WO2020069111A1 - Resource selection and reservation associated with vehicle to everything sidelink - Google Patents

Abstract

A wireless transmit/receive unit (WTRU) with aperiodic sidelink traffic to send may receive a resource pool configuration. The resource pool configuration may include two regions, with a first region having smaller resources than a second region. The WTRU may select a data resource or control resource in the second region. The WTRU may select a resource of the first region based on clear channel assessment (CCA) sensing. The WTRU may transmit a scheduling assessment (SA) reservation using the selected resource of the first region. The SA reservation may indicate a reservation of the data resource or control resource in the second region. The WTRU may send the data or control transmission using the data or control resource in the second region based on the indicated reservation of the data resource or control resource in the second region.

Description

RESOURCE SELECTION AND RESERVATION ASSOCIATED WITH VEHICLE TO EVERYTHING

SIDELINK

CROSS-REFERENCE TO RELATED CASES

[0001] The present application claims the benefit of U.S. Provisional Patent Application No. 62/736,666 filed September 26, 2018, the contents of which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Use cases for emerging 5G systems may include Enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (mMTC) and Ultra Reliable and Low latency Communications (URLLC). Different use cases may focus on different requirements such as higher data rate, higher spectrum efficiency, low power and higher energy efficiency, lower latency, and/or higher reliability.

SUMMARY

[0003] Systems, methods, and instrumentalities are provided for resource allocation associated with new radio (NR) vehicle to everything (V2X) sidelink. A scheduling assessment (SA) reservation may be sent by, for example, a transmitting wireless transmit/receive unit (WTRU), on a resource in a first resource region to indicate a selection of a data resource or a control resource in a second resource region, e.g., for transmitting data or control information.

[0004] A WTRU with aperiodic sidelink traffic to send may receive a resource pool configuration. The resource pool configuration may include two regions, with a first region having smaller resources than a second region. A resource in the first region may have a greater granularity than a resource in the second region, e.g., based on different numerologies and/or sizes of subchannels. The WTRU may select a data resource or a control resource in the second region. The data resource may be used for a data transmission. The control resource may be used for a control transmission.

[0005] The WTRU may select a resource of the first region based on clear channel assessment (CCA) sensing. The WTRU may transmit a scheduling assessment (SA) reservation using the selected resource of the first region. The SA reservation may indicate a reservation of the data resource or the control resource in the second region and a reservation of a feedback resource in the first region. The WTRU may send the data transmission using the data resource in the second region based on the indicated reservation of the data resource in the second region. The WTRU may send the control transmission using the control resource in the second region based on the indicated reservation of the control resource in the second region. The WTRU may receive the feedback based on the indicated reservation of the feedback resource of the first region. The data resource may be used for physical sidelink shared channel (PSSCH) transmission. The control resource may be used for physical sidelink control channel (PSCCH) transmission. The feedback resource of the first region may be used for physical sidelink feedback channel (PSFCH) transmission.

[0006] The SA reservation may include quality of service (QoS) information used for a determination of a preemption. In an example, the WTRU may determine that the data or control transmission preempts the data or control transmissions that another WTRU(s) intends to perform based on a determination that the data or control transmission has a higher priority or lower latency requirement than data or control transmissions that another WTRU(s) intends to perform using the data resource or control resource in the second region.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0008] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0009] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0010] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0011] FIG. 2 depicts an exemplary resource allocation indication for Physical Sidelink Shared Channel (PSSCH) (re)transmission.

[0012] FIG. 3 depicts an exemplary semi-persistent scheduling (SPS) with shared resources.

[0013] FIG. 4 depicts an example processing of periodic traffic using SPS resources.

[0014] FIG. 5 depicts an exemplary frame structure with listen before talk (LBT) for a time division multiplexing (TDM) or a frequency division multiplexing (FDM) multiplexed scheduling assignment (SA) and data. [0015] FIG. 6 depicts an exemplary resource selection for aperiodic traffic.

[0016] FIG. 7 depicts an exemplary frame structure of the SA in resource with LBT and data in resource without LBT.

[0017] FIG. 8 depicts example FDM multiplexed resource pool regions for periodic traffic and aperiodic traffic.

[0018] FIG. 9 depicts an example resource pool configuration.

[0019] FIG. 10 depicts an exemplary WTRU implementation of transmitting aperiodic data via cross slot scheduling

[0020] FIG. 11 illustrates an example of resource usage , e.g., for one or more of aperiodic traffic, bursty traffic, event-driven traffic, or the like

[0021] FIG. 12 depicts an example of a WTRU receiving aperiodic data and sending feedback.

[0022] FIG. 13 depicts an example resource exchange.

[0023] FIG. 14 depicts an exemplary mode 1 WTRU PSSCH transmission.

[0024] FIG. 15 depicts exemplary WTRU data transmission with more than one retransmission.

[0025] FIG. 16 depicts an example decoding of PSSCH data by a receiving WTRU.

DETAILED DESCRIPTION

[0026] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 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-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0027] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a ON 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though 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 a "STA”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0028] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0029] 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), relay nodes, 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 licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions. [0030] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0031] More specifically, as noted above, the communications 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, and the like. 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 establish the air interface 1 15/1 16/1 17 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (FI SPA) and/or Evolved HSPA (FISPA+). HSPA may include High-Speed Downlink (DL) Packet Access (FISDPA) and/or High-Speed UL Packet Access (FISUPA).

[0032] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0033] 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 1 16 using New Radio (NR).

[0034] 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 implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by 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., a eNB and a gNB).

[0035] 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, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like. [0036] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet 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 femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115.

[0037] The RAN 104/113 may be in communication 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 varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, 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 that 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 be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0038] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide 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), 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 communications 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. [0039] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications 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 over different wireless links). For example, the WTRU 102c shown in FIG. 1 A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0040] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include 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, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0041] 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 in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. 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. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0042] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over 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 an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0043] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, 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 transm it/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0044] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0045] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0046] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0047] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102.

In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location- determination method while remaining consistent with an embodiment.

[0048] The processor 118 may further be 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 peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (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, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of 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.

[0049] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (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 either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0050] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to 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.

[0051] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though 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.

[0052] 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 UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface. [0053] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0054] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. 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.

[0055] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the 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 user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0056] 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 1 10, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0057] 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 communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves 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 the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0058] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0059] In representative embodiments, the other network 1 12 may be a WLAN.

[0060] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the

BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. 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 the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad- hoc” mode of communication.

[0061] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs 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 in 802.11 systems. For CSMA/CA, the STAs (e.g., every 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.

[0062] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0063] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0064] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 h, and 802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type

Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0065] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11h, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode.

In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0066] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0067] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an 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. [0068] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 1 13 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, gNBs 180a, 108b 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 an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0069] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the 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 gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0070] 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 the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c. [0071] Each of the gNBs 180a, 180b, 180c 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 UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E- UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0072] The CN 115 shown in FIG. 1 D 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. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0073] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 1 13 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 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, and/or the like. The AMF 162 may provide a control plane function for switching between the RAN 1 13 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.

[0074] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N1 1 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet- based, and the like.

[0075] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the

RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet- switched networks, such as the Internet 1 10, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0076] 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 serves 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 the other networks 112, which may include other wired and/or wireless networks that are 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 the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0077] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-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, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[0078] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the 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 in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may performing testing using over-the-air wireless communications.

[0079] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data. [0080] In vehicle to everything (V2X), a vehicle may be in transmission mode 3 (e.g., a mode 3 user) or may be in transmission mode 4 (e.g., a mode 4 user). A mode 3 user may use (e.g., directly) the resources allocated by a base station for sidelink (SL) communication among vehicles and/or between a vehicle and a pedestrian. A mode 4 user may obtain a list of candidate resources allocated by a base station. The mode 4 user may select a resource among the list of candidate resources for its SL communication.

[0081] In new radio (NR) V2X, a mode 1 user may be, for example, similar to the mode 3 user in LTE V2X. A mode 2 user may include the mode 4 user in NR V2X. "User” or "WTRU” may refer to a vehicle in one or more examples herein.

[0082] Downlink control information (DCI) format 5A (e.g., in LTE) may be used for the scheduling of physical sidelink control channel (PSCCH), and/or several sidelink control information (SCI) format 1 fields used for the scheduling of physical sidelink shared channel (PSSCH). The payload of DCI format 5A may include one or more of the following: carrier indicator -3 bits; lowest index of the subchannel allocation to the initial transmission - f^"log2 (S^ubc^haⁿⁿe^l )! bits; SCI format 1 fields including frequency resource location of initial transmission and retransmission and/or time gap between initial transmission and retransmission; and/or SL index - 2 bits (e.g., this field may be present only for cases with time division duplexing (TDD) operation with uplink-downlink configuration 0-6). If and/or when the format 5A cyclic redundancy check (CRC) is scrambled with SL-SPS-V-RNTI, one or more of the following fields may be present: SL SPS configuration index - 3 bits; and/or activation/release indication - 1 bit.

[0083] If the number of information bits in format 5A mapped onto a given search space is less than the payload size of format 0 mapped onto the same search space, zeros may be appended to format 5A until the payload size equals that of format 0 including any padding bits appended to format 0.

[0084] If the format 5A CRC is scrambled by SL-V-radio network temporary identifier (RNTI) and if the number of information bits in format 5A mapped onto a given search space is less than the payload size of format 5A with CRC scrambled by SL-SPS-V-RNTI mapped onto the same search space and format 0 is not defined on the same search space, zeros may be appended to format 5A until the payload size equals that of format 5A with CRC scrambled by SL-SPS-V-RNTI.

