Method implemented by wireless transmit receive unit (WTRU)

Abstract

The present application provides a method implemented by a wireless transmit receive unit (WTRU), the method comprising: receiving configuration information indicating a set of cyclic prefix extension (CPE) start positions associated with a shared channel occupancy time (COT), where each CPE start position in the set is associated with a sidelink transmission priority, and where the set of CPE start positions is associated with a shared channel occupancy time (COT); wherein each CPE has a duration; receiving a side link control information (SCI) message, wherein the SCI message indicates a remaining COT duration; transmitting the CPE in the shared COT at a starting position for a certain duration, wherein the starting position and the duration of the CPE are determined based on the priority of sidelink messages and the configuration information; the sidelink message is transmitted in the shared COT after the CPE at a transmission time determined according to the remaining COT duration.

Description

[0001] This application is a divisional application of the invention whose applicant is Interactive Digital Patent Holdings Corporation, whose application date is February 8, 2023, whose application number is 202380025513.5, and whose name is “Method for sidelink unlicensed channel access”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 63 / 308,341 filed on February 9, 2022, U.S. Provisional Application No. 63 / 327,206 filed on April 4, 2022, U.S. Provisional Application No. 63 / 395,220 filed on April 4, 2022, U.S. Provisional Application No. 63 / 410,907 filed on September 28, 2022, and U.S. Provisional Application No. 63 / 421,831 filed on November 2, 2022, the contents of which are incorporated herein by reference. Background Art

[0004] In unlicensed spectrum communications, a process known as listen-before-talk may be employed to ensure that each device operating in the unlicensed spectrum does not interrupt another device. However, there is a need to improve this basic concept to provide a more efficient and capable system for communicating in the unlicensed spectrum. Summary of the invention

[0005] There may be methods for sidelink unlicensed (SL U) channel access in mode 2. For example, a wireless transmit receive unit (WTRU) may perform SL U channel access and resource selection for channel occupancy time (COT) sharing and COT initiation within a resource selection window (RSW). The WTRU may detect the COT and share based on control information such as remaining duration, number of scheduled transmissions within the COT, frequency resource assignment, priority, broadcast type, WTRU source and / or destination ID, COT / resource reservation, channel congestion, etc. The WTRU may determine SL COT initiation based on LBT and SCI sensing information including COT / resource reservation, priority, broadcast type, WTRU source and / or destination ID, channel congestion, etc.

[0006] The present application provides a method implemented by a wireless transmission receiving unit (WTRU), the method comprising: receiving configuration information, the configuration information indicating a set of cyclic prefix extension (CPE) starting positions associated with a shared channel occupation time (COT), wherein each CPE starting position in the set of CPE starting positions is associated with a side link transmission priority, wherein each CPE has a duration; receiving a side link control information (SCI) message, wherein the SCI message indicates a remaining COT duration; transmitting a CPE in the shared COT at a starting position for a certain duration, wherein the starting position and the duration of the CPE are determined based on the priority of the side link message and the configuration information; and transmitting the side link message in the shared COT after the CPE at a transmission time determined according to the remaining COT duration.

[0007] The present application also provides a wireless transmit-receive unit (WTRU), the WTRU comprising: a processor, the processor being operatively coupled to a transceiver, the processor and the transceiver being configured to receive configuration information, the configuration information indicating a set of cyclic prefix extension (CPE) starting positions associated with a shared channel occupancy time (COT), wherein each CPE starting position in the set of CPE starting positions is associated with a side link transmission priority, wherein each CPE has a duration; the processor and the transceiver being configured to receive a side link control information (SCI) message, wherein the SCI message indicates a remaining COT duration; the processor and the transceiver being configured to transmit a CPE in the shared COT at a starting position for a certain duration, wherein the starting position and the duration of the CPE are determined based on the priority of the side link message and the configuration information; the processor and the transceiver being configured to transmit the side link message in the shared COT after the CPE at a transmission time determined according to the remaining COT duration. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements, and in which:

[0009] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0010] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system;

[0011] Figure 1C is an example of an embodiment in which Figure 1A a system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0012] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0013] Figure 2A and Figure 2B An example of a SL U resource allocation unit is illustrated;

[0014] Figure 3 An example of sharing a WTRU determination of a Type 2 LBT for COT sharing is illustrated;

[0015] Figure 4A , Figure 4B and Figure 4C An example of SL U channel access and resource selection is illustrated;

[0016] Figure 5 An example of WTRU determination of a COT starting position within a SL slot is illustrated;

[0017] Figure 6 illustrates an example of WTRU resource group / COT selection prior to Type 1 LBT for COT initiation; and

[0018] Figure 7 An example of a process for a WTRU to transmit in an unlicensed spectrum is illustrated. DETAILED DESCRIPTION

[0019] As discussed herein, there may be one or more abbreviations as indicated in Table 1.

[0020]

[0021]

[0022]

[0023]

[0024] Table 1

[0025] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0026] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0027] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0028] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0029] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0030] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0031] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0032] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using NR.

[0033] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0034] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), GSM Enhanced Data Rates for Evolution (EDGE), GSM EDGE (GERAN), etc.

[0035] Figure 1A The base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a micro-micro cell base station or a femto cell base station. As Figure 1A As shown, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0036] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the accompanying drawings, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0037] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0038] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0039] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0040] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0041] The transmission / reception element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmission / reception element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmission / reception element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In another embodiment, the transmission / reception element 122 may be configured to transmit and / or receive both RF signals and optical signals. It should be understood that the transmission / reception element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0042] Although the transmit / receive element 122 Figure 1B 102 as a single element, but the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0043] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0044] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0045] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0046] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0047] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Module, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. Peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geographic location sensor, altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor, humidity sensor, etc.

[0048] The WTRU 102 may include a full-duplex radio for which some or all of the transmissions and receptions (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which some or all of the transmissions and receptions (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which some or all of the transmissions and receptions (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0049] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0050] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0051] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0052] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0053] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0054] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0055] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0056] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0057] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0058] In a representative embodiment, the other network 112 may be a WLAN.

[0059] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent by the AP, for example, where the source STA may send traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be sent between the source STA and the destination STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0060] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may transmit a beacon on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0061] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0062] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be transmitted by transmitting STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be sent to the medium access control (MAC).

[0063] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0064] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, due to a STA (e.g., only supporting a 1MHz operating mode) transmitting to the AP, all available frequency bands may be considered busy even if most of the available frequency bands remain idle.

[0065] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0066] Figure 1D 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0067] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0068] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0069] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRU 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the evolved Node-B 160a, 160b, 160c. For example, the WTRU 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-B 160a, 160b, 160c may act as a mobility anchor for the WTRU 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRU 102a, 102b, 102c.

[0070] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0071] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0072] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as Wi-Fi.

[0073] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure the traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy implementation and QoS, providing DL data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0074] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0075] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0076] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0077] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0078] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which may include one or more antennas) can be used by the simulation device to transmit and / or receive data.

[0079] In some cases, the WTRU may operate in an unlicensed (U) spectrum. In addition, the WTRU may communicate using sidelink (SL) communications. Therefore, in an unlicensed spectrum, such as frequency range 1 (FR1), there may be sidelink operations for both mode 1 and mode 2, which may be referred to as sidelink unlicensed (SL U). For example, the unlicensed SL bands may be 5 GHz and 6 GHz, and the Uu operations associated with mode 1 may be limited to licensed spectrum. The SL U channel access design may be based on regional regulatory requirements with new radio unlicensed (NR U) channel access as a starting point.

[0080] The SL resource allocation mechanism for licensed spectrum may be (re)used in SL U. SL U may cover changes to the NR SLPHY channel structure and procedures for operating in unlicensed spectrum.

[0081] In some cases, the WTRU may operate in an unlicensed spectrum. In addition, the WTRU may communicate in an NR system. In New Radio Unlicensed (NR U), the WTRU may access a channel for uplink (UL) transmissions according to one of the Type 1 or Type 2 UL channel access procedures. These procedures may be designed to comply with regulatory requirements related to, for example, sensing (e.g., Listen Before Talk (LBT)), Maximum Channel Occupancy Time (MCOT), Occupied Channel Bandwidth (OCB), and / or Power Spectral Density (PSD).

[0082] The type 1 channel access procedure may include LBT sensing with random backoff and a variable extended clear channel assessment (CCA) period based on a contention window; the contention window size may be selected based on the channel access priority level (CAPC) configuration. A base station (e.g., gNB, etc.) or a WTRU may perform a type 1 channel access procedure to initiate a channel occupation time (COT). When the transmission gap is 25us and 16us, type 2A and 2B channel access may be performed, respectively. When the transmission gap is less than 16us, type 2C channel access may be applied in the case of transmission immediately after the gap without performing sensing.

[0083] For initial access, NR U may use one or more discovery reference signals (DRS) containing a burst set of synchronization signals / physical broadcast channel (SSB) blocks with an increased number of candidate SSB positions within the DRS window. The design may also include handling of reduced SSB blocks and remaining minimum system information (RMSI) transmission opportunities due to LBT failure. Modifications to the random access procedure may be used to handle reduced message 1 / 2 / 3 / 4 transmission opportunities due to LBT failure, such as physical random access channel (PRACH) repetitions in the frequency domain and extension of the random access response window. The PRACH preamble format may also be extended to meet OCB requirements.

[0084] For downlink (DL) transmissions, NR U can address COT structure indication, dynamic PDCCH monitoring and / or flexible PDSCH starting position due to the uncertainty caused by LBT. For UL control and data channel transmissions, in order to comply with one or more OCB requirements, new block-interleaved based transmissions can be used for PUCCH and PUSCH, with PUSCH having a flexible starting position. NR U sounding reference signal (SRS) transmissions can also be enhanced with additional flexibility in configuration and triggering. In addition, NR U can support frame structures with multiple DL to UL and UL to DL switching points within a shared COT.

[0085] NR U can support additional HARQ transmission opportunities and immediate HARQ transmission for corresponding data in the same shared COT and subsequent COTs to ensure channel access for HARQ transmission.

[0086] For a WTRU operating in an unlicensed spectrum, one or more problems may arise.

[0087] For example, the SL PHY layer structure and signals may not need to be modified to address the parameters required for occupied channel bandwidth (OCB) and power spectral density (PSD). In an unlicensed spectrum, a transmission may be required to occupy at least a certain amount, X%, of the channel bandwidth, such as 90%. This OCB requirement ensures that the occupancy of the channel can be detected. In addition, a maximum PSD may be required on transmissions in the unlicensed spectrum to spread the generated interference across the entire unlicensed carrier. The SL PHY layer structure and signal design may need to address these issues. For example, in one case, a SL transmission may span one or more subchannels and occupy only a portion of the SL carrier. The maximum PSD within such a transmission may be significantly higher than the maximum PSD requirement. In addition, guard symbols (e.g., the length of the guard symbols may be greater than 16us) may be used at the end of the SL slot and between the PSSCH symbol and the PSFCH symbol in the SL slot. Transmissions from the WTRU separated by such a gap may be considered separate transmission bursts, and new sensing for channel access may need to be performed after the gap, and therefore a single-slot SL transmission may not be completed with one channel access. Additionally, the SL resource pool may include logical slots that are not contiguous in the time domain, and a SL transmission burst over several such logical slots indicated by contiguous indices may have gaps within the transmission and thus cannot be performed in one COT.

[0088] In another example of a potential problem, SL resource allocation and reservation may not be feasible in unlicensed spectrum due to regulatory requirements for fair coexistence. In some cases, for unlicensed spectrum, all nodes must follow the channel access procedures specified for the unlicensed spectrum to enforce fair coexistence. SL resource allocation and reservation in Mode 1 and Mode 2 may not include channel access based on LBT sensing, and therefore improved mechanisms may be required for SL resource acquisition in unlicensed spectrum, especially considering one or more changes in the PHY layer structure and the resulting resource granularity for SL transmission. In a SL design with reserved future resources indicated in the SL control information (SCI) in the PSCCH, reservations for resources (such as for retransmissions of a non-periodic SL TB or for transmissions of another new SL TB (e.g., semi-persistent transmissions)) can be deterministic. However, in the unlicensed spectrum, due to the uncertainty of the results of sensing and channel access, resources may not be reserved in the same manner as in SL, and new resource reservation designs may be required.

[0089] In another example of a potential problem, there may be no centralized base station (e.g., gNB) to coordinate and schedule COT sharing in Mode 2. In the NR U design, the WTRU may receive UL scheduling information containing a COT indication and sharing information, such as COT duration and channel access for COT sharing. As a central node, the base station is able to coordinate a set of DL and UL transmissions to and from the WTRUs so that the WTRUs can share the COT initiated by the base station. For example, the base station may schedule UL transmissions with timing that can be aligned with its DL transmissions, so the WTRUs can share the COT without performing sensing using Type 2C channel access. In SL Mode 2, when the WTRUs acquire and reserve resources without the participation of the base station, COT sharing between WTRUs may be performed by the WTRUs in a distributed manner, so one or more procedures are required to address this approach.

[0090] As discussed herein, there may be one or more approaches to addressing the aforementioned potential issues as well as other issues not disclosed herein.

[0091] In some cases (e.g., for the time domain), the WTRU may determine the SLU resources that belong to the SLU resource pool. The minimum SLU time domain allocation unit for PSSCH / PSCCH transmission may be a certain time unit, such as a time slot, a mini-slot, etc. The WTRU may be (pre)configured with a time unit configuration for the (pre)configured SLU resource pool. The time unit configuration may include a duration (e.g., for a mini-slot, such as 2 symbols, 5 symbols, or 7 symbols). As discussed herein, although some examples herein may refer to specific time units for demonstration purposes, any reference to a time unit (such as a time slot) may refer to a time slot and / or a mini-slot, and / or any other time unit as discussed herein.

[0092] The WTRU may perform transmission of a TB in a PSSCH with an associated PSCCH within a timeslot. The associated PSCCH transmission may carry a first level of SCI (SCI-1) associated with the PSSCH transmission. A second level of SCI (SCI-2) may be multiplexed with the PSSCH within the resources allocated for PSSCH transmission. In some instances, the WTRU may not switch between PSCCH transmission and reception within a timeslot. In another example, the PSCCH may carry all control information for the associated SL PSSCH transmission.

[0093] In one method, the WTRU may be (pre)configured with all symbols for PSSCH / PSCCH transmission within a slot.The WTRU may perform PSSCH / PSCCH transmission and associated DMRS transmission in consecutive symbols within such a PSSCH / PSCCH slot.

[0094] The WTRU may be (pre)configured with an automatic gain control (AGC) symbol as the first symbol of a timeslot. The WTRU may copy the contents of the second symbol to the AGC symbol. The AGC symbol may enable convergence of the AGC for reception of PSSCH / PSCCH transmissions. During the AGC symbol, the WTRU may adjust the RX front-end radio gain to achieve the desired baseband input power level. Due to variations in the received incoming signal, it may take some time for the gain to converge to the desired level.

[0095] The WTRU may be (pre)configured with a set of DMRS configurations for PSSCH / PSCCH transmissions. Each configuration may include an index of a symbol for DMRS transmission in a slot. The WTRU may determine the DMRS configuration and indicate the determined DMRS configuration in the SCI in the associated PSCCH transmission.

[0096] In some cases (eg, for frequency domain), the WTRU may be (pre)configured with one or more SLU carriers. The WTRU may be (pre)configured with one or more SLU bandwidth parts (BWPs) within the (pre)configured SLU carriers.

[0097] The WTRU may be (pre)configured with one or more RB sets in a SL U BWP. Each RB set may include a number of consecutive RBs, and the (pre)configuration of the RB set may include an index of the starting RB and the number of RBs in the RB set. Within the SL U BWP, the RB sets may be indexed in ascending order. The WTRU may determine the frequency resource allocation of the RB set based on the RB set index.

[0098] The minimum SLU frequency domain allocation unit for PSSCH / PSCCH transmission may be an RB interleave. SLU transmission based on RB interleave may meet the occupied channel bandwidth (OCB) requirements of unlicensed spectrum. The WTRU may be (pre) configured with M RB interlaces on the frequency bandwidth of an RB set. The value of M may be associated with the subcarrier spacing (SCS), such as 10 for 15kHz and 5 for 30kHz. Each RB interleave within an RB set and / or resource pool may be indicated by an index (m), where m may be an integer from 0 to M-1. RB interleave (m) may include RBs indexed as (m, m+M, m+2xM, m+3xM…m+NxM), where N may be the (pre) configured total number of RBs for the RB interleave.

[0099] In some cases, the WTRU may determine the SL U resources that belong to a resource pool. FIG. 2 may be referred to herein as reference Figure 2A and Figure 2B FIG. 2 illustrates an example of SLU resources including RB interleaving within a certain time period (e.g., Figure 2A Examples involving time slots, and Figure 2B Examples involving micro-slots).

[0100] like Figure 2A and Figure 2B As shown, both figures illustrate resource block sets, where time (202) is illustrated on the horizontal axis and frequency (201) is illustrated on the vertical axis. Below each diagram of the RB is an example of how the RB may be used (e.g., for each symbol 203 in the RB, there may be different types of transmissions reserved or scheduled for these time positions, such as AGC, DMRS, PSSCH, PSCCH, etc.): at 205A, there is a time slot for PSCCH / PSSCH transmission, with 14 symbols including the AGC symbol at the beginning of the time slot; and at 205B, there is a mini-slot for PSCCH / PSSH transmission, with 7 symbols including the AGC symbol at the beginning of the time slot. For illustrative purposes, a set of RBs 206 is illustrated in one SLU resource pool, however, there may be more than one set of RBs in a given pool. For illustrative purposes, only one time slot / mini-slot is shown, however, there may be more than one time slot / mini-slot (e.g., one or more sets) in a resource pool. In one example, as shown, the AGC symbol may be used for convergence (as discussed herein), and therefore it cannot hold useful data. Therefore, the data may be copied / replicated to the AGC symbol at the next symbol, and therefore replicated 204.

[0101] The WTRU may be (pre-)configured with one or more SL U resource pools. The WTRU may allocate and reserve one or more such SL resources belonging to the resource pool for SL U transmission.

[0102] The frequency domain resource allocation of such an SLU resource pool may include one or more RB sets. For a resource pool and / or RB set, the WTRU may be (pre)configured with M RB interlaces. Each RB interlace may include N RBs separated by M-1 RBs, and N may be (pre)configured for a resource pool and / or RB set.

[0103] In the time domain, the WTRU may determine the set of time slots that may belong to the SL resource pool based on the (pre-)configuration bitmap associated with the resource pool and the S-SSB transmission (pre-)configuration. The WTRU may determine the set of time slots that may belong to the SL resource pool based on the (pre-)configuration bitmap associated with the resource pool and the S-SSB transmission (pre-)configuration. max), where max may be the maximum index (e.g., 10240 for 15kHz SCS, 20480 for 30kHz SCS, and 40960 for 60kHz SCS), and t0 may indicate the first time slot of a radio frame corresponding to SFN 0 or DFN 0 of the serving cell. The time slots indexed within such a set may be denoted as physical time slots, and the physical time slots in the set may be contiguous in the time domain.

[0104] The WTRU may first exclude from the set the time slots that are (pre)configured for S-SS / PSBCH block (S-SSB) transmissions. The number of such time slots (N) may be determined based on (pre)configured S-SSB parameters such as the duration of the S-SSB transmission periodicity, the number of S-SSB time slots within the S-SSB transmission period, and / or the periodicity of the S-SSB transmissions. S-SSB ).

[0105] The WTRU may determine the remaining (NN) in the set based on the bitmap configuration associated with the resource pool. S-SSB ) time slots may be assigned to the resource pool. The bitmap may include L bits, and the WTRU may expect (NN S-SSB )MOD L is equal to zero. The WTRU may apply a bitmap for each L time slots in the set, with each bit corresponding to a time slot. If the (pre)configured bit value is one, the WTRU may determine that the corresponding time slot may belong to the resource pool. The WTRU may exclude the time slots or mini-time slots corresponding to the bit value zero from the set. The WTRU may determine that all remaining time slots may belong to the resource pool.

[0106] In another method, the WTRU may determine the set of time slots that may belong to the SL resource pool based on the (pre-)configured non-SL time slot set, the (pre-)configuration bitmap associated with the resource pool and / or the S-SSB transmission (pre-)configuration.

[0107] The WTRU may exclude a set of non-SL timeslots from the same set of physical timeslots. Non-SL timeslots may be physical timeslots that are not available for SL transmission and / or reception, and therefore, the WTRU may not include non-SL timeslots in the resource pool.

[0108] In one example, the WTRU may receive a SL symbol (pre)configuration that may include a starting symbol index and a number of symbols after the starting symbol. The WTRU may determine that a physical slot may be a SL slot when symbols within the slot corresponding to the (pre)configuration may be UL symbols. The WTRU may be (pre)configured to perform SL operations on UL symbols and, therefore, may determine that a physical slot may be a non-SL slot when one or more SL symbols corresponding to the SL symbol (pre)configuration may not be UL symbols.

[0109] In another example, the WTRU may receive a SL timeslot (pre)configuration which may indicate which timeslots may be used for SL transmission and / or reception in a carrier. Such a (pre)configuration may include a pattern of physical timeslots allocated for Uu (DL / UL) and SL operations. The WTRU may determine that a physical timeslot may be a non-SL timeslot when a timeslot may be (pre)configured for Uu operation.

[0110] The WTRU may exclude the determined non-SL time slots from the set of physical time slots, and the number of such non-SL time slots may be denoted as N non-SL In addition, the WTRU may exclude N channels that are (pre)configured for S-SS / PSBCH block (S-SSB) transmission. S-SSB time slots, as discussed above.

[0111] The WTRU may determine the remaining (NN) in the set based on the bitmap configuration associated with the resource pool. S-SSB -N non-SL ) time slots may be assigned to the resource pool. The bitmap may include L bits, and the WTRU may further exclude N from the set of time slots. reserved time slots, where N reserved Can be equal to (NN S-SSB -N non-SL )MOD L. The WTRU may apply a bitmap for each L time slots in the set, with each bit corresponding to a time slot. If the (pre)configured bit value is one, the WTRU may determine that the corresponding physical time slot may belong to the resource pool. The WTRU may exclude the physical time slot corresponding to the bit value zero from the set.

[0112] The WTRU may determine that all remaining physical time slots may belong to a resource pool that is (pre)configured with an associated bitmap. The WTRU may continuously reindex the determined time slots of the resource pool in ascending order as (T0, T1, ..., T max ), where T max Can be equal to t max -N S-SSB -N non-SL -N reservedThe WTRU may apply these re-indexed time slots of the resource pool as logical time slots.

[0113] In some cases, the WTRU may determine the temporal continuity of logical time slots in a resource pool.

[0114] In one example, the WTRU may determine that the resource pool may include all available physical time slots when one or more of the following conditions are met: All time slots may be (pre-)configured for SL operation in the carrier (N non-SL = 0); SSB transmission may not be (pre)configured (N S-SSB =0); the value of each bit in the (pre-)configuration bitmap associated with a resource pool may be equal to one (N non-allocated =0), such as all time slots assigned to the associated resource pool; and / or, (NN S-SSB -N non-SL )MOD L can be equal to zero (N reserv =0).

[0115] Alternatively, the WTRU may be (pre)configured with a resource pool that includes all available physical time slots. When the resource pool includes all available physical time slots, the logical time slots may correspond to physical time slots denoted by the same index, such as t i =T i (i from 0 to t max ). The logical time slots of such a resource pool may be continuous in the time domain.

