Method and apparatus for autonomous resource selection in new radio vehicle-to-everything (NR V2X)

Abstract

To provide methods and apparatuses for sidelink communication in a wireless transmit / receive unit (WTRU).SOLUTION: A first WTRU using first and second resource pools performs at least one congestion measurement of the second resource pool. The first resource pool is for use by the first WTRU for transmission of first data. The second resource pool is for use by a second WTRU for transmission of second data associated with a higher priority than the first data. If the at least one congestion measurement of the second resource pool is below a predetermined threshold, the first WTRU transmits the first data using the first resource pool. If the at least one congestion measurement of the second resource pool is above the predetermined threshold, the first WTRU does not transmit the first data using the first resource pool.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for autonomous resource selection in New Radio Vehicle-to-X (NR V2X) communications. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 715,512, filed August 7, 2018, and U.S. Provisional Patent Application No. 62 / 735,981, filed September 25, 2018, the contents of which are incorporated herein by reference.

[0003] In Long Term Evolution Device to Device (LTE D2D) communications, a wireless transmit / receive unit (WTRU) can select radio resources based on transmission priorities pre-assigned or pre-configured to the WTRU. In Long Term Evolution Vehicle to Everything (LTE V2X) communications, a WTRU can transmit data with a limited number of quality of service (QoS) requirements using a single resource pool. Compared with LTE D2D and LTE V2X, New Radio Vehicle to Everything (NR V2X) implements a wider range of QoS, which requires more efficient / dynamic resource selection. For example, the latency requirements for NR V2X are much smaller than those of LTE D2D and LTE V2X. The data rate and reliability requirements are much larger for NR V2X than for LTE D2D and LTE V2X. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, to meet the increasing QoS requirements in NR V2X, methods and apparatus are needed for efficient / dynamic selection of radio resources, especially during periods of high congestion. [Means for solving the problem]

[0005] Described herein are methods and apparatus for sidelink communication in a wireless transmit / receive unit (WTRU) in a New Radio Vehicle-to-Vehicle / Roadside (NR V2X) system. For example, a first WTRU configured with a first resource pool and a second resource pool can perform at least one congestion measurement of the second resource pool to determine transmission of first data on the first resource pool. The first resource pool can be configured for use by the first WTRU for transmission of the first data. The second resource pool can be configured for use by the second WTRU for transmission of the second data. The second data can be associated with a higher priority than the first data. The at least one congestion measurement can include at least one of a channel occupancy, a received signal strength, or a channel busy rate.

[0006] Based on at least one congestion measurement of a second resource pool associated with the second WTRU, the first WTRU may transmit or not transmit the first data on the first resource pool. Specifically, if the at least one congestion measurement of the second resource pool is below a predetermined threshold, the first WTRU may transmit the first data using the first resource pool. If the at least one congestion measurement of the second resource pool is above a predetermined threshold, the first WTRU may postpone transmission of the first data on the first resource pool for a predetermined period of time. If the at least one congestion measurement of the second resource pool is above a predetermined threshold, the first WTRU may preempt a reserved transmission (or a future transmission) of the first data on the first resource pool. If at least one congestion measurement on the second resource pool is above a predetermined threshold, the first WTRU may reduce the amount of resources in the first resource pool and then transmit the first data using the remaining resources in the first resource pool. Effect of the Invention

[0007] A novel method and apparatus for autonomous resource selection in new radio vehicle-to-vehicle / road-to-vehicle communications is provided. A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numbers indicate similar elements and in which: [Brief description of the drawings]

[0008] [Figure 1A] FIG. 1 illustrates an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1A illustrates an exemplary wireless transmit / receive unit (WTRU) that may be used within the communications system of FIG. 1A, according to an embodiment. [Figure 1C]FIG. 1B is a system diagram of an example radio access network (RAN) and core network (CN) that can be used within the communication system of FIG. 1A, according to an embodiment. [Figure 1D] FIG. 1B is a system diagram illustrating a further example RAN and CN that can be used within the communication system of FIG. 1A, according to an embodiment. [Diagram 2] FIG. 2 illustrates an exemplary procedure for resource selection. [Diagram 3] FIG. 1 illustrates an example resource selection based on different center frequencies or bandwidth parts (BWPs). [Figure 4A] FIG. 1 illustrates an example resource selection using a quality of service (QoS) based resource pool. [Figure 4B] FIG. 1 illustrates an example resource selection based on congestion measurements. [Diagram 5] FIG. 1 illustrates an example procedure for resource selection based on congestion measurements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1A is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may utilize 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-tailed Unique Word DFT Spread OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, and Filter Bank Multi-Carrier (FBMC).

[0010] 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104, a CN 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain situations), consumer electronics devices, and devices operating on commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be referred to interchangeably as UEs.

[0011] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0012] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a particular geographic area, which may be relatively constant or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, one for each sector of the cell. In an embodiment, the base station 114a may utilize multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell, e.g., beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0013] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0014] More specifically, as mentioned above, the communication system 100 may be a multiple access system and may utilize one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using Wideband CDMA (WCDMA). WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0015] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE), and / or LTE Advanced (LTE-A), and / or LTE Advanced Pro (LTE-A Pro).

[0016] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) radio access, which may establish the air interface 116 using NR.

[0017] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0018] In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c are IEEE 802.11 (i.e., Wireless Fidelity (WiFi)) , IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), and GSM EDGE (GERAN) may be implemented.

[0019] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as an office, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., used by drones), and a roadway. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 through the CN 106.

[0020] The RAN 104 may communicate with the CN 106, which may be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various Quality of Service (QoS) requirements, such as different throughput requirements, delay requirements, error resilience requirements, reliability requirements, data throughput requirements, and mobility requirements. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, 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 and / or the CN 106 may communicate directly or indirectly with other RANs that utilize the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) that utilizes GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0021] The CN 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communications protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs that may utilize the same RAT as the RAN 104 or a different RAT.

[0022] 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 a base station 114a that may utilize a cellular-based wireless technology and with a base station 114b that may utilize an IEEE 802 wireless technology.

[0023] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any subcombination of the above elements while remaining consistent with an embodiment.

[0024] The processor 118 can be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, which can be coupled to the transmit / receive element 122. Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0025] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0026] 1B, the transmit / receive element 122 is depicted as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may utilize MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0027] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0028] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may obtain information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0029] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components within 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 batteries (e.g., Nickel-Cadmium (NiCd), Nickel-Zinc (NiZn), Nickel Metal Hydride (NiMH), Lithium-Ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0030] The processor 118 may also be coupled to a 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 instead of information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or may determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information using any suitable location determination method while remaining consistent with an embodiment.

[0031] 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 photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, which 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 barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0032] The WTRU 102 may include a full-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and the downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing via a processor (e.g., a separate processor (not shown) or the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or the downlink (e.g., for reception).

[0033] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to an embodiment. As mentioned above, the RAN 104 can communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 can also communicate with the CN 106.

[0034] The RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, the eNodeB 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0035] Each of the eNodeBs 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, etc. As shown in FIG 1C, the eNodeBs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0036] 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. Although each of the above elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity different from the CN operator.

[0037] The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act 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 initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0038] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, as well as managing and storing the context of the WTRUs 102a, 102b, 102c.

[0039] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0040] 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 landline communications devices. For example, the CN 106 may include or 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0041] Although in Figures 1A-1D the WTRU is described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communications interface (e.g., temporarily or permanently) with the communications network.

[0042] In an exemplary embodiment, the other network 112 may be a WLAN.

[0043] 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 access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic within and / or outside the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs in the BSS may be sent through the AP, e.g., a source STA may send traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs in the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent (e.g., directly) between a source STA and a destination STA using a direct link setup (DLS). In one representative embodiment, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all of the STAs) in or using an IBSS may communicate directly with each other. IBSS mode communication is sometimes referred to herein as an "ad-hoc" mode of communication.

[0044] When using 802.11ac infrastructure mode of operation or a similar mode of operation, the AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by STAs to establish a connection with the AP. In one representative embodiment, for example, in an 802.11 system, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected by a particular STA and / or determined to be busy, the particular STA may back off. Within a given BSS, one STA (e.g., only one STA) may transmit at any given time.

[0045] High-throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0046] A Very High Throughput (VHT) STA can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel can be formed by combining consecutive 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels or two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data can pass through a segment parser that can split the data into two streams after channel encoding. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be performed separately for each stream. The streams can be mapped onto two 80 MHz channels and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed and the combined data can be transmitted to a medium access control (MAC).

[0047] Sub-1 GHz mode operation is supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support meter-type control / machine-type communication, such as MTC devices in macro coverage areas. MTC devices can have limited functionality, including, for example, support of (e.g., only) a certain bandwidth and / or limited bandwidth. MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0048] A WLAN system, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, that may support multiple channels and channel bandwidths, includes a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA that supports a minimum bandwidth operating mode among all STAs operating in the BSS. In an 802.11ah example, for a STA (e.g., an MTC type device) that supports (e.g., only supports) the 1 MHz mode, the primary channel may be 1 MHz wide, 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) setting may depend on the status of the primary channel. For example, if the primary channel is busy because a STA (that only supports a 1 MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy, even though most of the available frequency band may remain idle and available.

[0049] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total available bandwidth for 802.11ah is 6MHz to 26MHz, depending on country regulations.

[0050] 1D is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned above, the RAN 104 can communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using NR radio technology. The RAN 104 can also communicate with the CN 106.

[0051] The RAN 113 may include gNBs 180a, 180b, 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may transmit wireless signals to and / or receive wireless signals from the WTRU 102a using multiple antennas, for example. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multipoint (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or gNB 180c).

[0052] The WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can be varied for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting for different lengths of absolute time).

[0053] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing other RANs (e.g., eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect to a gNB 180a, 180b, 180c while also communicating / connecting to another RAN, such as the eNodeBs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0054] Each of the gNBs 180a, 180b, 180c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, and routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c can communicate with each other over the Xn interface.

[0055] The CN 106 shown in Figure 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the above elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity different from the CN operator.

[0056] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, and mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service utilized by the WTRUs 102a, 102b, 102c. Different network slices may be established for different use cases, such as, for example, services relying on ultra-reliable low latency (URLLC) access, services relying on eMBB access, and / or services for machine type communication (MTC) access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0057] The SMFs 183a, 183b can be connected to the AMFs 182a, 182b in the CN 106 via an N11 interface. The SMFs 183a, 183b can also be connected to the UPFs 184a, 184b in the CN 106 via an N4 interface. The SMFs 183a, 183b can select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b can perform other functions such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notification. The PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0058] The UPFs 184a, 184b may connect to one or more of the gNBs 180a, 180b, 180c in the RAN 104 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 UPFs 184a, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homing PDU sessions, handling user plane QoS, buffering downlink packets, as well as providing mobility anchoring.

[0059] The CN 106 may facilitate communication with other networks. For example, the CN 106 may include or 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may connect to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0060] In view of Figures 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices 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.

