Adjustable lower layer trigger mobility handover execution window

Abstract

A wireless transmit / receive unit (WTRU) may receive configuration information. The configuration information may include an indication of a first lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource configuration to be applied when performing handover to a candidate cell of a plurality of candidate cells. The WTRU may receive an indication to perform the handover to the candidate cell of the plurality of candidate cells. The indication may include a first time duration window. The WTRU may determine a second time duration window at least based on the first time duration window and one or more conditions. The second time duration window may be a subset of the first time duration window. The WTRU may send information indicating the second time duration window and / or the one or more conditions used to determine the second time duration window.

Description

ADJUSTABLE LOWER LAYER TRIGGER MOBILITY HANDOVER EXECUTION WINDOWCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to United States Provisional Patent Application No. 63 / 517,254 filed on August 2, 2023, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] Inter-cell beam management may manage one or more beams in a carrier aggregation (e.g., CA) case, but cell change / add may be unsupported.One objective of the work item Further NR Mobility Enhancements may include specifying mechanism(s) and / or procedure(s) of L1 / L2 based inter-cell mobility for mobility latency reduction. Specifying mechanism(s) and / or procedure(s) of L1 / L2 based inter-cell mobility for mobility latency reduction may include one or more of the following: Configuration and / or maintenance for one or more (e.g., multiple) candidate cells for fast application of configurations for candidate cells (e.g., [RAN2, RAN3]); Dynamic switch mechanism among candidate serving cells (e.g., including special cell (SpCell) and / or secondary cell (SCell)) for the potential applicable scenarios based on L1 / L2 signaling (e.g., [RAN2, RAN1]); L1 enhancements for inter-cell beam management, including L1 measurement and reporting, and / or beam indication (e.g., [RAN1, RAN2]); Timing Advance management (e.g., [RAN1 , RAN2]); and / or centralized unit (CU)-distributed unit (DU) interface signaling to support L1 / L2 mobility (e.g., if needed, [RAN3]). RAN2 involvement (e.g., early RAN2 involvement) may be included, for example, with respect to timing advance management, (e.g., including the possibility of further clarifying the interaction of timing advance management and L1 enhancements for inter-cell beam management). Frequency range 2 (FR2) specific enhancements may not be precluded (e.g., if any).

[0003] The procedure of L1 / L2 based inter-cell mobility may be applicable to the following scenarios: Standalone, CA and NR-dual connectivity (DC) case with serving cell change within one configured grant (CG); Intra-DU case and / or intra-CU inter-DU case (e.g., applicable for Standalone and CA: no new RAN interfaces may be expected); both intra-frequency and inter-frequency; both frequency range 1 (FR1) and FR2; source and / or target cells may be synchronized or non-synchronized; and / or inter-CU case may not be included.SUMMARY

[0004] A wireless transmit / receive unit (WTRU) may receive configuration information. The configuration information may include lower-layer triggered mobility (LTM) candidates and / or a first set of handover (HO) window lengths. The WTRU may send a channel state information (CSI) report to a first cell. The WTRU may receive a LTM cell switch medium access control (MAC) control element (CE). The MAC CEL may include an indication of a first window time position and / or an indication of a window length of the configured first set of HO window lengths. The WTRU may perform one or more LTM preparation actions. One or more LTM preparation actions may include theWTRU to stop CSI reporting. The WTRU may determine a second window to trigger LTM. The WTRU may send an indication to a second cell, for example, at a determined cell switch time.

[0005] A WTRU may receive configuration information from a network device via a first cell. The configuration information may include an indication of a first lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource configuration to be applied when performing handover to a candidate cell of a plurality of candidate cells. The WTRU may receive an indication from the network device via the first cell to perform the handover (HO) to the candidate cell of the plurality of candidate cells. The indication may include a first time duration window (e.g., first LTM HO window). The WTRU may determine a second time duration window (e.g., second LTM HO window), for example, at least based on the first time duration window (e.g., first LTM HO window) and / or one or more conditions. The second time duration window (e.g., second LTM HO window) may be a subset of the first time duration window (e.g., first LTM HO window). The first time duration window (e.g., first LTM HO window) may be longer than the second time duration window (e.g., second LTM HO window). The second time duration window (e.g., second LTM HO window) may include a start time, a duration, and / or an end time. The WTRU may send an indication of the second time duration window (e.g., second LTM HO window) and / or an indication of one or more conditions used to determine the second time duration window (e.g., second LTM HO window) to the network. The indication may be received via a medium access control (MAC) control element (CE). A cell switch may occur at the end time of the second time duration window (e.g., second LTM HO window).

[0006] The WTRU may perform the handover in accordance with the radio resource configuration. The WTRU may perform LTM preparation during a start of the first time duration window (e.g., first LTM HO window). Performing LTM preparation during the first LTM HO window may include one or more of the following: switching off channel state information (CSI) reporting; transmitting hybrid automatic repeat request (HARQ) feedback; performing (e.g., early) timing advance (TA) acquisition; and / or performing one or more measurements and / or one or more predictions to determine the second time duration window. The WTRU may send a CSI report. The indication of the first time duration window (e.g., first LTM HO) window may be associated with the CSI report.

[0007] The configuration information may include one or more of WTRU-triggered LTM cell switch conditions for triggering a cell switch within the first time duration window (e.g., first LTM HO window), one or more conditions to be used for determining the second time duration (e.g., second LTM HO window), and / or an indication of an artificial intelligence (Al) model to be used for the determination of the second time duration window (e.g., second LTM HO window). The configuration information may include an indication of a length out of a plurality of predefined lengths that should be used for the first time duration window (e.g., first LTM HO window). Determining the second LTM HO window may include determining a start position and / or a length of the second time duration window (e.g., second LTM HO window).

[0008] Determining the second time duration window (e.g., second LTM HO window) may be based on one or more conditions. The one or more conditions may include one or more of: radio measurement(s), a number of packets in buffer at HO time, throughput, packet delay, packet loss, location, velocity, and / or HARQ data packets sent and not acknowledged.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0010] 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.

[0011] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0012] 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.

[0013] FIG. 2 depicts a system diagram illustrating a measurement model for a wireless transmit / receive unit (WTRU) to measure one or more (e.g., multiple) beams of a cell and measurements thereof.

[0014] FIG. 3 depicts a diagram illustrating an example layer 1 (L1) / layer 2 (L2) trigger mobility (LTM) using carrier aggregation (CA).

[0015] FIG. 4 depicts an example system flow diagram of an example LTM baseline procedure.

[0016] FIG. 5 illustrates an example of the time series prediction for reference signal received power (RSRP).

[0017] FIG. 6 depicts a flow chart illustrating an example of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure.

[0018] FIG. 7 depicts a process flow illustrating an example of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure.

[0019] FIG. 8 depicts a flow chart illustrating an example fallback case of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure.

[0020] FIG. 9 depicts a process flow chart illustrating an example fallback case of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure.

[0021] FIG. 10 depicts a diagram illustrating an example scenario of selecting one or more (e.g., multiple) target configurations.

[0022] FIG. 11 depicts a flow chart diagram illustrating an example scenario of selecting one or more (e.g., multiple) target configurations.

[0023] FIG. 12 depicts a process flow chart illustrating an example scenario of selecting one or more (e.g., multiple) target configurations.DETAILED DESCRIPTION

[0024] 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 uniqueword DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0025] 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 "STA", may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g. , a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0026] 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.

[0027] 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), relaynodes, 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.

[0028] 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).

[0029] 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).

[0030] 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).

[0031] 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).

[0032] 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).

[0033] 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.

[0034] 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 ON 106 / 115.

[0035] 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.

[0036] 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.

[0037] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multimode capabilities (e.g, the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicatingwith 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.

[0038] 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.

[0039] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0040] 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.

[0041] 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 Ml MO 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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] 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 location-determination method while remaining consistent with an embodiment.

[0046] 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.

[0047] 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., forreception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0048] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0049] 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.

[0050] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0051] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The ON 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.

[0056] Although the WTRU is described in FIGS. 1A-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.

[0057] In representative embodiments, the other network 112 may be a WLAN.

[0058] 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 802.11z 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.

[0059] 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 primarychannel 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.

[0060] 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.

[0061] 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).

[0062] 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 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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).

[0067] 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).

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0073] 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.

[0074] 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.

[0075] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0076] 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.

[0077] 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.

[0078] In RRC_CONNECTED, for example, the WTRU may measure one or more (e.g., multiple) beams (e.g., at least one) of a cell and / or the one or more measurements results (e.g., power values) may be averaged to derive the cell quality. In doing so, the WTRU may be configured to consider a subset of the detected beams. Filtering may take place at one or more (e.g., two) different levels: at the physical layer to derive beam quality and / or (e.g., then) atradio resource control (RRC) level to derive cell quality from one or more (e.g. , multiple) beams. Cell quality from beam measurements may be derived in the same way for the serving cell(s) and / or for the non-serving cell(s). One or more measurement reports may include the measurement result(s) of the X best beams, for example, if the WTRU is configured to do so by the gNB.

[0079] FIG. 2 depicts an example of the corresponding high-level measurement model 200. One or more RRC measurements may be performed in new radio (NR). K beams may correspond to the one or more measurements on SSB and / or CSI-RS resources configured for L3 mobility by gNB and / or detected by the WTRU at layer 1 (L1). A may reference one or more measurements (e.g., beam specific samples) internal to the physical layer. Layer 1 filtering may include internal layer 1 filtering of the one or more inputs measured at point A. Exact filtering may be implementation dependent. How the measurements are (e.g., actually) executed in the physical layer by an implementation (e.g., inputs A and / or Layer 1 filtering) may not be constrained (e.g., by the standard). A1 may include one or more measurements (e.g., beam specific measurements) reported by layer 1 to layer 3 based on (e.g., after) layer 1 filtering. Beam Consolidation / Selection may include beam specific measurements are consolidated to derive cell quality. The behavior of the Beam consolidation / selection may be standardized and / or the configuration of this module may be provided by RRC signaling. Reporting period at B may equal one measurement period at A1. B may include a measurement (e.g., cell quality) determined (e.g., derived) from beam-specific measurements reported to layer 3 after beam consolidation / selection. Layer 3 filtering for cell quality may include filtering performed on the measurements provided at point B. The behavior of the Layer 3 filters may be standardized and / or the configuration of the layer 3 filters is provided by RRC signaling. Filtering reporting period at C may equal one measurement period at B. C may include a measurement based on (e g., after) processing in the layer 3 filter. The reporting rate may be identical to the reporting rate at point B. This measurement is used as input for one or more evaluation of reporting criteria. Evaluation of reporting criteria may determine (e.g., check) whether actual measurement reporting is necessary at point D. The evaluation can be based on more than one flow of measurements at reference point C, e.g., to compare between different measurements. This may be illustrated by input C and C1. The WTRU may evaluate the reporting criteria (e.g., at least every time a new measurement result is reported at point C, C1). The reporting criteria may be standardized and / or the configuration may be provided by RRC signaling (e.g., WTRU measurements). D may include measurement report information (e.g., message) sent on the radio interface. L3 Beam filtering may include filtering performed on the measurements (e.g., beam specific measurements) provided at point A1 . The behavior of the beam filters may be standardized and / or the configuration of the beam filters is provided by RRC signaling. Filtering reporting period at E may equal one measurement period at A1. E may include a measurement (e.g., beam-specific measurement) after processing in the beam filter. The reporting rate may identical to the reporting rate at point A1. This measurement may be used as input for selecting the X measurements to be reported. Beam Selection for beam reporting may include selecting the X measurements from the measurements provided at point E. The behavior of the beam selection may be standardized and / or the configuration of this modulemay be provided by RRC signaling. F may include beam measurement information included in measurement report (e.g., sent) on the radio interface.