[0116] In another example, the WTRU may determine a resource pool that may include a subset of all available physical time slots when one or more of the following physical time slots are excluded from the resource pool: physical time slots in which one or more (pre-)configured SL symbols are not UL symbols according to the (pre-)configured DL / UL TDD configuration (N non-SL >0); SSB transmission is (pre)configured physical time slot (N S-SSB >0); a physical time slot (N) for which the value of the corresponding bit in the (pre-)configuration bitmap associated with the resource pool may be equal to zero non-allocated >0), such as physical timeslots that are not allocated to the associated resource pool; and / or physical timeslots that are identified as reserved timeslots to be excluded from the resource pool to ensure that the index of the logical timeslots of the resource pool can be repeated in each SFN / DFN cycle, where the WTRU may determine N reserv time slots, where N reserv =(NN S-SSB -N non-SL )MOD L and (N reserv >0).

[0117] In such a resource pool, the logical slots may not correspond to physical slots with the same index, and the determined set of logical slots of the resource pool may not be contiguous in the time domain. In this case, the WTRU may determine the mapping between the index of the logical slots of the resource pool and the index of the corresponding physical slots. The WTRU may determine whether any two logical slots of the resource pool with consecutive indices may be contiguous in the time domain.

[0118] In another case, the WTRU may not re-index the logical time slots included in the resource pool, but may use the index of the corresponding physical time slot of the resource pool to represent the logical time slot of the resource pool. In this case, the WTRU may determine whether two logical time slots can be time-contiguous based on the continuity of the index of the time slot.

[0119] In some cases, the WTRU may send / receive a PSSCH transmission and an associated PSCCH transmission. The WTRU may perform transmissions of the PSSCH and the associated PSCCH in one or more RB interlaces within a timeslot. The WTRU may indicate the RB interlace assignment of the PSSCH in the "Frequency Resource Assignment" bit field in the SCI in the associated PSCCH transmission. The indication may include one or more RB interlace indices and / or RB set indices.

[0120] The WTRU may be (pre)configured with several symbols within a time slot for PSCCH transmission, as shown in the example of FIG2 . For example, the second and third symbols of the time slot may be (pre)configured for PSCCH transmission of the resource pool. In addition, the WTRU may transmit the PSCCH transmission in the (pre)configured PSCCH RBs in the (pre)configured PSCCH symbols. In one example, when one or more RB interlaces are assigned for PSSCH / PSCCH transmission, the WTRU may transmit the PSCCH transmission in the (pre)configured RBs starting from the lowest RB of the RB interlace with the lowest RB interlace index.

[0121] The WTRU may perform a SL transmission burst in an initiated or shared COT in a resource pool. The SL transmission burst may include PSSCH / PSCCH transmissions on consecutive logical and / or physical time slots of the resource pool applied in the time domain, with one PSSCH / PSCCH transmission in each time slot.

[0122] In some cases, the WTRU may be in a specific mode (e.g., Mode 2) and there may be one or more procedures for determining SLU channel access and resource selection. In some cases, SLU channel access and / or resource selection may be based on LBT and / or SCI sensing. The WTRU may perform LBT sensing to determine the availability of the SLU channel before transmission on the SLU channel. The SLU channel may refer to a resource pool and / or RB set that is (pre) configured for SL transmission in a shared spectrum. For example, the WTRU may be on the same bandwidth as the bandwidth of the SLU resource pool and / or RB set and for a duration of T sl LBT sensing is performed within the LBT sensing time slot of =9us.

[0123] The WTRU may perform an SL U channel access and resource selection procedure to determine whether the WTRU can transmit in a sensed SL U channel and select and / or reserve which resources for SL transmission. Generally speaking, in order to reserve something for SL transmission, the WTRU may send a reservation signal, transmission and / or message to indicate to other devices that this WTRU is trying to reserve a channel for use. In one instance, one type of reservation signal may be a cyclic prefix extension (CPE), and the CPE and reservation signal may be interchangeable, as disclosed herein. In another instance, the reservation transmission may be any type of message disclosed herein (e.g., SCI, control information, reservation message, reservation signal, channel occupancy information, window information, etc.). In one instance, the reservation signal may be transmitted continuously, only once per desired period, periodically and / or intermittently to reserve the channel, as needed for a given instance. The WTRU may perform one or more SL transmissions within the channel occupancy time (COT) when the SL U channel access and resource selection procedure is successful.

[0124] The WTRU may perform the SL U channel access and resource selection procedure for COT initiation to initiate the COT. The WTRU may perform one or more SL continuous transmissions starting from the initiated COT. The SL U channel access and resource selection procedure for COT initiation may include LBT sensing-based channel access for COT initiation, and SCI sensing-based channel access and resource selection for COT initiation. For example, LBT sensing-based channel access for COT initiation may be based on type 1 channel access.

[0125] When the gap between transmissions of two WTRUs reaches a threshold (e.g., 25us), the WTRU may perform a transmission in a COT initiated by another WTRU, such as a shared COT. The WTRU may perform a SL transmission in a determined set of time slots and / or mini-time slots within the shared COT. The WTRU may perform SL U channel access and resource selection procedures for COT sharing to share detected and ongoing COTs. The SL U channel access and resource selection procedures for COT sharing may include LBT sensing-based channel access for COT sharing, and SCI sensing-based channel access and resource selection for COT sharing.

[0126] For one or more techniques disclosed herein, there may be a determination of a SL U LBT energy detection threshold (EDT). The WTRU may perform type 1 and / or type 2 LBT sensing based on power detection (e.g., RSSI measurement) performed in a sensing time slot with a (pre)configured duration (e.g., 9us). When the detected power (e.g., measured RSSI) is less than the energy detection threshold (EDT) for at least a specified amount of time (e.g., 4us) within the sensing time slot duration (e.g., 9us), the WTRU may determine whether the channel is available during the sensing time slot. Otherwise, the WTRU may determine that the channel is busy during the sensing time slot. It should be recognized that a low EDT may make it more difficult to acquire a channel, but the acquired channel will have less interference (e.g., due to conflicts) compared to a high EDT. Given the distributed manner of channel access for SL WTRUs, it may be beneficial to allow the WTRU to adjust the EDT in real time so that the WTRU can more easily acquire a channel when the channel congestion level and the associated risk of conflicts are low.

[0127] In one method, the WTRU may determine a default EDT for the LBT procedure based on one or more of: a (pre)configured EDT (e.g., a maximum EDT (pre)configured by a higher layer); a regulatory required EDT level (e.g., an explicit level in dBm); a (pre)configured channel access type (e.g., dynamic channel access, such as load-based equipment (LBE), or semi-static channel access, such as frame-based equipment (FBE)); a (pre)configured SLU maximum transmit power in the LBT channel; and / or a (pre)configured LBT bandwidth.

[0128] The WTRU may dynamically determine the EDT for an upcoming LBT procedure based on a default EDT and one or more of: channel congestion level (e.g., SL CBR, CO, and / or RSSI); type of channel to be transmitted (e.g., PSSCH / PSCCH or PSFCH); priority of the SL TB to be transmitted; remaining PDBs of the SL TB to be transmitted; remaining duration of the resource selection window for the SLTB to be transmitted; received HARQ feedback status associated with transmissions performed in the LBT channel; received SL CSI reports (e.g., CQI measurements); and / or type 1 LBT (COT initiated) or type 2 (COT shared).

[0129] The WTRU may increase the default EDT by a (pre)configured offset (e.g., X dBm) when one or more of the following conditions occurs: the channel congestion level (e.g., SL CBR, CO and / or RSSI) measured in the channel is below a (pre)configured threshold; the remaining PDBs of the SL TB to be transmitted and / or the remaining duration of the resource selection window are below a (pre)configured threshold; the number of HARQ ACKs received from transmissions performed in the channel may exceed a (pre)configured threshold; the number of reported SL CSI (e.g., CQI measurements) above the (pre)configured threshold may exceed a (pre)configured threshold; and / or the WTRU performs type 2 LBT for COT sharing for PSSCH / PSCCH and / or PSFCH transmissions.

[0130] The WTRU may reduce the default EDT by a (pre)configured offset (e.g., X dBm) when one or more of the following conditions occurs: the channel congestion level (e.g., SL CBR, CO, and / or RSSI) measured in the channel exceeds a (pre)configured threshold; the priority of the TB to be transmitted is higher than the (pre)configured threshold; the number of HARQ NACKs received from transmissions performed in the channel may exceed a (pre)configured threshold; the number of reported SL CSI (e.g., CQI) measurements below the (pre)configured threshold may exceed a (pre)configured threshold; and / or the WTRU performs a COT-initiated type 1 LBT for PSFCH transmissions.

[0131] In some cases, the WTRU may perform SCI decoding for SCI sensing. The WTRU may monitor PSCCH transmissions in each time slot belonging to one or more (pre-)configured resource pools other than the resource pool in which the WTRU performs the transmission. The WTRU may perform blind decodings in (pre-)configured PSCCH resources such as the lowest RB of each RB interlace that is (pre-)configured for a resource pool and / or RB set in each monitored time slot. The number of such blind decodings may depend on the number of RB interlaces that are (pre-)configured for each resource pool and / or RB set, the number of RB sets that are (pre-)configured for a resource pool, and / or the number of (pre-)configured resource pools for SCI monitoring.

[0132] When the WTRU successfully decodes the SCI in time slot (t), the WTRU may receive information from the corresponding bit field included in the decoded SCI.

[0133] In one example, the WTRU may decode the SCI information associated with the TB carried in the PSSCH transmission and receive the SCI information. The priority level (e.g., L1) assigned to the TB, the broadcast type and / or source ID and destination ID of the TB. The broadcast type of the TB may be indicated as unicast, groupcast, or broadcast.

[0134] In one example, the WTRU may decode and receive SCI information associated with the COT (e.g., the current COT) that transmits the decoded SCI, such as remaining COT duration, MCOT duration, COT start slot index, COT initiation / sharing indication, COT sharing for PSSCH / PSCCH indication, COT sharing for PFSCH indication, and / or channel congestion indication.

[0135] The remaining COT duration may be the remaining time of the COT used between the time slot in which the SCI is decoded and the end of the COT. The units of such remaining COT duration indication may be time units (e.g., ms) and / or number of time slots. For example, a remaining COT duration of 5 time slots indicated in the SCI received in time slot (t) may indicate that the current COT may include consecutive time slots from time slot (t+1) to time slot (t+5). In one example, the unit of the remaining COT duration may be a logical time slot of a resource pool for PSSCH / PSCCH transmissions carrying the decoded SCI. In another example, a physical time slot may be applied to indicate the duration. The WTRU may determine the number of logical time slots or time (e.g., ms) remaining in this COT relative to the maximum COT. In one case, based on this indicator and the remaining transmission indicator in the SCI, the WTRU may determine a time period and / or number of logical time slots within the COT that may not be scheduled for transmission and may therefore be applied to COT sharing. In one example, the value may be indicated using a Time Resource Indication Value (TRIV).

[0136] For the MCOT duration, the WTRU may determine the maximum COT duration of the ongoing COT based on this SCI indication.The maximum COT value indicated in this SCI field may be determined by the initiating WTRU for the COT corresponding to the CAPC configuration of the Type 1 LBT procedure being performed.

[0137] For the COT start slot index, the WTRU may determine the logical slot index of the first slot of the COT. In another example, when the WTRU decodes the SCI within the COT, the WTRU may determine the time period and / or number of logical slots within the COT based on the indicated COT start slot index and the MCOT duration indicated in the same SCI.

[0138] For the COT initiation / sharing indication, when this SCI indicator indicates COT initiation, the WTRU may determine that the received SCI may be transmitted by the WTRU that initiated the COT. The WTRU may further identify the initiating WTRU by the WTRU source and / or destination ID indicated in the same SCI. Similarly, when this SCI indicator indicates COT sharing, the WTRU may determine that the received SCI may be transmitted by the WTRU that shares the COT. The WTRU may further identify the shared WTRU by the WTRU source and / or destination ID indicated in the same SCI. In one example, a value may correspond to COT initiation (e.g., 0), and the value may be incremented by each WTRU that shares the COT (e.g., 1 may indicate the first WTRU that shares the COT, 2 indicates the second WTRU that shares the COT, and so on). The WTRU may determine the number of WTRUs that share the current COT based on this indication. When the number of WTRUs that share the COT may exceed a (pre)configured threshold, the WTRU may determine that the COT is not shared.

[0139] For example, COT sharing for PSSCH / PSCCH indication may indicate whether the current COT may be shareable and may be shared by another WTRU to perform PSSCH / PSCCH transmissions within the COT. When a shareable COT is indicated, the WTRU may perform the SLU channel access and resource selection procedures for COT sharing to perform PSSCH / PSCCH transmissions in the current COT.

[0140] The COT sharing for PSFCH indication may indicate whether one or more PSFCHs carrying HARQ feedback corresponding to one or more PSSCH / PSCCH transmissions within the current COT may be transmitted within the COT. When a shareable COT for PSFCH is indicated, the WTRU may perform the SLU channel access and resource selection procedure for COT sharing to perform PSFCH transmissions in the current COT.

[0141] The channel congestion indication may be an indication of the congestion status of the SLU channel. In one example, a binary channel congestion indication may be (pre)configured, and a value of one may indicate a congested channel, and a value of zero may indicate that the channel may not be congested.

[0142] The indication of SL time slots for sharing within the COT may be an indication of which SL time slots in the COT may be shared. In one example, a TRIV may be used to indicate a logical time slot offset, such as a logical time slot number between an SL time slot indicated by the SCI and an SL time slot indicated for sharing. In another example, a logical time slot index of an SL time slot for sharing may be indicated.

[0143] In one example, the WTRU may decode and receive one or more of the following SCI information associated with resource allocations (such as remaining transmission duration) for PSSCH / PSCCH transmissions performed within the current COT and / or frequency resource assignments for PSCCH transmissions.

[0144] The remaining transmission duration may be the number of consecutive time slots scheduled for PSCCH / PSSCH transmission in the remaining COT duration. For example, a time resource indication value (TRIV) may be used to indicate the number of remaining scheduled time slots. A TRIV of x in the SCI received in time slot (t) may indicate that the WTRU transmitting the decoded SCI may continue PSCCH / PSSCH transmission in the next x consecutive time slots from time slot (t+1) to time slot (t+x). In one example, the time slots applied in this indication may be logical time slots of a resource pool for PSSCH / PSCCH transmission carrying the decoded SCI, such as x consecutive time slots may be x consecutive logical time slots. In another example, physical time slots may be applied. In one example, the value may be indicated using TRIV.

[0145] The frequency resource assignment for the PSSCH may be an RB interlace index and / or an RB set index for a PSSCH transmission performed within the current COT. In one example, the WTRU may perform transmissions of TBs and / or different TBs within a COT using the same frequency resource assignment. In the SCI associated with each PSSCH transmission scheduled within the COT, the WTRU may indicate a frequency resource indication value (FRIV) value based on the frequency resource assignment, such as the index of the assigned starting RB interlace and the number of RB interlaces and / or RB sets assigned for PSSCH transmission. In this example, the FRIV value may be calculated based on the starting RB interlace and the number of RB interlaces for PSSCH transmission in each time slot within the COT. In another example, the WTRU may perform transmissions of TBs and / or different TBs within a COT using different frequency resource assignments (e.g., different RB interlace indices in one resource pool and / or RB set). In this example, the WTRU may indicate a frequency resource indication value (FRIV) in the SCI transmitted in time slot (t) calculated based on the frequency resource assignment of the PSSCH transmission in each of the consecutive time slots from (t) to (t+a), where a may be a (pre-)configured value for the resource pool. For example, in the case where a=2, the FRIV value indicated in the SCI transmitted in time slot (t) may be calculated based on the starting RB interlace and the number of RB interlaces of the PSSCH transmissions in time slot (t), time slot (t+1), and time slot (t+2).

[0146] In an example, the WTRU may decode and receive SCI information associated with a reservation of a COT and / or resources for transmission by a WTRU transmitting a decoded SCI, such as a COT / resource reservation interval and / or a COT / resource reservation window. Such reservation by the WTRU may indicate that the WTRU may perform channel access and resource selection for COT initiation to initiate a COT after the reservation interval or within the duration of the reservation window. The WTRU performing channel access based on such decoded SCI information may exclude the time slot associated with the reserved COT and / or the reservation window from the WTRU's SLU channel access and resource selection procedures for COT initiation.

[0147] The COT and / or resource reservation interval may be a time period in ms or number of slots between the current COT and / or resources indicated in the decoded SCI and the reserved COT and / or resources for transmission by the same WTRU for another TB. The range of the reservation interval may be (pre)configured in the resource pool, and the WTRU may determine the length of the interval based on the traffic periodicity of the SL service and / or application. The WTRU may reserve the same frequency resources as those used in the current COT within the reserved COT. The WTRU may reserve a COT of the same length as the length of the current COT. For example, the reserved COT length may be determined based on an association with the L1 priority of the TB indicated for transmission in the current COT. In another example, the reservation window may be (pre)configured in association with the length of the reserved COT. In another example, a reservation window associated with the indicated COT and / or resource reservation interval may be indicated in the same SCI. The WTRU may perform channel access and resource selection to initiate such a reserved COT within the (pre)configured window. In one example, the unit of COT and / or resource reservation interval may be a logical time slot of a resource pool for PSSCH / PSCCH transmission carrying decoded SCI. In another example, a physical time slot may be applied to indicate this interval time. In one example, the value may be indicated using TRIV.

[0148] The COT and / or resource reservation window may be a time period in ms or number of time slots after the end of the current COT indicated in the decoded SCI. The length of the window may be (pre)configured in the resource pool. In one example, the WTRU may determine the length of the window based on the remaining packet delay budget (PDB) of the TB transmitted in the current COT. In one example, the unit of the COT and / or resource reservation window may be a logical time slot of the resource pool used for the PSSCH / PSCCH transmission carrying the decoded SCI. In another example, a physical time slot may be applied to indicate this window length. In one example, the value may be indicated using TRIV.

[0149] In an example, the WTRU may decode SCI information associated with the HARQ process of the PSSCH / PSCCH transmission in time slot (t) and receive the SCI information, such as the HARQ process number and / or the HARQ feedback enable / disable indication. The HARQ process number may be a new data indicator and / or a redundancy version. The HARQ feedback enable / disable indication may be an indication of whether HARQ feedback is enabled and whether the PSFCH carrying HARQ ACK / NACK is expected for the PSSCH / PSCCH transmission.

[0150] In one example, the WTRU may decode and receive SCI information associated with the transmission configuration of the PSSCH / PSCCH transmission in time slot (t), such as the transmission configuration including the number of DMRS ports, DMRS mode, MCS value and / or MCS table indication.

[0151] In an example, the WTRU may decode SCI information associated with an SCI-2 transmission multiplexed with a PSSCH transmission in time slot (t) and receive the SCI information, such as an indication of the SCI-2 format and a beta offset value.

[0152] In one example, the WTRU may decode and receive one or more of the following SCI information associated with the WTRU's geographic location and the range requirement of a TB transmitted in a time slot (t): the WTRU's zone ID; and / or an index corresponding to a (pre)configured minimum communication range (MCR) requirement in meters.

[0153] In one example, the WTRU may decode and receive one or more of the following SCI information associated with the synchronization source of the WTRU performing the received PSSCH transmission in time slot (t): based on the indication of the synchronization source, the WTRU may determine that the transmission received in the COT was performed by a WTRU synchronized with a GNSS, gNB, SyncRef WTRU, or an internal WTRU clock; and / or the WTRU may determine the SLSSID of the SL synchronization signal of the indicated SyncRef WTRU.

[0154] In some cases, the WTRU may perform SCI decoding within the detected SL COT. When the WTRU decodes the SCI in slot (t) and detects the COT indicated in the SCI, the WTRU may determine one or more COT-specific PSCCH resources in which the WTRU may perform SCI decoding during the remaining duration of the detected COT. The COT-specific PSCCH resources may include: the number of (pre-)configured symbols in each slot included in the detected COT; and / or the number of (pre-)configured RBs in one or more RB interlaces scheduled for PSSCH transmission within the detected COT.

[0155] In one example, the WTRU may determine one or more COT-specific PSCCH resources based on the time (TRIV) and frequency (FRIV) indicated in the decoded SCI. The WTRU may determine the RB interlace that includes the PSCCH RB based on the PSSCH interlace index indicated in the FRIV. The WTRU may switch from blind decoding in each RB interlace (pre-)configured in the resource pool to performing COT-specific SCI decoding in the determined COT-specific PSCCH resources for the remaining duration of the detected COT. The WTRU may switch back to blind decoding of the SCI after the detected COT ends.

[0156] In another example, when the WTRU source and / or destination IDs indicated in the same SCI may not be (pre)configured by higher layers, the WTRU may determine to stop SCI decoding for the remaining COT duration indicated in the decoded SCI. In this case, the WTRU may not be (pre)configured to receive TBs transmitted within the detected COT. When SL DRX may be (pre)configured and enabled, the WTRU may enter an inactive state. The WTRU may determine the inactive state of micro-sleep, light sleep, and / or deep sleep based on the length of the remaining duration of the detected COT. The WTRU may wake up and resume SCI decoding (e.g., blind decoding) in the first SL timeslot after the detected COT ends.

[0157] In some cases, there may be an SLU channel access and resource selection procedure for COT sharing. In some cases, the WTRU may perform SCI sensing for access and resource selection. The WTRU may be triggered by a higher layer to perform SLU channel access and resource selection for COT sharing in a timeslot (n) for transmission of one or more TBs. As discussed herein, the WTRU may perform SCI sensing for triggered SLU channel access and resource selection for COT sharing.

[0158] One or more of the following information may be provided by higher layers to the WTRU for SCI sensing: resource pools and / or RB sets applicable to the SL channel and resource selection determination, such as an index indicating the resource pool and / or RB set; priority of the TB (priority TX ), where when SCI sensing may be triggered for transmissions of different TBs, the WTRU may determine this priority as the highest priority of the TB (e.g., the lowest L1 priority value); the number of RB interlaces (L1) to be used for PSSCH / PSCCH transmissions carrying TBs in one timeslot RB_interlace ); a remaining packet delay budget (PDB), wherein when SCI sensing may be triggered for transmissions of different TBs, the WTRU may determine the value of this remaining PDB as the minimum remaining PDB of the TBs; and / or a COT and / or resource reservation interval (PRT) when the traffic type of a TB is periodic and COT and / or resource reservation for another TB is enabled in the (pre)configuration of the indicated resource pool and / or RB set. rsvp_TX ).

[0159] The WTRU may determine a resource selection window (RSW), such as a time interval between time slots (n+T1) and (n+T2). The WTRU may determine T2 based on the indicated remaining PDB (e.g., T2 may be equal to the indicated remaining PDB value). The WTRU may determine T1 based on the processing time (e.g., T process,1 The (pre)configured processing time may indicate a time period for the WTRU to process the decoded SCI and measured RSRP within the SCI sensing window. In one example, the WTRU may use the time period for the WTRU to process the decoded SCI and measured RSRP based on its T process,1 The T1 value is determined by the capacity as the upper limit.

[0160] The WTRU may determine the number of transmissions (N TX ), including initial transmissions and retransmissions to be performed within the determined RSW. This determination may be based on the QoS requirements of the TB, such as priority, reliability, and / or latency. The WTRU may determine the corresponding total number (N) of SLU resources within the RSW. r_total ), for example N r_total Equal to N TX In another example, N r_total Can be equal to N TX Multiply by the number of RB interlaces for transmission. The WTRU may determine the number of RB interlaces to use for transmission based on the MCS and RB interlace configuration of the resource pool. Each SLU resource available for transmission may include the indicated number of RB interlaces in a timeslot and may be referred to herein as a candidate resource.

[0161] The WTRU may perform SCI sensing for SLU channel access and resource selection for COT sharing in each time slot (i) starting from time slot (n) until the determined N TX The transfer can be performed in the RSW until the number of transfers performed using the RSW is less than the determined N TX When the WTRU starts from time slot (n) until time slot (n+T2-T proc,1 ) performs SCI sensing for SLU channel access and resource selection for COT sharing in each time slot (i).

