CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/716,236, filed August 8, 2018 and U.S. Provisional Application No. 62/736,802, filed September 26, 2018, the contents of which are incorporated herein by reference.

BACKGROUND

[0002] In wireless communication systems for vehicle to everything (V2X), or related systems, there are a growing number of use cases that have a variety of requirements such as high data rate, high spectrum efficiency, low power, low latency, high reliability, and the like. In order to address these requirements, there is a need for an improvement of communication protocols efficiency and effectiveness.

SUMMARY

[0003] Systems, methods, and devices for ensuring reliable sidelink data transmissions. A wireless transmit receive unit (WTRU) may have a transceiver and a processor. The WTRU may receive a control channel with side link control information regarding a data transmission to be received in a shared channel. The data transmissions may be an initial transmission, or a retransmission depending on whether feedback was previously provided by the WTRU indicating that a transmission was completely received. The WTRU may decode the data transmission and send HARQ feedback. In some cases, the WTRU may perform beam-based transmissions. The WTRU may utilize beam sweeping and sensing for the beam-based transmissions. The WTRU may use course and fine beam tuning.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein like reference numerals in the figures indicate like elements, and wherein:

[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. 1A 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. 1A 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. 1A according to an embodiment;

[0009] FIG. 2 illustrates an example of resource allocation indication for PSSCH

(re)transmissions in LTE V2X;

[0010] FIG. 3 illustrates an example of resource allocation for 2 PSSCH retransmissions in

NR V2X;

[001 1] FIG. 4 illustrates an example of resource allocation for 3 PSSCH retransmissions in

NR V2X;

[0012] FIG. 5 illustrates an example of PSCCFI scheduling for multiple PSSCH resources;

[0013] FIG. 6A illustrates an example of a an example procedure of a WTRU receiving sidelink data, sensing, and selecting resources for FIARQ feedback for unicast/groupcast;

[0014] FIG. 6B illustrate an example of PSCCFI as it relates to retransmission;

[0015] FIG. 7 illustrates an example of a procedure for beam-based transmission;

[0016] FIG. 8A illustrates an example of a fine beam-based groupcast;

[0017] FIG. 8B illustrates an example of a coarse beam-based groupcast;

[0018] FIG. 9 illustrates an example of different modes of coarse beam-based groupcast for different QoS requirements;

[0019] FIG. 10 illustrates an example resource pool configuration;

[0020] FIG. 1 1 illustrates an example of coarse beam directions that may be derived based on GPS locations;

[0021] FIG. 12 illustrates an example of fine tune beam directions for accurate transmissions; and

[0022] FIG. 13 illustrates an example procedure of beam-based NR V2X groupcast.

DETAILED DESCRIPTION

[0023] 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.

[0024] 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 1 10, and other networks 1 12, 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 WTRU/UE.

[0025] The communications systems 100 may also include a base station 1 14a and/or a base station 114b. Each of the base stations 1 14a, 1 14b 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 1 10, and/or the other networks 112. By way of example, the base stations 1 14a, 1 14b may be a base transceiver station (BTS), a Node-B, an eNode B, a Flome Node B, a Flome eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 1 14a, 1 14b are each depicted as a single element, it will be appreciated that the base stations 1 14a, 1 14b may include any number of interconnected base stations and/or network elements.

[0026] The base station 114a may be part of the RAN 104/1 13, 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 1 14a and/or the base station 1 14b 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 1 14a may be divided into three sectors. Thus, in one embodiment, the base station 1 14a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 1 14a 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.

[0027] The base stations 114a, 114b may communicate with one or more of the WTRUs

102a, 102b, 102c, 102d over an air interface 1 16, 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 1 16 may be established using any suitable radio access technology (RAT).

[0028] 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 1 14a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 1 15/116/1 17 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (FISPA+). HSPA may include High-Speed Downlink (DL) Packet Access (FISDPA) and/or High- Speed UL Packet Access (FISUPA).

[0029] 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 1 16 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0030] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 1 16 using New Radio (NR).

[0031] In an embodiment, the base station 1 14a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 1 14a 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).

[0032] In other embodiments, the base station 1 14a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.1 1 (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.

[0033] The base station 1 14b in FIG. 1A may be a wireless router, Flome Node B, Flome 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 802.1 1 to establish a wireless local area network (WLAN). In an embodiment, the base station 1 14b 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 1 14b 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 1 14b may have a direct connection to the Internet 1 10. Thus, the base station 1 14b may not be required to access the Internet 1 10 via the CN 106/115.

[0034] The RAN 104/1 13 may be in communication with the CN 106/1 15, 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 106/1 15 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 106/1 15 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/1 13 or a different RAT. For example, in addition to being connected to the RAN 104/1 13, which may be utilizing a NR radio technology, the CN 106/1 15 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology. [0035] The CN 106/1 15 may also serve as a gateway for the WTRUs 102a, 102b, 102c,

102d to access the PSTN 108, the Internet 1 10, and/or the other networks 1 12. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 1 10 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 1 12 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 1 12 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.

[0036] 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. 1A may be configured to communicate with the base station 1 14a, which may employ a cellular-based radio technology, and with the base station 1 14b, which may employ an IEEE 802 radio technology.

[0037] 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 1 18, 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 subcombination of the foregoing elements while remaining consistent with an embodiment.

[0038] The processor 1 18 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 1 18 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 1 18 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 1 18 and the transceiver 120 as separate components, it will be appreciated that the processor 1 18 and the transceiver 120 may be integrated together in an electronic package or chip.

[0039] 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 1 16. 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.

[0040] 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 1 16.

[0041] 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 802.1 1 , for example.

[0042] The processor 1 18 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 1 18 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 1 18 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 1 18 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).

[0043] 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. [0044] The processor 1 18 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 1 16 from a base station (e.g., base stations 1 14a, 1 14b) 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.

[0045] 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.

[0046] 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 139 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 1 18). 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)).

[0047] 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 116. The RAN 104 may also be in communication with the CN 106. [0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 1 12, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0055] In representative embodiments, the other network 1 12 may be a WLAN.

[0056] 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 802.1 1e DLS or an 802.1 1 z 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.

[0057] When using the 802.1 1 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 802.1 1 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0058] 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. [0059] 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).

[0060] Sub 1 GHz modes of operation are supported by 802.1 1 af and 802.1 1 ah. The channel operating bandwidths, and carriers, are reduced in 802.1 1 af and 802.1 1 ah relative to those used in 802.1 1 h, and 802.11 ac. 802.1 1 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).

[0061] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 h, 802.1 1 ac, 802.11 af, and 802.1 1 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.1 1 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. [0062] In the United States, the available frequency bands, which may be used by

802.1 1 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 802.1 1 ah is 6 MHz to 26 MHz depending on the country code.

[0063] 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 1 13 may also be in communication with the CN 115.

[0064] 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 1 16. 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).

[0065] 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).

[0066] 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.

[0067] 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.

[0068] The CN 1 15 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.

[0069] 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. [0070] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 1 15 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 WTRU 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.

[0071] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b,

180c in the RAN 1 13 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0072] 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 1 15 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.

[0073] Although the WTRU is described in FIGs. 1A-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.

[0074] In view of FIGs. 1A-1 D, and the corresponding description of FIGs. 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-ab, 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. [0075] 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.

[0076] 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.

[0077] The wireless communication systems as described herein may support many different deployment environments for wireless communications networks, such as indoor sports, dense urban areas, rural areas, urban macro environments, high speed transportation, and the like. In addition to these deployment environments, there may also be deployment situations with specific performance requirements, such as Enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (mMTC) and Ultra Reliable and Low Latency Communications (URLLC). Depending on the use case, there may be a focus on different requirements such as higher data rate, higher spectrum efficiency, low power and higher energy efficiency, lower latency, and/or higher reliability.

