Method and apparatus for autonomous resource selection in NR v2x

Abstract

Methods and apparatus for autonomous resource selection in NR V2X, in particular methods of wireless transmit / receive units (WTRUs) and sidelink communications thereof, are described herein. For example, a first WTRU configured with first and second resource pools may perform at least one congestion measurement of the second resource pool. The first resource pool may be configured to be used by the first WTRU to transmit the first data. The second resource pool may be configured to be used by a second WTRU to transmit 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 may transmit 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 cannot transmit the first data using the first resource pool.

Description

[0001] This application is a divisional application of a Chinese invention patent application filed on August 6, 2019, with application number 201980053020.6 and invention name “Method and device for autonomous resource selection in new radio vehicle-to-everything (NR V2X)”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 715,512, filed on August 7, 2018, and claims the benefit of U.S. Provisional Application Serial No. 62 / 735,981, filed on September 25, 2018, both of which are incorporated herein by reference in their entireties. Technical Field

[0004] The present application relates to the field of communication technology. Background Art

[0005] In Long Term Evolution Device-to-Device (LTE D2D) communications, a wireless transmit / receive unit (WTRU) may select radio resources based on a transmission priority that is pre-assigned or pre-configured to the WTRU. In Long Term Evolution Vehicle-to-Everything (LTEV2X) communications, the WTRU may use a single resource pool to transmit data with a limited number of quality of service (QoS) requirements. New Radio Vehicle-to-Everything (NR V2X) implementations require a wider range of QoS that requires more efficient / dynamic resource selection compared to LTE D2D and LTE V2X. For example, the latency requirements of NR V2X are much smaller than those of LTE D2D and LTE V2X. The data rate and reliability requirements of NR V2X are much greater than those of LTE D2D and LTE V2X. Therefore, in order to meet the increased QoS requirements in NR V2X, methods and apparatus for efficiently / dynamically selecting radio resources are needed, especially during high congestion. Summary of the invention

[0006] Methods and apparatus for sidelink communication in a wireless transmit / receive unit (WTRU) in new radio vehicle-to-everything (NR V2X) are described herein. For example, a first WTRU configured with a first resource pool and a second resource pool may 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 may be configured to be used by the first WTRU for transmission of the first data. The second resource pool may be configured to be used by the second WTRU for transmission of the second data. The second data may be associated with a higher priority than the first data. The at least one congestion measurement may include at least one of channel occupancy, received signal strength, or channel busy rate.

[0007] Based on the at least one congestion measurement of the 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 at least one congestion measurement of the second resource pool is below a predetermined threshold, the first WTRU may use the first resource pool to transmit the first data. If at least one congestion measurement of the second resource pool is above a predetermined threshold, the first WTRU may postpone the transmission of the first data on the first resource pool for a predetermined time period. If at least one congestion measurement of the second resource pool is above a predetermined threshold, the first WTRU may preempt the reserved transmission (or future transmission) of the first data on the first resource pool. If at least one congestion measurement of 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 use the remaining resources in the first resource pool to transmit the first data. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention may be understood in more detail from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0009] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0010] Figure 1B is a diagram showing that according to an embodiment, Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the communication system is shown;

[0011] Figure 1C is a diagram showing that according to an embodiment, Figure 1A A system diagram of an example radio access network (RAN) and an example core network (CN) used within the illustrated communication system;

[0012] Figure 1D is a diagram showing that according to an embodiment, Figure 1A A system diagram of an additional example RAN and an additional example CN used within the illustrated communication system;

[0013] Figure 2 is a diagram illustrating an example process of resource selection;

[0014] Figure 3 is a diagram illustrating example resource selection based on different center frequencies or bandwidth parts (BWPs);

[0015] Figure 4A is a diagram illustrating example resource selection using a resource pool based on quality of service (QoS);

[0016] Figure 4B is a diagram illustrating example resource selection based on congestion measurement; and

[0017] Figure 5 is a diagram illustrating an example process for resource selection based on congestion measurement. DETAILED DESCRIPTION

[0018] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT-UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0019] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110, and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each WTRU 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or MiFi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0020] 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 / 115, 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 appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0021] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology, and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0022] 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).

[0023] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. 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).

[0024] 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 Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-APro).

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using new radio (NR).

[0026] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to or from multiple types of base stations (e.g., eNBs and gNBs).

[0027] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE802.11 (i.e., Wireless Fidelity (WiFi), IEEE802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM Evolution (GERAN), etc.

[0028] Figure 1AThe base station 114b in the example 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 local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. Figure 1A As shown, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0029] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Data may have varying quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calls, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although in Figure 1A Although not shown, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0030] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0031] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0032] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0033] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0034] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) via an air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0035] Although the transmit / receive element 122 is Figure 1B Although depicted as a single element in the embodiment, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0036] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122, and to demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, for example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0037] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keyboard 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 keyboard 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0038] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium, nickel-zinc, nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0039] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more neighboring base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0040] The processor 118 may also 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 electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 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 magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0041] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., signals associated with particular subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and / or substantially eliminate self-interference via hardware (e.g., choke) or via signal processing by a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., signals associated with particular subframes for UL (e.g., for transmission) or ...

[0042] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0043] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0044] 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, user scheduling in the UL and / or DL, etc. Figure 1C As shown in FIG. , the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0045] Figure 1C The CN 106 shown in FIG. 1 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0046] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0047] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNode-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102B, 102c, managing and storing the context of the WTRUs 102a, 102B, 102c, and the like.

[0048] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0049] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that 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.

[0050] Although the WTRU Figures 1A-1D Although described as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use (eg, temporarily or permanently) a wired communications interface with a communications network.

[0051] In a representative embodiment, other network 112 may be a WLAN.

[0052] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic sent into and / or out of the BSS. Traffic initiated by a STA outside the BSS may be reached by the AP and may be delivered to the STA. Traffic initiated from a STA to a destination outside the BSS may be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within a BSS may be sent by the AP, for example, where a source STA may send traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be sent between a source STA and a destination STA (e.g., directly between a source STA and a destination STA) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

[0053] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP can send beacons on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., a 20MHz wide bandwidth) or a width dynamically set via signaling. The primary channel can be an operating channel of the BSS and can be used by the STA to establish a connection with the AP. In certain representative embodiments, such as in an 802.11 system, carrier sense multiple access with collision avoidance (CSMA / CA) can be implemented. For CSMA / CA, STAs (e.g., each STA) including the AP can sense the main channel. If the main channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0054] A high throughput (HT) STA may communicate using a 40 MHz wide channel, for example, by combining a primary 20 MHz channel with an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel.

[0055] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining adjacent 20MHz channels. 160MHz channel can be formed by combining 8 consecutive 20MHz channels or by combining two non-contiguous 80MHz channels, which can be referred to as 80+80 configuration. For 80+80 configuration, after channel coding, the data can pass through a segment parser, which can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing respectively. The stream can be mapped to two 80MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operation of the above 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0056] The operating mode below 1 GHz is supported by 802.11af and 802.11ah. The channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah relative to the channel operating bandwidth and carrier used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz and 20MHz bandwidths in the TV white space (TVWS) spectrum, while 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz and 16MHz 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 may have certain capabilities, for example, including limited capabilities for support (e.g., only support) for certain and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0057] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include channels that can be designated as primary channels. 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 among all STAs operating in the BSS, which supports the minimum bandwidth operating mode. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports the 1MHz operating mode) transmits to the AP, the entire available band may be considered busy even if most of the band remains idle and available.

[0058] In the United States, the available frequency band that 802.11ah can use is from 902MHz to 928MHz. In South Korea, the available frequency band is from 917.5MHz to 923.5MHz. In Japan, the available frequency band is from 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah is 6MHz to 26MHz.

[0059] Figure 1D1 is a system diagram showing the RAN 113 and the CN 115 according to an embodiment. As described above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0060] RAN113 may include gNBs 180a, 180b, 180c, but it should be understood that RAN113 may include any number of gNBs while remaining consistent with the embodiment. Each of gNBs 180a, 180b, 180c includes one or more transceivers for communicating with WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to send signals to and / or receive signals from gNBs 180a, 180b, 180c. Therefore, gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from WTRU102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit a plurality of component carriers (not shown) to the WTRU 102a. 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 multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and gNB 180b (and / or gNB 180c).

[0061] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter configurations (numerology). For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing different numbers of OFDM symbols and / or continuously varying absolute time lengths).

[0062] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without also accessing other RANs (e.g., the eNode-Bs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNBs 180a, 180b, 180c while also communicating / connecting with another RAN, such as an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may serve 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.

[0063] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing user plane data to a user plane function (UPF) 184a, 184b, routing control plane information to an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0064] Figure 1DThe CN 115 shown in the figure may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DN) 185a, 185b. Although each of the aforementioned elements is depicted as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0065] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, and the like. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of service used by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies (eg, LTE, LTE-A Pro, and / or non-3GPP access technologies such as WiFi).

[0066] SMF 183a, 183b may be connected to AMF 182a, 182b in CN115 via N11 interface. SMF 183a, 183b may also be connected to UPF 184a, 184b in CN115 via N4 interface. SMF 183a, 183b may select and control UPF 184a, 184b, and configure the routing of services through UPF 184a, 184b. SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy implementation and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0067] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0068] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) or may communicate with an IP gateway that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local data network (DN) 185a, 185b through the UPF 184a, 184b via an N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0069] Given that Figures 1A-1D and Figures 1A-1D In accordance with the corresponding description of the present invention, one or more or all of the functions described herein with respect to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU 102a-d, base station 114a-b, eNodeB 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b and / or any (one or more) other devices described herein. The simulation device may be one or more devices configured to simulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0070] The simulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more simulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing purposes, and / or tests can be performed using over-the-air wireless communications.

