WO2020068906A1

WO2020068906A1 - Wtru autonomous beamformed unicast transmission

Info

Publication number: WO2020068906A1
Application number: PCT/US2019/052837
Authority: WO
Inventors: Tao Deng; Martino M. Freda; Tuong Duc HOANG; Aata EL HAMSS; Moon-Il Lee; Chunxuan Ye
Original assignee: Idac Holdings, Inc.
Priority date: 2018-09-25
Filing date: 2019-09-25
Publication date: 2020-04-02

Abstract

WTRU autonomous sidelink (SL) unicast transmission beam management may be performed. A WTRU may be configured to receive a channel state information (CSI) configuration. The CSI configuration may indicate a CSI reference signal (CSI-RS) transmission configuration and a CSI reporting configuration. The CSI-RS transmission configuration may indicate a CSI-RS transmission window. The WTRU may be configured to select a first resource for a CSI-RS transmission. The selected first resource may be within the CSI-RS transmission window. The WTRU may be configured to determine a CSI transmission window, for example, based on one or more of the CSI reporting configuration, a processing capability of a peer WTRU, a minimum communication range, estimated channel information, or a quality of service (QoS) parameter. The WTRU may be configured to select a second resource to receive a CSI report. The second resource may be within the determined CSI transmission window.

Description

WTRU AUTONOMOUS BEAMFORMED UNICAST TRANSMISSION

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62/735,995, filed on September 25, 2018; U.S. Provisional Patent Application No. 62/789,798, filed on January 8, 2019; and U.S. Provisional Patent Application No. 62/886,583, filed on August 14, 2019; the contents of which are hereby incorporated by reference herein in their entireties.

BACKGROUND

[0002] Mobile communications using wireless communication continue to evolve. A fifth generation may be referred to as 5G. A previous (legacy) generation of mobile communication may be, for example, fourth generation (4G) long term evolution (LTE).

SUMMARY

[0003] Systems, methods, and instrumentalities for wireless transmit/receive unit (WTRU) autonomous beamformed unicast transmission may be disclosed herein. A WTRU may be configured to receive a channel state information (CSI) configuration, for example, from a network. The CSI configuration may be a device-to-device (D2D) and/or a vehicular communications (V2X) CSI configuration. The CSI configuration may indicate a CSI reference signal (CSI-RS) transmission configuration and a CSI reporting configuration. The CSI reporting configuration may be associated with the CSI-RS transmission configuration. The CSI-RS transmission configuration may indicate a CSI-RS transmission window. The WTRU may be configured to select a first resource for a CSI-RS transmission. The selected first resource may be within the CSI-RS transmission window. The CSI-RS transmission window may include one or more of a time period during which a CSI-RS transmission may be sent and/or a time during which feedback based on the CSI-RS transmission may be received. The WTRU may be configured to determine a CSI transmission window, for example, based on one or more of the CSI reporting configuration, a processing capability of a peer WTRU, a minimum communication range, estimated channel information, or a quality of service (QoS) parameter. Determining the CSI transmission window may include determining a CSI transmission window start time and a CSI transmission window duration. [0004] The WTRU may be configured to select a second resource to receive a CSI report. The second resource may be within the CSI transmission window. The selected second resource may be an earliest available resource in the CSI transmission window. The selected second resource may be associated with the sub-channel of the selected first resource. For example, the selected second resource may be in the same sub-channel as the selected first resource. The selected second resource may be an earliest available resource in the CSI transmission window that is in the same sub-channel as the selected first resource. The selected second resource may be separated in time from the selected first resource by less than a duration of the CSI transmission window. The WTRU may be configured to send a CSI-RS transmission in the selected first resource. The WTRU may be configured to receive a CSI report in the selected second resource. The WTRU may be configured to send sidelink control information (SCI). The SCI may indicate the selected second resource. The WTRU may be configured to send CSI information {e.g., such as the CSI report) in a Physical Sidelink Shared Channel (PSSCH) using the selected second resource. The WTRU may be configured to perform beam management during the CSI transmission window.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0006] 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.

[0007] FIG. 1 C 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.

[0008] 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.

[0009] FIG. 2 shows an example channel state information (CSI) reference signal (CSI-RS) resource and CSI reporting resource selection 200.

[0010] FIG. 3 shows an example of new radio (NR) vehicular communication (V2X) WTRU autonomous unicast beamformed reference signal transmission.

[0011] FIG. 4 shows an example of NR V2X WTRU autonomous beam initiation for sidelink (SL) unicast transmission. [0012] FIG. 5 shows an example of NR V2X WTRU autonomous beam re-selection for SL unicast transmission.

DETAILED DESCRIPTION

[0013] 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.

[0014] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/1 13, a ON 106/1 15, 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.

[0015] The communications systems 100 may also include a base station 114a and/or a base station 1 14b. Each of the base stations 1 14a, 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.

[0016] 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.

[0017] 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).

[0018] 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 115/116/117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0019] 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).

[0020] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0021] 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).

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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)). [0037] FIG. 1 C 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 1 16. The RAN 104 may also be in communication with the CN 106.

[0038] 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 1 16. 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.

[0039] 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. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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. 10044] 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.

[0045] 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.

[0046] In representative embodiments, the other network 112 may be a WLAN.

[0047] 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.

[0048] 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

- IQ - 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.

[0049] 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.

[0050] 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).

[0051] 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).

[0052] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 h, 802.11 ac, 802.11 af, and 802.11ah, 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.

[0053] 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.

[0054] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 1 15 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.

[0055] 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).

[0056] 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).

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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. [0061] 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.

[0062] 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.

[0063] The CN 115 may facilitate communications with other networks. For example, the CN 1 15 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 1 15 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 1 12, 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.

[0064] 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 1 14a-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.

[0065] 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.

[0066] 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.

[0067] Vehicular communication (V2X) sidelink (SL) unicast transmission may be performed in LTE- based systems. LTE V2X transmission bandwidth may be, for example, 10 MHz or 20 MHz. LTE V2X message payload requirements may be, for example, 50-300 bytes (e.g., for periodic traffic) and/or up to 1200 bytes (e.g., for event-triggered traffic). LTE may support unicast transmission based on, for example, a service ID on an application layer. A V2X wireless transmit/receive unit (WTRU) (e.g., each V2X WTRU) may decode SL data and may obtain the service ID. The service ID may be used by the application layer to determine whether the transmission is a broadcast or unicast transmission intended for the WTRU.

[0068] At lower layers, a WTRU may handle SL transmissions (e.g., all SL transmissions) in a similar (e.g., identical) manner regardless of whether the transmission is unicast or broadcast. The WTRU may perform SL transmission and reception without knowledge at lower layers (e.g., PHY, MAC, etc.) regarding the transmission type, transmission destination, link quality, etc.

[0069] NR V2X SL beamformed transmissions may occur. NR V2X SL may support high-throughput and low-latency transmissions. For example, a periodic packet size may range between 30,000 and 60,000 bytes and latency may be as low as 3 ms in certain use cases (e.g., advanced use cases). A NR V2X SL study may include SL frequencies for FR2 (e.g., up to 52.6 GHz), for example to take advantage of the large bandwidth available at FR2 frequencies and short transmission duration (e.g., due to large sub-carrier spacings applied at these frequencies).

[0070] Analogue and digital beamforming techniques may be supported in NR V2X SL transmission, for example to compensate for high path loss at FR2 frequencies. The NR V2X SL beamforming design may inherently leverage the beam-based NR Uu design and enhance with SL-specific features. Enhancements may include, for example, enablement for a beamformed unicast transmission between two NR V2X UEs (e.g., without gNB involvement). As exemplified in the unified NR Uu design framework between below- and above-6 GHz frequencies, a common NR V2X SL design for both FR1 and FR2 frequencies may ensure flexible and efficient resource utilization while providing required performance.

[0071] Lower layer beam management may be performed, for example, without centralized coordination. Beam management may involve a sequence including, for example, beam sweeping, measurement and feedback {e.g., as demonstrated in NR Uu beam-based design), which may be coordinated by a centralized scheduler (e.g., a gNB). The beam managements may be performed at MAC/PHY layer to reduce latency.

[0072] As described herein, NR V2X SL operations may be beam-based, with beam management tailored for SL operation. There may be no lower layer beam-management in V2X systems. In Mode 2 transmission, NR V2X WTRUs may schedule and perform transmissions without gNB involvement.

MAC/PHY mechanisms may be used for NR V2X SL to enable WTRUs to autonomously perform beam management, e.g. to establish a beam pair for a unicast transmission without centralized coordination.

