WO2024211392A1

WO2024211392A1 - Methods for layer 1/2 triggered mobility (ltm) with network energy saving (nes)

Info

Publication number: WO2024211392A1
Application number: PCT/US2024/022807
Authority: WO
Inventors: Brian Martin; Umer Salim; Oumer Teyeb; Faris ALFARHAN; Paul Marinier
Original assignee: InterDigital Patent Holdings Inc
Current assignee: InterDigital Patent Holdings Inc
Priority date: 2023-04-04
Filing date: 2024-04-03
Publication date: 2024-10-10
Anticipated expiration: 2025-10-04

Abstract

A WTRU may receive configuration information for one or more NES states. A NES state cell-off may be configured to indicate a cell may be turned off for a time duration. Based on the WTRU location, the network may configure the WTRU with a set of candidate neighbor cells for L1/2 triggered measurement (LTM). The network may send a L1/2 signaling message indicating the activation of the NES state cell-off for a subset of the candidate neighbor cells configured. The indication may be sent to a group of WTRUs or all WTRUs in the cell. The WTRU may trigger LTM-associated measurements in the candidate neighbor cells that are not in NES state cell-off. The measurements may be reported to the network using L1/2 signaling message. Based on the measurement report received, the network may then send a L1/2 signaling message indicating the WTRU to switch to a target cell.

Description

METHODS FOR LAYER 1/2 TRIGGERED MOBILITY (LTM) WITH NETWORK ENERGY SAVING (NES)

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/457,059, filed April 4, 2023, the contents of which are incorporated herein by reference.

BACKGROUND

[0002] LTM may involve the usage of a L1/2 lower layer signaling for handover associated procedures such as measurement reporting. This may involve using MAC control elements (CE) in contrast to using L3 RRC messages. For example, instead of a base station sending an RRC reconfiguration message to a WTRU, a MAC-CE may be sent instead. In one example, the WTRU may be configured with one or more handover parameters, such as different candidate cells to handover to, the base station may send a MAC-CE indicating to the WTRU which configuration to use for the handover. Additionally, the base station decision to trigger a handover may be taken based on layer 1 measurements, such as CSI-RS, instead of relying on the RRC measurement report message.

[0003] A network energy savings (NES) may be associated with a cell, indicating a base station power savings status. A cell in NES state cell-off may represent the cell is turned off, e.g. , the base station’s baseband hardware is completely turned off. A cell in active NES state may represent the cell is operating normally. A WTRU may determine whether it may transmit or receive in a cell based on the cell’s NES state.

SUMMARY

[0004] In a system, method, and/or device, network energy savings is taken into consideration in determining candidate cell selection management during mobility events. In a system, there may be a method to configure a device with network energy savings information, which may determine reporting and switching later on. Also, there may be system information block and/or group common indications for conditional network energy savings cell switching.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein like reference numerals in the figures indicate like elements, and wherein:

[0006] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0007] 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 one or more techniques disclosed herein. [0008] 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 one or more techniques disclosed herein.

[0009] FIG. 1D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to one or more techniques disclosed herein.

[0010] FIG. 2 illustrates an example of a measurement model.

[0011] FIG. 3 illustrates an example of LTM operation using Carrier Aggregation (CA).

[0012] FIG. 4 illustrates an example of an LTM baseline procedure.

[0013] FIG. 5 illustrates an example of LTM configuration update based on a common indication updating

NES state of cells.

[0014] FIG. 6 illustrates an example of the interaction between NES states and LTM operation.

[0015] FIG. 7 illustrates an example of a dedicated and dynamic indication to enable/disable different LTM neighbors based on NES state.

[0016] FIG. 8 illustrates an example where a cell switch command contains an indication of the NES state for the cell sending the cell switch command.

[0017] FIG. 9 illustrates a flow chart of an example of a WTRU LTM procedure while a WTRU receives common signaling with a NES indication.

[0018] FIG. 10 illustrates a flow chart of an example group common NES indication and WTRU reporting when the SpCell enters the NES state cell-off.

[0019] FIG. 11 illustrates a flow chart of an example of LTM updates with SIB based NES indication(s) and. [0020] FIG. 12 illustrates a flow chart of an example of LTM updates with SIB based NES indication and conditional LTM.

DETAILED DESCRIPTION

[0021] Table 1 bellow lists one or more acronyms that may be used herein.

[0022] T able 1 : Acronyms

[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), singlecarrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S- OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0024] As shown in FIG 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (ON) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though itwill 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 (STA), may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[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, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a Home Node B, a Home eNode B, a next generation NodeB, such as a gNode B (gNB), a new radio (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, 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, and the like. 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 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 116 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 Uplink (UL) Packet Access (HSUPA).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro). [0030] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using 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 , an 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. 1A 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.

[0034] The RAN 104 may be in communication with the CN 106, 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 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 and/or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing a NR radio technology, the CN 106 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 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 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. 1 A may be configured to communicate with the base station 114a, which may employ a cellularbased 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), any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[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 location-determination 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, a humidity sensor and the like.

[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 DL (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 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 DL (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. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While 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. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

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

[0057] A WL XN 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 access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA The traffic between STAs within a BSS may be considered and/or referred to as peer-to-peer traffic. The peer-to- peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[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. 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 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 noncontiguous 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 802.11ah relative to those used in 802.11n, 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 (MTC), 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, 802.11ac, 802.11af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, 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, all available frequency bands may be considered busy even though a majority of the available frequency bands remains idle.

[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 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an NR 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.

[0065] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 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 a 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, DC, 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 106 shown in FIG. 1D 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 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.

[0070] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 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 protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (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 MTC access, and the like The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 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 106 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 106 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing DL 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 104 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 DL packets, providing mobility anchoring, and the like.

[0073] The CN 106 may facilitate communications with other networks. 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 In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local 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 FIGs. 1A-1 D, and the corresponding description of FIGs. 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[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 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.

[0077] In RRC_CONNECTED, a WTRU may detect and measure one or more beams of a cell, and 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 of the results may take place at two different levels: at the physical layer, to derive beam quality for each beam detected, and at the RRC layer, to derive cell quality based on the multiple beams detected. Cell quality from beam measurements may be derived in the same way for the serving cell(s) and for the non-serving cell(s). Measurement reports may contain the measurement results of the X best beams if the WTRU is configured to do so by the base station.

[0078] FIG. 2 illustrates an example of a measurement model.

[0079] As shown in FIG. 2, the beam specific samples (A) may represent the measurements internal to the physical layer 201 The beam specific samples (A) may be the input to a layer 1 filtering 202. Exact filtering may vary depending on implementation choice. The process utilized to perform measurements in the physical may vary (e.g , inputs A and Layer 1 filtering may be implementation specific).

[0080] The output of layer 1 filtering, A¹ 203, may be reported by layer 1 to layer 3211.

[0081] Beam consolidation/selection 204 may be used to consolidate beam specific measurements to derive cell quality 205. The behavior of the beam consolidation/selection 204 may be standardized, and the configuration of this module may be provided by RRC signaling. The cell quality, B 205, may be derived from beam-specific measurements reported to layer 3 after the beam consolidation/selection 205. The reporting period at B 205 may equal one measurement period at A¹ 203.

[0082] Further layer 3 filtering 206 for cell quality 205 may be performed on the measurements provided at point B 205. The behavior of the layer 3 filters may be standardized and the configuration of the layer 3 filters may be provided by RRC signaling The filtering reporting period at C 207 may equal one measurement period at B 205.

[0083] The result after a measurement is processed by the layer 3 filter is represented by C in FIG. 2 207. The reporting rate may be identical to the reporting rate at point B 205 This measurement may be used as input for one or more evaluation of reporting criteria 208.

[0084] Evaluation of reporting criteria 208 may be the process of verifying whether measurement reporting is necessary at point D 209. The evaluation may be based on more than one flow of measurements at reference point C 207, for example to compare between different measurements. This is illustrated by input C 207 and C¹210. The WTRU may evaluate the reporting criteria at least every time a new measurement result is reported at point C 207, or C¹ 210. The reporting criteria may be standardized and the configuration may be provided by RRC signaling (e.g., WTRU measurement report configuration).

[0085] D 209, as shown in FIG. 2, represents the measurement report information sent on the radio interface (e g., on a message)

[0086] L3 beam filtering 211 may be performed on the measurements provided at point A¹ 203 (e.g., on the beam specific measurements). The behavior of the beam filters may be standardized and the configuration of the beam filters may be provided by RRC signaling. Filtering reporting period at E may equal one measurement period at A¹.

[0087] E 212 represents measurements (e.g., beam-specific measurement) after processing in the L3 beam filter 211. Those measurements are associated with K beams 215. The reporting rate may be identical to the reporting rate at point A¹ 203. [0088] The beam selection process 213 may result in the selection of X beams 214 out of the K beams 215 measurements provided at point E 212, resulting in the measurement in point F 216. The behavior of the beam selection may be standardized and the configuration of this module may be provided by RRC signaling.

[0089] F 216 represents beam measurement information included in a measurement report (e.g., sent) on the radio interface.

[0090] Layer 1 filtering may employ a certain level of measurement averaging. How and when the WTRU exactly performs the required measurements may be implementation specific and may be based on some predetermined performance requirements of the output at B 205. Layer 3 filtering for cell quality 206, and associated parameters, may not introduce any delay in the sample availability between B 205 and C 207, ideally. C¹ 210 is the input used in the event evaluation for reporting criteria 208. L3 beam filtering 211 and associated parameters may not introduce any delay in the sample availability between E 212 and F 216, ideally. [0091] Measurement reports may be characterized in one or more ways. For example: measurement reports may include the measurement identity of the associated measurement configuration that triggered the reporting; cell and beam measurement quantities may be included in measurement reports that may be configured by the network; the number of non-serving cells to be reported may be limited through configuration by the network; cells belonging to an excl ude-l ist configured by the network may not be used in event evaluation and reporting, and conversely when an allow-list is configured by the network, only the cells belonging to the allow-list may be used in event evaluation and reporting; beam measurements to be included in measurement reports may be configured by the network (e.g , beam identifier only, measurement result and beam identifier, no beam reporting, etc.).

