Methods, architectures, apparatus and systems for broadband operation for side chains in unlicensed frequency bands

Abstract

The present disclosure relates to methods, architectures, devices, and systems for broadband operation for sidechain communications in an unlicensed frequency band. In an embodiment, a method may be implemented in a wireless transmit / receive unit (WTRU). The method may include receiving scheduling information for one or more side chain transmissions from a network. The scheduling information may indicate a set of scheduled resources. The method may include performing listen before talk (LBT) in a set of scheduled resources for obtaining a subset of resources in the set of scheduled resources. The method may include transmitting side chain control information indicating the acquired subset of resources. The method may include transmitting data in the acquired subset of resources. The method may include transmitting feedback information related to the one or more sidechain transmissions to the network based on the number of resources acquired and the number of scheduled resources (e.g., a ratio between).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application No. 63 / 395,627 filed on August 5, 2022, U.S. Patent Application No. 63 / 445,551 filed on February 14, 2023, and U.S. Patent Application No. 63 / 468,619 filed on May 24, 2023, each of which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to wireless communications. For example, one or more embodiments disclosed herein relate to methods, architectures, devices, and systems for wideband operation for sidelink communications in unlicensed bands. Background Art

[0003] In unlicensed bands, a channel access procedure prior to transmission allows for fair sharing of the unlicensed spectrum among different radio access technologies.The embodiments described herein have been designed with the above in mind. Summary of the invention

[0004] Methods, architectures, apparatus, and systems related to broadband operation for sidelink communications in unlicensed bands are described herein. In one embodiment, a method implemented in a wireless transmit / receive unit (WTRU) is described herein. The method may include receiving scheduling information for one or more sidelink transmissions from a network. The scheduling information may indicate a set of scheduled resources. The method may include performing listen before talk (LBT) in the set of scheduled resources to obtain a subset of resources in the set of scheduled resources. The method may include transmitting sidelink control information indicating the acquired subset of resources. The method may include transmitting data in the acquired subset of resources. The method may include transmitting feedback information related to the one or more sidelink transmissions to the network based on (e.g., a ratio between) the number of acquired resources and the number of scheduled resources.

[0005] In one embodiment, a WTRU is described herein that includes a processor and a transmitter and a receiver (e.g., a transceiver) operatively coupled to the processor. The WTRU may be configured to receive scheduling information for one or more sidelink transmissions from a network. The scheduling information may indicate a set of scheduled resources. The WTRU may be configured to perform LBT in the set of scheduled resources for acquiring a subset of resources in the set of scheduled resources. The WTRU may be configured to transmit sidelink control information indicating the acquired subset of resources. The WTRU may be configured to transmit data in the acquired subset of resources. The WTRU may be configured to transmit feedback information related to the one or more sidelink transmissions to the network based on (e.g., a ratio between) the number of acquired resources and the number of scheduled resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] A more detailed understanding can be obtained from the following detailed description given as an example in conjunction with the accompanying drawings. Like the detailed description, the figures in such drawings are exemplary. Thus, the figures and detailed description should not be considered limiting, and other equally effective examples are possible and desirable. In addition, like reference numerals ("reference") in the various figures ("Figures") indicate similar elements, and wherein: Figure 1A is a system diagram illustrating an example communication system; Figure 1B This diagram shows the Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within a communication system illustrated in; Figure 1C This diagram shows the Figure 1A A system diagram of an example radio access network (RAN) and an example core network (CN) used within a communication system illustrated in FIG. Figure 1D This diagram shows the Figure 1A A system diagram of a further example RAN and a further example CN used within the communication system illustrated in FIG. Figure 2 is a diagram illustrating an example resource pool for an SLU; Figure 3 is a diagram illustrating several LBTs or transmission schemes for an SLU for one transport block (TB); Figure 4 is a diagram illustrating several LBTs or transmission schemes for an SLU for multiple TBs; Figure 5 is a resource diagram illustrating selection of resources for an LBT or transmission scheme; Figure 6is a resource diagram illustrating selection of resources for performing contiguous LBT; Figure 7 is a resource diagram illustrating selection of resources for performing LBT using puncturing / rate matching of a channel occupancy time (COT) of another WTRU; Figure 8 is a resource diagram illustrating a WTRU stopping transmission in a time slot before a reserved COT of another WTRU to help the other WTRU acquire a channel; Fig. 9 is a resource diagram illustrating a WTRU deferring transmission to a future time slot based on LBT success; Fig.10 is a diagram illustrating selection of a set of time slots available for LBT and transmission; Fig.11 is a diagram illustrating the determination of whether reserved resources are available or unavailable for LBT and transmission; Fig.12 is a diagram illustrating WTRU procedures after failing to perform LBT and transmit in a time slot; Fig.13 is a diagram illustrating determination of available time slots for broadband transmission; Fig.14 is a diagram illustrating determination of a channel access priority class (CAPC) to be used based on a maximum (eg, pre-)configured amount of data for access channels; Fig.15 is a resource diagram illustrating different transmission schemes and guard band usage for wideband operation; Fig.16 is a diagram illustrating an example method for reselecting an LBT subband for wideband sidelink transmission in an unlicensed spectrum; Fig.17 is a diagram illustrating an example method for broadband sidelink transmission in an unlicensed spectrum; Fig.18 is a diagram illustrating an example method for selecting resources for performing LBT for broadband sidelink transmission in an unlicensed spectrum; Fig.19 is a diagram illustrating an example method for reporting feedback information related to SL transmission to a network; Fig. 20 is a diagram illustrating an example method for determining whether to maintain a current LBT subband or select another LBT subband; Fig.21 is a diagram illustrating an example method for determining a primary LBT subband; Fig. 22 is a diagram illustrating an example method for selecting a time slot in a resource selection window; and Fig.23 is a diagram illustrating an example method for transmission in a first start symbol of a slot having multiple start symbols. DETAILED DESCRIPTION

[0007] In the following detailed description, many specific details are set forth to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples can be practiced without some or all of the specific details set forth herein. In other examples, well-known methods, processes, components, and circuits have not yet been described in detail to avoid blurring the following description. Further, embodiments and examples not specifically described herein can be practiced in place of or in conjunction with embodiments and other examples described herein, disclosed, or otherwise explicitly, implicitly, and / or inherently provided (collectively referred to as "provided").

[0008] Although various embodiments are described and / or claimed herein in which devices, systems, equipment, etc. and / or any elements thereof implement operations, processes, algorithms, functions, etc. and / or any portions thereof, it should be understood that any embodiments described and / or claimed herein specify that any device, system, equipment, etc. and / or any elements thereof are configured to implement any operation, process, algorithm, function, etc. and / or any portion thereof.

[0009] Example Communication System The methods, devices, and systems provided herein are well suited for communications involving both wired and wireless networks. Wired networks are well known. Figures 1A-1D To provide an overview of various types of wireless devices and infrastructure, wherein various elements of the network can utilize the methods, apparatuses, and systems provided herein, perform the methods, apparatuses, and systems provided herein, are arranged according to the methods, apparatuses, and systems provided herein, and / or are adapted and / or configured for the methods, apparatuses, and systems provided herein.

[0010] 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 by sharing 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 DFT spread OFDM (ZT UW DTS-sOFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0011] like Figure 1A As shown in FIG, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, although it will be appreciated 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” and / or “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 context), 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.

[0012] 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 that is 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 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node-B, an eNode B, a home Node B, a home eNode B, a gNB, an NR NodeB, a site controller, an access point (AP), a wireless router, and the like. Although 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.

[0013] The base station 114a may be part of the RAN 104 / 113, 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 a licensed spectrum and an unlicensed spectrum. A cell may provide coverage for a specific geographic area for a wireless service, which may be relatively fixed or may change over time. A 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 one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology, and multiple transceivers may be used for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0014] 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, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0015] 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 / 113, and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which 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 Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0016] In one 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), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0017] In an 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 New Radio (NR).

[0018] 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).

[0019] 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 (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0020] Figure 1A The base station 114b in the example may be, for example, a wireless router, a home Node B, a home eNode B, 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 one 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 picocell or a femtocell. Figure 1A As shown in FIG, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not be required to access Internet 110 via CN 106 / 115.

[0021] The RAN 104 / 113 may communicate with the CN 106 / 115, 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 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, etc. and / or perform advanced security functions, such as user authentication. Although Figure 1ANot shown, but it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0022] The CN 106 / 115 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 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 / 113 or a different RAT.

[0023] 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 WTRU 102c shown in FIG. 1 may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and the base station 114b, which may employ an IEEE 802 radio technology.

[0024] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown in FIG, 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 above elements while remaining consistent with an embodiment.

[0025] 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) circuit, 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 will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0026] The transmit / receive element 122 may be configured to transmit a signal to a base station (e.g., base station 114a) or receive a signal from the base station via the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and optical signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0027] Although the transmit / receive element 122 is 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.

[0028] 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. Thus, for example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0029] The processor 118 of the WTRU 102 may be coupled to 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), and may receive user input data therefrom. 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, or the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0030] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to 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.

[0031] 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. 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 in addition to or in lieu of the information from the GPS chipset 136. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0032] The processor 118 may be further coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the components 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, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. Peripheral 138 may include one or more sensors, which may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0033] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both uplink (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate 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 transmission and reception of some or all signals (e.g., associated with specific subframes for both uplink (e.g., for transmission) or ...

[0034] 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.

[0035] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-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 eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0036] Each of the eNode-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 the uplink (UL) and / or downlink (DL), etc. Figure 1C As shown in FIG. , the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0037] Figure 1C The CN 106 shown in FIG. 1 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by entities other than the CN operator.

[0038] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, and 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.

[0039] The SGW 164 may be connected to each of the eNode 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-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the contexts of the WTRUs 102a, 102b, 102c, and the like.

[0040] 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.

[0041] 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 and / or wireless networks owned and / or operated by other service providers.

[0042] Although the WTRU Figures 1A to 1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use (eg, temporarily or permanently) a wired communications interface with a communications network.

[0043] In a representative embodiment, other network 112 may be a WLAN.

[0044] 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 into the BSS and / or carries traffic out of the BSS. Traffic originating from outside the BSS to a STA may arrive through the AP and may be delivered to the STA. Traffic from a STA to a destination outside the BSS may be sent to the AP so as to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent through 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 peer traffic. Peer traffic may be sent between the source and destination STAs (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 (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0045] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, the AP may transmit beacons 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 width dynamically set via signaling. 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 with 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.

[0046] A high throughput (HT) STA may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel.

[0047] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz 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 (which can be referred to as 80+80 configurations). For the 80+80 configuration, after channel coding, the data can be passed through a segment parser, which can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be done separately on each stream. The stream can be mapped to two 80MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0048] The operation mode below 1 GHz is supported by 802.11af and 802.11ah. The channel operation bandwidth and carrier are reduced in 802.11af and 802.11ah relative to the channel operation bandwidth and carrier used in 802.11n and 802.11ac. 802.11af supports 5MHz bandwidth, 10MHz bandwidth and 20MHz bandwidth in the TV white space (TVWS) spectrum, and 802.11ah supports 1MHz bandwidth, 2MHz bandwidth, 4MHz bandwidth, 8MHz bandwidth and 16MHz bandwidth using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support instrument type control / machine type communication, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, for example, limited capabilities, including support for (e.g., only support for) certain and / or limited bandwidths. MTC devices may include batteries whose battery life is above a threshold (e.g., to maintain a very long battery life).

[0049] A WLAN system that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) includes a channel that can be designated as a primary channel. 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 the STA that supports the minimum bandwidth operating mode among 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 (which only supports a 1MHz operating mode) transmitting to the AP, the entire available band may be considered busy, even if most of the band is still idle and may be available.

[0050] In the United States, the available frequency band that 802.11ah can use is from 902MHz to 928MHz. In South Korea, the available frequency band is from 917.5MHz to 923.5MHz. In Japan, the available frequency band is from 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah is 6MHz to 26MHz.

[0051] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0052] The RAN 113 may include gNBs 180a, 180b, 180c, although it will be appreciated that the RAN 113 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, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and gNB 180b (and / or gNB 180c).

[0053] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. 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 various or scalable lengths (e.g., containing different numbers of OFDM symbols and / or lasting different lengths of absolute time) .

[0054] 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 without also accessing other RANs (e.g., such as, for example, the eNode-Bs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchors. 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 WTRUs 102a, 102b, 102c may communicate / connect to the gNBs 180a, 180b, 180c while also communicating / connecting to another RAN, such as the eNode-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput to serve the WTRUs 102a, 102b, 102c.

[0055] 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 uplink (UL) and / or (DL), support of network slicing, dual connectivity, interworking between 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. As shown in FIG. Figure 1D As shown in , gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0056] Figure 1DThe CN 115 shown in FIG. 1 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possibly a data network (DN) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by entities other than the CN operator.

[0057] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 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, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, terminating non-access stratum (NAS) signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRU 102a, 102b, 102c based on the type of service 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 machine type communication (MTC) access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 113 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 WiFi.

[0058] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure 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 enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0059] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 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 184a, 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 downlink packets, providing mobility anchoring, etc.

[0060] The CN 115 may facilitate communications with other networks. For example, the CN 115 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 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local data network (DN) 185a, 185b through the UPF 184a, 184b via an N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0061] Given that Figures 1A to 1D as well as Figures 1A to 1D , one or more or all of the functions described herein with respect to one or more of the following items may be performed by one or more simulation devices (not shown) to perform one or more or all of the functions described herein with respect to one or more of the following items: WTRU102a-d, base station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any other device(s) described herein. The simulation device may be one or more devices configured to simulate 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.

[0062] The simulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, the one or more simulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. The one or more simulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing purposes and / or can use over-the-air wireless communications to perform testing.

[0063] The one or more simulation devices can perform one or more (including all) functions without being implemented / deployed as a 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 in a non-deployed (e.g., test) wired and / or wireless communication network to achieve the test of one or more components. The one or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication carried out via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to transmit and / or receive data.

[0064] Throughout the embodiments described herein, the terms "serving base station", "base station", "gNB", "network", collectively referred to as "network", may be used interchangeably to indicate any network element, such as, for example, a network element acting as a serving base station. The embodiments described herein are not limited to gNBs, but are applicable to any other type of serving base station.

[0065] For clarity, throughout the embodiments described herein, satisfying, failing to satisfy a condition, and configuring (one or more) condition parameters are described as being relative to a threshold (e.g., greater than or less than) a (e.g., threshold) value, configuring a (e.g., threshold) value, etc. For example, satisfying a condition may be described as being above a (e.g., threshold) value, and failing to satisfy a condition (e.g., performance criterion) may be described as being below a (e.g., threshold) value. The embodiments described herein are not limited to threshold-based conditions. Any variety of (one or more) other conditions and parameters (such as, for example, belonging to or not belonging to a range of values) may be applicable to the embodiments described herein.

[0066] Throughout the embodiments described herein, (e.g., configuration) information may be described as being received by the WTRU from the network, such as through system information or via any kind of protocol message. Although not explicitly mentioned throughout the embodiments described herein, the same (e.g., configuration) information may be pre-configured in the WTRU (e.g., via any kind of pre-configuration method, such as, for example, via factory settings) so that the (e.g., configuration) information can be used by the WTRU without being received from the network.

[0067] Throughout the embodiments described herein, the expression “the WTRU may be configured with a parameter set” is equivalent to, or may be used interchangeably with, “the WTRU may receive configuration information indicating a parameter set (e.g., from another network element (e.g., gNB))”. Throughout the embodiments described herein, the expression “the WTRU may report something” and “the WTRU may be configured to report something” is equivalent to, or may be used interchangeably with, “the WTRU may transmit (e.g., report) information indicating something”.

[0068] In the embodiments described herein, the term Uu is used to refer to any of the data, transmission, interface, characteristics, etc. associated with the (uplink / downlink) link to the base station.

[0069] Operation in unlicensed spectrum This article describes operation in the unlicensed spectrum.

[0070] SL Operation in Unlicensed Spectrum It was agreed at the 3rd Generation Partnership Project (3GPP) RAN#94 meeting that the R18 Sidelink (SL) Evolution Work Item (WI) includes research on support for sidelink operation for both Mode 1 and Mode 2 in unlicensed spectrum in Frequency Range 1 (FR1) (Sidelink Unlicensed). The unlicensed SL bands are 5 GHz and 6 GHz, and Uu operations associated with Mode 1 are limited to licensed spectrum. The sidelink unlicensed (SL U) channel access design can be based on regional regulatory requirements for existing 5G New Radio Unlicensed (NR U) channel access as a starting point.

[0071] The R16 SL resource allocation mechanism specified for licensed spectrum can be reused. The scope of R18 SL U also covers changes to the NR SL physical (PHY) channel structure and procedures for operating in unlicensed spectrum. For example, hybrid automatic repeat request (HARQ) feedback supported in new radio vehicle to everything (NR V2X) for unicast and multicast transmissions will be evaluated in the R18 WI discussion.

[0072] Unlicensed requirements for a single LBT sub-band In an unlicensed band, a channel access procedure prior to transmission may allow for fair sharing of unlicensed spectrum between different radio access technologies. Channel access may use a listen-before-talk (LBT) procedure. The listen-before-talk (LBT) procedure may be referred to as a mechanism by which a device may apply a clear channel assessment (CCA) check before using a channel. CCA may utilize at least energy detection to determine the presence or absence of other signals on a channel to determine whether a channel is occupied or clear, respectively. For some LBT types (e.g., type 2 LBT), a fixed sensing duration of 16 or 25 μs may be used to clear the channel. For other LBT types (e.g., type 1 LBT), a random number of sensing slots (e.g., each sensing slot spans 9 μs) of cleared idle slots may be used to clear the channel, which random number may be referred to as N. For example, if the channel is idle for a duration required for each sensing type (e.g., associated with each sensing type), the WTRU may perform a transmission.

[0073] There may be four channel access types (which may be referred to herein as LBT types) defined by regulations, such as, for example, type 1 channel access, type 2A channel access, type 2B channel access, and type 2C channel access.

[0074] In type 1 channel access, the transmitter may transmit after sensing the channel as idle during N sensing time slots, where N may be a (e.g., randomly selected) number. Whenever the channel is sensed as busy in one of the N time slots, sensing may be performed during an additional deferral duration.

[0075] In Type 2A channel access, a transmitter may transmit a transmission after (eg, immediately) sensing the channel as idle for at least 25 microseconds.

[0076] In Type 2B channel access, a transmitter may transmit a transmission after (eg, immediately) sensing the channel as idle for at least 16 microseconds.

[0077] In Type 2C channel access, the transmitter may not sense the channel before transmitting.

[0078] After the transmitter may have acquired the channel, the transmitter may occupy the channel (e.g., perform transmissions in the channel) during a channel occupation time (COT). The COT may have an upper bound (e.g., maximum) duration depending on which LBT type may be used to acquire the channel. A transmitter may initiate a COT and may share it with another transmitter under some restrictions (e.g., conditions), e.g., LBT type 1 may be used to initially acquire the channel, and the gap between different transmissions may be smaller than the (e.g., specified) gap.

[0079] Broadband operation in Unlicensed Uu: In unlicensed spectrum, an example of a bandwidth for one LBT subband may be 20 MHz. Wideband operation in unlicensed spectrum may be used to refer to the operation of a network element with a bandwidth greater than 20 MHz (e.g., multiple LBT subbands). Wideband operation may enable the WTRU to obtain greater bandwidth and achieve higher throughput.

[0080] R 16NR Uu supports two types of gNB channel access for wideband operation, which may be referred to as type A and type B wideband channel access. In type A, the gNB may maintain an individual LBT process for each LBT subband and may perform transmission in each LBT subband if LBT is successful. Type A may be divided into two subtypes, which may be referred to as type A1 and type A2. In type A1, a backoff counter N may be initiated per LBT subband. In type A2, a single backoff counter N may be used for all LBT subbands. In type B, the gNB may select one LBT subband (e.g., cj) for type 1 LBT and the remaining LBT subbands (e.g., sensing T before Tx in LBT subband cj) for type 2 LBT (e.g., 2B). mc =25μs). The gNB may transmit in LBT subband cj and in any subband ci for which Type 2 LBT may have succeeded (e.g., the channel was found to be clear). Type B may be divided into Type B1 and B2. In Type B1, a single contention window (CW) may be maintained for all LBT subbands. p ), and in type B2, an individual contention window (CW) may be maintained for each LBT subband p ).

[0081] For UL operation, the WTRU may be scheduled using the wideband Physical Uplink Idle Channel (PUSCH) and may perform a PUSCH transmission if LBT succeeds in all scheduled LBT subbands. This restriction may allow the network to avoid blind detection of transmissions from the WTRU due to unpredictable LBT results.

