Carrier selection

Abstract

A WTRU may receive configuration information indicating a restriction associated with selecting a carrier for carrier aggregation (CA). The WTRU may select a set of carriers for a sidelink CA. The WTRU may receive a message from a peer WTRU to establish a unicast link. The message indicates a set of potential carriers for the unicast link. The WTRU may determine a set of carriers for the unicast link based on the configured restriction associated with selecting the carrier for CA and / or the set of potential carriers. The WTRU may send, based on the set of carriers having at least one carrier, the set of carriers for the unicast communication to the peer WTRU.

Description

CARRIER SELECTIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 531 ,122 filed on August 7, 2023, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] Long term evolution (LTE) vehicle-to-everything (V2X) may support one subcarrier spacing (SCS) of 15 KHz for all carriers. For carrier aggregation, all the aggregated carriers may have the same synchronization configuration. All the aggregated carriers may be synchronized.

[0003] Multicarrier may currently be specified for new radio (NR) sidelink (SL). Multicarrier may be expected to use LTE as a baseline, while potentially considering some differences to account for unicast transmission in NR. Many restrictions in configuration may be imposed to simplify the design. For example, the imposed restrictions in configuration may include the same configuration of SCS, physical sidelink feedback channel (PSFCH), and / or sidelink synchronization signal block (S-SSB) across all carriers.

[0004] Multicarrier operation in NR sidelink evolution (SLE) may need to consider different transmission duration of various transmission channels (e.g., physical sidelink control channel (PSCCH) and / or physical sidelink shared channel (PSSCH) and / or physical sidelink feedback channel (PSFCH)) and / or the same channel in different carriers with different SCSs. NR SLE may also aggregate multiple carriers with various synchronization configurations due to operation band and / or the desired latency of packet delivery (e.g., the network may configure a larger SCS for targeting the lower latency requirement services).SUMMARY

[0005] A wireless transmit / receive unit (WTRU) may receive configuration information indicating a restriction associated with selecting a carrier for carrier aggregation. The WTRU may select a set of carriers for a sidelink carrier aggregation (CA). The WTRU may receive a message from a peer WTRU to establish a unicast link. The message indicates a set of potential carriers for the unicast link. The WTRU may determine a set of carriers for the unicast link based on the configured restriction associated with selecting the carrier for CA and / or the set of potential carriers. The WTRU may send, based on the set of carriers having at least one carrier, the set of carriers for the unicast communication to the peer WTRU.

[0006] The restriction associated with selecting a carrier for CA comprises one or more of a maximum number of carriers for CA, a frequency band, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, or a configured resource selection type.

[0007] The resource selection type may include a resource pool configured with one or more of full sensing, partial sensing, and / or random resource allocation.

[0008] The configuration information may include a prioritization associated with selecting a carrier for CA.

[0009] The prioritization associated with selecting a carrier for CA may include one or more of a frequency band for the currently selected carrier, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, a carrier adjacent to the currently selected carrier, and / or a configured resource selection type.

[0010] The WTRU may send an additional set of carriers for the unicast communication to the peer WTRU. The additional set of carriers may be based on the restriction and prioritization associated with selecting a carrier for CA.

[0011] The WTRU may determine, prior to sending the set of carriers for the unicast communication to the peer WTRU, a set of one or more carriers to perform broadcast services.

[0012] The WTRU may send, based on having no carriers for the unicast communication, a unicast link connect rejection to the peer WTRU. The WTRU may release a set of one or more established carriers to select another carrier for a new unicast link. The WTRU may select one or more potential carriers from the released set of one or more established carriers.

[0013] The WTRU may send an indication to the peer WTRU, the indication comprising the released set of one or more established carriers.

[0014] The WTRU may be sent using a PC5 radio resource control (RRC) unicast message.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0016] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0017] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0018] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0019] FIG. 2 is a diagram illustrating an example of WTRU selection of control channel 3 (CC3) to receive in a newly established unicast link to avoid an automatic gain control (AGC) reception issue.DETAILED DESCRIPTION

[0020] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0021] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or a “STA”, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0022] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the I nternet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AR), 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.

[0023] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of 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 transmit and / or receive signals in desired spatial directions.

[0024] 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).

[0025] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0026] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0027] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., a eNB and a gNB).

[0029] 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), and the like.