[0061] The emulation device may be designed to perform one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, the one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. The one or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes, and The one or more emulation devices can perform one or more functions, including all functions, without being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices can be utilized in a test lab and / or in a test scenario in a non-deployed (e.g., test) wired and / or wireless communication network to perform testing of one or more components. The one or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, for example, one or more antennas) can be used by the emulation devices to transmit and / or receive data.

[0062] Vehicle communications, such as Vehicle to Everything (V2X), are modes of communication by which WTRUs can communicate directly with each other. There can be different operation modes for vehicular (V2X) communications. For example, in mode 3, the network can provide the WTRU with a scheduling assignment for V2X sidelink transmissions. In mode 4, the WTRU can autonomously select resources from a configured / preconfigured resource pool. There can be different categories of resource pools. A receive resource pool can be monitored to receive V2X transmissions. In mode 4, the V2X transmit resource pool can be used by the WTRU to select transmit resources. The transmit resource pool cannot be used by a WTRU configured in mode 3.

[0063] The resource pool configuration or resource pool may be communicated to the WTRU semi-statically or dynamically via Radio Resource Control (RRC) signaling or system information broadcasting (e.g., SIB). In Mode 4, the WTRU may use sensing before selecting resources from the RRC configured transmission pool. The pool configuration may be conveyed via system information block (SIB) and / or dedicated RRC signaling.

[0064] As used herein, the term resource pool may refer to one or more sets of radio resources. The terms resource pool, pool, and radio resource pool may be used interchangeably throughout this disclosure. The term resource (or radio resource) may refer to one or more elements selected from the time domain, frequency domain, and / or spatial domain. Examples of resources may include, but are not limited to, resource blocks (RBs), resource elements (REs), frequencies, radio frames, subframes, subchannels, symbols, subcarriers, beam patterns, and antenna configurations.

[0065] New Radio (NR) systems are expected to support numerous use cases, including enhanced Mobile Broadband (eMBB) and ultra-reliable and low latency communications (URLLC). Enhanced V2X (eV2X) communications in NR systems are expected to support new services for both safety and non-safety scenarios (e.g. sensor sharing, autonomous driving, vehicle platooning, remote driving). Different eV2X services require different performance requirements. For some scenarios, a latency of 3 ms may be required.

[0066] A new use case of V2X in NR systems can be vehicle platooning. Vehicle platooning can enable vehicles to dynamically form groups that travel together. Vehicles in the platoon can receive periodic data from the lead vehicle to continue the platoon operation. This information can enable the distance between vehicles to be extremely small (e.g., the gap distance converted to time can be in the sub-second range). Platooning applications can enable trailing vehicles to be driven autonomously.

[0067] Another new use case of V2X in NR systems can be advanced driving. Advanced driving can enable semi-automated or fully automated driving. Longer vehicle distances can be envisaged. Each vehicle and / or Roadside Unit (RSU) can share data acquired from its local sensors with nearby vehicles, thus enabling the vehicles to adjust their trajectory or operation. In addition, each vehicle can share its driving intention with nearby vehicles. The benefits of this group of use cases are safer driving, collision avoidance, and improved traffic efficiency.

[0068] Another new use case of V2X in NR systems can be extended sensors. Extended sensors can enable the exchange of raw or processed data collected through local sensors or live video data between vehicles, RSUs, pedestrian devices, and V2X application servers. Vehicles can have enhanced awareness of the environment and a more holistic view of the local situation beyond what their own sensors can detect.

[0069] Another new use case for V2X in NR systems can be remote driving. Remote driving can enable a remote driver or V2X application to operate remote vehicles for passengers that cannot drive themselves, or remote vehicles located in hazardous environments. For cases with limited variation and predictable routes, such as public transportation, cloud computing-based driving can be used. Additionally, access to cloud-based back-end service platforms can be considered for this group of use cases.

[0070] Resource selection for Mode 4 in V2X may be based on sensing results, congestion measurements, or using any other method. In an example, upon triggering a resource selection or resource reselection procedure, the WTRU may check the sensing results over a time period such as the last second (i.e., the time period represented by subframes [n-1000,n], where n is the moment when resource selection is triggered). The sensing results may include all detected sidelink control information (SCI) transmissions in the last time period.

[0071] The WTRU can determine the available resources during the time period [n+T1,n+T2]. T1 can be determined by the WTRU implementation. T2 can represent a set of selectable resources and can be determined based on the latency requirement of the data to be transmitted. Specifically, T2 can satisfy T2min<T2<100, where T2min can be configured by the network, and T2 is such that it satisfies the latency requirement of the packets received from the upper layer.

[0072] Resource availability can be determined by the per-packet priority for ProSe (PPPP) associated with other WTRU transmissions in the last second. Specifically, the WTRU can be configured using a set of physical sidelink control channel (PSCCH) reference signal received power (RSRP) thresholds for each combination of the transmitted PPPP and the received PPPP. If the sidelink control information (SCI) transmitted by another WTRU reserves resources within the window [n+T1,n+T2] or within any subsequent window depending on the resources within the WTRU's own transmission period, and the measured RSRP of the SCI exceeds the thresholds configured for the transmitted PPPP and the PPPP included in the received SCI, the WTRU can consider such resources to be occupied.

[0073] Before performing resource selection, the WTRU can determine whether the amount of available resources exceeds, for example, 20% of the resources within the selectable time window. If so, the WTRU can perform a random selection among 20% of the resources with the lowest received signal strength indicator (RSSI). If not, the WTRU can repeat the determination of the available resources by reducing each of the network (NW)-configured RSRP thresholds by 3 dB.

[0074] A Mode 4 WTRU can reserve future resources for periodic transmissions by indicating in the SCI indicating the subchannel for the transmission an indication that it will keep / reserve the same resources for the actual period of the transmission as well as for the next period. The WTRU can recognize the intention of the transmitting WTRU to keep the resources for its next reservation period. During resource selection associated with periodic traffic, the WTRU can randomly select a number of periods for which it will keep / reserve the resources. It can then set the resource reservation flag in the SCI for each of its transmissions a number of times equal to this random selection. Furthermore, once the number of consecutive transmissions on the same resource is exhausted, the WTRU can further decide whether to keep or reselect a new resource. Such a decision can also be performed randomly in the WTRU.

[0075] In conventional V2X, PC5 Quality of Service (QoS) is managed by PPPP and ProSe Per Packet Reliability (PPPR) parameters. A WTRU in V2X can receive packets with PPPP and possibly PPPR from higher layers. PPPP is used for prioritization in Logical Channel Prioritization (LCP). The WTRU can prioritize data with lower PPPP when selecting data to be transmitted in a sidelink grant. In addition, PPPP can be implicitly provided to the eNB via a logical channel (LCG) for the eNB to prioritize Mode 3 transmissions between different WTRUs. The WTRU can use PPPR to decide whether to overlap transmissions on two separate carriers. The WTRU can be configured by the network with a PPPR threshold. If a packet with a PPPR below the threshold (i.e., higher reliability requirement) is received, the WTRU can transmit the same packet on two different carriers.

[0076] QoS requirements for NR V2X may be different from that of traditional V2X. The previously defined PPPP / PPPR may not meet the needs of new use cases. There may be more QoS parameters to consider for eV2X services, such as payload (bytes), transmission rate (messages / sec), maximum end-to-end latency (ms), reliability (%), data rate (Mbps), and minimum required communication range (meters).

[0077] Note that the same set of service requirements can apply to both PC5-based and Uu-based V2X communications. NR V2X can have a unified QoS model for PC5 and Uu that uses 5QI for V2X communications over PC5. In this way, the application layer can have a consistent way of indicating QoS requirements regardless of the link used.

[0078] For unicast and multicast type traffic, the same QoS model as that of Uu can be utilized (i.e., each unicast link can be treated as a bearer and can have a QoS flow associated with it). The additional parameters of QoS characteristics and data rates defined in the 5G QoS Indicator (5QI) can be applied. In addition, the minimum required communication range can be treated as an additional parameter specifically for PC5 usage.

[0079] For broadcast traffic, the bearer concept does not exist. In this case, the 5QI can be used in a manner similar to that of PPPP / PPPR (i.e., tagged with each packet). A new set of 5QIs can be defined specifically for NR V2X and called V2X 5QIs (VQIs).

[0080] Resource availability for WTRUs with different timing requirements is described herein. For example, per-packet latency requirements in conventional V2X can be as low as 10 ms for some use cases, while other use cases tolerate 100 ms latency. In NR V2X, the latency requirements can vary between 100 ms and 3 ms. The resource selection mechanism in V2X can rely on determining a resource selection window (i.e., T2) based on the latency requirements of the packets to be transmitted. A subframe (e.g., having a duration of 1 ms) can be selected from this window. This resource selection mechanism can present the following problems: As T2 decreases (e.g., for a time-critical WTRU), the number of resources that the WTRU can select becomes smaller, and the possibility of collisions is increased. A scheme in which a non-time-critical WTRU can select resources at a time that occurs immediately does not promote fairness in resource selection between WTRUs with time-critical transmissions and WTRUs without time-critical transmissions.

[0081] Additionally, over-allocation of resources for random selection, which may not be efficient for large bandwidth applications, is described herein. As described above, resource selection may be based on determining 20% ​​of the available resources and random selection among these resources. Having such a large proportion of the available resources from which to perform random selection may ensure that WTRUs performing resource selection during the same reservation period do not collide.

[0082] For NR V2X, packet sizes and data rates may be significantly larger. The WTRU may need to reserve a larger amount of resources compared to traditional V2X. In addition, reliability requirements (error rate) may be more stringent in NR V2X. Increasing the availability threshold by 3 dB to artificially achieve 20% of the resources are available may not be feasible for NR V2X resource selection.

[0083] NR resource selection may need to take into account new NR RAT features, such as beam-based transmission at higher frequencies, as well as different transmission time interval (TTI) formats (e.g., slot-based and symbol-based).

[0084] Conventional V2X PC5 resource selection is based on the QoS model defined by PPPP (e.g., priority and delay budget). NR V2X resource selection may need to consider new NR QoS requirements such as latency, reliability, congestion, or minimum transmission range. A new resource selection mechanism for Mode 4 PC5 that addresses the above issues may be desirable for NR V2X.

[0085] FIG. 2 illustrates an example resource selection procedure 200 that can be used in combination with any of the other embodiments described herein. In step 210, the WTRU can determine a set of time / frequency / beam resources (i.e., a set of selectable resources) from which resource selection can be made. Such resources can meet the latency requirements of the data to be transmitted. Upon determining the selectable resources, in step 220, the WTRU can determine the number of available resources (e.g., based on criteria including a determination of the use of resources by other WTRUs). The WTRU can determine whether such resources are sufficient to transmit the required data. In step 230, the WTRU can select the actual resources on which to transmit from the set of available resources.

