WO2025034835A1

WO2025034835A1 - Transmissions based on aggregation and quality of service

Info

Publication number: WO2025034835A1
Application number: PCT/US2024/041256
Authority: WO
Inventors: Tuong Duc HOANG; Tao Deng; Jaya Rao; Loic CANONNE-VELASQUEZ; Martino M. Freda; Jongwoo HONG; Benoit Pelletier; Ghyslain Pelletier; Virgile Garcia
Original assignee: InterDigital Patent Holdings Inc
Current assignee: InterDigital Patent Holdings Inc
Priority date: 2023-08-07
Filing date: 2024-08-07
Publication date: 2025-02-13
Anticipated expiration: 2026-02-07

Abstract

Described herein are systems, methods, and instrumentalities associated with aggregated transmissions. A wireless transmit/receive unit (WTRU) (e.g., a source WTRU) as described herein may be configured to receive configuration information from a network device, wherein the configuration information may indicate a first assistant WTRU associated with the source WTRU and an aggregated transmission scheme for transmitting one or more protocol data units (PDUs) associated with the source WTRU via at least the first assistant WTRU. The source WTRU may be further configured to receive a grant of resources from the network device and determine whether to transmit the PDU using the aggregated transmission scheme. Based on a determination to transmit the PDU using the aggregated transmission scheme, the source WTRU may send at least a first portion of the PDU and a first indication of the granted resources to the first assistant WTRU.

Description

TRANSMISSIONS BASED ON AGGREGATION AND QUALITY OF SERVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/531 ,241 , filed August 7, 2023, the content of which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Mobile applications are expanding in many directions, such as, e.g., extended reality (XR), industrial internet of things (loT), intelligent transportation system, and so on. These applications impose requirements on resources and power efficiency that a conventional cellular network may not be able to meet.

SUMMARY

[0003] Described herein are systems, methods, and instrumentalities associated with aggregated transmissions. A wireless transmit/receive unit (WTRU) (e.g., a source WTRU) as described herein may be configured to receive configuration information from a network device, wherein the configuration information may indicate a first assistant WTRU associated with the source WTRU and an aggregated transmission scheme for transmitting one or more protocol data units (PDUs) associated with the source WTRU via at least the first assistant WTRU. The source WTRU may be further configured to receive a grant of resources from the network device and determine whether to transmit the PDU using the aggregated transmission scheme. Based on a determination to transmit the PDU using the aggregated transmission scheme, the source WTRU may send at least a first portion of the PDU and a first indication of the granted resources to the first assistant WTRU.

[0004] In examples, the configuration information received by the source WTRU from the network device may further indicate a second assistant WTRU associated with the source WTRU, and the source WTRU may be further configured to, based on the determination to transmit the PDU using the aggregated transmission scheme, send a second portion of the PDU and a second indication of the granted resources to the second assistant WTRU. In examples, based on the determination to transmit the PDU using the aggregated transmission scheme, the source WTRU may be further configured to transmit a second portion of the PDU using the granted resources.

[0005] In examples, the source WTRU may be further configured to send an indication of the aggregated transmission scheme to the first assistant WTRU. In examples, the source WTRU may be further configured to send an indication of a transmission parameter associated with the PDU to the first assistant WTRU, wherein the transmission parameter may indicate a transmission beam, a transmission power, a modulation and coding scheme (MTS), or a hybrid automatic repeat request (HARQ) redundancy version (RV) associated with the PDU.

[0006] In examples, the configuration information received by the source WTRU from the network device may further indicate a set of transmission parameters associated with the aggregated transmission scheme. In examples, the determination of whether to transmit the PDU using the aggregated transmission scheme may be made based at least on a quality of service (QoS) requirement associated with a PDU. For instance, the QoS requirement may indicate that the PDU is associated with a radio bearer or a logical channel for which the aggregated transmission scheme is enabled. In examples, the configuration information received from the network device may further indicate the QoS requirement.

[0007] In examples, the configuration information received by the source WTRU from the network device may indicate a plurality of assistant WTRUs associated with the source WTRU, and the source WTRU may be configured to select the first assistant WTRU from the plurality of assistant WTRUs based on a quality of service requirement associated with the PDU or a power headroom associated with the first assistant WTRU.

[0008] In examples, the source WTRU may be configured to receive the grant of resources via a downlink control information (DCI) message, wherein the DCI message may further indicate that the grant is associated with the aggregated transmission scheme.

[0009] In examples, the configuration information received by the source WTRU from the network device may further indicate a HARQ retransmission scheme associated with the aggregated transmission scheme, and the source WTRU may be further configured to re-transmit the PDU using the HARQ retransmission scheme. In examples, the aggregated transmission scheme described herein may be based on single frequency network (SFN) combining.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments can be implemented.

[0011] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that can be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0012] FIG. 1 C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that can be used within the communications system illustrated in FIG. 1 A according to an embodiment. [0013] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that can be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0014] FIG. 2 is a diagram illustrating examples of a source WTRU and an assistant WTRU that may form a group of WTRUs to perform an aggregated uplink transmission.

[0015] FIG. 3 is a diagram illustrating examples of two assistant WTRUs that may form a group of WTRUs to perform an aggregated uplink transmission of a PDU associated with a source WTRU.

[0016] FIG. 4 is a diagram illustrating examples of transmission modes associated with a PDU of a source WTRU.

[0017] FIG. 5 is a diagram illustrating examples of transmission patterns for aggregation-based transmissions.

[0018] FIG. 6 is a diagram illustrating an example of a group coordinator WTRU sending group scheduling coordination information (GSCI) to a base station regarding the resource usage of a WTRU group.

[0019] FIG. 7 is a diagram illustrating an example of a configured grant for an aggregation-based transmission.

DETAILED DESCRIPTION

[0020] A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0021] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments can be implemented. The communications system 100 can be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 can enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 can 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), singlecarrier 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.

[0022] As shown in FIG. 1A, the communications system 100 can 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 can 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 can be referred to as a “station” and/or a “ST A”, can be configured to transmit and/or receive wireless signals and can include a user equipment (WTRU), 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 can be interchangeably referred to as a WTRU.

[0023] The communications systems 100 can include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b can 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 can be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a base station, a NR NodeB, 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 can include any number of interconnected base stations and/or network elements.

[0024] The base station 114a can be part of the RAN 104/113, which can 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 can be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which can be referred to as a cell (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for a wireless service to a specific geographical area that can be relatively fixed or that can change over time. The cell can further be divided into cell sectors. For example, the cell associated with the base station 114a can be divided into three sectors. Thus, in one embodiment, the base station 114a can include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a can employ multiple-input multiple output (MIMO) technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and/or receive signals in desired spatial directions. [0025] The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which can 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 can be established using any suitable radio access technology (RAT).

[0026] More specifically, as noted above, the communications system 100 can be a multiple access system and can 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 can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0027] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro). [0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as NR Radio Access, which can establish the air interface 116 using New Radio (NR).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can 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 can 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 base station).

[0030] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c can 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.

[0031] The base station 114b in FIG. 1 A can be a wireless router, Home Node B, Home eNode B, or access point, for example, and can 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 can 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 can 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 can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b can have a direct connection to the Internet 110. Thus, the base station 114b can not be required to access the Internet 110 via the CN 106/115.

[0032] The RAN 104/113 can be in communication with the CN 106/115, which can 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 can 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 can 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 can 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 can be utilizing a NR radio technology, the CN 106/115 can also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0033] The CN 106/115 can 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 can include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 can 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 can include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 can include another CN connected to one or more RANs, which can employ the same RAT as the RAN 104/113 or a different RAT.

[0034] One or more (e.g., all) of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 can include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1 A can be configured to communicate with the base station 114a, which can employ a cellularbased radio technology, and with the base station 114b, which can employ an IEEE 802 radio technology. [0035] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 can include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and/or other peripherals 138, among others. It will be appreciated that the WTRU 102 can include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0036] The processor 118 can 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 can perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, which can be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0037] The transmit/receive element 122 can 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 can be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 can be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 can be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 can be configured to transmit and/or receive any combination of wireless signals. [0038] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 can include any number of transmit/receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116. [0039] The transceiver 120 can 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 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0040] The processor 118 of the WTRU 102 can be coupled to, and can 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 can also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 can 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 can include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can 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 can 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).

[0041] The processor 118 can receive power from the power source 134, and can be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 can be any suitable device for powering the WTRU 102. For example, the power source 134 can 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.

[0042] The processor 118 can also be coupled to the GPS chipset 136, which can 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 can 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 can acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0043] The processor 118 can further be coupled to other peripherals 138, which can 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 can 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 Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 can include one or more sensors, the sensors can 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.

[0044] The WTRU 102 can 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) can be concurrent and/or simultaneous. The full duplex radio can include an interference management unit 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 WTRU 102 can 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)).

[0045] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 can employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 can also be in communication with the CN 106.

[0046] The RAN 104 can include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 can include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c can 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 can implement MIMO technology. Thus, the eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0047] Each of the eNode-Bs 160a, 160b, 160c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c can communicate with one another over an X2 interface.

[0048] The CN 106 shown in FIG. 1C can 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 can be owned and/or operated by an entity other than the CN operator.

[0049] The MME 162 can be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and can serve as a control node. For example, the MME 162 can 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 can 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.

[0050] The SGW 164 can be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 can generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 can 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.

[0051] The SGW 164 can be connected to the PGW 166, which can 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.

[0052] The CN 106 can facilitate communications with other networks. For example, the CN 106 can 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 can include, or can 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 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0053] 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 can use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0054] In representative embodiments, the other network 112 can be a WLAN.

[0055] A WLAN in Infrastructure Basic Service Set (BSS) mode can have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can 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 ST As that originates from outside the BSS can arrive through the AP and can be delivered to the STAs. Traffic originating from ST As to destinations outside the BSS can be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS can be sent through the AP, for example, where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. The traffic between STAs within a BSS can be considered and/or referred to as peer-to-peer traffic. The peer-to- peer traffic can be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS can use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode can not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS can communicate directly with each other. The IBSS mode of communication can sometimes be referred to herein as an “ad-hoc” mode of communication.

[0056] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP can transmit a beacon on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g, 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel can be the operating channel of the BSS and can 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) can be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g, every STA), including the AP, can sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA can back off. One STA (e.g, only one station) can transmit at any given time in a given BSS.

[0057] High Throughput (HT) STAs can 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.

[0058] Very High Throughput (VHT) STAs can support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, can be passed through a segment parser that can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, can be done on each stream separately. The streams can be mapped on to the two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80^-80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC).

[0059] 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 can support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices can have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0060] WLAN systems, which can 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 can be designated as the primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all ST As in the BSS. The bandwidth of the primary channel can be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel can 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 can 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 can be considered busy even though a majority of the frequency bands remains idle and can be available.

[0061] In the United States, the available frequency bands, which can 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.

[0062] 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 can employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 can also be in communication with the CN 115. [0063] The RAN 113 can include base stations 180a, 180b, 180c, though it will be appreciated that the RAN 113 can include any number of base stations while remaining consistent with an embodiment. The base stations 180a, 180b, 180c can each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the base stations 180a, 180b, 180c can implement MIMO technology. For example, base stations 180a, 108b can utilize beamforming to transmit signals to and/or receive signals from the base stations 180a, 180b, 180c. Thus, the base station 180a, for example, can use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the base stations 180a, 180b, 180c can implement carrier aggregation technology. For example, the base station 180a can transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers can be on unlicensed spectrum while the remaining component carriers can be on licensed spectrum. In an embodiment, the base stations 180a, 180b, 180c can implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from base station 180a and base station 180b (and/or base station 180c).

[0064] The WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing can vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c can communicate with base stations 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).

[0065] The base stations 180a, 180b, 180c can 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 can communicate with base stations 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 can utilize one or more of base stations 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c can communicate with base stations 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c can communicate with/connect to base stations 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c can implement DC principles to communicate with one or more base stations 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c can serve as a mobility anchor for WTRUs 102a, 102b, 102c and base stations 180a, 180b, 180c can provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0066] Each of the base stations 180a, 180b, 180c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support 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. 1 D, the base stations 180a, 180b, 180c can communicate with one another over an Xn interface.

[0067] The CN 115 shown in FIG. 1D can 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 can be owned and/or operated by an entity other than the CN operator.

[0068] The AMF 182a, 182b can be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N2 interface and can serve as a control node. For example, the AMF 182a, 182b can 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 can 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 can 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 can 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.

[0069] The SMF 183a, 183b can be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b can also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b can select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b can 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 can be IP-based, non-IP based, Ethernet-based, and the like. [0070] The UPF 184a, 184b can be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N3 interface, which can 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 can 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.

[0071] The CN 115 can facilitate communications with other networks. For example, the CN 115 can include, or can 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 can provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which can 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 can 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.

[0072] 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, base station 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, can be performed by one or more emulation devices (not shown). The emulation devices can be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices can be used to test other devices and/or to simulate network and/or WTRU functions.

[0073] The emulation devices can 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 can 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 can 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 can be directly coupled to another device for purposes of testing and/or can perform testing using over-the-air wireless communications.

[0074] The one or more emulation devices can 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, the emulation devices can 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 can be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which can include one or more antennas) can be used by the emulation devices to transmit and/or receive data.

[0075] Applications such as XR, industrial loT, and intelligent transportation system applications may impose requirements on resources and power efficiency including, for example, an ultra-high uplink (UL) data rate, ultra-low latency, and/or high reliability. Some service such as XR, virtual reality (VR) and/or augmented reality (AR) may synchronize data flows from different devices (e.g., gloves, glasses, etc.) that may run on a single application layer. A conventional mobile network configured to manage services on a per WTRU basis may not be sufficient to meet the stringent requirements of multiple devices simultaneously. To overcome these and/or other challenges, WTRU aggregation (e.g., multiple WTRUs collaborate for uplink transmissions and/or downlink receptions) may be used to boost the capabilities of the mobile network.

[0076] To support WTRU aggregation, one or more multipath relays may be deployed, and a WTRU may connect to a network via a Uu interface and/or a user equipment (UE)-to-network (U2N) relay (e.g., a single U2N relay). In some examples, PDCP layer aggregation for a multipath relay may be adopted and a WTRU may use a Uu path as a primary link for uplink transmission (e.g., an indirect path via a U2N relay may be used as a supplementary link to support uplink transmission when the amount of data in a buffer is sufficiently large). Lower layer (e.g., physical layer) conditions such as channel gains, transmission layers, etc., may not be considered in a higher layer aggregation scheme such as the aforementioned PDCP layer aggregation scheme.

[0077] Lower layer such as physical (PHY) layer aggregation may be supported. For WTRU aggregation (e.g., for uplink transmissions and/or downlink receptions), it may be assumed that the WTRU may perform uplink transmissions and/or downlink receptions with the support of one or multiple assistant WTRUs (e.g., to take advantage of WTRU diversity gains in the transmissions and/or receptions). For WTRU aggregation in a group, a network (e.g., a base station) may take advantage of multiple Uu links and/or sidelinks among WTRUs to route (e.g., dynamically) uplink and/or downlink data, and consider different conditions (e.g., such as transmission powers, channel conditions, quality of service (QoS) of the data, etc.) to efficiently manage the group (e.g., to guarantee the QoS and/or quality of experience (QoE) of services).

[0078] Lower layer (e.g., a media access control (MAC) layer and/or a PHY layer) aggregation may allow a network to combine gains at the lower layer to boost system performance. One or more channels (e.g., a PDSCH and/or a PUSCH) may be transmitted on the same resources to reduce resource overhead and/or enhance antenna capabilities. As a result, decoding performance (e.g., in a video related application or service) may be improved (e.g., due to the combining of gains at the lower layer). HARQ retransmissions may not be performed if transmissions by a WTRU succeed, which may reduce latency and/or avoid unnecessary re-transmissions.

[0079] For lower layer aggregation, a base station may schedule (e.g., dynamically) UL, DL, and/or sidelink (SL) transmissions or resources for one or more WTRUs in a group, while considering dynamic changes in Uu and/or SL conditions as well as the potential gains arising from lower layer aggregation (e.g., to help improve system performance).

[0080] The WTRUs in a group may have better knowledge about Uu and/or sidelink connections than a base station does. The base station may offload one or more functionalities to the group of WTRUs, such as, e.g., scheduling and/or routing. The offloading of the one or more functionalities to the group of WTRUs may be performed in a manner that guarantees the QoS of an application in the group.

[0081] When referred to herein, a protocol data unit (PDU) may refer to a PDU at any protocol layer. For example, a PDU may include a SDAP PDU, a PDCP PDU, a RLC PDU, a MAC PDU, or a PHY PDU. A PDU may also include a TB, a HARQ RV, etc. A PDU may also include a PDU of an adaptation layer introduced to support WTRU aggregation. When referred to herein, the quality of service (QoS) of a PDU (e.g., a MAC PDU) may include a combination of one or more of the following. The QoS of a PDU may include one or more 5QI parameters associated with a radio bearer (RB) or a logical channel (LCH). The QoS of a PDU may also include control information (e.g., MAC CE) that may be included in the PDU, such as, e.g., a priority, a PDB, a reliability measure (e.g., PER), a maximum data burst volume (MDBV), etc. The QoS of a PDU may also include one or more configurations associated with an RB/LCH that may be included in the PDU (e.g., MAC PDU). For example, these configurations may indicate whether an RB/LCH is configured with WTRU aggregation enabled/disabled, the number of aggregated WTRUs associated with an RB/LCH, a HARQ retransmission mode associated with an RB/LCH.