[0085] SCI format 1 may be used for the scheduling of PSSCH, e.g., in LTE. The payload of SCI format 1 may include one or more of the following: priority - 3 bits; resource reservation - 4 bits; frequency resource location of initial transmission and retransmission -

tj_me gap between initial transmission and retransmission - 4 bits; modulation and coding scheme - 5 bits; retransmission index - 1 bit; and/or reserved information bits are added until the size of SCI format 1 is equal to 32 bits. The reserved bits may be set to zero.

[0086] The data retransmission may supported with a maximum of 1 retransmission, e.g., in LTE V2X. The number of retransmissions may be configured via radio resource control (RRC) signaling (e.g., the IE “SL-PSSCH-TxConfigList”).

[0087] For mode 3 WTRUs, the DCI format 5A may include fields "Frequency resource location of initial transmission and retransmission” and/or "Time gap between initial transmission and retransmission”. The "Frequency resource location of initial transmission and retransmission” parameter may be equal to the "resource indication value (RIV)”, which can be used to derive L_subCH the number of contiguously allocated sub-channels (for both initial transmission and retransmission), and/or nf_abCH- the starting sub channel index (of the re-transmission). The "Time gap between initial transmission and retransmission” parameter may provide the information about the time gap SF_gap.

[0088] Upon receiving the DCI format 5A, a mode 3 WTRU may determine the sub-frame (e.g., T of the initial transmission from the field "SL index” and the starting sub-channel index (e.g., F of the initial transmission from the field "Lowest index of the sub-channel allocation to the initial transmission”. The sub- frame T_t and the starting sub-channel index F_t may provide the resources for the initial transmission.

[0089] In the case of SF_gap = 0, (e.g., no retransmission), the transmitting WTRU may set the corresponding SCI fields: "Frequency resource location of initial transmission and retransmission” may be calculated by L_subCH and F_t from the DCI 5A it receives; and/or "Time gap between initial transmission and retransmission” may be equal to 0.

[0090] In the case of SF_gap ¹ 0, WTRU may set the SCI fields of the initial transmission: "Frequency resource location of initial transmission and retransmission” may be calculated by L_subCH and nf^_bcii from the DCI 5A it receives; "Time gap between initial transmission and retransmission” may be equal to SF_gap from the DCI 5A it receives; and/or "Retransmission index” may be equal to 0.

[0091] For the resources of the retransmission (e.g., SF_gap ¹ 0), a mode 3 WTRU may determine the sub-frame as ( T₂ = T_t + SF_gap ) and the starting sub-channel index as

(i.e., F₂) from the DCI 5A it receives. The WTRU may set the SCI fields of the retransmission as: "Frequency resource location of initial transmission and retransmission” may be calculated by L_subCH from the DCI 5A it receives and F^ "Time gap between initial transmission and retransmission” may be equal to SF_gap from the DCI 5A it receives; and/or "Retransmission index” may be equal to 1. [0092] From the higher layer, a mode 4 WTRU may be informed of the number of sub-channels L_subCH to be used for PSSCH transmission in a subframe. Mode 4 WTRUs may determine the available time and frequency resources for initial transmission and retransmission, for example, based on sensing and/or reference signal received power (RSRP) measurement. The first selected resource may correspond to sub-frame T_t and the starting sub-channel index F_t and the second selected resource may correspond to sub-frame T₂ and the starting sub-channel index F₂ , where

< T₂ £ T₁ + 15.

[0093] A mode 3 or mode 4 WTRU may set the SCI fields of the initial transmission as: "Frequency resource location of initial transmission and retransmission” may be calculated by L_subCH and F₂ ; "Time gap between initial transmission and retransmission” may be equal to T₂— 7^; and/or "Retransmission index” may be equal to 0.

[0094] A mode 3 or mode 4 WTRU may set the SCI fields of the retransmission as: "Frequency resource location of initial transmission and retransmission” may be calculated by L_subCH and F_t \ "Time gap between initial transmission and retransmission” may be equal to T₂— 7^; and/or "Retransmission index” may be equal to 1.

[0095] Table 1 shows the SCI contents of the initial transmission and the retransmission (e.g., in LTE V2X).

Table 1 : Exemplary SCI contents for a (e.g., at most 1) retransmission

[0096] FIG. 2 depicts an exemplary resource allocation indication for PSSCH (re)transmission. In this example, the SF_gap > 0 may be signalled in SCI format 1 in both initial transmission and retransmission.

[0097] The resource selection for a mode 4 WTRU may include one or more of the following, e.g., in LTE V2X. The transmission window between [n + T₁, n + T₂\ may be determined by selecting proper T_t and T₂ values, for example based on latency requirements. A candidate resource may be denoted by R_{x y} , and the set of candidate resources may be denoted by S. The set of candidate resources may be determined by sensing a received signal strength indicator (RSSI). The total number of candidate resources may be M_total. A set S_A may be determined from S based on the RSRP level of candidate resources. For example, if a candidate resource in S has RSRP level above a certain threshold, it may be saved to S_A. A resource R_{x y} may be removed from the candidate resource set S_A if it conflicts its own transmissions or other WTRU's reserved resources (e.g., mode 3 reserved resources). If the number of remaining candidate resources in S_A after removing resource R_{x y} is no more than 0.2 * M_tota the set S ₄ may be determined with a smaller threshold. Otherwise, the set S_A of resources may be ranked based on its RSSI values averaged over the past several slots. The first 0.2 * M_ίoίaί ranked resources (e.g., S_B) may be reported to higher layers for the final resource selection.

[0098] Traffic may be periodic with fixed size. For example, in LTE V2X sidelink, most of the traffic may be periodic with fixed size. A WTRU (e.g., a mode 3 or a mode 4 WTRU) may determine a sidelink resource reservation with a certain period (e.g., as low as 20 ms). A reserved resource (e.g., each reserved resource) may be of the same size, for example, to fit the fixed size of the traffic payloads.

[0099] Traffic may be aperiodic and/or event-triggered, e.g., in NR V2X sidelink. For periodic traffic, the payload sizes may vary over time (e.g., for each period). The resource allocation and/or reservation may be different for NR V2X when compared to LTE V2X. The channel access of an NR mode 2 WTRU (e.g., each NR mode 2 WTRU) may not fully rely on the large scaled sensing results, which is based on the periodic resource reservation.

[0100] NR V2X sidelink may support unicast and groupcast. Supporting unicast and groupcast may be based on feedback transmissions, e.g., hybrid automatic repeat request (FIARQ)-ACK, CSI, etc. The resource allocation for feedback transmissions may developed and/or implemented. For example, resource allocation and/or channel access mechanisms may be developed and/or implemented for NR V2X sidelink.

[0101] A 99.999% reliability level may be adopted, for example, in a NR URLLC use case. V2X may be a kind of applications in URLLC use case. V2X may achieve a 99.999% reliability level. V2X sidelink may support a retransmission, e.g., in LTE. Retransmission may be limited to one retransmission, e.g., in LTE V2X. More retransmissions may be used in NR V2X, for example, to achieve high reliability.

[0102] Resource allocation, data redundancy versions, and/or the like may be developed and/or implemented to support more than 1 retransmission in NR V2X sidelink.

[0103] NR V2X may include multiple (e.g., 25) defined use cases. These use cases may be categorized to 4 use case groups. Some of the use cases require a high data rate. For example, the sidelink data rate could be 65 Mbps in vehicle platooning use cases. NR V2X sidelink may include support for high data rates. For example, the NR V2X sidelink resource allocation may be used to support higher data rates.

[0104] Schemes associated with resource allocation may include scheduling (e.g., semi-persistent scheduling) for periodic traffic with variable payload sizes. In LTE V2X, sidelink traffic may be (e.g., most likely) periodic with a fixed size. Semi-persistent scheduling (SPS) for a mode 3 user may fit the LTE V2X sidelink traffic. In NR V2X, sidelink traffic may be periodic with variable payload sizes. In examples, SPS for a NR mode 1 user may not work well for variable payload sizes. As an example, if a reserved SPS resource is equal to the lower bound of the periodic traffic payload size, the reserved SPS resource may not be large enough if and/or when the traffic payload size becomes larger. If the reserved SPS resource is equal to the higher bound of the periodic traffic payload size, the reserved SPS resource may be a waste (e.g., too large) if and/or when the traffic payload size is smaller. An SPS scheme may be deployed or implemented for periodic traffic with variable payload sizes.

[0105] SPS may be used to schedule extended resources. A user (e.g., WTRU 304 in FIG. 3) may have periodic traffic with variable payload sizes. The user may be an NR mode 1 user. If and/or when WTRU 304 requests resources from a network (e.g., gNB), WTRU 304 may provide the information on one or more of the following: the periodicity of its traffic, a minimum payload size of the periodic traffic, and/or a maximum payload size of the periodic traffic to the gNB. The gNB may configure SPS resources for WTRU 304's sidelink transmissions, for example, based on the information provided by WTRU 304. For example, the user may send traffic characteristics (e.g., a periodicity, a minimum payload size, and/or a maximum payload size) associated with the periodic traffic to the network. The network may configure SPS resources based on the traffic characteristics. An SPS configuration may include multiple sets of resources that include dedicated resource set and a shared resource set. The periods of these resource sets may be the same or different. In examples, the dedicated resource set may be assigned for the transmissions of normal payload sizes of the periodic traffic. The shared resource set may be assigned for the transmissions of the additional payload sizes over the normal payload sizes. Based on the traffic nature, the dedicated resource set may be occupied by a user (e.g., WTRU 304 in FIG. 3), for example to support its normal transmission requirement. The shared resource set may not always be occupied by the user. The shared resource set may be shared by several WTRUs.