[0086] The resource granularity of a particular time / frequency resource may be statically defined or dynamically defined / determined by the WTRU. The WTRU may determine the granularity (e.g., slot-based or symbol-based) of a particular resource (time / frequency / beam) based on one or more of the following:

[0087] The WTRU may determine the granularity based on a resource pool configuration. For example, the WTRU may receive one or more transmit / receive pool configurations from the network (e.g., a base station), which defines the allowable time / frequency / beam resources for the pool in addition to indicating the resource granularity of each of the resources in the resource pool. A resource pool may be associated with one granularity of resources (e.g., low-granularity or slot-based). A resource pool may be associated with both high-granularity (e.g., symbol) and low-granularity (e.g., slot) resources, and with an indication of which resources belong to each type, and potentially the actual granularity.

[0088] The WTRU may autonomously determine the resource granularity during the determination of selectable resources or during resource selection. Such a decision may be made based on the time criticality of the data it has available for transmission. For example, the WTRU may determine that it can transmit on a particular time / frequency / beam resource (e.g., one slot across multiple resource blocks) using symbol-based transmission on a subset of symbols in that slot. The decision may be based on sensing results, etc.

[0089] The WTRU may determine granularity-based network (NW) signaling. The WTRU may receive NW signaling (e.g., DCI) that indicates / changes the granularity of a particular resource.

[0090] The WTRU may determine resource granularity during the determination of selectable resources. It may then use such determination in the actual resource selection. Alternatively or additionally, the WTRU may perform the determination of selectable resources without determining such resource granularity. During resource selection, it may determine the resource granularity and perform resource selection based on this.

[0091] Resources associated with different service types may have different time granularities. More specifically, one service may be associated with transmissions on resources with symbol-based granularity. In this case, a packet may be transmitted completely on one or more OFDM symbols and one or more resource blocks in frequency. On the other hand, for another service, a packet may be transmitted completely using one or more slots and one or more resource blocks in frequency. In the following description, examples of different resource granularities are used to refer to different service-based resource types. It should be understood that examples describing different resource granularities are not necessarily limited to granularity alone, but may also refer to different resource types (e.g., associated with different services).

[0092] The WTRU may determine a set of resources from which it may select transmission resources based on the service type, criticality, or other QoS related parameters associated with the data to be transmitted. The WTRU may be configured with a first set of resources from which it may select for use with a first service type / criticality / QoS, and it may be configured with a second set of resources from which it may select for use with a second service type / criticality / QoS. The WTRU may limit resources for any of the resource selection activities described herein, i.e., determining selectable resources, monitoring sensing results over a period of time (T) prior to resource selection, determining available resources, and selecting transmission resources. The limitations may apply to resources associated with the service type.

[0093] For example, for time-critical transmissions, the WTRU may select from or use fine-grained resources (e.g., symbol-based resources) as selectable resources, otherwise the WTRU may use low-granularity resources (e.g., slot-based resources) or less granular resources as selectable resources.

[0094] This approach can be applicable when the resource granularity for a particular time / frequency / beam resource is statically defined (e.g., by configuration). For example, a WTRU can be configured with a set of resources that are slot-based and a set of resources that are symbol-based, either of which can select between slot-based or symbol-based as appropriate.

[0095] The WTRU may be configured to determine the amount or percentage of resources of each granularity to select based on one or more of the following criteria: The WTRU may use the QoS characteristics of any pending data to be transmitted, such as time criticality (e.g., priority, maximum delay, reliability, transmission range, etc.) for the decision. For example, the WTRU may select more symbol-based resources as part of the selectable resources when it has time-critical or more time-critical resources.

[0096] The WTRU may use sensing results, such as RSSI, RSRP of the scheduling assignment (SA) or SCI, and measured occupancy, for its decision. For example, the WTRU may select more slot-based resources as part of the selectable resources if the overall measurement of RSSI on the slot-based resources is below / above a threshold, which is below / above the overall measurement of RSSI on the symbol-based resources. The WTRU may determine the percentage or amount of slot-based or symbol-based resources based on the amount of available resources of each type (determined based on the sensing results) in a particular time window.

[0097] The WTRU may perform measurements on channel occupancy on each granularity of resources to make a decision. For example, the WTRU may determine a channel busy ratio (CBR) for resources of different granularity (e.g., slot-based vs. symbol-based) and may select a ratio / amount based on the CBR and possibly other factors.

[0098] The WTRU may use the NW configuration to make the decision, for example, the WTRU may be statically configured with the percentage of resources to use associated with each granularity.

[0099] The WTRU may use the WTRU type and / or the intended recipient to make the decision, which may be based on the destination address or may depend on whether the destination is unicast / multicast / broadcast.

[0100] In one example, the WTRU can use the time criticality of the data to be transmitted to select a window of time / frequency resources [T1, T2] that meets the latency requirement of the data to be transmitted. Within those resources, the WTRU can determine whether it can perform symbol-based transmission based on the latency requirement and / or the selected value of T2. For example, if T2<threshold, the WTRU can use a certain amount (e.g., x%) of the time-frequency resources as symbol-based resources for resource selection. In this case, the set of allowable resources can include both symbol-based (up to x%) and slot-based resources. In another example, the WTRU can determine the amount of available symbol-based resources based on PPPP or other QoS related parameters associated with the data to be transmitted.

[0101] The WTRU may select resources of only one granularity (e.g., only symbol-based) for a given resource selection attempt. Such selection may be based on any or a combination of the following criteria: QoS of the transmitted data that triggered the selection process (e.g., priority, maximum latency required, etc.), WTRU type, intended recipient (e.g., based on destination address or depending on whether the destination is unicast / multicast / broadcast), resource pool type or resource pool configuration (e.g., the WTRU may be configured with a TX pool with a particular granularity and the WTRU may select this pool based on other conditions), and NW configuration.

[0102] A WTRU may be configured with a set of resources that can be used only for slot-based transmissions, only for symbol-based transmissions, or can be used for either slot-based or symbol-based transmissions. A WTRU that is permitted to select slot / symbol-based transmissions can choose between slot / symbol-based resources and "soft" resources (resources that can be used for either slot-based or symbol-based transmissions).

[0103] For example, such a configuration may be present in the transmission pool configuration of the WTRU. The resources may be configured in two separate resource pools (e.g., a first resource pool configuring all slot-based resources and a second resource pool configuring all resources that can be used as symbol-based or slot-based). The resources may be configured in three separate resource pools (e.g., a slot pool, a symbol pool, and a slot / symbol pool). The configuration may be per WTRU (e.g., via a dedicated RRC configuration or pre-configuration) or per cell (e.g., via a SIB). The advantage of this approach is that it avoids excessive resource fragmentation that may occur with a purely WTRU autonomous selection of granularity (e.g., in cases where the WTRU sparsely selects symbol-based transmissions). A WTRU performing symbol / slot based transmission may be further limited in whether it can select from a "flexible" set of resources and how many symbol-based resources it can select based on any of the following: QoS requirements such as priority, reliability, or range for transmission; the amount of data to be transmitted with a given priority; the required beam direction, angle (number of beams) for transmission; whether the selection is for unicast / multicast / broadcast transmission; and the measured CBR on the set of resources.

[0104] Alternatively or additionally, the WTRU may autonomously determine which resources are symbol-based resources and which are slot-based resources. The WTRU may make such a decision based on sensing results obtained from lower layers or resource selection criteria further described herein, such as the determined amount of occupied resources of each type, a CBR measurement associated with each type, etc. The WTRU may also make such a decision based on the time criticality of its transmission.

[0105] A WTRU may determine that a subchannel (e.g., a single RB over a slot) has certain symbols occupied by the transmission of another WTRU. The remaining unoccupied transmissions may be considered as symbol-based resources selectable by the WTRU.

[0106] The WTRU may determine the amount of slot-based and symbol-based transmissions over a time window. The WTRU may determine whether a transmission resource (e.g., determined to be available based on sensing results) is symbol-based or slot-based using a ratio of occupied symbol-based and slot-based resources (e.g., to maintain a certain amount of symbol-based resources in a particular time window).

[0107] The WTRU may further use any of the same criteria defined for selecting a number of symbol-based resources from the set of flexible resources to autonomously determine the granularity.

[0108] A WTRU may determine that a subchannel (e.g., a single RB over a slot) has certain symbols occupied by the transmission of another WTRU. The remaining unoccupied transmissions may be considered as symbol-based resources selectable by the WTRU.

[0109] The WTRU may determine the amount of slot-based and symbol-based transmissions over a time window. The WTRU may determine whether a transmission resource (e.g., determined to be available based on sensing results) is symbol-based or slot-based using a ratio of occupied symbol-based and slot-based resources (e.g., to maintain a certain amount of symbol-based resources in a particular time window).

[0110] The WTRU may further use any of the same criteria defined for selecting a number of symbol-based resources from the set of flexible resources to autonomously determine the granularity.

[0111] The WTRU may determine or derive the time criticality of a transmission using one or more of the following criteria: absolute or relative time (e.g., frame, subframe, slot, etc.) by which the WTRU is requested from higher layers to transmit the packet; QoS related parameters attached to the packet, such as V2X 5QI (VQI), priority (PPPP), reliability (PPPR), expected throughput (e.g., prioritized bit rate); QoS flow or flow identification associated with the transmission, association to a sidelink radio bearer, etc.; application type, such as safety, remote driving, platooning, URLLC, and eMBB; intended recipient (e.g., destination address or identity); intended recipient role (e.g., platoon leader, follower, relay node, etc.); and determined transmission type or characteristics, such as beam-swept transmission, unicast / multicast / broadcast, etc.

[0112] The WTRU may determine either the bandwidth, the central location of the resource, the beam, the start time, or the resource granularity based on the time criticality.

[0113] The WTRU may select resources from a selectable set determined by the latency / time criticality of the data transmitted on those resources. Specifically, the WTRU may be able to select from a greater / lesser amount of resources depending on the time criticality and / or expected transmission / reception time of some or all of the data transmitted on those resources.

[0114] According to the determination of the time criticality of the transmission, the WTRU may apply certain restrictions / rules / criteria to determine the amount of allowable resources from which resource selection is allowed. Specifically, the WTRU may determine any of the following parameters that define the amount of available resources based on the time criticality: The WTRU may determine the bandwidth in terms of the number of resource blocks, carriers, and BWPs that can be used. The WTRU may determine beam-related criteria that define the number of resources, such as the number of beams, beam width / angle, and beam sweeping frequency.

[0115] The WTRU may select resources from a selectable set determined by the latency / time criticality of the data transmitted on those resources. More specifically, the WTRU may be able to select from a greater / lesser amount of resources depending on the time criticality and / or expected transmission / reception time of some or all of the data transmitted on those resources.

[0116] The WTRU may determine a time instant T based on an association of QoS parameters (e.g., latency) from higher layers to a required transmission time. Based on this latency, the WTRU may determine a total number of resources from which it can perform resource selection by calculating the number of resource elements (e.g., slot-based or symbol-based resource blocks) occurring before T in bandwidth B, and set bandwidth B such that the total number of resources is fixed. The total number of resources may be configured by the network or pre-configured (e.g., for out-of-coverage WTRUs). In such an example, the WTRU may further calculate the total number of resources based on current usage characteristics (e.g., channel busy ratio (CBR)) of the resource pool, bandwidth part (BWP), carrier, etc., calculated in the WTRU, QoS related parameters attached to the transmitted data (e.g., priority, reliability, etc.), transmission characteristics (e.g., whether the transmission is unicast or multicast, etc.), and the type of WTRU (e.g., capability).

