Enabling Layer 1 and Layer 2 mobility

Abstract

The present invention provides devices and methods for mobility mechanisms. [Solution] A wireless transmit / receive unit (WTRU) can perform L1 / L2 switching of a primary cell. In one method, a WTRU configured with common configuration information for a number of candidate cells and distinct configuration information specific to each candidate cell can receive an LTM instruction for a handover (HO) to a specific candidate cell. Upon receiving an LTM instruction for an HO to a specific candidate cell, the WTRU can retain the common configuration information, release the distinct configuration information specific to the serving cell, and / or apply the distinct configuration information specific to the target candidate cell.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 410,909, filed on September 28, 2022, and U.S. Provisional Patent Application No. 63 / 395,215, filed on August 4, 2022. U.S. Provisional Application Nos. 63 / 410,909 and 63 / 395,215 are hereby incorporated by reference in their entirety.

Background Art

[0002] The present disclosure generally relates to devices and methods for mobility mechanisms. More particularly, the technology relates to enabling layer 1 and layer 2 (L1 / L2) mobility.

[0003] Wireless communication systems have been extended and diversified to provide various types of communication services such as voice or data services. Generally, a wireless communication system is a multiple - access system capable of sharing available system resources (bandwidth, transmission power, etc.) to support communication with multiple users. Examples of multiple - access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC - FDMA) systems, and the like.

Summary of the Invention

[0004] A wireless transmit / receive unit (WTRU) can perform L1 / L2 switching of a primary cell via L1 / L2 triggered mobility (LTM). LTM can have low latency during handover (HO), and the WTRU can perform HO based solely on L1 / L2 indication (e.g., MAC CE), potentially facilitating the selection of a secondary cell, or even a non-serving cell, from a candidate LTM set to become the new PCell. Therefore, it may be necessary for the WTRU to have appropriate pre-configuration for all possible target PCells. It may also be necessary for the WTRU to perform subsequent switching from one target PCell to another without requiring RRC reconfiguration.

[0005] A WTRU configured with a common configuration for multiple candidate cells and a configuration specific to each candidate cell can receive an LTM indication for a HO to a specific candidate cell. Upon receiving an LTM indication for a HO to a specific candidate cell, the WTRU can maintain the common configuration, release the current cell-specific configuration, and / or apply the configuration specific to the target candidate cell.

[0006] The WTRU can receive configuration information related to the LTM. This configuration information may include a candidate cell group configuration. The candidate cell group configuration may include common configuration information for the serving cell and at least one candidate cell. The configuration information may also include separate configuration information specific to the serving cell and each of the at least one candidate cell. Based on the common configuration information and the information specific to the serving cell, the WTRU can communicate with the serving cell. The WTRU can receive an LTM command indicating a handover (HO) to a candidate cell among the at least one candidate cell. The WTRU can release information specific to the serving cell, while retaining common information. Without performing a reconfiguration of the configuration information related to the LTM, the WTRU can use the common configuration information and information specific to the indicated candidate cell among at least one candidate cell to perform a handover to the candidate cell as the serving cell. The WTRU can then send an HO complete message to the network. [Brief explanation of the drawing]

[0007] [Figure 1A] This is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] This figure illustrates an exemplary wireless transmit / receive unit (WTRU) that may be used in the communication system shown in Figure 1A, according to one embodiment. [Figure 1C] This figure illustrates an exemplary radio access network (RAN) and core network (CN) that may be used in the communication system shown in Figure 1A, according to one embodiment. [Figure 1D] This figure illustrates further exemplary RAN and CN that may be used in the communication system of Figure 1A according to one embodiment. [Figure 2] This is a sequence flow diagram showing an example of a handover procedure. [Figure 3] This figure shows an example of an excerpt of information elements related to RRC reconstruction. [Figure 4A] This figure shows an example of an excerpt of RRC reconstruction-related information elements (IE). [Figure 4B] This figure shows an example of an excerpt of RRC reconstruction-related information elements (IE). [Figure 4C] This figure shows an example of an excerpt of RRC reconstruction-related information elements (IE). [Figure 5] This figure shows an example of a Master Cell Group (MCG) and a Secondary Cell Group (SCG). [Figure 6] This figure shows an example of L1 / L2 cell-to-cell mobility operation. [Figure 7] This figure shows exemplary ASN.1 code for capturing exemplary L1 / L2 mobility signaling. [Figure 8] This figure shows an example of a WTRU that stores its configuration until it receives an L1 / L2 message. [Figure 9] This figure shows an example of a WTRU that stores its configuration until it receives an L1 / L2 message. [Figure 10] This figure shows an example of an ASN.1 structure. [Figure 11] This flowchart shows how WTRU can perform L1 / L2 switching of the primary cell (PCell) in the most optimal way possible, potentially avoiding the need for RRC reconfiguration for subsequent PCell changes. [Modes for carrying out the invention]

[0008] Figure 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, message delivery, and broadcast to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique-word OFDM (UW-OFDM), resource block filtering OFDM, and filter bank multicarrier (FBMC).

