Methods, architectures, apparatuses, and systems for layer 2 mobility

Abstract

Processes, methods, architectures, apparatuses, systems, devices, and computer program products for layer 2 mobility (LTM). A wireless transmit / receive unit (WTRU) performs measurements of respective downlink beams associated with at least one initial candidate cell for handover; determines, based on the measurements, a selected candidate cell for handover among the at least one initial candidate cell; transmits information indicating the selected candidate cell as a target cell using an uplink control channel resource; and transmits information indicating completion of handover.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 572,473, filed April 1, 2024, which is incorporated herein by reference in its entirety. Background Technology

[0002] This disclosure generally relates to the field of communications, including, for example, methods, architectures, apparatuses, and systems relating to Layer 2 Mobility (LTM). Summary of the Invention

[0003] In a first aspect, this principle relates to a method at a radio transmit / receive unit (WTRU), the method comprising: performing measurements of a corresponding downlink beam associated with at least one initial candidate cell for handover; determining a selected candidate cell for handover among the at least one initial candidate cells based on the measurements; transmitting information indicating the selected candidate cell as a target cell using uplink control channel resources; and transmitting information indicating completion of handover.

[0004] In an embodiment, the method includes determining a corresponding timing advance value for the at least one initial candidate cell for handover, and using the uplink control channel resources and the timing advance value of the selected candidate cell to send information indicating that the selected candidate cell is the target cell to the selected candidate cell.

[0005] In an embodiment, the method includes receiving an indication of an uplink shared channel from the selected candidate cell on a downlink control channel, wherein information indicating completion of handover is transmitted on the uplink shared channel. The information indicating the selected candidate cell as the target cell may be transmitted to the cell currently serving the WTRU. The method may include receiving information indicating activation of the uplink shared channel in response to transmitting the information indicating the selected candidate cell as the target cell. The uplink shared channel may be associated with dynamic granting. The uplink shared channel may be associated with configuration granting.

[0006] In an embodiment, when a triggering event occurs for at least one candidate cell for handover, the selected candidate cell for handover is determined.

[0007] In this embodiment, the selected candidate cell is the initial candidate cell with the highest measured beam quality among the at least one initial candidate cells.

[0008] In an embodiment, the method includes receiving information indicating the at least one initial candidate cell for handover, wherein for each initial candidate cell for handover, the information includes at least one uplink control channel resource associated with a downlink beam and conditions for performing the handover.

[0009] In this embodiment, the switching is a Layer 2 mobility switching.

[0010] In this embodiment, the uplink control channel resource is a scheduling request sent to the cell currently serving the WTRU.

[0011] In a second aspect, this principle relates to a wireless transmit / receive unit (WTRU) comprising at least one processor configured to: perform measurements of a corresponding downlink beam associated with at least one initial candidate cell for handover; determine a selected candidate cell for handover among the at least one initial candidate cells based on the measurements; transmit information indicating the selected candidate cell as a target cell using uplink control channel resources; and transmit information indicating completion of handover.

[0012] In an embodiment, the at least one processor is configured to: determine a corresponding timing advance value for the at least one initial candidate cell for handover; and use the uplink control channel resources and the timing advance value of the selected candidate cell to send information indicating that the selected candidate cell is the target cell to the selected candidate cell.

[0013] In an embodiment, the at least one processor is configured to receive an indication of an uplink shared channel from the selected candidate cell on a downlink control channel, wherein information indicating completion of handover is transmitted on the uplink shared channel. The information indicating the selected candidate cell as the target cell may be transmitted to the cell currently serving the WTRU. The at least one processor may be configured to receive information indicating activation of the uplink shared channel in response to transmitting the information indicating the selected candidate cell as the target cell. The uplink shared channel may be associated with dynamic granting. The uplink shared channel may be associated with configuration granting.

[0014] In an embodiment, the at least one processor is configured to determine the selected candidate cell for handover when a triggering event for at least one candidate cell for handover occurs.

[0015] In this embodiment, the selected candidate cell is the initial candidate cell with the highest measured beam quality among the at least one initial candidate cells.

[0016] In an embodiment, the at least one processor is configured to receive information indicating the at least one initial candidate cell for handover, the information including, for each initial candidate cell for handover, at least one uplink control channel resource associated with a downlink beam and conditions for performing the handover.

[0017] In this embodiment, the switching is a Layer 2 mobility switching.

[0018] In this embodiment, the uplink control channel resource is a scheduling request sent to the cell currently serving the WTRU. Attached Figure Description

[0019] A more detailed understanding can be obtained from the following detailed description given by way of example in conjunction with the accompanying drawings. As with the detailed description, the figures in such drawings are exemplary. Therefore, the figures and the detailed description should not be considered limiting, and other equally valid examples are possible. Furthermore, the same reference numerals (“reference marks”) in the figures indicate the same elements, and wherein: Figure 1A This is a system diagram illustrating an example communication system; Figure 1B It shows that it can be shown Figure 1A The system diagram shown is of an example wireless transmit / receive unit (WTRU) used in the communication system. Figure 1C It shows that it can be shown Figure 1A The system diagram shows an example radio access network (RAN) and an example core network (CN) used in the communication system shown. Figure 1D It shows that it can be shown Figure 1A The system diagram shown represents another example RAN and another example CN used within the communication system. Figure 2 The standard LTM procedure defined in 3GPP TS 38.300 v18.1.0 is shown; and Figure 3 A flowchart of a conditional LTM based on an embodiment of this principle is shown. Detailed Implementation

[0020] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the following description. Furthermore, embodiments and examples not specifically described herein may be practiced in place of or in combination with the embodiments and other examples expressly, implicitly, and / or inherently described, disclosed, or otherwise provided herein (collectively, the “Provided”). Although this document describes and / or claims various embodiments in which means, processes, algorithms, functions, etc., and / or any elements thereof perform operations, processes, algorithms, functions, etc., and / or any parts thereof, it should be understood that any embodiment described and / or claimed herein assumes that any means, systems, devices, etc., and / or any elements thereof are configured to perform any operations, processes, algorithms, functions, etc., and / or any parts thereof.

[0021] Example Communication System The methods, apparatus, and systems provided herein are well-suited for communications involving wired and wireless networks. About Figures 1A to 1D An overview of various types of wireless devices and infrastructures is provided, wherein various elements of the network may utilize, perform, be arranged according to, and / or be adapted and / or configured for use with the methods, apparatuses and systems provided herein.

[0022] Figure 1A This is a system diagram illustrating an example communication system 100 that can implement one or more of the disclosed embodiments. The communication system 100 can be a multiple access system providing content such as voice, data, video, messaging, and broadcasting to multiple wireless users. The communication system 100 enables multiple wireless users to access such content through shared system resources including wireless broadband. For example, the communication system 100 can employ one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Zero-Tail (ZT) Unique Word (UW) Discrete Fourier Transform (DFT) Extended OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0023] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, radio access networks (RANs) 104 / 113, core networks (CNs) 106 / 115, public switched telephone networks (PSTNs) 108, the Internet 110, and other networks 112. However, it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. For example, WTRUs 102a, 102b, 102c, and 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include / or be user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0024] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, and 102d, for example, to facilitate access to one or more communication networks such as CN 106 / 115, Internet 110, and / or Network 112. For example, base stations 114a and 114b may be base transceiver stations (BTS), node Bs (NBs), eNode-Bs (eNBs), master node Bs (HNBs), master eNode-Bs (HeNBs), gNode-Bs (gNBs), NR node Bs (NR NBs), site controllers, access points (APs), wireless routers, etc. Although base stations 114a and 114b are each depicted as a single element, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0025] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (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 specific geographic area that may be relatively fixed or may change over time. A cell may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in an embodiment, base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0026] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) can be used to establish air interface 116.

[0027] More specifically, as described above, the communication system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base station 114a in RAN 104 / 113 and WTRUs 102a, 102b, 102c can implement radio technologies, such as using Wideband CDMA (WCDMA) to establish Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) for air interface 116. WCDMA can include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed ​​Downlink Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

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

[0029] In the embodiments, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies, such as using New Radio (NR) to establish NR radio access for air interface 116.

[0030] In the embodiments, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can, for instance, use the dual connectivity (DC) principle to jointly implement LTE radio access and NR radio access. Therefore, the air interface used by WTRUs 102a, 102b, and 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0031] In the embodiments, base station 114a and WTRUs 102a, 102b, and 102c can implement radio technologies such as IEEE 802.11 (i.e., Wi-Fi), IEEE 802.16 (i.e., Global System for Multi-Use Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0032] Figure 1ABase station 114b can be, for example, a wireless router, master node B, master eNode-B, or access point, and can utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial locations, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for use by drones), roads, etc. In embodiments, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In embodiments, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In embodiments, base station 114b and WTRUs 102c, 102d can utilize cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish any of small cells, picocells, or femtocells. Figure 1A As shown, base station 114b can be directly connected to Internet 110. Therefore, base station 114b does not need to access Internet 110 via CN 106 / 115.