[0080] Inter-cell beam management may manage the one or more beams in carrier aggregation (e.g., CA) case, but no cell change / add may be supported.Mechanism(s) and / or procedure(s) of L1 / L2 based inter-cell mobility for mobility latency reduction are described herein. Specifying mechanism(s) and / or procedure(s) of L1 / L2 based inter-cell mobility for mobility latency reduction may include one or more of the following: Configuration and / or maintenance for one or more (e.g., multiple) candidate cells for fast application of configurations for candidate cells (e g., [RAN2, RAN3]); Dynamic switch mechanism among candidate serving cells (e.g., including special cell (SpCell) and / or secondary cell (SCell)) for the potential applicable scenarios based on L1 / L2 signaling (e.g., [RAN2, RAN1]); L1 enhancements for inter-cell beam management, including L1 measurement and reporting, and / or beam indication (e.g., [RAN1 , RAN2]); Timing Advance management (e.g., [RAN1 , RAN2]); and / or centralized unit (CU)-distributed unit (DU) interface signaling to support L1 / L2 mobility (e.g., if needed, [RAN3]). RAN2 involvement (e.g., early RAN2 involvement) may be included, for example, with respect to timing advance management, (e.g., including the possibility of further clarifying the interaction of timing advance management and L1 enhancements for inter-cell beam management). Frequency range 2 (FR2) specific enhancements may not be precluded (e.g., if any).

[0081] The procedure of L1 / L2 based inter-cell mobility may be applicable to the following scenarios: Standalone, CA and NR-dual connectivity (DC) case with serving cell change within one configured grant (CG); Intra-DU case and / or intra-CU inter-DU case (e.g., applicable for Standalone and CA: no new RAN interfaces may be expected); both intra-frequency and inter-frequency; both frequency range 1 (FR1) and FR2; source and / or target cells may be synchronized or non-synchronized; and / or inter-CU case may not be included.

[0082] L1 / L2 based mobility may include inter-cell beam management that addresses intra-DU and / or intra- frequency scenarios. In this case the serving cell remains unchanged (e.g., there is no possibility to change the serving cell using L1 / 2 based mobility). In FR2 deployments, CA may be used to exploit the available bandwidth, e.g. to aggregate multiple component carriers (CCs) in one band. These CCs may be transmitted with the same analog beam pair (e.g., gNB beam and WTRU beam). The WTRU may be configured with transmission configuration indicator (TCI) states (e.g., can have fairly large number, e.g. 64) for reception of physical downlink control channel (PDCCH) and / or physical downlink shared channel (PDSCH). Each TCI state may include a reference signal (RS) and / or synchronization signal block (SSB) that the WTRU refers to for setting its beam. The SSB can be associated with a non-serving PCI. Medium access control (MAC) signaling (e.g., TCI state indication for WTRU-specific PDCCH MAC control element (CE)) activates the TCI state for a Coreset / PDCCH. Reception of PDCCH from a non-serving cell is supported by MAC CE indicating a TCI state associated to non-serving PCI MAC signaling (e.g., TCI States Activation / Deacti vation for WTRU-specific PDSCH) may activate a subset of (e.g., up to) 8 TCI states for PDSCH reception. Downlink control information (DCI) may indicate which of the 8 TCI states. Embodiments are describedherein for supporting unified TCI state with a different updating mechanism (e.g. , DCI-based), with or without multi- TRP.

[0083] An objective of LTM may be to improve handover latency. With a L3 handover and / or on a conditional handover (CHO), the WTRU may first send a measurement report using RRC signaling. In response to the measurement report, the network may send (e.g., provide, configure) a further measurement configuration and / or a conditional handover configuration. With a conventional handover, the network may send (e.g., provide) a configuration for a target cell after the WTRU reports using RRC signaling that the cell meets a configured radio quality criteria. With conditional handover, in order to reduce the handover failure rate due to the delay in sending a measurement report then receiving an RRC reconfiguration, the network may send (e.g., provide), in advance, a target cell configuration as well as a measurement criteria which determines when the WTRU may trigger the CHO configuration. Both of these L3 methods, however, may suffer from some amount of delay due to the sending of measurement reports and / or receiving of target configurations (e.g., particularly in case of the conventional (nonconditional) handover).

[0084] An aim of LTM may include a fast application of configurations for candidate cells, including dynamically switching between SCells and switching of the primary cell (PCell) (e.g. switch the roles between SCell and PCell) without performing RRC signaling. The inter-CU case may not be included, as this may include relocation of the packet data convergence protocol (PDCP) anchor and / or may have already been excluded from the work item. An RRC based approach may be included at least to support inter-CU handover.

[0085] With the legacy L3 handover mechanisms, for example, one or more (e.g., any) currently active SCell(s) may be released before the WTRU completes the handover to a target cell in the coverage area of another (e.g., new) site, and / or can (e.g., only) be added back after successful handover, which may lead to throughput degradation during handover. One of the aims of L1 / 2 may include enabling CA operation to be enabled instantaneously upon serving cell change.

[0086] FIG. 3 shows an example of LTM operation 300. The candidate cell group may be configured by RRC and / or a dynamic switch of PCell and SCell may be achieved using L1 / 2 signaling. For example, RRC may initially configure cells 1-4 as candidates and / or may activate PCelU and / or SCell2 Dynamic SCell switch between Cell2 and Cell3 may occur (e.g., cell3 may become the SCell while Celli remains the primary cell). Dynamic switch of PCell may occur (e.g., PCell may switch from cell 1 to cell 2) and / or the SCell may switch to Cell4).

[0087] FIG. 4 depicts an example system flow diagram 400 of an example LTM baseline procedure. At 425, a WTRU 402 may perform a first portion (e.g., LTM preparation) of the LTM baseline procedure. At 450, the WTRU 402 may perform a second portion (e.g., early synchronization) of the LTM baseline procedure. At 475, the WTRU 402 may perform a third portion of the LTM baseline procedure. At 495, the WTRU 402 may perform a fourth portion of the LTM baseline procedure.

[0088] At 425, a WTRU may perform a first portion (e.g. , LTM preparation) of a LTM baseline procedure. For example, the WTRU may perform LTM preparation during a first time duration window (e.g., first LTM HO window). At 406, a WTRU 402 may be in RRC_Connected mode. At 408, the WTRU 402 may send a MeasurementReport message to the gNB 404. At 410, the gNB 404 may perform LTM candidate preparation. For example, the gNB 404 may determine (e.g., decide) to use LTM and / or may initiate LTM candidate preparation. At 412, the gNB 404 may transmit an RRCReconfiguration message to the WTRU. The RRC reconfiguration message 412 may include LTM candidate configuration (e.g., as described herein). For example, the RRCReconfiguration message may include the configuration of one or more (e g., multiple) LTM candidate target cells For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a first lower-layer triggered mobility (LTM) HO window from a network. At 414, the WTRU 402 may store the configuration of LTM candidate target cell (s) and / or may transmit a RRCReconfigurationComplete message to the gNB 404.

[0089] At 450, the WTRU 402 may perform a second portion (e.g., early synchronization) of the LTM baseline procedure. At 416a, the WTRU 402 may perform downlink (DL) synchronization and timing advance (TA) acquisition with candidate target cell(s) before receiving the LTM cell switch command. For example, the LTM cell switch command may be received via a MAC CE. DL synchronization may be supported for candidate cell(s) before cell switch command, at least based on SSB. TA acquisition of candidate cell(s) before LTM cell switch command may be supported, at least based on PDCCH ordered random access channel (RACH), where the PDCCH order is triggered by source cell. At 416b, the WTRU 402 may perform early uplink (UL) synchronization with one or more candidate cells (e.g., send a RACH preamble to the candidate cells, using which the network may determine the UL timing advance (TA) required for the WTRU to communicate with the candidate, if the candidate is later chosen to be the target cell at step 420).

[0090] At 418, the WTRU 402 may perform L1 measurements on the configured LTM candidate target cell(s), and / or may transmit lower-layer (e.g., L1) measurement report(s) to the gNB 404. The lower-layer measurement report(s) may be carried on L1 and / or MAC.

[0091] At 420, the gNB 404 may determine (e.g., decide) to execute LTM cell switch to a target cell.

[0092] At 422, the gNB 404 may transmit a cell switch command. For example, the gNB 404 may transmit a MAC CE triggering LTM cell switch by including the candidate configuration index of the target cell.

[0093] At 424, the WTRU 402 may switch to the configuration of the LTM candidate target cell. For example, the WTRU 402 may detach from a source cell and / or apply the target cell configuration(s) (e.g., received at 422).

[0094] At 426, the WTRU 402 may perform random access procedure towards the target cell, for example, if TA is not available. At 428, the WTRU 402 may indicate successful completion of the LTM cell switch towards target cell.

[0095] Artificial intelligence (Al) may include an ability for a machine to perceive, synthesize, and / or infer information. Such behavior may e.g., mimic cognitive functions to sense, reason, adapt, and / or act.

[0096] Machine learning (ML) may refer to type of algorithms that discern patterns and / or infer solutions to problems based on learning through experience (e.g. , data), for example, without explicitly being programmed (e.g. , configuring set of rules). Machine learning can be considered as a subset of Al. Different machine learning paradigms may be envisioned based in the nature of data and / or feedback available to the learning algorithm(s). For example, a supervised learning approach may involve learning a function that maps input to an output based on labeled training example, where each training example may be a pair including an input and the corresponding output. For example, unsupervised learning approach may involve detecting patterns in the data with no pre-existing labels. For example, reinforcement learning approach may involve performing sequence of actions in an environment in order to maximize the cumulative reward. Examples may include applying machine learning algorithms using a combination and / or interpolation of the approaches mentioned herein. For example, semi-supervised learning approach may use a combination of a small amount of labeled data with a large amount of unlabeled data during training. In this regard, semi-supervised learning may fall between unsupervised learning (e.g., with no labeled training data) and supervised learning (e.g., with only labeled training data).

[0097] Deep learning may refer to a class of machine learning algorithms that employ artificial neural networks (e.g., specifically deep neural networks (DNNs)) which may have been loosely inspired from biological systems. The Deep Neural Networks (DNNs) may be a special class of machine learning models inspired by the human brain, where the input is linearly transformed and / or passes through non-linear activation function one or more (e.g., multiple) times. DNNs may include multiple layers where each layer includes linear transformation and / or one or more given non-linear activation functions. The DNNs can be trained using the training data via back-propagation algorithm. DNNs may include state-of-the-art performance in a variety of domains (e.g , speech, vision, natural language etc.), and / or for various machine learning settings (e.g., supervised, un-supervised, and / or semisupervised).

[0098] Auto-encoders may be a specific class of DNNs that arise in context of un-supervised machine learning setting where the high-dimensional data is non-linearly transformed to a lower dimensional latent vector using the DNN based encoder and the lower dimensional latent vector is (e.g., then) used to re-produce the high-dimensional data using a non-linear decoder. The encoder may be represented as E(x We~), where x is the high-dimensional data and Werepresents the parameters of the encoder. The decoder may be represented as D(z,- Wd), where z is the low-dimensional latent representation and Wdrepresents the parameters of the encoder. Further, using training data { x , • •• , xN] the auto-encoder can be trained by solving the following optimization problem {Wetr, Wdr} = arg min Ef 11 xt- D(E(X We); Wd) 1 . The problem can be approximately solved using backpropagation algorithm. The trained encoder E(x; Wetr) can be used to compress the high-dimensional data and / or trained decoder D(z Wdr) can be used to decompress the latent representation.

[0099] The terms Artificial Intelligence (Al), Machine Learning (ML), Deep Learning (DL), and DNNs may be used interchangeably. Methods described herein may be exemplified based on learning in wireless communication systems. The methods may not be limited to such scenarios, systems, and / or services; the methods may be applicable to one or more (e.g., any) type of transmissions and / or services etc.

[0100] Recurrent neural network (RNNs) are algorithms that may be specifically effective in modeling sequential data. RNNs may include internal memory that enables the model to remember previous inputs, as well as current inputs to help sequence modelling. The output for any step within the neural network may be based on the current input and / or the output generated at one or more previous steps RNNs may exemplify how a neural network can track evolving conditions for a given task either e.g., in terms of tracking the impact of the changes in channel I radio, change in latency, bitrate, jitter e.g., for the purpose of determination how to apply quality of service (QoS_ treatment on a per packet basis for a given flow, and / or the like.

