WO2025174869A1

WO2025174869A1 - Adaptive conditional layer triggered mobility (ltm) and triggering of l1 measurement reporting

Info

Publication number: WO2025174869A1
Application number: PCT/US2025/015572
Authority: WO
Inventors: Brian Martin; Oumer Teyeb; Umer Salim; Martino Freda; Paul Marinier; Erdem Bala; Dylan WATTS; Keiichi Kubota
Original assignee: InterDigital Patent Holdings Inc
Current assignee: InterDigital Patent Holdings Inc
Priority date: 2024-02-12
Filing date: 2025-02-12
Publication date: 2025-08-21
Anticipated expiration: 2026-08-12

Abstract

A wireless transmit/receive unit (WTRU) may receive first configuration information. The first configuration information may include an indication of a first condition associated with one or more LTM cells. The WTRU may determine that the first condition is satisfied. The WTRU may receive second configuration information. The second configuration information may include an indication of a second condition associated with the one or more candidate LTM cells. The WTRU may determine that the second condition is satisfied. The WTRU may send an indication to select a cell of the one or more candidate LTM cells, for example based on the determination that the first condition is satisfied and/or on the determination that the second condition is satisfied.

Description

ADAPTIVE CONDITIONAL LAYER TRIGGERED MOBILITY (LTM) AND TRIGGERING OF L1 MEASUREMENT REPORTING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Application No. 63/552,482 filed on February 12, 2024, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] In RRC_CONNECTED, a wireless transmit/receive unit (WTRU) may measure multiple beams (e.g., at least one) of a cell and/or the measurements results (e.g., power values) may be averaged to derive the cell quality. The WTRU may be configured to consider a subset of the detected beams. Filtering may take place at different levels, for example two different levels. The two levels may include the physical layer to derive beam quality and (e.g., then) at the radio resource control (RRC) level to derive cell quality from 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). Measurement reports may contain the measurement results of the X best beams, for example if the WTRU is configured to do so by a gNB.

SUMMARY

[0003] Systems and methods herein may include one or more of layer 2 (L2) triggered mobility (LTM), conditional handover (CHO), conditional LTM, and/or layer 1 (L1) triggered measurement reporting. Additionally, or alternatively, systems and methods herein may be associated with fifth generation (5G) new radio (NR) and/or mobility enhancements.

[0004] There may be L1 and/or layer 3 (L3) measurement interaction, for example for evaluating conditional LTM trigger conditions. There may be network controlled conditional criteria modification. There may be WTRU autonomous conditional criteria modification. There may be L1 event triggered reporting conditions, for example beam stability. A L1 triggered beam stability report may be for (e.g., explicit) LTM. A WTRU based TA measurement report trigger may be for L1 report/conditional LTM. A WTRU based TA measurement report may be for (e.g., conditional and/or explicit) LTM preparation.

[0005] A wireless transmit/receive unit (WTRU) may receive configuration information. The configuration information may include a threshold and/or an indication of one or more candidate layer triggered mobility (LTM) cells. The WTRU may measure a value of a first cell of the one or more candidate LTM cells. The WTRU may determine that the value is greater than or equal to the threshold. The WTRU may transmit a report based on the determination.

[0006] The threshold may include one or more of a system information block (SSB) value, a channel state information (CSI)-reference signal (RS) value, a timing advance (TA) value, and/or a beam stability value. The WTRU may transmit the report in one or more of a medium access control (MAC) control element (CE) and/or a channel state information (CSI) message. The value may include a first value. The threshold may include a first threshold. The configuration information may include a second threshold. The WTRU may measure a second value of the first cell of the one or more candidate LTM cells and/or determine that the second value is greater than or equal to the second threshold. The WTRU may transmit the report based on the determination that the first value is greater than or equal to the threshold and/or the determination that the second value is greater than or equal to the second threshold.

[0007] A WTRU may receive first configuration information. The first configuration information may include an indication of a first condition associated with one or more LTM cells. The WTRU may determine that the first condition is satisfied. The WTRU may receive second configuration information. The second configuration information may include an indication of a second condition associated with the one or more candidate LTM cells. The WTRU may determine that the second condition is satisfied. The WTRU may send an indication to select a cell of the one or more candidate LTM cells, for example based on the determination that the first condition is satisfied and/or on the determination that the second condition is satisfied.

[0008] The first condition may include a layer 1 condition. The WTRU may perform a layer 1 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 1 measurement with the layer 1 condition. The layer 1 measurement may include a first layer 1 measurement and/or the layer 1 condition may include a first layer 1 condition. The layer 1 measurement may include one or more of a reference signal received power (RSRP) and/or a received signal strength indicator (RSSI), for example associated with one or more of a cell and/or a beam. The WTRU may perform a second layer 1 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 1 measurement with a second layer 1 condition. The WTRU may determine that the first condition is satisfied based on the comparison of the first layer 1 measurement to the first layer 1 condition and/or on the comparison of the second layer 1 measurement to the second layer 1 condition.

[0009] The layer 1 condition may include a threshold associated with one or more of a SSB value, a channel state information CSI-RS value, a TA value, or a beam stability value. The second condition may include a layer 3 condition. The WTRU may perform a layer 3 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 3 measurement with the layer 3 condition. The layer 3 measurement may include a filtered measurement, for example associated with one or more of a cell or a beam.

[0010] The WTRU may determine that the first condition is satisfied subsequent to receiving the second configuration information. The WTRU may send a message indicating that the first condition has been satisfied. For example, the WTRU may send the indication to select a cell of the one or more candidate LTM cells based on a time limit subsequent to the determination that the first condition is satisfied. The WTRU may receive an indication to modify the first condition. For example, the configuration information (e.g., first configuration information and/or second configuration information) may include the indication to modify the first condition. The WTRU may modify the first condition based on the indication. The WTRU may determine that the first condition is satisfied based on the modification of the first condition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0012] 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.

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

[0014] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0015] FIG. 2 is an example of a high-level measurement model.

[0016] FIG. 3 shows an example of LTM operation.

[0017] FIG. 4 shows an example of an LTM procedure.

[0018] FIG. 5 shows an example of beam refinement.

[0019] FIG. 6 shows an example of network controlled conditional criteria modification of a second criteria based on report of a first criteria.

[0020] FIG. 7 shows an example of WTRU autonomous conditional criteria modification of a second criteria based on report of a first criteria. [0021] FIG. 8 shows an example of L1 triggered beam stability report for explicit LTM.

[0022] FIG. 9 is an example of WTRU based TA measurement report for LTM preparation.

DETAILED DESCRIPTION

[0023] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0024] As shown in FIG. 1 A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a CN 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and/or a “ST A”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g, remote surgery), an industrial device and applications (e.g, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU. [0025] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the I nternet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (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.

[0026] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0027] 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).

[0028] 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). [0029] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0030] I n an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using New Radio (NR).

[0031] 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).

[0032] 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.

[0033] 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. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115. [0034] 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.

[0035] 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.

[0036] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0041] 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. [0042] 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).

[0043] 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.

[0044] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0045] 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.

[0046] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0047] 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.

[0048] 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.

[0049] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0050] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0055] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0056] In representative embodiments, the other network 112 may be a WLAN.

[0057] 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 ST As within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g. , directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11 e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (I BSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad- hoc” mode of communication.

[0058] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g, only one station) may transmit at any given time in a given BSS.

[0059] 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.

[0060] 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).

[0061] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control/Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0062] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a ST A, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0063] 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.

[0064] 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.

[0065] 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).

[0066] 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).

[0067] 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.

[0068] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0069] 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.

[0070] 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. [0071] 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.

[0072] 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.

[0073] 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.

[0074] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[0075] 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.

[0076] 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. The terms UE and WTRU may be used interchangeably herein.

[0077] A wireless transmit/receive unit (WTRU) may receive configuration information. The configuration information may include a threshold and/or an indication of one or more candidate layer triggered mobility (LTM) cells. The WTRU may measure a value of a first cell of the one or more candidate LTM cells. The WTRU may determine that the value is greater than or equal to the threshold. The WTRU may transmit a report based on the determination.

[0078] The threshold may include one or more of a system information block (SSB) value, a channel state information (CSI)-reference signal (RS) value, a timing advance (TA) value, and/or a beam stability value. The WTRU may transmit the report in one or more of a medium access control (MAC) control element (CE) and/or a channel state information (CSI) message. The value may include a first value. The threshold may include a first threshold. The configuration information may include a second threshold. The WTRU may measure a second value of the first cell of the one or more candidate LTM cells and/or determine that the second value is greater than or equal to the second threshold. The WTRU may transmit the report based on the determination that the first value is greater than or equal to the threshold and/or the determination that the second value is greater than or equal to the second threshold.

[0079] A WTRU may receive first configuration information. The first configuration information may include an indication of a first condition associated with one or more LTM cells. The WTRU may determine that the first condition is satisfied. The WTRU may receive second configuration information. The second configuration information may include an indication of a second condition associated with the one or more candidate LTM cells. The WTRU may determine that the second condition is satisfied. The WTRU may send an indication to select a cell of the one or more candidate LTM cells, for example based on the determination that the first condition is satisfied and/or on the determination that the second condition is satisfied.

[0080] The first condition may include a layer 1 condition. The WTRU may perform a layer 1 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 1 measurement with the layer 1 condition. The layer 1 measurement may include a first layer 1 measurement and/or the layer 1 condition may include a first layer 1 condition. The layer 1 measurement may include one or more of a reference signal received power (RSRP) and/or a received signal strength indicator (RSSI), for example associated with one or more of a cell and/or a beam. The WTRU may perform a second layer 1 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 1 measurement with a second layer 1 condition. The WTRU may determine that the first condition is satisfied based on the comparison of the first layer 1 measurement to the first layer 1 condition and/or on the comparison of the second layer 1 measurement to the second layer 1 condition.