[0033] RAN 104 / 113 can communicate with CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU 102a, 102b, 102c, and 102d. Data can have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although Figure 1A As not shown, but will be understood, RAN 104 / 113 and / or CN 106 / 115 can communicate directly or indirectly with other RANs employing the same RAT as or a different RAT than RAN 104 / 113. For example, in addition to being connected to RAN 104 / 113, which may be utilizing NR radio technology, CN 106 / 115 can also communicate with another RAN (not shown) employing any of the following radio technologies: GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi.

[0034] CN 106 / 115 can also serve as a gateway for WTRU 102a, 102b, 102c, 102d to access PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 / 114 or a different RAT.

[0035] Some or all of the WTRUs 102a, 102b, 102c, and 102d in communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A The WTRU 102c shown can be configured to communicate with a base station 114a that can use cellular-based radio technology and with a base station 114b that can use IEEE 802 radio technology.

[0036] Figure 1B This is a system diagram illustrating example WTRU 102. (See diagram below.) Figure 1B As shown, WTRU 102 may include a processor 118, a transceiver 120, a transmitting / receiving element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other components / peripherals 138, etc. It will be understood that, while remaining consistent with the embodiments, WTRU 102 may include any sub-combination of the foregoing components.

[0037] Processor 118 can be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 can be coupled to transceiver 120, which can be coupled to transmitting / receiving element 122. Although Figure 1B The processor 118 and transceiver 120 are depicted as separate components, but it will be understood that the processor 118 and transceiver 120 can be integrated together, for example, in an electronic package or chip.

[0038] Transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In another embodiment, transmitting / receiving element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, transmitting / receiving element 122 can be configured to transmit and / or receive both RF signals and optical signals. It will be understood that transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0039] Although the transmitting / receiving element 122 is in Figure 1B While depicted as a single element, WTRU 102 may include any number of transmitting / receiving elements 122. For example, WTRU 102 may employ MIMO technology. Therefore, in an embodiment, WTRU 102 may include two or more transmitting / receiving elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via air interface 116.

[0040] Transceiver 120 can be configured to modulate signals transmitted by transmitting / receiving element 122 and demodulate signals received by transmitting / receiving element 122. As described above, WTRU 102 can have multi-mode capability. Therefore, transceiver 120 can include multiple transceivers for enabling WTRU 102 to communicate via various RATs (e.g., such as NR and IEEE 802.11).

[0041] The processor 118 of WTRU 102 can be coupled to and receive user input data from: a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit). The processor 118 can also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. Additionally, the processor 118 can access information and store data from any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. 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. Removable memory 132 may include a subscriber identity module (SIM) card, memory stick, secure digital storage (SD) card, etc. In other embodiments, the processor 118 can access information and store data from memory not actually located on WTRU 102, such as on a server or home computer (not shown).

[0042] The processor 118 may receive power from the power supply 134 and may be configured to distribute power to other components in the WTRU 102 and / or control power to those other components. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 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, etc.

[0043] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that, while remaining consistent with the embodiments, the WTRU 102 may acquire location information using any suitable location determination method.

[0044] The processor 118 can also be coupled to other components / peripherals 138, which may include one or more software and / or hardware modules / units that provide additional features, functions, and / or wired or wireless connectivity. For example, components / peripherals 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (e.g., for photos and / or video), Universal Serial Bus (USB) ports, vibration devices, television transceivers, hands-free headsets, Bluetooth® modules, FM radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Components / peripherals 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; geolocation sensors; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0045] WTRU 102 may include a full-duplex radio, wherein the transmission and reception of some or all of the signals (e.g., associated with a specific subframe of both the uplink (e.g., for transmission) and the downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing (e.g., a separate processor (not shown) or via processor 118). In embodiments, WTRU 102 may include a half-duplex radio, wherein the transmission and reception of some or all of the signals (e.g., associated with a specific subframe of either the uplink (e.g., for transmission) or the downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0046] Figure 1C This is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 can employ E-UTRA radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0047] RAN 104 may include eNode-Bs 160a, 160b, and 160c, but it will be understood that RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In the embodiments, eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Therefore, for example, eNode-B 160a may use multiple antennas to transmit radio signals to and receive radio signals from WTRU 102a.

[0048] Each of the eNode-B 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in the uplink (UL) and / or downlink (DL), etc. Figure 1C As shown, eNode-B 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0049] Figure 1C The CN 106 shown may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (PGW) 166. While each of the foregoing elements is described as part of CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0050] The MME 162 can connect to each of the eNode-Bs 160a, 160b, and 160c in RAN 104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c, etc. The MME 162 can provide control plane functions for handover between RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0051] The SGW 164 can connect to each of the eNode Bs 160a, 160b, and 160c in RAN 104 via the S1 interface. The SGW 164 can typically route and forward user data packets to or from WTRUs 102a, 102b, and 102c. The SGW 164 can perform other functions such as anchoring the user plane during eNode-B handover, triggering paging when DL data is available to WTRUs 102a, 102b, and 102c, and managing and storing the context of WTRUs 102a, 102b, and 102c.

[0052] SGW 164 can be connected to PGW 166, which can provide WTRU 102a, 102b, 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0053] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to circuit-switched networks (such as PSTN 108) to facilitate communication between WTRUs 102a, 102b, and 102c and traditional terrestrial line communication equipment. For example, CN 106 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and PSTN 108, or can communicate with it. Additionally, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0054] Despite WTRU in Figures 1A to 1D While described as a wireless terminal, it is envisioned that, in some representative embodiments, such a terminal may (e.g., temporarily or permanently) use a wired communication interface with a communication network.

[0055] In a representative embodiment, the other network 112 may be a WLAN.

[0056] A WLAN in Infrastructure Basic Services 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 access a distribution system (DS) or another type of wired / wireless network that loads traffic into and / or loads traffic out of the BSS, or have an interface to it. Traffic originating outside the BSS destined for a STA can be delivered to the AP via it. Traffic from a STA destined for a destination outside the BSS can be sent to the AP for delivery to the appropriate destination. Traffic between STAs within the BSS can be sent via the AP, for example, where a source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as point-to-point traffic. Point-to-point traffic can be sent between a source STA and a destination STA using a direct link setup (DLS) (e.g., directly between them). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using the Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode may sometimes be referred to as a "self-organizing" communication mode in this document.

[0057] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of fixed width (e.g., a 20 MHz bandwidth) or dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access - Collision Avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, each STA (e.g., every STA), including the AP, can sense the primary channel. If a particular STA senses / detects that the primary signal is busy and / or determines that the primary signal is busy, that STA can back off. In a given BSS, at any given time, only one STA (e.g., only one station) can transmit.

[0058] High-throughput (HT) STAs can communicate using a 40MHz wide channel, for example, by combining a primary 20MHz channel with adjacent or non-adjacent 20MHz channels.

[0059] Very High Throughput (VHT) STAs can support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz and / or 80 MHz channels can be formed by combining consecutive 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels, or by combining two non-consecutive 80 MHz channels, which can be referred to as an 80+80 configuration. In the 80+80 configuration, after channel coding, data can be passed through a fragment parser, which splits the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed on each stream separately. The streams can be mapped onto the two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations of the 80+80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC) layer, entities, etc.

[0060] 802.11af and 802.11ah support operating modes below 1 GHz. The channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV Blank (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument-type control / machine-type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only) certain and / or limited bandwidths. MTC devices may include batteries with a battery life exceeding a threshold (e.g., to maintain a very long battery life).

[0061] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STAs operating in the BSS that support the minimum bandwidth operating mode. In the 802.11ah example, for STAs that support (e.g., only support) the 1 MHz mode (e.g., MTC type devices), the primary channel can be 1 MHz wide, 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 Sense and / or Network Assignment Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, due to STAs (which only support the 1 MHz operating mode) transmitting to the AP, the entire available band may be considered busy even if most of the band remains idle and potentially available.

[0062] In the United States, the available frequency band for 802.11ah is 902 MHz to 928 MHz. In South Korea, the available frequency band is 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0063] Figure 1D This is a system diagram illustrating RAN 113 and CN 115 according to an embodiment. As described above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 113 may also communicate with CN 115.

[0064] RAN 113 may include gNBs 180a, 180b, and 180c, but it will be understood that RAN 113 may include any number of gNBs while remaining consistent with the embodiments. gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In embodiments, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from WTRUs 102a, 102b, and 102c. Therefore, for example, gNB 180a may use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a. In embodiments, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be located on unlicensed spectrum, while the remaining component carriers may be located on licensed spectrum. In embodiments, gNBs 180a, 180b, and 180c can implement Coordinated Multipoint (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNBs 180a and 180b (and / or gNB 180c).

[0065] WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using transmissions associated with scalable parameter sets. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., including different numbers of OFDM symbols and / or absolute times of varying durations).

[0066] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNode-Bs 160a, 160b, and 160c). In standalone configuration, WTRUs 102a, 102b, and 102c can use one or more of gNBs 180a, 180b, and 180c as mobile anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in unlicensed frequency bands. In a non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate / connect with gNBs 180a, 180b, and 180c while also communicating / connecting with another RAN (such as eNode-Bs 160a, 160b, and 160c). For example, WTRUs 102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c. In a non-standalone configuration, eNode-Bs 160a, 160b, and 160c can act as mobile anchors for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput to serve WTRUs 102a, 102b, and 102c.

