is small (e.g., 1 to 27 subchannels), allowing blind decoding to be feasible. If the Rx UE successfully decodes the PSCCH, the UE may also attempt to decode the PSSCH scheduled by the PSCCH for the sidelink data. Depending on the decoding result, the Rx UE may provide a hybrid automatic repeat request (HARQ) acknowledgment / negative acknowledgment (ACK / NACK) feedback to the Tx UE in the physical sidelink feedback channel (PSFCH). For example, if the Rx UE fails to decode the sidelink data, the UE may provide a NACK to the Tx UE, and if the Rx UE successfully decodes the sidelink data, the UE may provide an ACK to the Tx UE. If the Tx UE receives a NACK from the Rx UE, the Tx UE may retransmit the sidelink data. Otherwise, if the Tx UE receives ACK from the Rx UE, the Tx UE may send new data to the Rx UE, or send data to a different Rx UE.

[0076] Figure 5 An example 500 of allocation of time slots 502 and subchannels 504 in a resource pool is illustrated. A Tx UE may transmit PSCCH and PSSCH in the same time slot. While PSSCH may occupy up to a configured number of consecutive subchannels in a time slot, The PSCCH may occupy only up to one subchannel in the slot with the lowest subchannel index. Figure 5 In the example of , the PSCCH may occupy subchannel 504 in time slot 502 (e.g., the upper left subchannel shown corresponding to the lowest subchannel index). The Tx UE may send SCI-1 in the PSCCH, which may include information about the PSSCH bandwidth and resource reservations configured in subsequent time slots. The Tx UE may also send SCI-2 in the PSSCH, which may include information such as a source identifier (Source ID) and a destination identifier (Destination ID) of the sidelink packet carried in the PSSCH. Upon receiving the sidelink transmission, the Rx UE may blindly decode each subchannel of the time slot used for the PSCCH. After decoding the PSCCH, the Rx UE may decode the PSSCH to distinguish whether the sidelink packet is intended for the Rx UE or another UE and identify the Tx UE that transmitted the packet.

[0077] When the Tx UE sends SCI-1, the SCI-1 may indicate the number and location of resource reservations for the PSSCH. For example, the SCI-1 may indicate a frequency domain resource allocation (FDRA) and a time domain resource allocation (TDRA), which indicate the subchannels and time slots reserved for sidelink data transmission. The FDRA and TDRA may each be a field of the SCI-1, where each field may include a different number of bits, depending on the number of reservations configured for sidelink transmission. For example, in the FDRA, the number of bits in the FDRA field for two reservations may be or some other number, and for three reservations it could be Or some other number. The value of the bit in FDRA can indicate the subchannel and RB allocated for the sidelink data in the resource pool. Similarly, in TDRA, the number of bits can be 5 or some other number for two reservations and 9 or some other number for three reservations. The value of the bit in TDRA indicates the time slot and symbol allocated for the sidelink data in the resource pool.

[0078] In addition to TDRA and FDRA, SCI-1 may include various other fields. For example, SCI format 1-A in PSCCH may indicate at least the following information: a priority associated with PSSCH transmission and having a fixed number of bits (e.g., 3 bits or some other number), an FDRA whose number of bits depends on the number of timeslot reservations and the number of subchannels such as previously described, a TDRA whose number of bits depends on the number of reservations such as previously described (e.g., 5 bits for 2 reservations and 9 bits for 3 reservations), a resource reservation period whose number of bits depends on the number of allowed periods, a DMRS pattern whose number of bits depends on the number of configured patterns, a resource reservation period whose number of bits depends on the number of allowed periods, a resource reservation period whose number of bits depends on the number of configured patterns, a resource reservation period whose number of bits depends on the number of resource reservations such as previously described ... The SCI-1 may include an SCI-2 format having a fixed number of bits (e.g., 2 bits or some other number), a beta offset for SCI-2 rate matching having a fixed number of bits (e.g., 2 bits or some other number), a DMRS port having a number of bits (e.g., 1 bit or some other number) indicating the number of data layers of the PSSCH (e.g., one or two data layers), an MCS having a fixed number of bits (e.g., 5 bits or some other number), an additional MCS table having a fixed number of bits (e.g., 0 to 2 bits or some other range), a PSFCH overhead indicator having a fixed number of bits (e.g., 0 or 1 bit or some other number), and reserved bits used by upper layers. The Rx UE may decode the SCI-1 to determine this information and receive the PSSCH. In addition, when the resources allocated in the SCI-1 are autonomously determined by the Tx UE (in mode 2 resource allocation), the Rx UE and other sidelink UEs may decode the SCI-1 in order to perform channel sensing and avoid resource conflicts.

[0079] Figure 6 An example of a resource pool 600 including resource reservations 602 for sidelink data transmission is illustrated. Each resource reservation 602 may include a time slot 604 and one or more subchannels 606. For example, a base station or Tx UE may configure a resource pool with three resource reservations, such as Figure 6 As shown, each resource reservation spans one time slot and two subchannels. The base station may configure the resource pool 600 and the resource reservation 602 in the DCI (in mode 1 resource allocation), or the Tx UE may autonomously determine the resource pool 600 and the resource reservation 602 (in mode 2 resource allocation). The Tx UE may also indicate the resource pool 600 and the resource reservation 602 in SCI-1 to the Rx UE. For example, the Tx UE may send a PSCCH including SCI-1 in time slot i, indicating that resource reservations for the PSSCH are present in time slots i, i+x, and i+y, and each resource reservation spans a plurality of subcarriers z, where i, x, y, and z are configuration values ​​such as indicated in, for example, Table 1 below. These values ​​are merely examples; in other examples, the resource pool may be configured with a different number of resource reservations spanning a different number of time slots and subchannels.

[0080]

[0081] Table 1

[0082] Therefore, the Tx UE may send SCI-1 to indicate to the Rx UE the resources allocated for the PSSCH. Additionally, the Tx UE may send SCI-2 to indicate other information for the Rx UE to decode the PSSCH. For example, SCI-2 may be front-loaded in the PSSCH to indicate at least the following information: a HARQ process ID of the PSSCH whose number of bits depends on the number of HARQ processes, a new data indicator (NDI) with a fixed number of bits (e.g., 1 bit), a redundancy version identifier (RV-ID) with a fixed number of bits (e.g., 2 bits), a source identifier of the Tx UE with a fixed number of bits (e.g., 8 bits), a destination identifier of the Rx UE with a fixed number of bits (e.g., 16 bits), and a HARQ enable / disable flag with a fixed number of bits (e.g., 1 bit). Additionally, SCI-2 may include other fields specific to the SCI-2 format. For example, the SCI 2-A format may indicate a transmission type (broadcast, groupcast, unicast) of the PSSCH with a fixed number of bits (e.g., 2 bits) and a CSI request flag with a fixed number of bits (e.g., 1 bit), and the SCI 2-B format may indicate an area identifier (e.g., 12 bits) and a communication range (e.g., 4 bits). The Rx UE and other sidelink UEs may determine this information to identify which UEs are the Rx UEs and to allow the Rx UEs to successfully decode the PSSCH in the allocated resources. In some aspects, for configuration grants in both Type 1 and Type 2 sidelink communications, the HARQ process ID associated with the first time slot transmitted by the sidelink can be derived from the following equation: HARQ Process ID = [floor(CURRENT_slot / sl-PeriodCG)] modulosl-NrOfHARQ-Processes+sl-HARQ-ProcID-offset, where CURRENT_slot = (SFN×numberOfSlotsPerFrame+number of time slots in a frame), and numberOfSlotsPerFrame refers to the number of consecutive time slots per frame.

[0083] Figure 7 is a diagram illustrating an example 700 of side link communications and access link communications according to various aspects of the present disclosure. Figure 7 As shown, a transmitter (Tx) UE 702 and a receiver (Rx) UE 710 can communicate with each other via sidelink communication 704. As further shown, in some sidelink modes, the base station 102 / 180 can communicate with the Tx UE 702 via an access link. The Tx UE 702 and / or the Rx UE 706 can correspond to one or more UEs described elsewhere herein, such as Figure 1104 of the base station 102 / 180. Thus, the direct link between the UEs 104 (e.g., via the PC5 interface) may be referred to as a side link, and the direct link between the base station 102 / 180 and the UE 104 (e.g., via the Uu interface) may be referred to as an access link. Side link communications may be sent via a side link, and access link communications may be sent via an access link. Access link communications may be downlink communications (from the base station 102 / 180 to the UE 104) or uplink communications (from the UE 104 to the base station 102 / 180).