[0162] The WTRU may determine an SCI sensing window, such as the SCI sensing window between time slots (i-T0) and (i-T proc,0 ). The WTRU may be (pre)configured with a T0 value for the indicated resource pool and / or RB set. For example, when COT and / or reservation of resources for another TB is enabled in the (pre)configuration of the resource pool, the WTRU may be (pre)configured with a T0 value corresponding to the maximum length of the (pre)configured reservation interval. When COT and / or reservation of resources for another TB is disabled in the (pre)configuration of the resource pool, the WTRU may be (pre)configured with a T0 value corresponding to the maximum value of the (pre)configured COT length. The WTRU may be (pre)configured with a T0 value for a resource pool associated with an SCS (such as 1 timeslot for a 15kHz SCS). proc,0 value.

[0163] The WTRU may monitor the SCI in the PSCCH in the time slots belonging to the indicated resource pool within the determined sensing window, in addition to those time slots in which the WTRU performs transmissions. The WTRU may perform blind decoding in the (pre)configured lowest RB of each RB interlace that is (pre)configured for the indicated resource pool and / or RB set within each monitored time slot. When the WTRU successfully decodes the SCI in the time slots in the SCI sensing window, the WTRU may measure the RSRP of the DMRS associated with the detected PSSCH / PSCCH transmission. The WTRU may perform blind decoding based on the DMRS from time slots (i-T0) and (i-T1). proc,0 ) to process the decoded SCI and measured RSRP data.

[0164] In some cases, the WTRU may determine COT sharing based on SCI sensing. The WTRU may be triggered by higher layers to perform SLU channel access and resource selection for COT sharing in time slot (n) for transmission of one or more TBs. The WTRU may perform SCI sensing to determine whether the WTRU may perform COT sharing for transmission of the TBs.

[0165] The WTRU may be based on, for example, a time slot (tT proc,1 ) to determine whether to perform COT sharing in time slot (t) for each time slot within the RSW. When the WTRU determines the remaining COT duration (e.g., TRIV) indicated in the SCI decoded in the sensing window (e.g., including time slot (t)), the WTRU may detect the COT in time slot (t). The detected COT may be referred to herein as the current COT.

[0166] The WTRU may determine the number of available candidate resources (N) for COT sharing within the current COT based on one or more of the following SCI sensing information: r_COT ): Remaining COT duration (T remaining_COT ); Remaining transmission duration (T remaining_TX ); frequency resource assignments for PSSCH transmissions scheduled in the current COT, such as RB interleaving and / or RB set indices; and / or candidate resources for TB transmission, such as L in a time slot RB_interlace RBs are interwoven.

[0167] The WTRU may determine that the last time slot of the current COT may be time slot (t+T remaining_COT ), and between time slot (t) and time slot (t+T remaining_COT ) between which there is no transmission (N slot_no_tx ) can be (T remaining_COT -T remaining_TX ). For example, if the remaining COT duration and remaining transmission duration indicated for time slot (t) are 5 and 2 time slots respectively, the WTRU may determine that the number of time slots without scheduled transmissions in the current COT will be 3 time slots.

[0168] The WTRU may determine the number of available candidate resources (N) within the current COT for COT sharing. r_COT). This number may be the sum of one or more of the number of available candidate resources in a time slot determined in the absence of a transmission within the current COT and / or the number of available candidate resources in a time slot scheduled for transmission within the current COT. For example, there may be only one COT referred to as a shared current COT, and there may be two types of time slots within the shared current COT: Type 1 being time slots not occupied by transmissions by a WTRU initiating the COT, and Type 2 being time slots occupied by transmissions by a WTRU initiating the COT. In unoccupied time slots, the number of resources may be equal to the number of interlaces per time slot multiplied by the number of unoccupied time slots, and in occupied time slots, the number of resources may depend on how many interlaces are occupied by the WTRU initiating the COT, so the number may be calculated based on the number of unused interlaces multiplied by the number of occupied time slots; the total resources may be the sum of these two types of numbers.

[0169] For the number of available candidate resources in the determined time slots that have no transmission in the current COT, the WTRU may determine this number as N slot_no_tx ×floor(M / L RB_interlace ), where N slot_no_tx M may be the number of time slots without transmission in the current COT, M may be the (pre-)configured number of RB interlaces of the indicated resource pool and / or RB set, and floor(M / L RB_interlace ) can be the number of available candidate resources in each such time slot.

[0170] For the number of available candidate resources in the time slots scheduled for transmission in the current COT, the WTRU may determine this number as T remaining_TX ×floor((M–N assigned_interlace ) / L RB_interlace ), where T remaining_TX is the number of time slots with scheduled transmissions in the current COT, M is the (pre-)configured number of RB interlaces for the indicated resource pool and / or RB set, N assigned_interlace is the number of assigned / occupied RB interlaces, and floor((M–N assigned_interlace ) / L RB_interlace ) is the number of available candidate resources in each such time slot.

[0171] In SCI sensing, the WTRU may also determine whether the current COT may overlap with the reserved COT and / or resources based on the decoded SCI information associated with the reservation of the COT and / or resources for the transmission. Such SCI information may include the COT and / or resource reservation interval (e.g., for semi-persistent reservation) and the COT and / or resource reservation window (e.g., for retransmission reservation). The WTRU may determine one or more time slots within the RSW included in such COT and / or resource reservation. When the time slot is included in the current COT, the WTRU may determine that the current COT may overlap with such reserved COT and / or resources. The WTRU may associate an L1 priority (e.g., an L1 priority indicated in an SCI from which the COT and / or resource reservation may be decoded) and a measured RSRP value (e.g., an RSRP value measured on a DMRS of a PSCCH and / or PSSCH transmission including the SCI from which the COT and / or resource reservation may be decoded) with the determined overlap.

[0172] The WTRU may determine whether to share the current COT based on one or more of the following information: (pre)configured COT sharing enable / disable in the resource pool; COT sharing indicated by the PSSCH / PSCCH associated with the current COT, such as an indication included in the SCI in which the current COT information may be decoded; the determined number of available candidate resources (N) for COT sharing. r_COT ); a channel congestion indication associated with the current COT, such as an indication included in an SCI in which the current COT information may be decoded; an L1 priority (priority) of a TB transmitted in the current COT COT ), broadcast type, WTRU source and / or destination ID; L1 priority of the TB to be transmitted by the WTRU (priority TX ), broadcast type, WTRU source and / or destination ID; the determined overlap between the current COT and the reserved COT and / or resources and the associated L1 priority (priority resv ) and RSRP values; the distance to the WTRU that may have initiated the current COT; the measured RSRP of the PSCCH DMRS and / or PSSCH DMRS associated with the SCI carrying information of the current COT; the measured congestion level (e.g., SL U CBR and RSSI); the broadcast type of PSSCH / PSCCH transmissions within the COT by the WTRU that initiated the COT; the WTRU source and / or destination ID of the WTRU that initiated the COT; a COT initiation and / or sharing indication in the SCI; and / or an indication of SL time slots for sharing within the COT.

[0173] The WTRU may determine whether to share the current COT based on one or more conditions.

[0174] In an example, when COT sharing is (pre)configured to be enabled in the indicated resource pool, the WTRU may determine to share the current COT.

[0175] In one example, when the COT sharing indication indicates that the current COT may be shared, the WTRU may determine to share the current COT.

[0176] In one example, when the L1 priority (priority) of the TB to be transmitted TX ) is above a threshold value (pre) configured for the resource pool, the WTRU may determine to share the current COT. In another example, such a threshold value may be associated with a channel congestion state having a higher threshold value for a congested channel (e.g., when the channel congestion indication associated with the current COT may be one). The WTRU may determine a threshold value corresponding to the value of the channel congestion indication associated with the current COT. This association may prioritize WTRUs with high priority TBs in COT sharing.

[0177] In one example, when the L1 priority (priority) of the TB to be transmitted TX ) may be equal to or higher than the L1 priority (priority) associated with the TB transmitted in the current COT COT ), the WTRU can determine to share the current COT.

[0178] In one example, the WTRU may determine to share the current COT when one or more conditions (e.g., two conditions) are met: an indication of COT initiation in the SCI decoded in the current COT; and / or a priority value (priority value) of the TB to be transmitted in the COT. TX ) is lower than or equal to the priority value indicated in the SCI decoded in the current COT (Priority COT ), such as the priority of the TB to be transmitted is higher than or equal to the priority of the TB transmitted in the COT. Since the priority indicated by the initiating WTRU in the COT is used to set the LBT and resource selection parameters to acquire and initiate the COT, it may be unfair to other non-3GPP systems in the unlicensed spectrum that another WTRU can share the COT to transmit a TB with a lower priority.

[0179] In one example, the WTRUs may determine to share the current COT when the broadcast type of the TB transmitted in the current COT is unicast and the WTRU source and destination ID pair of the unicast transmission and the WTRU source and destination ID pair of the TB to be transmitted are associated with the same unicast SL (e.g., the WTRUs may share the current COT for TBs associated with the same unicast link). When two WTRUs establish a unicast SL between each other, each WTRU may be (pre-)configured with a pair of unidirectional WTRU source and destination IDs associated with the transmission of the unicast SL. The two WTRUs may exchange WTRU source and destination ID information via RRC connection establishment and / or configuration signaling so that each WTRU may associate two pairs of WTRU source and destination IDs with the same unicast SL.

[0180] In one example, the WTRU may determine to share the current COT when the WTRU initiating the COT is a peer WTRU with a unicast link (pre)configured between the initiating WTRU and the WTRU sharing the COT. Each WTRU may indicate a pair of WTRU IDs in the SCI of the PSSCH / PSCCH transmission to the peer WTRU for unicast link traffic as discussed herein. Thus, when the COT initiation is indicated in the SCI, the WTRU may determine that the initiating WTRU may be a peer WTRU of the (pre)configured unicast link when the source and destination WTRU ID pair indicated in the same SCI is (pre)configured for a unicast link. In one case, the WTRU may share a COT initiated by a peer WTRU of a (pre)configured unicast link and perform a PSSCH / PSCCH transmission to the peer WTRU (e.g., the initiating WTRU) for traffic associated with the unicast link. In this case, COT sharing may be specifically applied to traffic of a unicast link carried in an SL transmission between two WTRUs that are (pre)configured for a unicast link. In another case, the WTRU may share a COT initiated by a peer WTRU of a (pre-)configured unicast link and perform PSCCH / PSCCH transmissions for traffic associated with the unicast, multicast and / or broadcast links operated by the WTRU.

[0181] In one example, when the broadcast type of a TB transmitted in the current COT is multicast, and the WTRU destination ID of the multicast transmission is the same as the WTRU destination ID of the TB to be transmitted, the WTRU may determine to share the current COT, such as the WTRU may share the current COT with transmissions of TBs associated with the same multicast SL.

[0182] In one example, when the transmission type of a TB transmitted in the current COT is broadcast, and the WTRU destination ID of the broadcast transmission is the same as the WTRU destination ID of the TB to be transmitted, the WTRU may determine to share the current COT, such as the WTRU may share the current COT with transmissions of TBs associated with the same broadcast SL.

[0183] In one example, when the SCI decoded in the current COT indicates COT sharing, the WTRU may determine that the COT is not shared, such as the COT may already be shared by another WTRU. In this case, the COT initiated by the WTRU may be shared by no more than one WTRU. However, in multicast and / or broadcast transmissions, it may be beneficial for multiple WTRUs to share a COT for SL services associated with the same multicast and / or broadcast link. Therefore, in another case, when the SCI decoded in the current COT indicates COT sharing and the WTRU is a member of the group indicated by the WTRU destination ID in the SCI decoded in the current COT, the WTRU may determine that the COT is shared. The WTRU may share the COT and perform transmission of TBs associated with the same WTRU destination ID indicated in the SCI received in the COT, such as services belonging to the same multicast and / or broadcast link.

[0184] In one example, sharing of a COT by one or more WTRUs such as discussed herein may be enabled or disabled by (pre)configuration of a resource pool. In addition, when such sharing is enabled, a maximum number of shared WTRUs may be (pre)configured in the resource pool. When a WTRU detects a sharable WTRU and determines that the value of the COT sharing indication is lower than the (pre)configured maximum number of shared WTRUs for the COT, the WTRU may determine that the COT is shared. Otherwise, the WTRU may determine that the COT is not shared.

[0185] The WTRU may determine that the COT is shared when the synchronization source indicated in the SCI decoded in the current shareable COT is the same as the WTRU's own synchronization source and / or belongs to the same (pre-)configured synchronization source group. In another example, when both the indicated synchronization source and the WTRU's own synchronization source are SyncRef WTRUs, the WTRU may determine that the COT is shared when the indicated SLSSID is also the same as the SLSSID of the WTRU's own SyncRef WTRU, such as the initiating WTRU and the sharing WTRU of the COT may be synchronized with the same SyncRef WTRU. When the SLSSIDs are different, the WTRU may determine that the COT is not shared.

[0186] In one example, when the determined number of available candidate resources for COT sharing (N r_COT) is equal to or greater than a (pre)configured threshold, the WTRU may determine to share the current COT. In one example, the value of such a threshold may be associated with the L1 priority of the TB to be transmitted, a large threshold corresponding to a high L1 priority. In another example, the value of such a threshold may also be associated with a channel congestion state, a large value corresponding to a channel congestion indication of one. The WTRU may determine such a threshold corresponding to the L1 priority of the TB to be transmitted and / or the value of the channel congestion indication associated with the current COT. When such a (pre)configuration does not exist or the (pre)configured value is zero, the WTRU may determine to share the current COT without taking into account the determined number of available candidate resources for COT sharing.

[0187] In one example, when the determined available candidate resources overlap with a reserved COT and / or resource, and the RSRP associated with the overlap (e.g., determined in SCI sensing) is above a (pre-)configured threshold, the WTRU may determine not to share the current COT. In one example, the WTRU may determine not to share the current COT based on the L1 priority (priority resv ) and the L1 priority of the TB to be transmitted (priority TX ) to determine the value of such a threshold. In another example, the value of such a threshold may be associated with channel congestion. The WTRU may determine the value of such a threshold with respect to the priority resv , Priority TX The RSRP threshold corresponding to the channel congestion indicated in the SCI of the current COT. This ensures that WTRUs with higher priority TBs share the same current COT, especially in congested channels.

[0188] In an example, the WTRU may determine to share the current COT when the distance between the WTRU itself and the WTRU initiating the current COT is below a (pre)configured threshold. The WTRU may determine such distance (e.g., in meters) based on its own position information (such as GNSS geographical coordinates and / or a zone ID indicated in the SCI carrying the information of the current COT). In an example, the (pre)configured threshold may be an MCR requirement indicated in the SCI carrying the information of the current COT.

[0189] In one example, the WTRU may determine that the current COT is shared when the RSRP measured on the PSCCH DMRS and / or PSSCH DMRS associated with the SCI carrying information of the current COT is above a (pre)configured threshold. In one example, such a threshold may be (pre)configured to be related to the L1 priority (priority) of the TB to be transmitted. TX ) and / or the L1 priority (priority) associated with the TB transmitted in the current COT COT ). A lower threshold may be associated with a higher priority (priority) of the TB to be transferred. TX) so that WTRUs with higher priority TBs can be prioritized to share the current COT.

[0190] In one example, the WTRU may determine the shared current COT when the measured congestion level is below a (pre)configured threshold. The WTRU may determine such congestion level based on one or more (pre)configured measurements performed in LBT sensing and / or SCI sensing. These measurements may include: RSSI measured in the sensing timeslot, RSSI measured in the SL timeslot, RSRP measured on the PSCCH DMRS, PSSCH DMRS associated with the decoded SCI and / or the number of timeslots where the LBT sensing results of the channel may be busy, etc. The WTRU may perform such congestion level measurements within a (pre)configured SLU channel congestion measurement window. The measured channel congestion level may be expressed as the ratio of the number of timeslots where the measured value (e.g., RSSI or the number of busy sensing timeslots) exceeds the (pre)configured level to the total number of measured sensing and / or SL timeslots in the resource pool. In one example, the (pre)configured threshold is proportional to the L1 priority (priority) of the TB to be transmitted. TX ) and / or the L1 priority (priority) associated with the TB transmitted in the current COT COT ). A higher threshold may be associated with a higher priority (priority) of the TB to be transmitted. TX ), so at a given congestion level, WTRUs with higher priority TBs may be allowed to share the current COT. When there is an indication of SL timeslot sharing in the COT, the WTRU may determine to share the current COT.

[0191] In some cases, the WTRU may select resources within the shared COT. When the WTRU determines to perform COT sharing, the WTRU may determine available candidate resources for transmission of TBs within the current COT based on one or more factors, such as: the total number of resources determined for transmission of TBs (N r_total ); the determined available candidate resources (N r_COT ); L1 priority of the TB to be transmitted (Prio TX ).

[0192] The WTRU may be (pre)configured with a maximum number of available candidate resources (N) for COT sharing in a resource pool. r_max ), and the WTRU may determine the number of resources to use (N r_share ) is N r_share =Nr _max In another example, such a value may be associated with an L1 priority. The WTRU may select an L1 priority based on the (pre-)configured association and the L1 priority (priority) of the TB to be transmitted. TX) to determine N r_max The maximum resource determination may allow the current COT to be shared between WTRUs.

[0193] In another method, the WTRU may be (pre)configured with respect to the determined available candidate resources (N r_COT ) ratio (P%). The WTRU may calculate the number of resources to be used in the current COT (N r_share ) is determined as N r_share =Nr _COT × P%. The value of P may be associated with the L1 priority, and the WTRU may select a TB to be transmitted based on the L1 priority (priority TX ) to determine the value of P. In another example, the value of P may be associated with the channel congestion status. The WTRU may determine the value of P based on the L1 priority (priority TX ) and / or a channel congestion indication associated with the current COT determines the value of P. Therefore, when the channel is not congested, more resources can be selected.

[0194] When the WTRU is not (pre-)configured with such N r_max and / or P ratio, the WTRU may determine to use all determined available candidate resources in the shared current COT, N r_share =Nr _COT When the determined N r_share When it is greater than or equal to the total number of resources determined for transmission of TB (N r_share >=N r_total ), the WTRU may determine Nr _share The number of = N r_total In this case, the WTRU may complete the transmission of the determined TB in the shared current COT.

[0195] The WTRU may sort N in ascending order according to the RB interlace index and the time slot index. r_COT For example, the WTRU may first index the available candidate resources in a time slot in ascending order of the RB interlace index and then continue to index the candidate resources in the next time slot until the last time slot for sharing in the current COT. The WTRU may use an index such as r j The index of each available candidate resource is represented by the index j, where the index j can be (0, 1, N r_COT -1).

[0196] The WTRU may obtain r_COT N of these resources are selected for the transmission of TB r_shareThe WTRU may determine that there are one or more available candidate resources in each time slot of the shared current COT that may not include a scheduled transmission.

[0197] The WTRU may determine which N to use based on one or more of the following: r_share available candidate resources for transmission of a TB: random selection; WTRU source and / or destination ID; timeslot index; broadcast type; and / or (pre-)configured resource pattern.

[0198] The WTRU can select from (0, 1, N r_COT -1) randomly select N r_share The WTRU may determine N based on the broadcast type and value of the associated WTRU source and / or destination IDs. r_share In one example, for unicast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU source ID and / or the WTRU destination ID. In addition, the WTRU may also include the time slot index in the initialization of the seed. In another example, for multicast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU destination ID and / or the (pre-)configured group member IDs. For broadcast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU destination ID.

[0199] The WTRU may be (pre)configured with a set of available candidate resource patterns. For example, the WTRU may select a first set of consecutive N r_share Available candidate resources, the indexes of these available candidate resources are (r0, r1, r Nr_sharing ) indicates. When N r_share =N r_total , the WTRU may perform all transmissions of the TB within the first contiguous available candidate resources within the shared current COT.

[0200] In another example, the WTRU may select a set of consecutive N r_tx_sharing Available candidate resources, the indexes of these available candidate resources are represented by (r offset 、r offset+1 、r offset+Nr_sharing). The WTRU may determine the available candidate resource group offset value based on the WTRU source and / or destination ID and the WTRU destination ID for unicast transmissions. The WTRU may determine the available candidate resource group offset value based on the WTRU destination ID and / or the (pre-)configured multicast member IDs for multicast transmissions. The WTRU may determine the available candidate resource group offset value based on the WTRU destination ID for broadcast transmissions. For example, the WTRU may determine such an offset by performing a modulo function using the values ​​of the WTRU ID and / or the multicast member ID and the number of available candidate resource groups, which may be equal to floor(N r_COT / N r_share ).

[0201] In another method, the WTRU determines the frequency resources for PSSCH / PSCCH transmission to share the COT based on the WTRU source and / or destination ID. The frequency resources may include one or more RBs, RB interlaces, subchannels and / or RB sets. The WTRU may be (pre)configured with a set of such frequency resources, each frequency resource represented by an index. The WTRU may perform a modulo operation of the total number of resources and the digital version of the WTRU source and / or destination ID to determine the index of the starting frequency resource for the PSSCH / PSCCH transmission. In another example, the WTRU may select a frequency resource based on a resource group and / or COT reservation information. Before performing a selection based on the WTRU ID as discussed above, the WTRU may exclude the reserved frequency resources from the (pre)configured set of frequency resources.

[0202] In some cases, there may be a frequency reuse based COT sharing COT, where the frequency reuse based COT sharing scheme may be (pre)configured in the resource pool as enabled or disabled. When the scheme is (pre)configured in the resource pool as disabled, the WTRU may share the COT by performing SL transmissions in the remaining unused SL slots of the shared COT (e.g., without scheduled transmissions) after the Type 2 LBT procedure as described herein. When the scheme is (pre)configured in the resource pool as enabled, the WTRU may share the COT by performing SL transmissions in the remaining unused slots (e.g., as discussed herein) and using the available RB interlaces in the SL slots with existing SL transmissions.

[0203] The WTRU may determine the number of unused time slots in the COT to be shared based on the received SCI indication including the remaining COT duration, the remaining scheduled transmissions, the maximum COT duration and / or the logical time slot index of the starting time slot of the shared COT.

[0204] The WTRU may determine one or more available RB interlaces in a SL slot with an existing SL transmission in a shared COT based on the frequency assignment in the SCI of the PSSCH / PSCCH transmission within the COT. In one case, the WTRU may randomly select one or more available RB interlaces for a SL transmission multiplexed with an existing SL transmission in the shared COT (e.g., by an initiating WTRU).

[0205] In another case, the WTRU may determine which of the available RB interlaces to use for transmission to share the COT based on the synchronization source indicated in the SCI decoded in the COT. In one example, when the indicated synchronization source is the same as the WTRU's own synchronization source (e.g., GNSS, same gNB and / or same SyncRef WTRU) and / or belongs to the same (pre-)configured synchronization source group, the WTRU may apply any available RB interlace for SL transmission. A common synchronization source may mitigate inter-RB interference between transmissions from different WTRUs multiplexing frequency domains.

[0206] When the indicated synchronization source is different from the WTRU's own synchronization source and / or does not belong to the same (pre-)configured synchronization source group, the WTRU may not perform frequency reuse based COT sharing. In this case, the WTRU may select one or more RB interlaces for transmission among the available RB interlaces based on the muting (pre-)configuration. In one example, the WTRU may mute (e.g., not select and not transmit in) RB interlaces adjacent to the RB interlace used for SL transmission in the COT (e.g., by the initiating WTRU).

[0207] In addition, when the WTRU determines to perform such frequency reuse-based COT sharing, the WTRU may determine the maximum power of the WTRU's SL transmission multiplexed with the existing SL transmission in the SL time slot based on: the measured power level (e.g., RSSI) of the existing SL transmission in the SL time slot in the shared COT; and / or the power spectral density (PSD) requirement imposed by the regulation in the channel (e.g., a maximum value of P0 dBm / MHz).