[0082] To mitigate intra-carrier interference between transmissions in different LBT subbands between Wi-Fi and NR U, a guard band between two adjacent LBT subbands may be introduced, which may be semi-statically configured or predefined (e.g., in 3GPP TS 38.101). If zero guard band is configured, the gNB cannot perform transmissions if it fails to acquire any LBT subband in the carrier. If the WTRU acquires two adjacent LBT subbands, the guard band between the two LBT subbands may be used.

[0083] Mode 1 Scheduling: For Mode 1 dynamic scheduling, the network may schedule the WTRU for a sidelink grant for the transmission of one TB. The network may indicate the UL resources to be used to feedback the usage status of the grant (e.g., transmit information indicating it). For example, if the WTRU uses the grant to transmit a HARQ-enabled TB, the WTRU may report ACK and / or NACK based on the positive acknowledgement (ACK) / negative acknowledgement (NACK) feedback or discontinuous transmission (DTX) from the Rx WTRU. If the WTRU uses the grant to transmit a HARQ-disabled TB, the WTRU may report NACK if more resources are expected to transmit the TB. Otherwise, the WTRU may report ACK.

[0084] In sidelink resource allocation, there may be two scheduling modes, which may be referred to herein as WTRU autonomous resource allocation (e.g., Mode 2) and network scheduling (e.g., Mode 1). For wideband operation in the sidelink unlicensed spectrum, the WTRU may be (e.g., pre-)configured with multiple LBT subbands. Mechanisms for performing LBT subband selection and resource allocation are described herein.

[0085] In NR U, the gNB is the receiver for the UL resources scheduled by the network. The gNB may be aware of the UL transmission status. In the sidelink, the network may not be aware of the SL transmissions in the sidelink resources it schedules. This document describes a mechanism for coordination between the gNB and the WTRU regarding sidelink scheduling to cope with the unpredictability of the LBT process.

[0086] If a WTRU acquires two adjacent LBT subbands, it may be beneficial for the system and the WTRU to use a guard band between the two LBT subbands. The Rx WTRU may not be aware of this decision. Mechanisms to coordinate and optimize guard band usage are described herein.

[0087] Two metrics may be used to characterize the channel state, thereby allowing the WTRU to take action: the channel busy ratio (CBR) and the channel occupancy ratio (CR). The channel busy ratio (CBR) may be considered as the fraction of subchannels in the resource pool for which the measured received signal strength may exceed a (e.g., pre-)configured threshold. This metric may be sensed, for example, over the last hundred subframes / timeslots. The CBR may provide an estimate of the overall state of the channel. The channel occupancy ratio (CR), which may be determined at a subframe / timeslot (e.g., n), may be considered as the total number of subchannels used for its transmission in the previous subframe / timeslot (e.g., [na,n-1]) and authorized in the upcoming subframe / timeslot (e.g., [n,n+b]) divided by the total number of subchannels (e.g., within [na,n+b]), where a, b, and n may be integers determined by the WTRU. The CR may provide an indication of the channel utilization by the transmitter itself.

[0088] Method and apparatus for broadband operation in SL U In the embodiments described herein, the term “LBT subband” may be used interchangeably with “a set of LBT subbands,” “resource pool,” “sidelink carrier,” “bandwidth part (BWP),” “subband,” and “resource block (RB) set.”

[0089] In the embodiments described herein, the term "reserved resources" may be used to describe resources reserved for LBT and / or transmission. The term "resources" may be used interchangeably with the term "COT".

[0090] In the embodiments described herein, resources may be used to describe a collection of smaller resources, where each smaller resource may be used for one transmission.

[0091] In the embodiments described herein, the action of "puncturing / rematching a transmission" may be used interchangeably with the action of "determining the duration of a transmission."

[0092] In the embodiments described herein, received signal strength indicator (RSSI), reference signal received power (RSRP), and reference signal received quality (RSRQ) may be used interchangeably to refer to a quality metric representing signal quality.

[0093] In the embodiments described herein, “physical sidelink control channel (PSCCH) / physical sidelink shared channel (PSSCH) transmission” may be used interchangeably with “SL transmission”.

[0094] In the embodiments described herein, "number" and "percentage" of (e.g., acquired) resources over a set of (e.g., scheduled) resources, collectively referred to as "number / percentage," may be used interchangeably to refer to a subset of (e.g., acquired) resources within a set of (e.g., scheduled) resources, such as, for example, a ratio of (e.g., acquired) resources over (e.g., scheduled) resources.

[0095] METHOD FOR WTRU AUTONOMOUS RESOURCE ALLOCATION LBT parameters In some embodiments, the WTRU may perform LBT prior to transmission. The WTRU may determine one or any combination of the following LBT parameters: LBT type for multi-channel access (e.g., LBT type A, A1, A2, B, B1, B2); LBT type for one LBT subband channel access (e.g., LBT type 1, 2, 2A, 2B, 2C); LBT category in one LBT sub-band (e.g., LBT CAT 1, 2, 4); Channel Access Priority Class (CAPC); Contention window size, which may include the current contention window (CW p ), a lower bound (e.g., minimum) and / or an upper bound (e.g., maximum) on the contention window (e.g., CW p , CW min,p and CW max,p ); Either the current value or the initial value of the rollback counter (N); COT duration, which may include current COT and / or maximum COT; Delay period (T d ); LBT energy detection threshold used to determine channel availability; Fixed frame period (FFP) configuration; and • Clear Channel Access (CCA) duration.

[0096] Herein, LBT parameters may include one or any combination of parameters related to the channel access process. The parameters may include, but are not limited to, LBT type for multi-channel access, LBT type for one LBT subband channel access, LBT category in one LBT subband, CAPC, contention window size (which may include CW p , CW min,p and CW max,p), current or initialized back-off counter N, COT duration, postponement period, LBT energy detection, FFP configuration and CCA duration.

[0097] WTRU determines LBT parameters for access channel In some embodiments, the WTRU may determine one or any combination of LBT parameters based on one or any combination of the following two examples.

[0098] In a first example, the WTRU may determine any of the LBT parameters based on any of the QoS of the TB, sidelink radio bearer (SLRB), and logical channel (LCH). Herein, the QoS of the TB, SLRB, and / or LCH may include one or more of the following: priority, latency, reliability, range requirements, data rate, remaining packet delay budget (PDB), type of data traffic (e.g., whether the data is periodic or non-periodic), periodicity of the traffic, type of HARQ feedback (e.g., whether the TB, SLRB, and / or LCH is HARQ enabled, disabled, or a mixture of HARQ enabled and disabled), cast type of the TB (e.g., whether the TB, SLRB, and / or LCH is associated with unicast, multicast, and / or broadcast), size of the TB, remaining PDB (e.g., for retransmission of the TB), and one or more LBT parameters for accessing a channel to transmit the TB.

[0099] In a second example, the WTRU may determine any of the LBT parameters based on the TB size, the WTRU's buffer status, and any of the channel busy ratios (CBRs) of the resource pools and / or LBT subbands.

[0100] WTRU determines resource size for performing LBT and / or resource allocation In one embodiment, the WTRU may determine the resource size for performing LBT and / or transmission. The resource size may include the bandwidth or minimum bandwidth and / or duration or minimum duration of each resource for performing LBT and / or transmission. In one scheme, the WTRU may perform LBT and / or transmission for resources having at least M consecutive subchannels spanning at least N time slots, where M and N are integers. In another scheme, the WTRU may perform LBT and / or transmission for resources having at least M consecutive LBT subbands spanning at least N time slots. This scheme may be motivated to optimize the number of attempts to access the channel.

[0101] exist Figure 2In one example shown in , the WTRU may be (e.g., pre-)configured to perform transmissions in a resource pool having three LBT subbands. The WTRU may determine to perform LBT and / or transmissions in resources having a size of at least two contiguous LBT subbands spanning at least two time slots. The WTRU may then select resources in a rectangle as shown at 201, 203, 205, which may include resources for performing LBT and / or transmissions. The resources in the rectangle shown at 201, 203, 205 satisfy the resource size requirement of at least (e.g., at least) two LBT subbands spanning at least (e.g., at least) two time slots.

[0102] The WTRU may determine the resource size for performing LBT and / or transmission based on one or any combination of the following six examples (e.g., which may include any one of a minimum of M LBT subbands spanning at least N time slots).

[0103] In a first example, the WTRU may determine the resource size based on a (e.g., pre-) configuration in a resource pool. For example, the WTRU may be (e.g., pre-) configured with M and / or N values ​​for performing LBT and / or transmission. The WTRU may then select M and / or N values ​​based on the (pre-) configuration.

[0104] In a second example, the WTRU may determine the resource size based on the size of the TB. For example, the WTRU may be (e.g., pre-)configured with a range of resource sizes (e.g., a minimum of M LBT subbands spanning a minimum of N time slots) for performing LBT and / or transmissions based on the TB size. The WTRU may (e.g., then) determine the M and / or N values ​​for performing LBT and / or transmissions based on the TB size.

[0105] In a third example, the WTRU may determine the resource size based on the CBR of the resource pool and / or LBT subband. For example, the WTRU may be (e.g., pre-)configured with a range of resource sizes for performing LBT and / or transmission based on the CBR of the resource pool and / or LBT subband. The WTRU may (e.g., then) determine which resource size to select to perform LBT and / or transmission based on the measured CBR of the resource pool and / or LBT subband. For example, if the CBR of the resource pool and / or LBT subband is greater than a threshold, the WTRU may use a smaller resource size. If the CBR of the resource pool and / or LBT subband is less than a threshold, the WTRU may use a larger resource size.

[0106] In a fourth example, the WTRU may determine the resource size based on any of the QoS of the TB, SLRB, and LCH. For example, the WTRU may be (e.g., pre-)configured with a range of resource sizes for performing LBT and / or transmission based on the QoS of the TB (e.g., the priority of the TB). The WTRU may then determine which resource size to use to perform LBT and / or transmission based on the QoS associated with the TB.

[0107] In a fifth example, the WTRU may determine the resource size based on one or more LBT parameters for accessing a channel. In one example, the WTRU may determine the resource size for performing LBT and / or transmission based on the LBT type for multi-channel access. For example, the WTRU may be (e.g., pre-) configured with a range of resource sizes of a minimum of M LBT subbands across N time slots for each LBT type for multi-channel access. For example, the WTRU may be (e.g., pre-) configured with a resource size of one LBT subband across one time slot for LBT type A. Alternatively, the WTRU may be (e.g., pre-) configured with a resource size of two LBT subbands across two time slots for LBT type B. In another example, the WTRU may determine the resource size to be used to perform LBT and / or transmission based on the CAPC of the TB. For example, the WTRU may be (e.g., pre-) configured with a range of resource sizes for performing LBT and / or transmission based on the CAPC of the TB. The WTRU may then determine which resource size to use to perform LBT and / or transmission based on the CAPC of the TB and the (e.g., pre-)configured resource size range. For example, the WTRU may select a small resource size for a high CAPC priority (i.e., a low CAPC value) and may select a large resource size for a low CAPC priority (e.g., a high CAPC value). This scheme may allow low CPAC data to access more resources based on a longer LBT time. In yet another example, the WTRU may select a smaller resource size based on the current contention window (CW p ) and / or backoff value N to determine the resource size to use to perform LBT and / or transmission. The WTRU may be (e.g., pre-)configured with a range of resource sizes for each contention window and / or backoff value. The WTRU may then determine the resource size to use to perform LBT and / or transmission based on the contention window (CW p ) and / or fallback value N to determine which resource size to use for LBT and / or transmission.

[0108] In a sixth example, the WTRU may determine a resource size based on the WTRU's buffer status (e.g., the amount of data in the buffer and / or the amount of data in the (e.g., pre-)configured set of logical channels (LCHs). In one example, for each range of the total amount of data in the buffer, the WTRU may be (e.g., pre-)configured with a maximum / minimum of M LBT subbands and / or a maximum / minimum of N time slots for LBT. The WTRU may then determine which value of M and / or N to use based on the amount of data in the buffer. For example, if the WTRU has a total data in the buffer that is less than a first (e.g., pre-)configured threshold, the WTRU may use a resource size of one RB set and one time slot. For example, if the total amount of data is greater than a first threshold and less than a second threshold, the WTRU may use a resource size of two RB sets and one time slot or one RB set and two time slots. For example, if the total amount of data is greater than a third threshold, the WTRU may use a resource size of two RB sets and two time slots or three RB sets and one time slot. In yet another example, the WTRU may determine the resource size (eg, the maximum value of M and / or N) based on the amount of data having a priority greater than a (eg, pre-)configured threshold.

[0109] WTRU performs LBT and / or transmission scheme in one TB wideband operation In some embodiments, the WTRU may perform one or any combination of the following LBT and / or transmission schemes in broadband operation for one TB.

[0110] In the first scheme, the WTRU may first select an LBT subband. The WTRU may perform transmissions of LBT and / or TB in the selected LBT subband. The WTRU may perform (e.g., all) transmissions (e.g., initial transmission and (one or more) retransmissions) of a TB in the same LBT subband.

[0111] In a second approach, the WTRU may perform transmissions of LBT and / or TB in multiple LBT subbands. For example, the WTRU may select an LBT subband to perform LBT and / or transmission for (e.g., each) transmission of a TB. The WTRU may select resources for LBT and / or transmission such that two resources in two LBT subbands may not overlap.

[0112] In a third scheme, the WTRU may perform one LBT type (e.g., any of type A, B, A1, A2, B1, B2) to access multiple LBT subbands. When LBT is successful, the WTRU may perform transmissions in (e.g., each) subband. If the WTRU acquires multiple LBT subbands in a timeslot, the WTRU may perform multiple transmissions of a TB in the same timeslot (e.g., one initial transmission and one or more retransmissions), where each transmission may be associated with one LBT subband. The WTRU may indicate (e.g., in the sidelink control information (SCI)) that the WTRU may perform multiple transmissions of a TB in the same timeslot. The WTRU may indicate information related to transmissions in the same timeslot, which may implicitly or explicitly include a set of LBT subbands. This scheme may allow the Rx WTRU to be assisted in TB decoding.

[0113] In a fourth scheme, the WTRU may perform an LBT type (e.g., any of Type A, B, A1, A2, B1, B2) to access multiple LBT subbands. If the WTRU acquires multiple LBT subbands in a timeslot, the WTRU may perform a transmission of a TB across the acquired LBT subbands. The WTRU may acquire adjacent LBT subbands to perform such a transmission. If the WTRU acquires non-adjacent LBT subbands, the WTRU may perform a transmission in a subset of the acquired LBT subbands, which may be adjacent subbands. The WTRU may indicate (e.g., in an SCI) a set of subbands for transmission of TBs. The WTRU may transmit an SCI in one of the LBT subbands (e.g., the lowest / highest indexed LBT subband).

[0114] exist Figure 3 In one example shown in , the WTRU may implement one of the four LBT and / or transmission schemes discussed above for one TB. For example, the WTRU may be configured with two LBT subbands (e.g., LBT subbands 1 and 2) to perform wideband operation. Figure 3 In the first LBT and / or transmission scheme shown at 31 in FIG. 1 , the WTRU may first select an LBT subband (e.g., LBT subband 1) to perform LBT and / or transmission. The WTRU may then select resources for performing LBT and potential transmission.

[0115] exist Figure 3 In the second LBT and / or transmission scheme shown at 32 in FIG. 1 , the WTRU may select each resource for LBT and / or transmission. The WTRU may then perform two first transmissions in the first LBT subband. The WTRU may then perform the last transmission of the TB in the second LBT subband.

[0116] exist Figure 3In the third LBT and / or transmission scheme shown at 33 in FIG. 1 , the WTRU may perform LBT and acquire two LBT subbands, for example simultaneously. The WTRU may then perform a transmission of one TB in the two LBT subbands across two time slots. In each time slot, the WTRU may perform two transmissions, each of which may be within one LBT subband.

[0117] Different from the third scheme, in the fourth scheme shown at 34, in each time slot, the WTRU may perform one transmission of a TB across two LBT subbands. Guard bands may be used in the third and fourth schemes shown at 33 and 34.

[0118] WTRU performs LBT and / or transmission schemes in wideband operation with multiple TBs The WTRU may perform one or any combination of the following LBT and / or transmission schemes in wideband operation for multiple TBs: In a first scheme (e.g., which may be referred to as Scheme A), the WTRU may perform one LBT type (e.g., Type A, B, A1, A2, B1, B2) to access multiple LBT subbands. The WTRU may perform a transmission of each TB in the acquired set of LBT subbands. The WTRU may perform one or more transmissions of a TB, where (e.g., each) transmission of the TB may be within an LBT subband. The WTRU may perform one transmission of a TB (e.g., an initial transmission) in one LBT subband and one or more other transmissions of the TB (e.g., retransmissions) in other LBT subbands. Each transmission of a TB may occupy one time slot. The WTRU may perform a transmission of a TB in one or more time slots.

[0119] In a second scheme (e.g., which may be referred to as Scheme B), the WTRU may perform one LBT type (e.g., Type A, B, A1, A2, B1, B2) to access multiple LBT subbands. The WTRU may perform transmissions of (e.g., each) TB in a set of acquired LBT subbands. The WTRU may perform one or more transmissions of a TB in multiple LBT subbands, where each transmission may span multiple LBT subbands (e.g., span multiple (e.g., all) acquired LBT subbands).

[0120] In a third scheme (e.g., which may be referred to as Scheme C), the WTRU may combine the first and second schemes, wherein the WTRU may use the first scheme for one set of TBs (e.g., the first one or more TBs transmitted in the COT) and may use the second scheme for another set of TBs (e.g., the last one or more TBs transmitted in the COT).

[0121] In a fourth scheme (e.g., which may be referred to as scheme D), the WTRU may select an LBT subband to perform LBT and / or transmission for each TB. The WTRU may use the same or different LBT subbands for multiple TBs. The WTRU may perform one LBT type (e.g., type A, B, A1, A2, B1, B2) to access multiple LBT subbands. If LBT is successful in one LBT subband, the WTRU may perform transmission of the associated TB in the LBT subband.

[0122] exist Figure 4 In one example shown in , the WTRU may implement one of four LBT and / or transmission schemes for multiple TBs. Figure 4 In the first LBT and / or transmission scheme shown at 41 in FIG. 4, in the same time slot, the WTRU may perform LBT and may acquire two LBT subbands. The WTRU may perform multiple transmissions of a TB in one time slot, where each transmission may be within one LBT subband. Figure 4 As shown in , the WTRU may perform transmissions of two TBs, where the transmission of the first TB is in the diagonally shaded rectangle as shown at 401 and the transmission of the second TB is in the horizontally shaded rectangle as shown at 402. The WTRU may perform four transmissions per TB across two time slots. In each time slot, the WTRU may perform two transmissions per TB, where each transmission may be within one LBT subband.

[0123] exist Figure 4 In the second LBT and / or transmission scheme shown at 42 in FIG. 4 , the WTRU may perform one transmission of one TB in each timeslot, which may span multiple acquired LBT subbands.

[0124] exist Figure 4 In the third LBT and / or transmission scheme shown at 43, the WTRU may use the first scheme for the first TB and the second scheme for the second TB.

[0125] exist Figure 4 In a fourth scheme shown at 44 in FIG. 4 , the WTRU may select first and second LBT subbands for first and second TBs, respectively. The WTRU may then independently perform LBT and / or transmission for each TB in each LBT subband.

[0126] The WTRU indicates its LBT and / or transmission scheme to another network element The WTRU may indicate (e.g., transmit information indicating its LBT and / or transmission scheme) to other network elements (e.g., one or more receiver WTRUs). The WTRU may use one or any combination of NAS, PCT radio resource control (RRC), MAC control element (MAC CE), and / or SCI to indicate its LBT and / or transmission scheme. In one example, the WTRU may use one or more SCIs (e.g., second stage SCIs) associated with one or more transmissions of a TB to indicate whether the TB spans multiple subbands or is within one LBT subband. The WTRU may use the SCI to indicate whether it performs multiple transmissions of a TB in a timeslot. The WTRU may (e.g., also) use the SCI to indicate a set of LBT subbands for performing simultaneous transmissions of a TB in the same timeslot.

[0127] The WTRU determines which LBT and / or transmission scheme to use for wideband operation In some embodiments, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on one or any combination of the following ten examples.

[0128] In a first example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on (e.g., pre-) configuration in a resource pool. For example, the WTRU may be configured with resource pool information indicating whether to perform transmission of TBs in one or more LBT subbands. For example, the WTRU may be (e.g., pre-) configured with one or more LBT types (e.g., any one of types A, B, A1, A2, B1, B2) for multi-channel access. The WTRU may then use one of the (e.g., pre-) configured LBT types to access multiple channels.

