CN118042609A - Side-link transmission method, apparatus and computer readable medium - Google Patents

Abstract

The UE obtains COT occupying a group of resources on SL in the unlicensed spectrum through the channel access procedure. The UE determines whether the FDM transmission scheme is used for SL transmission on the side link in the COT. The UE selects the CPE start position before including the initial symbol for the SL transmission. When the FDM transmission scheme is adopted, the UE selects a default CPE start position as the CPE start position. When the FDM transmission scheme is not employed, the UE selects a subset from the set of all candidate CPE start positions based on the L1 priority of the SL transmission and randomly selects a CPE start position from the subset. The UE transmits the CPE at the selected CPE start location and performs SL transmission after transmitting the CPE.

Description

Side-link transmission method, apparatus and computer readable medium

Technical Field

The present invention relates generally to communication systems and, more particularly, to techniques for transmitting cyclic prefix extensions (cyclic prefix extension, CPE) on side links on unlicensed spectrum.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. A typical wireless communication system may employ multiple-access (multiple-access) techniques that are capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access techniques include code division multiple access (Code Division Multiple Access, CDMA) systems, time division multiple access (time division multiple access, TDMA) systems, frequency division multiple access (frequency division multiple access, FDMA) systems, orthogonal frequency division multiple access (Orthogonal Frequency Division Multiple Access, OFDMA) systems, single-carrier frequency division multiple access (single-carrier frequency division multiple access, SC-FDMA) systems, and time division synchronous code division multiple access (time division synchronous code division multiple access, TD-SCDMA) systems.

These multiple access techniques have been applied in various telecommunications standards to provide a generic protocol that enables different wireless devices to communicate at the city level, country level, regional level, and even the global level. One example telecommunications standard is the fifth generation (fifth G) New Radio (NR). The 5G NR is part of the continuous mobile broadband evolution promulgated by the third generation partnership project (Third Generation Partnership Project,3 GPP) and can meet new demands related to latency, reliability, security, scalability (e.g., with the internet of things (Internet of things, ioT)), and other demands. Some aspects of 5G NR may be based on the fourth generation (4th Generation,4G) long term evolution (long term evolution, LTE) standard. Further improvements are needed for the 5G NR technology. These improvements may also be applicable to other multiple access techniques and telecommunication standards employing these techniques.

Disclosure of Invention

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate 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 the more detailed description that is presented later.

In one aspect of the invention, a method, computer-readable medium, and apparatus are provided. The apparatus may be a User Equipment (UE). The UE obtains a channel occupancy time (channel occupancy time, COT) for occupying a set of resources on a Sidelink (SL) in the unlicensed spectrum through a channel access procedure. The UE determines whether a frequency division multiplexed transmission (frequency division multiplexing, FDM) scheme is used for SL transmission on the side link in the COT. The UE selects the CPE start position before including the initial symbol for the SL transmission. When the FDM transmission scheme is adopted, the UE selects a default CPE start position as the CPE start position. When the FDM transmission scheme is not employed, the UE selects a subset from the set of all candidate CPE start positions based on the layer 1 (L1) priority of the SL transmission and randomly selects a CPE start position from the subset. The UE sends the CPE at the selected CPE start location. The UE performs SL transmission after transmitting the CPE.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The detailed description and the figures describe certain illustrative features of one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed and the description is intended to include all such aspects and their equivalents.

Drawings

Fig. 1 is a schematic diagram illustrating an example of a wireless communication system and an access network.

Fig. 2 is a schematic diagram illustrating a base station communicating with a UE in an access network.

Fig. 3 illustrates an example logical structure of a distributed access network.

Fig. 4 illustrates an example physical structure of a distributed access network.

Fig. 5 is a diagram showing an example of a Downlink (DL) -centered subframe.

Fig. 6 is a diagram showing an example of an Uplink (UL) -centered subframe.

Fig. 7 is a schematic diagram illustrating a CPE start position.

Fig. 8 is a schematic diagram illustrating CPE selection.

Fig. 9 is a flow chart illustrating transmitting CPE.

Detailed Description

The embodiments set forth below in connection with the figures are intended as descriptions of various configurations and are not intended to represent the only configurations in which the concepts described herein may be implemented. The present embodiments include specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to one skilled in the art that the concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

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

By way of example, an element, or any portion of an element, or any combination of elements, may be implemented as a "processing system" comprising one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (graphics processing unit, GPU), central processing units (central processing unit, CPU), application processors, digital signal processors (DIGITAL SIGNAL processor, DSP), reduced instruction set computing (reduced instruction set computing, RISC) processors, systems on a chip (systems on a chip, soC), baseband processors, field programmable gate arrays (field programmable GATE ARRAY, FPGA), programmable logic devices (programmable logic device, PLD), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions of all aspects of the invention. One or more processors in a processing system may execute software. Software should be construed broadly as instructions, instruction sets, code segments, program code, programs, subroutines, software components, applications, software packages, routines, subroutines, objects, executable files, threads of execution, programs, functions, etc., whether referred to as software, firmware, intermedial software, microcode, hardware description language, or otherwise.

Thus, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, these functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer readable media includes computer storage media. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, computer-readable media can comprise random-access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (ELECTRICALLY ERASABLE PROGRAMMABLE ROM), optical disk storage, magnetic disk storage, other magnetic storage devices, and combinations of the above, or any other medium that can be used to store computer-executable code in the form of computer-accessible instructions or data structures.

Fig. 1 is a schematic diagram illustrating an example of a wireless communication system and an access network 100. A wireless communication system, which may also be referred to as a Wireless Wide Area Network (WWAN), includes a base station 102, a UE 104, and an evolved packet core (Evolved Packet Core, EPC) 160, and another core network 190 (e.g., a 5G core (5 gc)). The base station 102 includes a macro cell (macro cell) (high power cell base station) and/or a small cell (SMALL CELL) (low power cell base station). The macrocell includes a base station. The small cells include femto cells (femtocells), pico cells (picocell), and micro cells (microcell).

