CN117941429A - Side link collision detection and indication - Google Patents

Abstract

Systems, methods, and instrumentalities are described herein for Side Link (SL) collision detection and indication (e.g., in new air interface (NR) vehicle communications (V2X)). A wireless transmit/receive unit (WTRU) may send a resource reservation (e.g., in a side link control information (SCI)). A Receiving (RX) WTRU may receive SCI from a Transmit (TX) WTRU(s), where the TX WTRUs reserve resources for transmission. The TX WTRUs may not be aware of other TX WTRUs (e.g., are unaware of resources reserved by other TX WTRUs). For example, if reserved resources overlap (e.g., partially or fully), then the resources may collide. For example, a collision may occur if multiple TX WTRUs reserve resources for transmission that are in conflict and/or if those TX WTRUs that reserve resources for transmission that are in conflict do not reselect non-conflicting resources.

Description

Side link collision detection and indication

Cross Reference to Related Applications

The application claims the benefit of U.S. provisional application Ser. No. 63/228,653 filed on 8/3/2021 and U.S. provisional application Ser. No. 63/249,260 filed on 28/9/2021, the contents of which are incorporated herein by reference in their entirety.

Background

Mobile communications using wireless communications continue to evolve. The fifth generation mobile communication Radio Access Technology (RAT) may be referred to as 5G new air interface (NR). The previous generation (legacy) mobile communication RAT may be, for example, fourth generation (4G) Long Term Evolution (LTE).

Disclosure of Invention

Systems, methods, and instrumentalities are described herein for Side Link (SL) collision detection and indication (e.g., in new air interface (NR) vehicle communications (V2X)). A wireless transmit/receive unit (WTRU) may send a resource reservation (e.g., in a side link control information (SCI)). A Receiving (RX) WTRU may receive SCI from a Transmit (TX) WTRU(s), where the TX WTRUs reserve resources for transmission. The TX WTRUs may not be aware of other TX WTRUs (e.g., are unaware of resources reserved by other TX WTRUs). For example, if reserved resources overlap (e.g., partially or fully), then the resources may collide. For example, a collision may occur if multiple TX WTRUs reserve resources for transmission that are in conflict and/or if those TX WTRUs that reserve resources for transmission that are in conflict do not reselect non-conflicting resources.

An RX WTRU (e.g., a first WTRU) may receive configuration information indicating a collision detection processing time (e.g., a time at which the RX WTRU is to determine that a collision exists and send a collision indication). The RX WTRU may receive a first SCI from a first TX WTRU (e.g., a second WTRU). The first SCI may include an indication (e.g., a first indication) indicating the first resource, the first collision indication setting, and/or the first priority value. The RX WTRU may receive an indication of a collision indication processing time, e.g., associated with the first TX WTRU. The RX WTRU may determine a collision detection trigger occasion (e.g., a time window in which the RX WTRU has sufficient time to detect a collision and, for example, send a collision indication to the first TX WTRU) based on at least the collision detection processing time and the first resource. The collision detection trigger occasion may be determined, for example, based on the collision detection processing time, the collision indication processing time (e.g., associated with the first TX WTRU), and the first resource. For example, during a collision detection trigger occasion, the RX WTRU may receive a second SCI from a second TX WTRU (e.g., a third WTRU). The second SCI may include an indication (e.g., a second indication) indicating a second resource, a second collision indication setting, and/or a second priority value. The RX WTRU may determine that there is a collision associated with the first resource and the second resource. For example, the RX WTRU may determine that there is a collision associated with the first resource and the second resource based on a determination that a measurement associated with the second SCI (e.g., reference Signal Received Power (RSRP)) is greater than a first threshold. For example, based on a determination that the first resource overlaps (e.g., partially or fully) with the second resource, the RX WTRU may determine that there is a collision associated with the first resource and the second resource. The RX WTRU may send a collision indication to the first TX WTRU, for example. For example, the RX WTRU may send a collision indication to the first TX WTRU based on a determination that the first collision indication setting is enabled and the second collision indication setting is disabled. For example, the RX WTRU may send a collision indication to the first TX WTRU based on a determination that the first collision indication setting is enabled, the second collision indication setting is enabled, and the first priority value is greater than the second priority value.

Drawings

Fig. 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented.

Fig. 1B is a system diagram illustrating an exemplary wireless transmit/receive unit (WTRU) that may be used within the communication system shown in fig. 1A, in accordance with an embodiment.

Fig. 1C is a system diagram illustrating an exemplary Radio Access Network (RAN) and an exemplary Core Network (CN) that may be used within the communication system shown in fig. 1A, according to an embodiment.

Fig. 1D is a system diagram illustrating another exemplary RAN and another exemplary CN that may be used in the communication system shown in fig. 1A, according to an embodiment.

Fig. 2A-2D illustrate examples of WTRU collision detection trigger occasions for retransmitting resource reservations.

Fig. 3 illustrates an example of an RX WTRU performing collision detection and collision indication.

Fig. 4A to 4C illustrate examples of PSICH transmission.

Fig. 5A illustrates an example of PSICH transmission for one-time resource reselection.

Fig. 5B illustrates an example of PSICH transmission for periodic resource reselection.

Detailed Description

Systems, methods, and instrumentalities are described herein for Side Link (SL) collision detection and indication (e.g., in new air interface (NR) vehicle communications (V2X)). A Receiver (RX) wireless transmit/receive unit (WTRU) may determine a trigger for collision detection of one or more resources reserved in received SL Control Information (SCI) associated with a (pre) configured WTRU source and/or destination Identifier (ID), e.g., based on information indicated in the received SCI (e.g., L1 priority and time resources) and/or (pre) configured parameters (e.g., channel Busy Rate (CBR) and L1 priority threshold). The RX WTRU may detect the collision and/or collision type, e.g., based on SCI decoding in the SL slot set, which may be determined, e.g., based on reserved time resources, reference Signal Received Power (RSRP) threshold configuration, and/or indicated resource reservation periods. The RX WTRU may determine that the TX WTRU is to transmit a physical side link indication channel (PSICH) transmission to indicate one-time resource reselection, periodic resource reselection, cancellation of retransmissions, etc., e.g., as a result of a detected collision using the corresponding PSICH format and resources. TX WTRU behavior may be determined, for example, based on receiving a PSICH transmission based on PSICH information (e.g., including shutting down resource preemption).

Fig. 1A is a schematic diagram illustrating an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. Communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messages, broadcasts, etc., to a plurality of wireless users. Communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, 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 Multicarrier (FBMC), and the like.

As shown in fig. 1A, the communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104/113, CNs 106/115, public Switched Telephone Networks (PSTN) 108, the internet 110, and other networks 112, although it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. As an example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a "station" and/or a "STA") may be configured to transmit and/or receive wireless signals and may include User Equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular telephones, personal Digital Assistants (PDAs), smartphones, laptop computers, netbooks, personal computers, wireless sensors, hot spot or Mi-Fi devices, internet of things (IoT) devices, watches or other wearable devices, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in an industrial and/or automated processing chain environment), consumer electronic devices, devices operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

Communication system 100 may also include base station 114a and/or base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the internet 110, and/or the other network 112. By way of example, the base stations 114a, 114B may be Base Transceiver Stations (BTSs), node bs, evolved node bs, home evolved node bs, gnbs, NR node bs, site controllers, access Points (APs), wireless routers, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

Base station 114a may be part of RAN 104/113 that may also include other base stations and/or network elements (not shown), such as Base Station Controllers (BSCs), radio Network Controllers (RNCs), relay nodes, and the like. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a particular 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 base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of a cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of a cell. For example, beamforming may be used to transmit and/or receive signals in a desired spatial direction.

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, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable Radio Access Technology (RAT).

More specifically, as noted above, 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, or the like. For example, a 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 interfaces 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).

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 use Long Term Evolution (LTE) and/or LTE-advanced (LTE-a) and/or LTE-advanced Pro (LTE-a Pro) to establish the air interface 116.

In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may use a new air interface (NR) to establish the air interface 116.

In embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, e.g., using a Dual Connectivity (DC) principle. Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., enbs and gnbs).

In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., wireless fidelity (WiFi)), IEEE 802.16 (i.e., worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000 1X, CDMA EV-DO, tentative standard 2000 (IS-2000), tentative standard 95 (IS-95), tentative standard 856 (IS-856), global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE (GERAN), and the like.

The base station 114B in fig. 1A may be, for example, a wireless router, home node B, home evolved node B, or access point, and may utilize any suitable RAT to facilitate wireless connections in local areas such as business, home, vehicle, campus, industrial facility, air corridor (e.g., for use by drones), road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a Wireless Local Area Network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-a Pro, NR, etc.) to establish a pico cell or femto cell. As shown in fig. 1A, the base station 114b may have a direct connection with the internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106/115.

The RANs 104/113 may communicate with the CNs 106/115, which may be any type of network configured to provide voice, data, application, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102 d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, delay requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location based services, prepaid calls, internet connections, video distribution, etc., and/or perform advanced security functions such as user authentication. Although not shown in fig. 1A, it should be appreciated that the RANs 104/113 and/or CNs 106/115 may communicate directly or indirectly with other RANs that employ the same RAT as the RANs 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113 that may utilize NR radio technology, the CN 106/115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA 2000, wiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112.PSTN 108 may include circuit-switched telephone networks that provide Plain Old Telephone Services (POTS). The internet 110 may include a global system for interconnecting computer networks and devices using common communication protocols, such as Transmission Control Protocol (TCP), user Datagram Protocol (UDP), and/or Internet Protocol (IP) in the TCP/IP internet protocol suite. Network 112 may include wired and/or wireless communication networks owned and/or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RANs 104/113 or a different RAT.

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 over different wireless links). For example, the WTRU102c shown in fig. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based radio technology, and with a base station 114b, which may employ an IEEE 802 radio technology.

Fig. 1B is a system diagram illustrating an exemplary WTRU 102. As shown in fig. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and/or other peripheral devices 138, etc. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuit (IC), a state machine, or the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to a transmit/receive element 122. Although fig. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

The transmit/receive element 122 may be configured to transmit signals to and receive signals from a base station (e.g., base station 114 a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to emit 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 RF and optical signals. It should be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted as a single element in fig. 1B, 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.

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

The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker/microphone 124, a keypad 126, and/or a display/touchpad 128, such as a Liquid Crystal Display (LCD) display unit or an Organic Light Emitting Diode (OLED) display unit. The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. Further, the processor 118 may access information from and store data in any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include Random Access Memory (RAM), read Only Memory (ROM), a hard disk, or any other type of memory storage device. 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 never physically locate memory access information on the WTRU 102, such as on a server or home computer (not shown), and store the data in that memory.

The processor 118 may receive power from the power source 134 and may be configured to distribute and/or control power to 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 battery packs (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

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

The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software modules and/or hardware modules that provide additional features, functionality, and/or wired or wireless connections. For example, the number of the cells to be processed, peripheral devices 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (for photographs and/or video), universal Serial Bus (USB) ports, vibrating devices, television transceivers, hands-free headsets, wireless communications devices, and the like,Modules, frequency Modulation (FM) radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and/or augmented reality (VR/AR) devices, activity trackers, and the like. The peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; a geographic position sensor; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and/or humidity sensors.

WTRU 102 may include a full duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and/or simultaneous. The full duplex radio station may include an interference management unit for reducing and/or substantially eliminating 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 one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or downlink (e.g., for reception)).

Fig. 1C is a system diagram illustrating a RAN 104 and a CN 106 according to one embodiment. As noted above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using an E-UTRA radio technology. RAN 104 may also communicate with CN 106.

RAN 104 may include enode bs 160a, 160B, 160c, but it should be understood that 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 to communicate with the WTRUs 102a, 102B, 102c over the air interface 116. In one embodiment, the evolved node bs 160a, 160B, 160c may implement MIMO technology. Thus, the enode B160 a may transmit wireless signals to and/or receive wireless signals from the WTRU 102a, e.g., using multiple antennas.

Each of the evolved node bs 160a, 160B, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and/or DL, and the like. As shown in fig. 1C, the enode bs 160a, 160B, 160C may communicate with each other over an X2 interface.

The CN 106 shown in fig. 1C may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the evolved node bs 162a, 162B, 162c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating the user of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, and the like. MME 162 may provide control plane functionality for switching between RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and/or WCDMA.

SGW 164 may be connected to each of the evolved node bs 160a, 160B, 160c in RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102 c. The SGW 164 may perform other functions such as anchoring user planes during inter-enode B handover, triggering paging when DL data is available to the WTRUs 102a, 102B, 102c, managing and storing the contexts of the WTRUs 102a, 102B, 102c, etc.

The SGW 164 may be connected to a PGW 166 that may provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network (such as the PSTN 108) to facilitate communications between the WTRUs 102a, 102b, 102c and legacy landline communication devices. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers.

Although the WTRU is depicted in fig. 1A-1D as a wireless terminal, it is contemplated that in some representative embodiments such a terminal may use a wired communication interface with a communication network (e.g., temporarily or permanently).

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

A WLAN in an infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP may have access or interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic to and/or from the BSS. Traffic originating outside the BSS and directed to the STA may arrive through the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be sent to the AP to be delivered to the respective destination. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may pass the 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 (e.g., directly between) the source and destination STAs using 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 (e.g., 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.

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

High Throughput (HT) STAs may communicate using 40MHz wide channels, for example, via a combination of a primary 20MHz channel with an adjacent or non-adjacent 20MHz channel to form a 40MHz wide channel.

Very High Throughput (VHT) STAs may support channels that are 20MHz, 40MHz, 80MHz, and/or 160MHz wide. 40MHz and/or 80MHz channels may be formed by combining consecutive 20MHz channels. The 160MHz channel may be formed by combining 8 consecutive 20MHz channels, or by combining two non-consecutive 80MHz channels (this may be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data may pass through a segment parser that may split the data into two streams. An Inverse Fast Fourier Transform (IFFT) process and a time domain process may be performed on each stream separately. These streams may be mapped to two 80MHz channels and data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be sent to a Medium Access Control (MAC).