[0067] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interoperability between NR and E-UTRA, routing of user plane data to User Plane Functions (UPF) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMF) 182a and 182b, etc. Figure 1D As shown, gNB180a, 180b, and 180c can communicate with each other via the Xn interface.

[0068] Figure 1DThe CN 115 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the foregoing elements is described as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0069] AMF 182a and 182b can connect to one or more of the gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can act as control nodes. For example, AMF 182a and 182b can be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different Protocol Data Unit (PDU) sessions with different requirements), selecting specific SMF 183a and 183b, managing registration areas, terminating NAS signaling, mobility management, etc. AMF 182a and 182b can use network slicing, for example, to customize CN support for WTRU 102a, 102b, and 102c based on the service types being used by WTRU 102a, 102b, and 102c. For example, different network slices can be created for different use cases, such as services that rely on Ultra Reliable Low Latency (URLLC) access, services that rely on Enhanced Massive Mobile Broadband (eMBB) access, and services for MTC access. AMF 162 can provide control plane functions for handover between RAN 113 and other RANs (not shown) that employ other radio technologies (such as LTE, LTE-A, LTE-A Pro) and / or non-3GPP access technologies (such as Wi-Fi).

[0070] SMFs 183a and 183b can connect to AMFs 182a and 182b in CN 115 via the N11 interface. SMFs 183a and 183b can also connect to UPFs 184a and 184b in CN 115 via the N4 interface. SMFs 183a and 183b can select and control UPFs 184a and 184b, and configure traffic routing through UPFs 184a and 184b. SMFs 183a and 183b can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, or Ethernet-based.

[0071] UPF 184a and 184b can be connected via the N3 interface to one or more of the gNBs 180a, 180b, and 180c in RAN 113. These gNBs can provide WTRU 102a, 102b, and 102c with access to packet-switched networks (such as the Internet 110), for example, to facilitate communication between WTRU 102a, 102b, and 102c and IP-enabled devices. UPF 184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0072] CN 115 can facilitate communication with other networks. For example, CN 115 may include or be able to communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 115 and PSTN 108. Additionally, CN 115 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In an embodiment, WTRUs 102a, 102b, and 102c can be connected to DN 185a and 185b via UPF 184a and 184b through the N3 interface to UPF 184a and 184b and the N6 interface between UPF 184a and 184b and local data networks (DNs) 185a and 185b.

[0073] Given Figures 1A to 1D and Figures 1A to 1D The corresponding description can be performed by one or more emulation components / devices (not shown) that perform one or more or all of the functions described herein with respect to any of the following: WTRU 102a to 102d, base stations 114a to 114b, eNode-B 160a to 160c, MME 162, SGW 164, PGW 166, gNB 180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b, and / or any other components / devices described herein. An emulation device can be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device can be used to test other devices and / or simulate network and / or WTRU functions.

[0074] Simulation devices can be designed to perform one or more tests on other devices in laboratory and / or carrier network environments. For example, one or more simulation devices may perform one or more functions when fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices may perform one or more functions when temporarily implemented / deployed as part of a wired and / or wireless communication network. Simulation devices may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communication to perform tests.

[0075] One or more simulation devices may perform one or more functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, a simulation device may be used to test scenarios in a laboratory and / or an undeployed (e.g., tested) wired and / or wireless communication network to enable testing of one or more components. One or more simulation devices may be test equipment. Simulation devices may transmit and / or receive data using direct RF connections and / or wireless communication via an RF circuit system (e.g., which may include one or more antennas).

[0076] Layer 2 Mobility (LTM) was introduced in 3GPP Release 18 for wireless networks. Compared to conventional Layer 3 Mobility, it offers better handover latency and downtime.

[0077] Section 9.2.3.5 of 3GPP TS 38.300 v18.1.0 describes LTM as follows [with explanations of some abbreviations added in square brackets].

[0078] “ LTM works as follows: the gNB receives L1 measurement reports from the UE, and based on these reports, the gNB performs L1 measurement operations via... The MAC CE sends a cell handover command to change the UE's serving cell. The cell handover command instructs the gNB to prepare in advance and The LTM candidate configuration is provided to the UE via RRC (Radio Resource Control) signaling. Then, the UE switches according to the cell handover command. To the target configuration. The LTM process can be used to reduce mobility latency, as described in Annex G.

[0079] When configured by the network, TCI [transmission] can be activated for one or more cells that are different from the currently serving cell. [Configuration Instructions] Status. For example, LTM candidate cells can be activated in advance before any of these cells becomes the serving cell. The TCI status of the cells. This allows the UE to perform DL synchronization with these cells, thereby facilitating faster migration to these cells when a cell handover is triggered. One of the districts will switch to another cell.

[0080] When configured by the network, a UL TA procedure can be initiated for one or more cells that are different from the currently serving cell. (This is known as the early TA) process. If the cell has the same N as the currently serving cell... TA or N TA =0, then early TA is not needed. Acquisition Process. The network may request the UE to perform early TA acquisition for candidate cells before cell handover. Early TA Acquisition Process Triggered by the PDCCH [Physical Downlink Control Channel] command specified in Section 9.2.6, or by means of configuration as specified by RRC. This is achieved based on TA measurements of the UE. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the serving UE. The serving cell's gNB. When an LTM cell handover is triggered, the serving cell sends the TA value in the LTM cell handover command MAC CE. In the latter case, the UE performs TA measurements on the candidate cells after being configured by RRC, but the exact time when the UE performs the TA measurements is unknown. Depending on the UE implementation, the UE applies its own measured TA value and performs a no-RACH operation upon receiving a cell handover command. LTM. The network can also send the TA value in the LTM cell handover command MAC CE without performing early TA acquisition.

[0081] Depending on the availability of a valid TA value, the UE performs either RACH-less LTM or RACH-based LTM cell handover. If in If the cell handover command provides a TA value, the UE applies the TA value according to the network's instructions. This applies when UE-based TA measurement is configured but... If the TA value is not provided in the cell handover command, the UE will apply the TA value automatically (if available). Meanwhile, the UE will receive... After receiving the cell handover command, a no-RACH LTM cell handover is performed. If no valid TA value is available, the UE performs a RACH-based handover. LTM cell handover.

[0082] Regardless of whether the UE is configured for UE-based TA measurements for a specific candidate cell, it will still follow the guidelines including This requests a PDCCH command for the random access procedure of a candidate cell. This also applies to candidate cells where the UE can derive its TA value itself. In addition, regardless of whether the UE has already performed a random access procedure for a candidate cell, it will still follow the UE-based measurement... Quantity configuration (if network configuration).

[0083] For LTM without RACH, the UE uses configured authorization or dynamic authorization to access the target cell. In the LTM candidate configurations... Provide configuration authorization, and the UE selects the timing of the configuration authorization associated with the beam indicated in the cell handover command. Initiating After handover to the target cell's LTM cell, the UE begins monitoring the PDCCH on the target cell for dynamic scheduling. In the absence of a RACH... Before the LTM process is completed, if the UE does not have a valid PUCCH (Physical Uplink Control Channel) for the triggered SR, If the source is not specified, the UE should not trigger a random access procedure.

[0084] The following principles apply to LTM: - Maintain security keys during LTM cell handover; -Supports subsequent LTM.

[0085] LTM supports intra-gNB-DU and inter-gNB-DU mobility within and between gNB-CUs. LTM also supports intra-frequency and inter-frequency mobility. This includes mobility to inter-frequency cells that are not the current serving cell. LTM only supports licensed spectrum. It supports the following scenarios: - PCell changes in non-CA and non-DC scenarios; -Changes to PCell and SCell in the CA scenario; - In dual-connection scenarios, changes to PCell and MCG SCell, as well as changes to PSCell and SCG SCell within the SN, are not affected. MN. LTM is not supported for simultaneous changes to PCell and PSCell.

[0086] When the UE has already stored the LTM candidate configuration, the UE can also execute any L3 handover command sent by the network. " The LTM procedure defined in this file is... Figure 2 (As shown in “Figure 9.2.3.5.2-1. Signaling process for LTM” in this document, it will not be described in this article.)

[0087] However, as stated in 3GPP work item RP-234036: Compared to Layer 3 mobility, the mobility introduced in Rel-18 LTM also has many limitations. This Rel-19 work item is designed to eliminate several of these limitations.

[0088] LTM operation only supports mobility between cells within the same gNB (same CU). This depends on network deployment. This could significantly limit opportunities to use LTM. By enabling LTM operation between cells in different gNBs (i.e., between CUs), the network will... It allows you to reap the benefits of LTM for a larger number of switching operations.

[0089] Layer 3 mobility uses Layer 3 measurement reports, which support events that trigger measurement reports in UE assessments. Furthermore, it reduces signaling overhead compared to periodic measurement reports. L1 measurements used for LTM mobility do not support this event-triggered event. hair.

[0090] L1 measurements used in LTM processes are limited to SSB measurements. Extending L1 measurements to include CSI-RS can solve this problem. Limitations can be mitigated, and greater throughput can be expected on the target cell immediately after cell handover.