[0078] Cellular based Vehicle to Everything (V2X) communication may refer to a deployment environment that focuses on the communication between vehicles, and also between vehicles and entities in their environment. V2X may employ any communication technology that suits the deployment scenario and technical demands of a use case in that environment. There may be use cases in V2X that have specific technical demands, such as vehicle platooning, sensor and state map sharing, remote driving, and automated cooperative driving. As discussed herein, an entity in a V2X environment (e.g., vehicle, pedestrian with a device, road infrastructure, etc.) may be referred to interchangeably as a“user” or“WTRU” or“vehicle” unless otherwise specified. [0079] V2X may offer improvements and benefits to various deployment scenarios. For example, in the use case of vehicle platooning where a group of vehicles are operated in a closely linked manner so that the vehicles move like a train with virtual strings attached between vehicles, in order to maintain vehicle distance, the vehicles may share status information among themselves using V2X. By using this V2X enabled platooning technique, the distances between vehicles may be reduced, and the number of needed drivers may be reduced. This could also lower the overall fuel consumption for the vehicles.

[0080] In one example of a V2X deployment scenario, signals may be blocked by other vehicles, called vehicle blockage, which may result in a disabling reduction of signal strength, especially for high carrier frequency (e.g., above 6 GHz), such as used in NR technologies. In order to address this, vehicle blockage may be treated as a separate state, beyond line-of-sight state and non-line-of-sight state.

[0081] As V2X advances, there is a need to develop systems, methods, and devices that address various V2X deployment scenarios. In one or more embodiments, obtaining more reliable transmissions on NR V2X sidelink may be addressed, where NR URLLC requires a high level of reliability. In a V2X sidelink design, it may be desirable to have more than one retransmission. To achieve the high reliability for NR V2X more retransmissions may be used. Furthermore, for unicast or groupcast, the transmitting WTRU may require feedback from the receiving WTRU to achieve high reliability. Systems, methods, and devices may be discussed herein that address schemes (e.g., including resource allocation, data redundancy versions, etc.) to implement more than 1 retransmission.

[0082] Additionally, there may be one or more embodiments where beam-based NR V2X sidelink transmission may be addressed. NR V2X sidelink frequency may support both Sub 6GHz frequencies (FR1 ) and mmW frequencies (FR2). Beamforming may be essential to compensate for high path loss at high frequencies. In LTE V2X sidelink, there may be broadcast transmissions. In NR V2X sidelink, there may be unicast, groupcast, and broadcast transmissions. In order to address NR V2X sidelink, there may be a beam-based common or unified design for FR1 and FR2 to support NR V2X sidelink unicast, groupcast, and broadcast. Additionally, in a beam-based NR V2X system, a WTRU in a V2X environment may need to address possible problems for reliable sidelink data transmission. For example, what beam direction a WTRU should use is important because if a beam direction from the transmitting WTRU is not aligned well with the receiving WTRU(s), it may be a waste of resources to select and allocate resources for a data transmission. Also, a specific beam direction, resource pool, or resource set may be needed for beam-based NR V2X sidelink transmission if there are overlapping beams which are currently active. [0083] Any of the techniques discussed regarding an embodiment may be used interchangeably with other techniques of the same embodiment or different embodiments, which may include swapping or substituting entities, actions, methodologies, formats, and the like.

[0084] Generally, in V2X, a vehicle may be in transmission mode 3 (i.e., mode 3 user) or may be in transmission mode 4 (i.e., mode 4 user). A mode 3 user may directly use the resources allocated by a base station for the sidelink (SL) communication among vehicles or between a vehicle and a pedestrian. A mode 4 user may obtain a list of candidate resources allocated by a base station and may select a resource among the candidate resources for its SL communication.

[0085] In some cases, for LTE the DCI format 5A may be used for the scheduling of

Physical Sidelink Control Channel (PSCCH), as well as several Side Link Control Information (SCI) format 1 fields used for the scheduling of Physical Sidelink Shared Channel (PSSCH). The payload of DCI format 5A may include: carrier indicator, which may be 3 bits; lowest index of the subchannel allocation to the initial transmission, which may be fiog ₂ (/v _s ¾ _channel )] bits; SCI format 1 fields, which may include frequency resource location of initial transmission and retransmission and the time gap between initial transmission and retransmission; and/or, SL index, which may be 2 bits and may only be present for cases with TDD operation with uplink-downlink configuration 0-6.

[0086] When the DCI format 5A CRC is scrambled with SideLink Semi-Persistent

Scheduling V-RNTI (SL-SPS-V-RNTI), the following fields may be present: SL SPS configuration index, which may be 3 bits; and/or activation/release indication, which may be 1 bit.

[0087] If the number of information bits in DCI format 5A mapped onto a given search space is less than the payload size of format 0 mapped onto the same search space, zeros may be appended to DCI format 5A until the payload size equals that of format 0 including any padding bits appended to format 0.

[0088] If the DCI format 5A CRC is scrambled by SL-V-RNTI and if the number of information bits in DCI format 5A mapped onto a given search space is less than the payload size of DCI format 5A with CRC scrambled by SL-SPS-V-RNTI mapped onto the same search space, and format 0 is not defined on the same search space, zeros may be appended to DCI format 5A until the payload size equals that of DCI format 5A with CRC scrambled by SL-SPS-V-RNTI.

[0089] In some cases, the LTE SCI format 1 may be used for the scheduling of PSSCH.

The payload of SCI format 1 may include: priority, which may be 3 bits; resource reservation, which may be 4 bits; frequency resource location of initial transmission and retransmission, which may be bits; time gap between initial transmission and retransmission, which may be 4 bits; modulation and coding scheme, which may be 5 bits; retransmission index, which may be 1 bit; and reserved information bits, which may be added until the size of SCI format 1 is equal to 32 bits. The reserved bits may be set to zero.

[0090] In LTE V2X, the data retransmission may be supported with a maximum of 1 retransmission. For mode 3 WTRUs, the DCI format 5A may include fields“Frequency resource location of initial transmission and retransmission” and‘Time gap between initial transmission and retransmission.”

[0091] The “Frequency resource location of initial transmission and retransmission” parameter may be equal to the resource indication value (RIV), which can be used to derive: Lsu _b c _H the number of contiguously allocated sub-channels (for both initial transmission and retransmission), and ^: the starting sub-channel index (of the re-transmission).

[0092] The “Time gap between initial transmission and retransmission” parameter may provide the information about the time gap SF _gap . Upon receiving the DCI format 5A, a mode 3 WTRU may determine the sub-frame (i.e., 7 ) of the initial transmission from the field“SL index” and the starting sub-channel index (i.e., F of the initial transmission from the field“Lowest index of the sub-channel allocation to the initial transmission”. These 7 and F ₁ may provide the resources for the initial transmission.

[0093] In the case of SF _gap = 0, (i.e., no retransmission), the transmitting WTRU may set the corresponding SCI fields as follows: “Frequency resource location of initial transmission and retransmission” is calculated by L _subCH and F ₁ from the DCI 5A it receives, and“Time gap between initial transmission and retransmission” may be equal to 0.

[0094] In the case of SF _gap ¹ 0, the transmitting WTRU may set the SCI fields of the initial transmission as follows: “Frequency resource location of initial transmission and retransmission” may be calculated by L _subCH and n _s ^s ^ _b ^r c _H from the DCI 5A it receives;“Time gap between initial transmission and retransmission” may be equal to SF _gap from the DCI 5A it receives; and“Retransmission index” may be equal to 0.

[0095] For the resources of the retransmission (i.e., SF _gap ¹ 0), a mode 3 WTRU may determine the sub-frame as ( T ₂ = T ₁ + SF _gap ) and the starting sub-channel index as (i.e., F ₂ ) from the DCI 5A it receives.

[0096] The WTRU may set the SCI fields of the retransmission as follows: “Frequency resource location of initial transmission and retransmission” may be calculated by L _subCH from the DCI 5A it receives and F _x ;“Time gap between initial transmission and retransmission” may be equal to SF _gap from the DCI 5A it receives; and“Retransmission index” may be equal to 1. [0097] A mode 4 WTRU may know the number of sub-channels L _subCH to be used for

PSSCH transmission in a subframe based on information/indication from the higher layer. Mode 4 WTRUs may determine the available time and frequency resources for initial transmission and retransmission based on sensing and/or RSRP measurement. For example, the first selected resource may correspond to sub-frame 7 and the starting sub-channel index F and the second selected resource may correspond to sub-frame T ₂ and the starting sub-channel index F ₂ , where T ₁ < T ₂ £ T ₁ + 15.