[0117] The WTRU can select between a number of predefined BWs or BW configurations based on the QoS parameters associated with the data to be transmitted. This can ensure fairness in the resource selection procedure by allowing WTRUs with different timing requirements to select from the same amount of resources (e.g., a WTRU with tight timing requirements is not constrained to select from a smaller amount of resources compared to a WTRU with a larger timing requirement). It can force WTRUs with less time-critical data to select resources that may be further away in time by limiting the amount of resources across frequency resources in the selection process. In conventional V2X, the selectable BWs for all WTRUs can be the same, which can result in an unfair advantage for WTRUs with less critical time requirements to have a larger amount of resources to select from for transmission.

[0118] The WTRU may determine the frequency locations (e.g., center frequencies, reference frequencies, bandwidth parts, etc.) of the selectable resources, possibly using different frequency locations for each transmission or selection process. The WTRU may determine such frequency locations based on one or more of the following criteria: random selection, WTRU measurements (e.g., RSSI, CBR, or sensing results / measurements applied per subband, bandwidth part, pool, etc.), time criticality determination as defined above, and / or other QoS characteristics of the transmission such as priority, WTRU ID (e.g., destination address, or transmitting WTRU address), QoS flow ID, radio bearer ID, or similar identification associated with the data being transmitted, and previous selection of a center frequency by the WTRU (e.g., rules such as avoiding selecting the same center frequency twice in a row).

[0119] The WTRU may first determine the RSSI of the entire set of resources in a resource pool, carrier, BWP, etc. Then, as in the previous solution, the WTRU may select a center frequency or location that minimizes the average RSSI of the selectable resources within bandwidth B.

[0120] The WTRU may determine all possible center frequency locations such that a frequency contiguous set of resources having bandwidth B may be acquired within a resource pool, BWP, carrier, etc. The WTRU may then make a random selection from among one of these possible center frequency locations.

[0121] FIG. 3 illustrates an example resource selection 300 based on different center frequencies or bandwidth parts (BWPs), which can be used in combination with any of the other embodiments described herein. As illustrated in FIG. 3, a WTRU can be configured with a number of possible center BWPs 310, 320, 330 to use for determining selectable resources, and one of the center frequencies can be selected randomly or based on some factor to achieve randomization, such as WTRU ID, flow ID, etc. This approach can maintain equal bandwidth for different criticality transmissions while maximizing overall bandwidth or resource pool utilization. For example, a WTRU with low latency (or latency critical) transmissions can be configured to use multiple center frequencies or BWPs, such as BWP1 310, BWP2 320, and BWP3 330, for resource selection, with the total bandwidth being divided among the three BWPs 310, 320, 330. Other WTRUs with high-latency (or latency non-critical) transmissions may be configured to use only a single center frequency, or a partition of the total bandwidth, for resource selection. When selecting resources for low-latency transmissions, a WTRU with high-latency (or latency non-critical) transmissions may periodically change its BWP, or a partition of the total bandwidth, on which it performs resource selection. For example, at time t1, the WTRU may perform resource selection for BWP1 310. At time 2, the WTRU may perform resource selection for BWP2 320. At time 3, the WTRU may perform resource selection for BWP3 330. In this manner, utilization of the overall bandwidth or resource pool may be maximized.

[0122] The WTRU may determine the start time (e.g., symbol, slot, etc.) of the resource selection window based on the time criticality of the resource. Specifically, the WTRU may determine the earliest selectable resource (in time) based on the time criticality of the transmission. The relationship between the start time and the time criticality may be configured by the network or preconfigured, and may further depend on additional factors such as the size of the transmission, the reliability of the data being transmitted, channel occupancy, channel busy ratio (CBR) or similar channel measurements, the size of the BWP and carrier, the number of beams required, the beam angle or beam sweeping frequency, the type of transmission (e.g., multicast, unicast, broadcast), as well as some randomness factor derived from any of the above quantities. For example, a WTRU with a low-latency (or time-critical) transmission may initiate resource selection immediately after the WTRU receives a packet. However, a WTRU with a high-latency (or time-noncritical) transmission may postpone its resource selection for a period of time when it receives a packet, thereby allowing the WTRU with the low-latency transmission to have more resources to select from.

[0123] In an example, the WTRU may determine a selectable set of resources occurring within a time window between T1 and T2, where T2 corresponds to the latest allowable transmission time of a packet, and T1 may be set to a number of slots prior to T2. The number of slots may further be determined by one or more of the size of the WTRU's transmission, the channel occupancy (e.g., CBR) measured by the WTRU, the pool configuration, and the time criticality of the data.

[0124] The WTRU may determine T1 based on the time criticality of the data and a randomness factor. More specifically, the WTRU may determine T1 to be a random variable between 0 and T2. For time-critical WTRUs, the random variable increases the probability of selecting T1 close to 0. For non-time-critical data, the random variable increases the probability of selecting T1 close to T2.

[0125] This approach can avoid a WTRU selecting resources that are located close in time to the resource selection moment when a transmission is non-critical, thus reserving such resources for other WTRUs that may have more critical transmissions.

[0126] The WTRU may include in the set of selectable resources only resources associated with transmission of a beam or set of beams. The WTRU may be configured with a beam or set of beams on which the WTRU should transmit PDUs. More specifically, such a beam or set of beams may correspond to transmission to a single WTRU (e.g., unicast transmission) or transmission to a set of WTRUs located in a particular direction (e.g., multicast for platooning).

[0127] The WTRU may be configured with a set of resources, which may be part of the selectable resources for a given destination address or destination WTRU ID, etc. The WTRU may determine the destination address for transmission and may include in the set of selectable resources only those resources that correspond to allowed beams for transmission on those resources.

[0128] The WTRU may be configured with a sequence of periodically occurring time resources (e.g., slots, symbols) associated with a particular direction or resource configuration. In addition, the WTRU may be configured by the NW to use a time offset associated with each set of periodically occurring resources or may determine it autonomously (e.g., based on measurement and / or monitoring of a reference signal). The WTRU may also change / adjust the time offset between resource selection moments for the same set of beams. For example, every nth resource (with respect to a reference time or offset) may be associated with a beam. The WTRU may be configured with multiple such directions or resource configurations for transmission. For example, configuration 1 may be (slots 0, n, 2n, 3n, ...). Configuration 2 may be (slots 0, 1, 2, ..., n, n+1, n+2, n+3, ..., 2n+1, 2n+2, 2n+3, ...).

[0129] A resource configuration may include all resources in time (omni-directional transmission). Other configurations may be associated with transmissions only on a subset of beams. The WTRU may be further configured with a mapping of transmissions to one or more resource configurations. Such a mapping may be determined by the WTRU (possibly for each transmission or for a set of transmissions) based on any or a combination of the following criteria:

[0130] The mapping may be determined by a destination address or similar ID that identifies the receiving WTRU, group of WTRUs, or receiving service of the transmission. For example, one destination address may be associated with unicast, and the WTRU may transmit using a configuration that transmits only on one or a subset of the beams. A second destination address may be associated with broadcast, and the WTRU may select a configuration associated with all beams (omnidirectional).

[0131] The mapping may be determined by a pool configuration. For example, the WTRU may select a transmission pool that defines the configuration to be used. Alternatively, a resource configuration may be associated with multiple / all pools.

[0132] The mapping may be determined by QoS related characteristics of the transmission, such as timing (PDB), priority, reliability, or range requirements.

[0133] The mapping may be determined by measurement / reception of a particular signal (eg, a reference signal) or a transmission from another WTRU. The mapping may be determined by an indication from a higher layer.

[0134] The mapping may be determined by the WTRU speed, for example, the WTRU may be configured to transmit on more beams as it increases its speed.

[0135] The mapping may be determined by radio bearer identification and / or QoS flow identification.

[0136] The WTRU may associate a transmission with a destination address to be a unicast transmission and may select its configuration to correspond to a beam that may be used to communicate with that WTRU. The information may be determined / indicated by higher layers (e.g., higher layers may provide configurations associated with destinations and indicate any changes in such association). The information may be provided by the network (e.g., RRC, MAC, or L1 signaling, etc.). The information may be based on the timing of a received transmission from another WTRU (possibly associated with a destination or ID of the first WTRU's transmission). For example, the WTRU may be configured with a mapping between received resource configurations and transmission configurations. The WTRU may determine one or more transmission configurations based on a receive configuration in which the other WTRU's transmission was received / measured (e.g., with a certain quality).

[0137] The WTRU may include in its selectable resource set only those resources (possibly within a time window [t1, t2]) that correspond to the configuration of the destination of the PDU to be transmitted. The configuration associated with the destination may be indicated to the WTRU by higher layers. The WTRU may also receive PDUs to be transmitted to multiple destination addresses. In such a case, the WTRU may include resources in its selectable resource set that consist of the union or intersection of the resource configurations for the different destinations.

[0138] In another example, the WTRU may further determine the configuration based on QoS characteristics, such as reliability, and may select a configuration associated with higher reliability (e.g., associated with a larger number of beams) for a more reliable transmission.

[0139] The WTRU may decide to postpone transmission to a subsequent transmission window or set of selectable resources when the resource selection does not yield acceptable resources. Specifically, the WTRU may determine a first set of selectable resources on which to perform resource selection. If the resource selection yields an acceptable set of resources, the WTRU may perform transmission on these resources. Otherwise, the WTRU may defer to a subsequent set of acceptable resources. The WTRU may further perform new resource selection for the same and / or additional data on the subsequent set of acceptable resources. The WTRU may perform such subsequent resource selection at a later time.

[0140] The WTRU may consider resource selection successful on a set of selectable resources based on any or a combination of the following criteria: the amount of "available" resources in the selectable set is deemed above a threshold, the measured RSRP, RSSI, or CBR, etc. of all or the set of resources is above / below a threshold, the absence of one or more higher priority transmissions is detected within the available set of resources, and the time criticality of its own transmission. Additional criteria for availability, which are also applicable, may be described below.

[0141] The WTRU may change any of the following for each subsequent resource selection attempt for a given transmission: The WTRU may change the criteria for successful resource selection. For example, the WTRU may change a threshold, utilization criterion, or similar parameter for each successive resource selection step in order to make successful resource selection more likely as the set of selectable resources approaches the transmission timing requirements of the packet.

[0142] The WTRU may change the amount of resources in the selectable set by postponing transmission on the selectable set, increasing the BW, considering alternative and / or additional BWPs or carriers, considering additional beams, or changing the beam angle.

[0143] The WTRU may change the nature / granularity of resources. The WTRU may change the granularity of resources with subsequent selection attempts for the same transmission. For example, the WTRU may change from selecting to using slot-based resources to symbol-based resources after it has postponed transmission on a given set of selectable resources.