[0091] Layer 3 mobility has evolved over several versions. Conditional switching (CHO) and other conditional mobility procedures have been developed. (CPAC, SCPAC) to enable the process to be performed without prior signaling exchange with the source cell. Achieving high robustness. The LTM introduced in Rel-18 provides short interruption times, but it does not have the same water as the conditional L3 mobility process. Flat robustness. In Rel-19, enhancements should be specified so that the system can benefit from both high robustness and short interrupts. " In other words, the LTM introduced in Rel-18 provides short outage times, but does not have the same level of robustness as conditional L3 mobility procedures such as conditional handover (CHO) and other conditional mobility procedures (CPAC, SCPAC) that were developed to achieve high robustness by enabling the procedure to be performed without prior signaling exchange with the source cell.

[0092] However, to support conditional LTM with short downtime and robustness by avoiding prior signaling exchange with the source cell, the UE needs to be able to perform a No Random Access Channel (RACH) Chord. Typically, to support RACH-free handover, the UE needs uplink timing information (timing advance) and needs to be configured with authorization to transmit directly on the Physical Uplink Shared Channel (PUSCH), or needs to monitor the scheduling of the Physical Downlink Control Channel (PDCCH) on the target cell. This requires the target cell to be aware of the UE's presence (e.g., the target should be ready if the source issues a cell handover command). This can mean significant resource overhead, as all potential conditional LTM candidates should be prepared as long as the UE is configured for evaluation (and in this case, the UE will have to transmit RACH to let the target know of its presence), or configuration authorization needs to be reserved on all potential target cells and beams.

[0093] Therefore, it will be understood that resource-efficient conditions (LTM) with low interruption and latency are expected.

[0094] In short, as will be described in more detail later, according to this principle, the UE is configured to perform conditional LTM and determines the PUCCH resources on the target cell corresponding to the downlink beam measurement that satisfies the conditions for triggering LTM for the target cell, sends an indication to the target cell that a no-RACH conditional LTM handover is being performed using the PUCCH resources, and receives downlink control information (DCI) that schedules uplink PUSCH transmissions.

[0095] Figure 3 A flowchart of a conditional LTM method according to an embodiment of this principle is shown.

[0096] In step S302, the UE receives information from the network (e.g., the source cell, cell A) indicating the configuration of one or more LTM candidate cells. This information includes PUCCH resources (e.g., scheduling request (SR) resources) associated with downlink beams (e.g., synchronization signal blocks) and conditions for performing LTM execution (i.e., LTM triggering).

[0097] LTM triggering can be based on any of those detailed in the “LTM Execution Triggering” section below. PUCCH resources may include elements in the uplink control information (UCI) used for CHO indication (in addition to SR, Channel Quality Indicator (CQI), etc.), or may use SRs with specific resource configurations. This configuration may include Type 2 Configuration Grant (CG) on the target associated with the downlink beam or PUCCH resource.

[0098] In step S304, the UE performs measurements on downlink beams from one or more configured LTM candidates (i.e., target cell, cell B), evaluates these measurements, and determines (e.g., calculates) the timing advance (TA) value of the target cell (e.g., by receiving a Media Access Control (MAC) element (MAC CE) or by performing UE-based measurements). The TA can be determined in different ways, as described in the “Early TA Acquisition” section below; in short, the TA can be a fixed value in the RRC configuration (e.g., if target cells are located in the same physical location), provided in the MAC CE, transmitted by the target cell to the source cell after transmission to the UE, or estimated by the UE based on measurements.

[0099] If the LTM candidate cell meets the configuration conditions for performing LTM, in step S306, the UE determines the PUCCH resource based on the best quality downlink beam (i.e., the beam that causes the conditions to be met).

[0100] In step S308, the UE uses the determined PUCCH resource and the determined TA to send an indication. This indication may include, for example, the Measurement Event ID or other information in the UCI. The PUCCH resource is specific to the UE's completion of the Conditional LTM, and therefore can implicitly indicate the Conditional LTM.

[0101] In step S310, the UE receives PDCCH scheduling information. The beam information of the PDCCH is implicitly known, for example, due to its quasi-co-occurrence (QCL) relationship with the optimal beam corresponding to the determined PDCCH resource.

[0102] In step S312, the UE sends a message indicating that the RRC reconfiguration is complete on the indicated PUSCH resource (e.g., indicated by CG, pre-configured by RRC or dynamic authorization, or received in DCI on PDCCH).

[0103] This method enables RACH-free conditional LTM handover without requiring signaling on the source cell or reserving dedicated preamble or PUSCH resources on the target cell. The UE obtains uplink timing before attempting conditional handover. This method can provide lower latency and better robustness, as well as faster beamfinding when CSI-RS can be measured.

[0104] Execute LTM In this document, "execute LTM" or "execute LTM procedure" refers to executing... Figure 3 The steps described herein. Specifically, early synchronization with one or more candidate cells is performed in the DL and / or UL, L1 measurement and reporting are performed on one or more candidate cells, and handover is performed between candidate cells (i.e., a handover is executed). The UE may move / handover between multiple candidate cells during this process.

[0105] Candidate Community Set One or more candidate cell sets can be groups of more than one RRC configuration, which correspond to the handover configuration of one or more candidate SpCells and optional SCells. This can be modeled or received as one or more complete RRC reconfiguration messages, one or more cell group configurations, or one or more cell configurations. Each candidate cell configuration may include a candidate configuration identifier, and each candidate cell group may include a candidate cell group identifier. If the grouping is performed at an RRC, the handover between different candidate cell sets may include updating the serving cell index or candidate configuration index used in L1 and MAC signaling to reference a specific index (e.g., the MAC CE that triggers the reconfiguration may include a candidate configuration index to inform the UE which cell to perform the reconfiguration for).

[0106] One or more candidate cell groups can be configured as a single list or group of candidate cells at the RRC. Grouping can occur during the early synchronization or LTM execution phase, rather than during the configuration phase. This means that the candidate cell set can be viewed as a single group about the RRC configuration list or group, and the cells selected for performing early synchronization, L1 measurements, and LTM execution depend on further grouping into multiple subsets of the entire candidate cell list. In other words, grouping is not performed at the RRC using candidate configuration identifiers, but rather as part of the early synchronization or LTM execution process.

[0107] Throughout this specification, when referring to LTM candidate configurations, this can apply to any type of pre-configured cell information. For example, a UE can be configured with one or more conditional reconfigurations, such as Conditional Handover (CHO), Conditional PSCell Addition (CPA), or Conditional PSCell Change (CPC), which are effective before and / or after a cell change, or in certain cells.

[0108] L1 measurement L1 measurements can include measurements of Reference Signal Received Power (RSRP), Received Signal Strength Indicator (RSSI), etc., performed by the UE, beam, group of cells, or group of beams in a cell. Such L1 measurements can be similar to L3 measurements reported in Radio Resource Management (RRM), but differ in filtering, the reference signal used for measurement, and the reporting mechanism.

[0109] L1 measurements can also be used for RRM reports. In this document, measurement generally refers to L1 measurement for LTM. However, in some embodiments, measurement may also refer to RRM / L3 measurement as well as other measurements (e.g., speed, position, altitude, traffic volume, etc.).

[0110] LTM cell handover can also be applied to any type of handover execution. In this document, LTM cell handover refers to L1 / 2 triggered mobility, whereby a pre-configured RRC configuration is applied when the UE receives an indication using MAC CE or when certain conditions are met at the UE. However, some embodiments may also be applicable to RRC reconfiguration, RRC conditional reconfiguration, and any other type of mobility procedure.

[0111] LTM candidate configurations The gNB (e.g., the CU in a CU / DU split architecture — note: RRC resides in the central unit (CU)) uses RRC signaling to configure potential LTM candidates. In one embodiment, the UE uses an RRC reconfiguration message to receive information indicating the LTM candidate configuration, for example, in Figure 2 During the “LTM Preparation” phase shown, the UE can store LTM candidate configurations for later application when it receives an indication to perform a cell handover using L1 / 2 signaling (e.g., MAC CE), for example, in Figure 2 The “LTM Execution” phase is shown.

[0112] In one embodiment, the configuration of potential LTM candidates may include a candidate set, such as a first set that may be suitable for a first path (e.g., the UE turns left and takes the first path) and a second set that may be suitable for a second path (e.g., the UE turns right and takes the second path).

[0113] In one embodiment, some or all of the candidate set information is broadcast in the system information, and the UE enables the pre-configuration of these broadcast configurations when it receives an indication in dedicated signaling (e.g., RRC reconfiguration) that relates to the broadcast of one or more configurations (e.g., using an index or identifier).

[0114] In one embodiment, the configuration may include all or a subset of potential cells in a specific region (e.g., all cells belonging to the CU currently connected to the UE or cells within a specific geographic region). These cells may still be detected or measured by the UE, but are configured in advance. In one embodiment, after the initial configuration of the LTM candidate configuration, the UE may receive updates to the configuration to modify, add, remove, or replace any part of the LTM candidate configuration.

[0115] In one embodiment, the UE may receive an indication to enable or disable some or all of the LTM configurations. For example, if it is predicted that using L3 (e.g., RRC measurement reporting, RRC reconfiguration, conditional reconfiguration) will better handle UE mobility, LTM may be disabled. On the other hand, if it is predicted that LTM will be better suited to UE mobility, LTM may be enabled (e.g., previously configured and disabled LTM configurations may be re-enabled).