[0208] The WTRU may determine the maximum power of the SL timeslot to be the maximum PSD specified in the regulation P = P0 (dBm / MHz) × total transmission bandwidth (MHz), where the total transmission bandwidth may be the LBT BW. The WTRU may determine the maximum power of the SL transmissions performed in the same timeslot to be PP measured , where P measured It can be the power level measured in the SL timeslot.

[0209] In one method, a shared WTRU may share the current COT by performing a PSSCH / PSCCH transmission in a time slot that includes a PSSCH / PSCCH transmission by the WTRU that initiated the current COT. The initiating WTRU may indicate a gap for Type 2 LBT in the SCI of each PSSCH / PSCCH transmission. In another example, the WTRU may be (pre)configured with such a gap at the end of a PSSCH / PSCCH transmission.

[0210] The shared WTRU may determine the frequency resources scheduled for PSSCH / PSCCH transmission by the initiating WTRU based on the frequency assignment information in the decoded SCI. The shared WTRU may select frequency resources such as a set of RBs, RB interlaces and / or subchannels for PSSCH / PSCCH transmission. In one example, the shared WTRU may determine such frequency resource allocation by excluding the decoded frequency resources from the (pre-)configured resource pool and selecting frequency resources among the remaining frequency resources based on the WTRU source and / or destination ID.

[0211] The WTRU may perform Type 2 LBT, such as Type 2B LBT, in the indicated or (pre)configured gaps. When the channel is available, the WTRU may perform PSSCH / PSCCH transmissions using the determined frequency resources in the time slots including the PSSCH / PSCCH transmission by the initiating WTRU. When the channel is not available, the physical layer may indicate LBT failure to higher layers.

[0212] In some cases, the WTRU may send a PSSCH / PSCCH transmission in the shared current COT. The WTRU may determine N within the shared current COT. r_share The WTRU may perform LBT sensing for SLU channel access and resource selection when there is a gap in the PSSCH / PSCCH transmission performed for COT sharing. The WTRU may determine to perform LBT sensing after such a gap of 25us (e.g., type 2A LBT channel access as discussed herein). The WTRU may determine to perform LBT sensing after such a gap of 16us (e.g., type 2B LBT channel access as discussed herein). The WTRU may determine to perform LBT sensing after such a gap of less than 16us (e.g., type 2C LBT channel access as discussed herein). The WTRU may perform LBT sensing on the bandwidth of the resource pool and / or RB set indicated for SCI sensing.

[0213] In some cases, the WTRU may select Type 2 LBT procedures for COT sharing. The WTRU may allow sharing of a COT that is initiated and / or shared by the WTRU based on one or more scenarios (eg, where the WTRU performs an action).

[0214] In one example scenario, when the COT is to be shared by another WTRU's PSCCH / PSSCH transmission, the WTRU may set the value of COT sharing indicated by the PSSCH / PSCCH in the SCI for the PSSCH / PSCCH transmission in the COT to "enabled".

[0215] In one example scenario, when the COT is to be shared by another WTRU's PSFCH transmission, the WTRU may set the value of COT sharing indicated by the PSFCH in the SCI for PSSCH / PSCCH transmissions in the COT to "enabled".

[0216] In an example scenario, the WTRU may not transmit in a (pre)configured type 2 LBT opportunity (e.g., gap period) at the end of the last PSCCH / PSSCH transmission scheduled in the COT (e.g., COT end gap). The WTRU may perform rate matching for a shortened PSSCH / PSCCH transmission in the last PSCCH / PSSSCH slot. In an example, such a gap may be (pre)configured as one symbol, such as in a 14-symbol SL slot, the last PSCCH / PSSCH transmission may occupy 13 symbols in the COT, and the last symbol may be empty.

[0217] A WTRU that detects a current COT that can be shared may perform a Type 2 LBT procedure at the start of a Type 2 LBT opportunity to acquire a channel before sharing the COT. Type 2 LBT procedures may include Type 2A, Type 2B, and / or Type 2C LBT procedures.

[0218] When performing Type 2A LBT procedures, the WTRU may transmit immediately after sensing that the channel is available within the 25us sensing period. During the sensing period, the WTRU may perform LBT sensing on two 9us sensing slots, and when the channel is available in both sensing slots, the WTRU may determine that the channel is available.

[0219] When performing Type 2B LBT procedures, the WTRU may perform a transmission immediately after sensing that the channel is available for a sensing period of 16us. The WTRU may perform LBT in a sensing slot of 9us and may determine that the channel is available when the channel is sensed to be available for a total of at least 5us and at least 4us within the sensing slot.

[0220] When performing Type 2C LBT procedures, the WTRU may perform transmissions without performing sensing. The duration of such transmissions without sensing may be up to 584 us.

[0221] When the WTRU performs Type 2A or Type 2B LBT to acquire a channel to share a COT, the WTRU may transmit until the maximum duration (MCOT) of the shared COT ends. The WTRU may determine this information based on the SCI indication including the remaining COT duration, the MCOT, and / or the logical slot index of the starting slot of the COT received in the COT. The WTRU may stop transmitting in the shared COT when the MCOT duration of the shared COT ends.

[0222] When the WTRU performs Type 2C LBT to acquire a channel to share the COT, the WTRU may perform SL transmission within the minimum duration between 584us and the remaining COT duration until the maximum duration (e.g., MCOT) ends.

[0223] In one method, the WTRU may determine a Type 2 LBT opportunity within a COT based on one or more SCI indications received in the COT, such as the remaining scheduled transmission duration, the remaining COT duration, and / or an index of a logical time slot of the COT. At the start of a detected Type 2 LBT opportunity in a shareable COT, the WTRU may perform one of the Type 2 LBT procedures described herein. Prior to sharing a COT, the WTRU may determine which Type 2 LBT procedure to perform (e.g., 2A, 2B, or 2C) based on one or more of the following: the L1 priority (priority) of the TB to be transmitted in the shared COT; TX ); L1 priority associated with the TB transmitted in the current COT (priority COT ); the remaining PDB of the TB to be transmitted in the shared COT; the duration of the transmission of the TB in the shared COT; the remaining duration of the resource selection window for the TB to be transmitted in the shared COT; the broadcast type of the TB to be transmitted in the shared COT; the type of SL channel to share the COT (e.g., PSFCH or PSSCH / PSCCH transmission); the measured channel congestion level (e.g., SL CBR, CO, RSSI); the channel congestion indication in the SCI transmitted by the initiating WTRU in the COT; the measured RSRP of the PSCCH and / or PSSCH received in the COT; and / or the distance between the initiating WTRU and the shared WTRU.

[0224] When the priority (priority) associated with a WTRU's transmission TX) may be higher than a (pre)configured threshold and the transmission duration may be less than 584us (e.g., PSSCH / PSCCH transmission using 60kHz SCS on one SL timeslot), the WTRU may perform a Type 2C LBT procedure. In another case, when the remaining PDB of a TB and / or the remaining duration of the resource selection window may be less than a (pre)configured threshold and the transmission duration may be less than 584us, the WTRU may perform a Type 2C LBT procedure.

[0225] When the WTRU transmits one or more PSFCHs in the shared COT, the WTRU may perform Type 2C LBT procedures.

[0226] When the SL transmission duration exceeds 485us, the WTRU may determine whether to use Type 2B or Type 2A LBT procedures. In one case, the WTRU may be (pre)configured to perform Type 2A LBT for unicast and / or multicast transmissions and Type 2B LBT for broadcast transmissions.

[0227] In one case, if the priority of TB (priority TX ) is higher than or equal to a (pre)configured threshold, the WTRU may determine to perform Type 2A LBT, otherwise determine to perform Type 2B LBT. In another case, if the remaining PDB of the TB is less than or equal to a (pre)configured threshold, the WTRU may perform Type 2B LBT procedure, otherwise perform Type 2A LBT procedure.

[0228] In another case, there may be two criteria, such as when the channel congestion level is higher than or equal to a (pre)configured threshold (eg, first criterion), and when the priority of the TB (priority level) is higher than or equal to a (pre)configured threshold (eg, first criterion). TX ) is above or equal to a (pre)configured threshold (e.g., a second criterion), the WTRU may determine to perform a Type 2A LBT procedure (e.g., in a busy channel for a high priority TB, apply a longer LBT). If one or both criteria are not met, the WTRU may determine to perform a Type 2B LBT procedure. When the channel is busy, the WTRU may perform longer sensing to reduce contention for a high priority TB.

[0229] When the channel congestion level is below a (pre)configured threshold, the priority of the TB (priority TX ) is higher than or equal to a (pre)configured threshold, the WTRU may determine to perform a Type 2B LBT procedure. When the priority is below the threshold, the WTRU may determine to perform a Type 2A LBT procedure. When the channel is not busy, the WTRU may perform shorter sensing for high priority TBs to acquire the channel faster.

[0230] The WTRU may determine the channel congestion level based on measurements of SL CBR, CO and / or RSSI of the channels (pre)configured for LBT. In another example, the WTRU may determine the information based on the congestion level indicated in the COT by the initiating WTRU.

[0231] In one example, the (pre)configured priority threshold applied in the Type 2 LBT determination discussed above may be based on the priority (priority COT ).

[0232] Figure 3 An example of sharing a WTRU determination for a Type 2 LBT for COT sharing is illustrated. As shown, there may be an initiating WTRU 310, a sharing WTRU 311 with priority 1, and a sharing WTRU 312 with priority 2. Time is shown on the horizontal axis, however, frequency is not intended to be shown on the vertical axis. As shown, WTRU 310 may initiate a COT, which may then be shared by WTRUs 311 and 312. In one example, each WTRU may use the same, partially the same (i.e., overlapping), or different frequency resources since the transmissions of one WTRU will not overlap in time.

[0233] Since the Type 2B LBT procedure takes less time to acquire a channel when the channel is available, the priority-based Type 2 LBT selection may enable WTRUs with high priority TBs to share the COT more easily when multiple WTRUs attempt to share the COT. This may be applicable in low congestion scenarios where conflicts are not severe. Figure 3As shown in the example of , both WTRU 311 and WTRU 312 may detect an ongoing sharable COT (e.g., initiated by WTRU 310) and perform Type 2 LBT at the same Type 2 LBT opportunity. WTRU 311 may perform Type 2B LBT because the priority (Priority_1) may be above a threshold and associated with Type 2B LBT, and the measured CBR is below a (pre)configured threshold (e.g., where CBR is an SL measurement of a resource pool; the SL measurement is an indication of congestion in the channel). WTRU 312 may perform Type 2A LBT because the priority (Priority_2) of its TB may be below a threshold and associated with Type 2A LBT (e.g., the measured CBR is also below the threshold). WTRU 311, which has a transmission of a higher priority TB, may share the COT with WTRU 310, and WTRU 312 may detect a busy channel due to the transmission of WTRU 311 and continue to obtain channel access (e.g., repeating one or more procedures referenced herein). In one case, the WTRU 311 may transmit a reservation signal 303, such as a cyclic prefix extension (CPE), at the end of the COT so that the WTRU may start transmission of its higher priority TBs.

[0234] In another example, if the distance between the WTRU and the intended target WTRU of the transmission is higher than or equal to a (pre-)configured threshold, the WTRU may determine to perform Type 2A LBT, otherwise determine to perform Type 2B LBT.

[0235] In another example, the WTRUs sharing the COT may perform Type 2 LBT procedures based on Type 2 channel access information indicated in the SCI of the PSSCH / PSCCH transmission in the COT. In this case, the WTRU initiating and / or sharing the COT may indicate the following information in the SCI of the PSSCH / PSCCH transmission in the COT: when the COT is to be shared by the PSCCH / PSSCH transmission of another WTRU, the value of COT sharing indicated by the PSSCH / PSCCH is "enabled"; when the COT is to be shared by the PSFCH transmission of another WTRU, the value of COT sharing indicated by the PSFCH is "enabled"; the start of the time period for the Type 2 LBT procedure (e.g., logical slot index, symbol index with slots, (pre-)configured Type 2 LBT opportunity, etc.); the type of Type 2 LBT to be performed for sharing the COT (2A, 2B or 2C); the length of the gap reserved for Type 2 LBT before starting transmission to share the COT; an indication of the SL slots that can be used for sharing in the COT; and / or COT times, such as MCOT, remaining COT duration and / or COT start slot index.

[0236] In some cases, the WTRU may perform the transmission of a channel reservation signal and / or CPE after the last PSCCH / PSSCH transmission scheduled in the COT has finished (e.g., as in Figure 3 ). In some instances, the WTRU may not perform a PSSCH / PSSCH transmission in the last symbol of the last SL timeslot scheduled in the COT. Instead, the WTRU may transmit a channel reservation signal and / or CPE from the beginning of the last symbol to maintain the initiated and / or shared COT. The WTRU may leave a gap of length Xus between the end of the channel reservation signal and / or CPE transmission and the end of the last symbol. In one example, the value of X may be explicitly indicated in an SCI bit field having log2(max(X)) bits, where max(X) is the maximum gap length (e.g., one symbol). In another example, the gap length may be indicated by an index in the SCI bit field. The index set may be (pre)configured to indicate a gap length of, for example, less than 16us, 16us, greater than 16us and less than 25us, and / or equal to or greater than 25us.

[0237] The WTRUs sharing the initiated and / or shared COT may determine to perform type 2 LBT channel access based on the gap length indicated in the SCI received in the COT. For example, when the indicated gap length is less than 16us, the WTRU may perform type 2C LBT channel access; when the indicated gap length is 16us, the WTRU may perform type 2B LBT channel access.

[0238] When the indicated gap length is greater than 16us and less than 25us, the WTRU may perform Type 2B LBT channel access. The WTRU may randomly select a 16us period within the gap to perform Type 2B LBT. In another approach, the WTRU may select the start time Type 2B LBT based on the priority of the TB to be transmitted in the shared COT. For example, when the priority is above a (pre)configured threshold, the WTRU may perform Type 2B LBT in the first 16us period of the gap. Otherwise, the WTRU may perform Type 2B LBT in the last 16us period of the gap.

[0239] In one case, when the indicated gap length is greater than 16us and less than 25us, the WTRU may be (pre)configured with Type 2X (e.g., Type 2A, 2B, or 2C) LBT channel access. In case of Type 2X LBT channel access, the WTRU may perform SL transmissions for a duration equal to the gap length indicated in the SCI received in the COT after sensing that the channel is idle. The Type 2X LBT duration may include a sensing slot (e.g., at the end of the duration).

[0240] The WTRU may perform transmission of a reservation signal and / or CPE between the end of a type 2 LBT channel access (e.g., type 2A LBT) and the start of a PSSCH / PSCCH transmission to share the COT. In one case, the WTRU may determine the duration of the channel reservation signal and / or CPE based on the priority of the TBs to be transmitted in the shared COT.

[0241] In one example, the reserved signal and / or CPE may have an integer (N Reserv / CPE ) number of (pre)configured time units (T unit ) duration (T Reserve / CPE ), such as T Reserve / CPE =N Reserv / CPE ×T unit The time unit can be the LBT sensing time slot (T SL )、LBT competition period (T contention ), 16us and / or 25us. Each SL priority can be (pre)configured with a corresponding N Reserv / CPE Higher priority (lower priority value) can be used with larger N Reserv / CPE Value associated.

[0242] A WTRU (e.g., desiring to share a COT) may determine the start of a PSSCH / PSCCH transmission (boundary of the first SL slot of the shared COT (t t t )) based at least in part on one or more of the SCI indications (including the MCOT, the remaining COT duration, the starting slot index, an indication of the SL slots for sharing, and / or the like as disclosed herein). sharing-start )) to share the COT. The WTRU may determine the start of a PSSCH / PSCCH transmission based at least in part on the determined start of a PSSCH / PSCCH transmission (t sharing-start ) and / or the duration of the channel reservation signal and / or CPE (T Reserve / CPE ) to determine the start of type 2 LBT channel access (e.g., type 2A LBT). For example, the start of type 2A LBT channel access may be at (t sharing-start -T Reserve / CPE -25) places.

[0243] Therefore, when multiple WTRUs attempt to share a detected COT starting from the same SL timeslot, a WTRU with a higher priority TB may perform a longer channel reservation signal and / or CPE transmission and thus start a Type 2 LBT channel access earlier in the gap. The resulting channel reservation signal and / or CPE transmission may cause a Type 2 LBT channel access failure for another WTRU with a lower priority TB (see, for example, Figure 3 for example).

[0244] In another example, the WTRU may be (pre)configured with a set of Type 2 LBT procedures (e.g., as discussed herein) in addition to other Type 2A / 2B / 2C procedures. Each Type 2 LTB may include N sensing slots, and the WTRU may determine that the channel is available before performing COT sharing. The number (N) may be associated with the priority and / or channel congestion level (e.g., CBR, channel occupancy (CO), and / or RSSI) of the TBs to be transmitted in the shared COT. In one example, when the congestion level exceeds a (pre)configured threshold, the WTRU may determine a large number (N) of sensing slots for high priority TBs. When the congestion level is below a (pre)configured threshold, the WTRU may determine a small number (N) of sensing slots for high priority TBs.

[0245] In one example, when the WTRU determines that there is no SL transmission in the SL timeslot immediately preceding the first SL timeslot of the shared COT (such as the last SL timeslot of the remaining transmissions indicated in the current shared COT), the WTRU may determine not to perform PSSCH / PSCCH transmissions of one or more TBs in the shared current COT. The WTRU may determine that there is no transmission when the WTRU does not detect SCI in the SCI decoding in the SL timeslot (e.g., the timeslot immediately preceding the first SL timeslot of the shared COT). For this example, the absence of SL transmissions does not necessarily mean that there is no transmission, but that there is no transmission (e.g., non-3GPP transmissions) for which the SCI cannot be decoded, and therefore sharing will not be possible. For example, the WTRU may only share the COT when the ongoing transmission is a SL transmission. In another example, the WTRU may determine that there is no transmission when the WTRU may measure an RSSI level below a (pre) configured threshold in the LBT sensing in the SL timeslot.

[0246] In some cases, a WTRU sharing a COT may perform non-continuous transmissions within the COT. The WTRU may determine the shared COT based on the SCI indications and / or conditions disclosed herein. For a first transmission on one or more symbols or one or more consecutive SL time slots, the WTRU may perform type 2 LBT channel access and transmission of a channel reservation signal and / or CPE based on the SCI indication or the priority of the TB to be transmitted in the COT. The first transmission may be, for example, PSFCH and / or PSSCH. The second transmission will depend on the availability of spectrum and may have one or more methods.

[0247] If the first transmission ends before the end of the shareable COT length, the WTRU may perform a second transmission and continue to share the COT when the following conditions are met: the WTRU may determine that the channel is available before the start of the second transmission, and the WTRU may perform LBT sensing immediately after the first transmission and determine the channel availability based on the LBT results over this period (e.g., the WTRU may perform LBT in each sensing time slot and determine that the channel is available when the results of all sensing time slots indicate that the channel is idle, such as the measured RSSI is below a (pre)configured threshold); and / or the WTRU may further perform a type 2 LBT channel access (e.g., a type 2A LBT channel access) and determine that the channel is available immediately before the second transmission. The WTRU may determine the shareable COT length (e.g., the number of shareable time slots in the COT) based on one or more of the following: the maximum COT (MCOT) associated with the priority as indicated in the CAPC configuration; the remaining scheduled transmission duration and / or the remaining COT; the COT starting time slot index; and / or an indication of the time slots shared.

[0248] If any of these conditions are met, the second transmission may occur. However, if these conditions are not met, the WTRU may not perform the second transmission and stop COT sharing. If the second transmission is not sent, the WTRU may perform a Type 1 LBT channel access to initiate another COT for the transmission of the TB that would have been carried in the second transmission that was never sent.

[0249] In this COT sharing method for non-continuous transmission, channel reservation signaling and / or CPE transmission may not be performed between the first transmission and the second transmission. If the channel is sensed as available within the COT, the WTRU sharing the COT with the first transmission may continue the second transmission to share the COT.

[0250] For each PSSCH / PSCCH transmission performed in the shared current COT, the WTRU may indicate one or more SCI information in the PSCCH on the shared current COT, transmitted TBs, transmission configuration, etc.

[0251] The one or more SCI information may include the L1 priority, broadcast type, WTRU source ID and / or destination ID of the TB transmitted in the PSSCH.

[0252] The one or more pieces of SCI information may include a remaining COT duration, which may be a remaining time of the COT between a time slot in which the SCI is transmitted and an end of the shared current COT.

[0253] The one or more SCI information may include the MCOT duration, where the maximum COT corresponding to the configuration of the Type 1 LBT performed to initiate the current COT may be indicated by the initiating WTRU. The maximum COT may be in ms or logical SL time slots. The sharing WTRU may replicate (e.g., resend) this information in its transmission within the shared COT.

[0254] The one or more SCI information may include a COT starting slot index, where the initiating WTRU may indicate the logical slot index of the first slot of the COT. When the WTRU decodes the SCI within the COT, the WTRU may determine the number of remaining slots within the COT that may be used for SL transmission based on the indicated starting slot index and the MCOT duration. The sharing WTRU may replicate this information in its transmission within the shared COT.

[0255] The one or more SCI information may include COT sharing for PSSCH / PSCCH indication, where the value of this indication may be enabled, which may be the same as the indication associated with the currently shared COT.

[0256] One or more SCI information may include COT sharing for PSFCH indication, which may be an indication of enabling / disabling according to the PSFCH resource configuration (pre) configured for the resource pool when HARQ feedback is enabled for TBs transmitted in PSSCH. When HARQ feedback is disabled for TBs transmitted in PSSCH, the indication may be disabling.

[0257] One or more SCI messages may include a COT initiation / sharing indication. The WTRUs sharing the COT may indicate a value corresponding to COT sharing (e.g., a value of one) in this SCI field for all transmissions performed to share the COT. In another example, when multiple WTRUs sharing a COT (e.g., in a resource pool (pre) configuration) are enabled, the sharing WTRU may increment the value in this field to indicate the number of WTRUs sharing this COT.

[0258] The one or more pieces of SCI information may include a channel congestion indication, where the value of this indication may be the same as the value indicated in the SCI associated with the shared current COT.

[0259] The one or more pieces of SCI information may include a remaining transmission duration, which may be the number of consecutive time slots scheduled for PSCCH / PSSCH transmission in the remaining shared current COT duration, for example, indicated in TRIV.

[0260] The one or more pieces of SCI information may include a frequency resource assignment for the PSSCH, which may be an RB interlace index and / or an RB set index for PSSCH transmissions performed within the shared current COT, for example, indicated by a frequency resource indication value (FRIV).

[0261] The one or more SCI information may include a COT and / or a resource reservation window, wherein the WTRU may indicate a value of zero when COT and / or resource reservation for retransmissions shared by COT may be disabled in the resource pool. r_total ) may be performed in the shared current COT, the WTRU may indicate a value of zero. The WTRU may indicate a value of a time period in ms or number of slots after the end of the shared current COT and / or between the end of the current COT and the start of the next reserved COT and / or the reservation period. The WTRU may determine the length of the window based on the remaining packet delay budget (PDB) of the TBs transmitted in the shared current COT.

[0262] The one or more pieces of SCI information may include a HARQ process number, a new data indicator, and / or a redundancy version.

[0263] One or more SCI information may include a HARQ feedback enable / disable indication, which may be an indication of whether HARQ feedback may be enabled and a PSFCH carrying HARQ ACK / NACK may be expected for PSSCH / PSCCH transmission. The WTRU may determine this indication based on the QoS requirements of the TBs transmitted in the shared current COT. In one example, QoS may be associated with a priority, as configured in a higher layer. In one example, to decide whether HARQ is enabled / disabled, the WTRU may use one or more QoS parameters (e.g., priority or other parameters).

[0264] The one or more pieces of SCI information may include a transmission configuration including a number of DMRS ports, a DMRS pattern, an MCS value, and / or an MCS table indication.

[0265] The one or more pieces of SCI information may include an indication of an SCI-2 format and a beta offset value.