[0082] When referred to herein, a PDU transmitted or received at a lower layer (e.g., such as a MAC layer) may comprise multiple higher layer (e.g., SDAP, PDCP, and/or RLC layers) PDUs. The QoS associated with the lower-layer PDU may include a combination of one or more of the following. The QoS of the PDU may include a maximum and/or minimum value of a 5QI parameter of multiple (e.g., all) RBs/LCHs. The QoS of the PDU may include control information (e.g., MAC CE) that may be included in the PDU such as a maximum priority, a minimum PDB, a minimum PER, a maximum MDBV, etc. The QoS of the PDU may include one or more configurations associated with an RB/LCH included in the PDU (e.g., MAC PDU). For example, these configurations may indicate whether the PDU include an RB/LCH configured with WTRU aggregation enabled/disabled, the maximum number of aggregated WTRUs associated with an RB/LCH included in the PDU, a HARQ retransmission mode associated with an RB/LCH included in the PDU.

[0083] When referred to herein, a WTRU may be a source WTRU (e.g., an initiator of a PDU to transmit to another node such as a base station or another WTRU), a destination WTRU (e.g., an end receiver of a PDU that may be transmitted from a base station or another WTRU), an assistant WTRU (e.g., a WTRU supporting another WTRU such as a source WTRU or destination WTRU in the transmission and reception of a PDU), a group coordinator WTRU (e.g., a WTRU supporting a base station to perform one or more functions such as scheduling for one or more WTRUs that may belong to a group), or a member WTRU (e.g., a WTRU in a group that may interact with a group coordinator WTRU and/or other member WTRUs to perform one or more procedures under the coordination of the group coordinator WTRU). A member WTRU may be a WTRU of a group that may coordinate with other WTRUs in the group to perform a group-related function.

[0084] When referred to herein, WTRU aggregation may include a scenario in which two or more WTRUs may transmit and/or receive a PDU for a WTRU. For a WTRU aggregation-based transmission, two or more WTRUs may transmit a PDU for a source WTRU. In this scenario of WTRU aggregation, the source WTRU may or may not be one of the transmitting WTRUs. For a WTRU aggregation-based reception, two or more WTRUs may receive a PDU from a base station for a destination WTRU. In this scenario of WTRU aggregation, the destination WTRU may or may not be one of the receiving WTRUs associated with the base station.

[0085] When referred to herein, a beam may have the following characteristics. A WTRU may transmit or receive a physical channel or reference signal according to at least one spatial domain filter, and the term “beam” may be used to refer to a spatial domain filter. The WTRU may transmit a physical channel or signal using the same spatial domain filter as the spatial domain filter used for receiving an RS (e.g., such as CSI-RS) or a SS block. The WTRU transmission may be referred to as a “target” and the received RS or SS block may be referred to as a “reference” or “source.” In these cases, the WTRU may be said to transmit a target physical channel or signal according to a spatial relation with a reference to such an RS or SS block.

[0086] A WTRU may transmit a first physical channel or signal using the same spatial domain filter as the spatial domain filter used for transmitting a second physical channel or signal. The first and second transmissions may be referred to as “target” and “reference” (or “source”), respectively. In such cases, the WTRU may be said to transmit the first (target) physical channel or signal according to a spatial relation with the second (reference) physical channel or signal. The spatial relation may be implicit, configured via RRC signaling, or signaled in an MAC CE or DCI. For example, a WTRU may implicitly transmit a PUSCH and/or DM-RS of a PUSCH using the same spatial domain filter as an SRS indicated by an SRS resource indicator (SRI) indicated in DCI or configured via RRC signaling. In another example, the spatial relation may be configured via RRC signaling for an SRI, or signaled by a MAC CE for a PUCCH. Such a spatial relation may also be referred to as a “beam indication.”

[0087] A WTRU may receive a first (target) downlink channel or signal using the same spatial domain filter or spatial reception parameter as a second (reference) downlink channel or signal. For example, an association may exist between a physical channel (e.g., such as a PDCCH or a PDSCH) and its respective DM-RS. At least when the first and second signals are reference signals, the association may exist if the WTRU is configured with a quasi-colocation (QCL) assumption type D between corresponding antenna ports. Such an association may be configured as a transmission configuration indicator (TCI) state. The WTRU may receive an indication of the association between a CSI-RS (or an SS block) and a DM-RS, for example, via an index to a set of TCI states configured via RRC signaling and/or signaled using a MAC CE. Such an indication may also be referred to as a “beam indication.”

[0088] When referred to herein, a WTRU being “configured with” may include the scenario in which the WTRU may receive configuration information from a base station or another node (e.g., a group coordinator WTRU). If the WTRU receives the configuration information from the base station, the WTRU may receive dedicated RRC configuration information or a SIB from the base station. If the WTRU receives the configuration information from another node, the WTRU may receive the configuration information via sidelink communication (e.g., via PC5 RRC signaling).

[0089] When referred to herein, the radio link quality between two nodes (e.g., between a source WTRU and an assistant WTRU, between two assistant WTRUs, between a group coordinator and a member WTRU, between two member WTRUs, or between a WTRU and a base station) may include a combination of one or more of the following. The radio link quality may include an RLF status between two nodes. For example, the link quality between two nodes may indicate whether RLF is detected/declared by an evaluating node (e.g., an evaluating WTRU). The radio link quality may include a synchronization status between two nodes. For example, the link quality between two nodes may refer to whether an evaluating node (e.g., an evaluating WTRU) is synchronized with a peer node (e.g., a base station or a peer WTRU). The radio link quality may include a beam management status between two nodes. For example, the link quality between two nodes may indicate whether a beam failure is detected/declared by an evaluating node (e.g., an evaluating WTRU). The radio link quality may include layer 1 (L1) and/or layer 3 (L3) measurements of transmission(s) between two nodes, which may include but may not be limited to an RSRP, RSRQ, SINR, RSSI, pathloss, BLER, etc. In examples, the L1 or L3 measurements may be performed at an evaluating node (e.g., an evaluating WTRU). In examples, the L1 or L3 measurements may be perform at a peer node (e.g., a base station) and sent to an evaluating node (e.g., an evaluating WTRU). For example, the link quality between two nodes may refer to the L3 RSRP of a transmission from a peer node.

[0090] When referred to herein, a link quality between two nodes may refer to the distance between the two nodes. For example, a WTRU may deem the link quality between two nodes as good if the distance between those two nodes is smaller than a configured threshold. Otherwise, the WTRU may deem the link quality between the two nodes as not good.

[0091] When referred to herein, a channel busy ratio (CBR) of a resource pool may be used to exchange PDUs between two nodes. For example, the link quality between two nodes may refer to the CBR of a resource pool used to transmit data between the two nodes (e.g, a source WTRU and an assistant WTRU). When referred to herein, a link quality between two nodes may refer to the maximum/minimum latency requirement for transmitting a PDU between the two nodes. For example, the link quality between the two node may be considered as good if the latency is smaller than a configured threshold. Otherwise, the link quality between two nodes may be considered not good. When referred to herein, an uplink channel such as a PUCCH or PUSCH may be used to transmit of a PDU. A technique used for PUSCH transmissions may be applicable to PUCCH transmissions, and vice versa.

[0092] A WTRU (e.g, which may be a source WTRU or an assistant WTRU) may be configured to perform a WTRU aggregation-based transmission (e.g, in the uplink). The WTRU (e.g, a source WTRU) may collaborate with one or more other WTRUs (e.g, assistant WTRUs) to transmit a PDU to a base station. The set of WTRUs transmitting the PDU may be referred to as a set of aggregated WTRUs. The PDU transmitted by the set of aggregated WTRUs may originate from one of the aggregated WTRUs. The PDU transmitted by the set of aggregated WTRUs may be from another WTRU that may not be one of the set of aggregated WTRUs. In a WTRU aggregation-based transmission of the PDU, the set of aggregated WTRUs may (e.g, all) transmit the same PDU, or each WTRU of the set of aggregated WTRUs may transmit a part of the PDU. The set of aggregated WTRUs may use a combination of one or more of the following WTRU aggregation uplink transmission schemes.

[0093] In a first example of the aggregated transmission scheme (e.g, scheme 1), a transmission may be aggregated based on PHY layer single frequency network (SFN) combining using a same set of resources, in which transmissions by multiple WTRUs (e.g, a source WTRU and one or more assistant WTRUs) may be performed using the same time/frequency resources. An indication may be transmitted to indicate that the multiple WTRUs are transmitting a message (e.g., the same PDU) using the same set of resources, and a receiver may combine the signals received from the transmitter WTRUs to decode the message (e.g., the PDU). The multiple (e.g., all) WTRUs may also use the same HARQ RV and/or MCS to transmit in the resources. A base station may then combine (e.g., based on SFN combining) the transmissions of the WTRUs and decode the PDU. This example WTRU aggregation scheme may help the base station obtain channel diversity from multiple WTRUs transmitting using the same resources.

[0094] In examples, a source WTRU may use an assistant WTRU to perform a WTRU aggregation-based transmission. For example, the source WTRU may receive an uplink grant for a WTRU aggregation-based transmission. The source WTRU may forward at least a portion of a PDU (e.g., a MAC PDU) to the assistant WTRU and may indicate the scheduled resources to the assistant WTRU. The source WTRU itself may perform a transmission of the PDU (e.g., a first portion of an MAC PDU) in the scheduled resources, while the assistant WTRU may receive the PDU (e.g., a second portion of the MAC PDU) and the indication of the scheduled resources (e.g., scheduled by the uplink grant) from the source WTRU, and transmit the PDU (e.g., the second portion of the MAC PDU) using the indicated resources (e.g., to assist the source WTRU with the uplink PDU transmission). As such, the source and/or the assistant WTRUs may transmit the same PDU (e.g., the MAC PDU) using the same resources (e.g., allocated by the uplink grant).

[0095] In examples, a source WTRU may use multiple (e.g., two) assistant WTRUs to perform an uplink transmission. For example, the source WTRU itself may decide not to perform an uplink transmission associated with a PDU, and may forward portions of the PDU (e.g., a MAC PDU) to the assistant WTRUs. The source WTRU may indicate the resources for the assistant WTRUs to transmit the PDU, and the assistant WTRUs may transmit the PDU (e.g., respective portions of the PDU) in the resources indicated by the source WTRU. As such, the assistant WTRUs may transmit the same PDU provided by the source WTRU using the same resources (e.g., allocated by the uplink grant).

[0096] In a second example of the aggregated transmission scheme (e.g., scheme 2), a WTRU may aggregate a transmission based on PHY layer SFN combining using different resources, in which the transmission may be performed by multiple WTRUs (e.g., a set of aggregated WTRUs) using different resources. The multiple (e.g., all) WTRUs may also use the same RV and/or MCS to transmit in these resources (e.g., the multiple WTRUs may use the same RV and/or MCS to transmit the PDU).

[0097] In a third example scheme of the aggregated transmission scheme (e.g., scheme 3), a WTRU may aggregate a transmission based on PHY layer HARQ combining, in which a receiver WTRU may combine the receptions of multiple transmissions to decode a message (e.g., including providing HARQ feedback for the message). In this scheme, a set of aggregated WTRUs may transmit the same PDU using different resources. A (e.g., each) WTRU may use the same or different RVs and/or MCSs to transmit the PDU (e.g., the portion of the PDU assigned to the WTRU). A base station may decode the PDU transmitted by the WTRUs by performing HARQ combining.

[0098] In a fourth example of the aggregated transmission scheme (e.g., scheme 4), a WTRU may aggregate a transmission based on L2/L3 aggregation. In this scheme, a source WTRU may send a PDU (e.g., a PDCP PDU, an RLC PDU, or a MAC PDU) to a set of aggregated WTRUs (e.g., the source WTRU may or may not be one of the aggregated WTRUs). The set of aggregated WTRUs may then transmit (e.g., in the uplink) the PDU provided by the source WTRU to a base station. An (e.g., each) aggregated WTRU may individually transmit the PDU (e.g., the portion of the PDU assigned to the WTRU) on behalf of the source WTRU without coordination (e.g., PHY coordination) among the WTRUs.

[0099] In examples, a source WTRU may use an assistant WTRU to support an uplink transmission. The source and assistant WTRUs may aggregate the transmission at a PDCP layer. For a PDCP PDU without WTRU aggregation-based transmission enabled, the source WTRU may not forward the PDCP PDU to the assistant WTRU (e.g., the source WTRU itself may transmit the PDCP PDU). For a PDCP PDU with WTRU aggregation-based transmission enabled, the source WTRU may forward at least a portion of the PDCP PDU to the assistant WTRU. Both the source and the assistant WTRUs may transmit the PDCP PDU (e.g., respective portions of the PDCP PDU). The assistant WTRU may request its own uplink resources to transmit the PDCP PDU provided by the source WTRU. The assistant WTRU may multiplex PDCP PDUs from multiple WTRUs into a PDU (e.g., a MAC PDU) that the assistant WTRU may transmit using a resource.

[0100] In examples, a source WTRU may use multiple (e.g., two) assistant WTRUs to perform an uplink transmission. The WTRUs (e.g., three WTRUs, including the source WTRU and two assistant WTRUs) may aggregate the uplink transmission at a PDCP layer. The source WTRU may have a primary and a secondary assistant WTRUs. The source WTRU may forward a non-aggregation-based PDCP PDU to the primary assistant WTRU and forward an aggregation-based PDCP PDU to both the primary and the secondary assistant WTRUs. An (e.g., each) assistant WTRU may request its own uplink resources to transmit the PDCP PDU associated with the source WTRU and may multiplex PDCP PDUs from multiple WTRUs (e.g., the assistant WTRU’s own PDU and the source WTRU’s PDU) into a PDU that the assistant WTRU may transmit using a resource. [0101] FIG. 2 illustrates an example where a source WTRU may use an assistant WTRU to support an uplink transmission. For PHY layer WTRU aggregation, the source WTRU may use scheme 1 described herein for the aggregation, in which the assistant and the source WTRUs may transmit a PDU (e.g., respective portions of the PDU) using the same resources and/or the same MCS and/or HARQ RV. The WTRUs may also use scheme 2 or 3 described herein for the aggregation, in which the source WTRU and the assistant WTRU may transmit the PDU using different resources.

[0102] FIG. 3 illustrates an example where a source WTRU may use multiple assistant WTRUs to support an uplink transmission. For PHY layer WTRU aggregation, the source WTRU may use scheme 1 described herein for the aggregation. In this scheme, the assistant and the source WTRUs may transmit a PDU (e.g., respective portions of the PDU) using the same resources and/or the same MCS and/or HARQ RV. The WTRUs may also use scheme 2 or 3 described herein for the aggregation, in which case the source WTRU and the assistant WTRU may transmit the PDU using different resources.

[0103] When a WTRU (e.g., a source WTRU) has a PDU (e.g., a transport block (TB)) to transmit in the uplink, the WTRU may perform the transmission using one or more of the following transmission modes. With a first transmission mode (e.g., mode A), the WTRU may transmit the PDU as a non-WTRU aggregation-based transmission (e.g., the WTRU may not request an assistant WTRU to help with the transmission and may perform the transmission on its own). In a second transmission mode (e.g., mode B), the WTRU may transmit the PDU as a non-WTRU aggregation-based transmission and may use an assistant WTRU for the transmission. For example, the WTRU (e.g., a source WTRU) may forward the PDU (e.g., a TB) to an assistant WTRU. The source WTRU itself may not transmit the PDU and the assistant WTRU may transmit the PDU for the source WTRU. The source WTRU may provide information to the assistant WTRU to help the assistant WTRU perform the uplink transmission. The information may indicate uplink resources, transmission parameters (e.g., transmission beam, transmission power, MCS, RV, etc.), a WTRU aggregation scheme, etc. For this uplink transmission mode, the source WTRU may have an assistant WTRU to transmit a PDU for the source WTRU (e.g., the source WTRU may forward the PDU to the assistant WTRU and may ask the assistant WTRU to perform the uplink transmission).

[0104] In a third transmission mode (e.g., mode C), the WTRU (e.g., a source WTRU) may transmit the PDU as a WTRU aggregation-based transmission without the source WTRU itself performing part of the transmission. For example, the WTRU may forward the PDU to multiple assistant WTRUs, which may form a set of aggregated WTRUs and transmit the PDU for the source WTRU. The set of aggregated WTRU may use any of the WTRU aggregation schemes described herein to transmit the PDU for the source WTRU. The source WTRU may provide information to the assistant WTRUs to help them perform the uplink transmission. The information may include uplink resources, transmission parameters (e.g., transmission beam, transmission power, MCS, RV, etc.), a WTRU aggregation scheme, etc. For example, the source WTRU may be configured with multiple assistant WTRUs. The source WTRU may forward a PDU to the multiple assistant WTRUs for transmission in the uplink, and the assistant WTRUs may transmit the PDU for the source WTRU using one of the WTRU aggregation schemes described herein. The assistant WTRUs may coordinate with each other to transmit the PDU using PHY layer aggregation. Each assistant WTRUs may also transmit the PDU independently using L2 or L3 aggregation.