The 802.11af and 802.11ah support modes of operation below 1 GHz. Channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11 ac. The 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the television white space (TVWS) spectrum, and the 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter type control/machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including supporting (e.g., supporting only) certain bandwidths and/or limited bandwidths. MTC devices may include batteries with battery lives above a threshold (e.g., to maintain very long battery lives).

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 STAs from all STAs operating in the BSS (which support a minimum bandwidth mode of operation). In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only) 1MHz mode, the primary channel may be 1MHz wide, even though the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and/or other channel bandwidth modes of operation. The carrier sense 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 the STA (supporting only 1MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy even though most of the frequency band remains idle and possibly available.

The available frequency band for 802.11ah in the united states is 902MHz to 928MHz. In korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

Fig. 1D is a system diagram illustrating RAN 113 and CN 115 according to one embodiment. As noted above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, 102c over an air interface 116. RAN 113 may also communicate with CN 115.

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

The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using transmissions associated with the scalable parameter sets. For example, the OFDM symbol interval and/or OFDM subcarrier interval may vary from one transmission to another, from one cell to another, and/or from one portion of the wireless transmission spectrum to another. The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using various or scalable length subframes or Transmission Time Intervals (TTIs) (e.g., including different numbers of OFDM symbols and/or continuously varying absolute time lengths).

The gnbs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in an independent configuration and/or in a non-independent configuration. In a standalone configuration, the WTRUs 102a, 102B, 102c may communicate with the gnbs 180a, 180B, 180c while also not accessing other RANs (e.g., such as the enode bs 160a, 160B, 160 c). In an independent configuration, the WTRUs 102a, 102b, 102c may use one or more of the gnbs 180a, 180b, 180c as mobility anchor points. In an independent configuration, the WTRUs 102a, 102b, 102c may use signals in unlicensed frequency bands to communicate with the gnbs 180a, 180b, 180 c. In a non-standalone configuration, the WTRUs 102a, 102B, 102c may communicate or connect with the gnbs 180a, 180B, 180c, while also communicating or connecting with other RANs (such as the enode bs 160a, 160B, 160 c). For example, the WTRUs 102a, 102B, 102c may implement DC principles to communicate with one or more gnbs 180a, 180B, 180c and one or more enodebs 160a, 160B, 160c substantially simultaneously. In a non-standalone configuration, the 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, 102 c.

Each of the gnbs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and/or DL, support of network slices, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and so on. As shown in fig. 1D, gnbs 180a, 180b, 180c may communicate with each other through an Xn interface.

The CN 115 shown in fig. 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it should be understood that any of these elements may be owned and/or operated by an entity other than the CN operator.

AMFs 182a, 182b may be connected to one or more of gNB 180a, 180b, 180c in RAN 113 via an N2 interface and may function as a control node. For example, the AMFs 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slices (e.g., handling of different PDU sessions with different requirements), selection of a particular SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMFs 182a, 182b may use network slices to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service used by the WTRUs 102a, 102b, 102 c. For example, different network slices may be established for different use cases, such as services relying on ultra-high reliability low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, services for Machine Type Communication (MTC) access, and so on. AMF 162 may provide control plane functionality for switching between RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-a Pro, and/or non-3 GPP access technologies, such as WiFi.

The SMFs 183a, 183b may be connected to AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to UPFs 184a, 184b in the CN 115 via an N4 interface. SMFs 183a, 183b may select and control UPFs 184a, 184b and configure traffic routing through UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, ethernet-based, etc.

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

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

In view of fig. 1A-1D and the corresponding descriptions of fig. 1A-1D, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more emulation devices (not shown): the WTRUs 102a-d, base stations 114a-B, evolved node bs 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMFs 182a-B, UPFs 184a-B, SMFs 183a-B, DN 185a-B, and/or any other devices described herein. The emulated device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation device may be used to test other devices and/or analog network and/or WTRU functions.

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

The one or more emulation devices can perform one or more (including all) functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the simulation device may be used in a test laboratory and/or a test scenario in a non-deployed (e.g., test) wired and/or wireless communication network in order to enable testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and/or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation device to transmit and/or receive data.

Systems, methods, and instrumentalities are described herein for Side Link (SL) collision detection and indication (e.g., in new air interface (NR) vehicle communications (V2X)). A wireless transmit/receive unit (WTRU) may send a resource reservation (e.g., in a side link control information (SCI)). A Receiving (RX) WTRU may receive SCI from a Transmit (TX) WTRU(s), where the TX WTRUs reserve resources for transmission. The TX WTRUs may not be aware of other TX WTRUs (e.g., are unaware of resources reserved by other TX WTRUs). For example, if reserved resources overlap (e.g., partially or fully), then the resources may collide. For example, a collision may occur if multiple TX WTRUs reserve resources for transmission that are in conflict and/or if those TX WTRUs that reserve resources for transmission that are in conflict do not reselect non-conflicting resources.

An RX WTRU (e.g., a first WTRU) may receive configuration information indicating a collision detection processing time (e.g., a time at which the RX WTRU is to determine that a collision exists and send a collision indication). The RX WTRU may receive a first SCI from a first TX WTRU (e.g., a second WTRU). The first SCI may include an indication (e.g., a first indication) indicating the first resource, the first collision indication setting, and/or the first priority value. The RX WTRU may receive an indication of a collision indication processing time, e.g., associated with the first TX WTRU. The RX WTRU may determine a collision detection trigger occasion (e.g., a time window in which the RX WTRU has sufficient time to detect a collision and, for example, send a collision indication to the first TX WTRU) based on at least the collision detection processing time and the first resource. The collision detection trigger occasion may be determined, for example, based on the collision detection processing time, the collision indication processing time (e.g., associated with the first TX WTRU), and the first resource. For example, during a collision detection trigger occasion, the RX WTRU may receive a second SCI from a second TX WTRU (e.g., a third WTRU). The second SCI may include an indication (e.g., a second indication) indicating a second resource, a second collision indication setting, and/or a second priority value. The RX WTRU may determine that there is a collision associated with the first resource and the second resource. For example, the RX WTRU may determine that there is a collision associated with the first resource and the second resource based on a determination that a measurement associated with the second SCI (e.g., reference Signal Received Power (RSRP)) is greater than a first threshold. For example, based on a determination that the first resource overlaps (e.g., partially or fully) with the second resource, the RX WTRU may determine that there is a collision associated with the first resource and the second resource. The RX WTRU may send a collision indication to the first TX WTRU, for example. For example, the RX WTRU may send a collision indication to the first TX WTRU based on a determination that the first collision indication setting is enabled and the second collision indication setting is disabled. For example, the RX WTRU may send a collision indication to the first TX WTRU based on a determination that the first collision indication setting is enabled, the second collision indication setting is enabled, and the first priority value is greater than the second priority value.

The WTRU may determine detection of a collision in one or more aperiodic/periodic SL resources reserved by the multiple mode 2 WTRUs. The indication of the collision may be provided to the WTRU (e.g., one) based on, for example, priority, time and frequency allocation, and the reservation interval period indicated in the SCI. The method of SL collision detection and indication may include, for example, one or more of the following.

For example, the WTRU may be configured with one or more of the following: a subset of WTRU source and/or destination IDs; SL priority threshold (e.g., prio _thre); SL CBR threshold (e.g., CBR _thre); conflict detection processing time (e.g., T _proc); collision indicates a transmission processing time (e.g., T _PSICH); an enable/disable indication (e.g., conflictDetEnabled) for collision detection; an enable/disable indication (e.g., conflictIndEnabled) for a conflict indication; SL collision detection RSRP threshold (e.g., RSRP _conflict); PSICH format; and/or PSICH resource configuration.

The WTRU may receive a resource reservation in the SCI from the first TX WTRU and/or may determine a collision detection trigger occasion and/or a corresponding source for detection, e.g., based on one or more of: the number of resources reserved in SCI; a configured conflict detection processing time threshold; the configured conflict indicates a processing time threshold; time resource allocation indicated in the receiving SCI; and/or a resource reservation period indicated in the received SCI. The WTRU may determine a collision detection trigger occasion for an SP-based resource reservation that includes multiple (e.g., two) retransmission resources.

The WTRU may trigger collision detection under the determined collision detection trigger conditions, e.g., based on one or more of the following (e.g., a determination): the priority indicated in the received SCI and/or a configured priority threshold (e.g., prio _thre); measured SL CBR and/or configured CBR threshold (e.g., CBR _thre); a ConflictDetEnabled indicated in the received SCI; RSRP; a distance; TX WTRU power save state; a resource allocation scheme; TX WTRU type; a decoding state; and/or HARQ feedback status.

The WTRU may detect a collision in one or more resources of the determined collision detection, e.g., based on one or more of the following: a configured RSRP threshold; and/or RSRP from SCI transmissions of a second TX WTRU that are pre-reserved for the same resources measured in sensing.

The WTRU may determine a TX WTRU for collision indication transmission (e.g., PSICH) and corresponding (e.g., PSICH) format and information, e.g., based on one or more of: a priority indicated in the SCI by the first TX WTRU and the second TX WTRU; a resource reservation period indicated in the SCI by the first TX WTRU and the second TX WTRU; an enable/disable indication (e.g., conflictIndEnabled) for a conflict indication; and/or a configured PSICH format.

The WTRU may determine the determined resources of the PSICH transmission, e.g., based on one or more of: configured PSICH resources; the determined source and/or destination IDs of the TX WTRU; and/or time and/or frequency resource allocation indicated in SCI from the determined TX WTRU.

The WTRU may transmit the PSICH in the determined resources to the determined TX WTRU.

For example, a WTRU such as a Receiver (RX) WTRU may determine a trigger for collision detection for one or more resources reserved in the received SL Control Information (SCI) associated with a (pre) configured WTRU source and/or destination Identifier (ID), e.g., based on information indicated in the received SCI (e.g., L1 priority and time resources) and/or (pre) configured parameters (e.g., channel Busy Rate (CBR) and L1 priority threshold).

The RX WTRU may detect the collision and/or collision type, e.g., based on SCI decoding in the SL slot set, which may be determined, e.g., based on reserved time resources, reference Signal Received Power (RSRP) threshold configuration, and/or indicated resource reservation periods. The types of collisions may include collisions specific to beamforming (e.g., FR 2) operations, previously received SP-based reservations, SL/UL transmissions, multicast TX/RX collisions, and/or simultaneous partial overlapping and corresponding prioritized and indicated transmissions.

The RX WTRU may determine that the TX WTRU is to transmit a physical side link indication channel (PSICH) transmission to indicate one-time resource reselection, periodic resource reselection, cancellation of retransmissions, etc., e.g., as a result of a detected collision using the corresponding PSICH format and resources.

TX WTRU behavior may be determined, for example, based on receiving a PSICH transmission based on PSICH information (e.g., including shutting down resource preemption).

The WTRU may determine the PSICH power setting. The WTRU may determine the PSICH power setting, for example, in view of DL or SL path loss and concurrent PSICH and PSFCH transmissions. The PSICH power setting may be used for PSICH transmission or concurrent PSICH and/or PSFCH transmissions. For example, in view of prioritization, the WTRU may perform concurrent PSICH and PSFCH transmissions. Prioritization may be based on SL priority (e.g., associated with PSICH and/or PSFCH transmissions).

The WTRU may perform (e.g., determine) a collision information transmission. The conflicting information transfer may include information associated with a set of resources for which a conflict exists. The conflicting information transmission may include WTRU source and/or destination IDs associated with the set of resources in which a conflict exists. The WTRU may perform a collision information transmission, for example, to the TX WTRU. The TX WTRU may determine which set of resources to use for transmission based on, for example, a WTRU source/destination ID, a Reference Signal Received Power (RSRP), or a TX-RX distance for transmission of the collision information. The TX WTRU may combine the resources in the selected set in a resource selection window.

The SCI decoded RX WTRU behavior may be determined, for example, based on the transmission of resource information to the TX WTRU. For example, the RX WTRU may determine candidate resources (e.g., PSCCH candidate resources) within the resources (e.g., in the transmission of resource information) provided to the TX WTRU to the RX WTRU (e.g., from the decoded resource allocation). The RX WTRU may determine to prioritize (e.g., decode) candidate resources (e.g., PSCCH candidate resources) that are provided, for example, in a resource information transmission, within a set of resources of the TX WTRU (e.g., conflicting and non-conflicting).

Inter-WTRU coordination may be enabled and/or provided. Resource allocation (e.g., mode 2 resource allocation) may be improved (e.g., in terms of reliability). Mode 2 resource selection reliability may be affected by hidden nodes, exposed nodes, half duplex, and/or Uplink (UL)/Side Link (SL) transmission overlap. A Transmitter (TX) WTRU (e.g., a mode 2TX WTRU) may perform resource selection, e.g., based on sensing, which may not detect a problem. Multiple TX WTRUs may transmit concurrently on the same time and frequency resources, which may result in collisions. There may be persistent collisions between transmissions of semi-persistent reservations, which may reduce the reliability of vehicle communication (V2X) services.

Inter-WTRU coordination may alleviate one or more problems. Coordination may enable a Receiver (RX) WTRU to provide information to assist in the selection of resources of the TX WTRU. The coordination or sharing information may include, for example, a set of (e.g., explicit) resources, which may or may not be preferred for transmissions from the TX WTRU. The coordination or sharing information may include, for example, a collision indication (e.g., implicitly) applicable to resources that may be reserved by the TX WTRU.

The process of achieving inter-WTRU coordination may be based on V2X design and/or various operating scenarios.