A base station 102 configured for 4G LTE, collectively referred to as an evolved universal mobile telecommunications system (Evolved Universal Mobile Telecommunications System, UMTS) terrestrial radio access network (UMTS terrestrial radio access network, E-UTRAN), is connected to the EPC 160 through a backhaul link 132 (e.g., S1 interface). A base station 102 configured for 5G NR, collectively referred to as a next generation radio access network (Next Generation radio access network, NG-RAN), is connected to a core network 190 through a backhaul link 184. Base station 102 may perform, among other functions, one or more of the following: user data transfer, radio channel encryption and decryption, integrity protection, header compression, mobile 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 (radio access network, RAN) sharing, multimedia broadcast multicast services (multimedia broadcast multicast service, MBMS), user (subscore) and device tracking, RAN information management (RAN information management, RIM), paging, positioning, and alert messaging. Base stations 102 may communicate with each other directly or indirectly (e.g., through EPC 160 or core network 190) over backhaul link 134 (e.g., an X2 interface). The backhaul link 134 may be wired or wireless.

The base station 102 may communicate wirelessly with the UE 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102' may have a coverage area 110', the coverage area 110' overlapping with the coverage areas 110 of one or more macro base stations 102. A network comprising both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a home evolved node B (home evolved node B, heNB), where the HeNB may provide services to a restricted group called a closed subscriber group (closed subscriber group, CSG). The communication link 120 between the base station 102 and the UE 104 may include UL (also may be referred to as a reverse link) transmissions from the UE 104 to the base station 102 and/or DL (also may be referred to as a forward link) transmissions from the base station 102 to the UE 104. Communication link 120 may use MIMO antenna techniques including spatial multiplexing, beamforming, and/or transmit diversity. The communication link may be through one or more carriers. The base station 102/UE 104 may use a spectrum up to Y megahertz (e.g., 5, 10, 15, 20, 100 megahertz) bandwidth per carrier, where the spectrum is allocated in carrier aggregation up to Yx megahertz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers for DL and UL may be asymmetric (e.g., DL may be allocated more or less carriers than 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 (PRIMARY CELL, PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PHYSICAL SIDELINK broadcast channel, PSBCH), a physical sidelink discovery channel (PHYSICAL SIDELINK discovery channel, PSDCH), a physical sidelink shared channel (PHYSICAL SIDELINK SHARED CHANNEL, PSSCH), and a physical sidelink control channel (PHYSICAL SIDELINK control channel, PSCCH). D2D communication may be through various wireless D2D communication systems, e.g., FLASHLINQ, WIMEDIA, bluetooth, zigBee, wi-Fi based on the IEEE 802.11 standard, LTE, NR, etc.

The wireless communication system further includes a wireless fidelity (WIRELESS FIDELITY, wi-Fi) Access Point (AP) 150 that communicates with a Wi-Fi Station (STA) 152 in a 5 gigahertz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, STA 152/AP 150 may perform a clear channel assessment (CLEAR CHANNEL ASSESSMENT, CCA) to determine whether a channel is available prior to communicating.

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

Base station 102, whether a small cell 102' or a large cell (e.g., macro base station), may include an eNB, a gndeb (gNB), or other type of base station. Some base stations, such as the gNB (or gNodeB) 180, may operate at millimeter wave (MILLIMETER WAVE, mmW) frequencies and/or near mmW frequencies to communicate with the 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. The extremely high Frequency (extremely high Frequency, EHF) is part of the Radio Frequency (RF) in the electromagnetic spectrum. EHF has a wavelength in the range of 30 gigahertz to 300 gigahertz and between 1 millimeter and 10 millimeters. The radio waves in this band may be referred to as millimeter waves. The near mmW may extend down to 3 gigahertz frequencies with a wavelength of 100 millimeters. The ultra-high frequency (super high frequency, SHF) band ranges from 3 gigahertz to 30 gigahertz, also known as a centimeter wave. Communications using mmW/near mmW RF bands have extremely high path loss and short range. Beamforming 182 may be used between the base station 180 and the UE 104 to compensate for extremely high path loss and shorter range.

The base station 180 may transmit the beamformed signals to the UE 104 in one or more transmit directions 108 a. The UE 104 may receive the beamformed signals from the base station 180 in one or more receive directions 108 b. The UE 104 may also transmit the beamformed signals in one or more transmit directions to the base station 180. The base station 180 may receive the beamformed signals from the UEs 104 in one or more directions. The base stations 180/UEs 104 may perform beam training to determine the best reception and transmission direction for each of the base stations 180/UEs 104. The transmission and reception directions of the base station 180 may be the same or different. The transmit and receive directions of the UE 104 may be the same or different.

EPC 160 includes Mobility MANAGEMENT ENTITY (MME) 162, other MMEs 164, serving gateway (SERVING GATEWAY) 166, MBMS Gateway (GW) 168, broadcast multicast service center (broadcast multicast SERVICE CENTER, BM-SC) 170, and Packet Data Network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (Home Subscriber Server, HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Generally, MME 162 provides bearer and connection management. All user internet protocol (Internet protocol, IP) packets pass through the serving gateway 166, which serving gateway 166 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 BM-SC 170 connect to a PDN 176. The PDN 176 may include the internet, an intranet, an IP multimedia subsystem (IP multimedia subsystem, IMS), a packet-switched streaming service (PS STREAMING SERVICE, PSS), and/or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may be used as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services in a public land mobile network (public land mobile network, PLMN), and may be used to schedule MBMS transmissions. The MBMS GW 168 may be used to allocate MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (multicast broadcast single frequency network, MBSFN) area broadcasting a particular service and is responsible for session management (start/stop) and collecting evolved MBMS (eMBMS) related payment information.

The core network 190 includes access and mobility management functions (ACCESS AND Mobility Management Function, AMF) 192, other AMFs 193, location management functions (location management function, LMF) 198, session management functions (Session Management Function, SMF) 194, user plane functions (User Plane Function, UPF) 195.AMF 192 may communicate with Unified data management (Unified DATA MANAGEMENT, UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. In general, SMF 194 provides QoS flows and session management. All user internet protocol (Internet protocol, IP) datagrams are transmitted over the UPF 195. The UPF 195 provides UE IP address assignment as well as other functions. The UPF 195 is connected to an IP service 197. The IP services 197 may include the internet, an intranet, an IP multimedia subsystem (IP Multimedia Subsystem, IMS), PS streaming services, and/or other IP services.

A base station may also be called a gNB, a Node B, an evolved Node B (eNB), an AP, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a Basic SERVICE SET (BSS), an Extended SERVICE SET (ESS), or other suitable terminology. The base station 102 provides the UE 104 with an AP to the EPC 160. Examples of UEs 104 include a mobile phone, a smart phone, a session initiation protocol (session initiation protocol) phone, a notebook, a Personal Digital Assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, an automobile, an ammeter, an air pump, an oven, or any other similarly functioning device. Some UEs 104 may also be referred to as IoT devices (e.g., parking timers, air pumps, ovens, automobiles, etc.). The UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, or other suitable terminology.