[0129] In a second example, the WTRU may determine which LBT and / or transmission scheme to use for broadband operation based on whether the guard band is (e.g., pre-) configured in the resource pool. In one example, for the transmission of one TB, the WTRU may determine the LBT scheme based on whether the guard band is (e.g., pre-) configured in the resource pool. For example, if the guard band is not (e.g., pre-) configured in the resource pool, the WTRU may determine that a type of LBT process for multi-channel access (e.g., any one of LBT types A2, B, B1, B2, where the LBT process in one LBT subband depends on the LBT process in another LBT subband) is to be performed. Otherwise, if the guard band is (e.g., pre-) configured in the resource pool, the WTRU may perform any type of LBT for multi-channel access (e.g., LBT type A1). In another example, the WTRU may determine the transmission scheme based on whether the guard band is (e.g., pre-) configured in the resource pool. For example, if the guard band is not (e.g., pre-) configured in the resource pool, the WTRU may perform one transmission of a TB across multiple LBT subbands. Otherwise, if the guard band is (e.g., pre-) configured in the resource pool, the WTRU may perform multiple transmissions of the TB in the same timeslot, where each transmission may be within one LBT subband.

[0130] In a third example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the acquired set of LBT subbands. For example, if the WTRU acquires a set of contiguous LBT subbands, the WTRU may select an LBT and / or transmission scheme (e.g., Figure 3 For example, if the WTRU acquires non-contiguous LBT subbands, the WTRU may use another LBT and / or transmission scheme (e.g., Figure 3 A third LBT and / or transmission scheme for one TB is shown in , where each transmission may span multiple LBT subbands).

[0131] In a fourth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the QoS associated with any of the TB, SLRB, and LCH. For example, if the reliability of the TB is greater than a threshold, the WTRU may select an LBT and / or transmission scheme (e.g., such as Figure 3 Otherwise, if the reliability of the TB is less than the threshold, the WTRU may select another LBT and / or transmission scheme (e.g., Figure 3 A second LBT and / or transmission scheme for one TB as shown in FIG.

[0132] In a fifth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the size of the TB. For example, if the size of the TB is less than a threshold, the WTRU may select an LBT and / or transmission scheme for one TB (e.g., Figure 3 ); otherwise, if the size of the TB is greater than the threshold, the WTRU may select another LBT and / or transmission scheme (e.g., Figure 3 , where the WTRU may perform simultaneous transmission of the TB in multiple LBT subbands). The TB size threshold may be (e.g., pre-) configured in the resource pool.

[0133] In a sixth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the WTRU's buffer status. For example, if the WTRU's buffer size is less than a threshold, the WTRU may select an LBT and / or transmission scheme (e.g., such as Figure 4 Otherwise, if the WTRU's buffer size is greater than the threshold, the WTRU may select another LBT and / or transmission scheme (e.g., Figure 4 LBT and / or transmission scheme C for multiple TBs shown in , where the WTRU may transmit one TB across multiple LBT subbands). The buffer size threshold may be (e.g., pre-)configured in the resource pool.

[0134] In a seventh example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on a data rate (e.g., requirement) associated with a service. For example, if the data rate (e.g., requirement) associated with a sidelink service is less than a threshold, the WTRU may select an LBT and / or transmission scheme (e.g., such as Figure 4 Otherwise, if the WTRU's data rate is greater than the threshold, the WTRU may select another LBT and / or transmission scheme (e.g., Figure 4 LBT and / or transmission scheme C shown in , where the WTRU may transmit one TB across multiple LBT subbands). The buffer size threshold may be (e.g., pre-)configured in the resource pool.

[0135] In an eighth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the CBR of the resource pool and / or LBT subband. For example, if the CBR is greater than a threshold, the WTRU may select an LBT and / or transmission scheme (e.g., Figure 3 Otherwise, if the CBR is less than the threshold, the WTRU may select another LBT and / or transmission scheme (e.g., Figure 3 A second LBT and / or transmission scheme for one TB as shown in FIG.

[0136] In a ninth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the order of transmission of TBs in the COT and / or the transmission time slot of the COT. For example, for one or more TBs at the beginning of the COT, the WTRU may select an LBT and / or transmission scheme for one TB (e.g., such as Figure 3 , where the WTRU may perform multiple transmissions of the TB in a timeslot and each transmission may be within an LBT subband). For example, for one or more TBs at the end of the COT or for a TB after the first one or more TBs of the COT, the WTRU may select another LBT and / or transmission scheme for another TB (e.g., as Figure 3 , where a WTRU may perform one transmission of a TB in a timeslot across multiple LBT subbands).

[0137] In a tenth example, the WTRU may determine which LBT and / or transmission scheme to use for wideband operation based on the number of TBs prepared for LBT and / or transmission. For example, if the WTRU has prepared one TB before LBT, it may perform an LBT and / or transmission scheme (e.g., Figure 3 Otherwise, if the WTRU has prepared more than one TB (e.g., two TBs) before the LBT, it may perform another LBT and / or transmission scheme (e.g., Figure 3 The fourth LBT and / or transmission scheme shown in ).

[0138] The WTRU determines the number of TBs to prepare for LBT and / or transmission in wideband operationIn one aspect, the WTRU may prepare only one TB for one or more LBT and / or transmission opportunities in a set of LBT subbands. In another aspect, the WTRU may prepare multiple TBs for one or more LBT and / or transmission opportunities. The WTRU may determine the number of TBs to prepare for one or more LBT and / or transmission opportunities based on any of the following: (i) the resource size used to perform LBT and / or transmission; and (ii) the set of LBT subbands used to perform LBT and / or transmission.

[0139] For example, the WTRU may determine a number of TBs that are smaller in resource size than the number of LBT subbands for LBT and / or transmission.

[0140] For example, the WTRU may be (e.g., pre-)configured with a maximum / minimum number of TBs to prepare based on the number of LBT subbands that the WTRU may intend to use to perform LBT and / or transmission. The WTRU may then determine the number of TBs to prepare to satisfy the maximum / minimum (e.g., pre-)configured values.

[0141] For example, the WTRU may perform transmissions for each TB in one LBT subband. The WTRU may then determine the number of TBs to prepare for wideband operation based on the number of LBT subbands that the WTRU may intend to use to perform LBT and / or transmissions. The WTRU may then determine the number of TBs to perform transmissions based on the number of acquired LBT subbands. For example, the WTRU may perform transmissions for each TB in one acquired LBT subband.

[0142] The WTRU determines which TB to transmit in the acquired set of LBT subbands In some embodiments, the WTRU may prepare multiple TBs for wideband operation. The WTRU may perform LBT in a set of LBT subbands. The WTRU may acquire one or more LBT subbands. The WTRU may determine which TB to transmit in one or more acquired resources of one or more LBT subbands based on one or any combination of the following four examples.

[0143] In a first example, the WTRU may determine which TB to transmit in one or more acquired resources of one or more LBT subbands based on the LBT subband associated with the initial transmission of the TB. For example, the WTRU may determine which TB may be transmitted in an LBT subband based on whether the LBT subband is used for the initial transmission of the TB. For example, for an acquired COT in an LBT subband, the WTRU may prioritize the TB with the initial transmission in the LBT subband.

[0144] In a second example, the WTRU may determine which TB to transmit in one or more acquired resources of one or more LBT subbands based on the QoS associated with the TB. For example, if the number of acquired LBT subbands is less than the number of acquired LBT subbands, the WTRU may select which TB to transmit based on the QoS of the TB. Specifically, the WTRU may prioritize TBs with higher priority to be transmitted first. In another example, the WTRU may determine which TB to transmit based on whether it is performing an initial transmission or a retransmission of the TB. Specifically, the WTRU may prioritize the retransmission of a TB relative to the initial transmission of the TB in the acquired LBT subband.

[0145] In a third example, the WTRU may determine which TB to transmit in one or more acquired resources of one or more LBT subbands based on the remaining PDB of the TB. For example, the WTRU may determine whether to perform an initial transmission of a TB or a retransmission of another TB. In one scheme, the WTRU may prioritize the TBs for retransmission. In another scheme, the WTRU may determine which TB to transmit in the resources based on the remaining PDB of the TB. For example, the WTRU may prioritize the TBs with smaller remaining PDBs. If the remaining PDB of the TB for retransmission is less than the PDB of the TB for initial transmission, the WTRU may prioritize the TB for retransmission. Otherwise, the WTRU may prioritize the TB for initial transmission.

[0146] In a fourth example, the WTRU may determine which TB to transmit in one or more acquired resources of one or more LBT subbands based on one or more LBT parameters associated with the TB. In one example, the WTRU may determine whether a TB may be transmitted in the acquired COT of the LBT subband based on one or more LBT parameters for accessing the LBT subband. Specifically, the WTRU may be (e.g., pre-) configured with one or more LBT parameters for accessing a channel based on the QoS of the TB. Based on the values ​​of the one or more LBT parameters for accessing the channel, the WTRU may determine which TB may access the channel (e.g., a TB with a priority greater than a threshold). Then, if the QoS (e.g., priority) of the TB is greater than the threshold, the WTRU may perform the transmission of the TB in the acquired COT. Otherwise, the WTRU may not transmit the TB in the acquired COT. In another example, the WTRU may determine which TB to transmit in the acquired LBT based on the CAPC associated with the TB. Specifically, the WTRU may prioritize the TB with the lowest CAPC value (e.g., the highest priority).

[0147] WTRU determines to perform LBT subband selection (reselection) In some embodiments, the WTRU may perform transmissions in a set of LBT subbands. The WTRU may trigger LBT subband selection (reselection). For example, the WTRU may determine which LBT subbands to select or reselect for its transmission. For LBT subband selection, the WTRU may select a set of LBT subbands for performing LBT and / or transmission. For LBT subband reselection, the WTRU may reselect a different or the same set of LBT subbands. The WTRU may select (reselect) a primary LBT subband for performing a type of LBT (e.g., type 1 LBT) for a type of multi-channel LBT (e.g., type BLBT). LBT subband selection (reselection) may be triggered based on one or any combination of the following nine examples of events (e.g., based on any of the following conditions being met).

[0148] In a first example, LBT subband selection (reselection) may be triggered based on the number of available resources (e.g., time slots) within a window (e.g., resource selection window) being less than a threshold. For example, the WTRU may be (e.g., pre-)configured with a threshold for the number / percentage of available resources (e.g., available time slots) for triggering LBT subband selection (reselection). The WTRU may first determine the set of available resources (e.g., time slots) in the window (e.g., resource selection window). If the percentage / number of available resources is less than a (e.g., pre-)configured value, the WTRU may trigger subband selection (reselection). Otherwise, the WTRU may use the current LBT subband.

[0149] In a second example, LBT subband selection (reselection) may be triggered based on preemption of reserved resource(s) in the current set of LBT subband(s). For example, the WTRU may trigger LBT subband selection (reselection) if one or more of the WTRU's reserved resource(s) are preempted.

[0150] In a third example, LBT subband selection (reselection) may be triggered based on WTRU triggering resource selection (reselection). For example, if WTRU triggers resource selection (reselection), WTRU may trigger LBT subband selection (reselection).

[0151] In a fourth example, LBT subband selection (reselection) may be triggered based on the WTRU's failure to access the channel after multiple LBT attempts. For example, the WTRU may select a (e.g., certain) number of resources (e.g., time slots) for performing LBT before transmission. If the number of LBT failures is greater than a threshold, the WTRU may trigger an LBT subband switch. The threshold may be (e.g., pre-)configured in the resource pool, which may be a function of any of the QoS of the TB, one or more LBT parameters, and the CBR of the resource pool.

[0152] In a fifth example, LBT subband selection (reselection) may be triggered based on the WTRU failing to access the channel after a certain period of time. For example, the WTRU may perform LBT for accessing the channel for transmission of one or more TBs. If the WTRU fails to access the channel after a (e.g., pre-)configured period of time, the WTRU may trigger LBT subband selection (reselection). The (e.g., pre-)configured period of time may be a function of any of the QoS of the TB, one or more LBT parameters (e.g., CAPC, contention window, etc.), and the CBR of the resource pool and / or LBT subband.

[0153] In a sixth example, LBT subband selection (reselection) may be triggered based on the number of transmissions for one or more TBs within a period being less than a threshold. For example, if the number of transmissions performed for one or more TBs within a period threshold is less than a threshold, the WTRU may trigger LBT subband selection (reselection). The number of transmission thresholds and / or period thresholds may be (e.g., pre) configured in the resource pool, which may be a function of any of the QoS of the TB, one or more LBT parameters, and the CBR of the resource pool.

[0154] In a seventh example, LBT subband selection (reselection) may be triggered based on the WTRU's failure to transmit one or more TBs. For example, if the WTRU fails to transmit a (e.g., a certain) number of TBs, the WTRU may trigger LBT subband reselection. The number of failed TB transmissions for triggering LBT subband selection (reselection) may be (e.g., pre) configured in the resource pool, which may depend on any of the QoS of the TB, the CBR of the resource pool, and one or more LBT parameters for accessing the channel. The WTRU may consider whether a TB transmission has failed based on any of the following: (i) the number of transmissions for the TB (e.g., within the PDB of the TB) is less than a threshold (which may be a function of the QoS of the TB); and (ii) the WTRU does not receive any ACK feedback within the PDB of the TB from the Rx WTRU to acknowledge the reception of the TB, or the WTRU receives NACK feedback from the Rx WTRU to indicate a reception failure.

[0155] In an eighth example, LBT subband selection (reselection) may be triggered based on one or more LBT parameters satisfying (e.g., pre-configured) conditions for LBT subband selection (reselection). For example, if the WTRU uses a maximum contention window value (i.e., CW ) for any of a (e.g., pre-)configured period, a (e.g., pre-)configured number of times, and a (e.g., pre-)configured number of COTs, p =CW max ), the WTRU may be (e.g., pre-)configured to perform LBT subband selection (reselection).

[0156] In a ninth example, LBT subband selection (reselection) may be triggered based on a CBR of one or more LBT subbands in a current set of (one or more) LBT subbands being greater than a threshold. For example, if the CBR of the WTRU's current LBT subband is greater than a threshold, the WTRU may trigger LBT subband selection (reselection). The threshold may be (e.g., pre) configured in a resource pool.

[0157] The WTRU determines the set of LBT subbands for performing LBT and / or transmission In some embodiments, the WTRU may perform LBT subband selection (reselection) by performing one or any combination of the following two examples of operations.

[0158] In a first example of operation, the WTRU may select an LBT subband or a set of (one or more) LBT subbands for performing LBT and / or transmission of one or more TBs.

[0159] In a second example of operation, for multi-channel access, the WTRU may determine an LBT subband (i.e., a primary LBT subband) for performing one type of LBT (e.g., Type 1 LBT). If LBT is successful in the selected LBT subband, the WTRU may determine a set of LBT subbands selected for performing another type of LBT (e.g., the WTRU may select a set of LBT subbands for at least T mc =25 μs sensing interval to sense each LBT subband). The WTRU may then determine the set of LBT subbands to use for performing transmission from the set of successful LBT subbands.

[0160] The WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on one or any combination of the following ten examples.

[0161] In a first example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on the CBR of the LBT subband. In one example, the WTRU may select an LBT subband with a CBR less than a threshold. Specifically, the WTRU may be (e.g., pre) configured with a CBR threshold for selecting an LBT subband. If the CBR of the LBT subband is less than the threshold, the WTRU may be allowed to select the LBT subband. Otherwise, the WTRU may not select the LBT subband. If the WTRU has multiple LBT subbands with a CBR below the threshold, in one approach, the WTRU may select the LBT subband with the lowest CBR. In another approach, the WTRU may select an LBT subband (e.g., randomly) from a set of LBT subbands that meet the CBR threshold.

[0162] In a second example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on a set of available resources in a window (e.g., a resource selection window). For example, the WTRU may be (e.g., pre-)configured with a threshold of the number / percentage of available resources (e.g., available time slots) for performing LBT and / or transmission in the LBT subband. If the number / percentage of available resources (e.g., time slots) for performing LBT and / or transmission is greater than the threshold, the WTRU may select the LBT subband. Otherwise, the WTRU may not select the LBT subband. If the WTRU has multiple LBT subbands with a number / percentage of available resources less than the threshold, in one approach, the WTRU may select the LBT subband with the highest number / percentage of available resources. In another approach, the WTRU may select an LBT subband (e.g., randomly) from a set of LBT subbands that meet the threshold.

[0163] In a third example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on the selected primary LBT subband for wideband operation. For example, when LBT in the primary LBT subband is successful, the WTRU may sense that the channel may be idle for at least T mc =25μs later, the LBT subband for performing transmission is selected. The WTRU may select a secondary LBT subband for transmission that satisfies the contiguity of the primary LBT subband. Specifically, the WTRU may prioritize transmissions in the primary LBT subband and the two LBT subbands adjacent to it. For example, the WTRU may acquire a set of LBT subbands for performing transmission. If the acquired set of LBT subbands is non-contiguous, the WTRU may discard one or more of the (one or more) LBT subbands, resulting in non-contiguous transmissions with respect to the primary LBT subband.

[0164] In a fourth example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on a destination associated with a TB. For example, the WTRU may be (e.g., pre-)configured with a set of LBT subbands for (e.g., per) destination (e.g., per destination ID, per unicast pair, per multicast ID, etc.). The WTRU may then determine a set of LBT subbands for performing LBT and / or transmission based on the (e.g., pre-)configured LBT subbands for the destination. The (pre-)configuration may be based on an association between LBT subbands and services. The (pre-)configuration may be based on a negotiation between WTRUs in a group (e.g., for unicast, multicast), where the WTRU may use PC5 RRC to communicate such negotiation.

[0165] In a fifth example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on whether HARQ feedback resources are (e.g., pre-)configured in the LBT subbands. For example, for HARQ-enabled TBs, the WTRU may prioritize LBT subbands with (e.g., pre-)configured HARQ feedback resources. For HARQ-disabled TBs, the WTRU may prioritize LBT subbands without (e.g., pre-)configured HARQ feedback resources.

[0166] In a sixth example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on one or more LBT parameters for accessing each LBT subband. For example, the WTRU may select an LBT subband with a contention window (e.g., value) less than a threshold. Specifically, the WTRU may be (e.g., pre-)configured with a contention window threshold (e.g., for CW) for selecting an LBT subband. p , CW min,p or CW max,p If the contention window (e.g., value) of the LBT subband is less than the threshold, the WTRU may be allowed to select the LBT subband. Otherwise, the WTRU may not select the LBT subband. If the WTRU has multiple LBT subbands with contention windows (e.g., value) below the threshold, then in one scheme, the WTRU may select the LBT subband with the lowest value of the contention window. In another scheme, the WTRU may select an LBT subband (e.g., randomly) from a set of LBT subbands that meet the contention window threshold.

[0167] In a seventh example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on the earliest available resources of (e.g., each) LBT subband. For example, the WTRU may prioritize the LBT subbands with the earliest resources (e.g., time slots) for LBT and / or transmission.

[0168] In an eighth example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on the first successful subband in the LBT. For example, the WTRU may perform LBT in the set of LBT subbands, and the WTRU may then perform transmission in the first acquired LBT subband.

[0169] In a ninth example, the WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on the availability of a shareable COT in one LBT subband. For example, the WTRU may prioritize selecting LBT subbands with shareable COTs within a resource selection window. The WTRU may share a COT with another WTRU using frequency division multiplexing (e.g., the WTRU may use an orthogonal interleave with the interleave used by the COT initiator WTRU) or using time division multiplexing (e.g., the WTRU may perform a transmission after the other WTRU completes its transmission).

[0170] In a tenth example, a WTRU may determine a set of (one or more) LBT subbands for performing LBT and / or transmission based on an implicit / explicit indication from another network element. Specifically, the WTRU may implicitly / explicitly receive an indication from an RxWTRU to perform LBT and / or transmission in an LBT subband. The WTRU may then select an LBT subband for performing LBT and / or transmission. In one example, the WTRU may receive HARQ ACK / NACK feedback from an Rx WTRU. The TxWTRU may then select an LBT subband with HARQ feedback from the Rx WTRU to perform LBT and / or transmission. In another example, the WTRU may receive an indication from an Rx WTRU (e.g., via a PC5 radio resource control (RRC) message) to perform LBT and / or transmission in an LBT subband. The WTRU may then perform LBT and / or transmission in the indicated LBT subband. In another example, the WTRU may receive a transmission from a peer WTRU in an LBT subband. The WTRU may then select the LBT subband to perform LBT and / or transmission. In another example, the WTRU may receive sensing information (e.g., a set of available resources) in an LBT subband. The WTRU may then select the LBT subband with the sensing information to perform LBT and / or transmission.

[0171] The WTRU determines whether to maintain the current set of LBT subband(s) to perform LBT and / or transmission In some embodiments, the WTRU may semi-statically use a set of LBT subbands to perform LBT and / or transmission. The WTRU may trigger resource allocation (e.g., for either a new TB or a retransmission of an existing TB). The WTRU may determine whether to maintain the current set of (one or more) LBT subbands to perform LBT and / or transmission based on one or any combination of the following five examples.