[0081] The layer 1 condition may include a threshold associated with one or more of a SSB value, a channel state information CSI-RS value, a TA value, or a beam stability value. The second condition may include a layer 3 condition. The WTRU may perform a layer 3 measurement associated with the one or more candidate LTM cells. The WTRU may compare the layer 3 measurement with the layer 3 condition. The layer 3 measurement may include a filtered measurement, for example associated with one or more of a cell or a beam.

[0082] The WTRU may determine that the first condition is satisfied subsequent to receiving the second configuration information. The WTRU may send a message indicating that the first condition has been satisfied. For example, the WTRU may send the indication to select a cell of the one or more candidate LTM cells based on a time limit subsequent to the determination that the first condition is satisfied. The WTRU may receive an indication to modify the first condition. For example, the configuration information (e.g., first configuration information and/or second configuration information) may include the indication to modify the first condition. The WTRU may modify the first condition based on the indication. The WTRU may determine that the first condition is satisfied based on the modification of the first condition.

[0083] FIG. 2 is an example of a high-level measurement model 200. For example, in RRC_CONNECTED, the WTRU may measure one or more (e.g., multiple) beams of a cell. The WTRU may average measurements results (e.g., power values), for example to derive cell quality. The WTRU may be configured to consider a subset of the detected beams. Filtering may take place at different levels, for example at two different levels. The two levels may include the physical layer to derive beam quality and/or (e.g, then) at the radio resource control (RRC) level to derive cell quality from multiple beams. Cell quality from beam measurements may be derived in the same way for the serving cell (s) and/or for the nonserving cell(s). Measurement reports may contain the measurement results of the X best beams, for example if the WTRU is configured to do so by the gNB.

[0084] A network (e.g, gNB) may transmit a number of beams. For example the network may transmit K beams. At 202 the WTRU may filter the beams, for example each beam. For example, there may be layer 1 filtering of each beam. The filtering may be WTRU implementation specific. The RRC layer may configure parameters, for example for beam consolidation and/or selection, for layer 3 filtering for cell quality, and/or for reporting criteria evaluation. At 204 the WTRU may perform beam consolidation and/or selection (e.g. using the filtered beams). At 206 the WTRU may perform layer 3 filtering for cell quality. At 208 the WTRU may evaluate reporting criteria. The WTRU may (e.g., then) report. At 210, for example after 202, the WTRU may perform layer 3 (L3) beam filtering (e.g., on K beams). The WTRU may (e.g., then) perform beam selection for reporting at 212. The WTRU may (e.g., then) report.

[0085] Systems and methods herein may include one or more of layer 2 (L2) triggered mobility (LTM), conditional handover (CHO), conditional LTM, and/or layer 1 (L1) triggered measurement reporting. Additionally, or alternatively, systems and methods herein may be associated with fifth generation (5G) new radio (NR) and/or mobility enhancements.

[0086] There may be L1 and/or layer 3 (L3) measurement interaction, for example for evaluating conditional LTM trigger conditions. There may be network controlled conditional criteria modification. There may be WTRU autonomous conditional criteria modification. There may be L1 event triggered reporting conditions, for example beam stability. A L1 triggered beam stability report may be for (e.g., explicit) LTM. A WTRU based TA measurement report trigger may be for L1 report/conditional LTM. A WTRU based TA measurement report may be for (e.g., conditional and/or explicit) LTM preparation. LTM as herein may mean layer triggered mobility. The layer may be L2 for example. The layer may be L1/L2 for example. The layer may be L1 , for example.

[0087] Systems and methods may include inter-cell L1/L2 (Iayer1/layer2) triggered mobility. Inter-cell beam management may manage the beams, for example in a carrier aggregation (CA) case. In some examples, no cell change/add is supported. There may be systems and methods of L1/L2 based inter-cell mobility for mobility latency reduction. For example, configuration and/or maintenance for multiple candidate cells may allow (e.g., fast) application of configurations for candidate cells (e.g., RAN2, RAN3). A dynamic switch mechanism, for example among candidate serving cells (e.g., including SpCell and/or SCell) for the potential applicable scenarios may be based on L1/L2 signaling (e.g, RAN2, RAN1). There may be L1 enhancements for inter-cell beam management, for example including L1 measurement and/or reporting, and/or beam indication (e.g, RAN1 , RAN2). Early RAN2 involvement may be utilized, for example including further clarifying the interaction between RAN2 and L1 enhancements for inter-cell beam management.

[0088] There may be timing advance management (e.g, RAN1 , RAN2). A centralized unit-distributed unit (CU-DU) interface signaling may support L1/L2 mobility, for example in RAN3. FR2 specific enhancements may not be precluded. L1/L2 based inter-cell mobility may be applicable to one or more of standalone, CA and NR-DC with a serving cell change within one CG, intra-DU case and intra-CU inter-DU (e.g, applicable for Standalone and CA and/or where no new RAN interfaces are expected), (e.g., both) intra-frequency and inter-frequency, (e.g., both) FR1 and FR2, when source and target cells may be synchronized or nonsynchronized; and/or inter-CU may not be included.

[0089] L1/L2 based mobility and/or inter-cell beam management may address intra-distributed unit (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/L2 based mobility). In frequency range 2 (FR2) deployments for example, carrier aggregation (CA) may be used in order to exploit the available bandwidth (e.g., to aggregate multiple CCs in one band). These component carriers (CCs) may be transmitted with the same analog beam pair (e.g., gNB beam and/or WTRU beam).

[0090] The WTRU may be configured with transmission configuration indicator (TCI) states (e.g., can have fairly large number, e.g. 64) for reception of PDCCH and/or physical downlink shared channel (PDSCH). Each TCI state may include a RS and/or synchronization signal block (SSB). The WTRU may refer to the RS and/or SSB for setting a beam. The SSB may be associated with a non-serving PCI. MAC signaling (e.g., TCI state indication for WTRU-specific PDCCH medium access control (MAC) control element (CE)) may activate the TCI state for a control resource set (CORESET)/ physical downlink control channel (PDCCH).

[0091] Reception of PDCCH from a non-serving cell may be supported by MAC CE, for example by indicating a TCI state associated to non-serving PCI. MAC signaling (e.g., TCI States Activation/Deactivation for WTRU-specific PDSCH) may activate a subset of (e.g., up to) 8 TCI states, for example for PDSCH reception. DCI may indicate one (e.g., which) of the 8 TCI states. A unified TCI state may additionally, or alternatively be supported, for example with a different updating mechanism (e.g., DCI- based) and/or without multi-TRP. A unified TCI state with multi-TRP may be supported.

[0092] LTM may improve handover latency. For example with a conventional L3 handover and/or with a conditional handover, the WTRU may first send a measurement report using RRC signaling. The network may provide a (e.g., further) measurement configuration and/or a conditional handover configuration, for example in response to the measurement report (e.g., from the WTRU). The network may provide a configuration for a target cell (e.g., for handover), for example after the WTRU reports using RRC signaling that the cell meets a configured radio quality criteria. In order to reduce the handover failure rate due to the delay in sending a measurement report then receiving an RRC reconfiguration for example, the network may provide (e.g., in advance) a target cell configuration and/or a measurement criteria. The target cell configuration and/or measurement criteria may be used to determine when the WTRU should trigger the CHO configuration. Some L3 methods may include delay due to the sending of measurement reports and/or receiving of target configurations, for example in conventional (e.g., non-conditional) handover. [0093] LTM may allow an (e.g., fast) application of configurations for candidate cells, for example including dynamically switching between SCells and switching of the PCell (e.g. switch the roles between SCell and PCell) without performing RRC signaling. The inter-CU case may include relocation of the PDCP anchor. Therefore, an RRC based approach may be desired, for example to support at least inter-CU handover.

[0094] With some L3 handover mechanisms for example, any currently active SCell(s) may be released before the WTRU moves and/or completes the handover to a target cell in the coverage area of a new site. Additionally, or alternatively, the currently active SCell(s) may (e.g., only) be added back after successful handover, which for example may lead to throughput degradation during handover. L1/L2 may enable CA operation to be enabled instantaneously upon serving cell change.

[0095] 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 is achieved using L1/L2 signaling. L1/L2 signaling may be used for SCell activation and/or deactivation, for example for inter-CU handover. Cell candidates may include one or more of Cell 1 (e.g., 3.5 GHz), Cell2 (e.g., 2.1 GHz), Cell3 (e.g., 26 GHz), and/or Cell 4 (e.g., 26 GHz). A WTRU 302 may move, for example in a direction. As the WTRU 302 moves for example, there may be a switch between cells. For example, RRC may (e.g., initially) configure Cells 1-4 as candidates. RRC may activate PCelU and/or SCell2. As the WTRU 302 moves there may be a (e.g., dynamic) switch between Cell2 and Cell3. As the WTRU 302 moves further (e.g., in the direction), there may be a (e.g., dynamic) PCell switch to Celli and/or a (e.g., dynamic) SCell switch to Cell4.

[0096] An LTM procedure may include a gNB receiving one or more L1 measurement report(s) from a WTRU. The gNB may change a WTRU serving cell by a cell switch command signaled via a MAC CE, for example based on the one or more measurement report(s). The cell switch command may indicate an LTM candidate configuration, for example that the gNB previously prepared and provided to the WTRU through RRC signaling. The WTRU may (e.g., then) switch to the target configuration according to the cell switch command. The LTM procedure may be used to reduce mobility latency.

[0097] When configured by the network for example, TCI states of one or more cells that are different from the current serving cell may be activated. For example, the TCI states of the LTM candidate cells may be activated before any of the LTM candidate cells become the serving cell. The WTRU may (e.g., therefore) be DL synchronized with those cells, which for example may facilitate a faster cell switch to one of the LTM candidate cells when cell switch is triggered.