[0071] One or more simulation devices can perform one or more functions, including all functions, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. The simulation device can use direct RF coupling and / or wireless communication via an RF circuit (e.g., which can include one or more antennas) to transmit and / or receive data.

[0072] Vehicular communication, such as vehicle-to-everything (V2X) is a communication mode whereby WTRUs may communicate directly with each other. There may be different modes of operation in vehicular (V2X) communication. For example, in mode 3, the network may give the WTRU a scheduling allocation for V2X sidelink transmissions. In mode 4, the WTRU may autonomously select resources from a configured / preconfigured resource pool. There may be different categories of resource pools. The receive resource pool may be monitored to receive V2X transmissions. In mode 4, the V2X transmit resource pool may be used by the WTRU to select transmit resources. A WTRU configured in mode 3 may not use the transmit resource pool.

[0073] The resource pool configuration or resource pool may be semi-statically or dynamically signaled to the WTRU via radio resource control (RRC) signaling or system information broadcast (e.g., SIB). In Mode 4, the WTRU may use sensing before selecting a resource from the RRC configured transmitting pool. The pool configuration may be carried via a system information block (SIB) and / or dedicated RRC signaling.

[0074] 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 in this disclosure. The term resource (or radio resource) may refer to one or more elements selected from the time domain, frequency domain, and / or space 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 arrangements.

[0075] New radio (NR) systems are expected to support multiple use cases such as enhanced mobile broadband (eMBB), ultra-high reliability 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, and remote driving). Different eV2X services require different performance requirements. For some scenarios, a latency of 3ms may be required.

[0076] A new use case for V2X in NR systems could be vehicle platooning. Vehicle platooning could enable vehicles to dynamically form groups that travel together. Vehicles in a platoon could receive periodic data from the lead vehicle for platooning operations. This information could allow the distance between vehicles to become extremely small (e.g., the gap distance converted to time could be in the range of seconds). Platoon applications could allow following vehicles to be driven autonomously.

[0077] Another new use case of V2X in NR systems could be advanced driving. Advanced driving can enable semi-autonomous or fully autonomous driving. Longer inter-vehicle distances can be assumed. Each vehicle and / or roadside unit (RSU) can share data obtained from its local sensors with nearby vehicles, allowing vehicles to coordinate their trajectories or maneuvers. In addition, each vehicle can share its driving intentions with nearby vehicles. The benefits of this use case group are safer driving, collision avoidance, and improved traffic efficiency.

[0078] Another new use case of V2X in NR systems may be extended sensors. Extended sensors may enable the exchange of raw or processed data or live video data collected by local sensors between vehicles, RSUs, pedestrian devices, and V2X application servers. Vehicles may enhance their perception of their environment beyond what their own sensors can detect, and have a more comprehensive view of the local situation.

[0079] Another new use case of V2X in NR systems could be remote driving. Remote driving could enable a remote driver or V2X application to operate a remote vehicle for passengers who cannot drive themselves or to operate a remote vehicle located in a hazardous environment. For situations where changes are limited and routes are predictable, such as public transportation, cloud-based driving could be used. In addition, for this use case group, access to a cloud-based backend service platform could be considered.

[0080] Resource selection for Mode 4 in V2X may be based on the use of sensing results, congestion measurements, or any other method. In an example, upon triggering a resource selection or resource reselection procedure, the WTRU may check sensing results over a time period such as the last second (i.e., a time period represented by subframe [n-1000, n], where n is the time instant when resource selection was triggered). The sensing results may include all detected sidelink control information (SCI) transmissions in the last time period.

[0081] The WTRU may determine the available resources in the time period [n+T1, n+T2]. T1 may be determined by the WTRU implementation. T2 may represent a set of optional resources and may be determined based on the delay requirements of the data to be transmitted. Specifically, T2 may satisfy T2 min <T2<100, where T2 min Configurable by the network, T2 is such that it meets the latency requirements of packets received from upper layers.

[0082] Resource availability may be determined by the PPPP of the data to be transmitted relative to the ProSe per-packet priority (PPPP) associated with other WTRU transmissions in the last second. Specifically, the WTRU may be configured with a set of physical sidelink control channel (PSCCH) reference signal received power (RSRP) thresholds for each combination of transmitted PPPP and received PPPP. If the sidelink control information (SCI) transmitted by another WTRU reserves resources in the window [n+T1, n+T2], or in any subsequent window depending on the WTRU's own transmission cycle, and the measured RSRP of this SCI is higher than the threshold configured for the PPPP to be transmitted and the PPPP contained in the received SCI, then the WTRU may consider such resources to be occupied.

[0083] Before performing resource selection, the WTRU may determine whether the amount of available resources is higher than, for example, 20% of the resources in a selectable time window. If so, the WTRU may perform a random selection among the 20% of resources with the lowest received signal strength indicator (RSSI). Otherwise, the WTRU may repeat the determination of available resources again by reducing each of the RSRP thresholds configured by the network (NW) by 3 dB.

[0084] Mode 4 The WTRU may reserve future resources for periodic transmissions by indicating an indication in the SCI indicating the subchannel used for the transmission, which indicates that the WTRU will reserve / reserve the same resources for the next period as well as the actual period of the transmission. The WTRU may be aware of the transmitting WTRU's intent to reserve resources for its next reservation period. During resource selection associated with periodic services, the WTRU may randomly select a number of periods in which the WTRU will reserve / reserve resources. It may then set the resource reservation flag in the SCI with the number of times for each transmission of the SCI being equal to this random selection. In addition, once the number of consecutive transmissions on the same resources has expired, the WTRU may further decide whether to retain or reselect new resources. This decision may also be performed randomly at the WTRU.

[0085] In traditional V2X, PC5 Quality of Service (QoS) is managed by parameters of PPPP and ProSe per-packet reliability (PPPR). A WTRU in V2X may receive packets with PPPP and possible PPPR from upper layers. PPPP is used for prioritization in logical channel prioritization (LCP). When selecting data to be transmitted in a sidelink grant, the WTRU may prioritize data with lower PPPP. In addition, PPPP may be implicitly provided to the eNB via a logical channel (LCG) so that the eNB prioritizes mode 3 transmissions between different WTRUs. The WTRU may use PPPR to determine whether to duplicate a transmission on two separate carriers. The WTRU may be configured with a PPPR threshold by the network. If the received packet has a PPPR below a threshold (i.e., a higher reliability requirement), the WTRU may transmit the same packet on two different carriers.

[0086] The QoS requirements for NR V2X may be different from those for traditional V2X. The previously defined PPPP / PPPR may not meet the needs of new use cases. For eV2X services, more QoS parameters may be considered, such as: payload (bytes); transmission rate (messages / Sec); maximum end-to-end delay (MS); reliability (%); data rate (Mbps); and minimum required communication range (meters).

[0087] It should be noted that the same set of service requirements can be applied to both PC5-based V2X communications and Uu-based V2X communications. NR V2X can have a unified QoS model for PC5 and Uu, which uses 5QI for V2X communications over PC5. In this way, the application layer can have a consistent way to indicate QoS requirements regardless of the link used.

[0088] For both unicast and multicast types of services, the same QoS model as Uu can be utilized (i.e., each unicast link can be considered as a bearer and a QoS flow can be associated). Additional parameters for QoS characteristics and data rates defined in the 5G QoS Indicator (5QI) can be applied. In addition, the minimum required communication range can be considered as a specific additional parameter used by PC5.

[0089] For broadcast services, there is no bearer concept. In this case, 5QI can be used in a similar way to PPPP / PPPR (i.e., marked with each in the packet). A new set of 5QIs can be defined specifically for NR V2X, called V2X 5QI (VQI).

[0090] This document discusses resource availability for WTRUs with different timing requirements. For example, for certain use cases, the delay requirement for each packet in traditional V2X is as low as 10ms. On the other hand, other use cases allow for a delay of 100ms. In NR V2X, the delay requirement may vary between 100ms and 3ms. The resource selection mechanism in V2X may rely on determining a resource selection window (i.e., T2) based on the delay requirement of the packet to be transmitted. A subframe (e.g., having a duration of 1ms) may be selected from this window. Such a resource selection mechanism may have the following problems. As T2 decreases (e.g., for time-critical WTRUs), the number of resources that the WTRU can choose from decreases and the possibility of conflicts increases. The scheme where a non-time-critical WTRU can select a time resource that occurs immediately does not improve the fairness of resource selection between WTRUs with time-critical transmissions and WTRUs without time-critical transmissions.

[0091] Additionally, the present invention discusses over-allocation of resources for random selection, which may not be effective for large bandwidth applications. As described above, resource selection may be based on the determination of 20% of available resources and random selection among these resources. Having such a large ratio of available resources to perform random selection ensures that WTRUs performing resource selection during the same reservation period do not conflict.

[0092] For NR V2X, the packet size and data rate may be much larger. The WTRU may need to reserve a larger amount of resources than for legacy V2X. In addition, the reliability requirements (error rates) may be more stringent in NR V2X. Increasing the availability threshold by 3dB to artificially achieve 20% available resources may not be feasible for NR V2X resource selection.

[0093] NR resource selection may need to take into account new NR RAT characteristics, such as beam-based transmissions with high frequencies and different transmission time interval (TTI) formats (e.g., slot-based and symbol-based).

[0094] Traditional 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, minimum transmission range, etc. A new resource selection mechanism for Mode 4 PC5 that addresses the above issues may be desirable for NR V2X.

[0095] Figure 2 An example resource selection process 200 is shown, which may be used in conjunction with any of the other embodiments described herein. At step 210, the WTRU may determine a set of time / frequency / beam resources from which resource selection may be made (i.e., a set of selectable resources). Such resources may meet the latency requirements of the data to be transmitted. After determining the selectable resources, at step 220, the WTRU may determine the number of available resources (e.g., based on criteria including determining usage of resources by other WTRUs). The WTRU may determine whether these resources are sufficient to transmit the desired data. At step 230, the WTRU may select an actual resource from the set of available resources to transmit on.