[0144] The WTRU may determine an initial set of selectable resources as a time window of length L from the arrival of the packet. The WTRU may determine the value of L based on the time criticality of the data to transmit (e.g., L may be a function of a time criticality parameter such that L is less than the required transmission time of the packet). For example, a WTRU with a packet transmission requirement of 500 ms may be configured with multiple consecutive time windows of length 100 ms starting from the arrival of the packet. If resource selection is not successful in the first window, the WTRU may postpone transmission to a subsequent window of length L that begins immediately after the first window or some time later. In one option, the WTRU may perform resource selection on the subsequent window at a later time (e.g., at the start of the subsequent window). In another option, resource selection on the subsequent window may be performed immediately after failing to select resources in the first window. In subsequent windows, the WTRU may increase the (e.g., RSRP, RSSI) threshold for determining whether a particular resource is occupied based on the sensing results collected for that resource, or the WTRU may reduce the allowable number of available resources required for successful selection from the available resources.

[0145] The WTRU may first determine the transmission granularity to be used for transmitting the packet. This approach may be applicable, for example, when the determination of the selectable resources does not distinguish between symbol-based and slot-based resources, or when both slot-based or symbol-based transmissions are allowed on the same set of resources. Once resources are selected from the set of selectable resources, the WTRU may be configured with lower layer mechanisms to transmit data in a symbol-based or slot-based manner. The lower layer mechanisms may allow combinations of consecutive or non-consecutive symbols to be selected by the WTRU from the set of selectable resources. Furthermore, the WTRU may be restricted to selecting only certain combinations of symbol-based resources based on rules, pool configurations, or configuration of a set of symbol combination patterns.

[0146] As described herein, transmission of a packet may include transmission of multiple repetitions of the same packet on different resources for purposes of beam sweeping (e.g., transmitting the same packet on different beams), or repetition (transmission of multiple redundant versions), or both.

[0147] The WTRU may determine the transmission granularity (eg, whether to use slots or symbols) to use for a packet transmission based on one or more of the following criteria:

[0148] The WTRU can determine the transmission granularity to use for transmitting a packet by deriving it from the time criticality parameter. For example, the WTRU can be configured with a mapping of logical channels or LCGs to granularities (symbols or slots) and further configured with a mapping of priorities (e.g., PPPP) to logical channels or LCGs. In another example embodiment, the WTRU can be configured with a mapping of QoS flows and / or sidelink radio bearers to logical channels (or LCGs) and with a mapping of logical channels (LCGs) to granularities. When data arrives from the application layer, the WTRU transmits on the SL resources with the associated granularity. The WTRU can multiplex data with different time criticalities (e.g., different flows or different PPPPs) onto the same transport block, in which case the highest priority / criticality determines the granularity of resources to use.

[0149] The WTRU may be configured with a mapping of required latency (e.g., time to transmit) to resource granularity. The required latency may be the worst-case latency for all or a portion of the PDUs transmitted by the PHY layer.

[0150] The WTRU may determine the allowable resources for transmission based on a fixed configuration (eg, different pools symbol-based vs. slot-based) or autonomously.

[0151] The WTRU may determine the resource granularity for transmission based on the result of the sensing and / or the determination of the availability information. More specifically, the WTRU may use one or a combination of the following decision criteria for determining the transmission granularity of the MAC PDU:

[0152] The WTRU may use the best resource, such as the resource with the lowest or average RSSI. The WTRU may use the total amount of available symbol-based and slot-based resources, or the ratio between them. The WTRU may use a occupancy ratio (CR), which gives the ratio of resources used by the WTRU to the total resources available or selectable in a given window. For example, the WTRU may calculate separate occupancy ratios for symbol-based and slot-based resources and may select the granularity with the lowest ratio, or that does not cause the WTRU to exceed a threshold CR.

[0153] The WTRU may use time criticality, potentially combined with other criteria. The WTRU may use a measurement of total channel occupancy (e.g., CBR). For example, the WTRU may use the CBR in determining the transmission granularity. The WTRU may measure separate CBRs for slot-based and symbol-based resources and maintain separate CBR values.

[0154] The WTRU may use random selection, for example, the WTRU may determine available resources, potentially slot-based and symbol-based, that may be used to transmit a MAC PDU and then apply random selection on a combination of the slot-based and symbol-based resources.

[0155] The resource granularity for transmission may be based on a configured minimum / maximum. For example, the WTRU may be configured with a minimum and / or maximum number of subchannels or resource blocks for slot-based and / or symbol-based transmission. The WTRU may choose to use symbol-based transmission as long as the number of required symbols to transmit a packet does not exceed the configured maximum. The configured maximum / minimum number of slot-based and / or symbol-based resources for transmission may further depend on other parameters, such as CBR, priority (PPPP), reliability (PPPR) or other QoS related parameters.

[0156] The resource granularity for transmission can be based on the message or PDU size.

[0157] A WTRU with a criticality parameter above the threshold (e.g., time-critical data) may transmit data using symbol-based transmission. A WTRU with a criticality parameter below the threshold (e.g., non-time-critical data) may be able to transmit using slot-based or symbol-based transmission. If the CBR of the symbol-based resource is below the threshold and / or the CR for the symbol-based resource is below the threshold and / or the RSSI of the selected symbol-based resource is below the threshold, the WTRU may select the symbol-based resource.

[0158] The WTRU may be configured with a maximum number of symbol-based subchannels (e.g., RBs) and a maximum number of slot-based subchannels. Based on QoS-related parameters associated with the data to be transmitted, the WTRU may be permitted to select a symbol-based resource or a slot-based resource, and the WTRU selects a symbol-based resource as long as it can transmit a PDU for transmission within the maximum number of configured symbol-based subchannels for transmission. The WTRU may further select such a symbol-based resource subject to CBR, and / or CR, and / or reliability requirements. A transmission may be mapped to a preferred granularity by configuration. If the WTRU finds available resources of that granularity within the timing requirements of the packet, it may transmit using that granularity. The conditions or criteria for determining availability are described further herein. Otherwise, the WTRU may transmit resources using a less preferred granularity.

[0159] The WTRU may determine resource availability based on one or a combination of the following: RSSI of the time / frequency / beam resources, a determination of an indication by another WTRU (e.g., through the SCI) that it is using the time / frequency / beam resources, a determination that such an indication has been measured above a threshold, which may be determined based on any of other conditions (e.g., priority of the WTRU's transmissions), priority of the WTRU's own transmissions, priority of the transmissions of other detected WTRUs, range and / or reliability requirements of the WTRU's own transmissions, and range and / or reliability requirements of another WTRU's transmissions.

[0160] From the sensing results, the WTRU may determine resource availability, which varies depending on the granularity of the resource on which it transmits.

[0161] Different sensing results for different granularities (e.g., slot-based results and symbol-based results) may be provided to the WTRU. When performing resource selection, the WTRU may utilize the sensing results associated with the particular granularity with which it will make the transmission. The WTRU may further enable / disable sensing operations (e.g., performed by lower layers) based on a higher layer indication that a particular service has been enabled / disabled, or may / may not generate data to be transmitted for a period of time.

[0162] The sensing results based on the smallest granularity may be provided to the WTRU. The WTRU may determine the availability of fine-grained (e.g., symbol-based) resources based directly on the sensing results. The WTRU may use some rules to determine the availability of slot-based resources based on the sensing results of the symbol-based resources. The WTRU may determine the availability of slot-based resources based on any or a combination of the following criteria in addition to those mentioned above: priority, range, or transmission of the WTRU itself or others, etc.

[0163] The WTRU may determine slot-based resource availability based on the availability or occupancy of any of the symbols in the slot. For example, the WTRU may determine a slot that is occupied / available if there is at least one SCI that has an RSRP above a threshold and that reserves at least one of the symbols in the slot.

[0164] The WTRU may determine slot-based resource availability based on the availability or occupancy of a number of symbols in a slot. The number may be (pre-)configured and / or may be determined based on any other criteria described herein. For example, if a received RSRP of an SCI above a threshold results in the reservation of at least x symbols in the slot, the WTRU may determine that the slot is occupied.

[0165] The WTRU may determine slot-based resource availability based on the location of available or occupied symbols for its own transmission. For example, the WTRU may be requested to transmit in a particular symbol within a slot, or on a particular beam within a time / frequency resource, and the WTRU may determine that the resource is available if at least that particular symbol (or beam) is available.

[0166] Only slot-based sensing results may be provided to the WTRU, and the WTRU may derive symbol-based resource availability based on these sensing results. The WTRU may determine that a symbol-based resource is available only if the availability condition for the entire slot is satisfied. The WTRU may use different thresholds and / or other availability conditions to determine symbol availability compared to slot availability. For example, the WTRU may determine resource availability based on a comparison of the SCI RSRP to a threshold. The WTRU may use threshold 1 when determining whether a resource is available if it intends to transmit on the entire slot, and it may use threshold 2 when determining whether a resource is available if it intends to transmit on a single symbol of the slot.

[0167] A WTRU may consider the transmission range or distance and / or the required reliability for its own and / or other detected WTRU transmissions when determining resource availability. The transmission range (or range) may be a minimum communication range (MCR) that should meet QoS requirements, such as reliability and latency, or other criteria for V2X communications. Examples of range may include, but are not limited to, distance between WTRUs, size of a V2X group, number of WTRUs in a V2X group, V2X group placement, and any other indicator that indicates a small, medium, or large metric for V2X communications between WTRUs or within a group of WTRUs. The transmission range (or range) may be received from other WTRUs or from the network, such as a base station, a V2X control function, a PCF, or a V2X application server, via a sidelink control channel (e.g., SCI). Alternatively, or in addition, it may be preconfigured in the WTRU.

[0168] The WTRU may include range-related (e.g., MCR) or reliability-related parameters in its reservation signal (e.g., SCI). Such parameters may be indicated using one or more of the following: explicitly using the required distance in the SCI or using an index (e.g., from a table) related to the distance, using the required received power or received RSRP, etc., using an index related to such (e.g., referencing a preconfigured table), implicitly indicated as part of the WTRU ID (e.g., a particular WTRU ID or set of WTRU IDs may indicate a range parameter, or part of a WTRU ID), explicitly conveyed as a single QoS value that also indicates other QoS parameters (e.g., PQI, PFI, or an index into a QoS table that maps values ​​to a set of QoS parameters, one of which is a range), implicitly determined from one of the received WTRU decoding parameters (e.g., search space, SCI type, CRC check parameter), and / or implicitly indicated based on a reference signal used to transmit the SCI (e.g., DMRS pattern). The WTRU may derive such range-related parameters for inclusion of the SCI based on information received from higher layers related to the data to be transmitted.