[0101] In examples, the term rule-based processing may refer to specified WTRU behavior and / or requirements (e.g., explicitly) outlined (e.g., defined) in the form of procedural text, signaling syntax, and / or the likes. Rule-based processing may refer to any processing based on one or more (e.g., legacy) algorithms that may be (e.g., essentially) non-AI based. For example, logical channel prioritization (LCP) procedure may include (e.g., may be defined as) one or more (e.g., a sequence of) procedural steps. An entity that performs Al processing may be referred to as a rulebased component.

[0102] In examples, the term Al processing may refer to specified WTRU behavior and / or processing and / or parts thereof that are learned based on training using data. Al processing may involve one or more of classical machine learning techniques and / or deep learning techniques. Al processing may apply one or more Al model architectures to perform one or more of: classification, prediction, pattern recognition, dimensionality reduction, estimation, interpolation, clustering, regression, compression, recommendation, approximation of an arbitrary function, and / or the like. Al processing may utilize supervised, unsupervised, reinforcement learning, and / or a combination or a variant thereof. For example, an Al model applying Al processing may be trained by various techniques such as offline training, online training, online refinement, and / or a combination thereof. For example, such training may be performed (e.g., locally) on the WTRU, partially on the WTRU, and / or downloaded from the network. An entity that performs Al processing may be referred to as Al component and / or an Al filter.

[0103] A WTRU may be configured with one or more (e.g., a plurality of) Al models. Each Al model may be associated with a context. For example, a context may refer to a set of conditions under (e.g., and / or during) which the performance of the Al model is expected to be satisfactory. The performance of an Al component may be related to e.g., inference accuracy for the given task of the Al model used by the Al component.

[0104] A contextual Al model may include an Al model that is associated with a specific context. The inference accuracy of a contextual model may be based on (e.g., depend on) the context under which the model is executed. The size, training time, inference latency, complexity, and / or power consumption associated with a contextual Almodel may be (e.g., much) lower than that of an Al model that is expected to perform under one or more (e.g., all) the contexts.

[0105] The L1 / 2 triggered mobility (LTM) procedure being standardised may improve mobility latency, for example, by one or more of the following: preconfiguring multiple target cells prior to handover; using L1 measurement reports for mobility purpose; and / or the use of MAC CE to indicate cell switch.

[0106] The cell switch time may be based on (e.g., primarily dependent on) one or more radio conditions. Reduction of the interruption time, as well as reduction of measurement reporting latency, as provided by the introduction of LTM, may provide more flexibility in terms of the precise time to perform cell switch - there may be less probability of radio link failure (RLE) on source, and / or handover failure (HOF) on target compared to traditional (L3) handover due to the improved latency.

[0107] AI / ML together with LTM may provide an opportunity to (e.g., further) optimise throughput during handover. Throughput may be optimized during handover by exploiting an improved mobility latency and / or reduced failure probability together with predictive models on traffic and / or radio conditions to determine an optimal cell switch time, for example, by using input from both the WTRU and the network.

[0108] The optimal cell switch time may be based on (e.g., depend on) the real time radio conditions (e.g., the precise point at which cell B becomes better than cell A, which may not be possible to determine based on traditional report / execution commands even if using L1 / 2 signalling because of the delay due to transmission of a report of the measurement and / or reception of the trigger for reconfiguration). The optimal cell switch time may (e.g., further) be based on (e.g., depend on) the traffic. For example, it may be beneficial to switch later in order to complete retransmissions of larger protocol data units (PDUs) on the source before switching, and / or switch earlier before initiating an initial PDU transmission.

[0109] LTM may be based on (e.g., relies on) frequent L1 reporting to achieve optimal cell switch time, resulting in excessive resource (e.g. physical uplink control channel (PUCCH)) overhead and / or WTRU measurement processing.

[0110] Systems, methods, and / or apparatuses provided herein may be with respect to how to enable dynamic control of the optimal cell switch time so the WTRU may perform a cell switch time decision for optimal trade-off between the throughput, latency / robustness, and measurement reporting overhead.

[0111] Systems, methods, and / or apparatuses may be provided herein with respect to adjustable LTM handover (HO) execution window.

[0112] Initial HO execution time window selection may be performed at the gNB side and / or indicated to the WTRU in the MAC CE triggering LTM cell switch using, e.g., an index to a preconfigured window position and / or length. This may be based on, e.g., reported and / or predicted radio conditions in cells A (e.g., source cell), B (e.g., target cell) - the network may determine and / or indicate (e.g., suitable) limits to minimize HO failure and / or RLF and / or avoiding too long wait (e.g. long resource reservation in the target cell).

[0113] The WTRU may determine the precise cell switch time within the configured window taking into account, e.g., the real-time / instantaneous radio condition measurements, predicted measurements, and / or service / traffic prediction - the WTRU may select the optimal time to execute LTM in order to maximize throughput based on predicted throughput at cell A and / or cell B during the configured window. The WTRU may (e.g., further) determine a more precise window within the network (NW) configured window during which the cell switch would be most optimal (e.g. throughput and / or failure probability within a certain tolerance limit which is better than the NW configured window provides), and / or may report to the NW to assist with Al model training.

[0114] A WTRU may receive a configuration of LTM candidate cells, and / or a configuration of allowed first handover window lengths. Configuration of LTM candidate cells, and / or a configuration of allowed first handover window lengths may include an explicit list of length values, and / or enable one of multiple predefined tables. Window sizes may correspond, e.g., to cell size / coverage / time in cell / velocity. Window size may be defined in terms of time, serving, and / or target cell RSRP range, location, etc. Configuration may include WTRU-triggered LTM cell switch conditions / criteria for triggering the cell switch within the first window. Configuration may include conditions to be used for selecting a second window, and / or an indication of the Al model to be used for a particular indicated first or second window length. Configuration may include an indication of a second window. The indication of the second window may include different actions for the WTRU to take during the first and second windows, (e.g., first window for LTM preparation steps, second window for LTM execution).

[0115] The WTRU may transmit channel state information (CSI) reporting.

[0116] The WTRU may receive an indication from a network device from a first cell to perform handover and / or cell switch to a candidate cell of a plurality of candidate cells. The indication may include a first time duration window For example, the WTRU may receive LTM cell switch MAC CE, including indication of a first window time position (e.g. time offset and / or system frame number (SEN)) and / or an indication to one of the multiple predefined lengths). Determination may be at the NW side - may be, e.g., based on the CSI report, and / or a constraint based on NW predicted radio conditions / traffic. Offset may include (e.g., be) pointers to list of preconfigured values, explicit SFN indication, delta from current time, etc.

[0117] The WTRU may perform specific (e.g , first) LTM preparation actions during the first time duration window. For example, the WTRU may perform LTM preparation a during a start of the first time duration window (e.g., first LTM HO window). The WTRU may switch off and / or minimize (e.g. report on fewer beams and / or less frequently) candidate cell CSI reporting during the first window (e.g., the HO execution may be based on WTRU measurement and / or prediction without CSI reporting). Performing the LTM preparation during the first time duration window (e.g., first LTM window) may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window. For example, the WTRU may transmit an acknowledgement before / upon CSI reporting being paused / reduced. The WTRU may perform an early TA acquisition(e.g., random access channel (RACH) to target) during the first window. For example, the WTRU may receive random access response (RAR) including TA from target cell and / or from source. The WTRU may perform measurements and / or predictions to determine the position of the second window. For example, the WTRU determining the second window may include the WTRU determining a start position and / or a length of the second time duration window.

[0118] The WTRU may determine (e.g., may select) the position and / or the length of a second HO window within the first HO window to determine the optimal cell switch time range, and / or the WTRU may select a time within the second window to perform cell switch. For example, the WTRU may determine the second time duration window at least based on the first time duration window and / or one or more conditions (e.g., as described herein). The second time duration window may be a subset of the first time duration window. The second time duration window may include a variable position and / or a second (shorter) length. For example, the second time duration window may be based on more up to date (e.g., than the reported and / or NW determined) radio conditions and / or traffic prediction. For example, the aim of the second window may be to maximize throughput during the HO window. Additionally or alternatively, the second window may be determined (e g., selected) based on explicit NW indication (e.g., NW configures). The WTRU may determine (e.g., select) a different Al measurement prediction model and / or window length selection criteria based on (e.g., depending on) window length. For example, shorter window may use (e.g., only use) radio conditions. For example, a longer window may (e.g., allow) service aspects to be taken into consideration.

[0119] The WTRU may perform other (e.g., second) LTM actions during the second window. For example, the WTRU may monitor for a LTM trigger condition to be met during the second window

[0120] The WTRU may perform cell switch and / or handover at the determined time, and / or may transmit an indication (e.g., to the new cell). For example, the WTRU may perform the cell switch and / or the handover in accordance with the radio resource (re)configuration. The WTRU may report the determined position of the second window, and / or the conditions used to determine (e.g., radio measurements, number of packets in buffer at HO time or throughput, packet delay, packet loss, location, velocity, etc.). For example, the WTRU may send, to the network device, information indicating the second time duration window and / or the one or more conditions used to determine the second time duration window. The WTRU may send an indication (e.g., one more sequence numbers) of Hybrid automatic repeat request (HARQ) and / or radio link control (RLC) data PDUs which have been transmitted but for which the respective acknowledgements have not been received (e.g., sent but not ACKed). The WTRU may indicate a cause of HO time decision.

[0121] Systems, methods, and / or apparatuses are provided herein with respect to fallback and / or report if predicted LTM HO condition is not met.

[0122] The NW may determine a fallback cell based on radio conditions and / or a target cell based on a prediction. The gNB may indicate LTM handover to the target cell ahead of the condition being met, and / or may indicate a fallback condition (e.g. , may be a 3rdcell, or may be the original source cell).

[0123] The WTRU may trigger cell switch to the indicated target cell, for example, if the predicted condition is met during a time window (e.g., as described herein). If the condition is not met, for example, (e.g., then) the WTRU may trigger a fallback. The WTRU may indicate the failure to the fallback cell.

[0124] The WTRU may receive a configuration of LTM candidate cells, and / or a configuration of one or more predefined fallback / failure conditions. Condition(s) may include measured and / or predicted radio quality metric, and / or one or more time window lengths. Condition(s) can be based on whether the WTRU determined window falls within the NW predicted window or not.

[0125] The WTRU may transmit CSI reporting (e.g., measured and / or predicted). For example, the indication of the first time duration window may be associated with the CSI report.

[0126] The WTRU may receive LTM cell switch MAC CE, including indication of one or more target cell(s), indication of the trigger condition(s), and / or indication of a fallback behavior. The fallback behavior may be an alternative target cell to trigger LTM towards, and / or may be a fallback to source cell + send a measurement report. Trigger conditions, target cells, and / or fallback cells may be preconfigured (e.g., the NW may preconfigure the WTRU). Associations between (e.g., among) target / fallback / conditions may be partially and / or fully preconfigured and / or dynamically indicated in MAC CE.

[0127] The WTRU may perform LTM preparation actions (e.g. the WTRU may switch off CSI reporting and / or perform early TA acquisition during the window). For example, the WTRU may perform LTM preparation during the first time duration window. Performing the LTM preparation during the first LTM window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0128] The WTRU may determine that the fallback / failure condition is met. For example, the WTRU may determine if the measured radio condition criteria is not met and / or if the TA was not successfully obtained and / or is no longer valid within the indicated time window for one of the target cells (e.g. measurement does not match the indicated prediction).

[0129] The WTRU may determine an alternative (e.g., to the indicated) window in which the handover is estimated to be completed successfully according to WTRU measurements / predictions and / or may indicate the WTRU determined window(s).

[0130] The WTRU may trigger LTM to the fallback cell and / or may transmit a report of at least the radio conditions measured of the indicated / failed target cell within the time window, window calculation, etc.

[0131] If the fallback cell is the original cell, for example, the WTRU may revert LTM preparation actions (e.g. the WTRU may resume CSI reporting).

[0132] Embodiments are described herein for different target configuration (e.g., activated Scells) windows based on (e.g., depending on) the WTRU selection (e.g., determination) within the main window (e.g., the PCell switch time). The WTRU may be provided with (e.g., the NW may configure) one or more (e.g., multiple) target configurations (e.g. which Scells may be activated) determined (e.g., selected) based on (e.g., depending on) the precise WTRU conditions triggering SpCell change, such that the most optimal one is enabled.