[0073] Signaling overhead and latency may be higher for unicast transmission establishment. NR V2X higher layer design may include implementations to establish a radio bearer for a unicast transmission between two NR V2X WTRUs. The resulting signaling overhead may be high and may incur additional latency. It may be desirable for NR V2X WTRUs to not perform establishment every time a unicast transmission packet arrives. It may be helpful that lower layers maintain the established unicast transmission link (e.g., re-establishment of a beam pair) based on, for example, real-time monitoring, and provide a higher layer with a related status notification.

[0074] A NR V2X WTRU may perform autonomous initiation for a beamformed unicast transmission. A WTRU may determine resources for SL reference signal transmission and associated feedback transmission. For example, a WTRU may determine an SL reference signal (RS) time and frequency resource pool. As used herein, a unicast SL reference signal may be referred to as an SL feedback reference signal (SFRS), and the two terms may be interchangeable. A WTRU may determine a SL time resource pool for unicast SL reference signal transmission based on, for example, UL and/or flexible symbols configured in a system broadcast information. For example, a WTRU may determine a slot-based SL time resource pool based on configured uplink (UL) slots for unicast SL reference signal transmission. For example, a WTRU may determine a slot-based SL time resource pool based on configured flexible slots for unicast SL reference signal transmission.

[0075] WTRU autonomous SL unicast transmission beam management may be performed, for example including beam pair establishment, monitoring and/or maintenance. A WTRU may perform autonomous SL channel state information (CSI) requesting, scheduling and/or reporting. [0076] A WTRU may determine an SL feedback reference signal (SFRS) transmission resource based on one or more configured {e.g., pre-configured) SFRS resources and their association with an SFRS measurement type, QoS, channel condition, etc. A WTRU may determine associated feedback transmission resources, for example including a feedback transmission window and/or a window duration based on a QoS requirement, channel condition(s), a CSI measurement type, etc. A WTRU may perform unicast data transmission. The WTRU may perform unicast data transmission based on a received SFRS transmission, for example, without using feedback information due to channel reciprocity.

[0077] A WTRU may (e.g., implicitly and/or explicitly) schedule a beam specific reference signal transmission and an associated CSI feedback transmission, e.g. within a CSI monitoring window. A WTRU may determine beam link quality and/or failure, for example based on a timer. The timer's expiration may be determined based on, for example the beam link property, measurement and/or WTRU mobility information. A flexible SL time resource may be configured for reference signal transmission, for example allowing beam sweeping within an (e.g., one) sensing resource. A WTRU may reconfigure a spatial domain transmission filter (e.g., a beam switch) based on, for example, feedback and/or link monitoring.

[0078] A WTRU may determine to turn CSI reporting on/off, for example, based on a WTRU Tx-Rx distance and/or a minimum communication range (MCR). A WTRU may drop a feedback transmission, for example, when no available resource is identified within a determined feedback transmission window, followed by an indication transmission and/or a CSI request. A WTRU may multiplex a CSI reporting with a PSSCH transmission. A WTRU may perform a unicast data transmission that is associated with an SFRS transmission.

[0079] A WTRU may be configured with one or more frequency resources allocated for unicast SL transmission. For example, a WTRU may be configured with a set of BWPs for unicast SL transmission. A WTRU may be configured with a set of frequency resource pools for unicast SL transmissions. Within a unicast transmission frequency resource allocation, a WTRU may be configured with a number of sets of unicast reference signal transmission frequency resources in terms of, for example, sub-carriers, sub carrier blocks, sub-channels, etc. For example, the WTRU may be configured with the sets of unicast reference signal transmission frequency resources for each unicast transmission frequency resource allocation. A set (e.g., each set) of unicast reference signal frequency resource may include a number of, for example, sub-carriers, sub-carrier blocks, and/or sub-channels that may be allocated in a fixed pattern. For example, a (e.g. one) unicast reference signal frequency resource set may include one or more (e.g., two) sub-carrier blocks. A unicast reference signal frequency resource set (e.g., each set) may have an index that may indicate its location within a configured unicast BWP or uncast frequency resource pool. [0080] A WTRU may be configured with one or more SFRS resources. An SFRS resource may be associated with an SL feedback (SLFB) measurement type. A WTRU may be configured {e.g., pre configured) with a set of SL resource pools for unicast transmissions. The WTRU may determine a resource pool from the SL resource pool set to use for a unicast transmission based on, for example, one or more QoS requirements of the unicast transmission and/or based on one or more other transmission characteristics of the unicast transmission. The one or more QoS requirements may include, for example, link capacity, reliability, latency, range, etc.

[0081] A WTRU may be configured by a network entity and/or may be preconfigured (e.g., at manufacture). A WTRU may be pre-configured with information that the WTRU acquires without a network connection. For example, an out-of-coverage V2X WTRU may operate in Mode 2 and may acquire a V2X configuration from a memory storage located within the WTRU. A WTRU may be configured with information that the WTRU receives from the network via an established radio link. For example, an in coverage V2X WTRU may operate in Mode 1 and may receive a V2X configuration in the downlink signaling (e.g., SIB, RRC, MAC CE, etc.). The V2X configuration may be a device-to-device (D2D) configuration. The V2X configuration may be a CSI configuration that may include feedback information. For example, the V2X configuration may include a reference signal configuration and/or a feedback reporting configuration. A WTRU may receive a feedback configuration (e.g., the V2X configuration). The WTRU may receive the feedback configuration from the network, e.g., via downlink signaling (e.g., RRC signaling). The feedback configuration may indicate a reference signal configuration (e.g., CSI-RS transmission configuration) and/or a feedback reporting configuration (e.g., CSI reporting configuration). The reference signal configuration may indicate a reference signal transmission window (e.g., CSI-RS transmission window). The reference signal transmission window may be associated with a start time and/or a duration. The WTRU may be configured to transmit a CSI-RS during the reference signal transmission window. The WTRU may be configured to receive CSI feedback based on a CSI-RS transmitted during the reference signal transmission window. The feedback may be received within the same reference signal transmission window as was used to send the CSI-RS.

[0082] A WTRU may be configured (e.g., pre-configured) with a number of SFRS resource sets within an SL resource pool. For example, each SL resource pool used by the WTRU may be associated with one or more configured SFRS resource sets. A WTRU may be configured (e.g., pre-configured) with a number of SFRS resources in a SFRS resource set. The configuration of a SFRS resource may include, for example, one or more of a time, frequency and/or code resource allocation in which the SFRS may be transmitted. The configuration parameters may include one or more of the following. The index of the slot in which the SFRS resource is located may be a configuration parameter. The number of consecutive symbols and the index of the starting symbol may be a configuration parameter. The index of a sub channel, PRB bundle, PRB and/or sub-carrier may be a configuration parameter. The pattern and/or density of the SFRS transmission may be a configuration parameter. The pattern and/or density of the SFRS transmission may include, for example, a comb-like pattern in the allocated frequency resource, repetition in the allocated time resource, etc. The index of a sequence used for the SFRS resource may be a configuration parameter. The type of transmissions intended for the SFRS resource {e.g., unicast, groupcast, and/or broadcast transmissions) may be a configuration parameter.

[0083] A WTRU may be configured (e.g., pre-configured) with an identity of an SFRS resource set and/or an SL RS resource. For example, the identity of each SFRS resource set and/or each SL RS resource may be configured (e.g., pre-configured) in the WTRU. For example, the WTRU may be configured (e.g., pre-configured) with a distinct index of an SFRS resource. For example, the distinct index of each SFRS resource may be configured (e.g., pre-configured) in the WTRU. The WTRU may indicate the SFRS index in the SL control information (SCI) associated with the SFRS transmission.

[0084] A WTRU may be configured (e.g., pre-configured) with an association between an SFRS resource and an SL feedback (SLFB) measurement type. The SLFB measurement type may include an SLFB measurement metric. For example, an SL RS resource may be associated with channel state information. The channel state information may include, for example, a wide-band channel quality indicator (CQI), sub-band CQI, precoder matrix index (PMI), rank indicator (Rl), layer indicator (LI), etc. An SL RS resource may be associated with beam management (e.g., L1 -RSRP). An SL RS resource may be associated with energy detection (e.g., RSSI). An SL RS resource may be associated with interference measurement.

[0085] The SLFB measurement type may include an SLFB measurement periodicity. For example, an SL RS resource may be associated with a periodic measurement. An SL RS resource may be associated with a semi-persistent measurement. An SL RS resource may be associated with an aperiodic measurement.

[0086] The SLFB measurement type may include priority and/or QoS information of unicast transmission data associated with the SFRS transmission and the SLFB measurement. For example, an SFRS resource may be associated with a unicast transmission configured with the parameters of PPPP, PPPR, VQI, and/or range.