[0098] A mode 4 WTRU may set the SCI fields of the initial transmission as follows:

“Frequency resource location of initial transmission and retransmission” may be calculated by Lsu _bCH and F ₂ ; “Time gap between initial transmission and retransmission” may be equal to T ₂ - Ti, and“Retransmission index” may be equal to 0.

[0099] A mode 4 WTRU may set the SCI fields of the retransmission as follows:

“Frequency resource location of initial transmission and retransmission” may be calculated by Lsu _bCH and F _x ; “Time gap between initial transmission and retransmission” may be equal to T ₂ - Ti, and“Retransmission index” may be equal to 1.

Table 1 : Example SCI contents for at most 1 retransmission

[00100] Table 1 shows the SCI contents of the initial transmission and the retransmission in LTE V2X. FIG. 2 shows an example resource allocation indication for PSSCH (re)transmission in LTE V2X. Time 201 (e.g., slot) is shown on the horizontal axis, and frequency 202 (e.g., subchannel) is shown on the vertical axis. The initial transmission happens at and F The retransmission happens at r ₂ and F ₂ . In the initial transmission, the SCI 204 may contain a frequency location of the retransmission F ₂ , time gap between T ₂ and 7 , and a retransmission index of 0. In the retransmission, the SCI 205 may contain the frequency location F _lt time gap between T ₂ and T _lt and a retransmission index of 1. The L _SUb c _H per resource 203 may show the number of contiguously allocated sub-channels for each transmission (e.g., the shaded blocks). [00101] As discussed herein, mode 3 or LTE mode 3 may be interchangeably used with mode 1 or NR mode 1 , which may be defined as base stations scheduling sidelink resources to be used by a WTRU for sidelink transmissions. Mode 4 or LTE mode 4 may be interchangeably used with mode 2 or NR mode 2, which may be defined as where a WTRU determines (i.e., base station does not schedule) the sidelink transmission resources within the sidelink resources, which are configured by the base station / network or are pre-configured sidelink resources.

[00102] In NR V2X, there may be a data transmission with more than one retransmission in order to increase the reliability level of the PSSCH transmission. Consequently, there is need for resource allocation schemes for NR PSSCH (re)transmission. In some approaches DCI or SCI signaling mechanisms may be used.

[00103] In a first scheme, there may be a mechanism for a mode 3 WTRU with two or more retransmissions. Upon receipt of a NR DCI format, a mode 3 WTRU may determine the slot (i.e., from the field“SL index”, and the starting sub-channel index of the initial transmission (i.e., F _x ) from the field“Lowest index of the sub-channel allocation to the initial transmission”.

[00104] The time unit for each NR resource may be in terms of slot or sub-slot. For illustration purposes, slot may be used as a unit of time, and it may be interchangeable with sub-slot as discussed herein.

[00105] In the case of SF _{gap l} = 0 and/or SF _{gap 2} = 0 (i.e., no retransmission or 1 retransmission), the transmitting WTRU may set the SCI fields for the initial transmission and retransmission as described above.

[00106] In the case of SF _{gap l} ¹ 0 and SF _{gap 2} ¹ 0, (i.e., 2 retransmissions), the ^ and F may provide the resources for the initial transmission. For the resources of the first retransmission, a mode 3 WTRU may determine the slot as {T ₂ = T ₁ + SF _{gap l} ) and the starting sub-channel index as F ₂ = ^h _H, i from the NR DCI it receives. For the resource of the second retransmission, a mode 3 WTRU may determine the slot as [T ₃ = T ₂ + SF _{gap 2} ) and the starting sub-channel index as F ₃ = n _s ^s ^c _H,2 from the DCI 5A it receives.

[00107] The transmitting WTRU may set the SCI fields of the initial transmission as follows: “Frequency resource location of initial transmission and retransmission” may be calculated by L _S u _b c _H,i and n ^s fc _{H, i} = from the DCI 5A it receives;“Time gap between initial transmission and retransmission” may be equal to SF _{gap l} from the DCI 5A it receives; and“Retransmission index” may be equal to 0.

[00108] The transmitting WTRU may set the SCI fields of the first retransmission as follows: “Frequency resource location of the first retransmission and the second retransmission” may be calculated by L _{subCH 2} and 2 = from ^the DCI 5A it receives;“Time gap between the first retransmission and the second retransmission” may be equal to SF _{gap 2} from the DCI 5A it receives; and“Retransmission index” may be equal to 1.

[00109] For the second retransmission (i.e., SF _{gap 2} ¹ 0), a mode 3 WTRU may determine the slot as ( T ₃ = T ₂ + SF _{gap 2} ) and the starting sub-channel index as F _s = ^h *! _H,2 from the DCI 5A it receives. Furthermore, the WTRU may set the corresponding SCI fields as follows: “Frequency resource location of the first retransmission and the second retransmission” may be calculated by L _subCH/2 from the DCI 5A it receives and F ₂ , “Time gap between the first retransmission and the second retransmission” may be equal to SF _{gap 2} from the DCI 5A it receives; and“Retransmission index” may be equal to 2.

[001 10] The field of“Frequency resource location of initial transmission and retransmission” in SCI of the initial transmission and the field of “Frequency resource location of the first retransmission and the second retransmission” in SCI of the retransmissions may be called the field of“Frequency resource location of current transmission and neighbor (or next) transmission”.

[001 11] Similarly, the field of ‘Time gap between initial transmission and retransmission” in SCI of the initial transmission and the field of “Time gap between the first retransmission and the second retransmission” in SCI of the retransmissions may be called the field of“Time gap between current transmission and neighbor (or next) transmission”.

[001 12] The first scheme with the SCI signal indication may be summarized in Table 2.

[001 13] FIG. 3 shows an example resource allocation indication for PSSCH transmission with two retransmissions in NR V2X, as discussed above. Time 301 (e.g., slot) is shown on the horizontal axis, and frequency 302 (e.g., sub-channel) is shown on the vertical axis. The initial transmission happens at 7 and F _t . The first retransmission happens at T ₂ and F ₂ . The second retransmission happens at r ₃ and F ₃ . In the initial transmission, the SCI 304 may contain a frequency location of the retransmission F ₂ , time gap between and T ₂ , and a retransmission index of 0. In the first retransmission, the SCI 305 may contain the frequency location F ₃ , time gap between T ₃ and T ₂ , and a retransmission index of 1. In the second retransmission at T ₃ , the SCI 306 may contain the frequency location F ₂ , time gap between T ₃ and T ₂ , and a retransmission index of 2. The L _subCH per resource 303 may show the number of contiguously allocated subchannels for each transmission (e.g., the shaded blocks).

[001 14] As shown in FIG. 3, the“retransmission index” in the SCI of the three transmissions may be equal to 0, 1 , and 2, respectively. This is based on the assumption that the maximum number of retransmissions, being 2, may be known to the receiver. Explained another way, once the receiver decodes the SCI of the first retransmission, it may continue to decode the next retransmission. Once the receiver decodes the SCI of the second retransmission with the “retransmission index” being 2, then it may know to stop receiving any further retransmissions. In this example, each SCI may contain 4 bits for SF _gap (i.e., for up to a 15 ms gap between the two (re)transmissions) and 2 bits for the retransmission index.

[001 15] In an alternative to the above described first scheme, there may be a second scheme used for mode 3 WTRU(s), where the SCI signal indication may be summarized in Table 3 and described below.

[001 16] In the case of SF _{gap l} = O and/or SF _{gap 2} = O (i.e., no retransmission or 1 retransmission), the transmitting WTRU may set the SCI fields for the initial transmission and retransmission, as described herein with regard to LTE V2X sidelink data retransmissions, with the SFgap ⁱⁿ the retransmission set as 0.