Although the invention may relate to 5G NR, the invention may be applicable to other similar fields, such as LTE, LTE-A, CDMA, global system for mobile communications (Global System for Mobile communications, GSM) or other wireless/radio access technologies.

Fig. 2 is a block diagram of a base station 210 in communication with a UE 250 in an access network. In DL, the controller/processor 275 may be provided with IP packets from the EPC 160. Controller/processor 275 implements layer 3 and layer 2 functions. Layer 3 includes a radio resource control (radio resource control, RRC) layer, and layer 2 includes a packet data convergence protocol (PACKET DATA convergence protocol, PDCP) layer, a radio link control (radio link control, RLC) layer, and a medium access control (medium access control, MAC) layer. The controller/processor 275 provides RRC layer functions, PDCP layer functions, RLC layer functions, and MAC layer functions, wherein the RRC layer functions are associated with system information (e.g., master information block (master information block, MIB), system information block (systeminformation block, SIB)) broadcast, RRC connection control (e.g., RRC connection paging, RRC connection setup, RRC connection modification, and RRC connection release), inter-radio access technology (Radio Access Technology, RAT) mobility, and measurement configuration for UE measurement reporting; wherein the PDCP layer function is associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; wherein RLC layer functions are associated with delivery of upper layer packet data units (PACKET DATA units, PDUs), error correction by automatic retransmission request (automatic repeat request, ARQ), concatenation, segmentation and reassembly of RLC service data units (SERVICE DATA units, SDUs), re-segmentation of RLC data PDUs and re-ordering of RLC data PDUs; wherein the MAC layer function is associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to Transport Blocks (TBs), de-multiplexing of TB to MAC SDUs, scheduling information reporting, error correction by hybrid automatic repeat request (hybrid automatic repeat request, HARQ), priority handling and logical channel priority.

A Transmit (TX) processor 216 and a Receive (RX) processor 270 implement layer 1 functions associated with various signal processing functions. Layer 1 (including physical, PHY) layer may include error detection on a transport channel, forward error correction (forward error correction, FEC) encoding/decoding of a transport channel, interleaving (interleaving), rate matching, mapping on a physical channel, modulation/demodulation of a physical channel, and MIMO antenna processing. TX processor 216 processes a mapping to a signal constellation (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-quadrature amplitude modulation, M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) subcarriers, multiplexed with reference signals (e.g., pilots) in the time and/or frequency domain, and then combined together using an inverse fast fourier transform (INVERSE FAST Fourier transform, IFFT) to produce a physical channel carrying the time domain OFDM symbol stream. The OFDM streams are spatially precoded to produce a plurality of spatial streams. The channel estimates from the channel estimator 274 may be used to determine coding and modulation schemes, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel state feedback transmitted by the UE 250. Each spatial stream may then be provided to a different antenna 220 via a separate transceiver 218 (transceiver 218 includes RX and TX). Each transceiver 218 may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 250, each transceiver 254 (transceiver 254 includes RX and TX) receives signals through its respective antenna 252. Each transceiver 254 recovers information modulated onto an RF carrier and provides the information to the RX processor 256. TX processor 268 and RX processor 256 perform layer 1 functions associated with various signal processing functions. RX processor 256 may perform spatial processing on the information to recover any spatial streams that are to be transmitted to UE 250. If there are multiple spatial streams to send to UE 250, rx processor 256 combines the multiple spatial streams into a single OFDM symbol stream. The RX processor 256 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast fourier transform (fast Fourier transform, FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the signal constellation most likely to be transmitted by base station 210. These soft decisions may be based on channel estimates computed by channel estimator 258. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 210 on the physical channel. The data and control signals are then provided to a controller/processor 259 that performs layer 3 and layer 2 functions.

The controller/processor 259 can be associated with a memory 260 that stores program codes and data. Memory 260 may be referred to as a computer-readable medium. In the UL, the controller/processor 259 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 259 is also responsible for error detection using an Acknowledgement (ACK) and/or negative acknowledgement (Negative Acknowledgement, NACK) protocol to support HARQ operations.

Similar to the description of the functions of DL transmission by the base station 210, the controller/processor 259 provides RRC layer functions, PDCP layer functions, RLC layer functions, and MAC layer functions, wherein the RRC layer functions are associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reports; PDCP layer functions are associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functions are associated with delivery of upper layer PDUs, error correction by ARQ, concatenation, segmentation and reassembly of RLC SDUs, and reordering of RLC data PDUs; the MAC layer function is associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to TBs, demultiplexing of TB to MAC SDUs, scheduling information reporting, error correction by HARQ, priority handling, and logical channel priority.

The channel estimate derived by channel estimator 258, which is derived from the reference signal or feedback transmitted by base station 210, may be used by TX processor 268 to select an appropriate coding and modulation scheme, and to facilitate spatial processing. The spatial streams generated by TX processor 268 may be provided to different antennas 252 via separate transceivers 254. Each transceiver 254 may modulate an RF carrier with a respective spatial stream for transmission. The manner in which the base station 210 processes UL transmissions is similar to the manner in which the receiver function at the UE 250 is described. Each transceiver 218 receives signals through a respective antenna 220. Each transceiver 218 recovers information modulated onto an RF carrier and provides the information to the RX processor 270.

The controller/processor 275 may be associated with a memory 276 that stores program codes and data. Memory 276 may be referred to as a computer-readable medium. In the UL, the controller/processor 275 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 250. IP packets from controller/processor 275 may be provided to EPC 160. The controller/processor 275 is also responsible for error detection using ACK and/or NACK protocols to support HARQ operations.

NR refers to a radio configured to operate according to a new air interface (e.g., other than an OFDMA-based air interface) or a fixed transport layer (e.g., IP). NR may use OFDM with Cyclic Prefix (CP) in UL and DL and include support for half-duplex operation using time division duplex (Time Division Duplexing, TDD). NR may include critical tasks for enhanced mobile broadband (enhanced mobile broadband, eMBB) services over a wide bandwidth (e.g., over 80 megahertz), mmW for high carrier frequencies (e.g., 60 gigahertz), bulk MTC (MASSIVE MTC, MMTC) for non-backward compatible Machine Type Communication (MTC) technology, and/or for Ultra-reliable low latency Communication (Ultra-Reliable Low Latency Communication, URLLC) services.