[0087] The SLFB measurement type may include the type of a transmission. For example, an SFRS resource may be associated with a unicast transmission, a groupcast transmission, and/or a broadcast transmission. The SLFB measurement type may include one or more other parameters, for example, such as an applicable WTRU speed. [0088] The association may be configured (e.g., pre-configured) in accordance with the configuration of the SFRS resource. For example, an SFRS resource may be associated with wide-band CQI measurement when its configuration includes a wide frequency allocation. An SFRS resource may be associated with beam management feedback when its configuration includes multiple blocks of symbols in one slot specific for a repetition pattern. An SFRS resource may be associated with unicast transmission when the resource is configured in a resource pool dedicated for unicast transmission.

[0089] A WTRU may determine a SLFB measurement type implicitly based on the configured (e.g., pre configured) association and the resource allocation of the received SL RS transmission. For example, a WTRU may be configured (e.g., pre-configured) with an indication of the association for a configured (e.g., pre-configured) SFRS resource. A WTRU may indicate the association index in the SL control information (SCI) associated with the SFRS transmission. A WTRU may determine an SLFB measurement type based on an explicit indication in the SCI transmission.

[0090] A WTRU may be configured to perform SFRS transmission with unicast transmission identity information. A WTRU may be configured (e.g., pre-configured) with information uniquely associated with a unicast SL transmission, e.g. a link identity, a source WTRU identity, a destination WTRU identity and/or a service identity. A WTRU may associate this information with a unicast reference signal transmission. For example, the WTRU may use the information to scramble the CRC bits of the control information, e.g. that may include scheduling information of the unicast reference signal transmission. The WTRU may select a unicast reference signal type and/or index based on the information. For example, the WTRU may be configured with a set of ZC sequences for unicast reference signal transmission. The WTRU may determine the index of the sequence based on the destination WTRU identity. The WTRU may apply bit- level and/or symbol-level scrambling using a scrambling sequence (e.g., a gold sequence) based on the unicast transmission identity information.

[0091] A WTRU may determine an SFRS transmission resource. The SFRS transmission resource may be a resource for a CSI-RS transmission. A WTRU may perform sensing and may (e.g., subsequently) determine which configured unicast reference signal resources may be available for a unicast reference signal transmission. The WTRU may identify one or more resources within a reference signal transmission window. The WTRU may determine which of these one or more resources to use for a reference signal transmission. The WTRU may perform the determination based on unicast transmission properties, e.g. reliability, latency, capacity and/or range. For example, a WTRU may select a frequency resource set (e.g., including denser frequency resources) and may use a longer sequence for unicast reference signal transmission to provide higher resolution of the channel feedback for high-reliability unicast transmission.

A denser frequency resource may be defined as a SFRS density of 1 RE per PRB in a sub-channel. The WTRU may select the resource for a CSI-RS transmission. The selected resource may be within a transmission window {e.g., a CSI-RS transmission window).

[0092] In examples, a WTRU may determine an SFRS transmission resource based on one or more selected SFRS resources. The WTRU may be configured to select the SFRS resources based on one or more QoS requirements of the unicast transmission and/or based on one or more other transmission characteristics of the unicast transmission. The one or more QoS requirements may include, for example, link capacity, reliability, latency, range, etc. SFRS resources may be semi-statically configured per resource pool, and a WTRU may select an SFRS resource from a resource pool based on QoS parameters. The WTRU may determine which resource to use to transmit an SFRS (e.g., may determine an SFRS transmission resource) from the resources it selects based on the QoS requirement. For example, the WTRU may select SFRS resources of relatively short duration (e.g., one symbol or two symbols) and/or of relatively short interval (e.g., once a slot or twice a slot) for low latency transmission. The WTRU may select SFRS resources with repetition over multiple slots and/or PRBs for high reliability transmission. The WTRU may select SFRS resources with a large number of PRBs, for example to ensure RS detection at the required range. The required range may be based on a minimum communication range requirement.

[0093] The WTRU may determine the SFRS transmission resource based on one or more channel conditions. The channel condition(s) may include one or more of a WTRU speed, a path loss, a number of ranks, a delay spread, etc. For example, a WTRU in high speed may use an SFRS resource with high density in time domain, e.g., to provide better channel information. An SFRS resource with high density in time domain may include two symbols in one slot. In examples, a WTRU may obtain (e.g., determine) channel condition(s) based on previous CSI reporting. The WTRU may determine a subsequent SFRS transmission resource based on the channel condition(s) determined based on previous CSI reporting. For example, a WTRU may select an SFRS resource with high density for a link with large path loss.

[0094] The WTRU may determine the SFRS transmission resource based on candidate resources for the SL RS transmission. For example, the candidate resources may be available time/frequency/spatial resources. The WTRU may determine the candidate resources during sensing by evaluating, for example, energy- and/or SNR-based measurement and/or an SLFB measurement association with the determined SL RS resource. The energy- and/or SNR-based measurement may be, for example, RSSI and/or RSRP. For example, the WTRU may apply priority information to calculate a sensing threshold based on the configured (e.g., pre-configured) association between the SFRS resource and SLFB measurement type.

[0095] An SFRS transmission may include hand-shaking between a Tx WTRU and a Rx WTRU. A hand-shaking may be performed, for example, to avoid the case that a Rx WTRU may not be able to receive/measure one or more SFRS transmitted for beam measurement. [0096] In examples, a Tx WTRU for SFRS transmission may send a reservation signal in a first slot {e.g., slot #n) and the reserved resource for one or more SFRS may be in a second slot {e.g., slot #n+k). A Rx WTRU may confirm the reception of the reservation signal. One or more of following may apply to a hand-shaking between a Tx WTRU and a Rx WTRU for SFRS transmission.

[0097] A signal to confirm the reception of the reservation signal (e.g., a configuration signal) may be sent from the Rx WTRU. For example, the signal to confirm the reception of the reservation signal may be sent from the Rx WTRY within a time window between slot #n and slot #n+k. The time window and/or the value of k may be determined based on one or more of the following. The time window and/or the value of k may be determined based on a congestion ratio of the resource pool (e.g., CBR). If CBR is higher than a threshold, the window size may be increased; otherwise, a predefined time window may be used. In an example, the time window may be determined as a function of the CBR range. The time window and/or the value of k may be determined based on a QoS of the unicast link or packet. A best or a worst QoS value may be used to determine the time window, for example, for a unicast link. The time window and/or the value of k may be determined based on a range of the unicast link or packet. A shortest or longest minimum communication range requirement for the unicast link may be used to determine the time window. A confirmation (e.g., confirmation signal) may be sent if the Rx WTRU received the reservation signal and the WTRU receives SFRS in the reserved resource in slot #n+k. If the Rx WTRU received a reservation signal but the WTRU is not be able to receive SFRS in the slot #n+k, the WTRU may signal to delay the SFRS transmission (e.g., receive the SFRS in a later slot).

[0098] The Tx WTRU may not send SFRS if the WTRU does not receive a confirmation (e.g., a confirmation indication) from the Rx WTRU. The Tx WTRU may send SFRS if the WTRU receives the confirmation.

[0099] In examples, a Rx WTRU may trigger an SFRS transmission from a Tx WTRU. For example, the Rx WTRU may trigger an SFRS transmission from the Tx WTRU if a current quality or strength of a beam of a side link channel (e.g., SL-RSRP of PSCCH, PSSCH, PSFCH, and/or SFRS) is lower than a threshold. Trigger information associated with the trigger may include a resource reservation for an SFRS transmission (e.g., a subchannel and/or a slot), a number of SFRS required, and/or a current channel quality (e.g., SL-RSRP).

[0100] A WTRU may determine an associated feedback transmission resource. A WTRU may determine the transmission resources for a feedback transmission associated with an SFRS transmission, for example in addition to the SFRS transmission resource. For example, the transmission resources for the feedback transmission associated with the SFRS transmission may be resources in which a result of a SLFB measurement associated with the SFRS transmission is received. The feedback transmission resource may include a time resource allocation, a frequency allocation, and/or a beamforming configuration of the feedback transmission.

[0101] FIG. 2 shows an example CSI-RS and CSI reporting resource selection 200. A WTRU may select one or more resources for transmission of reference signals based on resources available for sending CSI feedback for the reference signals. For example, a plurality of candidate resources may be available for transmission of reference signals and/or CSI feedback. The WTRU may select a pair of the candidate resources {e.g., time and frequency resources) to reserve for a CSI-RS transmission and a corresponding CSI reporting transmission. The WTRU may select the pair of resources based on a time requirement (e.g., a maximum time gap) within a CSI-RS transmission window.