[001 17] In the case of SF _{gap l} ¹ O and SF _{gap 2} ¹ O, (i.e., 2 retransmissions), the 7 and F ₁ may provide the resources for the initial transmission. For the resources of the first retransmission, a mode 3 WTRU may determine the slot as {T ₂ = T ₁ + SF _{gap l} ) and the starting sub-channel index as F ₂ = n _s ^s ^ _H,i f ^rom the NR DCI it receives. For the resource of the second retransmission, a mode 3 WTRU may determine the slot as ( T ₃ = T ₂ + SF _{gap 2} ) and the starting sub-channel index as F ₃ = from the DCI 5A it receives.

[001 18] The transmitting WTRU may set the SCI fields of the initial transmission as follows: 1 )“Frequency resource location of initial transmission and retransmission” is calculated by L _SU bcH,i and n¾ = F ₂ from the DCI 5A it receives; 2) ‘Time gap between initial transmission and retransmission” is equal to SF _{gap l} from the DCI 5A it receives; and 3)“Retransmission index” is equal to 0.

[001 19] The transmitting WTRU may set the SCI fields of the first retransmission as follows: 1 ) “Frequency resource location of the first retransmission and the second retransmission” is calculated by L _{subCH 2} = ^F s from ^the DCI 5A it receives; 2)‘Time gap between the first retransmission and the second retransmission” is equal to SF _{gap 2} from the DCI 5A it receives; and 3)“Retransmission index” is equal to 1.

[00120] For the second retransmission (i.e., SF _{gap 2} ¹ O), a mode 3 WTRU may determine the slot as {T ₃ = T ₂ + SF _{gap 2} ) and the starting sub-channel index as F ₃ = n^cH 2 from the DCI 5A it receives. Furthermore, the WTRU may set the corresponding SCI fields as follows: 1 ) “Frequency resource location of the first retransmission and the second retransmission” is calculated by L _subCH/2 from the DCI 5A it receives and F ₂ , 2) “Time gap between the first retransmission and the second retransmission” is equal to O from the DCI 5A it receives; and 3) “Retransmission index” is equal to 2. Note that“Retransmission index” may or may not present in the SCI signal indication fields or be listed in Table 3 for the second scheme used for mode 3 or NR mode 1 WTRU(s).

Table 3: Exemplary SCI contents for at most 2 retransmissions (second scheme)

[00121] In one scenario, the first scheme may be used with mode 4 WTRU(s) with two retransmissions, from the higher layer, where the mode 4 WTRU may know the number of subchannels L _subCH to be used for PSSCH transmission in a subframe. Here, the common number of sub-channels may be used in the initial transmission and retransmissions. In some cases, the initial transmission and retransmission may occupy different numbers of sub-channels. [00122] Mode 4 WTRUs may determine the available time and frequency resources for initial transmission and the two retransmissions based on sensing and/or RSRP measurement. The first selected resource may correspond to slot 7 and the starting sub-channel index F _t , the second selected resource may correspond to slot T ₂ and the starting sub-channel index F ₂ , and the third selected resource may correspond to slot T ₃ and the starting sub-channel index F ₃ , where 7 < T2 £= T _j + 15 and T ₂ T ₃ T ₂ -l· 15.

[00123] Mode 4 WTRUs may apply similar retransmission schemes as mode 3 WTRUs as described above, for example, using the examples found in FIG. 3 or Table 2 relating to the first scheme.

[00124] Mode 4 WTRUs may set the SCI fields for the initial transmission as:“Frequency resource location of the current transmission and the previous/next transmission” may be calculated by L _subCH and F ₂ ;‘Time gap between the current transmission and the previous/next transmission” is equal to T ₂ - 7 ; and“Retransmission index” may be equal to 0.

[00125] Mode 4 WTRUs may set the SCI fields for the first retransmission as:“Frequency resource location of the current transmission and the previous/next transmission” may be calculated by L _subCH and F ₃ ;‘Time gap between the current transmission and the previous/next transmission” may be equal to T ₃ - T ₂ , and“Retransmission index” may be equal to 1.

[00126] Mode 4 WTRUs may set the SCI fields for the second retransmission as: “Frequency resource location of the current transmission and the previous/next transmission” may be calculated by L _subCH and F ₂ ,“Time gap between the current transmission and the previous/next transmission” may be equal to T ₃ - T ₂ ;“Retransmission index” may be equal to 2.

[00127] Similarly, for the second scheme (i.e., Table 3), mode 4 WTRU may set the SCI fields for the initial transmission as scheme 1 with the exception of the second retransmission,“Time gap between the current transmission and the previous/next transmission” is equal to 0. Note that “Retransmission index” may or may not present in the SCI signal indication fields or be listed in Table 3 for the second scheme used for mode 4 or NR mode 2 WTRU(s).

[00128] In one scenario, a WTRU(s) may have more than 2 retransmissions, such as 3 retransmissions. The previously described first scheme for mode 3 WTRUs with 2 retransmissions may be extended to support 3 retransmissions, which may be demonstrated by extending the example of FIG. 3, as shown in Table 4 and FIG. 4. In this scenario, only up to 3 retransmissions are described, but the same techniques may be used to enable more than 3 transmissions.

Table 4: Example SCI contents for at most 3 retransmission (first scheme)

[00129] FIG. 4 shows an example resource allocation for 3 PSSCH retransmissions in NR V2X. While 3 retransmissions are discussed, the principles and techniques may be extended to more retransmissions (e.g., 4, 5, 6, etc.). Time 401 (e.g., slot) is shown on the horizontal axis, and frequency 402 (e.g., sub-channel) is shown on the vertical axis. The initial transmission happens at 7 and F ₄ . The first retransmission happens at T ₂ and F ₂ . The second retransmission happens at r ₃ and F ₃ . The third retransmission happens at r ₄ and F ₄ . The L _subCH per resource 403 may show the number of contiguously allocated sub-channels for each transmission (e.g., the shaded blocks). In the initial transmission, the SCI 404 may contain a frequency location of the retransmission F ₂ , time gap between 7 and T ₂ , and a retransmission index of 0. In the first retransmission, the SCI 405 may contain the frequency location F ₃ , time gap between T ₃ and T ₂ , and a retransmission index of 1. In the second retransmission at T ₃ , the SCI 406 may contain the frequency location F ₂ , time gap between T ₃ and T ₂ , and a retransmission index of 2. In the third retransmission at T ₄ , the SCI 407 may contain the frequency location F ₃ , time gap between G ₄ and T ₃ , and a retransmission index of 3. [00130] Additionally, the previously described second scheme for mode 3 WTRUs or NR mode 1 WTRU(s) with 2 retransmissions may be extended to support 3 retransmissions, as shown in Table 5. Note that“Retransmission index” may or may not present in the SCI signal indication fields or be listed in Table 5 for the second scheme used for mode 3 or NR mode 1 WTRU(s). The time gap for a PSSCH (re)transmission may be set to zero to indicate the corresponding PSSCH is a last (re)transmission. The schemes described above for three retransmissions could be extended to more than 3 retransmissions. Similarly, scheme 1 as shown in Table 4 and scheme 2 as shown in Table 5 may be applied for mode 4 or NR mode 2 WTRUs to support 3 retransmissions. Note that “Retransmission index” may or may not present in the SCI signal indication fields or be listed in Table 5 for the second scheme used for mode 4 or NR mode 2 WTRU(s). The time gap for a PSSCH (re)transmission may be set to zero to indicate the corresponding PSSCH is a last (re)transmission in Table 5. The schemes described above for three retransmissions could be extended to more than 3 retransmissions for mode 4 or NR mode 2 WTRU(s).

[00131] As discussed herein, the above techniques and examples may be based on where the HARQ process is not activated. If the HARQ process was activated (e.g., for NR V2X sidelink unicast or groupcast) then the NR SCI may include the HARQ process number. In such a case, the repetition may be automatically disabled or the associated schemes may be ignored by the receiver WTRU.

[00132] In view of the above, there may be one or more approaches for the WTRU to receive a PSCCH in situation(s) where there is a data transmission with more than one retransmission. For each PSCCH resource configuration associated with sidelink transmission LTE mode 3 or NR mode 1 , a WTRU configured by higher layers to detect NR SCI format (e.g., SCI format 1 or the like or NR new SCI format) on PSCCH may attempt to decode the PSCCH according to the PSCCH resource configuration. The WTRU may not be required to decode more than one PSCCH at each PSCCH resource candidate.

