WO2025212492A1

WO2025212492A1 - Data prioritization for rlc in xr

Info

Publication number: WO2025212492A1
Application number: PCT/US2025/022282
Authority: WO
Inventors: Tuong Duc HOANG; Ghyslain Pelletier; Faris ALFARHAN; Francois Periard; Jaya Rao; Tejaswinee LUTCHOOMUN; Senay NEGUSSE
Original assignee: InterDigital Patent Holdings Inc
Current assignee: InterDigital Patent Holdings Inc
Priority date: 2024-04-01
Filing date: 2025-03-31
Publication date: 2025-10-09
Anticipated expiration: 2026-10-01

Abstract

Systems, methods, and instrumentalities are described herein associated with data prioritization for radio link control (RLC) in extended reality (XR). For example, an RLC protocol data unit (PDU) may be determined (e.g., from multiple PDUs) to prioritize. The prioritization may be performed, for example, based on a reception status of a PDU set associated with the PDU set and/or a quality of service (QoS) associated with a PDU.

Description

DATA PRIORITIZATION FOR RLC IN XR

CROSS-REFERENCE TO RELATED APPLICATOINS

[0001] The application claims the benefit of U.S. Provisional Application 63/572,633, filed April, 1 2024, the contents of which are incorporated by reference in their entirety herein.

BACKGROUND

[0002] Mobile communications using wireless communication continue to evolve. A fifth generation of mobile communication radio access technology (RAT) may be referred to as 5G new radio (NR). A previous (legacy) generation of mobile communication RAT may be, for example, fourth generation (4G) long term evolution (LTE).

SUMMARY

[0003] Systems, methods, and instrumentalities are described herein associated with data prioritization for radio link control (RLC) in extended reality (XR). For example, an RLC protocol data unit (PDU) may be determined (e.g., from multiple PDUs) to prioritize. The prioritization may be performed, for example, based on a reception status of a PDU set associated with the PDU set and/or a quality of service (QoS) associated with a PDU.

[0004] A wireless transmit/receive unit (WTRU) may perform prioritization among multiple PDUs. The WTRU may transmit a first PDU (e.g., associated with a first PDU set). The WTRU may determine to retransmit the first PDU, for example, based on a received negative acknowledgement (NACK) report or based on an estimated reception successful value associated with the first PDU (e.g., being lower than a threshold).The first PDU may be associated with a first arrival time. The first PDU may be associated with a first sequence number. The WTRU may receive a second PDU (e.g., associated with an initial transmission). The second PDU may be associated with the second arrival time. The second PDU may be associated with a second PDU. The WTRU may receive at least one of a first reception status (e.g., associated with the first PDU) or a second reception status (e.g., associated with the second PDU). The WTRU may receive (e.g., from a network) a radio link control status report that may indicate the at least one of the first reception status or the second reception status. The WTRU may determine a transmission priority, for example, associated with a retransmission of the first PDU and a transmission (e.g., initial transmission) of the second PDU. The transmission priority may be determine based on one or more of a first QoS associated with the first PDU, a second QOS associated with the second PDU, or at least one of the first reception status or the second reception status. The first QoS may be associated with a first PDU importance. The second QoS may be associated with a second PDU importance.The transmission priority may indicate that the first PDU has a higher priority than the second PDU. The WTRU may send a transmission based on the transmission priority. The transmission may include the first PDU (e.g., retransmission of the first PDU) or the second PDU (e.g., initial transmission of the second PDU). The transmission may include the retransmission of the first PDU if the transmission priority indicates that the first PDU has a higher priority than the second PDU. The transmission may include the transmission (e.g., initial transmission) of the second PDU, for example, if the transmission priority indicates that the second PDU has a higher priority than the first PDU. The WTRU may send a second transmission. The WTRU may send a second transmission (e.g., after the first transmission). The second transmission may include the second PDU (e.g., initial transmission of the second PDU), for example, if the first transmission does not include the second PDU. The second transmission may include the first PDU (e.g., retransmission of the first PDU), for example, if the first transmission does not include the retransmission of the first PDU. The WTRU may determine to discard a PDU. The WTRU may determine to discard the first PDU.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0006] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0007] FIG. 1 C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0008] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0009] FIG. 2 illustrates an example RLC header to indicate the sequence of a PDU in a PDU set.

DETAILED DESCRIPTION

[0010] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0011] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a ON 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and/or a “ST A”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0012] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements. [0013] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0014] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0015] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0016] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0017] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0018] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., a eNB and a gNB).

[0019] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0020] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115.

[0021] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology. [0022] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/113 or a different RAT.

[0023] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0024] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, 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 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0025] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 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 may be integrated together in an electronic package or chip.

[0026] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0027] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0028] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0029] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0030] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like. [0031] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0032] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

[0033] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0034] 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 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0035] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0036] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0037] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0038] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

[0039] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0040] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0041] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. [0042] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0043] In representative embodiments, the other network 112 may be a WLAN.

[0044] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0045] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0046] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0047] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0048] 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

802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0049] WLAN systems, which may support multiple channels, and channel bandwidths, such as

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

[0050] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for

802.11 ah is 6 MHz to 26 MHz depending on the country code. [0051] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0052] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0053] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0054] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0055] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E- UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0056] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0057] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

[0058] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernetbased, and the like. [0059] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet- switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0060] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0061] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[0062] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may performing testing using over-the-air wireless communications.

[0063] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

[0064] Systems, methods, and instrumentalities are described herein associated with data prioritization for radio link control (RLC) in extended reality (XR). For example, an RLC protocol data unit (PDU) may be determined (e.g., from multiple PDUs) to prioritize. The prioritization may be performed, for example, based on a reception status of a PDU set associated with the PDU set and/or a quality of service (QoS) associated with a PDU.

[0065] A wireless transmit/receive unit (WTRU) may perform prioritization among multiple PDUs. The WTRU may transmit a first PDU (e.g., associated with a first PDU set). The WTRU may determine to retransmit the first PDU, for example, based on a received negative acknowledgement (NACK) report or based on an estimated reception successful value associated with the first PDU (e.g., being lower than a threshold).The first PDU may be associated with a first arrival time. The first PDU may be associated with a first sequence number. The WTRU may receive a second PDU (e.g., associated with an initial transmission). The second PDU may be associated with the second arrival time. The second PDU may be associated with a second PDU. The WTRU may receive at least one of a first reception status (e.g., associated with the first PDU) or a second reception status (e.g., associated with the second PDU). The WTRU may receive (e.g., from a network) a radio link control status report that may indicate the at least one of the first reception status or the second reception status. The WTRU may determine a transmission priority, for example, associated with a retransmission of the first PDU and a transmission (e.g., initial transmission) of the second PDU. The transmission priority may be determine based on one or more of a first QoS associated with the first PDU, a second QOS associated with the second PDU, or at least one of the first reception status or the second reception status. The first QoS may be associated with a first PDU importance. The second QoS may be associated with a second PDU importance.The transmission priority may indicate that the first PDU has a higher priority than the second PDU. The WTRU may send a transmission based on the transmission priority. The transmission may include the first PDU (e.g., retransmission of the first PDU) or the second PDU (e.g., initial transmission of the second PDU). The transmission may include the retransmission of the first PDU if the transmission priority indicates that the first PDU has a higher priority than the second PDU. The transmission may include the transmission (e.g., initial transmission) of the second PDU, for example, if the transmission priority indicates that the second PDU has a higher priority than the first PDU. The WTRU may send a second transmission. The WTRU may send a second transmission (e.g., after the first transmission). The second transmission may include the second PDU (e.g., initial transmission of the second PDU), for example, if the first transmission does not include the second PDU. The second transmission may include the first PDU (e.g., retransmission of the first PDU), for example, if the first transmission does not include the retransmission of the first PDU. The WTRU may determine to discard a PDU. The WTRU may determine to discard the first PDU.

[0066] A wireless transmit/receive unit may perform prioritization among multiple PDUs. The WTRU may transmit a first PDU associated with a first PDU set. The WTRU may determine to retransmit the first PDU (e.g., based on receiving a NACK associated with the first PDU, based on an estimated reception successful value associated with the first PDU set being below a threshold). The WTRU may receive a second PDU associated with a second PDU set. The second PDU set may be the same or different as the first PDU set. The WTRU may receive a reception status associated with at least one of the first PDU set or the second PDU set (e.g., first reception status associated with the first PDU set, second reception status associated with the second PDU set). The WTRU may determine a transmission priority, for example, associated with the first PDU set and the second PDU set. The transmission priority may be determined based on one or more of a received reception status (e.g., associated with a PDU set) or a QoS (e.g., associated with a PDU set). The transmission priority may indicate a priority associated with transmitting the first PDU set and transmitting the second PDU set. For example, the transmission priority may indicate that the first PDU set has a higher transmitting priority than the second PDU set. The transmission priority may indicate that the second PDU set has a higher transmitting priority than the second PDU set. The transmission priority may indicate that the first PDU set has a same transmitting priority as the second PDU set. The WTRU may send a transmission based on the transmission priority. For example, the WTRU may send a transmission comprising the first PDU set if the transmission priority indicates that the first PDU set has a higher transmitting priority than the second PDU set. The WTRU may send a transmission comprising the second PDU set if the transmission priority indicates that the second PDU set has a higher transmitting priority than the first PDU set. The WTRU may transmit (e.g., in a subsequent transmission) the PDU set associated with the lower transmitting priority (e.g., the PDU set not transmitted in the initial transmission).

[0067] Features and/or details associated with radio link control (RLC) acknowledge mode (AM) operation (e.g., in NR) may be provided herein.

[0068] RLC AM may work according to transmitting/receiving window-based operation (e.g., in which (e.g., all) PDUs transmitted from the transmitter (Tx) to the receiver (Rx) may be (e.g., guaranteed to be) received successfully and acknowledged by the Rx RLC entity). A (e.g., each) RLC protocol data unit (PDU) may have an (e.g., its) associated sequence number (SN) and Tx and Rx maintain its own transmission and reception window with a size (e.g., size of AM_Window_Size). The Tx WTRU may refrain from transmitting (e.g., may not be allowed to transmit) more data, for example, if the gap between the acknowledged SN and the current SN is greater than the window size.

[0069] The acknowledgement procedure may be implemented (e.g., according to the polling-response procedure), for example, in which the RLC AM transmission entity may poll the status of its transmitted PDU (e.g., after a configured number of transmitted PDU (e.g., pollPDU) and/or transmitted byes (e.g., poll Byte)).