[0116] In one embodiment, the configuration may be based on a prediction model that is within and determined by the network (e.g., gNB). For example, the prediction may be based on the most likely path for the UE determined by the NW prediction model.

[0117] In some embodiments, the candidate cell configuration includes all or part of the information required to complete the reconfiguration (e.g., handover) of the candidate cell, such as channel configuration (e.g., Physical Random Access Channel (PRACH), PDCCH, PDSCH), CORESET, Bandwidth Part (BWP), security parameters, L2 parameters (e.g., MAC, RLC, Packet Data Convergence Protocol (PDCP)), radio bearer configuration, etc.

[0118] LTM Execution Trigger In this article, LTM execution trigger refers to the conditions used to execute LTM (e.g., condition switching trigger or measurement report trigger), which are configured or indicated by the network to the UE or estimated / determined by the UE.

[0119] Triggers can be based on one or more of the following: time (e.g., absolute or relative time measurement at the UE, system frame number (SFN), and subframe number), radio quality measurements or predicted radio quality of one or more of the serving or target cells (e.g., RSRP (beam or cell), Reference Signal Received Quality (RSRQ) (beam or cell), cri-RI-PMI-CQI, cri-RI-i1, cri-RI-i1-CQI, cri-RI-CQI, cri-RSRP, ssb-Index-RSRP, and cri-RI-LI-PMI-CQI), location (e.g., area (e.g., defined by a reference point and radius) or coordinate range, and a distance threshold from the reference location), L3 measurement events (e.g., event A1 (service becomes lower than a threshold)). Events A1, B2 (service becomes worse than the threshold), A3 (neighbor becomes better than SpCell by offset), A4 (neighbor becomes better than the threshold), A5 (SpCell becomes worse than threshold 1, and neighbor becomes better than threshold 2), A6 (neighbor becomes better than SCell by offset), B1 (inter-RAT neighbor becomes better than the threshold), and B2 (PCell becomes worse than threshold 1, and inter-RAT neighbor becomes better than threshold 2), L1 measurement events or conditions (e.g., any defined event that uses L1 beam measurements to assess whether a criterion or condition is met), predicted events (e.g., using any of the measurements previously listed in this paragraph), and explicit indications from the network (e.g., the UE may base its decisions on explicit indications received from the network, such as MAC addresses). (CE) to enable CSI reporting, and then perform LTM cell handover when a second MAC CE is received from the network, measured, predicted or estimated throughput, error rate, buffer state or QoS parameters, and evaluation metrics (e.g., trigger time, hysteresis, offset (e.g., radio quality measurement offset) or measurement filter configuration).

[0120] Triggers may include one or more conditions that allow the UE to perform actions related to LTM. For example, the UE may perform one or more of the following procedures.

[0121] Early TA Acquisition In a first embodiment, the UE can trigger a RACH to the target LTM cell. In a first example, the UE can receive the TA value, for example, from the target cell or via the source cell in a Random Access Response (RAR). In a second example, the UE can receive the TA value in a MAC CE that triggers cell handover. In a third example, if no RAR / MAC CE is received, the UE can perform a power ramp and preamble retransmission to the target.

[0122] In the second embodiment, the UE can obtain the TA value of the candidate LTM cell through measurement and trigger it upon completion. The UE can support and be configured to perform UE-based TA measurement, thereby obtaining the TA value of the candidate cell through measurement.

[0123] Close CSI Report The UE can be allowed or required to disable CSI reporting to reduce uplink reporting overhead. CSI reporting can be reduced rather than disabled (e.g., reducing the number of cell or beam reports, or reducing the reporting frequency). The UE can resume CSI reporting when the conditions are no longer met.

[0124] Perform LTM cell handover There are conditions or criteria that allow a UE to trigger LTM cell handover.

[0125] Monitoring PDCCH on the target cell The UE can be configured to monitor the scheduling PDSCH on the target cell or to indicate one or more actions (e.g., initiating a cell handover procedure) on the target cell via DCI.

[0126] Execute BFR or RLM on the target cell The UE can be configured to monitor beam fault detection (BFD) resources on the target cell or perform radio link monitoring (RLM) on the target cell during the window period.

[0127] Activate or deactivate certain SCells The UE can be configured with one or more specific SCells that should be active or inactive during the window.

[0128] No RACH CHO and early TA acquisition To enable conditional handover without RACH (CHO), the UE does not need to send a random access preamble or perform a random access procedure on the target cell after reconfiguration is triggered. Instead, the UE uses the already provided TA to perform PDCCH reception and uplink transmission. The UE can perform an early TA acquisition procedure with the candidate cell before receiving the cell handover command or before triggering the conditional reconfiguration.

[0129] In one embodiment, early TA acquisition can be performed using contention-free random access (CFRA) triggered by a PDCCH command from the source cell, after which the UE can send a preamble to the candidate cell. Information identifying the allocated CFRA resources can be indicated in the PDCCH command to enable shared preamble resources among multiple UEs in the RRC configuration. The source gNB dynamically indicates which UE uses the resources at any given time.

[0130] In one embodiment, an early TA acquisition can be performed upon receiving a MAC CE instructing the execution of a RACH transmission on the target cell.

[0131] In one embodiment, this can be performed by sending a contention-based random access (CBRA) preamble.

[0132] In one embodiment, and to minimize data interruption in the source cell due to CFRA for candidate cells, the UE does not receive RAR at all. For example, if the preamble is not received, the source cell can use another PDCCH command to trigger preamble retransmission / power ramp. In this case, TA can be provided from the target cell to the source cell and to the UE in the MAC CE that triggers cell handover or enables conditional LTM for one or more target cells.

[0133] In one embodiment, the UE may receive the TA value from the target cell in a Random Access Response (RAR). In another embodiment, the UE may receive the TA value from the source cell in a Random Access Response (RAR). If the UE does not receive a RAR in response to transmitting the preamble (e.g., within a specified time), the UE may use higher transmission power to retransmit the preamble.

[0134] In one embodiment, the UE can store the received TA value for later use when a reconfiguration trigger occurs. The UE can store the TA value for a limited time period (e.g., a validity timer) and can trigger or be triggered to perform a new TA acquisition process when the time expires.

[0135] In one embodiment, the UE may receive and / or store multiple TA values, each associated with more than one cell.

[0136] In one embodiment, the UE can obtain the TA value of the target cell by measurement.

[0137] If the UE has already stored a valid TA value for the candidate cell when a cell handover to the candidate cell is triggered (either by the NW using an explicit cell handover command or by the UE when the triggering conditions are met), the UE performs a handover without RACH. For example, the UE may perform LTM (e.g., applying a pre-configured RRC configuration to a new SpCell) when it determines that the measured radio quality of the target cell is above a threshold.

[0138] The UE can support and be configured with UE-based TA measurements, thereby obtaining the TA value of the candidate cell through measurement. If the cell handover command does not include the TA value, and the UE has already obtained the TA measurement value, then if the UE has been configured to perform a RACH-free handover via RRC, the UE will perform a RACH-free handover.

[0139] TA effectiveness The UE may determine that a received / stored TA is valid based on at least one of the following: a validity timer pre-configured for use with the TA value; a validity timer received with the TA value; conditions regarding the DL cell timing of the received / stored TA with respect to the source cell and the DL cell timing of the candidate cell (e.g., the UE may consider the TA valid when the difference between the DL cell timings of the source cell and the candidate cell is less than a configured threshold; the UE may consider the TA valid when the difference between the DL cell timings of the source cell and the candidate cell is within a configured range); and conditions regarding the DL cell timing of the candidate cell (e.g., if the TA is received...). The following conditions apply: (1) If the difference between the DL cell timing of the target cell and the current DL cell timing of the same target cell does not exceed a value / range of a specific configuration, the UE can consider the TA valid; (2) Conditions regarding UE mobility (e.g., if the UE is static (does not move) or moves below a speed threshold of a specific configuration, the UE can consider the TA valid); (3) Conditions regarding UE location (e.g., if it has been determined that the UE's location has not changed beyond a threshold of a specific configuration (e.g., x meters) after the TA is acquired); and (4) Conditions based on the availability of UE TA measurements and cell quality or beam quality measurements being above a threshold.

[0140] UE-based TA calculation report In one embodiment, when the TA based on the UE is acquired, the UE may trigger an event, and when the TA has been acquired based on the UE measurement value, it may send a MAC CR, CSI or other uplink indication to the source cell or candidate cell, for example.

[0141] In one embodiment, the UE may trigger an event based on a measurement criterion (e.g., RSRP or any of the other triggers listed above) and may only send a corresponding report if a TA has already been acquired (e.g., the TA is available due to a previous UE-based TA acquisition). In one embodiment, a report or LTM execution trigger caused by a measurement-based event or trigger may be delayed until the UE-based TA acquisition is complete. That is, a measurement event (e.g., beam RSRP exceeding a threshold) may cause the UE to initiate a UE-based TA acquisition, and the trigger is executed when the measurement event is met and the TA has been acquired.

[0142] In one embodiment, in response to receiving a report from the UE (e.g., a UE-based TA acquisition has been performed and beam or cell measurements are above a threshold), the network may, for example, send a command to the UE in the MAC CE to enable conditional LTM assessment. The UE may receive the command, and based on the content of the command, may enable conditional LTM assessment based on the determination of one or more measurement conditions.