[0092] Intra-frequency neighbor cell measurements and inter-frequency neighbor cell measurements may be based on one or more definitions. For example, for Synchronization Signal Block (SSB) beam based intra- frequency measurement, a measurement may be defined as an SSB based intra-frequency measurement provided the center frequency of the SSB of the serving cell and the center frequency of the SSB of the neighbor cell are the same, and the subcarrier spacing of the two SSBs is also the same. For example, for SSB based inter-frequency measurement, a measurement may be defined as an SSB based inter-frequency measurement provided the center frequency of the SSB of the serving cell and the center frequency of the SSB of the neighbor cell are different, or the subcarrier spacing of the two SSBs is different (e.g., for SSB based measurements, one measurement object may correspond to one SSB and the WTRU considers different SSBs as different cells). For example, for channel state information - reference signal (CSI-RS) based inter-frequency measurement, a measurement may be defined as a CSI-RS based inter-frequency measurement if it is not a CSI-RS based intra-frequency measurement (e.g., extended cyclic prefix (CP) for CSI-RS based measurement may not be supported in all cases). For example, for CSI-RS based intra-frequency measurement, a measurement may be defined as a CSI-RS based intra-frequency measurement provided one or more conditions: the subcarrier spacing (SCS) of CSI-RS resources on the neighbor cell configured for measurement is the same as the SCS of CSI-RS resources on the serving cell indicated for measurement; for 60kHz subcarrier spacing, the cyclic prefix (CP) type of CSI-RS resources on the neighbor cell configured for measurement is the same as the CP type of CSI-RS resources on the serving cell indicated for measurement; and/or, the center frequency of CSI-RS resources on the neighbor cell configured for measurement is the same as the center frequency of CSI-RS resource on the serving cell indicated for measurement.

[0093] Whether a measurement is non-gap-assisted or gap-assisted may depend on the capability of the WTRU, the active bandwidth part (BWP) of the WTRU, and/or the current operating frequency. For example, for SSB based inter-frequency measurement, if the measurement gap requirement information is reported by the WTRU, a measurement gap configuration may be provided according to the information. A measurement gap configuration may be provided in the following cases: if the WTRU only supports per-WTRU measurement gaps; if the WTRU supports per-frequency range (FR) measurement gaps and any of the serving cells are in the same frequency range of the measurement object In another example, for SSB based intra-frequency measurement, if the measurement gap requirement information is reported by the WTRU, a measurement gap configuration may be provided according to the information. Otherwise, a measurement gap configuration is always provided in the following case: Other than the initial BWP, if any of the WTRU configured BWPs do not contain the frequency domain resources of the SSB associated to the initial DL BWP.

[0094] In non-gap-assisted scenarios, the WTRU may be able to carry out such measurements without measurement gaps. In gap-assisted scenarios, the WTRU may not be assumed to be able to carry out such measurements without measurement gaps.

[0095] In some cases, a device may be able to use inter-cell beam management for managing beams in a carrier aggregation (CA) case. It may be desirable to also support cell change/add in the same scenarios. There is a need for techniques and procedures of L1/L2 based inter-cell mobility for mobility latency reduction. In one sense, this may be inter-cell L1/L2 triggered mobility (LTM).

[0096] LTM may involve the usage of a L1/2 lower layer signaling for procedures associated with handover, such as measurement reporting. This may involve using MAC control elements (CE) in contrast to using L3 RRC messages. For example, instead of a base station sending an RRC reconfiguration message to a WTRU, a MAC-CE may be sent instead. In one example, the WTRU may be configured with one or more handover parameters, such as configuration for different candidate neighbor cells to handover to, the base station may send a MAC-CE indicating to the WTRU which configuration to use for the handover.

Additionally, the base station decision to trigger a handover may be made based on layer 1 measurements, such as CSI-RS, instead of relying on the RRC measurement report message.

[0097] Different approaches may be considered, for example: configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells; dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1/L2 signaling; L1 enhancements for inter-cell beam management, including L1 measurement and reporting, and beam indication ; timing advance management ; and/or, Central Unit (CU) - Distributed Unit (DU) interface signaling to support L1/L2 mobility, if needed. In some instances, the procedure of L1/L2 based inter-cell mobility may be applicable to one or more of the following scenarios: standalone, carrier aggregation (CA) and new radio (NR) - dual connectivity (DC) case with serving cell change within one cell group (CG); Intra-DU case and intra-CU inter-DU case (e g., applicable for standalone and CA: no new RAN interfaces are expected); both intra-frequency and inter-frequency; both FR1 (low frequency bands, e.g., sub-6GHz frequency range) and FR2 (high frequency ranges, e.g., above 6GHz, mmwave); source and target cells may be synchronized or non-synchronized; and/or, inter-CU case is not included.

[0098] In some cases, during LTM and/or inter-cell beam management, which addresses intra-DU and intra-frequency scenarios, the serving cell remains unchanged (e.g., there is no possibility to change the serving cell using L1/2 based mobility) In FR2 deployments, CA may be used in order to exploit the available bandwidth, for example to aggregate multiple composite carriers (CCs) in one band. These CCs may be transmitted with the same analog beam pair (e.g., base station beam and WTRU beam). The WTRU may be configured with transmission configuration indication (TCI) states (e.g., may have fairly large number, for example 64) for reception of PDCCH and PDSCH. Each TCI state may include a RS or SSB that the WTRU refers to for setting its beam. The SSB may be associated with a non-serving physical cell identity (PCI). MAC signaling (“TCI state indication for WTRU-specific PDCCH MAC control element (CE)”) may activate the TCI state for a Coreset/PDCCH. Reception of PDCCH from a non-serving cell may be supported by MAC CE indicating a TCI state associated to non-serving PCI. MAC signaling (“TCI states activation/deactivation for WTRU-specific PDSCH”) may activate a subset of (up to) 8 TCI states for PDSCH reception. DCI may indicate which of the 8 TCI states. Additionally, “unified TCI state” with a different updating mechanism (downlink control information (DCI)-based) may be supported, but without multi-TRP In other cases, there may be support for unified TCI state with multi-TRP.

[0099] One of the objectives of LTM may be to improve handover latency. In a conventional L3 handover or conditional handover, the WTRU may first send a measurement report using RRC signaling. In response to the measurement report, the network (e.g., base station, network node, etc.) may provide a further measurement configuration and potentially a conventional handover or a conditional handover (CHO) configuration. With a conventional handover the network provides a configuration for a target cell after the WTRU reports, using RRC signaling, that the cell meets a configured radio quality criteria. With conditional handover (CHO), in order to reduce the handover failure rate due to the delay in sending a measurement report then receiving an RRC reconfiguration, the network may provide, in advance, a target cell configuration as well as a measurement criteria which determines if and when the WTRU should trigger the CHO configuration. Both of these L3 methods, however, may suffer from some amount of delay due to the sending of measurement reports and receiving of target configurations, particularly in case of the conventional (non-conditional) handover.

[0100] In particular, one goal of LTM may be to enable a fast application of configurations for candidate cells, including dynamically switching between SCells and switching of the PCell (e.g., switch the roles between SCell and PCell), without performing RRC signaling. It is noted that the inter-CU case may be excluded from LTM, as it may require relocation of the PDCP anchor, and accordingly, an RRC/L3 based approach may be needed to at least to support inter-CU handover.

[0101] Furthermore, with legacy L3 handover mechanisms, any currently active SCell(s) may be released before the WTRU completes the handover to a target cell in the coverage area of a new site, and may only be added back after successful handover, which may lead to throughput degradation during handover. One of the goals of LTM may be to enable instantaneous CA operation upon serving cell change.

[0102] FIG. 3 illustrates an example of LTM operation using Carrier Aggregation (CA). In this example, a candidate cell group may be configured by RRC and a dynamic switch of PCell and SCell is achieved using L1/2 signaling, e.g , MAC Control Element (CE).

[0103] Four cells are considered in the example in FIG. 3. The cells may be configured to operate at frequencies ranging, e.g., from 2 1GHz to 26GHz. This is one example of a possible frequency range, and cell frequencies in the range. One skilled in the art will appreciate that other frequency ranges and cell frequencies may be adopted and the solutions described herein can be used for other frequencies.

[0104] To execute a dynamic switch, the network may send a dynamic switch indication to the WTRU using L1/2 signaling such as a MAC CE. The WTRU’s MAC layer may receive the MAC CE with the dynamic switch indication from the network. The WTRU’s MAC layer then may indicate the dynamic switch to the WTRU’s RRC layer. The WTRU’s RRC layer may apply the new configuration to execute the dynamic switch. Once in the new cell, the RRC layer may send an RRC message in the new cell indicating the successful switching. Optionally, the indication of successful switching may be sent in the new cell via a L1/2 signaling, such as a MAC CE.

[0105] In the example in FIG. 3, the RRC may initially configure all 4 cells (cells 1 to 4) 301 302 303 304 as candidate cells and may activate 305 cell 1 301 as a PCell and cell 2302 as an SCell. The WTRU movement direction in FIG. 3 is illustrated from left to right 306, as shown in the arrow, and the WTRU starts at the leftmost point in the arrow 305. In this example, as the WTRU moves and approaches cell 3 303, the network may send a first indication (e.g., a L1/2 MAC CE) 307 triggering the WTRU (MAC/RRC) to execute a dynamic switch and change the SCell from cell 2 302 to cell 3 303. Upon continued movement, the WTRU may leave cell 3 303, and the WTRU (MAC/RRC) may receive a second indication 308 from the network (e.g., in a MAC CE) to dynamically switch the Scell back to cell 2302. Upon leaving cell 1 301 , the WTRU may receive a third indication from the network (e.g , in a MAC CE) 309 to dynamically switch the PCell to cell 2 302, and, as approaching cell 4 304, to also dynamically switch 309 the SCell to cell 4 304.

[0106] FIG. 4 illustrates an example of an LTM baseline procedure.

[0107] At 1, the WTRU may send a measurement report message to the base station. The base station may decide to use LTM and initiate candidate cell(s) preparation.

[0108] At 2, the base station may transmit an RRC reconfiguration message to the WTRU including the LTM candidate cell configurations of one or multiple candidate cells [0109] At 3, the WTRU may store the LTM candidate cell configurations and transmit a RRC reconfiguration complete message to the base station.

[0110] At 4a/4b, the WTRU may perform DL synchronization and TA acquisition with candidate cell(s) before receiving the cell switch command In some instances, DL synchronization for candidate cell(s) before cell switch command may be supported, at least based on SSB. Also, TA acquisition of candidate cell(s) before LTM cell switch command may be supported, at least based on PDCCH ordered RACH, where the PDCCH order is only triggered by source cell.

[0111] At 5, the WTRU may perform L1 measurements on the configured candidate cell(s), and transmit lower-layer measurement reports to the base station. In some instances, the lower-layer measurement reports may be carried on L1 and/or MAC. Additionally, the order of DL/UL sync (step 4a/4b) and L1 measurement (step 5) may not be defined and may employ other techniques described herein, and/or may be optional.

[0112] At 6, the base station may execute cell switch to a target cell, and transmit a MAC CE triggering cell switch by including the candidate configuration index of the target cell. The WTRU may switch to the configuration of the target cell.

[0113] At 7, the WTRU may perform random access procedure towards the target cell.

[0114] At 8, the WTRU may indicate successful completion of the cell switch towards the target cell by sending an uplink message.

[0115] In some instances, the WTRU may perform the steps 4-8 multiple times for subsequent LTM cell switch based on the configuration provided in step 2.

[0116] In some instances, an uplink control signal, such as a MAC-CE and/or an RRC message may be sent after the WTRU has switched to the target cell, to indicate successful completion of the LTM cell switch.