[0070] An RLC AM transmission entity may (e.g., be allowed to) poll the RLC AM reception entity, for example, if one or the following conditions are satisfied: the amount of data without polling is larger than a threshold (e.g., PDU_WITHOUT_POLL >= pollPDU; or BYTE_WITHOUT_POLL >= pollByte); its buffer (e.g., initial and retransmission buffer) may be (e.g., will be) empty after the current PDU; its window is stalling (e.g., gap between the current SN and the ACKED SN is greater than the window size); etc.

[0071] The WTRU may consider the RLC PDU for retransmission, for example, based on reception of negative acknowledgement (NACK) feedback (e.g., in the STATUS PDU of a RLC PDU). The WTRU may retransmit the PDU (e.g., with the polling request), for example, if a duration (e.g., t-Pollretransmit duration/timer) expires and/or it has not received a positive acknowledgement from the receiver. The RLC entity may indicate (e.g., to an upper layer) and/or declare radio link failure (RLF), for example, if the number of retransmission reaches a threshold (e.g., maximumThreshold).

[0072] The entity may (e.g., at the RLC AM reception) send a control RLC PDU (e.g., STATUS PDU) to the RLC AM transmission entity, for example, to indicate until which PDU (e.g., PDU segment) it receives (e.g., via an ACK) and which PDU (e.g., PDU segment) is not received correctly (e.g., via an NACK), for example, if the RLC AM reception entity receives the poll request from Tx, or the duration (e.g., via a timer) to assemble a PDU-segment (t-Reassembly) expires. The WTRU may (e.g., be allowed to) transmit the STATUS report (e.g., if the StatusProhibit is expired), for example, to control the frequency of STATUS report transmission.

[0073] Details and/or features associated with extended Reality (XR) may be provided herein.

[0074] The term extended Reality (XR) may include different types of immersive experiences, for example, including one or more of Virtual Reality (VR), Augmented Reality (AR), Mixed Reality (MR), or the realities interpolated among them. Virtual Reality (VR) may include a rendered version of a delivered visual and audio scene. The rendering may mimic (e.g., be designed to mimic) the visual (e.g., stereoscopic 3D) and audio sensory stimuli of the real world as naturally as possible to an observer or user as they move within the limits defined by the application. Augmented Reality (AR) may include when a user is provided with additional information or artificially generated objects/items, or content overlaid upon their current environment. Mixed Reality (MR) may include a form of AR (e.g., an advanced form of AR) where some virtual elements are inserted into the physical scene with the intent to provide the illusion that these elements are part of the real scene. XR may include (e.g., all) real-and-virtual combined environments and human-machine interactions generated by computer technology and wearables.

[0075] The notion of immersion in the context of XR applications/services may include the sense of being surrounded by the virtual environment as well as providing the feeling of being physically and spatially located in the virtual environment. The levels of virtuality may range from partial sensory inputs to fully immersive multi-sensory inputs leading to a virtual reality practically indiscernible from actual reality.

[0076] In XR services and applications, the traffic may include data/PDUs which may be associated with an application data unit (ADU), PDU set or data burst. In examples, the PDUs associated with (e.g., belonging to) a PDU set may be associated with different segments or components of a video frame or a video slice. A data burst may include one or more PDU sets that may be transmitted/received over a time window. For example, a number of PDUs in an PDU set or data burst transmitted in UL and/or received in DL may be dependent on the type of the media frame (e.g., 3D video frame, audio frame).

[0077] In XR applications, the WTRU may transmit XR traffic including one or more PDUs/PDU sets in UL (e.g., pose, gesture, video data) and/or may receive XR traffic in DL (e.g., video, audio, haptics). Such traffic may be transmitted and/or received periodically or aperiodically in one or more data flows (e.g., QoS flows). During UL transmissions, XR traffic may arrive from application layer at WTRU and/or from different devices/terminals/WTRUs (e.g., via sidelink) at different time instances. Such XR traffic may be characterized by different attributes such as variable payload sizes per PDU set, variable number of PDUs per PDU set, variable per-PDU/PDU set level importance, or different levels of inter-dependencies between PDUs/PDUs sets. Such XR traffic (e.g., PDU/PDU sets) received by the WTRU may experience different delays, jitter, data rate, and/or loss rate. For ensuring QoS and high user experience (QoE), data transmission/reception and other associated functions (e.g., prioritization, multiplexing, scheduling) may be performed on a timely basis with XR awareness (e.g., awareness of PDU set attributes).

[0078] Characteristics of XR for decoding operations may be provided.

[0079] A PDU set (e.g., which may include inter-dependent PDUs) may be introduced, for example, in XR. XR applications may support one or more of the following types of PDU sets: reliable delivery of all PDUs in the set; conditional delivery, e.g., the transmission of a PDU set is unsuccessful if (e.g., when) at least one (e.g., possibly specific) PDU fails transmission; “X out of Y” e.g., the transmission of a PDU set may be successful if (e.g., when) X PDUs of the PDU set of Y PDUs are received (e.g., if/when FEC is used or if/when additional layered encoding is used and assigned to the same PDU set); etc.

[0080] In examples (e.g., for an RLC AM system), the WTRU may refrain from discarding (e.g., may not be allowed to discard) a RLC SDU, e.g., if it is associated with a Sequence Number (SN) (e.g., as the WTRU may not be allowed to create a SN gap in RLC AM), the RLC PDU retransmission may be prioritized (e.g., always be prioritized) over an initial RLC PDU, for example, in RLC AM.

[0081] In examples (e.g., for XR application(s)), transmission of user data may be successful, for example, if (e.g., even if) a subset of PDUs (e.g., only a subset of PDUs) are successfully transmitted for a given set of PDUs, e.g., if FEC is used, x out of y PDU may be sufficient. PDUs for which transmission has not yet completed may no longer be transmitted (e.g., no longer be required to be transmitted), e.g., for PDUs part of a PDU set on which PDU set discard is applied or for PDUs part of a successfully received PDU set (e.g., for FEC).

[0082] Sequential treatment of PDUs according to the arrival time may not be beneficial (e.g., for XR applications), for example, because PDUs in the QoS flow may have different QoS requirement. Prioritizing (e.g., always prioritizing) the RLC PDU retransmission may not be favorable as the reliability and latency requirement of a retransmitted PDU may not necessarily be as high as other PDU especially for the FEC type PDU set, which may not rely on the retransmitted PDU to decode an XR frame.

[0083] Prioritization among RLC PDUs (e.g., initial RLC PDU vs. retransmission RLC PDU) may be enabled, performed, and/or described herein. A transmission window may be advanced. A PDU may be removed from a transmit window, for example, to support fast operation of an acknowledged mode protocols that is using a transmit window.

[0084] A WTRU may determine which PDU (e.g., RLC PDU) to prioritize. The WTRU may determine which PDU (e.g., RLC PDU) among multiple (e.g., two) PDUs (e.g., a first PDU and a second PDU) to prioritize (e.g., initial RLC PDU vs. retransmission RLC PDU; the first PDU vs. the second PDU; etc.), for example, based on reception status of the PDU (e.g., a first reception status associated with the first PDU and/or a second reception status associated with the second PDU) or PDU set associated with each PDU and/or the QoS (e.g., remaining PSDB, Importance) associated with each PDU (e.g., a first QoS associated with the first PDU and a second QoS associated with the second PDU).

[0085] A WTRU may transmit a first RLC PDU associated with a first PDU set. The WTRU may (e.g., determine to) retransmit the first RLC PDU. The WTRU may (e.g., determine to) retransmit the first RLC PDU, for example, based on a NACK report (e.g., receiving (e.g., from the gNB) a NACK report) for the RLC PDU. The WTRU may (e.g., determine to) retransmit the first RLC PDU, for example, based on an estimated reception successful of the first RLC PDU being smaller than a threshold.

[0086] The WTRU may receive a second RLC PDU associated with a second PDU set (e.g., from the upper layer). The second PDU set may be the same as the first PDU set or different from the first PDU set.

[0087] The WTRU may receive (e.g., from the gNB) a reception status (e.g., receive a first reception status associated with the first PDU and/or first PDU set, and/or receive a second reception status associated with the second PDU and/or the second PDU set). The reception status may be associated with the first and/or the second PDU set.

[0088] The WTRU may determine which RLC PDU (e.g., first RLC PDU vs. second RLC PDU) to prioritize for transmission (e.g., during LCP procedure), for example, based on the reception status (e.g., at least one of the reception status associated with each PDU (e.g., the first reception status and/or second reception status) and/or the QoS (e.g., the remaining PSDB, the Importance) associated with each PDU (e.g., a first QoS associated with the first PDU and a second QoS associated with the second PDU). The WTRU may discard the NACKed PDU, for example, if it receives ACK status for the first PDU set (e.g., X PDUs of the PDU set of Y PDUs are received from the gNB). The WTRU may prioritize the second PDU, for example, if the WTRU does not meet (e.g., cannot meet) the PSDB of the first PDU (e.g., remaining PSDB of the first PDU is zero). The WTRU may retransmit (e.g., still retransmit) the first PDU (e.g., in a subsequent transmission). The WTRU may prioritize the second PDU, for example, if its importance is higher than the first PDU.

[0089] The WTRU may transmit the prioritized RLC PDU.

[0090] The WTRU may discard an unnecessary RLC PDU (e.g., based on the prioritization as described herein), for example, which may help improve spectrum efficiency.

[0091] The WTRU may (e.g., based on the prioritization as described herein) prioritize (e.g., flexibly prioritize) the more important transmission (e.g., WTRU may prioritize initial transmission PDU instead of always prioritizing the retransmission RLC PDU), for example, which may help improve the QoS of the XR service.

[0092] A network may be defined.

[0093] The network may include one or more of the following: a base station (e.g., gNB, TRP, RAN node, access node), a core network function (e.g. AMF, SMF, PCF, NEF), an application function (e.g. edge server function, remote server function), etc.

[0094] A WTRU may include a (e.g., any) XR device/node which may come in variety of form factors. A WTRU (e.g. XR WTRU) may include, but may not be limited to, one or more of the following: Head Mounted Displays (HMD), optical see-through glasses and camera see-through HMDs for AR and MR, mobile devices with positional tracking and camera, wearables, haptic gloves, haptic body suit, haptic shoes, etc. In addition to the above, several different types of XR WTRU may be envisioned based on XR device functions for e.g. as display, camera, sensors, sensor processing, wireless connectivity, XR/Media processing and power supply, to be provided by one or more devices, wearables, actuators, controllers and/or accessories. One or more device/nodes/WTRUs may be grouped into a collaborative XR group for supporting any of XR applications/experience/services. [0095] Sidelink (SL) operation may be enabled, applied, and/or performed.