[0143] Beam refinement is performed on the target cell before or during handover. The UE can perform beam refinement on the target cell before or during handover and before accessing the target cell. This allows the UE to first perform SSB resource measurements, and then select a subset of CSI-RS resources to measure based on the SSB measurements (e.g., based on the best measured SSB). The UE can then perform measurements on the selected subset of CSI-RS resources and determine the best CSI-RS resources. The selected best CSI-RS resources can be indicated before (e.g., for the source cell) handover or at initial access (e.g., for the target cell), rather than only after connection to the target cell is completed.

[0144] Report CSI-RS measurements The UE can report measurements of a subset of CSI-RS resources to the source cell using a CSI report on the PUCCH. Alternatively, this report can be sent using MAC CE, RRC measurement reports, or any other type of uplink signaling. The report may contain one or more of the following: RSRP (beam or cell), RSRQ (beam or cell), cri-RI-PMI-CQI, cri-RI-i1, cri-RI-i1-CQI, cri-RI-CQI, cri-RSRP, ssb-Index-RSRP, and cri-RI-LI-PMI-CQI.

[0145] Enable CSI-RS measurement The UE can determine a subset of CSI-RS to be measured based on triggers. For example, the UE can determine this based on a pre-configured association between SSB and CSI-RS resources (e.g., configured by RRC). The UE can determine the optimal SSB based on an SSB indication or based on the SSB measurement performed.

[0146] A subset of CSI-RS can be explicitly indicated in the random access response (e.g., using a pointer to one of multiple subsets) or implicitly indicated (e.g., the UE enables a subset of CSI-RS based on the reported or indicated SSB when a RAR is received). Alternatively, when the UE receives a PDCCH command that triggers early TA acquisition, the UE can enable a subset of CSI-RS measurements in response to the PRACH preamble transmission for TA acquisition, including a RAR or MAC CE activation configuration authorization for the TA.

[0147] CSI-RS measurements can be temporarily configured. For example, the UE can activate CSI-RS measurements within a specific time period or a specific number of reports that can be configured or predefined. For example, the UE can deactivate CSI-RS measurements when the optimal SSB changes, or when the SSB or CSI-RS measurement value is below a threshold.

[0148] Configure authorization activation The UE can receive an activation grant instruction from either the source cell or the target cell. This could be, for example, a type 2 configuration grant, whereby the first cell configures the grant and the second cell activates the grant, an explicit grant (a direct indication of the grant to be used), or a pointer to one or more pre-configured grants (e.g., previously configured by RRC).

[0149] The authorization instruction can be a pointer to a configuration authorization corresponding to the reported SSB, or it can be a set of configuration authorizations corresponding to multiple CSI-RS associated with the reported SSB.

[0150] Configuring authorization activation can be received in a PDCCH command (e.g., triggering TA acquisition), a MAC CE (e.g., triggering LTM), or a RAR (e.g., received from a source or destination, containing a TA value for RACH-free handover).

[0151] UEs can proactively activate configuration authorization based on conditions (e.g., any of the LTM execution triggers already listed).

[0152] Determine the PUCCH resources sent on it. In addition to LTM candidate configuration and downlink measurement resource configuration (e.g., SSB, CSI-RS), the UE may also be configured, for example, in an RRC reconfiguration message, with PUCCH resources for one or more LTM candidates. The PUCCH resources for LTM candidates can be configured to be associated with one or more downlink measurement resources. For example, one or more PUCCH resources can be associated with each of the downlink measurement resources, allowing at least one PUCCH resource to be selected based on identifying the best measurement resource.

[0153] The UE can determine one or more optimal beams (e.g., SSB, CSI-RS measurements) in candidate LTM cells based on downlink measurements. The UE can then select the corresponding PUCCH resource to use based on its association with the optimal measurement beam. In some embodiments, the UE autonomously selects the PUCCH resource based on the optimal measurement beam. In some embodiments, the UE reports measurements to the source cell (e.g., CSI report, MAC CE, or RRC measurement report) and then receives an indication of the target beam (e.g., in the MAC CE). Based on the indicated target beam, the UE can then select the associated PUCCH resource. The indication of the PUCCH resource can be explicitly provided by the source cell, for example, in the MAC CE that provides the TA value to the UE. The UE can determine the PUCCH to use based on a PDCCH command from the source cell (e.g., a PDCCH command instructing the UE to perform a RACH transmission to the target cell for TA measurement may include an indication of a downlink beam, which may be associated with a PUCCH resource).

[0154] When the conditions for handover are met, the UE can then transmit on the determined PUCCH resource. This allows the target gNB to know that the conditions for cell handover have been met, and for which beam the gNB should schedule further transmissions. The gNB can then respond and send a DCI to the UE. The UE can receive the DCI, which activates configuration authorization (e.g., Type 2 CG), or the UE can be explicitly scheduled to perform transmissions and / or receptions (e.g., by sending an RRC reconfiguration complete message on the PUSCH).

[0155] PUCCH configuration can be a new type of uplink control information specifically used to indicate that a condition for LTM triggering has been met. The uplink control information may include a payload portion indicating information related to the event, such as the event ID, source cell, cell or beam above a threshold (e.g., 1 bit per beam, measured as above the configured threshold), timing information (e.g., synchronization information), or cell quality information (e.g., the CQI of the target cell, or the beam RSRP of one or more optimal beams).

[0156] PUCCH can alternatively be a scheduling request using one of the known formats and with specific resource configurations. PUCCH SR can be multiplexed with other uplink control information; for example, SR can be multiplexed with CQI transmission.

[0157] In some embodiments, the association between PUCCH resources and downlink beams can be dynamically controlled. For example, a UE may receive a configuration of multiple potential associations for a particular cell (e.g., multiple SSBs associated with the PUCCH) and then receive one or more indications (e.g., in a MAC CE) to indicate which are active or enabled at any given time.

[0158] Now we will provide information about Figure 3 Further details of the method shown.

[0159] In step S302, the UE receives configuration information from the network (e.g., BS). After receiving the information, the UE can configure itself accordingly.

[0160] For example, this information can be received in an RRC reconfiguration message. This information can identify an LTM candidate. It can also identify the PUCCH resource (e.g., SR resource) associated with a downlink beam (e.g., SSB) and the conditions for performing LTM execution (e.g., any triggers described in "LTM Execution Trigger"). In some embodiments, the event ID associated with the conditional reconfiguration determines the PUCCH resource to be selected (e.g., if more than one event is configured for conditional reconfiguration, the UE can select the associated PUCCH).

[0161] PUCCH resources may additionally depend on one or more of the following: timing information (e.g., the SFN of the target cell, the time to satisfy an event, or, in the case where multiple events need to be satisfied, the time between satisfying the first and second events (e.g., the first event may be defined based on cell quality and the second event may be defined based on beam quality)), priority associated with the cell or beam, priority associated with the ongoing service or data, latency or throughput requirements, CG availability, and explicit indications in the DCI or MAC CE (e.g., pre-configured PUCCH resources and dynamic indications of which resources are enabled or active).

[0162] In step S304, the UE measures the downlink beam, evaluates these measurements, and determines the TA value of the target cell. Based on the configuration in step S302, the UE measures the configured candidate cells and / or beams (e.g., as described in “LTM Execution Triggering”). The TA value can be determined as described in “No RACH CHO and Early TA Acquisition”.

[0163] If the LTM candidate cell meets the configuration conditions for performing LTM, i.e., if the trigger condition is met, in step S306, the UE determines the PUCCH resource based on its configuration. As mentioned, the PUCCH resource may be associated with the beam determined to have the best signal quality (e.g., beam RSRP).

[0164] In step S308, the UE uses the determined PUCCH resources to send an indication. This indication can convey that the conditions for LTM cell handover have been met and indicate the optimal beam and the met conditions to the network (e.g., BS and / or gNB).

[0165] In step S310, the UE receives an indication on the PDCCH. For example, the received indication may indicate PDCCH scheduling information. Based on the PUCCH indication in step S308, the UE monitors and receives indications on the PDCCH. The PDCCH indication may include one or more of the following: dynamic scheduling providing authorization for transmitting the RRC completion message, type 2 CG activation, and beam refinement indications (e.g., one or more CSI-RS that are measured and reported before or during the transmission of the handover completion message).

[0166] In step S312, the UE sends a message indicating that the RRC reconfiguration is complete on the indicated PUSCH resource (CG or dynamic).

[0167] In some embodiments, if the authorization is sufficient, the UE can cancel the SR (e.g., for subsequent transmissions after an RRC completion message, for transmissions of RRC completion information, or for activation of the authorization configuration) based on the received PDCCH for scheduling uplink transmissions.

[0168] In some embodiments, more than one beam or cell can be conditionally triggered (e.g., if a triggering condition is met when the measured signal quality is above a threshold). In this embodiment, the UE may attempt to send an SR (or other PUCCH indication) to a cell (e.g., the best cell or the cell with the best beam).

[0169] In some embodiments, the UE may determine that the cell being attempted has failed (e.g., due to no response within a certain time period), and may then continue sending SRs to another cell (e.g., the second best cell).