[0084] In Mode 1 resource allocation, the base station 102 / 180 may provide a resource grant 710 to the Tx UE 702 indicating a resource allocation for the sidelink communication 704. The resource grant 710 may be, for example, a dynamic grant (DG), a configuration grant (CG) type 1, or a CG type 2. For DG, the resource grant 710 may be a DCI that the base station 102 / 180 provides to the Tx UE 702 aperiodically, indicating the time-frequency resources for the sidelink communication 704 on a slot-by-slot basis. For CG type 1, the resource grant 710 may be an RRC configuration that the base station 102 / 180 provides to the Tx UE 702 periodically, indicating the time-frequency resources for the sidelink communication 704 for a configured period of time or until a subsequent resource grant is sent. For CG type 2, the resource grant 710 can be a DCI that the base station 102 / 180 provides to the Tx UE 702 to activate the configured resource allocation for the sidelink communication 704 for a configured time period or until a subsequent resource grant is sent. The activated resource allocation can be configured in an RRC configuration similar to the configuration for CG type 1. In the DG or CG where the base station 102 / 180 provides the DCI to the Tx UE 702 to allocate or activate time-frequency resources, the DCI can include a specific DCI format 3_0 associated with mode 1 resource allocation. The DCI format can indicate the TDRA and FDRA of the sidelink source, the transmission timing between receiving the resource grant 710 and sending the sidelink communication 704, and other information. The DCI may not configure a specific MCS for the sidelink communication; instead, the Tx UE can determine the MCS within the limits configured by the base station. After obtaining the resource allocation, the Tx UE 702 provides the sidelink communication 704 to the Rx UE 706 in the allocated resources.

[0085] In contrast, for mode 2 resource allocation, the Tx UE 702 may not receive a resource grant from the base station that allocates resources for the sidelink communication 754. Instead, the Tx UE 702 autonomously performs channel sensing and resource selection. For example, during channel sensing, the Tx UE 702 blindly decodes all PSCCH channels and determines the resources reserved for other sidelink transmissions. After determining the reserved resources, during resource selection, the Tx UE 702 reports the available resources to the upper layers of the Tx UE 702, which then decides the resources to be allocated to the sidelink communication 704. After selecting the resources, the Tx UE 702 can provide the sidelink communication 704 to the Rx UE 706 in the selected resources.

[0086] Sidelink communication may also be applicable to the Industrial Internet of Things (IIoT). In IIoT, a programmable logic controller (PLC) can communicate directly with a sensor or actuator in a sidelink manner to collect, exchange and analyze data, and promote improvements in productivity, efficiency or other benefits in industrial applications. Typically, IIoT services are deterministic for packets of 32 to 256 bytes (or other byte ranges), and since the bandwidth required for IIoT services is relatively low, a small amount of RBs (such as 2 RBs) may be sufficient for data communication. In addition, sensors and actuators may have UE capability constraints in terms of bandwidth and processing power, even if the total bandwidth in a dedicated band or unlicensed band may be relatively large. In addition, sensors and actuators may not detect or monitor all transmissions in IIoT. Therefore, each of these business characteristics allows sidelink communication to be an effective communication method in IIoT.

[0087] Figure 8 8 is a diagram illustrating an example 800 of sidelink communications according to various aspects of the present disclosure. Figure 8As shown, the first UE 805-1 can communicate with the second UE 805-2 (and one or more other UEs 805) via one or more side link channels 810. UEs 805-1 and 805-2 can communicate using one or more side link channels 810 for P2P communication, D2D communication, V2X communication (e.g., which may include V2V communication, V2I communication, V2P communication, etc.), mesh networking, etc. In some aspects, UE 805 (e.g., UE 805-1 and / or UE 805-2) can correspond to one or more other UEs described elsewhere herein, such as UE 120. In some aspects, one or more side link channels 810 can use a PC5 interface and / or can operate in a high frequency band (e.g., 8.9 GHz band). Additionally or alternatively, UE 805 can use global navigation satellite system (GNSS) timing to synchronize the timing of a transmission time interval (TTI) (e.g., frame, subframe, time slot, symbol, etc.).

[0088] like Figure 8 As further shown, the one or more sidelink channels 810 may include a physical sidelink control channel (PSCCH) 815, a physical sidelink shared channel (PSSCH) 820, and / or a physical sidelink feedback channel (PSFCH) 825. The PSCCH 815 may be used to convey control information, similar to a physical downlink control channel (PDCCH) and / or a physical uplink control channel (PUCCH) used for cellular communication with the base station 102 via an access link or access channel. The PSSCH 820 may be used to convey data, similar to a physical downlink shared channel (PDSCH) and / or a physical uplink shared channel (PUSCH) used for cellular communication with the base station 102 via an access link or access channel. For example, the PSCCH 815 may carry sidelink control information (SCI) 830, which may indicate various control information for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, space resources, etc.), where a transport block (TB) 835 may be carried on the PSSCH 820. The TB 835 may include data. The PSFCH 825 may be used to communicate sidelink feedback 840 such as hybrid automatic repeat request (HARQ) feedback (eg, acknowledgement or negative acknowledgement (ACK / NACK) information), transmit power control (TPC), scheduling request (SR), and the like.

[0089] In some aspects, one or more sidelink channels 810 may use a resource pool. For example, a scheduling assignment (e.g., included in SCI 830) may be sent in a subchannel across time using specific resource blocks (RBs). In some aspects, data transmissions associated with a scheduling assignment (e.g., on PSSCH 820) may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and the associated data transmission are not sent on adjacent RBs.

[0090] In some aspects, UE 805 may operate using a transmission mode in which resource selection and / or scheduling is performed by UE 805 (e.g., rather than base station 102). For the purpose of brevity, depending on the specific implementation, UE 805 refers to one of UE 805-1 or 805-2, or both together. In some aspects, UE 805 may perform resource selection and / or scheduling by sensing channel availability for transmission. For example, UE 805 may measure received signal strength indicator (RSSI) parameters associated with various side link channels (e.g., side link RSSI (S-RSSI) parameters), may measure reference signal received power (RSRP) parameters associated with various side link channels (e.g., PSSCH-RSRP parameters), may measure reference signal received quality (RSRQ) parameters associated with various side link channels (e.g., PSSCH-RSRQ parameters), etc., and may select a channel for transmission of side link communication based at least in part on these measurements.

[0091] Additionally or alternatively, the UE 805 may perform resource selection and / or scheduling using the SCI 830 received in the PSCCH 815, which may indicate occupied resources, channel parameters, etc. Additionally or alternatively, the UE 805 may perform resource selection and / or scheduling by determining a channel busy rate (CBR) associated with each sidelink channel, which may be used for rate control (e.g., by indicating a maximum number of resource blocks that the UE 805 may use for a particular set of subframes).

[0092] In a transmission mode in which resource selection and / or scheduling is performed by the UE 805, the UE 805 may generate a sidelink grant and may transmit the grant in the SCI 830. The sidelink grant may indicate, for example, one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks (e.g., for TB 835) to be used for an upcoming sidelink transmission on the PSSCH 820, one or more subframes to be used for an upcoming sidelink transmission, a modulation and coding scheme (MCS) to be used for an upcoming sidelink transmission, etc. In some aspects, the UE 805 may generate a sidelink grant indicating one or more parameters (such as the periodicity of the sidelink transmission) for semi-persistent scheduling (SPS). Additionally or alternatively, the UE 805 may generate a sidelink grant for event-driven scheduling (such as for an on-demand sidelink message).

[0093] Fig. 9 900 is a diagram illustrating an example of an acknowledgement message for a sidelink channel in accordance with various aspects of the present disclosure. In some aspects, a base station (e.g., base station 102) may send and a UE (e.g., UE 905-2) may receive a resource grant (e.g., as described above in conjunction with Figure 7 and 8 As described above). Thus, UE 905-2 can communicate with one or more additional UEs (e.g., UE 905-1) on at least one sidelink channel. In some aspects, the resource grant can include a DCI, such as format 3_0 DCI (e.g., as defined in 3GPP specifications and / or other standards).

[0094] In some aspects, the base station 102 may send and the Tx UE 905-2 may receive a resource grant 910 for at least one sidelink channel. Fig. 9 As shown, the resource grant 910 may include downlink control information (DCI), such as format 3_0 DCI (e.g., as defined in 3GPP specifications and / or other standards). The resource grant 910 may indicate one or more time resources (e.g., one or more symbols spanning one or more time slots within one or more frames) for use by the Tx UE 905-2 on at least one side link channel. Additionally or alternatively, the resource grant 910 may indicate one or more frequency resources (e.g., one or more component carriers (CCs) to be used on one or more subbands within one or more bandwidth parts (BWPs)) for use by the Tx UE 905-2 on at least one side link channel.