[0096] Details associated with UL transmission of the WTRU may be described herein. Examples described herein may be applicable for sidelink enhancement, for example, in which the network may be replaced (e.g., by another WTRU). The WTRU may transmit/receive to/from another WTRU, for example, instead of transmitting/receiving to/from the network.

[0097] The WTRU may receive configuration information (e.g., may be configured with something).

[0098] The WTRU receiving configuration information (e.g., being configured with something) may include and/or indicate that the WTRU is (pre)configured (e.g., with something, such as, for example, configuration information), and/or the WTRU receives the network configuration information of something. The network configuration information may be received via signaling (e.g., a SIB, a dedicated RRC message, MAC CE, or DCI). For example, the WTRU receiving configuration information indicating (e.g., may be configured with) a threshold may be equivalent to the WTRU being preconfigured (e.g., the WTRU stores the configuration information) with the threshold or equivalent to the WTRU receiving, from the network (e.g., via SIB, RRC, MAC CE, and/or DCI) the threshold.

[0099] A PDU set may be described herein.

[0100] A PDU set may include a PDU set, for example, in its integrity and/or the PDUs that make up the PDU set. A PDU set may include one or more PDUs that make up the PDU set. A PDU set (e.g., all PDUs making up the PDU set) may be considered as a (e.g., one) frame. A (e.g., one) PDU set may include one or more PDUs. A (e.g., some) PDU set may be associated with a PDU Set Integrated Handling Indication (PSIHI) type, e.g., PDUs (e.g., all PDUs) of the PDU set may be used (e.g., needed) at the application by the PSDB and/or PSDD for the application to be able to decode the PDU set. Other PDU sets may not be of the PSIHI type, e.g., the application may (e.g., still be able to) decode the PDU set if some PDUs of the PDU set are lost and/or delayed beyond the PSDB and/or PSDD. In examples, successful reception of a number/percentage of PDUs in a PDU set (e.g., 80% of the PDUs of the PDU set) may be sufficient for the successful decoding of the PDU set at the application. In examples, successful reception of a number/percentage of PDUs in a PDU set (e.g., 70% of the PDUs of the PDU set) may be sufficient for the successful decoding of the PDU set at the application.

[0101] Details associated with a data burst may be described herein.

[0102] A data burst may include data produced by the application in a short period of time, for example, comprising PDUs from one or more PDU Sets. Such attributes, associations and inter-dependencies (e.g., intra-PDU set and/or inter-PDU set) may include the start/end indication of a PDU set/data burst (e.g., via sequence number, start/end indication, timestamp), start/end time, duration, payload sizes, periodicity, importance/priority, and/or QoS (e.g. PSDB). The attributes, associations and inter-dependencies may be visible, for example, to the AS-layers (e.g. with associated IDs) and/or handled at the AS layers with the awareness of the association during data transmission in UL and reception in DL.

[0103] Details associated with a data set may be provided herein.

[0104] A Data Set may be used to represent a PDU-segment (e.g., a RLC PDU-segment), one or more PDUs, a subset of a PDU set, a PDU set, a Data Burst, etc.

[0105] Details associated with a service data unit (SDU) and/or a PDU may be provided herein.

[0106] SDU and PDU may be used interchangeably. SDU-segment and PDU-segment may be used interchangeably. Examples associated with a PDU may apply for a SDU and vice versa. Examples associated with a PDU-segment may apply for a SDU-segment and vice versa.

[0107] Details associated with a sequence number (SN) may be provided herein.

[0108] An SN may include the sequence number of a SDU, PDU, and/or PDU set. The sequence number may be used interchangeably, for example, in a (e.g., any) layer. For example, the SN may indicate a PDCP SN and/or RLC SN. The RLC SN can be used interchangeably with PDCP SN and a different (e.g., any other) SN. In examples, the SN may convey information on the PDUs belonging to a PDU set, for example, [1 ,1], [1 ,2], [1 ,3] may be used for PDUs 1, 2 and 3 of PDU set 1.

[0109] A QoS may be associated with a data set.

[0110] QoS associated with a Data Set may be used to indicate one or more of the following: one or more parameters (e.g., QoS parameters) of a PDU/PDU-segment associated with the data set; one or more parameters of a PDU set associated with the data set; one or more parameters of a data burst associated with the data set; etc.

[0111] QoS associated with a data set may be used to indicate, for example, one or more parameters (e.g., QoS parameters) of a PDU/PDU-segment associated with the Data Set. The parameters of a PDU/PDU-segment may include one or more of the following: a PDU Importance (e.g., which may be used to indicate the Importance of the PDU set associated with the PDU, the relative Importance of the PDU in the PDU set, the relative Importance of the PDU in a Data Burst, and/or the relative Importance of the in the QoS flow), a priority; a latency requirement of the PDU/PDU-segment (e.g., which may include a packet delay budget (PDB), a remaining PDB, etc.); a reliability requirement of the PDU (e.g., Packet Error Rate (PER)); a maximum data burst volume (MDBV); a type of PDU/PDU-segment (e.g., periodic vs. aperiodic); the periodicity of the PDU/PDU-segment; a size of the PDU/PDU-segment; etc.

[0112] QoS associated with a data set may be used to indicate, for example, one or more parameters of a PDU Set (e.g., QoS parameters) associated with the Data Set. The parameters of the PDU set may include one or more of the following: a PDU Set Importance (e.g., which may be used to indicate the relative importance of a PDU Set compared to other PDU Sets within a QoS Flow); a PDU set Priority; a latency requirement associated with the PDU set; a PDU set integrated handling indication (PSI HI) (e.g., which may indicate whether (e.g., all) PDUs of a PDU set are associated with the usage (e.g., needed for the usage) of the PDU set, for example, by an application layer); a reliability requirement of a PDU set (e.g., PDU set error rate (PSER)); a volume of a PDU set; a type of PDU set; a periodicity of the PDU set; etc.

[0113] The latency requirement associated with the PDU set may be associated with a PDU Set Delay Budget (PSDB), for example, which may be used to indicate the maximum time between reception of the first PDU (e.g., at the UPF in DL, at the WTRU in UL) and the successful delivery of the last arrived PDU of a PDU Set (e.g., at the WTRU in DL, at the UPF in UL). PSDB may be a parameter (e.g., an optional parameter when provided). The PSDB may supersede the PDB. The latency requirement associated with the PDU set may be associated with a remaining PSDB. The latency requirement associated with the PDU set may be associated with a PDU Set Delivery Deadline (PSDD). The PSDD may include a deadline (e.g., the absolute deadline) where a PDU (e.g., last PDU) of a PDU set may be received (e.g., may need to be received) at the application, for example, so that the application can make use of the PDU set.

[0114] The type of the PDU set may include one or more of the following: a first type of PDU set, which may be associated with (e.g., require) delivery (e.g., reliable delivery) of PDU(s) (e.g., all PDUs) in the set; a second type of PDU set, in which the transmission of a PDU set may be unsuccessful if (e.g., when) a (e.g., at least one) PDU (e.g., specific PDU) fails transmission; a third type of PDU set, in which the transmission of a PDU set may be successful if (e.g., when) X PDUs of the PDU set of Y PDUs are received. For example, if (e.g., when) FEC is used or if (e.g., when) additional layered encoding is used and assigned to the same PDU set.

[0115] A reliability requirement of a PDU Set (e.g., such as PDU Set Error Rate (PSER)) may be used to indicate one or more of the following: an upper bound for the rate of PDU Sets that have been processed by the sender of a link layer protocol (e.g., RLC in RAN of a 3GPP access) but that are not successfully delivered by the corresponding receiver to the upper layer (e.g., PDCP in RAN of a 3GPP access); an upper bound for the rate of PDUs per PDU set that have been processed by the sender of a link layer protocol (e.g. RLC in RAN of a 3GPP access) but that are not successfully delivered by the corresponding receiver to the upper layer (e.g. PDCP in RAN of a 3GPP access); an upper bound for the rate of PDUs per PDU set are not successfully received by the receiver of the upper layer (e.g. PDCP in RAN of a 3GPP access); etc.

[0116] The volume of the PDU set may include one or more of the following: the size of a (e.g., each) PDU; the number of PDUs in the PDU set; etc. [0117] QoS associated with a data set may be used to indicate, for example, one or more parameters of a Data Burst associated with the Data Set. The one or more parameters of a data burst associated with the data set may include the volume of the Data Burst. The volume of the data burst may include one or more of the following: the size of a (e.g., each) PDU in the Data Burst; a number of PDU sets in the Data Burst; the volume of each PDU set in the Data Burst; etc.

[0118] Details associated with a QoS of a PDU/PDU-segment may be provided.

[0119] The QoS of a PDU/PDU-segment may be used to describe the QoS of the PDU/PDU-segment itself and the QoS associated with the PDU set of the PDU/PDU-segment. The QoS of a PDU/PDU- segment may include one or more of the following: a PDU Importance, a priority, a latency requirement of the PDU/PDU-segment, a maximum data burst volume (MDBV), a type of PDU/PDU-segment, the periodicity of the PDU/PDU-segment, a size of the PDU/PDU-segment, a PDU set importance, a PDU set priority, a latency requirement associated with the PDU set (e.g., PSDB, remaining PSDB, PSDD, PSIHI), a reliability requirement of the PDU set (e.g., PSER), the volume of the PDU set, etc.

[0120] The STATUS PDU may indicate (e.g., be used to denote) a message/transmission from the WTRU to the network. The STATUS PDU may indicate the reception status of the WTRU. A message including (e.g., containing) the receiver status information may be referred to (e.g., denoted) as a STATUS PDU. A STATUS PDU may be sent as a control PDU (e.g., as described herein). The PDU may include control information (e.g., only include control information). The STATUS PDU may be sent as a data PDU (e.g., in which the PDU may include both the control information (e.g., such as the receiver status information) and the data). A STATUS PDU may include a PDU in a (e.g., any) layer (e.g., such as SDAP, PDCP, RLC, MAC, or PHY). The term STATUS PDU may be used interchangeably with STATUS report.

[0121] An SN may be assigned, for example, for a RLC SDU.

[0122] A WTRU may receive configuration information (e.g., may be configured with multiple RLC subwindows).

[0123] In examples, the WTRU may receive configuration information indicating (e.g., may be configured with) a (e.g., multiple) RLC sub-window to perform uplink transmission of RLC PDUs. The WTRU may (e.g., determine to) assign arrival (e.g., each arrival) RLC SDU to a (e.g., one) sub-window to process. The WTRU may map data to a (e.g., each) sub-window using PDU set granularity. The PDU(s) (e.g., all PDUs) in a PDU set may be mapped to a (e.g., one) sub-window. This approach may be motivated to allow the WTRU to parallelly process RLC SDU in a (e.g., each) sub-window, for example, which may help to avoid a (e.g., one) PDU set with high Importance and/or low PSDB being blocked by a different (e.g., other) PDU set with low Importance and/or high PSDB. A (e.g., each) sub-window may be associated with one or any combination of the following: the delay requirement (e.g., PSDB, remaining PSDB, PSDD) of each RLC SDU; the importance of a (e.g., each) RLC SDU; the type of RLC treatment for the PDU; etc.