[00133] In a scenario where the "Reserved bits" in SCI format 1 are reused or reinterpreted to support more than one retransmission for a NR V2X WTRU, the LTE mode 3 WTRU may not assume any value for the "Reserved bits" before decoding a SCI format 1 , and the NR mode 1 WTRU may assume the values proposed above before decoding a SCI format 1. If a HARQ process is activated then the“Reserved bits" may be reused or reinterpreted to support HARQ. In a case where there is a SCI format specific to NR V2X, the NR mode 1 WTRU may not assume any value for the "Reserved bits" before decoding a new SCI format.

[00134] For each PSCCH resource configuration associated with sidelink transmission LTE mode 4 or NR mode 2, a WTRU configured by higher layers to detect NR SCI format (e.g., SCI format 1 or NR SCI format) on PSCCH may attempt to decode the PSCCH according to the PSCCH resource configuration. The WTRU may not be required to decode more than one PSCCH at each PSCCH resource candidate.

[00135] In a case where the "Reserved bits" in SCI format 1 are reused or reinterpreted to support more than one retransmission for NR V2X WTRU, the LTE mode 4 WTRU may not assume any value for the "Reserved bits" before decoding a SCI format 1 , and the NR mode 2 WTRU may assume the values proposed above before decoding a SCI format 1. If a HARQ process is activated then the“Reserved bits" may be reused or reinterpreted to support HARQ. In a case where there is a SCI format specific to NR V2X, the NR mode 2 WTRU may not assume any value for the "Reserved bits" before decoding a new SCI format.

[00136] In view of the above, there may also be one or more approaches for the WTRU to receive a PSCCH scheduling multiple transport block (TB) where there may be a data transmission with more than one (re)transmission. In LTE V2X sidelink transmissions, the PSCCH and PSSCH may be in the same sub-frame. The SCI on the PSCCH may indicate the resources used for PSSCH. The same TB may be repeatedly transmitted where the SCI associated with the initial transmission also indicates the resources for the retransmissions (i.e., without the HARQ feedback). In contrast, for NR V2X sidelink transmissions, a single SCI format may support or indicate the scheduling of the transmissions of multiple TBs on multiple PSSCHs. This may reduce the control signaling overhead. The scheduling and/or transmission unit may be slot or sub-slot (e.g., mini-slot or non-slot or one or more symbols). As discussed herein, (sub)slot may indicate a unit of resource in the time domain to support more refined granularity and NR V2X flexible sidelink frame structure (i.e., slot-based and non-slot/symbol-based SL frame structure).

[00137] There may be differences between the transmissions described herein and SPS transmissions, such as the transmission approaches described herein being more flexible. The transmission interval of the data may not need to be periodic, and the frequency resources used for multiple data transmissions may not need to be the same. The difference between NR SCI and LTE SCI sidelink retransmission schemes may be that NR approaches may support the transmission of different TBs, or different payloads on different PSSCH transmissions, while the LTE V2X sidelink retransmission approaches may send the same data or apply to the same TB on different PSSCH transmissions.

[00138] FIG. 5 shows an example of a single PSCCH (i.e., a single NR SCI format carried in a PSCCH) scheduling of multiple PSSCH. The SCI of this PSCCH may contain the information about a few resource locations, where each may be used for a different TB. Time resources are shown in the horizontal axis 501 and frequency resources are shown in the vertical axis 502. Each time resource block may be a slot 506 (or sub slot). Time resource for PSSCH and PSCCH may be same or different. The PSCCH Resources 505 are at the top of FIG. 5, and the PSSCH Resources 503 are at the bottom of FIG. 5. The frequency resource of the PSSCH may indicate as 504 SizeSubchannel. The frequency resource of the PSCCH may be pre-specified or (pre)configured or signaled to a certain value (e.g., 2RBs) that may be smaller than 504 SizeSubchannel. All of the boxes filled with the same angled lines are example of a single PSCCH (or a SCI) scheduling multiple TBs or multiple PSSCH transmissions for different TBs (e.g., PSCCH 510 schedules PSSCH 51 1 , 512, 513, and PSCCH 520 schedules 521 , 522, 523). The maximum number of different TBs scheduled by a SCI or a PSCCH may be pre-specified or (pre)configured or indicated in SIB or RRC message or L2 or L1 signaling.

[00139] The SCI may contain the following additional information for the multiple resource reservations for multiple TBs on multiple PSSCHs. For each resource except the one for the first TB, there may be a pair of parameters to indicate the time and frequency resource offset for other TBs with respect to the resource for the first TB. There may be more than one way to define the two parameters. In one example, the first parameter may define the (sub)slot offset to the resource for transmitting the first TB. The second parameter may define the sub-channel offset to the resource for transmitting the first TB.

[00140] In another example, for each resource except the one for the first TB, there may be a pair of parameters to indicate the time and frequency resource offset for the current TB with respect to the resource for the previous TB. Specifically, the first parameter may define the (sub)slot offset for the current TB to the resource for transmitting the previous TB. The second parameter may define the sub-channel offset for the current TB to the resource for transmitting the previous TB.

[00141] Besides these two parameters, an additional resource allocation may be defined for the retransmissions of each TB. This may follow the LTE SCI format 1 with the parameters of “Frequency resource location of initial transmission and retransmission” and“Time gap between initial transmission and retransmission” or NR new format proposed above with the parameters of “Frequency resource location of (re)transmission” and“Time gap between current Tx and neighbor (or next) Tx”. If the resource relationship between initial transmission and retransmission for the first TB is the same as that for the second TB or the remaining TBs, then this definition may be ignored for the second or remaining TBs. The use of multiple TBs may apply to any NR scenario, such as broadcast, groupcast and unicast.

[00142] Another consideration when using more than one retransmission in NR V2X may be the consideration of FIARQ feedback and resource selection for mode 4 or NR mode 2 WTRUs. For groupcast or unicast cases, a receiving WTRU may need to send the FIARQ feedback to the transmitting WTRU.

[00143] FIG. 6A shows an example procedure where the WTRU is receiving sidelink transmissions and sending FIARQ feedback. Initially, a receiving WTRU may first receive and detect a SCI on a PSCCFI at 601. Generally, the WTRU may use this detected SCI to determine resources of the current and future transmissions for one or more TBs. The WTRU may also use this detected SCI to determine the PSSCFH decoding parameters such as Modulation and coding scheme, or the like. Next, at 602 the traffic type is determined (e.g., groupcast, unicast, or broadcast). The traffic type may be determined by: an indication in the SCI; the CRC mask with WTRU-ID (e.g., RNTI, C- RNTI, CS-RNTI, IMSI, s-TMSI, and/or any RNTI assigned or configured to the WTRU) or group ID (e.g., group-RNTI such as an RNTI assigned or configured for the group of WTRUs); and/or, the different scrambling sequences (e.g., or different initialization values of a certain scrambling sequence) on top of rate matched bit sequence. [00144] If the PSSCH data is for broadcast, then the receiving WTRU may decode the PSSCH at 603.

[00145] If the PSSCH data is for groupcast or unicast, which requires HARQ feedback, then the receiving WTRU may need to obtain the HARQ feedback latency requirement 604 from the received SCI 601 , and/or check its capability of the PSSCH decoding delay (i.e., latency). Based on these latency requirements, the receiving mode 4 or NR mode 2 WTRU may determine sensing and a resource selection window for the HARQ feedback at 605. Specifically, the WTRU may determine a sensing and resource selection window based on the determined latency requirements, and the WTRU may exclude resources reserved for multiple TBs with more than one transmission based on the detected SCI. The resource pool for sending sidelink HARQ feedback may be a separate resource pool from the one for data transmissions, or the resource pool could be the same as the one for sidelink control and/or data transmissions. Next, the receiving WTRU may decode the PSSCH at 606 based on the detected SCI. The WTRU may send HARQ feedback 607, using the selected resource. In the case of a successful decoding the mode 4 or NR mode 2 WTRU may send ACK information; if the decoding is unsuccessful, then the mode 4 or NR mode 2 WTRU may send NACK information. The ACK or NACK bits may be treated with a certain PUCCH format (e.g. PUCCH format 0 or PUCCH format 1 ).