[0172] In a first example, the WTRU may determine whether to maintain the current set of (one or more) LBT subbands to perform LBT and / or transmission based on the resource pool and / or the CBR of the LBT subband. For example, if the CBR of the LBT subband is less than a threshold, the WTRU may determine to maintain the current LBT subband. Otherwise, the WTRU may switch to another LBT subband to perform LBT and / or transmission.

[0173] In a second example, the WTRU may determine whether to maintain the current set of LBT subbands (one or more) to perform LBT and / or transmission based on the availability of a shareable COT in the current set of LBT subbands. For example, if the WTRU detects a shareable COT in the current set of LBT subbands (one or more), the WTRU may maintain the current set of LBT subbands.

[0174] In a third example, the WTRU may determine whether to maintain the current set of (one or more) LBT subbands to perform LBT and / or transmission based on the availability of a shareable COT in another set of LBT subbands. For example, if the WTRU detects a shareable COT in another set of LBT subbands within the resource selection window, the WTRU may switch to another LBT subband.

[0175] In a fourth example, the WTRU may determine whether to maintain the current set of (one or more) LBT subbands to perform LBT and / or transmission based on one or more LBT parameters satisfying the (e.g., pre-)configured conditions for maintaining the LBT subbands. In one example, the WTRU may be (e.g., pre-)configured with a contention window threshold (e.g., CW ) for maintaining the current set of (one or more) LBT subbands. p , CW min,p or CW max,p If the contention window (e.g., value) satisfies a (e.g., pre-)configured threshold (e.g., CW p Smaller than CW p , the WTRU may maintain the current set of LBT subbands. Otherwise, the WTRU may switch to another set of (one or more) LBT subbands. In another example, the WTRU may be (e.g., pre-)configured with an initialized backoff value threshold for maintaining the current set of (one or more) LBT subbands. If the initialized backoff value is less than the threshold, the WTRU may maintain the current set of LBT subbands. Otherwise, the WTRU may switch to another set of (one or more) LBT subbands.

[0176] In a fifth example, the WTRU may determine whether to maintain the current set of (one or more) LBT subbands to perform LBT and / or transmission based on the number of available resources (e.g., time slots) in a window (e.g., a resource selection window) for performing LBT and / or transmission. For example, the WTRU may be (e.g., pre-) configured with a threshold of the number / percentage of available resources (e.g., available time slots) for performing LBT and / or transmission to maintain the current set of (one or more) LBT subbands. If the number / percentage of available resources (e.g., time slots) is greater than the threshold, the WTRU may maintain the current set of (one or more) LBT subbands. Otherwise, the WTRU may select a different set of (one or more) LBT subbands.

[0177] The WTRU determines available resources (e.g., time slots) for LBT and / or transmission In some embodiments, the WTRU may determine a set of available resources (e.g., time slots) in a resource selection window for performing LBT and / or transmission. Specifically, if a resource (e.g., time slot) satisfies one or any combination of the following two examples of conditions, the WTRU may determine that the resource is available.

[0178] In a first example, a WTRU may determine that a resource (eg, a time slot) is available if the resource is not reserved by any WTRU.

[0179] In a second example, a WTRU may determine a resource (e.g., a time slot) as available if it is reserved by another WTRU and the sidelink reference signal received power (SL-RSRP) is less than a threshold. In one approach, the threshold may be fixed, which may be a function of a channel idle detection threshold. In another approach, the threshold may be based on any of the following: (i) one or more LBT parameters of a reserved WTRU for a reserved channel; (ii) QoS of a reserved TB; (iii) one or more LBT parameters of a WTRU for an access channel; and (iv) QoS of a TB and / or SLRB / LCH.

[0180] The WTRU determines which timeslot to perform LBT and / or transmission of one or more TBs In some embodiments, the WTRU may (e.g., first) determine a set of available resources (e.g., time slots) based on SCI decoding in a resource selection window. The resource selection window may be a window that starts after a first offset (e.g., T1) from a time slot (e.g., n) in which the WTRU may have triggered resource selection and ends after a second offset (e.g., T2) from a time slot in which the WTRU may have triggered resource selection (e.g., a window of time slots that may be referred to as [n+T1, n+T2]). The WTRU may (e.g., then) perform one or any combination of the following to select resources (e.g., time slots) for performing LBT and / or transmission.

[0181] In a first approach, the WTRU may select a set of the first (e.g., initial) N resources (e.g., time slots) for possible LBT and / or transmission in a resource selection window (N may be referred to as an integer). The first (e.g., initial) N resources (e.g., time slots) may be located at the beginning of the resource selection window. In one approach, the WTRU may select N resources from one LBT subband. In another approach, the WTRU may select N resources from multiple LBT subbands. The WTRU may select (e.g., randomly) one resource (e.g., time slot) from the set of the first N resources for performing LBT and / or transmission. If the WTRU successfully acquires the channel, the WTRU may perform transmission in the selected resource. Otherwise, if the WTRU fails to access the channel, in one approach, the WTRU may select another resource (e.g., time slot) from the remaining resources in the N resources (e.g., randomly). In another approach, the WTRU may perform LBT on the next available resource (e.g., time slot). The value of N (e.g., any of a minimum, maximum, and exact value) can be (e.g., pre-)configured in the resource pool and / or can be a function of the QoS of the TB (e.g., any of priority and remaining PDBs), one or more LBT parameters (e.g., contention window), and any of the CBR of the resource pool.

[0182] In a second approach, the WTRU may select a window (e.g., a resource selection subwindow), which may be located at the beginning of the resource selection window. The WTRU may then select a resource (e.g., a time slot) from a set of available resources within the resource selection subwindow for performing LBT and / or transmission (e.g., randomly). If the WTRU successfully acquires the channel, the WTRU may perform the transmission in the selected resource. Otherwise, if the WTRU fails to acquire the channel, in one approach, the WTRU may select another resource (e.g., a time slot) from the resource allocation subwindow (e.g., randomly). In another approach, the WTRU may perform LBT on the next available resource (e.g., a time slot). The size of the resource selection subwindow (e.g., any of a minimum size, a maximum size, an exact size) may be (e.g., pre-) configured in the resource pool, and / or may be a function of any of the QoS of the TB (e.g., priority or remaining PDB), one or more LBT parameters, and the CBR of the resource pool.

[0183] In the above first and second schemes, the WTRU can (e.g., randomly) select resources (e.g., time slots) for performing LBT and / or transmission to reduce conflicts between different WTRUs performing LBT simultaneously.

[0184] exist Figure 5 In one example shown in FIG. 5 , the WTRU may perform one of two options (e.g., a first scheme 51 versus a second scheme 52) to determine a first time slot for LBT and / or transmission. In the first scheme 51, the WTRU may select the first N=4 available time slots 511, 512, 513, 514. The WTRU may then select a time slot (e.g., randomly) from the N=4 available time slots (e.g., Figure 5 In a second approach, the WTRU may determine a resource allocation (RA) subwindow 520 to determine the first time slot in which to perform LBT and / or transmission. In the subwindow 520, the WTRU may have three available time slots 521, 522, 523. The WTRU may then (e.g., randomly) select one of those three time slots (e.g., Figure 5 The 3rd time slot 523) in the transmission to perform LBT and / or transmission.

[0185] The WTRU determines to perform neighbor LBT In some embodiments, the WTRU may perform contiguous LBT until it acquires an LBT subband for performing transmission.The WTRU may first select a first resource (eg, time slot) for performing LBT, which may be determined based on one or any combination of the following three schemes.

[0186] In a first approach, the WTRU may perform SCI decoding to determine a set of available resources. The WTRU may then select a resource (e.g., randomly) from a set of the first N available resources (e.g., time slots), or it may select an available resource (e.g., time slot) from a set of N available resources (e.g., randomly). The WTRU may then perform contiguous LBT until it acquires an LBT subband. The value of N (e.g., any of a minimum (e.g., lower) value, a maximum (e.g., upper) value, an exact value) may be (e.g., pre-)configured in the resource pool, which may be a function of any of the QoS of the TB (e.g., priority and / or remaining PDBs), one or more LBT parameters (e.g., contention window), and the CBR of the resource pool.

[0187] In a second approach, the WTRU may perform SCI decoding to determine a set of available resources. The WTRU may then select (e.g., randomly) one resource (e.g., time slot) in the subwindow from the set of available resources. The WTRU may then perform contiguous LBT until it acquires the LBT subband. The size of the subwindow (e.g., any of a minimum (e.g., lower) size, a maximum (e.g., upper) size, an exact size) may be (e.g., pre-)configured in the resource pool, which may be a function of any of the QoS of the TB (e.g., priority and / or remaining PDBs), one or more LBT parameters, and the CBR of the resource pool.

[0188] In a third approach, the WTRU may not perform SCI decoding to determine available resources in the resource selection window. The WTRU may first select (e.g., randomly) a resource (e.g., a time slot) in a subwindow (e.g., a RA subwindow) to perform LBT and / or transmission. The WTRU may then perform contiguous LBT until it acquires an LBT subband. The size of the subwindow (e.g., any of a minimum (e.g., lower) size, a maximum (e.g., upper) size, an exact size) may be (e.g., pre-)configured in the resource pool, which may be a function of any of the QoS of the TB (e.g., priority and / or remaining PDBs), one or more LBT parameters, and the CBR of the resource pool.

[0189] In the above scheme, the WTRU may select resources (eg, time slots) for performing LBT and / or transmission to reduce conflicts between different WTRUs performing LBT simultaneously.

[0190] exist Figure 6In one example shown in , the WTRU may perform one of three schemes 61, 62, 63 to determine a first time slot for performing LBT and / or transmission. After the first time slot may be selected, the WTRU may perform neighbor sensing until it acquires the LBT subband. The WTRU may perform SCI decoding in the first 61 and second 62 schemes to determine the set of available resources. Figure 6 In the first scheme 61 illustrated in the top portion of FIG. , the WTRU may select (eg, randomly) a time slot from a set of the first N available time slots (eg, Figure 6 The second time slot shown at 612 in FIG. Figure 6 In the second scheme 62 illustrated in the middle portion of FIG. 5 , the WTRU may select (eg, randomly) a time slot (eg, Figure 6 The third time slot shown at 623 in FIG. Figure 6 In the third scheme 63 illustrated in the bottom portion of FIG. 5 , the WTRU may not perform SCI decoding to determine the set of available resources. The WTRU may select a time slot (e.g., randomly) in the subwindow (e.g., Figure 6 The third time slot shown at 633 in the figure) is used to perform LBT.

[0191] The WTRU determines the availability of a reserved resource and / or COT from another WTRU In some embodiments, the WTRU may receive an SCI from another WTRU that has reserved resources and / or COT. The WTRU may determine whether the reserved resources and / or COT are available. For example, if the reserved resources (e.g., the reserved COT) are available, the WTRU may include it in the set of resources for selection and transmission. Otherwise, if the reserved resources are not available, the WTRU may exclude it from the set of resources for selection and transmission. The WTRU may determine whether the reserved resources are available based on any of the QoS, CAPC, one or more LBT parameters, and SL-RSRP associated with the reserved resources and / or any of the QoS, CAPA, and one or more LBT parameters associated with the WTRU's data. In one example, if the CAPC associated with the WTRU's data is greater than the CAPC associated with the reserved resources, the WTRU may consider (e.g., determine to be) available the reserved resources. Otherwise, the WTRU may consider (e.g., determine to be) unavailable the reserved resources. In another example, if the CAPC associated with the reserved resources is greater than a (e.g., pre) configured threshold, the WTRU may consider (e.g., determine) the reserved resources to be unavailable. Otherwise, the WTRU may consider (e.g., determine) the reserved resources to be unavailable.

[0192] The WTRU determines the availability of one or more time slots after the COT of another WTRUIn some embodiments, the WTRU may determine the availability of resources for transmission and / or reservation. The WTRU may determine the availability of one or more time slots after the COT of another WTRU. For example, the WTRU may determine whether one or more time slots after the COT of another WTRU are available based on one or any combination of the following two examples.

[0193] In a first example, the WTRU may determine whether one or more time slots after the COT of another WTRU are available based on the QoS of the TB and / or one or more LBT parameters of the WTRU. For example, if the QoS of the TB and / or the CAPC of the TB are less than a threshold, the WTRU may determine the first time slot after the reserved COT of the other WTRU as available. For example, if the QoS of the TB and / or the CAPC of the TB are greater than a threshold and less than another threshold, the WTRU may consider (e.g., determine as) one time slot after the reserved COT of the other WTRU as unavailable. For example, if the QoS of the TB and / or the CAPC of the TB are less than a threshold, the WTRU may consider (e.g., determine as) N≥2 time slots after the reserved COT of the other WTRU as unavailable. This scheme may allow the WTRU to reserve time for LBT after the COT of another WTRU.

[0194] In a second example, the WTRU may determine whether one or more time slots after the COT of another WTRU are available based on the QoS associated with the reserved COT and / or one or more LBT parameters associated with the reserved COT.

[0195] WTRU performs puncturing / rate matching on another WTRU’s transmission before reserved resources / COT In some embodiments, the WTRU may rate match / puncture a portion of the transmission resources in the last transmission before the reserved resources / COT of another WTRU. Rate matching / puncturing a transmission may be used interchangeably herein with the WTRU process for determining the duration of a transmission, which may be expected for the WTRU to not perform a transmission of one or more symbols. The WTRU may then implicitly and / or explicitly indicate the puncturing / rate matching duration or the transmission duration (e.g., in the SCI), which may be used to support the receiving WTRU to decode the TB. The rate matching / puncturing duration may be determined based on one or any combination of the following four examples.

[0196] In a first example, the rate matching / puncturing duration may be determined based on a (e.g., pre) configuration in a resource pool. In an example, the WTRU may be (e.g., pre) configured to puncture / rate match a portion of the resources in the last transmission before the reserved resources / COT. The WTRU may then follow the (e.g., pre) configured value to determine the duration of the puncturing / rate matching. In another example, the WTRU may be (e.g., pre) configured to stop transmission of one or more symbols before the reserved resources (e.g., COT) of another WTRU. The WTRU may then determine to stop transmission at this time.

[0197] In a second example, the rate matching / puncturing duration may be determined based on an implicit and / or explicit indication in a transmission reserving the resource (e.g., SCI). In one example, the WTRU may determine the rate matching / puncturing duration based on an indicated LBT duration (e.g., expected LBT duration) of a channel accessing the other WTRU (e.g., the WTRU reserving the resource / COT). The LBT duration may be indicated in the SCI. In another example, the WTRU may determine the rate matching / puncturing duration based on one or more LBT parameters (e.g., contention window value) and / or one or more QoS parameters (e.g., priority) indicated in a transmission reserving the WTRU (e.g., SCI).

[0198] In a third example, the rate matching / puncturing duration may be determined based on the QoS of the TB and / or one or more LBT parameters for accessing the LBT subband.

[0199] In a fourth example, the rate matching / puncturing duration may be determined based on the CBR of the resource pool and / or LBT subband.

[0200] exist Figure 7 In one example shown in , the WTRU may obtain the COT and perform transmissions in the vertical shaded rectangle shown at 701. The WTRU may (e.g., intend to) perform two transmissions in the COT. In the last transmission, the WTRU may rate match / puncture several symbols to help (e.g., assist) other WTRUs to perform LBT (e.g., in the rectangle shown at 702).

[0201] The WTRU performs puncturing / rate matching in the last transmission of its COT The WTRU may determine the transmission duration in the last transmission of the COT. For example, the WTRU may perform puncturing / rate matching in the last transmission of its COT, which may be used to facilitate LBT procedures for other WTRUs. The WTRU may determine any of the following: (i) whether to perform rate matching / puncturing in the last transmission of its COT; (ii) the puncturing / rate matching duration; and (iii) the transmission duration of the last transmission of the COT.

[0202] The transmission and / or puncturing / rate matching duration of the last transmission may be determined based on one or any combination of the following four examples.

[0203] In a first example, the transmission and / or puncturing / rate matching duration of the last transmission may be determined based on whether the COT is shareable. For example, the WTRU may be (e.g., pre-)configured with a gap duration between the last transmission in the COT and a slot boundary for use with a shareable COT. The WTRU may determine the duration of the last transmission to be punctured / rate matched to satisfy the (e.g., pre-)configured gap between the last transmission and a slot boundary. For example, if the COT is not shareable, the WTRU may perform a transmission in a full slot. In this scenario, the WTRU may also use the last symbol as a guard symbol for Tx / Rx switching.

[0204] In a second example, the transmission and / or puncturing / rate matching duration of the last transmission may be determined based on whether there are any reserved resources after the last transmission: for example, if there are any reserved resources after the last transmission, the WTRU may determine to perform puncturing / rate matching for a certain duration (e.g., one or more symbols) in its last transmission of the COT.

[0205] In a third example, the transmission and / or puncturing / rate matching duration of the last transmission may be determined based on the QoS of the TB and / or one or more LBT parameters used to access the LBT subband.

[0206] In a fourth example, the transmission and / or puncturing / rate matching duration of the last transmission may be determined based on the CBR of the resource pool and / or LBT subband.

[0207] WTRU determines puncturing / rate matching in simultaneous multiple LBT subband transmissions In some embodiments, the WTRU may perform simultaneous transmissions on multiple LBT subbands. The WTRU may determine the transmission duration in the last transmission of the COT based on the transmission duration in each LBT subband. For example, the transmission duration on multiple LBT subbands may be the minimum (e.g., lowest) transmission duration of all LBT subbands. The WTRU may indicate to another node (e.g., in an SCI) the transmission duration of multiple LBT subbands for broadband operation. This scheme may allow the WTRU to complete its transmissions for all LBT subbands simultaneously.

[0208] The WTRU terminates its COT for a certain duration before reserving resources A WTRU may terminate its COT (e.g., early COT termination) within a certain duration (e.g., one or more time slots) before another WTRU's reserved resources (e.g., reserved COT). The early COT termination duration may be determined based on the (pre-)configuration of the resource pool and one or more LBT / QoS parameters of the reserved COT and / or any of the WTRUs. The one or more LBT / QoS parameters of the reserved COT may be indicated in the transmission (e.g., SCI) that reserved the COT. For example, the transmission stop duration may be determined based on the CAPC and / or contention window indicated in the reserved resources. This scheme may allow the WTRU that reserved the COT to have enough time to clear the channel before reserving the resources.

[0209] exist Figure 8 In one example shown in FIG. 8 , a WTRU may acquire a COT and perform a transmission in its COT, which is shown in the vertical shaded rectangle at 801. The WTRU may determine not to perform a transmission one slot before the reserved COT of another WTRU. The other WTRU may then perform LBT (shown at 802) to clear the channel. The COT reserved WTRU may perform a transmission in the reserved COT 803.

[0210] The WTRU terminates its COT for the duration of the broadband operation. The WTRU may terminate its COT (e.g., early COT termination) within a duration (e.g., one or more time slots) for wideband operation (e.g., over multiple LBT subbands). For example, the WTRU may detect a reserved COT of another WTRU in one or more LBT subbands, and the WTRU may then determine to perform early COT termination in the one or more LBT subbands (e.g., stop transmission for one or more time slots before the reserved COT). The WTRU may perform early termination of the COT across the entire wideband. The early termination duration of the COT may be determined based on the early termination of each LBT subband. For example, the termination duration of the COT for wideband operation may be the longest termination among a set of LBT subbands for wideband operation (e.g., for each LBT subband therein).

[0211] The WTRU reserves resources for (eg, potential) transmission A WTRU may reserve one or more resources (e.g., COT) for (one or more) (e.g., potential) transmissions. In one aspect, the WTRU may reserve (one or more) resources for performing LBT and / or transmissions. In another aspect, the WTRU may reserve (one or more) resources for transmissions only. The WTRU may indicate (e.g., transmit information indicating the same as described below) whether the reserved resources are for LBT and / or transmissions. The WTRU may determine whether to reserve resources (e.g., future COTs) for future (e.g., upcoming) transmissions based on one or any combination of the following four examples.

[0212] In a first example, the WTRU may determine whether to reserve resources for one or more upcoming transmissions based on any of the QoS of the TB, SLRB, and LCH. For example, the WTRU may be (e.g., pre-)configured with conditions for (e.g., certain) QoS parameters for reserving resources (e.g., future COTs). If the QoS of the TB is not met, the WTRU may not reserve resources. Otherwise, the WTRU may reserve resources.

[0213] In a second example, the WTRU may determine whether to reserve resources for one or more upcoming transmissions based on the CBR of the resource pool and / or LBT subband. For example, the WTRU may be (e.g., pre-)configured with a range of CBRs for reserving resources (e.g., future COTs). If the CBR is within the range, the WTRU may determine to reserve resources. Otherwise, the WTRU may not reserve resources. The CBR range may be (e.g., pre-)configured as a function of any one of the QoS of the TB, SLRB, and LCH. The CBR range may be (e.g., pre-)configured as a function of any one of the CAPC of the TB, SLRB, and LCH.