[0133] The WTRU may receive a configuration of LTM candidate cells, a first SpCell change condition, and / or a configuration of one or more (e.g., multiple) target (e.g. active SCell) configurations, each of which may be associated with a second condition (e.g. time window and / or RSRP range) to be applied based on (e.g., depending on) when the first SpCell change condition is met. For example, a different set of Scells may be activated (e.g., one or more different configurations) based on (e.g., depending on) the time (2ndcondition) that the SpCell switch criteria (1stcondition) is met. For example, the SpCell cell switch decision may be based on the current SpCell going below a threshold, while the set of activated SCells may be based on (e.g., depend on) one or more of the target cells (e.g. if target SpCell is within range 1 then activate SCell 1, if within range 2 then activated SCell 2). For example, the WTRU may be provided with an SpCell change window. Based on (e.g., depending on) the actual cell switch decision time (e.g., based on prediction as systems, methods, and / or apparatuses provided herein), (e.g., then) the WTRU may activate one or more different sets of SCells.

[0134] The WTRU may transmit CSI reporting. For example, a WTRU may send a CSI report. The indication of the first time duration window may be associated with the CSI report.

[0135] The WTRU may receive cell switch command, including indication of the PCell switch time window.

[0136] The WTRU may determine the optimal PCell switch time within the indicated window. The WTRU may consider in the AI / ML model evaluation the optimal SCell(s) and / or determine (e.g., select) a HO trigger time (e.g., also) based on SCell.

[0137] Based on (e.g., depending on) the determined (e.g., selected) PCell switch time (e.g., and / or other condition), for example, the WTRU may determine (e g., select) the corresponding target configuration. For example, if the PCell switch is executed in a first time duration within the window, (e.g., then) a first set of Scells may be activated; otherwise, for example, a second set (e.g., of Scells) may be activated.

[0138] The WTRU may perform cell switch at the determined time, and / or may transmit an indication to the other (e.g., new) cell of the selected configuration.

[0139] Perform LTM and / or perform LTM procedures may refer to performing one or more (e.g., any, each) of the procedures described herein (e.g , in FIG. 4). Specifically, early synchronization in downlink (DL) and / or uplink (UL) to one or more of the candidate cells, performing L1 measurements and / or reporting on one or more of the candidatecells, switching (e.g., performing handover) between candidate cells (e.g., Perform LTM may include the WTRU moves / switches between multiple candidate cells during the procedure).

[0140] The one or more candidate cell sets may be groups of more than one RRC configuration corresponding to a handover configuration for one or more candidate SpCells and / or SCells. This may be modelled and / or received as one or more complete RRC Reconfiguration messages, one or more cell group configurations, and / or one or more cell configurations. Each of the candidate cell configurations may include a candidate configuration identifier, and / or each of the candidate cell groups may include a candidate cell group identifier. If the grouping is performed at RRC, for example, the switching between different sets of candidate cells may include updating the serving cell indexes and / or candidate configuration indexes which are used in L1 and / or MAC signaling to refer to specific indexes (e.g., a MAC CE triggering the reconfiguration may include a candidate configuration index informing the WTRU which cell to perform the reconfiguration to).

[0141] The one or more candidate cell groups may be configured as a single list and / or group of candidate cell configurations at RRC. The grouping may occur at the early sync and / or LTM execution phase (e.g., rather than the configuration phase). The candidate cell set may be considered as a single group in terms of an RRC configuration list and / or group, while the cells selected for performing early sync, L1 measurements, and / or LTM execution may be based on (e.g., depend on) a further grouping into one or more (e.g., multiple) subsets of the overall candidate cell list. The grouping itself may not be modelled at RRC using candidate configuration identifiers; the grouping may be executed as part of the early sync and / or the LTM execution procedure.

[0142] An LTM candidate configuration may apply to one or more (e.g., any) types of preconfigured cell information For example, a WTRU may be configured with one or more conditional reconfigurations, such as conditional handover (CHO), conditional PSCell addition (CPA), and / or conditional PSCell change (CPC), which are valid before and / or after a cell change, and / or valid in certain cells.

[0143] An L1 measurement herein may include a measurement of reference signal received power (RSRP), RSRQ, received signal strength indicator (RSSI), etc., performed by a WTRU of a cell, beam, set of cells, and / or set of beams. Such L1 measurement(s) may be similar to layer 3 (L3) measurement(s) reported in radio resource management (RRM), with differences in the filtering, reference signals measured, reporting mechanisms, etc.

[0144] Herein, measurements may refer to L1 measurements for LTM. Methods, systems, and / or apparatuses herein may apply also to RRM / L3 measurements, as well as other measurements (e.g., measurements of speed, location, height, traffic, etc.).

[0145] The WTRU experienced conditions may come from one or more real measurements the WTRU performs over time. In an example (e.g., simple) mobility scenario, a WTRU in mobility may read that the current serving cell’s RSRP and / or may report the current serving cell’s RSRP to the NW. If the WTRU is moving to an area approaching the serving cell's edge, for example, the WTRU may record that RSRP values are decreasing. RSRP values may be communicated to the NW via measurement reports for the NW to make a determination (e.g., decision).

[0146] The NW may have a pre-trained AI / ML model that is able to produce predictions of air-interface measurements (RSRP, RSRQ, signal to interference noise ratio (SI NR), etc.) of serving and / or neighbor cells (e.g., any cell). The predictions may determine (e.g., anticipate) the radio conditions the WTRU may experience (e.g., instead of waiting for the WTRU to report).

[0147] In order to produce more (e.g., meaningful) predictions in this context, the NW may predict one or more measurements (e.g., RSRP) in a time series manner. This may include that from the moment the NW predictions are triggered, for example, the WTRU may produce one or more (e.g., several) prediction outputs over a future time span, with a certain granularity and / or time step.

[0148] FIG. 5 illustrates an example of the time series prediction for RSRP as an example. Past and / or current RSRP, and / or one or more other (e.g., relevant) inputs may be included as inputs into the Al and / or ML model. The NW (e.g., via ML) may predict RSRP at time t (e.g., 502, 504). The NW may predict one RSRP prediction point per time step from time t+1 until t+t_fb (e.g., at 506). The variable fb may represent the end of a time horizon for the prediction(s). Another variable n may be used to represent a prediction window when predictions are output as a time series, such that when a prediction is triggered at time t the window would last n(fb) and the total window time may be t+n. Each RSRP prediction may correspond to a respective error. For example, the NW may predict RSRP at t+1 ; error 1 . The ML may predict RSRP at t+2; error2. The ML may predict RSRP at t+t_fb; errortjb.

[0149] Predictions can also be done for one point in time (e.g., only), and / or can extend over several time steps. In examples, prediction with time series output may be (e.g., more) beneficial than single value predictions as it may be difficult to match the prediction with, e.g., a NW configured event with a single prediction point.

[0150] This may lead to a practical issue, that is the granularity of the timestamp associated with a prediction. If the WTRU and / or the NW predict one or more future values, for example, a timestamp may (e.g., in principle) be associated with that prediction (e.g., a timestamp for t+1 , t+2, etc.). The granularity of that timestamp may be based on (e.g., depend on) the AI / ML model in use and / or one or more other ML related settings. Terminology like predicted value, inferred value, future value and / or others may be used to refer to future predicted values that may have an associated timestamp. If future predicted values do have an associated timestamp, for example, the timestamp can be considered a small delta time interval within which the predicted value may be considered to be accurate and / or valid (e.g., either completely or with a certain degree of confidence). In one or more (e.g., all) WTRU-NW exchanges, predictions may be represented by a tuple such as ["predicted value”; timestamp - delta; timestamp + delta],

[0151] NW and / or WTRU predictions may be performed in response to one or more triggers. For example, a WTRU may be configured to predict future measurements based on current and / or historical measurements. For example, the WTRU may be configured with a trained AI / ML model that is able to produce predictions for radio interface radio signal levels. In examples, the AI / ML model at the WTRU may be implementation based. In examples, the WTRU may obtain the AI / ML model from the NW. In examples, the AI / ML model may be configured to take as an input current and / or historical RSRP measurements. In examples, the AI / ML model may be configured to takeadditional inputs such as WTRU location information, WTRU mobility etc. In examples, the AI / ML model may be configured to produce single value predictions (e.g. , RSRP at a future time instant t). In examples, the AI / ML model may be configured to predict a series of RSRP values corresponding to future time instances (e.g., t+1 , t+2 so on up to t+t_fb).

[0152] A model may be offline trained, and / or online trained, and / or may be exchanged in a pre-configuration step.

[0153] Systems, methods, and apparatuses proposed herein may provide the opportunity for the network to provide a range (e.g. a window) of one or more criteria (e.g. time, radio quality measurement, position) under which it is expected that a handover can be (e.g , completely) successfully (e.g with minimum probability of handover failure and / or radio link failure); the WTRU may adjust the precise time of handover according to more up to date (e.g. than the NW configuration time) measurements and / or Al predictions in order to maximize performance (e.g. maximize throughput, minimize interruption and / or latency) during a handover execution. Additionally or alternatively, this may provide an opportunity to improve robustness (e.g., by enabling a WTRU triggered handover execution) while limiting the network resource overhead in doing so (e.g. reserving resources on target cells for a limited duration only).Certain embodiments may include a NW Al model to be trained by use of WTRU feedback and / or reporting, and / or to fine-tune the network estimation for future handovers. Certain embodiments may provide fallback mechanisms to support a more aggressive approach to predicted handover events by (e.g., further) improving the robustness of the mechanisms. Certain embodiments may include (e.g., enable) the WTRU enable to determine (e.g., select) the most appropriate handover trigger timing and / or to determine (e.g., select) the most appropriate and / or the most effective configuration (e.g., providing the highest estimated throughput, least errors, smaller failure rates, etc.) to apply upon executing the handover.

[0154] The gNB (e.g. a CU in case of CU / DU split architecture, RRC may reside in CU) may configure (e.g., potential) LTM candidates using RRC signaling. In examples, the WTRU may receive the LTM candidate configurations using an RRC Reconfiguration message, for example, during the LTM preparation phase (e.g., as shown in FIG. 4). The WTRU may store the LTM candidate configurations to (e.g., later) apply based on (e.g., upon) receiving an indication using L1 / 2 signaling (e.g. MAC CE) to perform a cell switch, for example, in the LTM execution phase (e.g., as shown in FIG. 4).

[0155] In examples, the configuration of (e.g., potential) LTM candidates may include candidate sets. For example, a first set which may be suitable for a first path (e.g., a WTRU may turn left and / or may take a first road) and a second set may be suitable for a second path (e.g. the WTRU may turn right and take second road).

[0156] In examples, one or more (e.g., some, and / or all) of the candidate set information may be broadcast in system information. The WTRU may enable the pre-configuration of these broadcast configurations based on (e.g., upon) receiving an indication in dedicated signaling (e.g. RRC Reconfiguration) which may refer to the broadcast of one or more configurations (e.g. using an index or identifier).

[0157] In examples, the configuration may include one or more (e.g., all, or a subset) of the potential cells in a specific area (e.g., all cells belonging to the CU with which the WTRU is currently connected and / or cells within a particular geographical area). These cells may not yet have been detected and / or measured by the WTRU, but are configured in advance. In examples, based on (e.g., after) the initial configuration of LTM candidate configurations, the WTRU may receive an update to the configuration to modify, add, remove, and / or replace one or more (e.g., any) part of the LTM candidate configurations.

[0158] In examples, the WTRU may receive an indication to enable or disable one or more (e.g., some, and / or all) of the LTM configurations. For example, if it is predicted that the WTRU mobility would be better handled using L3 (e.g. RRC measurement report, RRC reconfiguration, conditional reconfiguration) (e.g., then) LTM may be disabled. If it is predicted that LTM would better suit the WTRU mobility, for example, (e.g., then) LTM may be enabled (e.g. a previously configured and / or disabled LTM configuration may be re-enabled).

[0159] The configuration may be based on a prediction model internal to, and / or determined by, the network (e.g. gNB). This prediction may, for example, be based on what it (the NW prediction model) determines to be the WTRU’s most likely paths.