[0170] In some embodiments, if the UE does not receive a response on the first cell, the UE may transmit on PUCCH resources corresponding to multiple (e.g., all) of other cells or beams that meet the conditions.

[0171] In some embodiments, the UE may transmit to one or more targets based on certain criteria, such as relative measurements (e.g., if a cell or beam has a measured signal quality that is better than the second best cell relative quality threshold, the UE may transmit to only one cell; otherwise, the UE may transmit on more than one cell), or the periodicity of the corresponding PUCCH resource (e.g., if the PUCCH resource is configured with a relatively long periodicity, the UE may transmit on the SR resource faster depending on the cells on which it is available).

[0172] In some embodiments, the UE may monitor multiple PDCCH resources corresponding to multiple PUCCH resources transmitted by the UE thereon.

[0173] In some embodiments, the UE may attempt a PUCCH transmission once before determining that the no-RACH conditional handover (HO) has failed, or attempt it a limited number of times (e.g., N times), or until the timer expires, and thus instead send a random access preamble.

[0174] In some embodiments, the UE may be configured with additional conditions for selecting whether to perform a RACH-free CHO, a RACH-based CHO, or to report an L1 measurement report to the source cell. For example, a RACH-free CHO is performed if the target cell quality is above a threshold and / or a TA value is available; conversely, a RACH-based CHO is performed if it is below the threshold.

[0175] In some embodiments, the UE may determine whether to perform LTM without RACH or another mobility method based on traffic volume or the QoS characteristics of the configured service.

[0176] In some embodiments, the TA validity time threshold determines whether to send on PUCCH or RACH (e.g., if the TA is about to expire, a RACH-based handover is used).

[0177] In some embodiments, the selected PUCCH resources can be configured on the source cell. That is, different PUCCH resources correspond to different target cells and beams, and the UE indicates to the source cell that the conditions have been met before attempting to receive PDCCH or perform PUSCH transmission using CG on the target cell.

[0178] In some embodiments, the UE indicates to the source cell the use of PUCCH resources or MAC CE, and receives activation of configuration grant (e.g., Type 2) in the target cell from the source cell before performing a cell handover. In some solutions, the UE may determine whether to transmit on PUCCH resources on the target or whether to transmit an indication on the source cell based on conditions (e.g., measured signal quality of the source cell). In some solutions, once configuration grant is selected or activated on the target / optimal beam, the UE may determine whether the configuration grant is within a specific time. If the configuration grant is determined to be within a specific time, the configuration grant can be used to transmit reconfiguration completion. If the configuration grant is not within a specific time, the source cell may be indicated RRC completion (e.g., using PUCCH resources or MAC CE).

[0179] In some embodiments, a PUCCH resource may correspond to multiple downlink beams or cells. For example, a PUCCH resource in a cell belonging to a DU may be used to indicate the beam quality of any cells belonging to that DU. In this case, the PUCCH indication will include an explicit indication of the best beam or cell.

[0180] In some embodiments, multiple thresholds that need to be met before certain steps can be performed. For example, a first threshold can be used to determine whether to send a PUCCH indication to the target cell, which can activate configuration authorization. A second threshold can be used to determine when cell handover is complete and transmission is performed using configuration authorization.

[0181] Although features and elements have been provided above in specific combinations, those skilled in the art will understand that each feature or element may be used alone or in any combination with other features and elements. This disclosure is not limited in its description of the specific embodiments described herein, which are intended as illustrative of various aspects. Many modifications and variations may be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Any element, action, or instruction used in the description of this application should not be construed as critical or essential to the invention unless expressly provided so. In addition to those listed herein, functionally equivalent methods and apparatus within the scope of this disclosure will be apparent to those skilled in the art based on the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims and the full scope of equivalents conferred by such claims. It should be understood that this disclosure is not limited to the specific methods or systems described herein.

[0182] For simplicity, the foregoing embodiments have been discussed in terms of terminology and construction of infrared-capable devices (i.e., infrared transmitters and receivers). However, the embodiments discussed are not limited to these systems, but can be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0183] It will also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the term “video” or the term “image” may mean any of a snapshot, a single image, and / or multiple images displayed on a time basis. As another example, when referred to herein, the term “user equipment” and its abbreviation “UE,” the term “remote,” and / or the term “head-mounted display” or its abbreviation “HMD” may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of many embodiments of a WTRU; (iii) a device, particularly configured with some or all of the structural and functional aspects of a WTRU, having wireless and / or wired capabilities (e.g., tetherable); (iv) a device configured with fewer than all of the structural and functional aspects of a WTRU having wireless and / or wired capabilities; or (iv) similar devices. References herein Figures 1A to 1D Details of an example WTRU are provided, which may represent any WTRU described herein. As another example, various disclosed embodiments herein are further illustrated. The above text and The following text Described as utilizing a head-mounted display. Those skilled in the art will recognize that devices other than head-mounted displays can be used, and some or all of the embodiments of this disclosure and its various disclosures can be modified accordingly without excessive experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adaptive, realistic experience.

[0184] Furthermore, the methods described herein can be implemented in computer programs, software, or firmware incorporated into computer-readable media for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, 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 discs and digital multifunction disks (DVDs). The processor associated with the software can be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

[0185] Variations of the methods, apparatus, and systems provided above are possible without departing from the scope of the invention. Given the wide variety of embodiments that can be applied, it should be understood that the illustrated embodiments are merely examples and should not be construed as limiting the scope of the appended claims. For example, embodiments provided herein include handheld devices that may include or be used with any suitable voltage source (such as a battery) that provides any suitable voltage.

[0186] Furthermore, in the embodiments provided above, a processing platform, computing system, controller, and other devices including a processor are mentioned. These devices may include at least one central processing unit (“CPU”) and memory. According to the practice of those skilled in the art of computer programming, references to actions and symbolic representations of operations or instructions can be performed by various CPUs and memories. Such actions and operations or instructions may be referred to as “execution,” “computer execution,” or “CPU execution.”

[0187] Those skilled in the art will understand that the actions and symbols representing operations or instructions include the CPU's manipulation of electrical signals. An electrical system represents a data bit, which can cause a final conversion or reduction of an electrical signal and is maintained in a memory location within a storage system, thereby reconfiguring or otherwise altering the CPU's operation and other signal processing. The memory location maintaining the data bit is a physical location having specific electrical, magnetic, optical, or organic characteristics corresponding to or representing the data bit. It should be understood that the embodiments are not limited to the platforms or CPUs described above, and other platforms and CPUs may support the provided methods.

[0188] Data bits can also be maintained on a computer-readable medium, including disks, optical disks, and any other CPU-readable volatile (e.g., random access memory (RAM)) or non-volatile (e.g., read-only memory (ROM)) mass storage system. The computer-readable medium can include cooperative or interconnected computer-readable media that exist only on the processing system or are distributed across multiple interconnected processing systems that may be located locally or remotely on the processing system. It should be understood that the embodiments are not limited to the above-described memories, and other platforms and memories may support the provided methods.

[0189] In the illustrative embodiments, any operations, processes, etc., described herein can be implemented as computer-readable instructions stored on a computer-readable medium. These computer-readable instructions can be executed by a processor of a mobile unit, network element, and / or any other computing device.

[0190] The differences between the hardware and software implementations of various aspects of the system are minor. The use of hardware or software is typically (but not always, as the choice between hardware and software can become important in certain situations) a design choice representing a cost-efficiency trade-off. Various vehicles (e.g., hardware, software, and / or firmware) may exist to implement the processes and / or systems and / or other technologies described herein, and the preferred vehicle can vary depending on the context in which the processes and / or systems and / or other technologies are deployed. For example, if the implementer determines that speed and accuracy are most important, then the implementer may choose the primary hardware and / or firmware vehicle. If flexibility is most important, then the implementer may choose the primary software implementation. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware.

[0191] The foregoing detailed description has illustrated various embodiments of the apparatus and / or processes using block diagrams, flowcharts, and / or examples. Those skilled in the art will understand that each function and / or operation within such block diagrams, flowcharts, or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware, or virtually any combination thereof, with respect to the inclusion of one or more functions and / or operations in such block diagrams, flowcharts, or examples. In embodiments, several portions of the subject matter described herein may be implemented via application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integration formats. However, those skilled in the art will recognize that all or part of some aspects of the embodiments disclosed herein can be equivalently implemented in integrated circuits as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or virtually as any combination thereof, and that designing circuit systems and / or writing code for software and / or firmware in accordance with this disclosure will be entirely within the skill of those skilled in the art. Furthermore, those skilled in the art will understand that the mechanisms of the subject matter described herein can be distributed as a program product in various forms, and the illustrative examples of the subject matter described herein apply regardless of the specific type of signal-bearing medium used for actual distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable media, such as floppy disks, hard disk drives, CDs, DVDs, digital magnetic tapes, computer memory, etc.; and transmission media, such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.).