[00146] FIG. 6B illustrates the flow of resources for the example of FIG. 6A. Generally, the PSCCH may carry or include the SCI, which may comprise an indication of PSSCH resources for one or multiple TBs. For each TB (e.g., that may support more than one transmission), the SCI may indicate the frequency resources for the current PSSCH and the next PSSCH (i.e., unless it is the last retransmission), and the SCI may also indicate the time gap (e.g., in slots) between the current and next PSSCH, which may be set to 0 for the last retransmission. The resources as indicated in the PSCCH are shown with the arrows of FIG. 6B.

[00147] In this example, there may be two TBs 610 and 620, and each TB may have multiple transmissions. TB 610 may have three transmissions 611 , 612, and 613, and TB 620 may have two transmissions. As discussed herein a retransmission may be labeled as a transmission since it is still transmitting data even though the data has already been transmitted, but a transmission is only a retransmission when the transmission is retransmitting data after an initial transmission. In the initial (i.e., first) transmission 61 1 , the PSCCH 611 a may contain an SCI that indicates the resources for the current PSSCH 61 1 b, the next PSSCH 612b in the next transmission 612 (i.e., retransmission), and the PSSCH 621 a of the first transmission 621 of the next transport block (i.e., TB 620). In the second transmission 612, the PSCCH 612a may indicate resources for PSSCH 612b, and PSSCH 613b. Resource indication may be similar for the third transmission 613, however, since this is the last retransmission then PSCCH 613a only provides resources for PSSCH 613b and the time gap indicated may be set to 0. The TB 620 may have a similar resource indication flow to TB 610.

[00148] In addition to, or alternatively to, the techniques discussed above, beam forming techniques for sidelink transmissions may be used to enhance the reliability of NR V2X. A NR V2X sidelink frequency may support both Sub 6GHz frequencies (FR1) and mmW frequencies (FR2). A beam based common unified design for FR1 and FR2 may be one approach to enable reliable NR V2X sidelink transmission including unicast, groupcast, and broadcast. Specifically, for a beam- based NR V2X sidelink transmission: a single beam may be used for unicast; a group or set of beams may be used for groupcast; and, and all beams or an omni-beam may be used for broadcast.

[00149] Without the loss of generality, the beam techniques, schemes, embodiments, and/or examples discussed herein may be described in the context of groupcast, but they may also be applied to unicast when the number of groupcast WTRUs is equal to 1 , and broadcast when all of the WTRUs around the transmitting WTRU are expected to receive the data.

[00150] FIG. 7 shows an example procedure of a beam-based transmission (i.e., groupcast). Generally, the WTRU may determine the available beam resources 701 (e.g., indicated by gNB, measured at the WTRU, etc.), perform transmission (TX) beam sweeping 702, perform beam sensing 703, determine the beam tuning type for the transmission 704, and then send the transmission 705 (e.g., or retransmission).

[00151] Regarding the beam sweeping 702, the WTRU may perform TX beam sweeping to determine target beam direction(s). Depending on the transmission type (e.g., groupcast, unicast, broadcast) a WTRU is going to support, a WTRU may need to determine one or multiple target beam direction(s). Generally, TX beam sweeping 702 may comprise a transmitter WTRU sending a reference signal, and in response to the reference signal a receiver WTRU may report back measurement information relative to the reference signal.

[00152] When a transmitter WTRU performs beam sweeping 702 over a group of candidate beams (e.g., beam direction and beam width for each candidate beam), resource allocation or selection for reference signal transmission may be needed (i.e., determining the available resources 701). For example, resource allocations/selections for transmitting sidelink reference signals (e.g., SL CSI-RS, SL synchronization signals, etc.) may be known to the receiver WTRU so that beam measurement and reporting may be performed at the receiver WTRU. Beam sweeping 702 may determine one or more target beams (including its direction).

[00153] For mode 1 NR V2X WTRUs (e.g., similar to mode 3 LTE V2X WTRUs), a radio resource may be allocated by a gNB. In this case, the radio resources for reference signals may be allocated by a gNB (i.e., as part of determining available resources 701), and the allocated resource may be configured/indicated to both the transmitter WTRU and the receiver WTRU such that the beam measurement reporting (e.g., reported reference signal index or resource index as part of the TX beam sweeping 702) from the receiver WTRU may be correctly interpreted (e.g., the reported reference index matching a unique swept beam during beam sweeping) by the transmitter WTRU.

[00154] For mode 2 NR V2X WTRU (e.g., similar to mode 4 LTE V2X WTRU), a radio resource may be determined by the WTRU itself (i.e., as part of determining available resources 701). In this case, the transmitter WTRU may need to perform an initial sweep and beam sensing for each swept beam before transmitting a reference signal during beam sweeping 702 (i.e., the prior beam sweeping and beam sensing would take place as part of determining the available resources 701). Then the WTRU may select a subset of resources that are not sensed to be used during the sensing time. The selected resources may be from one or multiple resource pool(s) that are known (i.e., previously configured) to the receiver WTRU. When the receiver WTRU tries to measure all possible resource locations based on the known resource pool(s), then the receiver WTRU may report the index for each successfully measured set of resources if measurement quantity (e.g., RSRP, RSRQP) meets certain criteria (e.g., higher than a threshold value or the top K best measurement value among all measured resources). Since the transmitter WTRU itself may perform the resource selection from the resource pool for each swept beam, the transmitter WTRU may be able to differentiate which beam is actually reported by the reported resource index from the receiver WTRU.

[00155] Regarding the beam sensing 703, the WTRU may perform beam sensing using a group of resource pools and resource sets over the determined target beam direction(s). If any active transmissions are identified, this may mean other active beam(s) are partially or fully overlapping with the determined beam direction(s). Collision avoidance may be needed for resource allocations. If no other active transmissions are identified, a resource allocation method may be used.

[00156] Note that for groupcast transmission, the beam techniques may assume that a WTRU performs simultaneous transmissions. For the case where a WTRU does not perform simultaneous transmission, the groupcast, if needed, may be supported by sequential unicast.

[00157] At 704, the WTRU may determine the beam tuning type for a data transmission in NR V2X. There may be two beam tuning types for beam-based groupcast, where each beam tuning type may provide different functionality as it relates to an antenna panel(s) of a WTRU. This is discussed further herein. [00158] At 705, the WTRU may transmit the transmission using the determined beams and resources.

[00159] A first tuning type may be fine beam-based groupcast. FIG. 8A illustrates an example of a NR V2X WTRU using fine beam-based groupcast. In this example there may be three vehicles/WTRUs (e.g., 801 , 802, 803) each with one or more panels; WRTU 801 may have two panels (e.g., panel 1 and panel 2). In this situation, a specific narrow beam target may be determined. For example, beam 3 of WTRU 801 panel 1 may be used to for transmissions towards WTRU 802. In using a fine beam tuning type, higher latency may be expected since fine-tuned beam(s) may need to be determined and both TX and RX beam sweeping may be needed.

[00160] Fine tuning the beam may be preferred if there are multiple active beam pair links overlapping with the beam pair link between a source-destination pair (e.g., between WTRU 801 and WTRU 802, or between WTRU 801 and WTRU 803). The fine tuning beam sweeping delay may be tolerable (i.e., within operating parameters). Alternatively, proactive beam sweeping may be performed where a WTRU may perform beam sweeping in a periodic manner, in case future data arrives, and the WTRU may immediately transmit. In such a case, a smaller amount of resources may be required since the number of target beams may be smaller; also, this approach may be more efficient in terms of resource allocation.

[00161] In some cases, fine beam-based groupcast may be realized based on QoS requirements. When the transmitter WTRU performs beam sweeping to find specific beams for a group of WTRUs within a group, the specific beams may have different beam widths. For example, if wide beams are swept during beam sweeping, the beam sweeping delay may be smaller such that low latency data may be transmitted as soon as possible. If narrow beams are swept during beam sweeping, the beam sweeping delay may be bigger but higher beamforming gain may be achieved such that longer transmission range or/and higher capacity may be desirable. In some cases (e.g., real-time video groupcast on the high-speed vehicles), when both relative high capacity and low latency may be needed, the PHY layer of the transmitter WTRU may switch/adapt to a reduced groupcast with less group members or broadcast (e.g., the switching/adaptation decision may be made by PHY layer or higher layer).