[0117] A cell may be in a network energy saving state (NES). For instance, a cell may be in a discontinuous transmission (DTX) state or a partial-DTX state. For instance, in a partial-DTX state, one or more downlink channels may be unavailable in the cell, i.e., not being transmitted by the base station. As another example, a cell may be in a discontinuous reception (DRX) state or a partial-DRX state. For instance, in a partial-DRX state, one or more uplink channels may be unavailable to the UEs in the cell. A combination of DRX and DTX may also be possible. And as another example, the cell may be turned-off at the moment, e g., in NES state cell-off, or in NES state cell-off for a certain duration or even a be in NES state cell-off periodically. An active NES state may be associated to a normal state of the cell, e.g., where all channels are operating normally.

[0118] The terms NES state, NES status, and availability state may be used interchangeably herein to represent the cell state.

[0119] Many NES states can be envisioned, and multiple examples will be used herein to illustrate the different functions and system behavior. For example, a NES state may be a reduced Tx power state, a dormant state, a micro sleep state, a light sleep state, or a deep sleep state. Such examples should not limit the scope of the different aspects described herein. [0120] In some cases, the WTRU may determine whether it may transmit or receive on certain resources depending on a network availability state and/or network energy savings (NES) state, which may imply the base station’s power savings status. An availability state may correspond to a network energy savings (NES) state, a cell DTX mode, a cell DRX mode, and/or a base station availability state. An availability state may be uplink or downlink specific, and may change from symbol to symbol, slot to slot, frame to frame, or on longer duration granularity. The availability state may be determined by the WTRU or indicated by the network. In addition to the examples listed above, an availability state may be, for example, “On”, “DL and UL active”, “UL only active", “off”, “reduced Tx power”, “dormant”, “micro sleep”, “light sleep”, or “deep sleep”. Such states may be abstracted by network configuration parameters and/or values, and a dynamic indication to the UE may point to the active availability state (e g., by DCI or MAC CE signaling).

[0121] The NES states may be operator specific, such as each operator chooses which NES states are applicable to their network. The NES states may be cell specific, such as each operator decides which NES states are applicable to each cell in their network. The NES states may be WTRU-specific, such as a certain user or group of users may be configured with specific NES state, such as a “group-specific dormant state”, where only a specific group of WTRUs are to behave as if the cell is in that NES state (e.g., cell-off NES state). This may help with the overall energy savings of the base station, even though the cell is still operational for certain selected users (e.g., VIP users). Different categories of users may be defines and charged accordingly. [0122] Each NES state may have their own NES parameters. For example, a cell-off NES state may imply that the base station’s baseband hardware is completely turned off. For a cell-off NES state the following NES parameters may be relevant: a maximum or minimum time duration which the cell may be turned off, whether or not the broadcast channel is still transmitted in the cell, whether or not paging functionality is still enabled in the cell, which actions the WTRU should take when receiving a page during the cell-off state, etc. The WTRU may be configured with these parameters either via the broadcast channel or via dedicated RRC messages, for example. In a reduced Tx power state, the WTRU may be configured with a maximum transmit power. This may imply that only WTRUs near the base station may get coverage in that cell. The same parameters may apply to downlink power. Another example is a case where the UL or DL communication is only allowed at some very basic rate.

[0123] Each operator may be able to select which NES parameters to use and assign the values accordingly WTRUs in their network may be configured with the applicable NES states and associated NES parameters for each state. The NES states and parameters may be configured in the WTRU via broadcast or dedicated RRC configuration signaling The WTRU may determine an availability state from reception of availability state indication from, for example by L1/L2 signaling (e.g., a group common DCI or indication), or implicitly may determine it form the reception of periodic DL signaling -or lack thereof.

[0124] In some availability states, some DL or UL resources are not available during certain periods of time, and this enables the network to turn off baseband processing and other activities. Some measurement resources (e.g., SSBs or CSI-RS) may only be made available in certain availability states, including: RLM, BFD, RRM measurements, CSI-RS feedback configuration, and/or a different power offset for CSI feedback.

[0125] The WTRU may determine if a resource is available for transmission/reception and/or if certain measurements are applicable in the active availability state. The WTRU may adapt its active C-DRX cycle, active spatial elements (e.g., antenna or logical ports), active TRPs, and/or paging occasions as a function of the signaled or determined availability state.

[0126] Under certain conditions, the WTRU may further transmit a request to the network (e.g., wake-up request) to modify the availability state to a state for which resources that would satisfy WTRU requirements are available.

[0127] Parameters associated with a state may be defined in a parameters set. For example, a NES parameters set may include configuration to be used during the NES state, and it may include one or more of: a number of antenna ports, a C-DRX configuration, a measurement configuration (e g., for RRM, RLM, and/or BFD), CSI feedback, a CSI-RS configuration, an SSB configuration, CHO or mobility candidates, a set of active TRPs. The WTRU may be configured with one or more NES parameters sets per availability state,

[0128] The WTRU may be configured with one or more sets of NES transmission and/or reception parameters per availability state. The NES parameter sets may be configured in the WTRU via broadcast or dedicated RRC configuration signaling. The WTRU may apply the parameter set (e.g., NES parameters set) according to the determined or signaled availability state. The WTRU may apply one or more applicable configurations depending on the determined NES state In one example, not all WTRUs may be in the same NES state, e.g., a group of WTRU may be offered less power in the downlink transmissions, thus reducing the energy spent by the base station without compromising the quality of another group of WTRUs. In another example, the NES state may be defined per cell, and may be the same for all WTRUs in the cell.

[0129] An availability state may be applicable to at least one transmission, reception, or measurement resource. An availability state may be applicable to at least one time period such as a time slot or time symbol. An availability state may be applicable to a serving cell, a cell group, a frequency band, a bandwidth part, a TRP, a set of spatial elements, or a range of frequencies within a bandwidth part. For example, when an NES state changes in a cell, the WTRU may receive an availability state change indication indicating that this change is just for that cell, for all cells at the same frequency, or/and same RAT.

[0130] The WTRU may consider the active availability state associated with a cell, carrier, TRP, or frequency band to be “Off”, “Deep sleep”, or “Micro sleep” after reception of a DL signaling that changes the cell’s or TRP’s availability state. For example, the WTRU may receive a turn off command on broadcast signaling, RRC signaling, DCI (e g., a group common DCI), or a DL MAC CE (e.g., indication part of PDSCH). The WTRU may determine an availability state from reception of availability state indication from, for example by L1/L2 signaling (e.g., a group common DCI or indication) or broadcast signaling associated with an availability state. [0131] For example, an availability state change indication could also be part of SI update or SIB signaling (e g., in a separate SIB that is not read by legacy WTRUs). There may be a common time for all WTRUs in the cell to determine availability state status.

[0132] For example, the WTRU may determine a change of NES state from the reception of a group common command L1 signaling (e.g., a group common DCI, a multi-stage DCI, a specific DCI format, or a DCI scrambled by a configured or specified NES-specific RNTI). L1 signaling may indicate one of the configured NES parameters sets to apply, or may determine a delta configuration from the current set of parameters upon determining an NES state change. The WTRU may transmit feedback/acknowledgment to base station, possibly multiplexed with UL data (e.g., part of an UL TB as a MAC CE or a sub-header indication), following the reception of NES state change indication.

[0133] For example, the WTRU may determine a change of NES state change from the reception of broadcast signaling associated with NES state indication or change, including signaling in SIB(s) or part of a broadcast or multicast PDSCH. The WTRU may be indicated the NES state explicitly in the SIB. The WTRU may be configured with one or more SIBs exclusively associated with configuration of NES parameters. The WTRU may be configured to receive such broadcast or multicast indication periodically; the WTRU may determine an indication may have been mis-detected if not received on expected periodic occasions, and/or if a timer has elapsed since the last reception of the NES state indication. The WTRU may count the number of misdetections. The WTRU may start inter-cell, inter-frequency, and/or inter-RAT measurements, start a mobility procedure, and/or start evaluating configured CHO candidates following the determination of one or more misdetections of the NES state indication.

[0134] The WTRU may implicitly assume a certain availability state associated with a cell, carrier, TRP, or frequency band (e.g., “Off, “deep sleep”, “micro sleep” or dormant”) based on one or more conditions (a condition associated with another event, as opposed to sending a direct message to the WTRU).

[0135] For example, a condition might be the reception of a command or signal indicating a change in availability state: for example a group common DCI in connected mode or RRC signaling or a presence signal. The WTRU may determine an availability state implicitly form the reception of periodic DL signaling. The WTRU may be configured or specified to associate an availability state with one or more DL signal type (e.g., SSB, partial SSB, and/or one or more periodicity).

[0136] For example, a condition might be the reception of a paging message, paging DCI, or a paging PDSCH, possibly on a subset of PCs (e.g., those aligned with NES DRX cycle or a configured subset of PDCCH resources). The WTRU may assume a certain availability state after reception of an indication part of the DCI or PDCCH scheduling paging (e.g., as a function of the P-RNTI, NES-RNTI or based on receiving an explicit indication -e.g. on a reserved bit). The WTRU may assume a certain availability state after the reception of a paging message with a certain P-RNTI. In one example, a newly defined NES P-RNTI, or the NES-RNTI may be configured in the WTRU. The WTRU may assume a certain availability state after the reception of a paging message with a certain P-RNTI. [0137] For example, for the case where early paging indication (EPI) is configured in the cell, the WTRU may be configured to be part of a paging early indication (PEI) subgroup of devices, in which case the PEI may address all WTRUs in the subgroup. The PEI subgroup may be associated with one or more NES states, e.g., the WTRU may assume a certain NES state after reception of a PEI with an NES subgroup, if that subgroup is configured and/or associated with the NES state. The indication of the applicable NES state or an indication for a NES state switch may be in a paging payload, for example, as a flag part of the paging message or a short message. Such a paging indication may further indicate an alternative cell to monitor the paging channel while the current cell (the cell from which the indication was received) is off, sleep, or in any other NES state. Such a paging indication may further indicate or signal applicable reconfiguration parameters (e.g., for initial access, applicable PRACH resources, applicable SSB/RS occasions, applicable SI cycle, and/or the applicable cell(s) and associated availability states).

[0138] For example, a condition might be the base station DTX status (e.g., whether the base station is in active time or an associated activity timer is running)

[0139] For example, a condition might be the lack of detection of a presence indication in a cell (e.g., absence of DL synchronization channel). For instance, a WTRU may determine an availability state associated with the cell (e.g., “off” or “deep sleep”) if presence indication was not detected on one or more presence indication occasion. For instance, a WTRU may assume or change the cell's availability state after a number of consecutive misdetections or after a timer expires following no detection of a presence signal. The WTRU may determine an availability state is active or inactive after expiry of a timer associated with the availability state. Such a timer may be configured and/or maintained in RRC connected mode only, or also in other modes (e g., RRC idle and RRC inactive modes).