A single component carrier with a bandwidth of 100 mhz may be supported. In one example, an NR Resource Block (RB) may span 12 subcarriers with a subcarrier bandwidth of 60 khz, a duration of 0.125 ms, or a subcarrier bandwidth of 15 khz, a duration of 0.5 ms. Each radio frame may include 20 or 80 subframes (or NR slots) of length 10 milliseconds. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission, and the link direction of each subframe may be dynamically switched. Each subframe may include DL/UL data and DL/UL control data. UL and DL subframes of NR may be described in detail in fig. 5 and 6 below.

The NR RAN may include a Central Unit (CU) and a Distributed Unit (DU). An NR Base Station (BS) (e.g., gNB, 5G Node B, transmission reception point (transmission reception point, TRP), AP) may correspond to one or more BSs. The NR cells may be configured as access cells (ACCESS CELL, ACell) or data only cells (DCell). For example, the RAN (e.g., CU or DU) may configure the cell. The DCell may be a cell for carrier aggregation or dual connectivity and is not used for initial access, cell selection/reselection or handover. In some cases, dcell does not send a synchronization signal (synchronization signal, SS). In some cases, the DCell transmits the SS. The NR BS may transmit a DL signal indicating a cell type to the UE. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine an NR BS based on the indicated cell type to consider for cell selection, access, handover, and/or measurement.

Fig. 3 illustrates an example logical structure of a distributed RAN 300 in accordance with aspects of the present invention. The 5G access node 306 includes an access node controller (access node controller, ANC) 302. The ANC may be a CU of the distributed RAN 300. The backhaul interface to the next generation core network (next generation core network, NG-CN) 304 may terminate at the ANC. The backhaul interface to the neighboring next generation access node (next generation access node, NG-AN) may terminate at the ANC. ANC includes one or more TRP 308 (which may also be referred to as BS, NR BS, node B, 5G NB, AP, or some other terminology). As described above, TRP may be used interchangeably with "cell".

TRP 308 may be a DU. TRP may be connected to one ANC (ANC 302) or more than one ANC (not shown). For example, for RAN sharing, service radio (radio AS A SERVICE, raaS), and service specific ANC deployments, TRP may be connected to more than one ANC. The TRP includes one or more antenna ports. TRP may be configured to serve traffic to the UE independently (e.g., dynamically selected) or jointly (e.g., jointly transmitted).

The local structure of the distributed RAN 300 may be used to describe the fronthaul (fronthaul) definitions. Structures supporting a forward-drive solution across different deployment types may be defined. For example, the structure may be based on transmit network performance (e.g., bandwidth, latency, and/or jitter). The structure may share features and/or components with LTE. According to various aspects, NG-AN 310 may support dual connectivity with NR. NG-AN may share common preambles for LTE and NR.

The structure may enable collaboration between TRP 308. For example, collaboration may be within the TRP and/or across TRP presets via ANC 302. According to various aspects, an interface between TRPs may not be required/present.

According to various aspects, dynamic configuration of the split logic functions may exist within the distributed RAN 300 architecture. The PDCP, RLC, MAC protocol may be adaptively placed in ANC or TRP.

Fig. 4 illustrates an example physical structure of a distributed RAN 400 in accordance with aspects of the present invention. The centralized core network element (centralized core network unit, C-CU) 402 may assume core network functions. The C-CUs may be deployed centrally. The C-CU function may tear down (e.g., to advanced wireless services (ADVANCED WIRELESS SERVICE, AWS)) to handle peak capacity. The centralized RAN unit (centralized RAN unit, C-RU) 404 may assume one or more ANC functions. Alternatively, the C-RU may assume core network functions locally. The C-RUs may be distributed. The C-RU may be closer to the network edge. The DU 406 may entail one or more TRPs. The DUs may be located at the network edge with RF functionality.

Fig. 5 is a diagram 500 illustrating an example of DL-centric sub-frames. The DL-centric sub-frame comprises a control portion 502. The control portion 502 may exist in an initial or beginning portion of a DL-centric sub-frame. The control portion 502 includes various scheduling information and/or control information corresponding to portions of the DL-centric sub-frame. In some configurations, the control portion 502 may be a physical downlink control channel (physical downlink control channel, PDCCH), as shown in fig. 5. The DL-centric sub-frame also includes a DL data portion 504.DL data portion 504 is sometimes referred to as the payload of a DL-centric sub-frame. The DL data portion 504 includes communication resources for communicating from a scheduling entity (e.g., UE or BS) to a subordinate entity (e.g., UE). In some configurations, DL data portion 504 may be a physical downlink shared channel (physical downlink SHARED CHANNEL, PDSCH).

DL-centric sub-frames also include a common UL portion 506. The common UL portion 506 is sometimes referred to as a UL burst, a common UL burst, and/or various other suitable terms. The common UL portion 506 includes feedback information corresponding to various other portions of the DL-centric sub-frame. For example, the common UL portion 506 includes feedback information corresponding to the control portion 502. Non-limiting examples of feedback information include ACK signals, NACK signals, HARQ indications, and/or various other suitable types of information. The common UL portion 506 includes additional or alternative information, such as information related to Random Access Channel (RACH) procedures, scheduling requests (scheduling request, SR), and various other suitable types of information.

As shown in fig. 5, the end of DL data portion 504 may be separated in time from the beginning of common UL portion 506. This time separation may sometimes be referred to as a gap, guard period (guard interval), guard interval (guard interval), and/or other suitable terminology. The separation provides time for a handoff from DL communication (e.g., a receive operation of a subordinate entity (e.g., UE)) to UL communication (e.g., a transmission of the subordinate entity (e.g., UE)). Those skilled in the art will appreciate that the above is merely an example of DL-centric subframes and that alternative structures with similar features are possible without necessarily offsetting the aspects described herein.

Fig. 6 is a diagram 600 illustrating an example of UL-centric sub-frames. The UL-centric sub-frame comprises a control portion 602. The control portion 602 may be present in an initial or beginning portion of a UL-centric subframe. The control portion 602 of fig. 6 may be similar to the control portion 502 described with reference to fig. 5. The UL-centric sub-frame also includes UL data portion 604.UL data portion 604 may sometimes be referred to as the payload of a UL-centric subframe. The UL portion may refer to communication resources for communicating from a subordinate entity (e.g., UE) to a scheduling entity (e.g., UE or BS). In some configurations, the control portion 602 may be a PDCCH.

