Method and apparatus for multi-carrier operation

Abstract

A wireless transmit / receive unit (WTRU) may determine to transmit or receive a first sidelink (SL) transmission using a first carrier using a first SL resource, and to transmit a second SL transmission using a second carrier using a second SL resource. The second SL resource may include an overlap period, where the second SL resource overlaps the first SL resource. If the overlap period is in the last one or more symbols of the second SL resource, the WTRU may transmit at least a portion of the second SL transmission using the second carrier using a first symbol set of the second SL resource in the overlap period, and not transmitting a portion of the second SL transmission using the second carrier using a second symbol set of the second SL resource in the overlap period. The WTRU may transmit or receive the first SL transmission in the overlap period.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 327,244, filed on April 4, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Both Long Term Evolution (LTE) V2X and New Radio (NR) V2X operations have been developed. V2X communications may include one or more of vehicle-to-vehicle (V2V) communications, vehicle-to-pedestrian (V2P) communications, vehicle-to-infrastructure (V2I) communications, and vehicle-to-network (V2N) communications. A V2X wireless transmit receive unit (WTRU) may participate in V2X communications.

[0004] The 3rd Generation Partnership Project (3GPP) specifications for LTE V2X technology support sidelink multi-carrier operation, which includes, for example: Packet Data Convergence Protocol (PDCP) duplication and transmission using carrier aggregation, and carrier selection and (re)selection based on measured channel busy rate (CBR). LTE multi-carrier transmission can be applied only to broadcast transmissions, and the functions can be specified in the Radio Resource Control (RRC) and Medium Access Control (MAC) layers.

[0005] LTE V2X may support one subcarrier spacing (SCS) of 15kHz for all carriers. For carrier aggregation, it may be expected that all aggregated carriers have the same synchronization configuration. Specifically, all carriers may have the same configured synchronization offset, synchronization periodicity, and number of synchronization opportunities per synchronization period. In addition, it may be expected that all aggregated carriers use the same synchronization source and are synchronized in both transmission and reception. For synchronous transmission, the WTRU may be pre-configured to transmit a side link synchronization signal (SLSS) in one predefined carrier or in all aggregated carriers configured for synchronous carrier aggregation.

[0006] On the other hand, in addition to supporting broadcast transmission, the 3GPP Release 16 (R16) NR specification for V2X may support multicast and unicast transmission. In order to support hybrid automatic repeat request (HARQ)-based transmission for multicast / unicast in sidelink communication, a feedback channel (e.g., a physical sidelink feedback channel (PSFCH)) may be designed to transmit HARQ feedback information (e.g., acknowledgement (ACK) / negative ACK (NACK)). Summary of the invention

[0007] Methods and apparatus for multi-carrier operation are provided herein. A wireless transmit / receive unit (WTRU) may determine to use a first carrier to send or receive a first side link (SL) transmission using a first SL resource, and to use a second carrier to send a second SL transmission using a second SL resource. In an example, the second SL resource may include an overlapping period. In addition, the second SL resource may overlap with the first SL resource in the overlapping period. If the overlapping period is in the last one or more symbols of the second SL resource, the WTRU may use the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, and not use the second carrier to send in the second symbol set of the second SL resource in the overlapping period. In addition, the WTRU may use the first carrier to send or receive the first SL transmission using the first SL resource in the overlapping period.

[0008] In an example, the first SL resource may include a first time resource, and the second SL resource may include a second time resource. In addition, the overlap period may be in one or more symbols of the second time resource that overlap in time with one or more symbols of the first time resource.

[0009] In addition, the first SL transmission may be a physical sidelink feedback channel (PSFCH) transmission. In addition, the first SL resource may be a PSFCH resource.

[0010] In addition, the second SL transmission may be a physical side link control channel (PSCCH) transmission. In addition, the second SL transmission may be a physical side link shared channel (PSSCH) transmission. In addition, the second SL transmission may be a combination of a PSCCH transmission and a PSSCH transmission. In addition, the second SL resource may be a PSCCH resource. In addition, the second SL resource may be a PSSCH resource. In addition, the second SL resource may be a combination of a PSCCH resource and a PSSCH resource.

[0011] In another example, using the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, and not using the second carrier for transmission in the second symbol set of the second SL resource in the overlapping period can be considered as perforation. Additionally or alternatively, using the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, and not using the second carrier for transmission in the second symbol set of the second SL resource in the overlapping period can be considered as rate matching.

[0012] Additionally or alternatively, if the overlap period is earlier than the last one or more symbols of the second SL resource, the WTRU may discard the transmission or reception of the first SL transmission or discard the transmission of the second SL transmission based on a comparison of the priority associated with the first SL resource with the priority associated with the second SL resource. In another example, the WTRU may send information about the first symbol set of the second SL resource and the second symbol set of the second SL resource to the receiving WTRU in a sidelink control information (SCI).

[0013] Furthermore, the WTRU may receive a SL grant for resources to send a second SL transmission using a second carrier. Additionally or alternatively, the WTRU may select resources to send a second SL transmission using a second carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements, and in which:

[0015] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0016] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system;

[0017] Figure 1C is an example of an embodiment in which Figure 1A a system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0018] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0019] Figure 2 are resource diagrams illustrating two typical example scenarios in which a WTRU performs resource prioritization;

[0020] Figure 3 is a resource diagram illustrating an example scenario of PSFCH carrier selection for simultaneous physical sidelink feedback channel (PSFCH) transmission;

[0021] Figure 4is a resource diagram illustrating an example procedure performed by a WTRU for prioritizing between PSFCH resources and Physical Sidelink Control Channel (PSCCH) or Physical Sidelink Shared Channel (PSSCH) resources;

[0022] Figure 5 is a flow chart illustrating an example of prioritization between PSFCH resources and PSCCH / PSSCH resources;

[0023] Figure 6 is a flow chart illustrating an example of prioritization between a first side link (SL) transmission and a second SL transmission;

[0024] Figure 7 is a resource diagram illustrating an example of a WTRU excluding PSCCH / PSSCH resources that overlap with a scheduled PSFCH transmission / reception;

[0025] Figure 8 is a resource diagram illustrating an example of a WTRU excluding PSCCH / PSSCH resources having associated PSFCH transmission / reception overlapping with scheduled / reserved resources from another carrier;

[0026] Fig. 9 is a resource diagram illustrating an example of a WTRU performing resource reselection when PSCCH / PSSCH resources and / or their associated PSFCH resources overlap with received resources in another carrier;

[0027] Fig.10 is a resource diagram illustrating an example scenario in which a WTRU determines whether to perform resource reselection or other prioritization method due to overlapping resources in different carriers; and

[0028] Fig.11 is a resource diagram illustrating an example scenario in which a WTRU determines a Side Link Synchronization Signal (SLSS) opportunity in which to send the SLSS. DETAILED DESCRIPTION

[0029] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0030] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0031] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0032] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0033] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0034] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. 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 ​​Uplink (UL) Packet Access (HSUPA).

[0035] 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) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0036] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0037] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0038] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0039] Figure 1A The base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.11) to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology (such as IEEE 802.15) to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As Figure 1A As shown, the base station 114 b may have a direct connection to the Internet 110. Therefore, the base station 114 b may not need to access the Internet 110 via the CN 106.

[0040] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the accompanying drawings, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0041] The CN 106 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. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0042] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0043] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0044] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0045] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station by an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, IR, UV or visible light signals. In another embodiment, the send / receive element 122 may be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0046] Although the transmit / receive element 122 Figure 1B 1 as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0047] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0048] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0049] 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 cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0050] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0051] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographic location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0052] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0053] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0054] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0055] 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, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0056] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although 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.

[0057] 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 serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0058] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0059] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0060] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 networks and / or wireless networks owned and / or operated by other service providers.

[0061] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0062] In a representative embodiment, the other network 112 may be a WLAN.

[0063] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Services originating from outside the BSS and directed to the STA may be reached by the AP and may be delivered to the STA. Services originating from the STA and directed to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Services between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit services to the AP, and the AP may deliver services to the destination STA. Services between STAs within the BSS may be considered and / or referred to as point-to-point services. Point-to-point services may be transmitted between the source STA and the destination STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0064] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of the BSS and may be used by the STA 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, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0065] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0066] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0067] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0068] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (which only supports a 1MHz operating mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0069] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South 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.

[0070] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0071] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0072] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0073] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0074] Each of the gNBs 180a, 180b, 180c may be associated with a specific 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 slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0075] Figure 1DThe illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned 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.

[0076] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0077] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0078] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0079] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0080] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU102a to 102d, base station 114a to 114b, evolved Node B 160a to 160c, MME 162, SGW 164, PGW 166, gNB180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0081] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0082] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0083] NR V2X can use broadcast, multicast and unicast transmission. In order to support hybrid automatic repeat request (HARQ) based transmission for multicast / unicast in sidelink communication, a feedback channel (such as a physical sidelink feedback channel (PSFCH)) can be designed to transmit HARQ feedback information (such as acknowledgement (ACK) / negative ACK (NACK)).

[0084] A pool of sidelink resources which may include a consecutive number of subchannels that are periodically repeated in the time domain. If a timeslot is configured for PSFCH transmission / reception, the PSFCH transmission may be placed at the end of the timeslot. If one or more PSFCH transmissions are configured in a resource, the WTRU may be configured with a PSFCH opportunity, for example, every 1, 2, or 4 timeslots.

[0085] A one-to-one mapping between a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH) and the PSFCH may be established in a resource pool so that a transmitting (Tx) WTRU of HARQ feedback may know the time, frequency, and code resources to transmit HARQ feedback for a given PSCCH / PSSCH reception, and a Tx WTRU of PSCCH / PSSCH may not need to perform blind detection of the HARQ feedback channel for the PSCCH / PSSCH resources it transmits. The mapping between the PSCCH / PSSCH and PSFCH resources may be configured such that the time gap between the two resources may be greater than or equal to K logical time slots in the resource pool. K may be configured or pre-configured between two and three time slots in the resource pool.

[0086] A WTRU may send multiple PSCCH / PSSCH transmissions to two different destinations with HARQ feedback enabled in a short period of time and may be expected to receive multiple PSFCHs in the same timeslot, where each PSFCH may be associated with a PSCCH / PSSCH transmission. A WTRU that receives multiple PSCCH / PSSCHs from the same or different transmitters WTRU in a short period of time may be expected to perform simultaneous PSFCH transmissions in the same timeslot.

[0087] Simultaneous transmission or reception of PSFCH transmissions may be supported in R16 NR V2X. Depending on some WTRU capabilities, the WTRU may perform simultaneous reception of a certain number of PSFCH transmissions and concurrent transmissions on a certain number of PSFCHs. Simultaneous PSFCH transmissions in one carrier may be carefully designed in R16 NR V2X to ensure reliability of HARQ feedback and reduce HARQ discards.

[0088] R16 NR V2X can support various subcarrier spacing (SCS) per carrier, which can vary from 15kHz to 120kHz. Regarding the synchronization configuration of each carrier, it is expected that all carriers can have the same synchronization periodicity (e.g., 160ms). However, the synchronization offset and the number of synchronization opportunities per synchronization period can vary depending on the SCS and the frequency of the carrier.

[0089] Research on carrier aggregation (CA) may be ongoing in the development of Release 18 (R18) Sidelink Evolution (SLE), with Release 15 LTE V2X CA being considered as a baseline. Modifications to wireless communications may include support for LTE sidelink CA features for NR as well as future technologies that may include synchronization of aggregated carriers, handling of limited capacity, and power control for simultaneous sidelink transmits (TX).

[0090] Unlike LTE V2X, modifications to wireless communications may include multi-carrier operation using carriers with the same or different SCS, different PSFCH and / or synchronization configurations. Sidelink communications may be established in different frequency bands, which may include full-duplex and half-duplex bands. For half-duplex bands, regardless of the number of transceiver (TRX) chains, the WTRU may not be expected to perform simultaneous transmission and reception in different carriers within the band.

[0091] Further modifications to wireless communications may include newly introduced channels in NR (e.g., PSFCH) and different transmit durations on various transmit channels (e.g., PSCCH / PSSCH, PSFCH) or a channel in a different carrier with a different SCS. Therefore, handling of limited WTRU capabilities may require appropriate resource allocation and resource prioritization schemes to reduce resource conflicts and discards. In addition, due to the operating band and the expected latency of packet delivery (e.g., the network may be configured for a larger SCS targeting services with lower latency requirements), it is also expected that modified wireless communications aggregate multiple carriers with various synchronization configurations. Therefore, it may be necessary to investigate synchronization procedures to address such different synchronization configurations.

[0092] Various solutions to the above problems are described herein. As used herein, the phrases "the WTRU may be configured with" something, "the WTRU may be configured with" something, and "the WTRU may be (pre-)configured with" something may be used equivalently or interchangeably with the phrase "the WTRU receives a configuration of something from another node (e.g., a gNB)" and still remain consistent with the examples and embodiments provided herein.

[0093] As described herein, the overlapping region between two resources in the time domain may include the actual overlapping symbols and the processing time used by the WTRU to transition to process the two resources, such as Tx / Rx switching time, automatic gain control (AGC) setup time, etc.

[0094] As used herein, the terms resource allocation, preemption, and resource reassessment are used interchangeably and may be used to describe a procedure for identifying whether a preselected resource or reserved resource is still available and / or identifying available resources for transmission by performing due to sensing and extracting sensing results. If not otherwise specified, resource allocation may mean, for example, initial resource allocation, preemption, and / or resource reassessment. In the description herein, the term "carrier" is used throughout. However, "carrier" may be used interchangeably with or equivalent to "BWP," "resource pool," or "radio access technology (RAT)," and is still consistent with the embodiments and examples provided herein. The terms "conflict" and "overlap" may be used interchangeably and are still consistent with the embodiments and examples provided herein.

[0095] As used herein, the term resource may refer to a single resource or may be considered to refer to multiple resources and still be consistent with the embodiments and examples provided herein. Likewise, the term resource may refer to multiple resources or may be considered to refer to a single resource and still be consistent with the embodiments and examples provided herein. In addition, the phrases "using resources" and "on resources" may be used interchangeably and still be consistent with the embodiments and examples provided herein. Similarly, "using carriers" and "on carriers" may be used interchangeably and still be consistent with the embodiments and examples provided herein.

[0096] In addition, as used herein, PSCCH / PSSCH transmission may refer to any one of PSCCH transmission, PSSCH transmission, or a combination of PSCCH transmission and PSSCH transmission, and these terms may be used interchangeably and remain consistent with the embodiments and examples provided herein. Similarly, PSCCH / PSSCH resources may refer to any one of PSCCH resources, PSSCH resources, or a combination of PSCCH resources and PSSCH resources, and these terms may be used interchangeably and remain consistent with the embodiments and examples provided herein. As used herein, resources may include any one of one or more time resources, one or more frequency resources, or a combination of one or more time resources and one or more frequency resources.