[0140] For example, a “cell-off time duration” may be a parameter in the parameter set associated with the NES state cell-off. When the cell enters the cell-off NES state, the WTRU is notified (explicitly or implicitly), and the WTRU may start a timer. When the timer reaches the value of “cell-off time duration”, the WTRU may assume that the cell is no longer in NES state cell-off, and the cell returned to normal state. Optionally, the parameters set associated with the NES state cell-off may include an indication of a specific NES state (instead of normal state), so that when the timer reaches the value of “cell-off time duration”, the WTRU may assume that the cell is no longer in NES state cell-off, and the cell entered the specific NES state indicated in the parameters set associated with the NES state cell-off.

[0141] For instance, a WTRU may determine an availability state implicitly from the lack of reception of periodic DL signaling For example, the WTRU may be configured with a signal quality threshold (e.g., an RSRP threshold) and if the WTRU does not detect a signal associated with an availability state (e.g., a presence signal or an SSB) with a signal strength above the threshold, the WTRU may assume that this availability state is not active and may assume a different availability state. This criterion may be also coupled with lack of detection of an identifying sequence of the presence signal (e.g., detection of the PSS sequence for example). [0142] For example, a condition might be based on time in the day, where a WTRU may be configured to automatically assume a certain availability state (e.g., off, sleep, or dormant) for a configured subset of cells (e g., capacity boosting cells) based on the time in the day. For example, the WTRU may be configured such that it knows that a capacity boosting cell has an availability state as “On” in certain hours of the day, “Deep sleep” in other configured hours, and “Off” in a third set of configured hours of the day or night.

[0143] For example, a condition might be based on the availability state of an associated cell (e.g., another carrier of the same MAC entity, another carrier in the same cell group, another carrier in the same base station, another sector in the same base station, or a configured associated cell or capacity boosting cell).

[0144] For example, a NES state may be associated with a condition such as the detection of a PSS only signal or a simplified/stripped down SSB signal.

[0145] For example, a NES state may be associated with a condition such as the detection of an RS signal (e g., CSI-RS, PRS, TRS) or the lack thereof.

[0146] For example, a NES state may be associated with a condition such as the WTRU’s RRC state (Idle, inactive, or connected mode).

[0147] For example, a NES state may be associated with a condition such as whether paging has been received, possibly within a configured time window.

[0148] For example, a NES state may be associated with a condition such as whether system information (e g., periodic SI or a subset of SIBs) have/has been received, possibly within a configured time window.

[0149] For example, a NES state may be associated with a condition such as where a measured channel condition(s) being below -or above- a threshold. The WTRU may assume a change of NES state based on a change of measured channel conditions or making a channel measurement below -or above- a threshold. For example, the WTRU may use degradation in measurements of SSBs or CSI-RS, possibly in combination with other signaling- to determine the NES state. For example, a configured window following the DCI reception may be used to measure SSBs and/or CSI-RS for degradation, and if a delta of SSB-RSRP drop is measured the WTRU may determine that the NES state has changed and assume associated actions for such NES state (e g., trigger for CHO candidate selection or for group scheduling for a mobility command).

[0150] The WTRU may be configured to monitor an indication that may characterize the NES state. The NES state may be associated with a base station and/or a cell. In one example, the WTRUs may assume the same NES state for all cells that are part of the same base station, for example cells of the same MAC entity. The NES state indication may be sent in a channel (e.g., a PDCCH) and/or a signal (e.g., a sequence, such as the SSB for presence indication). An indication of a NES state or of a NES state change may indicate the level of activity the WTRU may expect from the associated base station and/or cell, such as reduced activity or increased activity (e.g., relative to a threshold). The NES state may contain activity information of other base stations and/or cells. The NES state indication may be sent in a PDCCH containing group common signaling. For example, the network may transmit a NES-specific RNTI or a group common DCI to a group of WTRUs (e g., WTRUs in the serving cell) indicating a change of an availability state in UL and/or DL. The CRC of the PDCCH may be scrambled with a dedicated “activity indication RNTI or an NES-RNTI.” A WTRU may be configured with at least one search space associated with the monitoring occasions of the activity indication PDCCH. The indication may comprise of a go-to-sleep signal, such as a predefined sequence. When a WTRU detects this sequence, the WTRU may expect a reduced availability state over a specific time duration. The WTRU may activate C-DRX for the period of time indicated. Alternatively, two sequences may be used to indicate regular activity and reduced activity.

[0151] The signaling within the PDCCH or the activity indication may contain one or more parameters.

[0152] For example, a parameter may be an expected availability state of the associated base stations/cells over a specific time interval (e.g., an availability state) The availability state may be predetermined and/or configured and may, for example, comprise of regular and reduced activity The signaling may indicate the availability state. For example, bit “1” may indicate regular activity and bit "0" may indicate reduced activity.

[0153] For example, a parameter may be a transmission and /or reception attribute for each availability state. For example, during certain availability states, a WTRU may not be expected to monitor certain PDCCH search spaces (e.g., including all SSs), and/or receive a certain type of PDSCH (e g., including all PDSCH), and/or transmit PUCCH/PUSCH, and/or perform certain measurements. The WTRU may start or stop monitoring PDCCH and/or TCI states associated with determined NES state, including PDCCH resources or transmission configuration information (TCI) states associated with (de)activated TRPs or spatial elements.

[0154] For example, a parameter may be a set of configurations that may be associated with an availability state and may be used/applied when that availability state is indicated (e.g., an NES parameter set) For example, SS configurations, CSI reporting configurations, indices of transmitted SSBs, etc. Each set of configurations may have an attribute associated with an availability state For example, a tag that can be set to “reduced activity”.

[0155] For example, a parameter may be a time interval over which an availability state is assumed may be signaled in the PDCCH or part of the activity indication. In one instance, the time interval may be indicated using a bitmap where each bit in the bitmap may be associated with a specific duration, such as a slot or a frame. For example, bit “1” may indicate regular activity and bit “0” may indicate reduced activity on an associated frame. In another instance, the time interval may be indicated with a start time and length of interval. The start time may be defined; for example, it may be determined by adding a fixed offset to the time the indication is received. The length of the interval may be configured or signaled in the indication PDCCH.

[0156] For example, a parameter may be a time interval over which an availability state is assumed may be predetermined. The WTRU may assume an interruption delay (e.g., or more generally a time until the NES state changes) after the NES state change command reception (e.g., after the last symbol or slot on which the command was received). The interruption time may be in absolute time, a number of symbols, or a number of slots.

[0157] The WTRU may determine that an uplink ordownlink resource or signal is available for transmission/ reception and/or measurements for the determined network availability state if it is applicable in the active availability state. The WTRU may determine that a subset of measurement resources and/or signals (e.g., SSBs, CSI-RS, TRS, PRS) are not applicable in certain availability states The WTRU may determine that a subset of uplink or downlink resources (e.g., PRACH, PUSCH, PUCCH) are not applicable in certain availability states. The WTRU may transmit some uplink signals only in a subset of network availability states (e.g., SRS, pSRS, PRACH, UCI).

[0158] In some cases, the WTRU may perform cell (re)-selection, mobility to another serving cell, trigger mobility related measurements, and/or start evaluating CHO candidates on alternate cells upon determining a NES change on the camped cell or the serving cell The WTRU may be configured or predefined with an alternative serving cell to perform initial access, mobility, or cell reselection on in the event the current serving cell or a capacity boosting cell (e.g., a cell not configured as an alternative cell) is turned off (NES state cell- off) or a certain condition is met. The WTRU may be configured per broadcast or dedicated signaling with a list of fallback or alternative serving cells, possible per serving cell, per base station, per PLMN, or per network identity.

[0159] In one example, the WTRU may initiate a cell reselection or mobility procedure to an alternative serving cell associated with a cell or base station from which a turn-off indication was received. In one example, the turn off or go-to-sleep indication may dynamically indicate to the WTRU which cell to fallback or connect to, for example by dedicated or broadcast signaling. The fallback/alternative cell may be configured or predefined to be a cell within the same base station from which a sector has entered NES state (e.g., off, sleep, or reduced power). In another example, the fallback cell may be predefined as the master node cell if the WTRU is in dual connectivity. The fallback/alternative cell may be configured or predefined to be a cell associated with a different RAT or frequency band. For example, the WTRU may fallback to an LTE or an FR1 cell associated with the cell or base station from which the turn off indication was received (e.g., if the WTRU is in CA or DC using multiple RATs or multiple frequency bands).

[0160] The terms alternative cell and stable cell may be used interchangeable as discussed herein. A stable cell is a cell that may change NES state with low frequency (where “low” may be defined by a parameter, such as a percentage of time). The WTRU may be configured with a list of stable cells (e.g., alternative cells that will not turn off, e.g., some macro cells); the list may be either a list of alternative cells per serving/camped cell or a general list of PCIs for the whole network, Tracking area, etc. The WTRU may be configured with measurement object configuration for the alternative cells Alternative cells may be preconfigured to be CHO candidates, and/or potentially considered as CHO candidates only if the source cell turns off/activates NES.

[0161] In at least one scenario of the basic procedure of LTM, the network first pre-configures multiple target cell candidates in RRC, then the WTRU performs L1 measurements and reporting, then the WTRU may be triggered to perform DL and UL sync on one or more target cells, before finally receiving a MAC CE which triggers the reconfiguration/handover

[0162] Turning off some cells may achieve NES by reducing the amount of power consumed by the network equipment associated with those cells. By selectively turning off cells that are not heavily utilized or strategically reducing the number of cells in a certain area, the network may operate more efficiently, reducing energy consumption and costs while maintaining adequate coverage and capacity. This may result in significant energy savings over time, reducing the environmental impact of the network and improving its sustainability, especially during times of low demand (for example at night).

[0163] LTM configurations may provide a means to reduce the interruption times for WTRUs. The energy saving mechanisms may select some of the cells that have been configured as LTM candidates. Smooth handling of LTM and NES procedures may be required so that the network may save energy whenever possible without putting the WTRUs in danger of failure (e.g., LTM failure, handover failure, etc.). Therefore, there is a need for LTM procedures to consider the possibility of dynamic changing of cell configurations due to NES.

[0164] Generally, as discussed herein, “perform LTM” or “perform LTM procedure” may refer to performing any combination of, and/or all of the steps described in FIG. 4. For example, performing early synchronization in DL and/or UL to one or more candidate cells, performing L1 measurements, reporting on one or more of the candidate cells, and/or switching (e.g., performing handover) between candidate cells (e g., “Perform LTM” may mean that the WTRU moves/switches between multiple candidate cells during the procedure).

[0165] Generally, as discussed herein, one or more candidate cell sets may be groups of more than one RRC configuration(s) corresponding to a handover configuration for one or more candidate SpCells and optionally SCells. This may be modelled or received as one or more complete RRC Reconfiguration messages, one or more cell group configurations, or one or more cell configurations. Each of the candidate cell configurations may include a candidate configuration identifier, and each of the candidate cell groups may include a candidate cell group identifier. If the grouping is performed at RRC, the switching between different sets of candidate cells may include updating the serving cell indices or candidate configuration indices that are used in L1 and MAC signaling to refer to specific indices (e.g., a MAC CE triggering the reconfiguration may include a candidate configuration index informing the WTRU which cell to perform the reconfiguration to).