[0096] The resource granularity of a particular time / frequency resource may be statically defined by the WTRU or may be dynamically defined / determined by the WTRU. The WTRU may determine the granularity of a particular resource (time / frequency / beam) based on one or more of the following (e.g., slot-based or symbol-based).

[0097] The WTRU may determine the granularity based on the resource pool configuration. For example, the WTRU may receive one or more transmit / receive pool configurations from the network (e.g., a base station) that defines the allowed time / frequency / beam resources for the pool and further indicates the resource granularity for each resource within the resource pool. A resource pool may be associated with a granularity of resources (e.g., low granularity or based on time slots). A resource pool may be associated with resources of both high granularity (e.g., symbol) and low granularity (e.g., time slots) and may indicate each type of resource as well as the potential actual granularity.

[0098] The WTRU may autonomously determine the granularity of resources during determination of selectable resources or during resource selection. This determination may be made based on the time criticality of the data it has available for transmission. For example, the WTRU may decide that it may transmit on a particular time / frequency / beam resource (e.g., one slot over multiple resource blocks) using symbol-based transmission on a subset of symbols within the slot. This determination may be based on sensing results, etc.

[0099] The WTRU may determine network (NW) signaling based on granularity. The WTRU may receive NW signaling (eg, DCI) indicating / changing the granularity of a particular resource.

[0100] The WTRU may determine the resource granularity during the determination of the optional resources. It may then use this determination in the actual resource selection. Alternatively or additionally, the WTRU may perform the determination of the optional resources without determining the granularity of these resources. At the time of resource selection, it may determine the resource granularity and perform resource selection based thereon.

[0101] Resources associated with different service types may have different time granularities. More specifically, a service may be associated with a transmission on a resource with a symbol-based granularity. In this case, a packet may be transmitted completely on one or more OFDM symbols and one or more frequency resource blocks. On the other hand, for another service, one or more time slots and one or more frequency resource blocks may be used completely to transmit a packet. 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 of different resource granularities may also refer to different resource types (e.g., associated with different services) that are not necessarily limited to granularity.

[0102] The WTRU may determine a set of resources from which the WTRU may select transmission resources based on a 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 the WTRU may select for use using a first service type / criticality / QoS, and the WTRU may be configured with a second set of resources from which the WTRU may select for use using a second service type / criticality / QoS. The WTRU may restrict any of the resources in the resource selection activities described herein: determining selectable resources, monitoring sensing results over a time period (T) prior to resource selection, determining available resources, and selecting transmission resources. The restriction may apply to resources associated with a service type.

[0103] For example, for time-critical transmissions, the WTRU may select from high-granularity resources (e.g., symbol-based resources) or use high-granularity resources as optional resources. Otherwise, the WTRU may use low-granularity (e.g., slot-based resources) or fewer high-granularity resources as optional resources.

[0104] This approach may be applicable when the resource granularity of a particular time / frequency / beam resource is statically defined (e.g., by configuration). For example, the WTRU may be configured with a slot-based resource set, and the symbol-based resource set may be selected from slot-based or symbol-based resources accordingly.

[0105] The WTRU may be configured to determine the amount or percentage of resources per granularity to be selected based on one or more of the following criteria: The WTRU may use QoS characteristics (e.g., priority, maximum delay, reliability, transmission range, etc.) of any pending data to be transmitted, such as time criticality, for determination. For example, when the WTRU has time critical or more time critical resources, the WTRU may select more symbol based resources as part of the selectable resources.

[0106] The WTRU may use sensing results, such as RSSI, RSRP of a scheduling assignment (SA) or SCI, and measured occupancy, for making the determination. For example, if the overall measurement of RSSI on slot-based resources is below / above a threshold, if it is below / above the overall measurement of RSSI on symbol-based resources, then the WTRU may select more slot-based resources as part of the selectable 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 in a particular time window (determined based on sensing results).

[0107] The WTRU may measure the channel occupancy at each granularity of the resource to make the determination. For example, the WTRU may determine the channel busy rate (CBR) of resources of different granularities (e.g., slot-based versus symbol-based) and may select a ratio / amount based on the CBR and possibly other factors.

[0108] The WTRU may use the NW configuration to make this determination. For example, the WTRU may be statically configured with a percentage of resources to be used associated with each granularity.

[0109] The WTRU may use the WTRU type and / or the intended recipient to make this determination. This may be based on the destination address, or may depend on whether the destination is unicast / multicast / broadcast.

[0110] In an example, the WTRU may use the time criticality of the data to be transmitted to select a window of time / frequency resources [T1, T2] that meets the delay requirements of the data to be transmitted. Within these resources, the WTRU may determine whether it can perform symbol-based transmission based on the delay requirements and / or the selected value of T2. For example, if T2 < threshold, the WTRU may use a certain amount (e.g., x%) of time-frequency resources as symbol-based resources for resource selection. In this case, the set of allowable resources may include both symbol-based (up to x%) and slot-based resources. In another example, the WTRU may determine the amount of available symbol-based resources based on PPPP or other QoS-related parameters associated with the data to be transmitted.

[0111] The WTRU may select a resource with only one granularity (e.g., based on symbols only) for a given resource selection attempt. This selection may be based on any one or a combination of the following criteria: QoS (e.g., priority, required maximum delay, etc.) of the data to be transmitted that triggered the selection process; WTRU type; intended recipient (e.g., based on the 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 that includes a specific granularity, and the WTRU may select that pool based on other conditions); and NW configuration.

[0112] A WTRU may be configured with a set of resources that may be used for slot-based transmissions only, symbol-based transmissions only, or may be used for either slot-based transmissions or symbol-based transmissions. A WTRU that is allowed to select slot / symbol based transmissions may select from slot / symbol based resources and "flexible" resources (resources that may be used for either slot-based or symbol-based transmissions).

[0113] For example, such a configuration may exist in the transmit pool configuration of the WTRU. Resources may be configured in two separate resource pools (e.g., a first resource pool that configures all slot-based resources and a second resource pool that configures all resources that may be used as symbol-based or slot-based). Resources may be configured in three separate resource pools (e.g., a slot pool, a symbol pool, and an either slot / symbol pool). The configuration may be per WTRU (e.g., via a dedicated RRC configuration or pre-configured) or per cell (e.g., via a SIB). The advantage of this approach is that it avoids excessive resource fragmentation that may occur with purely WTRU autonomous granularity selection (e.g., where the WTRU sparsely selects symbol-based transmissions). A WTRU performing symbol / slot-based transmissions may also be restricted in whether and how many symbol-based resources it may select from a "flexible" set of resources based on any of the following: QoS requirements, such as priority, reliability, or transmission range; the amount of data to be transmitted at a given priority; the required beam direction, angle (number of beams) used for transmission; the selection of whether to use for unicast / multicast / broadcast transmissions; and the CBR measured on the set of resources.

[0114] Alternatively or additionally, the WTRU may autonomously decide which resources are symbol-based resources and which resources are slot-based resources. The WTRU may also make such a decision based on sensing results obtained from lower layers or resource selection criteria further described herein (e.g., the determined amount of occupied resources of each type, CBR measurements associated with each type, etc.). The WTRU may also make such a decision based on the time criticality of its transmissions.

[0115] The WTRU may determine that a subchannel (eg, a single RB on a timeslot) has some symbols occupied by another WTRU's transmission. The remaining unoccupied transmissions may be considered by the WTRU as selectable symbol-based resources.

[0116] The WTRU may determine the amount of slot-based and symbol-based transmissions over a time window. The WTRU may use the ratio of occupied symbol-based resources and slot-based resources to determine whether transmission resources (e.g., available transmission resources determined based on sensing results) are symbol-based or slot-based (e.g., to maintain a certain amount of symbol-based resources in a particular time window).

[0117] The WTRU may also use any of the same criteria for autonomously determining granularity as defined for selecting the number of symbol-based resources from the set of flexible resources.

[0118] The WTRU may determine that a subchannel (eg, a single RB on a timeslot) has some symbols occupied by another WTRU's transmission. The remaining unoccupied transmissions may be considered by the WTRU as selectable symbol-based resources.

[0119] The WTRU may determine the amount of slot-based and symbol-based transmissions over a time window. The WTRU may use the ratio of occupied symbol-based resources and slot-based resources to determine whether transmission resources (e.g., available transmission resources determined based on sensing results) are symbol-based or slot-based (e.g., to maintain a certain amount of symbol-based resources in a particular time window).

[0120] The WTRU may also use any of the same criteria for autonomously determining granularity as defined for selecting the number of symbol-based resources from the set of flexible resources.

[0121] The WTRU may determine or derive the time criticality of a transmission using one or more of the following criteria: the absolute or relative time (e.g., frame, subframe, time slot, etc.) at which the WTRU is required to transmit a packet from a higher layer; QoS-related parameters attached to the packet, such as V2X 5QI (VQI), priority (PPPP), reliability (PPPR), and expected throughput (e.g., prioritized bit rate); the QoS flow or flow identification associated with the transmission; the association with a sidelink radio bearer or similar bearer; the application type, such as safety, remote driving, queuing, URLLC, and eMBB; the intended recipient (e.g., destination address or identity), the intended recipient role (e.g., fleet leader, follower, relay node, etc.); and the determined transmission type or transmission characteristics, such as beam scanning transmission, unicast / multicast / broadcast.

[0122] The WTRU may determine any of the bandwidth, resource center location, beam, start time, or resource granularity based on time criticality.