[0160] In examples, the candidate cell configurations may include one or more (e.g., all, and / or part of) the information (e.g., information necessary) necessary to complete a reconfiguration (e.g. handover) to the candidate cell, such as channel configurations (e.g. physical RACH (PRACH), dedicated physical control channel (DPCCH), dedicated physical shared channel (DPSCH)), control resource set (CORESET), bandwidth part (BWP), security parameters, L2 parameters (E.g. MAC, RLC, PDCP), radio bearer configurations, and so on.

[0161] Embodiments are described for NW model training using WTRU reported information. In examples, the WTRU may report a selected window size, and / or information used for the determination (e.g., selection). For example, the reported information may include one or more of the following. The reported information may include window start time (e.g., SFN and / or subframe) and / or offset (e.g. offset from a configured start time).

[0162] The reported information may include: window length (e.g. number of subframes and / or number of ms) and / or offset (e.g. offset from a configured length). The reported information may include measured and / or predicted CSI information: RSRP (beam and / or cell); RSRQ (beam and / or cell); CSI reference signal resource indicator (CRI)- rank indicator (Rl)-precoding matrix indicator (PMI)-channel quality index (CQI); cri-RI-single wideband indication (i1); cri-RI-i1-CQI; cri-RI-CQI; cri-RSRP; ssb-lndex-RSRP; and / or cri-RI-Layer Indicator (LI)-PMI-CQI.

[0163] The reported information may include a predicted LTM cell switch execution time and / or range of times. The reported information may include an indication of the predicted optimal SCells to be activated upon SpCell switch. The reported information may include one or more beam and / or cell identifiers which are predicted and / or measured. The reported information may include one or more LTM candidate cell and / or cell set identifiers. The reported information may include an index to one of multiple predefined measurement values. The reported information may include an explicit cell quality measurement value. The reported information may include an indication of whether oneor more of the reported values is predicted and / or an actual measurement. The reported information may include an indication of the model used for prediction. The reported information may include an indication of a timescale used for prediction. The reported information may include failure information, such as: cells on which the WTRU detected a beam failure or radio link failure; measurements associated with the failure conditions (e.g., cells meeting a certain configured criteria such as cell quality thresholds, and / or absolute measurements such as RSRP); and / or one or more (e.g., a number) of preamble transmissions and / or retransmissions in case of a failed RACH procedure.

[0164] The reported information may include: location information (e.g., GPS co-ordinates, cell fingerprint, location history, velocity, height, device orientation, etc.).

[0165] The reported information may include throughput (e.g. on source and / or target). The reported information may include packet error rates (e.g. on source and / or target). The reported information may include packet delay (e.g. on source and / or target). The reported information may include a cause value, for example, an indication that the WTRU has determined (e.g., selected) a second window based on one of more of the information types provided herein.

[0166] LTM execution window herein may refer to a range, which is either configured and / or indicated by the network to the WTRU, and / or estimated / determined by the WTRU.

[0167] A range may be based on one or more (e.g., any) of the following. A range may be based on time (e.g. absolute or relative time measured time at WTRU, SFN, and / or Subframe number). A range may be based on radio quality measurement and / or predicted radio quality one or more of the serving cells and / or target cells (e.g., RSRP (beam and / or cell), RSRQ (beam and / or cell), cri-RI-PMI-CQI, cri-RI-11 , cri-RI-i1-CQI, cri-RI-CQI, cri-RSRP, ssb- Index-RSRP, cri-RI-LI-PMI-CQI, etc.). A range may be based on position For example, position may include an area (e.g. defined by reference point and / or radius) and / or range of co-ordinates. Position may include a distance threshold from a reference location. A range may be based on data (e.g., data related). For example, a range may be based on an amount of data to be received in the downlink since the start of the window. For example, a range may be based on an amount of data to be transmitted in the uplink since the start of the window. For example, a range may be based on a total volume of data exchanged with the network. A range may be based on QoS related (e.g., the WTRU may predict some relevant QoS metrics such as packet loss, packet error rate and / or throughput, and / or may set the range of the window based on that. For example, the window may start with one or more (e.g., any) of the options herein and end when the WTRU has predicted throughput will drop under a threshold or end when the WTRU has predicted packet loss / packet error rate will be higher than threshold. A range may be based on multi conditions approaches, e.g., the WTRU may determine the start of the window as soon as it receives relevant signaling from the NW (e.g., as described herein), and / or consider a specific SFN, and / or determine the end of the window based on one or more (e.g., another) conditions that is not time related (e g., predicted radio conditions).

[0168] The window may define the range of conditions under which the WTRU may determine (e.g., select) a specific time to perform an action related to LTM. For example, the WTRU may perform one or more of the following procedures.

[0169] The WTRU may perform early TA acquisition. For example, the WTRU may trigger a RACH to a target LTM cell. The WTRU may receive a TA value in a RAR. The RAR may come from target cell, and / or via source cell. The WTRU may receive a TA value in a MAC CE triggering the cell switch. The WTRU may perform power ramping and / or preamble retransmission on the target if a RAR / MAC CE is not received.

[0170] The WTRU may switch off CSI reporting. A configured and / or determined window may indicate a period of time (e.g., and / or another condition) when the WTRU may (e.g., is allowed to, and / or required to) switch off CSI reporting to reduce reporting overhead in the uplink. The CSI reporting may be reduced rather than switched off. For example, reduced CSI reporting may include reduced number of cells and / or beams reporting, and / or a reduced frequency of reporting. The CSI reporting to be switched off and / or reduced may include the target PCell, other candidate LTM cells, and / or one or more (e.g., all) LTM cells. The UE may resume CSI reporting when the window ends.

[0171] The WTRU may switch on CSI reporting. For example, the WTRU may (e.g., be required to) perform and / or report CSI measurements on one or a subset of LTM candidate cells during the window.

[0172] The WTRU may perform LTM cell switch. A window may include (e.g., define) the range of time and / or conditions under which the WTRU may (e.g., is allowed to) trigger LTM cell switch. The window may define the limits of a range of condition(s), and / or may be associated with one or more additional conditions. For example, the window may include (e.g., define) the time range under which the WTRU can trigger LTM cell switch, if a measured radio quality criteria is met within that time range.

[0173] The WTRU may monitor PDCCH on a target cell. The WTRU may be configured to monitor on a target cell for a DCI scheduling PDSCH and / or indicating one or more actions on the target cell, for example, to initiate the cell switch procedure.

[0174] The WTRU may perform beamforming request (BFR) and / or radio link monitoring (RLM) on a target cell. The WTRU may be configured to monitor beam failure detection (BFD) resources on a target cell, and / or perform RLM on a target cell during the window.

[0175] The WTRU may activate and / or deactivate one or more (e.g., certain) SCells. The WTRU may be configured with one or more specific SCells which should be active or not active during the window.

[0176] After sending the LTM cell switch command, the WTRU / network behavior may be as in legacy HO. That is, serving cell / node may release WTRU resources / context and / or there may be no DL / UL communication with the source cell after the correct reception of the LTM cell switch command. To enable the modified execution time window behavior (e.g., being proposed here), the source cell / node may keep the WTRU resources / context at least until the maximum configured cell switch time / window, so that the communication between the source cell / node andWTRU can be maintained. In examples, systems, methods, and apparatuses provided herein may include LTM conditional cell where the source cell / WTRU can maintain the connection with the source while the conditions for actually executing the LTM cell switch are being monitored.

[0177] Examples are provided herein for LTM execution triggers. In examples, the WTRU may be provided with a specific trigger for performing the one or more procedures. These specific triggers may be provided in addition to a configured and / or determined window using a range. For example, the WTRU may execute an LTM cell switch, trigger an early TA acquisition (e.g. send a random access preamble to the target cell), and / or may perform reduced CSI reporting as long as it is within the range defined by the window and additionally meets one or more of the following criteria (e.g., which may be based on one or more measurements and / or predictions): one or more L3 measurement events; one or more (e.g., any) L1 measurement event and / or condition; one or more (e.g., any) predicted L1 / L3 event; an explicit indication from the network; and / or a measured, predicted, or estimated throughput, error rate, buffer status, or QoS parameter.

[0178] The WTRU may execute an LTM cell switch, trigger an early TA acquisition (e.g. send a random access preamble to the target cell), and / or may perform reduced CSI reporting as long as it is within the range defined by the window and meets one or more L3 measurement event. L3 measurement events may include one or more of the following: Event A1 (e.g., Serving cell becomes better than threshold); Event A2 (e.g., Serving cell becomes worse than threshold); Event A3 (Neighbor cell becomes offset better than SpCell); Event A4 (Neighbor cell becomes better than threshold); Event A5 (SpCell becomes worse than threshold 1 and neighbor becomes better than threshold2); Event A6 (Neighbor cell becomes offset better than SCell); Event B1 (Inter RAT neighbor cell becomes better than threshold); and / or Event B2 (Pcell becomes worse than threshold 1 and inter RAT neighbor cell becomes better than threshold2).

[0179] The WTRU may execute an LTM cell switch, trigger an early TA acquisition (e.g. send a random access preamble to the target cell), and / or may perform reduced CSI reporting as long as it is within the range defined by the window and meets one or more (e.g., any) L1 measurement event and / or condition. For example, one or more (e.g., any event) provided (e.g., defined) herein (e.g., above) but which utilizes L1 / beam measurements to evaluate whether a criteria or condition is met.

[0180] The WTRU may execute an LTM cell switch, trigger an early TA acquisition (e.g. send a random access preamble to the target cell), and / or may perform reduced CSI reporting as long as it is within the range defined by the window and meets one or more (e.g., any) predicted L1 / L3 events. For example, using one or more (e.g., any) of the measurement quantities described herein (e.g., measurement quantities listed under / associated with Measured and / or predicted CSI information).

[0181] The WTRU may execute an LTM cell switch, trigger an early TA acquisition (e.g. send a random access preamble to the target cell), and / or may perform reduced CSI reporting as long as it is within the range defined by the window and meets an explicit indication from the network. For example, the WTRU may switch off CSI reportingduring a configured window, and / or (e.g. , then) execute LTM cell switch based on (e.g., upon) receiving a MAC CE from the network.

[0182] Embodiments are provided herein for an adjustable LTM handover (HO) execution window. Initial HO execution time window selection may be performed at the gNB side and / or indicated to the WTRU in the MAC CE triggering LTM cell switch using, e.g., an index to a preconfigured window position and / or length. This may be based on, e.g., reported and / or predicted radio conditions in cells A (e.g., source cell), B (e.g., target cell) - the network may determine and / or indicate (e.g., suitable) limits to minimize HO failure and / or RLF and / or avoiding too long wait (e.g. long resource reservation in the target cell).

[0183] The WTRU may determine the precise cell switch time within the configured window taking into account, e.g., the real-time / instantaneous radio condition measurements, predicted measurements, and / or service / traffic prediction - the WTRU may select the optimal time to execute LTM in order to maximize throughput based on predicted throughput at cell A and / or cell B during the configured window. The WTRU may (e.g., further) determine a more precise window within the network (NW) configured window during which the cell switch may be performed (e.g. throughput and / or failure probability within a certain tolerance limit which is better than the NW configured window provides), and / or may report to the NW to assist with Al model training.

[0184] The WTRU may receive a configuration of LTM candidate cells, and / or a configuration of allowed first handover window lengths. Configuration of LTM candidate cells, and / or a configuration of allowed first handover window lengths may include an explicit list of length values, and / or enable one of multiple predefined tables. Window sizes may correspond, e.g., to cell size / coverage / time in cell / velocity. Window size may be defined in terms of time, serving, and / or target cell RSRP range, location, etc. Configuration may include WTRU-triggered LTM cell switch conditions / criteria for triggering the cell switch within the first window. Configuration may include conditions to be used for selecting a second window, and / or an indication of the Al model to be used for a particular indicated first or second window length. Configuration may include an indication of a second window. The indication of a second window may include different actions for the WTRU to take during the first and second windows, (e.g., first window for LTM preparation steps, second window for LTM execution).

[0185] The WTRU may transmit channel state information (CSI) reporting.

[0186] The WTRU may receive LTM cell switch MAC CE, including indication of a first window time position (e.g. time offset and / or system frame number (SEN)) and / or an indication to one of the multiple predefined lengths. A determination may be made at the NW side - may be, e.g., based on the CSI report, and / or a constraint based on NW predicted radio conditions / traffic. The time offset may include (e.g., be) pointers to list of preconfigured values, explicit SFN indication, delta from current time, etc.