[0098] When configured by the network for example, a UL TA acquisition (e. g. , early TA) procedure of one or more cells (e.g., that are different from the current serving cells) may be initiated. If the cell has the same NTA as the current serving cells and/or NTA=0 for example, an early TA acquisition procedure may not be used. The network may request that the WTRU perform early TA acquisition of a candidate cell, for example before a cell switch. The early TA acquisition procedure may be triggered by PDCCH order and/or realized through WTRU-based TA measurement as configured by RRC. When triggered by PDCCH order for example, a gNB (e.g., to which the candidate cell belongs) may calculate the TA value and/or sends the TA value to the gNB to which the serving cell belongs. The serving cell may send the TA value in the LTM cell switch command MAC CE, for example when triggering LTM cell switch.

[0099] When the TA acquisition procedure is triggered by a WTRU-based TA measurement as configured by RRC for example, the WTRU may perform the TA measurement for the candidate cells after being configured by RRC. The exact time the WTRU may perform the TA measurement may be up to WTRU implementation. The WTRU may apply the TA value measured and/or perform RACH-less LTM, for example upon receiving the cell switch command. The network may additionally, or alternatively, send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0100] Depending on the availability of a valid TA value for example, the WTRU may perform (e.g., either) a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command for example, the WTRU may apply the TA value (e.g., as instructed by the network). When the WTRU- based TA measurement is configured but no TA value is provided in the cell switch command for example, the WTRU may apply the TA value (e.g., if available). The WTRU may perform a RACH-less LTM cell switch, for example upon receiving the cell switch command. If no valid TA value is available for example, the WTRU may perform a RACH-based LTM cell switch.

[0101] PDCCH order may be followed, which for example may include requesting a random access procedure to the candidate cells. The WTRU may follow the PDCCH order whether or not the WTRU is configured for WTRU-based TA measurement for a certain candidate cell. Additionally, or alternatively, the WTRU may follow PDCCH order for candidate cells for which the WTRU may derive TA values.

Additionally, or alternatively, regardless of whether the WTRU has already performed a random access procedure towards the candidate cells, the WTRU may use the WTRU-based measurement configuration if configured by the network. [0102] For RACH-less LTM for example, the WTRLI may access the target cell using (e.g., either) a configured grant and/or a dynamic grant. The configured grant may be provided in the LTM candidate configuration. The WTRU may select the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell for example, the WTRU may start to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion for example, the WTRU may not trigger a random access procedure. For example the WTRU may not trigger a random access procedure if the WTRU does not have a valid PUCCH resource for triggered SRs.

[0103] A security key may be maintained, for example upon an LTM cell switch. Subsequent LTM may be supported. LTM may support (e.g., both) intra-gNB-DU and/or intra-gNB-CU inter-gNB-DU mobility. LTM may support (e.g., both) intra-frequency and/or inter-frequency mobility, for example including mobility to inter-frequency cell that is not a current serving cell. LTM may be supported for the licensed spectrum.

[0104] A PCell change in a non-CA scenario and/or a non-DC scenario may be supported. A PCell and/or SCell(s) change in CA scenario may be supported. A PCell and MCG SCell(s) change and intra-SN PSCell and SCG SCell(s) change without MN involvement may be supported, for example in a dual connectivity scenario. LTM for simultaneous PCell and PSCell change may not be supported. The WTRU may execute any L3 handover command sent by the network, for example when the WTRU has stored LTM candidate configurations.

[0105] FIG. 4 shows an example of an LTM procedure 400. A WTRU 402 may be in RRC_CONNECTED mode. At 406 the WTRU may send a MeasurementReport message to a gNB 404. The gNB 404 may determine to configure LTM and/or initiates LTM candidate preparation. At 408 the gNB 404 may transmit an RRCReconfiguration message to the WTRU 402, for example including the LTM candidate configurations. The WTRU 404 may store the LTM candidate configurations. Additionally, or alternatively, at 410 the WTRU 402 may transmit an RRCReconfigurationComplete message to the gNB 404. At 412 the WTRU 402 may perform DL synchronization with the candidate cell(s), for example before receiving the cell switch command. At 414 the WTRU 402 may perform UL synchronization with the candidate cell(s), for example before receiving the cell switch command.

[0106] When WTRU-based TA measurement is configured for example, the WTRU 402 may acquire the TA value(s) of the candidate cell(s) by measurement. The WTRU 402 may perform early TA acquisition with the candidate cell(s) as requested by the network, for example before receiving the cell switch command. The WTRU 402 may send a preamble to the indicated candidate cell, for example after CFRA triggered by a PDCCH order from the source cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s) for example, the WTRU 402 may not receive random access response from the network for the purpose of TA value acquisition and/or the TA value of the candidate cell may be indicated in the cell switch command. The WTRU 402 may not maintain the TA timer for the candidate cell and/or may rely on network implementation, for example to guarantee the TA validity. [0107] The WTRU 402 may perform L1 measurements on the configured candidate cell (s) . At 416 the WTRU 402 may transmit a L1 measurement reports to the gNB 404. The gNB 404 may determine to execute a cell switch to a target cell. At 418 the gNB 404 may transmit the cell switch command, for example in a MAC CE. For example, the gNB 404 may include the candidate configuration index of the target cell in the cell switch command. The WTRU 402 may detach from the source cell, switch to the target cell, and/or apply the configuration indicated by candidate configuration index. The WTRU 402 may perform a random access procedure with the target cell, for example if WTRU 402 does not have valid TA of the target cell. At 422 the WTRU 402 may complete the LTM procedure 400.

[0108] For example, the WTRU may complete the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the WTRU 402 has performed a RA procedure (e.g., at 420) for example, the WTRU may determine that the LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM for example, the WTRU 402 may determine that a LTM cell switch execution is successfully completed when the WTRU determines that the network has successfully received first UL data. In some examples steps 412, 414, 416, 418, 420, and/or 420 may be performed multiple times, for example for subsequent LTM using the LTM candidate configuration(s) provided (e.g., at 408). A procedure (e.g., 400) over an air interface described, for example as in FIG. 4 may be applicable to (e.g., both) intra-gNB-DU LTM and/or inter-gNB-DU LTM. LTM procedures may be over F1-C interface in some examples.

[0109] Systems and methods may include RACH-less LTM. A WTRU may perform early timing advance (TA) acquisition with candidate cell(s), for example before receiving the cell switch command. The WTRU may perform early TA acquisition with candidate cell (s) via contention-free random access (CFRA), for example triggered by a PDCCH order from the source cell. The WTRU may (e.g., then) send a preamble to a candidate cell. Information that identifies the allocated CFRA resource may be indicated in the PDCCH order, for example to enable shared preamble resource among multiple WTRUs in the RRC configuration. The source gNB may (e.g., dynamically) indicate which WTRU uses the resource at any specific time. [0110] The WTRU may not receive RAR (e.g., at all) , for example In order to minimize the data interruption of the source cell due to CFRA to the candidate cell(s) for example. A source cell may trigger a preamble retransmission/power ramping using another PDCCH order, for example if the preamble was not received. If the TA value of the candidate cell is indicated in the cell switch command for example, the WTRU may perform a RACH-less handover. Additionally, or alternatively, the WTRU may support and/or be configured with a WTRU-based TA measurement, for example whereby the WTRU may acquires the TA value(s) of the candidate cell(s) by measurement. If the cell switch command does not contain a TA value and/or the WTRU has acquired a TA measurement for example, the WTRU may perform a RACH-less handover. For example, the WTRU may perform a RACH-less handover if configured by RRC.

[0111] A L1/L2 triggered mobility (LTM) procedure may improve mobility latency, for example by one or more of preconfiguring multiple target cells prior to handover, early DL/UL sync of target cells, L1 measurement reports, and/or MAC CE to indicate cell switch. There may be measurements related enhancements for purpose of supporting LTM (e.g., RAN2, RAN1). Measurement related enhancements may be applicable to intra-CU master cell group (MCG)Zsecondary cell group (SCG) LTM and/or inter-CU MCG/SCG LTM. Components (e.g., necessary components) to support event triggered L1 measurement reporting (e.g., RAN2, RAN1) may be specified. RAN1 and/or RAN2 may progress (e.g., independently) on the event triggered measurements objectives of their respective MIMO and/or mobility enhancement. Support for channel state information (CSI)-reference signal (RS) measurements for LTM procedures and/or to enable CSI-RS based beam management are disclosed herein. Other physical layer operations on candidate cells before LTM (e.g., RAN1) are disclosed herein.

[0112] Support of conditional LTM (e.g., RAN2, RAN3, RAN1) may be specified. WTRU evaluated conditions for triggering LTM may be specified. Systems and methods to support conditional LTM including subsequent LTM may be included herein. Intra-CU LTM may be prioritized in some examples.

[0113] LTM may allow for improved latency and/or reduced interruption. L3 conditional handover (CHO) may enable (e.g., more) robust mobility, for example by reducing RLF and/or HOF. However, L3 CHO may use L3 filtering and/or time-to-trigger to determine that a target is suitable, for example to avoid failure at the target and/or to reduce ping-pong. Using L1 measurements, for example instead of L3 measurements may enable latency improvement.

[0114] LTM may use a CSI reporting framework, which for example may support periodic CSI reporting (e.g., transmission of a CSI report at fixed preconfigured intervals) and/or aperidoc CSI reporting (e.g., in response to an explicit network request). CSI reporting may support scheduling and/or beam management in a serving cell, which for example may utilize frequent reporting. However, mobility events may be less frequent and/or use of CSI reporting may imply significant signalling overhead. Therefore event triggered reporting, for example similar to L3 measurements, may be used to support mobility.