[0124] A (e.g., each) sub-window may be associated with the delay requirement (e.g., PSDB, remaining PSDB, PSDD) of a (e.g., each) RLC SDU. For example, the WTRU may receive configuration information indicating (e.g., be configured with) multiple sub-windows, in which a (e.g., each) sub-window may be associated with a remaining time or PSDB of a PDU set. For example, the WTRU may receive configuration information indicating (e.g., be configured with) two sub-windows, in which the first subwindow may be associated with the PDU sets having remaining PSDB being smaller than a configured threshold and the second sub-window may be associated with the PDU sets having remaining PSDB being larger than a threshold.

[0125] A (e.g., each) sub-window may be associated with the importance of each RLC SDU. For example, the WTRU may receive configuration information indicating (e.g., be configured with) two subwindows, in which the first sub-window may be associated with Importance being greater than a configured threshold or PSI level being less than a configured threshold and the second sub-window may be associated with the Importance being smaller than a configured threshold.

[0126] A (e.g., each) sub-window may be associated with the type of RLC treatment for the PDU (e.g., whether SN gap is allowed for the sub-window). For example, the WTRU may receive configuration information indicating (e.g., be configured with) two sub-windows, in which the first sub-window may allow RLC SN gap operation, and the second sub-window may not allow RLC SN gap operation. For example, the WTRU may receive configuration information indicating (e.g., be configured with) two sub-windows, in which the first sub-window may be associated with In-order delivery and the second sub-window may be associated with out-of-order delivery.

[0127] A WTRU may determine a (e.g., which) sub-window to put a RLC SDU.

[0128] The WTRU may assign a sub-window for the RLC SDU, for example, based on arrival of a RLC SDU. The WTRU may determine a (e.g., which) sub-window to assign for the RLC SDU, for example, based on the property of the RLC SDU (e.g., such as QoS and the configured property associated with the sub-window). For example, the WTRU may put the PDU/PDU-segment associated to the PDU set with the Importance being greater than a threshold and/or the PSI level being less than a threshold to the first subwindow. The WTRU may put the PDU/PDU-segment associated to the PDU set with the Importance being smaller than a threshold or the PSI level being greater than a threshold in the second sub-window. For example, the WTRU may put the PDU set with PSDB being smaller than a configured threshold in the first sub-window. For example, the WTRU may put the PDU set with PSDB being larger than the configured threshold in the second sub-window. [0129] A WTRU may indicate the SN for a RLC SDU.

[0130] In examples, the WTRU may assign/allocate a sequence number/ID to one or more RLC SDUs (e.g., which may be processed in each RLC). The WTRU may indicate the sequence number/ID of an (e.g., each) RLC SDU in the RLC header associated with each SDU. Such sequence number/ID assigned to the RLC SDU may be the same or different than that assigned by the PDCP entity, for example. The WTRU may assign the sequence number/ID for each RLC SDU based on one or more of the following: the subwindow associated with the RLC SDU (e.g., the number of bits may indicate the sub-window may be the function of the maximum number of sub-windows); the order of the PDU set associated with the RLC SDU (e.g., the number of bits to indicate the order of the PDU set may be a function of the maximum number of PDU sets to handle per sub-window); the order of the RLC SDU in the PDU set (e.g., the number bits to indicate the order of the RLC SDU may be the function of the maximum number of PDUs in a PDU set); etc.

[0131] In examples (e.g., as shown in FIG. 2), the WTRU may (e.g., be configured to) indicate the sequence of 18 bits. In examples, four (4) bits may be used (e.g., maximum 16 sub-windows) to indicate the number of sub-windows, four (4) bits (e.g., maximum 16 PDUs in a PDU set) may be used to indicate the order of RLC SDU in a PDU set, and ten (10) bits may be used to indicate the order of PDU set (e.g., maximum 1024 PDU sets per sub-window).

[0132] FIG. 2 illustrates an example RLC header to indicate the sequence of a PDU in a PDU set.

[0133] Details associated with RLC status reporting may be provided herein.

[0134] A WTRU may indicate PDU set information, for example, in the RLC PDU.

[0135] In examples, the WTRU may perform a transmission (e.g., UL transmission) for the Data Set(s). The WTRU may indicate PDU set information. The PDU set information may include one or more of the following: the PDU set sequence; the start, end, number of PDUs in the PDU set; and/or the order of a (e.g., each) PDU in the PDU set. Such PDU set information may be indicated, for example, in a header of a protocol L2 (e.g., such as PDCP header, RLC header, or MAC header). In examples, such information may be transmitted separately (e.g., not in-band), for example, in a control PDU. Such information may be used by the network (e.g., help the network) to decode the PDU set information. Such information may be used (e.g., by the network) to report the reception status of one or more PDU sets to the WTRU.

[0136] A WTRU may receive status (e.g., RLC Status) reporting from the network.

[0137] The WTRU may receive a RLC STATUS report from the network (e.g., which may indicate the reception status of one or more PDU sets). The WTRU may receive the RLC status report from the network for example, based on (e.g., upon) indicating PDU set information in each PDU/PDU-segment and performing UL transmission. The WTRU may discard and/or deprioritize (e.g., by transmitting in a best- effort manner) one or more remaining PDU/PDU-segments in a PDU set, for example, if the PDU set is successfully received from the network] (e.g., where the successful reception of the PDU set may be determined based on a successful reception of a certain percent or a certain number of PDUs in the PDU set.

[0138] The WTRU may receive PDU set information for a (e.g., each) PDU/PDU-segment from the network.

[0139] In examples, the WTRU may perform reception (e.g., DL reception). The WTRU may receive PDU set information. The PDU set information may include one or more of the following: the PDU set sequence; the start, end, number of PDUs in the PDU set; and/or the order of each PDU in the PDU set. Such PDU set information may be indicated, for example, in a header of a protocol L2 (e.g., such as PDCP header, RLC header, or MAC header). The WTRU may decode the PDU set information. The WTRU may report the reception status of one or more PDU sets.

[0140] The WTRU may report status information of RLC PDUZPDU-segment(s) and/or PDU set(s) (e.g,, an individual RLC PDU/PDU-segment and/or PDU set).

[0141] In examples, the WTRU may perform DL reception. The WTRU may report a (e.g., its) RLC Reception status. The WTRU may use a RLC Control PDU to report the reception status of the (e.g., its) RLC AM reception entity. The WTRU may (e.g., alternatively) use a RLC Data PDU to report the reception status of the (e.g., its) RLC AM reception entity. The WTRU may indicate the status of the (e.g., its) RLC reception entity in the header of an (e.g., its) RLC SDU. The PDU (e.g., PDU including the status of the receiver) may be considered as a STATUS PDU or STATUS report. The WTRU may indicate one more of the following in the STATUS PDU: the reception status of a (e.g., each individual) RLC PDU/PDU-segment, in which the content of this individual status report may follow the conventional design (e.g., the WTRU may indicate the SN associated with the next not received RLC SDU which may not be reported as missing and NACK status of the RLC PDU/PDU-segment which may have been detected as lost); the reception status of one or more PDU sets; etc.

[0142] In examples, the WTRU may receive configuration information indicating (e.g., be configured with) a STATUS PDU format (e.g., more than one (e.g., two) STATUS PDU formats). A (e.g., each) format may be used for a (e.g., one) type of reporting (e.g., PDU set based reporting vs. individual PDU/PDU- segment based reporting). The WTRU may indicate (e.g., in one bitfield of the RLC header) which STATUS format it is using, for example, based on a report indicating the status of the RLC receiving entity. In examples, the WTRU may receive configuration information indicating (e.g., be configured with) a (e.g., one) STATUS PDU format, in which the WTRU may report the status of individual PDUs/PDU-segments and/or the status of one or more PDU set. The WTRU may indicate the status of a (e.g., each) PDU set, for example, if it is successfully received. The WTRU may indicate the status of individual PDU/PDU-segment, in which the WTRU may follow the conventional indication (e.g., alternatively), for example, if the PDU set has not received successfully. This approach may be motivated to allowed the network to be aware of which PDU/PDU-segment needs to be retransmitted. The WTRU may refrain from retransmitting (e.g., not need to retransmit) a (e.g., any) PDU of the PDU set, for example, if the PDU set is received successfully. The NACK status of individual PDU in the successfully received PDU set may not be necessary. The gNB may be aware (e.g., need to be aware) of which PDU/PDU-segment as NACK to retransmit, for example, if (e.g., when) a PDU set has not been received successfully.

[0143] For the first type of PDU set (e.g., reliable delivery of all PDUs in the set), the WTRU may indicate (e.g., only indicate) the status of the PDU set (e.g., ACK for the PDU set), for example, if the PDUs (e.g., all PDUs) in the PDU set are received successfully. For the third type of PDU set (e.g., X out of Y), the WTRU may indicate the status of the PDU set (e.g., ACK for the PDU set), for example, if at least X out of Y PDUs in the PDU set is received successfully. The value of X or X/Y (e.g., the successful reception ratio for a PDU set) may be configured by the network.

[0144] The WTRU may trigger RLC Status reporting for reception (e.g., DL reception).

[0145] The WTRU may trigger sending a STATUS PDU for the gNB. The WTRU may send the STATUS PDU based on one or any combination of the following: reception of polling from the network; an indication and/or configuration information from the network; a reception status associated with one or more grants (e.g., configured grant, dynamic grant); a reception status associated with one or more HARQ IDs; the amount of data (e.g., the number of PDUs, PDU sets, the number of bytes) received; periodicity of STATUS report; a duration (e.g., t-StatusReport duration, for example, via a timer or a t-StatusReport timer) expires; the reception status available of a configured number (e.g., one or more) of PDU sets; the reception status available of more specific PDU/PDU-segment in the PDU set, in which the successfully reception of such PDUs/PDU-segments may be critical for the successfully reception of the PDU set; detection of SN gap in its reception buffer; detection of HARQ NACK feedback in its buffer; etc.

[0146] The WTRU may send the STATUS PDU, for example, based on an indication and/or configuration information from (e.g., indicated by) the network. For example, the WTRU may be configured/indicated to enable WTRU autonomous RLC status reporting. The WTRU may report its RLC status to the gNB. The WTRU may receive configuration information indicating (e.g., be configured with) one or more triggering conditions to report its RLC status. The WTRU may report its RLC status, for example, based on one or more configured triggering condition being satisfied.