Excessive signaling overhead and congestion may be caused by collision indication transmissions. For example, if (e.g., when) an RX WTRU receives a SCI in a physical side link control channel (PSCCH) from a TX WTRU in SL slot y ₀, then the SL Control Information (SCI) may reserve (e.g., additional) resources in subsequent SL slots to schedule physical side link shared channel (PSSCH)/PSCCH transmissions over an L _subCH subchannel in the same slot. The reserved resources may include, for example, multiple (e.g., two) resources for retransmission of (e.g., the same) SL Transport Block (TB) slots (e.g., y ₁＝y₀+T₁ and y ₂＝y₀+T₂). For example, if (e.g., when) the resource reservation period (e.g., P _{rsvp_TX}) is not equal to zero, resources reserved in one or more SL slots (e.g., y ₀、y₁ and y ₂) may be reserved (e.g., periodically) in the SL slots (e.g., y ₀+n*P_{rsvp_TX}、y₁+n*P_{rsvp_TX} and y ₂+n*P_{rsvp_TX}) for initial transmission and/or retransmission of (e.g., new) TBs. There may be several WTRUs in the vicinity that may receive the SCI and perform collision detection. The WTRU (e.g., each of several WTRUs) may transmit (e.g., several) the indication transmission. For example, signaling overhead and congestion may be reduced while improving reliability.

WTRU processing capabilities may be improved (e.g., to overcome limitations) to detect, indicate, and/or operate in accordance with collisions of (e.g., all) resources reserved in (e.g., one) SCI. The WTRU may utilize (e.g., sufficient) time and processing to perform collision detection (e.g., with high reliability) and prepare and transmit (e.g., subsequent) indications. The WTRU receiving the indication transmission to decode, process, and operate according to the indication may utilize more time. The WTRU may participate in V2X mode 2 sensing and resource selection processing to detect and indicate a collision of reserved resources (e.g., each) (e.g., regardless of the mode of the resources in the time domain). The WTRU receiving the indication may have the capability, limited capability, or no capability to operate in accordance with the indication. For example, a vulnerable road user (vulnerable road user, VRU) type WTRU may not have a receiver and/or may perform random resource selection.

The WTRU may detect a collision of resources, e.g., indicated in the received SCI. Conflicts of SL resources may be detected. The indication of the conflict may be (pre-) configured. The WTRU may receive an indication (e.g., configured (in advance) by higher layers) with configuration information such as one or more of the following (e.g., related to SL resource collision detection and indication): a subset of WTRU source and/or destination Identifiers (IDs); SL priority threshold (e.g., prio _thre); a SL Channel Busy Rate (CBR) threshold (e.g., CBR _thre); conflict detection processing time (e.g., T _proc); collision indicates a transmission processing time (e.g., T _PSICH); an enable/disable indication (e.g., conflictDetEnabled) for inter-WTRU coordination and/or collision detection; an enable/disable indication and/or a collision indication (e.g., conflictIndEnabled) for inter-WTRU coordination; a SL collision detection Reference Signal Received Power (RSRP) threshold (e.g., RSRP _conflict); and/or PSICH and/or PSFCH resource configurations for inter-WTRU coordination and/or collision detection.

The WTRU may receive configuration information indicating (e.g., configured (in advance) by a higher layer) a pair of WTRU source and/or destination IDs, e.g., for unicast SL transmission and/or reception. The WTRU may receive configuration information indicating (e.g., configured by higher layers (in advance) the WTRU destination ID, e.g., for multicast and/or unicast SL transmission and reception. The WTRU may receive (e.g., be (pre) configured with) configuration information for one or more (e.g., a set of) WTRU source and/or destination IDs, e.g., based on supported services (e.g., V2X services) and/or applications (e.g., V2X applications). In some examples, a subset of WTRU source and/or destination IDs may be indicated for (e.g., (pre) configuration) SL resource collision and/or indication. The WTRU may perform SL resource collision detection and indication, for example, on resources reserved for SL transmissions associated with a subset of WTRU source and/or destination IDs.

In some examples, the WTRU may receive (e.g., be (pre) configured with) configuration information for a SL priority threshold (e.g., prio _thre) in the SL resource pool. The WTRU may trigger SL resource collision detection and indication, e.g., based on (e.g., pre-configured) Prio _thre at (e.g., within) the resource collision detection trigger occasion. The SL priority threshold may (e.g., thus) enable collision detection and indication for SL transmissions (e.g., with high priority).

In some examples, the WTRU may receive configuration information indicating (e.g., being (pre) configured with) a SL CBR threshold (e.g., CBR _thre) in the SL resource pool. The WTRU may trigger SL resource collision detection and indication, e.g., based on (e.g., pre-configured) CBR _thre at (e.g., within) the resource collision detection trigger occasion. The SL CBR threshold may accommodate for an increase in SL congestion, which may be caused by the transmission of an indication as a result of SL resource collision detection.

The WTRU may receive configuration information indicating (e.g., being (pre) configured with) a WTRU collision detection processing time threshold (e.g., T _proc). The collision detection processing time threshold may correspond to a (e.g., minimum) period of time for the WTRU to perform collision detection (e.g., and transmit a result indication) (e.g., as needed). The time threshold may be expressed, for example, in terms of the number of SL slots. The value of the time threshold may be based on, for example, WTRU processing power and/or subcarrier spacing (SCS), such as SCS associated with SL bandwidth part (BWP) (e.g., a (pre) configured SL bandwidth part (BWP)).

The WTRU may receive configuration information indicating (e.g., being (pre) configured with) a WTRU collision detection processing time threshold (e.g., T _PSICH). The collision indication processing time threshold may correspond to a (e.g., minimum) period of time for the WTRU to receive and decode the collision indication (e.g., and perform an indicated operation, such as a resource reselection) (e.g., required). The time threshold may be expressed, for example, in terms of the number of SL slots. The value of the processing time threshold may be based on, for example, WTRU processing capabilities and/or SCS, such as SCS associated with SL BWP (e.g., a (pre) configured SL BWP).

In some examples, the RX WTRU may determine a collision detection trigger occasion (e.g., the most recent collision detection trigger occasion) for resources reserved in the SCI received from the TX WTRU, e.g., based on T _proc and/or T _PSICH. The RX WTRU may trigger collision detection near the reserved SL slot, e.g., to acquire as many conflicting SL resource reservations as possible. The conflicting SL resource reservation may be a reservation that may reserve partially or fully overlapping sub-channels in a SL slot (e.g., the same SL slot). The triggering of collision detection may occur, for example, early enough to allow collision detection and indication transmission at the RX WTRU and processing time of the indication reception and indication operation of the TX WTRU.

In some examples, the WTRU may receive (e.g., be (pre) configured with) an enable/disable indication (e.g., conflictDetEnabled) for collision detection. The TX WTRU may include ConflictDetEnabled indications, for example, in the SCI of the PSSCH/PSCCH transmission. For example, if (e.g., when) the indication for collision detection is set to "enabled," the RX WTRU may perform collision detection on the reserved resources in the SCI. For example, if (e.g., when) the indication for collision detection is set to "disabled," the RX WTRU may refrain from performing (e.g., not performing) collision detection on the resources reserved in the SCI.

In some examples, the WTRU may receive (e.g., be (pre) configured with) an enable/disable indication (e.g., conflictIndEnabled) for the collision indication. The TX WTRU may include ConflictIndEnabled indications, for example, in the SCI of the PSSCH/PSCCH transmission. For example, if (e.g., when) the indication for the collision indication is set to "enabled," the RX WTRU may transmit the collision indication to the TX WTRU for (e.g., specific to) the resources reserved in the SCI. For example, if (e.g., when) the indication for collision indication is set to "disabled," the RX WTRU may refrain from performing (e.g., not performing) a transmission of collision indication to the TX WTRU reserving resources in the SCI.

ConflictDetEnabled and ConflictIndEnabled SCI indicate that WTRUs with limited or no reception capabilities (e.g., VRU devices without RX Hardware (HW)) may be supported. The WTRU (e.g., with limited or no reception capability) may perform random resource selection without sensing. The resulting SL transmissions may experience enhanced collisions. SL resource detection of randomly selected resources may improve transmission reliability. For example, due to HW limitations, the indication transmission may be inhibited from being executed (e.g., not executed).

In some examples, the WTRU may receive configuration information indicating (e.g., being (pre) configured with) a SL collision detection RSRP threshold (e.g., RSRP _conflict). The WTRU may determine that a collision is detected in the reserved resources, e.g., based on the (pre) configured) RSRP _conflict. For example, the RX WTRU may determine that a collision is detected if (e.g., when) the measured RSRP is above an indicated (e.g., pre-configured) SL collision detection RSRP threshold (e.g., RSRP _conflict). The value of the (pre) configured) SL collision detection RSRP threshold may depend on, for example, the priority indicated in SCI of resources reserved (e.g., the same) by different WTRUs.

In an example, the WTRU may receive configuration information indicating (e.g., being (pre) configured with) PSICH and/or PSFCH resources for inter-WTRU coordination and/or collision detection. The resource configuration information may be associated with (e.g., dedicated to) the SL resource pool. If PSCIH and/or PSFCH are configured in the resource pool, the WTRU may determine that inter-WTRU coordination and/or collision detection and indication may be enabled, for example, and the WTRU may perform inter-WTRU coordination and/or collision detection for SL transmissions (e.g., using the resources of the resource pool).

The RX WTRU may determine a collision detection occasion for resources reserved in the received SCI. In some examples, the RX WTRU may determine a physical side link indication channel (PSICH) transmission occasion based on, for example, a PSICH resource configuration of a resource pool, which may be located (e.g., at least) T _PSICH before (e.g., each) reserved SL slot of the reserved resources. The (pre-) configured) periodicity of the PSICH transmission occasions may be e.g. one per SL slot, one per two SL slots, one per four SL slots, etc. The WTRU may determine a time offset (e.g., T _offset) between the determined PSICH transmission opportunity and the reserved SL slot. For example, if (e.g., when) the PSICH transmission period is one per SL slot, then T _offset may be set equal to T _PSICH. For example, if (e.g., when) the PSICH transmission periodicity is one per two SL slots (e.g., according to the index of the reserved SL slot), then T _offset may be set equal to T _PSICH or T _PSICH +1 (e.g., as shown in the examples of fig. 2A-2D).

The RX WTRU may determine a (e.g., most recent) collision detection trigger occasion corresponding to the reserved resource, which may be located (e.g., at least) T _proc before the determined PSICH transmission occasion. The RX WTRU may (e.g., therefore) determine that a collision detection trigger occasion for reserving resources may occur (e.g., at least) (T _proc+T_offset) before the resources for collision detection.

Fig. 2A-2D illustrate examples of WTRU collision detection trigger occasions for retransmitting resource reservations.

The RX WTRU may determine a collision detection occasion to reserve resources for retransmission in the received SCI. The RX WTRU may determine one or more (e.g., the most recent) collision detection opportunities for resources reserved for retransmission in SCI received in SL slot y ₀, e.g., based on one or more of the following: conflict detection processing time (e.g., T _proc); collision indicates a transmission processing time (e.g., T _PSICH); one or more PSICH transmission occasions in a resource pool (e.g., (pre) configured); the number of resources reserved in the received SCI; for resources reserved in SL slots (e.g., y ₁＝y₀+T₁), time resource allocation indicated in the received SCI (e.g., T ₁); and/or for resources reserved in SL slots (e.g., y ₂＝y₀+T₂), time resource allocations indicated in the received SCI (e.g., T ₂).

The RX WTRU may determine one or more (e.g., most recent) collision detection opportunities for resources reserved for retransmission in SCI received in SL slot y ₀, e.g., as described in one or more of the following examples. The (e.g., most recent) collision detection occasion may represent a time instance after which the WTRU may refrain from triggering (e.g., not triggering) collision detection. The WTRU may trigger inter-WTRU coordination and/or collision detection in a collision detection occasion (e.g., SL slot (SL slot n)), e.g., before the determined (e.g., most recent) collision detection occasion. The trigger may be based on a (pre) configured) condition (e.g., as discussed herein).

In some examples, retransmission resources may be reserved (e.g., one) in SL slot y ₁＝y₀+T₁. As shown in the example in fig. 2A, T ₁>＝T_proc+T_offset. The RX WTRU may determine the most recent collision detection occasion in SL slot y _trig＝y₀+T₁-T_proc-T_offset, which corresponds to the reserved retransmission resource in SL slot y ₁ (e.g., if T ₁>＝T_proc+T_offset). For example, if T ₁<T_proc+T_offset, the RX WTRU may refrain from performing (e.g., not performing) collision detection on the reserved resources (e.g., determining).

In some examples, multiple (e.g., two) retransmission resources may be reserved in SL slots y ₁＝y₀+T₁ and y ₂＝y₀+T₂. As shown in the example in fig. 2B, T ₁>＝T_proc+T_{offset_1}, and T ₂-T₁>＝T_proc+T_{offset_2}. The RX WTRU may determine multiple (e.g., the last two) collision detection opportunities. The RX WTRU may determine that the collision detection occasion will correspond to the resource reserved in SL slot y ₁, for example, in SL slot y _{trig_1}＝y₀+T₁-T_proc-T_{offset_1}. The RX WTRU may determine that the collision detection occasion will correspond to the resource reserved in SL slot y ₂, for example, in SL slot y _{trig_2}＝y₀+T₁-T_proc-T_{offset_2}.

In some examples, multiple (e.g., two) retransmission resources may be reserved in SL slots y ₁＝y₀+T₁ and y ₂＝y₀+T₂. As shown in the example in fig. 2C, T ₁<T_proc+T_offset, and T ₂-T₁>＝T_proc+T_offset. The RX WTRU may determine the most recent collision detection occasion in SL slot y _trig＝y₀+T₂-T_proc-T_{offset_2}, which corresponds to the reserved retransmission resource in SL slot y ₂. The RX WTRU may refrain from performing (e.g., not performing) collision detection on the reserved retransmission resources in SL slot y ₁.