[0105] In a fourth transmission mode (e.g., mode D), the WTRU (e.g., a source WTRU) may transmit the PDU as a WTRU aggregation-based transmission with the source WTRU performing at least part of the transmission. For example, the source WTRU may forward the PDU (e.g., a TB) to one or more assistant WTRUs. The source WTRU and the one or more assistant WTRUs may form a set of aggregated WTRUs (e.g, including the source WTRU itself), which may transmit the PDU using one or more of the WTRU aggregation-based transmission schemes described herein. The source WTRU may provide information to the assistant WTRU(s) to help them perform the uplink transmission. The information may include uplink resources, transmission parameters (e.g, transmission beam, transmission power, MCS, RV, etc.), a WTRU aggregation scheme, etc. For example, the source WTRU may be configured with an assistant WTRU and may forward the PDU to the assistant WTRU for transmission in the uplink. Both the source and the assistant WTRUs may transmit the PDU for the source WTRU using a WTRU aggregation scheme described herein.

[0106] FIG. 4 illustrates an example in which a source WTRU may be configured with two assistant WTRUs (e.g. Assistant WTRU1 and Assistant WTRU2) and may transmit a PDU using one or more of the uplink transmission modes described herein. As shown in FIG. 4, the WTRU may use transmission mode A described herein to transmit PDU 1 , during which the WTRU itself may transmit the PDU via a Uu link. The WTRU may use transmission mode B described herein to transmit PDU2, during which the WTRU may forward the PDU to Assistant WTRU1 and have Assistant WTRU1 transmit the PDU via a Uu link. The WTRU may use transmission mode C to transmit PDU3, during which the WTRU may forward the PDU to two assistant WTRUs, and the assistant WTRUs may transmit the PDU to a base station using one of the WTRU aggregation schemes described herein. The WTRU may use transmission mode D to transmit PDU4, during which the WTRU may forward the PDU to Assistant WTRU2, and the WTRU and Assistant WTRU2 may transmit the PDU using one of the WTRU aggregation-based transmission schemes described herein. [0107] A WTRU (e.g, a destination WTRU) may perform a WTRU aggregation-based downlink reception. For example, the WTRU (e.g., destination WTRU) may collaborate with one or more other WTRUs (e.g., assistant WTRUs) to receive a PDU from a base station. The set of WTRUs receiving the PDU may form a set of aggregated WTRUs (e.g., the destination WTRU may or may not be one of the aggregated WTRUs). In the case where the destination WTRU is not one of the aggregated WTRUs, one or more of the aggregated WTRUs may forward the downlink PDU to the destination WTRU. The set of aggregated WTRUs may use one or more of the following schemes associated with a WTRU aggregation-based downlink reception.

[0108] In a first reception scheme (e.g., reception scheme 1), the WTRU aggregation-based reception may be performed based on PHY reception diversity using the same set of resources. In this scheme, the set of aggregated WTRUs may be scheduled to receive a PDU using the same resources and may coordinate with each other to decode the PDU. For example, the destination WTRU may use an assistant WTRU to perform the WTRU aggregation-based reception using reception scheme 1 , under which both the destination and the assistant WTRUs may be scheduled to receive the PDU (e.g, for the destination WTRU) using the same resources. The two WTRUs may coordinate to decode the PDU. For example, the assistant WTRU may forward the decoded PDU to the destination WTRU if the destination WTRU fails to decode the PDU.

[0109] In a second reception scheme (e.g, reception scheme 2), the WTRU aggregation-based reception may be performed based on PHY reception diversity using different resources. In this scheme, the set of aggregated WTRUs may be scheduled to receive a PDU using different resources. A (e.g, each) WTRU may use the same or different HARQ RVs and/or MCSs of the PDU in a scheduled resource. The set of aggregated WTRUs may coordinate with each other to decode the PDU. For example, the destination WTRU may use multiple (e.g, two) assistant WTRUs to perform the WTRU aggregation-based reception using reception scheme 2, under which the set of aggregated WTRUs may be scheduled with multiple resources to receive a PDU and an (e.g, each) assistant WTRU may be scheduled with a resource to decode the PDU. The assistant WTRU may then forward the decoded PDU to the destination WTRU.

[0110] In a third reception scheme (e.g, reception scheme 3), the WTRU aggregation-based reception may be performed based on L2/L3 reception diversity. In this scheme, the set of aggregated WTRUs may support the destination WTRU in a downlink reception. An (e.g, each) aggregated WTRU in the set of aggregated WTRUs may independently receive a PDU (e.g, a PDCP PDU, an RLC PDU, or a MAC PDU) for the destination WTRU. An (e.g, each) aggregated WTRU may individually receive the PDU from a base station without PHY coordination. The aggregated WTRU may then forward the received PDU to the destination WTRU. For example, the destination WTRU may have one or more assistant WTRUs to support it in a downlink reception. The destination and the assistant WTRUs may aggregate at a PDCP layer. The assistant WTRU may receive a PDCP PDU targeting the destination WTRU and may forward the received PDU to the destination WTRU.

[0111] A WTRU (e.g., a destination WTRU) may receive a PDU (e.g., a MAC PDU) in the downlink using one or more of the following downlink reception modes, and may determine which mode to use for the downlink reception. In a first downlink reception mode (e.g., mode A), the WTRU may receive the PDU as a non-WTRU aggregation-based reception. For example, the WTRU itself may receive the PDU (e.g., a MAC PDU) and may not request another WTRU to assist with the reception of the PDU. In a second downlink reception mode (e.g., mode B), the WTRU may receive the PDU as a non-WTRU aggregation-based reception and may use an assistant WTRU for the reception. For example, the WTRU may not receive the PDU directly from a base station and the assistant WTRU may receive the PDU via the downlink and send the PDU to the destination WTRU. In a third downlink reception mode (e.g., mode C), the WTRU may receive the PDU as a WTRU aggregation-based reception without the destination WTRU performing the reception itself. For example, multiple assistant WTRUs may form a set of aggregated WTRUs and may receive the PDU for the destination WTRU using one or more of the WTRU aggregation downlink reception schemes described herein. The by one or more of the assistant WTRUs may then provide the PDU to the destination WTRU. In a fourth downlink reception mode (e.g., mode D), the WTRU may receive the PDU as a WTRU aggregation-based reception with the destination WTRU performing at least part of the reception. For example, a set of aggregated WTRUs including the destination WTRU itself may be formed, which may receive the PDU using one or more of the WTRU aggregation downlink reception schemes described herein. The destination WTRU may coordinate with the other WTRUs in the set of aggregated WTRUs to receive the PDU transmitted by a base station.

[0112] A base station may assist with WTRU aggregation in the uplink and/or the downlink. For example, a WTRU (e.g., a source WTRU) may have a PDU to transmit and may determine which uplink transmission mode (e.g., non-WTRU aggregation-based transmission by the source WTRU, non-WTRU aggregation-based transmission by an assistant WTRU, WTRU aggregation-based transmission without the source WTRU, or WTRU aggregation-based transmission with the source WTRU) to use for the transmission based on an indication (e.g., configuration information) received from the base station. The indication (or configuration information) may include one or more of the following.

[0113] The indication received from the base station may include configuration information regarding a specific uplink transmission mode. For example, the source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may receive configuration information from the base station to perform the transmission based on WTRU aggregation (e.g., mode D uplink transmission described herein). The WTRU may transmit a PDU using one or more of the WTRU aggregation uplink transmission schemes described herein.

[0114] The indication received from the base station may include an implicit or explicit indication of an uplink transmission mode to be used with an uplink grant. For example, the WTRU may receive a grant (e.g., a configured or dynamic grant), which may implicitly or explicitly indicate the uplink transmission mode to use for a corresponding uplink transmission. The WTRU (e.g., a source WTRU) may use an assistant WTRU for the uplink transmission. The grant received by the WTRU may include a dedicated configured grant, a grant in a dedicated carrier for WTRU aggregation, a grant in a dedicated BWP for WTRU aggregation, etc., which may be dedicated for (e.g., allow for) a WTRU aggregation-based transmission. The WTRU may use the grant for the uplink WTRU aggregation-based transmission (e.g., as a mode D uplink transmission). If the WTRU determines to transmit a PDU in the dedicated grant as a WTRU aggregation-based uplink transmission, the WTRU may forward the PDU to the assistant WTRU and ask the assistant WTRU to perform the WTRU uplink aggregation-based transmission. The WTRU may use a set of transmission parameters associated with WTRU aggregation-based transmissions for the PDU. The WTRU (e.g., a source WTRU) may use multiple (e.g., two) assistant WTRUs for the uplink transmission. The WTRU may or may not have a direct Uu connection with a network (e.g., with a base station). The WTRU may be configured to use multiple (e.g., two) uplink transmission modes, wherein a first transmission mode may use one assistant WTRU to transmit a PDU in the uplink, and a second transmission mode may use multiple (e.g., two) assistant WTRUs to transmit the PDU in the uplink. The WTRU may be scheduled with a grant (e.g., a configured grant) for each of the transmission modes. If the grant is dedicated for the first transmission mode described above (e.g., transmission using one assistant WTRU), the WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to transmit the PDU. If the grant is dedicated for the second transmission mode described above (e.g., transmission using multiple assistant WTRUs), the WTRU may forward the PDU to the assistant WTRUs and request them to transmit the PDU.

[0115] The indication received from the base station may include an activation/deactivation of an uplink transmission mode (e.g., the indication may be received via RRC signaling, a MAC CE, or a DCI message). The WTRU (e.g., a source WTRU) may use an assistant WTRU to support an uplink transmission. The WTRU may receive an activation indication from the base station to use an uplink transmission mode for a PDU (e.g., a WTRU aggregation-based transmission involving the source WTRU). The WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to transmit the PDU using one or more of the WTRU aggregation uplink transmission schemes described herein. The WTRU (e.g., a source WTRU) may use multiple (e.g., two) assistant WTRUs for an uplink transmission. The WTRU may have one assistant WTRU transmit a PDU. The WTRU may receive an activation indication from the base station to use multiple assistant WTRUs to transmit the PDU. The WTRU may forward the PDU to the assistant WTRUs and request that the assistant WTRUs transmit the PDU as a WTRU aggregation-based transmission using one or more of the WTRU aggregation uplink transmission schemes described herein.

[0116] The indication received from the base station may include configuration information regarding a transmission mode associated with a QoS (e.g., a QoS associated with a PDU). For example, the WTRU may receive configuration information from the base station regarding an association between the QoS of a PDU (e.g., a QoS associated with a radio bearer and/or an LCH via which the PDU may be transmitted) and an uplink transmission mode. The WTRU may determine the uplink transmission mode for the PDU based on the QoS associated with the PDU (e.g., based on one or more radio bearers (RBs) and/or logical channels (LCHs) associated with the PDU).

[0117] A WTRU may receive an indication from a base station regarding a WTRU aggregation-based transmission. For example, the WTRU (e.g., a source WTRU) may have a PDU to transmit with a scheduled uplink resource. The WTRU may determine whether or not to perform a WTRU aggregation-based transmission of the PDU based on an indication from the base station. If the WTRU determines to perform the WTRU aggregation-based transmission in the scheduled resource, the WTRU may forward the PDU to a set of aggregated WTRUs and may request the set of aggregated WTRUs to perform a WTRU aggregation-based transmission of the PDU. If the WTRU determines not to perform the WTRU aggregation-based transmission, the WTRU may transmit the PDU on its own (e.g., without involving other WTRUs). For an assistant WTRU, if it determines to perform the WTRU aggregation-based transmission, it may use a set of transmission parameters associated with WTRU aggregation-based transmissions to transmit the PDU. The source WTRU and/or the assistant WTRU may determine whether to perform a WTRU aggregation-based transmission of the PDU based on one or more of the following indications from the base station.

[0118] The one or more indications received from the base station may include an RNTI (e.g., a group- RNTI) scrambled in a scheduling DCI. For example, a WTRU (e.g., an assistant WTRU) may be configured with two RNTIs (e.g., a C-RNTI and a group-RNTI), wherein one of the RNTIs (e.g., the group-RNTI) may be associated with WTRU aggregation-based transmissions and the other RNTI (e.g., the C-RNTI) may be associated with non-WTRU aggregation-based transmissions. The WTRU may determine to perform a WTRU aggregation-based uplink transmission if the DCI (e.g., scheduling DCI) received by the WTRU is scrambled by the RNTI (e.g., the group-RNTI) associated with WTRU aggregation-based transmissions. If the DCI is scrambled by the RNTI (e.g., the C-RNTI) associated with non-WTRU aggregation-based transmissions, the WTRU may perform a non-WTRU aggregation-based transmission. If the DCI is scrambled by the group-RNTI, the WTRU (e.g., an assistant WTRU) may transmit the PDU (e.g., part of the PDU) associated with a source WTRU and determine/use a set of transmission parameters for the WTRU aggregation-based transmission. If the DCI is scrambled by the C-RNTI, the WTRU (e.g., an assistant WTRU) may transmit its own PDU (e.g., using resources indicated by the DCI message) and determine/use a set of transmission parameters for the non-WTRU aggregation-based transmission. In examples, a WTRU (e.g., a source WTRU) may be configured with a group-RNTI via a scheduling DCI associated with a WTRU aggregation-based transmission. The WTRU may forward a PDU to one or more assistant WTRUs. If the DCI is scrambled by the group-RNTI, the WTRU may determine to transmit the PDU as a WTRU aggregation-based uplink transmission, for which a set of transmission parameters associated with WTRU aggregation-based transmissions may be used. If the DCI is scrambled by a C-RNTI, the WTRU may transmit the PDU as a non-WTRU aggregation-based transmission, for which a set of transmission parameters associated with non-WTRU aggregation-based transmissions may be used.

[0119] The one or more indications received from the base station may include a DCI search space. For example, a WTRU may be configured with a dedicated search space for scheduling DCI that is associated with WTRU aggregation-based transmissions. The WTRU may perform a WTRU aggregation-based transmission of a PDU using resources indicated by a scheduling DCI that is detected in the dedicated search space. If the WTRU is scheduled by a DCI in another search space, the WTRU may perform a non-WTRU aggregationbased transmission.

[0120] The one or more indications received from the base station may include a Control Resource Set (CORESET). For example, a WTRU may be configured with a dedicated CORESET in which the WTRU may monitor for a scheduling DCI associated with WTRU aggregation-based transmissions. The WTRU may perform a WTRU aggregation-based transmission of a PDU using resources provided by a scheduling DCI that is detected in the dedicated CORESET. If the WTRU is scheduled by a DCI detected in another CORESET, the WTRU may perform a non-WTRU aggregation-based transmission.

[0121] The one or more indications received from the base station may include a DCI format. For example, a WTRU may be configured with an uplink scheduling DCI format for WTRU aggregation-based transmissions. The WTRU may perform a WTRU aggregation-based transmission of a PDU using resources scheduled by that DCI format. If the WTRU is scheduled by another DCI format, the WTRU may perform a non-WTRU aggregation-based transmission.

[0122] The one or more indications received from the base station may be received via uplink scheduling DCI. For example, a WTRU may use an assistant WTRU to assist with an uplink transmission. The WTRU may receive an uplink scheduling DCI indicating whether to perform a WTRU aggregation-based or non-WTRU aggregation-based transmission of a PDU. If the DCI indicates that the WTRU may perform a WTRU aggregation-based transmission, the WTRU may forward the PDU to the assistant WTRU and perform the WTRU aggregation-based transmission. If the DCI indicates the WTRU may perform a non-WTRU aggregation-based transmission of the PDU, the WTRU may transmit the PDU as a non-WTRU aggregationbased transmission.

[0123] The one or more indications received from the base station may include a HARQ process ID. For example, a WTRU may be configured with a set of HARQ process IDs for WTRU aggregation-based transmissions. The WTRU may perform a WTRU aggregation-based transmission if the WTRU is indicated to transmit the PDU using a HARQ ID associated with WTRU aggregation-based transmissions. If the WTRU is indicated with another HARQ process ID, the WTRU may perform a non-WTRU aggregation-based transmission of the PDU.

[0124] A WTRU may determine a WTRU aggregation-based transmission scheme based on an indication (e.g., configuration information) received from a base station. The indication may include one or more of the following.

[0125] The indication received from the base station may include configuration information from the base station (e.g., RRC configuration information). For example, a source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may receive configuration information from the base station that may indicate a WTRU aggregation-based transmission scheme to be used by the WTRU. The WTRU may transmit a PDU using the configured WTRU aggregation-based transmission scheme.

[0126] The indication received from the base station may include a HARQ ID (e.g., HARQ process ID) associated with a WTRU aggregation-based scheme. For example, a WTRU may be configured with a WTRU aggregation-based transmission scheme per HARQ ID. The WTRU may receive a scheduling grant from the base station, which may indicate an associated HARQ ID. The WTRU may determine which WTRU aggregation-based transmission scheme to use based on the HARQ ID indicated by the base station. [0127] The indication received from the base station may include an implicit or explicit indication of a WTRU aggregation-based transmission scheme for an uplink grant. For example, a WTRU may receive a grant (e. g. , a configured or dynamic grant), which may implicitly or explicitly indicate an uplink WTRU aggregation-based scheme to be used with the grant. The WTRU may apply the indicated WTRU aggregation-based scheme according to the indication from the base station.

[0128] The indication received from the base station may include an activation/deactivation indication of a WTRU aggregation-based transmission scheme. For example, a WTRU may perform a non-WTRU aggregation-based transmission and may receive an activation indication from the base station (e.g., via RRC signaling, a MAC CE or a DCI message) to use a WTRU aggregation-based scheme (e.g., PHY layer SFN combining using the same resources) for a WTRU aggregation-based transmission. The WTRU may perform a WTRU aggregation-based transmission upon reception of the activation indication from the base station.