[0097] Methods for resource prioritization among multiple resources are described herein. In some solutions, a WTRU may prioritize transmit / receive resources.

[0098] In some solutions, the WTRU may determine whether to perform prioritization between multiple resources, which may be transmit and / or receive resources. In some examples, the WTRU may perform prioritization between multiple transmit resources due to one or any combination of the following conditions: the number of TX chains is less than the number of transmit carriers; the WTRU does not support the frequency band combination in the scheduled resources; the WTRU TX chain switching time of the WTRU does not meet the transmission in multiple carriers; the WTRU may not meet the RF requirements, for example due to power spectral density (PSD) imbalance; or the WTRU's transmit power exceeds the maximum allowed power.

[0099] In some examples, the WTRU may perform prioritization between transmit and receive resources due to one or any combination of the following conditions: the number of TRX chains is less than the number of transmit / receive carriers; the WTRU operates in a half-duplex band, which may not allow the WTRU to perform simultaneous transmit and receive; or the WTRU's Tx / Rx switching time does not meet the requirements for transmitting in one carrier and receiving in another carrier.

[0100] In some examples, the WTRU may perform prioritization between receive resources due to one or any combination of the following conditions: the number of receive (RX) chains is less than the number of receive carriers; the number of receive channels exceeds the WTRU capability; or the WTRU's RX switching / retuning time does not meet the requirements for receiving in multiple carriers.

[0101] Figure 2 200 is a resource diagram illustrating two typical example scenarios in which a WTRU performs resource prioritization. In the example shown in resource diagram 200, in two cases, the WTRU may perform prioritization between two resources used for transmission and / or reception in two carriers. In the first case, such as case 1, if the two transmission / reception resources overlap, the WTRU may perform prioritization. Specifically, if the PSCCH / PSSCH resource 210 overlaps with the PSFCH resource 220, the WTRU may perform resource prioritization. In the example, the overlapping resources may be time resources. In the second case, such as case 2, the two resources do not overlap. If the time gap between the end of the first resource (such as the PSCCH / PSSCH resource 250) and the beginning of the second resource (such as the PSFCH resource 260) is less than a determined threshold, the WTRU may perform resource prioritization. The determined threshold may be fixed, configured in a resource pool, pre-configured in a resource pool, and / or based on WTRU capabilities. For example, if the WTRU has one TRX chain, the determined threshold may be at least one symbol. However, if the WTRU has two TRX chains, the determined threshold may be much smaller than one symbol time since the WTRU may not need to perform Tx / Rx switching.

[0102] In some solutions, the WTRU may perform prioritization between transmit and / or receive resources. Specifically, the WTRU may determine to perform prioritization between two or more resources for transmit and / or receive resources. The WTRU may perform one or any combination of the following procedures for prioritization between resources.

[0103] In some examples, the WTRU may discard one or more resources. Discarding a transmit resource in this document may mean not performing a transmit in that resource. Discarding a receive resource in this document may mean not performing a receive in that resource. For example, the WTRU may determine to discard and / or not perform a transmit / receive in one or more non-prioritized resources. In addition, the WTRU may determine to perform a transmit / receive in one or more prioritized resources.

[0104] In some examples, the WTRU may reduce the transmit power of one or more resources. For example, the WTRU may be configured or pre-configured with one or more parameters to determine / calculate the transmit power of one or more resources. The WTRU may then determine to reduce the transmit power of one or more non-prioritized resources compared to the calculated / determined / configured transmit power. The WTRU may determine to maintain the same power of one or more prioritized transmit resources.

[0105] In some examples, the WTRU may increase the transmit power of one or more resources. For example, the WTRU may be configured or pre-configured with one or more parameters to determine / calculate the transmit power of one or more resources. The WTRU may then determine to increase the transmit power of one or more prioritized resources compared to the calculated / determined / configured transmit power.

[0106] In some examples, the transmitting WTRU may rate match or puncture a transmit resource. Puncturing and / or rate matching of symbols herein may be referred to as not transmitting or not receiving a signal in a symbol. The transmitting WTRU may then indicate its puncturing and / or rate matching to the receiving WTRU, for example, implicitly / explicitly in the sidelink control information (SCI). The method may be triggered to help the receiver WTRU decode the rate matching / puncturing transmission. For example, the WTRU may determine to rate match or puncture one or more symbols of one or more non-prioritized resources, which may overlap with the prioritized resources or may have a time gap less than a time gap threshold from the start of the prioritized resources, where the threshold may be fixed, configured in a resource pool, pre-configured in a resource pool and / or may be based on WTRU capabilities. In an example, the WTRU capability may be a Tx / Rx switching capability.

[0107] In some examples, the WTRU may only perform transmission. For example, the WTRU may need to perform prioritization between two sets of resources, one of which may be used for transmission and the other may be used for reception. The WTRU may then determine to prioritize the transmission resources. The WTRU may then determine to only perform transmission.

[0108] In some examples, the WTRU may only perform reception. For example, the WTRU may need to perform prioritization between two resource sets, where one set is available for transmission and the other set is available for reception. The WTRU may then determine to prioritize the reception resources. The WTRU may then determine to only perform reception. The WTRU may determine not to perform transmission in non-prioritized resources.

[0109] In some examples, the WTRU may perform resource reselection for one or more transmit resources. For example, the WTRU may need to prioritize between two resources, at least one of which may be used for transmission. If the transmit resources are de-prioritized, the WTRU may then determine to perform resource reselection for the transmit resources. For example, the WTRU may detect a potential conflict between a transmit resource (e.g., a PSCCH / PSSCH resource) in one carrier and a transmit / receive resource (e.g., a PSCCH / PSSCH resource) in another carrier, and the WTRU may trigger resource reselection for the transmit resource in the first carrier.

[0110] In some examples, the WTRU may trigger one or more inter-UE coordination (IUC) transmissions. For example, the WTRU may select / reserve or be scheduled for a transmit / receive resource in one carrier. The WTRU may receive an SCI from another WTRU that schedules / reserves transmit resources in another carrier, which transmit resources may overlap with the WTRU's selected / reserved / scheduled transmit / receive resources. The WTRU may then trigger the transmission of an IUC transmission to a peer WTRU, including, for example, a Scheme 2 conflict indication, to indicate a potential conflict. The WTRU may expect the receiver of the IUC to reselect resources to avoid resource conflicts.

[0111] In some solutions, the WTRU may determine which procedure to perform for resource prioritization.The WTRU may determine which procedure and / or which combination of procedures to perform for prioritization among multiple resources based on one or any combination of parameters as described in the following examples.

[0112] For example, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize among multiple resources based on the WTRU capabilities. For example, if the WTRU is configured to transmit and / or receive in multiple carriers, if the number of TRX chains is greater than the number of configured carriers, the WTRU may determine to perform transmission and / or reception in all carriers. If the transmission in all carriers exceeds the maximum limit, the WTRU may perform power reduction of one or more non-prioritized carriers. Otherwise, if the number of TRX chains is less than the number of configured carriers, the WTRU may determine to discard transmission / reception resources in one or more carriers.

[0113] For example, if the WTRU supports band combining, the WTRU may determine to transmit in multiple carriers. Then, if the transmission in all carriers exceeds the maximum limit, the WTRU may perform power reduction for one or more carriers. Otherwise, if the WTRU does not support band combining, the WTRU may determine to drop transmit / receive resources in one or more carriers.

[0114] For example, if the WTRU cannot transmit in both carriers simultaneously, the WTRU may perform puncturing / rate matching in the overlapping symbols between the two resources of the two carriers. Otherwise, if the WTRU determines to transmit in both carriers, the WTRU may reduce the transmit power of the non-prioritized resources.

[0115] In another example, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize among multiple resources based on the channel type used for transmission, reception, or both. In an example, the channel used may be one or any combination of PSFCH, PSCCH / PSSCH, or a physical sidelink broadcast channel (PSBCH).

[0116] For example, if the WTRU cannot transmit and / or receive in both resources simultaneously, the WTRU may determine whether to drop resources in one carrier or rate match / puncture the non-prioritized resources based on the channel type used for transmission, reception, or both. For example, if the two conflicting resources are PSCCH / PSSCH resources, the WTRU may determine to drop one resource. The WTRU may determine to rate match / puncture the PSCCH / PSSCH transmissions around the conflicting region between the PSFCH resources and the PSCCH / PSSCH resources.

[0117] In another example, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize among multiple resources based on the transmit duration of each resource, the receive duration of each resource, or both. For example, if the transmit / receive duration of a resource is less than a threshold, then the WTRU may perform discarding or power reduction if the resource is deprioritized. Otherwise, if the transmit / receive duration of a resource is greater than a threshold, then the WTRU may perform puncturing / rate matching, discarding, and / or power reduction if the resource is non-prioritized.

[0118] In another example, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize between multiple resources based on the overlap area between two resources. For example, in the case where the WTRU determines not to perform simultaneous transmission in two carriers, if the overlap duration between the two resources is greater than a threshold, the WTRU may determine to discard the resources in one carrier; otherwise, if the overlap duration between the two resources is less than the threshold, the WTRU may perform puncturing / rate matching on the non-prioritized resources.

[0119] For example, if the overlapping region belongs to the last time slot of one resource and the initial time slot of another resource, the WTRU may determine to perform rate matching / puncturing of one resource. If the overlapping region between two resources is in the middle of one resource, the WTRU may drop one of the resources, which may require the WTRU to resume transmission after the resources are punctured / rate matched.

[0120] In some examples, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize between multiple resources based on the number of resources / channels transmitted and / or received in one or more carriers. For example, if the number of discarded resources in one carrier is greater than a threshold, the WTRU may perform power reduction. Otherwise, if the number of discarded resources is less than a threshold, the WTRU may perform resource discarding. The threshold may be configured in the resource pool or pre-configured.

[0121] In some examples, the WTRU may determine which procedure and / or which combination of procedures to perform to prioritize between multiple resources based on the QoS (e.g., priority, reliability, and / or latency requirements) associated with the sending and / or receiving resources. For example, the WTRU may determine whether to perform discarding based on the QoS (e.g., priority) of the resource. Specifically, if the priority of the non-prioritized resource is less than a threshold, the WTRU may determine to discard the resource. Otherwise, if the priority of the non-prioritized resource is greater than the threshold, the WTRU may not perform resource discarding. Specifically, if the priority of the resource is greater than the threshold, the WTRU may perform power reduction and / or rate matching / puncturing of the resource.

[0122] In some examples, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize between multiple resources based on the synchronization state between the two carriers. For example, if the two carriers associated with the two resources are asynchronous, the WTRU may perform a drop of one resource. Otherwise, if the two carriers are synchronized, the WTRU may perform puncturing and / or rate matching of one resource.

[0123] In some examples, the WTRU may determine which procedure and / or combination of procedures to perform to prioritize between multiple resources based on the time gap between the prioritization event and the potential resource conflict time. For example, if the time gap between the prioritization event and the potential resource conflict time is greater than a threshold, the WTRU may perform resource reselection. The threshold may be configured or preconfigured in the resource pool. The threshold may be determined based on the WTRU capabilities. Otherwise, if the time gap between the prioritization event and the potential resource conflict time is less than the threshold, the WTRU may perform other prioritization procedures, such as discarding of one resource, reducing transmit power, and / or rate matching / puncturing.

[0124] Furthermore, in some examples, if the time gap between the prioritization event and the potential resource conflict is within a certain range (e.g., less than one threshold and greater than another threshold), the WTRU may perform puncturing / rate matching of a de-prioritized resource (e.g., PSCCH / PSSCH). Otherwise, if the time gap between the prioritization event and the potential resource conflict is outside the range, the WTRU may perform other prioritization procedures, such as dropping a resource or performing resource reselection for a resource.

[0125] In some embodiments as may be described herein, the WTRU may determine which resource to prioritize. For example, the WTRU may perform prioritization between two resources in the same or different carriers. The WTRU may determine which resource to prioritize based on one or any combination of parameters as described in the following examples.

[0126] The WTRU may determine which resource to prioritize based on the physical channel transmissions sent in the resource. For example, the WTRU may prioritize a sidelink (SL) synchronization signal block (SSB) (SL-SSB) over other channels. For example, the WTRU may prioritize SL-SSB transmissions in one carrier over transmission / reception of signals in other channels in another carrier. For example, the WTRU may prioritize other channel reception / transmissions (e.g., PSFCH) in one carrier over SL-SSB receptions in another carrier. Additionally or alternatively, the WTRU may prioritize PSFCH transmissions / receptions over other channels other than SL-SSB.

[0127] The WTRU may determine which resource to prioritize based on the information transmitted in the transmission. The information transmitted in the PSFCH may be IUC information, ACK indication, NACK indication for NACK groupcast, NACK indication for unicast. In some methods, the WTRU may determine which resource to prioritize based on the information transmitted in the resource. In another method, similar to the existing prioritization schemes, the WTRU may first determine which resource to prioritize based on the priority associated with the resource. However, if two resources have the same priority, the WTRU may then prioritize one resource over another based on the information transmitted in the resource. For example, if the PSCCH / PSSCH has one or more SL channel state information (CSI) reference signals (RS) (SSL-CSI-RS), the WTRU may prioritize the PSCCH / PSSCH over other channels (e.g., other PSCCH / PSSCH, PSFCH, etc.).

[0128] In some examples, the WTRU may determine whether to prioritize PSCCH / PSSCH or PSFCH based on the information conveyed in the PSFCH. For example, if the PSFCH conveys IUC information, the WTRU may prioritize PSCCH / PSSCH over PSFCH. However, if the PSFCH conveys HARQ feedback information, the WTRU may prioritize PSFCH over PSCCH / PSSCH.

[0129] The WTRU may determine which resource to prioritize based on the carrier associated with each resource. For example, the WTRU may determine which resource to prioritize based on the resource pool associated with each resource. In one method, the WTRU may be configured or pre-configured with a priority associated with each carrier. In another method, the WTRU may be configured or pre-configured between two carriers based on which carrier has a higher priority. The WTRU may then determine which resource to prioritize based on the carrier associated with the resource. The WTRU may first determine which resource to prioritize based on the priority associated with each resource. If the two resources have the same priority, the WTRU may determine which resource to prioritize based on which carrier has a higher priority. The WTRU may prioritize the resources in the carrier with the higher priority.

[0130] The WTRU may determine which resource to prioritize based on the type of carrier associated with each resource. For example, the WTRU may prioritize resources in a shared carrier with a Uu carrier. The WTRU may prioritize resources in a licensed carrier.

[0131] The WTRU may determine which resource to prioritize based on the scheduling pattern of the resource and / or the scheduling pattern associated with the resource. For example, the WTRU may prioritize network-scheduled resources or associated resources (e.g., PSFCH) over resources selected by the WTRU.