[0106] FIG. 3 depicts an exemplary SPS with shared resources. NR mode 1 WTRUs may share the shared resources. Shared resource usage may be indicated using DCI and/or SCI. Data may be periodic in time domain. Data size in an (e.g., each) occasion may change and/or follow a certain pattern. In examples, WTRU 304 may follow a payload size pattern (e.g., 1000, 2000, 1000 bits) of periodic traffic, and WTRU 306 may follow a payload size pattern (1000, 1000, 2000 bits) of periodic traffic. The dedicated resource set may be used by WTRU 304 in the second occasion and may be used by WTRU 306 in the third occasion. WTRUs 304 and/or 306 may be NR mode 1 WTRUs.

[0107] Shared resources may be pre-configured or may be configured by dedicated RRC signals to certain WTRUs. A shared resource usage may be indicated, for example, via a DCI and/or SCI indication In examples, if an/or when a gNB activates the SPS configurations {e.g., via DCI format) to a WTRU, the gNB may indicate which shared SPS resource(s) could be used by the WTRU. The WTRU may or may not be informed of information of other WTRUs that have access to the shared resources. If the WTRU intends to use the shared resources for a (e.g., the next) transmission occasion, the WTRU may include an indication (e.g., a shared resources indication) in the SCI format. This indication in SCI may inform the receiving WTRUs about the additional traffic that is more than the data in the dedicated SPS configured resources. The indication may inform other WTRUs about the WTRU's upcoming usage of the shared resource(s). Other WTRUs, who were also assigned access to the shared resource(s), may react accordingly.

[0108] Access to shared resource may be based on, for example, QoS of traffic. A WTRU may monitor another WTRU's reservation of a shared resource. For example, if two or more WTRUs have a common shared resource, these WTRUs may monitor each other's reservation of the common shared resource. If there is no conflict of the shared resource usage, a WTRU that reserves the shared resource (e.g., a reserving WTRU) may continue to use the shared resource. If there is a conflict of the shared resource usage, a selection may be implemented (e.g., independently) at these WTRUs. The selection may depend on the QoS of the data (e.g., the priority of the data and/or the latency requirement of the data). For example, a first WTRU may have periodic traffic data with an additional payload at a first transmission occasion. The first WTRU may use the dedicated SPS resource to transmit part of the data. In this transmission, the SCI may indicate that the first WTRU intends use the upcoming shared resource, and the priority and/or latency of the data may be the same as the current data in the SCI (e.g., by default). The first WTRU may monitor the transmissions of other WTRUs assigned to the same shared resources. If other WTRUs do not reserve the shared resource for the next transmission occasion, the first WTRU may continue to use the shared resource for the next transmission occasion. If there is another WTRU(s) reserving the shared resource for the next transmission occasion, the first WTRU may determine whether it continues to use the next shared resource or skip the usage of the next shared resource. The first WTRU may determine whether to use the next shared resource based on the QoS of the data between the reserving WTRUs. If the first WTRU intends to use the shared resource to transmit/receive a high priority traffic (e.g., with a higher priority than the other reserving WTRU(s)), the first WTRU may continue to use the shared resource for the next transmission occasion. If the first WTRU intends to use the shared resource to transmit/receive traffic associated with low latency (e.g., with a lower latency requirements than the other reserving WTRU(s)), the first WTRU may continue to use the shared resource for the next transmission occasion. Otherwise, the first WTRU may give up the transmission in the next transmission occasion of the shared resources. For example, one of the other reserving WTRUs may use the next shared resource.

[0109] A WTRU may be configured to process periodic traffic using SPS resources, for example, as described herein. FIG. 4 depicts an example processing of periodic traffic using SPS resources. A WTRU (e.g., an NR mode 1 WTRU) configured via SPS may have access to an extended shared resource. As shown in FIG. 4, if and/or when the WTRU receives the periodic traffic with additional payloads, the WTRU may separate the additional payloads to multiple (e.g., two) parts. A first part may be of the same size as the normal payload sizes. The WTRU may process these parts separately. The processed first part may be sent, for example, using the dedicated SPS resource. The SCI for the transmission of the first part may indicate the WTRU's reservation of the next shared resource. In an example, the SCI for the transmission of the first part may indicate that the WTRU intends to use the next shared resource for the second part of the periodic payload (e.g., the additional payloads). The WTRU may monitor the transmissions of other WTRUs that have (e.g., are assigned with) access to the shared resources. The WTRU may monitor the other WTRUs' intentions of using the next shared resource. For example, the WTRU may monitor (e.g., track) the SCI of other WTRUs' transmissions. The WTRU may determine whether there is a conflict of using the shared resource. If no other WTRUs show the intention of using the next shared resource, the WTRU may use (e.g., directly use) the next shared resource for transmitting the remaining data including the second part of the payloads. If one or more other WTRUs show the intention of using the next shared resource, the WTRU may determine whether other WTRU's data has higher priority or lower latency. In an example, if one or more other WTRUs show the intention of using the next shared resource, WTRU may compare the QoS associated with the intended transmissions of the one or more other WTRUs and itself.

If the WTRU has higher priority data and/or lower latency data than the one or more other WTRUs to transmit, the WTRU may continue to use the next shared resource for transmitting its remaining data. Otherwise, the WTRU may not use the next shared resource or may use the next shared resource in a random fashion or in a predefined (random) pattern.

[0110] A WTRU may be configured with multiple shared SPS resources. A WTRU may be assigned a dedicated SPS resource and a shared SPS resource. A single shared SPS resource may not be enough, for example, for relatively large variations of periodic payload sizes. More than one shared SPS resource may be configured for a WTRU. The usage of the additional shared SPS resources may be, for example, similar to a (e.g., the first) shared SPS resource. For example, the WTRU may have access to multiple shared SPS resources. An indication of using the additional SPS resources may be included in the SCI of the dedicated SPS resource and/or in the first shared SPS resource.

[0111] Schemes associated with resource allocation may include listen before talk (LBT) used for aperiodic traffic. LBT used for aperiodic traffic may be used, for example, to address collision(s) resulting from the aperiodic traffic. In LBT, a WTRU (e.g., each WTRU) may initialize a random number or counter. The WTRU may use clear channel access (CCA) to check whether a resource is occupied by other WTRUs. The WTRU may compare an energy measurement of the resource during the CCA time against a preconfigured threshold. If the resource is determined to be empty, the WTRU may reduce the initial random number or counter by one. Otherwise, the WTRU may retain the initial random number or counter. The initial random number or counter may be reduced to zero. Once the initial counter is 0, the WTRU may use the empty resource for its transmissions. In case of failure transmission(s), a back-off counter may be generated, for example, within a contention window. CSMA/CA type contention window size updates may be used, for example, as the contention window herein.

[0112] A resource may last for a slot duration, for example, in the time domain. A resource may occupy a sub-channel with a configurable size, for example, in frequency domain. CCA may take a sub-slot and/or several symbols in time domain and a whole sub-channel in frequency domain. FIG. 5 depicts an exemplary frame structure with listen before talk (LBT) for TDM or FDM multiplexed Scheduling

Assignment (SA) and data. CCA-based general PSCCH/PSSCH may be used, e.g., in FIG. 5(a). FIG. 5(a) depicts an exemplary frame structure with LBT for TDM multiplexed SA and data. FIG. 5(a) depicts an exemplary frame structure with LBT for FDM multiplexed SA and data.

[0113] As shown in FIG. 5, the overhead of automatic gain control (AGC), GAP, DMRS, and/or CCA may be relatively large. The resource elements left for data transmissions may be relatively limited. CCA- based standalone PSCCH may be used.

[0114] LBT resources may include SCI (e.g., only). An example of the LBT resources may include CCA resources shown in FIG. 5. Aperiodic traffic may be a relatively large size. For aperiodic traffic with a relatively large size, a relatively large number of contiguous sub-channels may be reserved for data transmissions. The chance of collision may be relatively high if and/or when a relatively large number of contiguous sub-channels are simultaneously empty. In an example, the overhead caused by CCA may be large and the resource elements for data transmissions may be limited if and/or when an LBT scheme

(e.g., in Fig. 5) is used. Control information (e.g., only control information) may be transmitted in LBT resource(s). The control information may reserve some future resources for data transmission(s). In examples, if and/or when the LBT resource(s) includes only SCI, the resource to be used for LBT may be a single sub-channel. If and/or when the LBT resource(s) includes only SCI, the resource to be used for LBT may include a sub-channel with a smaller number of subcarriers than that of a sub-channel for data transmissions. Using a single sub-channel and/or using a sub-channel with a smaller number of subcarriers with LBT may reduce a chance of collision(s).

[0115] A WTRU may follow a resource selection implementation for aperiodic traffic. The WTRU may be an NR mode 2 WTRU. FIG. 6 depicts an exemplary resource selection for aperiodic traffic. As shown in FIG. 6, the WTRU may determine whether the traffic to be transmitted/received is aperiodic. If the traffic is periodic, one or more reserved resources may be used for sending the data. If the traffic is aperiodic, the WTRU may determine whether the aperiodic traffic is of a relatively large payload size. If the aperiodic is not of a relatively large payload (e.g., a small payload size), the WTRU may apply resource selection with LBT on a proper number of sub-channels. If and/or when an empty resource is detected, the WTRU may send the aperiodic traffic (e.g., SA and/or data of small payload) on the empty resource.

[0116] If the aperiodic traffic is of a relatively large payload size, the WTRU may apply the resource selection associated with LBT on a single sub-channel and/or a sub-channel with fewer sub-carriers. The WTRU may apply a resource selection (e.g., legacy) for data transmissions in a later slot. The WTRU may send the control information to reserve future data resources. In an example, in the selected resource associated with LBT, the WTRU may only send the control information (e.g., SA) to reserve future data resources. The WTRU may use the selected data resource to transmit data. FIG. 7 depicts an exemplary frame structure of the SA in resources with LBT and data in resources without LBT. As shown in FIG. 7, transmission of data in resources without LBT may follow the SA in resources with LBT.