[0030] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 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 orfemtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0031] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide 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), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0033] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0034] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, aspeaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0036] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0037] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0038] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0039] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 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 the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0040] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0041] 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 over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0042] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0043] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g, for transmission) or the downlink (e.g, for reception)).

[0044] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0045] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0046] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0047] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0048] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0049] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0050] 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.

[0051] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0052] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0053] In representative embodiments, the other network 112 may be a WLAN.

[0054] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the APto be delivered to respective destinations. Traffic between ST As within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11 e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (I BSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad- hoc” mode of communication.

[0055] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0056] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0057] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0058] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e. g . , only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0059] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a ST A, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0060] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0061] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0062] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b,180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0066] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 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.

[0068] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0069] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0070] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0071] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0072] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may performing testing using over-the-air wireless communications.

[0073] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, theemulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0074] A wireless transmit / receive unit (WTRU) may determine a set of carriers for collaborative sensing. The WTRU may detect a potential transmission overlapping and / or having different starting and / or ending symbol with its reserved resource. The WTRU may perform automatic gain control (AGC)-issue avoidance procedure. The WTRU may determine whether to trigger resource allocation or puncture and / or ratematch the overlapping duration. The WTRU may exclude the resource overlapping with the reservation from other WTRU. The WTRU may perform a logical channel prioritization (LCP) procedure to determine which logical channel (LCH) to multiplex the transport block (TB). The WTRU may determine whether to enable / disable hybrid automatic repeat request (HARQ) feedback. The WTRU may be configured with a set of restrictions for carrier selection. The WTRU may select a set of carriers for the unicast link. The WTRU may indicate which carrier to feedback physical sidelink feedback channel (PSFCH) for each physical sidelink control channel (PSCCH) and / or physical sidelink shared channel (PSSCH). The WTRU may determine which carrier to feedback PSFCH for an associated PSCCH and / or PSSCH. The WTRU may request another WTRU to send sensing information for the set of carriers. The WTRU may select a carrier based on the sensing information reported from other WTRU. The WTRU may determine the priority associated with sidelink synchronization signal block (S-SSB) transmission per carrier. The WTRU may determine the potential transmission power of S-SSB in each carrier in each S-SSB occasion. The WTRU may determine whether to transmit S-SSB in each carrier in one configured S-SSB occasion. The WTRU may determine the number of S-SSB repetition per S-SSB occasion.

[0075] Long term evolution (LTE) vehicle-to-everything (V2X) may support one subcarrier spacing (SCS) of 15 KHz for all carriers. For carrier aggregation, all the aggregated carriers may have the same synchronization configuration. All the aggregated carriers may be synchronized.

[0076] Multicarrier may currently be specified for new radio (NR) sidelink (SL). Multicarrier may be expected to use LTE as a baseline, while potentially considering some differences to account for unicast transmission in NR. Many restrictions in configuration may be imposed to simplify the design. For example, the imposed restrictions in configuration may include the same configuration of SCS, physical sidelink feedback channel (PSFCH), and / or sidelink synchronization signal block (S-SSB) across all carriers.

[0077] Multicarrier operation in NR Sidelink Evolution (SLE) may need to consider different transmission duration of various transmission channels (e.g., physical sidelink control channel (PSCCH) and / or physical sidelink shared channel (PSSCH) and / or physical sidelink feedback channel (PSFCH) and / or the same channel in different carriers with different SCSs. NR SLE may also aggregate multiple carriers with various synchronization configurations due to operation band and the desired latency of packet delivery (e.g., the network may configure a larger SCS for targeting the lower latency requirement services).

[0078] For carrier aggregation, the receive (Rx) wireless transmit / receive unit (WTRU) may perform automatic gain control (AGC) convergence over multiple carriers. While a Rx WTRU is receiving a channel (e.g., PSCCH and / or PSSCH), and another WTRU transmitting may be in the middle of its reception. In such case, the receiving channel may be affected, and / or the WTRU may fail to decode the channel. AGC issues may severely affect the reliability of the packet reception, e.g., in the system with non-synchronized and various transmission in multiple carriers.

[0079] Moreover, due to limited reception capability and / or imbalance in transmit (Tx) and / or Rx carriers, a WTRU may not be able to transmit and / or receive in the same set of carriers. Therefore, it may be desirable to support cross carrier feedback, wherein the WTRU may feedback in a different carrier compared to the associated data. Directions on how to perform carrier selection for HARQ feedback may be needed.