In some examples, multiple (e.g., two) retransmission resources may be reserved in SL slots y ₁＝y₀+T₁ and y ₂＝y₀+T₂. As shown in the example in fig. 2D, T ₁>＝T_proc+T_offset, and T ₂-T₁<T_proc+T_offset. The RX WTRU may determine the (e.g., most recent) collision detection occasion in SL slot y _trig＝y₀+T₁-T_proc-T_{offset_1}, which corresponds to the reserved retransmission resources in SL slots y ₁ and y ₂. The RX WTRU may perform collision detection on the reserved retransmission resources in SL slot y ₁ and SL slot y ₂.

In some examples, multiple (e.g., two) retransmission resources may be reserved in SL slots y ₁＝y₀+T₁ and y ₂＝y₀+T₂. For example, if T ₁<T_proc+T_offset and T ₂-T₁<T_proc+T_offset, the RX WTRU may refrain from performing (e.g., not performing) collision detection on the reserved resources.

The RX WTRU may determine a collision detection occasion to reserve resources for initial transmission and/or retransmission in the received SCI. For example, if (e.g., when) the value of the resource reservation period (e.g., P _{rsvp_TX}) indicated in the SCI is greater than zero, the RX WTRU may receive a periodic resource reservation in the SCI in SL slot y ₀. The (e.g., same) subchannels reserved in SL slots y ₀、y₁ and y ₂ (e.g., if retransmission resources are reserved) may be reserved (e.g., periodically) in SL slots y ₀+n*P_{rsvp_TX}、y₁+n*P_{rsvp_TX} and y ₂+n*P_{rsvp_TX}. The value of N may be 1 to N. N may be, for example, an indicated (e.g., configured by higher layers (in advance)) resource reselection value.

The RX WTRU may determine one or more (e.g., most recent) collision detection opportunities for resources reserved for (e.g., initial) transmission and/or retransmission in SCI received in SL slot y ₀, for example, based on one or more of: conflict detection processing time (e.g., T _proc); collision indicates a transmission processing time (e.g., T _PSICH); one or more PSICH transmission occasions (pre) configured in the resource pool; the number of resources reserved in the received SCI; for resources reserved in SL slot y ₁＝y₀+T₁, the time slot indicated in the received SCI (e.g., T ₁); for resources reserved in SL slot y ₂＝y₀+T₂, the time slot indicated in the received SCI (e.g., T ₂); and/or a resource reservation period P _{rsvp_TX}.

The RX WTRU may determine (e.g., for a reservation period, such as each reservation period) one or more (e.g., the most recent) collision detection opportunities for resources reserved for retransmission in SCI received in SL slot y ₀. One or more of the following may be applied.

An initial resource may be reserved (e.g., one) in SL time slot y ₀+n*P_{rsvp_TX} (e.g., periodically), where P _{rsvp_TX}>＝T_proc+T_offset. For example, if initial resources are reserved (e.g., periodically) in SL slot y ₀+n*P_{rsvp_TX} and P _{rsvp_TX}>＝T_proc+T_offset, the RX WTRU may determine the (e.g., most recent) collision detection occasion in SL slot y _{trig_n}＝y₀+n*P_{rsvp_TX}-T_proc-T_offset, which corresponds to the reserved initial transmission of the (e.g., new) SL TB in SL slot y ₀+n*P_{rsvp_TX}.

An initial resource, e.g., P _{rsvp_TX}<T_proc+T_offset, may be reserved (e.g., periodically) (e.g., one) in SL slot y ₀+n*P_{rsvp_TX}. For example, if initial resources are reserved (e.g., periodically) in SL slot y ₀+n*P_{rsvp_TX} and P _{rsvp_TX}<T_proc+T_offset, the RX WTRU may refrain from performing (e.g., not performing) collision detection on the reserved resources.

The initial transmission (e.g., one) and retransmission resources (y ₁＝y₀+T₁) may be reserved in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX}, e.g., where P _{rsvp_TX}>＝T_proc+T_{offset_1} and T ₁>＝T_proc+T_{offset_2}. For example, if (e.g., one) initial transmission and (e.g., one) retransmission resource (y ₁＝y₀+T₁) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX} and P _{rsvp_TX}>＝T_proc+T_{offset_1} are simultaneously T ₁>＝T_proc+T_{offset_2}, the RX WTRU may determine multiple (e.g., the last two) collision detection opportunities. The RX WTRU may determine a plurality (e.g., two) of the most recent collision detection opportunities, wherein one of the most recent collision detection opportunities includes a collision detection opportunity in SL slot y _{trig_n_1}＝y₀+n*P_{rsvp_TX}-T_proc-T_{offset_1}, corresponding to the resources reserved in SL slot y ₀+n*P_{rsvp_TX}. The RX WTRU may determine a plurality (e.g., two) of the most recent collision detection opportunities, wherein one of the most recent collision detection opportunities includes a collision detection opportunity in SL slot y _{trig_n_2}＝y₀+n*P_{rsvp_TX}+T₁-T_proc-T_{offset_2}, corresponding to the resources reserved in SL slot y ₁+n*P_{rsvp_TX}.

The initial transmission (e.g., one) and retransmission resources (y ₁＝y₀+T₁) may be reserved in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX}, e.g., where P _{rsvp_TX}<T_proc+T_{offset_1} and T ₁>＝T_proc+T_{offset_2}. For example, if (e.g., one) initial transmission and (e.g., one) retransmission resource (y ₁＝y₀+T₁) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX} and P _{rsvp_TX}<T_proc+T_{offset_1} is simultaneous in T ₁>＝T_proc+T_{offset_2}, the RX WTRU may determine a (e.g., most recent) collision detection occasion in SL slot y _trig＝y₀+n*P_{rsvp_TX}+T₁-T_proc-T_{offset_2}, corresponding to the reserved retransmission resource in SL slot y ₁+n*P_{rsvp_TX}. The RX WTRU may refrain from performing (e.g., not performing) collision detection on the reserved retransmission resources in SL slot y ₀+n*P_{rsvp_TX}.

The initial transmission (e.g., one) and retransmission resources (y ₁＝y₀+T₁) may be reserved in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX}, e.g., where P _{rsvp_TX}>＝T_proc+T_{offset_1} and T ₁<T_proc+T_{offset_2}. For example, if (e.g., one) initial transmission and (e.g., one) retransmission resource (y ₁＝y₀+T₁) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX} and P _{rsvp_TX}>＝T_proc+T_{offset_1} is simultaneous T ₁<T_proc+T_{offset_2}, the RX WTRU may determine the most recent collision detection occasion in SL slot y _trig＝y₀+n*P_{rsvp_TX}-T_proc-T_{offset_1}, corresponding to the reserved retransmission resource in SL slots y ₀+n*P_{rsvp_TX} and y ₁+n*P_{rsvp_TX}. The RX WTRU may perform collision detection (e.g., at one collision detection occasion) on the reserved retransmission resources in both SL slots.

The initial transmission (e.g., one) and retransmission resources (y ₁＝y₀+T₁) may be reserved in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX}, e.g., where P _{rsvp_TX}<T_proc+T_{offset_1} and T ₁<T_proc+T_{offset_2}. For example, if (e.g., one) initial transmission and (e.g., one) retransmission resource (y ₁＝y₀+T₁) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX} and y ₁＝y₁+n*P_{rsvp_TX} and P _{rsvp_TX}<T_proc+T_{offset_1} and T ₁<T_proc+T_{offset_2}, the RX WTRU may (e.g., determine) refrain from performing (e.g., not performing) collision detection on (e.g., any) reserved resources.

For example, the RX WTRU may refrain from considering (e.g., not considering) the time gap (T ₁) between initial transmission and retransmission if/when determining the (e.g., most recent) collision detection trigger occasion for such semi-persistent resource reservation (e.g., if (e.g., one) initial transmission and (e.g., one) retransmission resource (y ₁＝y₀+T₁) reservation (e.g., periodically) in SL slot y ₀＝y₀+n*P_{rsvp_TX}). For example, if P _{rsvp_TX}>＝T_proc+T_offset, the RX WTRU may determine the (e.g., most recent) collision detection occasion in SL slot y _{trig_n}＝y₀+n*P_{rsvp_TX}-T_proc-T_offset, which may correspond to the (e.g., two) resources reserved for the initial transmission of the (e.g., new) SL TB in SL slot y ₀+n*P_{rsvp_TX} and its retransmission in SL slot y ₁＝y₁+n*P_{rsvp_TX}.

The RX WTRU may determine a number (e.g., three) of the most recent collision detection occasions if (e.g., one) initial transmission and a number (e.g., two) retransmission resources (y ₁＝y₀+T₁ and y ₂＝y₀+T₂) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX},y₁＝y₁+n*P_{rsvp_TX} and y ₂＝y₂+n*P_{rsvp_TX}, and if P _{rsvp_TX}>＝T_proc+T_{offset_1} and T ₁>＝T_proc+T_{offset_2} and T ₂>＝T_proc+T_{offset_3}. In an example, the RX WTRU may determine the nearest collision detection occasion in SL slot y _{trig_n_1}＝y₀+n*P_{rsvp_TX}-T_proc-T_{offset_1} (e.g., one of the multiple) that may correspond to the resource reserved in SL slot y ₀+n*P_{rsvp_TX}. The RX WTRU may determine the nearest collision detection occasion in SL slot y _{trig_n_2}＝y₀+n*P_{rsvp_TX}+T₁-T_proc-T_{offset_2} (e.g., one of the multiple) that may correspond to the resource reserved in SL slot y ₁+n*P_{rsvp_TX}. The RX WTRU may determine the nearest collision detection occasion in SL slot y _{trig_n_3}＝y₀+n*P_{rsvp_TX}+T₂-T_proc-T_{offset_3} (e.g., one of the multiple) corresponding to the resource reserved in SL slot y ₁+n*P_{rsvp_TX}.

If (e.g., one) initial transmission and two retransmission resources (y ₁＝y₀+T₁ and y ₂＝y₀+T₂) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX},y₁＝y₁+n*P_{rsvp_TX} and y ₂＝y₂+n*P_{rsvp_TX}, and if P _{rsvp_TX}<T_proc+T_{offset_1} and T ₁<T_proc+T_{offset_2} and T ₂<T_proc+T_{offset_3}, the RX WTRU may determine to refrain from performing (e.g., not performing) collision detection on (e.g., either of) the reserved resources.

For example, if (e.g., when) a most recent collision detection trigger occasion for (e.g., such) (e.g., semi-persistent) resource reservation is determined (e.g., if (e.g., one) initial transmission and two retransmission resources (y ₁＝y₀+T₁ and y ₂＝y₀+T₂) are reserved (e.g., periodically) in SL slots y ₀＝y₀+n*P_{rsvp_TX},y₁＝y₁+n*P_{rsvp_TX} and y ₂＝y₂+n*P_{rsvp_TX}), the RX WTRU may refrain from considering (e.g., not considering) the time gap (e.g., T1, T2) between the initial transmission and the retransmission. If P _{rsvp_TX}>＝T_proc+T_offset (e.g., and reserving initial transmission and two retransmission resources as described herein), the RX WTRU may determine the latest collision detection occasion in SL slot y _{trig_n}＝y₀+n*P_{rsvp_TX}-T_proc–T_offset, which may correspond to the initial transmission of the (e.g., new) SL TB in SL slot y ₀+n*P_{rsvp_TX} and its multiple (e.g., three) resources reserved for retransmission in SL slots y ₁＝y₁+n*P_{rsvp_TX} and y ₂＝y₂+n*P_{rsvp_TX}.

The RX WTRU may trigger collision detection (e.g., determine) at a collision detection trigger occasion (e.g., determined). The RX WTRU may trigger collision detection in the SL slot (e.g., slot n), e.g., prior to the determined (e.g., most recent) collision detection trigger occasion (e.g., corresponding to the resources reserved in the SCI received in the SL slot y ₀). The determination to trigger collision detection may be based on, for example, one or more of the following: a subset of WTRU source and/or destination IDs; SL priority threshold (e.g., prio _thre); SL CBR threshold (e.g., CBR _thre); an enable/disable indication (e.g., conflictDetEnabled) for inter-WTRU coordination and/or collision detection; PSICH/PSFCH resource configuration information; SL RSRP of PSCCH carrying SCI in SL slot y_0; using the region ID indicated in the SCI received in SL slot y_0 and the Minimum Communication Requirement (MCR) (e.g., the distance between the RX WTRU and TX WTRU specific to the SL TB to be transmitted in the reserved resource); SL power save status indication (e.g., indicated in SCI received in SL slot y_0); a resource allocation scheme (e.g., indicated in SCI received in SL slot y_0); WTRU type indication (e.g., indicated in SCI received in SL slot y_0); decoding status and/or HARQ feedback status of PSSCH transmission in reserved resources in SCI received in SL slot y_0; and/or a (e.g., explicit) request from the TX WTRU for inter-WTRU coordination and/or collision detection.

In some examples, the RX WTRU may receive configuration information indicating (e.g., configured (in advance) by higher layers) a subset of WTRU source/destination IDs, e.g., for SL resource collision and indication. The RX WTRU may receive the resource reservation in SCI of PSSCH/PSCCH transmission. For example, if (e.g., when) the WTRU source and/or destination IDs indicated in the received SCI are within the indicated (e.g., (pre) configured) subset, the RX WTRU may trigger collision detection (e.g., determine).

SL in some examples, the RX WTRU may receive configuration information indicating (e.g., being (pre) configured with) a SL priority threshold (e.g., prio _thre) in the SL resource pool. The RX WTRU may receive the resource reservation in SCI of PSSCH/PSCCH transmission. For example, the RX WTRU may trigger collision detection (e.g., determine) if (e.g., when) the priority indicated in the received SCI is above a (pre) configured SL priority threshold.

The WTRU may receive configuration information indicating (e.g., being (pre) configured with) a SL CBR threshold (e.g., CBR _thre) in the SL resource pool. The RX WTRU may receive the resource reservation in SCI of PSSCH/PSCCH transmission. For example, the RX WTRU may trigger collision detection (e.g., determine) if (e.g., when) the measured CBR at the resource collision detection trigger occasion is below a (pre) configured SL CBR threshold.