[0166] The one or more candidate cell groups may be configured as a single list or group of candidate cell configurations at RRC. The grouping may occur at the early sync or LTM execution phase rather than the configuration phase - meaning, that the candidate cell set may be considered as a single group in terms of an RRC configuration list or group, while the cells selected for performing early sync, L1 measurements, and LTM execution depend on a further grouping into multiple subsets of the overall candidate cell list. In other words, the grouping itself may not be modelled at RRC using candidate configuration identifiers, but the grouping may be executed as part of the early sync or the LTM execution procedure

[0167] As disclosed herein, when referring to an LTM candidate configuration, this may apply to any type of preconfigured cell information. For example, a WTRU may be configured with one or more conditional reconfigurations such as conditional handover (CHO), conditional PSCell addition (CPA) or conditional PSCell change (CPC) that are valid before and/or after a cell change, or valid in certain cells.

[0168] As disclosed herein, an L1 measurement = may comprise of a measurement of RSRP, RSRQ, RSSI, etc., performed by a WTRU of a cell, beam, set of cells, or set of beams. Such L1 measurement may be similar to L3 measurements reported in RRM, with differences in the filtering, reference signals measured, reporting mechanisms, etc.

[0169] As discussed herein, measurements may refer to L1 measurements for LTM. However, certain examples may apply also to RRM/L3 measurements, as well as other measurements (e g., measurements of speed, location, height, traffic, etc.).

[0170] In some cases, a WTRU may be provided with a preconfigured pattern of neighbor cell NES states. In general this may be a list of cells with associated NES related parameters or information. For example, the WTRU may be configured with a list of cells that are configured with at least one NES technique, a list of cells may serve NES capable WTRUs, or a list of cells that are actively using at least one NES technique (e.g., cell DTX, spatial or power domain adaptation, cell turn off, or sleep etc.). In some instances, the WTRU may be configured with multiple patterns which may be referenced using an index or identity.

[0171] In one example, a list of neighbor cells is provided, for example, using a permanent identifier such as PCI or Cell ID, or using a temporary identifier such as a serving cell identity or candidate cell identity, with an indication of the state or certain parameters. The (e.g., neighbor) cell state may be configured per cell, or there may be a common configuration which may be indicated as being applicable to multiple cells - for example a configuration comprising of cell state = on, Cell DTX/DRX pattern = pattern A may be applied to one or more cells in the list.

[0172] In some instances, the preconfigured NES pattern may be provided in broadcast signaling, for example in a SIB. In one example, this may be provided to a WTRU using dedicated signaling, for example in an RRC Reconfiguration.

[0173] A WTRU, as disclosed herein, may be provided with any of the parameters or configurations as disclosed herein, and/or the WTRU may be provided with NES alternative cells, as described herein.

[0174] A changing of a NES state or parameter may impact one or more of the following LTM related parameters or procedures: LTM candidate list; CSI reporting, which may update the SSBs or CSI-RS which are active in some of the candidates; DL sync, where whether the WTRU maintains downlink synchronization to a cell may depend on the NES states; UL sync, where whether the WTRU maintains a TA for a candidate cell may depend on the NES state; RA type, where the WTRU may determine to use a particular RA procedure (e g., 2 step, 4 step, or RACH-less) depending on the NES state; L1 event triggered reporting, where there may be a new MAC CE for L1 event reporting, limited to the only the active NES cells; update thresholds or L1 reporting criteria based on cell state; update active BWPs to use when triggering the LTM; and/or, replace some of the candidate cells with NES alternative cells depending on the NES state of a candidate cell. The WTRU may change or apply a subset of these LTM parameters depending on the direction of the NES state change of the source cell and/or a candidate cell (e.g., On to OFF vs. OFF to On, Cell DTX activated vs. Cell DTX de-activated, spatial/power domain coverage reduction etc.)

[0175] FIG. 5 illustrates an example of LTM configuration update based on a common indication updating NES state of cells. Here, an example message sequence for LTM configuration update based on a common indication updating NES state of cells is shown. The key aspect of this solution is that the information related to NES information update is conveyed in a common indication. In the example in FIG. 5, a system information block (SIB) is used 501.

[0176] Initially, the WTRU may be configured with one or more sets of NES state parameters associated with one or more NES states 501. As an example, in a periodic cell-off NES state, the set of NES state parameters may define a starting time, a periodicity of the cell-off NES state, a duration of the cell-off NES state, and an ending time. The starting time may not be needed, if an indication is used to notify the WTRU that the cell is entering that state. The same may apply to the ending time, which may be based on an indication sent to the WTRU.

[0177] The WTRU may be configured with a subset of cells as LTM candidates via dedicated RRC signaling, such as using an RRC reconfiguration message 502.

[0178] To receive common signaling, the WTRU may be configured by the network with a group common signaling. This may be achieved by providing the WTRU with a group common RNTI (e.g. , a cell specific RNTI or a NES-RNTI).

[0179] Since the WTRU is pre-configured with the NES state parameter set, an indication notifying the WTRU that the cell is entering a given NES state may be based on a short indication 503, and the parameters associated with each state do not need to be transmitted with the short indication.

[0180] The short indication 503 may be transmitted for example in a DCI 503. The DCI may be sent in a CORESET configured against a NES specific RNTI, a group common RNTI or another common RNTI. An RRC configuration for NES indication may provide the mapping between the PC Is and the bits in the DCI where the indication is sent. Or the bits may be pre-defined or pre-provisioned in the WTRU. The NES indication may be transmitted in a bitmap pattern in the DCI. The NES state indication may be limited to certain cells (e.g., non-stable cells).

[0181] In one example, the bitmap indicated in the DCI may correspond to an indication for which of the alternative cells or configured candidate cells to consider for LTM, and the bitmap size may be determined as the size of alternative cell candidates configured for the source cell from which the DCI was received.

[0182] Optionally, the short indication 503 may be transmitted in the MAC-CE that may be transmitted in the data scheduled through a NES specific DCI, group common DCI, or a WTRU specific DCI. The signaling may be based upon bitmap where pre-configuration associates the cell identities to the specific bits in the bitmap

[0183] More than one types of MAC-CE may be used. One NES indication MAC-CE may comprise a bitmap providing NES state indication for the cells configured to be indicated through MAC signaling. One long NES indication MAC-CE may be used, which may provide the indication of NES state of a set of cells configured to be indicated. The long NES indication MAC-CE may also provide additional attributes related to NES procedures In one case, for each cell turning ON/OFF, timing information may be provided as to when the network is planning to turn these cells ON or OFF. The NES state indication may be limited to non-stable cells. [0184] In one example, the bitmap indicated in the MAC CE may correspond to an indication for which of the alternative cells, non-stable cells, or configured candidate cells to consider for LTM. The MAC CE size may be fixed, but cells indicated part of the MAC CE may be re-configured. For example, the MAC CE size may be fixed to indicate x candidate cells or alternative cells, but the list of configured alternative cells may be y (where y>x) RRC (re)-configuration may configure which of the y alternative cells are to be included in the MAC CE.

[0185] The long MAC-CE may provide attributes modifying the WTRU processing/behavior for LTM procedure. In one instance, the indication may comprise of a trigger to provide the LTM measurements to the network at a specific time

[0186] Optionally, short messages may be used to transmit the short indication 503. Short messages may be transmitted on PDCCH using P-RNTI with or without associated paging message using, for example, a short message field in DCI format 1_0. The signaling conveying a change in a NES state may use one or more of the reserved bits (by redefining the bits), where the NES state may be associated with the serving cell. The bits may indicate a single on/off indication using a single bit, or a combination of bits may be used to provide more information such as a configuration index or indicate the presence of an associated paging message. The associated paging message, or any associated message type received on PDSCH, may contain further information such as an index to a predefined NES cell state list, or may provide attributes modifying the WTRU processing/behavior for LTM procedure. In one case, the indication may comprise of a trigger to provide the LTM measurements to the network at a specific time.

[0187] In one example, one bit may indicate a flag for NES state change associated with the source cell. Another bit may indicate a NES state change associated at least with another candidate cell Upon reception of such a flag, the paging message may include further information on the nature of the NES state change The paging message may include further information on the NES state change of candidate cells.

[0188] The parameters of NES states may be update via a SIB update 504. The LTM measurement report triggers may also be updated 505. When a triggers occurs, the WTRU may send an LTM measurement report and complete the LTM procedure 506.

[0189] FIG. 6 illustrates an example of the interaction between NES states and LTM operation. The WTRU may receive configuration information for one or more NES states 601. The configuration information may be sent in a cell-specific message, e.g., a common RRC message (e.g., SIB message) 601 or in an RRC dedicated message (e.g., RRC reconfiguration message, not shown in FIG. 6). The configuration information may contain NES parameters for each of the configured NES states 602. A NES state cell-off may be defined, with its associated parameters, indicating a cell may be turned off for a certain time duration.

[0190] The network may configure a set of neighbor cells as candidate cells. These candidate cells may be configured for LTM. These candidate cells may be selected by the network based on the WTRU location. As an example, in FIG. 6, cell 1 to cell (x+y) are configured as LTM candidate cells 603.

[0191] This may be sent in a UE-specific RRC message (e.g , RRC reconfiguration message) 603. Optionally this may be broadcast in the cell system information [0192] An LTM measurement triggering event (referred to as LTM-event in FIG. 6) is an event identified by the WTRU which may trigger the WTRU to perform LTM measurements. The WTRU monitors for the events, and if the event is triggered (i.e., the event occurs), the WTRU starts performing the LTM measurements associated with that event.

[0193] An LTM measurement report triggering event (LTM-MR-event) is an event that triggers the WTRU to report LTM measurements to the network (e.g , to the serving cell). The LTM-MR-event may be associated with the LTM measurement results, such as a condition on the measurement result may trigger the reporting from the WTRU. A measurement is performed by the UE is specific cells, including e.g., the serving cells and neighbor cells. The WTRU monitors for the events, and if the event is triggered (i.e., the event occurs), the WTRU reports the LTM measurement results. The results may be based on the LTM measurements that were performed.

[0194] The UE may optionally be pre-configured with one or more LTM-events associated with the candidate cells. The LTM-event may optionally be an implicit triggering event that the WTRU is pre-configured to identify, as it was discussed in previous paragraphs herein. Optionally, the network may configure LTM- events in the WTRU using an RRC message 603. In FIG 6, the network configures the WTRU with LTM-events when configuring the LTM candidate cells (e.g., RRC reconfiguration message) 603. The LTM-MR-events may also be configured in the WTRU via the RRC dedicated message 603.

[0195] The LTM-event may be associated with the NES state of the cells. As an example, the LTM-event may be the event of one or more cells from the candidate set of cells entering a specific NES state. In one example, the WTRU may be triggered to perform LTM measurements when one or more cells from the candidate sets changes their NES state. The new NES state may be configured to be the NES state cell-off.