[0192] Those skilled in the art will recognize that devices and / or processes are typically described in the manner set forth herein, and that engineering practice is subsequently used to integrate such described devices and / or processes into data processing systems. That is, at least a portion of the devices and / or processes described herein can be integrated into a data processing system through a reasonable number of experiments. Those skilled in the art will recognize that a typical data processing system typically includes a system unit housing, a video display device, memory such as volatile and non-volatile memory, a processor such as a microprocessor and a digital signal processor, a computing entity such as an operating system, drivers, a graphical user interface and application processes, one or more interactive devices such as a touchpad or screen, and / or a control system including feedback loops and control motors (e.g., feedback for sensing position and / or speed; control motors for moving and / or adjusting the number and / or quantity of components). A typical data processing system can be implemented using any suitable commercially available components, such as those commonly found in data computing / communication and / or network computing / communication systems.

[0193] The topics described herein sometimes illustrate different components that are included within or connected to different other components. It should be understood that such depicted architectures are merely examples, and many other architectures that achieve the same functionality can actually be implemented. Conceptually, any arrangement of components used to achieve the same functionality is effectively “associated” such that the desired functionality can be achieved. Therefore, any two components combined herein to achieve a particular functionality can be considered “associated” with each other such that the desired functionality is achieved regardless of the architecture or intermediate components. Similarly, any two such associated components can also be considered “operably connected” or “operably linked” to each other to achieve the desired functionality, and any two components that can be suchly associated can also be considered “operably linked” to each other to achieve the desired functionality. Specific examples of operablely linked components include (but are not limited to) physically matable and / or physically interactive components, and / or wirelessly interactive and / or logically interactive components.

[0194] Regarding the use of virtually any plural and / or singular terms herein, those skilled in the art can convert plural to singular and / or singular to plural as appropriate to the context and / or application. For clarity, various singular / plural permutations may be explicitly described herein.

[0195] Those skilled in the art will understand that, generally, the terms used herein and especially in the appended claims (e.g., the body of the appended claims) are intended to be largely "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including but not limited to," etc.). Those skilled in the art will further understand that if an intention is to express a specific number of introduced claim statements, then such intention will be explicitly stated in the claims, and without such a statement, such intention does not exist. For example, the term "single" or similar language may be used where only one item is desired. To aid understanding, the appended claims and / or the description herein may include the use of introductory phrases "at least one" and "one or more" to introduce multiple claim statements. However, the use of such phrases should not be construed as implying that a claim statement introduced by the indefinite article "a" or "an" will limit any particular claim including such an introduced claim statement to an embodiment that includes only one such statement, even if the same claim includes the introductory phrase "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim statements. Furthermore, even if a specific number of introduced claim statements are explicitly stated, those skilled in the art will recognize that this statement should be interpreted as meaning at least the number stated (e.g., simply stating "two statements" without other modifiers implies at least two statements or two or more statements). Furthermore, in cases where conventions such as "at least one of A, B, and C" are used, this structure is generally intended to represent a convention that a person skilled in the art would understand (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C). In cases where conventions such as "at least one of A, B, or C" are used, a person skilled in the art will generally understand that such a meaning is expected in the sense of the convention (e.g., "a system having at least one of A, B, or C" will include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C). A person skilled in the art will further understand that any transitional words and / or phrases (whether in the specification, claims, or drawings) that actually give two or more alternatives should be understood to be intended to include the possibility of including one, any, or both of the items.For example, the phrase “A or B” will be understood to include the possibility of “A” or “B” or “A and B”. Furthermore, the term “any” followed by a list of multiple items and / or multiple categories of items as used herein is intended to include “any,” “any combination,” “any multiple,” and / or “any combination of multiple” individually or in combination with other items and / or other categories of items. Additionally, as used herein, the term “set” is intended to include any number of items, including zero. Furthermore, as used herein, the term “number” is intended to include any number, including zero. And the term “multiple” as used herein is intended to be synonymous with “multiple.”

[0196] Furthermore, when features or aspects of this disclosure are described in accordance with the Markush Group, those skilled in the art will recognize that this disclosure is also described in accordance with any individual member or subgroup member of the Markush Group.

[0197] As those skilled in the art will understand, for any and all purposes, such as providing a written description, all scopes disclosed herein also encompass any and all possible subscopes and combinations thereof. Any listed scope can be readily identified as sufficiently descriptive and capable of being decomposed into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each scope discussed herein can be readily decomposed into a lower third, a middle third, and an upper third, etc. As those skilled in the art will also understand, all language such as “at most,” “at least,” “greater than,” “less than,” etc., includes the listed numbers and refers to a scope that can subsequently be subdivided into subscopes as discussed above. Finally, as those skilled in the art will understand, a scope includes each individual member. Thus, for example, a group having 1 to 3 units refers to a group having 1, 2, or 3 units. Similarly, a group having 1 to 5 units refers to a group having 1, 2, 3, 4, or 5 units, and so on.

[0198] Furthermore, unless otherwise stated, the claims should not be construed as being limited to the order or elements provided. Additionally, the use of the term "means for..." in any claim is intended to invoke 35 USC §112, ¶ 6 or the means plus function claim format, and any claim without the term "means for..." is not intended to do so.

Claims

1. A method at a wireless transmit / receive unit (WTRU), the method comprising: Perform measurements of the corresponding downlink beam associated with at least one initial candidate cell used for handover; Based on the measurement, a selected candidate cell for handover is determined from the at least one initial candidate cell; The uplink control channel resources are used to transmit information indicating the selected candidate cell as the target cell; as well as Send a message indicating that the switchover is complete.

2. The method according to claim 1, wherein the method comprises: Determine the corresponding timing advance value for the at least one initial candidate cell used for handover; and Specifically, the uplink control channel resources and the timing advance value of the selected candidate cell are used to send information indicating that the selected candidate cell is the target cell to the selected candidate cell.

3. The method according to claim 1 or 2, wherein the method comprises: Receive an indication of the uplink shared channel from the selected candidate cell on the downlink control channel; and Specifically, information indicating the completion of the handover is transmitted on the uplink shared channel.

4. The method according to claim 3, wherein, Send information to the cell currently serving the WTRU indicating that the selected candidate cell is the target cell.

5. The method according to claim 4, wherein the method comprises: In response to sending information indicating the selection of a candidate cell as the target cell, information indicating the activation of the uplink shared channel is received.

6. The method according to any one of claims 3 to 5, wherein, The uplink shared channel is associated with dynamic licensing.

7. The method according to any one of claims 3 to 5, wherein, The uplink shared channel is associated with configuration authorization.

8. The method according to any one of claims 1 to 7, wherein, When a trigger event occurs for at least one candidate cell for handover, the selected candidate cell for handover is determined.

9. The method according to any one of claims 1 to 8, wherein, The selected candidate cell is the initial candidate cell with the highest measured beam quality among the at least one initial candidate cells.

10. The method according to any one of claims 1 to 9, the method comprising: Receive information indicating at least one initial candidate cell for handover, wherein for each initial candidate cell for handover, the information includes at least one uplink control channel resource associated with a downlink beam and conditions for performing the handover.

11. The method according to any one of claims 1 to 10, wherein, The switching is a Layer 2 mobility switching.

12. The method according to any one of claims 1 to 3, wherein, The uplink control channel resource is a scheduling request sent to the cell currently serving the WTRU.

13. A wireless transmit / receive unit (WTRU) comprising at least one processor, said at least one processor being configured to: Perform measurements of the corresponding downlink beam associated with at least one initial candidate cell used for handover; Based on the measurement, a selected candidate cell for handover is determined from the at least one initial candidate cell; The uplink control channel resources are used to transmit information indicating the selected candidate cell as the target cell; as well as Send a message indicating that the switchover is complete.

14. The WTRU of claim 13, wherein, The at least one processor is configured to: Determine the corresponding timing advance value for the at least one initial candidate cell used for handover; and The uplink control channel resources and the timing advance value of the selected candidate cell are used to send information indicating that the selected candidate cell is the target cell.

15. The WTRU according to claim 13 or 14, wherein, The at least one processor is configured to: Receive an indication of the uplink shared channel from the selected candidate cell on the downlink control channel; and Specifically, information indicating the completion of the handover is transmitted on the uplink shared channel.

16. The WTRU according to claim 15, wherein, Send information to the cell currently serving the WTRU indicating that the selected candidate cell is the target cell.

17. The WTRU according to claim 16, wherein, The at least one processor is configured to: In response to sending information indicating the selection of a candidate cell as the target cell, information indicating the activation of the uplink shared channel is received.

18. The WTRU according to any one of claims 15 to 17, wherein, The uplink shared channel is associated with dynamic licensing.

19. The WTRU according to any one of claims 15 to 17, wherein, The uplink shared channel is associated with configuration authorization.

20. The WTRU according to any one of claims 13 to 19, wherein, The at least one processor is configured to determine the selected candidate cell for handover when a triggering event for at least one candidate cell for handover occurs.

21. The WTRU according to any one of claims 13 to 20, wherein, The selected candidate cell is the initial candidate cell with the highest measured beam quality among the at least one initial candidate cells.

22. The WTRU according to any one of claims 13 to 21, wherein, The at least one processor is configured to: Receive information indicating at least one initial candidate cell for handover, wherein for each initial candidate cell for handover, the information includes at least one uplink control channel resource associated with a downlink beam and conditions for performing the handover.

23. The WTRU according to any one of claims 13 to 22, wherein, The switching is a Layer 2 mobility switching.

24. The WTRU according to any one of claims 13 to 15, wherein, The uplink control channel resource is a scheduling request sent to the cell currently serving the WTRU.

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