[0102] A WTRU may determine a feedback transmission timing within a feedback transmission window (e.g., a CSI transmission window). The WTRU may determine the feedback transmission window. The feedback transmission window may be determined such that it is within a corresponding CSI-RS transmission window. The feedback transmission window may include a feedback transmission window start time and a feedback transmission window duration. For example, the WTRU may determine one or more feedback transmission window parameters. The feedback transmission window parameters may include the feedback transmission window start time, the feedback transmission window duration, and/or a feedback transmission window expiry time. For example, the feedback transmission window may be determined to ensure validity of the feedback. The feedback transmission window may be determined to ensure timely transmission of CSI reporting for an accurate link adaptation of a SL unicast transmission. The feedback transmission window parameters may be determined based on an SFRS transmission, a SLFB measurement type, and/or one or more QoS parameters.

[0103] The WTRU may determine the window start timing (e.g., time) using the timing of the determined SFRS transmission timing (e.g., plus a time interval). The WTRU may select (e.g., determine) a resource to use when receiving a feedback report (e.g., a CSI report). The determined resource to use when receiving a feedback report may be within the determined feedback transmission window. For example, the WTRU may determine a first resource (e.g., an SL RS resource for RS transmission) in Slot n and a second resource (e.g., a feedback resource for an associated feedback transmission) in Slot n+x, where x may be a number of slots, mini-slots or symbols. The WTRU may send a reference signal transmission in the first resource. The WTRU may receive a feedback report in the second resource. The WTRU may determine a duration of the transmission window within which the WTRU may receive the associated feedback transmission. For example, the WTRU may determine an expiry period (e.g., expiry time) of the feedback transmission window. [0104] The WTRU may set the feedback transmission window in such a way that a WTRU transmitting a SFRS transmission receives the associated feedback information within a configured {e.g., pre-configured) time constraint. The configured time constraint may be the feedback transmission window expiry time. The WTRU may determine the feedback transmission window parameters including start timing and duration based on one or more of the following. The WTRU may determine the feedback transmission window parameters based on the required latency of the unicast transmission. The WTRU may determine the feedback transmission window parameters based on the required range of the unicast transmission. The WTRU may determine the feedback transmission window parameters based on the WTRU's processing capabilities. The WTRU may determine the feedback transmission window parameters based on a peer WTRU's processing capabilities. The WTRU may determine the feedback transmission window parameters based on SLFB measurement type information. The WTRU may determine the feedback transmission window parameters based on the estimated channel coherent time and/or other channel condition information. For example, the WTRU may determine the feedback transmission window parameters based on one or more QoS parameters. The WTRU may determine the feedback transmission window parameters based on SFRS transmission parameters. For example, the WTRU may determine the feedback transmission window parameters based on a feedback configuration. The feedback configuration may indicate the SFRS transmission parameters.

[0105] The WTRU may use the feedback transmission window to apply the feedback information during the window to schedule data transmission {e.g. by setting MCS) and/or to perform beam management (e.g. by selecting the most appropriate/best beam). For example, the WTRU may determine the MCS of a data transmission based on the CQI received in a feedback transmission within the feedback window when the data transmission is within the feedback transmission window (e.g., the CQI is valid). The WTRU may be configured to perform beam management during the feedback transmission window. The WTRU may determine the beamforming configuration based on the beam information indicated in the feedback window when the data transmission is within the feedback transmission window. The beam information may include, for example, a beam index or a TCI state.

[0106] A WTRU may determine one or more feedback transmission window parameters. The feedback transmission window parameter(s) may include a start of the feedback transmission window, for example, based on a WTRU processing capability. A WTRU may obtain one or more processing capabilities for the other WTRU of a unicast side link during an initial unicast transmission establishment. The start of the feedback transmission window may indicate an earliest timing at which a feedback transmission may occur, for example, relative to the associated SFRS transmission. [0107] A WTRU may determine feedback transmission window parameters (e.g., an end of the feedback and/or a duration of the feedback transmission window) based on a QoS requirement of the unicast transmission (e.g., latency and/or range). For example, the WTRU may determine a short time interval and small window size for low-latency unicast transmission for advanced NR use cases. The WTRU may estimate a two-way propagation delay based on the required range parameter and set the feedback transmission window accordingly. The end of the feedback transmission window may indicate a latest timing at which a feedback transmission may occur, for example, relative to the associated SFRS transmission.

[0108] The WTRU may determine the feedback transmission window parameters (e.g., an end of the feedback and/or a duration of the feedback transmission window) based on the SLFB measurement type, periodicity, priority information and/or type of transmission. For example, the WTRU may determine a short time interval and small window size for SFRS measurement based on energy detection (e.g., without baseband processing) for beam management. The WTRU may apply a large time interval for SLFB measurement intended for advanced channel state information (e.g., sub-band CQI/PMI/RI).

[0109] The WTRU may determine the feedback transmission window parameters (e.g., an end of the feedback and/or a duration of the feedback transmission window) based on an estimated channel condition information. For example, a WTRU with a high speed may apply a short time interval and small window size to enable a fast feedback transmission for the fast-varying channel. A WTRU may derive other channel conditions from an SL transmission (e.g., SCI) that may be quasi co-located (QCL:ed) with the SFRS transmission. For example, the channels used for the SL transmission and the SFRS transmission may be QCL:ed in terms of the channel conditions. The channel conditions may include, for example, a Doppler shift, Doppler spread, average delay, delay spread and/or Spatial Rx parameter.

[0110] The WTRU may determine the feedback transmission window parameters (e.g., an end of the feedback and/or a duration of the feedback transmission window) based on SFRS transmission parameters, an SLFB type, and/or one or more QoS parameters. For example, the WTRU may apply a large time interval and large window to allow the receiving WTRU to process measurement of a SFRS transmission with a beam sweeping configuration.

[0111] The WTRU may (e.g., subsequently) determine the associated feedback transmission resources based on the determined feedback transmission window and/or the candidate resources described herein (e.g., available time/frequency /spatial resources for the SFRS transmission). For example, the WTRU may determine the associated feedback resources by selecting the earliest candidate resources within the feedback transmission window. [0112] A WTRU may determine frequency resources of a feedback transmission based on the frequency resource of the SFRS resource configuration. For example, the WTRU may select a feedback resource that is in the same sub-channel {e.g., same frequency) as a selected reference signal resource. The feedback resource may be a feedback reporting resource. For example, the feedback resource may be used by the WTRU to receive a feedback (e.g., CSI) report. The WTRU may select a feedback resource that is an earliest available resource within a feedback transmission window that is also in the same sub-channel as a selected reference signal resource. The earliest available resource may be the earliest candidate resource of the selected candidate resources, as described herein. The frequency resources of an SFRS transmission may include a starting index and a number of sub-channels/PRB bundles/PRBs/sub-carriers. For example, a WTRU may be configured (e.g., pre-configured) with a set of associations between an SL RS transmission and an associated feedback transmission. For example, the association may include an offset in terms of a number of sub-channels/PRB bundles/PRBs/sub-carriers. The WTRU may determine (e.g., implicitly) the frequency allocation based on the frequency resources of the received SFRS transmission.

[0113] A WTRU (e.g., which is transmitting SLRS) may indicate in SCI the feedback transmission window parameters. The feedback transmission window parameters may include an end of the feedback and/or a duration of the feedback transmission window. Indicating the feedback transmission window parameters in SCI may ensure that the SLFB is received in the feedback transmission window. If SLFB is not received in the feedback transmission window, a retransmission of SLRS may be triggered. The WTRU may indicate (e.g., via sidelink control information (SCI)) a selected reference signal resource and/or a selected feedback resource. The WTRU may send CSI information (e.g. , a received CSI report) in a Physical Sidelink Shared Channel (PSSCH), for example, using the selected feedback resource. The WTRU may multiplex the CSI information when sending. The WTRU may send the CSI information in a medium access control (MAC) control element (CE).

[0114] The WTRU may indicate (e.g., in SCI) the beamforming configuration for the associated feedback transmission. For example, the WTRU may indicate the beamforming configuration of the associated feedback transmission including , for example, using the same beam as the SL control channel, using beam sweeping, using a wide beam, etc., in an SCI bit field.

[0115] A WTRU may perform beamformed unicast reference signal transmission with feedback scheduling assistance information. Within the determined SL time resource for a unicast reference signal transmission, a WTRU may determine a sequence of reference signal transmissions with different spatial domain transmission filter configurations. The determination may be made based on, for example, the WTRU's beamforming capability and unicast transmission properties including, for example, capacity, reliability, latency and/or range. For example, a WTRU may apply a set of spatial domain transmission filter configurations that may generate higher beamforming gain to provide longer range unicast transmission.

[0116] A WTRU may determine spatial domain transmission filter configurations for the unicast reference signal transmission based on the spatial domain transmission filter used for the sensing. For example, the WTRU may apply a spatial domain transmission filter to transmit a unicast reference signal within a subset of the beam coverage provided by the spatial domain transmission filter in the sensing.