[0169] The WTRU may consider a resource available / occupied if the conditions related to the range / reliability related parameters in the SCI are / are not met. Such a condition may be determined by comparing the received Physical Sidelink Control Channel (PSCCH) / Physical Sidelink Shared Channel (PSSCH) RSRP and / or RSSI with the values ​​related to the range / reliability parameters in the SCI, the WTRU's own transmission reliability requirements, the WTRU's current location with the values ​​related to the range / reliability parameters in the SCI, the location of the WTRU transmitting the SCI that has reserved the resource in question. The location may be estimated by the WTRU determining resource availability. The location may be determined based on the parameters transmitted in the SCI. The location may be indicated by the application layer.

[0170] A WTRU that receives range-related parameters, transmission range, or other WTRU location information from another WTRU may use the range information in addition to sensing results on signals received from the other WTRU to select available resources. For example, a first WTRU may calculate the distance between two WTRUs based on its own location information and the location information of a second WTRU. If the distance (or range) between two WTRUs is below (or within) a required transmission range (e.g., MCR), the first WTRU may not select a resource for transmitting data to the second WTRU due to expected interference. However, if the distance (or range) between two WTRUs is above (or exceeds) the transmission range, the first WTRU may select a resource and transmit data to the second WTRU.

[0171] The WTRU may perform resource selection based on a range parameter (e.g., MCR) of the data it receives from higher layers. The WTRU may select an occupied resource with a larger PSCCH / PSSCH RSRP when the MCR of its data is below a threshold, or may select a non-occupied resource when the MCR is above a threshold.

[0172] The WTRU may determine the PSCCH RSRP of another WTRU's transmission. If the received RSRP is greater than a threshold, the WTRU may consider the announced resource occupied. Such threshold may be derived from the range / reliability related parameters transmitted in the SCI based on a ((pre)configured) table. That is, the WTRU may associate the range / reliability related parameters transmitted in the SCI with the PSCCH threshold based on such a table. The WTRU may further modify / adjust / select such threshold based on other conditions, such as the relative priority between the WTRU's transmissions, the received / transmitted granularity, etc.

[0173] The WTRU may use different resource availability decision criteria depending on the range / reliability value associated with the WTRU's pending transmission. More specifically, for some values ​​of the range / reliability requirement associated with the packet transmission, the WTRU may use a first criterion, while for other values ​​of the range / reliability requirement, the WTRU may use a second criterion. For example, the criteria for reliable transmissions may be stricter than for other transmissions. The criteria include, but are not limited to, excluding resources for which another WTRU's SCI is detected and whose SCI reserves the same resource or a subset of resources (e.g., the same slot or symbols within a slot), excluding resources for which another WTRU's SCI is detected and whose SCI reserves resources adjacent (in time / frequency / beam) to that resource, and using stricter thresholds for the range / reliability values ​​for PSCCH RSRP comparison.

[0174] The WTRU may consider resources where there are no detected SCI transmissions from other WTRUs as available resources for transmissions with certain range / reliability requirements (e.g., PPPR-like parameter > threshold). For other range / reliability requirements (e.g., PPPR-like parameter <= threshold), the WTRU may allow selection of resources where other WTRUs have reserved the resource but the PSCCH-RSRP measured by the selected WTRU is below the threshold. The PPPR-like parameter may be derived by the WTRU based on the VQI.

[0175] The WTRU may exclude some or all of the resources for which there are no detected SCI transmissions from other WTRUs reserving those resources. The WTRU may perform such exclusion only for certain values ​​of range / reliability values ​​associated with pending transmissions (e.g., those associated with low reliability requirements). This may limit the amount of completely free resources used by WTRUs with low reliability requirements, leaving these resources for use by WTRUs with transmissions with high reliability / range requirements. The WTRU may further perform such exclusion as long as the amount of available resources is sufficient for resource selection among those available resources.

[0176] The WTRU may use the existing LTE PSSCH-RSRP threshold mechanism for resource availability determination, but may further increase the threshold by a certain amount for transmissions with certain values ​​of reliability / range.

[0177] As explained above, in conventional V2X, 20% of the resources in the sensing window may need to be available for resource selection. If these are not available, the WTRU may change the thresholds used for resource availability. This approach may not be ideal for NR V2X due to the larger number of WTRUs supported and the more extensive QoS requirements.

[0178] The WTRU can dynamically determine the amount of sufficient resources based on the transmission parameters. The WTRU can determine the amount of available resources (among those available resources) that is sufficient to proceed with resource selection (e.g., as an absolute number of resources or a percentage of the total resources considered) based on one or more of the following factors: QoS parameters of the data to be transmitted, such as the measured CBR, PPPP, PPPR, range parameters, or 5QI of the channel, destination address or destination WTRU ID, transmission type, such as whether the WTRU is using unicast, multicast, or broadcast, beam direction, number of beams, or beam angle, size of the time window for selectable resources (e.g., [T1,T2]), number of available resources, and whether the resources and / or transmissions are on slot-based or symbol-based resources.

[0179] The WTRU may measure a channel busy ratio (CBR) of the channel and may determine a percentage x% based on the measured CBR. Such a determination may be static or based on a preconfigured table of CBR ranges up to an acceptable percentage. The percentage may represent a percentage of resources determined to be available across the set of all resources within the selection window (e.g., across a time interval [T1, T2]). If the percentage of resources determined to be available by the sensing process falls below x%, the WTRU may proceed with resource selection within the acceptable resources; otherwise, the WTRU may perform one of the alternative procedures described herein.

[0180] The WTRU may determine the percentage x% based on a combination of parameters derived from CBR and / or VQI. For a given combination of CBR ranges and / or PPPP-like and / or PPPR-like parameters, the WTRU may determine the value of x%. If the percentage of resources determined to be available by the sensing process falls below x%, the WTRU may proceed with resource selection within the allowable resources; otherwise, the WTRU may perform one of the alternative procedures described herein.

[0181] The value of x% may depend on the beam angle on which the WTRU is transmitting (i.e., whether the WTRU uses a wide or narrow beam). The WTRU may determine one value of x% when it intends to transmit a packet on an N1 beam and may determine a different value of x% when it intends to transmit a packet on an N2 beam.

[0182] The WTRU may perform a fallback procedure when the amount of available resources is insufficient. The procedure may include performing one or more of the following actions: retrying the resource selection procedure (determination of available resources), possibly in conjunction with other actions that may affect the available resources; performing a backoff for a configured, random, or determined time T; changing the transmission mode (e.g., from WTRU autonomous [Mode 4-like] to NW controlled [Mode 3-like]) or requesting the NW to change the transmission mode; changing the transmission resource pool; changing the RAT (e.g., from NR V2X to conventional V2X); improving transmission robustness such as increasing the number of autonomous retransmissions, changing the MCS, changing the beam angle, possibly including an indication in the SCI of a condition of insufficient available resources; completing resource selection followed by a transmission; deleting a pending transmission; changing from slot-based to symbol-based transmission or considering a different granularity of resources for transmission (e.g., considering both slot-based and symbol-based transmissions as opposed to only slot-based transmissions); and changing the BW or BWP of operation.

[0183] The WTRU may further determine which procedure to use based on any of the following: QoS parameters associated with the data to be transmitted, transmission type (unicast, multicast, broadcast), and beam angle (i.e., transmitting on a single beam or multiple beams).

[0184] The WTRU may perform a backoff for a randomly selected time T when the amount of available resources within the considered window is not sufficient. The value of T may further depend on the time requirements of the data. The WTRU may retry the selection after time T. The WTRU may further apply such a backoff only to data with certain QoS requirements, such as certain PPPP or PDB values. The WTRU may possibly for certain values ​​of QoS parameters (e.g., PPPP, PDB).

[0185] The WTRU may autonomously change the BWP of operation (e.g., for certain values ​​of QoS parameters (e.g., PPPP, PDB) from the current BWP to a BWP with a larger bandwidth. The WTRU may then perform the resource selection procedure again on the new BWP.

[0186] The WTRU may repeat the resource selection procedure by considering both symbol-based and slot-based resources in the potential resources for resource selection (e.g., for a certain value of the QoS parameter (e.g., PPPP, PDB)). In that case, the WTRU may consider both symbol-based and slot-based resources to determine the amount of available resources. In that case, the WTRU performs one of the other alternative procedures if the amount of available resources is not sufficient after considering both slot-based and symbol-based resources.

[0187] The WTRU may determine a set of resources from the selectable resources that are available or not being used by other WTRUs. The WTRU may then select resources from the set of available resources based on any or a combination of the following factors and / or criteria:

[0188] The WTRU may select a resource based on a random selection from the remaining available resources, which may potentially be determined by any of the other factors described herein.

[0189] The WTRU may use the sensing results, such as the SCI RSRP and / or PSSCH RSSI of the relevant resources in the sensing window, to select resources to use for transmission. For example, the WTRU may select resources for which no other WTRU has forward-reserved resources. If such resources do not exist in the set of available resources, the WTRU may select resources that may be reserved by another WTRU but have the smallest SCI RSRP.

[0190] The WTRU may be configured to randomly select between available resources, and different resources may be weighted based on time. The WTRU may be configured with different weighting configurations or arrangements (e.g., assignment of weights to resources at times within the window of selectable resources) for different time criticality parameters (e.g., PPPP, packet latency requirements). A WTRU with non-time critical data may more likely select resources that occur later in the window of selectable resources.

[0191] The WTRU may select from only those resources that are applicable to a particular destination, direction, or transmission type (e.g., unicast / multicast / broadcast), etc. Once a subset of such resources is determined, the WTRU may select resources from these using other factors (e.g., random selection, weighting, etc.).

[0192] The WTRU may select resources corresponding to applicable beams for transmission when resource selection is triggered. For example, the WTRU may determine a set of allowable time resources (e.g., corresponding to one or more beams) that can be used for each destination. For example, such a set of resources may be associated with a periodicity configuration configured for a particular destination address, etc., as described further herein. The time offset / reference of such resources may also change over time. The WTRU may maintain sensing results for all time / frequency / beam resources. At resource selection time, the WTRU may select resources from the set of resources associated with the configuration of the particular destination to which it transmits.

[0193] The WTRU may select a different number of resources depending on the reliability requirements of the transmission. For example, the WTRU may select more resources for a transmission with a larger range / reliability criterion. Such resources may be contiguous (e.g., to allow for greater coding for the initial transmission) or non-contiguous (to allow for more repetitions of the same data).

[0194] The WTRU may determine the number of repetitions / retransmissions of a transport block based on a QoS parameter associated with the data (e.g., reliability, PPPR, or 5QI, etc.) The WTRU may select a number of distinct time / frequency resources within a set of available resources (e.g., in time period (T1, T2)) that correspond to the number of repetitions / retransmissions.

[0195] The WTRU may select resources having a particular quality metric depending on the QoS parameters associated with the data to be transmitted. For example, the WTRU may select resources with better quality metrics to facilitate transmission of packets having higher QoS (e.g., higher priority, reliability, range, or similar QoS requirements) and conversely, may select resources with lower quality metrics for packets having lower QoS requirements. The quality metric may be determined by the WTRU using any or a combination of the following criteria:

[0196] The quality metric may be determined by detection of SCI reserved resources. The WTRU may determine resources in which it does not detect an SCI transmitted by another WTRU that reserves resources with high quality.