[0147] The WTRU may send the STATUS PDU, for example, based on a reception status associated with one or more grants (e.g., configured grant, dynamic grant). For example, the WTRU may be scheduled with one or more configured grants. The WTRU may trigger STATUS reporting, for example, if a NACK is determined for reception in one or more configured grants. For example, the WTRU may be scheduled with a (e.g., one) configured grant (e.g., in which each period may include multiple PDSCH transmissions). The WTRU may trigger a STATUS reporting, for example, if the number of PDSCH received successfully within a period is smaller than a configured threshold. The WTRU may (e.g., alternatively) trigger STATUS reporting, for example, if it determines that a configured number of PDSCH transmissions received is below a threshold (e.g., fails to receive a configured number of PDSCHs, which may be within a configured grant period).

[0148] The WTRU may send the STATUS PDU based on reception status associated with one or more HARQ IDs. For example, the WTRU may receive configuration information indicating (e.g., be configured with) a (e.g., one) HARQ ID to enable WTRU autonomous STATUS reporting. The WTRU may trigger STATUS reporting, for example, if it receives one or more NACKs associated with the HARQ ID. The WTRU may (e.g., alternatively) trigger STATUS reporting, for example, if it receives a (e.g., one or more) NACK feedback associated with the HARQ ID and the WTRU has not received ACK feedback associated with the HARQ ID after a period.

[0149] The WTRU may send the STATUS PDU, for example, based on the amount of data (e.g., the number of PDUs, PDU sets, the number of bytes) received. In examples, the WTRU may trigger a STATUS report after reception of a configured number of PDUs, PDU sets, and/or Bytes.

[0150] The WTRU may send the STATUS PDU based on a periodicity of a STATUS report. For example, the WTRU may be configured to periodically transmit the status of its receiving RLC entity.

[0151] The WTRU may send the STATUS PDU based on the reception status (e.g., available) reception status of a configured number (e.g., one or more) of PDU sets. For example, the WTRU may trigger a STATUS report, for example, if it successfully detects reception of one or more PDU sets, in which the number of successfully received PDU sets to trigger a STATUS report (e.g., where the number of successfully received PDU sets to trigger a STATUS report may be configured or fixed (e.g., as one)). For example, the WTRU may trigger a STATUS report, for example, if it determines a (e.g., one or more) PDU set is not received (e.g., if it fails to receive one or more PDU sets). A number of PDU set reception failures to trigger STATUS reporting may be configured by the network or fixed (e.g., as one).

[0152] The WTRU may send the STATUS PDU based on the reception status of one or more specific PDU/PDU-segments in a PDU set, in which the successfully reception of such PDUs/PDU-segments may be critical for the successfully reception of the PDU set.

[0153] The WTRU may send the STATUS PDU based on a duration (e.g., t-StatusReport duration, via a timer or t-StatusReport timer). The WTRU may (re-)start tracking a duration (e.g., via the timer), for example, after a (e.g., each) reception of a PDU (e.g., possibly only within a PDU set). The WTRU may transmit a STATUS PDU based on expiry of the duration (e.g., via the timer). This approach may be motivated to trigger the WTRU reporting the RLC reception status for periodic traffic, in which the WTRU may trigger the status report based on missing a period. The WTRU may stop tracking the duration (e.g., the timer) based on one or more of the following: reception of the whole PDU set, determining ACK for the whole PDU set, or receiving the last PDU within a PDU set. For example, the WTRU may (re-)start a duration (e.g., the timer) after a (e.g., each) transmission of a STATUS report. The WTRU may transmit a STATUS PDU upon expiry of the duration (e.g., timer). This approach may be motivated to allow the WTRU to transmit a STATUS PDU after each period.

[0154] The WTRU may send the STATUS PDU based on detection of SN gap in its reception buffer. In examples, the WTRU may send a STATUS PDU based on detection of a SN gap. In examples, the WTRU may (re)start tracking a duration (e.g., timer, t-StatusReport timer) based on detection of a SN gap. The WTRU may transmit the STATUS PDU based on expiry of the duration (e.g., timer). The WTRU may stop tracking the duration (e.g., the timer) or restart the duration (e.g., timer) based on successfully reception of the PDU/PDU-segment associated with the SN. For example, if the WTRU receives SDUs with a specific SN (e.g., SN 1, 2, 3, then 5), the WTRU may trigger transmission of an RLC status report or start tracking a duration (e.g., a t-StatusReport duration/timer) to transmit such report based on its expiry. For example, once SDU with SN 4 is received, the WTRU may stop tracking the duration (e.g., the t-StatusReport timer). The SN gap may be determined by the WTRU based on RLC and/or PDCP sequence numbers.

[0155] The WTRU may send the STATUS PDU based on detection of HARQ NACK feedback in the buffer. In examples, the WTRU may send a STATUS PDU based on detection of one or more HARQ NACKs from a HARQ ID. In examples, the WTRU may start tracking a duration (e.g., a timer, t- StatusReport timer) based on detection of one or more HARQ NACKs from a HARQ ID. Such HARQ ID may be associated with a DRB or PDU set configured for RLC low-latency retransmission flag. Such HARQ ID may (e.g., alternatively) be configured to enable WTRU autonomous STATUS reporting. Such HARQ ID may be configured to be associated with one or more RB, and/or PDU set, for example, which may use (e.g., require) low latency retransmission. The WTRU may transmit the STATUS PDU, for example, based on expiry of the duration (e.g., timer). The WTRU may stop tracking the duration (e.g., the timer), for example, after receiving an HARQ ACK, associated with the HARQ ID.

[0156] Prioritizing among multiple PDU/PDU-segments may be provided, enabled, and/or performed.

[0157] A WTRU may determine to (re)transmit a RLC PDU/PDU-segment.

[0158] In examples, the WTRU may transmit a RLC PDU/PDU-segment. The WTRU may trigger retransmission of the RLC PDU/PDU-segment. The triggering may be based on reception of NACK report for the RLC PDU from the network or the estimated reception successful probability the PDU being smaller than a threshold.

[0159] The WTRU may perform LCP, for example, based on the multiplexing-priority associated with a (e.g., each) RLC PDU/PDU-segment.

[0160] The WTRU may perform prioritization among RLC PDUs/PDU-segments, for example, to multiplex in a MAC PDU (e.g., in LCP procedure) based on the multiplexing-priority associated with each RLC PDU/PDU-segment. The WTRU may multiplex (e.g., sequentially multiplex) a PDU/PDU-segment to a MAC PDU, for example, in the ascending order of multiplexing-priority associated with each PDU/PDU- segment. The WTRU may prioritize the PDU/PDU-segment with the lower SN, for example, if the two PDU/PDU-segments have the same multiplexing-priority. The WTRU may prioritize the PDU/PDU-segment that arrives sooner. The WTRU may determine the multiplexing-priority associated with each PDU/PDU- segment based on one or any combination of the following: whether out-of-order delivery is configured for the RB/LCH or not; whether the PDU/PDU-segment is the initial transmission or retransmission; whether a PDU-segment is subject for retransmission; whether the delay requirement of the PDU/PDU-segment (e.g., PSDB, remaining PSDB, the PSDD) is smaller than a threshold; whether the delay requirement of the PDU/PDU-segment (e.g., the PSDB, remaining PSDB, the PSDD) is smaller than a first threshold (e.g., of multiple thresholds); whether the PDU/PDU-segment corresponds to a best-effort PDUs (e.g., best effort PDUs may be a PDU that satisfy a configured condition associated with treating the PDU in a best effort manner); etc.

[0161] The WTRU may determine the multiplexing-priority associated with a (e.g., each) PDU/PDU- segment based on whether out-of-order delivery is configured for the RB/LCH or not. The WTRU may (e.g., be required/configured to) perform in-order delivery of its PDCP PDU to upper layer (e.g., application layer), for example, if out-of-order delivery is not configured for the RB/LCH. The WTRU may prioritize PDU/PDU-segment retransmission over PDU/PDU-segment initial transmission. For initial transmission PDUs/PDU-segments, the WTRU may follow in-sequence delivery of the SN. The WTRU may prioritize the PDU/PDU-segment with the lowest SN. The WTRU may perform out-of-order delivery to its PDCP PDU to upper layer (e.g., application layer), for example, if out-of-order delivery is configured for the RB/LCH. The WTRU may refrain from prioritizing (e.g., not always prioritize) a PDU/PDU-segment for retransmission over PDU/PDU-segment for initial transmission. The WTRU may refrain from prioritizing (e.g., not always prioritize) the PDU/PDU-segment with lowest SN. The WTRU may prioritize the PDU/PDU-segment based on other criteria such as the latency requirement (e.g., prioritize the PDU/PDU-segment with smaller PSDD). [0162] The WTRU may determine the multiplexing-priority associated with each PDU/PDU-segment based on whether the PDU/PDU-segment is the initial transmission or retransmission. The WTRU may assign a higher multiplexing-priority for retransmission PDU/PDU-segment, for example, if other condition(s) are the same (e.g., both PDU/PDU-segment having PSDB being smaller than a configured threshold). The WTRU may assign a higher multiplexing-priority for retransmission PDU/PDU-segment regardless of other condition(s). The WTRU may refrain from considering (e.g., not consider) whether the PDU/PDU-segment is the initial transmission or retransmission to assign the multiplexing-priority for the PDU/PDU-segment. The WTRU may use other criteria to assign the multiplexing-priority for each PDU/PDU-set.

[0163] The WTRU may determine the multiplexing-priority associated with a (e.g., each) PDU/PDU- segment, for example, based on whether a PDU-segment is subject for retransmission. The WTRU may assign the highest multiplexing-priority for the PDU-segment, for example, if a PDU-segment is subject for retransmission. The WTRU may prioritize multiplexing the PDU-segment first (e.g., in the MAC PDU).

[0164] The WTRU may determine the multiplexing-priority associated with a (e.g., each) PDU/PDU- segment, for example, based on whether the delay requirement of the PDU/PDU-segment (e.g., the PSDB, remaining PSDB, the PSDD) is smaller than a configured threshold. The WTRU may assign a higher multiplexing-priority for a PDU/PDU-segment, for example, if the delay requirement of the PDU/PDU- segment is smaller than the threshold. The WTRU may assign a lower multiplexing-priority for a PDU/PDU- segment, for example, if the delay requirement of the PDU/PDU-segment is larger than a threshold.