[0214] In a third example, the WTRU may determine whether to reserve resources for one or more upcoming transmissions based on the CAPC of the SLRB and / or LCH. For example, the WTRU may be (e.g., pre-)configured with a range of CAPCs for reserving resources (e.g., future COTs). If the CAPC of the TB, SLRB, and / or LCH is within the range, the WTRU may determine to reserve resources. Otherwise, the WTRU may not reserve resources. The CBR range may be (e.g., pre-)configured as a function of any of the QoS of the TB, SLRB, and LCH.

[0215] In a fourth example, the WTRU may determine whether to reserve resources for one or more upcoming transmissions based on one or more LBT parameters for accessing resources. For example, the WTRU may be (e.g., pre-)configured with a contention window (CW) for reserving resources (e.g., a future COT). p ). If the contention window is within the range, the WTRU may determine to reserve resources. Otherwise, the WTRU may not reserve resources.

[0216] The WTRU defers / postpones its transmission to a future time slot In some embodiments, the WTRU may defer / postpone its transmission to a future time slot when LBT is successful (e.g., backoff counter reaches 0, N=0). The WTRU may not d ) to perform transmission after N reaches 0. The WTRU may then continue its LBT in a future time slot (e.g., a short LBT). If the time gap between the LBT success and the reserved COT of another WTRU is less than a threshold, the WTRU may postpone its transmission. The WTRU may then continue its LBT and transmission after the reserved COT. This scheme may allow the WTRU to select more resources for the transmission of a TB. The time gap threshold that may be used to determine whether to postpone its transmission may be determined based on one or any combination of the following four examples.

[0217] In a first example, the time gap threshold may be determined based on a (e.g., pre-)configuration in the resource pool. For example, if the LBT success practice is one time slot before the reserved COT of another WTRU, the WTRU may be (pre-)configured to postpone / delay its LBT and / or transmission. If the time gap between the LBT success and the reserved COT of another WTRU is less than one time slot, the WTRU may postpone / delay its transmission.

[0218] In a second example, the time gap threshold may be determined based on the QoS of the TB. For example, the WTRU may be (e.g., pre-)configured with a time gap for deferring / delaying its transmission based on the QoS of the TB (e.g., the reliability or HARQ type of the TB). The WTRU may then determine the time gap threshold for deferring / delaying its transmission based on the QoS of the TB. If the time gap is within the determined time gap threshold, the WTRU may determine to defer / delay its LBT and / or transmission.

[0219] In a third example, the time gap threshold may be determined based on the QoS associated with a reserved COT of another WTRU.

[0220] In a fourth example, the time gap threshold may be determined based on the CBR of the resource pool. For example, the WTRU may be (e.g., pre-)configured with a time gap threshold for deferring its transmission according to the CBR of the resource pool. The WTRU may determine the time gap threshold for deferring / delaying its transmission based on the CBR of the resource pool. The WTRU may determine whether to defer / delay its transmission based on whether the time gap between the LBT success and the reserved COT of another WTRU is greater than the determined time gap threshold.

[0221] exist Fig. 9 In one example shown in FIG. 1 , a WTRU may succeed in the LBT process as shown at 91 before another WTRU's reserved COT 92. The WTRU may defer its transmission in the window between the LBT success time and the other WTRU's reserved COT. The WTRU may continue its LBT as shown at 93 and may obtain a new COT 94 after the other WTRU's reserved COT 92.

[0222] The WTRU determines which time slots are not available for performing LBT and transmitting In one embodiment, the WTRU may determine a set of time slots in which to perform LBT and transmission. For example, the WTRU may perform LBT before a time slot boundary and may transmit PSCCH / PSSCH from the time slot boundary. The WTRU may consider (e.g., determine as) the following time slots as unavailable for LBT and transmission.

[0223] If frequency division multiplexing (FDM) between two WTRUs in the same time slot is not allowed in the resource pool, the WTRU may determine that the time slot reserved by another WTRU is unavailable for LBT and transmission.

[0224] The WTRU may determine that X time slots after the reserved time slot are unavailable for LBT and transmission, and the WTRU may consider them unusable for transmission (eg, due to conflict with the reserved WTRU). X may be an integer.

[0225] The WTRU may determine that Y time slots before the reserved time slot are not available for LBT and transmission, and the WTRU may consider them unusable for transmission (eg, due to conflict with the reserved WTRU). Y may be an integer.

[0226] The values ​​of X and / or Y may be determined based on one or any combination of the following examples.

[0227] In a first example, the values ​​of X and / or Y may be determined based on a (e.g., pre-)configuration in a resource pool. For example, the WTRU may be (e.g., pre-)configured with values ​​of X and Y (e.g., for 15KHz subcarrier spacing (SCS), X=1, Y=1; for 30KHz SCS, X=2, Y=2).

[0228] In a second example, the values ​​of X and / or Y may be determined based on the SCS configured (eg, pre) in the resource pool. For example, the values ​​of X and Y may be higher for a higher SCS.

[0229] In a third example, the values ​​of X and / or Y may be based on one or more LBT parameters (e.g., CAPC, CW, p , CW min,p , CW max,p , an initial value of the backoff counter N, a deferral period, etc.). For example, the value of X may be determined based on one or more LBT parameters used by the WTRU to access the channel. In one example, the WTRU may be (e.g., pre-)configured with a value of X per the CAPC. The WTRU may determine the value of X based on the CAPC used to access the channel.

[0230] In a fourth example, the values ​​of X and / or Y may be based on one or more LBT parameters (e.g., CAPC, CW, p , CW min,p , CW max,p , an initial value of the backoff counter N, a deferral period, etc.). For example, the value of Y may be determined based on one or more LBT parameters used by the reserved WTRU to access the channel. In one example, the WTRU may be (e.g., pre-)configured with a value of Y per CAPC. The WTRU may determine the value of Y based on the CAPC used by the reserved WTRU to access the channel.

[0231] The WTRU determines which time slots may be available time slots for performing LBT and transmitting The WTRU may determine a set of available time slots for performing LBT and transmission based on the set of unavailable time slots. For example, from the set of total time slots in the resource selection window, the WTRU may exclude the set of unavailable time slots. The remaining set of time slots may be considered (e.g., determined to be) the set of available time slots. The WTRU may use time slots from the set of available time slots to perform LBT and transmission.

[0232] exist Fig.10 In one example shown in , the WTRU may perform resource allocation in a resource selection window. Fig.10, the white time slot 1011 may be considered (e.g., determined to be) available. The WTRU may detect and determine that there may be two reserved time slots 1012, 1013, which may be considered (e.g., determined to be) unavailable for LBT and transmission. The WTRU may determine that X=2 time slots (e.g., after elimination of the first reserved and unavailable time slot 1012) and Y=1 time slot (e.g., before the second reserved and unavailable time slot 1013). The WTRU may not be able to transmit in the determined time slot. In the case where frequency division multiplexing (FDM) between the two WTRUs is allowed and there are available frequency resources (e.g., available interleaving) in the two reserved time slots, the WTRU may consider the two reserved time slots available. Otherwise, if FDM is not allowed, the WTRU may consider the two reserved time slots unavailable.

[0233] The WTRU determines whether a reserved resource is available or unavailable In one embodiment, the WTRU may perform resource selection in a resource selection window, where the WTRU may perform sensing by decoding the SCI in a sensing window prior to the resource selection window. If a resource is reserved in the resource selection window, the WTRU may determine whether the reserved resource is available based on one or more of the following two examples.

[0234] In a first example, the WTRU may determine whether the reserved resources are available based on the RSSI measured in the transmission that reserved the resources. For example, if the RSSI measured in the transmission that reserved the resources is greater than a (e.g., pre-)configured threshold, the WTRU may consider (e.g., determine) the resources to be unavailable. Otherwise, the WTRU may consider (e.g., determine) the resources to be available. The threshold may be in accordance with the LBT energy detection threshold and a (e.g., pre-)configured offset.

[0235] In a second example, the WTRU may determine whether reserved resources are available based on any of: (i) the CAPC of its data; (ii) the CAPC of the data associated with the reserved resources; and (iii) the relative CAPC of its data and the CAPC associated with the reserved resources.

[0236] exist Fig.11 In one example shown in , a WTRU may determine that resources that may be reserved by another WTRU are unavailable if (1) the CAPC associated with the reserved resource is greater than the CAPC of its data and (2) the RSSI measured in the reserved transmission in the sensing window is greater than (e.g., a preconfigured threshold). Fig.11 , the white time slot shown at 1110 can be considered (eg, determined to be) available.

[0237] The WTRU prioritizes the time slot(s) in which to perform LBT and transmitAfter extracting the sensing results, the WTRU may determine a set of time slots for performing LBT and transmission. The WTRU may determine which resource / time slot to prioritize based on any of the following: (i) a time slot that may not be reserved by any other WTRU; and (ii) a time slot that is earlier in time.

[0238] WTRU procedures after accessing a channel without LBT in a slot allocated for a single channel resource In one embodiment, the WTRU may not perform LBT to access the channel before the selected time slot for performing LBT and transmission. The WTRU may then perform one or any combination of the following three options.

[0239] In a first option, the WTRU may maintain the current LBT parameters (eg, N) and may continue to perform LBT in subsequent time slots.

[0240] In a second option, the WTRU may hop (e.g., continue) to the next pre-selected timeslot. For example, in one scenario, the WTRU may pre-select X timeslots from a set of Y temporally earliest timeslots (e.g., by random selection) to perform LBT and transmission, where the values ​​of X and / or Y (e.g., any of the maximum value of X, the maximum value of Y, the minimum value of X, the minimum value of Y) may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). In another scenario, the WTRU may pre-select X timeslots from a subwindow (e.g., an early subwindow from a resource selection window) to perform LBT and transmission, where the value of X and / or the size of the subwindow may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). If the WTRU fails to access the first pre-selected timeslot, the WTRU may hop (e.g., continue) to a second pre-selected timeslot to perform LBT and transmission. The WTRU may maintain the current LBT parameters before hopping to the second pre-selected timeslot. The WTRU may continue this process until it successfully performs LBT and transmits in one of the pre-selected time slots.

[0241] In a third option, the WTRU may use the updated LBT parameters (e.g., N) to trigger resource selection (reselection) based on LBT failure. For example, the WTRU may first pre-select a timeslot to perform LBT and transmission. If the WTRU fails to access the pre-selected timeslot, the WTRU may trigger resource selection (reselection) based on LBT failure by determining a set of available timeslots for performing LBT and transmission based on the updated LBT parameters (e.g., maintaining the current value of N), the resource selection window, and the QoS of the TB (e.g., the remaining PDB). The WTRU may then pre-select another timeslot to perform LBT and transmission. The WTRU may continue the process until it successfully performs LBT and transmission in one of the pre-selected timeslots.

[0242] exist Fig.12 In one example shown in , the WTRU may first fail to perform LBT and transmit in a pre-selected time slot (e.g., time slot 4). Fig.12 , the white time slot may be considered available. Before failing to perform LBT and transmit in time slot 4, the WTRU may have updated N=1. In the first option 1210, the WTRU may continue to perform LBT from time slot 4 until it successfully performs LBT and can transmit in the time slot. In the second option 1220, the WTRU may first pre-select time slot 4, time slot 5, and time slot 10 to perform LBT and transmission. After the WTRU fails to perform LBT and transmission in time slot 4, it may jump to time slot 5 to perform LBT and transmission. The WTRU may use N=1 as one of (one or more) updated LBT parameters. If the WTRU does not perform LBT and transmission in time slot 5, the WTRU may jump to time slot 10 to perform LBT and transmission. In the third option 1230, the WTRU may trigger resource reselection based on LBT failure, where the WTRU may update the availability of each resource. For example, the WTRU may determine X=0 during this resource selection (reselection) process. The WTRU may determine that the unavailable time slot 8 may be available in the new resource selection (reselection) process. The WTRU may select one of the time slots to perform LBT and transmit. The WTRU may use N=1 as one of the updated LBT parameter(s).

[0243] For wideband operation, the WTRU determines which time slots are available to perform LBT and transmit For wideband operation, the WTRU may be (e.g., pre-)configured to select a resource where at least M sets of RBs are contiguously available (M is an integer). The WTRU may determine to select an available time slot. In one embodiment, the WTRU may consider (e.g., determine to be) a time slot with at least M contiguous available RB sets as an available time slot. In another embodiment, the WTRU may consider (e.g., determine to be) a time slot with at least M contiguous available RB sets including a primary RB set as an available time slot. For example, Fig.13 As shown in , the WTRU may consider (e.g., determine as) available time slots with two available RB sets. Specifically, the WTRU may consider (e.g., determine as) available time slots 5, 9, and 10.

[0244] WTRU prioritizes to perform LBT and transmit in time slots used for wideband transmission After extracting the sensing results, the WTRU may determine a set of time slots in which to perform LBT and transmission. The WTRU may determine which resource / time slot to prioritize based on one or any combination of the following: a time slot that has at least a (e.g. pre-)configured number of (e.g. contiguous) RB sets that is considered available, a time slot that is considered available and has at least a (eg, pre-)configured number of (eg, contiguous) RB sets including the primary RB set, A timeslot that may not be reserved by any other WTRU, The earliest time slot in terms of time.

[0245] For wideband transmission, the WTRU determines in which timeslot to perform LBT and transmit The WTRU may determine in which time slot to perform LBT and transmission for wideband transmission based on a set of time slots having at least M (e.g., pre-)configured contiguous available RB sets. In one embodiment, the WTRU may select (e.g., a certain) number of time slots (e.g., X% of the time slots) in a subwindow (e.g., the earliest subwindow in the resource selection window). The WTRU may select (e.g., randomly) one of the time slots in which to perform LBT and transmission. In another approach, the WTRU may select (e.g., a certain) number of earliest available time slots in time (e.g., X time slots). The WTRU may then (e.g., randomly) select one of the X time slots in which to perform LBT and transmission.

[0246] WTRU procedures after LBT is not performed to access a channel in a slot allocated for multiple channels In one embodiment, for wideband transmission, the WTRU may not perform LBT to access the channel before the selected timeslot for performing LBT and transmission. The WTRU may then perform one or any combination of the following three options.

[0247] In a first option, the WTRU may continue to perform LBT in subsequent available time slots. In one approach, the WTRU may maintain the same primary RB set to perform LBT, and the WTRU may maintain the updated LBT parameters (e.g., N) to perform LBT. In another approach, the WTRU may change the primary RB set and may use another set of LBT parameters to access the channel, which may be associated with the newly selected primary RB set.

[0248] In a second option, the WTRU may hop (e.g., continue) to the next pre-selected time slot. For example, the WTRU may pre-select X time slots from a set of Y time-first time slots (e.g., by random selection) to perform LBT and transmission, where the values ​​of X and / or Y (e.g., any of the maximum value of X, the maximum value of Y, the minimum value of X, the minimum value of Y) may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). In another example, the WTRU may pre-select X time slots from a subwindow (e.g., an early subwindow from a resource selection window) to perform LBT and transmission, where the value of X and / or the size of the subwindow may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). If the WTRU fails to access the first pre-selected time slot, the WTRU may hop (e.g., continue) to a second pre-selected time slot to perform LBT and transmission. The WTRU may maintain the current LBT parameters before hopping (e.g., continuing) to the second pre-selected time slot. The WTRU may continue this process until it successfully performs LBT and transmits in one of the pre-selected time slots.

[0249] In a third option, the WTRU may use the updated LBT parameters (e.g., N) to trigger resource selection (reselection) based on LBT failure. For example, the WTRU may first pre-select a timeslot to perform LBT and transmission. If the WTRU fails to access the pre-selected timeslot, the WTRU may trigger resource selection (reselection) based on LBT failure by determining a set of available timeslots for performing LBT and transmission based on any one of the updated LBT parameters (e.g., maintaining the current value of N), the resource selection window, and the QoS of the TB (e.g., the remaining PDB). The WTRU may pre-select another timeslot to perform LBT and transmission. The WTRU may continue to perform the process until it successfully performs LBT and transmission in one of the pre-selected timeslots.

[0250] WTRU determines the primary RB set The WTRU may determine a primary RB set (eg, for type BLBT) based on one or any combination of the following five examples, for example, among multiple RB sets.

[0251] In a first example, the WTRU may determine the primary RB set based on the CBR of each RB set (e.g., of the multiple RB sets). For example, the WTRU may select the RB set that satisfies a condition (e.g., having the lowest CBR) as the primary RB set. For example, the WTRU may select the RB set that has a CBR less than a (pre-)configured threshold as the primary RB set.

[0252] In a second example, the WTRU may determine the primary RB set based on the WTRU's channel occupancy ratio (CR) (eg, satisfying a condition). For example, the WTRU may select the RB set with the lowest CR of the WTRU as the primary RB set.

[0253] In a third example, the WTRU may determine the primary RB set based on the number of its reserved resources (eg, satisfying a condition) in the window. For example, the WTRU may select the RB set with the minimum / maximum number of reserved resources in the window as the primary RB set.

[0254] In a fourth example, the WTRU may determine the RB set based on the number of resources transmitted in the past (eg, satisfying a condition). For example, the WTRU may select the RB set with the minimum / maximum number of transmitted resources in the window as the primary RB set.

[0255] In a fifth example, the WTRU may determine the primary RB set based on the number of available resources / time slots (e.g., satisfying a condition). For example, the WTRU may select the RB set with the maximum number of available resources / time slots in a window (e.g., a resource selection window) as the primary RB set.

[0256] WTRU determines the switch primary RB set The WTRU may trigger the primary RB set (e.g., for Type B LBT) based on one or any combination of the following events (e.g., conditions being met): The WTRU performs resource selection (reselection); The WTRU is not performing LBT; The WTRU has not performed LBT for a (e.g., pre-)configured number of consecutive times; The WTRU fails to access the channel after a certain period of time The CBR of the primary RB set becomes larger than a (eg pre-)configured threshold; and • The CBR of the other RB set becomes smaller than the CBR of the primary RB set by a (eg pre-)configured offset.

[0257] WTRU procedures after single channel resource allocation without LBT to access the channel in wideband In one embodiment, in wideband operation, the WTRU may not perform LBT to access the channel before the selected resources in one RB set for performing single-band transmission. The WTRU may perform one or any combination of the following four options.

[0258] In a first option, the WTRU may continue to perform LBT in subsequent available resources in the same RB set. The WTRU may maintain the updated LBT parameters (eg, N) to perform LBT in subsequent time slots.

[0259] In a second option, the WTRU may jump to the next pre-selected timeslot, which may be in the same or different set of RBs as compared to the first pre-selected resource. For example, the WTRU may pre-select a certain number of available resources (e.g., a certain number) in which to perform LBT and transmission. The set of pre-selected resources may be a set of available resources from a subwindow (e.g., the earliest subwindow from the resource selection window) or selected (e.g., randomly) from a set of X temporally earliest resources. In one embodiment, the WTRU may maintain a set of LBT parameters for all RB sets. The WTRU may use the updated LBT parameters (e.g., N) to access the channel in the next pre-selected resource. In another embodiment, the WTRU may use independent LBT parameters for each RB set.

[0260] In a third option, the WTRU may hop to the next pre-selected timeslot. For example, the WTRU may pre-select X resources (e.g., by random selection) from a set of Y time-first timeslots to perform LBT and transmission, where the values ​​of X and / or Y (e.g., any of the maximum of X, the maximum of Y, the minimum of X, the minimum of Y) may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). The X and Y resources may be located in all (e.g., any) RB sets. In another example, the WTRU may pre-select X resources from a subwindow (e.g., an early subwindow from a resource selection window) to perform LBT and transmission, where the value of X and / or the size of the subwindow may be (e.g., pre-)configured based on the QoS of the TB (e.g., any of the remaining PDBs, the priority). If the WTRU fails to access the first pre-selected timeslot, the WTRU may hop to a second pre-selected timeslot to perform LBT and transmission. In one approach, the WTRU may maintain one set of LBT parameters for all RB sets. The WTRU may use the updated LBT parameters (eg, N) to access the channel in the next pre-selected resource. In another approach, the WTRU may maintain independent LBT parameters for each RB set.

[0261] In a fourth option, the WTRU may use the updated LBT parameters (e.g., N) to trigger resource selection (reselection) based on LBT failure. For example, the WTRU may first pre-select a resource to perform LBT and transmission. If the WTRU fails to access the pre-selected resource, the WTRU may trigger resource selection (reselection) based on LBT failure by determining a set of available resources for performing LBT and transmission based on any one of the updated LBT parameters (e.g., maintaining the current value of N), the resource selection window, and the QoS of the TB (e.g., the remaining PDB). The WTRU may pre-select another resource to perform LBT and transmission. The WTRU may continue to perform the process until it successfully performs LBT and transmission in one of the pre-selected resources.