[0009] As shown in Figure 1A, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, but it will be understood that the disclosed embodiments intend any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, WTRU102a, 102b, 102c, 102d, any of which may be referred to as “station” and / or “STA”, may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed subscriber units or mobile subscriber units, subscriber-based units, pagers, mobile 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., for remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain context), consumer electronics devices, devices operating on commercial wireless networks and / or industrial wireless networks, etc. WTRU102a, 102b, 102c, and 102d can all be referred to as UE for compatibility purposes.

[0010] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks, such as CN 106 / 115, the Internet 110, and / or other networks 112. For example, base stations 114a and 114b may be base transceiver stations (BTS), node B, enode B, home node B, home enode B, gNB, NR node B, site controller, access point (AP), wireless router, etc. Although base stations 114a and 114b are each depicted as single elements, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0011] 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 a base station controller (BSC), a radio network controller (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be licensed spectra, unlicensed spectra, or a combination of licensed and unlicensed spectra. Cells may provide coverage of wireless services to specific geographic areas that may be relatively fixed or change over time. Cells may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver per sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and utilize multiple transceivers per sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

[0012] Base stations 114a and 114b may communicate with one or more WTRUs 102a, 102b, 102c, and 102d via an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0013] More specifically, as described above, the communication system 100 can be a multiple access system and can adopt one or more channel access methods such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a within RAN 104 / 113, and WTRUs 102a, 102b, 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish air interfaces 115 / 116 / 117 using wideband CDMA (WCDMA). 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 UL Packet Access (HSUPA).

[0014] In one embodiment, the base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0015] In one embodiment, the base station 114a, and WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can establish the air interface 116 using New Radio (NR) technology.

[0016] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together using, for example, the dual connectivity (DC) principle. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by transmissions sent to / from multiple types of radio access technologies and / or multiple types of base stations (e.g., eNBs and gNBs).

[0017] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), IS-95, IS-856, Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0018] The base station 114b in Figure 1A may be, for example, a wireless router, home node B, home e-node B, or access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as offices, homes, vehicles, campuses, industrial facilities, aerial corridors (for use by drones, for example), roads, etc. In one embodiment, the base station 114b and WTRU 102c, 102d may implement wireless technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and WTRU 102c, 102d may implement wireless technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base stations 114b and WTRUs 102c, 102d may establish picocells or femtocells using cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in Figure 1A, base station 114b may have a direct connection to the internet 110. Therefore, base station 114b may not need to access the internet 110 via CN 106 / 115.

[0019] RAN104 / 113 can communicate with CN106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU102a, 102b, 102c, and 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, and mobility requirements. CN106 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in Figure 1A, it will be understood that RAN104 / 113 and / or CN106 / 115 may communicate directly or indirectly with other RANs employing the same or different RAT as RAN104 / 113. For example, in addition to being connected to RAN104 / 113 which can utilize NR radio technology, CN106 / 115 can also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0020] CN106 / 115 may also function as a gateway for WTRU102a, 102b, 102c, 102d to access PSTN108, the Internet 110, and / or other networks 112. PSTN108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices, which use common communication protocols such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the Internet protocol (IP) of 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 employ the same RAT as RAN104 / 113 or a different RAT.

[0021] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multimode functionality (for example, WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, WTRU 102c shown in Figure 1A may be configured to communicate with base station 114a, which may employ cellular-based radio technology, and base station 114b, which may employ IEEE 802 radio technology.

[0022] Figure 1B is a system diagram illustrating an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any partial combination of the aforementioned elements while maintaining consistency with one embodiment.

[0023] The processor 118 may be a general-purpose processor, a dedicated 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. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120 which can be coupled to a transmit / receive element 122. Figure 1B depicts the processor 118 and the transceiver 120 as separate components, but it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0024] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be a radiator / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0025] Although the transmit / receive element 122 is depicted as a single element in Figure 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0026] The transceiver 120 may be configured to modulate the signal transmitted by the transmit / receive element 122 and demodulate the signal received by the transmit / receive element 122. As described above, the WTRU 102 may have multimode capability. Therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0027] The processor 118 of the WTRU102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and may receive user input from these. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from any type of suitable memory, such as non-removable memory 130 and / or removable memory 132, and store data in memory. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from memory not physically located on the WTRU 102, such as on a server or home computer (not shown), and store data in memory.

[0028] The processor 118 may be configured to receive power from the power supply 134 and distribute and / or control power to other components in the WTRU 102. The power supply 134 may be any suitable device for supplying power to 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.

[0029] 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, the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via the 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 WTRU102 can acquire positional information by any preferred position determination method while maintaining consistency with one embodiment.

[0030] The processor 118 may be further coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connectivity. For example, peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, compass sensor, proximity sensor, temperature sensor, time sensor, geolocation sensor, altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor, and / or humidity sensor.