In some examples, the WTRU may receive configuration information indicating (e.g., being (pre) configured with) an enable/disable indication (e.g., conflictDetEnabled) for collision detection. The RX WTRU may receive the resource reservation in SCI of PSSCH/PSCCH transmission. For example, if (e.g., when) the indication of ConflictDetEnabled in the received SCI is set to "enabled," the RX WTRU may trigger collision detection (e.g., determine).

The RX WTRU may receive (e.g., be (pre) configured with) configuration information for a resource pool (e.g., including PSICH/PSFCH resources). The presence of PSICH/PSFCH resources in a (pre) configured resource pool may indicate inter-WTRU coordination and/or may enable collision detection for transmissions using the resources of the resource pool. For example, if (e.g., when) the reserved resources are included in a resource pool (e.g., with a PSICH/PSFCH resource configuration), the RX WTRU may determine to trigger collision detection of the reserved resources.

For example, if (e.g., when) the measured SL RSRP of the PSCCH carrying the SCI of the reserved resource in SL slot y_0 exceeds a (pre) configured SL RSRP threshold, the RX WTRU may determine to trigger collision detection for the reserved resource. In an example, the WTRU may receive configuration information indicating (e.g., being (pre) configured with) a set of SL RSRP thresholds, and (e.g., each of) the SL RSRP thresholds (e.g., of the set of SL RSRP thresholds) may be associated with a SL priority. The RX WTRU may determine a SL RSRP threshold corresponding to the L1 priority value indicated in the SCI reserving resources for collision detection.

In an example, the RX WTRU may determine to trigger collision detection on reserved resources, for example, if (e.g., when) the TX-RX distance does not exceed the MCR indicated in the SCI of the reserved resources for collision detection. In an example, the WTRU source and/or destination ID indicated in the SCI transmitted by the TX WTRU may be associated with the V2X service and/or SL application subscribed to by the RX WTRU. The RX WTRU may determine a geographic location of the TX WTRU indicated by the received TX WTRU's zone ID (e.g., as a center of a geographic area), and may calculate a TX-RX distance based on the TX WTRU and the RX WTRU's geographic location, for example.

For example, if (e.g., when) the SL power saving state indication (e.g., included in the SCI of the reserved resource) indicates a reduced power consumption state, the RX WTRU may (e.g., determine) to refrain from triggering (e.g., not triggering) collision detection of the reserved resource. For example, the TX WTRU may be in a power saving state in which sensing and/or reception is limited or disabled. The TX WTRU may disable resource reselection in a power saving state, for example, to reduce power consumption. The TX WTRU may indicate this power saving state in the resource reservation included in the SCI and the RX WTRU may (e.g., determine) to refrain from triggering (e.g., not triggering) collision detection for such SL transmissions.

In an example, the RX WTRU may refrain from triggering (e.g., not triggering) collision detection of the reserved resources, for example, if (e.g., when) a random and/or partial resource selection scheme is indicated in the SCI of the reserved resources. In an example, the TX WTRU may select resources (e.g., randomly) for SL transmission, e.g., without performing sensing. This may be due to power saving and/or HW limitations, such as TX-only WTRUs without RX HW. In an example, the TX WTRU may perform partial sensing for SL transmissions, and the RX WTRU may (e.g., be (pre) configured) refrain from triggering (e.g., not triggering) collision detection for such transmissions.

In an example, the RX WTRU may refrain (e.g., determine) from (e.g., not to trigger) collision detection on the reserved resources, for example, if the (e.g., pre-configured) WTRU type is indicated in the SCI of the reserved resources. Such (pre-configured) WTRU types may include Vulnerable Road Users (VRUs), low power wearable devices, and/or WTRUs with limited HW capabilities. The RX WTRU may (e.g., be (pre) configured) refrain from triggering (e.g., not triggering) collision detection of SL transmissions performed by this type of WTRU.

The RX WTRU may trigger (e.g., determine) collision detection on reserved resources, e.g., based on the decoding status and/or HARQ feedback status (e.g., if/when HARQ is enabled) of PSSCH transmissions received in reserved resources in SCI received in SL slot y ₀. The RX WTRU may receive configuration information indicating (e.g., being (pre) configured with) a threshold for decoding CRC errors and/or HARQ NACKs. For example, the RX WTRU may trigger collision detection (e.g., determine) if (e.g., when) the decoding CRC error and/or HARQ NACK corresponding to the PSSCH transmission received in the reserved resources in the SCI received in SL slot y ₀ exceeds a (pre) configured threshold. In an example, the RX WTRU may receive (e.g., semi-persistent) PSSCH transmissions in reserved resources in SL slots y ₀+n*P_{rsvp_TX}、y₁+n*P_{rsvp_TX} and y ₂+n*P_{rsvp_TX}, e.g., where N may be 1 to N, and N may be a resource reselection value (e.g., indicated by higher layers and/or (pre) configured).

In an example, the RX WTRU may trigger inter-WTRU coordination and/or collision detection, e.g., if (e.g., when) the RX WTRU receives (e.g., explicit) a request from the TX WTRU. The (e.g., explicit) request may include a WTRU source and/or destination ID associated with the V2X service and/or SL application (e.g., subscribed to by the RX WTRU). The RX WTRU may trigger inter-WTRU coordination of the received resource reservation and/or collision detection (e.g., based on receiving the request), e.g., including the WTRU source and/or destination ID indicated in the (e.g., explicit) request.

Fig. 3 illustrates an example of an RX WTRU performing collision detection and collision indication.

The RX WTRU may detect the collision based on the trigger (e.g., at the time of the trigger) (e.g., determining that the condition is met). The RX WTRU may determine the collision, for example, due to a detected overlapping resource reservation (e.g., as shown in fig. 3). The RX WTRU may determine that collision detection in SL slot n has been triggered (e.g., the condition has been met). The RX WTRU may process the decoded SCI and/or RSRP measurements in the determined set of subchannels and/or SL slots (e.g., based on the trigger of collision detection in SL slot n), e.g., to determine whether a collision is detected in reserved resources for collision detection. SL collision detection may include, for example, one or more of the following (e.g., performed by the RX WTRU): determining one or more collision detection parameters; performing SCI decoding; determining an overlap of reserved resources; determining collision detection based on the overlapping reservations; and/or determine the type of conflict detected.

The RX WTRU may determine one or more collision detection parameters. One or more (e.g., collision detection) parameters may be indicated in the received (e.g., configured by higher layers) (in advance) configuration information, such as one or more of the following parameters: SL collision detection RSRP threshold (e.g., RSRP _conflict); a collision detection window (e.g., T _window, such as 1000 SL slots); demodulation reference signals (DM-RS) for measurement (e.g., PSCCH DM-RS or PSCCH DM-RS); and/or a set of resource reservation periods (e.g., P' _{rsvp_TX}, such as 10 SL slots, 20 SL slots, etc.). One or more (e.g., collision detection) parameters may be indicated in the SCI of the reserved resources in the SL slot (e.g., SL slot y) for collision detection (e.g., from the reserved TX WTRU), such as one or more of the following parameters: l1 priority (e.g., prio _{TX_1}) indicated in the received SCI and/or associated with WTRU source and/or destination IDs (e.g., as a result of V2X services and/or applications supported by the RX WTRU) configured (in advance) for the RX WTRU; the number of reserved subchannels (e.g., L _subCH); and/or a resource reservation period (e.g., P _{rsvp_TX_1}).

The RX WTRU may perform SCI decoding in (e.g., all) subchannels of the resource pool in (e.g., each) SL slot within the collision detection window (e.g., from SL slot (n-T _window) to SL slot (n)).

The RX WTRU may determine the overlap of reserved resources, for example, if (e.g., when) the SCI decoded in the SL slot includes a reservation of a subchannel that partially or completely overlaps with L _subCH in slot (y). The SL time slots may be (e.g., any) SL time slots, for example, ranging from SL time slot (y-32) to SL time slot (y). The SL slot may include SCI transmission reserving resources for retransmission, which may overlap with reserved resources in the SL slot (y). The SL slot may be, for example, a (e.g., any) SL slot that is q x P' _{rsvp_TX} slots preceding the SL slot (y). In some examples, P' _{rsvp_TX} may be (e.g., any) (pre) configured resource reservation period, and/or q may be a non-zero positive integer. The SL slot may include SCI transmission reserving periodic resources, which may overlap with reserved resources in the SL slot (y).

The RX WTRU may determine collision detection, e.g., based on the overlap reservation decoded in the SCI and/or by RSRP measured by (pre-configured) DM-RSs (e.g., PSCCH or PSSCH DM-RSs) associated with the decoded SCI. For example, the RX WTRU may determine that a collision is detected if (e.g., when) the measured RSRP is above an indicated (e.g., pre-configured) SL collision detection RSRP threshold (e.g., RSRP _conflict). RSRP _conflict may be calculated, for example, based on L1 priorities (e.g., prio _{TX_1} and prio _{TX_2}) indicated in multiple (e.g., two) SCIs reserving overlapping resources.

The RX WTRU may determine the type of collision detected (e.g., one-time collision or periodic collision) based on, for example, one or more of the following: a resource reservation period (e.g., P _{rsvp_TX_1}) that may be indicated in the SCI (e.g., indicated by the reserved TX WTRU); and/or a resource reservation period (e.g., P _{rsvp_TX_2}) that may be indicated in the SCI (e.g., including overlapping resource reservations), e.g., by the conflicting TX WTRUs.

In some examples, P _{rsvp_TX_2} = 0, and/or P _{rsvp_TX_1} = 0. The RX WTRU may determine that the detected collision may be the result of an aperiodic transmission (e.g., and may occur once), where the detected collision may be a one-time collision (e.g., if P _{rsvp_TX_2} =0 and/or P _{rsvp_TX_1} =0). In some examples, P _{rsvp_TX_1} and P _{rsvp_TX_2} >0 are P _{rsvp_TX_1}＝m*P_{rsvp_TX_2} or P _{rsvp_TX_2}＝m*P_{rsvp_TX_1} simultaneously (e.g., where m is a non-zero positive integer). For example, if P _{rsvp_TX_1} and P _{rsvp_TX_2} >0 and P _{rsvp_TX_1}＝m*P_{rsvp_TX_2} or P _{rsvp_TX_2}＝m*P_{rsvp_TX_1}, the RX WTRU may determine that the detected collision may be the result of periodic transmissions (e.g., and may occur periodically), where the detected collision may be a periodic collision. Periodic collisions may result in persistent collisions between periodic transmissions.

For example, if (e.g., when) there are multiple resources (e.g., as shown in the example in fig. 2D), the RX WTRU may perform collision detection (e.g., as described herein) on the reserved resources (e.g., each) that may be included in the trigger collision detection.

For example, the RX WTRU may determine the same slot collision due to overlapping resource reservations. In an example, the RX WTRU may perform collision detection on resources reserved in the same slot (e.g., SL slot y ₀) in which SCI of the reserved resources may be received. The collision detection may be based on parameters indicated in the (e.g., each) decoded resource reservation received in SL slot y ₀. These parameters may include WTRU source and/or destination IDs, and/or number of reserved subchannels (L _subCH).

For example, the RX WTRU may determine that a collision is detected in SL slot y ₀ if (e.g., when) the following two occur: SCI decoded from multiple (e.g., two or more) PSCCHs in SL slots y ₀ indicates overlapping reservations on (e.g., at least) subchannels reserved for PSSCH transmissions in the same SL slot; and the WTRU source and/or destination IDs indicated in the overlapping resource reservation are associated with V2X services and/or SL applications to which the RX WTRU subscribes.

In an example, for example, the RX WTRU may determine that a collision is detected in SL slot y ₀ if (e.g., when) the following two occur: SCI decoded from multiple (e.g., two or more) PSCCHs in SL time slots y ₀ indicate the same WTRU source and/or destination ID specific to the multicast transmission; and the WTRU source and/or destination IDs indicated in the reservation are associated with V2X services and/or SL applications to which the RX WTRU subscribes.

The RX WTRU may determine a collision due to a previously received resource reservation. In an example, the WTRU may determine collision detection based on a previously received semi-persistent resource reservation and a resource reservation that triggers collision detection (e.g., based on a trigger of collision detection in SL slot n). The WTRU may perform one or more of the following in association with burst detection.

The RX WTRU may determine collision detection parameters, such as one or more of the following collision detection parameters: parameters for collision detection (e.g., from a reserved TX WTRU) indicated in SCI of reserved resources in a SL slot (e.g., SL slot y); and/or parameters indicated in SCI previously received from another TX WTRU in a semi-persistent resource reservation.

Parameters indicated in SCI of reserved resources in a SL slot (e.g., SL slot y) for collision detection (e.g., from a reserved TX WTRU) may include the number of reserved subchannels (L _{subCH_1}), the resource reservation period (P _{rsvp_TX_1}), and/or the TCI status (TCI ₁) of transmissions in reserved resources.

The RX WTRU may determine collision detection parameters, such as parameters indicated in SCI previously received from another TX WTRU in a semi-persistent resource reservation. The WTRU source and/or destination IDs indicated in such SCI may be among the IDs (e.g., the (pre) configuration) to be received by the RX WTRU. Parameters indicated in SCI received previously (e.g., from another TX WTRU in a semi-persistent resource reservation) may include the number of reserved subchannels (L _{subCH_2}), reserved SL slots, resource reservation periods (e.g., P _{rsvp_TX_2}) and P _{rsvp_TX_2} >0, and/or TCI status of transmissions in reserved resources (TCI ₂).

For example, if (e.g., when) there is a previously received resource reservation in slot (y) (e.g., a SL slot reserved by another TX WTRU may overlap with slot (y)) and one or more of the following conditions exist, the RX WTRU may determine that a collision is detected: the reserved sub-channels overlap (e.g., partially or fully) with L _subCH in slot (y); or the receive spatial domain filters associated with TCI ₁ and TCI ₂ may be spatially orthogonal (e.g., an RX WTRU may not be able to receive both using one RX beam).