[0095] like Fig. 9As further shown, the resource grant 910 may indicate uplink resources (e.g., resources on the PUCCH) so that the Tx UE 905-2 may report an acknowledgement message (e.g., ACK / NACK feedback and / or other HARQ feedback) received from the Rx UE 905-1 (e.g., on the PSFCH). In some aspects, the Tx UE 905-2 may copy the acknowledgement message received on the PSFCH to the PUCCH indicated by the resource grant 910. In one example, when the Tx UE 905-2 (e.g., only to the Rx UE 905-1) unicasts data, the Tx UE 905-2 may copy the acknowledgement message received on the PSFCH to the PUCCH and send NACK feedback on the PUCCH when nothing is received on the PSFCH. In another example, when Tx UE 905-2 multicasts data (e.g., to a group of UEs including Rx UE 905-1), when an ACK message is received from the group of UEs on all PSFCHs, Tx UE 905-2 may send ACK feedback on PUCCH, otherwise send NACK feedback. In yet another example, when Tx UE 905-2 performs area-based transmission (e.g., to the geographic area where Rx UE 905-1 is located), when a NACK message is received on any PSFCH, Tx UE 905-2 may send NACK feedback on PUCCH, otherwise send ACK feedback.

[0096] In some aspects, the Tx UE 905-2 may use a listen-before-talk (LBT) procedure on at least one side link channel. For example, the Tx UE 905-2 may wait for one or more symbols of a time slot and transmit in the time slot (e.g., to the Rx UE 905-1) only if the Tx UE 905-2 does not decode the transmission in those one or more symbols. In some aspects, the Tx UE 905-2 may use the LBT procedure at least in part because at least one side link channel is on an unlicensed band channel. For example, at least one side link channel may use NR unlicensed (NR-U) spectrum.

[0097] Typically, the physical layer of the Tx UE 905-2 may report the LBT status (e.g., pass or fail) to the upper layer (e.g., medium access control (MAC) layer) of the Tx UE 905-2. The upper layer will filter and average the LBT status and report them to the base station 102 (e.g., using a MAC control element (MAC-CE)). However, this results in a delay between the Tx UE 905-2 detecting the LBT status and reporting them to the base station 102. In addition, the Tx UE 905-2 consumes additional processing resources by filtering and averaging the LBT status, even though this results in the base station 102 receiving less accurate information about which subbands on at least one side link channel should be reallocated.

[0098] Some techniques and apparatus described herein allow a UE (e.g., UE 104 and / or UE 905-2) to report at least one state associated with an LBT procedure using an uplink channel (e.g., PUCCH) configured by a base station (e.g., base station 102). Thus, UE 905-2 may report the LBT state to base station 102 via the PUCCH.

[0099] Fig.10 1 is a diagram illustrating an example 1000 associated with LBT reporting for a sidelink channel in accordance with various aspects of the present disclosure. In some aspects, a base station (e.g., base station 102) may send and a UE (e.g., UE 1005-2) may receive a resource grant (e.g., as described above in conjunction with Figure 3 and 10 As described above). Thus, UE 1005-2 can communicate with one or more additional UEs (e.g., UE 1005-1) on at least one sidelink channel. In some aspects, the resource grant can include a DCI, such as format 3_0 DCI (e.g., as defined in 3GPP specifications and / or other standards).

[0100] like Fig.10 As shown, the resource grant may indicate uplink resources for sending a sidelink transmission confirmation message. For example, the resource grant may indicate uplink resources (e.g., resources on the PUCCH) so that UE 1005-2 can report confirmation messages (e.g., ACK / NACK feedback and / or other HARQ feedback) received from UE 1005-1 (e.g., on the PSFCH as shown in example 1000).

[0101] In some aspects, UE 1005-2 may employ LBT procedures on at least one sidelink channel. For example, UE 1005-2 may employ LBT procedures at least in part because at least one sidelink channel is on an unlicensed band channel.

[0102] like Fig.10 As further shown, UE 1005-2 may transmit on an uplink resource (e.g., on a PUCCH resource) and base station 102 may receive on the uplink resource an indication of at least one state associated with an LBT procedure used on at least one sidelink channel. In some aspects, as described below in conjunction with Fig.10 As described above, the indication may also be based at least in part on one or more sidelink transmission confirmation messages (e.g., received on the PSFCH). Fig.10 The indication of at least one state may include two or more bits.

[0103] In some aspects, UE 1005-2 may receive additional resource grants for at least one additional sidelink channel. Additionally, the resource grant may indicate uplink resources for sending sidelink transmission confirmation messages. Thus, multiple resource grants (e.g., format 3_0 DCI and / or other resource grants as defined in 3GPP specifications) may indicate the same uplink resources (e.g., the same PUCCH resources) for reporting confirmation messages (e.g., ACK / NACK feedback and / or other HARQ feedback) received from UE 1005-1 (e.g., on the PSFCH shown in example 1000).

[0104] In some aspects, UE 1005-2 may employ LBT procedures on at least one additional side link channel. For example, UE 1005-2 may employ LBT procedures at least in part because at least one additional side link channel is on an unlicensed band channel.

[0105] Thus, UE 1005-2 may determine at least one additional state associated with the LBT procedure used on at least one additional side link channel. Additionally, UE 1005-2 may combine the at least one additional state with the at least one state before transmitting on the uplink resource (e.g., as described below in conjunction with Fig.10 described above).

[0106] By using the combination Fig.10 With the described technology, UE 1005-2 can use an uplink channel (e.g., PUCCH) configured by base station 102 to report at least one state associated with the LBT procedure. Therefore, UE 1005-2 can report the LBT state to base station 102 with reduced latency while saving processing resources. In addition, base station 102 can receive a more accurate LBT state from UE 1005-2. Therefore, base station 102 can more efficiently reallocate subbands on at least one side link channel, and thus improve the quality and reliability of communications on at least one side link channel.

[0107] Fig.11 An example 1100 of sidelink communication based on Mode 1 resource allocation in accordance with various aspects of the present disclosure is illustrated. In the illustrated example, a base station may send a PDCCH 1104 to a Tx UE 1102 that schedules resources for a PSCCH 1106, a PSSCH 1108, and a PSFCH 1110 in multiple resource reservations. Fig.11 An example of indicating resources in a DCI from a base station in a PDCCH 1104 for CG type 2 is shown, but alternatively resources may be configured in an RRC configuration for CG type 1. In addition, the Tx UE 1102 may repeat the sidelink communication in each configured resource according to the time gap indicated in the DCI. For example, in Fig.11 In the example of , where the base station configures three resource reservations for sidelink communication (e.g., an initial transmission and two retransmissions), the Tx UE 1102 may communicate the sidelink data to the Rx UE three times starting three time slots after receiving the DCI. If the Rx UE fails to receive or decode the sidelink data transmission, the Rx UE may provide HARQ-ACK feedback to the Tx UE 1102 in the PSFCH 1110, such as Fig.11 For example, Fig.11 As shown in , Tx UE 1102 sends PSCCH 1106 and PSSCH 1108 to Rx UE, and determines through HARQ-ACK feedback from Rx UE that Rx UE fails to receive or decode PSSCH 1108. At this point, Tx UE 1102 sends the first retransmission of PSSCH 1108 (together with PSCCH 1106) to Rx UE at a time instance after the PSFCH associated with the initial transmission. The time instances may be separated by time gaps. In one or more specific implementations, the time gap may be defined as T_prep+δ. After sending the retransmission, Tx UE 1102 determines through HARQ-ACK feedback from Rx UE that Rx UE fails to receive or decode the retransmission of PSSCH 1108. In this regard, the Tx UE 1102 sends a second retransmission of the PSSCH 1108 (along with the PSCCH 1106) to the Rx UE at a time instance separated by the same time gap after the PSFCH associated with the first retransmission. In response to receiving the HARQ-ACK feedback associated with the second retransmission, the Tx UE 1102 may provide the HARQ-ACK feedback to the base station in the PUCCH 1112 according to the PSFCH to HARQ feedback timing and the PRI indicated in the DCI. For example, Fig.11In the example of , the Tx UE may provide HARQ-ACK feedback to the base station in the configured resources of the PUCCH 1112 after receiving the PSFCH 1110 .