[0080] Moreover, due to limited sensing capability and / or imbalance in Tx and / or Rx carriers, the WTRU may not be able to sense a carrier before carrier selection. However, the WTRU may be able to take advantage of the surrounding WTRU (e.g., via inter WTRU coordination (IUC)) to decide carrier reselection properly. The design to enable such a WTRU to support another WTRU in carrier selection may be considered.

[0081] Directions on how to design a synchronization procedure may be provided for multi-carrier. These directions may ensure a proper synchronization coverage of all carriers considering different SCS and / or synchronization configuration in different carriers.

[0082] The terms “resource allocation”, “pre-emption”, and “resource re-evaluation” may be used interchangeably herein. The terms “resource allocation”, “pre-emption”, and “resource re-evaluation” may describe the procedure to identify whether a preselected resource and / or a reserved resource can identify the available resources for transmission. The preselected resource and / or a reserved resource may make this identification by performing sensing and / or extracting a sensing result.

[0083] The WTRU may refers to a WTRLI that receives configuration from the gNB (e.g., via dedicated radio resource control (RRC) signaling and / or a system information block (SIB)) and / or the WTRU preconfigured with information (e.g., a threshold).

[0084] For carrier aggregation, the Rx WTRU may perform AGC convergence over multiple carriers. While the WTRU is receiving a channel (e.g., PSCCH and / or PSSCH), the receiving channel may be affected and may fail to decode the channel, e.g., if another WTRU transmitting in the middle of its reception. Carrier selection and / or resource allocation for multiple carriers consider AGC problem.

[0085] A WTRU may perform pre-emption checking to determine whether its reserved PSCCH and / or PSSCH resource and / or associated PSFCH overlaps and have different starting and / or ending symbols with the reserved resource from other WTRU in one carrier. The WTRU may determine whether to puncture and / or ratematch the overlapping symbols of PSCCH and / or PSSCH or reselect another resource based on the overlapping duration. The WTRU may determine whether to transmit hybrid automatic repeat request (HARQ) enabled / disabled transport block (TB) based on whether the associated PSFCH occasion overlaps and has different starting and / or ending symbol with a reserved physical sidelink control channel (PSCCH) and / or physical sidelink shared channel (PSSCH) or the associated PSFCH of another WTRU from a carrier.

[0086] A WTRU may determine the set of carriers to receive and / or transmit for a unicast link based on the SCS and / or the PSFCH configuration associated with the carrier. The WTRU may indicate the determined set of carriers to the peer WTRU.

[0087] The WTRU (e.g., Rx WTRU) may be configured to perform the following. The WTRU may be configured with a restriction to select a carrier for carrier aggregation (CA). The restriction to select a carrier for CA may include one or more of a maximum number of carriers (e.g., a number N) for CA, frequency band, SCS and / or PSFCH configuration, and / or configured resource selection type (e.g., full sensing, partial sensing, random). The WTRU may have established and / or selected a set of carriers for sidelink CA. The WTRU may receive a PC5 establishment message from a peer WTRU to establish a unicast link. This PC5 establishment message may indicate the set of potential carriers and / or associated configurations for the unicast link.

[0088] The WTRU may determine the set of carriers to receive and / or transmit for the unicast link based on the configured carrier selection restriction and / or prioritization. For example, the WTRU may first restrict the carrier in the same band with one of the established and / or selected carriers. Then the WTRU may restrict the carrier with the same SCS and / or PSFCH configuration with one of the established and / orselected carriers. Then the WTRU may restrict the full sensing carrier RA until the maximum number of carriers (e.g., a number N) for CA is reached. The WTRU may send the set of carriers for the unicast communication to the peer WTRU if the set has at least one carrier. Otherwise, the WTRU may reject the link connection with the peer WTRU.

[0089] The WTRU may be configured with a set of restrictions for carrier selection. In examples, the WTRU may be configured with one or any combination of the following restrictions to select one or more carriers for carrier aggregation: for example, he WTRU may be configured with the maximum number of carriers (e.g., a number N) for carrier aggregation.

[0090] The WTRU may be configured with the frequency band. For example, the WTRU may select an additional carrier in the same frequency band with one carrier in the set of already established / selected carriers.