[0196] The network may then send a L1/2 signaling message 604 indicating the activation of a NES state for one or more cells from the candidate cells configured. For example, in FIG. 6, candidate cells from cell 1 to cell x are indicated to the WTRU to enter NES state cell-off 605. The NES state activation indication may be a bitmap.

[0197] As previously mentioned, the LTM-event for the example shown in FIG. 6 is to trigger LTM measurements when one or more cells from the candidate set changes their NES state to NES state cell-off. Accordingly, the WTRU may be monitoring for that event, and it identifies the LTM-event 606. In this example, the WTRU may be configured to, upon identification of the LTM-event, start performing LTM measurements in the cells that are not in NES state cell-off. Candidate cells from cell (x+1) to cell (x+y) are not in NES state cell- off, so the WTRU may start measuring the candidate cells from cell (x+1 ) to cell (x+y) 607.

[0198] The WTRU may be monitoring for the event LTM-MR-event. In the example in FIG. 6, the WTRU identifies the occurrence of the LTM-MR-event 608. The LTM-MR-event may be associated with signal strengths of the candidate cells, SINR of candidate cells, and comparisons between the serving cells and the candidate cells. The LTM-MR-event may be associated with events that may trigger a handover. [0199] The measurement report may be sent to the network over a L1/2 signaling message, such as using a MAC CE 609. Based on the measurements received 609, the network may then send a L1/2 signaling message indicating the WTRU to switch to a target cell 610. The target cell may be one of the candidate cells that are not in NES state cell-off and that the WTRU measured and reported to the network. The signaling received may trigger the WTRU to switch to the indicated target cell 611

[0200] FIG. 7 illustrates an example dedicated and dynamic indication to enable/disable different LTM neighbors based on NES state. As shown, there may be a message sequence for the dynamic indication to enable/disable different LTM neighbors based on NES state. The key aspect of this example is that the NES state of neighbor cells is informed to the WTRU using a MAC CE sent to the WTRU using dedicated signaling. With this approach, the network may dynamically update the LTM candidate NES states per WTRU, which may provide the best performance, for example in case NES state is very dynamic according to scheduler.

[0201] As shown in FIG. 7, initially, LTM candidates are preconfigured in the WTRU 701. The preconfiguration may include cell specific NES information including LTM specific information that depends on the NES state of the cell. This may be provided by an RRC Reconfiguration, or a SIB 701 . This may be different preconfigured NES cell state patterns (e.g., active cells, load, priority, threshold, DRX config etc.).

[0202] The WTRU may receive an indication of NES state of current and one or more neighbor LTM candidate cells 702. The MAC CE bitmap may contain an index to a preconfigured cell state pattern. In some situations, a MAC CE containing a bitmap may be received by the WTRU. Each bit in the MAC CE may refer to an LTM candidate cell ID or a serving cell ID and indicate whether the NES state is on (e.g., bit = 'T) or off (e g., bit = ‘0’). In another example, the WTRU may not know exactly the nature of the NES state of the candidate cells but may use the bit indications to know whether or not to consider the cell for LTM. Each bit in the MAC CE may refer to an LTM candidate cell ID or a serving cell ID and indicate whether to consider such cell for LTM (e.g., bit = ‘T) or exclude such cell from LTM (e.g., bit = ‘0’); where such indication may be only for the list of cells configured as non-stable cells. In some instances, the MAC CE contains an index referring to a preconfigured NES pattern or state.

[0203] Based on the received MAC CE information, the WTRU may update the LTM candidate cells and/or the LTM parameters, such as updating the CSI reporting triggers 703.

[0204] Upon receiving a measurement report, the network may decide to handover the WTRU to one of the reported cells 704. The network may send a control MAC CE indicating a cell switch to the target cell. The WTRU may switch to the target cell and send an indication to the target cell 706, e.g., LTM complete, handover complete, or RRC reconfiguration complete.

[0205] FIG. 8 illustrates an example where a cell switch command contains an indication of the NES status for the cell sending the cell switch command.

[0206] The key aspect of this example is that the NES state of the source cells may be informed to the WTRU using a MAC CE, as part of LTM cell switch indication. With this approach, the WTRU may be informed of the NES state of a cell just visited when cell switch is triggered. In this case there may be no need to transfer information/coordinate between cells.

[0207] Initially, the WTRU may receive a pre-configuration of cell specific NES information including LTM specific information which depends on the NES state of the cell.

[0208] The WTRU may receive a configuration of LTM candidate cells 801.

[0209] The WTRU may receive L1/2 signaling (e.g., MAC CE) 802 containing an LTM cell switch indication, and including NES indication of: a cause value indicating that a source cell is being switched off or changing NES state, and/or a delay for the cell switch.

[0210] The WTRU may perform reconfiguration according to the indicated candidate cell received in the LTM cell switch command, and may release or update configuration of the source cell RRC candidate configuration, if indicated, after the indicated delay.

[0211] In one example, the WTRU may receive additional NES information in the same MAC CE triggering a cell switch. The MAC CE may contain, for example, a candidate configuration ID (e.g., an ID of a target cell configuration) and an indication of a change of NES state of the source cell. In some situations, a separate MAC CE may be provided before the LTM execution MAC CE that may contain this additional information.

[0212] In one example, the NES state change indication may be a single flag indicating a switch between 2 binary states. In some situations, the NES state change indication may be an index identifying a preconfigured NES state. The WTRU may exclude cells indicates as in NES state from the list of candidate cells considered for LTM.

[0213] In one example, the WTRU may receive (e.g., in a MAC CE or a DCI) a list of neighbor cells that will be turned on or that are no longer applying a NES technique (e.g., cell DTX, spatial or power domain adaptation) Upon reception of such indication, the WTRU may start LTM related measurements for such indicated cells and perform mobility if the configured mobility conditions are satisfied.

[0214] In one example, the NES information received in the MAC CE may provide a status or an upcoming status of the cell that sent the MAC CE.

[0215] In one example, the NES information may additionally include a timer value, indicating a time at which the change of state will take place (e.g , a number of milliseconds or seconds in the future) In some situations, the time indication has a value of either “immediate” or “at a preconfigured time” wherein the preconfigured time may be a fixed value, or may be pre-provisioned, or may be configured in a semi-static manner, for example in SIB or dedicated signaling. For example, the WTRU may be configured with a switchon period, a switch off period, a cell DTX activation period, a cell DTX deactivation period. Upon reception of a MAC CE indication an upcoming NES state change, the WTRU may assume that the indicated neighbor cell will apply the NES state change after the configured period has elapsed, and the WTRU may start LTM related measurements during such duration or after the configured period has elapsed (e.g., in the case of cell turn off for example). [0216] FIG. 9 illustrates an example flow chart of a WTRU LTM procedure while a WTRU receives common signaling with a NES indication. In this example, the network may update the status of LTM configured candidates for a WTRU. Further, the example has a flow chart for updating LTM candidate configurations with a group common signaling based indication.

As shown, initially the WTRU is configured with NES dynamic indication that may be provided in a group common signaling 901 . RRC configuration provides the details on the cell identities and the dynamic indication pattern. The WTRU may be configured with an LTM procedure with a set of LTM candidates and the reporting mechanisms for the configured candidates. The WTRU may be configured to treat LTM candidates with respect to NES (ON/OFF) indication. The WTRU may, for example, stop monitoring the LTM candidates which the network is planning to switch OFF. In addition, there may be two sets of thresholds (e.g., two sets of offsets) for LTM candidates. One set of thresholds may be applicable for LTM candidates when the serving cell is ON, and another set when the serving cell is turning OFF, according to the NES indication. The WTRU may monitor, measure, and provide a report about the LTM candidates as per the LTM configuration.

[0217] The WTRU may receive group common signaling providing the update on the status of neighbor cells NES state 902. The NES state indication may include cells being turned ON or OFF with a (pre- Jconfigured/indicated time delay. These may contain a NES neighbor cells config ID or a mapping table so that the WTRU may associate the correct NES state to the relevant cell.

[0218] The WTRU may identify the NES indication from the group common signaling for the cells that are LTM candidates 903.

[0219] The WTRU may remove the LTM candidates for which the network has indicated NES indication with status OFF from its set of actively monitored LTM candidates 904.

[0220] The WTRU may activate its LTM candidates for which network has indicated NES indication with status ON from its set of actively monitored LTM candidates 905.

The WTRU may perform the measurements over the actual LTM candidates 906. The WTRU may provide a measurement report of the strongest (a configurable number of strongest, e.g., N) cell(s) to the network by sending a report.

[0221] The WTRU may receive the network indication for the LTM switching to one of the candidates 907.

[0222] The WTRU may perform LTM switching to the network indicated cell 908.

[0223] FIG. 10 illustrates a flow chart of an example of group common NES indication and WTRU reporting when the SpCell enters the NES state cell-off. In this example, the network is updating the status of SpCell for WTRU within the NES common indication. Similar to the SIB based approach, the WTRU may be configured to trigger a measurement report when the SpCell is being turned off, to identify the most suitable alternative beam or cell (e.g., an NES alternative cell).

[0224] Initially, the WTRU may be configured with NES dynamic indication that may be provided in a group common signaling 1001. RRC configuration may provide configuration information for LTM and NES operation. The configuration information may include the details on the cell identities and the dynamic indication pattern. The WTRU may be configured with LTM procedure with a set of LTM candidates. The WTRU may be configured to treat LTM candidates with respect to NES (ON/OFF) indication. This may be configured, for example, by stopping to monitor the LTM candidates which the network is planning to switch OFF. In addition, there may be two sets of thresholds (e.g., two sets of offsets) for LTM candidates. One set of thresholds may be applicable for LTM candidates when the serving cell is ON, and another set when the serving cell is turning OFF according to the NES indication.

[0225] The WTRU may be configured with a special reporting mechanism in case NES signaling provides the indication of PSCell being turned OFF 1001.

[0226] The WTRU may monitor, measure, and provide (e g., send) the report on measurements of the LTM candidate cells, as per the configuration.

[0227] The WTRU may receive group common signaling providing the update on the neighbor cells NES state 1002. NES state indication may be cells being turned ON or OFF with a (pre-) configured/indicated time delay. The signaling may contain a NES neighbor cells config ID or a mapping table so that WTRU may associate the correct NES state to the relevant cell 1003.

[0228] The WTRU may identify the NES indication from the group common signaling for the cells which are its LTM candidates.

[0229] The WTRU may remove the LTM candidates for which network has indicated NES indication with state OFF from its set of actively monitored LTM candidates 1004. The WTRU may monitor the LTM candidates that are indicated to be turning ON 1005.

[0230] The group common signaling providing NES state may include the turn OFF indication for the SpCell 1006, in which case the WTRU may trigger a special reporting to the network 1007. Otherwise, the WTRU may measure the LTM candidates and provide a measurement report of the strongest (e.g., a configurable number of strongest) cell(s) to the network 1008.