[0108] In some aspects, each of the three resource reservations may be dynamically configured for sidelink communication with the corresponding PDCCH. For example, the base station may again provide DCI to the UE in PDCCH 1104 to configure Tx UE 1102 to retransmit the TB in the resource reservation allocated for retransmission, such as Fig.11 as shown in the example.

[0109] In some aspects, up to three sidelink data resources may be assigned to the Tx UE 1102 during each CG period. In one aspect, the resource grant indicates that only one sidelink data resource may be used for a new TB. Other sidelink data resources may also be used for retransmissions of new TBs that have been sent in the current CG period or a previous CG period. In some aspects, the resource grant may indicate that the second sidelink resource is configured at a time gap after a PSFCH instance associated with the first sidelink data resource. In some aspects, the maximum number of retransmissions per TB may be associated with the priority of the TB.

[0110] The Tx UE 1102 may send HARQ-ACK feedback, such as an ACK / NACK report (if configured) in a PUCCH configured after the PSFCH associated with the last sidelink data resource allocated for each CG period. The HARQ-ACK feedback may correspond to one or more bits of the PUCCH 1112 to inform the base station of the success of the potential last three sidelink data transmissions.

[0111] The ACK / NACK report may include information of an initial transmission and one or more retransmissions of the same TB. In some aspects, the Tx UE 1102 may report ACK in the PUCCH 1112 only if all Rx UEs correctly receive at least one of the retransmissions and the Rx UEs positively acknowledge receipt of the retransmissions to the Tx UE 1102. When the feedback report includes information of transmissions and retransmissions of different TBs, the Tx UE 1102 may report ACK only if all Rx UEs correctly receive different TBs and the Rx UEs positively acknowledge receipt of different TBs to the Tx UE 1102.

[0112] In sidelink Mode 1 operation for unlicensed spectrum, the NAK in PUCCH 1112 does not reflect whether the negative acknowledgement is due to an LBT failure or a decoding failure. Fig. 9 and Fig.10The legacy technique described in provides for reusing PUCCH resources allocated for HARQ-ACK feedback reporting in sidelink mode 1 operation to report LBT failures directly to the base station. In some aspects, L1-based LBT failure reporting can have less latency than the PUCCH legacy approach. The LBT status report can be configured on top of the HARQ-ACK feedback. The LBT status report can be sent per subband or subband group. The PUCCH resources granted by DCI 3_0 in sidelink mode 1 operation can be at a location where the scheduled PSSCH is assumed to be transmitted and the corresponding PSFCH is received.

[0113] Fig.11 Some of the described techniques and apparatus allow the Tx UE 1102 to report at least one state associated with the LBT procedure using a PUCCH 1112 configured by a base station (e.g., base station 102). However, for unlicensed spectrum operation, sidelink transmissions are subject to the LBT state, and therefore, multiple transmission opportunities for the CG may be required. In NR-U operation, the mechanisms for both CG Type 1 and CG Type 2 can be extended, and the number of allocated time slots after the time instance corresponding to the indicated configuration grant offset can be configured to provide additional LBT opportunities. For example, the NR-U configuration may indicate (via the cg-nrofSlots parameter) the number of time slots allocated in the configuration grant periodicity after the time instance of the configuration grant offset, and also indicate (via the cg-nrofPUSCH-InSlot parameter) the number of consecutive PUSCHs configured for the CG within the time slot, where the SLIV indicates the first PUSCH and an additional PUSCH with the same length attached. For sidelink unlicensed (SL-U) operation, there is a need to introduce additional LBT opportunities. Although legacy sidelink operation provides up to three sidelink data resources within a CG period, at least two sidelink data resources may need to be spaced apart to allow the PSFCH to be located in the middle for feedback.

[0114] In one or more specific implementations, the present technology provides for extending the number of allocated time slots for additional LBT opportunities after a time instance corresponding to a timing offset indicated by a TRIV within a sidelink CG period.

[0115] Fig.12 Another example 1200 of sidelink communication based on mode 1 resource allocation according to various aspects of the present disclosure is illustrated. Fig.11In the example shown, the base station may send a PDCCH 1204 to a Tx UE 1202, which schedules resources for PSCCH 1206, PSSCH 1208, and PSFCH 1210 in multiple resource reservations. For a CG type 1 configuration, the TRIV may be included in the RRC via the sl-TimeResourceCG-Type1 parameter. For a CG type 2 configuration, the TRIV may be included in a DCI having format 3_0 for CG activation and / or reactivation. The TRIV may schedule sidelink data resources with up to three time slots for initial transmission and retransmission. The Tx UE 1202 may repeat the sidelink communication in each configured resource according to the time gap indicated in the DCI. However, in this example, the Tx UE 1202 is configured with additional candidate transmission time slots for each resource reservation in the resource reservation. In one or more specific implementations, the present technology provides for extending the number of allocated time slots for additional LBT opportunities after a time instance corresponding to a timing offset indicated by the TRIV in a sidelink CG time period. In this example, the initial transmission may be configured with a set of transmission slots 1220. For example, the transmission slots 1220 include a nominal slot for the initial transmission carrying a new TB and three additional candidate transmission slots. In some aspects, the transmission slots 1220 include continuous slots. For example, the nominal slot and the three additional candidate transmission slots are continuous with each other in time and / or frequency. In other aspects, the transmission slots 1220 include non-continuous slots. For example, the nominal slot and the three additional candidate transmission slots may be separated from each other in time and / or frequency. In one aspect, a subset of the transmission slots 1222 may be continuous, and another subset of the transmission slots 1222 may be non-continuous.

[0116] In some aspects, all time slots including the nominal time slot and the additional time slots thereafter are candidate transmission time slots that allow additional LBT opportunities. If the Tx UE 1202 determines that the LBT procedure fails at the nominal time slot, the Tx UE 1202 can use the additional time slots after the nominal time slot to continue additional LBT attempts. By doing so, the Tx UE 1202 can increase the probability of LBT success and reduce the number of occurrences of LBT failure. In some aspects, when the Tx UE 1202 determines that LBT is cleared and PSCCH / PSSCH is sent, any additional time slot may not be used. In this example, the Tx UE 1202 determines that LBT fails in the nominal time slot, so it attempts LBT in the next time slot (represented as the first additional candidate transmission time slot in three additional candidate transmission time slots). LBT is cleared in the additional time slot, so the Tx UE 1202 attempts to send PSSCH1208 during the time slot. The two remaining candidate transmission time slots may not be used by the Tx UE 1202. For example, the Tx UE 1202 may avoid attempting the LBT procedure at any of the two remaining candidate transmission time slots.

[0117] In one or more specific implementations, the number of additional time slots allocated after the nominal time slot is configurable. In some aspects, the number of additional time slots can be configured via RRC signaling for both CG type 1 and CG type 2. In some aspects, additional time slots allowed for LBT opportunities may become additional overhead for the network. In this regard, the present technology provides a more dynamic control over the number of additional time slots. In some specific implementations, the LBT status report can be sent back to the network via PUCCH 1212. In this regard, for side link CG type 2 operation, the base station may need to dynamically readjust the number of additional time slots. For example, the number of additional time slots for side link CG type 2 operation can be configured via DCI (e.g., DCI3_x) for CG activation and / or reactivation. In some aspects, the number of additional time slots can be indicated in one or more DCI fields.

[0118] In this example, the Rx UE does not successfully decode the sidelink communication in the initial transmission, so the Rx UE may provide HARQ-ACK feedback to the Tx UE 1202 in the PSFCH 1210, as shown in FIG. Fig.12As shown in the example of . In response to receiving HARQ-ACK feedback indicating that the Rx UE failed to receive or decode the initial transmission of PSSCH 1208, the Tx UE 1202 retransmits the previous sidelink data to the Rx UE by performing a retransmission of PSSCH 1208 (together with PSCCH 1206) at a time instance after the PSFCH associated with the initial transmission. In this example, the retransmission can be configured with a set of transmit time slots 1222. For example, the transmit time slot 1222 includes a nominal time slot for carrying a retransmission of previous sidelink data and three additional candidate transmit time slots. The LBT is cleared in the nominal time slot allocated for the retransmission, so the TX UE 1202 attempts to retransmit PSSCH 1208 during this time slot. The three remaining candidate transmit time slots may not be used by the Tx UE 1202. The Tx UE 1202 may similarly provide HARQ-ACK feedback to the base station in the PUCCH 1212 based on the PSFCH to HARQ feedback timing and the PRI indicated in the DCI. Thus, the Tx UE 1202 may report the LBT status to the base station 102 with reduced latency while saving processing resources. In addition, the base station 102 receives a more accurate LBT status from the Tx UE 1202. Thus, the base station 102 may more efficiently reallocate subbands on one or more sidelink channels and thereby improve the quality and reliability of communications on these sidelink channels.