As shown in fig. 6, the end of the control portion 602 may be separated in time from the beginning of the common UL data portion 604. This time separation may sometimes be referred to as an interval, a guard period, a guard interval, and/or other suitable terminology. The separation provides time for a handoff from DL communication (e.g., a receive operation of a scheduling entity) to UL communication (e.g., a transmission of a scheduling entity). UL-centric sub-frames also include a common UL portion 606. The common UL portion 606 of fig. 6 may be similar to the common UL portion 606 described with reference to fig. 6. The common UL portion 606 may additionally or alternatively include information regarding channel quality indications (channel quality indicator, CQI), SRS, and various other suitable types of information. Those skilled in the art will appreciate that the above is merely an example of DL-centric subframes and that alternative structures with similar features are possible without necessarily offsetting the aspects described herein.

In some cases, two or more subordinate entities (e.g., UEs) may communicate with each other using side-downlink signals. Practical applications for such side-link communications include public safety, proximity services, UE-To-network relay, vehicle-To-Vehicle (V2V) communications, internet of everything (Internet of Everything, ioE) communications, ioT communications, mission critical grids (mission-CRITICAL MESH), and/or various other suitable applications. In general, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE 1) to another subordinate entity (e.g., UE 2) without the need to relay the communication through a scheduling entity (e.g., UE or BS), even though the scheduling entity may be used for scheduling and/or control purposes. In some examples, the sidelink signals may communicate using licensed spectrum (as opposed to wireless local area networks, which typically use unlicensed spectrum).

For transmission on the side-uplink (SL over unlicensed spectrum, SL-U) on the unlicensed spectrum, the UE performs a listen-before-transmit (LBT) procedure before transmission. After a successful channel access procedure (e.g., type 1 channel access), the UE may occupy the channel for a period of time, which is the Channel Occupancy Time (COT). There is a gap between the successful channel access procedure and the future COT start time. During this interval, other systems (e.g., wiFi) may perform carrier sensing and begin transmitting during the interval, as the interval requirements of these systems may be less than the requirements of the side-links. Thus, once transmissions on the side links begin during the COT, collisions may occur.

A Cyclic Prefix (CP) is added at the beginning of each OFDM symbol to mitigate inter-symbol interference. CPE extends the CP duration prior to OFDM symbol transmission. CPE may be used prior to PSCCH/PSSCH transmission on the side links to occupy the channel earlier. This helps to obtain channel access, especially beyond COT. CPE is an additional waveform preceding the regular CP of an OFDM symbol, effectively extending the CP duration. This is done by starting transmission earlier than the normal OFDM symbol start time. By using CPE in the interval before the COT, the UE keeps the channel occupied until the COT starts. This may prevent other systems from accessing the channel in the interval.

CPE of a signal (e.g., a control signal or a data signal) may be performed at a single (default) starting location and/or at a location selected from among a plurality of starting locations within a symbol preceding a first symbol (i.e., OFDM symbol period) containing the signal. The number of CPE start positions within a symbol and the interval between two consecutive CPE start positions may be configured (pre-configured or configured) at the transmitting UE and/or signaled to the transmitting UE.

Fig. 7 is a schematic diagram 700 showing a CPE start position, wherein the maximum length of the CPE is one symbol. In one example, slots 722, 724 are two consecutive slots according to the 15KHz SCS. Each of the slots 722, 724 includes 14 symbols. The first CPE start position may be set at 16us after the start position/leading boundary of the symbol (last symbol carrying the last transmitted traffic) and the other CPE start positions may be set at a spacing from the previous CPE start position, e.g. the spacing may be 9us.

In this example, OFDM symbol #0 of slot 724 containing PSCCH/PSSCH may use CPE. In symbol #13 of slot 722, an exemplary plurality of CPE start positions t1-t7 are 16us, 25us, 34 us..70 us, respectively.

In another example, the slots 732, 734 are two consecutive slots according to the SCS of 30 KHz. Each of the slots 732, 734 comprises 14 symbols. In this example, OFDM symbol #0 of slot 734 containing PSCCH/PSSCH may use CPE. In symbol #13 of slot 732, the exemplary plurality of CPE start positions t1-t3 are 16us, 25us, 34 us..70 us, respectively.

In yet another example, slots 742, 744 are two consecutive slots according to the SCS of 60 KHz. Each of the slots 742, 744 includes 14 symbols. In this example, OFDM symbol #0 containing slot 744 of PSCCH/PSSCH may use CPE. In symbol #13 of slot 742, the exemplary CPE start position t1 is at 16us.

Typically, on the side link, the UE transmits the CPE at a determined CPE start location before the UE transmits the control or data signal.

As described above, multiple CPE start positions for PSCCH and PSSCH side uplink transmissions are supported. Further, in FDM, different UEs may transmit simultaneously on different portions of the frequency band. In some configurations, all UEs that gain access to channels on the side-to-side link in the COT select the same CPE starting location prior to their transmission. If different UEs use different CPE start positions, this may lead to a situation where an earlier CPE blocks the sensing of a later CPE.

For example, UE-1 has gained access to the first portion of the frequency band in the COT and determines to start its CPE transmission from location Tl based on sensing that the channel is idle. In addition, UE-2 has gained access to the second part of the frequency band and has selected a later CPE start time T2, again sensing that the channel is idle. At T1, UE-1 begins transmitting its CPE. When time T2 arrives, UE-2 performs a fast carrier sense check just before UE-2 initiates its intended CPE. This allows the UE-2 to detect whether the channel conditions have changed since the earlier channel access procedure. During this carrier sensing, UE-2 detects the UE-1 ongoing CPE transmission at time T2. Since it is now sensed that the channel is busy, UE-2 does not transmit its CPE. Early CPE of UE-1 has hindered the transmission of UE-2 in COT.

By aligning CPE start locations across UEs, they can reliably perform simultaneous frequency division multiplexed transmissions without collision or blocking.

The PSCCH/psch transmission from a UE may occupy part or all of an RB set allocation over a frequency band. Partial RB set allocation means that transmission uses only some of the available RBs in the RB set, while full RB set allocation uses all of the available RBs.