[0165] The WTRU may determine the multiplexing-priority associated with a (e.g., each) PDU/PDU- segment based on whether the delay requirement of the PDU/PDU-segment (e.g., the PSDB, remaining PSDB, the PSDD) is smaller than a threshold (e.g., from multiple thresholds, for example, whether the delay requirement is smaller than a first threshold, a second threshold, etc.). The WTRU may be configured with multiple delay requirement thresholds. For example, the WTRU may be configured with N delay requirement thresholds, for example, which may be from #VALUE(1) to #VALUE(N). The WTRU may determine the multiplexing-priority for a (e.g., each) PDU/PDU-segment, for example, based on whether the delay requirement of the PDU/PDU-segment is smaller than a delay threshold from multiple thresholds (e.g., the value of n in #VALUE(n)) out of multiple configured thresholds from #VALUE(1) to #VALUE(N). The PDU/PDU-segment with a lower associated delay threshold may be assigned to a higher multiplexingpriority. The PDU/PDU-segment with a higher associated delay threshold may be assigned to a lower multiplexing-priority. The two PDU/PDU-segment with the same associated delay threshold may be assigned to the same multiplexing-priority. For example, the two PDU/PDU-segment having remaining PSDB requirement being smaller than #VALUE(n) (e.g., #VALUE(1) < #VALUE(n) < #VALUE(N)) may be assigned the same multiplexing-priority.

[0166] The WTRU may determine the multiplexing-priority associated with a (e.g., each) PDU/PDU- segment, for example, based on whether the PDU/PDU-segment corresponds to a best-effort PDU(s) (e.g., PDU(s) which satisfy a condition (e.g., best-effort condition). The WTRU may assign the lowest priority for a best-effort PDU/PDU-segment. The WTRU may transmit the best-effort PDU/PDU-segment with the besteffort resource or forwarding configuration (e.g., LCH). The WTRU may multiplex a best-effort PDU/PDU- segment (e.g., in a MAC PDU), for example, if all the higher multiplexing-priority are multiplexed or transmitted. The WTRU may discard a best effort PDU/PDU-segment (e.g., one (1), multiple, or all besteffort PDU/PDU-segments). A PDU/PDU-segment may be a best-effort PDU/PDU-segment based on one or more of the following: the PDU/PDU-segment may not satisfy the delay requirement (e.g., PSDD has passed, remaining PSDB is zero); the PDU/PDU-segment is associated with a PDU or PDU set discarded by higher layer (e.g., PDCP); the PDU/PDU-segment is association with a number of retransmissions attempts being greater than a configured threshold; the PDU/PDU-segment associated with the PDU set is successfully received by the network; etc.

[0167] In examples, a WTRU may perform prioritization among RLC PDU/PDU-segments to multiplex in a PDU (e.g., MAC PDU), for example, based on the multiplexing-priority associated with each RLC PDU/PDU-segment. The WTRU may be configured with a delay threshold. The WTRU may prioritize the PDU/PDU-segment retransmission over PDU/PDU-segment initial transmission, for example, if both PDU/PDU-segments satisfy the delay threshold or both PDU/PDU-segment do not satisfy the delay threshold. The WTRU may prioritize the PDU/PDU-segment with a lower SN, for example, if multiple PDUs/PDU-segments have the same multiplexing-priority. The WTRU may be configured with a multiplexing-priority from 1 to 5, in which the lowest multiplexing-priority value (e.g., 1) may be associated with the highest multiplexing-priority. The WTRU may assign the highest multiplexing-priority (i.e., multiplexing-priority = 1) for a PDU/PDU-segment for retransmission having delay requirement being smaller than the configured threshold. The WTRU may assign the second highest multiplexing-priority (i.e., multiplexing-priority = 2) for a PDU/PDU-segment for initial transmission having delay requirement being smaller than the configured threshold. The WTRU may assign the third highest multiplexing-priority (i.e., multiplexing-priority = 3) for a PDU/PDU-segment for retransmission having delay requirement being larger than a configured threshold. The WTRU may assign the fourth multiplexing-priority (i.e., multiplexingpriority = 4) for a PDU/PDU-segment for initial transmission having delay requirement being larger than a configured threshold. The WTRU may assign the lowest multiplexing-priority (i.e., multiplexing-priority = 5) for a best-effort PDUs/PDU-segments. The best-effort PDUs/PDU-segment may be the PDU/PDU-segment associated with the PDU set successfully received by the network. The best-effort PDUs/PDU-segment may be the PDU/PDU-segment that satisfies the delay requirement (e.g., the PSDD has passed, remaining PSDB is zero). The best-effort PDUs/PDU-segment may be the PDU/PDU-segment with the number of retransmissions attempts being greater than a configured threshold.

[0168] In examples, the WTRU may perform prioritization among a RLC PDU/PDU-segment to multiplex (e.g., in a MAC PDU) based on the multiplexing-priority associated with each RLC PDU/PDU-segment. The WTRU may be configured with a delay threshold. The WTRU may refrain from differentiating (e.g., not differentiate) between initial transmission and retransmission PDU/PDU-segment. The WTRU may prioritize the PDU/PDU-segment with lower SN, for example, if multiple PDUs/PDU-segments have the same multiplexing-priority. The WTRU may be configured with multiple multiplexing-priorities (e.g., three (3) multiplexing-priorities). The WTRU may assign the highest multiplexing-priority (e.g., multiplexing-priority = 1) for a PDU/PDU-segment having delay requirement being smaller than the configured threshold. The WTRU may assign the second highest multiplexing-priority (e.g., multiplexing-priority = 2) for a PDU/PDU- segment having delay requirement being larger than the configured threshold. The WTRU may assign the lowest multiplexing-priority (e.g., multiplexing-priority =3) for a best-effort PDUs/PDU-segments.

[0169] The WTRU may performs prioritization among RLC PDU/PDU-segment to multiplex (e.g., in a MAC PDU) based on the multiplexing-priority associated with each RLC PDU/PDU-segment. The WTRU may be configured with an N delay threshold (e.g., #VALUE(1), ..., #VALUE(n), ..., #VALUE(N)), in which #VALUE(1) < #VALUE(n) < #VALUE(N). The WTRU may prioritize the PDU/PDU-segment retransmission over PDU/PDU-segment initial transmission, for example, if both PDU/PDU-segments satisfy the delay threshold #VALUE(n) or both PDU/PDU-segments do not satisfy the delay threshold #VALUE(N). The WTRU may prioritize the PDU/PDU-segment with lower SN, for example, if multiple PDUs/PDU-segments have the same multiplexing-priority. The WTRU may be configured with 2N+3 multiplexing-priority from 1 to 2N+3, in which the lowest multiplexing-priority value (e.g., 1) may be associated with the highest multiplexing-priority. The WTRU may assign the highest multiplexing-priority (e.g., multiplexing-priority = 1) for a PDU/PDU-segment for retransmission having delay requirement being smaller than #VALUE(1). The WTRU may assign the second highest multiplexing-priority (e.g., multiplexing-priority = 2) for a PDU/PDU- segment having a delay requirement being smaller than #VALUE(1). The WTRU may assign multiplexingpriority = 2n-1 for a PDU/PDU-segment for retransmission having delay requirement being smaller than #VALUE(n). The WTRU may assign the multiplexing-priority = 2n for a PDU/PDU-segment having delay requirement being smaller than #VALUE(n). The WTRU may assign the multiplexing-priority = 2N+1 to the PDU/PDU-segment for retransmission having delay requirement being larger than #VALUE(N). The WTRU may assign a multiplexing-priority = 2N+2 to the PDU/PDU-segment for initial transmission having delay requirement being larger than #VALUE(N). The WTRU may assign the lowest multiplexing-priority (i.e., multiplexing-priority = 2N+3) for a best-effort PDUs/PDU-segments.

[0170] The WTRU may perform prioritization among a RLC PDU/PDU-segment to multiplex (e.g., in a MAC PDU) based on the multiplexing-priority associated with each RLC PDU/PDU-segment. The WTRU may be configured with an N delay threshold (e.g., #VALUE(1), ..., #VALUE(n), ..., #VALUE(N)), in which #VALUE(1) < #VALUE(n) < #VALUE(N). The WTRU may refrain from differentiating (e.g., not differentiate) between initial transmission and retransmission PDU/PDU-segment. The WTRU may prioritize the PDU/PDU-segment with a lower SN, for example, if multiple PDUs/PDU-segments have the same multiplexing-priority. For example, the WTRU may be configured with an N+1 multiplexing-priority from 1 to N+2, in which the lowest multiplexing-priority value (e.g., 1) may be associated with the highest multiplexing-priority. The WTRU may assign the highest multiplexing-priority (e.g., multiplexing-priority = 1) for a PDU/PDU-segment having delay requirement being smaller than #VALUE(1). The WTRU may assign the multiplexing-priority = n for a PDU/PDU-segment having delay requirement being smaller than #VALUE(n). The WTRU may assign the multiplexing-priority = N+1 to the PDU/PDU-segment having delay requirement being larger than #VALUE(N). The WTRU may assign the lowest multiplexing-priority (e.g., multiplexing-priority =N+2) for a best-effort PDUs/PDU-segments.

[0171] The WTRU may determine which RLC PDU/PDU-segment to prioritize for transmission.

[0172] The WTRU may perform Logical Channel Prioritization (LCP) to determine which RLC PDU/PDU-

Segment to prioritize to multiplex in a PDU (e.g., in a MAC PDU). The WTRU may prioritize among RLC PDU/PDU-segments for initial transmission, among RLC PDU/PDU-segments for retransmission, and/or among RLC PDU/PDU-segments for initial transmission and retransmission. The WTRU may determine which RLC PDU/PDU-Segment to prioritize, for example, based on one or any combination of the following: whether out-of-order deliver is configured for the RB/LCH or not; whether a PDU-segment is subject for retransmission; the property of the scheduled grant (e.g., size of the grant, the carrier (e.g., unlicensed vs. licensed), the transmit beam (e.g., beam index, SRI or TCI state), the MCS); the sub-window associated with a (e.g., each) RLC-PDU; the transmission status of a (e.g., each) PDU/PDU-segment, which may be based on the number of retransmission attempts made for the PDU/PDU-segment; the number of PDUs the WTRU has made for a (e.g., each) PDU set associated with a (e.g., each) PDU/PDU-segment subject to prioritization; one or more QoS parameters (e.g., PSDB, remaining PSDB, PSDD, importance) associated with a (e.g., each) RLC PDU/PDU-segment; whether a (e.g., each) PDU/PDU-segment is the best-effort one; etc.