[0123] The WTRU may select resources from a selectable set determined by the time delay / criticality of the data to be transmitted on the resources. Specifically, the WTRU may be allowed to select from a larger / smaller amount of resources based on time criticality and / or the expected transmission / reception time of some or all data to be transmitted on these resources.

[0124] After determining 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 time criticality. The WTRU may determine the bandwidth based on the number of resource blocks, carriers, and BWPs that can be used. The WTRU may determine beam-related criteria that define the amount of resources, such as the number of beams, beam width / angle, and beam scanning frequency.

[0125] The WTRU may select resources from a selectable set determined by the time delay / criticality of the data to be transmitted on the resources. More specifically, the WTRU may be allowed to select from a larger / smaller amount of resources based on time criticality and / or the expected transmission / reception time of some or all data to be transmitted on these resources.

[0126] The WTRU may determine the time T based on an association of QoS parameters (e.g., latency) from upper layers with the required transmission time. Based on the latency, the WTRU may determine the total number of resources for which resource selection may be performed by calculating the number of resource elements (e.g., slot-based or symbol-based resource blocks) in bandwidth B that occur before T, and setting bandwidth B so that the total number of resources is fixed. The total number of resources may be configured by the network or preconfigured (e.g., for WTRUs outside of coverage). In such an example, the WTRU may also calculate the total number of resources based on: current usage characteristics (e.g., channel busy rate (CBR)) of a resource pool, bandwidth part (BWP), carrier, etc., calculated at the WTRU; QoS-related parameters (e.g., priority, reliability, etc.) attached to the data to be transmitted; transmission characteristics (e.g., whether the transmission is unicast or multicast, etc.); and the type of WTRU (e.g., capabilities).

[0127] The WTRU may select between multiple predefined BWs or BW configurations based on QoS parameters associated with the data to be transmitted. This may ensure fairness in the resource selection process by allowing WTRUs with different timing requirements to select from the same number of resources (e.g., a WTRU with strict timing requirements is not constrained to select from a smaller number of resources than a WTRU with larger timing requirements). It may also force WTRUs with less time-critical data to select resources that may be further away in time by limiting the amount of resources in the total frequency resources during the selection process. In traditional V2X, the selectable BWs for all WTRUs may be the same, which may result in WTRUs with less critical timing requirements having an unfair advantage in having a larger amount of resources to select from for transmission.

[0128] The WTRU may determine the frequency location of the selectable resource (e.g., center frequency, reference frequency, bandwidth portion, etc.), and may use a different frequency location for each transmission or selection process. The WTRU may determine such frequency location 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 portion, 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 the center frequency by the WTRU (e.g., such as rules to avoid selecting the same center frequency twice in a row).

[0129] The WTRU may first determine the RSSI of the entire set of resources in a resource pool, carrier, BWP, etc. The WTRU may then select a center frequency or location such that the average RSSI of the selectable resources in bandwidth B is minimized as per the previous solution.

[0130] The WTRU may determine all possible center frequency locations such that a frequency-contiguous set of resources with bandwidth B is available in a resource pool, BWP, carrier, etc. The WTRU may then randomly select among one of these possible center frequency locations.

[0131] Figure 3 An example resource selection 300 based on different center frequencies or bandwidth parts (BWPs) is shown, which can be used in conjunction with any other embodiment described herein. Figure 3As shown, the WTRU may be configured with multiple possible center BWPs 310, 320, 330 for determining selectable resources, and one of the center frequencies may be randomly selected, or randomization may be performed based on some factors (e.g., WTRU ID, flow ID, etc.). This approach may maintain equal bandwidth for different critical transmissions while maximizing overall bandwidth or resource pool utilization. For example, a WTRU with low latency (or latency critical) transmissions may be configured to use multiple center frequencies or BWPs, such as BWP1 310, BWP2 320, and BWP3 330, for resource selection, where the total bandwidth is divided into 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 portion of the total bandwidth for resource selection. When selecting resources for low latency transmissions, the WTRU with high latency (or latency non-critical) transmissions may periodically change its BWP or the portion of the total bandwidth on which the WTRU performs resource selection. For example, at time t1, the WTRU may perform resource selection for BWP1 310. At time t2, the WTRU may perform resource selection for BWP2 320. At time t3, the WTRU may perform resource selection for BWP3 330. In this way, the overall bandwidth or resource pool utilization may be maximized.

[0132] The WTRU may determine the start time (e.g., symbol, time slot, etc.) of the resource selection window based on the time criticality of the resource. Specifically, the WTRU may determine the earliest (in time) selectable resource based on the time criticality of the transmission. The relationship of the start time and time criticality may be configured by the network or pre-configured, and may also depend on additional factors such as: the size of the transmission; the reliability of the data to be transmitted; the channel occupancy, channel busy rate (CBR), or similar channel measurement; the size of the BWP and carrier; the number of beams, beam angles, or beam scanning frequencies required; the type of transmission (e.g., multicast, unicast, broadcast); and 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 non-critical) transmission may defer its resource selection for a period of time when it receives a packet, thereby allowing the WTRU with a low latency transmission to have more resources to select.

[0133] In an example, the WTRU may determine that the selectable set of resources occurs in a time window between T1 and T2, where T2 corresponds to the latest allowed transmission time for the packet, and T1 may be set to a number of time slots before T2. The number of time slots may be further determined by one or more of: the WTRU's transmission size; the channel occupancy (e.g., CBR) measured by the WTRU; the pool configuration; and the time criticality of the data.

[0134] The WTRU may determine T1 based on the time criticality of the data and a randomness factor. More specifically, the WTRU may determine T1 as a random variable between 0 and T2. For time critical WTRUs, the random variable will increase the probability of selecting T1 close to 0. For non-time critical data, the random variable will increase the probability of selecting T1 close to T2.

[0135] This approach may prevent a WTRU from selecting a resource that is close in time to the resource selection instant when the transmission is not critical, thereby reserving the resource for other WTRUs that may have more critical transmissions.

[0136] The WTRU may include in the selectable resource set only the resources associated with the transmission of a beam or a beam set. The WTRU may be configured with a beam or a beam set on which the WTRU should transmit a PDU. More specifically, such a beam or a beam set may correspond to a transmission to a single WTRU (e.g., unicast transmission) or a set of WTRUs located in a particular direction (e.g., multicast for a queue).

[0137] The WTRU may be configured with a set of resources that may be part of the selectable resources for a given destination address, destination WTRU ID, or the like. The WTRU may determine the destination address for the transmission and may include in the set of selectable resources only those resources that correspond to beams that are allowed to transmit on those resources.

[0138] The WTRU may be configured with a sequence of periodically occurring time resources (e.g., time slots, symbols) associated with a particular direction or resource configuration. In addition, the WTRU may be configured by the NW with or may autonomously determine (e.g., based on measurement and / or monitoring of reference signals) a time offset associated with each periodically occurring set of resources. The WTRU may also change / adjust the time offset between resource selection instances for the same beam set. For example, every Nth resource (relative to a reference time or offset) may be associated with a beam. The WTRU may be configured to have multiple such directions or resource configurations for transmission. For example, configuration 1 may be (time slots 0, n, 2n, 3n, ...). Configuration 2 may be (time slots 0, 1, 2, ..., n+1, n+2, n+3, ..., 2n+1, 2n+2, 2n+3, ...).

[0139] A resource configuration may include all time resources (omni-directional transmission). Other configurations may be associated with transmissions on only a subset of beams. The WTRU may also be configured with a mapping of transmissions to one or more resource configurations. Such mapping may be determined by the WTRU (perhaps for each transmission or for a set of transmissions) based on any one or a combination of the following criteria:

[0140] 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 on only one beam or a subset of beams. A second destination address may be associated with broadcast, and the WTRU may select a configuration that is associated with all beams (omni).

[0141] The mapping may be determined by the pool configuration. For example, the WTRU may select a transmit pool that defines the configuration to use. Alternatively, a resource configuration may be associated with multiple / all pools.

[0142] The mapping may be determined by QoS related characteristics of the transmission, such as timing (PDB), priority, reliability or range requirements.

[0143] The mapping may be determined by measurement / reception of a specific signal (eg, a reference signal) or a transmission from another WTRU. The mapping may be determined by an indication from upper layers.

[0144] The mapping may be determined by the WTRU speed. For example, the WTRU may be configured to transmit on more beams as its speed increases.

[0145] The mapping may be determined by the radio bearer identity and / or the QoS flow identity.

[0146] 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 the WTRU. This information may be determined / indicated by upper layers (e.g., upper layers may provide a configuration associated with a destination and indicate any changes in such association). This information may be provided by the network (e.g., RRC, MAC, L1 signaling, etc.). This information may be based on the timing of a transmission received from another WTRU (which may be associated with the destination or ID of the first WTRU's transmission). For example, the WTRU may be configured with a mapping between received resource configurations and transmit configurations. The WTRU may determine one or more transmission configurations based on the receive configurations in which the transmissions of other WTRUs are received / configured (e.g., with a certain quality).

[0147] The WTRU may include in the optional resource set only those resources that correspond to the configuration of the destination of the PDU to be transmitted (possibly in the time window [t1, t2]). The configuration associated with the destination may be indicated to the WTRU by upper layers. The WTRU may also receive PDUs to be transmitted to multiple destination addresses. In this case, the WTRU may include resources in the optional resource set that consists of the union or intersection of resource configurations for different destinations.

[0148] In another example, the WTRU may also determine the configuration based on QoS characteristics (eg, reliability). The WTRU may select a configuration associated with higher reliability (eg, associated with a larger number of beams) for higher reliability transmission.

[0149] When the resource selection does not generate acceptable resources, the WTRU may decide to postpone the transmission to a subsequent transmission window or set of optional resources. Specifically, the WTRU may determine the first set of optional resources on which to perform resource selection. If the resource selection generates an acceptable set of resources, the WTRU may perform the transmission on these resources. Otherwise, the WTRU may postpone the subsequent set of allowed resources. The WTRU may also perform new resource selection for the same data and / or additional data on the subsequent set of allowed resources. The WTRU may perform such subsequent resource selection at a later time.