[0129] The indication received from the base station may include configuration information regarding a WTRU aggregation-based transmission scheme associated with the QoS of a PDU. For example, a WTRU may receive configuration information from the base station of an association between the QoS of a PDU (e.g., associated with a radio bearer and/or LCH) and a WTRU aggregation-based transmission scheme. The WTRU may determine the uplink transmission mode for a PDU based on the QoS associated with the PDU (e.g., a set of RBs/LCHs included in the PDU).

[0130] The indication received from the base station may indicate a property of uplink scheduled resources, which may include the number, size, and timing of the scheduled resource. For example, a WTRU may perform a WTRU aggregation-based transmission using scheme 1 described herein if the WTRU is scheduled with a PUSCH resource. The WTRU may perform a WTRU aggregation-based transmission using scheme 2 described herein if the WTRU is scheduled with multiple (e.g., two) PUSCH resources of the same size. The WTRU may perform a WTRU aggregation-based transmission if the WTRU is scheduled with multiple (e.g., two) PUSCH resources with different sizes.

[0131] A WTRU may receive a grant for an uplink transmission and determine which PDU to transmit with the grant. For example, a source WTRU) may determine which LCHs to multiplex in the PDU (e.g., a MAC PDU) to be transmitted with the grant. An assistant WTRU may have a PDU from itself and a PDU from another WTRU (e.g., a source WTRU) to transmit. The assistant WTRU may determine whether to transmit its own PDU and/or the PDU from the other WTRU. A WTRU (e.g., a source or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on one or more of the following. [0132] The WTRU may determine which PDU to transmit in a scheduled resource based on configuration information received from a base station regarding a specific uplink transmission mode. For example, an assistant WTRU may be configured to support a source WTRU in an uplink transmission. The assistant WTRU may receive an activation indication or configuration information to initialize an assistant mode. The assistant WTRU may multiplex PDUs from the source WTRU in a scheduled uplink grant.

[0133] The WTRU may determine which PDU to transmit in a scheduled resource based on an indication of a specific uplink transmission mode received from the base station. The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on an RNTI (e.g., a group-RNTI) configured for WTRU aggregation-based transmissions. For example, an assistant WTRU may be configured to support a source WTRU in an uplink transmission. The assistant WTRU may be configured with a group-RNTI for a WTRU aggregation-based transmission and may transmit a PDU from the source WTRU if the scheduling DCI is scrambled by the group-RNTI. If the scheduling DCI is not scrambled by the group-RNTI, the assistant WTRU may transmit its own PDUs. As another example, a source WTRU may be configured with a group-RNTI for a WTRU aggregation-based transmission. The source WTRU may prioritize multiplexing LCHs that may have WTRU aggregation enabled in a resource scheduled by a DCI scrambled by the group- RNTI. If the resource is scheduled by a DCI scrambled by another RNTI, the source WTRU may perform a normal LCP procedure (e.g., to prioritize LCHs with a higher priority to multiplex in a PDU such as a MAC PDU) or to exclude LCHs that may have WTRU aggregation enabled from being multiplexed in the PDU (e.g., a MAC PDU) to be transmitted in the scheduled resource.

[0134] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on a DCI search space. For example, a source WTRU may be configured with a dedicated search space for a DCI scheduling WTRU aggregation-based transmissions. An assistant WTRU may transmit a PDU from the source WTRU in the resource scheduled by a DCI detected in the dedicated search space for WTRU aggregation. If the resource is scheduled by a DCI in another search space, the assistant WTRU may transmit its own PDUs.

[0135] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on a CORESET. For example, the WTRU may be configured with a dedicated CORESET to monitor for a DCI scheduling a WTRU aggregation-based transmission. A source WTRU may prioritize multiplexing PDUs from LCHs that may have WTRU aggregation enabled if the resource is scheduled by a DCI detected in the dedicated CORESET for WTRU aggregation. Otherwise, the WTRU may perform a normal LCP procedure (e.g., to prioritize the LCH with higher priority to multiplex in a PDU such as a MAC PDU) or to exclude LCHs that may have WTRU aggregation enabled from being multiplexed in the PDU (e.g., a MAC PDU) to be transmitted in the scheduled resource.

[0136] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on a DCI format configured for WTRU aggregation. For example, the WTRU may be configured with an uplink scheduling DCI format for WTRU aggregation-based transmissions. An assistant WTRU may multiplex PDUs from a source WTRU in the PDU (e.g., a MAC PDU) to be transmitted in a resource scheduled by the DCI format configured for WTRU aggregation. If the WTRU is scheduled by another DCI format, the WTRU may transmit its own PDUs.

[0137] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on an implicit/explicit indication included in an uplink scheduling DCI regarding whether to perform a WTRU aggregation-based or non-WTRU aggregation-based transmission in the scheduled resource. For example, a source WTRU may receive an uplink scheduling DCI indicating whether to perform a WTRU aggregation-based or non-WTRU aggregation-based transmission. If the indication is to perform the WTRU aggregation-based transmission, the WTRU may prioritize multiplexing the PDUs of LCHs that may have WTRU aggregation enabled. As another example, an assistant WTRU may receive an uplink scheduling DCI indicating whether to perform a WTRU aggregation-based or non-WTRU aggregation-based transmission. If the indication is to perform the WTRU aggregation-based transmission, the assistant WTRU may multiplex PDUs from the source WTRU in the PDU (e.g., MAC PDU) to be transmitted using the resource scheduled by the DCI. Otherwise, the assistant WTRU may multiplex its own PDUs to be transmitted in the resource scheduled by the DCI.

[0138] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on a HARQ process ID. For example, a source WTRU may be configured with a HARQ process ID for WTRU aggregation-based transmissions. The WTRU may prioritize multiplexing PDUs of LCHs that may have WTRU aggregation enabled if the WTRU is scheduled with the HARQ process ID for WTRU aggregation-based transmissions. Otherwise, if the WTRU is scheduled with another HARQ process ID, the WTRU may perform a normal LCP procedure (e.g., to prioritize LCHs with a higher priority to be multiplexed in a PDU such as a MAC PDU) or to exclude LCHs that may have WTRU aggregation enabled from being multiplexed in the PDU (e.g., a MAC PDU) to be transmitted in the scheduled resource.

[0139] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on an implicit or explicit indication from a base station regarding whether to perform a WTRU aggregation-based transmission in an uplink grant. For example, the WTRU may receive a grant (e. g . , a configured or dynamic grant) that may implicitly or explicitly indicate whether to perform a WTRU aggregation-based transmission. As another example, a WTRU (e.g., a source WTRU) may use an assistant WTRU for uplink transmissions. The source WTRU may receive a grant (e.g., a dedicated configured grant, a grant in a dedicated carrier for WTRU aggregation, a grant in a dedicated BWP for WTRU aggregation, etc.), which may be dedicated for WTRU aggregation-based transmissions. The source WTRU may prioritize multiplexing the PDUs of LCHs that may have WTRU aggregation enabled in the PDU (e.g., MAC PDU) to be transmitted in the scheduled resource.

[0140] The WTRU (e.g., a source WTRU or assistant WTRU) may determine which PDU to transmit in a scheduled resource based on an indication from a node other than the base station (e.g., from a source WTRU). For example, a source WTRU may indicate resources for an assistant WTRU to use for an uplink transmission. The source WTRU may implicitly request the assistant WTRU to transmit a PDU of the source WTRU. The assistant WTRU may multiplex the PDU from the source WTRU in a PDU (e.g., MAC PDU) to be transmitted in the indicated resource. As another example, the source WTRU may indicate resources for the assistant WTRU, and further indicate that the assistant WTRU may transmit its own PDUs using the indicated resources. In response, the assistant WTRU may transmit its own PDUs in the indicated resources.

[0141] A WTRU may perform an LCP procedure for WTRU aggregation-based transmissions. For example, the WTRU may be scheduled with a resource for a WTRU aggregation-based transmission. The WTRU may perform an LCP procedure to multiplex a PDU in the PDU (e.g., a MAC PDU) to be transmitted in the scheduled resource. The WTRU may multiplex, in the PDU (e.g., MAC PDU) to be transmitted, a PDU from LCHs that may have WTRU aggregation enabled. The WTRU may not multiplex a PDU from LCHs that may not have WTRU aggregation enabled. The WTRU may prioritize multiplexing a PDU from LCHs that may have WTRU aggregation enabled. The WTRU may multiplex a PDU from LCHs that may not have WTRU aggregation enabled after prioritizing the LCHs with WTRU aggregation enabled. For example, the WTRU may multiplex a PDU from the LCHs without WTRU aggregation enabled after multiplexing PDUs (e.g., all PDUs) from the LCHs with WTRU aggregation enabled. As another example, the WTRU may multiplex a PDU from the LCHs without WTRU aggregation enabled after the number of multiplexed PDUs from one or more LCHs with WTRU aggregation enabled becomes greater than a configured threshold. The WTRU may perform a legacy LCP procedure, in which the WTRU may determine which LCH(s) to multiplex in a PDU for transmission in a resource based on the priority associated with the LCH(s). The WTRU may determine an uplink transmission mode and/or WTRU aggregation-based transmission scheme based on the QoS of the PDU. If the PDU includes a PDU of an LCH with WTRU aggregation enabled, the WTRU may perform a WTRU aggregation-based transmission of the PDU. If there is no LCH with WTRU aggregation enabled, the WTRU may perform a non-WTRU aggregation-based transmission of the PDU.

[0142] A WTRU may determine a set of WTRUs (e.g, assistant WTRUs) to be used for an uplink transmission of a PDU based on an indication from a base station. The WTRU (e.g., a source WTRU) may receive semi-static configuration information from the base station (e.g., via an RRC message or a MAC CE) indicating the set of WTRUs to be used to perform the WTRU aggregation-based transmission. The WTRU may monitor for a DCI for a group of WTRUs (e.g., a WTRU aggregation group). The WTRU may receive a dynamic indication from the base station (e.g., in a DCI) indicating the set of WTRUs to transmit in one or more resources indicated in the DCI. For example, the WTRU may be configured with a DCI format that may schedule one or more resources for a WTRU aggregation group. The WTRU may be configured with a group- RNTI, with which the WTRU may monitor for a DCI for the group. The DCI may include one or multiple scheduled resources for the group of WTRUs. A (e.g., each) scheduled resource may have an associated ID (e.g, member ID) of the WTRU aggregation group. The WTRU may determine a scheduled resource for each WTRU in the group. The WTRU may indicate the scheduled resource for each WTRU in the group. Such an indication may be transmitted, for example, via a sidelink using an adaptation layer. For example, a source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may be configured with a WTRU aggregation-based transmission scheme (e.g, scheme 3 described herein based on PHY layer HARQ combining). The source WTRU may be configured with a DCI format, which may schedule multiple (e.g, two) uplink resources, where a first resource may be used by the source WTRU, and a second resource may be used by the assistant WTRU. The DCI may be scrambled by a group-RNTI for a WTRU aggregationbased transmission. The source WTRU may monitor for a DCI for the assistant WTRU to perform the WTRU aggregation-based transmission. Upon detection of a DCI scrambled by the group-RNTI, the source WTRU may indicate a second PUSCH resource to the assistant WTRU, which may be used to perform a WTRU aggregation-based transmission of the assistant WTRU’s own PDUs.

[0143] A WTRU determine resources for performing a WTRU aggregation-based transmission. The WTRU (e.g, an assistant WTRU) may be configured to support a source WTRU for an uplink transmission of a PDU from the source WTRU. The assistant WTRU may determine the resources to be used for a WTRU aggregation-based transmission based on an indication from the network. The assistant WTRU may monitor for a DCI that may schedule resources for a group of WTRUs (e.g, a WTRU aggregation group). The assistant WTRU may be configured with a DCI format that may schedule resources for WTRU aggregation-based transmissions. A (e.g, each) resource indicated in the DCI may have an associated ID (e.g, a member ID). The assistant WTRU may be configured with an RNTI (e.g., a group-RNTI) for WTRU aggregation-based scheduling. The assistant WTRU may receive an DCI scrambled by the group-RNTI and may determine which resource(s) to use for a WTRU aggregation-based transmission based on an ID (e.g., member ID) associated with the resource(s). For example, a source WTRU may use multiple (e.g., two) assistant WTRUs to support an uplink transmission. The assistant WTRUs may be configured with a DCI format, which may schedule multiple (e.g., two) PUSCH resources. Each assistant WTRU may determine its resource based on a member ID associated with the resource. For example, a first resource may be used by a first assistant WTRU and a second resource may be used by a second assistant WTRU. A source WTRU may be configured with a WTRU aggregation-based transmission scheme (e.g., scheme 3 described herein based on PHY layer HARQ combining). The source WTRU may be configured with a DCI format that may schedule multiple (e.g., two) uplink resources, wherein a first resource may be used by the source WTRU, and a second resource may be used by an assistant WTRU. The DCI may be scrambled by a group-RNTI for WTRU aggregation-based transmissions. Each assistant WTRU may monitor for DCI associated with WTRU aggregation-based transmissions. Upon detection of a DCI scrambled by a group-RNTI, a first assistant WTRU may use the first resource and a second assistant WTRU may use a second resource for a WTRU aggregation-based transmission (e.g., to support the source WTRU in its uplink transmissions).

[0144] A WTRU may determine whether to use a scheduled resource for a WTRU aggregation-based transmission. The WTRU may determine not to use the scheduled resource if there is no PDU to transmit for LCHs that may have WTRU aggregation-based transmission enabled. The WTRU may prioritize multiplexing LCHs that may have WTRU aggregation enabled. The WTRU may multiplex other LCHs (e.g., LCH without WTRU aggregation enabled) after prioritizing one or more LCHs (e.g., all LCHs) with WTRU aggregation enabled.

[0145] A WTRU may determine a pattern of a WTRU aggregation-based transmission based on an indication received from a base station. The WTRU may be configured with a WTRU aggregation scheme (e.g., scheme 3 described herein). The WTRU may receive an uplink scheduling from the base station for a WTRU aggregation-based transmission. The WTRU may be configured (e.g., via RRC configuration information) with one or multiple WTRU transmission patterns. Each WTRU transmission pattern may determine which WTRU to transmit in which resources in a set of scheduled resources. The WTRU may receive a scheduling grant (e.g., a configured grant or a dynamic grant). The WTRU may receive an indication from the base station regarding which WTRU transmission pattern to use in the scheduling grant. The WTRU may receive such an indication via DCI, a MAC CE, or an RRC message associated with the resource scheduling message. Based on the pattern indicated by the base station, the WTRU may determine which resource to use for its transmission. In example, a (e.g., each) WTRU in a group may receive an indication of the WTRU aggregation-based transmission pattern (e.g., via common DCI or dedicated DCI for each WTRU). In examples, one of the WTRUs in the group (e.g., a source WTRU) may receive the indication of the WTRU aggregation-based transmission pattern. The WTRU may then indicate the WTRU transmission pattern to the other WTRUs in a set of aggregated WTRUs (e.g., one or more assistant WTRUs), so that the other WTRUs may know which resource may be used for an uplink transmission.

[0146] FIG. 5 illustrates an example in which a source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may be configured to use scheme 2 described herein (e.g., based on PHY layer HARQ combining) for a WTRU aggregation-based transmission. In examples, the source and/or the assistant WTRUs may be configured with a first WTRU transmission pattern (e.g., Pattern 1 in FIG. 5) with which a (e.g., each) transmission of the source WTRU may be followed by a transmission of the assistant WTRU. In examples, the source and/or assistant WTRUs may be configured with a second WTRU transmission pattern (e.g., Pattern 2 in FIG. 5) with which multiple (e.g., all) transmissions by the source WTRU may be performed first, followed by multiple (e.g., all) transmissions by the assistant WTRU.

[0147] A WTRU may determine one or more uplink transmission parameters for a PDU. These parameters may include, for example, a transmission beam to be used for the PDU, a transmission power for the PDU, a MCS for the PDU, a HARQ RV and/or HARQ RV pattern for the PDU, etc. The WTRU may determine the transmission parameters (e.g., the transmission power, MCS, HARQ RV and/or HARQ RV pattern) for the PDU based on one or more of the following.

[0148] The WTRU may determine the transmission parameters for the PDU based on an uplink transmission mode. For example, the WTRU may be configured with multiple (e.g., two) beams to use, and the WTRU may use a first beam (e.g., a beam optimized for non-WTRU aggregation transmissions) for a mode A uplink transmission, and use a second beam (e.g., a suboptimal beam used for WTRU aggregation-based transmissions) for a mode D uplink transmission.

[0149] The WTRU may determine the transmission parameters for the PDU based on a WTRU transmission aggregation scheme. For example, the WTRU may be configured with multiple WTRU aggregation schemes. For a (e.g., each) WTRU aggregation scheme, the WTRU may be configured with a set of transmission parameters (e.g., transmission beam, transmission power, MCS, HARQ RV pattern, etc.). The WTRU may determine which set of transmission parameters to use based on a selected WTRU aggregation scheme. For example, the WTRU may be configured with two WTRU aggregation schemes (e.g., scheme 1 and scheme 3 described herein). The WTRU may use a first transmission power for the WTRU aggregation scheme 1 and the first transmission power may be derived based on a set of parameters (e.g., pathloss, alpha, etc.) associated with scheme 1 . The WTRU may use a second transmission power for WTRU aggregation scheme 3, and may derive the second transmission power based on a set of parameters (e.g., pathloss, alpha, etc.) associated with scheme 3. In examples, an assistant WTRU may determine which transmission parameters (e.g., HARQ RV) to use based on an indicated WTRU aggregation scheme. For example, the assistant WTRU may use HARQ RVO for scheme 1 WTRU aggregation (e.g., based on PHY layer SFN combining using the same resources) and may use HARQ RV1 for scheme 3 WTRU aggregation (e.g., based on PHY layer HARQ combining).