[00162] Another beam tuning type may be coarse beam-based groupcast. FIG. 8B illustrates an example of a NR V2X WTRU using coarse beam-based groupcast. In this example, there may be three vehicles/WTRUs (e.g., 81 1 , 812, 813) each with one or more panels; WRTU 81 1 may have two panels (e.g., panel 1 and panel 2). Also, in this example, a group of beams may be used for the transmissions towards a specific WTRU; specifically, WTRU 81 1 may determine three beams (e.g., beams 2, 3 and 4) to be used for transmissions to WTRU 812. Generally, the WTRU may use a coarse tuning approach thereby leading to less delay (i.e., reducing latency) and being more efficient in terms of beam direction determinations. Using the course beam approach, a WTRU may detect other potential overlapped beams more quickly such that the WTRU may quickly determine target resource pool/sets which are currently not used. Also, this approach may be preferred if there are a small number of active beams or small amount of resource pools/sets being used.

[00163] Additionally, but not shown, by using a coarse beam tuning type a WTRU may use sensing results of a wider beam. Sensing results may be one or any combination of RSRP, RSSI and resource occupancy, or resource availability information. A wider beam may cover the directions of beams 2, 3 and 4 of FIG. 8B.

[00164] Further, using the course beam approach, the group of beams may be simultaneously transmitted or sequentially transmitted, which may depend on a WTRU antenna capability. For example, if there is only one RF chain for one panel, then only one beam from one panel may be transmitted. In another example, if the group of beams crosses multiple WTRU panels, more than one beam from the identified group may be used.

[00165] In some cases, coarse beam-based groupcast may be realized based on QoS requirements. For example, for high capacity traffic, narrow beam(s) with high beamforming gain may be needed, and data may be repeated multiple times over the narrow beams. On the other hand, for high reliability or/and low latency traffic, wide beam(s) or even omni beam may be preferred.

[00166] FIG. 9 shows two examples of different beam widths, or modes, of coarse beam- based groupcast. Generally, for any manner of beam-based transmission, the number of narrow beams may be larger than the number of wide beam(s) in order to provide the same spatial coverage (e.g., target geographical area) from a transmitter WTRU. As a result, the overall repetition delay for narrow beam transmission may be larger than with wide beam transmission.

[00167] As shown in FIG. 9, there may be an example mode 900 which uses a narrow beam for coarse beam-based groupcast, and an example mode 910 that uses wide beam for coarse beam-based groupcast. In the example of mode 900 there is a transmitter WTRU 901 that uses narrow beams and three receiver WTRUs in the groupcast (902, 903, 904). In the example of mode 910 there is a transmitter WTRU 91 1 that uses wide beams and three receiver WTRUs in the groupcast (912, 913, 914). In either example mode 900 or 910, the number of beams may be determined based on the geographical distribution of the group of WTRUs (e.g., spatial coverage or target geographical area). In comparing the two modes 900 and 910, WTRU 91 1 may repeat data on a small number of wide beams (e.g., 2) for higher reliability and/or lower latency groupcast as compared to the WTRU 901 , which would need to operate a larger number of narrow beams (e.g., 4) to achieve the same spatial coverage (e.g., target geographical area) from the transmitter WTRU for a groupcast.

[00168] It follows from the example of FIG. 9, that when the number of the WTRUs within a group of a groupcast increases, and/or the spatial coverage (i.e., target geographical area) for a transmitter WTRU increases, the repetition delay for narrow beam based transmission may become larger, and also the overhead due to a large number of repetitions may become larger as well. A wider beam width may be used to mitigate the issue. However, beam width may not be arbitrarily increased, and a larger number of repetitions over wide beams may still be needed if spatial coverage keeps increasing.

[00169] A threshold of spatial coverage, or target geographical area, may be used to evaluate the overhead of a groupcast over a group of WTRUs. For example, if the spatial coverage (e.g., calculated by relative location between a group of receiver WTRUs and the transmitter WTRU) is larger than a threshold of degrees (e.g., 60 degrees), groupcast traffic may be transmitted over broadcast at the PHY layer (i.e., where PHY layer may provide lower latency). Alternatively, feedback information may be sent to the higher layer to indicate, for example, the potential risk that QoS requirements (e.g., estimated delay may be larger than the traffic demands) may not be met. In such a case, the higher layer may respond with lower QoS requirements or a smaller number of WTRUs or a list of WTRUs that may be removed from the original list to be transmitted via groupcast at the PHY layer (i.e., the higher layer may involve a larger delay since group size or changing group ID may be carried out, such as in the MAC header, instead of the PHY layer).

[00170] The flexibility of groupcast at the PHY layer (e.g., reduced group size for groupcast, broadcast for groupcast) may be supported by PHY layer only, or a cross-layer coordination. For example, the PHY layer may remove a subset of WTRUs (e.g., a small number of WTRUs constituting a first subgroup located far away from a large number of WTRUs constituting a second subgroup) from the group and perform the groupcast. Alternatively, the information from the PHY layer may be processed and sent to a higher layer (e.g., MAC layer or RRC layer), and the higher layer may be triggered to make a decision (e.g., use broadcast at the PHY layer instead of groupcast at the PHY layer or reduce the size of the groupcast) for the PHY layer. Note that this flexibility may be considered to be an adaptation of groupcast at the PHY layer, and this adaptation (i.e., groupcast to broadcast or reduce the size of groupcast) may be based on the QoS requirements of the transmitted data such as latency and communication range. [00171] In both tuning types of beam-based groupcast at the PHY layer methods (i.e., fine beam-based and coarse beam-based), the overhead may vary with group size and geographical distribution of the receiver WTRUs within a group.

[00172] In one scenario course beam-based groupcast may be used where a V2X WTRU may be configured with a group of resource pools. Each resource pool may be associated with a specific WTRU panel, or shared by multiple WTRU panels. As discussed herein, a panel may be associated with, and referred to, by other terminologies, such as group ID, set ID, or similar terms to differentiate panel specific configurations for beamforming where there are a group or a set of beams. Due to WTRU capability reporting, the network may be aware of a WTRU’s antenna capability (e.g., the number of panels and the number of beams supported by each panel, etc.). The network may also know the directional coverage for each WTRU panel. FIG. 10. shows an example resource pool configuration information element (IE).

[00173] FIG. 11 shows an example of coarse beam directions derived from a WTRU’s location. To determine beam directions, a WTRU 1 101 may be aware of the receiver(s)’s (e.g., WTRU 1 102 or WTRU 1 103) location in advance (e.g., network indicates the GPS location by RRC, MAC-CE or L1 messages). In the example, a coarse beam direction may be derived based on the GPS locations of WTRU 1 101 and WTRU 1 102, the course beam direction shown in with a dash line and being determined by multiple beams (1 , 2, 3, 4). Based on the coarse beam direction, the transmitter WTRU 1 101 may form one or multiple wide RX beams (not shown) from one or multiple WTRU panels, and then perform beam sensing.

[00174] The beam sensing may be performed simultaneously or sequentially (e.g., beam sweeping) based on WTRU capability. To sense over each formed RX beam, the WTRU 1101 may review a list of resource pools and select frequency domain resources by following a specific pattern. This pattern may be determined by a group of adjacent or non-adjacent resource blocks (RBs) within one bandwidth part (BWP) or one component carrier (CC). The list of the resource pools may be determined by network configuration, or determined by WTRU panels (e.g., group ID, set ID), or determined by quasi co-location (QCL) relationship. For example, the list of resource pools may be selected where the resources of one pool is not overlapping with the resources of another pool so that the beam sensing results may cover enough spectral diversity.