[0150] The WTRU may consider resource selection on an optional set of resources to be successful based on any one or a combination of the following criteria: the amount of "available" resources in the optional set is deemed above a threshold; the measured RSRP, RSSI, CBR or similar for all or the set of resources is above / below a threshold; the absence of one or more higher priority transmissions is detected in the available set of resources; and the time criticality of its own transmission. Additional criteria for availability that may also apply may be described below.

[0151] The WTRU may change any of the following in 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 with each successive resource selection step so that a successful resource selection is more likely to be made as the set of selectable resources approaches the transmission timing requirement of the packet.

[0152] The WTRU may change the amount of resources in the alternative set. The WTRU may change the amount of resources in the alternative set by increasing the BW, considering alternative and / or additional BWPs or carriers, considering additional beams, or changing the beam angle after deferring transmission on the alternative set.

[0153] The WTRU may change the nature / granularity of resources. The WTRU may change the granularity of resources for subsequent selection attempts for the same transmission. For example, the WTRU may change from using slot-based selection to symbol-based selection after deferring transmission on a given set of selectable resources.

[0154] The WTRU may determine the initial set of selectable resources as a time window of length L from the arrival of a packet. The WTRU may determine the value of L based on the time criticality of the data to be transmitted (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 500 ms packet transmission requirement may be configured with multiple consecutive time windows of length 100 ms from the arrival of a packet. If resource selection is unsuccessful in a first window, the WTRU may defer transmission to a subsequent window of length L that starts immediately after the first window or at a time after the first window. In one option, the WTRU may perform resource selection for the subsequent window at a later time (e.g., at the beginning of the subsequent window). In another option, resource selection for the subsequent window may be performed immediately after a failure to select a resource in the first window. In the subsequent window, the WTRU may increase a threshold (e.g., RSRP, RSSI) to determine whether the resource is occupied based on the sensing results collected for a particular resource. Alternatively, the WTRU may reduce the allowable number of available resources required for a successful selection from the available resources.

[0155] The WTRU may first determine the transmission granularity to be used for packet transmission. For example, this method is applicable if the determination of the optional resources does not distinguish between symbol-based resources and time slot-based resources, or where both time slot-based transmissions or symbol-based transmissions are allowed on the same set of resources. The WTRU may be configured with a lower layer mechanism so that once resources are selected from the set of optional resources, data is transmitted in a symbol-based manner or in a time slot-based manner. The lower layer mechanism may allow the WTRU to select a combination of consecutive or non-consecutive symbols from the set of optional resources. The WTRU may also be restricted to select only specific combinations of symbol-based resources based on a rule, a pool configuration, or a configuration of a set of symbol combination patterns.

[0156] As described herein, transmission of a packet may include transmitting multiple repetitions of the same packet in different resources for the purposes of beam scanning (eg, transmitting the same packet in different beams) or repetition (transmission of multiple redundant versions), or both.

[0157] The WTRU may determine the transmission granularity (eg, whether to use time slots or symbols) for packet transmission based on one or more of the following criteria.

[0158] The WTRU may determine the transmission granularity used to transmit packets by deriving the transmission granularity from a time criticality parameter. For example, the WTRU may be configured to have a mapping of logical channels or LCGs to granularity (symbols or time slots), and may be further configured to have a mapping of priorities (e.g., PPPP) to logical channels or LCGs. In another example embodiment, the WTRU may be configured to have a mapping of QoS flows and / or sidelink radio bearers to logical channels (or LCGs) and a mapping of logical channels (LCGs) to granularity. When data arrives from the application layer, the WTRU transmits it on the SL resources at the associated granularity. The WTRU may multiplex data with different time criticality (e.g., different streams or different PPPPs) on the same transport block, in which case the highest priority / criticality determines the resource granularity to be used.

[0159] The WTRU may be configured with a mapping of a required delay (eg, transmission time) to a resource granularity. The required delay may be the worst case delay for all or a portion of a PDU to be transmitted by the PHY layer.

[0160] The WTRU may determine the allowed resources for transmission based on a fixed configuration (eg, a symbol-based pool versus a different slot-based pool) or autonomously.

[0161] The WTRU may determine the resource granularity for transmission based on the results of sensing and / or determining the availability information. More specifically, the WTRU may use one or a combination of the following decision criteria to decide the transmission granularity of the MAC PDU.

[0162] The WTRU may use the best resource, such as the resource with the lowest RSSI or average RSSI. The WTRU may use the total amount or ratio between the available symbol-based resources and slot-based resources. The WTRU may use an occupancy ratio (CR) which gives the ratio of the resources used by the WTRU in a given window to the total available or selectable resources. For example, the WTRU may calculate separate occupancy ratios for symbol-based resources and slot-based resources and may select the granularity with the lowest ratio, or the granularity that does not cause the WTRU to exceed a threshold CR.

[0163] The WTRU may use time criticality, potentially in combination with other criteria. The WTRU may use a measurement of total channel occupancy (e.g., CBR). For example, the WTRU may use CBR in the determination of transmission granularity. The WTRU may measure separate CBRs for slot-based resources and symbol-based resources and maintain separate CBR values.

[0164] The WTRU may use random selection. For example, the WTRU may determine the available resources, possibly slot-based and symbol-based available resources, which may be used to transmit the MAC PDU, and then apply random selection to a combination of slot-based and symbol-based resources.

[0165] The granularity of resources used for transmission may be based on a configured minimum / maximum value. For example, the WTRU may be configured to have a minimum and / or maximum number of subchannels or resource blocks for slot-based transmission and / or symbol-based transmission. The WTRU may choose to use symbol-based transmission as long as the number of symbols required to transmit a packet does not exceed the configured maximum value. The configured maximum / minimum number of slot-based and / or symbol-based resources used for transmission may also depend on other parameters, such as CBR, priority (PPPP), reliability (PPPR), or other QoS related parameters.

[0166] The resource granularity used for transmission can be based on message or PDU size.

[0167] A WTRU with a criticality parameter above a threshold (e.g., time-critical data) may transmit data using symbol-based transmission. A WTRU with a criticality parameter below a threshold (e.g., non-time-critical data) may be allowed to transmit using slot-based or symbol-based transmission. A WTRU may select a symbol-based resource if the CBR of the symbol-based resource is below a threshold, and / or the CR of the symbol-based resource is below a threshold, and / or the RSSI of the selected symbol-based resource is below a threshold.

[0168] 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 allowed to select symbol-based resources or slot-based resources and select symbol-based resources as long as the PDU for transmission can be transmitted within the maximum number of configured symbol-based subchannels for transmission. The WTRU may also make such a decision based on CBR and / or CR and / or reliability requirements.

[0169] The transmission may be mapped to a preferred granularity by configuration. If the WTRU finds available resources at that granularity within the timing requirements of the packet, the WTRU may transmit using that granularity. Conditions or criteria for determining availability are further described herein. Otherwise, the WTRU may transmit resources at a less preferred granularity.

[0170] The WTRU may determine the availability of resources based on one or a combination of: the RSSI of the time / frequency / beam resource; a determination by another WTRU (e.g., via an SCI) indicating that it is using the time / frequency / beam resource; a determination that the indication is measured to be above a threshold that may be determined based on any other conditions (e.g., the priority of the WTRU's transmissions); the priority of the WTRU's own transmissions; the priority of transmissions of other detected WTRUs; the range and / or reliability requirements of the WTRU's own transmissions; and the range and / or reliability requirements of another WTRU's transmissions.

[0171] The WTRU may determine the availability of resources differently from the sensing results depending on the granularity of resources on which it will transmit.

[0172] The WTRU may be provided with different sensing results for different granularities (e.g., slot-based results and symbol-based results). When performing resource selection, the WTRU may utilize the sensing results associated with the specific granularity at which it will transmit. The WTRU may also enable / disable sensing operations (e.g., performed by lower layers) based on upper layer indications that a particular service is enabled / disabled or that data may / may not be generated to be transmitted within a particular time period.

[0173] The WTRU may be provided with sensing results based on the smallest granularity. The WTRU may determine the availability of fine-grained (e.g., symbol-based) resources directly based on the sensing results. The WTRU may use certain rules to determine the availability of slot-based resources based on the sensing results for symbol-based resources. The WTRU may determine the availability of slot-based resources based on any criteria other than those previously mentioned or a combination of the following criteria, such as priority, range, or the WTRU's own transmission or other transmissions.

[0174] The WTRU may determine the availability of resources based on a timeslot based on the availability or occupancy of any symbol in the timeslot. For example, if there is at least one SCI with RSRP above a threshold that reserves at least one symbol in the timeslot, the WTRU may determine that the timeslot will be occupied / available.

[0175] The WTRU may determine the availability of resources based on a time slot based on the availability or occupancy of a number of symbols in the time slot. This number may be (pre)configured and / or may be determined based on any other criteria discussed herein. For example, if the RSRP of the received SCI is above a threshold resulting in at least x symbols being reserved in the time slot, the WTRU may determine a time slot to be occupied.

[0176] The WTRU may determine the availability of slot-based resources based on the location of available or occupied symbols relative to the WTRU's own transmissions. For example, the WTRU may be required to transmit on a specific symbol within a slot or on a specific beam within a time / frequency resource and may determine that the resource is available if at least that specific symbol (or beam) is available.