[0115] Systems and methods herein address aspects of measurement improvement for LTM. For example, systems and methods address triggering the event-triggered L1 report and/or conditional LTM. Systems and methods address L1 events making use of shorter triggering times and/or unfiltered measurements. Systems and methods may address providing robustness and/or avoiding unnecessary ping-pong without compromising latency. Systems and methods may address one or more of improved stability, reduced ping-pong due to reduction or lack of measurement filtering, improved efficiency of resource reservation in the network (NW) (e.g. CG for RACH-less, CSI reporting resources on PUCCH), and/or (e.g., while) maintaining better latency and/or interruption offered by LTM.

[0116] There may be adaptive conditional LTM. A combination and/or interaction between L3 filtered measurements and L1 unfiltered measurements may be used to determine the CHO trigger. Interaction between the L1 and L3 measurements may be used to dynamically update the C-LTM parameters. The outcome/result of evaluation of one of the measurement types may be utilized to adjust parameters used for evaluation of the other measurement type. A WTRU may be configured with multiple measurement conditions, for example which may be met before C-LTM can be triggered. If at least one condition is met for example, an L1 report may be triggered (e.g. to inform NW that C-LTM is likely such that the network may prepare resources on the target such as a configured grant and/or may indicate/update the resource to the WTRU). A network (NW) may indicate a value for the second condition (e.g. time, relative threshold). The LTM may be triggered, for example when one or more of the conditions (e.g., all of the conditions) (e.g. including additional conditions) are met.

[0117] A WTRU may receive a configuration of LTM candidate cells, for example a conditional LTM configuration. A (e.g., conditional LTM) configuration may include a L1 condition, for example based on L1 measurements and/or an associated L3 condition, for example based on L3 filtered measurements. A L1 measurement condition may be based on one or more of an RSRP threshold (e.g. SSB and/or CSI-RS measurement), acquisition/availability of WTRU-based TA measurement, one or more L1 filtered beam measurements, one or more beam stability measurements (e.g., number of beam failure indication(s) (BFI) within a time window at target is better than source), and/or a counter and sliding window (e.g. number of times beam goes above a threshold within a certain time). An L3 condition may re-use existing L3 events. Additionally, or alternatively, the L3 condition may use filtered beam measurement(s) and/or cell quality measurement(s) derived from one or more beam measurements, and/or set a threshold relative to highest beam measurement (e.g., if L3 filtered measurement is above a threshold of X dB from the beam measurement meeting the L1 condition).

[0118] A WTRU may perform (e.g., measure) and/or evaluate L1 and/or L3 measurements on a configured target. When a first condition is met for example, an L1 report may be triggered, for example using one or more of a MAC CE, CSI report, SR, and/or another L1 reporting mechanism. For example, a L1 beam may go above a threshold X times (e.g., SSB and/or CSI-RS measurement). The WTRU may have acquired a TA using WTRU-based measurement, beam RSRP, and/or beam stability, for example above a threshold. The WTRU may perform a beam stability comparison of source and target. Additionally, or alternatively, a L3 criteria may be met (e.g. lower threshold) and (e.g., then) set parameters and/or evaluate a L1 beam trigger.

[0119] A WTRU may receive an indication to dynamically modify the C-LTM parameters, for example using a MAC CE. The WTRU may receive a validity time, an updated threshold, a CG resource indication, a counter value, a window size, a target beam, and/or a beam stability target. Additionally, or alternatively, the WTRU may autonomously adjust the C-LTM evaluation. For example, the WTRU may be configured to set a threshold for the L3 criteria relative and/or scaled according to a metric obtained by performing L1 evaluation. The threshold for the L3 condition may be increased, for example if the WTRU detects a higher value of beam failure indications on the target with a certain time (e.g., to ensure stability of the cell measurement).

[0120] When a first condition and/or second condition is met for example, LTM may be triggered. For example, a filtered measurement may be above a relative threshold and a L1 condition may be met. LTM may be triggered within a time limit from the first condition being met (e.g., and report sent). The WTRU may trigger a second report to source (e.g, instead of triggering LTM), for example if the condition is not met within a specific time (e.g. CG valid time). The WTRU may send an indication to a target. The WTRU may include trigger details, for example in the indication. The trigger details may include one or more of a relative threshold setting, timing of trigger occurrences, counters (e.g. BFI count), and/or measurements (e.g. RSRP when TA was acquired)

[0121] LTM may be performed. Herein, perform LTM and/or perform LTM procedures may refer to performing any or of the steps, for example described in FIG.4. There may be early synchronization in DL and/or UL to one or more of the candidate cells. L1 measurements and reporting on one or more of the candidate cells may be performed. Additionally, or alternatively, switching (e.g, performing handover) between candidate cells may be performed. Performing LTM as herein may refer to the WTRU moving and/or switching between multiple candidate cells during the procedure.

[0122] There may be one or more candidate cell sets. The one or more candidate cell sets may include groups of more than one RRC configuration, for example corresponding to a handover configuration for one or more candidate SpCells and/or SCells. The RRC configuration 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. The candidate cell configurations (e.g., each) may include a candidate configuration identifier, and/or (e.g., 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. The serving cell indexes and/or candidate configuration indexes may be used in L1 and/or MAC signaling, for example to refer to specific indexes. For example a MAC CE triggering the reconfiguration may include a candidate configuration index informing the WTRU which cell to perform the reconfiguration to.

[0123] 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, for example rather than the configuration phase. For example, the candidate cell set may be considered as a single group in an RRC configuration list and/or group. Additionally, or alternatively, the cells selected for performing early sync, L1 measurements, and/or LTM execution may depend on a further grouping into multiple subsets of the overall candidate cell list. In some examples the grouping 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.

[0124] References to an LTM candidate configuration herein may apply to any type of preconfigured cell information. For example, a WTRU may be configured with one or more conditional reconfigurations. Example conditional reconfigurations may include one or more of conditional handover (CHO), conditional PSCell addition (CPA), and/or conditional PSCell change (CPC) which may be valid before and/or after a cell change, and/or valid in certain cells.

[0125] There may be L1 measurements. An L1 measurement herein may include a measurement of one or more of RSRP and/or RSSI, etc., for example performed by a WTRU of one or more of a cell, beam, set of cells, and/or set of beams. An L1 measurement may be similar to L3 measurements reported in RRM, for example with differences in one or more of the filtering, reference signals measured, and/or reporting mechanisms, etc. [0126] L1 measurement(s) may apply to RRM reporting. Herein measurements may refer to L1 measurements for LTM. Solutions herein may additionally, or alternatively, apply to RRM/L3 measurements. Solutions herein may additionally, or alternatively, apply to other measurements, for example one or more of speed, location, height, and/or traffic, etc.

[0127] An LTM cell switch may apply to any type of handover (HO) execution. Herein, the LTM cell switch may refer to L1/L2 triggered mobility, for example whereby a preconfigured RRC configuration is applied when the WTRU receives an indication using MAC CE and/or when a certain condition is met at the WTRU. Solutions herein may additionally, or alternatively, apply to one or more of an RRC reconfiguration, an RRC conditional reconfiguration, and/or any other type of mobility procedure.

[0128] The solutions described herein may provide improved mobility robustness (e.g. improve radio link failure (RLF)Zhandover failure (HOF) rates), for example by ensuring a mobility candidate/target has a stable measurement. LTM may offer improved interruption and/or latency over L3 mobility, for example by enabling a faster evaluation of target suitability and/or stability. Systems and methods may reduce resource overhead in the uplink compared to LTM, for example without event triggered L1 reporting and/or conditional LTM by enabling reduced L1 reporting to support mobility. In some examples the network resource efficiency may be improved, for example as resources may not be reserved on all of the potential candidate cells/beams until the WTRU indicates that a conditional mobility trigger is likely.

[0129] There may be an LTM candidate configuration. The gNB (e.g. a CU for a CU/DU split architecture) may configure (e.g., potential) LTM candidates using RRC signaling. RRC may reside in CU. The WTRU may receive the LTM candidate configurations using an RRC reconfiguration message, for example during an LTM preparation phase (e.g., as in FIG. 4). The WTRU may store the LTM candidate configurations to later apply, for example upon receiving an indication using L1/L2 signaling (e.g. MAC CE) to perform a cell switch (e.g., in the LTM execution phase of FIG. 4).

[0130] The configuration of potential LTM candidates may include one or more candidate sets. A first set may be suitable for a first path (e.g., a WTRU turns left and takes a first road) and/or a second set which may be suitable for a second path (e.g. WTRU turns right and takes a second road).

[0131] Candidate set information may be broadcast in system information. Additionally, or alternatively, the WTRU may enable pre-configuration of broadcast configurations, for example upon receiving an indication in dedicated signalling (e.g. RRC Reconfiguration). The indication may refer to the broadcast one or more configurations (e.g. using an index and/or identifier). [0132] The configuration may include all or a subset of (e.g., potential) candidate cells, for example 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). The cells may not yet have been detected and/or measured by the WTRU, but for example may be configured in advance. After the initial configuration of LTM candidate configurations for example, the WTRU may receive an update to the configuration to modify, add, remove, and/or replace any part of the LTM candidate configuration(s).

[0133] The WTRU may receive an indication to enable or disable one or more 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 disabled LTM configuration may be re-enabled).

[0134] The configuration may be based on a prediction model, for example internal to and/or determined by the network (e.g. gNB). The prediction may, for example, be based on what it (e.g., the network (NW) prediction model) determines to be the WTRUs most likely path(s).

[0135] The candidate cell configurations may contain all or part of the information (e.g., necessary) to complete a reconfiguration (e.g. handover) to the candidate cell. Example information may include one or more of channel configurations (e.g. PRACH, DPCCH, and/or DPSCH), CORESET, BWP, security parameters, L2 parameters (e.g. MAC, RLC, PDCP), and/or radio bearer configurations, etc.