[0132] The WTRU may determine which resource to prioritize based on the transmit power associated with each resource. In one method, the WTRU may prioritize resources with higher transmit power. In another method, the WTRU may prioritize resources with lower transmit power.

[0133] The WTRU may determine which resource to prioritize based on the transmit / receive duration of each resource. In some methods, the WTRU may prioritize resources with longer transmit / receive durations. In another method, the WTRU may prioritize resources with shorter transmit / receive durations.

[0134] The WTRU may determine which resource to prioritize based on the subcarrier spacing associated with the resource. In some methods, the WTRU may prioritize resources with longer subcarrier spacing. In another method, the WTRU may prioritize resources with shorter subcarrier spacing.

[0135] In another example, the WTRU may determine which resource to prioritize based on the number of occupied resources in the time domain and / or frequency domain. For example, the WTRU may determine which resource to prioritize based on the number of resources of the resource. In an example, the interconnection of the resources may include the number of subchannels. Additionally or alternatively, the number of resources may include the number of resource elements (REs). In one method, the WTRU may prioritize resources that occupy a larger number of resources. In another method, the WTRU may prioritize resources that occupy a smaller number of resources. .

[0136] The WTRU may determine which resource to prioritize based on the number of physical channels (e.g., PSFCH, PSCCH / PSSCH) in each resource. In particular, the WTRU may prioritize resources with a higher number of physical channels. For example, the WTRU may need to prioritize between PSFCH transmission / reception and PSCCH / PSSCH transmission / reception. The WTRU may determine whether to prioritize PSFCH transmission / reception based on the number of PSFCHs that the WTRU needs to send / receive. Specifically, if the number of PSFCHs that the WTRU needs to send / receive is greater than a threshold, the WTRU may prioritize PSFCH transmission / reception; otherwise, if the number of PSFCHs is less than a threshold, the WTRU may prioritize PSCCH / PSSCH.

[0137] The WTRU may determine which resource to prioritize based on the channel busy rate (CBR) of the resource pool associated with the resource. For example, the WTRU may prioritize sending resources in a resource pool with a lower CBR.

[0138] The WTRU may be configured or pre-configured to prioritize one RAT (e.g., LTE SL RAT, NR SL RAT, Uu RAT) over another RAT. In some examples, the WTRU may prioritize the LTE SL RAT over the NR SL RAT. The WTRU may then perform a prioritization procedure to de-prioritize resources in the NR RAT, which may include dropping resources in the NR RAT, rate matching / puncturing, and reducing transmit power. In some examples, the WTRU may prioritize the Uu RAT over the NR SLRAT.

[0139] In another example, the WTRU may determine which resource to prioritize based on the synchronization status of one carrier. For example, the WTRU may determine whether to prioritize SL-SSB reception in one carrier over transmission / reception in another carrier based on the synchronization status of the WTRU in the carrier. Specifically, if the carriers are synchronized, the WTRU may prioritize transmission / reception of one or more channels in other carriers. Otherwise, if the carriers are not synchronized, the WTRU may prioritize SL-SSB reception in the carrier.

[0140] In some embodiments as may be described herein, the WTRU may perform prioritization between transmit and receive resources. In some solutions, the WTRU may perform prioritization between transmit and receive resources, which may be in the same or different carriers. The WTRU may then determine whether to transmit or receive based on one or any combination of parameters, factors, or conditions, as described in the following examples.

[0141] The WTRU may determine whether to perform transmission or reception based on the number of resources / channels to be transmitted and / or received. For example, if the number of resources / channels that the WTRU expects to transmit is greater than the number of resources / channels that the WTRU expects to receive, the WTRU may prioritize transmission. For example, if the number of resources / channels that the WTRU expects to transmit is greater than a threshold, the WTRU may prioritize transmission, which threshold may be configurable or pre-configured per carrier. For example, if the number of resources / channels that the WTRU expects to receive is greater than a threshold, the WTRU may prioritize reception, which threshold may be configurable or pre-configured per carrier.

[0142] The WTRU may determine whether to perform a transmission or reception based on the physical channel associated with the transmit / receive resource. For example, the WTRU may prioritize PSFCH reception over PSCCH / PSSCH transmission. For example, if the two transmissions have the same priority, the WTRU may prioritize PSFCH reception over PSCCH / PSSCH transmission. In another example, the WTRU may prioritize PSCCH / PSSCH transmission over PSCCH / PSSCH reception. For example, if the two resources have the same priority, the WTRU may prioritize PSCCH / PSSCH transmission over PSCCH / PSSCH reception.

[0143] The WTRU may determine whether to perform transmission or reception based on the carrier associated with each resource. For example, the WTRU may be configured or pre-configured with a priority associated with each carrier. If there is an overlap between two carriers based on the priorities associated with each carrier, the WTRU may determine whether to perform transmission / reception in one carrier or in another carrier. The WTRU may prioritize transmission / reception in the carrier with the higher priority.

[0144] The WTRU may determine whether to perform transmission or reception based on the scheduling pattern of the PSCCH / PSSCH and the associated PSFCH. For example, the WTRU may prioritize transmission / reception of resources scheduled by the network over resources selected autonomously by itself.

[0145] The WTRU may determine whether to perform transmission or reception based on the amount of occupied resources in the time domain, the frequency domain, or both. For example, the WTRU may prioritize transmission / reception on resources with a larger amount of occupied resources in the time domain, the frequency domain, or both. For example, the WTRU may prioritize transmission / reception on resources with a smaller amount of occupied resources in the time domain, the frequency domain, or both.

[0146] In some example solutions, the WTRU may perform prioritization between PSFCH transmissions. The WTRU may be scheduled using multiple subsets of PSFCH transmission resources, which may overlap in the time domain. Each subset of PSFCH transmission resources may include PSFCH resources in the same carrier. The WTRU may then perform prioritization between multiple PSFCH resources or multiple subsets of PSFCH transmission resources to determine which PSFCH transmission resources and / or which (which) PSFCH transmission resource subsets are used for transmission. In some methods, the WTRU may include all scheduled PSFCH resources for potential transmissions. The WTRU may then sequentially remove one or more PSFCH transmission resources until it is able to perform transmissions in all remaining PSFCH resources. In another method, the WTRU may sequentially add a PSFCH resource and / or a PSFCH resource set to perform PSFCH transmissions until it is unable to transmit transmissions on all PSFCH resources.

[0147] In some example solutions, the WTRU may determine the number of PSFCH transmissions to be sent simultaneously in multiple carriers. For example, in some solutions, the WTRU may determine the number of PSFCH transmissions to be sent simultaneously in multiple carriers (e.g., the maximum, minimum, and exact number of PSFCH transmissions) based on the carrier aggregation settings. In particular, the WTRU may determine to send (e.g., the maximum, minimum, and exact number) N1 PSFCHs for a single carrier case. The WTRU may determine to send (e.g., the maximum, minimum, or exactly) N2 PSFCH transmissions for a two contiguous carrier case. The WTRU may determine to send (e.g., the maximum, minimum, or exactly) N3 (e.g., N1>N2>N3) PSFCH transmissions for a two non-contiguous carrier case.

[0148] In some solutions, the WTRU may determine on which carrier to send the PSFCH transmission. The WTRU may have PSFCHs from multiple carriers to perform simultaneous PSFCH transmissions. The WTRU may first determine which carrier to use for the transmission based on the priority of the PSFCHs in each carrier. Specifically, the WTRU may select the carrier with the highest priority PSFCH transmission resources. If two or more carriers have the same highest priority, the WTRU may select the carrier on which to send the PSFCH transmission based on one or any combination of the following: the carrier with the highest number of PSFCHs; the carrier that results in the highest total transmit power; or the carrier that results in the highest transmit power per PSFCH.

[0149] In some solutions, the WTRU may determine which carrier(s) to add to a carrier set for simultaneous PSFCH transmission. The WTRU may determine to send simultaneous PSFCH transmissions in multiple carriers. The WTRU may first add one carrier for potential PSFCH transmission (e.g., the carrier with the PSFCH with the highest priority). The WTRU may also determine which carrier(s) to add for PSFCH transmission based on one or any combination of the following parameters:

[0150] The WTRU may determine which carrier(s) to add to the carrier set for simultaneous PSFCH transmission based on the frequency gap relative to the previously / first selected carrier. Specifically, the WTRU may determine to add the carrier that has the smallest frequency gap with the previously / first selected carrier (e.g., a carrier adjacent to the previously / first selected carrier). If there are multiple such carriers, the WTRU may add the carrier with the highest priority for PSFCH.

[0151] The WTRU may determine which carrier(s) to add to the carrier set for simultaneous PSFCH transmission based on the priority of the PSFCH in the carriers. In particular, the WTRU may determine to additionally include the carrier with the highest priority for PSFCH in the carrier set for simultaneous PSFCH transmission.

[0152] In some solutions, the WTRU may determine which carrier(s) to drop from simultaneous PSFCH transmissions. The WTRU may be scheduled with PSFCH transmission resources in multiple carriers. The WTRU may not be able to perform simultaneous PSFCH transmissions in all carriers. The WTRU may determine to drop one or more carriers. The WTRU may first select a prioritized carrier for PSFCH transmission (e.g., the carrier with the highest priority PSFCH). The WTRU may then determine which carrier(s) to drop based on one or any combination of parameters as may be described in the following examples.

[0153] The WTRU may determine to drop one or more carriers based on the frequency gap with the prioritized carriers. Specifically, the WTRU may determine to drop the carrier with the largest frequency gap with the previously / first selected carrier. If there are multiple such carriers, the WTRU may drop the lower priority carrier with the highest priority PSFCH in the carrier.

[0154] The WTRU may determine to drop one or more carriers based on the priority of the PSFCHs in the carriers. Specifically, the WTRU may drop lower priority carriers with the highest priority PSFCH in the carriers compared to non-dropped carriers.

[0155] In some solutions, the WTRU may determine which PSFCH to discard from the set of PSFCH transmission resources. The WTRU may be scheduled with multiple PSFCHs for simultaneous PSFCH transmissions from one or more carriers. The WTRU may not be able to perform simultaneous transmissions in all PSFCH resources. The WTRU may determine to discard one or more PSFCH resources from the set of simultaneous PSFCH transmissions. The WTRU may first select a prioritized PSFCH resource (e.g., a PSFCH resource with the highest priority). The WTRU may then determine which PSFCH to discard based on one or any combination of parameters as described in the following examples.

[0156] The WTRU may determine which PSFCH to discard based on the carrier gap between the first / previously selected PSFCH and the carrier of the PSFCH under consideration. For example, the WTRU may discard the PSFCH that has the largest carrier gap with the first / previously selected PSFCH. For example, for intra-band carrier aggregation, the WTRU may first discard a PSFCH in a carrier that is non-contiguous with the carrier of the first / previously selected PSFCH. If the WTRU cannot perform simultaneous PSFCH transmission in two contiguous carriers, the WTRU may then discard a PSFCH in a carrier that is contiguous with the carrier of the first / previously selected PSFCH. If the WTRU cannot perform simultaneous PSFCH transmission in a carrier, the WTRU may finally discard a PSFCH in the same carrier as the first / previously selected PSFCH.

[0157] The WTRU may determine which PSFCH to drop based on the frequency gap with the first / previously selected PSFCH (e.g., the PSFCH with the highest priority). For example, the WTRU may drop the PSFCH with the largest frequency gap with the first / previously selected PSFCH.

[0158] The WTRU may determine which PSFCH to drop based on the priority of the PSFCH. For example, the WTRU may drop the PSFCH with the lowest priority.

[0159] In some embodiments, the WTRU may first / previously select a prioritized PSFCH. The WTRU may then discard all PSFCHs in carriers where the WTRU may not be able to perform simultaneous transmissions (e.g., carriers that result in non-contiguous simultaneous CA). If the WTRU is able to perform simultaneous transmissions in the remaining carriers, the WTRU may determine which PSFCH resource to discard based on its priority. Specifically, the WTRU may discard the PSFCH resources with the lowest priority until the WTRU is able to perform simultaneous PSFCH transmissions.

[0160] In some solutions, the WTRU may determine which PSFCH to add to the PSFCH transmission resource set. The WTRU may be scheduled to have multiple PSFCHs for simultaneous PSFCH transmissions from one or more carriers. The WTRU may not be able to perform simultaneous transmissions in all PSFCH resources. The WTRU may first select a prioritized PSFCH resource (e.g., a PSFCH resource with the highest priority). The WTRU may then determine which PSFCH to add to the simultaneous PSFCH transmission resource set based on one or any combination of parameters as described in the following examples.

[0161] The WTRU may then determine which PSFCH to add to the simultaneous PSFCH transmission resource set based on the priority of the PSFCH resources. For example, the WTRU may sequentially add the resources with the highest priority from the remaining scheduled PSFCH resource set.

[0162] The WTRU may then determine which PSFCH to add to the set of simultaneous PSFCH transmission resources based on the carriers associated with the PSFCH. For example, the WTRU may add resources in the carrier that has the smallest frequency gap with the carrier of the first / previously prioritized / selected PSFCH resources.

[0163] In some embodiments, the WTRU may first / previously select a prioritized PSFCH. The WTRU may then determine which carrier to add to the set of carriers to perform simultaneous PSFCH transmissions. The WTRU may then sequentially add the PSFCH in the set of selected carriers based on the priority of the selected carriers. Specifically, the WTRU may sequentially add the PSFCH resources with the highest priority from the remaining set of scheduled PSFCH resources.

[0164] In some embodiments, the WTRU may first / previously select a prioritized PSFCH. The WTRU may then sequentially add PSFCH resources in the carriers of the prioritized PSFCH resources. The WTRU may then sequentially add another carrier that may have the smallest frequency gap with the first / previously selected / prioritized carrier. The WTRU may then sequentially add PSFCH in the carriers based on the priority of the PSFCH. The WTRU continues this procedure until it may not be able to add another carrier from the set of simultaneous PSFCH transmissions.

[0165] Figure 3 300 is a resource diagram illustrating an example scenario of PSFCH carrier selection for simultaneous PSFCH transmissions. As shown in the resource diagram 300, the WTRU may be scheduled to have a PSFCH in three PSFCHs, where each carrier has its associated priority. The WTRU may first determine to add a first component carrier (CC), such as, for example, CC1, to the set of simultaneous PSFCH transmissions because it has the highest priority PSFCH, where the highest priority is equivalent to the lowest priority value. For example, CC1 has a PSFCH transmission 310 with a priority of 1, making it Figure 3 In contrast, PFSCH transmission 320 has priority 3, PFSCH transmission 330 has priority 3, PFSCH transmission 340 has priority 3, PFSCH transmission 350 has priority 2, and PFSCH transmission 360 has priority 2.