[0266] One or more SCI information may include an indication of a synchronization source used by the shared WTRU. In one example, the value may indicate one of the sources including GNSS, gNB, SyncRef WTRU, and WTRU internal clock. In another example, an additional indication may be (pre)configured to indicate the SL SSID.

[0267] One or more SCI information may include a COT and / or resource reservation interval, wherein the WTRU may indicate a value of zero when the COT and / or resource reservation of another TB used for COT sharing may be disabled in the resource pool, and / or the WTRU may indicate a value of zero when a TB transmitted in the PSSCH may be non-periodic.

[0268] When COT and / or resource reservation of another TB for COT sharing is enabled in the resource pool and the TBs transmitted in the PSSCH are periodic, the WTRU may indicate the time period in ms or number of slots between the current COT and / or resources shared and the reserved COT and / or resources for transmission of another TB. This time period may be set to the COT and / or resource reservation interval (P rsvp_TX ).

[0269] By reserving such COT and / or resources, the WTRU may perform SL channel access to initiate a reserved COT corresponding to the priority indicated in the SCI of the transmission performed in the shared current COT. Additionally, the reservation window may be (pre)configured with a COT length (e.g., which may be associated with a specific COT length). The WTRU may initiate a reserved COT within the reservation window.

[0270] In another example, the COT and / or resource reservation for transmissions performed in the shared COT may be enabled / disabled in the (pre-)configuration of the resource pool. When this (pre-)configuration is disabled in the resource pool, the WTRU may set the indication to zero regardless of the traffic type of the TB transmitted in the shared current COT and / or the (pre-)configuration for the COT and the resource reservation for another TB.

[0271] Figure 4 refers to Figure 4A , Figure 4B and Figure 4C (The end of one figure transitions to the next figure and can be illustrated using the indicator A in a circle, showing Figure 4B yes Figure 4A The indicator B in the circle shows Figure 4C yes Figure 4B FIG4 illustrates an example of SLU channel access and resource selection. In some cases, the WTRU may perform SLU channel access and resource selection for COT initiation after COT sharing. The WTRU may perform N in the currently shared COT based on the SLU channel access and resource selection procedure for COT sharing. r_share When the number of transmissions performed in the shared current COT may be less than the number of transmissions determined for the TB (N r_share <N r_total), the WTRU may continue to perform SCI sensing for triggered SLU channel access and resource selection for COT sharing. When the WTRU does not detect a shareable COT, the WTRU may perform SLU channel access and selection for COT initiation simultaneously with SLU channel access and resource selection for COT sharing, as indicated in FIG4 .

[0272] like Figure 4A As shown, at 401, the WTRU may be triggered to perform SLU LBT channel access and resource selection for transmission of one or more TBs in time slot (n). At 402, the WTRU may determine the number of total transmissions based on the QoS of the TBs and / or the corresponding number of required resources (N). At 403, the WTRU may select the number of total transmissions in time slot (nT). 0_proc) and time slot (n-T0) receive and process information from SCI sensing and measured RSRP of the decoded SCI within the sensing window between time slot (n+T1) and time slot (n+T2) (e.g., processing historical transmissions in which SCI information / measurements were obtained to see if there are any COT reservations). As a result of one or more of the received and / or collected information, the WTRU may determine: a resource selection window between time slot (n+T1) and time slot (n+T2); the existence of an SL COT including time slot (n+T1+1); and / or a reserved COT within the resource selection window. At 404, the WTRU may determine the SL U LBT channel access for COT initiation configuration based on the CAPC parameters configured according to the QoS of the TB (e.g., configured by higher layers for each TB for transmission). At 405, the WTRU may perform per-slot processing starting at time slot (n+T1+1) (e.g., all processing that may occur in the time slot after point 405). At 406, the WTRU may perform per-slot SCI decoding (e.g., the initiating WTRU is performing SCI decoding, which in this instance may be receiving / monitoring to see if there is a COT to be shared; since there has been no transmission, the COT has not yet been acquired). At 407, the WTRU may determine if there is a SL COT in the current slot based on the SCI decoded in one or more previous slots (e.g., decoding an ongoing transmission in the current COT). If yes (based on the SCI decoded in the previous slot, there is a SLCOT in the current slot), then at 408, the WTRU may determine if the SL COT is shareable based on one or more parameters, such as information from the SCI (e.g., remaining duration, interleaving block assignment, priority, broadcast type, source and / or destination ID) and / or TB information (e.g., priority, broadcast type, source and / or destination ID, periodicity, etc.). At 409, the WTRU determines that the COT is shareable (as explained in 408). If no (the COT is not shareable), then at 410, the WTRU determines if the current timeslot overlaps with a SL COT reserved by another WTRU from a previously decoded SCI. If yes (the COT is shareable), then the WTRU proceeds to 418, where the WTRUs share the SL. At 418, the WTRUs share the CL COT and determine the resources (e.g., timeslots, mini-slots, interleaved blocks, etc.) in the SL COT for transmission of the determined TB based on one or more of: the remaining COT duration; the scheduled transmission; and / or the RB interleaving assignment indicated in the decoded SCI associated with the shared COT. At 419, the WTRU determines to perform SL U LBT channel access for COT sharing.

[0273] Returning to 407, if no (there is no SL COT in the current slot based on the SCI decoded in the previous slot), then at 410 the WTRU determines if the current slot overlaps with a SL COT reserved by another WTRU from a previously decoded SCI. If yes (the current slot does overlap with a SL COT reserved by another WTRU from a previously decoded DCI), then at 422 the WTRU continues processing, where the slot next =Time slot current +1, and the WTRU may then proceed to 425 where the WTRU determines whether the time slot is greater than n+T as described herein 2-(pre) The configured minimum channel access time (425 and the results of its determination will be further discussed herein). If no (the current timeslot does not overlap with the SL COT reserved by another WTRU from a previously decoded DCI), then at 411, the WTRU performs SL U LBT channel access for COT initiation according to the determined configuration. At 412, if the channel access is completed and unsuccessful, the WTRU may return to 411 and repeat the channel access again (for example, in some instances, this may be repeated until the channel is acquired, alternatively, this may be repeated until the delay of the TB is reached (when the TB expires)). At 412, if the channel access is completed and successful, then at 413, the WTRU may determine whether the initiating SL COT overlaps with the SL COT reserved by another WTRU from a previously decoded SCI. If yes (the initiating SL COT will overlap with the SL COT reserved by another WTRU from a previously decoded SCI), then at 420, the WTRU may evaluate whether to initiate the SL COT based on one or more of the following information (e.g., decoded from the SCI that reserves the overlapping SL COT): resources reserved within the reserved SL COT; priorities associated with the reserved SL COT; and / or other information or parameters (e.g., as described herein). If no (the initiating SL COT will not overlap with the SL COT reserved by another WTRU from a previously decoded SCI), then the WTRU may proceed with initiating the SL COT (e.g., at 414).

[0274] Based on the evaluation at 420, at 421, the WTRU may determine whether to initiate a SL COT. If yes, the WTRU may proceed to initiate a SL COT (e.g., at 414). If no, the WTRU may proceed to the next time slot, where the time slot next =Time slot current +1, and the WTRU may then proceed to 425 where the WTRU determines whether the time slot is greater than n+T as described herein 2-(pre) The configured minimum channel access time (425 and the results of its determination are discussed further herein).

[0275] At 414, the WTRU may initiate the SL COT and determine the resources (e.g., slots, mini-slots, interface blocks, etc.) in the SL COT for transmission of the determined TB based on one or more of: the WTRU source and / or destination ID of the TB to be transmitted; and / or the RB interlace assignment indicated in the decoded SCI associated with the overlapped reserved COT. At 415, the WTRU may transmit a channel reservation signal (e.g., a set of AGC symbols, SL CSI-RS, etc.) until the start of the first slot of the initiated COT. At 416, the WTRU may perform the transmission (as further described herein).

[0276] At 416, the WTRU may TX M transmissions are performed in the determined resources in the SLCOT within the duration of time slots. Therefore, as shown at 417, the next time slot for processing may be equal to the time slot plus T TX And N remaining =N minus M (e.g., since the WTRU needs to transmit in N resources to start, each time the WTRU starts transmitting M transmissions, the remaining resources will be NM). At 423, the WTRU determines whether more resources are needed for one or more transmissions of the TB (e.g., based on step 417, N remaining If no (more resources are not needed for transmission of the TB), then at 424, channel access and resource selection for the TB is completed and the TB is transmitted. If yes (the WTRU does need more resources for transmission of the TB), then at 425, the WTRU determines whether the timeslot is greater than n+T (e.g., configured as part of the channel access configuration). 2-(pre) Configured minimum channel access time. If no (time slot is not greater than n+T 2-(pre) If yes (time slot is greater than n+T) then the process may return to 406 (eg, process per time slot). 2-(pre) configured minimum channel access time), then at 426, channel access and resource selection for the TB may fail, and this may be reported to higher layers.

[0277] In some cases, there may be one or more procedures for SLU channel access and resource selection procedures for COT initiation. In some cases, the WTRU may determine COT initiation based on LBT sensing. In one case, when the number of transmissions performed within the shared or initiated COT may be less than the determined total number of transmissions (N r_share <N r_total) and / or the WTRU may not detect a current COT available for sharing based on SCI sensing, the WTRU may determine to perform SLU channel access and resource selection for COT initiation. In one case, when COT sharing is (pre)configured as disabled in the resource pool, the WTRU may be triggered by a higher layer to perform SLU channel access and resource selection for COT in time slot (n) for transmission of one or more TBs.

[0278] The WTRU may perform LBT sensing based SLU channel access for COT initiation (e.g., Type 1 LBT channel access as discussed herein). As described herein, the WTRU may simultaneously perform SCI sensing to detect the current COT for COT sharing. The WTRU may determine the configuration for LBT sensing based SLU channel access (as described herein) based on one or more of the following SCI information: resource pool and / or RB set; priority of TB (priority TX ); remaining packet delay budget (PDB); resource selection window (RSW); and / or the number of transmissions (N) including initial transmission and retransmission of TB TX ) and the corresponding total number of SL U resources in RSW (N r_total ).

[0279] The WTRU may determine to use the bandwidth of a resource pool and / or RB set as the bandwidth for LBT sensing. In another example, the WTRU may be (pre)configured with several RB sets for LBT sensing. The WTRU may perform LBT sensing on the bandwidth of each RB set used for channel access based on LBT sensing.

[0280] The WTRU may determine the duration of the COT and the size of the contention window for initiating based on the priority, PDB, and / or number of transmissions of the TB. In one example, the WTRU may select a short COT duration and a small contention window size for a TB with a high priority and a small PDB. With this LBT sensing configuration, the WTRU may spend less time accessing the channel. In another example, the WTRU may select a long COT duration and a large contention window size for a TB with a low priority, a large PDB, and / or a large number of transmissions.

[0281] In one method, the WTRU may determine a time to start LBT sensing for SLU channel access initiated for COT within a determined resource selection window (RSW). For example, when no current and shareable COT is detected, the WTRU may start LBT sensing at the beginning of the RSW. In another example, the WTRU may randomly select the LBT sensing start time within the RSW.

[0282] In another method, the WTRU may determine the time to start LBT sensing channel access (e.g., type 1 LBT channel access for initiating COT) based on the (pre-)configured LBT sensing start timing within the SL time slot, subframe and / or frame. For example, a set of LBT sensing channel access start timings may be (pre-)configured in the SL time slot, subframe and / or frame. Each (pre-)configured LBT sensing channel access start timing may be associated with an SL priority. When the WTRU is triggered to perform an LBT sensing channel access (e.g., type 1 LBT channel access) for the transmission of a TB, the WTRU may start the triggered LBT sensing channel access at the earliest LBT sensing channel access time point associated with the priority of the TB.

[0283] In another method, the WTRU may determine to exclude one or more reserved COTs and / or resources from the RSW determined based on LBT sensing. In one example, the WTRU may consider the LBT sensing slots included in the excluded period with RSW to be busy. In another example, the WTRU may suspend LBT sensing during the LBT sensing slots, such as ignoring LBT sensing results from the sensing slots. The WTRU may select the reserved COTs and / or resources based on the priority (priority) associated with the reserved COTs and / or resources. resv ) (such as the priority indicated in the SCI that reserves the COT and / or resources and / or the priority of the TB to be transmitted (priority TX )) to determine whether to perform such exclusion. In one example, when the priority (Prio) associated with the reserved COT and / or resource resv ) is higher than the priority of the TB to be transferred (priority TX ), the WTRU may determine to perform the exclusion. In another example, the WTRU may determine to perform the exclusion when the RSRP measured on the PSSCH / PSCCH transmission of the reserved COT and / or resources exceeds a (pre)configured threshold. The WTRU may select a priority (priority) associated with the reserved COT and / or resources. resv ) and / or the priority of the TB to be transferred (priority TX ) to select this threshold.

[0284] In one case, during LBT sensing for SLU channel access for COT initiation, when the WTRU detects a current COT that can be shared, the WTRU may switch from the ongoing SLU channel access and resource selection for COT initiation to performing SLU channel access and resource selection for COT sharing. In another case, the WTRU may adjust the LBT sensing based channel access procedure based on SCI sensing and / or COT sharing. The WTRU may suspend and resume the LBT sensing based SLU channel access by excluding one or more of the following time slots from LBT sensing: the time slot in which the current COT is detected based on SCI sensing; and / or the time slot in which the WTRU performs transmission in the shared current COT.

[0285] In some instances, during SLU channel access based on LBT sensing, the WTRU may not perform LBT sensing within the time slot.

[0286] The WTRU may perform LBT sensing for COT initiated SL U channel access (such as type 1 channel access) in a set of consecutive logical time slots in the time domain of the determined SL resource pool. This LBT sensing may be performed continuously over time to ensure fair access to the spectrum.

[0287] In one example, the WTRU may perform LBT sensing in physical time slots to ensure temporal continuity of all sensing time slots. When LBT channel access is successful, the WTRU may determine to initiate a channel including a time slot with consecutive physical time slot indices (t i The WTRU may determine a logical time slot index (T ) for each of the included physical time slots based on a mapping between the physical time slots and the logical time slots belonging to the resource pool for PSSCH / PSCCH transmissions to be sent within the initiated COT. i ). WTRU determination of such mapping (e.g., WTRU procedures for determining temporal continuity of logical time slots in a resource pool) is further discussed herein. The WTRU may thus initiate a request including a request with a logical time slot index (T i ), which may or may not be consecutive. Thus, the WTRU may calculate and include in the SCI transmission indications based on the logical slots, such as the remaining COT duration, the remaining transmission duration, the COT and / or resource reservation interval, the COT and / or resource reservation window, etc.

[0288] In another example, the WTRU may perform LBT sensing in a logical time slot of a resource pool used for PSSCH / PSCCH transmission. When LBT sensing is performed on logical time slots (e.g., with consecutive logical time slot indices) that may not be consecutive (e.g., have gaps in the time domain), the WTRU may determine to stop the ongoing LBT sensing. The WTRU may restart LBT sensing for channel access after the gap in the time domain. Alternatively, the WTRU may continue the ongoing LBT sensing and add a number of deferral periods corresponding to the length of the gap in the time domain in the LBT sensing. Therefore, the WTRU may initiate a LBT sensing including a logical time slot with consecutive logical time slot indices (T i )’s set of logical time slots.

[0289] When the channel access based on LBT sensing is successful, for example, when the SLU channel is available, the WTRU may determine to initiate a COT and perform resource selection within the initiated COT. In another example, the WTRU may determine whether to initiate a COT based on the COT and the resource reservation information based on SCI sensing and perform resource selection within the initiated COT.

[0290] In one example, when the duration of the COT for initiation overlaps with the reserved COT and / or resources, the WTRU may determine not to initiate a COT. The WTRU may perform another LBT sensing-based channel access after the reserved time slot and / or resource reservation in the COT.

[0291] In another example, when the duration of the COT to be initiated overlaps with the reserved COT and / or resources, when the priority (priority resv ) and / or resources (eg, a priority indicated in the SCI that reserves the COT and / or resources) is higher than the priority (priority) of the TB to be transmitted in the COT to initiate the transmission. TX ), the WTRU may determine not to initiate COT. The WTRU may determine to perform LBT sensing-based SLU channel access for COT initiation after the overlapping reserved COT ends.

[0292] In another example, the WTRU may determine to initiate a COT that overlaps with a reserved COT and / or resources when the RSRP associated with the overlap (determined in SCI sensing) is below a (pre)configured threshold. For example, the L1 priority (priority) associated with the overlapping reserved COT may be used. resv ) and the L1 priority of the TB to be transmitted (priority TX ) to determine the value of such a threshold. The value of such a threshold may also be associated with channel congestion. The WTRU may determine the value of such a threshold with a priority resv , Priority TXand an RSRP threshold corresponding to channel congestion measured in LBT sensing and / or SCI sensing.

[0293] In another example, the WTRU may determine to initiate a COT that overlaps with a reserved COT and / or resources, while excluding frequency resources assigned for the reserved COT and / or resources from resource selection within the initiated COT. In this case, the WTRU may initiate a COT using resources multiplexed with frequency resources assigned in the COT and / or resource reservation in the frequency domain.

[0294] Upon successful LBT sensing channel access, the WTRU may determine to initiate a COT immediately after the end of LBT sensing. The WTRU may determine whether to initiate a COT based on the temporal continuity of the logical time slots to be included in the COT for initiation. In one example, the WTRU may determine that the logical time slots to be included in the COT may not be continuous in the time domain based on the mapping between the physical time slots and logical time slots belonging to the resource pool for the PSSCH / PSCCH transmission to be performed within the initiated COT. The WTRU may then determine not to initiate a COT after the performed LBT sensing channel access and start another LBT sensing channel access for COT initiation.

[0295] Upon successful LBT sensing channel access, the WTRU may determine to initiate a COT immediately after the end of LBT sensing based on the measured congestion level. In one example, the WTRU may determine to initiate a COT when the measured congestion level is below a (pre)configured threshold. The WTRU may determine such congestion level based on one or more (pre)configured measurements performed in LBT sensing and / or SCI sensing. These measurements may include, for example, RSSI measured in the sensing timeslot, RSSI measured in the SL timeslot, RSRP measured on the PSCCH DMRS and / or PSSCH DMRS associated with the decoded SCI, the number of timeslots where the LBT sensing results of the channel may be busy, etc. The WTRU may perform such congestion level measurements within a (pre)configured SL U channel congestion measurement window.

[0296] The measured channel congestion level may be expressed as the ratio of the number of slots for which the measured value (e.g., RSSI or number of busy sensing slots) exceeds a (pre-)configured level to the total number of measured sensing and / or SL slots in the resource pool. In one example, the (pre-)configured threshold may be related to the L1 priority (priority TX ). A higher threshold may be associated with a higher priority (priority) of the TB to be transferred. TX ) is associated, so at a given congestion level, a WTRU with a higher priority TB may be allowed to initiate COT upon successful LBT sensing channel access.

[0297] In some cases, there may be a WTRU transmission after a successful Type 1 LBT channel access without a channel reservation signal and / or CPE transmission. LBT-success Upon successful LBT sensing channel access at , the WTRU may not immediately perform the transmission of a channel reservation signal and / or CPE to hold the channel until the start time (t ) of the PSSCH / PSCCH transmission initiated by the COT. PSSCH-COT-start When one or more conditions are met, the WTRU may perform a COT initiated PSSCH / PSCCH transmission without the transmission of a channel reservation signal and / or CPE.

[0298] For example, one condition may be the time offset (ie, t PSSCH-COT-start -t LBT-success ) can be less than a (pre)configured threshold and greater than the symbol.

[0299] For example, one condition may be that the WTRU may determine that the channel is available in all N sensing slots before the PSSCH / PSCCH transmission of the COT begins. A minimum N value may be (pre)configured, such as one sensing slot. In one example, the WTRU may select N based on the measured SL U CBR. A larger value may be selected when the SL U CBR is high, such as when the channel is busy.

[0300] For example, one condition may be that the WTRU may determine that the channel is available in all sensing slots included in the LBT contention period after the N sensing slots. The LBT contention period may include a duration (T f =16us), followed by m p The duration of a continuous sensing time slot (T sl =9us), where m p A CAPC configuration may be selected based on the priority of the TBs to be transmitted in the initiated COT.

[0301] If one of the conditions is not met, the WTRU may not perform PSSCH / PSCCH transmission and may not initiate COT. The WTRU may perform another Type 1 LBT channel access to initiate another COT.

[0302] When the time offset between the completion of Type 1 LBT channel access and the start of PSSCH / PSCCH transmission (e.g., t PSSCH-COT-start -t LBT-success ) is less than the symbol, the WTRU may perform transmission of a channel reservation signal and / or CPE immediately after a successful Type 1 LBT sensing channel access.

[0303] In some cases, in an initiated COT, there may be one or more procedures for resource selection. When the WTRU initiates a COT, the WTRU may perform resource selection within the initiated COT. The WTRU may determine the number of available candidate resources (N) within the initiated COT based on one or more of the following information: r_COT ): initiated COT duration in time slots (T initiated_COT ); candidate resources for TB to be transmitted, such as L in a time slot RB_interlace RB interlaces; and / or overlapping frequency resource assignments of reserved COTs and / or resources.

[0304] The WTRU may determine the number of available candidate resources (N) within the initiated COT. r_COT ) is T initiated_COT ×floor(M / L RB_interlace ), where N slot is the number of time slots within the initiated COT, M is the (pre-)configured number of RB interlaces of the indicated resource pool, and / or the RB set and floor (M / L RB_interlace ) is the number of available candidate resources in each such time slot. When the WTRU initiates a COT that overlaps with the reserved COT and / or resources, the WTRU may specify the number of available candidate resources (N) within the initiated COT. r_COT ) is determined as T initiated_COT ×floor(M / L RB_interlace )–N r_reserve , where N r_reserve It can be the number of reserved resources.

[0305] The WTRU may be (pre-)configured with a maximum number of available candidate resources (N) for COT initiation in the resource pool. r_max ), and the WTRU may determine the number of resources to be used (N r_init ) is determined as N r_init =Nr _max In another example, this value can be combined with the L1 priority (priority TX ) association. The WTRU may associate the TB to be transmitted based on the (pre)configured association and the L1 priority (priority TX ) to determine N r_max .

[0306] In another example, the WTRU may be (pre)configured with respect to the determined available candidate resources (N r_COT ) ratio (P%). The WTRU may r_init ) is determined as N r_init =Nr_COT × P%. The value of P may be associated with the L1 priority, and the WTRU may select a TB to be transmitted based on the L1 priority (Prio TX ) to determine the value of P. In another example, the value of P may be associated with the channel congestion status. The WTRU may determine the value of P based on the L1 priority (priority) of the TB to be transmitted. TX ) and / or channel congestion measured in LBT sensing and / or SCI sensing (such as RSSI, resource pool and / or RB set over the bandwidth of LBT sensing).

[0307] When the WTRU is not (pre-)configured with such N r_max and / or P ratio, the WTRU may determine to use all determined available candidate resources in the initiated COT, N r_init =Nr _COT When the determined N r_init When it is greater than or equal to the total number of resources determined for transmission of TB (N r_init >=N r_total ), the WTRU may determine Nr _init The number of = N r_total In this case, the WTRU may complete the transmission of the determined TB in the initiated COT.

[0308] The WTRU may sort N in ascending order according to the RB interlace index and the time slot index. r_COT For example, the WTRU may first index the available candidate resources in a time slot in ascending order of the RB interlace index and then continue to index the candidate resources in the next time slot until the last time slot for sharing in the current COT. The WTRU may use an index such as r j The index of each available candidate resource is represented by the index j, where the index j can be (0, 1...N r_COT -1).

[0309] The WTRU may obtain r_COT N of these resources are selected for the transmission of TB r_init Available candidate resources, as discussed herein. The WTRU may determine that there are one or more available candidate resources in each time slot of the initiated COT.