[0136] There may be an LTM execution trigger. LTM execution trigger herein may refer to a condition for performing LTM (e.g. a conditional handover trigger or measurement report trigger). The condition for performing LTM may be (e.g., either) configured and/or indicated by the network to the WTRU. Additionally, or alternatively, the condition for performing LTM may be estimated and/or determined by the WTRU.

[0137] A trigger may be based on time, for example an absolute or relative time measured time at WTRU, a SFN, and/or subframe number. The trigger may be based on radio quality measurement(s) and/or predicted radio quality one or more of the serving cells or target cells (e.g., RSRP (beam or cell), RSRQ (beam or cell), cri-RI-PMI-channel quality indicator (CQI), cri-RI-i1 , cri-RI-i1 -CQI, cri-RI-CQI, cri-RSRP, ssb- Index-RSRP, and/or cri-RI-LI-PM I -CQI) . The trigger may be based on a position of the WTRU, for example an area (e.g. defined by reference point and radius). The trigger may be based on a range of coordinates, and/or a distance threshold from a reference location.

[0138] The trigger may be based on a (e.g., any) L3 measurement event. For example the L3 measurement event may include one or more of Event A1 (e.g., serving becomes better than threshold), Event A2 (e.g., serving becomes worse than threshold), Event A3 (e.g., neighbor becomes offset better than SpCell), Event A4 (e.g., neighbor becomes better than threshold), Event A5 (e.g., SpCell becomes worse than thresholdl and neighbor becomes better than threshold2), Event A6 (e.g., neighbour becomes offset better than SCell), Event B1 (e.g., inter RAT neighbour becomes better than threshold), and/or Event B2 (e.g., PCell becomes worse than thresholdl and inter RAT neighbor becomes better than threshold2). [0139] The trigger may be based on a (e.g., any) L1 measurement event and/or condition (e.g., any event defined which utilizes L1 beam measurements to evaluate whether a criteria or condition is met). The trigger may be based on a (e.g., any) predicted event (e.g., using any of the measurement quantities herein), an explicit indication from the network (e.g., the WTRU may enable CSI reporting based on an explicit indication (e.g. a MAC CE) received from the network, and/or (e.g., then) execute LTM cell switch upon receiving a second MAC CE from the network). The trigger may be based on a measured, predicted, and/or estimated throughput. The trigger may be based on a measured, predicted, and/or estimated error rate; a measured, predicted, and/or estimated buffer status; a measured, predicted, and/or estimated quality of service (QoS) parameter; an evaluation metric (e.g., a time-to-trigger, a hysteresis, offset (e.g. a radio quality measurement offset), and/or a measurement filtering configuration). A trigger as herein may be based on a combination of disclosed triggers (e.g., bases).

[0140] The trigger may include one or more conditions under which the WTRU is configured to perform any action related to LTM. For example, the WTRU may perform one or more of early TA acquisition, switching off CSI reporting, switching on and/or updating the CSI reporting configuration, performing LTM cell switch, monitoring PDCCH on a target cell, performing beam failure recovery (BFR) and/or radio link monitoring (RLM) on a target cell, and/or activating and/or deactivating (e.g., certain) SCells.

[0141] The one or more conditions may include early TA acquisition. The WTRU may trigger a RACH to a target LTM cell. The WTRU may receive a TA value in a random access response (RAR). The RAR may be sent from a target cell and/or via a source cell. The WTRU may receive a TA value, for example in a MAC CE, triggering the cell switch. The WTRU may perform power ramping and/or preamble retransmission on the target, for example if a RAR I MAC CE is not received. The WTRU may acquire the TA value of a candidate LTM cell by measurement, and/or a trigger when complete. The WTRU may support and/or be configured with a WTRU-based TA measurement. For example the WTRU may acquire the TA value(s) of the candidate cell(s) by measurement.

[0142] The one or more conditions may include switching off CSI reporting. The WTRU may be allowed and/or configured to switch off CSI reporting, for example in order to reduce reporting overhead in the uplink. The CSI reporting may be reduced rather than switched off in some examples. For example, a number of cells or beams reporting may be reduced, and/or a frequency of reporting may be reduced. The WTRU may resume CSI reporting, for example when the condition is no longer met.

[0143] The one or more conditions may include switching on and/or updating the CSI reporting configuration. The WTRU may be configured to perform and/or report CSI measurements on one and/or a subset of LTM candidate cells, for example during the window. The one or more conditions may include performing LTM cell switch. There may be conditions and/or criteria under which the WTRU is configured (e.g., allowed) to trigger LTM cell switch.

[0144] The one or more conditions may include monitoring PDCCH on a target cell. The WTRU may be configured to monitor on a target cell for a DCI scheduling PDSCH and/or indicate one or more actions on the target cell, for example to initiate the cell switch procedure. The one or more conditions may include performing BFR and/or RLM on a target cell. The WTRU may be configured to monitor for beam failure detection (BFD) resources on a target cell, and/or perform RLM (radio link monitoring) on a target cell, for example during the window. The one or more conditions may include activating and/or deactivating (e.g., certain) SCells. The WTRU may be configured with one or more specific SCells which, for example should be active or not active during the window.

[0145] There may be RACH-less CHO and/or early TA acquisition. The WTRU may perform an early TA acquisition procedure with candidate cell(s), for example before receiving the cell switch command and/or before triggering a conditional reconfiguration. The WTRU may perform an early TA acquisition procedure with candidate cell(s) before receiving the cell switch command and/or before triggering a conditional, for example to enable RACH-less conditional handover. Additionally, or alternatively, the WTRU may not need to send a random access preamble and/or perform a random access procedure on the target cell following a reconfiguration trigger. For example the WTRU may perform PDCCH reception and/or uplink transmission using the TA (e.g., already) provided reconfiguration.

[0146] Early TA acquisition may be performed using contention-free random access (CFRA), for example triggered by a PDCCH order from the source cell. The WTRU may (e.g., then) send a preamble to a candidate cell. The information that identifies the allocated CFRA resource may be indicated in the PDCCH order, for example to enable shared preamble resource among multiple WTRUs in the RRC configuration. The source gNB may (e.g., dynamically) indicate which WTRU uses and/or may use the resource at any specific time. The network (e.g., gNB) may indicate which WTRU uses and/or may use the resource at any specific time upon receiving a MAC CE indicating to perform a RACH transmission on a target cell. In some examples, the network (e.g., gNB) may indicate which WTRU uses and/or may use the resource at any specific time may be performed by transmitting using a contention-based random access (CBRA) preamble.

[0147] For example in order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the WTRU may not receive RAR (e.g., at all). A source cell may trigger a preamble retransmission and/or power ramping using another PDCCH order, for example if the preamble was not received. The TA may be provided from the target cell to the source cell (e.g., in this case). Additionally, or alternatively, the TA may be provided to the WTRU in a MAC CE triggering cell switch and/or an enabling conditional LTM to one or more target cells. In some examples the WTRU may receive a TA value from the target cell in a RAR. The WTRU may receive a TA value from the source cell in a RAR. If the WTRU does not receive a RAR in response to transmitting the preamble for example (e.g. within a prescribed time), the WTRU may retransmit a preamble using a higher transmission power.

[0148] The WTRU may store the received TA value, for example to be used later when a reconfigure trigger occurs. The WTRU may store the TA value for a limited period of time (e.g. a validity timer) and/or may trigger and/or be triggered to perform a new TA acquisition procedure when the time expires. In some examples the WTRU may receive and/or store multiple TA values associated with more than one cell. In some examples the WTRU may obtain the TA value of the target cell by measurement. If the WTRU has stored a valid TA value of a candidate cell when a cell switch is triggered towards that candidate cell for example (e.g., either triggered by the NW using an explicit cell switch command, or triggered by the WTRU upon meeting a trigger condition), (e.g., then) the WTRU may perform a RACH-less handover. For example, the WTRU may execute LTM (e.g. apply a pre-configured RRC configuration to a new SpCell) upon determining that a measured radio quality of the target cell is above a threshold. The WTRU may support and/or be configured with WTRU-based TA measurement. The WTRU may acquire the TA value(s) of the candidate cell (s) by measurement. If the cell switch command does not contain a TA value and/or the WTRU has acquired a TA measurement for example, the WTRU may perform a RACH-less handover (e.g., if it has been configured to do so by RRC).

[0149] There may be TA validity. A WTRU may determine a received and/or stored TA to be valid, for example based on one or more of a validity timer pre-configured to be used with TA value, a validity timer received with the TA value, a condition on the DL cell timing of the source cell and/or the DL cell timing of the candidate cell for which TA is received/stored, a condition on the DL cell timing of the candidate cell, a condition on the WTRU mobility, a condition on the WTRU location, and/or a condition that a WTRU-based TA measurement is available and/or a cell quality or beam quality measurement is above a threshold.

[0150] A WTRU may determine a received and/or stored TA to be valid, for example based on a condition on the DL cell timing of the source cell and/or the DL cell timing of the candidate cell for which TA is received/stored. A WTRU may determine (e.g., consider) the TA to be valid, for example when the difference of the DL cell timing of the source and candidate cell is less than a configured threshold. A WTRU may determine (e.g., consider) the TA to be valid, for example when the difference of the DL cell timing of the source and candidate cell is within a configured range.