[0187] The WTRU may perform specific LTM actions (e g., preparation actions) during the first window. The WTRU may switch off and / or minimize, e.g. report on fewer beams and / or less frequently) candidate cell CSI reporting during the first window (e.g., the HO execution may be based on WTRU measurement and / or prediction without CSIreporting). For example, the WTRU may transmit an acknowledgement before / upon CSI reporting being paused / reduced. The WTRU may perform an early TA acquisition (e.g., random access channel (RACH) to target) during the first window. For example, the WTRU may receive random access response (RAR) including TA from target cell and / or from source. The WTRU may perform measurements and / or predictions to determine the position of the second window. For example, performing the LTM preparation during the first time duration window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0188] The WTRU may determine (e.g., may select) the position and / or the length of a second HO window within the first HO window to determine the optimal cell switch time range, and / or the WTRU may determine (e.g., select) a time within the second window to perform cell switch. For example, the WTRU may determine the second time duration window at least based on the first time duration window and / or one or more conditions (e.g., as described herein). The second time duration window may be a subset of the first time duration window. The second window may include a variable position and / or a second (e.g., shorter) length. For example, the second window may be based on more up to date (e.g., than the reported and / or NW determined) radio conditions and / or traffic prediction. For example, the aim of the second window may be to maximize throughput during the HO window. Additionally or alternatively, the second window may be determined (e.g., selected) based on explicit NW indication (e.g., NW configures). The WTRU may determine (e.g., select) a different Al measurement prediction model and / or window length selection criteria based on (e.g., depending on) window length. For example, shorter window may use (e.g., only use) radio conditions. For example, a longer window may (e.g., allow) service aspects to be taken into consideration.

[0189] The WTRU may perform second LTM actions during the second window. For example, the WTRU may monitor for a LTM trigger condition to be met during the second window.

[0190] The WTRU may perform cell switch at the determined time, and / or may transmit an indication to the other (e.g., new) cell. The WTRU may report the determined position of the second window, and / or the conditions used to determine (e.g., radio measurements, number of packets in buffer at HO time or throughput, packet delay, packet loss, location, velocity, etc.). The WTRU may send an indication (e.g., one more sequence numbers) of Hybrid automatic repeat request (HARQ) and / or radio link control (RLC) data PDUs which have been transmitted but for which the respective acknowledgements have not been received (e.g., sent but not ACKed). The WTRU may indicate a cause of HO time decision.

[0191] FIG. 6 depicts a flow chart illustrating an example of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure 600.

[0192] At 608, a WTRU 602 may receive a message (e.g., RRC Reconfiguration) from Cell A 604. The RRC Reconfiguration message 608 may include information to preconfigure LTM candidate(s) and / or a list of HO windowlengths. For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or handover to a candidate cell of a plurality of candidate cells. The configuration may include a WTRU-triggered LTM cell switch condition for triggering a cell switch within the first time duration window, one or more conditions to be used for determining the second LTM window, and / or an indication of an artificial intelligence (Al) model to be used for the determination of the second time duration window. The configuration information may include an indication of a length out of a plurality of predefined lengths that should be used for the first time duration window.

[0193] At 610, the WTRU 602 may send a message (e.g., RRC Reconfiguration complete message), for example, to cell A 604. At 612, the WTRU 602 may transmit CSI reporting, as described herein, to cell A 604. For example, the WTRU may send a CSI report. The indication of the first LTM HO window may be associated with the CSI report.

[0194] At 614, the WTRU 602 may receive a control MAC CE. The WTRU may receive an indication from a network device via the first cell to perform the cell switch and / or the handover to the candidate cell of the plurality of candidate cells. The indication may include a first time duration window. For example, the control MAC CE may include a cell switch indication, which may include pointer to target configuration and / or an indication of at least the first window length. The WTRU 602 may perform LTM preparation action(s) (e.g., switch off CSI reporting, trigger early TA acquisition on target). Performing the LTM preparation during the first time duration window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0195] The WTRU 602 may determine a second LTM HO window. The WTRU 602 may determine a second window 615 in which it can trigger LTM based on, e.g., predicted CSI. The WTRU 602 may determine a time within the second window 615 to trigger LTM, for example, based on the current radio conditions. For example, the WTRU may determine a second time duration window at least based on the first LTM HO window and / or one or more conditions (e.g., as described herein). The WTRU may determine a start position and / or a length of the second time duration window. The WTRU may determine the second time duration window based on one or more conditions (e.g., as described herein). The one or more conditions may include: radio measurement(s); one or more (e.g., a number of) packets in buffer at How time, throughput; packet delay; packet loss; location; velocity; and / or HARQ data packets sent and not acknowledged. The second time duration window may be a subset of the first time duration window. For example, the second time duration window being a subset of the first time duration window may include the first time duration window being longer than the second time duration window. The second time duration window may include a start time, a duration, and / or an end time. The cell switch and / or handover (e.g., as described herein) may occur at the end time of the second time duration window.

[0196] At 616, the WTRU 602 may send an indication to a second cell (e.g., cell B 606). The indication 616 to the second cell (e.g., cell B 606) may include MAC and / or RRC (e.g , may be sent via MAC and / or RRC). For example, the WTRU may send information indicating the second time duration window and / or the one or more conditions used to determine the second time duration window to the network device.

[0197] FIG. 7 depicts a process flow illustrating an example of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure 700.

[0198] At 702, a WTRU may receive configuration of LTM candidate cells and / or a configuration of allowed first handover window lengths. The WTRU may receive a configuration of LTM candidate cells (e.g. as described herein). The WTRU may be preconfigured with one or more LTM candidates (e.g., may include list of HO window lengths). For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or a handover to a candidate cell of the plurality of candidate cells . Additionally or alternatively, the WTRU may receive a configuration of a list of allowed first and / or second window lengths. The predefined window configurations (e.g. a window as described herein) may include explicit of length / range values, and / or enable one of multiple predefined tables and / or may correspond, e.g., to cell size / coverage / time in cell / velocity. The configuration may include WTRU-triggered LTM cell switch conditions, such as one or more as described herein.

[0199] The configuration may include condition(s) to be used for determining (e.g., selecting) a second window, and / or an indication of the Al model to be used for a particular indicated first and / or second window length. For example, the condition(s) for determining (e.g., selecting) a second window may be based on one or more (e.g., any) of the conditions described herein for triggering an LTM procedure. The configuration may include a WTRU-triggered LTM cell switch condition for triggering a cell switch within the first time duration window, one or more conditions to be used for determining the second time duration window, and / or an indication of an artificial intelligence (Al) model to be used for the determination of the second time duration window. The configuration information may include an indication of a length out of a plurality of predefined lengths that should be used for the first time duration window.

[0200] The configuration may include an explicit indication configuring a second window. The configuration may include different actions to take during the first and second windows. For example, in the first window, the WTRU may (e.g., be required to) perform LTM preparation steps (e.g., change of CSI reporting behavior, early TA acquisition) and in the second window the WTRU may be configured to perform LTM execution, if the criteria is met. Performing the LTM preparation during the first time duration window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0201] At 704, the WTRU may transmit CSI reporting. For example, the WTRU may send a CSI report. The indication of the first LTM HO window may be associated with the CSI report. The WTRU may perform CSI measurements on one or more candidate cell beams and / or may report CSI measurements to the serving cell according to the received configuration.

[0202] At 706, the WTRU may receive LTM cell switch MAC CE, including an indication of a first window time position (e.g., time offset and / or SFN) and / or an indication to one of the one or more (e.g., multiple) predefined lengths. For example, the indication associated with LTM cell switch and / or handover may be received via MAC CE. The WTRU may receive an indication from a network device via a first cell to perform cell switch and / or handover to a candidate cell of a plurality of candidate cells. The indication may include a first time duration window. The WTRU may receive a MAC CE indicating a target configuration (e.g. including a SpCell and / or one or more SCell configurations). The MAC CE may include an indication of a window position and length. This indication may be a pointer, index, and / or reference to one or more of the values, parameters, and / or configurations provided herein (e.g., when receiving configuration information) . For example, an index to a list of window configurations provided when receiving a configuration of LTM candidate cells and / or a configuration of allowed first handover window lengths may be provided herein (e.g., provided in 3).

[0203] At 708, the WTRU may perform one or more first LTM actions during the first window. The WTRU may perform one or more first LTM action(s), for example, according to the configuration. For example, during the first window, the WTRU may stop reporting CSI measurements of the configured candidate cells and / or beams in order to reduce the uplink resource overhead. When the WTRU switches off the CSI reporting, the WTRU may continue to perform the measurements in order to determine whether a condition for LTM cell switch and / or a condition for selecting a second window is met.

[0204] Additionally or alternatively, the WTRU may change the CSI measurement and / or reporting configuration during the first window. For example, measurements may be performed and / or reported according to a reduced frequency and / or using a reduced number of cells and / or beams.

[0205] In examples, the WTRU may be configured to perform early DL and / or UL sync procedures. For example, the WTRU may be configured to perform a TA acquisition procedure, which may involve transmitting one or more PRACH preambles to target cell(s) in order that the gNB can estimate the TA value to provide to the WTRU.

[0206] In examples, the WTRU may monitor the LTM cell switch condition throughout the first window.

[0207] At 710, the WTRU may determine a second LTM HO window. The WTRU may select the position and / or length of a second HO window within the first HO window. The WTRU may determine (e.g., select) the position and / or length of a second window. For example, the WTRU may determine the second time duration window based at least on the first time duration window and / or one or more conditions (e.g., as described herein). The WTRU may determine a start position and / or a length of the second time duration window. The WTRU may determine the second time duration window based on one or more conditions (e.g., as described herein). The one or more conditions mayinclude: radio measurement(s); one or more (e.g. , a number of) packets in buffer at HO time; throughput; packet delay; packet loss; location; velocity; and / or HARQ data packets sent and not acknowledged. The second time duration window may be a subset of the first time duration window. For example, the second time duration window being a subset of the first time duration window may include the first time duration window being longer than the second time duration window. The second time duration window may include a start time, a duration, and / or an end time. The cell switch (e.g., as described herein) may occur at the end time of the second time duration window.

[0208] In examples, the WTRU may utilize one or more Al predictions to determine the size and / or position of the second window, for example, using one or more (e g., any) of the inputs listed herein. The Al model may be based on (e.g., depend on) the characteristics (e.g. the length) of the first window. The Al model may be explicitly indicated by the gNB, e.g., in the MAC CE triggering cell switch and / or in the RRC configuration.

[0209] In examples, additionally or alternatively, the WTRU may determine (e.g., select) the second window characteristic(s) (e.g., start time, duration, etc.,) based on explicit network indication (e.g., the second window may indicated in a similar manner as the first window).

[0210] In examples, additionally or alternatively, the WTRU may utilize radio quality measurements (e g. any of those listed herein) to determine the second window.

[0211] In examples, the WTRU use one or more (e.g., any) other types of information (e.g. any of those listed herein) to determine the second window.

[0212] At 712, the WTRU may perform second LTM actions during the second window. The WTRU may perform a second LTM action(s), for example, according to the configuration. For example, the WTRU may monitor (e.g., a specific) one or more LTM candidate cells and / or beams to determine whether the LTM execution condition(s) are met (e.g., any of the conditions listed herein).

[0213] At 714, the WTRU may perform cell switch at the determined time, and / or may transmit an indication to the other (e.g., new) cell. The WTRU may trigger LTM cell switch and / or may reconfigure (e.g., handover) to the target candidate SpCell (e.g., and / or SCells, if configured), according to the configuration. Additionally or alternatively, the WTRU may transmit a report according to the description (e.g., WTRU reported information) as described herein. For example, the WTRU may send, to a network device, an indication (e.g., information that indicates) of the second time duration window and / or an indication of one or more conditions used to determine the second time duration window.

[0214] The NW may impose one or more restrictions, for example, based on system performance key performance indicators (KPIs) (e.g. HOF, RLF based on radio conditions) while including (e.g., allowing) freedom for the WTRU to make optimal decision(s) based on internal prediction (e.g. based on predicted traffic and / or also the more up to date radio conditions).