[0117] Schemes associated with resource allocation may include configurable resource pool regions, for example, for periodic traffic and aperiodic traffic. Resource selection for a WTRU (e.g., NR mode 2 WTRU) may be based on periodic reservation of the resources. Resource selection for an LTE mode 4 WTRU may be based on the periodic reservation of the resources. Once the transmission resource is reserved, the reserved resource may be accessed (e.g., directly).

[0118] A WTRU may sense a resource before using it. Traffic in NR V2X may be aperiodic and/or event-triggered. A resource selection mechanism (e.g., the same resource selection mechanism as in LTE V2X) may lead to collisions. LBT and/or small-scale sensing may be applied in NR V2X, for example, to avoid collision(s). In an example, a WTRU may sense a selected resource before using it.

[0119] The usage of LBT for aperiodic traffic may increase the overhead of data transmission(s). The resource pool may be separated based on periodic or aperiodic traffic, for example, to minimize overhead. For example, one resource pool may be configured for periodic traffic and another resource pool may be configured for aperiodic traffic. A WTRU may switch (e.g., dynamically) among multiple resource pools. For example, a WTRU may dynamically switch between two resource pools for its periodic traffic and aperiodic traffic. Switching between resource pools may lead to some delays and/or increase the operational complexity. A resource pool having different regions may be used. In an example, a common resource pool with two different resource regions may include a resource region for periodic traffic and another resource region for aperiodic traffic.

[0120] Resource pool region for periodic traffic and resource pool region for aperiodic traffic may be separated. The separation of the resource pool region may be based on frequency and/or based on time. For frequency-based resource pool region separation, the first several sub-channels may be dedicated to aperiodic traffic. A WTRU may perform LBT before accessing these sub-channels. The WTRU may not monitor these sub-channels. The WTRU may not perform the RSSI-based ranking or resource selection on these sub-channels. Not monitoring or selecting the sub-channels in a resource pool region may simplify the WTRU's operations on the resource pool region. The remaining several sub-channels may be dedicated for periodic traffic. A WTRU may monitor the remaining several sub-channels {e.g., for a relatively long time). The WTRU may track periodic reservations (e.g., all the periodic reservations) on the channels. The WTRU may not perform LBT before accessing the remaining several sub-channels. Not performing LBT before accessing the remaining several sub-channels may result in the full usage of the resource. Resource usage of these sub-channels based on reservations may reduce the chance of collisions.

[0121] For time-based resource pool region separation, sub-channels (e.g., all the sub-channels) in a resource pool at certain slots or sub-slots may be dedicated to aperiodic traffic. Sub-channels (e.g., all the sub-channels) in a resource pool at other slots or sub-slots may be dedicated to periodic traffic. The time- based resource pool region separation may be mixed with frequency-based resource pool region separation.

[0122] SA/data multiplexing in the resource pool region for periodic traffic may be different from that in the resource pool region for aperiodic traffic. For example, the FDM multiplexed SA/data may be used for the periodic traffic resource pool region. The TDM multiplexed SA/data may be used for the aperiodic traffic resource pool region. FIG. 8 depicts example FDM multiplexed resource pool regions for periodic traffic and for aperiodic traffic. In the periodic traffic resource pool region, the SA/data may be FDM multiplexed. In the aperiodic traffic resource pool region, the SA/data may be TDM multiplexed. The PSCCFI and PSSCH resource pool may be nonadjacent, for example, in each case.

[0123] Resource pool region adjustment and/or indication may be signaled semi-statically or dynamically. The resource pool region separation information may be included in the RRC signaling, e.g., the IE of SL-CommResourcePoolV2X. The IE may indicate which sub-channels are assigned to periodic traffic and which sub-channels are assigned to aperiodic traffic. The configuration may be updated based on the demand of a type of traffic, the collision conditions, and/or the like. For example, a WTRU may find that it is hard to find empty resources in a certain resource pool region for its periodic traffic. The WTRU may report to gNB about this condition. The gNB may allocate more resources or more portions of resources for periodic traffic in certain RRC signaling.

[0124] A WTRU may detect collisions when using the certain resource pool region for its aperiodic traffic. The WTRU may report collision conditions to the gNB. The gNB may temporarily allow this WTRU to send aperiodic traffic on the resource pool region for periodic traffic. The WTRU may monitor the resource pool region to exclude the reserved resources for periodic traffic, and to perform LBT before accessing the resource. The gNB may send RRC signaling or physical layer signaling to indicate the WTRU for this usage. The gNB may allocate more portions of resources for aperiodic traffic in certain RRC signaling.

[0125] Schemes associated with resource allocation may include resource pool implementation for cross slot or cross sub-clot scheduling. In examples, multiple regions in a resource pool may have different numerologies and/or sub-channel sizes.

[0126] The PSSCH resource and its associated PSCCH resource may be adjacent or non-adjacent, for example, in FDM multiplexing manner. In examples, a WTRU may use a single resource time unit {e.g., a subframe) for transmitting SA and data, while receiving or monitoring channels in other resource time units. Half-duplex transmission may be used.

[0127] In TDM multiplexed SA and data where the SA and data are in different resource time units, the half-duplex constraint may cause that the transmitting WTRU to use two resource time units (e.g., one for SA and one for data) for one transmission. Using two resource time units for one transmission may restrict the transmitting WTRU's tracking and/or monitoring of other available channels, for example, restricting its future resource selection operations. Different numerologies may be used for the SA transmission and the data transmissions. A resource pool may be partitioned into two different regions. One region (e.g., a first resource region) may be for SA transmissions and another region (e.g., a second resource region) may be for data transmissions.

[0128] The second resource region may be like normal (e.g., LTE V2X) resource region. For example, each resource in the second resource region may or may not include control information. If the control information is included, the control information may be FDM or TDM multiplexed with data. In examples, the control information may be included in the second resource region for periodic traffic, while the control information may not be included in the second resource region for aperiodic traffic. Partial control information (e.g., MCS) may be included in the second resource region for aperiodic traffic, while other control information (e.g., resource reservation information) may not be included in the second resource region. The other control information may be included in region 1 (e.g., only). CCA or LBT operations may not apply to the second resource region. The avoidance of CCA in the second resource region may save resources for the data transmissions.

[0129] The first resource region may include SA information for aperiodic traffic. The first resource region may include the feedback e.g., for unicast and/or groupcast transmissions. The feedback may include HARQ, CSI, and/or the like. A preemption indication message may use the resources in the first resource region. CCA or LBT operations may apply to the first resource region. A sub-channel (e.g., each sub-channel) in the first resource region may occupy a less number of sub-carriers than that in the second resource region. Restricting CCA to the first resource region (e.g., only) may reduce the data transmission overhead.

[0130] In examples, the Sub-Carrier Spacing (SCS) of the first resource region may be larger than that of the second resource region. The resource time unit and/or scheduling unit of the first resource region may be shorter than that of the second resource region. A slot in the first resource region may be shorter than a slot in the second resource region.

[0131] In examples, the SCS of the first and second resource regions may be the same. The number of symbols per resource time unit and/or scheduling unit of the first resource region may be smaller than that of the second resource region. For example, a scheduling unit of the first resource region may occupy 7 OFDM symbols, while a scheduling unit of the second resource region may occupy 14 OFDM symbols. In one or more examples described herein, the SCS of the first resource region may be larger than the SCS of the second resource region. In one or more examples described herein, the SCS of the first and second resource regions may be the same.

[0132] A sub-channel (e.g., each sub-channel) in the first resource region may occupy less subcarriers than a sub-channel (e.g., each sub-channel) in the second resource region. The information to be delivered in a resource in the first resource region may be shorter than that to be delivered in a resource in the second resource region.

[0133] FIG. 9 illustrates an example resource pool configuration. The resource pool configuration may include a partition, for example, for PSSCH and SA/feedback. As shown in FIG. 9, a resource pool configuration 920 may include two regions: resource region 902 and resource region 904. Resource region 902 may include resources that are smaller than the resources in resource region 904. For example, the resources in resource region 902 may have greater granularity in time and/or frequency than the resources in resource region 904. In an example, the subcarrier spacing (SCS) for resource region 904 may be 15 kHz and the resource time unit {e.g., slot) may be 1 ms. The SCS for resource region 902 may be 30 kHz and the resource time unit may be 0.5 ms. A sub-channel in resource region 904 may occupy 12 subcarriers. A sub-channel in resource region 902 may occupy 6 subcarriers. The resources in resource region 902 may be used for transmitting/receiving scheduling assessment (SA) reservation, preemption indication and/or feedback. The resources in resource region 904 may be used for transmitting/receiving data and/or control traffic. As shown in FIG. 9, resource 908 in resource region 904 may be a PSSCH resource. Resource 910 in resource region 904 may be a PSCCH resource. Although the embodiments herein may be described based on the example shown in FIG. 9, it should be appreciated that similar schemes may be applied to other numerologies and sub-channel size assumptions.

[0134] A WTRU may use both resource regions to transmit aperiodic traffic. FIG. 10 depicts an exemplary WTRU implementation of transmitting aperiodic data via cross slot scheduling. A transmitting WTRU may receive a resource pool configuration, for example, having multiple regions such as two regions. If and/or when the transmitting WTRU has aperiodic traffic to send, the transmitting WTRU may select {e.g. firstly) a resource in the second resource region for its control or data transmissions. This resource selection may be based on resource exclusion and/or spectrum sensing approach (e.g., the LTE V2X based). The transmitting WTRU may monitor the traffic in the second resource region and/or may decode the SA reservation message in the first resource region, for example, to achieve comprehensive resource exclusion.