[0177] The WTRU may be provided with only slot-based sensing results and may derive the availability of symbol-based resources based on these sensing results. The WTRU may determine that symbol-based resources are available only when the availability condition for the entire slot is met. The WTRU may determine symbol availability using thresholds and / or other availability conditions that are different from slot availability. For example, the WTRU may determine the availability of resources based on a comparison of the SCI RSRP with a threshold. When determining whether a resource is available, the WTRU may use threshold 1 if the WTRU intends to transmit on the entire slot, and when determining whether a resource is available, the WTRU may use threshold 2 if the WTRU intends to transmit on a single symbol of the slot.

[0178] When determining the availability of resources, the WTRU may consider the transmission range or distance and / or the required reliability of its own and / or other detected WTRU transmissions. The transmission range (or ranges) may be a minimum communication range (MCR) that should meet QoS requirements (e.g., reliability and latency or other criteria for V2X communications). Examples of such ranges may include, but are not limited to, the distance between WTRUs, the size of the V2X group, the number of WTRUs in the V2X group, the V2X group arrangement, and any other indicator indicating a small, medium, or large measure of V2X communications between WTRUs or in a WTRU group. The transmission range (or ranges) may be received from other WTRUs via a sidelink control channel (e.g., SCI), or from the network (e.g., a base station, a V2X control function, a PCF, or a V2X application server). Alternatively or additionally, it may be pre-configured in the WTRU.

[0179] A WTRU may include range-related (e.g., MCR) or reliability-related parameters in its reservation signal (e.g., SCI). Such parameters may be indicated by one or more of: an explicit required distance in the SCI, or an index related to the distance (e.g., from a table); a required received power, received RSRP, or the like; an index related thereto (e.g., by reference to a preconfigured table); implicitly 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 the WTRU ID); explicitly signaled as a single QoS value that also indicates other QoS parameters (e.g., PQI, PFI, or an index to a QoS table that maps the value to a set of QoS parameters, one of which is a range); implicitly determined from one of the receiving WTRU decoding parameters (e.g., search space, SCI type, CRC check parameters); and / or implicitly based on the reference signal (e.g., DMRS pattern) used to transmit the SC. The WTRU may derive such range-related parameters for including the SCI based on information received from upper layers related to the data to be transmitted.

[0180] The WTRU may consider resources to be available / occupied if conditions related to range / reliability related parameters in the SCI are met / not met. Such conditions may be determined by comparing: the received physical sidelink control channel (PSCCH) / physical sidelink shared channel (PSSCH) RSRP and / or RSSI, which has a value related to the range / reliability parameters in the SCI; the WTRU's own transmission reliability requirements; the WTRU's current location, which has a value related to the range / reliability parameters in the SCI; and the location of the WTRU that transmitted the SCI that reserved the resources in question. The location may be estimated by the WTRU determining the resource availability. The location may be determined based on the parameters transmitted in the SCI. The location may be indicated by the application layer.

[0181] A WTRU that receives range-related parameters, transmission ranges, or location information of other WTRUs from other WTRUs may use the range information to select available resources in addition to using the sensing results of the signals received from the other WTRUs. 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 the two WTRUs is lower than (or within) the required transmission range (e.g., MCR), the first WTRU may not select resources to transmit data to the second WTRU due to expected interference. However, if the distance (or range) between the two WTRUs is higher than (or exceeds) the transmission range, the first WTRU may select resources and transmit data to the second WTRU.

[0182] The WTRU may perform resource selection based on a range parameter (e.g., MCR) of the data it receives from upper layers. When the MCR of the WTRU's data is below a threshold, the WTRU may select an occupied resource with a larger PSCCH / PSSCH RSRP, or when the MCR is above a threshold, the WTRU may select an unoccupied resource.

[0183] 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 resources to be occupied. Such thresholds 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 thresholds based on the table. The WTRU may also change / adjust / select these thresholds based on other conditions, such as the relative priority between the WTRU's transmissions, reception / transmission granularity, etc.

[0184] The WTRU may use different resource availability determination criteria depending on the value of range / reliability associated with the WTRU's pending transmission. More specifically, for certain values ​​of range / reliability requirements associated with packet transmissions, the WTRU may use a first criterion, while for other values ​​of range / reliability requirements, the WTRU may use a second criterion. For example, the criteria for high reliability transmissions may be more stringent than the criteria for other transmissions. The criteria may include, but are not limited to: excluding resources where another WTRU's SCI is detected and reserving the same resources or a subset of resources (e.g., the same timeslot, or symbols within a timeslot); excluding resources where another WTRU's SCI is detected and reserving resources that are adjacent (in time / frequency / beam) to the resources; and using a more stringent threshold to compare PSCCH RSRP for certain values ​​of range / reliability.

[0185] The WTRU may consider resources for which no SCI transmissions from other WTRUs are detected 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 for which other WTRUs have reserved resources but for which the PSCCH-RSRP measured by the selecting WTRU is below the threshold. The PPPR-like parameter may be derived by the WTRU based on the VQI.

[0186] The WTRU may exclude some or all resources for which no SCI transmissions from other WTRUs are detected that reserve those resources. The WTRU may perform this exclusion only for certain values ​​of range / reliability values ​​associated with pending transmissions, such as those associated with low reliability requirements. This may limit the amount of completely idle 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 this exclusion as long as the amount of available resources is sufficient for resource selection among those available resources.

[0187] The WTRU may use the existing LTE PSSCH-RSRP threshold mechanism to determine resource availability, but may further increase the threshold by a certain amount for transmissions with a specific value of reliability / range.

[0188] As described 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 threshold used for resource availability. This approach may not be ideal for NR V2X due to the large number of WTRUs to be supported and the wide range of QoS requirements.

[0189] The WTRU may dynamically determine the amount of resources that are sufficient based on transmission parameters. The WTRU may determine the amount of available resources (e.g., as an absolute number of resources under consideration or a percentage of total resources) that are sufficient for resource selection (among those available resources) based on one or more of the following factors: measured channel CBR; QoS parameters of the data to be transmitted, such as PPPP, PPPR, range parameters, 5QI, or the like; destination address or destination WTRU ID; transmission type, such as whether the WTRU uses 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 transmission are slot-based resources or symbol-based resources.

[0190] The WTRU may measure the channel busy rate (CBR) of the channel and may determine a percentage x% based on the measured CBR. This determination may be static or based on a preconfigured table of CBR ranges to allowable percentages. The percentage may represent the percentage of resources determined to be available over the set of all resources in the selection window (e.g., over the time interval [T1, T2]). If the percentage of resources determined to be available by the sensing process is less than x%, the WTRU may proceed with resource selection within the allowed resources, otherwise the WTRU may perform one of the alternative processes discussed herein.

[0191] The WTRU may determine a percentage x% based on a combination of CBR and / or parameters derived from VQI. For a given combination of CBR range, and / or PPPP-like parameters, and / or PPPR-like parameters, the WTRU may determine a value of x%. If the percentage of resources available as determined by the sensing process is less than x%, the WTRU may proceed with resource selection within the allowed resources, otherwise the WTRU may perform one of the alternative procedures discussed herein.

[0192] The value of x% may depend on the beam angle at which the WTRU is transmitting (i.e., whether the WTRU is using a wide beam or a narrow beam). The WTRU may determine one value of x% when it intends to transmit a packet on the N1 beam and may determine a different value of x% when it intends to transmit a packet on the N2 beam.

[0193] When the amount of available resources is insufficient, the WTRU may perform a backoff procedure. The procedure may include performing one or more of the following actions: retrying the resource selection process (determining available resources), possibly in conjunction with another action that may affect the available resources; performing a backoff with a configured, random, or determined time T; changing the transmission mode, or requesting the NW to change the transmission mode (e.g., from WTRU autonomous [similar to mode 4] to NW controlled [similar to mode 3]); changing the transmission resource pool; changing the RAT (e.g., from NR V2X to traditional V2X); increasing the robustness of the transmission, such as increasing the number of autonomous retransmissions, changing the MCS, changing the beam angle; completing resource selection and then transmitting, which may include an indication of the condition of insufficient available resources in the SCI; discarding pending transmissions; changing from slot-based transmissions to symbol-based transmissions, or considering different granularity of resources for transmission (e.g., considering both slot-based transmissions and symbol-based transmissions as opposed to only slot-based transmissions); changing the operating BW or BWP.

[0194] The WTRU may also decide which process to use based on any of: QoS parameters associated with the data to be sent; transmission type (unicast, multicast, broadcast); and beam angle (i.e., whether transmitting on a single beam or on multiple beams).

[0195] When the amount of available resources within the considered window is insufficient, the WTRU may perform a backoff at a randomly selected time T. 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 also apply this backoff only to data with specific QoS requirements, such as for certain PPPP values ​​or PDB values. The WTRU may target certain values ​​of QoS parameters (e.g., PPPP, PDB).

[0196] The WTRU may autonomously change the BWP of operation from the current BWP to a BWP with a larger bandwidth (eg, for certain values ​​of QoS parameters (eg, PPPP, PDB)). The WTRU may then perform the resource selection procedure again on the new BWP.

[0197] The WTRU may repeat the resource selection process by considering both symbol-based resources and slot-based resources (e.g., for certain values ​​of QoS parameters (e.g., PPPP, PDB) among the potential resources for resource selection. The WTRU may then determine the amount of available resources by considering both the slot-based resources and the symbol-based resources. If the amount of available resources is insufficient after considering both the slot-based and symbol-based resources, the WTRU performs one of the other alternative processes.

[0198] The WTRU may determine from the selectable resources a set of resources that are available or unused by other WTRUs. The WTRU may then select a resource from the set of available resources based on any or a combination of the following factors and / or criteria.

[0199] The WTRU may select a resource based on a random selection, potentially from the remaining available resources, which may be determined by any other factors described herein.

[0200] 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 the resource to be used for transmission. For example, the WTRU may select a resource for which no other WTRU has forward booked the resource. If there is no such resource in the set of available resources, the WTRU may select a resource that may be booked by another WTRU but has the smallest SCI RSRP.