[0310] The WTRU may determine which N to use based on one or more of the following: r_init available candidate resources for transmission of a TB: random selection; WTRU source and / or destination ID timeslot index; broadcast type; and / or (pre-)configured resource pattern.

[0311] The WTRU can select from (0, 1...Nr_COT -1) randomly select N r_init The WTRU may determine N based on the broadcast type and value of the associated WTRU source and / or destination IDs. r_init In one example, for unicast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU source ID and / or the WTRU destination ID. In addition, the WTRU may also include the time slot index in the initialization of the seed. In another example, for multicast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU destination ID and / or the (pre-)configured group member IDs. For broadcast transmissions, the WTRU may determine the random selection initialization seed based on the WTRU destination ID.

[0312] The WTRU may be (pre)configured with a set of available candidate resource patterns. For example, the WTRU may select a first set of consecutive N r_init Available candidate resources, the indexes of these available candidate resources can be represented by (r0, r1...r Nr_init ) indicates. When N r_init =N r_total When N r_init <N r_total When the WTRU may perform N r_init TB transmissions are performed, and a new SLU channel access procedure is performed to perform the remaining TB transmissions in the newly initiated COT or another shared COT.

[0313] In another example, the WTRU may select a set of consecutive N r_tx_init Available candidate resources, the indexes of these available candidate resources are represented by (r offset 、r offset+1 ...r offset+Nr_init ). The WTRU may determine the available candidate resource group offset value based on the WTRU source and / or destination ID and the WTRU destination ID for unicast transmissions. The WTRU may determine the available candidate resource group offset value based on the WTRU destination ID and / or the (pre-)configured multicast member IDs for multicast transmissions. The WTRU may determine the available candidate resource group offset value based on the WTRU destination ID for broadcast transmissions. For example, the WTRU may determine such an offset by performing a modulo function using the values ​​of the WTRU ID and / or the multicast member ID and the number of available candidate resource groups, which may be equal to floor(N r_COT / N r_init ).

[0314] In some cases, there may be PSSCH / PSCCH transmissions in the initiated COT. The WTRU may determine N r_init The WTRU may perform PSSCH / PSCCH transmission of one or more TBs in the available candidate resources. For each PSSCH / PSCCH transmission performed in the initiated COT, the WTRU may indicate one or more SCI information in the PSCCH on the initiated COT, the transmitted TB, the transmission configuration, etc.

[0315] An example of SCI information may be the L1 priority, broadcast type and / or WTRU source ID and / or destination ID of the TB transmitted in the PSSCH.

[0316] An example of SCI information may be a remaining COT duration, which may be the remaining time of the COT between the timeslot in which the SCI is transmitted and the end of the initiated COT. In one example, the unit of the remaining COT duration may be a logical timeslot of a resource pool used for PSCCH / PSCCH transmission within the initiated COT. In another example, a physical timeslot may be applied to indicate the duration. The WTRU may determine the remaining COT duration in each SCI transmitted in the COT based on the maximum COT and the index of the timeslot including the SCI transmission. The WTRU may not use all of the remaining COT duration for SL transmission. The actual transmission scheduled within the COT may be indicated in another SCI indication of the remaining transmission duration.

[0317] An example of SCI information may be the MCOT duration. The maximum COT corresponding to the configuration of Type 1 LBT that the WTRU may perform to initiate a COT may be indicated. The maximum COT may be in ms or logical SL slots.

[0318] An example of SCI information may be the COT starting slot index. The WTRU may indicate the logical slot index of the first slot of the COT. When the WTRU decodes the SCI within the COT, the WTRU may determine the number of remaining slots within the COT that may be used for SL transmission based on the indicated starting slot index and the MCOT duration.

[0319] One example of SCI information may be a COT initiation / sharing indication.A WTRU initiating a COT may indicate a value corresponding to COT initiation (eg, a value of one) in this SCI field for all SL transmissions performed by the WTRU in the initiated COT.

[0320] An example of SCI information may be COT sharing for PSSCH / PSCCH indication, where the WTRU may set the value of this indication based on the (pre)configuration (enable / disable) of the resource pool. The WTRU may set the value to "enable" when the COT transmitted by the WTRU may be shared by another WTRU. When the value is set to "disable", the COT may not be shared.

[0321] An example of SCI information may be COT sharing for PSFCH indication, where the WTRU may set the value of this indication based on the (pre)configuration (enabled / disabled) of the resource pool when HARQ feedback is enabled for TBs transmitted in PSSCH. The WTRU may set this indication to disabled when HARQ feedback is disabled for TBs transmitted in PSSCH. When this SCI indication is set to "enabled" and HARQ is enabled, PSFCH may be transmitted in the same COT in which the associated PSSCH / PSCCH transmission is received (e.g., the COT is shared). When this SCI indication is set to "disabled" and HARQ is enabled, PSFCH may not be transmitted in the same COT in which the associated PSSCH / PSCCH transmission is received (e.g., the COT may not be shared). In one example, the WTRU may disable PSFCH sharing when there is no (pre)configured PSFCH opportunity in the COT.

[0322] An example of SCI information may be a channel congestion indication, where the WTRU may determine such a value based on one or more (pre) configured attributes of the LBT sensing and / or SCI sensing performed to initiate the COT. The attributes may include, for example, the length of time to complete the procedure, the number of time slots in which the LBT sensing results of the channel may be busy, the number of deferral durations performed, etc. When one or more of the said numbers exceed a (pre) configured threshold, the WTRU may set the value to one. In another example, the WTRU may determine the channel congestion indication value based on the RSSI measured in the resource pool and / or RB set. When the measured RSSI may exceed a (pre) configured threshold, the WTRU may set the indication to one. In addition, the WTRU may use the ratio of the number of time slots in which the measured RSSI for the resource pool and / or RB set may exceed the (pre) configured level to the measured SL time slot number in the resource pool to determine the channel congestion level, such as the SL U channel busy ratio (CBR). When this channel congestion level may exceed a (pre) configured threshold, the WTRU may set the indication. The RSSI measurement may be based on LBT sensing and / or measurement of the PSCCH DMRS associated with the decoded SCI. The WTRU may perform such RSSI measurement within a (pre-)configured SL U CBR measurement window.

[0323] One example of SCI information may be a remaining transmission duration, which may be the number of consecutive time slots scheduled for PSCCH / PSSCH transmission between the time slot in which the SCI is transmitted and the end of the initiated COT, such as indicated by TRIV. In one example, the unit of the remaining transmission duration may be a logical time slot of a resource pool for PSCCH / PSCCH transmission within the initiated COT. In another example, a physical time slot may be applied.

[0324] One example of SCI information may be a frequency resource assignment for the PSSCH, which may be an RB interlace index and / or RB set index, such as indicated in FRIV, for PSSCH transmissions between the timeslot in which the SCI is transmitted and the end of the initiated COT.

[0325] An example of SCI information may be COT and / or resource reservation interval, where the WTRU may indicate a value of zero when COT and / or resource reservation for another TB may be disabled in the resource pool. The WTRU may indicate a value of zero when a TB transmitted in the PSSCH may be aperiodic.

[0326] When COT and / or resource reservation for another TB may be enabled in the resource pool and the TB transmitted in the PSSCH may be periodic, the WTRU may indicate the time period in ms or number of slots between the initiated COT and / or resource and the reserved COT and / or resource for transmission of another TB. This time period may be set to the COT and / or resource reservation interval (P rsvp_TX In one example, the unit of the COT and / or the resource reservation interval may be a logical time slot of a resource pool for initiating PSCCH / PSCCH transmission within the COT. In another example, a physical time slot may be applied to indicate this interval time.

[0327] By reserving such COT and / or resources, the WTRU may perform SL channel access to initiate a reserved COT of the same length as the initiated COT. Additionally, a reservation window may be (pre)configured in association with the COT length. The WTRU may initiate a reserved COT within the reservation window. In another example, a reservation window associated with an indicated COT and / or resource reservation interval may be indicated in the same SCI.

[0328] In another example, the COT and / or resource reservation for transmissions performed in the initiated COT may be enabled / disabled in the (pre-)configuration of the resource pool. When this (pre-)configuration is disabled in the resource pool, the WTRU may set the indication to zero regardless of the traffic type of the TB transmitted in the shared current COT and / or the (pre-)configuration for the COT and the resource reservation for another TB.

[0329] An example of SCI information may be the COT and / or resource reservation window, where the WTRU may indicate a value of zero when the COT and / or resource reservation for COT initiated retransmissions may be disabled in the resource pool. r_total ) may be performed in an initiated COT, the WTRU may indicate a value of zero. The WTRU may indicate a value of a time period in ms or number of time slots after the end of the current COT. The WTRU may determine the length of the window based on the remaining packet delay budget (PDB) of the TBs transmitted in the shared current COT. In addition, the WTRU may determine the length of the window based on the remaining packet delay budget (PDB) of the TBs transmitted in the initiated COT. In one example, the unit of the COT and / or the resource reservation window may be a logical time slot of a resource pool for PSCCH / PSCCH transmission within the initiated COT. In another example, a physical time slot may be applied to indicate this window length.

[0330] An example of SCI information may be a HARQ process number, a new data indicator, and / or a redundancy version.

[0331] An example of SCI information may be a HARQ feedback enable / disable indication, which may be an indication of whether HARQ feedback is enabled and whether PSFCH carrying HARQ ACK / NACK is expected for PSSCH / PSCCH transmission. The WTRU may determine this indication based on the QoS requirements of the TBs transmitted in the shared current COT.

[0332] An example of SCI information may be a transmission configuration including the number of DMRS ports, DMRS mode, MCS value, and MCS table indication.

[0333] An example of SCI information may be an indication of the SCI-2 format and a beta offset value.

[0334] One example of SCI information may be the region ID of the WTRU determined based on geographical coordinates (eg, from GNSS).

[0335] An example of SCI information may be an indication of a (pre-)configured minimum communication range (MCR) requirement (eg, in meters) for a TB transmitted in a PSSCH / PSCCH transmission, such as an index corresponding to the (pre-)configured MCR requirement.

[0336] An example of SCI information may be an indication of the synchronization source of the WTRU. The WTRU may set a set of values ​​corresponding to the source to which the WTRU is synchronized in this SCI indicator. These values ​​may be (pre)configured to correspond to GNSS, gNB, SyncRef WTRU and / or internal WTRU clock. In another case, an additional SCI indication may be applied to indicate the SL synchronization signal ID received from the SL synchronization signal (SLSS).

[0337] An example of SCI information may be an indication of SL slots for sharing within the COT. The WTRU may explicitly indicate which SL slots in the COT may be shared. In one example, a TRIV may be used to indicate a logical slot offset, such as including the number of logical slots between the SL slot indicated by the SCI and the SL slot indicated for sharing. In another example, a logical slot index of the SL slot for sharing may be indicated.

[0338] In some cases, the WTRU may determine a COT starting position for COT initiation and COT sharing. In one case, the WTRU may be (pre)configured with a set of starting positions of the COT (e.g., the moment to start SL transmission in the COT) within a (pre)configured time period. The (pre)configured time period may be a SL time slot, a SL subframe, a radio frame (represented by an SFN), and / or a (pre)configured time period in a SL resource pool. The (pre)configured set may include N COT starting positions in each consecutive (pre)configured time period in the resource pool. Each starting position may be represented by a COT starting position index specific to the (pre)configured time period. When the (pre)configured time period is a SL time slot, the COT starting position may also be represented by a symbol index. For example, when there are two COT starting positions (N=2) (pre)configured in the SL time slot, the first COT starting position may be located at symbol 0 of the SL time slot and the second COT starting position may be located at symbol 7 of the SL time slot. In one example, the COT starting position may be the start of a (pre-)configured SL slot and / or mini-slot.

[0339] In one method, the COT starting position can be one or more of the following transmission instances: the start of a PSSCH / PSCCH transmission included in an initiated and / or shared COT, wherein such a COT starting position can be (pre) configured as the start of a time slot, a mini-time slot and / or a symbol in the SL resource pool; and / or the start of a transmission of a reserved signal and / or CPE prior to a PSSCH / PSCCH transmission included in an initiated and / or shared COT, wherein the duration of the reserved signal and / or CPE may not be included in the length of the initiated and / or shared COT.

[0340] This COT start position can be (pre)configured as the start of a time unit. This time unit can be (pre)configured as one of the following: SL slot, mini slot, symbol, LBT sensing slot (e.g., 9us T sl ) and / or LBT contention period (e.g., T d =T f +m p ×T sl , where T f It can be 16us, T sl It can be 9us, and m p It may be a value of 1, 3 or 7 selected from the CAPC configuration based on the priority of the TBs to be transmitted in the simulated and / or shared COT.

[0341] The reservation signal and / or CPE may have a duration exceeding an integer number of the aforementioned (pre)configured time units. In one example, the SL timeslot may be (pre)configured with a set of LBT sensing timeslots and / or LBT contention periods, and the start of each LBT sensing timeslot and / or LBE contention period may be a COT start position. The WTRU may start transmission for the initiated and / or shared COT by performing transmission of the channel reservation signal and / or CPE at the earliest COT start position associated with the priority of the TB to be transmitted in the initiated and / or shared COT.

[0342] In another example, the WTRU may determine the transmission start position based on the channel reservation signal and / or the duration of the CPE associated with the priority of the TB to be transmitted in the COT. The duration may include a number of time units, and such a time unit may be the LBT sensing time slot (T SL )、LBT competition period (T contention ), a duration of 16us, a duration of 25us, a symbol, a SL mini-slot and / or a SL slot. Each such channel reservation and / or CPE duration may be (pre)configured with an association with a SL priority. The WTRU may select a channel reservation signal and / or CPE associated with the priority of the TB to be transmitted in the COT, and determine the corresponding transmission start position, such as the start position of the channel reservation signal and / or CPE (start of PSSCH / PSCCH transmission - duration of the channel reservation signal and / or CPE) based on the duration of the first PSSCH / PSCCH transmission of the COT and the starting symbol / mini-slot / slot.

[0343] In one case, the WTRU may be (pre)configured with an association between a COT start position and a SL TB priority threshold. When the WTRU completes a Type 1 LBT and finds an available channel, the WTRU may determine whether to initiate a COT and perform a SL transmission at the earliest upcoming COT start position after the Type 1 LBT is completed based on the priority of the TB to be transmitted in the COT and the priority threshold associated with the earliest upcoming COT start position.

[0344] Eight priority values ​​from 1 to 8 for the SL TB may be defined and indicated in the 3-bit SCI field. In one case, the higher the priority value indicated for a TB, the lower the priority of the TB, or vice versa may be another case.

[0345] When the priority of the TB is higher than or equal to the priority threshold associated with the earliest COT starting position (for example, the priority value of the TB is less than or equal to the priority threshold), the WTRU may determine to initiate a COT at the earliest upcoming COT starting position and perform SL transmission.

[0346] When the priority of the TB is lower than the priority threshold associated with the earliest COT starting position (e.g., the priority value of the TB is greater than the priority threshold), the WTRU may determine not to initiate a COT (e.g., abandon the available channel) and perform a SL transmission at the earliest upcoming COT starting position (e.g., abandon the available channel).

[0347] In one example, there are two COT starting positions (pre-)configured in a SL slot (N=2), and COT starting position 1 may be (pre-)configured to be associated with a priority threshold of 4 and COT position 2 may be (pre-)configured to be associated with a priority threshold of 8. In this example, both COT starting positions 1 and 2 may be used by the COT for SL transmissions of TBs with priority values ​​of 1, 2, 3, and 4. However, for TBs with priority values ​​of 5, 6, 7, and 8, the WTRU may not use COT starting position 1 and may have one starting position (e.g., COT starting position 2) in each SL slot.

[0348] In another approach, the set of (pre)configured COT starting positions may be divided into multiple subsets, and each subset of COT starting positions may be associated with a range of SL TB priorities. When the priority of a TB is associated with the earliest upcoming COT starting position after the Type 1 LBT is completed, the WTRU may determine to initiate a COT and perform a SL transmission of the TB at the earliest upcoming COT starting position. When the priority of a TB is not associated with the earliest upcoming COT starting position after the Type 1 LBT is completed, the WTRU may determine not to initiate a COT and not to perform a SL transmission of the TB at the earliest upcoming COT starting position.

[0349] In the above example with two (pre)configured COT starting positions in a set, the first subset may include two COT starting positions and be associated with priority values ​​ranging from 1 to 4. The second subset may include a second COT starting position in each SL slot and associated with priority values ​​ranging from 1 to 8.

[0350] When the WTRU determines to initiate a COT at the earliest upcoming COT start position, the WTRU may perform transmission of a CPE (cyclic prefix extension) and / or a channel reservation signal in the time gap between the completion of the Type 1 LBT and the earliest upcoming COT start position. When the WTRU determines not to initiate a COT at the earliest upcoming COT start position, the WTRU may start another Type 1 LBT and continue to acquire a channel for SL transmission of the TB.

[0351] Figure 5 An example of a WTRU determining a COT start position within a SL timeslot is illustrated. As shown, there are two WTRUs 501 and 502 attempting to transmit a message (e.g., a transmission block), with time being shown in the horizontal axis 510. The vertical axis is used to illustrate only two WTRUs, however, each WTRU may be transmitting on the same channel / spectrum (e.g., thus requiring the system to avoid competing transmissions). When multiple SL WTRUs are competing for a channel, this priority-based determination of the COT start position may enable WTRUs with high priority TBs to access the channel more frequently. As shown in FIG. Figure 5 As shown in the example of , two WTRUs (e.g., 501 and 502) compete for a channel for SL transmission of TBs with different priorities (e.g., priority 1 and priority 2, where priority 1 is lower). The result of this method is that WTRU 501 may complete the Type 1 LBT first, but determine to abandon the available channel, and WTRU 502 with the highest priority TB may acquire the channel and initiate COT for SL transmission. The WTRU may utilize CPE transmissions and / or channel reservation signaling transmissions (512) to accomplish this method.

[0352] As shown in this example, a first set of starting positions 513 (pre-)configured in the SL time slot may be associated with priority 2 and / or with a priority threshold value that is higher than or equal to the value of priority 2. A second set of starting positions 514 (pre-)configured in the SL time slot may be associated with both priority 1 and priority 2 and / or with a priority threshold value that is higher than or equal to the value of priority 1.

[0353] At 521, the WTRU 501 may detect available channels and determine that the earliest upcoming COT starting position is not associated with the second starting position set 514 for priority 1 and / or the priority 1 value is greater than the associated priority threshold. Therefore, the WTRU 501 may determine not to initiate a COT and perform another Type 1 LBT (e.g., at 522) to continue acquiring the channel.

[0354] At 531, the WTRU 502 may complete a Type 1 LBT and determine that the earliest upcoming COT start position is associated with priority 2 and / or the priority 2 value is less than the associated priority threshold. The WTRU 502 may therefore determine to initiate a COT at the earliest upcoming COT start position of the first set 513. The WTRU 502 may perform CPE transmissions and / or channel reservation signal transmissions (e.g., 516) until the earliest upcoming COT start position of the first set 513, at which point, at 532, the WTRU 502 may continue transmission of the TB.

[0355] The WTRU 501 may acquire an available channel within the resource selection window and determine that the earliest upcoming COT starting position is associated with priority 1 and / or the priority 1 value is less than the associated priority threshold. At 522, the WTRU 501 may perform another LBT Type 1 for priority 1, where there may actually be two starting positions from the second set of starting positions 514 applicable to the TB of priority 1 (e.g., one TB in each time slot), but the WTRU 501 will detect the reservation signal 516 from the WTRU 502 before the first starting position 514, and therefore, the WTRU 501 may determine to initiate the COT at the second appropriate starting position 514. The WTRU 502 may perform CPE transmissions and / or channel reservation signal transmissions 515 until the earliest upcoming COT starting position of the first set 514. At 523, the WTRU may continue with the transmission of the TB.

[0356] Assume that if the WTRU 501 fails to obtain an available channel within the resource selection window 511, the WTRU 501 may report LBT and / or channel access failure to higher layers.

[0357] In one method, the WTRU may apply a slot structure for a COT start position for PSSCH / PSCCH transmissions. For example, when the COT start position is symbol-based and (pre)configured with slots, each COT start position and subsequent symbols until the next COT start position may be a PSSCH / PSCCH mini-slot. When the WTRU initiates a COT, the WTRU may determine to apply such a mini-slot structure to perform PSSCH / PSCCH transmissions within the COT.

[0358] In another method, the WTRU may switch from a slot structure for the COT starting position to another slot structure that is (pre)configured for PSSCH / PSCCH transmissions in the initiated COT. In one example, the WTRU may apply slot-based PSSCH / PSCCH transmissions in the COT starting from the first SL slot boundary after one or more mini-slot-based transmissions in the COT. The WTRU may indicate the duration of the PSSCH / PSCCH transmissions in the COT (e.g., the number of symbols, mini-slots, and / or slots in the SCI).

[0359] Similarly, WTRU determination of the COT starting position based on the priority of the TB may be applied to COT sharing so that WTRUs with high priority TBs can more easily share the COT. In one case, the WTRU may determine whether to share the COT based on the priority of the TB and the priority range and / or priority threshold associated with the (pre-)configured COT starting position and start performing SL transmission at the earliest upcoming COT starting position within the ongoing shareable COT.

[0360] After a successful Type 2 LBT, the WTRU may determine that the COT is not shared when the earliest upcoming COT start position within the COT is not associated with the priority of the TB and / or is not associated with a priority threshold that is higher than the priority of the TB. The WTRU may determine that an ongoing and sharable COT is shared when the earliest upcoming COT start position within the COT is associated with the priority of the TB and / or is associated with a priority threshold that is lower than the priority of the TB.

[0361] In another case, when the CBR and / or RSSI measured in Type 1 and / or Type 2 LBT exceeds a (pre)configured threshold, the WTRU may apply COT start position determination (e.g., as discussed herein). When the CBR and / or RSSI measurements are below a (pre)configured threshold, the WTRU may initiate and / or share a COT at the earliest upcoming COT start position without considering the priority of the TBs to be transmitted in the COT.

[0362] In some cases, the WTRU may perform SLU channel access for SL synchronization signal block (S-SSB) transmission based on the synchronization reference (SyncRef) WTRU priority level. The WTRU may become a SyncRef WTRU and perform a SL synchronization signal block (S-SSB) transmission. The WTRU may be (pre)configured for the periodicity of SL synchronization signal block (S-SSB) transmission (e.g., X frames). In each time period, the number of S-SSB transmissions may be (pre)configured. The S-SSB candidate timing (such as the time domain position of the S-SSB transmission within the time period) may be (pre)configured with a starting slot offset and an S-SSB interval (e.g., in units of time slots). The WTRU may determine the first S-SSB candidate timing in a time slot, which may be N slots after the start of the time period, where N is the (pre)configured starting slot offset. The WTRU may determine subsequent S-SSB candidate timings based on the determined first S-SSB candidate timing and the S-SSB interval.

[0363] The priority level of a SyncRef WTRU may be based on one or more of: the GNSS coverage of the SyncRef WTRU; the network coverage of the SyncRef WTRU; and / or the synchronization reference of the SyncRef WTRU.

[0364] A SyncRef WTRU may be synchronized with a GNSS (eg, when in coverage), with a base station (eg, when in coverage), with another SyncRef WTRU, or with the SyncRef WTRU's own internal clock.

[0365] In one example, the priority levels of the SyncRef WTRU may be (pre)configured in descending order as follows: a first priority level, where the SyncRef WTRU may be within coverage and synchronized directly with the GNSS; a second priority level, where the SyncRef WTRU may be out of coverage and synchronized with another SyncRef WTRU that may synchronize directly with the GNSS (e.g., one hop away from the GNSS); a third priority level, where the SyncRef WTRU may synchronize directly with the base station; a fourth priority level, where the SyncRef WTRU synchronizes with another SyncRef WTRU that synchronizes directly with the base station (e.g., one hop away from the base station); a fifth priority level, where the SyncRef WTRU may synchronize with another SyncRef WTRU whose synchronization source may be two or more hops away from the base station or GNSS; and / or a sixth priority level, where the SyncRef WTRU may synchronize with its own internal clock.