[0215] The NW can adapt the window based on latest / current situation, and / or indicate dynamically. The WTRU can (e.g., further) adapt the window and / or send (e.g., provide) feedback to improve NW prediction.

[0216] Throughput may be maximised during optimised handover based on AI / ML.

[0217] The amount of CSI reporting overhead may be reduced; LTM may be based on (e.g. , relies on) frequent L1 reporting to achieve optimal cell switch time. If CSI reporting can be switched off during the HO execution, then resource overhead may be reduced.

[0218] Using the embodiments described herein, such as adjustable LTM HO execution window, may allow the NW to control the suitable handover time range based (e.g., primarily) on (e.g., traditional) methods (e.g. the radio conditions may primarily dictate the suitable cell switch time), and allow the WTRU to (e.g., further) adjust based on service and / or other considerations. The Al prediction model may be improved (e.g. for training of the NW model) and / or the overall handover performance in the system may be improved. The NW may optimize the timing for PDCCH order to obtain the TA - there may be interruption if the WTRU has to re-tune to a target frequency to send RA, the NW may be able to adjust the timing to minimise the disruption based on the feedback from the WTRU and / or from machine learning.

[0219] Embodiments are provided herein for fallback and / or report if predicted LTM HO condition is not met.

[0220] The NW may determine a fallback cell based on radio conditions and / or a target cell based on a prediction. The gNB may indicate LTM handover to the target cell ahead of the condition being met, and / or may indicate a fallback condition (e.g., may be a 3rdcell, and / or may be the original source cell).

[0221] The WTRU may trigger cell switch to the indicated target cell, for example, if the predicted condition is met during a time window (e.g., as described herein). If the condition is not met, for example, (e.g., then) the WTRU may trigger a fallback. The WTRU may indicate the failure to the fallback cell.

[0222] The WTRU may receive a configuration of LTM candidate cells, and / or a configuration of one or more predefined fallback / failure conditions. Condition(s) may include measured and / or predicted radio quality metric, and / or one or more time window lengths. Condition(s) can be based on whether the WTRU determined window falls within the NW predicted window or not.

[0223] The WTRU may transmit CSI reporting (e.g., measured and / or predicted).

[0224] The WTRU may receive LTM cell switch MAC CE, including indication of one or more target cell(s), indication of the trigger condition(s), and / or indication of a fallback behavior. The fallback behavior may be an alternative target cell to trigger LTM towards, and / or may be a fallback to source cell + send a measurement report Trigger conditions, target cells, and / or fallback cells may be preconfigured (e.g., the NW may preconfigure the WTRU). Associations between (e.g., among) target / fallback / conditions may be partially and / or fully preconfigured and / or dynamically indicated in MAC CE.

[0225] The WTRU may perform LTM preparation actions (e.g. the WTRU may switch off CSI reporting and / or perform early TA acquisition during the window). Performing the LTM preparation during the first time duration window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0226] The WTRU may determine that the fal Iback / fail ure condition is met. For example, the WTRU may determine if the measured radio condition criteria is not met and / or if the TA was not successfully obtained and / or is no longer valid within the indicated time window for one of the target cells (e.g. measurement does not match the indicated prediction).

[0227] The WTRU may determine an alternative (e.g., to the indicated) window in which the handover is estimated to be completed successfully according to WTRU measurements / predictions and / or may indicate the WTRU determined window(s).

[0228] The WTRU may trigger LTM to the fallback cell and / or may transmit a report of at least the radio conditions measured of the indicated / failed target cell within the time window, window calculation, etc.

[0229] If the fallback cell is the original cell, for example, the WTRU may revert LTM preparation actions (e.g., the WTRU may resume CSI reporting).

[0230] FIG. 8 depicts a flow chart illustrating an example fallback case of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure 800.

[0231] At 810, a WTRU 802 may receive configuration information (e.g , RRC configuration) from cell A 804 (e g., source cell). The configuration information may include information associated with preconfigured LTM candidates and / or may include fallback trigger conditions. For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or handover to a candidate cell of a plurality of candidate cells.

[0232] At 812, the WTRU 802 may send a reconfiguration message to the Cell A 804 (e.g., via RRC reconfiguration complete message). At 814, the WTRU 802 may send CSI reporting to the Cell A 804.

[0233] At 816, the WTRU 802 may receive a control MAC CE from the Cell A 804. For example, the WTRU may receive an indication from the network device via the first cell to perform the cell switch and / or handover to the candidate cell of the plurality of candidate cells. The indication may include a first time duration window. The HO decision 815 may include the gNB indicating a target cell, and / or condition(s) to meet (e.g., RSRP above a threshold within the time window). The gNB and / or HO determination may indicate a fallback cell (e.g., source or another cell). The Control MAC CE 816 may include cell switch indication including pointer to target configuration, the associated condition, and / or a fallback cell in case the switch to the target cell does not succeed.. The WTRU 802 may stop and / or reduce CSI reporting. The WTRU 802 may determine whether the fallback condition is met within the time window. If the condition is met, the WTRU 802 may trigger the cell switch to the fallback cell (e.g., cell C 808) and / or target cell (e.g., Cell B 806) and / or resume CSI reporting to the source cell (e.g., cell A 804).

[0234] At 818, the WTRU 802 may send an indication to the fallback cell that the cell switch to the intended target has failed. For example, the cell switch may fail based on one or more conditions not being met within the time window.

[0235] At 820, the WTRU 802 may send an indication to the fallback cell (e.g., cell C 808) via an indication message (e.g., MAC and / or RRC). The WTRU 802 may report WTRU calculated optimal window (e.g., occurring before or after the NW indicated optimal window).

[0236] FIG. 9 depicts a process flow chart illustrating an example fallback case of the use of dual condition windows with artificial intelligence (Al) prediction to optimize LTM procedure 900.

[0237] At 902, the WTRU may receive a configuration of LTM candidate cells and / or a configuration of one or more predefined failure conditions. A WTRU may receive a configuration of LTM candidate cells (e.g. as described herein). Additionally or alternatively, the WTRU may receive a configuration of a condition for performing WTRU triggered LTM cell switch, a window (e.g. as described herein), and / or one or more failure conditions. For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or handover to a candidate cell of a plurality of candidate cells. The failure conditions may use one or more of the following: the WTRU determined cell switch time may not fall within the indicated window; the WTRU determined window may not match the NW indicated window; the WTRU determined window may differ from the NW indicated window by a predefined threshold (e.g., threshold relative to window length or position); the WTRU may detect beam failure and / or radio link failure on a source or target cell; the WTRU may fail to acquire a TA from the target cell; measured radio quality of the target cell may not meet a configured threshold within the window; and / or the WTRU may fail to complete the handover within a certain configured time limit (e.g., may fail to decode PDCCH on the target, and / or may fail random access procedure).

[0238] At 904, the WTRU may transmit CSI reporting. The WTRU may perform CSI measurements on one or more candidate cell beams and / or may report CSI measurements to the serving cell according to the received configuration.

[0239] At 906, the WTRU may receive LTM cell switch MAC CE, including indication of one or more target cells, indication of the trigger condition(s), and / or an indication of a fallback behavior. The WTRU may receive a MAC CE indicating a target configuration (e.g. including a SpCell and / or one or more SCell configurations). For example, the WTRU may receive an indication from the network device via the first cell to perform the cell switch and / or handover to the candidate cell of the plurality of candidate cells. The indication may include a first time duration window. The MAC CE may (e.g., further) include an indication of a fallback behavior This fallback behavior indication may be a pointer, index, and / or reference to one or more of the values, parameters, and / or configurations provided herein. Thefallback behavior indication may include an identification of a fallback (e.g., an alternative) cell to perform cell switch towards should the failure condition(s) be met.

[0240] At 908, the WTRU may perform one or more LTM preparation actions (e.g., stop CSI reporting). The WTRU may perform LTM preparation action(s) towards the indicated target, according to the configuration. For example, during the first window, the WTRU may stop reporting CSI measurements of the configured candidate cells and / or beams in order to reduce the uplink resource overhead, as described herein. Performing the LTM preparation during the first time duration window may include switching off CSI reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, and / or performing one or more measurements and / or one or more predictions to determine the second time duration window.

[0241] At 910, the WTRU may determine that the fallback / failure condition is met. For example, the WTRU may determine if the measured radio condition criteria is not met and / or if the TA was not successfully obtained and / or is no longer valid within the indicated time window for one of the target cells (e.g. measurement does not match the indicated prediction). The WTRU may determine that one or more failure conditions configure (e.g., as described herein) have been met.

[0242] At 912, the WTRU may determine an alternative (e.g., to the indicated) window in which the handover is estimated to be completed successfully according to WTRU measurements / predictions and / or indicate the WTRU determined window(s). The WTRU may determine, for example based on one or more (e.g., any) of the predicted and / or measured metrics described herein, an alternative window during which the WTRU may have calculated would have resulted in a successful handover (e.g. avoiding the detected failure condition by taking into account the reason for failure).

[0243] At 914, the WTRU may trigger LTM to the fallback cell and / or may transmit a report of at least the radio conditions measured of the indicated / failed target cell within the time window, window calculation, etc. The WTRU may trigger the configured fallback, which may be to return to the original (e.g., source) cell and / or may be to perform a reconfiguration to an alternative target cell. The WTRU may transmit a report to the fallback cell including information related to the failure (e.g., as described herein), with an indication of the WTRU determined window.

[0244] At 916, if fallback cell is the original cell, the WTRU may revert LTM preparation actions (e g., resume CSI reporting). The WTRU may revert one or more (e.g., any) LTM preparation actions if the fallback cell is the original cell. For example, if the WTRU stopped reporting CSI measurements during the window, then the WTRU may resume CSI measurement reporting upon failure detection, such that the gNB may use the measurements to configure an alternative mobility target.

[0245] Fallback and report if predicted LTM HO condition is not met may include the NW to attempt a faster handover by use of a predicted event occurring in the future. If the event is not met, a fallback to (e.g., traditional) methods may be used to, e.g., a macro / coverage cell. For example, if systems, methods, and apparatuses include an indication to the source cell that the condition was not met, then the NW may use measurement report to triggerhandover at the correct time. Systems, methods, and apparatuses herein may reduce the CSI reporting overhead and / or attempt to perform WTRU triggered handover, but resume CSI reporting if this is not successful within the indicated time in order to perform (e.g., more conventional) handover based on UL reports. Systems, methods, and apparatuses herein may attempt more aggressive handover to smaller cell, but in case this is not successful then trigger handover to another target, e.g., a larger coverage cell which is more stable. Systems, methods, and apparatuses herein may use the method for model training, e.g., attempting predicted handovers and / or collecting the information about what went wrong.

[0246] Embodiments are described herein for different target configuration (e.g., activated Scells) windows based on (e.g., depending on) the WTRU selection (e.g., determination) within the main window (e.g., the PCell switch time). The WTRU may be provided with (e.g., the NW may configure) one or more (e.g., multiple) target configurations (e.g. which Scells may be activated) determined (e.g., selected) based on (e.g., depending on) the precise WTRU conditions triggering SpCell change, such that the most optimal one is enabled.

[0247] The WTRU may receive a configuration of LTM candidate cells, a first SpCell change condition, and / or a configuration of one or more (e g., multiple) target (e.g. active SCell) configurations, each of which may be associated with a second condition (e.g. time window and / or RSRP range) to be applied based on (e.g., depending on) when the first SpCell change condition is met. For example, a different set of Scells may be activated (e.g., one or more different configurations) based on (e.g., depending on) the time (2ndcondition) that the SpCell switch criteria (e.g., 1stcondition) is met. For example, the SpCell cell switch decision may be based on the current SpCell going below a threshold, while the set of activated SCells may be based on (e.g., depend on) one or more of the target cells (e.g if target SpCell is within range 1 then activate SCell 1 , if within range 2 then activated SCell 2). For example, the WTRU may be provided with an SpCell change window. Based on (e.g., depending on) the actual cell switch decision time (e.g., based on prediction as systems, methods, and / or apparatuses provided herein), (e.g., then) the WTRU may activate one or more different sets of SCells.

[0248] The WTRU may transmit CSI reporting.