[0091] The WTRU may be configured with SCS and / or PSFCH configuration, to select an additional carrier having the same SCS as one of the established and / or selected carriers. The WTRU may select an additional carrier having the same SCS and / or PSFCH configuration (e.g., the offset and periodicity of PSFCH occasion) with one of the already established and / or selected carriers. This approach may assist the WTRU in avoiding the AGC issue in the set of receiver carriers.

[0092] The WTRU may be configured with configured resource selection types (e.g., full sensing, partial sensing, and / or random) in the carrier for carrier prioritization. For example, the WTRU may be restricted to select carriers having a resource pool configured with full sensing. The WTRU may select carriers having a resource pool configured with full sensing and / or partial sensing. The WTRU be restricted to select a carrier having a resource pool configured with random resource allocation.

[0093] The WTRU may be configured with a prioritization order for carrier selection. In examples, the WTRU may be configured with one or more prioritizations to select another carrier for carrier aggregation. For example, the prioritization to select another carrier for carrier aggregation may include the frequency band of the already established and / or selected carrier, SCS and / or PSFCH configuration, the adjacent carrier with the already established and / or selected carrier, and / or configured resource selection type (e.g., full sensing, partial sensing, and / or random) in the carrier for carrier prioritization.

[0094] In examples, if the number of indicated carriers exceeds the maximum number of carriers for carrier aggregation, the WTRU may first prioritize the carrier in the same frequency band with one or more of the established carriers. The WTRU may further prioritize the carriers having the same SCS and / orPSFCH configuration with one or more of the established and / or selected carriers. If the number of remaining carriers is still greater than the maximum number of carriers for carrier aggregation, the WTRU may prioritize the carrier adjacent to one or more of the already established and / or selected carriers. The WTRU may prioritize the carrier configured with full sensing following by prioritizing the carrier configured with partial sensing.

[0095] The WTRU may establish a set of carriers for CA. In examples, the WTRU may sequentially establish one or more carriers to initialize one or more services. Specifically, the WTRU may first establish one or more carriers for broadcast services. Therein, the set of carriers used for the broadcast service may initiate one or more unicast and / or group cast service.

[0096] The WTRU may receive a request connection establishment from the peer WTRU. In examples, the WTRU may receive a request for unicast connection establishment. The request may indicate the set of potential carriers and associated configuration (e.g., SCS, PSFCH configuration, and / or resource selection type) for the unicast communication.

[0097] The WTRU may select a set of carriers for the unicast link. The WTRU may then select the set of carriers from the set of indicated carriers for unicast communication. The WTRU may then send the set of selected carriers to the connection requesting WTRU if the connection requesting WTRU has at least one carrier in the set of selected carriers. The WTRU may then select the set of carriers from the set of indicated carriers based on the set of established and / or selected carriers. Specifically, the WTRU may prioritize the already established and / or selected carrier in the set of indicated carriers. In case there is no established and / or selected carrier in the set of indicated carriers, the WTRU may select additional carriers to establish for unicast communication.

[0098] In examples, the WTRU may select the set of additional carriers for unicast communication based on the configured carrier selection restriction and / or prioritization. For example, the WTRU may first restrict the carrier in the same band with one of the established / selected carriers. The WTRU may then restrict the carriers with the same SCS and / or PSFCH configuration with one of the established and / or selected carriers. The WTRU may then restrict the full sensing carrier RA until the maximum number of carriers (e.g., a number N) for CA is reached. This approach may assist the WTRU avoid the AGC issue if the WTRU selects multiple carriers with different SCS and / or PSFCH configurations.

[0099] In examples, the WTRU may not have a carrier for unicast communication. Under such circumstances, the WTRU may perform one or any combination of the following procedures. For example,he WTRU may send a unicast link connection reject to the peer WTRU. The peer WTRLI may stop the connection establishment procedure between two WTRUs.

[0100] The WTRU may release one or more of the established and / or selected carriers. For example, the WTRU may release one or more of the established and / or selected carriers to select another carrier for the new unicast link. For example, the WTRU may have established and / or selected multiple carriers for one unicast link. In one approach the WTRU may release a subset of carriers in the set of established and / or selected carriers for the unicast link. The WTRU may send a message to the peer WTRU (e.g., PC5 RRC unicast re-establishment message). In the message, the WTRU may indicate the set of released carriers. Alternatively, the WTRU may indicate the new set of carriers for the unicast link communication. In another example, the WTRU may release the established unicast link.