[0366] A SyncRef WTRU may perform a Type 2 (e.g., Type 2A) channel access before an S-SSB candidate opportunity. If one S-SSB transmission (pre)configuration is applied, SyncRef WTRUs of different priority levels may contend for channel access before the same S-SSB candidate opportunity. Depending on the proximity and timing reference of the SyncRef WTRUs, a SyncRef WTRU of a lower priority level may access the channel first and block another SyncRef WTRU of a higher priority level. Avoiding such blocking may be beneficial.

[0367] In one method, a WTRU may be (pre)configured with an association between each S-SSB candidate opportunity and a SyncRef WTRU priority level. In one example, one or more S-SSB candidate opportunities may be associated with a priority level that is higher than or equal to a (pre)configured threshold. At these opportunities, SyncRef WTRUs with a priority level higher than or equal to the (pre)configured threshold may avoid channel contention with SyncRef WTRUs with a priority level lower than the threshold. The remaining S-SSB candidate opportunities may be associated with all priority levels. Thus, SyncRef WTRUs with higher priority levels may contend for channels at more S-SSB candidate opportunities.

[0368] In another method, the WTRU may be (pre)configured with a set of S-SSB transmission (pre)configurations. Each S-SSB transmission (pre)configuration may include a different starting slot offset and / or S-SSB interval and / or may have a different number of S-SSB candidate opportunities. The WTRU may be (pre)configured with an association between the S-SSB transmission (pre)configuration and the priority level of the SyncRef WTRU.

[0369] In one example, when the priority level of a SyncRef WTRU is higher than or equal to a (pre)configured threshold, the SyncRef WTRU may apply an S-SSB transmission (pre)configuration. The S-SSB transmission timing of such an S-SSB transmission (pre)configuration may not overlap with the S-SSB transmission (pre)configuration associated with a priority level lower than the threshold. Therefore, the SyncRef WTRU may avoid competing for the channel at the same S-SSB transmission timing. In another example, an S-SSB transmission (pre)configuration associated with a priority level higher than or equal to a (pre)configured threshold may have more S-SSB candidate timings. Therefore, a SyncRef WTRU with a high priority level may access the channel more frequently.

[0370] In another method, the WTRU may be (pre)configured with multiple starting positions associated with priority levels of one or more S-SSB candidate opportunities (pre)configured for S-SSB transmission. In one example, the starting position may be indicated by a timing offset before a symbol boundary of the first symbol of the S-SSB candidate opportunity. The timing offset may be an integer number of (pre)configured time units of an LBT sensing slot, contention period, symbol, mini-slot, and / or slot. A starting position with a large timing offset may indicate an earlier starting position for the S-SSB candidate opportunity. The WTRU may perform a reserved signal transmission and / or CPE transmission from the starting position to the start of the S-SSB candidate opportunity. In another example, the starting position may be indicated by the duration of the CPE transmission performed before the symbol boundary of the first symbol of the S-SSB transmission. The WTRU may be (pre)configured with a set of CPE durations to indicate the starting position for the S-SSB candidate opportunity.

[0371] A SyncRef WTRU of a high priority level may start CPE transmission at an earlier starting position before an S-SSB candidate opportunity that is (pre)configured with multiple starting positions associated with priority levels and thus block channel access by another SyncRef WTRU of a lower priority level.

[0372] The WTRU may also be (pre)configured with a single starting position for one or more S-SSB candidate opportunities for S-SSB transmission (pre)configured. At these S-SSB candidate opportunities, the SyncRef WTRU may access the channel regardless of the priority level.

[0373] In some cases, the WTRU may perform the SLU channel access and resource selection procedures for initiating a reserved COT to perform a retransmission of a TB transmitted in the previous COT.

[0374] When the number of transmissions performed may be less than the determined total number of transmissions (N) including initial transmissions and retransmissions to be performed within the determined RSW of the TB TX ), the WTRU may determine to perform LBT sensing-based SLU channel access and resource selection for COT initiation after performing initial transmission and retransmission of TB in the shared or initiated COT.

[0375] The WTRU may indicate the COT and / or resource reservation window in the SCI of the PSSCH / PSCCH transmissions performed in the shared or initiated COT. The WTRU may perform channel access and resource selection for COT initiation within the indicated window. In one example, the WTRU may indicate L w The value of the logical time slot, such as the length of the resource pool for PSSCH / PSCCH transmission is Lw The WTRU may determine L based on the remaining PDBs of the TB to be transmitted. w .

[0376] The start of the reservation window may be (pre)configured relative to the end of the COT in which the SCI including the reservation window information may be transmitted. In one example, when the WTRU performs transmission of a TB in a shared or initiated COT ending in time slot (t), the starting time slot of the reservation window may be time slot (t+T ch ), where T ch may be a (pre)configured processing time, and the end slot of the window may be the time slot (t+T ch +L w +1). In another example, the indicated window length and the window start and end slots may use units of physical time slots.

[0377] The WTRU may perform LBT sensing-based SL U channel access and resource selection for COT initiation within the indicated window, and upon successful channel access, the WTRU may determine the available resources within the initiated COT based on the resource selection in the initiated COT. When the LBT sensing-based SL U channel access is unsuccessful within the indicated reservation window, the WTRU may indicate the failure of the channel access and resource selection triggered by the transmitted TB to the higher layers.

[0378] In some cases, there may be a SLU channel access and resource selection procedure for initiating a reserved COT to perform initial transmissions and retransmissions of new TBs.

[0379] When COT and / or resource reservation for another TB for COT sharing is enabled in the resource pool, the WTRU may perform semi-static COT and / or resource reservation for initial transmission and retransmission of another TB.

[0380] The reservation interval may be indicated in ms or the number of logical time slots or physical time slots between the current COT and the reserved COT for transmission of another TB by the same WTRU. The WTRU may be (pre)configured to reserve a COT of the same length as the current COT. Furthermore, the WTRU may be (pre)configured to reserve the same frequency resources as those used within the current COT.

[0381] In one example, the retention window associated with the indicated retention interval may be included in the same SCI (e.g., the retention window is associated with the retention interval and both information are included in the SCI). The WTRU may determine the length of such associated retention window based on the remaining PDB of the TB transmitted in the current COT. The WTRU may assume that the TB transmitted in the current COT and the TB transmitted in the reserved COT have the same remaining PDB. In another example, such associated retention window may have a (pre)configured length.

[0382] When the WTRU performs transmission of a TB in the first SL slot (t) of the initiated or first shared SL slot (t) in the shared COT, the WTRU may indicate the reserved interval (P rsvp_TX ). This indication may inform the WTRU that it may perform SL U channel access and resource selection for COT initiation to initiate a COT starting at and / or including the SL timeslot (t+P rsvp_TX In another example, the WTRU may perform SLU channel access and resource selection for COT sharing to share the COT (t+P) including the SL time slot. rsvp_TX ).

[0383] In another example, the WTRU may perform SL U channel access and resource selection for COT initiation to initiate COT within the associated reservation window. The associated reservation window may be (pre)configured to include the SL time slot (t+P) at the beginning, middle, end, or in a (pre)configured position of the window. rsvp_TX ). The WTRU may initiate and / or share a COT within an associated retention window.

[0384] In another method, the reservation window may include a period of time reserved for type 1 LBT channel access before the reserved COT. The WTRU may determine the duration of the period based on the duration of the LBT contention window indicated in the CAPC configuration according to the priority of the TB to be transmitted in the reserved COT. The WTRU may perform type 1 LBT sensing channel access within this period to initiate the reserved COT in the reservation window.

[0385] In another example, when the WTRU performs transmission of a TB in a time slot (t) in an initiated or shared COT, the WTRU may indicate a reserved range and / or delay limit in the SCI associated with the PSSCH / PSCCH transmission performed in the COT. The WTRU may perform LBT sensing-based SLU channel access and resource selection for COT initiation to initiate a COT of the same length within the indicated range and / or before the delay limit. The WTRU may indicate the start and end slots of the range and delay limit in units of logical time slots of the resource pool. In another example, a physical time slot may be applied to the indication. The WTRU may determine the range and / or delay limit based on one or more factors, such as the remaining PDB of the TB to be transmitted.

[0386] Upon successful channel access within the indicated associated window, range and / or latency bounds, the WTRU may determine the available resources within the initiated COT based on resource selection in the initiated COT. When SLU channel access based on LBT sensing is unsuccessful, the WTRU may indicate to higher layers the failure of channel access and resource selection triggered by the transmitted TB.

[0387] Figure 6 An example of WTRU resource group / COT selection prior to Type 1 LBT for COT initiation is illustrated. In some cases, the WTRU may select a resource group / COT prior to LBT for COT initiation. As shown, time may be shown on the horizontal axis. The WTRU may determine a set of resource groups and / or COTs based on sensing information (e.g., SCI, RSRP, etc.) prior to performing Type 1 LBT to initiate a COT.

[0388] In one example, a resource group may include several time slots, in each of which several RB interlaces are selected for initial transmission or retransmission of a TB. The COT may be the duration of such a resource group, such as the number of consecutive time slots. In one example, the duration of a resource group may be the maximum COT indicated in the CAPC configuration corresponding to the priority of the TB.

[0389] In another example, the duration of the resource group may include a period before the COT. The WTRU may determine the duration of the period based on the duration of the LBT contention window indicated in the CAPC configuration and associated with the priority of the TB to be transmitted in the reserved COT. The WTRU may reserve the SL slots in the determined period included in the resource group. The reserved period may be intended for the WTRU to perform a type 1 LBT sensing channel access before initiating the reserved COT.

[0390] At 601, the WTRU may determine a resource selection window (RSW) 606 between time slots (n+T1) and (n+T2), where T1 and T2 may be (pre)configured WTRU processing times and values ​​based on the indicated remaining PDB (e.g., sensing window means that the WTRU decodes all detected SCIs and other related information and stores the information for processing and later use). At 602, the WTRU may be triggered by higher layers to transmit a priority (priority) in time slot (n). TX ) and SLTB of the remaining PDB.

[0391] In some examples, the WTRU may determine the total number of initial transmissions and retransmissions of the TB based on the indicated priority of the TB. The WTRU may determine the total number of SL slots used for initial transmissions and retransmissions of the TB, which may be the same as the total number of transmissions of the TB. In one method, if the priority of the TB corresponds to an MCOT of X slots and the total number of transmissions of the TB is Y, the WTRU may determine the number of required resource groups (N required ) and / or the COT for transmission can be Ceiling(Y / Z), such as the nearest integer greater than Y / Z.

[0392] In some instances, the WTRU may determine the number (N) of resource groups and / or COTs within the RSW to acquire using Type 1 LBT. Due to LBT uncertainty, the WTRU may determine a number greater than the required number (e.g., N=N required + offset). The offset may be a (pre)configured value. In one approach, the offset may be associated with the channel congestion level and / or the priority of the TB. A larger offset may be associated with a high congestion level and a high priority of the TB. An increased number of resource groups and / or COTs may allow the WTRU to perform more Type 1 LBT to acquire a channel.

[0393] In some instances, the WTRU may determine the location of N resource groups and / or COTs within the RSW based on the reserved COT / resource information decoded in sensing. The WTRU may exclude from the RSW one or more of the following time slots: time slots reserved in the COT and / or resource reservation; and / or RSRP of the resources / COTs whose reservation measured at the PSSCH / PSCCH transmission may exceed a (pre)configured threshold, where the value of the threshold may be based on a priority (priority) associated with the PSSCH / PSCCH transmission. resv ) and the priority of the TB to be transferred (priority TX ).

[0394] Among the remaining SL slots in the RSW, the WTRU may determine N selected resource groups and / or COTs (e.g. Figure 6Before each selected resource group and / or COT, the WTRU may determine the associated LBT period to perform the Type 1 LBT procedure. The duration of the LBT period may be (pre)configured.

[0395] In some examples, the WTRU may determine the frequency resources in each time slot of the selected resource group and / or COT. The frequency resources may be a number of subchannels or a number of RBs of an interlace. The determination of the subchannel or RB interlace may be based on one or more of the following: the total number of subchannels or RB interlaces (pre-)configured in the resource pool; WTRU source and / or destination ID; random selection; logical time slot index; and / or a (pre-)configured pattern.

[0396] like Figure 6 As shown, the WTRU may perform a Type 1 LBT procedure in an LBT period associated with a selected resource group and / or COT. When the channel is sensed as available, the WTRU may perform transmission of a channel reservation signal and / or CPE before the earliest time slot boundary (e.g., 605A and 605B). The WTRU may initiate a COT and perform transmission of a TB at a time slot boundary (e.g., 607A and 607B). When the channel is sensed to be busy at the end of the LBT period, the WTRU may stop LBT sensing (e.g., stop the LBT procedure for this period) and perform a Type 1 LBT procedure at an LBT period associated with the next selected resource group and / or COT.

[0397] like Figure 6 As shown in the example in , during the LBT period 612 associated with the first selected resource group and / or COT 613 within the RSW 606, the WTRU fails to acquire the channel (e.g., the channel is not available at the beginning of the selected resource group / COT / time window) and stops the Type 1 LBT. The WTRU may perform a Type 1 LBT (e.g., 604) in the LBT period 615 associated with the second selected resource group and / or COT 616, and the LBT may be successful (e.g., the channel is available at the beginning of the selected resource group / COT / time window) and initiate a COT for SL transmission (e.g., 607A). The WTRU may send a reservation signal 605A before transmitting the TB 607A. When the determined number of COTs to be initiated (N required) is greater than the number of COTs already initiated, the WTRU may continue to perform Type 1 LBT in the LBT period 618 associated with the next selected resource group and / or COT (e.g., the third selected resource group 619). In this example, the WTRU initiates another COT 619 at the third selected resource group and / or COT and the LBT is successful and all transmissions determined for the TB are completed (e.g., 607B). The WTRU may send a reservation signal 605B before transmitting the TB 607B. When the transmission is complete, the WTRU may not perform LBT and acquire channels at the remaining selected resource groups and / or COTs within the RSW (e.g., LBT may not need to be performed between 619 and 620).

[0398] In one example, Figure 5 and Figure 6 The examples may be read together, where the second selected resource group (COT) 616 covers instances where the WTRU 501 and the WTRU 502 perform LBT and the WTRU 502 sends a reservation signal and transmits a TB (e.g., 521, 522, 531, and 532). In addition, the third selected resource group (COT) 619 may cover situations where the WTRU 501 performs LBT, sends a reservation signal, and is able to transmit TBs of that WTRU (e.g., 522 and 523). In this combined example, neither the WTRU 501 nor the WTRU 502 is able to access the channel during the first selected group (e.g., due to a busy channel). Therefore, the WTRU 501 and the WTRU 502 may perform LBT at the next available opportunity (e.g., time) in the second selected resource group 616. The number of starting positions associated with priority 1 (e.g., as Figure 5 ) will be greater than priority 2. When the channel is idle, the WTRU 501 may first complete LBT, but during the long gap to the (pre)configured starting position of the WTRU 501, the WTRU 502 may first access the channel and transmit its TB. The WTRU 501 must then perform LBT before its associated next starting position and determine if the channel is idle.

[0399] Generally, when the WTRU does not acquire channels in all selected resource groups and / or COTs and / or the number of initiated COTs is less than the determined number of required COTs (N required ), the WTRU may indicate LBT failure to higher layers. In another case, when Type 1 LBT sensing channel access fails before one or more selected resource groups and / or COTs, the WTRU may trigger resource reselection.

[0400] The WTRU may perform a channel access (e.g., type 1 LBT channel access) before the start of the selected resource group. When the channel is sensed as available, the WTRU may initiate a COT and perform a PSSCH / PSCCH transmission in the selected resource. In one case, when the channel is sensed to be busy at the start of the selected resource group, the WTRU may stop the channel access and perform a new channel access before the next selected resource group within the resource selection window. In another case, when the channel is sensed to be busy at the start of the selected resource group, the WTRU may continue to perform LBT channel access in the selected resource group. The WTRU may sense that the channel is idle within the selected resource group and may initiate a COT using the remainder of the resource group. In another example, when the number of remaining logical time slots in the selected resource group exceeds a (pre)configured threshold, the WTRU may indicate a COT with the remainder of the selected resource group.

[0401] In some cases, the WTRU may initiate a COT with an MCOT that overlaps with the reserved resources / COT. When the WTRU is triggered to perform resource selection for a TB with priority (p), the WTRU may determine the transmission duration, such as the number of consecutive SL slots used for transmission in the initial transmission and retransmissions of the TB. The WTRU may determine the maximum COT (MCOT) duration based on the priority from the CAPC configuration.

[0402] When the WTRU selects a resource group and / or COT for initiation, including a time period for type 1 LBT sensing channel access and a determined transmission duration (as discussed herein), the WTRU may initiate a COT with a MCOT duration that may overlap with a reserved resource group and / or COT. The WTRU may not perform transmissions during the overlapping duration, such as the determined transmission duration may not overlap with any reserved resource group and / or COT. In addition, the WTRU may indicate in the SCI that the overlapping duration within the COT may not be shared by another WTRU. In one example, the WTRU may indicate "disabled" in the COT sharing SCI indication. In another example, the WTRU may explicitly indicate the index of the non-overlapping SL time slots to be shared within the COT.

[0403] In some cases, the WTRU may initiate a COT based on frequency domain multiplexing. The WTRU may select a resource group that may overlap in time with a reserved resource group and / or COT to initiate a COT. The WTRU may select one or more frequency resources that may not be reserved in a resource group and / or COT reservation. For example, a frequency resource may include one or more RBs, one or more subchannels, one or more RB interlaces, and / or one or more RB sets.

[0404] The WTRU may determine to perform a Type 1 LBT prior to the selected resource group. The WTRU may determine to initiate a COT within the selected resource group when one of the following occurs: the channel may be sensed as available as a result of the Type 1 LBT; and / or the channel may be sensed as busy due to the Type 1 LBT and the decoded SCI may indicate that the selected frequency resources cannot be used.

[0405] The WTRU may perform PSSCH / PSCCH transmission within the initiated COT in frequency resources different from the resource group detected in the SCI sensing and / or frequency resources indicated in the COT reservation.

[0406] In another example, when the channel is sensed as busy due to a Type 1 LBT and the decoded SCI may indicate that the selected frequency resources may be used, the WTRU may perform frequency reselection. The WTRU may perform a PSSCH / PSCCH transmission within the initiated COT in a frequency resource different from the frequency resource indicated in the SCI received during the Type 1 LBT.

[0407] Thus, the WTRU may initiate a COT that may be frequency domain multiplexed (via FDM) with the reserved and / or ongoing resource groups and / or COTs. The WTRU may be (pre)configured to perform such COT initiation via FDM when one or more of the following occurs: the number of candidate resource groups and / or COTs within the RSW is below a (pre)configured threshold; the channel congestion metric (e.g., CBR and / or CO) exceeds a (pre)configured threshold.

[0408] In some cases, the WTRU may determine the success or failure of the SLU channel access and resource selection. The WTRU may perform one or more SLU channel access and resource selections for COT initiation in the determined RSW. When the determined number (N) of SLU channel access and resource selections have been performed, the WTRU may perform one or more SLU channel access and resource selections for COT initiation in the determined RSW. TX ), the WTRU may stop performing SLU channel access and resource selection based on LBT sensing for COT in the determined RSW. The WTRU may indicate to higher layers the success of the channel access and resource selection triggered by the transmitted TB.

[0409] The WTRU may stop executing process_min ) in which time slot (n+T2) is the determined end of RSW, and T process_min is the (pre)configured minimum processing time, and / or the number of executed transfers (N) within the initiated COT and / or the shared COT within the RSW tx_performed ) is less than the determined number of TBs transferred (N TX )(Ntx_performed <N TX ). In this case, the WTRU may indicate to higher layers the failure of channel access and resource selection triggered by the transmitted TB.

[0410] In another example, the WTRU may be (pre)configured with a percentile threshold (Th tx %), the percentile threshold may indicate the relative to the determined number (N TX ) is the minimum number of transmissions to be performed for a TB. process_min ), the WTRU may indicate to higher layers the failure of channel access and resource selection triggered for transmitted TBs; for example, the number of performed transmissions (N) within the initiated COT and / or the shared COT within the RSW. tx_performed ) when the number of TB transfers (N) is less than tx_performed <Th tx %×N TX ). Otherwise, the WTRU may indicate to higher layers the success of the channel access and resource selection triggered for the transmitted TB. In another example, such a threshold may be associated with the priority of the TB, and the WTRU may select the threshold based on the (pre-)configuration and the priority of the TB to be transmitted.

[0411] In one example, when the WTRU initiates a COT, the WTRU may determine that a gap period applies at the end of the last PSSCH / PSCCH transmission scheduled in the COT. The WTRU may perform TX / RX switching during this gap period. In one example, the gap period may be (pre)configured with a duration greater than 16us, and a gap period of one symbol may be (pre)configured for a resource pool with an SCS of 15kHz, 30kHz, and 60kHz. In another example, the gap period may be (pre)configured with a duration greater than 25us. In this case, a gap period of one symbol may be (pre)configured in a resource pool with an SCS of 15kHz and 30kHz, and a gap period of two symbols may be configured in a resource pool with an SCS of 60kHz.

[0412] In some cases, there may be a WTRU physical layer LBT failure indication based on channel access for PSSCH / PSCCH transmission. Based on a Type 1 LBT channel access performed at one or more selected resource groups and / or COTs in the RSW for PSSCH / PSCCH transmission, the WTRU may indicate an LBT failure to higher layers. Examples of such selected resource groups and / or COTs are described in Figure 6 Shown in.

[0413] In some instances, the WTRU may indicate LBT failure to higher layers based on one or more circumstances.

[0414] For example, when the WTRU performs a Type 1 LBT channel access and fails to access the channel and fails to perform a PSSCH / PSCCH transmission during one of the selected resource groups and / or COTs within the RSW, the WTRU may indicate an LBT failure. The WTRU may evaluate the LBT failure indication for each selected resource group and / or COT within the RSW.

[0415] For example, when the WTRU performs a Type 1 LBT channel access and fails to access the channel and fails to perform a PSSCH / PSCCH transmission during the first selected resource group and / or COT within the RSW, the WTRU may indicate an LBT failure. The WTRU may not indicate an LBT failure at subsequent selected resource groups and / or COTs within the RSW regardless of the LBT channel access result. The WTRU may evaluate the LBT failure indication for each RSW.

[0416] For example, when the WTRU performs a Type 1 LBT channel access and fails to access the channel and fails to perform PSSCH / PSCCH transmissions during all selected resource groups and / or COTs within the RSW, the WTRU may indicate an LBT failure. Thus, the WTRU may evaluate the LBT failure indication for each RSW.

[0417] For example, when the WTRU performs a Type 1 LBT channel access and fails to access the channel and fails to perform a PSSCH / PSCCH transmission during each of a certain number of selected resource groups and / or COTs within a RSW, the WTRU may indicate an LBT failure. The WTRU may determine this number based on a (pre-)configured ratio relative to the total number of selected resource groups and / or COTs within the RSW. The WTRU may evaluate this LBT failure indication for each RSW.

[0418] In some examples, the WTRU may indicate LBT failure to higher layers based on the number of PSSCH / PSCCH transmissions performed within the RSW. The WTRU may indicate LBT failure based on one or more situations.

[0419] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel and fail to perform PSSCH / PSCCH transmissions of TBs within the RSW.