[0151] A WTRU may determine a received and/or stored TA to be valid based on the DL cell timing of the candidate cell. A WTRU may determine (e.g., consider) the TA to be valid if the difference of the DL cell timing of the target cell at the time of the TA reception is not different by more than a certain configured value/range than the current DL cell timing of the same target cell. A WTRU may determine a received and/or stored TA to be valid based on a condition on the WTRU mobility. A WTRU may determine (e.g., consider) the TA to be valid if it is static (e.g., not moving) and/or moving below a certain configured speed threshold. A WTRU may determine a received and/or stored TA to be valid based on a condition on the WTRU location. A WTRU may determine (e.g., consider) the TA to be valid if the WTRU has determined that the WTRU has not changed location by more than a certain configured threshold (e.g., x meters), for example after the TA acquisition.

[0152] FIG. 5 shows an example of beam refinement 500. Beam refinement may be in NR for example. A WTRU may measure SSBs before and/or during initial access. For example, the WTRU may perform measurements on SSB1, SSB2, and/or SSB3. The WTRU may indicate SSBs, for example by selecting a random access resource corresponding to the best measured SSB, to the gNB. The beam may be (e.g., further) refined once the WTRU is in RRC_CONNECTED, for example by configuring the WTRU to measure a set of CSI-RS and reporting the measurements (e.g. the best CSI-RS index / CRI index or indicating the RSRP). An SSB resource may be transmitted by the gNB using a wider beam and/or multiple CSI-RS resources may be transmitted using a narrower beam. The beam may be refined using the wider SSB beam (e.g., first), and/or (e.g., then) selecting one of multiple narrower CSI-RS beams (e.g., afterwards).

[0153] There may be beam refinement on a target cell before and/or during HO. The WTRU may perform beam refinement on a target cell before and/or during a handover, and/or before the WTRU accesses the target cell. For example, a WTRU first performs measurement of SSB resources, then selects a subset of CSI-RS resources to measure based on the SSB measurements (e.g. based on the best SSB measured). The WTRU may (e.g., then) perform measurements on the selected subset of CSI-RS resource and/or determine a best CSI-RS resource. The selected best CSI-RS resource can be indicated before a handover takes place (e.g. to a source cell) and/or upon initial access (e.g. to a target cell), for example rather than performing the beam refinement only after a connection to a target cell is completed.

[0154] A WTRU may report CSI-RS measurements. For example, the WTRU may report SCI0RS6, CSI- RS 7, CSI-RS 8, CSI-RS 9, and/or CSI-RS 10. The WTRU may report the measurements of the subset of CSI-RS resources, for example using CSI reporting on PUCCH to the source cell. The report may alternatively, or additionally, be transmitted using a MAC CE and/or an RRC measurement report, and/or any other type of uplink signaling. The report may contain one or more of RSRP (e.g., beam and/or cell), RSRQ (e.g., beam and/or cell), cri-RI-PMI-CQI, cri-RI-l, cri-RI-i1-CQI, cri-RI-CQI, cri-RSRP, ssb-lndex- RSRP, and/or cri-RI-LI-PMI-CQI.

[0155] CSI-RS measurements may be enabled. The WTRU may determine, for example based on a trigger, a subset of CSI-RS to measure. For example, the WTRU may determine based on a pre-configured association (e.g. configured by RRC) between SSB and CSI-RS resources. The WTRU may determine the subset of CSI-RS to measure based on an indication of an SSB and/or determine a best SSB from performed SSB measurements. The subset of CSI-RS may be indicated (e.g., explicitly) in a random access response (e.g. using a pointer to one of multiple subsets) and/or may be indicated implicitly (e.g., the WTRU enables a subset of CSI-RS depending on a reported or indicated SSB when the RAR is received).

[0156] The WTRU may alternatively, or additionally, enable the subset of CSI-RS measurements when the WTRU receives a PDCCH order triggering early TA acquisition. The RAR and/or MAC CE containing a TA in response to the PRACH preamble transmission for TA acquisition may activate the configured grant. The CSI-RS measurements may be configured temporarily. For example, the WTRU may activate CSI-RS measurements for a certain time period, and/or a certain number of reports. The time period and/or the number of reports may be configured and/or predefined. The WTRU may deactivate CSI-RS measurements, for example when a best SSB changes and/or when an SSB and/or CSI-RS measurement goes below a threshold.

[0157] There may be configured grant activation. The WTRU may receive an indication to activate a grant, for example from (e.g., either) a source and/or a target cell. The indication and/or the grant may include one or more of a type 2 configured grant (e.g., where the first cell may configure the grant and/or the second cell may activate the grant), an explicit grant (e.g., a direct indication of the grant to use), and/or a pointer to one or more preconfigured grants (e.g., previously configured by RRC). An indication of the grant may include a pointer to a configured grant, for example corresponding to a reported SSB. The indication of the grant may include an indication of a set of configured grants, for example corresponding to multiple CSI-RS associated with a reported SSB. The configured grant activation may be received in one or more of a PDCCH order (e.g. triggering TA acquisition), in a MAC CE (e.g. triggering LTM), and/or in a RAR (e.g. received from the source or the target, containing a TA value to use for RACH-less handover). The WTRU may (e.g., autonomously) activate a configured grant, for example based on a condition. For example, the WTRU may activate a grant based on any of the LTM execution triggers described herein.

[0158] There may be a WTRU based calculation report. The WTRU may trigger an event, for example when a WTRU-based TA acquisition has been completed. The WTRU may transmit a one or more of MAC CR, CSI, and/or other uplink indication to the source cell and/or the candidate cell, for example when a TA has been obtained based on WTRU measurement.

[0159] The WTRU may trigger an event based on measurement criteria (e.g. RSRP or any of the other triggers herein) and/or may send the corresponding report (e.g., only) for example if a TA has (e.g., additionally) been obtained. ATA may be obtained and/or available due to a prior WTRU-based TA acquisition. A report and/or an LTM execution trigger caused due to a measurement-based event and/or trigger may be delayed until a WTRU-based TA acquisition is completed. A measurement event (e.g. a beam RSRP is above a threshold) may cause the WTRU to initiate a WTRU-based TA acquisition. A trigger may (e.g., then) be executed, for example when (e.g., both) the measurement event may be satisfied and/or the TA may be obtained.

[0160] In response to receiving a report from the WTRU (e.g. WTRU-based TA acquisition has been performed and/or a beam or cell measurement is above a threshold) for example, the network may transmit to the WTRU a command to enable conditional LTM evaluation. The network may transmit the command to enable conditional LTM evaluation in a MAC CE. The WTRU may receive the command and/or (e.g., then) enable conditional LTM evaluation. Additionally, or alternatively, the WTRU may enable conditional LTM evaluation based on the content of the command, for example based on determination of one or more measurement conditions.

[0161] There may be beam stability. The WTRU may determine a beam stability evaluation on one or more target/candidate cells or beams, and/or on the source/serving cell. For example, BFD may be enabled on beams belonging to a candidate cell. Additionally, or alternatively, the WTRU may consider metrics related to the BFD monitoring when determining whether to trigger a report and/or to trigger an LTM execution. The WTRU may monitor the beam stability on one or more targets, for example while evaluating conditional LTM trigger. The WTRU may (e.g., then) select the most stable target, for example based on beam stability evaluation. The WTRU may abort an ongoing conditional LTM reconfiguration and/or execution. The WTRU may select a different cell (e.g., including in some solutions, the source cell), for example when the target cell beam stability is below a threshold.

[0162] The beam stability determination may cause the WTRU to perform different actions. If the beam stability of a selected target cell is below a threshold for example, the WTRU may perform LTM based on meeting the trigger criteria. The WTRU may perform a different procedure if the beam stability is above a threshold. For example, the WTRU may use a higher initial transmission power, use more PDU repetitions, use a different hybrid automatic repeat request (HARQ) mode of transmission, and/or use a different random access procedure (e.g. 2 step or 4 step random access channel (RACH), RACH-less), for example if the beam stability is above a threshold.

[0163] The WTRU may compare beam stability of the source/serving cell and/or beam with the target cell and/or beam. Based on the relative beam stability between source and target for example, the WTRU may apply different conditions. For example if the beam stability on the source is better than the target, then a higher RSRP threshold for triggering LTM may be used. If the beam stability is better on the target for example, (e.g., then) a lower RSRP threshold may be used. In some example, the WTRU may (e.g., therefore) determine a best cell which may have a lower cell quality measurement, for example based on the beam stability being better than a cell with a higher cell quality measurement.

[0164] Beam stability determination may be based on one or more of beam change statistics (e.g., how often the best beam changes on a cell, for example within a certain time), BFI counting (e.g., the number of BFIs detected within a certain time), BFD counting (e.g., the number of BFIs detected within a certain time), rate of change and/or variance of individual beam measurements (e.g. what is the range in dB of the best and/or worst beam measurement within a certain time), and/or a number of beams above a threshold.

[0165] The WTRU may report information regarding the beam stability of one or more target cells and/or beams to the source cell, and/or to the target cell, for example in a MAC CE and/or CSI report. The information may, for example, be used by the network to improve radio resource management (RRM) parameters and/or performance, and/or to train artificial intelligence (Al) models. In some examples, the reporting may be performed (e.g., only) after certain conditions are met, for example (e.g., only) when the beam stability meets certain criteria. The beam stability information may be reported to the target, for example if a problem is detected on the target during evaluation. In some examples the beam stability information may be reported to the target, for example if problems are detected on the source, and/or if an LTM execution to a target is successful.

[0166] There may be an L1 event. To support explicit LTM (e.g. use of a MAC CE to explicitly indicate cell change) and/or conditional LTM (e.g. WTRU evaluated condition for triggering cell change), event triggered L1 measurements may be defined. There may be periodic and/or aperiodic L1 reporting (e.g. using CSI reporting). Additionally, or alternatively, L3 measurement reporting may support periodic and/or event- triggered reporting. The WTRU may report using an RRC measurement report, for example if a preconfigured event criteria (e.g. A3, A4, and/or etc.) is determined to have been met. The pre-configured event criteria may be determined to have been met based on L3 filtered measurements (e.g. cell or beam measurements).