[0197] The quality metric may be determined by a physical sidelink control channel (PSCCH) RSRP. For example, the WTRU may determine the quality of a reserved / reserved resource for which the physical sidelink shared channel (PSSCH) RSRP is lower than another reserved / reserved resource of higher quality than that resource.

[0198] The quality metric may be determined by the PSSCH RSSI. For example, the WTRU may determine the quality of a resource based on the PSSCH RSSI of related resources that have occurred in the past (e.g., associated with the same beam, fixed periodicity, same time / frequency location, same channel, etc.).

[0199] The quality metric may be determined by the presence of adjacent resources (in time / frequency / beam). The WTRU may determine resources on which other WTRU transmissions are planned that are of lower quality (e.g., in the time, frequency, or beam dimensions). For example, a symbol in a slot where another WTRU has already reserved another symbol may be considered as lower quality.

[0200] The WTRU may be pre-configured with a randomness factor that is used to determine which resource to select among the available resources. The randomness factor may refer to a specific resource to select among the available resources or may be used as part of a hash function or randomization to make the selection among the available resources. The WTRU derives the randomness factor based on one or more of the following criteria: V2X or Process WTRU ID (ProSe WTRU ID) of the WTRU performing the resource selection, destination address of the WTRU ID, QoS parameters of the data to be transmitted such as PPPP, PPPR, or 5QI, PDCP / RRC SN or application layer SN, sequence number of the packet, NW configured value, pre-configured value, and geographic location (e.g., zone, GPS location, etc.). For example, the WTRU may determine the randomness factor from a GPS location or an index / identity of the configured zone or geographic area in which the WTRU is located.

[0201] The selection / hash function can be modulo arithmetic. For example, the resources can be ordered in time / frequency and a selection of the Nth value modulo the number of resources is performed. The WTRU can use a randomness factor as the value of N.

[0202] The selection / hash function can be a configured / determined association of resources to a randomness factor. For example, a WTRU can be configured with a set of resources, BW, one or more subchannels, or bandwidth parts, etc., that are available for a given configured randomness factor.

[0203] Compared to random selection in conventional V2X, this approach can reduce the need to have a large percentage of resources available (i.e., 20%) to avoid selection of the same resources by multiple WTRUs simultaneously performing a resource selection process. The WTRU can be allowed to perform a transmission when it is determined that less than 20% of the resources are available because it does not rely on random selection.

[0204] A WTRU may be configured to transmit in the sidelink on different (e.g., overlapping or non-overlapping) bandwidth parts (BWPs). A bandwidth part for the sidelink may be defined by a set of sidelink subchannels or resource blocks in frequency over a sidelink subframe / slot / symbol. In cases where a WTRU can transmit sidelink data over multiple bandwidth parts, resource selection may be performed.

[0205] The WTRU may first perform resource selection on a first BWP. If the resource selection fails on the first BWP, the WTRU may perform resource selection on a second BWP. The failure of the resource selection may be the result of one or more of the following: inability to find a sufficient number of available resources to satisfy the resource selection, a measured occupancy of the first BWP (e.g., a measurement of the channel busy ratio (CBR), number of SCI transmissions, etc.) exceeding some amount, and inability to satisfy one of the QoS requirements for the data based on the available resources.

[0206] Upon changing to resource selection in the second BWP, the WTRU may continue to perform resource selection in the second BWP for subsequent resource selection operations. The WTRU may return to performing resource selection in the first BWP upon one or more of the following: expiration of a timer, a set of related transmissions requiring a different resource selection operation to be successfully completed, and the WTRU no longer has data associated with a transmission of a certain priority or QoS characteristic to be transmitted.

[0207] The WTRU may decide whether transmission is allowed and / or the amount of resources to transmit on in one BWP / pool based on observed resource utilization in another BWP / pool (or a part thereof). More specifically, the WTRU may measure utilization in another BWP / pool (or a part thereof) to determine how many resources it should select from its own BWP / pool. When the WTRU detects high / low utilization on a different BWP / pool, it may decide to perform one of the following actions: The WTRU may postpone transmission on the initial pool for a period of time. The WTRU may delete / postpone its transmissions planned for the initial pool. The WTRU may change the carrier / pool / BWP. The WTRU may reduce the amount of selected resources (e.g., periodicity, number of RBs, total amount of time / frequency resources, etc.) by a certain amount.

[0208] The WTRU can measure utilization in another BWP / pool (or a portion thereof) based on the mechanisms described herein. The WTRU can determine the use or utilization of a pool or a portion of a BWP. A portion of a pool or BWP may consist of resources that the WTRU itself is not configured to use for a particular transmission. The portion may depend on the unique pool configuration. Only this portion of the pool or BWP may be considered for utilization, not the entire BWP.

[0209] A WTRU may be configured with multiple pools associated with different priorities and / or latency requirements. The priorities and / or latency requirements may be derived from the VQI. The pools may also have some overlapping resources so that a high-priority WTRU may use all of the resources available to a low-priority WTRU, as well as additional resources not available to the WTRU. A WTRU may be required to preempt its own transmission in a low-priority pool if it detects that the CBR of resources associated with a high-priority WTRU (that do not overlap with its own resources) exceeds a threshold.

[0210] FIG. 4A illustrates an example resource selection 400 using a quality of service (QoS) based resource pool that can be used in combination with any of the other embodiments described herein. As illustrated in FIG. 4A, multiple resource pools, such as pool 1 415 and pool 2 420, can be configured in one or more WTRUs based on QoS requirements (e.g., priority). For example, pool 1 415 can be configured with high priority transmissions 407, and pool 2 420 can be configured with low priority transmissions 412 and high priority transmissions 407. One or more WTRUs 405 with high priority data can be configured to use pool 1 415, pool 2 420, or both pool 1 415 and pool 2 420 when transmitting high priority data (i.e., high priority transmissions 407). One or more WTRUs 410 with low priority data can be configured to use only pool 2 420 when transmitting low priority data (i.e., low priority transmissions 412). At some point when there are more high priority transmissions 407 entering the resource pools 415, 420, resulting in the resource pools (i.e., Pool 1 425 and / or Pool 2 430) becoming more congested, one or more WTRUs 410 with low priority data may reduce its transmit power based on sensing results (e.g., RSSI, RSRP, etc.) on its own Pool 2 430, as described above. In this way, one or more WTRUs 405 with high priority data may more efficiently use the congested resource pools 425, 430. As used herein, a high priority transmission may refer to a transmission of data associated with a high priority, and a low priority transmission may refer to a transmission of data associated with a low priority.

[0211] FIG. 4B illustrates an example resource selection 450 based on congestion measurements that can be used in combination with any of the other embodiments described herein. Similar to FIG. 4A, multiple resource pools, such as pool 1 465 and pool 2 470, can be configured in one or more WTRUs based on QoS requirements (e.g., priority). For example, as illustrated in FIG. 4B, pool 1 465 can be configured with high priority transmissions 457, and pool 2 470 can be configured with low priority transmissions 462 and high priority transmissions 457. One or more WTRUs 455 with high priority data can be configured to use pool 1 465, pool 2 470, or both pool 1 465 and pool 2 470 when transmitting high priority data (i.e., high priority transmissions 457). One or more WTRUs 460 with low priority data can be configured to use only pool 2 470 when transmitting low priority data (i.e., low priority transmissions 462). At some point when there are more high priority transmissions 457 entering the resource pools 465, 470, resulting in a resource pool (i.e., Pool 1 475 and / or Pool 2 480) becoming more congested, one or more WTRUs 460 with low priority data may decide whether to stop transmitting low priority data on their own resource pool (i.e., Pool 2 480). The decision to stop transmitting on their own resource pool (i.e., Pool 1 475) may be based on congestion measurements on a resource pool (i.e., Pool 1 475) that is not configured for use by one or more WTRUs 460 with low priority data.

[0212] For example, a WTRU 460 with low priority data configured to use Pool 2 460 may perform at least one congestion measurement on Pool 1 475 that is not configured for use by the WTRU 460 with low priority data. As described above, Pool 1 455 is configured for use by other WTRUs 455 with high priority data and is not configured for use by the WTRU 460 with low priority data. If the congestion measurement on Pool 1 475 exceeds a certain threshold, the WTRU 460 with low priority data may postpone its own transmission on Pool 2 480 for a period of time. The period of time may be provided by the network, e.g., via RRC signaling, or may be preconfigured in the WTRU. During the period of time, the postponed low priority data may accumulate in the WTRU's buffer until it resumes low priority data transmission 462. In another example, if the congestion measurement on Pool 1 475 exceeds a certain threshold, a WTRU 460 with low priority data may preempt its planned (or reserved) future transmissions on Pool 2 480. In another example, if the congestion measurement on Pool 1 475 exceeds a certain threshold, a WTRU 460 with low priority data may reduce the amount of resources that the WTRU 460 with low priority data may select in Pool 2 480. A WTRU 460 with low priority data may transmit the low priority data on the remaining resources in Pool 2 480. If the congestion measurement on pool 1 475 returns below the threshold (or another threshold), the WTRU 460 with low priority data may continue its low priority transmission 462 on its pool 2 480 .

[0213] 4B, a WTRU 460 with a low priority pool may perform congestion measurements on multiple pools configured for high priority transmissions by other WTRUs. The congestion measurements may include, but are not limited to, channel occupancy, received signal strength, channel busy rate, and any other measurements described in this disclosure. A WTRU 455 with high priority data may also increase or decrease its high priority transmission 457 on a resource pool (e.g., pool 2 480) configured for low priority transmission 462 based on measurements, congestion measurements, and / or sensing on the low priority resource pool (e.g., pool 2 480) as described in this disclosure.

[0214] FIG. 5 illustrates an example procedure 500 for resource selection based on congestion measurements, which may be used in combination with any of the other embodiments described herein. In step 510, the WTRU may receive a resource pool configuration from a base station (BS), including information associated with multiple resource pools. The information may indicate the use, allocation, or placement of the multiple resource pools based on QoS requirements (e.g., priority, latency, reliability, and / or data rate). For example, the resource pool configuration may include an indication for a first resource pool and a second resource pool. Assuming that the WTRU has only low priority data to transmit, the first resource pool may be configured for low priority data transmission by the WTRU (and possibly by other WTRUs scheduled / assigned for low priority transmission). The second resource pool may be configured for high priority data transmission by other WTRUs. The resource pool configuration may be received at the WTRU via RRC signaling or system information broadcasting (e.g., SIB). Alternatively or additionally, the resource pool configuration may be pre-configured in the WTRU and / or other WTRUs. The first resource pool or the second resource pool may include one or more sets of radio resources including one or more elements selected from time, frequency, and / or spatial domains.