[0249] The WTRU may receive cell switch command, including indication of the PCell switch time window.

[0250] The WTRU may determine the optimal PCell switch time within the indicated window. The WTRU may consider in the AI / ML model evaluation the optimal SCell(s) and / or determine (e.g., select) a HO trigger time (e.g., also) based on SCell.

[0251] Based on (e.g., depending on) the determined (e.g., selected) PCell switch time (e.g., and / or other condition), for example, the WTRU may determine (e.g., select) the corresponding target configuration. For example, if the PCell switch is executed in a first time duration within the window, (e.g., then) a first set of Scells may be activated; otherwise, for example, a second set (e.g., of Scells) may be activated.

[0252] The WTRU may perform cell switch at the determined time, and / or may transmit an indication to the other (e.g., new) cell of the selected configuration.

[0253] FIG. 10 shows a potential scenario in which one or more (e.g., multiple) target configurations may be provided, and / or selected based on (e.g., depending) on the Pcell switch timing 1000. For example, consider a case where the WTRU may be served by PCell 1 1001 (e.g., the source cell) and / or has been configured to evaluate a condition for triggering LTM cell switch to PCell 2 1002 (e.g., the target cell). A (e.g., first) window 1004 (e.g. as described herein) may be provided for the WTRU 1003 to evaluate and / or determine (e.g., select) the most suitable switch time. For example, the first time duration window may include potential target SCells. Based on the PCell switch point, the optimal SCell may be different. Based on (e.g., depending on) the WTRU determination (e.g., selection), one or more different SCells may be available / suitable (e.g. because the WTRU 1003 may be moving across the coverage of multiple smaller SCells). It may be advantageous for the WTRU 1003 to (e.g., automatically) apply the most suitable configuration for the selected PCell switch time.

[0254] FIG. 11 depicts a flow chart diagram illustrating an example scenario of selecting one or more (e.g., multiple) target configurations 1100. At 1108, a WTRU 1102 may receive a message (e.g., RRC configuration) from Cell A 1104. The message may include preconfigure LTM candidates and / or may include a list of HO window lengths. For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or handover to a candidate cell of a plurality of candidate cells. At 1110, the WTRU 1102 may send a message (e.g., RRC Reconfigure complete) to the Cell A 1104. At 1112, the WTRU 1102 may send CSI reporting (e.g., to cell A 1104). At 1114, the WTRU 1102 may receive Control MAC CE, which may include cell switch indication (e.g., may include pointer to target configuration, and / or indication of window length). As FIG. 11 depicts, the network (e.g., current serving cell A 1104) may make the cell switch decision and / or may indicate the decision to perform cell switch in the MAC CE. The determination on the WTRU side may regard the (e.g., exact) timing when to perform the switching within, and / or based on that, what additional configuration to apply (e.g., if the switching to the target is done within window 1 , add cell 2 as a secondary cell; if the switching is done within window 2, add cell 3 as a secondary cell instead of cell 2, etc.). At 1115, the WTRU 1102 may determine HO trigger time within the first window. At 1116, the WTRU 1102 may send an indication (e.g., MAC and / or RRC) to the Cell B 1106 If the determined (e.g., selected) PCell switch time is within the second window, for example, the WTRU 1102 may activate a first target configuration (e.g., SCell 1). If the determined (e.g., selected) PCell switch time is within the third window, for example, the WTRU 1102 may activate a second target configuration (e.g., SCell 2).

[0255] FIG. 12 depicts a process flow chart illustrating an example scenario of selecting one or more (e.g., multiple) target configurations.

[0256] At 1202, a WTRU may receive a configuration of LTM candidate cells, a first (e.g., SpCell) change condition, and / or a configuration of one or more (e.g., multiple) target (e.g. active SCell) configurations, each of which may be associated with a second condition (e.g. time window and / or RSRP range) to be applied based on (e.g., dependingon) when the first SpCell change condition is met. The WTRU may receive a configuration of LTM candidate cells (e.g. as described herein) and / or a first condition (e.g LTM execution trigger as described herein). For example, a WTRU may receive configuration information from a network device via a first cell. The configuration information may include a first lower-layer triggered mobility (LTM) HO configuration associated with one or more candidate cells. The LTM configuration may indicate a radio resource (re)configuration to be applied when performing a cell switch and / or handover to a candidate cell of a plurality of candidate cells.. For at least one of the LTM candidate SpCells, the WTRU may be provided with one or more (e.g., multiple) target configurations which are associated with a second condition For example, the WTRU may be provided with one or more (e.g., multiple) SCell configurations, and / or the active SCells may be based on (e.g., depend on) the selected LTM cell switch time within the configured window.

[0257] In examples, the one or more (e.g., multiple) target configurations may include one or more of the following: SCell activation / deactivation states; One or more (e.g., all of, and / or any part of) an RRCReconfiguration,Cell GroupConfig, SpCellConfig, and / or SCellConfig; Measurement configurations (e.g., SSB and / or CSI-RS resource configurations, CSI reporting configuration(s), RRC Measurement event configurations, RRC Measurement reporting configurations, and / or Neigbour cell / carrier list); MAC configuration; RLC configurations; PDCP configurations; Radio bearer configurations; Physical channel configurations (e.g., PDCCH, PDSCH); Discontinuous reception (DRX) / discontinuous transmission (DTX) configurations; Cell group configurations (e.g., secondary cell group (SCG), master cell group (MCG)); Configured grant configuration; Modulation and coding scheme (MCS); and / or Random access parameters (e.g., preamble allocation, 2-step / 4-step procedure).

[0258] At 1204, the WTRU may transmit CSI reporting. The WTRU may perform CSI measurements on one or more candidate cell beams and / or may report CSI measurements to the serving cell according to the received configuration.

[0259] At 1206, the WTRU may receive LTM cell switch MAC CE, including indication of a first window. The WTRU may receive a MAC CE indicating a target configuration (e.g. including a SpCell and / or one or more SCell configurations).

[0260] At 1208, the WTRU may determine the optimal SpCell switch time within the indicated first window, for example, based on the first condition. The WTRU may select the optimal cell switch time using the LTM trigger (e.g., the first) condition configured (e.g., as described herein, based on the conditions described herein).

[0261] The WTRU may determine (e.g., select) the target SCell configuration corresponding to the determined optimal SpCell switch time, for example, based on the second condition. The WTRU may determine (e.g., select) the target configuration corresponding to the selected optimal LTM trigger (e.g., based on the conditions described herein) based on the second condition.

[0262] At 1210, the WTRU may determine (e.g., select) the LTM switch time based on the first condition (e.g., based on a predicted throughput or based on the source and / or target cell RSRP) and / or may determine (e.g., select)the target SCell configurations based on the second condition (e.g. based on the target cell RSRP and / or based on the selected cell switch time within the first window falling within a second window).

[0263] At 1212, the WTRU may perform LTM cell switch at the determined time, for example, by using the selected configuration and / or may transmit an indication to the new cell of the selected configuration. The WTRU may perform LTM cell switch at the selected time using the selected target configuration, and / or may transmit a report to the network indicating at least the selected configuration. In examples, the report further includes one or more of the WTRU reported information described herein.

[0264] One or more target CA (e.g., PCell + SCell) configurations can be provided, and / or the optimal one (e.g for throughput using a CA configuration) may be activated based on (e.g., depending on) the selected (e.g. for coverage) PCell switch time.

Claims

CLAIMS:1 . A wireless transmit / receive unit (WTRU) comprising: a processor configured to: receive configuration information from a network device via a first cell, wherein the configuration information comprises an indication of a first lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells, wherein the LTM configuration indicates a radio resource configuration to be applied when performing handover to a candidate cell of a plurality of candidate cells; receive an indication from the network device via the first cell to perform the handover to the candidate cell of the plurality of candidate cells, and wherein the indication comprises a first time duration window; determine a second time duration window at least based on the first time duration window and one or more conditions, wherein the second time duration window is a subset of the first time duration window; and send, to the network device, information indicating the second time duration window and the one or more conditions used to determine the second time duration window.

2. The WTRU of claim 1 , wherein the processor is configured to perform the handover in accordance with the radio resource configuration, and wherein the processor is configured to perform LTM preparation during a start of the first time duration window.

3. The WTRU of claim 2, wherein the processor being configured to perform LTM preparation during the first time duration window comprises the processor being configured to: switch off channel state information (CSI) reporting, transmit hybrid automatic repeat request (HARQ) feedback, perform early timing advance (TA) acquisition, or perform one or more measurements or one or more predictions to determine the second time duration window.

4. The WTRU of claim 1 , wherein the configuration information comprises a WTRU-triggered LTM cell switch condition for triggering a cell switch within the first time duration window, one or more conditions to be used for determining the second time duration window, or an indication of an artificial intelligence (Al) model to be used for the determination of the second time duration window.

5. The WTRU of claim 1 , wherein the configuration information comprises an indication of a length out of a plurality of predefined lengths that should be used for the first time duration window.

6. The WTRU of claim 1 , wherein the indication is received via a medium access control (MAC) control element (CE).

7. The WTRU of claim 1 , wherein the processor being configured to determine the second time duration window comprises the processor being configured to determine a start position and length of the second time duration window.

8. The WTRU of claim 1 , wherein the second time duration window being a subset of the first time duration window comprises the first time duration window being longer than the second time duration window, and wherein the second time duration window comprises a start time, a duration, or an end time, and wherein a cell switch occurs at the end time of the second time duration window.

9. The WTRU of claim 1 , wherein the processor is configured to send a channel state information (CSI) report, wherein the indication of the first LTM HO window is associated with the CSI report.

10. The WTRU of claim 1 , wherein the processor is configured to determine the second time duration window based on one or more conditions, wherein the one or more conditions comprise one or more of: radio measurements, number of packets in buffer at HO time, throughput, packet delay, packet loss, location, velocity, or hybrid automatic repeat request (HARQ) data packets sent and not acknowledged.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information from a network device via a first cell, wherein the configuration information comprises an indication of a first lower-layer triggered mobility (LTM) configuration associated with one or more candidate cells, wherein the LTM configuration indicates a radio resource configuration to be applied when performing handover to a candidate cell of a plurality of candidate cells; receiving an indication from the network device via a first cell to perform the handover to the candidate cell of the plurality of candidate cells, and wherein the indication comprises a first time duration window; determining a second time duration window at least based on the first time duration window and one or more conditions, wherein the second time duration window is a subset of the first time duration window; and sending, to the network device, information indicating the second time duration window and the one or more conditions used to determine the second time duration window.12 The method of claim 11 , further comprising performing handover in accordance with the radio resource configuration, and further comprising performing LTM preparation during a start of the first time duration window.

13. The method of claim 12, wherein performing LTM preparation during the first time duration window comprises: switching off channel state information (CSI) reporting, transmitting hybrid automatic repeat request (HARQ) feedback, performing early timing advance (TA) acquisition, or performing one or more measurements or one or more predictions to determine the second time duration window.

14. The method of claim 11 , wherein the configuration information comprises a WTRU-triggered LTM cell switch condition for triggering a cell switch within the first time duration window, one or more conditions to be used for determining the second time duration window, or an indication of an artificial intelligence (Al) model to be used for the determination of the second time duration window.

15. The method of claim 11, wherein the configuration information comprises an indication of a length out of a plurality of predefined lengths that should be used for the first time duration window.

16. The method of claim 11, wherein the indication is received via a medium access control (MAC) control element (CE).

17. The method of claim 11, wherein determining the second time duration window comprises determining a start position and length of the second time duration window.

18. The method of claim 11 , wherein the second time duration window being a subset of the first time duration window comprises the first time duration window being longer than the second time duration window, and wherein the second time duration window comprises a start time, a duration, or an end time, and wherein a cell switch occurs at the end time of the second time duration window.19 The method of claim 11 , further comprising sending a channel state information (CSI) report, wherein the indication of the first LTM HO window is associated with the CSI report.

20. The method of claim 1 , wherein the second time duration window is determined based on one or more conditions, wherein the one or more conditions comprise one or more of: radio measurements, number of packets in buffer at HO time, throughput, packet delay, packet loss, location, velocity, or hybrid automatic repeat request (HARQ) data packets sent and not acknowledged.

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