[0167] Due to the associated delays with L3 filtering of measurements and/or transmission of an RRC report for example, event triggered L1 reports are disclosed herein. The L1 report may be conveyed in a CSI report and/or other report on PUCCH, and/or may be conveyed using a MAC CE and/or other upper layer signaling method. The L1 measurement evaluation may use unfiltered beam measurements at L1. Additionally, or alternatively, a new filtering approach may be defined, for example at L1 , in MAC, and/or in RRC (e.g. RRC, using shorter and/or quicker filtering than is currently defined). New event triggering criteria may be used and/or L3 defined events may be modified to support faster triggering and/or alternative triggering conditions, for example based on L1 measurements.

[0168] The L1 trigger may be evaluated on one or more of SSB measurements, CSI-RS measurements, and/or a combination of measurements on both types of resource. For example, an average measurement may be derived using one or more SSB and/or CSI-RS measurements. Additionally, or alternatively to using a time-to-trigger (TTT), a counter and/or time window may be used. The TTT may specify a minimum amount of time for which a condition must be met before triggering an event. L1 beam measurements which, for example are unfiltered and/or are using shorter filtering times than L3 measurements, may be more unstable and/or fluctuate more rapidly than a longer-term filtered measurement. The number of times a L1 measurement meets a criteria within a certain time (e.g., in this case) may be counted, for example rather than meeting a condition (e.g., continuously) for a certain duration (e.g., as with TTT).

[0169] A beam quality measurement may be compared to an absolute and/or relative threshold. If the measurement goes above this threshold N times within a time X for example, then the event may be triggered. The relative beam quality of a source cell and/or one or more beams on a source cell may be compared to a target cell and/or one or more beams on a target cell. If the target cell is determined to be better than the source cell (e.g. including an offset or hysteresis - e.g. source measurement + offset/hysteresis < target measurement) for N times within a time X for example, (e.g., then) the event may be triggered. In some examples, the L1 event may be triggered if more than one condition is met. The condition may include a target beam/cell measurement above a threshold and/or a source measurement below a threshold. The condition may include a cell/beam quality criteria being met and/or a WTRU having acquired a TA value for the target cell using WTRU-based TA acquisition. The condition may include a time and/or distance criteria being met (e.g. event D1, D2, and/or T1) and/or a cell/beam quality criteria being satisfied. The condition may include an L1 beam measurement criteria being met and/or a L3 filtered beam/cell measurement criteria being met. Any combination of one or more criteria as herein may be used. [0170] There may be adaptive and/or combined measurement criteria. The WTRU may be configured with more than one measurement, measurement criteria, and/or measurement condition, for example to be used when determining the trigger for conditional LTM. For example, the conditional LTM trigger may use a L3 based condition (e.g. measurement event) and/or L1 based condition. In some example both conditions may be met for the WTRU to trigger the LTM. For example, a L3 event (e.g. event A3 and/or any of the other existing event types) may be met using a cell quality measurement (e.g. longer term L3 filtered).

Additionally, or alternatively, an L1 beam measurement criteria may be met (e.g., short-term condition using new L1 events).

[0171] In some examples, the outcome or result of one of a first and/or second measurement types may affect the operation and/or evaluation of the other measurement type. For example a parameter used in the second type of measurement evaluation may be modified based on the outcome of the first measurement evaluation. A L1 beam measurement may meet a criteria, for example a beam RSRP (e.g., SSB and/or CSI-RS) measurement may exceed a threshold one or more times. Based on the beam measurement for example (e.g., the highest beam measurement within a time and/or an average beam measurement), a cell quality measurement threshold may be set. The cell quality measurement may be set as XdB below the beam measurement.

[0172] The WTRU may (e.g., then) check whether the current filtered cell quality is above the threshold. The check may not utilize a time-to-trigger, for example as the filtered cell quality may be derived from a current measurement and/or previous measurements (e.g. it is already averaged over time). If the cell quality measurement (e.g., also) meets the criteria for example, (e.g., then) the combined criteria may be met, and/or a measurement report and/or a conditional LTM may be triggered. The cell quality measurement may be used as a stability check, for example when the beam measurement criteria is met. The cell quality measurement may be used as a stability check, for example as the cell quality (e.g. L3) measurement may provide an indication of an average quality over time. Additionally, or alternatively, the cell quality measurement may provide a stability metric, for example while allowing for faster triggering based on L1 measurements without waiting for a time-to-trigger.

[0173] The conditional LTM trigger may be evaluated using multiple steps. For example, L3 cell and/or beam quality measurement may be monitored (e.g., first). When the L3 measurement meets a trigger criteria (e.g. above a threshold) for example, (e.g., then) the L1 criteria may be evaluated (e.g. with or without waiting for a time-to-trigger). If the L3 criteria continues to be met and/or the L1 criteria is (e.g., also) met (e.g. beam measurement above a threshold) for example, (e.g., then) the combined conditional LTM trigger condition may be determined to be met. For example when the L3 criteria is met, L1 trigger evaluation may be enabled to start. Using a combined criteria with separate L1 and L3 measurement for example, the criteria may be evaluated in sequence (e.g., L1 first, or L3 first), or in parallel/simultaneously. In some examples two types of measurement may be used for the first and/or second criteria, as described herein.

[0174] If a second measurement (e.g. L1) evaluation is enabled by a first (e.g. L3) criteria being met for example, a timer may be used to limit the amount of time the second criteria is evaluated. If the second criteria is met within that time specified by the timer for example, then a cell change (e.g., LTM) may be triggered. If the criteria is not met within the time specified by the timer for example, (e.g., then) a report may be triggered. The report may be sent to the source indicating that the second criteria (e.g. the L1 criteria) was not met, for example even though the first criteria (e.g. the L3 criteria) was met. Based on the first criteria being met for example, the second criteria may be evaluated. Additionally, or alternatively, based on the second criteria being met or not, the WTRU may be configured to (e.g., either) perform a cell change, and/or report to the source.

[0175] The first type of measurement may be used for selecting a target cell. The second type of measurement may be used for selecting a beam on the (e.g., selected) target cell. For example if the cell quality threshold is met using L3 measurements, the WTRU may select the best beam belonging to that target cell and/or any beam above a threshold on that target cell (e.g., to execute the conditional LTM). A prohibit timer may be used to prevent the WTRU from performing conditional cell switch (e.g., too frequently). For example upon executing a conditional cell switch, the WTRU may be configured not to trigger any further cell switch for the duration of a timer (e.g., even if the measurement criteria are met). The WTRU may be configured to perform measurement reporting (e.g. periodic CSI report to the source cell) while the prohibit timer is running and/or to (e.g., then) stop CSI reporting and/or perform a conditional LTM evaluation after the timer expires.

[0176] A time-to-trigger may be extended, for example after a conditional LTM is triggered. For example, a new target cell may meet a criteria for a certain TTT. If one cell switch occurred within X seconds from a new conditional LTM trigger being met for example, (e.g., then), the criteria may (e.g., need to) be met for TTT x 2 (e.g., or any configurable or fixed value - 1 .5, 3, etc.). The TTT used for conditional LTM may be scaled according to a beam stability metric. For example, a higher number of beam switches within a certain time may increase the TTT used for determining cell switch.

[0177] A mobility evaluation process may be selected, for example based on one measurement type. For example, one measurement event may be used in case a beam stability is below a certain threshold. A second measurement event may be used in case the beam stability is above a certain threshold. The selection may additionally, or alternatively, be performed based on one or more of speed, location, time, and/or any quality measurement and/or trigger described herein.

[0178] FIG. 6 shows an example 600 of network controlled conditional criteria modification of a second criteria based on report of a first criteria. A WTRU 602 may receive one or more of a configuration of LTM candidate cells and/or a conditional LTM configuration including a L1 condition based on L1 measurements and an associated L3 condition based on L3 filtered measurements. For example the WTRU 602 may receive an RRC reconfiguration message from Cell A 604 at 608. The WTRU 602 may send a RRC reconfiguration complete message to Cell A 604 at 610. The WTRU performs a first type measurements on a candidate LTM cell and/or evaluates a first measurement condition. For example, the WTRU may perform L1 beam measurements on beams (e.g. measurement resources such as SSB, CSI-RS) and/or evaluates based on a first criteria. The first criteria may be based on any of the examples provided herein (e.g. SSB/CSI-RS measurement meeting a threshold, WTRU acquisition of TA, beam stability, and/or etc.).

[0179] Based on the first criteria being met for example, the WTRU 602 may trigger a L1 report to indicate to the network the criteria being met. The L1 report may be transmitted in one or more of a MAC CE, and/or CSI report, etc. For example, the WTRU 602 may send the L1 report to Cell A 604 at 612. The WTRU 602 may (e.g., then) receive a command updating and/or enabling a second measurement type and/or criteria, for example a L3 cell quality criteria. The WTRU 602 may receive the command (e.g., MAC CE, C-LTM modification) at 614. If the first criteria continues to be met and/or the second criteria is met for example, (e. g . , then) the WTRU 602 may initiate and/or triggers an LTM cell switch. For example, the WTRU 602 may trigger the LTM cell switch to Cell B 606 at 616.