[0173] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on whether out-of- order delivery is configured for the RB/LCH or not. The WTRU may prioritize PDU/PDU-segment retransmission over PDU/PDU-segment initial transmission, for example, if out-of-order delivery is not configured for the RB/LCH. For initial transmission PDUs/PDU-segments, the WTRU may follow insequence delivery of the SN. The WTRU may prioritize the PDU/PDU-segment with the lowest SN. The WTRU may refrain from prioritizing (e.g., not always prioritize) a PDU/PDU-segment for retransmission over PDU/PDU-segment for initial transmission, for example, if out-of-order delivery is configured for the RB/LCH. The WTRU may refrain from prioritizing (e.g., not always prioritize) the PDU/PDU-segment with lowest SN. The WTRU may prioritize the PDU/PDU-segment based on other criteria, for example, such as the QoS requirement of a (e.g., each) PDU/PDU-segment (e.g., latency requirement, importance).

[0174] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on whether a PDU- segment is subject for (e.g., to) retransmission (e.g., based on a determination to retransmit the PDU- segment, for example, based on a condition being satisfied). The WTRU may prioritize the PDU-segment over other PDU, for example, if a PDU-segment is subject for retransmission. This approach may be motivated to avoid delaying in RLC AM reception as the WTRU may trigger an t-assembly duration (e.g., timer) to wait for the PDU-segment.

[0175] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on the property of the scheduled grant (e.g., size of the grant, the carrier (e.g., unlicensed vs. licensed), the transmit beam (e.g., beam index, SRI or TCI state), the MCS). The WTRU may prioritize a PDU/PDU-segment for initial transmission, for example, if the size of the grant is not sufficient for the RLC PDU/PDU-segment retransmission. This approach may be motivated to avoid segmentation or re-segmentation of a PDU/PDU- segment for retransmission. The WTRU may perform prioritization between PDU/PDU-segment for initial and retransmission. The WTRU may determine which PDU/PDU-segment to prioritize, for example, based on the similarity between the scheduled grant and the grant used for initial transmission of the PDU/PDU- segment retransmission. The WTRU may prioritize the PDU/PDU-segment for initial transmission, for example, if the two grants are similar (e.g., same carrier, same size, MCS, same beam). The WTRU may prioritize the PDU/PDU-segment retransmission, for example, (e.g., otherwise) if the two grant can provide diversity gain (e.g., in different carrier, larger grant size, smaller MCS, different beam). This approach may be motivated to provide diversity gain for the PDU/PDU-segment retransmission.

[0176] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on the sub-window associated with each RLC-PDU. The WTRU may be configured with a multiplexing-priority for a (e.g., each) sub-window. The WTRU may prioritize the PDU/PDU-segment associated with the sub-window having highest multiplexing-priority.

[0177] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on the transmission status of each PDU/PDU-segment, for example, which may be based on the number of retransmission attempt made for the PDU/PDU-segment. The WTRU may prioritize the PDU/PDU-segment with a higher number of retransmission attempts, for example, if the number of retransmission attempts is smaller than a configured threshold.

[0178] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on the number of PDUs the WTRU has made for a (e.g., each) PDU set associated with a (e.g., each) PDU/PDU-segment subject to prioritization. The WTRU may prioritize the PDU/PDU-segment associated with the PDU with a higher number of PDUs transmitted. This approach may be motivated to allow the WTRU to successfully transmit a PDU set faster. The WTRU may prioritize the PDU/PDU-segment associated with the PDU with a lower number of PDUs transmitted. This approach may be motivated to allow the WTRU to accelerate the transmission of both PDU sets.

[0179] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on one or more QoS parameters (e.g., PSDB, remaining PSDB, PSDD, Importance) associated with a (e.g., each) RLC PDU/PDU-segment. The WTRU may perform prioritization between (e.g., two) PDU/PDU-segments regardless of whether the PDU/PDU-segment is for an initial transmission or retransmission. For example, the WTRU may prioritize the PDU/PDU-segment with the lower remaining PSDB, PSDB, and/or PSDD. The WTRU may prioritize the PDU/PDU-segment with higher importance value. The WTRU may perform prioritization between (e.g., two) PDU/PDU-segments based on whether each PDU/PDU-segment is the initial transmission or retransmission. The WTRU may prioritize between (e.g., two) PDU/PDU-segments for having the same transmission status (e.g., prioritizing between two PDUs/PDU-segments for initial transmission or prioritizing between two PDUs/PDU-segments for retransmission). The WTRU may prioritize the PDU/PDU-segment with the lower remaining PSDB, PSDB, and/or PSDD. The WTRU may prioritize the PDU/PDU-segment with higher importance value. The WTRU may perform in-sequence delivery of the (e.g., two) PDU/PDU-segments for initial transmission by prioritize the PDU/PDU-segment with lower SN. The WTRU may prioritize between PDU/PDU-segments for initial transmission and PDU/PDU-segments for retransmission. The WTRU may prioritize the PDU/PDU-segment for retransmission, for example, if the QoS (e.g., Importance, the latency requirement such as PSDB, remaining PSDB, PSDD,) of the PDU/PDU-segment satisfies a configured threshold. The WTRU may prioritize the PDU/PDU-segment for retransmission, for example, if the PSDB, remaining PSDB, and/or PSDD of the PDU/PDU-segment is smaller than a configured threshold. The WTRU may prioritize the PDU/PDU-segment for retransmission, for example, if the importance of the PDU/PDU-segment is greater than a configured threshold. The WTRU may prioritize the PDU/PDU-segment retransmission, for example, if the QoS requirement of the PDU/PDU-segment for initial transmission satisfies a threshold. The WTRU may prioritize the PDU/PDU-segment retransmission, for example, if the PSDB, remaining PSDB, and/or PSDD of the PDU/PDU-segment for initial transmission is larger than a configured threshold and/or the importance of the PDU/PDU-segment for initial transmission is smaller than a configured threshold. The WTRU may prioritize the PDU/PDU-segment for initial transmission, for example, if the Importance of the PDU/PDU-segment for initial transmission is greater than a configured threshold and the Importance of the PDU/PDU-segment for retransmission is smaller than a configured threshold. The WTRU may prioritize the PDU/PDU-segment for initial transmission, for example, if the latency requirement (e.g., PSDB, remaining PSDB, and/or PSDD) of the PDU/PDU-segment for initial transmission is smaller than a configured threshold and the latency requirement (e.g., PSDB, remaining PSDB, and/or PSDD) of the PDU/PDU- segment for retransmission is larger than a configured threshold.

[0180] The WTRU may determine which RLC PDU/PDU-Segment to prioritize based on whether a (e.g., each) PDUs/PDU-segments is the best-effort one. A PDU/PDU-segment is the best effort one, for example, if it satisfies one or more of the following: the PDU/PDU-segment may not satisfy the delay requirement (e.g., the PSDD has passed, remaining PSDB is zero, the discardTimer associated with the PDU/PDU- segment has expired); the associated PDU or PDU set in an upper layer (e.g., PDCP) is discarded; the PDU/PDU-segment is associated with the number of retransmissions attempts being greater than a configured threshold; the PDU/PDU-segment associated with the PDU set is successfully received by the network; etc. The WTRU may prioritize the other PDU/PDU-segment, for example, if a (e.g., one) PDU/PDU-segment is the best-effort one. The WTRU may discard the best-effort PDU/PDU-segment.

[0181] A PDU/PDU-segment may be discarded.

[0182] A WTRU may (e.g., determine whether to) discard a PDU/PDU-segment.

[0183] The WTRU may (e.g., determine to) discard a PDU/PDU-segment, for example, based on the condition to treat the PDU/PDU-segment in a best-effort manner. The WTRU may discard the PDU/PDU- segment based on one or more of the following conditions: the PDU/PDU-segment may not satisfy the delay requirement (e.g., the PSDD has passed, remaining PSDB is zero, the discardTimer associated with the PDU/PDU-segment has expired); the associated PDU or PDU set in upper layer (e.g., PDCP) is discarded; the PDU/PDU-segment is associated with a number of retransmissions attempts being greater than a configured threshold; the PDU/PDU-segment associated with the PDU set is successfully received by the network, e.g., following reception of an indication of successful delivery by the network; etc.

[0184] The WTRU may select (e.g., dynamically select) a RLC PDU/PDU-segment for probing transmission to support radio link failure (e.g., RLC AM-based RLF).

[0185] The WTRU may select and/or generate (e.g., dynamically select and/or generate) a RLC PDU (e.g., a data RLC PDU, control RLC PDU, RLC PDU without data) for probing transmission to support RLC AM-based RLF. The WTRU may be configured with an interval to trigger sending a probing RLC PDU. The WTRU may trigger sending the probing RLC PDU, for example, after a (e.g., each) configured interval. The WTRU may indicate (e.g., in the RLC header) that such RLC PDU may play the role as a probing RLC PDU. The WTRU may be configured with a duration (e.g., timer, e.g., probing_retx_timer) to control the frequent of the probing transmission. The WTRU may initiate (e.g., begin tracking) a duration (e.g., a probing_retx_duration, e.g., probing_retx_timer), for example, based on a transmission of a probing RLC PDU. The WTRU may retransmit the probing RLC PDU (e.g., if the WTRU has not received ACK feedback (e.g., in a STATUS report) from the gNB), for example, based on expiry of the timer. The WTRU may inform an upper layer and declare RLF. The WTRU may trigger a re-establishment procedure (e.g., RRC re-establishment procedure) to reconnect to the gNB.

[0186] The WTRU may inform the gNB regarding a discarded PDU/PDU-segment.

[0187] The WTRU may inform the gNB regarding the discarded Data Set (e.g., set of PDUs/PDU- segments, a subset of PDU set, one or more PDU sets). The WTRU may use a header (e.g., RLC Header) in a PDU (e.g., in a RLC PDU) to indicate the information regarding the discarded Data Set. The WTRU may use a control PDU (e.g., RLC Control PDU, DISCARD PDU) to inform the network regarding the discarded Data Set. The WTRU may slide the Transmit window to continue transmit uplink data, for example, based on discarding a Data Set. Based on discarding a Data Set and/or informing the gNB regarding the discarded Data Set, the WTRU may trigger one or more of the following: update (e.g., change the parameter value, reset the parameter value) one or more transmission window parameters; modify (e.g., stop, reset) one or more durations (e.g., timers).