[0101] The WTRU may reselect one or more carriers in the set of established / selected carriers. For example, the WTRU may select one or more carriers from the set of indicated carrier to replace one or more carriers in the set of established and / or selected carriers. The WTRU may indicate the new set of carriers to the peer WTRU in the already established unicast link for future unicast communication. The WTRU may send the indication using PC5 radio resource control (RRC) unicast message.

[0102] FIG. 2 depicts an example WTRU selection 200 to receive and / or transmit in a newly established unicast link to avoid AGC reception issue. As shown in FIG. 2, the WTRU may be indicated from the peer WTRU with four potential carriers for unicast communication with the peer WTRU, featured as CC2, CC3, CC4, and CC5 202b-e. CC2 and CC3 202b-c may be in Bandl 204a. CC4 and CC5 202d-e may be in Band2 204b. The WTRU may have CC1 202a as the already established carrier in Bandl 204a. The WTRU may apply the first restriction to select the component carrier in the same band with the already established component carrier. Therefore, the WTRU may select potential CC2 and / or CC3 202b-c for potential unicast communication. Finally, the WTRU may apply the SCS and / or PSFCH configuration restriction to select the component carrier having the same configuration with the already established CC1 202a and select CC3 202c as a potential component carrier for unicast communication. The WTRU may then indicate the selected CC3 202c to the peer WTRU to begin the unicast communication.

[0103] Due to limited transmission capability, a WTRU may not be able to transmit in all the Rx carriers. Therefore, it may be beneficial to configure cross-carrier feedback. In cross-carrier feedback, the WTRU may feedback PSFCH in different carrier compared to PSCCH and / or PSSCH. Assuming that a Rx WTRU may have multiple carriers to feedback PSFCH, the WTRU may select the carrier to feedback PSFCH as described herein.

[0104] A WTRU (e.g., Rx WTRU) may determine which carrier to transmit PSFCH based on a configured or preconfigured criteria (e.g., the carrier of PSFCH associated with another PSCCH and / or PSSCH with higher priority).

[0105] The WTRU (e.g., source WTRU) may be configured with a mapping of one PSCCH and / or PSSCH resource to multiple PSFCH resources in multiple carriers. The WTRU may receive one HARQ enabled PSCCH and / or / PSSCH in one carrier. The WTRU may determine which carrier to feedback PSFCH based on one or more of the carriers having the earliest PSFCH occasion, carrier of a PSFCH associated with another PSCCH and / or PSSCH, channel busy ratio (CBR) of the resource pool, transmission power of PSFCH in the carrier, carrier having reserved PSCCH and / or PSSCH resource, and / or carrier of the dropped PSFCH (e.g., if the WTRU select a carrier for a second PSFCH). The WTRU may transmit PSFCH feedback in an associated PSFCH resource of the selected carrier.

[0106] The Rx WTRU may have limited Rx capability. The Rx WTRU may not be able to measure one or more (e.g., all) carriers. IUC may assist one WTRU aware of a non-monitored carrier by requesting another WTRU to report the channel condition in the carrier. The WTRU may use IUC for carrier selection and / or reselection as described herein.

[0107] A WTRU (e.g., Tx WTRU) may request another WTRU (e.g., peer WTRU) to transmit IUC for carrier reselection. Upon reception of IUC from the peer WTRU, the WTRU may determine which carrier to select based on one of the parameters (e.g., RSRP threshold to obtain X% resources) indicated in the IUC message. The WTRU may transmit an indicated resource in the selected carrier.

[0108] A WTRU (e.g., Tx WTRU) may perform transmission in one carrier. The WTRU may trigger carrier reselection. The WTRU may send a request for another WTRU (e.g., peer WTRU in unicast) to report IUC for carrier reselection. The request may include one or more of indication of IUC type (e.g., for carrier reselection), the set of potential carriers, and / or the carrier evaluation parameters (e.g., percentage of available resources, RSRP threshold to have X% of resources, CBR). The WTRU may receive IUC message from the peer WTRU. The IUC message may include one or more of the percentage and / or number of the available resources in each indicated carrier, the RSRP threshold to have X% resource, CBR of one resource pool in each carrier, and / or a set of preferred resources in each carrier.