[0166] The WTRU may then determine to add another CC to the set of simultaneous PSFCH transmissions. Figure 3 In the example shown, the WTRU may select between CC2 and CC3. Since the frequency gap between CC2 and CC1 is smaller than the frequency gap between CC3 and CC1, the WTRU may then determine to add CC2 to the set of simultaneous PSFCH transmissions. Figure 3 As seen in the example shown, CC2 is adjacent to CC1. In this way, the WTRU selects CC2 over CC3 even though the PFSCH transmission of CC3 has a higher priority than the PFSCH transmission of CC2. The WTRU may then determine to perform simultaneous PSFCH transmission for PSFCH transmissions in CC1 and CC2.

[0167] In some solutions, the WTRU may perform prioritization between PSCCH / PSSCH and PSFCH resources. For example, in some solutions, the WTRU may perform prioritization between PSCCH / PSSCH and PSFCH resources, where the PSCCH / PSSCH and PSFCH resources may be in the same carrier or in different carriers. Specifically, the WTRU may determine to perform one or any combination of procedures for prioritizing between PSCCH / PSSCH transmit resources and PSFCH transmit and / or receive resources, as described in the following examples.

[0168] The WTRU may perform puncturing / rate matching of overlapping symbols between PSFCH resources and PSCCH / PSSCH resources. The WTRU may drop PSCCH / PSSCH or PSFCH resources. The WTRU may reduce the transmit power of non-prioritized resources.

[0169] In some solutions, the WTRU may determine whether to discard one or more non-prioritized resources or to puncture / rate match the PSCCH / PSSCH. For example, in some solutions, the WTRU may determine whether to discard non-prioritized resources or to puncture / rate match the overlapping region between the PSFCH resources and the PSCCH / PSSCH based on one or any combination of the following example aspects. In an example, the non-prioritized resources may be PSCCH / PSSCH resources, PSFCH resources, etc.

[0170] The WTRU may determine whether to drop non-prioritized resources or to puncture / rate match the PSCCH / PSSCH based on a configuration or pre-configuration from a resource pool / carrier. For example, if there is an overlap between the PSCCH / PSSCH and another resource in another carrier, the WTRU may be configured or pre-configured in the resource pool as to whether to drop or puncture / rate match the PSCCH / PSSCH. The WTRU may then determine whether to drop or puncture the PSCCH / PSSCH based on the configuration in the resource pool. For example, when the PSFCH is deprioritized, the WTRU may be configured or pre-configured as to whether to drop the PSFCH in the resource pool or to rate match / puncture the PSCCH / PSSCH. The WTRU may follow the configuration from the resource pool or the pre-configuration from the resource pool.

[0171] The WTRU may determine whether to discard non-prioritized resources or puncture / rate match the PSCCH / PSSCH based on the location of the overlapping area. For example, if the PSFCH and PSCCH / PSSCH overlap in the last symbol of the PSCCH / PSSCH resource, the WTRU may determine to puncture / rate match the overlapping symbols of the PSCCH / PSSCH between the PSCCH / PSSCH and the PSFCH. For example, if the PSFCH resource appears in the middle of the PSCCH / PSSCH resource, the WTRU may determine to discard the non-prioritized resource. In the example, the non-prioritized resource may be a PSCCH / PSSCH resource, a PSFCH resource, etc.

[0172] The WTRU may determine whether to discard non-prioritized resources or perform puncturing / rate matching on the PSCCH / PSSCH based on the content of the potential discarded symbols. For example, the WTRU may make its determination based on whether the discarded symbol contains one or more of a demodulation reference signal (DMRS), PSCCH, a second SCI, etc. For example, if the potential discarded symbol contains PSCCH, a second SCI, and / or DMRS, the WTRU may discard a resource. Otherwise, the WTRU may perform puncturing / rate matching on PSCCH / PSSCH resources. In an example, the one resource discarded may be a PSFCH resource or a PSCCH / PSSCH resource.

[0173] The WTRU may determine whether to discard a non-prioritized resource or to perform puncturing / rate matching on the PSCCH / PSSCH based on the amount of overlapping area between two resources. For example, the WTRU may determine whether to discard one resource or to perform puncturing / rate matching on the PSCCH / PSSCH resource based on the duration of the overlap between two resources. Specifically, if the duration of the overlap between two resources is greater than a threshold, the WTRU may determine to discard one resource. Additionally or alternatively, if the duration of the overlap between two resources is less than a threshold, the WTRU may determine to perform puncturing / rate matching on the PSCCH / PSSCH resource. The threshold may be fixed, configured in a resource pool, or pre-configured in a resource pool, which may be further determined based on the WTRU capabilities.

[0174] The WTRU may determine whether to discard non-prioritized resources or perform puncturing / rate matching on the PSCCH / PSSCH based on the number of potential rate matching / puncturing symbols. For example, if the number of potential rate matching / puncturing symbols is less than a threshold, the WTRU may perform PSCCH / PSSCH rate matching / puncturing; otherwise, the WTRU may discard a de-prioritized resource. The threshold may be fixed, configured in the resource pool, or pre-configured in the resource pool.

[0175] The WTRU may determine whether to discard a non-prioritized resource or perform puncturing / rate matching on the PSCCH / PSSCH based on the synchronization status between the two resources. For example, the WTRU may determine whether to discard a resource or perform puncturing / rate matching on the PSCCH / PSSCH resource based on the synchronization status between the two resources / carriers. In particular, if the two carriers are not synchronized, the WTRU may discard a resource. Otherwise, if the two carriers are synchronized, the WTRU may perform resource discarding or resource puncturing / rate matching.

[0176] The WTRU may determine whether to discard or puncture / rate match the PSCCH / PSSCH based on the QoS of the PSCCH / PSSCH resources. In an example, the QoS may be a priority. For example, if the QoS (e.g., priority) of the PSCCH / PSSCH resources is less than a threshold, the WTRU may determine to discard the PSCCH / PSSCH resources; otherwise, if the priority of the PSCCH / PSSCH resources is greater than a threshold, the WTRU may perform puncturing / rate matching of the PSCCH / PSSCH resources. The threshold may be configured in a resource pool or pre-configured in a resource pool. The method may be triggered to help the WTRU reduce resource discards of high priority transport blocks (TBs).

[0177] The WTRU may determine whether to discard non-prioritized resources or perform puncturing / rate matching on the PSCCH / PSSCH based on the priority of the PSFCH. For example, the WTRU may determine whether to discard the PSFCH or perform rate matching / puncturing on the PSCCH / PSSCH based on the priority of the PSFCH. Specifically, if the priority of the PSFCH is less than a threshold, the WTRU may discard the PSFCH. Otherwise, if the priority of the PSFCH is greater than a threshold, the WTRU may perform rate matching / puncturing on overlapping symbols between the PSFCH and PSCCH / PSSCH resources.

[0178] The WTRU may determine whether to discard non-prioritized resources or puncture / rate match the PSCCH / PSSCH based on the number of PSFCHs to be sent / received. For example, the WTRU may determine whether to discard a resource (e.g., PSFCH) or rate match / puncture the PSCCH / PSSCH based on the number of PSFCHs to be sent / received. Specifically, if the number of PSFCHs to be sent / received is less than a threshold, the WTRU may discard a resource (e.g., PSFCH). Otherwise, the WTRU may rate match / puncture the PSCCH / PSSCH in the overlapping symbols between the two resources.

[0179] The WTRU may determine whether to discard a non-prioritized resource or to puncture / rate match the PSCCH / PSSCH based on the amount of overlap between the two resources. For example, the WTRU may determine whether to discard a non-prioritized resource or to rate match / puncture the PSCCH / PSSCH based on the number of overlapping symbols between the two resources and / or the number of potential rate matching / puncturing symbols. Specifically, if the number of rate matching / puncturing time slots is less than a threshold, the WTRU may determine to puncture / rate match the PSCCH / PSSCH resource; otherwise, the WTRU may discard a non-prioritized resource.

[0180] The WTRU may determine whether to discard non-prioritized resources or to puncture / rate match the PSCCH / PSSCH based on the information conveyed in the transmission. For example, the WTRU may determine whether to discard or puncture / rate match the PSCCH / PSSCH based on the information conveyed in the PSCCH / PSSCH and / or PSFCH. For example, the WTRU may determine whether to discard the PSFCH or to rate match / puncture the PSCCH / PSSCH based on the information conveyed in the PSFCH. For example, if the PSFCH conveys IUC information, the WTRU may discard the PSFCH. Otherwise, if the PSFCH conveys ACK / NACK feedback, the WTRU may puncture / rate match the PSCCH / PSSCH.

[0181] The WTRU may determine whether to discard a non-prioritized resource or to perform puncturing / rate matching on the PSCCH / PSSCH based on the HARQ feedback type. For example, the WTRU may determine whether to discard a non-prioritized resource or to perform rate matching / puncturing on the PSCCH / PSSCH based on the number of overlapping symbols between two resources and / or the number of potential rate matching / puncturing time slots. Specifically, if the number of rate matching / puncturing time slots is less than a threshold, the WTRU may determine to perform puncturing / rate matching on the PSCCH / PSSCH resource; otherwise, the WTRU may discard a non-prioritized resource.

[0182] The WTRU may determine whether to drop non-prioritized resources or to puncture / rate match the PSCCH / PSSCH based on the RAT associated with the resource. For example, the WTRU may determine whether to drop non-prioritized resources or to rate match / puncture the PSCCH / PSSCH resources based on the RAT associated with the resource. For example, if the PSCCH / PSSCH resource is in an LTE SLRAT, the WTRU may drop the resource. Additionally or alternatively, if the PSCCH / PSSCH resource is in an NR SL RAT, the WTRU may drop or rate match / puncture the resource.

[0183] The WTRU may determine whether to discard non-prioritized resources or to perform puncturing / rate matching on the PSCCH / PSSCH based on the scheduling pattern of the associated PSCCH / PSSCH sent by the PSCCH / PSSCH and the PSFCH. For example, the WTRU may determine whether to discard non-prioritized resources or to perform rate matching / puncturing on the PSCCH / PSSCH based on the scheduling pattern of the PSCCH / PSSCH associated with the PSFCH. Specifically, if the PSFCH is deprioritized, the WTRU may rate match / puncture the PSCCH / PSSCH if the PSCCH / PSSCH of the associated PSFCH is scheduled by the base station. Otherwise, if the PSCCH / PSSCH of the associated PSFCH is autonomously selected by the WTRU, the WTRU may discard the PSFCH. The method may be triggered to prioritize resources scheduled by the network over resources selected by the WTRU. In the example, the base station may be a gNB.

[0184] The WTRU may determine whether to discard a non-prioritized resource or perform puncturing / rate matching on the PSCCH / PSSCH based on the transmit / receive duration of the resource. For example, the WTRU may determine whether to discard a resource or perform rate matching / puncturing on the PSCCH / PSSCH based on the transmit / receive duration of the PSCCH / PSSCH. Specifically, if the transmit duration of the PSCCH / PSSCH is greater than a threshold, the WTRU may perform puncturing / rate matching on the PSCCH / PSSCH; otherwise, the WTRU may discard a non-prioritized PSCCH / PSSCH.

[0185] The WTRU may determine whether to discard a non-prioritized resource or to puncture / rate match the PSCCH / PSSCH based on the subcarrier spacing associated with the resource. For example, the WTRU may determine whether to discard a resource or to rate match / puncture the PSCCH / PSSCH based on the subcarrier spacing of the PSCCH / PSSCH and / or PSFCH. For example, if the SCS of the PSCCH / PSSCH is less than a threshold, the WTRU may puncture / rate match the PSCCH / PSSCH; otherwise, the WTRU may discard a non-prioritized PSCCH / PSSCH. For example, if the SCS of the PSFCH resource is less than a threshold, the WTRU may puncture / rate match the PSCCH / PSSCH. Otherwise, the WTRU may discard a non-prioritized resource. The threshold may be configured or pre-configured in the carrier, which may be a function of the SCS of the two carriers having the resource subject to prioritization.

[0186] Figure 4 is a resource diagram illustrating an example procedure performed by a WTRU for prioritizing between PSFCH resources and PSCCH / PSSCH resources. In the example shown in resource diagram 400, the WTRU may perform prioritization between PSCCH / PSSCH resources and PSFCH resources in two different carriers. For example, the WTRU may send a PSFCH transmission in CC1 and a PSCCH transmission, a PSSCH transmission, or both in CC2.

[0187] In the example case shown in resource diagram 400, the WTRU may use PSFCH resource 426 to send PFSCH transmissions, and other resources may be used for other purposes in component carrier 420 (which may be referred to as CC1). For example, resources 422 and resources 425 may be used by the WTRU to perform AGC. In addition, resources 424 and resources 427 may be used by the WTRU for guard periods or guard symbols. In the example, one timeslot on CC1 may have an SCS of 15 kHz.

[0188] The PSFCH resources 426 may be associated with an earlier PSCCH / PSSCH transmission on CC1 420. In an example, the information conveyed in the PSFCH transmission may be IUC information, an ACK indication, a NACK indication, etc. For example, the WTRU may send a PSCCH / PSSCH transmission using CC1 420 and later receive HARQ information, such as an ACK indication, regarding the PSCCH / PSSCH transmission in a PSFCH transmission received using the PSFCH resources 426. In another example, the WTRU may successfully receive a PSCCH / PSSCH transmission using CC1 420 and later send HARQ information, such as an ACK indication, regarding the PSCCH / PSSCH transmission in a PSFCH transmission sent using the PSFCH resources 426.

[0189] In addition, the WTRU may use PSCCH resources 434 to send PSCCH transmissions and may use PSSCH resources 435 to send PSSCH transmissions using component carrier 430 (which may be referred to as CC2). In an example, the WTRU may use PSCCH / PSSCH resources 434, 435 to send PSCCH / PSSCH transmissions. In addition, resource 432 may be used by the WTRU to perform AGC, and resource 437 may be used by the WTRU for a guard period or guard symbol. In an example, PSFCH resource 426 may occur simultaneously with the last symbol of PSSCH resource 435 (which may also be used for PSCCH resources) or the last resource 436. The WTRU may perform transmission, reception, or both in both resource 436 and resource 426. Therefore, the WTRU may rate match, puncture, or both the overlapping symbols or overlapping resources between resource 436 and resource 426. For example, the WTRU may rate match / puncture the portion of the PSCCH / PSSCH transmission sent using resource 436. Therefore, the WTRU may perform rate matching / puncturing around the symbols used in the resources for the guard period 424, 427, the resources for AGC 425, and the PSFCH resources 426. In this way, conflicts with transmission / reception of PSFCH transmissions using the PSFCH resources 426 and the related resources 424, 425, 427 may be avoided.