[0188] Based on discarding a Data Set and/or informing the gNB regarding the discarded Data Set, the WTRU may trigger an update (e.g., change the parameter value, reset the parameter value) to one or more transmission window parameters. The one or more transmission window parameters may include one or more of the following: TX_Next_Ack; Tx.Next; Poll-SN; PDU_WITHOUT_POLL and/or

BYTE.WI OUT_POLL; RTX_COUNT; etc. TX_Next_Ack may indicate (e.g., hold) the value of the SN of the next RLC SDU for which positive acknowledgement is to be received. For example, the WTRU may update the value of Tx_Next_Ack to the SN right after the last discarded PDU. Tx_Next may indicate (e.g., hold) the value of the SN to be assigned for the next newly generated AMD PDU. For example, the WTRU may update the value of Tx_Next to the SN right after the last discarded PDU. Poll_SN may indicate (e.g., hold) the highest SN of the PDU with polling enabled. For example, the WTRU may set the Poll_SN based on the last discarded PDU in the Data Set. For example, the WTRU may set the Poll_SN to the SN of the last discarded PDU in the Data Set. PDU_WITHOUT_POLL and/or BYTE_WIOUT_POLL may indicate (e.g., count) the amount of data (e.g., number of Bytes, PDUs) transmitted from the last polling. For example, the WTRU may set the value of PDU_WITHOUT_POLL and/or BYTE_WIOUT_POLL to zero. The WTRU may increase the value of PDU_WITHOUT_POLL and/or BYTE_WIOUT_POLL by the amount of discarded data. RTX_COUNT may indicate (e.g., via a counter) a count associated with the number of retransmissions of an RLC SDU/SDU-segment. The WTRU may stop the RTX_COUNT, for example, if the RLC SDU/SDU-segment is discarded. The WTRU may set the initial value of RTX_COUNT for one or more future RLC SDU/SDU-segment as delta, for example, based on retransmission of a (e.g., each) RLCSDU/SDU-segment being triggered. The value of delta may include a function of the stopped RTX_COUNT. This approach may be motivated to help the WTRU to declare RLF based on RLC AM failure. Otherwise, the WTRU may not be able to declare RLF as the WTRU may always discard a PDU if it is retransmitted as the transmission may not be necessary as the RLC PDU/PDU-segment may already exceed the PSDB.

[0189] Based on discarding a Data Set and/or informing the gNB regarding the discarded Data Set, the WTRU may trigger a modification (e.g., stop, reset) associated with a duration. The modification may be associated with a duration (e.g., T-PollRetransmit duration). The WTRU may set a duration (e.g., via the timer) to retransmit a poll (e.g., T-PollRetransmit). For example, the WTRU may reset T-pollRetransmit. For example, the WTRU may stop the duration (e.g., T-PollRetransmit duration), e.g., via the timer.

[0190] A WTRU may receive information regarding discarded PDUs/PDU-segments.

[0191] The WTRU may receive the information from the network regarding a discarded Data Set (e.g., set of PDUs/PDU-segments, a subset of PDU set, one or more PDU sets). The WTRU may slide the receiving window to receive downlink data. Based on reception indication from gNB of a Discarded Data Set, the WTRU may perform one or more of the following: update (e.g., change the parameter value, reset the parameter value) one or more reception window parameters; modify (e.g., stop, reset) one or more durations (e.g., timers); trigger sending STATUS report to the gNB; modify the content of a STATUS report; etc.

[0192] Based on reception indication from gNB of a Discarded Data Set, the WTRU may perform an update (e.g., change the parameter value, reset the parameter value) to one or more reception window parameters. The reception window parameters may include one or more of the following: RX_Next; RX_Next_Status_Trigger; RX_Highest_Status; RX_Next_highest; etc. RX_Next may indicate (e.g., hold) the value of the SN following the last in-sequence completely received RLC SDU. For example, the WTRU may update the value of Rx_Next to the SN after (e.g., right after) the last discarded PDU. RX_Next_Status_Trigger may indicate (e.g., hold) the value of the SN following the SN of the RLC SDU which triggered PDU reassembly duration (e.g., timer). For example, the WTRU may stop/reset the value of RX_Next_Status_Trigger if the PDU associated with the RX_Next_Status_Trigger is discarded. RX_Highest_Status may indicate (e.g., hold) the highest possible value of the SN which can be indicated by “ACK_SN” if (e.g., when) a STATUS PDU is constructed (e.g., needs to be constructed). For example, the WTRU may update the value of RX_Highest_Status to the highest SN associated with the discarded PDUs of the discarded Data Set. RX_Next_highest may indicate (e.g., hold) the value of the SN following the SN of the RLC SDU with the highest SN among received RLC SDUs. For example, the WTRU may update the value of RX_Next_highest to the SN after (e.g., right after) the latest discarded PDU.

[0193] Based on reception indication from gNB of a Discarded Data Set, the WTRU may perform a modification (e.g., stop, reset) associated with one or more durations. The one or more durations may include a duration (e.g., T-StatusProhibit duration), e.g., via a timer. A T-StatusProhibit duration (e.g., T- StatusProhibit timer) may be used by the transmitting side of an AM RLC entity to retransmit a poll. For example, the WTRU may stop a T-StatusProhibit duration (e.g., timer). For example, the WTRU may reset/restart T-StatusProhibit duration (e.g., timer).

[0194] The WTRU may trigger sending a STATUS report to the gNB, for example, based on reception indication from gNB of a Discarded Data Set. This approach may be motivated to allow the gNB to be aware of the status of the receiving RLC entity after discard operation.

[0195] Based on reception indication from gNB of a Discarded Data Set, the WTRU may perform a modification associated with the content of a STATUS report. The WTRU may keep the ACK_SN field. The WTRU may refrain from reporting (e.g., not report) the status associated with the discarded PDU/PDU- segment. The WTRU may move ACK_SN field to the SN associated with (e.g., right after) the last discarded PDU.

[0196] 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.

[0197] 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.

[0198] 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

CLAIMS What Is Claimed Is:

1 . A wireless transmit/receive unit (WTRU) comprising, a processor configured to: transmit a first protocol data unit (PDU); receive a second PDU; receive at least one of a first reception status or a second reception status, wherein the first reception status is associated with the first PDU, and wherein the second reception status is associated with the second PDU; determine a transmission priority associated with a retransmission of the first PDU and a transmission of the second PDU, wherein the transmission priority is determined based at least on a first quality of service (QoS) associated with the first PDU, a second QoS associated with the second PDU, and at least one of the first reception status or the second reception status; and send a transmission based on the transmission priority, wherein the transmission comprises the first PDU or the second PDU.

2. The WTRU of claim 1 , wherein the transmission priority indicates that the first PDU has a higher priority than the second PDU, wherein the transmission comprises the retransmission of the first PDU.

3. The WTRU of claim 2, wherein the transmission is a first transmission, and wherein the processor is further configured to: send a second transmission, wherein the second transmission comprises the second PDU, wherein the second transmission is sent after the first transmission, wherein the first transmission does not include the second PDU.

4. The WTRU of claim 1 , wherein the transmission priority indicates that the second PDU has a higher priority than the first PDU, wherein the transmission is a first transmission, wherein the first transmission comprises the second PDU, and wherein the processor is further configured to: send a second transmission, wherein the second transmission comprises the retransmission of the first PDU, wherein the second transmission is sent after the first transmission, and wherein the first transmission does not include the retransmission of the first PDU.

5. The WTRU of claim 1 , wherein the transmission priority indicates that the second PDU has a higher priority than the first PDU, wherein the transmission comprises the second PDU, and wherein the processor is further configured to: determine to discard the first PDU; and based on the determination to discard the first PDU, discard the first PDU.

6. The WTRU of claim 1 , wherein the first PDU is associated with a first arrival time, wherein the second PDU is associated with a second arrival time, wherein the first arrival time is before the second arrival time, and wherein the transmission comprises the second PDU.

7. The WTRU of claim 1 , wherein the processor is further configured to: receive, from a network, a radio link control status report, wherein the radio link control status report indicates the at least one of the first reception status or the second reception status.

8. The WTRU of claim 1 , wherein the first QoS associated with the first PDU is a first PDU importance, wherein the second QoS associated with the second PDU is a second PDU importance.

9. The WTRU of claim 1 , wherein the processor is further configured to: determine to retransmit the first PDU based on at least one of a received negative acknowledgment (NACK) report associated with the first PDU or based on an estimated reception successful value associated with the first PDU being lower than a threshold.

10. The WTRU of claim 1 , wherein the first PDU is associated with a first sequence number and the second PDU is associated with a second sequence number, and wherein the transmission priority is further based on the first sequence number and the second sequence number.

11. A method comprising, transmitting a first protocol data unit (PDU); receiving a second PDU; receiving at least one of a first reception status or a second reception status, wherein the first reception status is associated with the first PDU, and wherein the second reception status is associated with the second PDU; determining a transmission priority associated with a retransmission of the first PDU and a transmission of the second PDU, wherein the transmission priority is determined based at least on a first quality of service (QoS) associated with the first PDU, a second QoS associated with the second PDU, and at least one of the first reception status or the second reception status; and sending a transmission based on the transmission priority, wherein the transmission comprises the first PDU or the second PDU.

12. The method of claim 11 , wherein the transmission priority indicates that the first PDU has a higher priority than the second PDU, wherein the transmission comprises the retransmission of the first PDU.

13. The method of claim 12, wherein the transmission is a first transmission, and wherein the method further comprises: sending a second transmission, wherein the second transmission comprises the second PDU, wherein the second transmission is sent after the first transmission, wherein the first transmission does not include the second PDU.

14. The method of claim 11 , wherein the transmission priority indicates that the second PDU has a higher priority than the first PDU, wherein the transmission is a first transmission, wherein the first transmission comprises the second PDU, and wherein the method further comprises: sending a second transmission, wherein the second transmission comprises the retransmission of the first PDU, wherein the second transmission is sent after the first transmission, and wherein the first transmission does not include the retransmission of the first PDU.

15. The method of claim 11 , wherein the transmission priority indicates that the second PDU has a higher priority than the first PDU, wherein the transmission comprises the second PDU, and wherein the method further comprises: determining to discard the first PDU; and based on the determination to discard the first PDU, discarding the first PDU.

16. The method of claim 11 , wherein the first PDU is associated with a first arrival time, wherein the second PDU is associated with a second arrival time, wherein the first arrival time is before the second arrival time, and wherein the transmission comprises the second PDU.

17. The method of claim 11 , wherein the method further comprises: receiving, from a network, a radio link control status report, wherein the radio link control status report indicates the at least one of the first reception status or the second reception status.

18. The method of claim 11 , wherein the first QoS associated with the first PDU is a first PDU importance, wherein the second QoS associated with the second PDU is a second PDU importance.

19. The method of claim 11 , wherein the method further comprises: determining to retransmit the first PDU based on at least one of a received negative acknowledgment (NACK) report associated with the first PDU or based on an estimated reception successful value associated with the first PDU being lower than a threshold.

20. The method of claim 11 , wherein the first PDU is associated with a first sequence number and the second PDU is associated with a second sequence number, and wherein the transmission priority is further based on the first sequence number and the second sequence number.