[0150] The WTRU may determine the transmission parameters for the PDU based on the set of WTRUs that may be used to transmit the PDU. For example, the WTRU may use a first transmission power if the WTRU transmits the PDU on its own and may use a second transmission power if the WTRU performs a WTRU aggregation-based transmission of the PDU.

[0151] A WTRU (e.g., an assistant WTRU) may be scheduled with a resource for an uplink transmission (e.g., via a configured grant). The WTRU may determine which HARQ RV to use to transmit a PDU (e.g., a first transmission of the PDU from the WTRU) and which HARQ RV pattern to use to transmit the PDU (e.g., an initial and repetitive transmissions of the PDU) based on one or more of the following.

[0152] The WTRU may determine the HARQ RV and/or HARQ RV pattern based on a WTRU aggregation scheme. For example, the WTRU (e.g., an assistant WTRU) may be configured to transmit HARQ RVO for a PDU if the WTRU performs a scheme 1 WTRU aggregation-based transmission. If the WTRU performs a scheme 3 WTRU aggregation-based transmission, the WTRU may transmit HARQ RV1 for the PDU. As another example, the WTRU (e.g., an assistant WTRU) may be configured with multiple (e.g., two) HARQ RV patterns. The WTRU may use a first HARQ RV pattern (e.g., 0231 pattern) for a first WTRU aggregation scheme (e.g., scheme 1 for WTRU aggregation-based transmissions) and use a second HARQ RV pattern (e.g., 1313 pattern) for a second WTRU aggregation scheme (e.g., scheme 3 for WTRU aggregation-based transmissions).

[0153] The WTRU may determine the HARQ RV and/or HARQ RV pattern based on a role of the WTRU in WTRU aggregation. For example, for a WTRU aggregation scheme, the WTRU may determine to use a first HARQ RV (e.g., HARQ RVO) for a PDU if the WTRU is a source WTRU. If the WTRU is an assistant WTRU, the WTRU may use another HARQ RV (e.g., HARQ RV1) for the PDU. As another example, for a WTRU aggregation scheme, the WTRU may determine to use a first HARQ RV pattern (e.g., 0303 pattern) for a PDU if the WTRU is a source WTRU. If the WTRU is an assistant WTRU, the WTRU may use a second HARQ RV pattern (e.g., 1203 pattern) for the PDU.

[0154] The WTRU may determine the HARQ RV and/or HARQ RV pattern based on one or more member IDs associated with a WTRU aggregation group. For example, the WTRU may determine which HARQ RV to use to transmit a PDU based on the WTRU’s member ID in a WTRU aggregation group. For a WTRU aggregation scheme, the WTRU may determine to use a HARQ RV (e.g., HARQ RVO) for a PDU if the WTRU is the first assistant WTRU in the group. The WTRU may use a second HARQ RV (e.g., HARQ RV1 ) for the PDU if the WTRU is the second assistant WTRU. As another example, for a WTRU aggregation scheme, the WTRU may determine to use a first HARQ RV pattern (e.g., 0303 pattern) if the WTRU is the first assistant WTRU in the group. If the WTRU is the second assistant WTRU, the WTRU may use another HARQ RV pattern (e.g., 1023 pattern).

[0155] A WTRU (e.g., a destination WTRU) may support WTRU aggregation-based receptions. The WTRU may be configured by a network to use one or more other WTRUs (e.g., assistant WTRUs) to decode a PDU targeting the destination WTRU. The destination WTRU and the assistant WTRU(s) may collaborate to receive a PDU from the base station. For example, the destination WTRU may request an assistant WTRU to forward a PDU if the assistant WTRU fails to decode the PDU (e.g., a TB). The destination WTRU may use multiple assistant WTRUs to receive a PDU. The multiple assistant WTRUs may collaborate to receive and decode the PDU for the destination WTRU. The assistant WTRUs may collaborate to forward the decoded PDU to the destination WTRU. The assistant WTRUs may collaborate to feedback a HARQ status of the PDU to a base station.

[0156] A WTRU (e.g., a destination WTRU) may feedback the HARQ status of a PDU based on a decoding status determined by the destination WTRU or one or more assistant WTRUs. For example, the WTRU may feedback its own decoding status of the PDU. As another example, the WTRU may report the decoding status of another WTRU (e.g., an assistant WTRU). In this regard, the WTRU may receive the decoding status from the assistant WTRU and may then report the decoding status of the assistant WTRU to a base station. As yet another example, the WTRU may feedback the HARQ status of a PDU to the base station based on combined decoding status of the destination WTRU itself and another WTRU (e.g., an assistant WTRU). In this regard, the WTRU may receive the decoding status of the PDU from the assistant WTRU. If both the destination WTRU and the assistant WTRU fail to decode the PDU, the WTRU may report a HARQ NACK. If either the destination WTRU or the assistant WTRU successfully decodes the PDU, the WTRU may report a HARQ ACK. [0157] In examples, a WTRU (e.g., a destination WTRU) may receive an indication (e.g., from a base station) to perform multiple (e.g., two) HARQ feedbacks for a WTRU aggregation-based reception of a PDU. A first HARQ feedback may be associated with the reception status of the destination WTRU’s own PDU reception, while a second HARQ feedback may be associated with the PDU reception status of an assistant WTRU. In examples, the second HARQ feedback may be associated with the PDU reception status of both the destination WTRU and the assistant WTRU. For instance, the WTRU may report a HARQ ACK if at least one of the destination WTRU or the assistant WTRU successfully decodes the PDU. Otherwise, the WTRU may report a HARQ NACK.

[0158] A WTRU (e.g., an assistant WTRU) may report PDU reception information to a base station. The information reported by the WTRU may be used by the base station to determine a channel between the base station and the WTRU (e.g., the WTRU may or may not report HARQ feedback to the base station). The information reported by the WTRU may include, for example, a packet error rate (PER), a percentage and/or number of PDUs successfully received, a block error rate (BLER), etc. The WTRU may report the PDU reception information periodically or based on one or more configured triggering conditions. These triggering conditions may include, for example, a BLER/PER being greater than a configured threshold, or a number of failed PDUs within a window being larger than a configured threshold.

[0159] A WTRU (e.g., an assistant WTRU) may send the decoding status of a PDU to another WTRU (e.g., a destination WTRU). The assistant WTRU may be configured with a condition for sending the decoding status of the PDU. For example, the assistant WTRU may send an indication of the decoding status of PDU to the other WTRU (e.g., the destination WTRU) if the assistant WTRU successfully decodes the PDU. As another example, the assistant WTRU may send the indication of the decoding status to the other WTRU (e.g., the destination WTRU) if the assistant WTRU fails to decode the PDU. As yet another example, the assistant WTRU may send the decoding status of the PDU regardless of the decoding status. As yet another example, the assistant WTRU may send the decoding status of the PDU upon reception of a request from the other WTRU (e.g., the destination WTRU).

[0160] A WTRU (e.g., an assistant WTRU) may forward a PDU to a destination WTRU if the assistant WTRU successfully decodes the PDU. The assistant WTRU may forward the PDU to the destination WTRU upon receiving a request from the destination WTRU. The destination WTRU may request the PDU from the assistant WTRU, for example, if the destination WTRU fails to decode the PDU.

[0161] Autonomous WTRU aggregation may be applied. A WTRU (e.g., a source WTRU) may determine a transmission mode for a PDU, which may include a WTRU aggregation mode and/or a non-WTRU aggregation mode. For example, the transmission mode may include a non-WTRU aggregation-based transmission by the source WTRU, a non-WTRU aggregation-based transmission by an assistant WTRU, a WTRU aggregationbased transmission without the source WTRU, a WTRU aggregation-based transmission with the source WTRU, etc. The transmission mode (e.g., uplink transmission mode) may be determined based on one or more of the following.

[0162] The transmission mode may be determined based on the QoS associated with a PDU. As an example, a source WTRU may use an assistant WTRU to perform an uplink WTRU aggregation-based transmission. The source WTRU may determine whether to perform a WTRU aggregation-based transmission for a PDU (e.g., mode D uplink transmission described herein) based on the QoS associated with the PDU. The source WTRU may be configured with a set of radio bearers (RBs) and/or LCHs that may have WTRU aggregation-based transmissions enabled. The WTRU may determine to transmit the PDU as a WTRU aggregation-based transmission (e.g., a mode D uplink transmission) if the PDU includes one or more of the RBs/LCHs with WTRU aggregation-based transmission enabled. If the PDU does not include an RB/LCH with WTRU aggregation-based transmission enabled, the WTRU may transmit the PDU on its own (e.g., as a mode A uplink transmission). As another example, the source WTRU may use multiple (e.g., two) assistant WTRUs to transmit a PDU for the source WTRU. The source WTRU may determine whether to use one assistant WTRU to transmit the PDU (e.g., as a mode B uplink transmission) or use multiple assistant WTRUs to transmit the PDU (e.g., as a mode C uplink transmission) based on the QoS of the PDU. The source WTRU may be configured with a set of RBs/LCHs that may use multiple (e.g., two) assistant WTRUs to transmit a PDU via a WTRU aggregation-based transmission. The source WTRU may forward the PDU to the assistant WTRUs and may request the assistant WTRUs to perform the WTRU aggregation-based transmission (e.g., Mode C uplink transmission) if the PDU includes one or more RBs/LCHs with WTRU aggregation-based transmission enabled. If the PDU does not include an RB/LCH with WTRU aggregation-based transmission enabled, the WTRU may forward the PDU to an assistant WTRU to transmit (e.g, as a mode B uplink transmission).

[0163] The transmission mode may be determined based on a link quality between a WTRU and a base station. As an example, the WTRU (e.g, a source WTRU) may use an assistant WTRU to support an uplink transmission. The WTRU may determine to transmit a PDU via a WTRU aggregation-based transmission if a Uu RSRP is smaller than a configured threshold. For instance, the WTRU may forward the PDU to the assistant WTRU and may form a set of aggregated WTRUs (e.g, which may or may not include the source WTRU) to transmit the PDU via a WTRU aggregation-based transmission (e.g, as a mode D uplink transmission) if the Uu RSRP is smaller than the configured threshold. If the Uu RSRP is greater than the configured threshold, the WTRU may transmit the PDU on its own (e.g., as a mode A uplink transmission). As another example, the WTRU (e.g., a source WTRU) may determine whether to transmit a PDU by the source WTRU itself or request an assistant WTRU to transmit the PDU based on the Uu link quality between the WTRU and the base station. For instance, the WTRU may transmit the PDU by itself (e.g., as a mode A uplink transmission) if the Uu RSRP is larger than a configured threshold. If the Uu RSRP is smaller than the configured threshold, the WTRU may transmit the PDU as a mode B uplink transmission.

[0164] The transmission mode may be determined based on the link quality between a source WTRU and an assistant WTRU. As an example, the source WTRU may use the assistant WTRU to support an uplink transmission. The source WTRU may determine to transmit a PDU as a mode D uplink transmission if a sidelink (SL) RSRP between the source WTRU and the assistant WTRU is larger than a configured threshold. If the SL RSRP between the source WTRU and the assistant WTRU is smaller than the configured threshold, the source WTRU may transmit the PDU as a mode A uplink transmission.

[0165] The transmission mode may be determined based on a transmission delay associated with a Uu link. For example, a WTRU may transmit a PDU as a mode C uplink transmission if the transmission delay in Uu is greater than a configured threshold. Otherwise, the WTRU may transmit the PDU as a mode A uplink transmission. As another example, the WTRU may transmit a PDU as a mode D uplink transmission if the transmission delay in Uu is larger than a configured threshold. Otherwise, the WTRU may transmit the PDU as a mode A uplink transmission.

[0166] The transmission mode may be determined based on a transmission delay associated with a sidelink. For example, a WTRU may transmit a PDU as a mode B uplink transmission if the transmission delay in the sidelink is smaller than a configured threshold. Otherwise, the WTRU may transmit the PDU as a mode A uplink transmission. As another example, the WTRU may transmit a PDU as a mode C uplink transmission if the transmission delay in the sidelink is smaller than a configured threshold. Otherwise, the WTRU may transmit the PDU as a mode D uplink transmission.

[0167] The transmission mode may be determined based on an uplink transmission power. For example, a WTRU may determine which uplink transmission mode to use for a PDU based on an uplink transmission power associated with the PDU. The WTRU may use a mode A uplink transmission if the transmission power in the uplink is smaller than a configured threshold. If the uplink transmission power is larger than the threshold, the WTRU may use a mode B uplink transmission. [0168] The transmission mode may be determined based on a sidelink transmission power. For example, a WTRU may determine which uplink transmission mode to use for PDU based on a sidelink transmission power associated with the PDU. If the sidelink transmission power is smaller than a configured threshold, the WTRU may use a mode C uplink transmission. If the sidelink transmission power is larger than the configured threshold, the WTRU may use a mode A uplink transmission. If the sidelink transmission power is smaller than a configured threshold, the WTRU may use a mode B uplink transmission. Otherwise, the WTRU may use a mode A uplink transmission.

[0169] The transmission mode may be determined based on the power headroom of a WTRU. For example, the WTRU may determine to transmit a PDU as a mode A uplink transmission if the power headroom of the WTRU is larger than a configured threshold. If the power headroom of the WTRU is smaller than the configured threshold, the WTRU may transmit the PDU as a mode B uplink transmission. As another example, the WTRU may determine to transmit a PDU as a mode D uplink transmission if the power headroom of the WTRU is smaller than a configured threshold. Otherwise, the WTRU may transmit the PDU as a mode A uplink transmission.

[0170] The transmission mode may be determined based on the power headroom of an assistant WTRU. For example, a source WTRU may have multiple assistant WTRUs to support an uplink transmission. The source WTRU may transmit a PDU as a mode C uplink transmission if the power headroom of the assistant WTRU is larger than a configured threshold. Otherwise, the source WTRU may transmit the PDU as a mode A uplink transmission. As another example, the source WTRU may transmit a PDU as a mode C uplink transmission if the power headroom of an (e.g., each) assistant WTRU is larger than a configured threshold. Otherwise, the source WTRU may transmit the PDU as a mode D uplink transmission.

[0171] The transmission mode may be determined based on a time gap associated with an uplink resource. The time gap may be determined based on the duration between a PDU arrival time and a scheduled uplink resource time. The time gap may be used to determine an uplink transmission mode for a configured grant, with which the WTRU may be aware of the uplink resource before the arrival of an uplink PDU. The time gap may be determined based on a gap between a scheduling time (e.g., the slot having uplink scheduling DCI) and a scheduled uplink grant. As an example, a source WTRU may determine to transmit a PDU by the source WTRU itself (e.g., using a mode A uplink transmission) if the gap between the PDU arrival and the uplink resource is smaller than a configured threshold. Otherwise, the source WTRU may forward the PDU to one or more assistant WTRUs and request the assistant WTRUs to transmit the PDU (e.g., using a mode B, mode C, or mode D uplink transmission). As another example, the source WTRU may receive an uplink grant for an uplink transmission (e.g., via DCI). The source WTRU may determine an uplink transmission mode for the PDU based on a time gap to the uplink grant. For instance, the source WTRU may determine whether to forward the PDU (e.g., a MAC PDU) to one or more assistant WTRUs and request the assistant WTRU to transmit the PDU based on the time gap to the uplink grant. If the time gap to the uplink grant is smaller than a configured threshold, the source WTRU may transmit the PDU using a non-WTRU aggregation-based transmission by the source WTRU itself. If the time gap is larger than the threshold, the source WTRU may forward the PDU to one or more assistant WTRUs and request the assistant WTRUs to transmit the PDU.

[0172] The transmission mode may be determined based on the size of an uplink grant. For example, a source WTRU may determine whether to forward a PDU (e.g., a MAC PDU) to an assistant WTRU and request the assistant WTRU to transmit the PDU based on the size of an uplink grant. The source WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to transmit the PDU if the size of the grant is smaller than a configured threshold. Otherwise, the source WTRU may not forward the PDU to the assistant WTRU. This approach may increase the reliability of the uplink transmission since, for example, for the same MCS and PDU size, the assistant WTRU may help increase the probability of decoding the PDU successfully.

[0173] The transmission mode may be determined based on a PDU size. For example, a source WTRU may determine whether to forward a PDU to an assistant WTRU and request the assistant WTRU to transmit the PDU based on the size of the PDU. The source WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to transmit the PDU if the PDU size is larger than a configured threshold. The source WTRU may transmit the PDU via a WTRU aggregation-based transmission involving the source WTRU. If the PDU size is smaller than the configured threshold, the source WTRU may not forward the PDU to the assistant WTRU. The source WTRU may transmit the PDU using a non-WTRU aggregation-based transmission by the source WTRU itself. This approach may increase the reliability of PDUs with a large PDU size.