[0231] The WTRU may receive the network indication for the LTM switching to one of the candidates 1009. [0232] The WTRU may perform LTM switching to the network indicated cell 1010.

[0233] FIG. 11 illustrates a flow chart of an example of an LTM update with SIB based NES indication. In this example, there may be SIB based design for NES indication and WTRU update of LTM configurations.

[0234] The WTRU may be configured with NES where NES indication for a set of cells is provided through an NES SIB. NES SIB with (pre-)configuration may specify the cell identities and the NES state update for the cells 1101. The NES indication may also provide the timing when a cell will change to indicated status with suitable granularities

[0235] The WTRU may be configured to trigger a special measurement reporting mechanism when the SpCell is being turned off, to identify the most suitable alternative beam or cell (e.g., an NES alternative cell) 1101. The WTRU may be configured with LTM procedure with a set of LTM candidates and the reporting mechanisms for the configured candidates.

[0236] The WTRU may be configured to treat LTM candidates with respect to NES (ON/OFF) indication provided in NES SIB This may be configured, for example, by stopping to monitor the LTM candidates which the network is planning to switch OFF In addition, there may be two sets of thresholds (e.g., two sets of offsets) for LTM candidates. One set of thresholds may be applicable for LTM candidates when the serving cell is ON, and another set when the serving cell is turning OFF according to the NES indication.

[0237] The WTRU may monitor, measure, and send a report about the LTM candidates as per the LTM configuration.

[0238] The WTRU may receive paging about NES SIB change 1102. In one instance, the P-RNTI may be used to indicate the NES SIB change indication. In one instance, a new P-NES-RNTI may be used to provide NES SIB change indication; This could save the non-NES WTRUs decoding the paging and subsequent system information acquisition.

[0239] The WTRU may acquire the SIB providing NES information (e.g., NES SIB) 1103. The NES SIB may provide NES information for a set of configured cells. If a NES SIB is not scheduled, the WTRU may request the network to receive NES SIB through dedicated signaling. The NES SIB may provide the update on the status of neighbor cells NES state. The NES state indication may be cells being turned ON or OFF with a (pre-)configuredZindicated time delay.

[0240] The WTRU may identify the NES indication from the NES SIB for the cells that are its LTM candidates 1104.

[0241] The WTRU may remove the LTM candidates for which the network has indicated NES indication with status OFF from its set of actively monitored LTM candidates 1105 The WTRU may activate the monitoring the LTM candidates for which the network has indicated NES indication with status ON 1106. The WTRU may report the measurements of e.g., the N best cells 1107.

[0242] The group common signaling may provide a NES state change to OFF for the SpCell, in which case the WTRU may trigger a special measurement reporting to the network configured for the case of PSCell turning OFF 1108. This reporting for the case of the SpCell turning OFF may be provided over a special resource (pre- Jconfigured to the WTRUs. In an alternative case, WTRUs may be pre-configured to transmit a scheduling request (SR) that WTRUs may transmit to the network when the SpCell is turning OFF. The network may provide an UL grant through which WTRUs may provide a measurement report that may be a MAC based or an RRC based reporting. The WTRU may measure the LTM candidates and provide a measurement report of the strongest (e.g., a configurable number of strongest) cell(s) to the network. In some instances, this measurement report may be performed using L1 event triggered reporting, CSI reporting and the WTRU may indicate the best beams and/or cells with their associated measurements (e.g., RSRP). In some instances, a specific CSI reporting configuration may be applied, for example, to enable reporting of some specific resources (e g., beams on NES alternative cells). [0243] The WTRU may receive the network indication for the LTM switching to one of the candidates 1109.

[0244] The WTRU may perform LTM switching to the network indicated cell 1110.

[0245] FIG. 12 illustrates a flow chart of an example of LTM updates with SIB based NES indication and conditional LTM. In this example, there may be SIB based or group common indication approach for NES indication and WTRU update of LTM configurations and WTRU triggering autonomously conditional LTM through prior configurations if the current SpCell is turning OFF.

[0246] The WTRU may be configured with NES support, where a NES indication for a set of cells is provided through an NES SIB. The NES SIB with (pre-)configuration may specify the cell identities and a NES state update for the cells 1201 . NES SIB may also provide the timing when a cell will change to indicated status with suitable granularities

[0247] The WTRU may be configured with LTM procedure with a set of LTM candidates and the reporting mechanisms for the configured candidates. The WTRU may be configured to treat LTM candidates with respect to NES (ON/OFF) indication provided in NES SIB. This may be configured, for example, by stopping to monitor the LTM candidates which network is planning to switch OFF. In addition, there may be two sets of thresholds (e g., two sets of offsets) for LTM candidates. One set of thresholds is applicable for LTM candidates when the serving cell is ON, and another set when the serving cell is turning OFF according to the NES indication.

[0248] The WTRU may monitor, measures, and send the report about the LTM candidates as per the LTM configuration.

[0249] The WTRU may receive paging about NES SIB change 1202. Alternatively, the WTRU may receive a common indication as described in other examples herein. In one instance, the P-RNTI may be used to indicate the NES SIB change indication. In one instance, a new P-NES-RNTI may be used to provide NES SIB change indication; this may save the non-NES WTRUs decoding the paging and subsequent system information acquisition. In one instance, the common indication may be conveyed using a MAC CE. In one instance, the common indication may be conveyed via a DCI using a group common RNTI, a NES RNTI, or another common RNTI. In one instance, the common indication may be conveyed using a short message carried on PDCCH using P-RNTI.

[0250] The WTRU may acquire the SIB providing NES information for a set of configured cells 1203. Alternatively, this acquiring the SIB may be optional, for example, if a common indication is used then it may contain all of the necessary information to update the NES state. If a NES SIB is not scheduled, the WTRU may request the network to receive NES SIB through dedicated signaling. The NES SIB may provide the update on the status of neighbor cells NES state. The NES state indication may be cells being turned ON or OFF with a (pre-jconfigured/indicated time delay.

[0251] The WTRU identify the NES indication from the NES SIB for the cells that are its LTM candidates 1204.

[0252] The WTRU may remove the LTM candidates for which the network has indicated NES indication with status OFF from its set of actively monitored LTM candidatesl 205. If the group common signaling providing NES state includes the turn OFF indication for the SpCell, the WTRU may determine a suitable LTM candidate as per the following: the WTRU may selecft a suitable LTM target among the activated configured LTM candidates (e g., “activated” may mean: the WTRU has a valid TA for this cell, the WTRU is maintaining DL synchronization, the WTRU is performing TRS tracking, and/or the WTRU is actively reporting CSI). The selection of a suitable candidate may be through a second set of RSRP (RSRQ) thresholds configured by the network. If there is no cell satisfying the autonomous selection conditions, the WTRU may choose the cell with the strongest signal quality; and/or, the strongest signal quality criterion may be RSRP, RSRQ associated with the RS of the target candidate The criterion may be part of the configuration.

[0253] The WTRU may activate the LTM candidate cells that are turning ON 1206. The WTRU may report the measurements of e.g., the N best cells 1207 The WTRU may execute LTM cell switch to the selected cell 1208.

[0254] In some cases, the WTRU may determine a suitable cell to autonomously switch to. For instance, the WTRU may attempt to autonomously trigger LTM if an indication was received that the PCell is switching off due to NES 1209.

[0255] The WTRU may attempt to autonomously trigger LTM if an indication was received that one or more neighbor cells are switching on.

[0256] The WTRU may select a subset of LTM candidate cells to consider for autonomous LTM. In one instance, the subset may be determined based on one or more of the following: cells for which the WTRU has a valid TA; cells on which the WTRU is maintaining DL synchronization; cells on which the WTRU is performing TRS tracking; cells on which WTRU is actively reporting CSI; cells with a radio quality measurement above a configured threshold; and/or, an explicit list of cells.

[0257] The subset of cells may be selected such that those cells are prepared for the WTRU to perform LTM at any time (e.g , based on an explicit MAC CE). As an example, the case where the WTRU has already performed a PDCCH ordered RA to obtain the TA or the case where the WTRU has been explicitly configured to maintain DL sync or report CSI measurements.

[0258] For example, the WTRU may select a subset of cells based on the current radio conditions, and the WTRU may need to trigger a random access to the target cell upon LTM execution. In some instances, the WTRU may be configured with early TA acquisition using RAR (e.g., the WTRU may be configured to perform early TA acquisition and receive TA in a RAR) In this case the WTRU may respond to the RAR (e.g., using a provided grant) in order to complete the LTM to the target cell.

[0259] The WTRU may attempt to perform a cell switch to a cell that has been indicated as switching on, and the WTRU may perform the random access after a certain period of time. The WTRTU may first trigger measurements and/or DL sync procedure before triggering RA.

[0260] The WTRU may have been preconfigured (either by RRC or in a MAC CE) with an indication of the specific cells to be included in the subset. This pre-configuration may include a TA to use, uplink resources to use, for example a configured grant (e.g., CG-PUSCH at a specific time) to transmit an ACK, specific RA resources. The WTRU may receive a time indication for this grant, with respect to reception timing of the signaling indicating the NES state. The time indication may be pre-configured, sent with the indication, or determined based on a received indication.

[0261] A suitable target cell may be determined from the subset This may be based on one or more of the following: a prioritization, for example prioritize intra-DU cells or specific cells; the best radio quality measurement, for example RSRP; and/or, the cell with the highest number of beams above a radio quality threshold.

[0262] If a suitable candidate cell is determined, the WTRU may then execute LTM. For example, perform an RRC reconfiguration using the stored candidate configuration, but without any explicit MAC CE.

[0263] In one approach, there may be an LTM configuration update based on a common indication updating a NES state of cells. Generally, a WTRU may receive a configuration enabling a dynamic update of neighbor cell NES states using common signaling. For example, one or more of the following may be configuration for the WTRU: the WTRU may be configured to receive one or more NES indications that may be provided in a group common signaling; a RRC pre-configuration may provide details of cell identities and NES state patterns; and/or, the WTRU may be configured with a set of LTM candidates and measurements, procedures, and parameters associated with particular NES states.

[0264] The WTRU may receive common signaling providing the update of one or more neighbor cells NES state. For example, one or more of the following may be included in the signaling: a NES state indication that may indicate cell(s) being turned ON or OFF with a (pre-)configured/indicated time delay; one or more NES neighbor cells config ID or a mapping table so that the WTRU may associate the correct NES state to relevant cell; and/or, an index to a pre-configured set of neighbor cell states.

[0265] The WTRU may update the LTM configuration according to the new NES states. For example, the WTRU may remove the LTM candidates for which the network has indicated NES indication with status OFF from its set of actively monitored LTM candidates and may enable LTM candidates for which the network has indicated NES indication with status ON. The WTRU may update an LTM candidate cell monitoring based on the NES state, for example: CSI reporting, which may update the SSBs or CSI-RS that are active in some of the candidates; DL/UL sync; L1 event triggered reporting, where new MAC CE for L1 event reporting (e.g., limited to the only the active NES cells); update thresholds or L1 reporting criteria based on cell state; and/or, update active BWPs to use when triggering the LTM.