[0190] In addition, the WTRU may implicitly notify, explicitly notify, or both notify the receiving WTRU of the puncturing / rate matching event to help the receiving WTRU to correctly decode the transmission. In an example, the WTRU may use the SCI to implicitly notify, explicitly notify, or both notify the receiving WTRU. For example, the WTRU may use the SCI to notify the receiving WTRU of the puncturing / rate matching of the PSSCH transmission sent using resource 436. In an example, resource 436 may be considered a subset of resource 435.

[0191] In another example case shown in resource diagram 400, the WTRU may use PSFCH resource 456 to send PFSCH transmissions, and other resources may be used for other purposes in component carrier 450 (which may be referred to as CC1). For example, resources 452 and resources 455 may be used by the WTRU to perform AGC. In addition, resources 454 and resources 457 may be used by the WTRU for guard periods or guard symbols. In an example, one timeslot using CC1 450 may have an SCS of 30 kHz.

[0192] The PSFCH resources 456 may be associated with an earlier PSCCH / PSSCH transmission using CC1 450. In an example, the information conveyed in the PSFCH transmission may be IUC information, an ACK indication, a NACK indication, etc. For example, the WTRU may send a PSCCH / PSSCH transmission using CC1 450 and later receive HARQ information, such as an ACK indication, regarding the PSCCH / PSSCH transmission in a PSFCH transmission received using the PSFCH resources 456. In another example, the WTRU may successfully receive a PSCCH / PSSCH transmission using CC1 450 and later send HARQ information, such as an ACK indication, regarding the PSCCH / PSSCH transmission in a PSFCH transmission sent using the PSFCH resources 456.

[0193] In addition, on a component carrier 460, which may be referred to as CC2, the WTRU may use PSCCH resources 464 to send PSCCH transmissions, and may use PSSCH resources 465 to send PSSCH transmissions. In an example, the WTRU may use PSCCH / PSSCH resources 464, 465 to send PSCCH / PSSCH transmissions. In addition, resource 462 may be used by the WTRU to perform AGC, and resource 467 may be used by the WTRU for a guard period or guard symbol. In an example, PSFCH resource 456 may occur simultaneously with the middle of the resources of PSSCH resource 465 (which may also be used for PSCCH resources). The WTRU may perform transmission, reception, or both in the two resources 465. Therefore, the WTRU may determine to discard one or more non-prioritized resources for PSFCH transmissions in overlapping symbols or overlapping resources between resource 456 and resource 465. Specifically, in the example case shown in resource diagram 400, the WTRU may discard PSFCH resource 456. Therefore, the WTRU may also not use the guard resources 454, 457 and the AGC resources 455. The WTRU may discard the PSFCH resources 456 due to the lower priority of the PSFCH resources 456 compared to the resources 465. In an example, overlapping symbols or overlapping resources may appear in the middle of the resources 465 for PSCCH / PSSCH transmissions, which is different from the end resources 436 of the resources 435 due to the different SCSs of the two carriers in these two example cases. For example, CC1 420 may have an SCS of 15 kHz and CC1 450 may have an SCS of 30 kHz.

[0194] Figure 5 500 is a flow chart illustrating an example of prioritization between PSFCH resources and PSCCH / PSSCH resources. As shown in the flow chart 500, the WTRU receives a sidelink grant of resources for performing a PSCCH / PSSCH transmission using a first carrier 520. In an example, the resources may be PSCCH / PSSCH resources. In another example, the resources may be selected by the WTRU for use without a recent grant.

[0195] Additionally, the WTRU may determine that it is expected to receive or transmit a PSFCH transmission using the second carrier during a period of time that overlaps with PSCCH / PSSCH resources using the first carrier 530. Thus, the WTRU may determine that a collision will result in an overlapping period without changing at least one of the intended transmissions or receptions.

[0196] In addition, the WTRU may determine whether the overlapping period is in the last one or more symbols of the PSCCH / PSSCH resource 550. If or under the condition that the overlapping period is not in the last one or more symbols of the PSCCH / PSSCH resource, the WTRU may discard the PSCCH / PSSCH transmission or PSFCH transmission / reception 560. In this way, conflicts are avoided. For example, if the overlapping period is in the middle period of the PSCCH / PSSCH resource, the WTRU may discard the PSCCH / PSSCH transmission or PSFCH transmission / reception. The WTRU may discard transmissions with lower priority. In addition, the WTRU may send / receive non-discarded transmissions 570. For example, if the PSCCH / PSSCH transmission has a higher priority than the PSFCH transmission / reception, the WTRU may discard the PSFCH transmission and send the PSCCH / PSSCH transmission.

[0197] Similarly, if PSFCH transmission / reception takes precedence over PSCCH / PSSCH transmission, the WTRU may drop the PSCCH / PSSCH transmission and may perform a PSFCH transmission or a PSFCH reception. Thus, the WTRU may send a PSFCH transmission or receive a PSFCH transmission while dropping the PSCCH / PSSCH transmission.

[0198] The WTRU may puncture or rate match the PSCCH / PSSCH transmission 580 if or under the condition that the overlapping period is in the last symbol of the PSCCH / PSSCH resource. In this way, conflicts are avoided. Therefore, the WTRU may send a punctured / rate matched PSCCH / PSSCH transmission 590. Therefore, the WTRU may send a PSCCH / PSSCH transmission in a first symbol set in the overlapping period and not send a PSCCH / PSSCH transmission in a second symbol set in the overlapping period. In addition, the WTRU may indicate the puncturing / rate matching information in the SCI. The WTRU acting as a transmitting WTRU may send the SCI to the sidelink receiving WTRU. In an example, the transmitting WTRU may explicitly indicate the puncturing / rate matching information. In other examples, the transmitting WTRU may implicitly indicate the puncturing / rate matching information.

[0199] Figure 6600 is a flowchart illustrating an example of prioritization between a first SL transmission and a second SL transmission. In the example shown in flowchart 600, the WTRU may determine to use a first carrier to use a first side link (SL) resource to send or receive a first SL transmission, and to use a second carrier to use a second SL resource to send a second SL transmission 620. In the example, the second SL resource may include an overlapping period. In addition, the second SL resource may overlap with the first SL resource in the overlapping period. Specifically, the WTRU may determine whether the overlapping period is in the last one or more symbols of the second SL resource 640. If the overlapping period is in the last one or more symbols of the second SL resource, the WTRU may use the second carrier in the first symbol set of the second SL resource in the overlapping period to send at least a portion of the second SL transmission, and not use the second carrier in the second symbol set of the second SL resource in the overlapping period to send 650. In addition, the WTRU may use the first carrier to send or receive the first SL transmission using the first SL resource in the overlapping period 660.

[0200] In an example, the first SL resource may include a first time resource, and the second SL resource may include a second time resource. In addition, the overlap period may be in one or more symbols of the second time resource that overlap in time with one or more symbols of the first time resource.

[0201] In the example, the first SL transmission may be a PSFCH transmission. In addition, the first SL resource may be a PSFCH resource. In another example, the second SL transmission may be a PSCCH / PSSCH transmission. In addition, the second SL resource may be a PSCCH / PSSCH resource. In addition, the second SL transmission may be a PSCCH transmission. In addition, the second SL transmission may be a PSSCH transmission. In addition, the second SL transmission may be a combination of a PSCCH transmission and a PSSCH transmission. In addition, the second SL resource may be a PSCCH resource. In addition, the second SL resource may be a PSSCH resource. In addition, the second SL resource may be a combination of a PSCCH resource and a PSSCH resource.

[0202] In another example, the first SL transmission may be a PSCCH / PSSCH transmission, and the first SL resource may be a PSCCH / PSSCH resource. In addition, the first SL transmission may be a PSCCH transmission. In addition, the first SL transmission may be a PSSCH transmission. In addition, the first SL transmission may be a combination of a PSCCH transmission and a PSSCH transmission. In addition, the first SL resource may be a PSCCH resource. In addition, the first SL resource may be a PSSCH resource. In addition, the first SL resource may be a combination of a PSCCH resource and a PSSCH resource. In addition, the second SL transmission may be a PSFCH transmission. In addition, the second SL resource may be a PSFCH resource.

[0203] In another example, using the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, and not using the second carrier for transmission in the second symbol set of the second SL resource in the overlapping period can be considered as perforation. Additionally or alternatively, using the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, and not using the second carrier for transmission in the second symbol set of the second SL resource in the overlapping period can be considered as rate matching.

[0204] Additionally or alternatively, if the overlap period is earlier than the last symbol or symbols of the second SL resource, then based on a comparison of the priority associated with the first SL resource with the priority associated with the second SL resource, the WTRU may discard the transmission or reception of the first SL transmission or discard the transmission of the second SL transmission 670. The WTRU may then transmit or receive a non-discarded transmission 680. For example, if the overlap period is earlier than the last symbol or symbols of the second SL resource, then the WTRU may compare the priority of the first SL resource with the priority of the second SL resource.

[0205] If the first SL resource has a higher priority than the second SL resource, the WTRU may then use the first SL resource to send or receive the first SL transmission. In addition, the WTRU may discard the second SL transmission.

[0206] In an example, if the second SL resource has a higher priority than the first SL resource, the WTRU may then use the second SL resource to send or receive the second SL transmission. Otherwise, the WTRU may discard the first SL transmission.

[0207] In another example, the WTRU may send information about the first symbol set of the second SL resource and the second symbol set of the second SL resource to the receiving WTRU in the SCI. In addition, the WTRU may receive a SL grant for sending resources for the second SL transmission using the second carrier. Additionally or alternatively, the WTRU may select resources for sending the second SL transmission using the second carrier.

[0208] Methods for resource allocation for multiple carriers are described herein. In some example solutions, the WTRU may perform resource exclusion to reduce resource conflicts. For example, in some example solutions, the WTRU may trigger one or any combination of the following events: resource allocation; resource reassessment; or preemption.

[0209] Upon triggering one of these events, the WTRU may determine two resource sets in a resource selection window (RSW), wherein the first resource set may be denoted as a conflicting / unavailable resource set and the second resource set may be referred to as an available resource set. The WTRU may then perform resource selection in the second resource set (i.e., the available resource set). The WTRU may add a resource to the first resource set (i.e., the unavailable resource set) and / or exclude the resource from the second resource set (i.e., the available resource set), and perform resource selection in the second resource set if the WTRU cannot perform simultaneous transmission in the resource and transmission / reception of another resource in another carrier due to one or any combination of parameters or conditions, such as described below.

[0210] Such a condition may be when the number of TX chains is less than the number of transmit / receive carriers. The condition may be when the WTRU does not support the frequency band combination in the scheduled resources. The condition may be when the WTRU TX chain switching time of the WTRU is not satisfied to transmit in multiple carriers. The condition may be when the WTRU operates in a half-duplex band, which may not allow the WTRU to perform simultaneous transmission and reception. The condition may be when the Tx / Rx switching time of the WTRU is not satisfied to transmit in one carrier and receive in another carrier.

[0211] Specifically, the WTRU may include a resource from a first resource set (i.e., an unavailable resource set) and / or exclude the resource from a second resource set (i.e., an available resource set), and perform resource selection in the second resource set based on one or any combination of parameters as described in the examples in the following paragraphs.

[0212] Resource selection may be based on resources (eg, PSCCH / PSSCH resources) in the resource selection carrier overlapping with scheduled PSFCH transmit / receive resources of the WTRU potentially in another carrier.

[0213] For example, the WTRU may select / reserve PSCCH / PSSCH resources, such as semi-persistent scheduling (SPS) resources, in one carrier (e.g., CC2). The WTRU may target sending HARQ-enabled TBs in the selected / reserved PSCCH / PSSCH resources. When performing resource allocation in another carrier (e.g., CC1), the WTRU may add resources (e.g., PSCCH / PSSCH resources) that overlap with PSFCH resources associated with the selected / reserved PSCCH / PSSCH resources in the other carrier (e.g., CC2) to the first resource set (i.e., the unavailable resource set) and / or exclude resources (e.g., PSCCH / PSSCH resources) that overlap with PSFCH resources associated with the selected / reserved PSCCH / PSSCH resources in the other carrier (e.g., CC2) from the second resource set (i.e., the available resource set). The WTRU may then perform resource allocation in the second resource set (i.e., the available resource set).

[0214] For example, a WTRU may receive SCI from another WTRU that has reserved PSCCH / PSSCH resources (e.g., SPS resources) that may be used to send HARQ enabled TBs. The WTRU may be the target receiver of the TBs sent in the PSCCH / PSSCH resources. When performing resource allocation in one carrier, the WTRU may exclude PSCCH / PSSCH resources that overlap with the associated PSFCH resources of the reserved PSCCH / PSSCH resources.

[0215] Figure 7 is a resource diagram illustrating an example of a WTRU excluding PSCCH / PSSCH resources that overlap with a scheduled PSFCH transmission / reception. In the example shown in resource diagram 700, the WTRU may trigger resource selection for transmission in CC1 720 at timeslot n for resource selection in the window [n+T1, n+T2]. Specifically, n may be a resource selection or resource reselection triggering timeslot. Furthermore, n+T1 may be the first timeslot of the resource selection window. Furthermore, n+T2 may be the last timeslot of the resource selection window.

[0216] The WTRU may have reserved PSCCH / PSSCH resources 734 for a PSCCH / PSSCH transmission in CC2 730 for a HARQ enabled TB. In an example, the PSCCH / PSSCH resources 734 for the transmission may have been reserved by a PSCCH / PSSCH transmission using PSCCH / PSSCH resources 732. The WTRU may expect to receive a PSFCH transmission 738 in a PSFCH slot 736. In an example, the PSFCH transmission 738 may be associated with a PSCCH / PSSCH transmission using PSCCH / PSSCH resources 734. The WTRU may add a set of slots 728 that overlap with the PSFCH slot 736 (e.g., in CC2 730) to a first set of resources (e.g., an unavailable set of resources) and / or exclude a set of slots 728 from a second set of resources (e.g., an available set of resources) in a resource selection window (RSW) of CC1 720. For example, by performing sensing in CC3 740, the WTRU may decode SCI from another WTRU that semi-persistently reserves PSCCH / PSSCH resources 744. In an example, the SCI may be received in PSCCH / PSSCH resources 742. The WTRU may be expected to send PSFCH 748 in PSFCH slots 746 using CC3 740. The WTRU may add a set of slots 726 that overlap with PSFCH slots 746 (e.g., of CC3 740) to a first set of resources (e.g., an unavailable set of resources) and / or exclude a set of slots 726 from a second set of resources (e.g., an available set of resources) in the RSW of CC1 720 that overlap with PSFCH slots 746 (e.g., of CC3 740).

[0217] Figure 8 is a resource diagram illustrating an example of a WTRU excluding PSCCH / PSSCH resources having associated PSFCH transmissions / receptions that overlap with scheduled / reserved resources from another carrier. Resource selection may be based on allocating resources (e.g., PSCCH / PSSCH resources) in a carrier having associated PSFCH transmissions / receptions that overlap with scheduled / reserved resources (PSCCH / PSSCH or PSFCH) in another carrier.