[0109] The WTRU may select a carrier based on one of the carrier evaluation parameters IUC report from the peer WTRU. For example, the WTRU may select the carrier with the lowest CBR reported from the peer WTRU. Alternatively, the WTRU may select the carrier with the highest percentage / number of available resources reported from the peer WTRU. The WTRU may select the carrier with the lowestRSRP threshold to have X% of resource. Moreover, the WTRLI may select and transmit data on one of the indicated resources in the selected carrier.

[0110] When the WTRU is required to transmit S-SSB in multiple carriers, power sharing may affect the coverage of S-SSB in each carrier. Designing the S-SSB transmission procedure to maintain the coverage of S-SSB in each carrier is described herein.

[0111] A WTRU may determine whether to transmit a S-SSB on one occasion of a carrier based on the set of carriers having S-SSB resource in the occasion and / or the associated S-SSB priority. The WTRU may then determine the number of repetitions to transmit S-SSB on one occasion based on the determined transmission power and the configured number of S-SSB repetitions per power level.

[0112] A WTRU may be configured with the set of carriers for S-SSB transmission carrier aggregations. The WTRU may be configured with coverage requirements of S-SSB per carrier (e.g., the number of S- SSB repetitions per transmission power level). The WTRU may be configured with the minimum transmission power for S-SSB per carrier. The WTRU may determine the priority of S-SSB based on the SCS associated with the carrier.

[0113] For each synchronization occasions, the WTRU may determine which set of carriers to transmit based on the minimum transmission power of S-SSB in each carrier and the priority of S-SSB in each carrier. For example, the WTRU may sequentially allocate power for S-SSB in the descending order of priority. The WTRU may determine the number of S-SSB repetitions in each carrier based on the determined transmission power and / or the minimum required transmission power. For example, if the transmission power is smaller than a first threshold, the WTRU may transmit two S-SSBs. If the transmission power is smaller than a second threshold, the WTRU may transmit 4 S-SSBs. The WTRU may perform synchronization transmission in the set of determined S-SSB resources in the set of selected carriers for synchronization transmission.

[0114] A wireless transmit / receive unit (WTRU) may transmit a request to a second WTRU to send an inter-WTRU coordination (IUC) message for carrier reselection. The WTRU may receive the IUC message from the second WTRU. The IUC message from the second WTRU may comprise one or more of a percentage of available resources in each carrier available for reselection, a reference signal received power (RSRP) threshold, a channel busy ratio (CBR) in each carrier available for reselection, and / or a set of preferred resources in each carrier available for reselection. The WTRU may select a new carrier based on the one or more percentage of available resources in each carrier, a RSRP threshold, a CBR in each carrier, and / or a set of preferred resources in each carrier reported in the IUC message from the secondWTRU. The WTRU may transmit data on the available resources or preferred resources in the selected new carrier.

[0115] The WTRU may request to a second WTRU to send the IUC message is transmitted using sidelink control information (SCI), medium access control (MAC) control element (CE), or PC5 radio resource control (RRC).

[0116] The first WTRU may be preconfigured with one or more IUC request types, and / or the request to the second WTRU comprises an indication of the IUC request type.

[0117] The one or more IUC request types comprises a request to determine for carrier reselection and / or a request for resource allocation.

[0118] The selected new carrier has the lowest CBR, the highest percentage and / or number of available resources, or the lowest RSRP threshold of all the carriers available for reselection.

[0119] The selected new carrier may have a CBR lower than a preconfigured threshold.

[0120] The first WTRU may determine which carriers to request sensing information based on the set of carriers configured for a service which triggers reselection or a set of already established carriers.

[0121] The first WTRU may be preconfigured with one or more indication parameters. The one or more indication parameters may indicate which of the one or more of a percentage of available resources in each carrier, a reference signal received power (RSRP) threshold, a channel busy ratio (CBR) in each carrier, and / or a set of preferred resources in each carrier to include in the request to the second WTRU to send the IUC message.

[0122] The one or more indication parameters may comprise a resource selection window, a sensing window, a priority associated with resource selection, and / or a received signal strength indicator (RSSI) threshold.