[0135] After selecting a resource in the second resource region, the transmitting WTRU may select a resource in the first resource region for its transmissions of SA reservation. The SA reservation may indicate its control and/or data resource selection decision. The access to the resource in the first resource region may be based on CCA, listen before talk (LBT) or other schemes. The resource for SA reservation transmissions may be a certain number of slots before the resource for control and/or data transmissions. The SA reservation may indicate its feedback resource selection decision. The SA reservation and the data may be multiplexed in frequency. The SA reservation and the control information may be multiplexed in frequency.

[0136] The transmitting WTRU may send the SA reservation over the selected resource in the first resource region. In an example, the transmission of the SA may last 0.5 ms, with the SCS of 30 kHz. The transmitting WTRU may retune to receive and/or monitor the transmissions from other WTRUs on the same resource pool, for example, the resources in both the first resource region and the second resource region. The transmitting WTRU may facilitate future resource selection and/or reservation based on the receiving and/or monitoring of the transmissions from other WTRUs. [0137] If the WTRU does not detect a conflict of using the control and/or data resources it reserved in the SA, the WTRU may continue to use the reserved resource in the second resource region for control and/or data transmissions. For example, additional control information may or may not be added on the data transmissions. If the WTRU detects some conflict of using the resources reserved in the SA, e.g. , via QoS based pre-emption, the WTRU may stop the transmissions in the reserved control or data resource.

[0138] For unicast or groupcast traffic where the ACK/NACK feedback is used, the transmitting WTRU may identify and/or reserve the corresponding feedback resources (e.g., in the first resource region), for a receiving WTRU's feedback message. The reservation information may be included in the SA reservation (e.g., initial SA message). The reservation information may be included in the PSCCFI message associated with data transmissions.

[0139] FIG. 11 illustrates an example of resource usage , e.g., for one or more of aperiodic traffic, bursty traffic, event-driven traffic, or the like. The exemplary resource usage shown in FIG. 11 may be based on the resource pool configuration shown in FIG. 9. As shown in FIG. 11 , a resource pool configuration 1120 may include two regions: resource region 1102 and resource region 1104. As shown in FIG. 11 , WTRU 1122 may use the resource pool configuration 1120 for one or more of the following: scheduling aperiodic traffic (e.g., data and/or control information), transmitting aperiodic data and/or control information, or receiving feedback. As shown in FIG. 11 , WTRU 1122 may be a transmitting WTRU (e.g., a WTRU that transmits aperiodic traffic). As shown in FIG. 11 , WTRU 1122 may receive the resource pool configuration 1120. As shown in FIG. 11 , WTRU 1122 may select a resource in resource pool configuration 1120 for one or more of the following: scheduling aperiodic traffic (e.g., data and/or control information), transmitting aperiodic data and/or control information, or receiving feedback.

[0140] As shown in FIG. 11 , resource region 1102 may include resources that are smaller than the resources in resource region 1104. For example, as shown in FIG. 11 , the resources in resource region 1102 may have different granularity e.g., smaller granularity in time and/or frequency than the resources in resource region 1104. Granularity in time and/or frequency may be based on a variation of one or more of the following: the size of (e.g., the number of subcarriers in) a sub-channel, the numerologies (e.g., subcarrier spacing (SCS)), the resource time unit (e.g., the number of symbols), and/or the like. As shown in FIG. 11 , the SCS for resource region 1104 may be 15 kHz and the resource time unit (e.g., slot) may be 1 ms. As shown in FIG. 11 , the SCS for resource region 1102 may be 30 kHz and the resource time unit may be 0.5 ms. As shown in FIG. 11 , the resource time unit for resource region 1104 may be 14 symbols and the resource time unit for resource region 1102 may be 7 symbols. As shown in FIG. 11 , resource region 1104 may include 3 sub-channels. A sub-channel in resource region 1104 may occupy X subcarriers, for example. As shown in FIG. 11 , resource region 1 102 may include 3 sub-channels. A sub channel in resource region 1 102 may occupy Y subcarriers, where Y is smaller than X for example.

[0141] As shown in FIG. 1 1 , WTRU 1 122 may have aperiodic traffic (e.g., data or control information) to send. For example, as shown in FIG. 1 1 , the aperiodic data may include aperiodic sidelink traffic. As shown in FIG. 1 1 , WTRU 1 122 may determine a resource on which to send the aperiodic sidelink traffic, e.g., based on resource(s) available in resource region 1104. WTRU 1122 may use the determined resource to send the aperiodic sidelink traffic. For example, as shown in FIG. 1 1 , WTRU 1122 may determine to use resource 1 108 to send the aperiodic sidelink data. As shown in FIG. 11 , WTRU 1 122 may reserve resource 1108 by sending scheduling for aperiodic sidelink traffic using resource 1106 (e.g., a scheduling assessment (SA) reservation). The SA reservation may indicate a reservation of resource 1108 in resource region 1104. As shown in FIG. 11 , the SA reservation that was sent using resource 1 106 in resource region 1102 may indicate WTRU 1 122's decision to select the physical sidelink shared channel (PSSCH) resource 1108 in the PSSCH in resource region 1104. A different WTRU, for example, WTRU 1 124, may receive the SA reservation.

[0142] As shown in FIG. 1 1 , WTRU 1122 may select a resource in resource region 1104 for transmitting data and/or control information. WTRU 1122 may select the resource in resource region 1 104, e.g., based on prediction and/or the availability of the resource. As shown in FIG. 1 1 , resource 1108 in resource region 1 104 may be a data resource and may be associated with a data transmission. As shown in FIG. 11 , WTRU 1122 may select resource 1108 for transmitting data traffic. As shown in FIG. 11 , resource 1 108 in resource region 1 104 may be a PSSCH resource. As shown in FIG. 11 , resource 11 10 in resource region 1 104 may be a control resource and may be associated with a control transmission. As shown in FIG. 11 , WTRU 1122 may select resource 1 110 for transmitting control information. As shown in FIG. 1 1 , resource 1 110 in resource region 1104 may be physical sidelink control channel (PSCCFI) resource.

[0143] As shown in FIG.11 , WTRU 1 122 may select resource 1106 in resource region 1102 to transmit SA reservation. As an example, resource 1106 may include a single resource in resource region 1102, as shown in FIG. 1 1. As shown in FIG.11 , resource 1106 in resource region 1102 may last 0.5 ms, for example, if the subcarrier spacing (SCS) for resource region 1 102 is 30 kHz or if the number of symbols is 7. Resource 1106 in resource region 1 102 may last 0.25 ms, for example, if the SCS for resource region 1 102 is 60 kHz or if the number of symbols is 3 or 4.

[0144] WTRU 1 122 may select resource 1106 in resource region 1 102 based on clear channel assessment (CCA) or other schemes including schemes associated with listen before talk (LBT). In an example, WTRU 1122 may use CCA to check whether resource 1106 is occupied by other WTRUs.

WTRU 1122 may initialize a random number or counter. WTRU 1 122 may compare an energy measurement of resource 1106 during CCA with a preconfigured threshold. If WTRU 1122 determines resource 1106 is empty based on the comparison, WTRU 1122 may reduce the random number or counter by one. If WTRU 1122 determines resource 1106 is not empty based on the comparison, the WTRU may retain the random number or counter. WTRU 1122 may use the empty resource 1106 for transmitting SA reservation, for example, if and/or when the random number or counter is 0. A back-off counter may be generated and/or used, for example, within a contention window in case of failure transmissions. In an example, selection of a resource in resource region 1102 may trigger a random back-off for the next channel access attempt.

[0145] As shown in FIG.11 , WTRU 1122 may select resource 1106 in resource region 1102 to transmit an SA reservation. As shown in FIG. 11 , the SA reservation may indicate that WTRU 1122 intends to use resource 1108 to transmit data. The SA reservation may indicate that WTRU 1122 intends to use resource 1110 to transmit control information. As shown in FIG. 11 , the SA reservation may indicate that WTRU 1122 intends to use resource 1112 to receive feedback associated with the data and/or control information. As shown in FIG. 11 , the SA reservation may include a preemption indication, e.g., an indication that the data and/or control information that WTRU 1122 intends to transmit in the determined resource may have higher priority than data and/or control information that other WTRUs intend to transmit in the determined resource. The SA reservation may include information related to preemption indication, for example, quality of service (QoS). A QoS associated with the data or control information may be used to determine the preemption indication.

[0146] As shown in FIG. 11 , WTRU 1122 may tune to a receiving mode, for example, after WTRU 1122 transmits an SA reservation in 1106. As shown in FIG. 11 , WTRU 1122 may tune to a receiving mode for the remaining time of a time slot, e.g., the first 1 ms time slot in resource region 1104. WTRU 1122 may perform energy measurement (e.g., SL-RSRP, SL-RSSI measurement) or decode payload such as decode payload in SCI. As shown in FIG.11 , WTRU 1122 may tune to a receiving mode during RX 1304. As shown in FIG. 11 , RX 1304 may include the remaining time 1114 of the first 1ms time slot in resource region 1104. WTRU 1122 may monitor the resource usage in resource region 1104. In the future resource selection for region 1104, the first 1 ms time slot in resource region 1104 and the periodic extension of the first 1ms time slot may not be excluded from being selected and/or may be selected. WTRU 1122 may track the PSSCH resources corresponding to the remaining time slot, for example, based on RSRP or SL-RSRP and/or RSSI or SL-RSSI measurements. As an example, WTRU 1122 may only track the latter half of the PSSCH resources corresponding to the 0.5 ms of the first 1 ms time slot. RSRP (or SL-RSRP) measurements and/or RSSI (or SL-RSSI) measurements of the PSSCH may be pro-rated, for example, based on the remaining time. WTRU 1122 may monitor (e.g., partially) the resources in resource region 1104, after transmitting the SA message. For example, WTRU 1122 may monitor the second half of the first 1 ms time slot. If resource region 1102 and resource region 1104 have the same numerology, WTRU 1122 may not monitor the resources in region 1104, while transmitting the SA message.