[0119] Fig.13 Another example 1300 of sidelink communication based on mode 1 resource allocation according to various aspects of the present disclosure is illustrated. Fig.12 In the example shown, the base station can send a PDCCH 1304 to a Tx UE 1302, which schedules resources for PSCCH 1306, PSSCH 1308, and PSFCH 1310 in multiple resource reservations. In this example, the Rx UE does not successfully decode the sidelink communication in the initial transmission, so the Rx UE can provide HARQ-ACK feedback to the Tx UE 1302 in PSFCH 1310, as shown. Fig.13As shown in the example of . In response to receiving HARQ-ACK feedback indicating that the Rx UE failed to receive or decode the initial transmission of PSSCH 1308, the Tx UE 1302 retransmits the previous sidelink data to the Rx UE by performing a retransmission of PSSCH 1308 (together with PSCCH 1306) at a time instance after the PSFCH associated with the initial transmission. In this example, the retransmission can be configured with a set of transmission time slots 1322. For example, the transmission time slot 1322 includes a nominal time slot for carrying a retransmission of the previous sidelink data and three additional candidate transmission time slots. LBT fails in the nominal time slot and the first additional candidate transmission time slot, but is eventually cleared in the second additional candidate transmission time slot, so the TX UE 1302 attempts to retransmit PSSCH 1308 during that time slot. The single remaining candidate transmission time slot may not be used by the Tx UE 1302.

[0120] The Tx UE 1302 may send HARQ-ACK feedback, such as an ACK / NACK report (if configured), in a PUCCH that is configured after the PSFCH associated with the last sidelink data resource allocated for each CG time period. In the present technology, additional candidate transmit time slots are introduced for the last allocated sidelink data resource, as may be indicated in the TRIV. In some aspects, each of the additional candidate transmit time slots may be associated with a corresponding PSFCH opportunity.

[0121] However, there may be some uncertainty as to when the Tx UE 1302 may receive an ACK / NACK report from the Rx UE via the PSFCH in the last allocated set of time slots. To address this uncertainty, the present technology provides for configuring the PUCCH to be transmitted after the PSFCH associated with the last candidate transmit time slot in the last allocated sidelink data resources indicated by the TRIV. In this example, the Tx UE 1302 may provide HARQ-ACK feedback to the base station in PUCCH 1312 after PSFCH 1324, which is the PSFCH associated with the last candidate transmit time slot. In some aspects, even if the PUCCH resources are allocated after the last possible PSFCH, the configuration grant offset may be determined by the sl-PSFCH-ToPUCCH-CG-Type1-r16 parameter for CG Type 1 and by the PSFCH to HARQ Feedback Timing DCI field for CG Type 2.

[0122] Fig.141 is a flow chart of a process 1400 for wireless communication according to various aspects of the present disclosure. Process 1400 may be performed by a wireless communication device (e.g., UE 104, 705-1, 705-2, 805-1, 805-2, 905-1, 905-2, 1005-1, 1005-2, 1102, 1202, 1302; device 450, 480, RSU 107; apparatus 1602, which may include a memory, a cellular baseband processor, and one or more components configured to perform process 1400). As shown, process 1400 includes a plurality of enumerated steps, but embodiments of process 1400 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of these enumerated steps may be omitted or performed in a different order. Optional aspects are represented by dashed lines.

[0123] At 1410, the Tx UE may receive a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, wherein the plurality of resources include a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with respective time slots of the plurality of allocated time slots for additional opportunities for LBT procedures on at least one sidelink channel. In some implementations, the resource grant involving RRC signaling may be, for example, provided by the RRC configuration component 1640 via Fig.16 In other specific implementations, resource grants involving DCI signaling can be received by, for example, control information component 1642 via Fig.16 The side link channel is received by the receiving component 1630 of the device 1602 for CG type 2 configuration. In some aspects, at least one side link channel is on an unlicensed band channel (e.g., SL-U).

[0124] At 1420, the Tx UE may send an indication of at least one state associated with an LBT procedure used on at least one sidelink channel to the base station. The indication of at least one LBT procedure may be provided, for example, by the sidelink communication manager 1632 via Fig.16 The sending component 1634 of the device 1602 in is sent. In some aspects, at least one state associated with the LBT procedure includes at least one of an LBT pass state or an LBT fail state.

[0125] Therefore, the Tx UE can report the LBT status to the base station with reduced latency while saving processing resources. In addition, the base station receives a more accurate LBT status from the Tx UE. Therefore, the base station can more efficiently reallocate subbands on one or more side link channels and thus improve the quality and reliability of communications on these side link channels.

[0126] In some aspects, the Tx UE may attempt the LBT procedure at a nominal time slot associated with a sidelink data transmission on at least one sidelink channel in a plurality of allocated time slots. The Tx UE may determine whether the LBT procedure fails at the nominal time slot, and based on a determination that the LBT procedure fails at the nominal time slot, attempt the LBT procedure using at least one candidate transmission time slot associated with the sidelink data transmission in one or more candidate transmission time slots after the nominal time slot.

[0127] In other aspects, the Tx UE may determine whether the LBT procedure fails at a first candidate transmit time slot among one or more candidate transmit time slots, and based on the determination that the LBT procedure fails at the first candidate transmit time slot, attempt the LBT procedure using a second candidate transmit time slot associated with sidelink data transmission among one or more candidate transmit time slots after the first candidate transmit time slot.

[0128] In some aspects, the Tx UE may determine that using at least one of the one or more candidate transmit time slots, the LBT procedure did not fail and transmit sidelink data on at least one sidelink channel. In one aspect, the Tx UE may avoid attempting the LBT procedure at one or more remaining candidate transmit time slots.

[0129] In some aspects, the Tx UE may receive downlink control information from a base station that indicates an adjustment to a number of one or more candidate transmit slots for configuring grant type 2 operation based on an indication of at least one state associated with an LBT procedure used on at least one sidelink channel.

[0130] In other aspects, the Tx UE may receive a TRIV that schedules multiple resources for sidelink communication, the multiple resources having up to three allocated time slots for initial transmission and up to two retransmissions in a plurality of allocated time slots. In one aspect, the TRIV indicates a corresponding timing offset for each of the plurality of allocated time slots within a configured time period. On the other hand, one or more candidate transmission time slots follow a time instance corresponding to the timing offset indicated by the TRIV within the configured time period. In one aspect, the TRIV is included in RRC signaling for configuring a grant type 1 configuration or configuring a grant type 2 configuration. On the other hand, the TRIV is included in a DCI message for configuring a grant type 2 configuration. In some aspects, the DCI dynamically configures the number of additional time slots included in one or more candidate transmission time slots for configuring a grant activation or reactivation.

[0131] In some aspects, the Tx UE may transmit a PUCCH after a PSFCH associated with a last candidate transmit slot of a last allocated sidelink data resource indicated by the TRIV. In one aspect, the PUCCH includes an indication of at least one state associated with an LBT procedure used on at least one sidelink channel. In some aspects, each of the one or more candidate transmit slots is associated with a corresponding PSFCH opportunity.

[0132] The wireless device may include a Fig.14 The components of each box of the algorithm in the aforementioned flowchart of the process / algorithm. These components can be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium so as to be implemented by a processor, or some combination thereof.

[0133] In one configuration, an apparatus for wireless communication may include a method for performing a combined Fig.14 The aforementioned components may be one or more of the aforementioned components of the apparatus and / or the processing system of the apparatus configured to perform the functions recited by the aforementioned components. The processing system may include the TX processor 468, the RX processor 456, and the controller / processor 459. Therefore, in one configuration, the aforementioned components may be the TX processor 468, the RX processor 456, and the controller / processor 459 configured to perform the functions recited by the aforementioned components.

[0134] Fig.15 1 is a flow chart of a process 1500 for wireless communication according to various aspects of the present disclosure. Process 1500 may be performed by a wireless communication device (e.g., BS 102, 180; device 410; apparatus 1702, which may include a memory, a cellular baseband processor, and one or more components configured to perform process 1500). As shown, process 1500 includes a plurality of enumerated steps, but embodiments of process 1500 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of these enumerated steps may be omitted or performed in a different order. Optional aspects are represented by dashed lines.