[0174] The transmission mode may be determined based on a buffer status of a WTRU. As an example, the WTRU (e.g., a source WTRU) may determine whether to forward a PDU to an assistant WTRU and request the assistant WTRU to transmit the PDU based on a buffer status of the source WTRU. The source WTRU may forward the PDU to the assistant WTRU if the number of PDUs in a buffer of the source WTRU or the amount data associated with certain RBs/LCHs in the buffer is greater than a configured threshold. Otherwise, the source WTRU may transmit the PDU by the source WTRU itself (e.g., via a non-WTRU aggregation-based transmission by the source WTRU). As another example, the source WTRU may use multiple assistant WTRUs (e.g., two) to transmit a PDU in the uplink. The source WTRU may determine the set of assistant WTRUs to whom to forward the PDU and a request for the assistant WTRUs to transmit the PDU based on the number of PDUs in a buffer of the source WTRU. If the number of PDUs in the buffer is smaller than a configured threshold, the source WTRU may forward the PDU to an assistant WTRU. If the number of PDUs in the buffer is greater than the configured threshold, the WTRU may forward the PDU to multiple (e.g., two) assistant WTRUs and request the assistant WTRUs to transmit the PDU.

[0175] The transmission mode may be determined based on a grant type. For example, for a dynamic grant (e.g., a grant scheduled by DCI), a source WTRU may transmit a PDU using a non-WTRU aggregation-based transmission by the source WTRU itself. For a configured grant, the source WTRU may transmit the PDU using a WTRU aggregation-based transmission mode such as a WTRU aggregation-based transmission mode without the source WTRU or a WTRU aggregation-based transmission mode with the source WTRU. This approach may ensure the source WTRU have sufficient time to forward the PDU to one or more assistant WTRUs.

[0176] The transmission mode may be determined based on whether a WTRU has sent a buffer status to a base station that may indicate the availability of a PDU with WTRU aggregation enabled. For example, the WTRU (e.g., a source WTRU) may be configured with multiple (e.g., two) uplink transmission modes including a non-WTRU aggregation-based transmission mode by the source WTRU and a WTRU aggregation-based transmission mode with the source WTRU. The source WTRU may have a PDU with WTRU aggregation enabled. The source WTRU may determine whether to transmit the PDU using the WTRU aggregation-based transmission mode based on whether the WTRU has sent a BSR indicating the availability of the PDU. If such a BSR has not been sent, the source WTRU may transmit the PDU using the non-WTRU aggregation-based transmission. If the BSR has been sent indicating the availability of the WTRU aggregation enabled PDU, the source WTRU may transmit the PDU using the WTRU aggregation mode.

[0177] The transmission mode may be determined based on a prioritized interface to transmit a PDU to a base station. As an example, a source WTRU may be configured to prioritize a transmission mode and may switch to another transmission mode if a configured transmission mode condition is satisfied. For instance, the source WTRU may prioritize a non-WTRU aggregation-based transmission with an assistant WTRU mode, in which the source WTRU may transmit a PDU to the assistant WTRU. The WTRU may switch to a non-WTRU aggregation-based transmission by the source WTRU mode if one or more configured conditions are satisfied. For example, the source WTRU may be configured to switch to the non-WTRU aggregation-based transmission by the source WTRU mode based on a link quality between the source WTRU and the assistant WTRU (e.g., whether an RLF is declared between the two WTRUs, whether the RSRP of a channel between the two WTRUs is smaller than a configured threshold, etc.). For example, the source WTRU may be configured to switch to the non-WTRU aggregation-based transmission by the source WTRU mode if the number of PDUs in a buffer is larger than a configured threshold.

[0178] The transmission mode may be determined based on the availability of one or more assistant WTRUs. For example, a source WTRU may prioritize the use of a WTRU aggregation-based transmission mode if there are one or more assistant WTRUs. The source WTRU may prioritize a WTRU aggregation-based transmission with the source WTRU mode if the source WTRU may use an assistant WTRU for transmission. If the source WTRU may not use an assistant WTRU, the source WTRU may use a non-WTRU aggregation with the source WTRU mode. As another example, the source WTRU may prioritize the use of an assistant WTRU if the assistant WTRU is available. The WTRU may prioritize a non-WTRU aggregation-based transmission without the source WTRU mode if the assistant WTRU is available. Otherwise, the source WTRU may use a non-WTRU aggregation-based transmission with the source WTRU mode. As yet another example, if the source WTRU has multiple assistant WTRUs, the WTRU may prioritize a WTRU aggregation-based transmission without the source WTRU mode. If the source WTRU has one or more assistant WTRUs, the source WTRU may prioritize a non-WTRU aggregation-based transmission without the source WTRU mode.

[0179] The transmission mode may be determined based on a power class. For example, a WTRU may determine to transmit a PDU using a mode A uplink transmission if the maximum transmission of the WTRU is greater than a configured threshold (e.g., the WTRU has a high power class). If the maximum transmission power of the WTRU is smaller than the configured threshold, the WTRU may transmit the PDU using a mode B uplink transmission.

[0180] The transmission mode may be determined based on the availability of an uplink grant for a source WTRU. For example, the source WTRU may transmit a PDU using a mode A uplink transmission if the WTRU has an uplink grant available to transmit the PDU (e.g., within a configured latency). Otherwise, the source WTRU may transmit the PDU using a mode B uplink transmission.

[0181] The transmission mode may be determined based on the availability of an uplink grant for an assistant WTRU. For example, a source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may transmit the PDU using a mode B uplink transmission if the assistant WTRU has an uplink grant available to transmit the PDU (e.g., within a configured window). Otherwise, the source WTRU may transmit the PDU using a mode A uplink transmission. As another example, the source WTRU may use an assistant WTRU to support an uplink transmission. The source WTRU may transmit the PDU using a mode D uplink transmission if the assistant WTRU has an uplink grant available to transmit the PDU (e.g., within a configured window). The source WTRU may transmit the PDU using scheme 1 WTRU aggregation, in which the source WTRU may use the same uplink grant scheduled for the assistant WTRU to transmit the PDU. If the assistant WTRU does not have an uplink grant available to transmit the PDU within the configured window, the source WTRU may transmit the PDU using a mode A uplink transmission.

[0182] The transmission mode may be determined based on the availability of a sidelink grant. For example, a WTRU may transmit a PDU using a mode D uplink transmission if the WTRU has a sidelink grant available to transmit the PDU (e.g., within a configured window). Otherwise, the WTRU may transmit the PDU using a mode A uplink transmission.

[0183] A WTRU (e.g., a source WTRU) may be configured with an uplink transmission mode (e.g., mode D uplink transmissions described herein) and one or more conditions for switching to another transmission mode (e.g., mode C or mode A uplink transmissions described herein). The WTRU may switch to the other transmission mode if one or more of the configured conditions are satisfied.

[0184] The conditions for transmission mode switching may be based on a link quality between the WTRU and a base station satisfying a configured criterion. For example, the WTRU may be configured to use mode D for uplink transmissions and may switch to mode B if a Uu RSRP is smaller than a configured threshold. As another example, the WTRU may switch to mode C for uplink transmissions if the Uu RSRP is smaller than a configured threshold. As yet another example, the WTRU may switch to mode B for uplink transmissions if an Uu RLF is declared. As yet another example, the WTRU may switch to mode C for uplink transmissions if a Uu beam failure is detected.

[0185] The conditions for transmission mode switching may be based on a link quality between a source WTRU and an assistant WTRU satisfying a configured criterion. For example, the source WTRU may be configured to use mode B for uplink transmissions and may switch to mode A if an SL RSRP of a link with the assistant WTRU is smaller than a configured threshold. The WTRU may switch to mode A for uplink transmissions if an RLF is detected in a link with the assistant WTRU.

[0186] The conditions for transmission mode switching may be based on a power headroom of a source WTRU. For example, the source WTRU may be configured to use mode A for uplink transmissions and may switch to mode D for uplink transmissions if the power headroom of the source WTRU is smaller than a configured threshold. [0187] The conditions for transmission mode switching may be based on a power headroom of an assistant WTRU. For example, a source WTRU may be configured to use mode B for uplink transmissions and may switch to mode D if the power headroom of an assistant WTRU is smaller than a configured threshold.

[0188] A WTRU may determine a WTRU aggregation-based transmission scheme for a PDU (e.g, a TB) based on one or more of the following.

[0189] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on a grant type. For example, the WTRU may use scheme 3 described herein for the PDU transmission if an uplink grant is a dynamic grant and may use scheme 1 described herein for the PDU transmission if the uplink grant is a configured grant.

[0190] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on the QoS of the PDU (e.g., such as a packet delay budget (PDB)). For example, the WTRU (e.g., a source WTRU) may use an assistant WTRU to support an uplink transmission of the PDU. The WTRU may use scheme 1 described herein for the PDU transmission if the PDB of the PDU is larger than a configured threshold. If the PDB of the PDU is smaller than the configured threshold, the WTRU may use scheme 3 described herein for the PDU transmission.

[0191] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on a link quality between a source WTRU and an assistant WTRU (e.g., based on the transmission latency of a PDU between the two nodes). For example, the source WTRU may use an assistant WTRU to support an uplink transmission of the PDU. The WTRU may use scheme 1 described herein for the PDU transmission if a transmission latency of the PDU between the two nodes is smaller than a configured threshold. Otherwise, the WTRU may use scheme 3 described herein for the PDU transmission.

[0192] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on a link quality between the WTRU and a base station (e.g, based on a Uu RSRP). For example, a source WTRU may use an assistant WTRU to support an uplink transmission of the PDU. The source WTRU may use scheme 1 described herein for the PDU transmission if a Uu RSRP is smaller than a configured threshold. Otherwise, the WTRU may use scheme 3 described herein for the PDU transmission.

[0193] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on an uplink transmission power of the WTRU and/or an assistant WTRU. For example, the WTRU (e.g, a source WTRU) may use an assistant WTRU to support an uplink transmission of the PDU. The source WTRU may use scheme 3 described herein for the PDU transmission if the uplink transmission power of the source WTRU and/or the assistant WTRU is larger than a configured threshold. Otherwise, the source WTRU may use scheme 1 described herein for the PDU transmission.

[0194] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on a power headroom of a source WTRU and/or an assistant WTRU. For example, the WTRU (e.g., a source WTRU) may use an assistant WTRU to support the uplink transmission of the PDU. The source WTRU may use scheme 3 described herein for the PDU transmission if the power headroom of the source WTRU and/or the assistant WTRU is greater than a configured threshold. Otherwise, the source WTRU may use The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on a

[0195] The WTRU may determine a WTRU aggregation-based transmission scheme for a PDU based on the power class of a source WTRU and/or an assistant WTRU. For example, the WTRU (e.g., a source WTRU) may use an assistant WTRU to support the uplink transmission of the PDU. The source WTRU may use scheme 3 described herein for the PDU transmission if the maximum transmission power of the source WTRU and/or the assistant WTRU is greater than a configured threshold. Otherwise, the source WTRU may use scheme 1 described herein for the PDU transmission.

[0196] A WTRU may determine the number of WTRUs to be used for a PDU transmission based on one or more of the following.

[0197] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on the QoS of the PDU. As an example, the WTRU may be configured with a number of assistant WTRUs to perform an uplink transmission for a (e.g., each) RB/LCH. The WTRU may multiplex PDUs from one or multiple LCHs. The WTRU may determine the number of assistant WTRUs to use for the PDU transmission based on the LCH that uses the maximum number of assistant WTRUs. The WTRU may forward the PDUs to the set of assistant WTRUs and may request the assistant WTRUs to transmit the PDUs. For instance, for a low reliability PDU, the WTRU may request one assistant WTRU and form an aggregation group of two WTRUs to transmit the PDU. For a high reliability PDU, the WTRU may request two assistant WTRUs and form an aggregation group of three WTRUs to transmit the PDU.

[0198] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on the transmission delay of an Uu link. For example, the WTRU (e.g., source WTRU) may use one WTRU (e.g., the source WTRU itself) to transmit the PDU if the transmission delay in the Uu link is smaller than a configured threshold. Otherwise, the WTRU may use two or more WTRUs to transmit the PDU. [0199] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on the transmission delay in a sidelink. For example, the WTRU (e.g. , a source WTRU) may be configured with multiple assistant WTRUs. The WTRU may use one assistant WTRU to transmit the PDU if the transmission delay in a sidelink to the assistant WTRU is smaller than a configured threshold. Otherwise, the WTRU may use two or more assistant WTRUs to transmit the PDU.

[0200] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on one or more properties of uplink scheduled resources, such as, e.g., the number, size, and/or timing of the scheduled resources. For example, the WTRU may determine the number of WTRUs to be used for the PDU transmission based on the number of scheduled PUSCH resources for transmitting the PDU.

[0201] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on an uplink transmission power. For example, the WTRU (e.g., a source WTRU) may use one WTRU (e.g., the source WTRU itself) to transmit the PDU if the uplink transmission power of the WTRU is smaller than a configured threshold. Otherwise, the WTRU may use two or more WTRUs to transmit the PDU.

[0202] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on a sidelink transmission power. For example, the WTRU may use one WTRU to transmit the PDU if the sidelink transmission power of the WTRU is larger than a configured threshold. If the sidelink transmission power of the WTRU is smaller than the configured threshold, the WTRU may use two or more WTRUs to transmit the PDU.

[0203] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on a power headroom of the WTRU. For example, the WTRU may use one WTRU to transmit a PDU if the power headroom of the WTRU is larger than a configured threshold. Otherwise, the WTRU may use two or more WTRUs to transmit the PDU.

[0204] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on The power headroom of an assistant WTRU. For example, the WTRU may use two or more WTRUs to transmit the PDU if the power headroom of one or more assistant WTRUs is greater than a configured threshold. If there is no assistant WTRU with a power headroom greater than the configured threshold, the WTRU may transmit the PDU using one WTRU (e.g., the WTRU itself).

[0205] The WTRU may determine the number of WTRUs to be used for a PDU transmission based on a power class. For example, the WTRU may have multiple assistant WTRUs to support an uplink transmission of the PDU. The WTRU may use multiple assistant WTRUs to transmit the PDU if the maximum transmission power of the WTRU is smaller than a configured threshold. Otherwise, the WTRU may use an assistant WTRU to transmit the PDU.

[0206] A WTRU may determine a set of WTRU(s) to be used for a WTRU aggregation-based transmission of a PDU based on one or more of the following.

[0207] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on a configured precedence of one or more WTRUs. As an example, the WTRU may be configured to prioritize itself as one of the transmitters of the PDU regardless of other conditions. As another example, the WTRU may configured to prioritize itself as one of the transmitters if the WTRU satisfies one or more configured conditions (e.g., a Uu RSRP is greater than a configured threshold, a transmission power is smaller than a configured threshold, etc.). As yet another example, the WTRU may configured to prioritize an assistant WTRU as one of the transmitters and deprioritize the WTRU itself as one of the transmitters (e.g., the WTRU may only transmit the PDU if it cannot find a sufficient assistant WTRU to transmit the PDU).

[0208] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the power headroom of one or more WTRUs. As an example, the WTRU may prioritize the selection of WTRUs with a higher power headroom to transmit the PDU. As another example, the WTRU may prioritize the selection of WTRUs having a power headroom greater than a configured threshold to transmit the PDU.

[0209] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on a Uu link quality between a (e.g., each) WTRU and a base station (e.g., based on a Uu RSRP). For example, the WTRU may select the WTRUs with a higher Uu RSRP to transmit the PDU. The WTRU may also select the WTRUs with a Uu RSRP greater than a configured threshold to transmit the PDU.

[0210] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the sidelink transmission power of one or more WTRUs. For example, the WTRU (e.g., a source WTRU) may prioritize the selection of an assistant WTRU for the PDU transmission if the source WTRU may use a lower transmission power to communicate with the selected assistant WTRU via a sidelink.

[0211] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the link quality between a source WTRU and one or more assistant WTRUs. For example, the source WTRU may prioritize the selection of an assistant WTRU if there is a higher SL RSRP between the source WTRU and assistant WTRU. [0212] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the availability of an uplink grant. For example, the WTRU may prioritize itself for the PDU transmission if the WTRU has an uplink grant available to transmit the PDU within a configured window.

[0213] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the availability and timing of an uplink grant for a WTRU to transmit the PDU. For example, the WTRU may prioritize an assistant WTRU if the assistant WTRU has an uplink grant available to transmit the PDU within a configured window. As another example, the WTRU may prioritize an assistant WTRU if the assistant WTRU has the earliest uplink grant available to transmit the PDU within a configured window.

[0214] The WTRU may determine the set of WTRU(s) for performing a PDU transmission based on the availability of a sidelink grant. For example, a source WTRU may prioritize an assistant WTRU if the source WTRU has a sidelink grant available to transmit the PDU to the assistant WTRU within a configured window. [0215] A WTRU may forward a PDU to one or more assistant WTRUs and request the assistant WTRU(s) to transmit the PDU. In examples, the WTRU may forward (e.g., directly) the PDU to the assistant WTRU(s). In examples, the WTRU may encode the PDU and forward an encoded bitstream to the assistant WTRU(s). In examples, the WTRU may determine an RV for the assistant WTRU(s) to transmit. The WTRU may forward the determined RV to the assistant WTRU(s).

[0216] A WTRU (a source WTRU) may provide (e.g., indicate) information to one or more other WTRUs (e.g., assistant WTRUs) to support the other WTRUs in performing a WTRU aggregation-based transmission of a PDU. The information may be transmitted in an adaptation layer and/or may be transmitted together with the PDU to the other WTRUs. The information may be transmitted via sidelink control information (SCI), a MAC CE, and/or PC5 RRC signaling. The information may be transmitted using a sidelink channel such as a PSSCH and/or PSCCH. The information may indicate which PDU(s) may be transmitted in a resource (e.g., based on PDU indexes). The information may indicate uplink time and frequency resources that may be used for transmitting a PDU. The information may indicate a transmission pattern for a (e.g, each) WTRU in a group. The information may indicate an uplink channel (e.g, a PUCCH or PUSCH) for transmitting a PDU. The information may include uplink synchronization information. The information may include downlink synchronization information. The information may indicate a timing advance (TA). The information may indicate an uplink transmission mode. The information may indicate a WTRU aggregation-based transmission scheme. The information may indicate one or more transmission parameters, which may include a transmission beam, a transmission power, a HARQ redundant version (e.g, HARQ RV), a HARQ RV pattern, a MCS for a PDU (e.g. a MAC PDU), etc. The transmission parameters may be use for an initial transmission and/or a HARQ retransmission.