[0147] WTRU 1122 may select a resource in resource region 1102 to receive feedback. As shown in FIG.11 , WTRU 1122 may determine resource 1112 in resource region 1102 to receive feedback. WTRU 1122 may receive feedback using the determined resource 1112 in resource region 1102. As shown in FIG. 11 , WTRU 1122 may receive feedback using resource 1112 in resource region 1102, e.g., after WTRU 1122 transmits aperiodic traffic at 1108 or 1110. The aperiodic traffic at 1108 or 1110 may be unicast or groupcast traffic. The feedback resource 1112 of resource region 1102 may be used for physical sidelink feedback channel (PSFCH) transmission.

[0148] As shown in FIG. 11 , WTRU 1122 may send traffic using the resource 1108 or 1110 selected in resource region 1104. WTRU 1122 may detect a conflict of transmitting traffic using resources 1108 or 1110 that are indicated in the SA reservation. SA reservation may include a preemption indication that is determined based on QoS. As an example, a different WTRU may also reserve resource 1108 . The different WTRU and WTRU 1122 may monitor each other's reservation of resource 1108. If there is no conflict of using resource 1108, WTRU 1122 may continue to use resource 1108. If there is a conflict of using resource 1108, a selection procedure may be implemented by WTRU 1122 and/or the different WTRU, for example, independently. The selection of resource 1108 by WTRU 1122 and/or the different WTRU may depend on the QoS of the data (e.g., the priority of the data and/or the latency requirement of the data). If WTRU 1122 has a higher priority data and/or data associated with lower latency to send, WTRU 1122 may continue to use resource 1108, for example, for the next transmission occasion. If WTRU 1122 has a lower priority data and/or data associated with less stringent latency requirements to send, WTRU 1122 may give up resource 1108 or release resource 1108. The different WTRU may use resource 1108 that is freed up, for example, for the next transmission occasion.

[0149] FIG. 11 may show WTRU 1122’s time line for TX and RX. As shown in FIG. 11 , WTRU 1122 may transmit SA reservation during TX 1302. WTRU 1122 may switch to receiving mode during RX 1304. WTRU 1122 may transmit data or control information during TX 1306. WTRU 1122 may switch to receiving mode during RX 1308.

[0150] FIG. 11 may show WTRU 1124's time line for TX and RX. As shown in FIG. 11 , WTRU 1124 may be a receiving WTRU. As shown in FIG. 11 , WTRU 1124 may be in a receiving mode during RX

1402. During RX 1402, WTRU 1124 may receive the SA reservation using resource 1106, receive the data traffic using resource 1108, and/or receive the control information using resource 1110. WTRU 1124 may switch to transmission mode when transmitting feedback during TX 1404, for example, using resource 1112. WTRU 1124 may switch back to receiving mode during RX 1406.

[0151] A WTRU may receive aperiodic traffic and sending feedback about the aperiodic traffic. FIG. 12 depicts an example of a WTRU receiving aperiodic data and sending feedback. A receiving WTRU may receive the SA reservation in the first resource region. The receiving WTRU may be informed of the upcoming data transmissions in certain data resource in the second resource region, for example, based on the received SA reservation. The receiving WTRU may be informed of the feedback resource {e.g., in the first resource region) reserved by the transmitting WTRU. The receiving WTRU may send ACK/NACK and/or other feedback information (e.g., CSI) using the feedback resource.

[0152] If the receiving WTRU does not detect a conflict of using the data resources reserved in the SA reservation, the receiving WTRU may continue to receive the data transmission in the reserved resource in the second resource region. Additional control information may or may not be added on the data transmissions. If the receiving WTRU detects some conflict of using the resources reserved in the SA reservation, e.g., via (QoS based) pre-emption, the receiving WTRU may stop receiving the data transmissions in the reserved data resource.

[0153] If a receiving WTRU successfully (or unsuccessfully) decodes the data transmissions, the receiving WTRU may send the ACK (or NACK) in the resource in the first resource region, which was reserved by the transmitting WTRU. The CCA or LBT may or may not be applied for this feedback transmission. Not using CCA or LBT on this resource may provide higher priority for the HARQ-ACK feedback transmission than SA reservation transmission.

[0154] The receiving WTRU may tune to transmission mode in a time slot (e.g., the 10^th slot in first resource region shown in FIG. 11) for sending the feedback. The receiving WTRU may monitor the resource usage in the second region for other times, for example, including part of the time slot that the receiving WTRU uses for feedback transmissions (e.g., the 5^th slot in the second region shown in FIG. 11). In future resource selection for the second region, the time slot (e.g., the 5^th slot shown in FIG. 11) and the periodic extension of the time slot may not be considered to be excluded from the selection. The RSRP measurement and/or RSSI measurement of the PSSCFIs may be pro-rated, as the receiving WTRU may track (e.g., only track) the first half (e.g., the first 0.5 ms) of the PSSCH sources. The receiving WTRU may monitor (e.g., partially) the resources in the second resource region, while transmitting the feedback message. The first resource region and the second resource region may have the same numerology. The receiving WTRU may not monitor the resources in the second resource region, while transmitting the feedback message if and/or when the first resource region and the second resource region have the same numerology. The receiving WTRU's time line for TX and RX may be as shown in FIG. 11 (e.g., 1402-1406). [0155] Schemes associated with resource allocation may include handling of data associated with relatively high priority and/or relatively low latency requirements. The lowest latency requirement of the data may be 10 ms, for example, in LTE V2X. In NR V2X, the lowest latency requirement may be 3 ms. A first WTRU may sense the resources and/or may select a resource with a relatively good (e.g., the best) condition, for example, to achieve the low latency data transmission. The first WTRU may be a NR mode 2 WTRU. If and/or when the resources in the selection window are not vacant, the first WTRU may pre-empt some other WTRU's (e.g., a second WTRU's) reserved resource for relatively low priority or relatively high latency data. The first WTRU may offer its future reserved resource (e.g., SPS reservation or autonomous reservation) to a second WTRU, for example, to compensate for pre-empting the second WTRU. The future reserved resource for the first WTRU may satisfy the QoS requirement of the second WTRU's data. This resource exchange message may be delivered to the second WTRU, for example, in a pre-emption message.

[0156] In an example, the first WTRU may boost its transmission power for its relatively high priority and/or relatively low latency data. This transmission may over-write the second WTRU's scheduled transmissions. The first WTRU may compensate for the second WTRU by notifying the second WTRU about the first WTRU's future reserved resource(s), which satisfies the QoS requirement of the second WTRU's data. In an example, this notification may happen after the first WTRU transmits its relatively high priority or relatively low latency data.

[0157] FIG. 13 depicts an example of resource exchange. WTRU 1334 and WTRU 1336 may have respective reserved periodic resources. WTRU 1334 may have relatively high priority and/or relatively low latency data to send. Using WTRU 1334's next reserved resource may exceed the data's delay budget. Based on resource selection, WTRU 1334 may be informed that WTRU 1336 reserved some resources for relatively low priority data transmissions, and WTRU 1336's resource is within the delay budget of WTRU 1334’s data. WTRU 1334 may send a resource exchange indication to WTRU 1336. The resource exchange indication may be used to propose to exchange WTRU 1334's next reserved resource with WTRU 1336 's next reserved resource.

[0158] If the resource exchange indication can reach WTRU 1336 before its next reserved resource, then WTRU 1336 may send its data in WTRU 1334's next reserved resource. If the resource exchange indication cannot reach WTRU 1336 before its next reserved resource, then WTRU 1336 may send its data in its next scheduled resource. In this case, WTRU 1334 may boost its transmission power to overwrite WTRU 1336's transmissions. In an example, WTRU 1334 may indicate the resource exchange associated with WTRU 1334's data transmission so that the targeted WTRU 1336's receivers may learn the changes and wait for the data transmissions from WTRU 1336 on WTRU 1334's next reserved resource. Later when WTRU 1336 receives the resource exchange indication from WTRU 1334, WTRU 1336 may resend its data in WTRU 1334's next reserved resource.

[0159] Schemes associated with resource allocation may include resource allocation for relatively large packets. The packet size in NR V2X sidelink transmissions may be larger than the packet size in LTE V2X sidelink transmissions. For transmitting the larger-size packets, more resources may be used. To transmit the larger-size packets in one shot, multiple continuous {e.g., in frequency domain) resources may be reserved simultaneously. Reserving multiple continuous resources may increase the collision chance and/or may congest the channel. A maximum number of resources (e.g., in frequency domain) may be determined. A WTRU may be restricted by the maximum number of resources. The maximum number or resources may be less than the total number of available resources in a resource pool or bandwidth part (BWP). The maximum number of frequency domain resources may depend on the number of WTRUs in the current zone, WTRU category/capability, and/or data QoS (e.g., priority).

[0160] The WTRU may segment the packet. For example, the WTRU may segment the packet based on the maximum allowed number of frequency-domain resources a WTRU may reserve at each slot. Code Block Group (CBG) based transmissions may be applied in the case of unicast or groupcast sidelink .