[0262] WTRU determines consistent LBT failure In one embodiment, the WTRU may maintain consistent (e.g., permanent, repetitive) LBT failure per RB set. In another embodiment, the WTRU may maintain consistent (e.g., permanent, repetitive) LBT failure per resource pool, which may include one or more RB sets. The WTRU may determine an LBT failure event (e.g., to be indicated to upper layers) based on any of the following: (i) the WTRU did not perform LBT to access a pre-selected resource; (ii) the WTRU did not perform LBT to access a pre-selected time slot; (iii) the WTRU did not perform LBT to transmit a TB; (iv) the WTRU did not receive HARQ ACK feedback for the TB; (v) the WTRU did not receive HARQ feedback for the transmission of the TB.

[0263] The WTRU determines which CAPC to use to access the channel In one embodiment, the WTRU may determine which CAPC to use to access the channel based on any of the following: (i) the amount of data in each LCH and / or the amount of data associated with each CAPC; (ii) the CBR of the resource pool; and (iii) the maximum amount of data that can be transmitted in each COT, which may be associated with the CAPC associated with the COT.

[0264] For example, Fig.14As shown in , the WTRU may determine to use CAPC1 to access the channel for a first case of the buffer status as shown at 1410, and the WTRU may determine to use CAPC3 to access the channel for a second case of the buffer status as shown at 1420. For example, the buffer status of LCH1 in the first case may be full, and the WTRU may use CAPC1 to transmit data (e.g., only) in LCH1. For example, the buffer status of the three LCHs in the second case may be low, and the WTRU may use CAPC3 to access the channel and transmit the entire data in one COT.

[0265] WTRU changes transmission bandwidth during COT duration In one embodiment, the WTRU may perform wideband transmissions in a set of acquired RB sets when initiating a multi-channel COT. The WTRU may determine to change the bandwidth of its transmission by dropping one or more RB sets, and may continue to perform PSCCH / PSSCH transmissions in a smaller bandwidth (e.g., a subset of the acquired RB sets). The WTRU may allow other WTRUs to share a subset of the RB sets. The WTRU may give other WTRUs (e.g., instructions) (e.g., transmit information) to share a subset of the RB sets (e.g., via SCI and / or MAC CE of the PSCCH / PSSCH in the COT). The WTRU may determine to reduce its transmission bandwidth based on one or any combination of the following three examples of conditions.

[0266] In a first example of a condition, the WTRU may determine to reduce its transmission bandwidth based on the WTRU detecting another WTRU reserving a subset of a set of RBs in its wideband COT.

[0267] In a second example of a condition, the WTRU may determine to reduce its transmission bandwidth based on the WTRU's CR being greater than a (eg, pre-)configured threshold.

[0268] In a third example of a condition, the WTRU may determine to reduce its transmission bandwidth based on the WTRU's buffer status being less than a (e.g., pre-)configured threshold. For example, if the WTRU does not have enough data to justify transmitting in wideband operation, the WTRU may reduce its transmission bandwidth for one or more remaining transmissions in the COT.

[0269] The WTRU determines in which time slot to perform LBT and transmit for multiple consecutive time slots.In one embodiment, the WTRU may be (e.g., pre) configured to perform resource selection for a multi-contiguous time slot transmission (MCSt) of N consecutive time slots (N is an integer). The WTRU may determine in which time slot to start LBT and transmission based on a time slot set having at least N adjacent available time slots. In one embodiment, the WTRU may select (e.g., a certain) number of time slots (e.g., X% of the time slots) in a subwindow (e.g., the earliest subwindow in the resource selection window). The WTRU may select (e.g., randomly) a time slot in which to perform LBT and transmission. In another approach, the WTRU may select a certain number of the earliest available time slots in time (e.g., X time slots). The WTRU may then (e.g., randomly) select one of the X time slots in which to perform LBT and transmission.

[0270] The WTRU determines in which time slot to perform LBT and transmit after a transmission in a COT In another embodiment, the WTRU may successfully acquire a COT and perform a transmission in the COT. After successfully transmitting in the COT, in one embodiment, the WTRU may determine in which time slot after the COT to perform LBT and transmission based on one of the reserved time slots in the previous COT. Specifically, in the current COT, the WTRU may reserve another COT in the resource selection window. The WTRU may then perform LBT and transmission in the next reserved COT. In another scenario, after the WTRU may have completed the transmission in the COT, it may trigger resource selection (reselection).

[0271] Method for network-assisted resource allocation WTRU requests sidelink resources In some embodiments, the WTRU may request sidelink resources from the network.The WTRU may implicitly / explicitly indicate one or more of the following information to the network.

[0272] In a first example, the WTRU may either implicitly or explicitly indicate one or more LBT parameters, such as any of a contention window and an initialized backoff time, for accessing a channel in a past and / or future transmission (eg, a next transmission).

[0273] In a second example, the WTRU may either implicitly or explicitly indicate information associated with the intended transmission of a TB, such as any of the QoS of the data, the TB size, the modulation and coding scheme (MCS), and the number of transmissions for the TB.

[0274] A WTRU may explicitly indicate any of the pieces of information described herein by transmitting explicit information indicating the piece of information. A WTRU may implicitly indicate any of the pieces of information described herein by transmitting another piece of information associated with the (eg, implicitly indicated) piece of information.

[0275] WTRU receives sidelink grant from network The WTRU may receive scheduling information from the network, which may include one or any combination of the following information.

[0276] In a first example, the scheduling information may indicate resources for one or more LBT subbands, which may include any of a frequency and a duration of resources in each LBT subband. In one approach, the WTRU may receive sidelink grant information with a fixed timing offset and duration. In another approach, the WTRU may receive sidelink grant information as a sliding window with a flexible offset and a fixed duration. For example, the WTRU may receive the sidelink grant information in a window of an offset and a fixed duration (e.g., four time slots). The WTRU may acquire a channel for four time slots whenever it can successfully perform LBT.

[0277] In a second example, the scheduling information may indicate one or more LBT parameters for accessing the channel.

[0278] In a third example, the scheduling information may indicate a transmission duration for the last transmission of the COT.

[0279] In a fourth example, the scheduling information may indicate UL feedback resources, which may be used to report LBT and / or transmission results. For example, the WTRU may receive downlink control information (DCI) to indicate PUSCH resources to report resource usage status of the scheduled sidelink grant. The WTRU may use either MAC CE and RRC messages to report the resource usage status to the network. In another example, the WTRU may receive DCI (e.g., the same DCI that schedules the sidelink resources) to indicate physical uplink control channel (PUCCH) resources to report resource usage status of the scheduled sidelink grant. The WTRU may use uplink control information (UCI) (e.g., HARQ) to report resource usage status of the scheduled sidelink grant.

[0280] The WTRU reports (e.g., triggers) the UCI and / or MAC CE to the network The WTRU may trigger reporting the result of the LBT and / or transmission in a scheduled sidelink grant from the network (e.g., sending feedback information indicating it). In one approach, the WTRU may trigger sending feedback information such as, for example, a Scheduling Request (SR) to the network (e.g., only). In another approach, the WTRU may trigger sending UCI (e.g., SR) and MAC CE (e.g., SL Buffer Status Report (SLBSR)) (e.g., both) to the network.

[0281] The WTRU (e.g., triggers) to send UCI to the network In one approach, the WTRU may be (e.g., pre-)configured with UCI resources (e.g., a dedicated SR for indicating the status of resource usage in a scheduled sidelink grant) to indicate the LBT and / or transmission status related to the scheduled sidelink grant to the network. For example, the WTRU may be (e.g., pre-)configured with conditions that trigger sending UCI (e.g., SR) related to LBT and / or transmission. The conditions that trigger sending UCI (e.g., SR) may be based on one or any combination of the following four examples.

[0282] In a first example, the condition for sending UCI (e.g., SR) may be based on the number / percentage of acquired LBT subbands relative to the scheduled LBT subbands. In one example, the WTRU may be scheduled with sidelink resources in two LBT subbands. For example, if the WTRU fails to acquire one or both of the LBT subbands, it may trigger (e.g., send) an SR to the network. In another example, the WTRU may trigger (e.g., send) an SR to the network only if it fails to acquire both LBT subbands.

[0283] In a second example, the condition for sending UCI (e.g., SR) may be based on the number / percentage of acquired timeslots relative to the number of scheduled timeslots. In one example, the WTRU may be scheduled with sidelink resources in two LBT subbands spanning 4 timeslots. If the WTRU fails to acquire one or both LBT subbands after two timeslots, it may trigger (e.g., send) an SR to the network.

[0284] In a third example, the condition for sending UCI (e.g., SR) may be based on the number / percentage of resources transmitted relative to the scheduled resources. In one example, the WTRU may be scheduled with sidelink resources in two LBT subbands spanning 4 time slots. If the WTRU fails to acquire 50% of the total scheduled sidelink resources, it may trigger (e.g., send) an SR to the network.

[0285] In a fourth example, the condition for sending UCI (e.g., SR) may be based on the remaining data in the buffer satisfying a further condition. For example, if the WTRU still has data with a priority and / or latency that satisfies a threshold, the WTRU may trigger UCI (e.g., SR).

[0286] The threshold for the number / percentage of acquired LBT subbands, timeslots and / or resources used to trigger the sending of UCI and / or MAC CE may be either (e.g., pre-)configured and dynamically indicated to the WTRU (e.g., via DCI).

[0287] The WTRU triggers the sending of a MAC CE to the network In some embodiments, the WTRU may trigger sending feedback information such as, for example, a MAC CE (e.g., SL-BSR) and / or an RRC message (e.g., WTRUAssistantInformation) to indicate the resource usage status (e.g., any of LBT and transmission status, buffer status of the WTRU) following the scheduled sidelink resources. The gNB may then know the amount of data that the WTRU may have transmitted in the scheduled grant (e.g., based on the scheduled grant). The WTRU may be (e.g., pre-)configured with one or more conditions that trigger sending a MAC CE and / or RRC message to send such an indication. The conditions may be based on one or any combination of the following three examples.

[0288] In a first example, the condition for sending feedback information indicating resource usage status (e.g., SL-BSR) may be based on the remaining buffer of the WTRU and / or the remaining buffer of the WTRU having a QoS that satisfies the condition. For example, if the WTRU still has data with a priority and / or latency that satisfies a threshold, the WTRU may trigger sending a MAC CE (e.g., SLBSR).

[0289] In a second example, the conditions for sending feedback information indicating resource usage status (e.g., SL-BSR) can be based on the amount / percentage of transmission and / or the amount / percentage of resources / LBT subbands used in the scheduled sidelink grant.

[0290] In a third example, the condition for sending feedback information indicating resource usage status (e.g., SL-BSR) may be based on whether an SR may have been sent. For example, if an SR associated with the resource usage status of the scheduled sidelink grant is sent, the WTRU may trigger sending a MAC CE (e.g., SLBSR).

[0291] WTRU sends HARQ feedback to report resource usage In one approach, the WTRU may send feedback information such as, for example, 1-bit HARQ feedback in the PUCCH to report the transmission status of the scheduled sidelink grant. In another approach, the WTRU may send a HARQ codebook in the PUCCH to send multi-bit HARQ feedback. In the codebook, the WTRU may use 1 bit to report the status of one scheduled LBT subband. The number of bits in the HARQ codebook used for one scheduling may be a function of the number of LBT subbands (e.g., pre-)configured in the resource pool. In the case where the WTRU sends 1-bit HARQ feedback, the WTRU may determine whether to send ACK or NACK based on any of the following: (i) the number / percentage of the acquired LBT subbands relative to the scheduled LBT subbands; (ii) the number / percentage of the acquired time slots relative to the number of scheduled time slots; and (iii) the number / percentage of the transmitted resources relative to the scheduled resources.

[0292] For example, if the number / percentage of acquired LBT subbands, time slots, and / or resources is greater than or equal to a threshold, the WTRU may send (e.g., positive) ACK feedback. Otherwise, the WTRU may send (e.g., negative) NACK feedback. The threshold for the number / percentage of acquired LBT subbands, time slots, and / or resources for feedback ACK / NACK may be either pre-configured or dynamically indicated to the WTRU (e.g., via DCI).

[0293] In the case of a HARQ codebook where the WTRU sends N bits of information, 1 bit may be associated with one scheduled LBT subband. The WTRU may determine whether to send an ACK or a NACK for each LBT subband based on any of the following: (i) the number / percentage of time slots acquired in each LBT subband relative to the number of scheduled time slots; and (ii) the number / percentage of resources transmitted in each LBT subband relative to the number of scheduled resources.

[0294] For example, if the number / percentage of acquired timeslots and / or resources in each LBT subband is greater than or equal to a threshold, the WTRU may send (e.g., positive) ACK feedback. Otherwise, the WTRU may send (e.g., negative) NACK feedback for each LBT subband. The threshold for the number / percentage of acquired LBT subbands, timeslots, and / or resources for feedback ACK / NACK may be either (e.g., pre-)configured and dynamically indicated to the WTRU (e.g., via DCI).

[0295] The WTRU may be configured to trigger sending UCI (e.g., indicating SR) and / or MAC CE (e.g., indicating SL-BSR) to the network based on whether PUCCH is available in the sidelink scheduling DCI. For example, if PUCCH for reporting HARQ status (e.g., ACK / NACK) is not included in the sidelink scheduling DCI (e.g., DCI format 3_0), the WTRU may trigger sending UCI and / or MAC CE if the number (e.g., or percentage) of acquired time slots and / or resources meets a condition (e.g., is less than a (e.g., pre-)configured threshold). Otherwise, if the sidelink scheduling DCI includes (e.g., indicates) PUCCH resources for reporting HARQ status, the WTRU may not trigger sending UCI and / or MAC CE, for example regardless of the LBT state in the sidelink.

[0296] Embodiments are described herein with respect to examples of ratios between a subset of acquired (e.g., transmitted) resources relative to a set of scheduled resources. Embodiments described herein are not limited to ratios, but are compatible with any function of acquired (e.g., transmitted) resources and scheduled resources for transmitting feedback information (e.g., including any of HARQ ACK, HARQ NACK, SR, and SL-BSR).

[0297] Method for guard band usage The WTRU determines its transmission scheme in an LBT subband The WTRU may acquire one LBT subband. The WTRU may perform one or any combination of the following three examples of transmission schemes in one LBT subband.

[0298] In a first example of a transmission scheme, the WTRU may not use a guard band.

[0299] In a second example of a transmission scheme, the WTRU may use a portion of the guard band (eg, half of the guard band) in one transmission of a TB.

[0300] In a third example of a transmission scheme, the WTRU may use the entire guard band between two adjacent LBT subbands.

[0301] The WTRU determines its transmission scheme in multiple contiguous LBT subbands The WTRU may acquire two contiguous LBT subbands. The WTRU may perform one or any combination of the following transmission schemes related to guard band usage.

[0302] In one transmission scheme, the WTRU may perform two transmissions of the same TB, where each transmission may be within its LBT subband and the guard band resources may not be used by any transmission.

[0303] In another transmission scheme, the WTRU may perform two transmissions of the same TB, where each transmission may be within its LBT subband, where one of the two transmissions may occupy all or part of the guard band and the other transmission may not use the guard band.

[0304] In another transmission scheme, the WTRU may perform two transmissions of the same TB, where each transmission may be within its LBT subband and each transmission may occupy a portion (e.g., half) of the guard band.

[0305] In another transmission scheme, the WTRU may perform one transmission of a TB across two LBT subbands. In some embodiments, the WTRU may not use the guard band. In other embodiments, the WTRU may use a portion of the LBT subband. In yet other embodiments, the WTRU may use the entire guard band.

[0306] In another transmission scheme, the WTRU may perform two transmissions of different TBs, where each transmission may be within its LBT subband and the guard band resources may not be used by any transmission.

[0307] In another transmission scheme, the WTRU may perform two transmissions of different TBs, where each transmission may be within its LBT subband. One of the two transmissions may occupy all or part of the guard band and the other transmission may not use the guard band.

[0308] In another transmission scheme, the WTRU may perform two transmissions of different TBs, where each transmission may be within its LBT subband and each transmission may occupy a portion (e.g., half) of the guard band.

[0309] The WTRU indicates the transmission scheme and guard band usage for one or more LBT subbands A WTRU may indicate (e.g., transmit information) to another node (e.g., receiver WTRU(s)) its transmission scheme and / or guard band usage in one and / or multiple LBT subbands (e.g., indication). In one aspect, the indication may be communicated (e.g., included) in an SCI associated with one or more transmissions. In another aspect, the indication may be communicated (e.g., transmitted) using a higher layer message (such as, for example, any of NAS, PC5 RRC, and MAC CE). For example, the WTRU may use one or more SCIs (e.g., second stage SCIs) associated with one or more transmissions of one or more TBs to indicate the transmission scheme and / or guard band usage of one or more TBs in a timeslot. For example, the WTRU may transmit information indicating one or any combination of the following two examples.

[0310] In a first example, the WTRU may transmit information indicating whether the WTRU uses a timeslot to transmit one or more TBs. For example, the information may indicate, for a TB transmitted in a timeslot, whether the TB spans multiple LBT subbands or each transmission is within one LBT subband.

[0311] In a second example, the WTRU may transmit information indicating whether a guard band is used in a timeslot and / or whether a transmission uses a guard band and / or bandwidth usage of the guard band (eg, full guard band or portion of the guard band).

[0312] exist Fig.15 In one example shown in , the WTRU may perform one of four transmission schemes and guard band usage for one TB transmitted simultaneously in two adjacent subbands and one of three transmission schemes and guard band usage for two TBs transmitted in the same time slot, where one TB may be associated with the transmission in the diagonally shaded rectangle shown at 1511 and the other TB may be associated with the transmission in the horizontally shaded rectangle shown at 1512.

[0313] The WTRU determines whether to use the guard band for its transmission In some embodiments, the WTRU may acquire two or more adjacent LBT subbands. The WTRU may determine a transmission scheme. The WTRU may determine whether to use a guard band and / or the bandwidth of the guard band for each transmission between two LBT subbands. The transmission scheme and guard band usage may be determined based on one or any combination of the following four examples.

[0314] In a first example, the transmission scheme and guard band usage may be determined based on a (e.g., pre-) configuration in a resource pool. For example, the WTRU may be (e.g., pre-) configured in a resource pool whether to use a guard band between two adjacent LBT subbands. The WTRU may follow the (pre-) configuration in the resource pool.

[0315] In a second example, the transmission scheme and guard band usage may be determined based on an indication from the network. For example, the WTRU may receive a broadband sidelink grant from the network. The WTRU may receive an indication from the network regarding which transmission scheme to use and / or whether to use a guard band. The WTRU may determine the transmission scheme and guard band usage based on an indication from the network.

[0316] In a third example, the transmission scheme and guard band usage may be determined based on whether the WTRU initiates a COT or shares a COT with other WTRUs. For example, if the WTRU shares a COT with another WTRU, it may determine that the guard band is not applicable. For example, if the WTRU shares a COT with another WTRU, the WTRU may use a transmission scheme in which each transmission may be within the LBT subband.

[0317] In a fourth example, the transmission scheme and guard band usage may be determined based on the order of transmissions in the COT (e.g., whether the WTRU transmits the first one or several TBs in the COT or the last several TBs in the COT). For example, the WTRU may use one transmission scheme for the first N slots and / or M TBs of the COT (e.g., each transmission may be within the LBT subband). For example, the WTRU may use another transmission scheme for transmissions after the first N slots and / or after the first M TBs (e.g., one transmission of a TB spans multiple LBT subbands). M may be fixed to 1 TB and N may be (e.g., pre-)configured and / or determined based on the processing capability of the WTRU. In another example, the WTRU may not use guard bands for the first N slots and / or M TBs of the COT. Alternatively, the WTRU may use guard bands for the first N slots and / or slots after the M TBs. M may be fixed to 1 TB and N may be (e.g., pre-)configured and / or determined based on the processing capability of the WTRU.

[0318] The WTRU determines whether to use the guard band based on the transmission scheme The WTRU may determine whether to use a guard band and / or the bandwidth of the guard band for transmission based on the WTRU's transmission scheme. For example, if one transmission of a TB spans across two LBT subbands, the WTRU may use the guard band. Alternatively, if each transmission of a TB is within one LBT bandwidth, the WTRU may not use the guard band. For example, if the WTRU performs transmissions of different TBs in a time slot, the WTRU may not use the guard band.

[0319] Method for SCI decoding reduction The WTRU determines which set of RBs to decode the SCI In one embodiment, the WTRU may determine which RB sets to decode SCI and / or which RB sets to prioritize SCI decoding based on any of the following: (i) an indication received from another network element (such as, for example, another WTRU, a peer WTRU of a unicast session, a gNB, etc.); (ii) RSSI measurement results and SCI decoding status; and (iii) (e.g., pre-)configured priority of (e.g., each) RB set.