[0117] A WTRU may perform a unicast beamformed reference signal transmission, e.g. as shown in FIG. 3. A WTRU may transmit SL control information (SCI) using the spatial domain transmission filter identical to the one used in sensing and subsequent unicast reference signal resource determination. A WTRU may provide the following information in the SCI: SL reference signal resource scheduling information; an SFRS resource indication; SLFB measurement information; an SL RS association indication; SL reference signal identification information; feedback scheduling assistance information; and/or SL reference signal transmission parameters.

[0118] A WTRU may provide SL reference signal resource scheduling information in SCI. A WTRU may provide the time and frequency resource for the reference signal transmission. For example, a WTRU may indicate the starting symbol and symbol duration for a reference signal transmission. The WTRU may indicate the starting symbol and symbol duration for each reference signal transmission. The WTRU may include an index of the reference signal resource set to provide the reference signal frequency resource information. The WTRU may include a periodicity configuration of the reference signal transmissions. For example, the WTRU may indicate the period of such reference signal transmission.

[0119] A WTRU may provide an SFRS resource indication in SCI. For example, the WTRU may indicate an SFRS resource ID and/or index to convey the information of the RS resource allocation of time, frequency, and/or code.

[0120] A WTRU may provide SLFB measurement information in SCI. For example, the WTRU may provide information regarding the measurement type, periodicity, type of transmission, etc.

[0121] A WTRU may provide SL reference signal identification information in SCI. A WTRU may indicate the number of reference signal transmissions within the time resource, e.g. the slot. The WTRU may provide identification information of the reference signals to be applied in the associated feedback transmission. For example, the information may be explicitly indicated by reference signal resource set index and/or sequence index. The WTRU may use a TCI state to indicate each reference signal transmission. For example, the information may be implicitly indicated by the order of the transmission of a reference signal with the slot. For example, order of transmission of each reference signal within the slot may implicitly indicate the information.

[0122] A WTRU may provide feedback scheduling assistance information in SCI. A WTRU may provide scheduling information for the feedback transmission corresponding to an associated SL unicast reference signal transmission. For example, the WTRU may indicate a time interval with reference to the reference signal transmission and frequency resource allocation based on the WTRU sensing result. For example, the WTRU may indicate a feedback transmission timing information with reference to the reference signal transmission (e.g., a feedback transmission window). The WTRU may indicate periodicity information of the reference signal transmission (e.g. when the SL reference signal transmission schedule is periodical). The WTRU may include a beamforming configuration as disclosed herein.

[0123] A WTRU may provide SL reference signal transmission parameters in SCI. The WTRU may include the power level of the reference signal transmission for path loss estimation. The WTRU may include an indication of the beamforming configuration of the SFRS.

[0124] A WTRU may apply bit-level and/or symbol-level scrambling of the SCI information using the unicast transmission identity information (e.g. source ID, destination ID and/or link ID) of the unicast transmission.

[0125] A WTRU may (e.g., subsequently) monitor a feedback transmission associated with the unicast reference signal transmission based on, for example, the transmitted feedback scheduling assistance information. For example, the WTRU may monitor the feedback transmission in a feedback transmission window as disclosed herein based on the time interval scheduled for the feedback transmission.

[0126] A WTRU may perform feedback transmission with unicast reference signal transmission. A WTRU may receive a unicast reference signal transmission based on, for example, the configured unicast transmission identity conveyed in the control information transmission. The WTRU may measure one or more quality metrics for a reference signal transmission scheduled in the control information. The quality metrics may include, for example, a channel quality indicator (CQI), signal to noise ratio (SNR), signal to interference plus noise ratio (SINR), reference signal received power (RSRP), noise level, etc. The WTRU may measure the quality metrics for each reference signal transmission scheduled in the control information.

[0127] As used herein, a Tx beam may be referred to as a spatial domain transmission filter configuration and the two terms may be interchangeable. The term spatial domain filter configuration may be used in NR specifications.

[0128] The WTRU may perform the measurement using a spatial domain transmission filter configuration similar (e.g., identical) to the one used to receive the control information transmission (e.g. wide beam). When reference signal transmissions are periodic, the WTRU may (e.g., subsequently) perform the measurement using a different spatial domain transmission filer configuration {e.g. narrow beam). When reference signal transmissions are not periodic, the WTRU may request a reference signal transmission for measurement using different spatial domain transmission filter configurations, e.g. for pairing a receiver beam with a reference signal transmission. For example, each reference signal transmission may be paired with a receiver beam.

[0129] A WTRU may include the quality metrics for one or more (e.g., all) reference signal transmissions. The WTRU may include the information of the reference signal transmission that has the best measured quality metric. The WTRU may include information regarding the spatial domain transmission filter used to measure the reference signal transmissions.

[0130] A WTRU may transmit the feedback information using a spatial domain transmission filter configuration corresponding to the one used to receive an SCI (e.g., that scheduled the associated reference signal transmission). The WTRU may provide feedback information in the same PHY channel as the one carrying scheduling control information. For example, the WTRU may transmit a PSCCH including bit fields for both scheduling information and feedback information.

[0131] A WTRU may transmit feedback information in a separate PHY channel, e.g. a Physical Layer SL Feedback Channel. For example, the unicast reference signal transmission scheduling may be periodic. The WTRU may transmit feedback information in a PSCCH without scheduling information and/or separately in a Physical SL Feedback Channel. The channel may be time and/or frequency multiplexed with the PSCCH, e.g. in an adjacent manner. The implementations disclosed herein may apply for both feedback channel implementations.

[0132] A WTRU may transmit feedback information in a physical (PHY) data channel, e.g., a PSSCH.

For example, a WTRU may include the feedback information in a MAC CE. A WTRU may merge a feedback reporting transmission with a data transmission when the WTRU has data to transmit and/or a transmission window of the data based on its QoS requirement may overlap with a determined feedback transmission window.

[0133] A WTRU select an available resource within an overlapping time period between a feedback transmission window and a data transmission window. A WTRU may multiplex coded feedback bits with the PSSCH in the PSSCH resource. The WTRU may indicate (e.g., in an associated SCI transmission) a presence of the multiplexed coded feedback bits in the PSSCH. The WTRU may include feedback resource allocation information in the associated SCI transmission. The feedback resource allocation information may be indicated in a bit field. The feedback resource allocation information may be used to determine one or more sub-carriers used for the feedback bits, one or more symbols used for the feedback bits, and/or a coding rate of the feedback bits. The PSSCH data may be rate matched and/or punctured to the feedback resource allocation information.

[0134] The feedback information may include channel information {e.g., CSI, SNR, RSRP, SINR, etc.) of one or more (e.g., all) measured reference signal transmission. The WTRU may feedback an identity information (e.g. resource indicator, index or transmission configuration indicator (TCI) state) of the reference signal transmission that has the best measured quality metric.

[0135] A WTRU may combine a feedback transmission with a reference signal transmission, for example to reduce latency in beam selection for a unicast transmission and/or to utilize the SL resource efficiently (e.g., a WTRU may use the same resource for its reference signal transmission and feedback transmission). For example, the WTRU may include both reference signal transmission and feedback transmission information in the control information transmission.

[0136] The WTRU may determine the feedback transmission based on, for example, the feedback scheduling assistance information received in the control information that schedules the associated reference signal transmission and/or the sensing result. For example, the WTRU may perform the transmission in the time resource (e.g. slot) in accordance with the feedback transmission timing included in the received control information. When the time resource is indicated as unavailable, the WTRU may select another available time resource that may be closest to the scheduled time resource.

[0137] An SLFB transmission may be dropped, for example, due to resource unavailability. The WTRU may receive the SFRS transmission and determine whether to transmit the associated feedback transmission based on the indicated feedback transmission window. In examples, a WTRU may drop a SLFB transmission when the WTRU is not able to select an available resource within the determined feedback transmission window. The WTRU may send an indicator and/or request another SFRS transmission in a SCI in PSCCH transmission. In examples, the WTRU may send the indicator and/or a SFRS transmission request in a MAC CE and/or RRC signaling carried in a PSSCH transmission. In examples, the WTRU may determine a PHY channel to transmit the feedback information based on the indicated feedback transmission timing and/or feedback transmission window. For example, the WTRU may determine to use a SL data channel to transmit the feedback information when the SL data channel transmission satisfies the feedback transmission timing.

[0138] FIG. 3 shows an example of NR V2X WTRU autonomous unicast beamformed reference signal transmission 300. As depicted in FIG. 3, a WTRU (e.g., WTRU1 as shown in FIG. 3) may determine to apply one or more (e.g., four) unicast reference signal transmissions within a slot. WTRU1 may transmit control information using a wide beam (e.g. using the spatial domain transmission filter used for the sensing) and the SCI may include reference signal scheduling and/or feedback scheduling assistance information. WTRU1 may transmit the unicast reference signals using a set of spatial domain transmission filters to provide a narrow beam sweeping. WTRU1 may embed a unicast transmission identity in the control information transmission, e.g. using cyclic redundancy check (CRC) scrambling or bit-level sequence scrambling. WTRU1 may provide feedback transmission resource information (e.g., a feedback transmission window) to assist in feedback transmission scheduling.