The RX WTRU may determine the type of collision detected (e.g., a one-time or periodic collision), for example, based on a first resource reservation period (e.g., P _{rsvp_TX_1}) indicated by the reserved TX WTRU in the SCI and/or a second resource reservation period (e.g., P _{rsvp_TX_2}) indicated by the conflicting TX WTRU in the SCI that includes overlapping resource reservations. In an example, for example, if (e.g., when) P _{rsvp_TX_1} and P _{rsvp_TX_1}＝m*P_{rsvp_TX_2} or P _{rsvp_TX_2}＝m*P_{rsvp_TX_1} (e.g., where m is a non-zero positive integer), the RX WTRU may determine that the detected collision is the result of a periodic transmission and may occur periodically, and the detected collision may be a periodic collision. Periodic collisions may result in persistent collisions between periodic transmissions.

In an example, the RX WTRU may determine that the detected collision is a periodic collision, for example, if (e.g., when) m is below a (pre) configured threshold. For example, if (e.g., when) m is equal to one, the reserved resources may overlap in each reservation period. For example, if (e.g., when) m is equal to two, the reserved resources may overlap every two reservation periods.

The RX WTRU may determine the collision based on (e.g., due to) its scheduled SL or UL transmissions. In an example, the RX WTRU may determine that a collision is detected if (e.g., when) one of the following transmissions by the RX WTRU was previously reserved in slot (y) and the WTRU source and/or destination ID indicated in SCI reserving resources in slot (y) is associated with the V2X service and/or SL application subscribed to by the RX WTRU: SL transmissions scheduled in slot (y) by the network (e.g., gNB) based on the SL mode 1 resource allocation, SL transmissions reserved in slot (y) by the RX WTRU based on the SL mode 2 resource allocation, and/or UL transmissions scheduled in slot (y) by the network (e.g., gNB). The RX WTRU may refrain from (e.g., cannot) receiving in the time slot of its transmission (e.g., due to half-duplex limitations of SL operation).

The WTRU may transmit a resource collision indication (e.g., in a PSICH transmission, e.g., as shown in fig. 3). The RX WTRU may determine a TX WTRU and/or corresponding information for PSICH transmission. For example, if (e.g., when) collision detection is triggered for a collision detection trigger occasion and a collision is detected (e.g., as shown in fig. 3), the RX WTRU may determine that the TX WTRU is transmitting a PSICH transmission. The collision detection trigger occasion may include a time window in which the RX WTRU has enough time to detect a collision and, for example, send a collision indication to the TX WTRU. Resources in which a collision is detected at a corresponding collision detection trigger occasion may be referred to as resources in which a collision exists. The determination (e.g., of the TX WTRU to which the PSICH transmission is to be transmitted) may be based on, for example, one or more of: one or more L1 priorities (e.g., prio _{TX_1} and prio _{TX_2}) indicated in SCI reserved overlapping resources; an enable/disable indication (e.g., conflictDetEnabled) for inter-WTRU coordination and/or collision detection; an enable/disable indication and/or a collision indication (e.g., conflictIndEnabled) for inter-WTRU coordination; SL CBR threshold (e.g., CBR _thre); decoding results of PSSCH transmission associated with SCI of reserved resource; the type of conflict detected (e.g., one-time or periodic); WTRU source and/or destination IDs indicated in SCI reserved for resources where there is a collision; a SL power saving indication indicated in SCI reserved for resources where there is a collision; WTRU type indication indicated in SCI reserved for resources where there is a collision; a resource allocation scheme indicated in SCI reserving resources in which collision exists; SL RSRP carrying PSCCH transmissions reserving SCI with conflicting resources; and/or the distance between the RX WTRU and the TX WTRU reserving the resources in which the collision exists.

The RX WTRU may determine the TX WTRU and/or corresponding information for the PSICH transmission based on, for example, an L1 priority indication in the SCI (e.g., carried in the PSCCH transmission, e.g., as shown in fig. 3). The RX WTRU may determine to which TX WTRU to transmit the PSICH transmission, e.g., based on the L1 priority (e.g., prio _{TX_1}) indicated in the SCI of the received reserved resources and/or based on the L1 priority (e.g., prio _{TX_2}) indicated in the decoded SCI including the overlapping resource reservations. The RX WTRU may transmit a PSICH transmission (e.g., as shown in fig. 3) to a TX WTRU with a lower priority (e.g., lower L1 priority). The RX WTRU may transmit a PSICH transmission (e.g., based on a trigger that the RX WTRU detects the presence of a collision) to a TX WTRU (e.g., a conflicting TX WTRU as shown in the example of fig. 4B), where the conflicting TX WTRU is requesting to reserve resources that overlap with resources already reserved (e.g., reserving resources that the TX WTRU has reserved as shown in the example of fig. 4B). For example, if (e.g., when) prio _{TX_1}<prio_{TX_2} (e.g., prio _{TX_1} in fig. 4B indicating a higher priority, e.g., a lower value of prio may indicate a higher priority), the RX WTRU may transmit a PSICH transmission to the conflicting TX WTRU. The RX WTRU may transmit a PSICH transmission to a TX WTRU (e.g., a reserved TX WTRU, as shown in the example in fig. 4A) that has transmitted a resource reservation that triggers the RX WTRU to monitor for a collision (e.g., based on the RX WTRU detecting a trigger that a collision exists). For example, if (e.g., when) prio _{TX_1}>prio_{TX_2} (e.g., prio _{TX_1} in fig. 4A indicating a lower priority, e.g., a higher value of prio may indicate a lower priority), the RX WTRU may transmit a PSICH transmission to the reserved TX WTRU. The RX WTRU may detect a trigger that a collision exists upon receiving a resource reservation from the colliding TX WTRU. The RX WTRU may detect the trigger of the existence of the collision (e.g., as shown in fig. 4A and 4B) at an offset time from the time the resource reservation from the colliding TX WTRU is received, e.g., by a collision detection processing time associated with the RX WTRU. The PSICH transmission may include an indication to reselect different resources. For example, if (e.g., when) the measured CBR at the resource collision detection trigger occasion is above a (e.g., pre-configured) SL CBR threshold, the RX WTRU may determine to refrain from transmitting (e.g., not transmit) the PSICH transmission (e.g., with equal L1 priority). For example, the RX WTRU may randomly select the TX WTRU (e.g., with equal L1 priority) to perform PSICH transmission. For example, if (e.g., when) the collision detection includes multiple (e.g., two) reserved resources and/or a collision is detected in each of the multiple resources, the RX WTRU may transmit simultaneous PSICH transmissions to the reserved and colliding TX WTRUs at the same PSICH transmission occasion. The RX WTRU may perform TX power sharing between simultaneous PSICH transmissions.

Fig. 4A to 4C illustrate examples of PSICH transmission.

The RX WTRU may determine the TX WTRU and/or corresponding information for PSICH transmission, e.g., based on ConflictDetEnabled and/or ConflictIndEnabled indications in the SCI. The RX WTRU may (e.g., determine) refrain from transmitting (e.g., not transmitting) a PSICH transmission to the TX WTRU with an indication of ConflictDetEnabled and/or ConflictIndEnabled set to "disabled" in the SCI. For example, the TX WTRU may refrain from performing (e.g., not (pre) configured for) collision detection and indication (e.g., due to HW limitations). The TX WTRU may indicate "disable" ConflictDetEnabled in the SCI reserved for SL resources. The resources reserved by the TX WTRU may not be subject to collision detection or indication.

In some examples, the TX WTRU may indicate "enable" ConflictDetEnabled and "disable" ConflictIndEnabled (e.g., a VRU device that performs random resource selection without receiving capability). For example, if (e.g., when) the RX WTRU detects a collision in resources reserved by the TX WTRU (e.g., VRU device), the RX WTRU may transmit a PSICH transmission to the colliding TX WTRU. The RX WTRU may indicate to the conflicting TX WTRU (e.g., in a PSICH transmission) that the resource reselection, for example, may be performed so that the reserved TX WTRU may continue transmitting in the reserved resources without collision.

The RX WTRU may determine the TX WTRU and/or corresponding information for PSICH transmission based on, for example, a resource reservation period in the SCI. The RX WTRU may determine to which TX WTRU (e.g., of the plurality of TX WTRUs) to transmit the PSICH transmission, e.g., based on the resource reservation period (e.g., P _{rsvp_TX_2}) indicated in the SCI of the conflicting TX WTRU and/or the reserved TX WTRU (e.g., P _{rsvp_TX_1}). For example, if (e.g., when) P _{rsvp_TX_2} =0 and P _{rsvp_TX_1} >0 and/or if (e.g., when) P _{rsvp_TX_1} =0 and P _{rsvp_TX_2} >0, the RX WTRU may determine that the detected collision is a one-time collision between an aperiodic transmission and a periodic transmission. The RX WTRU may transmit a PSICH transmission (e.g., determine) to the TX WTRU with a (e.g., periodic) resource reservation (e.g., a reservation with P _{rsvp_TX} > 0). The RX WTRU may indicate (e.g., determine) TX WTRU reselection resources, e.g., such that (e.g., aperiodic) transmissions may be performed without collision. In some examples, for example, if (e.g., when) prio _{TX_2} > priority threshold, the RX WTRU may receive configuration information indicating (e.g., being (pre) configured with) the priority threshold and/or may (e.g., determine) to transmit a PSICH transmission to a reserved TX WTRU with periodic resource reservation (e.g., where P _{rsvp_TX_2} > 0). For example, if the L1 priority of the transmissions of the conflicting WTRU is above a (e.g., pre-) configured threshold (e.g., priority threshold), the RX WTRU may (e.g., thus) instruct the reserved TX WTRU to reselect periodic resources to avoid collisions with the conflicting WTRU's aperiodic transmissions.

For example, if (e.g., when) P _{rsvp_TX_2} =0 and P _{rsvp_TX_1} >0, the RX WTRU may transmit a PSICH transmission to indicate a one-time or periodic resource reselection, e.g., based on the type of collision detected (e.g., determined). For example, if (e.g., when) a one-time collision is detected and prio _{TX_1}>prio_{TX_2}, the RX WTRU may indicate one-time resource reselection to the reserved TX WTRU in the PSICH transmission (e.g., as shown by example in fig. 5A). Resource reselection may (e.g., therefore) be limited to a (e.g., one) period of periodic resource reservation. For example, if (e.g., when) a periodic collision is detected and prio _{TX_1}>prio_{TX_2}, the RX WTRU may indicate periodic resource reselection to the reserved TX WTRU in PSCIH transmission (e.g., as shown in the example of fig. 5B). The resource reselection may be performed for one or more (e.g., all) cycles of the resource reservation.

Fig. 4A illustrates an example of PSICH transmission for one-time resource reselection. Fig. 5B illustrates an example of PSICH transmission for periodic resource reselection.

The RX WTRU may determine the TX WTRU and/or corresponding information for PSICH transmission based on, for example, a decoding status of the PSSCH transmission associated with the SCI of the reserved resource. The RX WTRU may determine to which TX WTRU to transmit PSICH transmissions based on, for example, a decoding status of PSSCH transmissions associated with SCIs from the reserved TX WTRUs. For example, if (e.g., when) the decoding status is a CRC check (e.g., the PSSCH transmission is decoded correctly), the RX WTRU may transmit the PSICH transmission to the reserved TX WTRU to cancel the retransmission (e.g., as shown in the example of fig. 4C). Cancellation may allow transmissions of the conflicting TX WTRU to be performed without a conflict.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a WTRU source and/or destination ID indicated in the SCI reserving resources in which a collision exists. In an example, the RX WTRU may determine which TX WTRU sent the collision indication transmission (e.g., in a PSICH transmission), e.g., based on the WTRU source and/or destination ID indicated in the SCI reserving the resources for which the collision exists. In an example, the RX WTRU may determine to transmit a PSICH transmission to the TX WTRU, the SCI of which indicates a WTRU source and/or destination ID associated with the V2X service and/or SL application to which the RX WTRU subscribes. The RX WTRU may instruct the TX WTRU to perform resource reselection in a PSICH transmission.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a power saving state indicated in the SCI of the reserved resources. For example, if (e.g., when) a SL power saving state indication included in the SCI from the TX WTRU reserving resources in which there is a collision is used to indicate a reduced power consumption state, the WTRU may determine to refrain from sending (e.g., not sending) a collision indication transmission to the TX WTRU (e.g., in a PSICH transmission). For example, a TX WTRU in such a reduced power consumption state may refrain from performing (e.g., not performing) sensing and/or SL reception, and thus may refrain from receiving (e.g., not being able to receive) and/or operate in accordance with the collision indication transmission. The RX WTRU may transmit a collision indication to (e.g., other) TX WTRUs reserving resources for which a collision exists, and indicate a resource reselection.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a resource allocation scheme indicated in the SCI of the reserved resources. In an example, the RX WTRU may determine to refrain from sending (e.g., not sending) a collision indication transmission (e.g., in a PSICH transmission) to the TX WTRU, for example, if (e.g., when) the TX WTRU applies random source selection and/or (e.g., partially) based on sensed resource selection. The resource selection scheme may be indicated in the SCI from the TX WTRU reserving the resources in which the collision exists. The RX WTRU may transmit a collision indication to (e.g., other) TX WTRUs reserving resources for which a collision exists, and indicate a resource reselection.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, the WTRU type indicated in the SCI of the reserved resources. In an example, an RX WTRU may determine to refrain from sending (e.g., not sending) a collision indication transmission (e.g., in a PSICH transmission) to a TX WTRU, which may be a weak road user (VRU), a low power wearable device, and/or a WTRU with limited HW capabilities, for example. Such WTRU type indication may be included in the SCI from the TX WTRU reserving resources where there is a conflict. The RX WTRU may transmit a collision indication to (e.g., other) TX WTRUs reserving resources for which a collision exists, and indicate a resource reselection.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a SL RSRP carrying a PSCCH reserving the SCI for which resources are in conflict. RX WTRI may determine which TX WTRU sent the collision indication transmission (e.g., in the PSICH transmission) based on, for example, the measured RSRP of the PSCCH transmission carrying SCI reserved for resources where collisions exist. In an example, the RX WTRU may transmit a PSICH transmission to the TX WTRU with the highest measured RSRP value. In an example, the RX WTRU may transmit a PSICH transmission to the TX WTRU with the highest measured RSRP value above the (e.g., pre-configured) RSRP threshold.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a distance between the RX WTRU and the TX WTRU reserving resources in which a collision exists. The RX WTRU may determine which TX WTRU sends the collision indication transmission (e.g., in a PSICH transmission) based on, for example, a calculated TX-RX distance between the RX WTRU and each TX WTRU reserving resources for which a collision exists. The RX WTRU may calculate the TX-RX distance based on, for example, a region ID indicated in the SCI from the TX WTRU. For example, if (e.g., when) the TX-RX distance is within the MCR indicated in the SCI from the TX WTRU, the RX WTRU may transmit a PSICH transmission to the TX WTRU. In an example, the RX WTRU may transmit PSICH transmissions to the TX WTRU having the smallest TX-RX distance and within the MCR indicated in the SCI from the TX WTRU.