[0320] In a first example, the WTRU may determine which RB sets to decode SCI and / or which RB sets to prioritize SCI decoding based on an indication that may be received from another network element (e.g., another WTRU, a peer WTRU of a unicast session, a gNB, etc.). In one example, the WTRU may be (e.g., pre-)configured with one (e.g., default) RB set to perform broadcast communications. The WTRU may establish a unicast session with another WTRU. The other WTRU may send information to the WTRU indicating a request to communicate in another set of RB sets. The WTRU may perform sensing and decoding SCI in a set of RB sets indicated by the peer WTRU. In another example, the other WTRU may indicate (e.g., send information indicating the congestion level) associated with transmission activities of other technologies (e.g., Wi-Fi) in one RB set. If the indicated congestion level (e.g., CBR) satisfies a condition (e.g., is greater than a (e.g., pre-)configured threshold), the WTRU may stop decoding SCI in that RB set. If the indicated congestion level (e.g., CBR) fails to satisfy the condition (e.g., is less than a (e.g., pre-)configured threshold), the WTRU may continue to decode the SCI. In another example, the WTRU may determine its SCI decoding behavior in a set of RBs based on an indication that may be received from another WTRU. For example, if the CBR (e.g., associated with transmission activity of other technologies) satisfies the condition (e.g., is greater than a (e.g., pre-)configured) threshold, the WTRU may reduce its SCI decoding periodicity (e.g., the WTRU may decode the SCI every N time slots, N being an integer). Otherwise (e.g., if the CBR is less than a threshold), the WTRU may decode the SCI, for example, every time slot / mini-slot.

[0321] In a second example, the WTRU may determine which RB sets to decode SCI and / or which RB sets to prioritize SCI decoding based on either the RSSI measurement results and the SCI decoding status. For example, if the RSSI measured in a certain period meets a first condition (e.g., greater than a (e.g., pre-)configured threshold) and if the number of decoded SCIs in the certain period meets a second condition (e.g., less than a (e.g., pre-)configured threshold), the WTRU may reduce the SCI decoding periodicity.

[0322] In a third example, the WTRU may determine which RB sets to decode SCI and / or which RB sets to prioritize SCI decoding based on a (e.g., pre-)configured periodicity for (e.g., each) RB set. For example, the WTRU may be (e.g., pre-)configured with priority decoding for (e.g., each) RB set. The WTRU may sequentially prioritize which RB sets to decode SCI based on the associated priority of the SCI decoding for (e.g., each) RB set.

[0323] The TxWTRU determines the number of symbols used for automatic gain control (AGC) purposes In one embodiment, for transmission in the first starting symbol of a time slot having multiple starting symbols, the WTRU may determine whether to use one or two symbols for automatic gain control (AGC) based on the number of (one or more) RB sets configured in the resource pool and the bandwidth of the transmission.

[0324] For example, the WTRU may be (e.g., pre-)configured with multiple starting symbols for PSCCH / PSSCH transmissions. If the WTRU transmits from the first symbol of a slot, it may determine the number of symbols used for AGC purposes. The WTRU may indicate (e.g., in the SCI) the number of AGC symbols used for its PSCCH / PSSCH transmissions, which may be used to support the Rx WTRU in decoding the transmission. For example, if the WTRU uses a symbol for AGC, the WTRU may repeat the same bit for subsequent symbols. In one approach, the Tx WTRU may determine the number of symbols used for AGC purposes. In another approach, the Rx WTRU may determine the number of AGC symbols to monitor. The number of symbols used for AGC may be determined based on any of the following: (i) the number of RG sets (e.g., pre-)configured in a resource pool; (ii) whether the PSCCH / PSSCH transmission spans a resource pool; and (iii) whether FDM is allowed for transmissions starting from the middle of a slot (e.g., not starting from the beginning of a slot).

[0325] In a first example, the WTRU may determine the number of symbols used for AGC based on the number of RB sets (e.g., pre-)configured in the resource pool. For example, if one RB set is (e.g., pre-)configured in the resource pool, the WTRU may include (or monitor) one symbol for AGC purposes. If multiple (e.g., more than one) RB sets are (e.g., pre-)configured in the resource pool, the number of AGC symbols may be equal to the (e.g., pre-)configured number of starting symbols in the slot.

[0326] In a second example, the WTRU may determine the number of symbols based on whether the PSCCH / PSSCH transmission spans (e.g., the entire) resource pool. For example, if the PSCCH / PSSCH transmission spans (e.g., the entire) resource pool, the WTRU may include (or monitor) one AGC symbol. Otherwise (e.g., if the PSCCH / PSSCH transmission does not span (e.g., the entire) resource pool (e.g., if the PSCCH / PSSCH transmission is localized in a set of contiguous resources of the resource pool)), the WTRU may include (or monitor) multiple (e.g., more than one) AGC symbols (e.g., the number of AGC symbols may be equal to the (e.g., pre-)configured number of starting symbols in the time slot).

[0327] In a third example, the WTRU may determine the number of symbols used for AGC based on whether FDM is allowed for transmissions starting from the middle of a slot (e.g., not starting from the beginning of a slot). For example, if FDM is not allowed for transmissions starting from the middle of a slot, the WTRU may include (or monitor) one AGC symbol. Otherwise, the WTRU may include (or monitor) multiple (e.g., more than one) AGC symbols (e.g., the number of symbols used for AGC purposes may be equal to the (e.g., pre-)configured number of starting symbols in a slot).

[0328] Example of WTRU performing LBT subband reselection In one embodiment, the WTRU may select a p less than a threshold, the number of available time slots for LBT in the resource selection window (RSW) is greater than a threshold) to determine whether to keep the current LBT subband or reselect another LBT subband to perform LBT (e.g., type 1 LBT for multi-channel access). If the conditions for switching to another LBT subband are met, the WTRU may switch to the LBT subband that meets the conditions (e.g., the LBT subband with the highest number of available time slots, the LBT subband with the lowest CW p More specifically, the WTRU may perform the following steps for the LBT subband reselection process.

[0329] In a first step, the WTRU may be (e.g., pre-)configured with one or more conditions (e.g., parameters) for reselecting an LBT subband to perform LBT and / or transmission. The one or more conditions (e.g., parameters) may include any of a contention window threshold, an initialized backoff threshold, and a threshold on the number of available slots in an RSW.

[0330] In a second step, the WTRU may be (e.g., pre-)configured with one or more conditions for selecting another LBT subband. The one or more conditions may include the LBT subband with the highest number of available time slots and the LBT subband with the lowest CW.p Any one of the LBT sub-bands.

[0331] In the third step, for example when a TB arrives, the WTRU may determine whether the LBT subband reselection conditions are met.

[0332] In the fourth step, if the LBT subband reselection condition is not met, the WTRU may perform LBT and / or transmission in the current LBT subband. Otherwise, the WTRU may determine an LBT subband that satisfies the LBT subband reselection condition and may perform LBT and / or transmission in the determined LBT subband.

[0333] Example of WTRU reporting LBT and / or transmission status of scheduled broadband resources In one embodiment, the WTRU may receive a sidelink grant in multiple LBT subbands. The WTRU may perform (e.g., simultaneously) initial and blind retransmissions for TBs in the set of acquired LBT subbands in a timeslot and may indicate such transmission scheme in the SCI. The WTRU may determine whether to report an ACK / NACK to the network based on the number of acquired LBT subbands and / or the number of transmissions made in the scheduled grant. For example, the WTRU may perform the following procedure for Mode 1 resource allocation in the wideband sidelink unlicensed spectrum.

[0334] In a first step, the WTRU may be (eg, pre-)configured with the percentage of acquired LTB subbands for 1-bit ACK / NACK feedback for the scheduled wideband resources.

[0335] In a second step, the WTRU may receive sidelink grant information for resource usage scheduled for feedback (eg, 1-bit feedback) across multiple LBT subbands and UL resources.

[0336] In a third step, the WTRU may perform LBT on the set of scheduled LBT subbands and may obtain a subset of LBT subbands for which LBT was successful (eg, subbands determined to be clear).

[0337] In a fourth step, the WTRU may perform (eg, simultaneously) initial transmission and blind retransmission in the acquired set of LBT subbands, and may indicate (eg, simultaneously) the set of transmitted LBT subbands in the SCI.

[0338] In the fifth step, the WTRU may determine whether to report ACK or NACK to the network based on the number of acquired LBT subbands.

[0339] Example of guard band usage In an embodiment, if the WTRU acquires two contiguous LBT subbands associated with a guard band, it may determine whether to use the guard band for wideband operation based on the transmission scheme of the TB (e.g., whether the TB spans across multiple LBT subbands or whether each transmission of the TB is within one LBT subband) and the transmission time slot in the COT. The WTRU may indicate (e.g., in the SCI) its transmission scheme and whether the guard band is used. For example, the WTRU may perform the following steps.

[0340] In a first step, the WTRU may determine a set of LBT subbands for performing LBT and (eg, potential) transmission.

[0341] In the second step, the WTRU may perform LBT in a set of LBT subbands and may acquire a subset of LBT subbands.

[0342] In the third step, for each time slot in the acquired COT, the WTRU may determine one of the following transmission schemes: (i) each transmission of the TB may span across the acquired LBT subbands; or (ii) each transmission of the TB may be within one LBT subband.

[0343] In a fourth step, the WTRU may determine whether to use any guard bands within the set of LBT subbands based on: (1) whether it acquires two contiguous LBT subbands; (2) the selected transmission scheme; and (3) the time slots in the COT in which it may perform transmissions. For example, if the WTRU performs transmissions across TBs of acquired contiguous LBT subbands, it may use guard bands. Otherwise, it may not use guard bands.

[0344] In a fifth step, the WTRU may perform transmissions in the acquired subset of LBT subbands and may indicate its transmission scheme and whether guard bands may be used (eg, in the SCI).

[0345] Example method for reselecting LBT subbands Fig.16 1 is a diagram illustrating an example method 1600 for reselecting an LBT subband to be used for wideband sidelink transmission in an unlicensed spectrum. The method 1600 may be implemented in a WTRU. As shown at 1610, the WTRU may determine whether a first condition for reselection of an LBT subband exists on a first subband currently selected by the WTRU for transmission. As shown at 1620, if the condition does not exist, the WTRU may perform LBT on the first subband. As shown at 1630, if the condition exists, the WTRU may select a second subband for wideband sidelink transmission in the unlicensed spectrum, and the WTRU may perform LBT on the second subband.

[0346] In various embodiments, the first condition may be that when the first subband satisfies a threshold, a contention window (CW p ) size.

[0347] In various embodiments, selecting the second sub-band for wideband sidelink transmission in the unlicensed spectrum may include selecting a sub-band having a highest number of available time slots.

[0348] In various embodiments, selecting the second subband for broadband sidelink transmission in the unlicensed spectrum may include selecting a subband having the lowest CW p sub-band.

[0349] In various embodiments, the WTRU may include a processor, a receiver, a transmitter, and a memory to implement the method 1600.

[0350] Example Methods for Wideband Sidelink Transmission in Unlicensed Spectrum Fig.17 is a diagram illustrating an example method 1700 for wideband sidelink transmission in an unlicensed spectrum. The method 1700 may be implemented in a WTRU. As shown at 1710, the WTRU may determine a plurality of LBT subbands on which to perform LBT operations. As shown at 1720, the WTRU may perform (e.g., perform) LBT operations on the determined plurality of LBT subbands. As shown at 1730, based on the LBT operations, the WTRU may acquire a subband set for a time period (e.g., a channel occupancy time or COT) for data transmission, the set comprising a plurality of subbands. As shown at 1740, for each time slot in the acquired subband set in the COT, the WTRU may select a transmission scheme. As shown at 1750, the WTRU may determine whether two of the subbands in the subband set are adjacent in frequency. As shown at 1760, the WTRU may transmit data on a subband set using a guard band used for transmitting data if (1) the selected transmission scheme permits a TB to span multiple subbands and (2) two of the subbands in the subband set are contiguous in frequency.

[0351] In various embodiments, the selected transmission scheme may be one of: (1) a scheme in which each transmission of a TB may span a set of subbands; and (2) a scheme in which each transmission of a TB may be limited to one subband.

[0352] In various embodiments, the WTRU may transmit an indication of the selected transmission scheme to the network.

[0353] In various embodiments, the WTRU may transmit an indication to the network whether a guard band is being used to transmit data.

[0354] In various embodiments, the WTRU may include a processor, a receiver, a transmitter, and a memory to implement method 1700.

[0355] Example method for selecting resources for performing LBT Fig.18 1 is a diagram illustrating an example method 1800 for selecting resources for performing LBT for wideband sidelink transmission in an unlicensed spectrum. The method 1800 may be implemented in a WTRU. As shown at 1810, the WTRU may determine a time slot that may be reserved by another WTRU. As shown at 1820, the WTRU may determine a time slot that may be available for performing LBT based on the time slot that may be reserved by another WTRU. As shown at 1830, the WTRU may determine whether the time slot that may be reserved by another WTRU may also be available for performing LBT by determining whether the received RSSI in the transmission of the other WTRU from the reserved time slot meets a threshold. As shown at 1840, the WTRU may determine a set of time slots that may be available for LBT according to (1) time slots that may not be reserved by another WTRU and (2) time slots that may be reserved by another WTRU and for which the RSSI in the transmission of the other WTRU from the reserved time slot meets a threshold. As shown at 1850, the WTRU may prioritize the time slots in the set of time slots. As shown at 1860, the WTRU may select a time slot for performing LBT from a set of time slots based on priority.

[0356] In various embodiments, determining a set of time slots that may be available for performing LBT may include: (1) determining any time slot that may be within X time slots after a time slot that is determined to be reserved by another WTRU and corresponds to an RSSI that fails to meet a threshold as unavailable for performing LBT, where X may be an integer; and (2) determining any time slot that may be within Y time slots before a time slot that is determined to be reserved by another WTRU and corresponds to an RSSI that fails to meet a threshold as unavailable for performing LBT, where Y may be an integer.

[0357] In various embodiments, prioritization may include assigning a higher priority to a timeslot that may not be reserved by another WTRU than a timeslot that may be reserved by another WTRU.

[0358] In various embodiments, prioritization may include assigning a higher priority to a time slot that may be earlier in time than a time slot that may be later in time.

[0359] In various embodiments, determining the set of time slots available for LBT may be further based on the CAPC of the time slots determined to be reserved by another WTRU.

[0360] In various embodiments, determining a set of time slots available for LBT may include comparing the CAPC of data in a time slot determined to be reserved by another WTRU with the CAPC of the transmission data at the WTRU.

[0361] In various embodiments, the WTR may include a processor, a receiver, a transmitter, and a memory to implement method 1800 .

[0362] Example method for reporting feedback information related to SL transmission to a network Fig.19 is a diagram illustrating an example method 1900 for reporting feedback information related to SL transmissions to a network. Method 1900 may be implemented in a WTRU. As shown at 1910, the WTRU may receive scheduling information for one or more sidelink transmissions from a network, the scheduling information indicating a set of scheduled resources. As shown at 1920, the WTRU may perform LBT in the set of scheduled resources for acquiring a subset of resources in the set of scheduled resources. As shown at 1930, the WTRU may transmit sidelink control information indicating the acquired subset of resources. As shown at 1940, the WTRU may transmit data in the acquired subset of resources. As shown at 1950, the WTRU may transmit feedback information related to the one or more sidelink transmissions to the network based on the number of acquired resources and the number of scheduled resources (e.g., a ratio therebetween).

[0363] In various embodiments, the sidelink transmission of the one or more sidelink transmissions may include a sidelink control information transmission and a data transmission.

[0364] In various embodiments, the number of resources acquired may be the number of resources in the acquired subset of resources.

[0365] In various embodiments, the number of scheduled resources may be the number of resources in a set of scheduled resources.

[0366] In various embodiments, the set of scheduled resources may span any of more than one LBT subband and more than one time slot.

[0367] In various embodiments, the acquired resource subset may span more than one LBT subband.

[0368] In various embodiments, the WTRU may determine whether conditions associated with the number of acquired resources and the number of scheduled resources are satisfied.

[0369] In various embodiments, the condition may be satisfied if a ratio between the number of acquired resources and the number of scheduled resources is above a threshold.

[0370] In various embodiments, the threshold may be either: pre-configured in the WTRU and dynamically indicated in the downlink control information.

[0371] In various embodiments, if it is determined that the conditions associated with the number of acquired resources and the number of scheduled resources are satisfied, the feedback information may indicate an acknowledgement.

[0372] In various embodiments, the positive acknowledgement may include positive HARQ feedback (such as HARQ ACK).

[0373] In various embodiments, if it is determined that the conditions associated with the number of acquired resources and the number of scheduled resources are not satisfied, the feedback information may indicate any of a negative acknowledgement and a request for more resources.

[0374] In various embodiments, the request for more resources may include any of a scheduling request (SR) and a sidelink buffer status report (SLBSR).

[0375] In various embodiments, the negative acknowledgement may include negative HARQ feedback (such as, for example, HARQ NACK).

[0376] In various embodiments, the WTRU may receive configuration information indicating conditions associated with the number of acquired resources and the number of scheduled resources.

[0377] In various embodiments, the WTRU may include circuitry including a processor, a receiver, a transmitter, and a memory configured to implement method 1900 .

[0378] Example method for determining whether to maintain a current LBT subband or select another LBT subband Fig. 20 2000 is a diagram illustrating an example method 2000 for determining whether to maintain a current LBT subband or to select another LBT subband. The method 2000 may be implemented in a WTRU. As shown at 2010, the WTRU may perform a first LBT operation in a first subband. As shown at 2020, the WTRU may determine whether a first condition associated with the first LBT operation is satisfied. As shown at 2030, the WTRU may perform a second LBT operation in the first subband or in a second subband based on determining whether the first condition associated with the first LBT operation is satisfied.

[0379] In various embodiments, if it is determined that the first condition associated with the first LBT operation is satisfied, the second LBT operation may be performed in the first sub-band.

[0380] In various embodiments, if it is determined that the first condition associated with the first LBT operation is not satisfied, a second LBT operation may be performed in the second sub-band.

[0381] In various embodiments, the first condition associated with the first LBT operation may be satisfied when a first contention window value associated with the first LBT operation is less than a first threshold.

[0382] In various embodiments, the first condition associated with the first LBT operation may be satisfied when an initialized backoff value associated with the first LBT operation is less than a second threshold.

[0383] In various embodiments, the first condition associated with the first LBT operation may be satisfied when the number of available time slots in a first resource selection window associated with the first LBT operation is greater than a third threshold.

[0384] In various embodiments, the second sub-band may be selected such that the second sub-band may satisfy the second condition.

[0385] In various embodiments, the second subband may satisfy the second condition if a second contention window value associated with the second subband is less than a first contention window value associated with the first subband.

[0386] In various embodiments, the second subband may satisfy the second condition if the second subband is associated with a minimum contention window value among the plurality of contention window values.

[0387] In various embodiments, the second subband may satisfy the second condition if the number of available time slots in the second resource selection window associated with the second subband is greater than the number of available time slots in the first resource selection window associated with the first subband.

[0388] In various embodiments, the second subband may satisfy the second condition if the second subband is associated with a maximum number of available time slots in a resource selection window among the plurality of resource selection windows.

[0389] In various embodiments, the first condition and the associated first parameter may be preconfigured in the WTRU.

[0390] In various embodiments, the WTRU may receive configuration information indicating a first condition and an associated first parameter.

[0391] In various embodiments, the second condition and the associated second parameter may be pre-configured in the WTRU.

[0392] In various embodiments, the WTRU may receive configuration information indicating a second condition and an associated second parameter.

[0393] In various embodiments, the WTRU may include circuitry including a processor, a receiver, a transmitter, and a memory configured to implement the method 2000 .

[0394] Example Method for Determining Dominant LBT Sub-bands Fig.21 21 is a diagram illustrating an example method 2100 for determining a primary LBT subband. The method 2100 may be implemented in a WTRU. As shown at 2110, the WTRU may determine a plurality of channel state metrics for a plurality of LBT subbands. As shown at 2120, the WTRU may select an LBT subband from the plurality of LBT subbands as a primary LBT subband for Type B LBT based on the channel state metrics associated with the LBT subbands that meet the condition. As shown at 2130, the WTRU may perform Type B LBT operations in the plurality of LBT subbands using the selected LBT subband as the primary LBT subband.

[0395] In various embodiments, the channel state metric associated with the LBT subband may include a channel busy ratio (CBR) of the LBT subband.

[0396] In various embodiments, a channel state metric associated with the LBT subband may satisfy a condition if the CBR of the LBT subband is below a first threshold.

[0397] In various embodiments, the channel state metric associated with the LBT subband may satisfy the condition if the CBR of the LBT subband is the lowest CBR among multiple CBRs associated with the multiple LBT subbands.