[0139] A WTRU (e.g., WTRU2 as shown in FIG. 3) may detect the WTRU1 reference signal transmission and perform measurement of a WTRU1 reference signal transmission. For example, WTRU2 may perform measurement of each WTRU1 reference signal transmission. WTRU2 may provide feedback information in the control information transmitted with its own reference signal transmission for WTRU1 measurement. The feedback information may include the identity information of the reference signal transmission the best measured quality metric. WTRU2 may transmit the feedback based on the resource indicated in the received feedback scheduling assistance information, for example following the indicated transmission timing information.

[0140] WTRU2 may transmit one or more beamformed reference signal transmissions multiplexed with the feedback information. In the example shown in FIG. 3, WTRU2 may have four spatial domain transmission filter configurations for reference signal transmission. Implementations disclosed herein may apply to WTRUs with any beamforming capability. WTRU1 may receive the feedback information in the same SCI as the scheduling information of the WTRU2 reference signal transmission, and WTRU1 may perform a similar measurement and provide feedback and/or schedule a (e.g., subsequent) reference signal transmission.

[0141] A WTRU may determine a spatial domain transmission filter for unicast control and/or data transmission. A WTRU may determine a spatial domain transmission filter configuration for both transmission and reception associated with a unicast transmission based on the reference signal and feedback transmissions disclosed herein. For example, the WTRU may select the spatial domain transmission filter configuration with the best measured quality metric indicated in the feedback transmission and may apply the configuration to the unicast data transmission. For example, a WTRU may determine to use the spatial domain transmission filter configuration for a transmission, which may be used to receive the reference signal transmission with the best measured quality metric (e.g., when the UE is capable of beam correspondence).

[0142] A WTRU may apply different spatial domain transmission filter configurations for control information and data transmissions within the same SL time resource based on unicast transmission properties and/or requirements. For example, a WTRU may determine to transmit control information in a wide beam (e.g., to ensure the reliability requirement of the transmission). For example, as shown in FIG. 4, WTRU1 and WTRU2 may determine that both may apply beam 5 for data transmission based on the reference signal transmissions. FIG. 4 shows an example of NR V2X WTRU autonomous beam initiation for SL unicast transmission 400. Both WTRUs may apply beam 1 for control information transmission and beam 5 for data transmission. This may ensure the reliability of the SL control information transmission.

[0143] The WTRU may indicate the spatial domain transmission filter configuration in the control information. For example, the control information may include a reference signal resource indicator, sequence index, and/or TCI state associated with the spatial domain transmission filter configuration. The control information may indicate whether the control information and data apply the same spatial domain transmission filter configuration.

[0144] A WTRU may provide data scheduling assistance information based on, for example, the reference signal transmission. For example, the WTRU may indicate the channel condition in the established unicast transmission link {e.g. CQI, SNR, noise level, etc.) measured in the established beam pair link. The data scheduling information may include a time and frequency resource and spatial domain transmission filter configuration (e.g., which transmit beam to use for the data transmission). For example, in FIG. 4, WTRU1 may indicate a time interval in the data scheduling assistance information with reference to its data transmission based on the sensing result.

[0145] A WTRU may determine a unicast data transmission resource based on SFRS and associated feedback transmissions. A WTRU may be configured (e.g., preconfigured) with an association between an SFRS resource and an SL data resources block (SDRB). For example, each SFRS resource may be associated with an SDRB. An SDRB may include a sub-channel, a PRB bundle, a PRB or a block of sub carriers (e.g., or multiple sub-channel/PRB bundles/PRBs/blocks of sub-carriers). An SFRS resource may locate within the associated SDRB in a configured (e.g., preconfigured) pattern (e.g., a SFRS resource may consist of a number of sub-carriers evenly distributed over a sub-channel and over a number of symbols).

[0146] A WTRU may determine a set of link quality indications of an SDRB based on the measurement metric reported in the feedback transmission associated with the SFRS transmission using the SFRS resource associated with the SDRB. The link quality indications may include the SLFB measurement metric disclosed herein.

[0147] A WTRU may be configured (e.g., preconfigured) with a mapping to estimate link qualities based on the link quality indications. A WTRU may determine/estimate an achievable throughput and/or reliability of an SDRB based on the indicated CQI/PM l/RI/RSSI . For example, the WTRU may determine an SDRB of CQI X is capable of providing a link capacity in terms of a throughput of Y mbps and/or a link reliability in terms of an SL control channel BLER of Z%. The values of X, Y and Z may be based on simulations of different channel conditions and may be configured (e.g., preconfigured) in the WTRU. [0148] The WTRU may determine a round-trip latency and range of an SDRB based on the timing of the received feedback transmission within the feedback transmission window disclosed herein. The WTRU may determine the spatial domain transmission filter configuration of an SDRB that may provide the achievable throughput, reliability, latency and/or range.

[0149] The WTRU may determine one or multiple SDRBs to apply for a unicast transmission link based on the achievable unicast link qualities and the required equivalent QoS requirements {e.g., capacity, reliability, latency and/or range). For example, the WTRU may select multiple SDRBs of which the achievable throughput and/or reliability exceeds what is required for the unicast transmission.

[0150] The WTRU may reserve the determined SDRBs using a bit field in an SL control channel and/or a reservation signal. The WTRU may be configured (e.g., preconfigured) with a time period within which the reservation is applicable. The WTRU may transmit a periodic SFRS at the SFRS resources associated with SDRBs for the purpose of resource selection and link adaption. The WTRU may not assess the sensing result during the reservation period.

[0151] A WTRU may be configured to perform SLFB reporting. The WTRU may activate or deactivate SLFB reporting. The WTRU may determine that a unicast channel has reciprocity and may transmit unicast data based on the received unicast data transmission parameters using SLFB reporting. The WTRU may determine that SLFB reporting may be turned off and may perform the data transmission based on the channel reciprocity. Turning off SLFB reporting may reduce transmission overhead when channel reciprocity is present. For example, channel reciprocity may be present in a LOS condition between two WTRUs performing SL unicast transmission with each other.

[0152] The WTRU may determine to turn off SLFB reporting based on channel condition measurement metrics. The channel condition measurement metrics may be determined based on received SFRS transmissions. The channel condition measurement metrics may include SNR/SINR/Path loss/interference. The channel condition measurement metrics may include spatial Rx parameters. For example, the spatial Rx parameters may include an angle of arrival (AoA) of received SFRS transmission energy. The channel condition measurement metrics may include a delay spread/average delay/doppler spread/doppler shift.

The channel condition measurement metrics may include a CQI/PMI/RI/LI. The channel condition measurement metrics may include RSSI/RSSP. The channel condition measurement metrics may include a measured multi-path distribution and strength.

[0153] The WTRU may determine to turn off SLFB reporting based on channel occupancy information. The channel occupancy information may be determined based on sensing. The channel occupancy information may include CBR. The WTRU may determine to turn off SLFB reporting based on received SLFB information associated with SFRS transmissions. The WTRU may determine to turn off SLFB reporting based on SFRS transmission parameters. The SFRS transmission parameters may include, for example, power level, transmission mode, precoding configuration, number of layers, etc. The WTRU may determine to turn off SLFB reporting based on WTRU mobility. The WTRU may determine to turn on/off SLFB reporting {e.g., CSI reporting) based on a WTRU Tx-Rx distance and/or a minimum communication range (MCR) requirement.

[0154] In an example, a WTRU (e.g., WTRU1 ) may determine that a unicast transmission link channel has reciprocity when the difference between one or multiple measured channel metrics and their corresponding metrics received from another WTRU (e.g., WTRU2) is within a configured (e.g., pre configured) range. For example, WTRU1 may evaluate a set of CQIs received from WTRU2 associated with SFRS transmissions by WTRU1 and another set of CQIs measured by WTRU1 on SFRS

transmissions by WTRU2. WTRU1 may determine that channel reciprocity is present when the difference between the two sets of CQI values is within a configured (e.g., pre-configured) range. The range may be, for example, +/- 1 . WTRU1 and WTRU2 may indicate the transmission configuration and parameters for the SFRS transmission in the SCI associated with the SFRS transmission.

[0155] In an example, a WTRU may determine that channel reciprocity is present when the measured and reported path loss are within a configured (e.g., pre-configured) range. For example, a WTRU may determine that a measured path loss less than a configured (e.g., pre-configured) threshold indicates a LOS channel that is reciprocal.