[0217] A WTRU may perform an initial transmission of a PDU, for example, via a non-WTRU aggregationbased transmission such as a mode A or mode B uplink transmission described herein. The WTRU may perform one or more HARQ retransmissions of the PDU, for example, using a WTRU aggregation-based transmission scheme. The WTRU may be configured with different HARQ retransmission modes including, for example, mode X HARQ retransmission (e.g. , HARQ retransmission by the same WTRU that may perform the initial transmission), mode Y HARQ retransmission (e.g., HARQ retransmission using a different WTRU compared to the initial transmission), and mode Z HARQ retransmission (e.g., HARQ retransmission using a WTRU aggregation-based scheme). The WTRU may determine which HARQ retransmission mode to use, for example, in response to a request from a base station to retransmit a PDU. The WTRU may determine the HARQ retransmission mode based on one or more of the following.

[0218] The WTRU may determine the HARQ retransmission mode for a PDU based on an indication from the base station. For example, the WTRU (e.g., a source WTRU) may be configured with an assistant WTRU. In response to receiving an indication from the base station to perform a mode X HARQ retransmission of the PDU, the source WTRU may retransmit the PDU by the source WTRU itself. In response to receiving an indication from the base station to perform a mode Y HARQ retransmission of the PDU, the source WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to retransmit the PDU. In response to receiving an indication to perform a mode Z HARQ retransmission of the PDU, the WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to perform a WTRU aggregation-based transmission of the PDU.

[0219] The WTRU may determine the HARQ retransmission mode based on the QoS of the PDU including, e.g., the set of RBs/LCHs included in the PDU, the HARQ retransmission scheme associated with the PDU, the remaining PDB of the PDU, etc. In an example, the WTRU (e.g., a source WTRU) may be configured with multiple (e.g., three) sets of RBs/LCHs. A first set of RBs/LCHs may require the WTRU to retransmit the PDU using the same WTRU as an initial transmission, a second set of RB/LCH may require the WTRU to retransmit the PDU using an assistant WTRU, and a third set of RB/LCH may require the WTRU to retransmit the PDU using the source WTRU itself and the assistant WTRU (e.g., a WTRU aggregation-based transmission). The WTRU may determine which type of HARQ retransmission to perform for the PDU based on the QoS of the PDU. If the PDU includes an RB/LCH requiring WTRU aggregation-based HARQ retransmission, the WTRU may perform a HARQ retransmission of the PDU based on WTRU aggregation (e.g., a mode Z HARQ retransmission). If the PDU includes an RB/LCH requiring HARQ retransmission by a different WTRU, the WTRU may forward the PDU to the assistant WTRU and request the assistant WTRU to retransmit the PDU (e.g., a mode Y HARQ retransmission). If the PDU doesn’t include either of the aforementioned types of RBs/LCHs, the WTRU may retransmit the PDU itself (e.g., a mode X HARQ retransmission).

[0220] As another example, the WTRU may determine which HARQ retransmission mode or scheme to use based on the remaining PDB of the PDU. If the remaining PDB of the PDU is smaller than a configured threshold, the WTRU may perform a mode Z HARQ retransmission. If the remaining PDB is larger than the configured threshold, the WTRU may perform a mode X HARQ retransmission.

[0221] A WTRU may determine the transmission parameters for a HARQ retransmission of a PDU including, for example, a transmission beam, a transmission power, a MCS, a HARQ redundant version (e.g., HARQ RV), etc. The WTRU may determine one or more of these transmission parameters based on an indication from a base station and/or a HARQ retransmission mode of the WTRU. For example, the WTRU may use RVO for an initial transmission. For a mode X HARQ retransmission, the WTRU (e.g., a source WTRU) may retransmit the PDU using a HARQ RV1 . For a mode Y HARQ retransmission, an assistant WTRU may retransmit the PDU using HARQ RVO. For a mode Z HARQ retransmission, both the source WTRU and the assistant WTRU may retransmit the PDU using HARQ RV1.

[0222] The WTRU may be configured with a transmission mode pattern for an initial transmission and a HARQ retransmission of a PDU. In examples, the transmission mode pattern may be configured per RB/LCH. The WTRU may determine which transmission mode pattern to use based on the set of RB/LCH included in the PDU. The WTRU may determine which transmission mode to use for the initial transmission and the HARQ retransmission of the PDU based on the transmission mode pattern associated with the PDU. In examples, the transmission mode pattern may be configured per uplink grant (e.g., configured grant). The WTRU may determine which transmission mode pattern to use based on the grant that the WTRU may use to transmit the PDU. Based on the determined transmission mode pattern, the WTRU (e.g., a source WTRU) may forward transmission related information (e.g., resources and/or transmission parameters) to an assistant WTRU to support the assistant WTRU in uplink transmissions.

[0223] A group of WTRUs may share resources. A WTRU (e.g., a group coordinator WTRU) may be configured to schedule transmission resources (e.g., Uu resources or sidelink resources) for the group of WTRUs. The WTRU may be configured with information about the group of WTRUs, which may indicate the ID of each WTRU in the group (e.g., a member ID). The WTRU may receive the information (e.g., member ID information) from a base station or from member WTRU(s) in the group. The WTRU may receive a set of resources (e.g., uplink resources or sidelink resources), which may be used by one or more WTRUs in the group for PDU transmissions (e.g., uplink transmissions). The WTRU may perform scheduling for the set of resources. For example, the WTRU may determine whether or not a resource may be used. The WTRU may further determine which WTRU may use the resource. The WTRU may send group coordination scheduling information (GCSI) to the base station.

[0224] A WTRU may receive an indication of group-common resources from another node. The WTRU (e.g., a member WTRU) may receive information about the group-common resources. For example, the WTRU may information regarding the time and/or frequency locations of the resources. The WTRU may information regarding one or more conditions for using the group-common resources. For example, the WTRU may receive an indication (e.g., configuration information) of one or more conditions associated with the QoS of a PDU (e.g., in a buffer) for using the group-common resources for the PDU. The WTRU may be configured with a set of RBs/LCHs that may use the group-common resource. The WTRU may be indicated (e.g., configured with) a minimum and/or maximum PDB of a PDU (e.g, in a buffer) as a criterion for using the group-common resources for the PDU. The WTRU may be indicated (e.g, configured with) a minimum and/or maximum amount of data in a buffer as a criterion for using the group-common resources. The WTRU may be provided (e.g, indicated) with a minimum time gap to a group-common resource as a criterion for using the group- common resource. The WTRU may receive the indication and/or configuration information described herein from a base station and/or another WTRU (e.g, a group coordinator WTRU).

[0225] A WTRU (e.g, a member WTRU) may determine whether to request resources for uplink transmissions from a group coordinator WTRU or from a base station. The WTRU may be configured to use one or more types of resources (e.g, group-common resources or WTRU-specific resources) and may determine which type of resources to use for a transmission. If the WTRU determines to use a group-common resource, the WTRU may perform the transmission using a resource dedicated to a group to which the WTRU may belong. The WTRU may request the group-common resource from the group coordinator WTRU. If the WTRU determines to use a WTRU-specific resource, the WTRU may request the base station to schedule such a WTRU-specific resource.

[0226] The WTRU may determine which type of resources to use based on one or more of the following. The WTRU may determine which type of resources to use for a PDU transmission based on configuration information received from the base station. For example, the WTRU may be configured to prioritize the use of group-common resources for a PDU transmission and may request, from the group coordinator WTRU, one or more resources in a set of group-common resources. [0227] The WTRU may determine which type of resources to use for a PDU transmission based on the QoS of the PDU. For example, the WTRU may be configured with multiple (e.g., two) sets of RBs/LCHs. A first set of RBs/LCHs may use group-common resources and a second set of RBs/LCHS may use WTRU-specific resources. The WTRU may determine whether to use group-common or WTRU-specific resources for the PDU based on whether the PDU belongs to the first or the second set of RBs/LCHs. If the PDU is associated with both sets of RBs/LCHs, the WTRU may prioritize the use of one type of resources (e.g, WTRU-specific resources) and request the prioritized type of resources for transmitting the PDU, or the WTRU may request both types of resources (e.g, WTRU-specific resources and group-common resources) to accommodate both types of RBs/LCHs. As another example, the WTRU may be configured to use a first type of resource (e.g, group-common resource) for the PDU if the PDB associated with the PDU is smaller than a configured threshold. If the PDB associated with the PDU is larger than the configured threshold, the WTRU may use a second type of resources (e.g, WTRU-specific resources) for the PDU.

[0228] The WTRU may determine which type of resources to use for a PDU transmission based on an amount data associated with the PDU in a buffer. For example, the WTRU may use a first type of resources (e.g, group-common resources) for the PDU if the amount of data associated with the PDU in a buffer is smaller than a configured threshold. If the amount of data associated with the PDU in the buffer is larger than the configured threshold, the WTRU may use a second type of resources (e.g, WTRU-specific resources) or use both types of resources.

[0229] The WTRU may determine which type of resources to use for a PDU transmission based on a time gap to a group-common resource and/or a WTRU-specific resource. For example, the WTRU may determine to request and use the earliest available resource.

[0230] A WTRU (e.g, a member WTRU) may indicates the availability of a PDU for transmission to a base station or to another WTRU (e.g, a group coordinator WTRU). For example, the WTRU may have a PDU to transmit in the uplink. The WTRU may request the base station to schedule an uplink grant for the PDU transmission, or request the group coordinator WTRU to allocate one or more resources from a set of group- common resources for the PDU transmission. The WTRU may indicate one or more of the following to the base station and/or the group coordinator WTRU. The WTRU may indicate the QoS of the PDU, the amount of data associated with PDU in a buffer, a Uu link quality between the WTRU and the base station (e.g, a Uu RSRP), a power headroom of the WTRU, etc.

[0231] A WTRU (e.g, a group coordinator WTRU) may determine whether or not a resource may be used by a group of WTRUs. The WTRU may make the determination based on the availability of a PDU in a buffer of one or more WTRUs in the group. For example, the WTRU may indicate to a base station that a group- common resource may not be used if the amount of data in the WTRU’s buffer is smaller than a configured threshold and/or if the WTRU has not received an indication from another WTRU in the group to use the group- common resource.

[0232] A WTRU (e.g., a group coordinator WTRU) may receive requests from multiple WTRUs, including itself, to transmit using a group-common resource. The WTRU may select one or more WTRUs to use the group-common resource based on one or more of the following.

[0233] The WTRU may select the one or more WTRUs based on a precedence associated with those WTRU(s). As an example, the WTRU may prioritize itself in using the resource. The WTRU may use the resource to transmit a PDU if the remaining PDB of the PDU is smaller than a configured threshold. If the remaining PDB of the PDU is larger than the configured threshold, the WTRU may allow other WTRU(s) to use the resource. As another example, the WTRU may be configured to prioritize one or more member WTRUs in using the resource. If the WTRU does not receive an indication from another WTRU or if the other WTRU is not allowed to use the resource (e.g., due to one or more conditions for using the resource not being met), the WTRU may be allowed to use the resource.

[0234] The WTRU may select the one or more WTRUs based on the timing of a request to use the resource. For example, the WTRU may prioritize the first WTRU that has requested the resource to use the resource.

[0235] The WTRU may select the one or more WTRUs based on a QoS associated with the transmission. For example, the WTRU may prioritize a WTRU that has a PDU with the lowest remaining PDB to use the resource.

[0236] The WTRU may select the one or more WTRUs based on the amount of data to be transmitted. For example, the WTRU may prioritize a WTRU with the largest amount data to transmit to use the resource.

[0237] The WTRU may select the one or more WTRUs based on the power headroom of each WTRU. As an example, the WTRU may prioritize a WTRU with the highest power headroom to use the resource. As another example, the WTRU may prioritize a WTRU with a power headroom greater than a configured threshold to use the resource.

[0238] A WTRU (e.g., a group coordinator WTRU) may indicate group scheduling coordination information (GSCI) to a base station. The GSCI may indicate the usage of one or more resources (e.g., future resources). The GSCI may indicate whether or not a group-common resource is used, which WTRU may have used or may be using a resource, a WTRU transmission pattern, and/or the like. As an example, the WTRU may be scheduled with an uplink resource before a set of resources is scheduled for a group. The WTRU may send the GSCI described herein to the base station using the resource scheduled for the WTRU. As another example, the WTRU may the GSCI using one or more resources scheduled for the group (e.g., the first resource scheduled for the group). The WTRU may send the GSCI via UCI and/or together with a PDU of the WTRU.

[0239] FIG. 6 illustrates an example of sending GSCI to a base station. As shown in FIG. 6, a group coordinator WTRU may be scheduled with a set of resources for a WTRU group. The WTRU may determine, for a (e.g., each) resource, whether it may be used and/or which WTRU may use the resource. The WTRU may send GSCI indicative of the determination to a base station. In an example, the WTRU may be scheduled with a resource before the set of resources for the group, and the WTRU may send the GSCI to the base station using the resource scheduled for the WTRU. The WTRU may indicate that the first resource may be used by itself, the next two resources may be used by WTRU1 and WTRU2, respectively, and so on. In examples, the WTRU may indicate that the last resource may not be used (e.g., since no WTRU may have data to transmit in the last resource), and the base station may use such an indication to schedule the last resource to another WTRU. In an example, the WTRU may perform a PDU transmission in the uplink and may send the GSCI together with the PDU (e.g., embed the GSCI in the PDU UCI transmitted together with the PDU). In this example, the WTRU may indicate that the next two resources may be used by WTRU1 and WTRU2, respectively. The WTRU may also indicate that the last resource may be unused.

[0240] A WTRU (e.g., a source WTRU) may be configured with a configure grant for WTRU aggregationbased transmissions. The configured grant may be used by a source WTRU and/or one or more assistant WTRUs. The WTRU may be configured with one or more of the following parameters for the configured grant: a number of PUSCH occasions per configured grant period, time and frequency resources for a PUSCH transmission, the SFN offset to a (e.g., each) PUSCH resource (e.g., a first SFN offset to a first PUSCH resource, a second SFN offset to a second PUSCH, etc.), a gap between two PUSCH resources, a number of repetitions per PUSCH resource, and/or the periodicity of the configured grant.

[0241] FIG. 7 illustrates an example of a configured grant for WTRU aggregation-based transmissions. As shown in FIG. 7, a source WTRU may be configured with a configured grant. The configured grant may have multiple (e.g., two) PUSCH resources per period, each of which may be associated with a repetition resource (e.g., denoted “Rep” in FIG. 7). The source WTRU may use a first PUSCH occasion and an assistant WTRU may use a second PUSCH occasion for a WTRU aggregation-based transmission. [0242] A WTRU may indicate its preferred configured grant to a base station. The WTRU may send the indication via RRC signaling (e.g., a WTRU assistant information message) or via a MAC CE. The WTRU may indicate one or more of the following for the preferred configured grant.

[0243] The WTRU may indicate the number of PUSCH occasions per configured grant period. The WTRU may determine the number of PUSCH occasions based on the number of assistant WTRUs available for a WTRU aggregation-based transmission. For example, the WTRU may be configured with scheme 3 described herein for WTRU aggregation and may use one assistant WTRU for a WTRU aggregation-based transmission. The WTRU may then request a configured grant with two PUSCH occasions, wherein the WTRU itself may use the first PUSCH occasion and the assistant WTRU may use the second PUSCH occasion.

[0244] The WTRU may indicate the time and/or frequency resources of a PUSCH transmission.

[0245] The WTRU may indicate the SFN offset to a PUSCH resource (e.g., a first SFN offset to a first

PUSCH, a second SFN offset to a second PUSCH, etc.). For example, the SFN offset to a first PUSCH may be determined based on an SFN offset to a traffic arrival time. The WTRU may indicate the SFN offset to the first PUSCH so that the time gap between the traffic arrival time and the timing of the PUSCH resource may be larger than a configured threshold. As another example, the WTRU may determine the SFN offset to a second PUSCH based on the transmission delay of a PDU between the source WTRU and the assistant WTRU.

[0246] The WTRU may indicate a gap between two PUSCH resources. For example, the WTRU may determine the SFN offset to a PUSCH occasion (e.g., the second PUSCH occasion described herein) based on the transmission delay of a PDU between the source WTRU and the assistant WTRU.

[0247] The WTRU may indicate the number of repetitions per PUSCH resource. For example, a source WTRU may determine to request an assistant WTRU to transmit using a repetition resource of an PUSCH occasion. The source WTRU may determine the number of repetitions based on the number of assistant WTRUs available for the WTRU aggregation-based transmission.

[0248] The WTRU may indicate the periodicity of the preferred configured grant. For example, the WTRU may determine the periodicity of the configured grant based on the periodicity of uplink traffic.