[0123] The one or more indication parameters may further comprise an indication of the starting slot, ending slot, and / or duration of the resource selection window to include in the request to the second WTRU to send the IUC message

Claims

CLAIMS:What is claimed is:1 . A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information indicating a restriction associated with selecting a carrier for carrier aggregation (CA); selecting a set of carriers for a sidelink CA; receiving a message from a peer WTRU to establish a unicast link, wherein the message indicates a set of potential carriers for the unicast link; determining a set of carriers for the unicast link based on the configured restriction associated with selecting the carrier for CA and the set of potential carriers; and sending, based on the set of carriers having at least one carrier, the set of carriers for the unicast communication to the peer WTRU.

2. The method of claim 1 , wherein the restriction associated with selecting a carrier for CA comprises one or more of a maximum number of carriers for CA, a frequency band, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, or a configured resource selection type.

3. The method of claim 2, wherein the configured resource selection type comprises a resource pool configured with one or more of full sensing, partial sensing, or random resource allocation.

4. The method of claim 1 , wherein the configuration information further comprises a prioritization associated with selecting a carrier for CA.

5. The method of claim 4, wherein the prioritization associated with selecting a carrier for CA comprises one or more of a frequency band for the currently selected carrier, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, a carrier adjacent to the currently selected carrier, or a configured resource selection type.

6. The method of claim 4, further comprising:sending an additional set of carriers for the unicast communication to the peer WTRU, wherein the additional set of carriers are based on the restriction and prioritization associated with selecting a carrier for CA.

7. The method of claim 1 , further comprising: determining, prior to sending the set of carriers for the unicast communication to the peer WTRU, a set of one or more carriers to perform broadcast services.

8. The method of claim 1 , further comprising: sending, based on having no carriers for the unicast communication, a unicast link connect rejection to the peer WTRU; releasing a set of one or more established carriers to select another carrier for a new unicast link; and selecting one or more potential carriers from the released set of one or more established carriers.

9. The method of claim 8, further comprising: sending an indication to the peer WTRU, the indication comprising the released set of one or more established carriers.

10. The method of claim 9, wherein the indication is sent using a PC5 radio resource control (RRC) unicast message.

11. A wireless transmit / receive unit (WTRU) comprising a processor and a memory, the processor and memory configured to: receive configuration information indicating a restriction associated with selecting a carrier for carrier aggregation (CA); select a set of carriers for a sidelink CA; receive a message from a peer WTRU to establish a unicast link, wherein the message indicates a set of potential carriers for the unicast link;determine a set of carriers for the unicast link based on the configured restriction associated with selecting the carrier for CA and the set of potential carriers; and send, based on the set of carriers having at least one carrier, the set of carriers for the unicast communication to the peer WTRU.

12. The WTRU of claim 11 , wherein the restriction associated with selecting a carrier for CA comprises one or more of a maximum number of carriers for CA, a frequency band, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, or a configured resource selection type.

13. The WTRU of claim 12, wherein the configured resource selection type comprises a resource pool configured with one or more of full sensing, partial sensing, or random resource allocation.

14. The WTRU of claim 11 , wherein the configuration information further comprises a prioritization associated with selecting a carrier for CA.

15. The WTRU of claim 14, wherein the prioritization associated with selecting a carrier for CA comprises one or more of a frequency band for the currently selected carrier, a subcarrier spacing (SCS) and physical sidelink feedback channel (PSFCH) configuration, a carrier adjacent to the currently selected carrier, or a configured resource selection type.

16. The WTRU of claim 14, the processor and memory further configured to: send an additional set of carriers for the unicast communication to the peer WTRU, wherein the additional set of carriers are based on the restriction and prioritization associated with selecting a carrier for CA.

17. The WTRU of claim 11 , the processor and memory further configured to: determine, prior to sending the set of carriers for the unicast communication to the peer WTRU, a set of one or more carriers to perform broadcast services.

18. The WTRU of claim 11 , the processor and memory further configured to:send, based on having no carriers for the unicast communication, a unicast link connect rejection to the peer WTRU; release a set of one or more established carriers to select another carrier for a new unicast link; and select one or more potential carriers from the released set of one or more established carriers.

19. The WTRU of claim 18, the processor and memory further configured to: send an indication to the peer WTRU, the indication comprising the released set of one or more established carriers.

20. The WTRU of claim 19, wherein the indication is sent using a PC5 radio resource control (RRC) unicast message.

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