To coordinate their transmissions, the UEs may send resource reservation information indicating which specific RBs they intend to occupy for their future transmissions. The reservation may also be detected by other UEs at the time of transmission.

If the UE detects a reservation of the same slot (e.g., slot 724) and uses the same set of RBs that the UE wants to transmit, this implies the risk of using FDM transmission schemes and collisions. In this case, the UE uses a default CPE start position that is pre-configured using the first technique described below. The same default CPE positions are used to align transmissions and to enable frequency division multiplexing between UEs, thereby avoiding collisions.

On the other hand, if no resource reservation is detected for the same slot and RB set that the UE wants to transmit, it is recommended that the FDM transmission scheme not be employed and that the chance of collision with other UEs is low. In this case, the UE may use a second technique described below for CPE selection based on the random CPE location of the transmission priority. Since the collision probability is already low, no aligned CPE is needed. The UE may randomly select from available CPE locations according to priority.

In a first scenario, the UE employs a first technique when it determines that its PSCCH/PSSCH transmission that initiates COT is under an FDM transmission scheme. More specifically, a single CPE start position within a previous symbol immediately prior to starting the COT is preconfigured and/or signaled as a default start position. The previous symbol and the initial symbol of the COT are consecutive symbols. The single CPE start position may be any one of the candidate CPE start positions.

In the example of slots 722, 724, the COT starts at slot 724. The UE is configured with a single default starting position, which may be any one of t1 to t7 in symbol # 13. Thus, the UE sends the CPE at a single default CPE start position in symbol # 13.

The location of a single default CPE start position may be (pre) configured and/or indicated. For example, it may be configured and/or indicated before the first of the plurality of CPE start positions and/or after the last of the plurality of CPE start positions and/or in-between the plurality of CPE start positions. In addition, a single CPE start position may be (pre) configured and/or indicated as one of a plurality of CPE start positions or not indicated.

The second technique is employed by the UE when the UE determines that the PSCCH/PSSCH transmission that initiates the COT is not under the FDM transmission scheme. More specifically, the candidate CPE start locations are divided into different groups, each group being associated with a respective priority of PSCCH/PSSCH transmissions. The UE randomly selects a CPE start position from a set of candidate CPE start positions associated with a priority of PSCCH/PSSCH transmissions to be made by the UE.

The priority of PSCCH/PSSCH transmission refers to the relative importance or urgency of control signaling and data transmitted on the side-link via the PSCCH and PSSCH channels, respectively. The priority of certain types of side-uplink transmissions is given preference to other types.

The priority level may be configured by the network, e.g., the base station assigns priority values or ranges to different side-uplink logical channels. For example, safety-related V2X messages (e.g., emergency brake warnings) may be assigned a higher priority than conventional driving state updates. The priority may also be based on transmission characteristics. For example, retransmissions may be given higher priority than initial transmissions.

Higher priority PSCCH/PSSCH transmissions generally have better access to radio resources. In particular, for CPE selection, higher priority transmissions may obtain an earlier CPE location to access the channel faster before lower priority transmissions. This ensures that emergency services such as secure messages have the best opportunity to access the channel with minimal delay.

In the example of slots 722, 724, the COT starts at slot 724. The candidate CPE start locations tl through t2 may be associated with a first priority of PSCCH/PSSCH transmissions; the candidate CPE start locations t3 through t4 may be associated with a second priority of PSCCH/PSSCH transmissions; the candidate CPE start locations t5 through t7 may be associated with a third priority of PSCCH/PSSCH transmissions. The UE may determine that its PSCCH/PSSCH transmission has a first priority. Thus, the UE randomly selects a CPE start location from t1 and t2 and sends the CPE at that location in symbol # 13.

In a second scenario, the UE may send CPE for additional signals within the existing COT using the first and second techniques described above. In this scenario, in the example of slots 722, 724, they are located in the same COT; in the example of slots 732, 734, they are located in the same COT; in the example of slots 742, 744, they are located in the same COT. The UE may perform type 2 channel access to transmit the additional PSCCH/PSCCH within the COT. The UE is configured with a single default CPE start position and multiple candidate CPE start positions based on priority. In the example of slots 722, 724, the UE will begin transmitting additional PSCCH/PSSCH transmissions at symbol #0 in slot 724, which is in the same COT as slot 722. The UE transmits CPEs in slot 722 at one of the CPE start positions in symbol # 13.

In this scenario, the UE applies the same CPE selection method as described previously for the case where type 1 channel access is performed for the UE to initiate COT. Specifically: if the UE sends or detects a resource reservation for the same slot (e.g., slot 724) and RB set within the COT as its intended PSCCH/PSSCH transmission, the UE selects a pre-configured default CPE start position (first technique) for transmission under the FDM scheme. Otherwise, the UE randomly selects a CPE start position from among a plurality of candidate positions based on a priority configuration for PSCCH/PSSCH transmission (second technique) for transmission under a non-FDM scheme.

For PSCCH/PSSCH transmissions, the default CPE starting position may be preconfigured as the first of the set of all candidate CPE starting positions. For example, the CPE start position index Δ _i is always 1 for one symbol interval and 3 in 30kHz and 60kHz for two symbol intervals.

For physical side uplink feedback channel (PHYSICAL SIDELINK feedback channel, PSFCH) transmissions, a single CPE start position is pre-configured for each resource pool. The preconfigured value for the starting position PSFCH CPE may be selected from a set of all candidate CPE starting positions defined in 3gpp TS 38.211.

In other words, the base station predefines a specific CPE start location for PSFCH transmissions for each resource pool. The starting location is selected from the candidate CPE locations. Then, the UE uses the single preconfigured location when transmitting PSFCH in a given resource pool.

The base station configures one or more PSFCH resource pools, each PSFCH resource pool indicating a set of allowed time-frequency resources for PSFCH. For each resource pool, the base station pre-configures a single CPE start position that the UE should use when transmitting PSFCH in that resource pool. The UE is informed of the CPE start location associated with each of its configured resource pools. When a UE transmits PSFCH in a given resource pool, it uses CPE start locations that are pre-configured for that resource pool.

For S-SSB transmissions, a single CPE start location is preconfigured. The preconfigured value for the S-SSB CPE start position may be selected from a set of all candidate CPE start positions defined in "3GPP TS 38.211V17.3.0(2022-09)Technical Specification;3rd Generation Partnership Project;Technical Specification Group Radio Access Network;NR;Physical channels and modulation(Release 17)"(3GPP TS 38.211), the entire content of 3gpp TS 38.211 is expressly incorporated herein by reference.