[0218] For example, the WTRU may be expected to transmit / receive PSCCH / PSSCH transmit / receive or PSFCH transmit / receive in one resource. When performing resource allocation in another carrier (e.g., potentially for HARQ-enabled TBs), the WTRU may add to a first resource set (e.g., an unavailable resource set) and / or exclude from a second resource set (e.g., an available resource set) PSCCH / PSSCH resources having associated PSFCH resources that overlap with reserved / scheduled PSCCH / PSSCH or PSFCH transmit / receive resources.

[0219] In one example shown in resource diagram 800, the WTRU may trigger resource selection for transmission in CC1 820 at time slot n for resource selection in window [n+T1, n+T2]. As described above, n may be a resource selection or resource reselection triggering time slot. Furthermore, n+T1 may be the first time slot of the resource selection window. Furthermore, n+T2 may be the last time slot of the resource selection window.

[0220] The WTRU may add to the first resource set (e.g., unavailable resource set) and / or exclude from the second resource set (e.g., available resource set) time slots having associated PSFCH resources 824 that overlap with reserved PSCCH / PSSCH resources or PSFCH resources from another carrier. For example, the WTRU may have PSCCH / PSSCH resources 834 reserved in one carrier (e.g., CC2 830). In an example, the PSCCH / PSSCH resources 834 may have been reserved by a PSCCH / PSCCH transmission 832, and the PSCCH / PSSCH resources 836 may have been reserved by a PSCCH / PSCCH transmission 833. In addition, the PSFCH resources 828 may be associated with the PSCCH / PSSCH resources 836. In another example, PSCCH / PSSCH resources 844 may have been reserved by PSCCH / PSCCH transmission 842, and PSCCH / PSSCH resources 846 may have been reserved by PSCCH / PSCCH transmission 843 in carrier CC3 840. Additionally, PSFCH resources 848 may be associated with PSCCH / PSSCH resources 846. In an example, PSCCH / PSSCH resources 834 and PSCCH / PSSCH resources 844 may overlap with PSFCH resources 824. Additionally, PSFCH resources 828 may overlap with PSFCH resources 838 and PSFCH resources 848. If the associated PSFCH resources 824, 828 of resources 822, 826 overlap with reserved / scheduled PSCCH / PSSCH resources 834 or PSFCH resources 838 from the WTRU itself (e.g., resources in CC2830), or overlap with reserved / scheduled PSCCH / PSSCH resources 844 or PSFCH resources 848 from another WTRU (e.g., resources in CC3 840), the WTRU may add the resources 822, 826 to a first resource set (e.g., an unavailable resource set) and / or exclude the resources 822, 826 from a second resource set (e.g., an available resource set), where the WTRU may be a target receiver.

[0221] For example, the WTRU may exclude PSCCH / PSSCH resources 822 because they have associated PSFCH resources 824 that overlap with PSCCH / PSSCH resources 834 from the WTRU itself. Similarly, the WTRU may exclude PSCCH / PSSCH resources 826 because they have associated PSFCH resources 828 that overlap with PSFCH resources 838.

[0222] In another example, the WTRU may exclude PSCCH / PSSCH resources 822 because they have associated PSFCH resources 824 that overlap with PSCCH / PSSCH resources 844 from another WTRU. Likewise, the WTRU may exclude PSCCH / PSSCH resources 826 because they have associated PSFCH resources 828 that overlap with PSFCH resources 848.

[0223] Resource selection may be based on resources in a resource allocation carrier (eg, PSCCH / PSSCH resources) that overlap with configured or pre-configured SL-SSB resources from another carrier.

[0224] Resource selection may be based on allocating resources (eg, PSCCH / PSSCH resources) in a carrier that overlap with reserved resources (eg, PSCCH / PSSCH resources or PSFCH resources) from another carrier where the WTRU is the target receiver.

[0225] In some solutions provided herein, the WTRU may determine whether to include resources from a set of unavailable resources.

[0226] For example, for a resource allocation procedure, the WTRU may determine whether to add resources (e.g., PSCCH / PSSCH resources) to a first resource set (e.g., an unavailable resource set) and / or exclude the resources from a second resource set (e.g., an available resource set) in a resource allocation window due to overlapping transmission / reception in another carrier based on one or any combination of the following.

[0227] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on a QoS (such as, for example, a priority) associated with the data (such as, for example, logical channel (LCH) data) that triggers the resource allocation. In some methods, if the priority of the data (e.g., LCH) that triggers the resource allocation is greater than a threshold, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in another carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set). The threshold may be configured per resource pool or pre-configured.

[0228] In some methods, if the priority of the data (e.g., LCH) triggering resource allocation is less than a threshold, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set) due to overlapping transmission / reception in another carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set). The threshold may be configured per resource pool or pre-configured.

[0229] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the QoS (e.g., priority) associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier. In some methods, if the priority associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier is greater than a threshold, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in the other carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set). The threshold may be configured per resource pool or pre-configured.

[0230] In some methods, if the priority associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier is less than a threshold, the WTRU may add a resource (e.g., PSCCH / PSSCH) to a first resource set (e.g., an unavailable resource set) and / or exclude the resource from a second resource set (e.g., an available resource set) due to overlapping transmission / reception in another carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., an unavailable resource set) and / or exclude the resource from the second resource set (e.g., an available resource set). The threshold may be configured per resource pool or pre-configured.

[0231] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the relative QoS (e.g., priority) between the LCH allocated by the triggering source and the overlapping PSCCH / PSSCH and / or PSFCH in another carrier. In some methods, if the priority of the LCH triggering the resource allocation is greater than the priority of the overlapping PSCCH / PSSCH and / or PSFCH in another carrier, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set) due to the overlapping transmission / reception in the other carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set).

[0232] In some methods, if the priority of the LCH triggering the resource allocation is less than the priority of the overlapping PSCCH / PSSCH and / or PSFCH in another carrier, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set) due to the overlapping transmission / reception in the other carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set).

[0233] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on whether the overlapping resources in the other carrier are transmission or reception resources and / or the type of overlapping channels. Specifically, the WTRU may determine whether to add resources (e.g., PSCCH / PSSCH resources) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) in the resource allocation window due to overlapping transmission / reception in the other carrier based on one or any combination of the following overlapping scenarios: the PSCCH / PSSCH of the resource allocation carrier overlaps with the PSCCH / PSSCH transmission from another carrier; the PSCCH / PSSCH of the resource allocation carrier overlaps with the PSCCH / PSSCH reception from another carrier; the PSCCH / PSSCH of the resource allocation carrier overlaps with the PSFCH from another carrier. Transmission overlap; PSCCH / PSSCH of the resource allocation carrier overlaps with PSFCH reception from another carrier; PSFCH associated with PSCCH / PSSCH of the resource allocation carrier overlaps with PSCCH / PSSCH transmission from another carrier; PSFCH associated with PSCCH / PSSCH of the resource allocation carrier overlaps with PSCCH / PSSCH reception from another carrier; PSFCH associated with PSCCH / PSSCH of the resource allocation carrier overlaps with PSFCH transmission from another carrier; PSFCH associated with PSCCH / PSSCH of the resource allocation carrier overlaps with PSFCH reception from another carrier.

[0234] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on whether the carrier of the overlapping resources is an intra-band carrier or an inter-band carrier and / or the number of TRX chains of the WTRU. For example, if the two carriers are intra-band carriers or the WTRU has only one TRX chain, the WTRU may add the resources (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in the other carrier. Otherwise, if the two carriers are inter-band carriers and the WTRU has two TRX chains, the WTRU may not add the resources to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set).

[0235] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on whether the carriers of overlapping resources are contiguous or non-contiguous for the intra-band carriers and / or the number of TRX chains of the WTRU.

[0236] The determination of whether to include resources from the unavailable set of resources and / or exclude resources from the available set of resources may be based on whether the frequency band is a full-duplex band or a half-duplex band and / or the number of TRX chains of the WTRU.

[0237] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the CBR of the resource pool. In some methods, if the CBR of the resource pool is greater than a threshold, the WTRU may add resources (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in another carrier. Otherwise, the WTRU may not add the resources to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set). The threshold may be configured per resource pool or pre-configured.

[0238] In some methods, if the CBR of the resource pool is less than a threshold, the WTRU may add a resource (e.g., PSCCH / PSSCH) to a first resource set (e.g., unavailable resource set) and / or exclude the resource from a second resource set (e.g., available resource set) due to overlapping transmission / reception in another carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set). The threshold may be configured per resource pool or pre-configured.

[0239] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the measured SL-RSRP of the decoded PSCCH / PSSCH resources. If the measured SL-RSRP of the PSCCH / PSSCH reception in another carrier is greater than a threshold, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in the other carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set). The threshold may be configured per resource pool or pre-configured.

[0240] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the resource reservation type for the overlapping PSCCH / PSSCH resources in the other carrier (e.g., whether the overlapping PSCCH / PSSCCH and / or its associated PSFCH is semi-persistently or dynamically reserved). In some methods, if the overlapping PSCCH / PSSCH or the associated PSFCH is semi-persistently reserved, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in the other carrier. Otherwise, the WTRU may not add the resource to the first resource set (e.g., the unavailable resource set) and / or exclude the resource from the second resource set (e.g., the available resource set).

[0241] In some methods, if the overlapping PSCCH / PSSCH or associated PSFCH is dynamically reserved, the WTRU may add the resource (e.g., PSCCH / PSSCH) to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set) due to overlapping transmission / reception in another carrier. Otherwise, if the overlapping PSCCH / PSSCH or associated PSFCH is semi-persistently reserved, the WTRU may not add the resource to the first resource set (e.g., unavailable resource set) and / or exclude the resource from the second resource set (e.g., available resource set).

[0242] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the type of reserved PSCCH / PSSCH resources (e.g., whether the reserved PSCCH / PSSCCH is semi-persistently or dynamically reserved). For example, if overlapping PSCCH / PSSCH or associated PSFCH is dynamically reserved, the WTRU may add resources (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in another carrier. Otherwise, if overlapping PSCCH / PSSCH or associated PSFCH is semi-persistently reserved, the WTRU may not add the resources to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set).

[0243] The determination of whether to include resources from the unavailable resource set and / or exclude resources from the available resource set may be based on the number / percentage of resources in the second resource set (e.g., the available resource set) after the exclusion procedure. For example, the WTRU may determine whether to add resources (e.g., PSCCH / PSSCH resources) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) in the resource allocation carrier due to overlapping transmission / reception in another carrier based on the number of remaining resources in the second resource set. Specifically, if the number / percentage of resources in the second resource set after the exclusion procedure is greater than a threshold, the WTRU may add resources (e.g., PSCCH / PSSCH) to the first resource set (e.g., the unavailable resource set) and / or exclude the resources from the second resource set (e.g., the available resource set) due to overlapping transmission / reception in another carrier. Otherwise, if the number / percentage of resources after the exclusion procedure is less than the threshold, the WTRU may not add resources to the first resource set and / or exclude the resources from the second resource set. The WTRU may prioritize overlapping resources of a certain type to exclude from the second set of resources until the number / percentage of resources in the second set of resources is greater than a threshold. The threshold may be configured or pre-configured in the resource pool.

[0244] In some solutions, the WTRU may perform resource reselection of a resource if it overlaps with an intended Tx / Rx resource in another carrier. In some solutions, the WTRU may perform resource re-evaluation and / or resource preemption, where resource re-evaluation may be for a pre-selected resource and resource preemption may be for a reserved resource. If a pre-selected / reserved resource and / or its associated PSFCH resource overlaps with a transmit / receive resource in another carrier, the WTRU may reselect the pre-selected / reserved resource, where the WTRU may not be able to perform one or both of the following: simultaneous transmission in the reserved / selected resource in one carrier and transmission / reception in the overlapping resource in another carrier; or simultaneous reception of the PSFCH resource in one carrier and transmission / reception of the overlapping resource in another carrier.

[0245] In some solution sets, the WTRU may reselect reserved / pre-selected resources if it decodes a transmission from another WTRU that reserves / schedules resources that overlap with the pre-selected / reserved PSCCH / PSSCH and / or overlaps with the PSFCH associated with the pre-selected / reserved PSCCH / PSSCH of the WTRU. Specifically, the WTRU may reselect the reserved / pre-selected PSCCH / PSSCH if it decodes a PSCCH / PSSCH transmission from another WTRU that reserves / schedules PSCCH / PSSCH and / or PSFCH that overlaps with the pre-selected / reserved PSCCH / PSSCH or overlaps with the PSFCH associated with the pre-selected / reserved PSCCH / PSSCH of the WTRU in the current resources of the allocated carrier.

[0246] In some solutions, the WTRU determines whether to reselect a reserved / pre-selected resource. The WTRU may determine whether to reselect a reserved / pre-selected resource based on one or any combination of the following parameters or conditions.

[0247] The determination of whether to reselect a reserved / pre-selected resource may be based on the QoS (e.g., priority) associated with the pre-selected / reserved PSCCH / PSSCH resource. For example, if the priority associated with the resource is less than a threshold, the WTRU may determine to reselect the pre-selected / reserved PSCCH / PSSCH; otherwise, the WTRU may not reselect the pre-selected / reserved PSCCH / PSSCH resource.

[0248] The determination of whether to reselect the reserved / pre-selected resources may be based on the QoS (e.g., priority) associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier. For example, if the priority associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier is greater than a threshold, the WTRU may reselect the pre-selected / pre-reserved PSCCH / PSSCH; otherwise, the WTRU may not reselect the pre-selected / pre-reserved PSCCH / PSSCH resources.

[0249] The determination of whether to reselect the reserved / pre-selected resources may be based on the relative QoS (e.g., priority) between the LCH that triggered the resource allocation and the overlapping PSCCH / PSSCH and / or PSFCH in another carrier. For example, if the priority associated with the PSCCH / PSSCH resources in the resource allocation carrier is less than the priority associated with the overlapping PSCCH / PSSCH and / or PSFCH in another carrier, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH; otherwise, the WTRU may not reselect the pre-selected / reserved PSCCH / PSSCH resources.

[0250] The determination of whether to reselect the reserved / pre-selected resources may be based on whether the overlapping resources in the other carrier are transmit or receive resources and / or the type of overlapping channels. Specifically, the WTRU may determine whether to reselect the pre-selected / pre-reserved PSCCH / PSSCH resources based on one or any combination of overlapping scenarios as described in the following paragraphs.

[0251] The determination of whether to reselect a reserved / pre-selected resource may be based on the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier that overlaps with a potential PSCCH / PSSCH transmission from another carrier. For example, if the priority of the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier is less than the priority of the potential PSCCH / PSSCH transmission from another carrier, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier.