[0156] In examples, a WTRU may determine whether channel reciprocity may be held or not for a unicast side link, for example, based on an analog feedback from a peer WTRU. For example, a peer WTRU may send an analog feedback of an estimated channel sent from a Tx WTRU. The analog feedback may include one or more of following. The analog feedback may include one or more of complex valued channel coefficients (e.g., each channel coefficient may be represented by amplitude and phase). The complex valued channel coefficient(s) may be measured/estimated from a reference signal that may be sent/fed back. The complex valued channel coefficient(s) may be multiplied to a reference signal and sent. An amplitude may be quantized; and, the phase may be multiplied to a reference signal. The amplitude may be ignored; and, an estimated phase value of the coefficient may be multiplied to a reference signal. The analog feedback may include two reference signals. For example, a first reference signal may be sent without multiplying with estimated channel and a second reference signal may be sent with multiplying with an estimated channel. The analog feedback may be triggered by a WTRU. The triggering WTRU may send a reference signal together with a triggering message. The feedback information may be piggybacked in a reference signal. [0157] When a WTRU determines the presence of a unicast transmission link channel reciprocity, the WTRU may turn off SLFB reporting and enter SLFB reporting OFF mode. In an example, the WTRU may turn off the SFRS and SLFB transmission configured for the unicast transmission. In an example, a WTRU may turn off SLFB transmission configured for the unicast transmission and perform OFF mode SFRS transmission. A WTRU may use the same SFRS transmission configuration in OFF mode as in ON mode {e.g., the same SFRS transmission resource and periodicity). In an example, a WTRU may apply aperiodic SFRS transmission in SLFB reporting OFF mode based on configured (e.g., pre-configured) triggering conditions.

[0158] A WTRU may determine to turn off a SLBK reporting transmission after receiving a SFRS transmission from another WTRU, for example, when the TX-RX distance between the two WTRUs exceeds a minimum communication range (MCR). The WTRU may obtain the MCR information associated with an SFRS transmission from an associated SCI transmission. The WTRU may send (e.g., subsequently send) an out-of-MCR indicator in an SCI, for example, to inform the other WTRU.

[0159] A WTRU may indicate the SLFB reporting ON and OFF mode in SCI associated with unicast data transmissions. For example, the WTRU may include a bit field in the SCI to switch ON and OFF SLFB reporting. In an example, a WTRU may be configured (e.g., pre-configured) with a semi-persistent SFRS transmission for a unicast transmission and the WTRU may apply the SLFB reporting ON/OFF signaling to activate and de-activate the SPS SFRS transmissions.

[0160] During SLFB reporting OFF mode, a WTRU may determine the unicast transmission parameters based on the received data transmission and/or SFRS transmission. For example, the WTRU may set the MCS of the data transmission based on the MCS parameter indicated in the SCI associated with and/or measured channel conditions such as SNR/SINR of the received data transmission and/or SFRS transmission. In an example, a WTRU may transmit unicast data using a spatial domain transmission filter configuration based on the measured AoA of the data transmission. In an example, a WTRU may determine the unicast transmission parameters based on the received SFRS and/or unicast data transmission. The unicast transmission parameters may include, for example, MCS and spatial domain transmission filter configuration.

[0161] A WTRU may determine a condition for which the SLFB reporting OFF mode may be initiated based on the QoS of the data. The WTRU may determine the difference between the measured channel and the reported channel, above/below which the OFF mode may be used. The WTRU may determine the difference based on VQI or a similar QoS parameter. The VQI or similar QoS parameter may be associated with the radio bearer(s) on the unicast link. The VQI or similar QoS parameter may be associated with the packets being transmitted. The VQI or similar QoS parameter may be associated with the unicast link during link establishment.

[0162] During the unicast transmission with SLFB reporting OFF mode, a WTRU may determine to enter SLFB reporting ON mode and turn on the SLFB transmission and SFRS transmission {e.g., when SFRS transmission is OFF in the SLFB reporting OFF mode) to assist data transmission and re-evaluate the channel reciprocity. The WTRU may determine to enter SLFB reporting ON mode based on a received FIARQ ACK/NACK. The WTRU may determine to enter SLFB reporting ON mode based on BLER of received data packets. The WTRU may determine to enter SLFB reporting ON mode based on channel condition measurement metrics. The channel condition measurement metrics may be based on received data transmissions (e.g., DMRS). The channel condition measurement metrics may include

SNR/SINR/Path loss/interference. The channel condition measurement metrics may include spatial Rx parameters. For example, the spatial Rx parameters may include an AoA of received SFRS transmission energy. The channel condition measurement metrics may include a delay spread/average delay/doppler spread/doppler shift. The channel condition measurement metrics may include a measured multi-path distribution and strength.

[0163] The WTRU may determine to enter SLFB reporting ON mode based on channel occupancy information. The channel occupancy information may be determined based on sensing. The channel occupancy information may include CBR. The WTRU may determine to enter SLFB reporting ON mode based on WTRU mobility.

[0164] During the unicast transmission with SLFB reporting OFF mode, a WTRU may determine the channel reciprocity has changed and may turn on SLFB reporting. For example, the WTRU may turn on SLFB reporting when the WTRU receives a number of FIARQ NACKs that exceeds a configured (e.g., pre configured) threshold within a configured (e.g., pre-configured) period of time. The WTRU may turn on SLFB reporting when the WTRU detects a change from a LOS channel to a non-LOS channel. The WTRU may detect the change from the LOS channel to the non-LOS channel based on detection of multiple similarly strong path clusters. The WTRU may turn on SLFB reporting when the WTRU speed has increased by an amount exceeding a configured (e.g., pre-configured) threshold. The WTRU may turn on SLFB reporting when the WTRU measures a CBR higher than a configured (e.g., pre-configured) threshold that may indicate increasing interference. The WTRU may turn on SLFB reporting when the WTRU measures one or more channel condition measurement metrics (e.g., SNR/SINR/interference of the received SFRS transmissions) that decrease by an amount exceeding a configured (e.g., pre-configured) threshold. [0165] In examples, a WTRU may turn on SLFB reporting. For example, a WTRU may turn on SLFB reporting when the WTRU determines a distance between WTRUs may be within the minimum communication range (MCR).

[0166] NR V2X beamformed unicast link monitoring and/or re-configuration may be performed.

[0167] A WTRU may be configured to perform unicast beam pair link monitoring. For example, a WTRU may be configured to monitor the established unicast beam pair link based on transmissions of a set of periodical reference signals. The WTRU may determine the reference signal set for beam pair link monitoring based on one or more of the following: control information transmission {e.g., the DMRS for the control information transmission), scheduled reference signals (e.g., the references signals scheduled for beam pair transmission as disclosed herein), or reference signals used in sensing.

[0168] A WTRU may be configured with a quality metric threshold based on, for example, SNR, SINR, noise level, etc., and may evaluate the beam pair link based on the reference signal measurement during the period without data transmission. The WTRU may determine a beam pair link failure event when the measured quality metric of the reference signals belonging to the reference signal set is below a threshold.

[0169] A WTRU may be configured with reference signal transmission based on sensing result. The WTRU may not be able to evaluate periodically the unicast beam pair link during the period without data transmission. For example, the WTRU may be configured with a unicast beam pair link quality timer for a reference signal (e.g., each reference signal) of the beam link monitoring reference signal set. The WTRU may determine the length of a timer (e.g., each timer) based on one or more of a spatial domain transmission filter configuration of the unicast transmission link or a time and frequency resource configuration.

[0170] The WTRU may determine the length of a timer (e.g., each timer) based on a spatial domain transmission filter configuration of the unicast transmission link. For example, the WTRU may determine the length of the timer based on beam width and/or beam direction. For example, the WTRU may determine a shorter timer length for a narrow beam pair (e.g., because the narrow beam pair may be more subject to blockage).

[0171] The WTRU may determine the length of a timer (e.g., each timer) based on a time and frequency resource configuration. For example, the WTRU may determine the length of the timer based on the size of the frequency resource pool and/or the availability of the time resource (e.g., depending on the WTRU time slot configuration).

[0172] The WTRU may dynamically adjust the length of the timer based on one or more of the following: reference signal transmission measurement, reference signal transmission feedback information, channel occupancy and/or usage based on sensing, or WTRU orientation variation and/or movement. [0173] The WTRU may dynamically adjust the length of the timer based on reference signal transmission measurement. For example, the WTRU may increase the length of the timer when the WTRU receives an aperiodic reference signal transmission and evalution indicates a quality metric is above a pre configured beam pair link quality threshold. The WTRU may decrease the timer length when the WTRU receives an aperiodic reference signal transmission and evalution indicates a quality metric is below a pre configured beam pair link quality threshold.