[0135] At 1510, the base station may send a resource grant to the UE, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with respective time slots of the plurality of allocated time slots for additional opportunities for LBT procedures on at least one sidelink channel. The resource grant involving RRC signaling may be, for example, provided by RRC configuration component 1740 via Fig.17 In other specific implementations, resource grants involving DCI signaling can be sent by, for example, the control information configuration component 1742 via Fig.17 The sending component 1734 of the device 1702 is used to send.

[0136] At 1520, the base station may receive from the UE an indication of at least one state associated with an LBT procedure used on at least one sidelink channel. The indication of at least one state associated with the LBT procedure may be, for example, Fig.17 The receiving component 1730 of the device 1702 receives it.

[0137] In some aspects, the base station may send downlink control information to the UE that indicates an adjustment to the number of one or more candidate transmit time slots for configuring grant type 2 operation based on an indication of at least one state associated with an LBT procedure used on at least one sidelink channel.

[0138] In other aspects, the base station can transmit a TRIV scheduling a plurality of resources for sidelink communication, the plurality of resources having up to three allocated time slots for an initial transmission and up to two retransmissions among a plurality of allocated time slots.

[0139] In some aspects, the base station may receive the PUCCH after the PSFCH associated with the last candidate transmit slot of the last allocated sidelink data resource indicated by the TRIV. In one aspect, the PUCCH includes an indication of at least one state associated with the LBT procedure used on at least one sidelink channel.

[0140] The wireless device may include a Fig.15 The components of each box of the algorithm in the aforementioned flowchart of the process / algorithm. These components can be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium so as to be implemented by a processor, or some combination thereof.

[0141] In one configuration, an apparatus for wireless communication may include a method for performing a combined Fig.15 The aforementioned components may be one or more of the aforementioned components of the apparatus and / or the processing system of the apparatus configured to perform the functions recited by the aforementioned components. The processing system may include the TX processor 416, the RX processor 470, and the controller / processor 475. Therefore, in one configuration, the aforementioned components may be the TX processor 416, the RX processor 470, and the controller / processor 475 configured to perform the functions recited by the aforementioned components.

[0142] Fig.16 1600 is a diagram illustrating an example of a hardware implementation for an apparatus 1602 according to various aspects of the present disclosure. The apparatus 1602 may be a UE or other wireless device (e.g., a Tx UE or Rx UE) that communicates based on a side link. The apparatus 1602 includes a cellular baseband processor 1604 (also referred to as a modem) coupled to a cellular RF transceiver 1622 and one or more subscriber identity modules (SIM) cards 1620, an application processor 1606 coupled to a secure digital (SD) card 1608 and a screen 1610, a Bluetooth module 1612, a wireless local area network (WLAN) module 1614, a global positioning system (GPS) module 1616, and a power source 1618. The cellular baseband processor 1604 communicates with other wireless devices such as UE 164 and / or base stations 162 / 180 through the cellular RF transceiver 1622. The cellular baseband processor 1604 may include a computer-readable medium / memory. The cellular baseband processor 1604 is responsible for general processing, including executing software stored on a computer-readable medium / memory. The software, when executed by the cellular baseband processor 1604, causes the cellular baseband processor 1604 to perform the various functions described above. The computer-readable medium / memory can also be used to store data manipulated by the cellular baseband processor 1604 when executing the software. The cellular baseband processor 1604 also includes a receiving component 1630, a side link communication manager 1632, and a transmitting component 1634. The side link communication manager 1632 includes one or more components shown. The components within the side link communication manager 1632 can be stored in a computer-readable medium / memory and / or configured as hardware within the cellular baseband processor 1604. The cellular baseband processor 1604 can be a component of the device 410 or 450 and can include a memory 460 or 476 and / or at least one of the following: a TX processor 416 or 468, an RX processor 456 or 470, and a controller / processor 459 or 475. In one configuration, the apparatus 1602 may be a modem chip and include only the baseband processor 1604, and in another configuration, the apparatus 1602 may be the entire wireless device (e.g., see Figure 4 device 410 or 450) and includes additional modules of device 1602.

[0143] The communication manager 1632 includes an RRC configuration component 1640 configured to receive an RRC configuration, for example, as described in conjunction with 1410. The communication manager 1632 also includes a control information component 1642 configured to receive control information indicating a sidelink data resource for a configuration grant period. In some aspects, the control information indicates a resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within the configuration time period, wherein the plurality of resources includes a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of the plurality of allocated time slots for additional LBT opportunities on at least one sidelink channel. The communication manager 1632 also includes an SCI component 1644 that can receive input in the form of sidelink data resources from the control information component 1642 and is configured to send an SCI including a TRIV, wherein the TRIV indicates a resource allocation for scheduling a set of sidelink data resources. For example, the TRIV may schedule a plurality of resources for sidelink communications, the plurality of resources having up to three allocated time slots for initial transmission and up to two retransmissions in a plurality of allocated time slots. The SCI component 1644 is also configured to send an SCI to a second UE, wherein the SCI indicates to the second UE that each sidelink data resource is for a time slot. The SCI component 1644 is also configured to send a first-level SCI and a second-level SCI to the UE, wherein either the first-level SCI or the second-level SCI indicates the downlink control information, which indicates an adjustment to the number of the one or more candidate transmission time slots for configuring a grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel. The communication manager 1632 also includes a sidelink data component 1646, which may receive input in the form of a sidelink data resource from the control information component 1642 and is configured to communicate sidelink data with the second UE in the sidelink data resource. The communications manager 1632 also includes a confirmation component 1648 that can receive input in the form of control information from the control information component 1642 and is configured to send a confirmation of the control information, the control information including an indication of at least one state associated with an LBT procedure used on at least one side link channel, for example, as described in conjunction with 1420.

[0144] The device 1602 may include executing Fig.14 The additional components of each box of the algorithm in the preceding flowchart. Therefore, Fig.14Each block in the aforementioned flow chart of can be performed by a component, and the apparatus may include one or more of those components. These components may be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0145] In one configuration, the apparatus 1602 (and in particular, the cellular baseband processor 1604) includes means for receiving a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel for a configured time period, wherein the plurality of resources includes a plurality of allocated time slots and one or more candidate transmit time slots associated with respective time slots of the plurality of allocated time slots for additional opportunities for an LBT procedure on the at least one sidelink channel. The apparatus 1602 may also include means for sending, to the base station, an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0146] The aforementioned means may be one or more of the aforementioned components of the apparatus 1602 configured to perform the functions recited by the aforementioned means. As described above, the apparatus 1602 may include a TX processor 416 or 468, an RX processor 456 or 470, and a controller / processor 459 or 475. Therefore, in one configuration, the aforementioned means may be a TX processor 416 or 468, an RX processor 456 or 470, and a controller / processor 459 or 475, which are configured to perform the functions recited by the aforementioned means.

[0147] Fig.171700 is a diagram illustrating an example of a hardware implementation for an apparatus 1702 according to various aspects of the present disclosure. The apparatus 1702 may be a base station or other wireless device that communicates based on a downlink / uplink. The apparatus 1702 includes a cellular baseband processor 1704 (also referred to as a modem) coupled to an RF transceiver 1724, a processor 1720, and a memory 1722. The cellular baseband processor 1704 communicates with other wireless devices such as UE 174 through the RF transceiver 1724. The cellular baseband processor 1704 may include a computer-readable medium / memory. The cellular baseband processor 1704 is responsible for general processing, including executing software stored on a computer-readable medium / memory. The software, when executed by the cellular baseband processor 1704, causes the cellular baseband processor 1704 to perform the various functions described above. The computer-readable medium / memory may also be used to store data manipulated by the cellular baseband processor 1704 when executing the software. The processor 1720 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1722. The software, when executed by the processor 1720, causes the device 1702 to perform the various functions described above for any particular device. The computer-readable medium / memory 1722 can also be used to store data manipulated by the processor 1720 when executing the software. The cellular baseband processor 1704 also includes a receiving component 1730, a relay communication manager 1732, and a transmitting component 1734. The relay communication manager 1732 includes one or more components shown. The components within the relay communication manager 1732 can be stored in a computer-readable medium / memory and / or configured as hardware within the cellular baseband processor 1704. The cellular baseband processor 1704 can be a component of the device 410 and can include a memory 476 and / or at least one of the following: a TX processor 416, an RX processor 470, and a controller / processor 475. In one configuration, the apparatus 1702 may be a modem chip and include only the baseband processor 1704, and in another configuration, the apparatus 1702 may be an entire wireless device (e.g., see Figure 4 device 410), and includes additional modules of device 1702.