[0420] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to perform the required number of PSSCH / PSCCH transmissions for the TBs within the RSW. When the WTRU is triggered for resource selection and LBT channel access for COT initiation by higher layers, the WTRU may determine the required number of PSSCH / PSCCH transmissions including initial transmission and retransmissions of one or more TBs.

[0421] In some examples, the WTRU may indicate LBT failure to higher layers based on a Type 1 LBT channel access performed for a PSSCH / PSCCH transmission scheduled by a base station. The WTRU may indicate LBT failure based on one or more situations.

[0422] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel before the start of a PSSCH / PSCCH transmission scheduled in a dynamic grant (DG). The WTRU may determine the start of a PSSCH / PSCCH transmission based on SL transmission timing information received in a DCI including a dynamic grant. The SL timing information may be indicated as the time gap (e.g., in units of logical SL slots) between the DL timeslot in which the DCI is received and the SL timeslot in which the PSSCH / PSCCH transmission is scheduled.

[0423] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel and perform PSSCH / PSCCH transmissions within the scheduled transmission period / window indicated in the dynamic grant (DG). The WTRU may receive SL transmission period and / or window duration information (e.g., in logical time slots) in the DCI including the dynamic grant. The period and / or window may start from the DL time slot in which the DCI is received and end after the indicated duration.

[0424] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel prior to the start of a periodic SL transmission according to a configured grant (CG). The WTRU may determine the start of a SL transmission based on transmission timing information included in the RRC configuration of the configured grant. The timing information may include a transmission periodicity, a reference slot, and / or a slot offset.

[0425] In some instances, the WTRU may indicate an LBT failure to higher layers based on a Type 2 LBT channel access performed for a PSSCH / PSCCH transmission. The WTRU may indicate an LBT failure when the following occurs. The WTRU may perform a Type 2 LBT channel access (e.g., Type 2A / 2B) and fail to access the channel before the starting position associated with the priority of the TB to be transmitted in the current shareable COT. As a result, the WTRU may not be able to share the current shareable COT (e.g., Figure 3 shown).

[0426] In some cases, there may be a WTRU physical layer LBT failure indication based on channel access for a PSFCH transmission. The WTRU may indicate an LBT failure to higher layers based on a Type 1 LBT channel access performed for one or more PSFCH transmissions at one or more PSFCH opportunities within the HARQ latency. In one example, such a PSFCH opportunity may be within a PSFCH slot outside of the COT that includes the PSSCH / PSCCH transmission associated with the PSFCH transmission.

[0427] The WTRU may determine the HARQ delay based on the QoS of the TB and indicate the HARQ delay in the SCI of the PSSCH / PSCCH transmission. In another example, the HARQ delay may be (pre)configured in association with a priority and the WTRU may determine the HARQ delay accordingly based on such (pre)configuration and the L1 priority indicated in the SCI of the associated PSSCH / PSCCH transmission.

[0428] In another example, the WTRU may determine the HARQ latency to be indicated in the SCI for the PSSCH / PSCCH transmission based on the received PUCCH resource configuration / scheduling. The WTRU may perform the PSSCH / PSCCH transmission based on the SL scheduling grant received from the base station in the DCI. The WTRU may receive the PUCCH resource configuration / scheduling in the same DCI to transmit the PUCCH carrying the SL HARQ feedback information associated with the scheduled PSSCH / PSCCH transmission. Therefore, the WTRU may indicate an LBT failure to higher layers based on a Type 1 LBT channel access performed for a PSFCH transmission to be included in the PUCCH scheduled by the base station.

[0429] The WTRU may determine one or more PSFCH time slots, each PSFCH time slot comprising a PSFCH opportunity within the determined HARQ delay. In one example, the PSFCH time slots may be (pre)configured in a resource pool. In another example, the PSFCH time slots may be indicated in the SCI of the associated PSSCH / PSCCH transmission.

[0430] In some instances, the WTRU may indicate LBT failure to higher layers in one or more circumstances.

[0431] For example, the WTRU may perform a Type 1 LBT channel access and fail to access the channel before the start of each PSFCH opportunity within the HARQ delay. The WTRU may evaluate the LBT failure for each PSFCH opportunity.

[0432] For example, the WTRU may perform a Type 1 LBT channel access and fail to access the channel before the start of the first PSFCH opportunity within the determined HARQ delay. The WTRU may not indicate LBT failure at subsequent PSFCH opportunities and may therefore evaluate LBT failure for each HARQ delay.

[0433] In some examples, the WTRU may indicate LBT failure to higher layers based on whether PSFCH transmission can be performed within the HARQ delay. The WTRU may indicate LBT failure in one or more situations.

[0434] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel and perform a PSFCH transmission within the HARQ delay. The WTRU may evaluate the LBT failure for each HARQ delay.

[0435] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel and perform a PSFCH transmission prior to a scheduled PUCCH transmission. The WTRU may evaluate the LBT failure for each scheduled PUCCH transmission.

[0436] For example, the WTRU may perform one or more Type 1 LBT channel accesses and fail to access the channel at a number of PSFCH opportunities before a successful PSFCH transmission within the HARQ delay. The number of such PSFCH opportunities may be (pre)configured in association with the priority. A low threshold may be (pre)configured for high priority to enable the WTRU to adjust the channel access parameters faster for HARQ feedback associated with high priority PSSCH / PSCCH transmissions.

[0437] For example, the WTRU may fail to receive a PSFCH transmission within the HARQ delay indicated in the performed PSSCH / PSCCH transmission. In another example, the WTRU may fail to receive a PSFCH transmission prior to a scheduled PUCCH transmission. The WTRU may report such LBT failure to the base station.

[0438] In some instances, the WTRU may indicate an LBT failure to higher layers based on a Type 2 LBT channel access performed for one or more PSFCH transmissions at one or more PSFCH opportunities within a HARQ delay. In one example, such a PSFCH opportunity may be within a PSFCH slot within a COT that includes a PSSCH / PSCCH transmission associated with the PSFCH transmission. The WTRU may indicate an LBT failure to higher layers in one or more cases. For example, a Type 2 LBT channel access (e.g., Type 2A / 2B) may be performed and a channel access may not be accessed prior to the start of a PSFCH opportunity in the current COT that may be shared for PSFCH transmissions.

[0439] In some cases, there may be a WTRU physical layer failure indication based on channel access for S-SSB (SL synchronization signal block) transmission. The WTRU may indicate LBT failure to higher layers based on Type 1 and / or Type 2 LBT channel access performed for one or more S-SSB transmissions at one or more S-SSB candidate opportunities within a (pre)configured S-SSB period. The WTRU may determine one or more S-SSB candidate opportunities (e.g., SL slots and symbol positions) based on the (pre)configured S-SSB period duration, the S-SSB start slot offset, and / or the spacing between S-SSBs within the period (e.g., all in logical SL slots).

[0440] In some instances, the WTRU may indicate LBT failure to higher layers based on one or more circumstances.

[0441] For example, when the WTRU performs Type 1 and / or Type 2 LBT (e.g., Type 2A / 2B) channel access and fails to access the channel before the S-SSB candidate opportunity and fails to perform an S-SSB transmission, the WTRU may indicate an LBT failure. The WTRU may evaluate the LBT failure indication for each S-SSB candidate opportunity.

[0442] For example, when the WTRU performs Type 1 and / or Type 2 LBT (e.g., Type 2A / 2B) channel access and fails to access the channel before the first S-SSB candidate opportunity within the S-SSB period, the WTRU may indicate an LBT failure. The WTRU may not indicate an LBT failure at the remaining S-SSB candidate opportunities within the S-SSB period. The WTRU may evaluate the LBT failure for each S-SSB period.

[0443] For example, when the WTRU performs one or more Type 1 and / or Type 2 LBT (e.g., Type 2A / 2B) channel accesses and fails to access the channel before all S-SSB candidate opportunities within the S-SSB period, the WTRU may indicate LBT failure. Thus, when the WTRU fails to perform any S-SSB transmission within the S-SSB period, the WTRU may indicate LBT failure.

[0444] For example, when the WTRU performs one or more Type 1 and / or Type 2 LBT (e.g., Type 2A / 2B) channel accesses and fails to access the channel before a (pre)configured number of S-SSB candidate opportunities within the S-SSB period, the WTRU may indicate an LBT failure.

[0445] The WTRU may adjust the S-SSB transmission parameters when the number of indicated S-SSB LBT failures exceeds a (pre)configured threshold. In one example, the WTRU may determine different S-SSB start slot offsets within the S-SSB period to access the channel at different times.

[0446] In some cases, there may be a physical layer indication of the WTRU with additional information of LBT failure. In addition to the LBT failure indication, the WTRU may also provide one or more of the following information to higher layers: the type of LBT channel access performed, such as Type 1, Type 2A, Type 2B LBT, etc.; the type of SL channel to be transmitted, such as PSSCH / PSCCH, PSFCH, S-SSB, etc.; the priority / CAPC configuration associated with the LBT channel access performed; and / or the mode of channel access, such as base station scheduled or WTRU autonomous.

[0447] In another example, when the number of failures of SLU channel access and resource selection as discussed herein may exceed a (pre)configured threshold, the WTRU may determine consecutive LBT sensing failures for SLU channel access and resource selection. In one example, the threshold may be the number of TBs that the WTRU may have failed to transmit due to LBT sensing failures. The WTRU may report such consecutive LBT sensing failures to higher layers. The WTRU may receive an LBT sensing configuration in response to the reported consecutive LBT sensing failures. For example, the CAPC configuration for subsequent LBT sensing for SLU channel access and resource selection may have a longer contention window.

[0448] Figure 7An example process of a WTRU transmitting a message in an unlicensed spectrum is illustrated. At some previous time, the WTRU may receive one or more configuration information in one or more messages. At 701, the WTRU may select a first channel occupation time (COT) period from a preconfigured number of candidate COT periods within a resource selection window (RSW). At 702, the WTRU may perform a first listen-before-talk (LBT) in the first COT period on a channel in the unlicensed spectrum. At 703, upon indicating that the first LBT is successful, the WTRU may determine a corresponding time gap until the earliest preconfigured transmission start time associated with a first priority of a side link transport block (SL-TB). At 704, the WTRU may transmit a channel reservation signal until the earliest preconfigured transmission start time associated with the first priority of the SL-TB. At 705, the WTRU may transmit a TB (e.g., transmit a physical side link shared channel transmission or a physical side link control channel transmission) at the earliest preconfigured transmission start time associated with the first priority of the SL-TB. At 706, in some instances, if the determined gap is greater than a symbol, the WTRU may perform a second LBT over a preconfigured number of time slots and proceed with the transmission of the PSSCH / PSCCH transmission based on the second LBT indicating that the channel is idle in all time slots. At 707, in some instances, a channel reservation signal may be transmitted under the condition that the determined gap is less than or equal to a preconfigured time period, where the preconfigured time period is a symbol. In some instances, the configuration information may include the number of candidate COT time periods within the RSW. In some instances, the first LBT may be type 1. In some instances, selecting the first COT time period may be based on COT reservation information from the sidelink control information (SCI). In some instances, the RSW may be determined based on the remaining packet delay budget (PDB) of the SL-TB.

[0449] Based on one or more techniques described herein, in one example, there may be one or more methods relating to SLU channel access and resource selection in Mode 2 based on LBT and SCI sensing based channel access for COT initiation and COT sharing performed within a resource selection window.

[0450] For example, a WTRU COT sharing method may include one or more steps. The WTRU may be triggered to perform a channel access and resource selection procedure for one or more TBs in time slot (n). The WTRU may determine: a channel access and resource selection window (RSW) between time slot (n+T1) and time slot (n+T2), where T1 is (pre)configured and T2 is based on the remaining PDBs of the TB; and / or a number of retransmissions based on the QoS of the TB and the corresponding total number of resources. The WTRU may determine based on SCI sensing that a COT is detected in a time slot within the determined RSW. The WTRU may determine to share the detected COT based on one or more subsequent decoded SCIs from the SCI sensing: the remaining duration of the detected COT; the number of scheduled transmissions within the COT; the frequency assignment of the scheduled transmissions; the broadcast type, WTRU source and / or destination ID associated with the TB transmitted in the COT; the priority associated with the TB to be transmitted by the WTRU; and / or a channel congestion indication. The WTRU may perform transmissions within the determined shared COT using: one or more time slots that are not scheduled for transmission; and / or one or more frequency resources that are not assigned for scheduled transmissions, such as RB interlace indices.

[0451] For example, a WTRU COT initiation method may include one or more steps. The WTRU may be triggered to perform a channel access and resource selection procedure for one or more TBs in time slot (n). The WTRU may determine the following: a channel access and resource selection window (RSW) between time slot (n+T1) and time slot (n+T2), where T1 is (pre) configured and T2 is based on the remaining PDB of the TB; and / or the number of retransmissions based on the QoS of the TB and the corresponding total number of resources. The WTRU may determine to perform the SLU channel access procedure for COT initiation using the RSW. The WTRU may suspend the SLU channel access procedure for COT initiation in a time slot that overlaps with a COT and / or resources reserved by another WTRU based on SCI sensing information. Upon successful channel access, the WTRU may determine the resources for transmission within the initiating COT and COT based on: the WTRU source and / or destination ID, type broadcast, priority of the TB to be transmitted; and / or the priority and scheduled resources of the PSSCH / PSCCH transmissions in the overlapping reserved COTs and / or resources. The WTRU may transmit a channel reservation signal, such as an AGC symbol and / or SL RS transmission, until the start of the initiated COT. The WTRU may transmit the PSSCH / PSCCH transmission of the TB within the initiated COT using the determined resources, where the following information is indicated in the SCI: the remaining duration of the detected COT; the number of scheduled transmissions within the COT; the frequency assignment of the scheduled transmissions; the priority, broadcast type, WTRU source and / or destination ID associated with the TB transmitted in the COT; and / or a channel congestion indication. The WTRU may repeat the channel access and resource selection initiated by the COT until: all determined TB transmissions are performed within the RSW; and / or time slot (n+T2-X), where X is the (pre)configured minimum processing time, and the number of performed transmissions is less than the number of transmissions of the determined TB. In one case, the WTRU may discard the remaining transmissions of the TB. Additionally / alternatively, the WTRU may indicate a failure of the SLU channel access and resource selection for the TB.

[0452] Based on one or more techniques described herein, in one example, there may be a WTRU determination that initiates the SL COT based on measured congestion conditions, such as the SL U CBR and time continuity of logical time slots within the SL COT based on a mapping between physical time slots and corresponding logical time slots in a resource pool for the SL COT.

[0453] Based on one or more techniques described herein, in one example, there may be a WTRU that switches between blind SCI decoding in each (pre)configured PSCCH resource in a resource pool outside a detected COT and SCI decoding in COT-specific PSCCH resources for the remaining duration of the detected COT.

[0454] Based on one or more techniques described herein, in one example, there may be a WTRU determination for SLCOT sharing based on the distance between the WTRU and the WTRU initiating the COT, the RSRP of the PSSCH / PSCCH DMRS, and the measured congestion status (e.g., SL U CBR).

[0455] Based on one or more of the techniques described herein, in one example, there may be a WTRU that performs LBT sensing channel access based on a COT and / or a resource reservation interval and an associated reservation window, a reservation range, a latency bound indicated in a semi-persistent COT, and / or a resource reservation in a previously transmitted SCI.

[0456] Based on one or more techniques described herein, in one example, there may be a WTRU dynamic determination of a COT starting location for COT initiation based on the priority of the TB, the priority associated with the COT starting location, and the channel congestion level.

[0457] Based on one or more techniques described herein, in one example, there may be COT sharing conditions based on the COT initiation / sharing indication in the SCI, the WTRU source and / or destination ID, the TB priority of the initiating and sharing WTRU, or the synchronization source.

[0458] Based on one or more techniques described herein, in one example, there may be a WTRU selection of Type 2A / 2B / 2C LBT procedures in COT sharing based on channel congestion, TB priority, broadcast and channel type, remaining PDB, and transmission duration.

[0459] Based on one or more techniques described herein, in one example, there may be a WTRU determining a shared frequency reuse-based COT that mutes interlaced RBs to mitigate interference and sets transmit power based on PSD control, transmit bandwidth, and measured power in the shared COT.

[0460] Based on one or more techniques described herein, in one example, there may be WTRU dynamic adjustment of the energy detection threshold (EDT) based on channel congestion, channel type, HARQ feedback status, CSI reporting, COT initiation / sharing, etc.

[0461] Based on one or more techniques described herein, in one example, there may be a WTRU COT initiation based on resource / COT selection prior to Type 1 LBT using resource / COT reservation information from sensing.

[0462] Based on one or more techniques described herein, there may be a method implemented by a WTRU. The WTRU may receive a trigger message prompting to perform LBT and resource selection in order to transmit a SL-TB. The WTRU may determine the RSW based on the remaining PDB of the SL-TB remaining PDB. The WTRU may select frequency resources based on the WTRU source / destination ID. The WTRU may select a (pre)configured number of candidate COT periods within the determined RSW based on COT reservation information sensed from the sidelink control information. The WTRU may perform LBT in the first determined candidate COT period for measurement. At the time of successful LBT, the WTRU may determine the corresponding time gap until the earliest preconfigured transmission start position associated with the L1 priority of the SL-TB. When the determined gap is less than or equal to the preconfigured time period, the WTRU may transmit a channel reservation signal until the earliest preconfigured transmission start position associated with the L1 priority of the SL-TB. The WTRU may transmit the PSSCH / PSCCH at the earliest preconfigured transmission start position associated with the L1 priority of the SL-TB. The WTRU may perform LBT sensing on a (pre)configured number of sensing slots, subject to the condition that the determined gap is greater than a symbol, and may proceed with transmission of PSSCH / PSCCH when the channel is idle in all sensed slots. The preconfigured time period may be a symbol. The frequency resource may be an index of a resource block interlace. The WTRU may perform sidelink control information (SCI) sensing. The LBT may be type 1. The WTRU may receive configuration information at an initial point, which may be related to performing one or more of the above actions.

[0463] In one or more embodiments disclosed herein, there may be a WTRU procedure that performs both COT-shared and COT-initiated SLU channel access and resource selection within the RSW.

[0464] In one or more embodiments disclosed herein, there may be a WTRU determination of SL COT detection and sharing based on SCI sensing information, which SCI sensing information includes remaining duration, number of scheduled transmissions within the COT, frequency resource assignment, priority, broadcast type, WTRU source and / or destination ID, COT / resource reservation, channel congestion, etc.

[0465] In one or more embodiments disclosed herein, there may be a WTRU determination of SL COT initiation based on LBT and SCI sensing information including COT / resource reservation, priority, broadcast type, WTRU source and / or destination ID, channel congestion, etc.

[0466] In one or more embodiments disclosed herein, there may be a WTRU determination of transmission resources within the shared and initiated SL COTs based on the WTRU source and / or destination ID of the TB to be transmitted, and the RB interleaving assignment indicated in the decoded SCI associated with the overlapping reserved COT.

[0467] As described herein, a higher layer may refer to one or more layers in a protocol stack, or a specific sublayer within a protocol stack. A protocol stack may include one or more layers in a WTRU or a network node (e.g., an eNB, a gNB, other functional entities, etc.), each of which may have one or more sublayers. Each layer / sublayer may be responsible for one or more functions. Each layer / sublayer may communicate directly or indirectly with one or more layers in other layers / sublayers. In some cases, these layers may be numbered, such as layer 1, layer 2, and layer 3. For example, layer 3 may include one or more of the following: non-access stratum (NAS), Internet protocol (IP), and / or radio resource control (RRC). For example, layer 2 includes one or more of the following: packet data convergence control (PDCP), radio link control (RLC), and / or medium access control (MAC). For example, layer 3 may include physical (PHY) layer type operations. The larger the number of a layer, the higher the layer is relative to other layers (e.g., layer 3 is higher than layer 1). In some cases, the foregoing examples may be referred to as layers / sublayers themselves, regardless of the layer number, and may be referred to as higher layers as described herein. For example, from highest to lowest, a higher layer may refer to one or more of the following layers / sublayers: a NAS layer, an RRC layer, a PDCP layer, an RLC layer, a MAC layer, and / or a PHY layer. Any reference to a higher layer in conjunction with a process, device, or system herein will refer to a layer higher than the layer of the process, device, or system. In some cases, references to a higher layer herein may refer to a function or operation performed by one or more layers described herein. In some cases, references to a higher layer herein may refer to information sent or received by one or more layers described herein. In some cases, references to a higher layer herein may refer to a configuration sent and / or received by one or more layers described herein.

[0468] Although features and elements are described above in particular combinations (e.g., embodiments, methods, examples, etc.), it will be understood by one of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. For example, as disclosed herein, for illustrative purposes, there may be a method described in conjunction with the accompanying drawings, and it will be understood by one of ordinary skill in the art that one or more features or elements from this method may be used alone or in combination with one or more features from another method described elsewhere (e.g., in another accompanying drawing, or in a separate portion of the specification). In addition, the methods described herein may be implemented in a device running a computer program, software, and / or firmware that is incorporated in a computer-readable medium for execution by a computer and / or processor operatively connected to a (e.g., wireless or wired) transceiver of the device. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as internal hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor in association with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method implemented by a wireless transmit receive unit (WTRU), the method comprising: receiving configuration information indicating a set of cyclic prefix extension (CPE) starting positions associated with a shared channel occupation time (COT), wherein each CPE starting position in the set of CPE starting positions is associated with a sidelink transmission priority, Where each CPE has a duration; receiving a sidelink control information (SCI) message, wherein the SCI message indicates a remaining COT duration; transmitting a CPE in the shared COT at a starting position for a duration, wherein the starting position of the CPE and the duration are determined based on a priority of a sidelink message and the configuration information; The sidelink message is transmitted in the shared COT after the CPE at a transmission time determined according to the remaining COT duration.

2. The method of claim 1 , wherein the shared COT is initiated by a second WTRU that sends the SCI message.

3. The method of claim 1, wherein the sidelink message is a physical sidelink control channel (PSCCH) message or a physical sidelink shared channel (PSSCH) message. The method of claim 1 , wherein the SCI message indicates sharing of the shared COT.

5. The method of claim 1, wherein a Type 2 Listen Before Talk (LBT) is performed prior to transmitting the CPE.

6. The method of claim 1, wherein transmitting the CPE in the shared COT is further based on performing Type 2 Listen Before Talk (LBT).

7. The method of claim 1, wherein the SCI message is received in a time slot, wherein the transmission time is further determined based on the time slot.

8. A wireless transmit-receive unit (WTRU), the WTRU comprising: a processor operatively coupled to the transceiver, The processor and the transceiver are configured to receive configuration information indicating a set of cyclic prefix extension (CPE) starting positions associated with a shared channel occupancy time (COT), wherein each CPE starting position in the set of CPE starting positions is associated with a sidelink transmission priority, Where each CPE has a duration; The processor and the transceiver are configured to receive a side link control information (SCI) message, wherein the SCI message indicates a remaining COT duration; The processor and the transceiver are configured to transmit a CPE in the shared COT at a starting location for a duration, wherein the starting location of the CPE and the duration are determined based on a priority of a sidelink message and the configuration information; The processor and the transceiver are configured to transmit the sidelink message in the shared COT after the CPE at a transmission time determined according to the remaining COT duration.

9. The WTRU of claim 8, wherein the shared COT is initiated by a second WTRU that sends the SCI message.

10. The WTRU of claim 8, wherein the sidelink message is a physical sidelink control channel (PSCCH) message or a physical sidelink shared channel (PSSCH) message.

11. The WTRU of claim 8, wherein the SCI message indicates sharing of the shared COT.

12. The WTRU of claim 8, wherein a Type 2 Listen Before Talk (LBT) is performed prior to transmitting the CPE.

13. The WTRU of claim 8, wherein transmitting the CPE in the shared COT is further based on performing Type 2 Listen Before Talk (LBT).

14. The WTRU of claim 8, wherein the SCI message is received in a time slot, wherein the transmission time is further determined based on the time slot.

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