[0252] The determination of whether to reselect a reserved / pre-selected resource may be based on the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier that overlaps with a PSCCH / PSSCH reception from another carrier. For example, if the pre-selected / reserved PSCCH / PSSCH or its associated PSFCH overlaps with a reserved PSCCH / PSSCH transmission from another WTRU (where the WTRU may be one of the target receivers), the WTRU may keep the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier. The WTRU may send a HARQ NACK to request the other WTRU to retransmit the TB.

[0253] The determination of whether to reselect a reserved / pre-selected resource may be based on the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier that overlaps with a PSFCH transmission from another carrier. For example, the WTRU may keep the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier if the pre-selected / reserved PSCCH / PSSCH overlaps with its PSFCH transmission in another carrier. Specifically, if the WTRU cannot perform simultaneous transmission in two carriers, the WTRU may perform rate matching / puncturing of the overlapping symbols of the PSCCH / PSSCH between the two resources.

[0254] The determination of whether to reselect the reserved / pre-selected resources may be based on the PSCCH / PSSCH of the resource allocation carrier that overlaps with the PSFCH reception from another carrier. For example, if the pre-selected / pre-reserved PSCCH / PSSCH overlaps with its PSFCH transmission in another carrier, the WTRU may keep the pre-selected / pre-reserved PSCCH / PSSCH of the resource allocation carrier. Specifically, if the WTRU cannot perform simultaneous transmission in PSCCH / PSSCH and reception of PSFCH in two carriers, the WTRU may perform rate matching / puncturing of the overlapping symbols of PSCCH / PSSCH between the two resources.

[0255] The determination of whether to reselect the reserved / pre-selected resources may be based on the associated PSFCH of the PSCCH / PSSCH of the resource allocation carrier that overlaps with a PSCCH / PSSCH transmission from another carrier. For example, if the associated PSFCH of the pre-selected / reserved PSCCH / PSSCH overlaps with a PSCCH / PSSCH transmission in another carrier, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier. Specifically, if the WTRU cannot perform simultaneous transmission in PSCCH / PSSCH and reception of PSFCH in two carriers, the WTRU may perform rate matching / puncturing of the overlapping symbols of the PSCCH / PSSCH between the two resources.

[0256] The determination of whether to reselect the reserved / pre-selected resources may be based on the associated PSFCH of the PSCCH / PSSCH of the resource allocation carrier that overlaps with the PSCCH / PSSCH reception from another carrier. For example, if the associated PSFCH of the pre-selected / reserved PSCCH / PSSCH overlaps with the PSCCH / PSSCH transmission in another carrier, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier. Specifically, if the WTRU cannot perform simultaneous transmission in PSCCH / PSSCH and reception of PSFCH in two carriers, the WTRU may perform rate matching / puncturing of the overlapping symbols of the PSCCH / PSSCH between the two resources.

[0257] The determination of whether to reselect a reserved / pre-selected resource may be based on the associated PSFCH of the PSCCH / PSSCH of the resource allocation carrier that overlaps with a PSFCH transmission from another carrier. For example, if the associated PSFCH of the pre-selected / reserved PSCCH / PSSCH overlaps with a PSFCH transmission from another carrier, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH of the resource allocation carrier. If the priority of the PSCCH / PSSCH is less than the priority of the overlapping PSFCH in another carrier, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH.

[0258] The determination of whether to reselect a reserved / pre-selected resource may be based on the associated PSFCH of the PSCCH / PSSCH of the resource allocation carrier that overlaps with PSFCH reception from another carrier. For example, the WTRU may maintain the pre-selected / pre-reserved PSCCH / PSSCH of the resource allocation carrier if the associated PSFCH of the pre-selected / pre-reserved PSCCH / PSSCH overlaps with PSFCH reception from another carrier.

[0259] The determination whether to reselect reserved / pre-selected resources may be based on whether the carrier of the overlapping resources is an intra-band carrier or an inter-band carrier and / or the number of TRX chains of the WTRU.

[0260] The determination whether to reselect reserved / pre-selected resources may be based on whether the carriers of overlapping resources are contiguous or non-contiguous for the intra-band carriers and / or the number of TRX chains of the WTRU.

[0261] The determination whether to reselect a reserved / pre-selected resource may be based on whether the frequency band is a full-duplex band or a half-duplex band and / or the number of TRX chains of the WTRU.

[0262] The determination of whether to reselect a reserved / pre-selected resource may be based on the CBR of the resource pool. In some methods, if the CBR of the resource pool is greater than a threshold, the WTRU may reselect a pre-selected / reserved PSCCH / PSSCH resource. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resource. The threshold may be configured or pre-configured in the resource pool. In some methods, if the CBR of the resource pool is greater than a threshold, the WTRU may reselect a pre-selected / reserved PSCCH / PSSCH resource. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resource. The threshold may be configured or pre-configured in the resource pool.

[0263] The determination of whether to reselect the reserved / pre-selected resources may be based on the measured SL-RSRP of the decoded PSCCH / PSSCH resources. For example, if the measured SL-RSRP of the PSCCH / PSSCH reception in another carrier is greater than a threshold, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resources in the current resource allocation carrier. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resources in the current resource allocation carrier. The threshold may be configured per resource pool or pre-configured.

[0264] The determination of whether to reselect the reserved / pre-selected resources may be based on the HARQ type of the TB and / or the HARQ type of the overlapping resources in another carrier. For example, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH for one HARQ type (e.g., HARQ disabled) of the TB and / or the overlapping resources. The WTRU may not reselect the pre-selected / reserved PSCCH / PSSCH for another HARQ type (e.g., HARQ disabled) of the TB and / or the overlapping resources.

[0265] The determination of whether to reselect a reserved / pre-selected resource may be based on the playout type of the TB and / or the playout type of the overlapping resources in another carrier. For example, the WTRU may reselect a pre-selected / reserved PSCCH / PSSCH for one playout type (e.g., unicast) of the TB and / or overlapping resources. The WTRU may not reselect a pre-selected / reserved PSCCH / PSSCH for another playout type (e.g., broadcast) of the TB and / or overlapping resources.

[0266] The determination of whether to reselect the reserved / pre-selected resources may be based on whether the WTRU is the receiver of the decoded PSCCH / PSSCH. For example, if the WTRU is the receiver of overlapping transmission resources in another carrier, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resources in the current resource allocation carrier. Otherwise, the WTRU may keep the pre-selected / reserved PSCCH / PSSCH resources.

[0267] The determination of whether to reselect the reserved / pre-selected resources may be based on whether the transmitter / receiver WTRU in the overlapping resources is the target receiver of the pre-selected / reserved PSCCH / PSSCH resources. For example, if the transmitter / receiver of the overlapping resources in another carrier is the target WTRU of the pre-selected / reserved PSCCH / PSSCH resources, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resources in the current resource allocation carrier.

[0268] The determination of whether to reselect a reserved / pre-selected resource may be based on whether the PSCCH / PSSCH resource is a pre-selected or reserved resource.

[0269] The determination of whether to reselect a reserved / pre-selected resource may be based on the resource reservation type for the overlapping PSCCH / PSSCH resources in another carrier (e.g., whether the overlapping PSCCH / PSSCCH and / or its associated PSFCH is semi-persistently or dynamically reserved). In some methods, if the overlapping PSCCH / PSSCH or associated PSFCH in another carrier is semi-persistently reserved, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resources. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resources. In some methods, if the overlapping PSCCH / PSSCH or associated PSFCH in another carrier is dynamically reserved, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resources. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resources.

[0270] The determination of whether to reselect a reserved / pre-selected resource may be based on the traffic type and / or resource reservation type of the pre-selected / reserved PSCCH / PSSCH resource in the resource allocation carrier (e.g., whether the pre-selected / reserved resource is reserved / selected for periodic reservation or non-periodic reservation). In some methods, if the pre-selected / reserved PSCCH / PSSCH resource is periodically reserved, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resource. Otherwise, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resource. In some methods, if the pre-selected / reserved PSCCH / PSSCH resource is periodically reserved, the WTRU may maintain the pre-selected / reserved PSCCH / PSSCH resource. Otherwise, the WTRU may reselect the pre-selected / reserved PSCCH / PSSCH resource.

[0271] Fig. 9 is a resource diagram illustrating an example of a WTRU performing resource reselection when a PSCCH / PSSCH resource and / or its associated PSFCH resource overlaps with a received resource in another carrier. As shown in resource diagram 900, the WTRU may determine to reselect a preselected / reserved resource based on one or any combination of the following events. The WTRU may make a determination based on reception of a PSCCH / PSSCH transmission on a PSCCH / PSSCH resource 961 that reserves other PSCCH / PSSCH resources 966 with associated PSFCH resources 964 that overlap with the WTRU's preselected / reserved PSCCH / PSSCH resource 922. The PSCCH / PSSCH transmission may be received on a first component carrier, such as CC1 920. As in other examples, n may be a resource selection or resource reselection triggering timeslot. Additionally, n+T1 may be the first timeslot of the resource selection window. Additionally, n+T2 may be the last timeslot of the resource selection window.

[0272] Additionally, the WTRU may make a determination based on reception of a PSCCH / PSSCH transmission on a PSCCH / PSSCH resource 965 that other PSCCH / PSSCH resources 969 are reserved that overlap with the WTRU's pre-selected / reserved PSCCH / PSSCH resource 922. The PSCCH / PSSCH transmission received on the PSCCH / PSSCH resource 965 may be received on a second component carrier, such as CC2 960.

[0273] In addition, the WTRU may make a determination based on reception of a PSCCH / PSSCH transmission on a PSCCH / PSSCH resource 962 that other PSCCH / PSSCH resources 970 are reserved that overlap with the associated PSFCH resources 928 of the WTRU's pre-selected / reserved PSCCH / PSSCH resource 922. Additionally or alternatively, the WTRU may make a determination based on reception of a PSCCH / PSSCH transmission on a PSCCH / PSSCH resource 963 that other PSCCH / PSSCH resources 967 are reserved that have associated PSFCH resources 968 that overlap with the associated PSFCH resources 928 of the WTRU's pre-selected / reserved PSCCH / PSSCH resource 922.

[0274] In some solutions, the WTRU may indicate resource conflicts to the WTRU that reserved conflicting resources.The WTRU may send an IUC (eg, conflict indication) to the WTRU that reserved conflicting resources to implicitly request the WTRU to perform resource selection.

[0275] In some solutions, the WTRU may perform a Logical Channel Prioritization (LCP) procedure. For example, the WTRU may perform an LCP restriction to determine whether to multiplex a HARQ-enabled LCH to a TB. Specifically, if the associated PSFCH of a PSCCH / PSSCH resource overlaps with another transmission / reception of the WTRU in another carrier, where the WTRU may not be able to perform simultaneous reception of the associated PSFCH in the current carrier and transmission / reception in the resource in another carrier, the WTRU may determine to multiplex the LCH with disabled HARQ to construct a TB for potential transmission in the PSCCH / PSSCH of the current carrier.

[0276] In some solutions, the WTRU may determine whether to perform resource reselection or other prioritization methods. The WTRU may determine whether to perform resource reselection or other prioritization methods (e.g., resource discarding, rate matching / puncturing, performing only transmission / reception) based on the time gap between the detection time / time slot of the resource overlap event and the actual resource overlap time slot or the transmission time slot of the reserved / scheduled resources in the overlap. Specifically, if the time gap between the detection time of the resource overlap event and the resource overlap time slot or the transmission time slot of the reserved / scheduled resources in the overlap is greater than a threshold, the WTRU may perform resource reselection. Otherwise, if the time gap is less than the threshold, the WTRU may perform other prioritization methods (e.g., resource discarding, rate matching / puncturing, performing only transmission / reception). The threshold may be configured in the resource pool or pre-configured. It may be determined based on the processing capability of the WTRU.

[0277] Fig.10 1000 is a resource diagram illustrating an example scenario in which a WTRU determines whether to perform resource reselection or other resource prioritization methods due to overlapping resources in different carriers. In one example shown in resource diagram 1000, the WTRU may determine whether to perform resource reselection or other resource prioritization methods (e.g., discarding transmit / receive resources, rate matching / puncturing, etc.) based on the detection of an overlap event and the time gap between resource overlapping time slots. Fig.10 In the example of , n+T2 may be the last time slot of the resource selection window.

[0278] Specifically, in Fig.10 In the example shown in Case 1 of , the WTRU may determine that the time gap (e.g., Timegap_1) between the detection of the overlapping event and the scheduling of the overlapping PSFCH time slots 1028, 1038 by the PSCCH / PSSCH resources 1022, 1036 is greater than a threshold. Therefore, the WTRU may determine to perform resource reselection. The WTRU may then perform resource reselection. Therefore, the WTRU may perform resource reselection to avoid resource overlap. In CC2 1030, the PSCCH / PSSCH transmission 1032 may schedule the PSCCH / PSSCH resource 1036, which may then be used by the PSCCH / PSSCH transmission associated with the PSFCH resource 1038. In addition, in CC1 1020, the PSCCH / PSSCH resource 1022 may be used by the PSCCH / PSSCH transmission associated with the PSFCH resource 1028. In the example, the WTRU may detect the overlapping event at time m1 at the beginning of Timegap_1. Furthermore, Timegap_1 may end when the PSCCH / PSSCH resource 1022 starts (which is also the start of the PSCCH / PSSCH transmission associated with the overlapping PSFCH resource 1028).

[0279] However, for case 2, the WTRU may determine that the time gap between the detection of the overlap event and the PSCCH / PSSCH scheduling of the overlap time slot (i.e., Timegap_2) is less than a threshold. Therefore, the WTRU may determine to perform resource discarding. Therefore, the WTRU may then perform resource discarding. In CC2 1060, the PSCCH / PSSCH transmission 1064 may schedule PSCCH / PSSCH resources 1066, which in turn may be used by the PSCCH / PSSCH transmission associated with the PSFCH resources 1068. In addition, in CC1 1050, the PSCCH / PSSCH resources 1056 may be used by the PSCCH / PSSCH transmission associated with the PSFCH resources 1058. In the example, the WTRU may detect an overlap event at time m2 at the beginning of Timegap_2. Additionally, Timegap_2 may end when PSCCH / PSSCH resource 1056 begins (which is also the start of the PSCCH / PSSCH transmission associated with the overlapping PSFCH resource 1058).

[0280] In some solutions, the WTRU may trigger a resource overlap detection event. The WTRU may trigger resource overlap detection to reduce potential resource overlap conflicts. In particular, the WTRU may determine that at least a period of time before the pre-selected / reserved resource is triggered for each pre-selected / reserved resource. If an overlap event is detected, the WTRU may then reselect the pre-selected / reserved resource.