[0266] If the group common signaling providing NES state includes the turn OFF indication for the PCell, then one or more of the following may apply: the WTRU may receive the network indication for the LTM switching to one of the candidates; the WTRU may execute LTM switching to the network indicated cell, and/or, the WTRU may measure a subset of LTM candidates and provide an indication to the network. For this last option, the indication may be one or more of: RRC measurement report, L1 event triggered report (E.g. in a MAC CE), or CSI report; a report of the strongest (e.g., a configurable number of strongest) cell(s) to the network; and/or, a specific set of cells (e.g., NES alternative cells). [0267] Group/common signaling may enable additional benefits to the system, such as reduced signaling overhead. The NES state of a cell may be informed using common signaling, and each WTRU may update the (e g., active) LTM configurations based on the NES state. There may be an identification of suitable alternative cell(s) to perform LTM before the cell is powered off.

[0268] In one approach, there may be a SIB based / group common NES indication(s) and an implicit and/or conditional LTM Generally, a WTRU may receive a configuration enabling a dynamic update of neighbor cell NES states using common signaling.

[0269] The WTRU may receive the common signaling providing the update of one or more neighbor cells NES state(s).

[0270] The WTRU may update the LTM configuration according to the new NES state(s).

[0271 ] There may be an implicit LTM trigger: If the common signaling providing NES state includes the turn OFF indication for the SpCell, the WTRU will determine a suitable LTM candidate and autonomously execute the LTM cell switch to the selected cell.

[0272] In such a case where there is an implicit LTM trigger, the WTRU may select a suitable LTM target from a subset of LTM candidates. The subset may be the cells on which the WTRU is maintaining DL sync and/or UL sync (e.g., has a valid TA); this may imply the cells are prepared and ready for LTM cell switch at any time. The subset may be the cells for which CSI reporting has been enabled. The subset may be a set of cells previously indicated as the LTM candidates for the case of NES turn OFF indication. The selection of a suitable target from the subset may be based on radio conditions, such as the strongest cell amongst the selected subset, or above a threshold.

[0273] In the case of implicit LTM trigger, if a suitable cell is selected, the WTRU may execute LTM without any MAC CE trigger. If the WTRU does not already have DL/UL sync then the WTRU may perform RACH to the target cell Otherwise, the WTRU may execute the LTM in the same way as if the candidate configuration index was received in a MAC CE (e.g., normal case).

[0274] In such a case where there is an implicit LTM trigger, if no suitable cell can be selected for implicit LTM trigger, then the WTRU may trigger RLF, or measurement report.

[0275] In this approach, there may be one or more benefits to the system, such as improved latency and signaling reduction when turning a cell off. Using common signaling, HO may be triggered implicitly for multiple WTRUs on a deactivated cell, avoiding the need to trigger WTRUs individually when a cell enters NES “off” state.

[0276] As described herein, a higher layer may refer to one or more layers in a protocol stack, or a specific sublayer within the protocol stack. The protocol stack may comprise of one or more layers in a WTRU or a network node (e g., eNB, gNB, other functional entity, etc.), where each layer may have one or more sublayers. Each layer/sublayer may be responsible for one or more functions. Each layer/sublayer may communicate with one or more of the other layers/sublayers, directly or indirectly. In some cases, these layers may be numbered, such as Layer 1 , Layer 2, and Layer 3. For example, Layer 3 may comprise of one or more of the following: Non-Access Stratum (NAS), Internet Protocol (IP), and/or Radio Resource Control (RRC). For example, Layer 2 may comprise of one or more of the following: Packet Data Convergence Control (PDCP), Radio Link Control (RLC), and/or Medium Access Control (MAC). For example, Layer 3 may comprise of physical (PHY) layer type operations. The greater the number of the layer, the higher it is relative to other layers (e.g., Layer 3 is higher than Layer 1). In some cases, the aforementioned examples may be called layers/sublayers themselves irrespective of layer number, and may be referred to as a higher layer as described herein. For example, from highest to lowest, a higher layer may refer to one or more of the following layers/sublayers: a NAS layer, a RRC layer, a PDCP layer, a RLC layer, a MAC layer, and/or a PHY layer. Any reference herein to a higher layer in conjunction with a process, device, or system will refer to a layer that is higher than the layer of the process, device, or system. In some cases, reference to a higher layer herein may refer to a function or operation performed by one or more layers described herein. In some cases, reference to a high layer herein may refer to information that is sent or received by one or more layers described herein. In some cases, reference to a higher layer herein may refer to a configuration that is sent and/or received by one or more layers described herein.

[0277] Although features and elements are described above in particular combinations (e.g., embodiments, methods, examples, etc.), one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. For example, as disclosed herein there may be a method described in association with a figure for illustrative purposes, and one of ordinary skill in the art will appreciate that one or more features or elements from this method may be used alone or in combination with one or more features from another method described elsewhere. A symbol 7’ (e g., forward slash) may be used herein to represent ‘and/or’, where for example, ‘A/B’ may imply A and/or B’. As used herein, ‘a’ and ‘an’ and similar phrases are to be interpreted as 'one or more’ and ‘at least one’. Similarly, any term which ends with the suffix ‘(s)’ is to be interpreted as 'one or more’ and ‘at least one’. The term ‘may’ is to be interpreted as ‘may, for example’ or indicate that something "does happen" or "can happen". In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random-access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS What is Claimed:

1. A method to be performed by a wireless receive-transmit unit (WTRU), the method comprising: receiving, from a first cell, configuration information for one or more candidate cells including a cell identification for the one or more candidate cells, wherein the one or more candidate cells are in active Network Energy Saving (NES) state; receiving, from the first cell , L1/2 triggered mobility (LTM) measurement configuration information for at least one cell from the one or more candidate cells; receiving, from the first cell, a first signaling message, wherein the first signaling message includes identification of at least one cell from the one or more candidate cells and an indication of activation of a cell-off NES state for the identified at least one cell from the one or more candidate cells; generating, by the WTRU, and based on the LTM measurement configuration information, measurement results for at least one candidate cell which is in the active NES state; sending, to the first cell, an LTM measurement report message, wherein the LTM measurement report message includes, for each measured cell, at least a measurement result and identification of the measured cell; receiving, from the first cell, a second signaling message, wherein the second signaling message includes an identification of a second cell, wherein the second cell is a cell included in the measurement report message; switching, at the WTRU, from the first cell to the second cell; and sending, by the WTRU, to the second cell, a third signaling message confirming the successful switching

2. The method of claim 1 , further comprising, receiving, from the network, configuration information for one or more NES states, wherein the one or more NES states include the active NES state and the cell-off NES state, and wherein the configuration information for the cell-off NES state includes a time value indicating a time duration that a cell will be turned off.

3. The method of claim 2, further comprising generating, by the WTRU, after receiving the first signaling message including an indication of activation of a cell-off NES state for the identified at least one cell from the one or more candidate cells, and upon elapsing of the time duration, LTM measurement results for the cells included in the first signaling message.

4. The method of any of claims from 1 to 3, wherein the first signaling message and second signaling message are received in a downlink control information (DC I).

5. The method of any of claims from 1 to 4, wherein the measurement report message is sent in a medium access control (MAC) control element (CE).

6. The method of any of claims from 1 to 5, wherein the third signaling message is sent in a radio resource control (RRC) message.

7. The method of any of claims from 1 to 6, wherein the first signaling message is a group common signaling message addressing a plurality of WTRUs.

8. The method of any of claims 1 to 7, wherein the first cell is a PCell.

9. The method of any of claims from 1 to 8, further comprising, receiving, from the network, a fourth signaling message, wherein the fourth signaling message includes an identification of at least one cell from the one or more candidate cells, wherein the identified at least one cell from the one or more candidate cells is in cell-off NES state and wherein the fourth signaling message includes an indication of activation of the active NES state for the identified at least one cell from the one or more candidate cells.

10. The method of claim 9, further comprising, generating, by the WTRU, based on the measurement configuration information, measurement results for the at least one cell from the one or more candidate cells identified in the fourth signaling message.

11. A wireless transmit-receive unit (WTRU), the WTRU comprising at least one processor and a transceiver, wherein the at least one processor and transceiver are configured to: receive, from a first cell, configuration information for one or more candidate cells including a cell identification for the one or more candidate cells, wherein the one or more candidate cells are in active Network Energy Saving (NES) state; receive, from the first cell, L1/2 triggered mobility (LTM) measurement configuration information for at least one cell from the one or more candidate cells; receive, from the first cell, a first signaling message, wherein the first signaling message includes identification of at least one cell from the one or more candidate cells and an indication of activation of a cell-off NES state for the identified at least one cell from the one or more candidate cells; generate, based on the LTM measurement configuration information, measurement results for at least one candidate cell which is in the active NES state; send, to the first cell, an LTM measurement report message, wherein the LTM measurement report message includes, for each measured cell, at least a measurement result and identification of the measured cell; receive, from the first cell, a second signaling message, wherein the second signaling message includes an identification of a second cell, wherein the second cell is a cell included in the measurement report message; switch from the first cell to the second cell; and send, to the second cell, a third signaling message confirming the successful switching.

12. The WTRU of claim 11 , wherein the at least one processor and the transceiver are further configured to receive, from the network, configuration information for one or more NES states, wherein the one or more NES states include the active NES state and the cell-off NES state, and wherein the configuration information for the cell-off NES state includes a time value indicating a time duration that a cell will be turned off.

13. The WTRU of claim 12, wherein the at least one processor and the transceiver are further configured to generate, after receiving the first signaling message including an indication of activation of a cell- off NES state for the identified at least one cell from the one or more candidate cells, and upon elapsing of the time duration, LTM measurement results for the cells included in the first signaling message.

14. The WTRU of any of claims from 11 to 13, wherein the first signaling and second signaling messages are received in a downlink control information (DCI).

15. The WTRU of any of claims from 11 to 14, wherein the measurement report message is sent in a medium access control (MAC) control element (CE).

16. The WTRU of any of claims from 11 to 15, wherein the third signaling message is sent in a radio resource control (RRC) message.

17. The WTRU of any of claims from 11 to 16, wherein the first signaling is a group common signaling message addressing a plurality of WTRUs.

18. The WTRU of any of claims 11 to 17, wherein the first cell is a PCell.

19. The WTRU of any of claims from 11 to 18, wherein the at least one processor and the transceiver are further configured to receive, from the network, a fourth signaling message, wherein the fourth signaling message includes an identification of at least one cell from the one or more candidate cells, wherein the identified at least one cell from the one or more candidate cells is in cell-off NES state and wherein the fourth signaling message includes an indication of activation of the active NES state for the identified at least one cell from the one or more candidate cells.

20. The WTRU of claim 19, wherein the at least one processor and the transceiver are further configured to generate, based on the measurement configuration information, measurement results for the at least one cell from the one or more candidate cells identified in the fourth signaling message.