The RX WTRU may determine the TX WTRU and corresponding information for PSICH transmission based on, for example, a type of collision detected in the resources where the collision exists. For example, if (e.g., when) the RX WTRU detects the same slot collision (e.g., as described herein with respect to the RX WTRU determining the same slot collision due to overlapping resource reservations), the RX WTRU may determine to send a PSICH transmission or PSFCH transmission to the TX WTRU. The PSICH transmission may include an indication of retransmission of the TB transmitted by the TX WTRU in the resources where the collision exists.

For example, if (e.g., when) the RX WTRU detects a collision due to a previously received resource reservation (e.g., as described herein with respect to the RX WTRU determining a collision due to a previously received resource reservation), the RX WTRU may determine to send a collision indication transmission (e.g., a PSICH transmission). The RX WTRU may determine to send a collision indication transmission (e.g., a PSICH transmission) based on, for example, the priority of the TB associated with the previously received resource reservation and the priority indicated in the SCI of the reserved resource (e.g., if (e.g., when) the RX WTRU detects a collision due to the previously received resource reservation). The RX WTRU may send a collision indication transmission to the TX WTRU with the highest priority indicated in the SCI reserving the resources with the collision.

For example, if (e.g., when) the RX WTRU detects a collision due to its scheduled SL or UL transmission (e.g., as described herein with respect to the RX WTRU determining a collision due to its scheduled SL or UL transmission), the RX WTRU may determine to send a collision indication transmission (e.g., a PSICH transmission) to the TX WTRU. For example, if (e.g., when) the priority of the TB for the SL or UL transmission is higher than the priority indicated in the SCI of the reserved resource, the RX WTRU may determine to send a collision indication transmission (e.g., a PSICH transmission) to the TX WTRU (e.g., if (e.g., when) the RX WTRU detects a collision due to its scheduled SL or UL transmission). The RX WTRU may indicate a resource reselection in the PSICH transmission. For example, if (e.g., when) the priority of the TB of the SL or UL transmission is lower than the priority indicated in the SCI of the reserved resource, the RX WTRU may determine to refrain from sending (e.g., not sending) the PSICH transmission and discard the SL or UL transmission and receive the SL TB in the reserved resource (e.g., as indicated in the SCI from the TX WTRU). The higher priority may correspond to a smaller value in the priority bit field of the SCI.

The RX WTRU may determine PSICH transport format and/or resources. The WTRU may receive an indication (e.g., configured (in advance) by higher layers, for example) configuration information for collision indication transmission, such as one or more of the following: PSICH transport format; PSFCH transmission formats; and/or PSICH transmission resource configuration.

The WTRU may receive configuration information indicating (e.g., being (pre) configured with) a PSICH transport format. In some examples, the PSICH transport format may be based on a sequence, such as a Zadoff Chu (ZC) sequence. The WTRU may generate a PSICH transmission sequence (e.g., ZC sequence cyclic shift value) and/or transmit SL collision detection and indication information in the selected PSICH transmission sequence. The PSICH transport format may include one or more (e.g., multiple) bit fields. The (e.g., each) bit field may comprise (e.g., be (pre) configured with) a set of code points. The WTRU may use the code point value in the PSICH transmission bit field to indicate the relevant information.

In some examples, the PSICH transmission may indicate information applicable to the resource reserved in the received SCI, e.g., if (e.g., when) a SL resource collision is detected in the resource. The PSICH transmission may indicate, for example, one or more of: an indication of retransmission of the SL TB transmitted in the PSSCH transmission associated with the received SCI; an indication to cancel a retransmission of the SL TB scheduled in the resource reserved in the received SCI; an indication of a one-time resource reselection (e.g., a reselection of a single resource reserved in the received SCI), such as an indication of an initial transmission of a (e.g., new) SL TB associated with the same WTRU source and/or destination ID as indicated in the received SCI and/or a retransmission of the SL TB transmitted in a PSSCH associated with the received SCI; and/or a request for periodic reselection (e.g., a reselection of periodically reserved resources in the received SCI), such as a request for initial transmission and retransmission of a (e.g., new) SL TB associated with the same WTRU source and/or destination ID as indicated in the received SCI.

In some examples, the WTRU may PSFCH the transmission format include SL resource collision and/or indication information (e.g., along with HARQ feedback information) of the resources reserved in the received SCI (e.g., if/when HARQ is enabled for the SL TB). PSFCH transport formats may indicate, for example, one or more of the following: HARQ ACK of SL TB transmitted in PSSCH transmission associated with the received SCI; an indication of HARQ NACK for the SL TB transmitted in the PSSCH transmission associated with the received SCI and/or HARQ retransmission in resources reserved in the received SCI; and/or an indication of HARQ NACK for the SL TB transmitted in the PSSCH transmission associated with the received SCI and/or HARQ retransmission with resource reselection (e.g., HARQ retransmission in a different resource than reserved in the received SCI due to detected collision).

For example, if (e.g., when) the RX WTRU detects a collision in the resources reserved for HARQ retransmissions, the RX WTRU may indicate a HARQ NACK and a resource reselection in PSFCH transmissions.

The WTRU may receive configuration information indicating (e.g., being (pre) configured with) PSICH resources. The (e.g., each) resource may include, for example, a PSICH transmission occasion, a PSICH frequency resource, and/or a PSICH sequence. In some examples, the PSICH transmission occasion may be a SL slot. For example, the number of periodic SL slots in the (pre) configured) resource pool may be indicated as PSICH transmission occasions. The WTRU may perform PSICH transmission (e.g., within a PSICH transmission occasion) at one or more (e.g., pre-configured) PSICH symbols indicated (e.g., where no PSSCH/PSCCH transmission may be performed). For example, collision detection and indication may be disabled in the resource pool if (e.g., when) the PSICH transmission occasion is not indicated (e.g., (pre) configured) in the resource pool.

In some examples, the PSICH transmission may be based on (e.g., a single) Physical Resource Block (PRB), e.g., for a sequence-based PSICH transport format. The number of (e.g., (pre) configured) PRBs may be indicated in a resource pool for PSICH transmission. A set of (pre) orthogonal sequences (e.g., ZC sequences with different cyclic shifts) may be indicated (e.g., pre-configured). Multiple PSICH transmissions may be code domain multiplexed within a PSICH transmission opportunity (e.g., one). The PSICH resources may (e.g., thus) be identified with indexes based on PRBs and/or sequences used in PRBs.

The RX WTRU may determine resources for PSICH transmission to the determined TX WTRU in the determined PSICH transmission occasion, e.g., based on one or more of: a WTRU source/destination ID of the determined TX WTRU (e.g., WTRU _ID); an Index (e.g., index _slot) of the SL slot of the SCI receiving the reserved resource; index (e.g., index _slot) of the SL slot of the determined PSICH transmission occasion; a PSCCH subchannel reserved by the determined TX WTRU; and/or a PSSCH subchannel reserved by the determined TX WTRU.

In some examples, the RX WTRU may determine an index of the psch resources corresponding to the reserved resources (e.g., as WTRU _ID+Index_slot)MOD(N_{PSICH_resource}).N_{PSICH_resource} may be a sum of the psch resource sets determined within the PRBs of the psch subchannel and/or within the PRBs of the PSCCH subchannel reserved in the resource reservation for collision detection).

In some examples, the frequency resources of the PSICH transmission may be based on (e.g., a single) subchannel. The WTRU may determine the sub-channel for PSICH transmission based on mode 2 sensing, for example. The WTRU may perform sub-channel based PSICH transmission at (e.g., pre-configured) symbols within the PSICH transmission occasion.

The RX WTRU may determine PSICH transmit power and concurrent PSICH and PSFCH transmissions. The RX WTRU may receive configuration information indicating (e.g., configured (in advance) with) PSICH transmission power settings for (e.g., a single) PSICH transmission and concurrent PSICH and/or PSFCH transmissions: PSICH transmit power offset (P _{0_PSICH}); a path loss compensation factor (alpha); a downlink path loss (DLPL); SL path loss (SLDL); maximum total number of concurrent PSICH and/or PSFCH transmissions (N _max); SCS parameter set (u); (e.g., pre-configured) maximum SL power (P _{SL_MAX}); and/or if (e.g., when) the measured SL CBR exceeds a (pre) configured) CBR threshold (e.g., a (pre) configured) maximum SL power (P _{SL_MAX_CBR}).

The RX WTRU may select which path loss to apply to the PSICH transmit power setting (e.g., as described herein), e.g., based on the TX WTRU selected for the PSICH transmission. The RX WTRU may set the power (P _PSICH,single) of the PSICH transmission to one of: a downlink path loss (DLPL) for a single PSICH transmit power setting; and/or SL path loss for a single PSICH transmit power Setting (SLPL).

For example, if (e.g., when) a PSICH transmission is transmitted to a selected TX WTRU and the WTRU source and/or destination ID indicated in the SCI transmitted by the TX WTRU is not associated with the V2X service and/or SL application subscribed to by the RX WTRU, the RX WTRU may determine to use downlink pathloss (DLPL) for a single PSICH power setting. The RX WTRU may estimate DLPL, e.g., based on DLPL estimated (e.g., same) downlink RSs for PUSCH transmissions. The RX WTRU may set the single PSICH transmit power to one ：P_PSICH,single＝minimum(P_{SL_MAX},P_{0_PSICH}+10log10(2^u)+Alpha*DLPL)dBm;P_PSICH,single＝minimum(P_{SL_MAX_CBR},P_{0_PSICH}+10log10(2^u)+Alpha*DLPL)dBm,, e.g., if (e.g., when) the RX WTRU measures that the SL CBR is above a (e.g., (pre) configured) CBR threshold; or if the RX WTRU is out of NW coverage, the RX WTRU may apply a (pre) configured maximum SL power as follows: p _PSICH,single＝P_{SL_max} dBm and P _PSICH,single＝P_{SL_max_CBR} dBm (e.g., if/when the RX WTRU measures that the SL CBR is above a (pre) configured CBR threshold).

For example, if (e.g., when) a PSICH transmission is transmitted to a selected TX WTRU and the WTRU source and/or destination ID indicated in the SCI transmitted by the TX WTRU is associated with a V2X service and/or SL application subscribed to by the RX WTRU, the RX WTRU may determine to use SL pathloss (SLPL) for a single PSICH power setting. The RX WTRU may estimate DLPL, e.g., based on DLPL estimated (e.g., same) downlink RSs for PUSCH transmissions. The RX WTRU may set the single PSICH power to one of: p _PSICH,single＝minimum(P_{SL_MAX},P_{0_PSICH}+10log10(2^u) +alpha SLPL) dBm (e.g., where SLPL is based on the estimated SL path loss of the SL RS, e.g., SL CSI-RS, PSCCH DMRS, and/or PSSCH DMRS transmitted by the TX UE for PSICH transmission, or P _PSICH,single＝minimum(P_{SL_MAX_CBR},P_{0_PSICH}+10log10(2^u) +alpha SLPL) dBm (e.g., if/when the RX WTRU measures that the SL CBR is above a (pre) configured CBR threshold).

The PSICH transmission occasion may overlap (e.g., completely) with PSFCH transmission occasions. The RX WTRU may perform concurrent PSICH and PSFCH transmissions at the (e.g., same) symbol positions within the SL slot. The RX WTRU may receive configuration information indicating the (e.g., maximum) total number (N _max) transmitted (e.g., maximum) at (e.g., one) PSFCH and/or PSICH transmission occasions (e.g., being (pre) configured) PSICH and PSFCH. The RX WTRU may perform prioritization to determine which PSICH and/or PSFCH transmissions to perform. The prioritization performed may be associated with one or more of the following: maximum power available, determined/scheduled PSICH and/or PSFCH transmissions; the actual number of PSICH/PSFCH transmissions.

For example, if (e.g., when) the RX WTRU measures that the SL CBR is above a (e.g., pre-configured) threshold, the RX WTRU may determine the available maximum power as P _max or P _{max_CBR}.

For example, if (e.g., when) the number of determined and/or scheduled PSICH and/or PSFCH transmissions (e.g., N _scheduled) is less than or equal to a (pre) configured) maximum number (e.g., N _max) and the total power is less than or equal to the determined maximum power available, the RX WTRU may perform (e.g., all, such as N _scheduled) the determined and/or scheduled PSICH and/or PSFCH transmissions.