[0281] Resource synchronization procedures are described herein. In some procedures, a WTRU may perform a sidelink synchronization transmission. A WTRU may determine to perform a sidelink synchronization signal (SLSS) transmission as a synchronization reference WTRU (SynRef WTRU). A WTRU may perform transmission of an S-PSS, S-SSS, and / or PBSCH for another WTRU to synchronize sidelink transmission and / or reception. In this document, the transmission of one or any combination of signals (e.g., S-PSS, S-SSS, PBSCH) may be referred to as an SLSS.

[0282] The WTRU may determine the carrier on which to send the SLSS. In some solutions, the WTRU may determine which carrier(s) to send the SLSS based on one or any combination of example factors as may be described in the following paragraphs.

[0283] The WTRU may determine which carrier(s) to send SLSS based on the service established at the WTRU. For example, the WTRU may be configured or pre-configured with a set of carriers for a sidelink service. The WTRU may then perform SLSS transmission in the carriers associated with the service established at the WTRU.

[0284] In another example of a service established at the WTRU, the WTRU may be configured or pre-configured with one or more sidelink services, where each service may be associated with one or more carriers. For a sidelink service, the WTRU may then determine to perform SLSS transmission in at least one carrier configured or pre-configured for each service.

[0285] The WTRU may determine which carrier(s) transmit the SLSS based on the reception of the SLSS. For example, the WTRU may determine to synchronize to a node (e.g., a WTRU). The WTRU may receive synchronization signals from the WTRU. The WTRU may transmit the SLSS in a carrier on which it receives the SLSS from another node. In an example, the other node may be a base station, a gNB, a SynRef WTRU, a SLWTRU, a peer WTRU, a relay WTRU, another WTRU, etc.

[0286] The WTRU may determine which carrier(s) to send SLSS based on the SCS of the carriers. In an example where the WTRU may determine which carrier to send SLSS based on the SCS of the carriers, the WTRU may be configured or pre-configured with a set of carriers for CA. For each configured or pre-configured SCS, the WTRU may perform SLSS transmission in at least one carrier. In some examples, the WTRU may determine to perform SLSS transmission in a carrier with the lowest SCS in a set of carriers configured or pre-configured for CA. In some examples, the WTRU may determine to perform SLSS transmission in a carrier with the highest SCS in a set of carriers configured or pre-configured for CA.

[0287] The WTRU may determine which carrier(s) to transmit SLSS based on the number of synchronization opportunities per synchronization period. In some examples, the WTRU may perform SLSS transmission in the carrier with the highest number of SLSS opportunities in the synchronization period. In some examples, the WTRU may perform SLSS transmission in the carrier with the least number of SLSS opportunities in the synchronization period.

[0288] The WTRU may determine which carrier(s) to send the SLSS based on the carrier type, which may include one or any combination of: a carrier pre-configured to the WTRU; a carrier shared with Uu; and / or a carrier indicated by the network. In an example, the carrier pre-configured to the WTRU may be an Intelligent Transport System (ITS) carrier.

[0289] The WTRU may determine which carrier(s) to send SLSS based on the carrier type used with Uu. For example, the WTRU may prioritize sending SLSS in a non-shared carrier with Uu.

[0290] In some solutions, the WTRU determines the synchronization occasion in which to send the sidelink synchronization signal. For example, in some solutions, the WTRU may determine which SLSS occasion to send SLSS in one carrier based on the configured or pre-configured SLSS occasions from other carriers. In some methods, the WTRU may prioritize sending SLSS in synchronization occasions with a smaller number of overlapping configured SLSS resources from other carriers. The method may be motivated to reduce power sharing of SLSS transmissions between carriers.

[0291] Fig.11 1100 is a resource diagram illustrating an example scenario in which a WTRU determines an SLSS opportunity during which to send an SLSS. In the example shown in resource diagram 1100, the WTRU may be configured or preconfigured with two carriers to send SLSS, where the synchronization periodicity and offset are the same between the two carriers. The WTRU may be configured or preconfigured with one SLSS opportunity per synchronization period for CC1 1120 and two SLSS opportunities per synchronization period for CC2 1160. For example, the WTRU may be configured or preconfigured with an SLSS opportunity 1122 for a first synchronization period, and an SLSS opportunity 1126 for a second synchronization period. In addition, the WTRU may be configured or preconfigured with SLSS opportunities 1162, 1164 for the first synchronization period, and SLSS opportunities 1166, 1168 for the second synchronization period. For CC2 1160, the WTRU may select an SLSS resource that does not overlap with the selected SLSS resource on CC1 1120 to send the SLSS. For example, since the WTRU selects SLSS resources 1122 , 1126 on CC1 1120 , the WTRU may select SLSS resources 1164 , 1668 for CC2 1160 that do not overlap with the selected SLSS resources 1122 , 1126 .

[0292] In some methods, the WTRU may send multiple SLSSs in a configured or pre-configured SLSS opportunity in a carrier. The WTRU may determine the number of SLSS opportunities to send based on the number of configured SLSS opportunities and the SLSS transmission status on another opportunity. Specifically, the WTRU may determine to send N SLSSs in one carrier per synchronization period. If one or more SLSSs are deprioritized, the WTRU may then increase the number of SLSSs to send. This may occur, for example, if the transmit power of the SLSSs in one carrier is reduced.

[0293] In some solutions, the WTRU may determine whether to perform SLSS transmission in N carriers simultaneously. For example, the WTRU may determine whether to perform SLSS transmission in N carriers simultaneously, where the N carriers may be configured or preconfigured for carrier aggregation. In some methods, if the transmission in the N carriers requires a power reduction in one or more prioritized carriers, the WTRU may determine not to transmit SLSS in all N carriers. In particular, the WTRU may be configured or preconfigured with a SLSS transmission priority for each carrier. The WTRU may then calculate the transmit power of the SLSS for each carrier. The WTRU may then determine whether to transmit the SLSS in one carrier based on whether the WTRU needs to reduce the transmit power of the SLSS in another carrier (e.g., a carrier with a higher SLSS priority). Specifically, if the transmission of the SLSS may result in a power reduction of the SLSS in one or more prioritized SLSSs, the WTRU may determine to reduce the transmit power of the non-prioritized SLSSs or discard the non-prioritized SLSSs.

[0294] In some solutions, the WTRU may perform prioritization between SLSS in different carriers. For example, in some solutions, the WTRU may be configured or pre-configured to potentially perform SLSS transmission in one or more carriers. The WTRU may determine which carrier to prioritize based on one or any combination of example parameters as may be described in the following paragraphs.

[0295] The WTRU may determine which carrier to prioritize based on the priorities associated with the carriers. For example, the WTRU may be configured or pre-configured with prioritization of SLSS resources associated with each carrier. The WTRU may then determine which SLSS to prioritize based on the priorities configured or pre-configured for the carriers.

[0296] The WTRU may determine which carrier to prioritize based on the received SLSS carriers. For example, the WTRU may prioritize SLSS transmissions in the carriers on which the WTRU received SLSS to reference the synchronization of the SLSS transmissions.

[0297] The WTRU may determine which carrier to prioritize based on the SCS associated with the carriers. In some examples, the WTRU may prioritize SLSS transmissions for carriers with lower SCS. In some examples, the WTRU may prioritize SLSS transmissions for carriers with higher SCS.

[0298] The WTRU may determine which carrier to prioritize based on the number of SLSS opportunities within the synchronization period configured in the carrier. In some examples, the WTRU may prioritize SLSS transmissions for carriers with a higher number of synchronization opportunities per synchronization period. In some examples, the WTRU may prioritize SLSS transmissions for carriers with a lower number of synchronization opportunities per synchronization period. In some examples, the WTRU may be configured or pre-configured to prioritize which carrier based on the SCS of the carrier (e.g., a carrier with a larger or smaller SCS). The WTRU may then determine which carrier to prioritize based on the SCS associated with the carrier and the configured or pre-configured prioritization rules.

[0299] The WTRU may determine which carrier to prioritize based on the transmit power associated with one or more carriers. In some examples, the WTRU may prioritize SLSSs with higher transmit power. In some examples, the WTRU may prioritize SLSSs with lower transmit power.

[0300] The WTRU may determine which carrier to prioritize based on carrier type, which may include one or any combination of: a carrier pre-configured to the WTRU (e.g., an ITS carrier); a carrier shared with Uu; and / or a carrier indicated by the network. In some examples, the WTRU may prioritize SLSS associated with a non-shared carrier with Uu. In some examples, the WTRU may prioritize SLSS associated with a shared carrier with Uu.

[0301] In some solutions, the WTRU may trigger the transmission of a sidelink synchronization signal in another carrier based on an indication from a peer WTRU. For example, in some solutions, the WTRU may determine to trigger SLSS transmission / reception in another carrier based on an indication from another WTRU. In particular, the WTRU may have a unicast / multicast connection with other WTRUs. In one method, the WTRU may instruct other WTRUs to establish a unicast / multicast session in another carrier. The WTRU may then trigger SLSS transmission / reception in the carrier. In another method, the WTRU may receive an indication from other WTRUs to establish a unicast / multicast session in another carrier. The WTRU may then trigger SLSS transmission / reception in the carrier. The WTRU may use PC5 radio resource control (RRC) signaling, MAC control element (CE) or SCI or any logically equivalent signal or message thereof to send / receive unicast / multicast establishment in another carrier.

[0302] The above embodiments, features and elements may be considered to include means for executing the methods and procedures described in the above examples. The means may include those known to those of ordinary skill in the art.

[0303] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method for use in a wireless transmit / receive unit (WTRU), the method comprising: Sure: One of: sending or receiving a first sidelink (SL) transmission using a first carrier using a first SL resource, and sending a second SL transmission using a second SL resource using a second carrier, wherein the second SL resource includes an overlapping period, and wherein the second SL resource overlaps with the first SL resource in the overlapping period; Using the second carrier to transmit at least a portion of the second SL transmission in a first symbol set of the second SL resource in the overlapping period, conditional on the overlapping period being in the last one or more symbols of the second SL resource, and not using the second carrier to transmit in a second symbol set of the second SL resource in the overlapping period; and One of the following is performed: sending or receiving the first SL transmission using the first carrier using the first SL resource in the overlapping period.

2. The method according to claim 1, wherein the first SL resource comprises a first time resource, wherein the second SL resource comprises a second time resource, and wherein the overlap period is in one or more symbols of the second time resource that temporally overlap with one or more symbols of the first time resource.

3. The method according to claim 1, wherein the first SL transmission is a physical sidelink feedback channel (PSFCH) transmission; and wherein the first SL resource is a PSFCH resource.

4. The method according to claim 1, wherein the second SL transmission is any one of a physical sidelink control channel (PSCCH) transmission, a physical sidelink shared channel (PSSCH) transmission, or a combination of a PSCCH transmission and a PSSCH transmission; and wherein the second SL resource is any one of a PSCCH resource, a PSSCH resource, or a combination of a PSCCH resource and a PSSCH resource.

5. The method according to claim 1, wherein using the second carrier in the first symbol set of the second SL resource in the overlapping period to send at least a part of the second SL transmission, and not using the second carrier in the second symbol set of the second SL resource in the overlapping period for transmission is perforation.

6. The method according to claim 1, wherein using the second carrier in the first symbol set of the second SL resource to send at least a part of the second SL transmission in the overlapping period, and not using the second carrier in the second symbol set of the second SL resource for transmission in the overlapping period is rate matching.

7. The method according to claim 1, further comprising: Under the condition that the overlapping period is earlier than the last one or more symbols of the second SL resource, one of the following is performed: based on the comparison of the priority associated with the first SL resource with the priority associated with the second SL resource, one of the transmission or the reception of the first SL transmission is discarded, or the transmission of the second SL transmission is discarded.

8. The method according to claim 1, further comprising: Information about the first set of symbols for the second SL resources and the second set of symbols for the second SL resources is sent to a receiving WTRU in sidelink control information (SCI).

9. The method according to claim 1, further comprising: A SL grant is received for sending resources for the second SL transmission using the second carrier.

10. The method according to claim 1, further comprising: Resources are selected for sending the second SL transmission using the second carrier.

11. A wireless transmit / receive unit (WTRU), comprising: processor; and a transceiver operatively coupled to the processor; wherein: The processor is configured to determine: One of: sending or receiving a first sidelink (SL) transmission using a first carrier using a first SL resource, and sending a second SL transmission using a second SL resource using a second carrier, wherein the second SL resource includes an overlapping period, and wherein the second SL resource overlaps with the first SL resource in the overlapping period; The transceiver is configured to use the second carrier to send at least a portion of the second SL transmission in the first symbol set of the second SL resource in the overlapping period, under the condition that the overlapping period is in the last one or more symbols of the second SL resource, and not use the second carrier to send in the second symbol set of the second SL resource in the overlapping period; and The transceiver is configured to do one of: transmit or receive the first SL transmission using the first carrier using the first SL resource in the overlapping period.

12. A WTRU according to claim 11, wherein the first SL resource includes a first time resource, wherein the second SL resource includes a second time resource, and wherein the overlapping period is in one or more symbols of the second time resource that overlap in time with one or more symbols of the first time resource.

13. The WTRU of claim 11, wherein the first SL transmission is a physical sidelink feedback channel (PSFCH) transmission; and wherein the first SL resource is a PSFCH resource.

14. The WTRU according to claim 11, wherein the second SL transmission is any one of a physical sidelink control channel (PSCCH) transmission, a physical sidelink shared channel (PSSCH) transmission, or a combination of a PSCCH transmission and a PSSCH transmission; and wherein the second SL resource is any one of a PSCCH resource, a PSSCH resource, or a combination of a PSCCH resource and a PSSCH resource.

15. A WTRU according to claim 11, wherein using the second carrier in the first symbol set of the second SL resource to send at least a portion of the second SL transmission in the overlapping period, and not using the second carrier in the second symbol set of the second SL resource for transmission in the overlapping period is perforation.

16. A WTRU according to claim 11, wherein using the second carrier in the first symbol set of the second SL resource to send at least a portion of the second SL transmission in the overlapping period, and not using the second carrier in the second symbol set of the second SL resource for transmission in the overlapping period is rate matching.

17. A WTRU according to claim 11, wherein the transceiver is further configured to perform one of the following: discard one of the transmission or the reception of the first SL transmission, or discard the transmission of the second SL transmission based on a comparison of the priority associated with the first SL resource with the priority associated with the second SL resource, under the condition that the overlapping period is earlier than the last one or more symbols of the second SL resource.

18. The WTRU of claim 11, wherein the transceiver is further configured to send information about the first symbol set of the second SL resource and the second symbol set of the second SL resource to a receiving WTRU in a sidelink control information (SCI).

19. The WTRU of claim 11, wherein the transceiver is further configured to receive a SL grant for transmitting resources for the second SL transmission using the second carrier.

20. The WTRU of claim 11, wherein the processor is further configured to select resources for sending the second SL transmission using the second carrier.

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