[0161] The resource selection within a given selection window may be more than 2 resources for a large packet size, for example, for NR mode 2 WTRU. The NR mode 2 WTRU may select multiple resources to transmit a large packet. A selected resource (e.g., each selected resource) may include different portions of the coded bits. A selected resource (e.g., each selected resource) may include the coded bits for different CBs or CBGs. Multiple selected resources may be for repetition, e.g., in LTE V2X.

[0162] A WTRU (e.g., mode 1 WTRU) may perform data transmissions with more than one retransmission.

[0163] In one or more examples herein, initial transmission may be used interchangeably with first transmission, second transmission may be used interchangeably with first retransmission, third transmission may be used interchangeably with second retransmission, and fourth transmission may be used interchangeably with third retransmission.

[0164] More than one retransmission may be supported, for example, via DCI signalling. In NR V2X, the number of retransmissions may be more than 1 , for example, to increase the reliability level of PSSCH transmissions. The number of data retransmissions may be dependent on data's QoS for NR mode 2 WTRU. The number of data retransmission may be indicated by DCI from gNB. The number of retransmissions may be dynamically determined. [0165] The number and resources for data retransmissions (e.g., in PSCCH) may be indicated. For example, DCI signalling schemes may be used to support two or more retransmissions in NR V2X.

[0166] FIG. 14 depicts an exemplary mode 1 WTRU PSSCH transmission. A mode 1 WTRU may receive {e.g., first obtain) a sidelink transmission grant from gNB. The sidelink transmission grant may be in DCI (e.g., NR DCI) format. NR DCI format may include NR SCI format fields with two independent sets of information. The first set of information may include one or more of the following. The first set of information may include frequency resource location of initial transmission and the first retransmission.

The frequency resource location of initial transmission and retransmission may be equal to RIV of the initial and the first retransmission. The frequency resource location of initial transmission and retransmission may be used to demeL_{subCH 1} the number of contiguously allocated sub-channels and/or nf^_{bCH,! '} the starting sub-channel index (of the first retransmission). The first set of information may include a time gap between initial transmission and retransmission, SF_{gap l}.

[0167] The second set of information may include one or more of the following. The second set of information may include a frequency resource location of the first retransmission and the second retransmission. The frequency resource location of the first retransmission and the second retransmission may be equal to RIV of the first retransmission and the second retransmission. The frequency resource location of the first retransmission and the second retransmission may be used to derive L_subCH,2 : the number of contiguously allocated sub-channels and/or nfu_bCH^ ^: the starting sub-channel index (of the second retransmission). The second set of information may include a time gap between the first retransmission and the second retransmission, SF_{gap 2}.

[0168] A NR DCI format may include NR SCI format fields with a set (e.g., single set) of information. It is possible that

the case of subCH.i = subCH,2 = subCH . the L_subCH, c_H.r and n ¾₂ may be jointly encoded to a single RIV. The bits representing nfu_bCH.i and nfu_bCH^ may he concatenated to determine nf^_bCH =

NsubCH, i \\ⁿs^SubCH, · A single RIV may be generated to

[0169] A NR DCI format may include NR SCI format fields with multiple (e.g., two) correlated sets of information. In the case of L_{subCH 1} = L_{subCH 2} = L_Su_bCH< ^{a wa}Y to construct NR DCI format may be to have two parts of information. The first part of information may include a frequency resource location of the initial transmission and the first retransmission. The frequency resource location of the initial transmission and the first retransmission may be equal to RIV of the initial and the first retransmission. The frequency resource location of the initial transmission and the first retransmission may be used to derive _sui>c//: the number of contiguously allocated sub-channels and/or nf ¾¾_/,i ^: the starting sub-channel index (of the first retransmission). The frequency resource location of the initial and the first retransmission may be used to derive a time gap between initial transmission and the first retransmission, SF_{gap l}.

[0170] The second part of information may include a starting sub-channel index (e.g., of the second retransmission) n_s ^s^_bc_H,2 The second part of information may include a time gap between the first retransmission and the second retransmission, SF_{gap 2}

[0171] The mode 1 WTRU may determine the total number of retransmissions, for example, based on SF_{gaP i} and SF_{gap 2} included in the DCI format. In an example,, if SF_{gap l} = 0, the number of sidelink transmission may be equal to 1 ; if SF_{gap l} > 0, SF_{gap 2} = 0, the number of sidelink transmission may be equal to 2; if SF_{gap l} > 0 , SF_{gap 2} > 0, the number of sidelink transmission may be equal to 3.

[0172] If the number of sidelink data retransmissions is equal to 0 or 1 , the WTRU may determine the time and/or frequency resources for the two PSSCH based on L_{subCH 1} , nf^_bcii_{, t}, and/or SF_{gap l}. If the number of sidelink data retransmissions is equal to 2, the WTRU may determine the time and/or frequency resources for the third PSSCH from L_{subCH 2} , n¾, and/or SF_{gaP 2}.

[0173] The time unit for an NR resource (e.g., each NR resource) may be in terms of slot or sub-slot.

Slot may be used herein as a unit. Slot may be used interchangeable with sub-slot in one or more examples herein.

[0174] A WTRU may send and/or receive data with 3 or more retransmissions. NR V2X PSSCH transmission may support 3 or more retransmissions. In examples, the WTRU sending and/or receiving data with 3 or more retransmissions may follow the example in FIG. 14. For mode 1 WTRUs, the NR DCI format may include NR SCI format fields with three or more independent sets of information. An independent set (e.g., each independent set) of information may include {L_{subCH i}, n_s ^s^_bc_{H i}, SF_{gap i}), i = 1,2,3.

[0175] In the case of L_subCH,i = L_subCH,2 = _su_bCH.3 = ^_su_bCH . e.g., all the transmissions having the same number of sub-channels, the NR DCI format may be alternatively constructed to have three dependent sets of information. The first set of information may include {L_{subCH 1}

SFg_{ap l}), and the last two sets of information may include {n^c_H.o SF_gap,d_< i=2,3.

[0176] FIG. 15 depicts exemplary WTRU data transmissions with more than one retransmission. A WTRU (e.g., a vehicle WTRU) may be configured via RRC signaling for the support of more than 1 retransmission. The data transmissions with more than 1 retransmission may involve the RRC configuration parameter setting. In the IE of "SL-PSSCH-TxParameters”, there may be a parameter of "allowedRetxNumberPSSCH” which may be set to n₀ (no retransmission),

(one retransmission), or both (e.g., in LTE V2X). How many retransmissions are supported in the RRC configuration may be indicated using a bitmap. For the case of up to 3 retransmissions (e.g., a total of 4 transmissions), 4 bits may be used to indicate whether 1) no retransmission, 2) one re-transmission, 3) two retransmissions, or 4) three retransmissions are supported. This is shown in the following example.

SL-PSSCH-TxParameters: := SEQUENCE {

allowedRetxNumberPSSCH SEQUENCE (size(maxSL-Retx-Number)) OF BOOLEAN,

}

maxSL-Retx-Number = INTEGER(0..8);

[0177] After configuration, the WTRU may receive some data for transmission. If the WTRU is a mode 1 WTRU, it may receive DCI from gNB with the sidelink grant information. The details of this DCI information are discussed in one or more examples herein. Based on the network dynamically assigned resources, the WTRU may determine the resources for its sidelink (re)transmission(s) and used the determined resources based on received DCI. If the WTRU is a mode 2 WTRU, the WTRU may dynamically determine the resource for its sidelink (re)transmission(s), for example, based on spectrum sensing and used the determined resource for its SL (re)transmission(s). The WTRU may set SCI fields for a (re)transmission (e.g., each (re)transmission). The WTRU may transmit PSSCH for a (re)transmission (e.g., each

(re)transmission).

[0178] A WTRU may follow an implementation (e.g., example shown in FIG. 16) for receiving data. FIG. 16 depicts an example decoding of PSSCH data by a receiving WTRU. Based on the SCI signalling, a receiving WTRU may have the following implementation of decoding the transport block (TB) carried by multiple PSSCH transmission. The receiving WTRU may decode a SCI and may determine the resources for the current PSSCH transmission. The receiving WTRU may decode the PSSCH with or without the combination of the currently received PSSCH and any of previously received PSSCH signal, for example, depending on the combining indicator value. The combining indicator may be initialized to 0. [0179] If the decoding is successful, the receiving WTRU may declare the decoding successful. If the decoding is unsuccessful, the receiving WTRU may decide whether there are any further retransmissions of the same TB, for example, based on some SCI signalling schemes. The decision of whether the current SL transmission is the last transmission may depend on the applied SCI signalling scheme. For an example SCI signalling scheme, the current SL transmission may be determined to be the last transmission if SF_gap is equal to 0 and/or the "Retransmission index” is set to 1. For an example SCI signalling scheme, the current SL transmission may be determined to be the last transmission if SF_gap is equal to 0.

[0180] If no more retransmissions are scheduled, the receiving WTRU may declare the decoding failed. Otherwise, the receiving WTRU may calculate the resources for the next retransmission, for example, based on some SCI signalling schemes. The receiving WTRU may set the combining indicator as 1. Once, it receives the next PSSCH transmissions, the receiving WTRU may apply the combining before the PSSCH decoding.

[0181] The receiving WTRU may set the SCI for a (re)transmission (e.g., each (re)transmission) according to the schemes, as described herein. The receiving WTRU may put the data in the determined resources, with redundancy versions of the data for initial transmission or retransmissions as described herein.

[0182] Some or all the retransmissions may have the same contents, e.g,, the FIARQ-Chase Combining (CC).

[0183] Different redundancy versions may be used for 2 or 3 retransmissions.