In other words, the base station predefines a specific CPE start location for S-SSB transmissions. A starting location is selected from the candidate CPE locations. Then SyncRef UE uses this single preconfigured location when sending the S-SSB.

Fig. 8 is a schematic diagram 800 illustrating CPE selection. In a first example, slots n and n+1 are two consecutive slots. Both UE-1 and UE-2 gain access to RB set 850 for the COT on the side link through a channel access procedure (e.g., a channel access procedure in slot n). COT starts at slot n+1. Before UE-1 and UE-2 begin PSCCH/PSSCH transmission in slot n+1, both UE-1 and UE-2 will transmit CPE in the last symbol of slot n (symbol # 13).

In this example, neither UE-1 nor UE-2 sends a resource reservation for resources in RB set 850 and slot n+1, and no such reservation is detected. This means that there is no overlapping resource reservation between UEs. Both UE-1 and UE-2 determine not to use the FDM transmission scheme and determine CPE start location based on priority.

In this example, UE-1 and UE-2 are each configured with 4 CPE start locations #0 to #3. In addition, CPE start locations #0, #1, and #2 are associated with a first priority of PSCCH/PSSCH transmission. CPE start position #3 is associated with a second priority of PSCCH/PSSCH transmissions. Further, PSCCH/PSSCH transmissions for UE-1 and UE-2 each have a first priority. Thus, UE-1 randomly selects CPE start location #0 and UE-2 randomly selects CPE start location #1 from among candidate locations #0, #1, #2 associated with the first priority.

UE-1 starts transmitting CPE at position #0 in symbol #13 of slot n. Since location #0 starts earlier than location #1, UE-2 performs a brief carrier sense check just before UE-2 initiates its intended CPE transmission at location # 1. During this sensing, UE-2 detects the CPE transmission that UE-1 is currently in progress. Since it is now sensed that the channel is busy, UE-2 does not send its CPE and subsequent PSCCH/PSSCH transmissions. Thus, in slot n+1, only UE-1 transmits its PSCCH/PSSCH on RB set 850.

In a second example, slots m and m+1 are two consecutive slots. Both UE-1 and UE-3 gain access to the RB set 850 for the COT on the side link through a channel access procedure, such as the channel access procedure in slot m. COT starts at slot m+1. Before UE-1 and UE-3 begin PSCCH/PSSCH transmission in slot m+1, both UE-1 and UE-3 will transmit CPE in the last symbol of slot m (symbol # 13).

In this example, both UE-1 and UE-3 send resource reservations for resources in RB set 850 and slot m+1. In addition, UE-1 and UE-3 detect reservations transmitted to each other. This means that there is an overlapping reservation of resources between UEs.

Because there is an overlapping reservation of resources, both UE-1 and UE-3 determine to use the FDM transmission scheme. As previously described, when FDM transmission is required, the UE will select a single default CPE start position (e.g., CPE start position # 0) that is pre-configured.

Thus, both UE-1 and UE-3 send CPE from the default CPE start position in symbol #13 of slot m. Since UE-1 and UE-3 use the same default location, their CPE transmissions will be aligned in time and will not block each other. This allows two UEs to successfully start their PSCCH/PSSCH transmissions in RB set 850 of slot m+1 with FDM.

Thus, when overlapping resource reservations are detected, indicating that FDM transmissions are required, the UEs will align their CPE transmissions by using the default CPE start position. This may prevent blocking and enable frequency division multiplexed transmission across multiple UEs.

In summary, for PSCCH/PSSCH transmissions, whether Type 1 or Type 2 channel access is performed, whether within or outside the COT, the CPE selection may be determined based on whether FDM transmissions are required. In some configurations, the UE may determine whether FDM transmission is required to select CPE accordingly based on whether a resource reservation is sent or detected. As described above, when there is a resource reservation, multiple UEs may select a single CPE start position for FDM transmission. When there is no resource reservation, multiple UEs may choose to transmit from one or more CPE start positions according to priority (or the same priority is random).

Fig. 9 is a flow chart 900 illustrating a method (process) of transmitting a CPE. The method may be performed by a UE. In operation 902, the UE obtains a COT occupying a set of resources on a SL in an unlicensed spectrum through a channel access procedure. In some configurations, the set of resources includes a set of slots and a set of RBs.

In operation 904, the UE determines whether the FDM transmission scheme is used for SL transmission over SL in the COT. In some configurations, the FDM transmission scheme is determined to be employed when a resource reservation for a set of resources for an intended SL transmission in the COT is sent or detected. When no resource reservation for a set of resources for an intended SL transmission in the COT is sent and not detected, it is determined that the FDM transmission scheme is not employed.

When the FDM transmission scheme is employed, the UE selects a default CPE start position prior to the initial symbol containing the SL transmission in operation 906. In some configurations, the default CPE home location is preconfigured as one of a set of all candidate CPE home locations. In some configurations, the default CPE home location is preconfigured to be independent of the set of all candidate CPE home locations.

When the FDM transmission scheme is not employed, the UE selects a subset from the set of all candidate CPE start positions based on the Ll priority of the SL transmission and randomly selects a CPE start position from the subset that precedes the initial symbol containing the SL transmission in operation 908. In some configurations, the subset includes at least one CPE start position selected from a set of all candidate CPE start positions based on L1 priority according to a pre-configuration. CPE start locations are randomly selected from a subset associated with the L1 priority of SL transmissions.

In operation 910, the UE determines whether a channel access procedure performed before the selected CPE start location was successful. When the channel access procedure is successful, the UE transmits the CPE at the selected CPE start position and performs SL transmission after transmitting the CPE in operation 912. When the channel access procedure is unsuccessful, the UE does not transmit the CPE at the selected CPE start position and does not perform SL transmission in operation 914.

In some configurations, CPE may be sent outside and inside the COT. In some configurations, the SL transmissions include at least one of PSCCH transmissions and PSSCH transmissions. In some configurations, the default CPE starting position prior to PSCCH or PSSCH transmission within the COT is the initial position in the set of all candidate CPE starting positions. In some configurations, the initial symbol comprising the SL transmission is the initial symbol of the COT. In some configurations, the initial symbol containing the SL transmission is not the initial symbol of the COT.