[0180] FIG. 7 shows an example 700 of WTRU autonomous conditional criteria modification of a second criteria based on report of a first criteria. A WTRU 702 may receive one or more of a configuration of LTM candidate cells, a conditional LTM configuration including a L1 condition based on L1 measurements and an associated L3 condition based on L3 filtered measurements. For example the WTRU 702 may receive a RRC reconfiguration message from Cell A 704 at 708. The WTRU 702 may send a RRC reconfiguration complete message to Cell A 704 at 710. The WTRU 702 may perform a first type measurements on a candidate LTM cell and/or evaluate a first measurement condition. For example, the WTRU 702 may perform L1 beam measurements on beams (e.g. measurement resources such as SSB, CSI-RS) and/or evaluate based on a first criteria. The first criteria may be based on any of the examples provided in herein (e.g. SSB/CSI-RS measurement meeting a threshold, WTRU acquisition of TA, beam stability, and/or etc.). [0181] Based on the first criteria being met the WTRU 702 may enable a second measurement type and/or criteria, for example a L3 cell quality criteria. For example, Cell B 706 may send a message including Cell B measurement and/or evaluation information to the WTRU 702 at 712. If the first criteria continues to be met and/or the second criteria is met for example, (e.g., then) the WTRU 702 may initiate and/or triggers an LTM cell switch. Cell B 706 may send a message including (e.g., an update to) Cell B measurement and/or evaluation information to the WTRU 702 at 714. The WTRU 702 may trigger the LTM cell switch to Cell B 706 at 716.

[0182] The first measurements may be cell quality measurements (e.g., L3 cell quality). Example (e.g., L3) cell quality measurements may include RSRP, reference signal received quality (RSRQ), signal to interference noise ration (SI NR), and/or RSSI. When a target cell meets a first criteria (e.g. target cell is above a threshold) for example, (e.g, then) the WTRU may autonomously enable L1 beam measurements on the target cell. For example the WTRU may select a subset of the configured L1 beams associated with the target cell based on beams selected during L3 beam selection for cell quality derivation. The WTRU may perform measurements on the selected target cell beams and/or evaluate the LTM trigger, for example based on the cell quality remaining above the threshold and/or a beam quality meeting a L1 trigger condition. The L3 threshold may be set to a relatively low value, for example to ensure a minimum measurement stability. The threshold may be lower than a threshold configured to support L3 handover, such that for example the target cell quality (e.g, alone) may not be enough indication to trigger a handover. When combined with the L1 measurement trigger for example, the L3 quality may provide an indication of stability. The L1 measurement may provide an indicator of high enough beam quality to trigger LTM.

[0183] FIG. 8 shows an example 800 of L1 triggered beam stability report for explicit LTM. A WTRU 802 may receive a configuration of LTM candidate cells and/or an event triggered L1 measurement report configuration. For example the WTRU 802 may receive a RRC reconfiguration from Cell A 804 at 808. The WTRU 802 may send a RRC reconfiguration complete message to Cell A 804 at 810. The event triggered L1 measurement may use any of the conditions detailed herein, for example a beam stability measurement. The WTRU 802 may perform the L1 based measurement on a target one or more cells and/or beams, for example as herein. When the criteria is met for example, a report may be transmitted to the network (e.g. , using a MAC CE and/or CSI report).

[0184] Based on the first criteria being met the WTRU 802 may enable a second measurement type and/or criteria, for example a L3 cell quality criteria. For example, Cell B 806 may send a message including Cell B measurement and/or evaluation information to the WTRU 802 at 812. The WTRU 802 may transmit a L1 measurement report to Cell A at 814. The WTRU 802 may receive a MAC CE and/or C-LTM modification at 814. If the first criteria continues to be met and/or the second criteria is met for example, (e.g., then) the WTRU 802 may initiate and/or triggers an LTM cell switch. Additionally, or alternatively, the WTRU may receive an LTM trigger, for example in a MAC CE from Cell A 804, at 816. The WTRU 802 may trigger the LTM cell switch to Cell B 806 at 816.

[0185] FIG. 9 is an example 900 of WTRU based TA measurement report for (e.g., conditional and/or explicit) LTM preparation. A WTRU 902 may receive a configuration of LTM candidate cells and/or an event triggered L1 measurement report configuration. The WTRU 902 may additionally, or alternatively, receive a conditional LTM configuration. For example, the WTRU 902 may receive a RRC reconfiguration message from Cell A at 904. The WTRU 902 may send a RRC reconfiguration complete message to Cell A 904 at 910. The event triggered L1 measurement may use any of the conditions detailed herein, for example a beam stability measurement. The WTRU 902 additionally, or alternatively, may receive a configuration to perform WTRU-based TA acquisition. The WTRU 902 may perform the L1 based measurement on a target one or more cells and/or beams, for example as detailed herein.

[0186] Based on the first criteria being met the WTRU 902 may enable a second measurement type and/or criteria, for example a L3 cell quality criteria. For example, Cell B 906 may send a message including Cell B measurement and/or evaluation information to the WTRU 902 at 912. The WTRU 902 additionally or alternatively may perform TA acquisition on the target cells. When the WTRU 902 successfully acquires the TA value from the target cell and/or when one or more criteria are met for example, the WTRU 902 may trigger the L1 report to the source cell. For example the WTRU 902 may send the L1 report to Cell A 904 at 914. The WTRU may (e.g., then) receive an explicit LTM trigger and/or a trigger to perform conditional LTM trigger evaluation. For example, the WTRU 902 may receive the LTM trigger from Cell A 904 at 916. The WTRU 902 may trigger the LTM cell switch to Cell B 906 at 918.

Claims

CLAIMS:

1 . A wireless transmit/receive unit (WTRU) comprising: a processor, the processor configured to: receive first configuration information comprising an indication of a first condition associated with one or more candidate layer triggered mobility (LTM) cells; determine that the first condition is satisfied; receive second configuration information comprising an indication of a second condition associated with the one or more candidate LTM cells; determine that the second condition is satisfied; and send, based on the determination that the second condition is satisfied, an indication of a selected cell of the one or more candidate LTM cells.

2. The WTRU of claim 1 , wherein the first condition comprises a layer 1 condition, and wherein the processor is configured to: perform a layer 1 measurement associated with the one or more candidate LTM cells, and compare the layer 1 measurement with the layer 1 condition.

3. The WTRU of claim 2, wherein the layer 1 measurement comprises one or more of a reference signal received power (RSRP) or a received signal strength indicator (RSSI) associated with one or more of a cell or a beam.

4. The WTRU of claim 2, wherein the layer 1 measurement comprises a first layer 1 measurement and the layer 1 condition comprises a first layer 1 condition, and wherein the processor is configured to: perform a second layer 1 measurement associated with the one or more candidate LTM cells, and compare the second layer 1 measurement with a second layer 1 condition; and determine that the first condition is satisfied based on the comparison of the first layer 1 measurement to the first layer 1 condition and on the comparison of the second layer 1 measurement to the second layer 1 condition.

5. The WTRU of claim 2, wherein the layer 1 condition comprises a threshold associated with one or more of a system information block (SSB) value, a channel state information (CSI)-reference signal (RS) value, a timing advance (TA) value, or a beam stability value.

6. The WTRU of claim 1 , wherein the second condition comprises a layer 3 condition, and wherein the processor is configured to: perform a layer 3 measurement associated with the one or more candidate LTM cells, and compare the layer 3 measurement with the layer 3 condition.

7. The WTRU of claim 6, wherein the layer 3 measurement comprises a filtered measurement associated with one or more of a cell or a beam.

8. The WTRU of claim 1 , wherein the processor is configured to determine that the first condition is satisfied subsequent to receiving the second configuration information.

9. The WTRU of claim 1 , wherein the processor is configured to send the indication to select a cell of the one or more candidate LTM cells based on a time limit subsequent to the determination that the first condition is satisfied.

10. The WTRU of claim 1 , wherein the processor is configured to: receive an indication to modify the first condition; modify the first condition based on the indication; and determine that the first condition is satisfied based on the modification of the first condition.

11. A method performed by a wireless transmit/receive unit (WTRU), the method comprising: receiving first configuration information comprising an indication of a first condition associated with one or more candidate layer triggered mobility (LTM) cells; determining that the first condition is satisfied; receiving second configuration information comprising an indication of a second condition associated with the one or more candidate LTM cells; determining that the second condition is satisfied; and sending, based on the determination that the second condition is satisfied, an indication of a selected cell of the one or more candidate LTM cells.

12. The method of claim 11 , wherein the first condition comprises a layer 1 condition, and wherein the method comprises: performing a layer 1 measurement associated with the one or more candidate LTM cells, and comparing the layer 1 measurement with the layer 1 condition.

13. The method of claim 12, wherein the layer 1 measurement comprises one or more of a reference signal received power (RSRP) or a received signal strength indicator (RSSI) associated with one or more of a cell or a beam.

14. The method of claim 12, wherein the layer 1 measurement comprises a first layer 1 measurement and the layer 1 condition comprises a first layer 1 condition, and wherein the method comprises: performing a second layer 1 measurement associated with the one or more candidate LTM cells, and comparing the second layer 1 measurement with a second layer 1 condition; and determining that the first condition is satisfied based on the comparison of the first layer 1 measurement to the first layer 1 condition and on the comparison of the second layer 1 measurement to the second layer 1 condition.

15. The method of claim 12, wherein the layer 1 condition comprises a threshold associated with one or more of a system information block (SSB) value, a channel state information (CSI)-reference signal (RS) value, a timing advance (TA) value, or a beam stability value.

16. The method of claim 11 , wherein the second condition comprises a layer 3 condition, and wherein the method comprises: performing a layer 3 measurement associated with the one or more candidate LTM cells, and comparing the layer 3 measurement with the layer 3 condition.

17. The method of claim 16, wherein the layer 3 measurement comprises a filtered measurement associated with one or more of a cell or a beam.

18. The method of claim 11 , comprising determining that the first condition is satisfied subsequent to receiving the second configuration information.

19. The method of claim 11 , comprising sending the indication to select a cell of the one or more candidate LTM cells based on a time limit subsequent to the determination that the first condition is satisfied.

20. The method of claim 11 , comprising: receiving an indication to modify the first condition; modifying the first condition based on the indication; and determining that the first condition is satisfied based on the modification of the first condition.