[00175] After sensing within a configurable time duration, the WTRU 1101 may be aware of whether there are any other beams overlapping with the swept RX beams. If there are overlapping beams, the WTRU may be aware of which resource pools or resources that are currently being used. [00176] Based on the sensing result from the coarse RX beams, the WTRU 1 101 may just transmit data and/or control messages over the narrow beams within the coarse beam directions. Alternatively, and not shown in FIG. 1 1 , the WTRU may form wide/coarse TX beams by following the directions of the coarse RX beams. The WTRU may select resources by any pre-defined rule or configuration order without considering potential collisions if no resource is detected to be occupied. Otherwise, the WTRU may select resources based on the occupancy status indicated by sensing result.

[00177] FIG. 12 shows an example of a fine tuning approach for beam directions for accurate transmission. Instead of coarse/wide beam directions as shown in FIG. 1 1 , a fine beam- based groupcast may be used, where a V2X WTRU may try to fine tune the TX beams so that the data and/or control messages may not to be repeated in multiple beams. In this example, there may be a transmitter WTRU 1201 , and two receiver WTRUs (1202, 1203). Beam 1 may be selected based on fine tuning. Based on the fine-tuned beam(s), a WTRU may improve the energy efficiency and achieve higher resource efficiency.

[00178] There may be more than one possible way to achieve fine beam-based groupcast. In one case, based on the sensing results from the coarse RX beams, as discussed previously with regard to FIG. 11 , a WTRU 1201 may be able to determine which resource is occupied or not. Therefore, the WTRU 1201 may select undetected resources to perform beam sweeping as shown by the arrows moving over the beams (1 , 2, 3, 4). In another case, the WTRU 1201 may perform a new beam sensing before beam sweeping. The beam sensing may be performed on each beam when beam sweeping is performed for each beam; again, see the arrows of FIG. 12 for the beam sweeping. In other words, each beam may be sensed before transmission. With the sensing result, appropriate resources may be selected such that the selected resource are not occupied.

[00179] FIG. 13 shows an example procedure of beam-based NR V2X; specifically, an example that illustrates beam-based groupcast that supports fine and course beam-based groupcast. This may be similar to FIG. 7, but expands on the beam tuning type determination process.

[00180] For resource pool configuration 1301 , according to WTRU capability reporting or signaling exchanges (e.g., a WTRU may only report minimum capability information in the capability reporting, but send more capability information later by on-demand request from network), the network may be aware of WTRU TX/RX capability associated with one or multiple WTRU panels. Therefore, a WTRU may be configured with one or multiple resource pools, which may include both time domain (e.g., index of symbols in a slot where a WTRU can transmit) and frequency domain (e.g., index of RBs in one BWP or multiple BWPs where a WTRU can transmit) transmission opportunities.

[00181] Each configured pool may be associated with none, one, or multiple panels, which means that the pool may be shared by all WTRU panels, dedicated to one WTRU panel, or shared by multiple WTRU panels. For example, if two panels of a WTRU cover two disjointed directional areas, the two panels may share one or multiple pools. An exemplary pool configuration may be shown in FIG. 10, where a pool is configured with none, one, or multiple panel IDs.

[00182] The transmitting WTRU may determine a WTRU list for groupcast 1302. The higher layer of the transmitter WTRU may be aware of the data transmission mode (e.g., unicast, broadcast, groupcast), and the physical layer of the transmitter WTRU may be informed of the transmission parameters (e.g., group ID for groupcast, WTRU ID for unicast, WTRU ID list for groupcast, QoS requirements for traffic, etc.) by the higher layer.

[00183] The transmitting WTRU may enumerate each WTRU from the WTRU list at 1303 to perform beam tuning type management.

[00184] The beam tuning type management process 1321 may be performed sequentially and independently for each WTRU or jointly simultaneously for multiple WTRUs. For example, the transmitter WTRU may have 3 panels, and potentially each panel may be associated with one or multiple WTRUs from the list. In this way, the transmitter WTRU may perform beam tuning type management for 3 panels simultaneously.

[00185] At one point 1304 a determination may be made if there are serving beams(s) available with the enumerated WTRU(s). If yes, the transmitter WTRU may switch to the serving beam(s) (e.g., sequentially or simultaneously according to WTRU capability) for beam sensing 1309. Based on the sensing results, a selection may be made based on the unoccupied resource pool and a set of resources within a pool 1310, by following certain predefined rules. If no, the transmitter WTRU may obtain the location information (e.g., GPS coordinates, relative direction with the transmitter WTRU, etc.) of the enumerated WTRU(s) (e.g., from network, neighboring WTRUs, etc.), and determine a coarse beam direction 1305, such as by the example FIG. 11.

[00186] Based on preconfigured rules, the transmitter WTRU may decide to perform fine beam-based groupcast or coarse beam-based groupcast with the enumerated WTRU(s) 1306. For example, with stringent latency requirement, the transmitter WTRU may not have enough time to perform beam refinement for fine beam-based groupcast. In another example, based on sensing results from forming one or multiple wider RX beam(s), the transmitter WTRU may realize that too many surrounding beams are transmitting and beam refinement is needed to improve the efficiency of resource allocations (e.g., selected resources transmitted on a few narrow beams instead of more narrow beams or wide beams, etc.).

[00187] If the transmitter WTRU decides to perform coarse beam-based groupcast 1308, it may directly switch to the beams without refinement and start sensing to determine which resource pool/sets are occupied. Then the WTRU may select unoccupied resource pool/set selection based on the sensing results.

[00188] If the transmitter WTRU decides to perform fine beam-based groupcast 1307, it may need to perform beam sweeping with corresponding enumerated WTRU(s) (i.e., receiver WTRU) and fine tune beam direction so that one or few narrow beam(s) may be identified. Then the transmitter WTRU may switch to each refined narrow beam sequentially (if there are multiple refined beams) and start sensing or it may switch to multiple refined narrow beams simultaneously (if there are multiple refined beams) and start sensing 1309, then select unoccupied resource pool/set selection for each narrow beam based on the sensing result 1310. Alternatively, in a course tuning process a WTRU may form one or multiple wide beam(s) within the beam direction and perform less rounds of sensing than narrow beam(s).

[00189] Once a transmitter WTRU decides the best beam(s) and unoccupied resource(s) for all the WTRUs in the group/list for groupcast 131 1 , the WTRU may complete the beam tuning type management and be ready to send data or control messages for groupcast 1312. Other periodical, semi-persistent, or aperiodic evaluation of the currently determined beam(s) and selected resource(s) may be still going on in the background.

[00190] Alternatively, the transmitter WTRU may evaluate transmission parameters (e.g., WTRU ID list, QoS requirements of the traffic, etc.) before performing beam management.

[00191] One such parameters may involve the evaluation of the geographical distribution of the receiver WTRU(s). In one case, based on the WTRU ID list, the physical layer of the transmitter WTRU or higher layer of the transmitter WTRU may derive the relative location (e.g., the distance and direction between a transmitter WTRU and a receiver WTRU) of each WTRU within the group. A spatial coverage, or target geographical area, may be derived based on the relative location of all WTRUs within the group. For example, the spatial coverage, or target geographical area, of the groupcast example in the FIG. 9 is shown the circles with dashed lines. In another case, based on the derived spatial coverage, or target geographical area, the transmitter may determine a group of beams with specific beam directions and beam width. The group of beams may be directly used for groupcast (e.g., coarse beam-based groupcast) or need to be refined by performing further beam management (e.g., fine beam-based groupcast). [00192] Another such parameter may involve the evaluation of QoS parameters. In one case, based on the QoS parameters, a group of beams (e.g., with specific beam directions and beam width) may be determined by the transmitter WTRU. For example, based on the estimated path-loss (e.g., working frequency, geographical distance) between each receiver WTRU and the transmitter WTRU and available power control parameters, the WTRU may derive suitable beamforming gain that is needed to meet required reliability from QoS requirements. The group of beams derived from QoS parameters may be directly used for groupcast (e.g., coarse beam-based groupcast) or need to be refined by performing further beam management (e.g., fine beam-based groupcast).

[00193] Although the solutions described herein consider New Radio (NR), 5G or LTE, LTE-

A specific protocols, it may be understood that the solutions described herein are not restricted to this scenario and may be applicable to other wireless systems as well.

[00194] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer- readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks

(DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.