[0215] At step 520, a WTRU configured to transmit low priority data on a first resource pool may perform congestion measurements of at least one of a second resource pool on which other WTRUs are configured to transmit high priority data. Based on the congestion measurements of the second resource pool, the WTRU may determine whether to transmit its low priority data using the first resource pool. For example, at step 530, the WTRU may determine whether the congestion measurement is below or above a pre-determined threshold. If the congestion measurement of the second resource pool is below the pre-determined threshold, the WTRU may transmit its low priority data using the first resource pool at step 540. If the congestion measurement is above the pre-determined threshold, the WTRU may not transmit its low priority data using the first resource pool at step 550. The pre-determined threshold may be received by the network prior to the congestion measurement or via system information broadcasting (e.g., SIB), or may be pre-configured in the WTRU.

[0216] In one embodiment, if the congestion measurement exceeds a predetermined threshold, the WTRU may postpone transmission of data on the first resource pool for a period of time. The period of time may be configured by the network via RRC signaling or system information broadcasting (e.g., SIB) or may be preconfigured in the WTRU. During the period of time, data to be transmitted on the first resource pool may accumulate in a buffer or queue of the WTRU until the WTRU resumes transmission using the first resource pool. In another embodiment, if the congestion measurement exceeds a predetermined threshold, the WTRU may preempt planned (or reserved) future transmissions of data on the first resource pool. In another embodiment, if the congestion measurement exceeds a predetermined threshold, the WTRU may reduce the amount of resources in the first resource pool and may transmit or not transmit data based on the remaining resources in the first resource pool.

[0217] Examples of congestion measurements may include, but are not limited to, channel occupancy, reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), signal-to-noise ratio (SNR), signal-to-interference plus noise ratio (SINR), signal-to-noise plus distortion ratio (SIDR), channel busy ratio (CBR), and any other measurements described in this disclosure.

[0218] The WTRU can select between different resource selection mechanisms based on QoS / recipient / channel usage. The WTRU can be configured to perform different types of WTRU autonomous resource selection. The WTRU can be further configured to use one type of resource selection mechanism under certain conditions and another type of resource selection mechanism under certain other conditions. The conditions governing the selection of the resource selection mechanism can be determined by one or more of the following criteria: The selection of the resource selection mechanism can be determined by the QoS of the data transmitted on the selected resources. The selection of the resource selection mechanism can be determined by the intended recipients of the data transmitted on the selected resources and / or their relative / absolute locations. The selection of the resource selection mechanism can be determined by the utilization state of the resources from which the selection is made, such as measured CBR or sensing results.

[0219] A WTRU may be configured with several different resource selection mechanisms. The resource selection mechanism may be one or more of the following categories: Fully autonomous resource selection may be when the WTRU uses its own sensing results to determine the set of available resources and transmits on a subset of those resources. Autonomous resource selection based on assistance from other WTRUs may be when the WTRU can use assistance information (e.g., sensing results) from other WTRUs. Scheduling of resources by one WTRU for another WTRU may be when one WTRU schedules resources for other WTRUs in a group. Another resource selection mechanism may be the use of a pre-configured set of resources.

[0220] The following examples do not preclude the use of different resource selection mechanisms that fall into the same category or are not included in any of these categories. The WTRU may select a resource selection mechanism based on channel usage or occupancy. Occupancy may be determined based on one or more of a measured CBR, a detected number of SCIs (or scheduling messages) and / or a measured signal strength of such scheduling messages, a detected number of forward resource reservation signals or messages that may reserve resources for some or an indefinite period of time, a measured RSSI, application layer information or network signaling indicating the use of a particular pool or set of resources, and a number of WTRUs transmitting one-off and / or periodic resources.

[0221] The WTRU may use a resource selection mechanism under high occupancy that reduces the likelihood of collisions, and under low occupancy that does not consider the likelihood of collisions.

[0222] The WTRU may be configured with resource selection based on sensing only (e.g., LTE) and resource selection requiring listen-before-talk (LBT). The WTRU may measure a CBR within a pool of resources for transmission. If the WTRU measures a CBR above a threshold, the WTRU may use LBT-based resource selection. If the WTRU measures a CBR below a threshold, the WTRU may use conventional (e.g., LTE) autonomous resource selection.

[0223] The WTRU may select a resource selection mechanism based on the QoS of the data to be transmitted. More specifically, the WTRU may be aware of the QoS of the data to be transmitted based on one or more of the following: The WTRU may be aware of the QoS of the data to be transmitted based on the logical channels that are multiplexed into the transmitted PDU. The WTRU may be aware of the QoS of the data to be transmitted based on a VQI or similar QoS parameter (e.g., PPPP, PPPR, etc.) associated with the data to be transmitted. This parameter may indicate any of the required transmission reliability, latency, range, priority, or data rate.

[0224] The WTRU may select the transmission mechanism that best suits the QoS parameters associated with the data to be transmitted.

[0225] The WTRU may determine the reliability requirement of the packet based on a VQI associated with a logical channel or bearer. The WTRU may consider a first range of VQIs to be highly reliable and a second range of VQI parameters to be considered low reliability. The WTRU may use resource selection based on pre-configured resources for high reliability transmissions and based on WTRU autonomous and / or WTRU-assisted selection of resources for low reliability.

[0226] The WTRU may determine the resource selection mode using multiple factors (e.g., QoS, channel occupancy, etc.) For example, the WTRU may use LBT transmission for reliable transmission under conditions where the CBR is above a threshold, and may use conventional (e.g., LTE) transmission otherwise.

[0227] As described above, the WTRU in transmission mode 4 can determine the granularity of time / frequency / beam resources based on pre-configuration or autonomously based on sensing results. The WTRU can determine the resource granularity for resource selection depending on the service type. The WTRU can determine the amount / percentage of symbol-based and slot-based resources within the set of selectable resources.

[0228] The WTRU can determine selectable resources (e.g., selectable bandwidth, granularity, beamwidth) over time T based on the time criticality of the transmission. The WTRU can determine the BW (possibly varying center frequency) based on the priority / time criticality. The WTRU can determine the selection window start time (T1) based on the priority / time criticality.

[0229] The WTRU may include resources associated with a subset of beams in the set of selectable resources. The beams may be determined based on higher layer information (e.g., destination addresses, etc.) and QoS information. The WTRU may select resources for a particular beam based on periodic resource configuration. The WTRU may change the offset based on measurements, information received from other WTRUs, or higher layer information.

[0230] The WTRU may use multiple resource selection attempts (over different time windows) or may postpone resource selection to a future window based on time criticality, CBR, or another parameter. The WTRU may change resource selection parameters for each subsequent window of multiple resource selection attempts.

[0231] The WTRU may determine the resource granularity to use for transmission if it is not determined during the selectable resource phase based on the QoS related characteristics of the packet, possibly in combination with sensing results / availability information.

[0232] The WTRU may determine resource availability given possible transmissions with different granularity. The WTRU may use separate sensing results for symbol-based and slot-based transmissions. The WTRU may determine resource availability for slot-based transmissions based on sensing results associated with symbol-based transmissions, and vice versa.

[0233] The WTRU may determine resource availability based on the range / reliability parameters of another WTRU (transmitted on the SCI) and the received RSRP on the SCI.

[0234] The WTRU may make a dynamic determination of the amount of sufficient resources to proceed with resource selection and new fallback procedures in case of failure.

[0235] The selection of a resource (from the set of available resources) may be based on one or more of: weighting of resources over time based on time criticality, number / amount of resources selected based on reliability / range requirements associated with data transmission, quality of resources compared to QoS characteristics, and use of pre-configured selection factors to hash the WTRU to one of the available resources.

[0236] The WTRU may make a temporary transmission / resource selection on a second sidelink BWP when the resource selection on the first BWP fails.

[0237] Although the features and elements have been described above in certain combinations, one skilled in the art will understand 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 can be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over a wired or wireless connection) and computer-readable storage media. Examples of non-transitory computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer. [Industrial Applicability]

[0238] The present invention can be used in communications.

Claims

1. 1. A method for use in a wireless transmit / receive unit (WTRU), comprising: selecting a percentage value threshold from a set of percentage value thresholds configured by the WTRU based on a priority of data corresponding to each percentage value threshold in the set; processing range information of the data to be transmitted; transmitting a sidelink control information (SCI) transmission comprising an index value, the index value being selected from a plurality of indexes, the index value being associated with a physical distance, the index value being based on the range information, the range information being associated with one or more logical channels to be multiplexed into a protocol data unit (PDU) comprising at least a portion of the data to be transmitted associated with the SCI transmission; transmitting the PDU to another WTRU using at least one of the available resources, under a condition that the available resources determined based on one or more Quality of Service (QoS) parameters of the data to be transmitted are equal to or greater than a threshold based on the percentage value threshold selected from the set of percentage value thresholds; A method for providing the above.

2. increasing a reference signal received power (RSRP) threshold for resource selection under a condition where the available resources, as determined based on the one or more QoS parameters of the data to be transmitted, are below the threshold based on the percentage value threshold selected from the set of percentage value thresholds; The method of claim 1 further comprising:

3. determining the available resources for resource selection; and calculating a percentage of the available resources; and The method of claim 1 further comprising:

4. 4. The method of claim 3, wherein the available resources are based on a process per packet priority (PPPP), a process per packet reliability (PPPR), one or more range parameters, or one or more 5G QoS indicators (5QIs).

5. The method of claim 1, further comprising determining a range requirement for transmission of the PDU.

6. The method of claim 5, wherein the index value is based on the determined range requirement.

7. 1. A wireless transmit / receive unit (WTRU), comprising: a processor configured to process range information for data to be transmitted; A transmitter and receiver, The processor and the transceiver selecting a percentage value threshold from a set of percentage value thresholds established by the processor based on a priority of the data corresponding to each percentage value threshold in the set; transmitting a sidelink control information (SCI) transmission comprising an index value, the index value being selected from a plurality of indexes, the index value being associated with a physical distance, the index value being based on the range information, the range information being associated with one or more logical channels to be multiplexed into a protocol data unit (PDU) comprising at least a portion of the data to be transmitted associated with the SCI transmission; transmitting the PDU to another WTRU using at least one of the available resources, under a condition that the available resources determined based on one or more Quality of Service (QoS) parameters of the data to be transmitted are equal to or greater than a threshold based on the percentage value threshold selected from the set of percentage value thresholds; The WTRU is configured to:

8. 8. The WTRU of claim 7, wherein the processor and the transceiver are further configured to increase a reference signal received power (RSRP) threshold for resource selection when the available resources, determined based on the one or more quality of service (QoS) parameters of the data to be transmitted, fall below the threshold based on the percentage value threshold selected from the set of percentage value thresholds.

9. The processor and the transceiver determining the available resources for resource selection; The WTRU of claim 7 , configured to calculate the percentage of the available resources.

10. 10. The WTRU of claim 9, wherein the available resources are based on a process per packet priority (PPPP), a process per packet reliability (PPPR), one or more range parameters, or one or more 5G QoS indicators (5QIs).

11. The WTRU of claim 7, wherein the processor is further configured to determine range requirements for transmission of the PDU.

12. The WTRU of claim 11, wherein the index value is based on the determined range requirement.

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