[0148] The communication manager 1732 includes an RRC configuration component 1740 configured to send an RRC configuration, e.g., as described in conjunction with 1510. The communication manager 1732 also includes a control information configuration component 1742 configured to configure control information indicating a resource grant, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configuration time period, wherein the plurality of resources include a plurality of allocated time slots and one or more candidate transmit time slots, the one or more candidate transmit time slots being associated with respective time slots in the plurality of allocated time slots for additional LBT opportunities, e.g., as described in conjunction with 1510. In some aspects, the control information configuration component 1742 can be configured to dynamically configure the control information via a DCI (e.g., DCI 3_0). For example, the control information configuration component 1742 can include in the DCI an adjustment to the number of one or more candidate transmit time slots for configuring a grant type 2 operation based on an indication of at least one state associated with an LBT procedure used on at least one sidelink channel. The communication manager 1732 also includes a control information sending component 1744, which can receive input in the form of sidelink data resources from the control information configuration component 1742 and is configured to send control information to the UE. The communication manager 1732 can also receive an indication of at least one state associated with the LBT procedure used on at least one sidelink channel from the UE via the receiving component 1730, for example, as described in conjunction with 1520.

[0149] The device 1702 may include executing Fig.15 The additional components of each box of the algorithm in the preceding flowchart. Therefore, Fig.15 Each block in the aforementioned flow chart of can be performed by a component, and the apparatus may include one or more of those components. These components may be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0150] In one configuration, the apparatus 1702 (and in particular, the cellular baseband processor 1704) includes means for sending a resource grant to a UE, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, the plurality of resources including a plurality of allocated time slots and one or more candidate transmit time slots associated with respective time slots of the plurality of allocated time slots for additional opportunities for an LBT procedure on the at least one sidelink channel. The apparatus 1702 may also include means for receiving, on an uplink resource, from the UE an indication of at least one state associated with an LBT procedure used on the at least one sidelink channel.

[0151] The aforementioned means may be one or more of the aforementioned components of the apparatus 1702 configured to perform the functions recited by the aforementioned means. As described above, the apparatus 1702 may include the TX processor 416, the RX processor 470, and the controller / processor 475. Therefore, in one configuration, the aforementioned means may be the TX processor 416, the RX processor 470, and the controller / processor 475 configured to perform the functions recited by the aforementioned means.

[0152] The following aspects are merely illustrative, and aspects thereof may be combined with aspects of other examples or teachings described herein, but are not limited thereto.

[0153] Aspect 1 is a method of wireless communication performed by a user equipment, the method comprising: receiving a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; and sending to the base station an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0154] In aspect 2, the method according to aspect 1 also includes: trying the LBT procedure at a nominal time slot associated with the side link data transmission on the at least one side link channel in the multiple allocated time slots; determining whether the LBT procedure fails at the nominal time slot; and based on the determination that the LBT procedure fails at the nominal time slot, trying the LBT procedure using at least one candidate transmission time slot associated with the side link data transmission in the one or more candidate transmission time slots after the nominal time slot.

[0155] In aspect 3, the method according to aspect 2 also includes: determining whether the LBT procedure fails at a first candidate transmission time slot among the one or more candidate transmission time slots; and based on the determination that the LBT procedure fails at the first candidate transmission time slot, trying the LBT procedure using a second candidate transmission time slot associated with the side link data transmission among the one or more candidate transmission time slots after the first candidate transmission time slot.

[0156] In aspect 4, the method according to any one of aspects 1 to 3 also includes: determining that the LBT procedure has not failed using at least one of the one or more candidate transmission time slots; sending side link data on the at least one side link channel; and avoiding attempting the LBT procedure at one or more remaining candidate transmission time slots.

[0157] In aspect 5, the method according to any one of aspects 1 to 4 also includes: receiving downlink control information from the base station, and the downlink control information indicates an adjustment to the number of the one or more candidate transmission time slots for configuring the grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one side link channel.

[0158] In aspect 6, the method according to any one of aspects 1 to 5 also includes: receiving the resource grant includes receiving a time resource indication value (TRIV) for scheduling the multiple resources for the side link communication, the multiple resources having up to three allocated time slots among the multiple allocated time slots for initial transmission and up to two retransmissions.

[0159] In aspect 7, the method according to aspect 6 further comprises the TRIV indicating a respective timing offset for each of the plurality of allocated time slots within the configured time period.

[0160] In aspect 8, the method according to aspect 6 further comprises: the one or more candidate transmission time slots follow a time instance corresponding to the timing offset indicated by the TRIV within the configuration time period.

[0161] In aspect 9, the method according to aspect 6 further comprises: the TRIV is included in a radio resource control (RRC) signaling for configuring a grant type 1 configuration or configuring a grant type 2 configuration.

[0162] In aspect 10, the method according to aspect 6 further comprises: the TRIV is included in a downlink control information (DCI) message for configuring a grant type 2 configuration.

[0163] In aspect 11, the method according to aspect 10 further includes: the DCI dynamically configuring the number of additional time slots included in the one or more candidate transmission time slots for configuring the grant of activation or reactivation.

[0164] In aspect 12, the method according to aspect 6 also includes: the sending includes sending a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmission time slot of the last allocated sidelink data resource indicated by the TRIV, and the PUCCH includes the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0165] In aspect 13, the method according to aspects 1 to 12 further comprises: each candidate transmission time slot of the one or more candidate transmission time slots is associated with a corresponding physical sidelink feedback channel (PSFCH) opportunity.

[0166] In aspect 14, the method according to aspects 1 to 13 further includes: the at least one side link channel is on an unlicensed band channel.

[0167] In aspect 15, the method according to aspects 1 to 14 also includes: the at least one state associated with the LBT procedure includes at least one of an LBT pass state or an LBT fail state.

[0168] Aspect 16 is a device comprising one or more processors and one or more memories storing instructions in electronic communication with the one or more processors, the instructions being executable by the one or more processors to enable the device to implement a method according to any one of Aspects 1 to 15.

[0169] Aspect 17 is a system or device, comprising components for implementing the method or device according to any one of aspects 1 to 15.

[0170] Aspect 18 is a non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors to cause the one or more processors to implement the method according to any one of aspects 1 to 15.

[0171] Aspect 19 is a method of wireless communication performed by a base station, the method comprising: sending a resource grant to a user equipment (UE), the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel within a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmission time slots, the one or more candidate transmission time slots being associated with corresponding time slots of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; and receiving from the UE an indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0172] In aspect 20, the method according to aspect 19 also includes: sending downlink control information to the UE, wherein the downlink control information indicates an adjustment to the number of the one or more candidate transmission time slots for configuring the grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one side link channel.

[0173] In aspect 21, the method according to any one of aspects 19 or 20 also includes: sending the resource grant includes sending a time resource indication value (TRIV) for scheduling the multiple resources for the side link communication, and the multiple resources have up to three allocated time slots among the multiple allocated time slots for initial transmission and up to two retransmissions.

[0174] In aspect 22, the method according to any one of aspects 19 to 21 also includes: the receiving includes receiving a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmit time slot of the last allocated sidelink data resource indicated by the TRIV, the PUCCH including the indication of the at least one state associated with the LBT procedure used on the at least one sidelink channel.

[0175] Aspect 23 is a device comprising one or more processors and one or more memories storing instructions in electronic communication with the one or more processors, the instructions being executable by the one or more processors to enable the device to implement a method according to any one of Aspects 19 to 22.

[0176] Aspect 24 is a system or apparatus, comprising components for implementing the method or apparatus according to any one of aspects 19 to 22.

[0177] Aspect 25 is a non-transitory computer-readable medium storing instructions, the instructions being executable by one or more processors to cause the one or more processors to implement the method according to any one of aspects 19 to 22.

[0178] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely an illustration of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart can be rearranged based on design preferences. In addition, some blocks can be combined or omitted. The attached method claims provide the elements of each block in a sample order, but are not meant to be limited to the specific order or hierarchy provided.