[0249] A WTRU (e.g., a source WTRU) may be configured with one or more triggering conditions for sending an indication of its preferred configured grant to a base station. The triggering conditions may be based on whether an assistant WTRU is available or unavailable. For example, if an assistant WTRU is unavailable, the source WTRU may trigger sending an indication to the base station to indicate the unavailability of the assistant WTRU. The WTRU may be configured with an SL RSRP threshold for determining the availability of the assistant WTRU. If the SL RSRP of the channel between the source WTRU and the assistant WTRU is smaller than the configured RSRP threshold, the WTRU may determine that the assistant WTRU is unavailable. As a result, the WTRU may request the network to deactivate a PUSCH occasion (e.g, the second PUSCH occasion described herein that would have been allocated to the assistant WTRU), or to reduce the number of repetitions per PUSCH occasion.

[0250] The triggering conditions may be based on whether the transmission delay of a PDU between the source WTRU and an assistant WTRU is greater than a configured threshold. For example, the WTRU may indicate its preferred gap between two PUSCH occasions if the transmission delay of a PDU between the source WTRU and the assistant WTRU is greater than a configured threshold.

[0251] In embodiments of present disclosure, a WTRU (e.g., a source WTRU) may determines whether to forward a PDU (e.g., a MAC PDU) to an assistant WTRU to perform a WTRU aggregation-based transmission of the PDU based on a QoS characteristic of the PDU (e.g, based on whether the PDU includes an RB/LCH with WTRU aggregation enabled). The WTRU may receive configuration regarding the assistant WTRU for an uplink transmission, a WTRU aggregation-based transmission scheme (e.g, PHY layer SFN combining using the same resource), a set of RBs/LCHs that may use WTRU aggregation-based transmissions, transmission parameters (e.g, transmission beam, transmission power, MCS, HARQ RV, etc.) associated with a WTRU aggregation-based transmission scheme (e.g, PHY layer SFN combining using the same resource), and/or transmission parameters for a non-WTRU aggregation mode. The WTRU may receive an uplink grant (e.g, a configured grant) for an uplink transmission. For a (e.g, each) PDU (e.g, a TB) to be transmitted in the scheduled grant, the WTRU may determine whether to perform a WTRU aggregation-based transmission of the PDU based on the QoS characteristic of the PDU (e.g, based on whether the PDU includes an RB/LCH with WTRU aggregation enabled). For example, if the PDU includes at least one RB/LCH with WTRU aggregation-based transmission enabled, the WTRU may forward the PDU to the assistant WTRU to perform a WTRU aggregation-based transmission. The WTRU (e.g, the source WTRU) may provide information such as an uplink transmission resource, a WTRU aggregation scheme, and/or one or more transmission parameters to the assistant WTRU (e.g, via an adaptation layer), and the information may be used by the assistant WTRU to transmit the PDU. The WTRU (e.g, the source WTRU) itself may also transmit the PDU using the transmission parameters associated with the configured WTRU aggregation-based transmission scheme. If the PDU does not include an RB/LCH with WTRU aggregation-based transmission enabled, the WTRU may transmit the PDU using non-WTRU aggregation-based transmission parameters. Using these techniques, the WTRU (e.g, a source UE), which may be capable of performing both WTRU aggregation-based and non- WTRU aggregation-based transmissions, may determine whether to transmit the PDU via an aggregationbased transmission in a scheduled resource.

[0252] In embodiments of the present disclosure, a WTRU (e.g., a source WTRU) may determine a group of WTRUs (e.g., including the source WTRU itself and one or more assistant WTRUs) to be used to transmit a PDU (e.g., a MAC PDU) based on a QoS characteristic of the PDU and/or the power headroom of the WTRUs in the group. The WTRU (e.g., the source WTRU) may receive configuration information regarding a group of assistant WTRUs that may be used for WTRU aggregation, and/or a number of WTRUs to be used to perform a WTRU aggregation-based transmission for an RB/LCH. The WTRU may receive an uplink transmission grant from a base station and/or power headroom reporting from the assistant WTRUs. In examples, for a PDU (e.g., a MAC PDU) to be transmitted, the WTRU may determine the number of WTRUs to be used for the transmission based on the QoS characteristic of the PDU. For example, the WTRU may determine the number of WTRUs to be used for the transmission based on the highest number of WTRUs needed by an RB/LCH multiplexed in the PDU. In examples, the WTRU may determine the set of WTRU to be used for the PDU transmission based on the power headroom of the WTRUs. For example, the WTRU may select one or more WTRUs with the highest power headroom and forward the PDU to the selected WTRUs for transmission. Using these techniques, the WTRU (e.g., a source UE), which may have a configured set of assistant WTRUs for a WTRU aggregation-based transmission, may determine which set of WTRUs (e.g., including the source WTRU itself and one or more assistant WTRUs) may be used to perform the transmission.

[0253] In embodiments of the present disclosure, a WTRU (e.g., an assistant WTRU) may determine which grant is scheduled for an uplink transmission and whether to use the grant to transmit a PDU for the assistant WTRU itself and/or for another WTRU. The WTRU may make the determination based on an indication from another node (e.g., a base station or a source WTRU). The WTRU (e.g., the assistant WTRU) may receive configuration information regarding an RNTI (e.g., a group-RNTI) associated with WTRU aggregation-based transmissions, and/or a DCI format for WTRU aggregation-based uplink scheduling (e.g., the DCI may indicate which WTRU (e.g., based on WTRU ID) may use a scheduled grant). The WTRU may receive configuration information regarding transmission parameters for a WTRU aggregation scheme (e.g., transmission beam, transmission power, MCS, HARQ RV, etc.), and/or the like. For example, the configuration information may indicate the HARQ RV of a PDU that may be transmitted in a WTRU aggregation-based transmission scheme (e.g., HARQ RVO for an SFN-based scheme, HARQ RV1 for a HARQ combining-based WTRU aggregation scheme, etc.). The configuration information may indicate respective member IDs of the WTRUs in an aggregated group. The WTRU (e.g., the assistant WTRU) may receive a PDU from a source WTRU and an uplink scheduling DCI. The WTRU may determine that the DCI is for a WTRU aggregation-based transmission if the DCI is scrambled by the configured group-RNTI. If a UL grant indicated by the DCI is associated with the member ID of the assistant WTRU, the assistant WTRU may determine a WTRU aggregation scheme and further determine a HARQ RV based on the determined WTRU aggregation scheme (e.g., based on number of UL grants indicated in the DCI). For example, if the DCI indicates one UL grant, the assistant WTRU may perform SFN-based WTRU aggregation and transmit HARQ RVO. Otherwise, the assistant WTRU may perform HARQ combining-based WTRU aggregation and transmit HARQ RV1 . If a UL grant indicated by the DCI is associated with the member ID of the assistant WTRU, the assistant WTRU may transmit a PDU from the source WTRU using the determined WTRU aggregation scheme. If the DCI is scrambled by a C-RNTI, the assistant WTRU may use a grant indicated by the DCI to transmit its own PDU. Using these techniques, the WTRU (e.g., an assistant WTRU), which may transmit a PDU for the WTRU itself and for another WTRU, may determine which PDU to transmit with an uplink grant and the network (e.g., a base station) may provide information (e.g., DCI scrambled with certain RNTI) to help the WTRU make that determination.

[0254] In embodiments of the present disclosure, a WTRU (e.g., a source WTRU) may determine a set of WTRUs for performing a HARQ retransmission of a PDU based on the set of WTRUs used for an initial transmission of the PDU and/or a QoS characteristic of the PDU (e.g., whether the PDU includes an RB/LCH that may allow its transmitting WTRUs to be changed). The WTRU (e.g., the source WTRU) may receive configuration information regarding an assistant WTRU for an uplink transmission, a set of RBs/LCHs and their associated HARQ retransmission modes, and/or transmission parameters (e.g., HARQ RV) associated with each HARQ retransmission mode. The configuration information regarding the RBs/LCHs may indicate a set of RBs/LCHs for which HARQ retransmissions may be performed using the same WTRU, a set of RBs/LCHs for which HARQ retransmissions may be performed using a different WTRU, and/or a set of RBs/LCHs for which HARQ retransmissions may be performed using WTRU aggregation. The configuration information regarding the transmission parameters may indicate that, for a HARQ retransmission, a source WTRU may transmit HARQ RV1 and an assistant WTRU may retransmit HARQ RVO. In these embodiments, the source WTRU may perform an initial transmission of a PDU (e.g., using a configured grant) and receive a request (or configuration information) from a base station to retransmit the PDU. The source WTRU may determines a HARQ retransmission mode for the PDU based on the QoS characteristic of the PDU (e.g., the RBs/LCHs multiplexed in the PDU and/or their associated HARQ retransmission modes). For example, if the PDU includes an RB/LCH for which HARQ retransmissions may be performed using WTRU aggregation, the source WTRU may forward the PDU to an assistant WTRU and request the assistant WTRU to perform a WTRU aggregation-based transmission of the PDU. The source WTRU itself may also perform a HARQ retransmission of the PDU (e.g., based on WTRU aggregation). If the PDU includes an RB/LCH for which HARQ retransmissions may be performed using a different WTRU, the source WTRU may forward the PDU to an assistant WTRU and indicate one or more transmission parameters (e.g., HARQ RV) to the assistant WTRU to perform a HARQ retransmission of the PDU (e.g., the assistant WTRU may retransmit the PDU using HARQ RVO). If the PDU includes an RB/LCH for which HARQ retransmissions may be performed using the same WTRU, the source WTRU may perform a HARQ retransmission of the PDU using parameters associated with that HARQ retransmission mode (e.g., the WTRU may transmit the PDU using HARQ RV1). Using these techniques, the WTRU (e.g., a source WTRU) may retransmit the PDU by taking into consideration the possibility of WTRU aggregation.

[0255] In embodiments of the present disclosure, resources may be shared by WTRUs in a group. A WTRU (e.g., a group coordinator WTRU) may determine whether or not a scheduled resource for a group may be using and/or which WTRU(s) may be using the resource based on an indication provided by one or more WTRUs in the group. The group coordinator WTRU may also determine the availability of a PDU from the group coordinator WTRU itself, and/or a QoS characteristic of a PDU from one or more other WTRUs in the group. The group coordinator WTRU may transmit information regarding the determinations to a base station (e.g., via UCI). The group coordinator WTRU may be configured to schedule uplink resources for the group of WTRUs, and may receive an uplink grant for the group of WTRUs. The group coordinator WTRU may further receive a request from one or more WTRUs in the group for UL transmission resources. The request may indicate the QoS characteristic of a PDU (e.g., a remaining PDB of the PDU) to be transmitted, and/or a power headroom of the requesting WTRU(s). The group coordinator WTRU may determine whether the scheduled uplink resource is used and/or which WTRU may use the resource based on the QoS characteristic (e.g., priority, remaining PDB, etc.) of a PDU of the group coordinator WTRU itself, the power headroom of the group coordinator WTRU and/or the other requesting WTRU(s) in the group, and/or the QoS characteristic of the PDU from the other requesting WTRU(s) in the group. For example, if the remaining PDB of the PDU from the group coordinator WTRU is smaller than a configured threshold, the group coordinator WTRU may determine to transmit the PDU using the scheduled resource. If the remaining PDB of the PDU from the group coordinator WTRU is larger than the configured threshold, the group coordinator WTRU may select another WTRU having the lowest PDB and/or a power headroom larger than a configured threshold to transmit in the scheduled resource. The group coordinator WTRU may notify the selected WTRU to transmit in the schedule resource. The group coordinator WTRU may also send an indication to the base station regarding which WTRU may be using the scheduled resource. Using these techniques, the WTRU (e.g., a group coordinator WTRU) may fulfill the responsibility for determining which WTRU(s) of a WTRU group may use a scheduled grant and indicating the determination/allocation to the network.

[0256] Although features and elements described above are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements. Although the implementations described herein may consider 3GPP specific protocols, it is understood that the implementations described herein are not restricted to this scenario and may be applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, New Radio (NR) or 5G specific protocols, it is understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

[0257] The processes described above may be implemented in a computer program, software, and/or firmware incorporated in a computer-readable medium for execution by a computer and/or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and/or optical media such as compact disc (CD)-ROM disks, and/or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and/or any host computer.

Claims

1 . A source wireless transmit/receive unit (WTRU), comprising: a processor configured to: receive configuration information from a network device, wherein the configuration information indicates a first assistant WTRU associated with the source WTRU and an aggregated transmission scheme for transmitting one or more protocol data units (PDUs) associated with the source WTRU via at least the first assistant WTRU; receive a grant of resources from the network device; determine whether to transmit the PDU using the aggregated transmission scheme; and based on a determination to transmit the PDU using the aggregated transmission scheme, send at least a first portion of the PDU and a first indication of the granted resources to the first assistant WTRU.

2. The source WTRU of claim 1 , wherein the configuration information received from the network device further indicates a second assistant WTRU associated with the source WTRU, and wherein, based on the determination to transmit the PDU using the aggregated transmission scheme, the processor is further configured to send a second portion of the PDU and a second indication of the granted resources to the second assistant WTRU.

3. The source WTRU of claim 1 , wherein, based on the determination to transmit the PDU using the aggregated transmission scheme, the processor is further configured to send a second portion of the PDU using the granted resources.

4. The source WTRU of claim 1 , wherein the processor is further configured to send an indication of the aggregated transmission scheme to the first assistant WTRU.

5. The source WTRU of claim 1 , wherein the processor is further configured to send an indication of a transmission parameter associated with the PDU to the first assistant WTRU, the transmission parameter indicating a transmission beam, a transmission power, a modulation and coding scheme, or a hybrid automatic repeat request (HARQ) redundancy version associated with the PDU.

6. The source WTRU of claim 1 , wherein the configuration information received from the network device further indicates a set of transmission parameters associated with the aggregated transmission scheme.

7. The source WTRU of claim 1 , wherein the determination of whether to transmit the PDU using the aggregated transmission scheme is made based at least on a quality of service (QoS) requirement associated with a PDU.

8. The source WTRU of claim 7, wherein the QoS requirement indicates that the PDU is associated with a radio bearer or a logical channel for which the aggregated transmission scheme is enabled.

9. The source WTRU of claim 7, wherein the configuration information received from the network device further indicates the QoS requirement.

10. The source WTRU of claim 1 , wherein the configuration information received from the network device indicates a plurality of assistant WTRUs associated with the source WTRU, and wherein the processor being configured to send at least the first portion of the PDU and the first indication of the granted resources to the first assistant WTRU comprises the processor being configured to select the first assistant WTRU from the plurality of assistant WTRUs based on a quality of service requirement associated with the PDU or a power headroom associated with the first assistant WTRU.

11. The source WTRU of claim 1 , wherein the processor is configured to receive the grant of resources via a downlink control information (DCI) message, and wherein the DCI message further indicates that the grant is associated with the aggregated transmission scheme.

12. The source WTRU of claim 1 , wherein the configuration information received from the network device further indicates a hybrid automatic repeat request (HARQ) retransmission scheme associated with the aggregated transmission scheme, and wherein the processor is further configured to re-transmit the PDU using the HARQ retransmission scheme.

13. The source WTRU of claim 1 , wherein the aggregated transmission scheme is based on single frequency network combining.

14. A method implemented by a source wireless transmit/receive unit (WTRU), the method comprising: receiving configuration information from a network device, wherein the configuration information indicates a first assistant WTRU associated with the source WTRU and an aggregated transmission scheme for transmitting one or more protocol data units (PDUs) associated with the source WTRU via at least the first assistant WTRU; receiving a grant of resources from the network device; determining whether to transmit the PDU using the aggregated transmission scheme; and based on a determination to transmit the PDU using the aggregated transmission scheme, sending at least a first portion of the PDU and a first indication of the granted resources to the first assistant WTRU.

15. The method of claim 14, wherein the configuration information received from the network device further indicates a second assistant WTRU associated with the source WTRU, and wherein the method further comprises sending, based on the determination to transmit the PDU using the aggregated transmission scheme, a second portion of the PDU and a second indication of the granted resources to the second assistant WTRU.

16. The method of claim 14, further comprising sending, based on the determination to transmit the PDU using the aggregated transmission scheme, a second portion of the PDU using the granted resources.

17. The method of claim 14, further comprising sending an indication of the aggregated transmission scheme to the first assistant WTRU.

18. The method of claim 14, further comprising sending an indication of a transmission parameter associated with the PDU to the first assistant WTRU, the transmission parameter indicating a transmission beam, a transmission power, a modulation and coding scheme, or a hybrid automatic repeat request (HARQ) redundancy version associated with the PDU.

19. The method of claim 14, wherein the determination of whether to transmit the PDU using the aggregated transmission scheme is made based at least on a quality of service (QoS) requirement associated with a PDU, the QoS requirement indicating that the PDU is associated with a radio bearer or a logical channel for which the aggregated transmission scheme is enabled.

20. The method of claim 14, wherein the configuration information received from the network device indicates a plurality of assistant WTRUs associated with the source WTRU, and wherein sending at least the first portion of the PDU and the first indication of the granted resources to the first assistant WTRU comprises selecting the first assistant WTRU from the plurality of assistant WTRUs based on a quality of service requirement associated with the PDU or a power headroom associated with the first assistant WTRU.

21 . The method of claim 14, the grant of resources is received via a downlink control information (DCI) message, and wherein the DCI message further indicates that the grant is associated with the aggregated transmission scheme.

22. The method of claim 14, wherein the configuration information received from the network device further indicates a hybrid automatic repeat request (HARQ) retransmission scheme associated with the aggregated transmission scheme, and wherein the method further comprises re-transmitting the PDU using the HARQ retransmission scheme.