[0201] The WTRU may be configured to randomly select between available resources, where different resources may be weighted based on time. The WTRU may be configured to have different weighting configurations or arrangements (e.g., assigning weights to time resources within a window of selectable resources) for different time criticality parameters (e.g., PPPP, packet delay requirements). A WTRU with non-time critical data may select a resource that appears later in the window of selectable resources with a higher probability.

[0202] The WTRU may select only from resources applicable to a particular destination, direction, transmission type (e.g., unicast / multicast / broadcast), or the like. Once a subset of resources for such operation is determined, the WTRU may use other factors (e.g., random selection, weighting, etc.) to select resources from these resources.

[0203] 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 may be used for each destination. For example, as further discussed herein, such a set of resources may be associated with a periodic configuration configured for a specific destination address or the like. The time offset / reference of these resources may also vary over time. The WTRU may maintain sensing results for all time / frequency / beam resources. At resource selection, the WTRU may select resources from a set of resources associated with the configuration for a specific destination to which it is to transmit.

[0204] The WTRU may select different amounts of resources depending on the reliability requirements of the transmission. For example, the WTRU may select more resources for transmissions with a larger range / reliability criteria. Such resources may be contiguous (e.g., to allow for a larger decoding for the initial transmission) or non-contiguous (to allow for more repetitions of the same data).

[0205] The WTRU may determine the number of repetitions / retransmissions of a transport block based on QoS parameters associated with the data (e.g., reliability, PPPR, 5QI, or similar). The WTRU may select a number of different time / frequency resources corresponding to the number of repetitions / retransmissions within the set of available resources (e.g., in the time period (T1, T2)).

[0206] The WTRU may select resources with a particular quality metric based on QoS parameters associated with the data to be transmitted. For example, the WTRU may select resources with a better quality metric to perform transmission of packets with a higher QoS (e.g., higher priority, reliability, range, or similar QoS requirements), and may conversely select resources with a lower quality metric for packets with a lower QoS requirement. The quality metric may be determined by the WTRU using any one or a combination of the following criteria:

[0207] The quality metric may be determined by detection of SCI reserved resources. The WTRU may determine that it has not detected resources of an SCI transmitted by another WTRU that reserved resources with a high quality.

[0208] The quality metric may be determined by the physical sidelink control channel (PSCCH) RSRP. For example, the WTRU may determine that the quality of a reserved / pre-booked resource is higher than the quality of another reserved / pre-booked resource for which the physical sidelink shared channel (PSSCH) RSRP is lower than that of the other reserved / pre-booked resource.

[0209] The quality metric may be determined by the PSSCH RSSI. For example, the WTRU may determine the quality of a resource based on PSSCH RSSI of related resources (e.g., associated with the same beam, fixed period, same time / frequency location, same channel, etc.) that occurred in the past.

[0210] The quality metric may be determined by the presence of neighboring resources (in time / frequency / beam). The WTRU may determine resources targeted by other WTRU transmissions scheduled on neighboring resources (e.g., in time, frequency, or beam dimensions) as being of lower quality. For example, a symbol in a slot for which another WTRU has already reserved another symbol may be considered to be of lower quality.

[0211] The WTRU may be pre-configured with a randomness factor that is used to determine which resource to select from among the available resources. The randomness factor may point to a specific resource to select from among the available resources, or may be used as part of a hash function or randomization to select from among the available resources. The WTRU derives the randomness factor based on one or more of the following criteria: the V2X or ProSe WTRU ID of the WTRU performing the resource selection; the destination address of the WTRU ID; the QoS parameters of the data to be transmitted, such as PPPP, PPPR, 5QI, or similar parameters; the sequence number of the packet, such as the PDCP / RRC SN or application layer SN; the NW configuration value; the pre-configured value; and the geographic location (e.g., region, GPS location, etc.). For example, the WTRU may determine its randomness factor based on its GPS location, or an index / identification of the configuration region or geographic region in which the WTRU is located.

[0212] The selection / hashing function may be a modular operation. For example, the resources may be ordered in time / frequency and the selection is performed at the Nth value and modulo the number of resources. The WTRU may use a randomness factor as the value of N.

[0213] The selection / hashing function may be an association of resources with a configuration / determination of a randomness factor. For example, the WTRU may be configured with a set of resources, a BW, one or more subchannels, a bandwidth portion, or the like that may be used for a given configured randomness factor.

[0214] Compared to random selection in conventional V2X, this approach may reduce the need to have a large percentage (i.e., 20%) of available resources to avoid multiple WTRUs performing the resource selection process simultaneously and selecting the same resource. When less than 20% of the resources are determined to be available, the WTRU may be allowed to perform the transmission because it does not rely on random selection.

[0215] The WTRU may be configured to transmit on different (e.g., overlapping or non-overlapping) bandwidth parts (BWPs) in the sidelink. The bandwidth part of the sidelink may be defined by a set of sidelink subchannels or resource blocks in frequency on a sidelink subframe / time slot / symbol. Resource selection may occur in the case where the WTRU may transmit sidelink data on multiple bandwidth parts.

[0216] The WTRU may first perform resource selection on a first BWP. If resource selection on the first BWP fails, the WTRU may perform resource selection on a second BWP. The resource selection failure may be a result of one or more of: failure to find a sufficient number of available resources to satisfy the resource selection; a measured occupancy of the first BWP (e.g., channel busy ratio (CBR), measurement of the number of SCI transmissions, etc.) is above some amount; and failure to satisfy one of the QoS requirements of the data based on the available resources.

[0217] When changing 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 in one or more of the following situations: expiration of a timer; successful completion of a set of related transmissions that require a different resource selection operation; and the WTRU no longer has data to transmit associated with transmissions of certain priority or QoS characteristics.

[0218] The WTRU may determine whether to allow a transmission and / or the amount of resources to transmit in one BWP / pool based on the resource utilization observed in another BWP / pool (or a portion thereof). More specifically, the WTRU may measure the utilization in another BWP / pool (or a portion thereof) to determine how many resources it should select from its own BWP / pool. When large / small utilization is detected on a different BWP / pool, the WTRU may decide to perform any of the following actions. The WTRU may postpone the transmission on the initial pool for a period of time. The WTRU may discard / preempt the transmission it had planned for the initial pool. The WTRU may change carriers / pools / BWPs. The WTRU may reduce the amount of resources selected (e.g., periodicity, number of RBs, total amount of time / frequency resources, etc.) by some amount.

[0219] The WTRU may measure the utilization in another BWP / pool (or a portion thereof) based on the mechanisms described herein. The WTRU may determine the usage or utilization of a portion of a pool or BWP. A portion of a pool or BWP may consist of resources that the WTRU itself is not configured to use for a specific transmission. This portion may depend on its own pool configuration. The usage of only this portion of a pool or BWP may be considered, rather than the usage of the entire BWP.

[0220] The WTRU may be configured to have multiple pools associated with different priorities and / or delay requirements. The priorities and / or delay requirements may be derived from the VQI. The pools may also have some overlapping resources so that a high priority WTRU may use all resources available to a low priority WTRU, as well as additional resources that are not available to the WTRU. If a WTRU detects that the CBR of resources associated with a high priority WTRU (and not overlapping with its own resources) is above a threshold, the WTRU may be required to preempt its own transmission in a low priority pool.

[0221] Figure 4A An example resource selection 400 using a resource pool based on quality of service (QoS) is shown, which can be used in conjunction with any other embodiment described herein. Figure 4AAs shown, multiple resource pools, such as pool 1 415 and pool 2 420, may be configured in one or more WTRUs based on QoS requirements (e.g., priority). For example, pool 1 415 may be configured with high priority transmissions 407, and pool 2 420 may be configured with low priority transmissions 412 as well as high priority transmissions 407. One or more WTRUs 405 with high priority data may 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 may be configured to use only pool 2 420 when transmitting low priority data (i.e., low priority transmissions 412). At some point, when more high priority transmissions 407 enter the resource pools 415, 420, and as a result, the resource pools (i.e., pool 1 425 and / or pool 2 430) become more congested, the one or more WTRUs 410 with low priority data may reduce their transmission power based on the sensing results (e.g., RSSI, RSRP, etc.) on their own pool 2 430 as described above. In this way, the 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 the transmission of data associated with a high priority, while a low priority transmission may refer to the transmission of data associated with a low priority.

[0222] Figure 4B An example resource selection 450 based on congestion measurement is shown, which can be used in conjunction with any other embodiment described herein. Figure 4A , multiple resource pools, such as pool 1 465 and pool 2 470, may be configured in one or more WTRUs based on QoS requirements (e.g., priority). Figure 4BAs shown, pool 1 465 may be configured with high priority transmissions 457, and pool 2 470 may be configured with low priority transmissions 462 as well as high priority transmissions 457. One or more WTRUs 455 with high priority data may 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 may be configured to use only pool 2 470 when transmitting low priority data (i.e., low priority transmissions 462). At some point, when more high priority transmissions 457 enter the resource pools 465, 470, and as a result, the resource pools (i.e., pool 1 475 and / or pool 2 480) become more congested, the one or more WTRUs 460 with low priority data may determine whether to stop transmitting low priority data on its own resource pool (i.e., pool 2 480). The determination to stop transmitting on its own resource pool (ie, pool 2 480) may be based on congestion measurements on resource pool(s) (ie, pool 1 475) that are not configured for use by one or more WTRUs 460 having low priority data.