[0179] The preceding description is provided to enable any person skilled in the art to practice 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. Therefore, the claims are not intended to be limited to the aspects shown herein, but to conform to the full scope consistent with the language claims, wherein the elements mentioned in the singular are not intended to mean "one and only one", unless specifically so stated, but "one or more". The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or having an advantage over other aspects. Unless otherwise specified, 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 "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple A, multiple B, or multiple 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 "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are or will later become known to a person of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, regardless of whether such disclosure is explicitly recited in the claims, nothing disclosed herein is intended to be disclosed to the public. Words such as "module," "mechanism," "element," "device," etc. cannot replace the word "component." Therefore, no claim element will be understood to be a part plus function unless the element is expressly stated using the phrase "component for..."

Claims

1. A method of wireless communication performed by a user equipment (UE), the method comprising: receiving a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communications on at least one sidelink channel for a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmit time slots associated with respective ones of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; as well as An indication of at least one status associated with the LBT procedure used on the at least one sidelink channel is sent to the base station.

2. The method according to claim 1, further comprising: attempting the LBT procedure at a nominal time slot in the plurality of allocated time slots associated with a sidelink data transmission on the at least one sidelink channel; determining whether the LBT procedure fails at the nominal time slot; as well as Based on the determination that the LBT procedure failed at the nominal time slot, the LBT procedure is attempted using at least one candidate transmission time slot associated with the sidelink data transmission from among the one or more candidate transmission time slots following the nominal time slot.

3. The method according to claim 2, further comprising: determining whether the LBT procedure fails at a first candidate transmit time slot of the one or more candidate transmit time slots; as well as Based on the determination that the LBT procedure failed at the first candidate transmit time slot, the LBT procedure is attempted using a second candidate transmit time slot associated with the sidelink data transmission in the one or more candidate transmit time slots after the first candidate transmit time slot.

4. The method according to claim 1, further comprising: determining that the LBT procedure has not failed using at least one candidate transmit time slot of the one or more candidate transmit time slots; transmitting sidelink data on the at least one sidelink channel; as well as Avoid attempting the LBT procedure at one or more of the remaining candidate transmit time slots.

5. The method according to claim 1, further comprising: Downlink control information is received from the base station, the downlink control information indicating an adjustment to a number of the one or more candidate transmit time slots for configuring grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

6. The method of claim 1 , wherein receiving the resource grant comprises receiving a time resource indication value (TRIV) for scheduling the plurality of resources for the sidelink communication, the plurality of resources having up to three allocated time slots of the plurality of allocated time slots for an initial transmission and up to two retransmissions.

7. The method of claim 6, wherein the TRIV indicates a respective timing offset for each of the plurality of allocated time slots within the configured time period.

8. The method of claim 6, wherein the one or more candidate transmit time slots follow a time instance within the configured time period corresponding to a timing offset indicated by the TRIV.

9. The method of claim 6, wherein the TRIV is included in a radio resource control (RRC) signaling for configuring a grant type 1 configuration or configuring a grant type 2 configuration.

10. The method of claim 6, wherein the TRIV is included in a downlink control information (DCI) message for configuring a grant type 2 configuration. 11 . The method according to claim 10 , wherein the DCI dynamically configures the number of additional time slots included in the one or more candidate transmission time slots for configuring the grant of activation or reactivation.

12. A method according to claim 6, wherein the sending includes sending a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmission time slot of the last allocated sidelink data resource indicated by the TRIV, and the PUCCH includes the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

13. The method of claim 1, wherein each of the one or more candidate transmit time slots is associated with a corresponding physical sidelink feedback channel (PSFCH) opportunity.

14. The method of claim 1, wherein the at least one sidelink channel is on an unlicensed band channel.

15. The method of claim 1, wherein the at least one state associated with the LBT procedure comprises at least one of an LBT pass state or an LBT fail state.

16. A method of wireless communication performed by a base station, the method comprising: sending a resource grant to a user equipment (UE), the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel for a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmit time slots associated with respective ones of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; as well as An indication of at least one status associated with the LBT procedure used on the at least one sidelink channel is received from the UE.

17. The method according to claim 16, further comprising: Downlink control information is sent to the UE, and the downlink control information indicates an adjustment to the number of the one or more candidate transmit time slots for configuring grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

18. The method of claim 16, wherein sending the resource grant comprises sending a time resource indication value (TRIV) for scheduling the plurality of resources for the sidelink communication, the plurality of resources having up to three allocated time slots of the plurality of allocated time slots for an initial transmission and up to two retransmissions.

19. A method according to claim 18, wherein the receiving includes receiving a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmit time slot of the last allocated sidelink data resource indicated by the TRIV, and the PUCCH includes the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

20. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: at least one processor; and A memory coupled to the at least one processor, the memory storing code executable by the at least one processor to cause the apparatus to: receiving a resource grant from a base station, the resource grant indicating a plurality of resources for sidelink communications on at least one sidelink channel for a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmit time slots associated with respective ones of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; as well as An indication of at least one status associated with the LBT procedure used on the at least one sidelink channel is sent to the base station.

21. The apparatus of claim 20, wherein the code executed by the at least one processor further causes the apparatus to: attempting the LBT procedure at a nominal time slot in the plurality of allocated time slots associated with a sidelink data transmission on the at least one sidelink channel; determining whether the LBT procedure fails at the nominal time slot; as well as Based on the determination that the LBT procedure failed at the nominal time slot, the LBT procedure is attempted using at least one candidate transmission time slot associated with the sidelink data transmission from among the one or more candidate transmission time slots following the nominal time slot.

22. The apparatus of claim 21, wherein the code executed by the at least one processor further causes the apparatus to: determining whether the LBT procedure fails at a first candidate transmit time slot of the one or more candidate transmit time slots; and Based on the determination that the LBT procedure failed at the first candidate transmit time slot, the LBT procedure is attempted using a second candidate transmit time slot associated with the sidelink data transmission in the one or more candidate transmit time slots after the first candidate transmit time slot.

23. The apparatus of claim 20, wherein the code executed by the at least one processor further causes the apparatus to: determining that the LBT procedure has not failed using at least one candidate transmit time slot of the one or more candidate transmit time slots; transmitting sidelink data on the at least one sidelink channel; and Avoid attempting the LBT procedure at one or more of the remaining candidate transmit time slots.

24. An apparatus according to claim 20, wherein the code executed by the at least one processor further causes the apparatus to: receive downlink control information from the base station, the downlink control information indicating an adjustment to the number of the one or more candidate transmit time slots for configuring grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one side link channel.

25. An apparatus according to claim 20, wherein the code executed by the at least one processor causing the apparatus to receive the resource grant further causes the apparatus to: receive a time resource indication value (TRIV) for scheduling the plurality of resources for the sidelink communication, the plurality of resources having up to three allocated time slots of the plurality of allocated time slots for an initial transmission and up to two retransmissions.

26. An apparatus according to claim 25, wherein the code executed by the at least one processor to cause the apparatus to send further causes the apparatus to: send a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmit time slot of the last allocated sidelink data resource indicated by the TRIV, the PUCCH including the indication of the at least one state associated with the LBT procedure used on the at least one sidelink channel.

27. An apparatus for wireless communication at a base station, the apparatus comprising: at least one processor; and A memory coupled to the at least one processor, the memory storing code executable by the at least one processor to cause the apparatus to: sending a resource grant to a user equipment (UE), the resource grant indicating a plurality of resources for sidelink communication on at least one sidelink channel for a configured time period, the plurality of resources comprising a plurality of allocated time slots and one or more candidate transmit time slots associated with respective ones of the plurality of allocated time slots for additional opportunities for a listen-before-talk (LBT) procedure on the at least one sidelink channel; as well as An indication of at least one status associated with the LBT procedure used on the at least one sidelink channel is received from the UE.

28. An apparatus according to claim 27, wherein the code executed by the at least one processor further causes the apparatus to: send downlink control information to the UE, the downlink control information indicating an adjustment to the number of the one or more candidate transmit time slots for configuring grant type 2 operation based on the indication of at least one state associated with the LBT procedure used on the at least one sidelink channel.

29. An apparatus according to claim 27, wherein the code executed by the at least one processor causing the apparatus to send the resource grant further causes the apparatus to: send a time resource indication value (TRIV) scheduling the plurality of resources for the sidelink communication, the plurality of resources having up to three allocated time slots of the plurality of allocated time slots for an initial transmission and up to two retransmissions.

30. An apparatus according to claim 29, wherein the code executed by the at least one processor to cause the apparatus to receive further causes the apparatus to: receive a physical uplink control channel (PUCCH) after a physical sidelink feedback channel (PSFCH) associated with a last candidate transmit time slot of the last allocated sidelink data resource indicated by the TRIV, the PUCCH including the indication of the at least one state associated with the LBT procedure used on the at least one sidelink channel.

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