The RX WTRU may perform prioritization of the determined and/or scheduled (N _scheduled) PSICH/PSFCH transmissions and may determine the actual number of PSICH/PSFCH transmissions (N _actual), e.g., based on whether the determined/scheduled number of PSICH and/or PSFCH transmissions (N _scheduled) is less than or equal to a (pre) maximum number (N _max) and the total power is greater than the determined maximum available power, or whether the determined/scheduled number of PSICH and/or PSFCH transmissions (N _scheduled) is greater than a (pre) maximum number (N _max), e.g., configured). The RX WTRU may determine to perform an actual number (N _actual) of PSICH and/or PSFCH transmissions (e.g., which may be less than the scheduled number) in descending order of priority (e.g., in ascending order of priority indication values), e.g., based on SL priorities associated with the PSICH and/or PSFCH transmissions. The priority may be indicated in the SCI reserved for the resources corresponding to the PSICH transmission and the SCI associated with the PSSCH corresponding to the PSFCH transmission. The RX WTRU may determine such an actual number (N _actual) so that the sum of the determined PSICH and/or PSFCH transmit powers is less than or equal to the determined maximum available power. The RX WTRU may prioritize allocation of available power to PSICH/PSFCH transmissions with highest SL priority and discard the transmissions with lowest priority.

The RX WTRU may determine to perform a transmission of resource information to the TX WTRU. In an example, the RX WTRU may determine to transmit to the TX WTRU a (e.g., explicit) set of resources for which there is a collision. In an example, the RX WTRU may determine such conflicting resources, e.g., based on excluded resources that the RX WTRU determines by sensing, resources reserved in the previously received SCI (e.g., as described herein with respect to RX WTRU determining collisions due to previously received resource reservations), and resources scheduled/reserved for the RX WTRU's own transmissions (e.g., as described herein with respect to RX WTRU determining collisions due to its scheduled SL or UL transmissions).

In collision related information transmission, the RX WTRU may include a WTRU source and/or destination ID associated with the set of resources where the collision exists. The WTRU source and/or destination ID may be associated with a V2X service and/or SL application to which the RX WTRU subscribes. In an example, the WTRU source and/or destination ID may be indicated in a (e.g., explicit) request from the TX WTRU. In an example, the WTRU source and/or destination ID may be indicated in a resource reservation from the TX WTRU. The RX WTRU may include a source ID and a destination ID assigned to a unicast transmission (e.g., via higher layers, such as higher layer signaling), such as for a unicast transmission between the TX WTRU and the RX WTRU. The RX WTRU may include a destination ID assigned to the multicast and broadcast transmissions (e.g., via higher layers, such as higher layer signaling), e.g., for the multicast and broadcast transmissions.

The RX WTRU may determine (e.g., all) resources for which there is a collision, e.g., during a resource selection window. The RX WTRU may be indicated with such a resource selection window in a (e.g., explicit) request for a set of resources from the TX WTRU. In an example, the RX WTRU may receive configuration information indicating (e.g., being (pre) configured with) a resource selection window for determining resources for which there is a collision. The RX WTRU may include resource selection window information, for example, in a set of resources transmitted to the TX WTRU. The RX WTRU may include its region ID and/or the SL RSRP value measured on the TX WTRU's (e.g., explicit) request and/or the SCI of the previous resources in the reserved resource set.

The SCI decoded RX WTRU behavior may be based on the transmission of resource information to the TX WTRU. The RX WTRU may receive configuration information indicating (e.g., configured (in advance) with) PSCCH candidate resources, which may include a plurality of (e.g., consecutive) symbols starting from a second SL symbol in a SL slot of the SL resource pool and/or a plurality of PRBs starting from a lowest PRB of a subchannel of the SL resource pool.

The RX WTRU may receive configuration information indicating (e.g., being (pre) configured with) PSCCH decoding resource allocation. The allocation may be, for example, a plurality of subchannels of a resource pool, or a set of resource pools. The resource pool(s) may be located in (e.g., one) SL BWP or a different SL BWP. The SL BWP may be located in a different SL carrier. The RX WTRU may be (pre) configured with a set of such PSCCH decoding resource allocations, and (e.g., each such source allocation may be associated with one or more of: WTRU source and/or destination IDs associated with V2X services and/or SL applications (e.g., SL URLLC traffic) to which an RX WTRU subscribes; a power saving state (e.g., ACTIVE state, ON duration, INACTIVE state, OFF duration); or WTRU capabilities and/or types (e.g., redCap WTRU with small bandwidth).

The RX WTRU may determine a PSCCH decoding resource allocation based on the resources provided to the TX WTRU, for example. In an example, the PSCCH may determine to exclude PSCCH candidate resources from the PSCCH decoding resource allocation among the resources provided to the TX WTRU. For example, SL slots and subchannels included in the conflicting set of resources provided to the TX WTRU may be suppressed from being monitored (e.g., not monitored) by the RX WTRU for SCI decoding for transmissions from the TX WTRU.

In an example, the RX WTRU may send to the TX WTRU a set of (e.g., explicit) resources to apply (e.g., a set of resources for which there is no collision). The RX WTRU may prioritize SCI decoding of the SL slots and PSCCH candidate resources within the sub-channels included in the resources provided to the TX WTRU.

The RX WTRU may perform the exclusion and/or prioritization of PSCCH candidate resources during a resource selection window indicated in the set of resources sent to the TX WTRU (e.g., as described herein). The RX WTRU may provide such a set of resources to different TX WTRUs. The RX WTRU may determine which PSCCH candidate resources to exclude and/or prioritize based on, for example, semi-persistent resource reservations made in SL slots by each TX WTRU (e.g., each) in the SL slot.

The TX WTRU may determine that collision detection and indication may be performed for the resource reservation indicated in the SCI associated with the SL transmission being performed. The determination may be based on, for example, one or more of the following (e.g., as may be (pre) configured herein with respect to SL resource conflicts and indications): a subset of WTRU source IDs and/or destination IDs; SL priority threshold (e.g., prio _thre); an enable/disable indication (e.g., conflictDetEnabled) for inter-WTRU coordination and/or collision detection; and/or an enable/disable indication and/or a collision indication (e.g., conflictIndEnabled) for inter-WTRU coordination.

The TX WTRU may determine a corresponding PSICH transmission occasion for PSICH monitoring of (e.g., each) reserved resources, e.g., as described herein (e.g., RX WTRU determination of collision detection occasions for resources reserved in the received SCI). The TX WTRU and the RX WTRU may identify the same PSICH transmission occasion for the resources received in the received SCI. The TX WTRU may determine a corresponding PSICH transmission occasion for PSICH monitoring of (e.g., each) reserved resources, e.g., based on one or more of: conflict detection processing time (e.g., T _proc); and/or collision indicates a transmission processing time (e.g., T _PSICH).

For example, the TX WTRU may determine the PSICH resources based on one or more of the following (e.g., as described herein in terms of the RX WTRU determining the PSICH transport format and resources): WTRU source and/or destination IDs indicated in SCI of reserved resources; index (e.g., index _slot) of SL slots of SCI transmission; index (e.g., index _slot) of the SL slot of the determined PSICH transmission occasion; a PSCCH subchannel reserved by the determined TX WTRU; and/or a PSSCH subchannel reserved by the determined TX WTRU.

For example, if (e.g., when) the TX WTRU determines that collision detection and indication is enabled for the resource reservation transmitted in the SCI, the TX WTRU may monitor the PSICH transmission at the determined PSICH transmission occasion using the determined resources. The TX WTRU may disable preemption for the reserved resources (e.g., if preemption is (pre) configured in the resource pool) and/or may make initial transmissions and/or retransmissions in the reserved resources (e.g., if/when the TX WTRU does not receive a PSICH transmission). Preemption may detect a collision of reserved resources at the TX WTRU. The RX WTRU that detected the collision may not be enough to have the TX WTRU skip preemption and reduce processing.

The TX WTRU may disable preemption (e.g., if/when the TX WTRU receives a PSICH transmission) (e.g., if preemption is (pre) configured in the resource pool) and/or may perform one or more of the following (e.g., based on information indicated in the PSICH of the (each) reserved resource): stop retransmission (e.g., if/when PSICH indicates cancel of retransmission); performing reselection for non-periodic reserved resources and/or for (e.g., one) period of periodic reserved resources (e.g., if/when PSICH indicates a one-time resource collision and/or reselection); performing reselection of one or more (e.g., all) cycles of the periodic reserved resources (e.g., if/when the PSICH indicates periodic resource collision and/or reselection); and/or if/when the PSICH transmission indicates a retransmission.

The TX WTRU may determine that there are conflicting resources, for example, based on multiple received sets of resources that are in conflict. In an example, a TX WTRU may receive transmissions from multiple RX WTRUs, and each transmission may include a (e.g., explicit) set of resources. The TX WTRU may determine which set of resources to use for the SL transmission, e.g., based on information included in the set of resources from the RX WTRU and/or parameters of the SL transmission of the TX WTRU. The information included in the set of resources from the RX WTRU may include the WTRU source and/or destination IDs, the resource selection window, the region ID, and/or SL RSRP measured on the TX WTRU.

Parameters for the SL transmission of the TX WTRU may include the WTRU source and/or destination IDs associated with the TB to be transmitted, the MCR of the TB to be transmitted, and/or a resource selection window.

In an example, the TX WTRU may determine the set of application resources when one or more of the following conditions are met: the WTRU source and/or destination IDs indicated in the received set of resources are the same as the source and/or destination IDs associated with the SL TB to be transmitted; the TX-RX distance (e.g., calculated based on the area ID indicated in the received set of resources and the TX UE's own geographic location) is less than or equal to the MCR of the TB to be transmitted; the SL RSRP indicated in the received set of resources is higher than a (e.g., (pre) configured) SL RSRP threshold associated with the MCR of the TB to be transmitted; or the resource selection window indicated in the resource set overlaps with the resource selection window determined for the TB to be transmitted.

The TX WTRU may determine a set of resources (e.g., a plurality of received sets of resources) for the resource selection applied to the SL TB transmission accordingly. In an example, the TX WTRU may determine a combination of resources to include non-overlapping resources that the TX WTRU may select from each of the determined sets of received resources. The TX WTRU may select resources from an overlapping portion between the indicated resource selection window and the determined resource selection window of the TB to be transmitted.

Although the above features and elements are described in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements.

While the implementations described herein may consider 3GPP specific protocols, it should be appreciated that the implementations described herein are not limited to this scenario and may be applicable to other wireless systems. For example, while the solutions described herein consider LTE, LTE-a, new air interface (NR), or 5G specific protocols, it should be understood that the solutions described herein are not limited to this scenario, and are applicable to other wireless systems as well.

The processes described above may be implemented in computer programs, software and/or firmware incorporated in a computer readable medium for execution by a computer and/or processor. Examples of computer readable media include, but are not limited to, electronic signals (transmitted over a wired or wireless connection) and/or 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, but not limited to, internal hard disks and removable disks), magneto-optical media, and optical media (such as Compact Disks (CD) -ROM disks, and/or Digital Versatile Disks (DVD)). A processor associated with the software may be used to implement a radio frequency transceiver for the WTRU, the terminal, the base station, the RNC, and/or any host computer.

Claims (12)

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

a processor configured to:

Receiving configuration information indicating conflict detection processing time;

Receiving first side link control information (SCI) from a second WTRU, the first SCI including a first indication indicating a first resource, a first collision indication setting, and a first priority value;

determining a collision detection trigger occasion based at least on the collision detection processing time and the first resource;

Receiving a second SCI from a third WTRU during the collision detection trigger occasion, wherein the second SCI includes a second indication indicating a second resource, a second collision indication setting, and a second priority value;

Determining that there is a conflict associated with the first resource and the second resource; and

Transmitting a collision indication to the second WTRU based on:

the first conflict indication setting is enabled and the second conflict indication setting is disabled, or

The first conflict indication setting is enabled, the second conflict indication setting is enabled, and the first priority value is greater than the second priority value.

2. The first WTRU of claim 1, wherein the determination that there is a collision associated with the first resource and the second resource comprises a determination that a measurement associated with the second SCI is greater than a first threshold.

3. The first WTRU of claim 2 wherein the measurement associated with the second SCI is Reference Signal Received Power (RSRP).

4. The first WTRU of claim 1, wherein the processor is further configured to:

An indication of a collision indication processing time associated with the second WTRU is received, wherein the collision detection trigger occasion is further determined based on the collision indication processing time associated with the second WTRU.

5. The first WTRU of claim 1, wherein the collision detection processing time is a duration associated with collision detection and performance of a collision indication by the first WTRU.

6. The first WTRU of claim 1, wherein the determination that there is a collision associated with the first resource and the second resource is based on a determination that the first resource overlaps with the second resource.

7. A method, the method comprising:

Receiving configuration information indicating conflict detection processing time;

Receiving first side link control information (SCI) from a first WTRU, the first SCI including a first indication indicating a first resource, a first collision indication setting, and a first priority value;

determining a collision detection trigger occasion based at least on the collision detection processing time and the first resource;

Receiving a second SCI from a second WTRU during the collision detection trigger occasion, wherein the second SCI includes a second indication indicating a second resource, a second collision indication setting, and a second priority value;

Determining that there is a conflict associated with the first resource and the second resource; and

Transmitting a collision indication to the first WTRU based on:

the first conflict indication setting is enabled and the second conflict indication setting is disabled, or

The first conflict indication setting is enabled, the second conflict indication setting is enabled, and the first priority value is greater than the second priority value.

8. The method of claim 7, wherein the determination that there is a conflict associated with the first resource and the second resource comprises a determination that a measurement associated with the second SCI is greater than a first threshold.

9. The method of claim 8, wherein the measurement associated with the second SCI is a Reference Signal Received Power (RSRP).

10. The method of claim 7, the method further comprising:

an indication of a collision indication processing time associated with the first WTRU is received, wherein the collision detection trigger occasion is further determined based on the collision indication processing time associated with the first WTRU.

11. The method of claim 7, wherein the conflict detection processing time is a duration associated with execution of the conflict detection and conflict indication.

12. The method of claim 7, wherein the determination that there is a conflict associated with the first resource and the second resource is based on a determination that the first resource overlaps the second resource.