[0174] The WTRU may dynamically adjust the length of the timer based on reference signal transmission feedback information. For example, the WTRU may increase the timer length when the WTRU receives feedback information that indicates a measured quality metric at the other end of the unicast transmission is above a pre-configured beam pair link quality threshold. The WTRU may decrease the timer length when the WTRU receives feedback information that indicates a measured quality metric at the other end of the unicast transmission is below a pre-configured beam pair link quality threshold.

[0175] The WTRU may dynamically adjust the length of the timer based on channel usage and occupancy based on sensing. For example, the WTRU may dynamically adjust the length of the timer based on measured received signal code power (RSCP), number of available resources, measured channel busy ratio (CBR), and/or the like. The WTRU may decrease the timer length when the sensing result indicates a high channel usage and occupany.

[0176] The WTRU may dynamically adjust the length of the timer based on WTRU orientation variation and movement. The WTRU may decrease the timer length when a speed at which the WTRU is moving increases. The WTRU may decrease the timer length when the WTRU orienation variation rate increases {e.g. the orienation changes more often).

[0177] The WTRU may determine a beam pair link failure event when the timer expires.

[0178] A WTRU may be configured with a counter of beam pair link failure events based on, for example, a beam pair link monitoring reference signal set and/or timer. The WTRU may declare a beam pair link failure when the counter exceeds a pre-configured maximum number of events. When the WTRU declares a beam pair link failure on one or more (e.g., all) reference signals of the beam pair link monitoring set, the WTRU may determine that no candidate spatial domain transmission filter configuration is available and may send a notification to higher layers accordingly.

[0179] A WTRU may be configured to perform a WTRU beam pair link switch. A WTRU may determine to re-configure the spatial domain transmission filter (e.g., switch beams) based on pre-configured triggering conditions including one or more of the following: reference signal transmission measurement, reference signal transmission feedback information, FIARQ ACK/NACK feedback transmission, beam pair link monitoring, channel sensing results, or control information decoding results. [0180] A WTRU may re-configure the spatial domain transmission filter of the control information transmission and align with that of the data transmission {e.g., as shown in the first beam switch in FIG. 5). A WTRU may perform such unicast link re-configuration when, for example, one or more of the following occurs: measured reference signal quality is above a pre-configured threshold; a feedback quality metric is above a pre-configured threshold; a number of NACKs is below a pre-configured threshold; or channel sensing using the current spatial domain transmission filter of the control information indicates high occupancy.

[0181] One or more (e.g., all) the triggering conditions may indicate that the beam pair link quality ensures control information reliability using the same spatial domain transmission filter as the one used for the data transmission. The WTRU may re-configure the spatial domain transmission filter of the control information transmission, for example to reduce the load and the interference in the wide beam (e.g., beam 1 in FIG. 4).

[0182] A WTRU may indicate an explicit spatial domain transmission filter re-configuration in the control information. For example, the indication may include re-configured reference signal identity information (e.g. a resource indicator, index or TCI state both WTRUs of the unicast transmission may apply in subsequent data transmissions). The WTRU may re-configure the reference signal set in accordance with the spatial domain transmission filter re-configuration. FIG. 5 shows an example of NR V2X WTRU autonomous beam re-selection for SL unicast transmission 500. For example, in FIG. 5, when WTRU1 switches from beam 1 to beam 5 for control information transmission, WTRU1 may (e.g., subsequently) monitor both beam 1 and beam 5 for beam link monitoring. WTRU1 may switch the beam link monitoring reference signal from beam 1 to beam 5.

[0183] A WTRU may re-configure the spatial domain transmission filter of both the control information and data (e.g., as shown in the second beam switch in FIG. 5) and may change the current configuration to a candidate configuration. The WTRU may perform such control and data transmission link re-configuration when, for example, one or more of the following occurs for the current spatial domain transmission filter configuration: beam link failure events are detected associated with current spatial domain transmission filter configuration; a measured reference signal associated with the current spatial domain transmission filter is below a pre-configured threshold; a feedback quality metric associated with the current spatial domain transmission filter is below a pre-configured threshold; or a number of NACKs is above a pre- configured threshold.

[0184] The WTRU may perform such control and data transmission link re-configuration when, for example, one or more of the following occurs for the candidate spatial domain transmission filter configuration: a measured reference signal associated with the candidate spatial domain transmission filter is above a pre-configured threshold; or a feedback quality metric associated with the candidate spatial domain transmission filter is above a pre-configured threshold.

[0185] One or more {e.g., all) of the triggering conditions may indicate that the beam pair link may fail or the quality may fall below a pre-configured reliability and/or range requirement for the unicast transmission.

[0186] Upon triggering of a switch, a WTRU may implicitly re-configure the spatial domain transmission filter to the one applied to the control information transmission associated with the reference signal transmission and/or sensing. For example, the WTRU may revert to a wide beam for control information transmission and transmit an explicit spatial domain transmission filter re-configuration indicator. The WTRU may transmit this control information without data scheduling. The WTRU may transmit the control information in the feedback information in PSCCH and/or separately in Physical SL feedback channel. The WTRU may transmit the control information with data transmission using the candidate spatial domain transmission filter configuration, e.g. to reduce latency resulting from the re-configuration. The WTRU may indicate (e.g., in the control information) a switch to a candidate spatial domain transmission filter configuration, which may be applied to a data transmission within the same SL time resource (e.g., the same slot). As illustrated in the 2^nd switch in FIG. 5, WTRU1 may revert to beam 1 to transmit explicit spatial domain transmission filter re-configuration to WTRU2 in the control information and WTRU1 may transmit data in beam 3 in the same SL time resource, e.g. a slot.

[0187] Table 1 may illustrate the meaning of one or more acronyms used herein.

Table 1. Common acronyms and their expansions

Claims

What is claimed is:

1. A wireless transmit/receive unit (WTRU) comprising:

a processor configured to:

receive a channel state information (CSI) configuration that indicates a CSI reference signal (CSI-RS) transmission configuration and a CSI reporting configuration that is associated with the CSI-RS transmission configuration;

determine a CSI transmission window based on one or more of the CSI reporting configuration, a processing capability of a peer WTRU, a minimum communication range, an estimated channel information, or a quality of service (QoS) parameter;

select a first resource, for a CSI-RS transmission, that is within a CSI-RS transmission window;

select a second resource, to receive a CSI report, that is within the CSI transmission window;

send the CSI-RS transmission in the selected first resource; and

receive the CSI report in the selected second resource.

2. The WTRU of claim 1 , wherein the selected second resource is an earliest available resource in the CSI transmission window that meets one or more criteria.

3. The WTRU of claim 1 , wherein the selected second resource is in a same sub-channel as the selected first resource.

4. The WTRU of claim 1 , wherein the selected second resource is an earliest available resource in the CSI transmission window that is in a same sub-channel as the selected first resource.

5. The WTRU of claim 1 , wherein being configured to determine the CSI transmission window comprises being configured to determine a CSI transmission window start time and a CSI transmission window duration.

6. The WTRU of claim 1 , wherein the second resource is separated in time from the selected first resource by less than a duration of the CSI transmission window.

7. The WTRU of claim 1 , wherein the processor is further configured to send sidelink control information (SCI) that indicates the selected second resource.

8. The WTRU of claim 1 , wherein the CSI configuration is a device-to-device (D2D)/vehicular communications (V2X) CSI configuration.

9. The WTRU of claim 1 , wherein the processor is further configured to send CSI information in a Physical Sidelink Shared Channel (PSSCH) using the selected second resource.

10. A method comprising:

receiving a channel state information (CSI) configuration that indicates a CSI reference signal (CSI-RS) transmission configuration and a CSI reporting configuration that is associated with the CSI-RS transmission configuration;

determining a CSI transmission window based on one or more of the CSI reporting configuration, a processing capability of a peer WTRU, a minimum communication range, an estimated channel information, or a quality of service (QoS) parameter;

selecting a first resource, for a CSI-RS transmission, that is within a CSI-RS transmission window; selecting a second resource, to receive a CSI report, that is within the CSI transmission window; sending the CSI-RS transmission in the selected first resource; and

receiving the CSI report in the selected second resource.

11. The method of claim 10, wherein the selected second resource is an earliest available resource in the CSI transmission window that meets one or more criteria.

12. The method of claim 10, wherein the selected second resource is in a same sub-channel as the selected first resource.

13. The method of claim 10, wherein the selected second resource is an earliest available resource in the CSI transmission window that is in a same sub-channel as the selected first resource.

14. The method of claim 10, wherein determining the CSI transmission window comprises determining a CSI transmission window start time and a CSI transmission window duration.

15. The method of claim 10, wherein the selected second resource is separated in time from the selected first resource by less than a duration of the CSI transmission window.