[0398] In various embodiments, the channel state metric associated with the LBT subband may include a channel occupancy ratio (CR) of the WTRU for the LBT subband.

[0399] In various embodiments, the channel state metric associated with the LBT subband may satisfy the condition if the CR of the WTRU for the LBT subband is below a second threshold.

[0400] In various embodiments, the channel state metric associated with the LBT subband may satisfy the condition when the CR of the WTRU for the LBT subband is the lowest CR of the WTRU among multiple CRs associated with the multiple LBT subbands.

[0401] In various embodiments, the WTRU may include circuitry including a processor, a receiver, a transmitter, and a memory configured to implement method 2100.

[0402] Example method for selecting a time slot in a resource selection window Fig. 22is a diagram illustrating an example method 2200 for selecting a time slot in a resource selection window. The method 2200 may be implemented in a WTRU. As shown at 2210, the WTRU may determine a set of available resources in a resource selection window that is located at the beginning of the resource selection window. As shown at 2220, the WTRU may perform a first LBT operation to acquire a channel in a first resource in the set of available resources. As shown at 2230, the WTRU may determine that the first LBT operation failed to acquire a channel. As shown at 2240, the WTRU may perform a second LBT operation to acquire a channel in a second resource in the set of available resources.

[0403] In various embodiments, the set of available resources may be determined based on a configured number of available resources in a resource selection window.

[0404] In various embodiments, the configured number of available resources may be pre-configured in the WTRU.

[0405] In various embodiments, the WTRU may receive configuration information indicating a configured number of available resources.

[0406] In various embodiments, a first LBT operation may be used for transmission of a transport block, and the configured number of available resources may be a function of the QoS of the transport block.

[0407] In various embodiments, the configured number of available resources may be a function of any of one or more LBT parameters and the CBR of the resource pool.

[0408] In various embodiments, the set of available resources may be determined based on a sub-window of the resource selection window. In various embodiments, the sub-window may be of a configurable size.

[0409] In various embodiments, the configured size of the sub-window may be pre-configured in the WTRU.

[0410] In various embodiments, the WTRU may receive configuration information indicating a configured size of a sub-window.

[0411] In various embodiments, a first LBT operation may be used for transmission of a transport block, and the configured size of the sub-window may be a function of the QoS of the transport block.

[0412] In various embodiments, the configured size of the sub-window may be a function of any of one or more LBT parameters and the CBR of the resource pool.

[0413] In various embodiments, the first LBT operation may be used for an initial transmission of a transport block.

[0414] In various embodiments, the set of available resources may be selected from a plurality of LBT sub-bands.

[0415] In various embodiments, the first resource may be randomly selected from a set of available resources.

[0416] In various embodiments, the second resource may be randomly selected from the next available resource in the set of available resources.

[0417] In various embodiments, the second resource may be selected as the next available resource in the set of available resources.

[0418] In various embodiments, the WTRU may include circuitry including a processor, a receiver, a transmitter, and a memory configured to implement method 2200.

[0419] Example method for transmission in the first start symbol of a time slot having multiple start symbols Fig.23 is a diagram illustrating an example method 2300 for transmission in a first start symbol of a time slot having multiple start symbols. The method 2300 may be implemented in a WTRU. As shown at 2310, the WTRU may receive scheduling information for a sidelink transmission from a network. In various embodiments, the scheduling information may indicate a time slot having multiple start symbols. As shown at 2320, the WTRU may determine a number of symbols to be used for automatic gain control based on the number of LBT subbands in the resource pool. As shown at 2330, the WTRU may transmit a sidelink transmission using the determined number of symbols for automatic gain control.

[0420] In various embodiments, in the case where the number of LBT subbands in the resource pool is 1, the number of symbols to be used for automatic gain control may be 1.

[0421] In various embodiments, in the event that the number of LBT subbands in the resource pool is more than 1, the number of symbols to be used for automatic gain control may be equal to the number of LBT subbands in the resource pool.

[0422] In various embodiments, in the case where the number of LBT subbands in the resource pool is more than 1, the number of symbols to be used for automatic gain control may be equal to 2.

[0423] In various embodiments, the number of symbols may be further determined based on a bandwidth associated with the sidelink transmission.

[0424] In various embodiments, the number of symbols may be further determined based on whether the sidelink transmission spans across a resource pool.

[0425] In various embodiments, where the sidelink transmission spans across a resource pool, the number of symbols to be used for automatic gain control may be equal to one.

[0426] In various embodiments, where the sidelink transmission is localized in a set of contiguous resources of a resource pool, the number of symbols to be used for automatic gain control may be greater than one.

[0427] In various embodiments, the number of LBT subbands in the resource pool may be pre-configured in the WTRU.

[0428] In various embodiments, the WTRU may include circuitry including a processor, a receiver, a transmitter, and a memory configured to implement the method 2300.

[0429] Any features, variations or embodiments described with respect to the method are compatible with an apparatus including means for processing any of the disclosed methods, an apparatus including a processor configured to process any of the disclosed methods, a computer program product including program code instructions, and a non-transitory computer-readable storage medium storing the program instructions.

[0430] Although features and elements are provided in specific combinations above, it will be appreciated by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. The present disclosure is not limited in terms of the specific embodiments described in the present application, which are intended to be illustrations of various aspects. Without departing from its spirit and scope, many modifications and variations can be made, which will be obvious to those skilled in the art. The elements, actions or instructions used in the specification of the present application should not be understood as being essential or indispensable to the present invention unless so explicitly specified. In addition to those listed herein, from the above description, the functionally equivalent methods and devices within the scope of the present disclosure will be obvious to those skilled in the art. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is limited only by the items of the appended claims and the full scope of the equivalents enjoyed by such claims. It should be understood that the present disclosure is not limited to a particular method or system.

[0431] For simplicity, the above embodiments are discussed with respect to the terminology and structure of infrared-enabled devices (i.e., infrared transmitters and receivers). However, the embodiments discussed are not limited to these systems, but can be applied to other systems using other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0432] It should also be understood that the terms used herein are used only to describe specific embodiments and are not intended to be limiting. As used herein, the term "video" or the term "imagery" may mean any of a snapshot, a single image, and / or a plurality of images displayed on a time basis. As another example, when referred to herein, the term "user equipment" and its abbreviation "UE", the term "remote" and / or the term "head-mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of many embodiments of a WTRU; (iii) a wirelessly-enabled and / or wiredly-enabled device (e.g., shareable via a mobile phone) configured with, among other things, some or all of the structure and functionality of a WTRU; (iii) a wirelessly-enabled and / or wiredly-enabled device configured with less than all of the structure and functionality of a WTRU; (iv) and the like. This document is about Figures 1A to 1D Details of an example WTRU are provided that may represent any WTRU described herein. As another example, various disclosed embodiments are described above and below herein as utilizing a head mounted display. Those skilled in the art will appreciate that devices other than a head mounted display may be utilized and that some or all of the present disclosure and various disclosed embodiments may be modified accordingly without undue experimentation. Examples of such other devices may include drones or other devices configured to flow information to provide an adapted reality experience.

[0433] In addition, the method provided herein can be implemented in a computer program, software or firmware incorporated into a computer-readable medium for execution by a computer or processor. The example of a computer-readable medium includes an electronic signal (transmitted by a wired or wireless connection) and a computer-readable storage medium. The example of a computer-readable storage medium includes, but is not limited to, a read-only memory (ROM), a random access memory (RAM), a register, a cache memory, a semiconductor memory device, a magnetic medium (such as an internal hard disk and a removable disk), a magnetic-optical medium and an optical medium (such as a CD-ROM disk and a digital versatile disk (DVD)). The processor associated with the software can be used to implement a radio frequency transceiver for a WTRU, a UE, a terminal, a base station, a RNC, a MME, an EPC, an AMF or any host computer.

[0434] Variations of the methods, devices, and systems provided above are possible without departing from the scope of the present invention. In view of the various embodiments that can be applied, it should be understood that the illustrated embodiments are merely examples and should not be considered to limit the scope of the appended claims. For example, the embodiments provided herein include handheld devices that can include or be used with any suitable voltage source (such as, batteries, etc.) to provide any suitable voltage.

[0435] In addition, in the embodiments provided above, processing platforms, computing systems, controllers and other devices including processors are mentioned. These devices may include at least one central processing unit ("CPU") and memory. According to the practice of those skilled in the art of computer programming, references to symbolic representations of actions and operations or instructions may be performed by various CPUs and memories. Such actions and operations or instructions may be referred to as "being executed", "being executed by a computer" or "being executed by a CPU".

[0436] Those of ordinary skill in the art will appreciate that actions and symbolically represented operations or instructions include manipulation of electrical signals by the CPU. The electrical system represents data bits, which can cause the resulting transformation or reduction of electrical signals, and maintain the data bits at memory locations in the memory system, thereby reconfiguring or otherwise changing the operation of the CPU, as well as other processing of signals. The memory location where the data bits are maintained is a physical location with specific electrical, magnetic, optical or organic properties corresponding to or representing the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs, and other platforms and CPUs can support the provided methods.

[0437] The data bits may also be maintained on a computer-readable medium, including magnetic disks, optical disks, and any other volatile (e.g., random access memory (RAM)) or non-volatile (e.g., read-only memory (ROM)) mass storage system that can be read by a CPU. The computer-readable medium may include cooperating or interconnected computer-readable media that reside exclusively on a processing system or are distributed among multiple interconnected processing systems that may be local or remote to the processing system. It should be understood that the embodiments are not limited to the memories mentioned above, and other platforms and memories may support the provided methods.

[0438] In an illustrative embodiment, any operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0439] There is little distinction between hardware and software implementations of aspects of the system. The use of hardware or software is typically (but not always, as the choice between hardware and software may become important in certain contexts) a design choice that represents a cost versus efficiency tradeoff. There may be a variety of vehicles by which the processes and / or systems and / or other technologies (e.g., hardware, software, and / or firmware) described herein may be implemented, and the preferred vehicle may vary depending on the context in which the processes and / or systems and / or other technologies are deployed. For example, if the implementer determines that speed and accuracy are most important, the implementer may select a vehicle that is primarily hardware and / or firmware. If flexibility is most important, the implementer may select a primarily software implementation. Alternatively, the implementer may select some combination of hardware, software, and / or firmware.

[0440] The above detailed description has been described various embodiments of the device and / or process by using block diagrams, flow charts and / or examples. Since such block diagrams, flow charts and / or examples include one or more functions and / or operations, those skilled in the art will understand that each function and / or operation within such block diagrams, flow charts or examples can be implemented individually and / or collectively by a variety of hardware, software, firmware or almost any combination thereof. In one embodiment, several parts of the subject matter described herein can be implemented via application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs) and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein can be equivalently implemented in whole or in part in an integrated circuit as one or more computer programs running on one or more computers (e.g., implemented as one or more programs running on one or more computer systems), implemented as one or more programs running on one or more processors (e.g., implemented as one or more programs running on one or more microprocessors), implemented as firmware or almost any combination thereof, and in view of the present disclosure, designing circuits and / or writing code for software and / or firmware will be well within the skills of those skilled in the art. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein may be distributed as a variety of forms of program products, and that the illustrative embodiments of the subject matter described herein apply regardless of the particular type of signal-bearing medium used to actually implement the distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable media such as floppy disks, hard drives, CDs, DVDs, digital tapes, computer memory, etc.; and transmission-type media such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.).

[0441] Those skilled in the art will recognize that it is common in the art to describe devices and / or processes in the manner set forth herein, and then use engineering practices to integrate such described devices and / or processes into data processing systems. That is, at least a portion of the devices and / or processes described herein can be integrated into data processing systems via a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system can typically include one or more of the following: a system unit housing, a video display device, a memory (such as, volatile and non-volatile memory), a processor (such as, a microprocessor and a digital signal processor), a computing entity (such as, an operating system, a driver, a graphical user interface, and an application), one or more interactive devices (such as, a touchpad or screen) and / or a control system including a feedback loop and a control motor (e.g., a feedback for sensing position and / or speed, a control motor for moving and / or adjusting components and / or quantities). A typical data processing system can be implemented using any suitable commercially available components, such as those components typically found in data computing / communication and / or network computing / communication systems.

[0442] The subject matter described herein sometimes illustrates different components that are included in or connected to different other components.It should be understood that this depicted architecture is only an example, and in fact, many other architectures that realize the same function can be realized.In the sense of concept, any arrangement of components that realize the same function is effectively "associated" so that the desired function can be realized.Therefore, any two components that are combined to realize a specific function herein can be regarded as "associated" with each other so that the desired function is realized, regardless of the architecture or intermediate components.Similarly, any two components so associated can also be regarded as "operably connected" or "operably coupled" to each other to realize the desired function, and any two components that can be so associated can also be regarded as "operably coupled" to each other to realize the desired function.Specific examples of operably coupling include but are not limited to components that can be physically paired and / or physically interacted and / or components that can be wirelessly interacted and / or wirelessly interacted and / or components that can interact logically and / or components that can interact logically.

[0443] With respect to the use of substantially any plural and / or singular terms herein, those skilled in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. For purposes of clarity, various singular / plural permutations may be expressly set forth herein.

[0444] Those skilled in the art will understand that, in general, the terms used herein and particularly in the appended claims (e.g., the bodies of the appended claims) are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including but not limited to", the term "having" should be interpreted as "having at least", the term "comprising" should be interpreted as "including but not limited to", etc.). Those skilled in the art will further understand that if a specific number of an introduced claim recitation is intended, such intent will be expressly recorded in the claim, and if no such recording is made, such intent does not exist. For example, where only one item is intended, the term "single" or similar language may be used. As an aid to understanding, the appended claims and / or the description herein may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be understood to imply that the introduction of a claim recitation by the indefinite article "a" or "an" will include any particular claim of such introduced claim recitation limited to embodiments including only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. In addition, even if specific numbers of introduced claim recitations are explicitly recited, those skilled in the art will recognize that such recitation should be interpreted as meaning at least the recited numbers (e.g., the unmodified recitation of "two recitations" without other modifiers means at least two recitations or two or more recitations). Furthermore, in those instances where a convention similar to “at least one of A, B, and C, etc.” is used, generally speaking, such construction is intended in the sense that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include, but is not limited to, a system having only A, a system having only B, a system having only C, a system having A and B together, a system having A and C together, a system having B and C together, and / or a system having A, B, and C together, etc.). In those instances where a convention similar to “at least one of A, B, or C, etc.” is used, generally speaking, such construction is intended in the sense that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include, but is not limited to, a system having only A, a system having only B, a system having only C, a system having A and B together, a system having A and C together, a system having B and C together, and / or a system having A, B, and C together, etc.).Those skilled in the art will further understand that, whether in the specification, claims or drawings, almost any alternative words and / or phrases presenting two or more replaceable terms should be understood to consider the possibility of including one of the terms, any one of the two terms or all of the two terms. For example, the phrase "A or B" will be understood to include the possibility of "A" or "B" or "A and B". Further, as used herein, the term "any of..." followed by a list of multiple items and / or multiple categories of items is intended to include "any one", "any combination", "any multiple" and / or "any combination of multiple" in the items and / or categories, either alone or in combination with other items and / or other categories of items. In addition, as used herein, the term "set" is intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero. Moreover, as used herein, the term "multiple" is intended to be synonymous with "plurality".

[0445] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0446] As will be understood by those skilled in the art, for any and all purposes, such as, in providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be easily identified as fully describing the same range and enabling the same range to be decomposed into at least equal half, one-third, one-quarter, one-fifth, one-tenth, etc. As a non-limiting example, each range discussed herein can be easily decomposed into a lower third, a middle third, and an upper third, etc. As will be understood by those skilled in the art, all languages ​​such as "up to", "at least", "greater than", "less than", etc. include the recorded numbers, and refer to the ranges that can be subsequently decomposed into sub-ranges as discussed above. Finally, as will be understood by those skilled in the art, the range includes each individual member. Therefore, for example, a group with 1 to 3 units refers to a group with 1, 2 or 3 units. Similarly, a group with 1 to 5 units refers to a group with 1, 2, 3, 4 or 5 units, and the like.

[0447] Furthermore, the claims should not be read as limited to the order or elements provided unless so stated. In addition, use of the term "means for..." in any claim is intended to invoke 35 USC § 112, 6 or “means-plus-function” claim format, and any claim without the term “means for…” is not intended to be so.

[0448] By way of example, suitable processors include a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), an application specific standard product (ASSP); a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), and / or a state machine.

[0449] The WTRU may be used in conjunction with modules including a software defined radio (SDR) implemented in hardware and / or software, as well as other components such as a camera, a video camera module, a video phone, a speaker phone, a vibration device, a speaker, a microphone, a television transceiver, a hands-free phone, a keyboard, a Bluetooth module, a frequency modulation (FM) radio unit, a near field communication (NFC) module, a liquid crystal display (LCD) display unit, an organic light emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and / or any wireless local area network (WLAN) or ultra-wideband (UWB) module.

[0450] Although various embodiments have been described in terms of a communication system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In certain embodiments, one or more of the functions of the various components may be implemented in software that controls a general purpose computer.

[0451] Furthermore, while the invention has been illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the range of equivalents of the claims and without departing from the invention.

Claims

1. A method implemented in a wireless transmit / receive unit (WTRU), the method comprising: receiving scheduling information for one or more sidelink transmissions from a network, the scheduling information indicating a set of scheduled resources; Performing listen before talk (LBT) on the set of scheduled resources for obtaining a subset of resources in the set of scheduled resources; transmitting sidechain control information indicating the acquired resource subset; transmitting data in the acquired subset of resources; as well as Feedback information related to the one or more sidelink transmissions is transmitted to the network based on a ratio between the number of acquired resources and the number of scheduled resources.

2. The method of claim 1, wherein the sidechain transmission in the one or more sidechain transmissions comprises sidechain control information transmission and data transmission.

3. The method of any one of claims 1 and 2, wherein the number of acquired resources is the number of resources in the acquired resource subset.

4. The method of any one of claims 1 to 3, wherein the number of scheduled resources is the number of resources in a set of scheduled resources.

5. The method of any one of claims 1 to 4, wherein the set of scheduled resources spans any of more than one LBT subband and more than one time slot.

6. The method of any one of claims 1 to 5, wherein the acquired resource subset spans more than one LBT subband.

7. The method according to any one of claims 1 to 6, comprising: A determination is made as to whether conditions associated with the number of acquired resources and the number of scheduled resources are satisfied.

8. The method of claim 7, wherein the condition is satisfied if a ratio between the number of acquired resources and the number of scheduled resources is above a threshold.

9. The method of claim 8, wherein the threshold is any one of: preconfigured in the WTRU and dynamically indicated in downlink control information.

10. The method according to any one of claims 7 to 9, wherein if it is determined that a condition associated with the number of acquired resources and the number of scheduled resources is satisfied, the feedback information indicates a positive acknowledgement.

11. The method of claim 10, wherein the positive acknowledgement comprises positive hybrid automatic repeat request (HARQ) feedback.

12. The method of any one of claims 7 to 11, wherein if it is determined that the conditions associated with the number of acquired resources and the number of scheduled resources are not satisfied, the feedback information indicates any one of a negative acknowledgement and a request for more resources.

13. The method of claim 12, wherein the request for more resources comprises any one of a scheduling request and a sidechain buffer status report.

14. The method of claim 12, wherein the negative acknowledgement comprises negative hybrid automatic repeat request (HARQ) feedback.

15. The method of any one of claims 7 to 14, comprising: Configuration information indicating a condition associated with a number of acquired resources and a number of scheduled resources is received.

16. A wireless transmit / receive unit (WTRU) comprising circuitry, the circuitry including a transmitter, a receiver, a processor, and a memory, configured to: receiving scheduling information for one or more sidelink transmissions from a network, the scheduling information indicating a set of scheduled resources; Performing listen before talk (LBT) on the set of scheduled resources for obtaining a subset of resources in the set of scheduled resources; transmitting sidechain control information indicating the acquired resource subset; transmitting data in the acquired subset of resources; as well as Feedback information related to the one or more sidelink transmissions is transmitted to the network based on a ratio between the number of acquired resources and the number of scheduled resources.

17. The WTRU of claim 16, wherein the sidelink transmission of the one or more sidelink transmissions comprises a sidelink control information transmission and a data transmission.

18. A WTRU as described in any of claims 16 to 17, wherein the set of scheduled resources spans any of more than one LBT sub-band and more than one time slot.

19. The WTRU of any one of claims 16 to 18, wherein the feedback information indicates a positive acknowledgement if a condition associated with the number of acquired resources and the number of scheduled resources is determined to be satisfied.

20. The WTRU of any one of claims 16 to 18, wherein if it is determined that a condition associated with the number of acquired resources and the number of scheduled resources is not satisfied, the feedback information indicates any one of a negative acknowledgement and a request for more resources.

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