[0223] For example, a WTRU 460 with low priority data that is configured to use pool 2 460 may perform at least one congestion measurement on pool 1 475 that is not configured to be used by the WTRU 460 with low priority data. As described above, pool 1 475 is configured to be used by other WTRUs 455 with high priority data, but is not configured to be used by the WTRU 460 with low priority data. If the congestion measurement on pool 1 475 exceeds certain thresholds, the WTRU 460 with low priority data may defer its own transmission on pool 2 480 for a period of time. This period of time may be provided by the network, for example, via RRC signaling, or may be preconfigured in the WTRU. During this period of time, the deferred low priority data may accumulate in the WTRU's buffer until it resumes the low priority data transmission 462. In another example, if the congestion measurement on pool 1 475 exceeds certain thresholds, the WTRU 460 with low priority data may preempt its planned (or reserved) future transmission on pool 2 480. In another example, if the congestion measurement on pool 1 475 exceeds some threshold, the 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. The 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 the low priority transmission 462 on its pool 2 480.

[0224] Although Figure 4B 480) configured for high priority transmissions 462.

[0225] Figure 5 An example process 500 for resource selection based on congestion measurement is shown, which may be used in conjunction with any other embodiment described herein. In step 510, a WTRU may receive a resource pool configuration from a base station (BS), the resource pool configuration including information associated with a plurality of resource pools. The information may indicate the use, allocation, or arrangement of a plurality of resource pools based on QoS requirements (e.g., priority, delay, 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 for the WTRU (and other WTRUs that may be scheduled / assigned for low priority transmission). The second resource pool may be configured for high priority data transmission for other WTRUs. The resource pool configuration may be received at the WTRU via RRC signaling or system information broadcast (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 radio resource sets, the radio resource sets including one or more elements selected from the time domain, the frequency domain, and / or the spatial domain.

[0226] In step 520, a WTRU configured to transmit low priority data on a first resource pool may perform at least one congestion measurement of a second resource pool on which other WTRUs are configured to transmit high priority data. Based on the congestion measurement of the second resource pool, the WTRU may determine whether to use the first resource pool to transmit its low priority data. For example, in step 530, the WTRU may determine whether the congestion measurement is below or above a predetermined threshold. If the congestion measurement of the second resource pool is below the predetermined threshold, then in step 540, the WTRU may use the first resource pool to transmit its low priority data. If the congestion measurement is above the predetermined threshold, then in step 550, the WTRU may not use the first resource pool to transmit its low priority data. The predetermined threshold may be received by the network via RRC signaling or system information broadcast (e.g., SIB) prior to the congestion measurement or may be preconfigured in the WTRU.

[0227] In one embodiment, if the congestion measurement is above a predetermined threshold, the WTRU may defer data transmission on the first resource pool for a time period. The time period may be configured by the network via RRC signaling or system information broadcast (e.g., SIB), or may be preconfigured in the WTRU. During this time period, data to be transmitted on the first resource pool may accumulate in a buffer or queue of the WTRU until the WTRU resumes its transmission using the first resource pool. In another embodiment, if the congestion measurement is above a predetermined threshold, the WTRU may preempt planned (or reserved) future data transmissions on the first resource pool. In another embodiment, if the congestion measurement is above a predetermined threshold, the WTRU may reduce the amount of resources in the first resource pool, and may transmit data or not transmit data based on the remaining resources in the first resource pool.

[0228] 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 the present disclosure.

[0229] The WTRU may select between different resource selection mechanisms based on QoS / receiver / channel usage. The WTRU may be configured to perform different types of WTRU autonomous resource selection. The WTRU may also be 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 specifying the selection of the resource selection mechanism may be determined by one or more of the following criteria. The selection of the resource selection mechanism may be determined by the QoS of the data to be transmitted on the selected resources. The selection of the resource selection mechanism may be determined by the intended recipients of the data to be transmitted on the selected resources and / or their relative / absolute locations. The selection of the resource selection mechanism may be determined by the usage conditions of the resources to be selected, such as measured CBR or sensing results.

[0230] The 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 where the WTRU uses its own sensing results to determine a set of available resources and transmits on a subset of these resources. Autonomous resource selection based on assistance from other WTRUs may be where the WTRU may use assistance information (e.g., sensing results) from other WTRUs. Scheduling resources by one WTRU for another WTRU may be where one WTRU schedules resources for other WTRUs in the group. Another resource selection mechanism may be to use a preconfigured set of resources.

[0231] The following examples do not exclude 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 the following: measured CBR, the number of detected SCIs (or scheduling messages) and / or measured signal strengths of such scheduling messages, the number of detected forward resource reservation signals or messages that may reserve resources for a number or an unlimited number of time periods, measured RSSI, application layer information or network signaling indicating the use of a particular resource pool or set of resources, and the number of WTRUs transmitting one-time and / or periodic resources.

[0232] The WTRU may use a resource selection mechanism that reduces the probability of collisions under high occupancy and may use a resource selection mechanism that does not consider the possibility of collisions under low occupancy.

[0233] The WTRU may be configured with resource selection based on sensing only (e.g., LTE) and with resource selection requiring listen before talk (LBT). The WTRU may measure the CBR in the resource pool used for transmission. If the WTRU measures the CBR above a threshold, the WTRU may use LBT based resource selection. If the WTRU measures the CBR below a threshold, the WTRU may use conventional (e.g., LTE) autonomous resource selection.

[0234] The WTRU may select a resource selection mechanism based on the QoS of the data to be transmitted. More specifically, the WTRU may identify the QoS of the data to be transmitted based on one or more of the following. The WTRU may identify the QoS of the data to be transmitted based on the logical channels multiplexed into the PDU to be transmitted. The WTRU may identify 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. The parameter may indicate any of reliability, latency, range, priority, or data rate of the desired transmission.

[0235] The WTRU may select the transport mechanism that best suits the QoS parameters associated with the data to be transmitted.

[0236] The WTRU may determine the reliability requirement of a packet based on a VQI associated with a logical channel or bearer. The WTRU may consider a first range of VQI parameters as high reliability and a second range of VQI parameters as low reliability. The WTRU may use resource selection based on preconfigured resources for high reliability transmissions and may use resource selection based on WTRU autonomous resource selection and / or selection with WTRU assistance for low reliability transmissions.

[0237] The WTRU may use multiple factors (e.g., QoS, channel occupancy, etc.) to determine the resource selection mode. For example, the WTRU may use LBT transmission for high reliability transmission when the CBR is above a threshold, and may use regular (e.g., LTE) transmission otherwise.

[0238] As described above, the WTRU in transmission mode 4 may autonomously determine the granularity of time / frequency / beam resources based on pre-configuration or based on sensing results. The WTRU may determine the resource granularity for resource selection based on the service type. The WTRU may determine the amount / percentage of symbol-based and slot-based resources in the selectable resource set.

[0239] The WTRU may determine the selectable resources (e.g., selectable bandwidth, granularity, beamwidth) at time T based on the time criticality of the transmission. The WTRU may determine the BW (possibly changing the center frequency) based on the priority / time criticality. The WTRU may determine the selection window start time (T1) based on the priority / time criticality.

[0240] The WTRU may include resources associated with a subset of beams in an optional resource set. The beam may be determined based on upper layer information (e.g., destination address, 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 upper layer information.

[0241] The WTRU may use multiple resource selection attempts (over different time windows) or defer resource selection to a future window based on time criticality, CBR or other parameters. The WTRU may modify resource selection parameters in each subsequent window of the multi-attempt resource selection.

[0242] If the resource granularity is not determined based on the QoS related characteristics of the packet during the optional resource phase, the WTRU may determine the resource granularity for transmission, possibly in conjunction with sensing results / availability information.

[0243] The WTRU may determine resource availability assuming that possible transmissions may have different granularities. The WTRU may use separate sensing results for symbol-based transmissions and slot-based transmissions. The WTRU may determine the availability of resources for slot-based transmissions based on sensing results associated with symbol-based transmissions and vice versa.

[0244] The WTRU may determine the availability of resources based on the range / reliability parameters of another WTRU (transmitted in the SCI) and the RSRP of the received SCI.

[0245] The WTRU may dynamically determine the amount of sufficient resources to perform resource selection and a new fallback procedure in case of failure.

[0246] Resource selection (from a set of available resources) can be based on one or more of the following: weighting the resources in time based on time criticality; the number / amount of resources selected based on reliability / range requirements associated with data transmission; the quality of the resources compared to QoS characteristics; and using a preconfigured selection factor to hash the WTRU to one of the available resources.

[0247] When resource selection on the first BWP fails, the WTRU may make a temporary transmission / resource selection on the second sidelink BWP.

[0248] Although the features and elements are described above in specific combinations, it will be understood by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein can be implemented in a computer program, software, or firmware that is incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of 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 the software can be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A wireless transmit receive unit (WTRU), comprising: a processor configured to select one or more resources based on congestion of a resource pool reserved for one or more higher priority WTRUs; as well as A transmitter is configured to transmit a sidelink signal to a second WTRU using the one or more resources.

2. A wireless transmit receive unit (WTRU), comprising: a processor configured to select one or more resources from a set of available resources using a function of a WTRU identity defined for each of a plurality of regions; as well as A transmitter is configured to transmit a sidelink signal to a second WTRU using the one or more resources.

3. A method performed by a wireless transmit receive unit (WTRU), the method comprising: Selecting one or more sources based on a delay of transmission using a set of subchannels, a starting resource, a percentage of resources of different granularities, or any combination thereof; as well as A sidelink transmission is transmitted to the second WTRU based on the selection.

4. A method performed by a wireless transmit receive unit (WTRU), the method comprising: determining, based on one or more quality of service parameters, an amount of available resources at which random resource selection can occur; transmitting a sidelink signal to a second WTRU if the amount of available resources is greater than or equal to a threshold; as well as When the available resource amount is less than the threshold, a backoff process is performed.

5. A wireless transmit receive unit (WTRU), comprising: a processor configured to select one or more resources; as well as A transmitter is configured to transmit a sidelink transmission to a second WTRU using the selected one or more resources.

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