[0184] If there are 2 retransmissions in NR V2X sidelink, the 2 retransmissions may include the same modulation symbols as the initial transmissions. Chase combining may be performed at the receiver side.

[0185] In examples, an initial transmission may include the RV0 with natural order modulation mapping. A first retransmission may include the RV0 with reverse order modulation mapping. A second

retransmission may include the RV0 with natural order modulation mapping. As an example,

b₀, b_lt b₂, b₃, b₄, b₅ may be 6 continuous rate matched bits to be transmitted. The natural order modulation mapping may convert {b₀, b_lt b₂, b₃, b₄, b₅) to a 64QAM symbol. The reverse order modulation mapping may convert (b₅, b₄, b₃, b₂, b_t, b₀) to a 64QAM symbol. The same mapping may be applied to other modulation orders.

[0186] In examples, an initial transmission may include the RV0 with natural order modulation mapping. A first retransmission may include the RV0 with 2-bit shift modulation mapping. A second retransmission may include the RV0 with 4-bit shift modulation mapping. As an example, b₀, b_lt b₂, b₃, b₄, b₅ may be 6 continuous rate matched bits to be transmitted. The 2-bit shift modulation mapping may convert

( b₂ , b₃, b₄, b_s, b₀, b_j) to a 64QAM symbol. The 4-bit shift modulation mapping may convert

(b₄, b₅, b₀, b_t, b₂, b₃) to a 64QAM symbol. The same mapping may be applied to other modulation orders.

[0187] In examples, an initial transmission may include RVO. A first retransmission may include RV2. A second retransmission may include RV3. The initial transmission, the first retransmission, and/or the second retransmission may include the natural order modulation mapping, reverse order modulation mapping, or other modulation mapping schemes.

[0188] RV schemes may be indicated in various ways. The RV version and/or modulation mapping of a (re)transmission (e.g., each (re)transmission) may be pre-determined and/or fixed, e.g., one of the schemes described herein may be used for all the cases. The RV pattern may be configured, e.g., RRC configuration. The contents of a transmission(s) (e.g., each transmission(s)) may be dynamically determined. For example, the scheme index may be included in the SCI.

[0189] The RV version may be associated with a "Retransmission index”, where the HARQ-IR

(Incremental Redundancy) combination scheme is applied. The selection between HARQ-IR and HARQ- CC may be determined, for example, through higher layer configuration and/or through a single bit indication in SCI.

[0190] The RV version may be associated with the "Time gap between current Tx and neighbour Tx”, e.g., in the SCI information. For example, in some SCI signaling schemes, the "Time gap between current Tx and neighbor Tx” equal to 0, SF_gap or SF_{gap l} may indicate that the RV version is 0, the "Time gap between current Tx and neighbor Tx” equal to SF_{gap 2} may indicate the RV version is 2, the "Time gap between current Tx and neighbor Tx” equal to SF_{gap 3} may indicate the RV version is 3.

[0191] The RV version may be associated with the "Time gap between current Tx and neighbour Tx” and the "Retransmission index” jointly. For example, in some SCI signaling schemes, the "Time gap between current Tx and neighbor Tx” equal to SF_gap and the "Retransmission index” equal to 0 may indicate that the RV version is 0, the "Time gap between current Tx and neighbor Tx” equal to SF_gap and the "Retransmission index” equal to 1 may indicate that the RV version is 2, etc.

[0192] A mode 2 WTRU may implement resource selection for higher data rates. In an example, PSSCH resource selection may be modified for a NR V2X mode 2 WTRU.

[0193] Multi-slot resources may be used for higher data rates. The resources for sidelink PSSCH transmissions may be single-subframe resources, e.g., in LTE. A resource (e.g., each resource) may be composed of the l_subCH contiguous sub-channels over a single subframe. A subchannel (e.g., each subchannel) may be composed of several contiguous resource blocks.

[0194] A resource for NR PSSCH may be across multiple slots, for example, to support increased data rate for NR sidelink. As an example, L_{subCH max} may denote the maximum number of subchannels in a BWP. A candidate multi-slot resource for PSSCH transmission may be defined as a set of L_subCH sub channels, denoted by R_{x y}. The candidate multi-slot resource may include for j = 0, ... , L_subCH— 1, the sub-channels (x + j ) mod L_{subCH max} in subframe t_y ^L +

[0195] Flexible and/or configurable thresholds may be used for resource filtering. Different use cases may have different latency and reliability requirements, for example, in NR. Some use cases may be associated with a higher reliability requirement than others.

[0196] A fixed threshold of 0.2 may be used to define a lower bound on the cardinality of S_A in Step 4, e.g., in LTE. The fixed threshold may be associated with the WTRU capability and/or data rate requirement. In examples, for a WTRU with higher data rate requirements, the fixed threshold may be lower such that the selected resources in S_A may have better SNR conditions which support the higher MCS index. For a WTRU with more capability, the fixed threshold may be higher such that more selected resources may be included in S_A, which uses more WTRU tracking capabilities.

[0197] A fixed RSRP threshold may be used to increase granularity (e.g., 3 dB) in Step 4, e.g., in LTE. The granularity may be associated with WTRU capability. In examples, for a WTRU with more capability, the granularity may be larger such that more candidate resources may be included in S_A, which uses more WTRU tracking capability.

[0198] A fixed threshold of 0.2 may be used to define a lower bound on the cardinality of S_B in Step 5, e.g., in LTE. The fixed threshold may be associated with WTRU capability and/or a data (e.g., use case) reliability requirement. In examples, for a use case with higher data reliability requirements, the fixed threshold may be lower such that the reported resources in S_B may have lower noise/interference power, which supports more reliable delivery of the data. For a WTRU with more capability, the fixed threshold may be higher such that more resources may be reported to a higher layer for its final decision, which uses more WTRU computational capabilities.

[0199] One or more of the thresholds, as described herein, may be configured via high layer signaling and/or physical layer signaling. [0200] Although the features and elements are described in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements.

[0201] Although the solutions described herein consider New Radio (NR), 5G or LTE, LTE-A specific protocols, it is understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

Claims

What is Claimed:

1 A wireless transmit/receive unit (WTRU) with aperiodic sidelink traffic to send, comprising:

a processor configured to:

receive a resource pool configuration comprising a first region and a second region, wherein resources in the first region are smaller than resources in the second region;

select, a second resource in the second region, wherein the second resource in the second region is at least one of a data resource or a control resource, wherein the data resource is associated with a data transmission and the control resource is associated with a control transmission;

select a first resource of the first region based on clear channel assessment (CCA) sensing;

transmit a scheduling assessment (SA) reservation using the selected first resource of the first region, wherein the SA reservation indicates a reservation of the second resource in the second region; and

send the data transmission or the control transmission using the second resource in the second region based on the indicated reservation of the second resource in the second region.

2. The WTRU of claim 1 , wherein the SA reservation indicates a reservation of a third resource of the first region, the third resource of the first region being associated with feedback, wherein the processor is further configured to receive the feedback based on the indicated reservation of the third resource of the first region associated with the feedback.

3. The WTRU of claim 1 , wherein a resource in the first region is associated with a smaller time or frequency granularity than a resource in the second region, the granularity being based on at least one of numerologies, a number of symbols, and sizes of subchannels.

4. The WTRU of claim 1 , wherein the SA reservation further comprises quality of service (QoS) information used for a determination of a preemption.

5. The WTRU of claim 3, wherein the processor is further configured to determine that the data transmission or the control transmission is associated with a higher priority or lower latency requirement than a data transmission or a control transmission that another WTRU intends to perform using the data resource or the control resource in the second region.

6. The WTRU of claim 1 , wherein the data resource is used for physical sidelink shared channel (PSSCH) transmission, and the control resource is used for physical sidelink control channel (PSCCH) transmission.

7. The WTRU of claim 1 , wherein the SA reservation and the data information are multiplexed in frequency, or the SA reservation and the control information are multiplexed in frequency.

8 The WTRU of claim 1 , wherein the processor is further configured to:

transmit in a part of a time unit, the time unit being associated with the second region; and monitor in a remaining part of the time unit.

9. The WTRU of claim 1 , wherein the selection of the first resource of the first region based on CCA sensing triggers a random back-off for a next channel access attempt.

10. A method, comprising:

receiving a resource pool configuration comprising a first region and a second region, wherein resources in the first region are smaller than resources in the second region;

selecting, a second resource in the second region, wherein the second resource in the second region is at least one of a data resource or a control resource, wherein the data resource is associated with a data transmission and the control resource is associated with a control transmission;

selecting a first resource of the first region based on clear channel assessment (CCA) sensing;

transmitting a scheduling assessment (SA) reservation using the selected first resource of the first region, wherein the SA reservation indicates a reservation of the second resource in the second region; and

sending the data transmission or the control transmission using the second resource in the second region based on the indicated reservation of the second resource in the second region.

11. The method of claim 10, wherein the SA reservation indicates a reservation of a third resource of the first region, the third resource of the first region being associated with feedback, the method further comprising receiving the feedback based on the indicated reservation of the third resource of the first region associated with the feedback.

12. The method of claim 10, wherein a resource in the first region is associated with a smaller time or frequency granularity than a resource in the second region, the granularity being based on numerologies, a number of symbols, and sizes of subchannels.

13. The method of claim 10, wherein the SA reservation further comprises quality of service (QoS) information used for determining a preemption.

14. The method of claim 13, further comprising determining that the data transmission or the control transmission is associated with a higher priority or lower latency requirement than a data transmission or a control transmission that another WTRU intends to perform using the data resource or the control resource in the second region.

15. The method of claim 10, wherein the data resource is used for physical sidelink shared channel (PSSCH) transmission, and the control resource is used for physical sidelink control channel (PSCCH) transmission.