In some configurations, the SL transmissions include PSFCH transmissions in which a single CPE start position is preconfigured from a set of all candidate CPE start positions.

It should be understood that the specific order or hierarchy of steps in the processes/flowcharts disclosed are descriptions of exemplary approaches. It should be appreciated that the particular order or hierarchy of steps in the processes/flowcharts may be rearranged based on design preferences. In addition, some steps may be further combined or omitted. The accompanying method claims present elements of the various steps in a sample order, and are not meant to limit the invention to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects of the invention described. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language claims, in which reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". The term "exemplary" means "serving as an example, instance, or illustration" in the present disclosure. Any aspect described as "exemplary" is not necessarily preferred or advantageous over other aspects. The term "some" means one or more unless stated otherwise. 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 a plurality of a, B or 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 a alone, B alone, 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 to the elements of the various aspects described herein are known or later come to be known to those of ordinary skill in the art and are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether the invention is explicitly recited in the claims. The terms "module," mechanism, "" component, "" apparatus, "and the like may not be a substitute for the term" means. Thus, unless the phrase "means for …" is used to explicitly state an element in a claim, that element should not be construed as a functional limitation.

Claims (20)

1. A method of side-uplink transmission, comprising:

obtaining channel occupation time of occupying a group of resources on a side link in an unlicensed spectrum through a channel access process;

Determining whether a frequency division multiplexing transmission scheme is used for side-uplink transmission on the side-link in the channel occupancy time;

Selecting a cyclic prefix extension starting position before an initial symbol containing the side-link transmission, wherein the cyclic prefix extension starting position is a default cyclic prefix extension starting position when a frequency division multiplexing transmission scheme is adopted, selecting a subset from a set of all candidate cyclic prefix extension starting positions based on layer 1 priority of the side-link transmission when the frequency division multiplexing transmission scheme is not adopted, and randomly selecting the cyclic prefix extension starting position from the subset; and

And transmitting a cyclic prefix extension at the selected cyclic prefix extension start position, and performing the side-uplink transmission after transmitting the cyclic prefix extension.

2. The method of side-link transmission of claim 1, wherein the frequency division multiplexing transmission scheme is determined to be employed when a resource reservation for the set of resources for an intended side-link transmission in the channel occupancy time is sent or detected.

3. The method of side-link transmission of claim 1, wherein the frequency division multiplexing transmission scheme is determined not to be employed when no resource reservation for the set of resources for the intended side-link transmission in the channel occupancy time is sent and not detected.

4. The side-link transmission method of claim 1, wherein the set of resources comprises a set of time slots and a set of resource blocks.

5. The side-uplink transmission method of claim 1, wherein the default cyclic prefix extension starting location is preconfigured as one of a set of all candidate cyclic prefix extension starting locations.

6. The side-uplink transmission method of claim 1, wherein the default cyclic prefix extension starting location is preconfigured independent of a set of all candidate cyclic prefix extension starting locations.

7. The side-uplink transmission method of claim 1, wherein the subset comprises at least one cyclic prefix extension starting location selected from the set of all candidate cyclic prefix extension starting locations according to a pre-configured layer 1-based priority.

8. The method of side-link transmission of claim 7, wherein the cyclic prefix extension start position is randomly selected from the subset associated with the layer 1 priority of the side-link transmission.

9. The side-uplink transmission method of claim 1, wherein the cyclic prefix extension is transmitted outside of and within the channel occupancy time.

10. The sidelink transmission method of claim 1, wherein the sidelink transmission comprises at least one of a physical sidelink control channel transmission and a physical sidelink shared channel transmission.

11. The sidelink transmission method of claim 10, wherein the default cyclic prefix extension starting position before the physical sidelink control channel transmission or the physical sidelink shared channel transmission within the channel occupancy time is an initial position in a set of all candidate cyclic prefix extension starting positions.

12. The method of side-link transmission of claim 1, wherein the initial symbol comprising the side-link transmission is an initial symbol of the channel occupancy time.

13. The method of side-link transmission of claim 1, wherein the initial symbol comprising the side-link transmission is not an initial symbol of the channel occupancy time.

14. The side-uplink transmission method of claim 1, further comprising:

Executing the channel access procedure before the selected cyclic prefix extension starting position, and when the channel access procedure is successful, transmitting the cyclic prefix extension at the selected cyclic prefix extension starting position; and

And when the channel access flow is unsuccessful, not transmitting the cyclic prefix extension at the selected cyclic prefix extension starting position.

15. The method of sidelink transmission of claim 1, wherein the sidelink transmission comprises a sidelink synchronization signal block transmission, wherein a single cyclic prefix extension start position is preconfigured from a set of all candidate cyclic prefix extension start positions for use before the sidelink synchronization signal block transmission.

16. The sidelink transmission method of claim 1, wherein the sidelink transmission comprises a physical sidelink feedback channel transmission, wherein a single cyclic prefix extension start position is preconfigured from a set of all candidate cyclic prefix extension start positions for use before the physical sidelink feedback channel.

17. An apparatus for side-link transmission, comprising:

a memory; and

At least one processor coupled to the memory for:

obtaining channel occupation time of occupying a group of resources on a side link in an unlicensed spectrum through a channel access process;

Determining whether a frequency division multiplexing transmission scheme is used for side-uplink transmission on the side-link in the channel occupancy time;

Selecting a cyclic prefix extension starting position before an initial symbol containing the side-link transmission, wherein the cyclic prefix extension starting position is a default cyclic prefix extension starting position when a frequency division multiplexing transmission scheme is adopted, selecting a subset from a set of all candidate cyclic prefix extension starting positions based on layer 1 priority of the side-link transmission when the frequency division multiplexing transmission scheme is not adopted, and randomly selecting the cyclic prefix extension starting position from the subset; and

And transmitting a cyclic prefix extension at the selected cyclic prefix extension start position, and performing the side-uplink transmission after transmitting the cyclic prefix extension.

18. The apparatus of claim 17, wherein the frequency division multiplexing transmission scheme is determined to be employed when a resource reservation for the set of resources for an intended side-link transmission in the channel occupancy time is sent or detected.

19. The apparatus of claim 17, wherein the frequency division multiplexing transmission scheme is determined not to be employed when no resource reservation for the set of resources for an intended side-link transmission in the channel occupancy time is sent and detected.

20. A computer readable medium storing computer executable code, wherein the computer executable code performs the steps of the sidelink transmission method of any of claims 1 to 16.