[0031] WTRU102 may include a full-duplex radio in which the transmission and reception of some or all of the signals associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception) may be in parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via either hardware (e.g., chokes) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, WRTU102 may include a half-duplex radio for the transmission and reception of any of the signals (e.g., associated with specific subframes for either UL (e.g., for transmission) or downlink (e.g., for reception)).

[0032] Figure 1C is a system diagram illustrating RAN104 and CN106 according to one embodiment. As described above, RAN104 may employ E-UTRA radio technology to communicate with WTRU102a, 102b, and 102c via the air interface 116. RAN104 can also communicate with CN106.

[0033] RAN104 may include enodes B160a, 160b, and 160c, but it will be understood that RAN104 may include any number of enodes B while maintaining consistency with one embodiment. Each of enodes B160a, 160b, and 160c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, enodes B160a, 160b, and 160c may implement MIMO technology. Thus, enode B160a may, for example, use multiple antennas to transmit a wireless signal to WTRU102a and / or receive a wireless signal from WTRU102a.

[0034] Each of the e-nodes B160a, 160b, and 160c may be associated with a specific cell (not shown) and may be configured to handle wireless resource management decisions, handover decisions, user scheduling in UL and / or DL, etc. As shown in Figure 1C, the e-nodes B160a, 160b, and 160c may communicate with each other via the X2 interface.

[0035] The CN106 shown in Figure 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the aforementioned elements is depicted as part of CN106, it should be understood that any of these elements may be owned and / or operated by a legal entity other than the CN operator.

[0036] The MME162 can be connected to each of the e-nodes B162a, 162b, and 162c in RAN104 via the S1 interface and can function as a control node. For example, the MME162 may perform roles such as authenticating users of WTRU102a, 102b, and 102c, activating / deactivating bearers, and selecting a specific serving gateway during the initial attachment of WTRU102a, 102b, and 102c. The MME162 may provide control plane functionality for switching between RAN104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0037] The SGW164 can be connected to each of the e-nodes B160a, 160b, and 160c in RAN104 via the S1 interface. The SGW164 can generally route and forward user data packets to and from WTRU102a, 102b, and 102c. The SGW164 can perform other functions, such as anchoring the user plane during e-node B handovers, triggering paging when DL data is available to WTRU102a, 102b, and 102c, and managing and remembering the context of WTRU102a, 102b, and 102c.

[0038] SGW164 may be connected to PGW166, which may provide WTRU102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU102a, 102b, and 102c and IP-enabled devices.

[0039] CN106 can facilitate communication with other networks. For example, CN106 can provide WTRU102a, 102b, and 102c with access to a circuit-switched network such as PSTN108 to facilitate communication between WTRU102a, 102b, and 102c and conventional terrestrial line communication devices. For example, CN106 may include, or communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) acting as an interface between CN106 and PSTN108. Furthermore, CN106 can provide WTRU102a, 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.

[0040] While WTRUs are described as wireless terminals in Figures 1A to 1D, in certain representative embodiments, such terminals are intended to be able to use a wired communication interface with a communication network (e.g., temporarily or permanently).

[0041] In a typical embodiment, the other network 112 may be a WLAN.

[0042] A WLAN in Infrastructure Basic Service Set (BSS) mode may have access points (APs) of the BSS and one or more stations (STAs) associated with the APs. APs may have access to or interfaces with a Distribution System (DS) or another type of wired / wireless network that carries traffic in and / or out of the BSS. Traffic originating outside the BSS and destined for an STA may reach and be delivered to the STA via an AP. Traffic originating from an STA for a destination outside the BSS may be sent to the AP to be delivered to its respective destination. Traffic between STAs within the BSS may be sent, for example, via an AP; a source STA may send traffic to an AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between a source STA and a destination STA (for example, directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using Independent BSS (IBSS) mode may not have APs, and STAs within or using IBSS (e.g., all STAs) may communicate directly with one another. The IBSS mode of communication may be referred to herein as “ad hoc” communication mode.

[0043] When using the 802.11ac infrastructure operating mode or a similar operating mode, an AP may transmit beacons on a fixed channel, such as the primary channel. The primary channel may be of a fixed width (e.g., a 20 MHz bandwidth) or a width dynamically set via signaling. The primary channel may be the operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain typical embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. In the case of CSMA / CA, the STA, including the AP (e.g., all STAs), may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that STA may be backed off. A single STA (for example, only one station) can transmit at any given time in a given BSS.

[0044] High-throughput (HT) STAs may use a 40 MHz wide channel for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0045] 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. 160 MHz channels can be formed by combining eight consecutive 20 MHz channels, or by combining two non-consecutive 80 MHz channels, which may be referred to as an 80+80 configuration. In the 80+80 configuration, after channel coding, the data can pass through a segment parser that can split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed separately for each stream. The streams may be mapped to two 80 MHz channels, and the data can be transmitted by a transmitting STA. At the receiver of the receiving STA, the operation described above for the 80+80 configuration may be reversed, and the combined data may be sent to Medium Access Control (MAC).

[0046] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. 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 bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV White Space (TVWS) spectrum, while 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz using the non-TVWS spectrum. According to a typical embodiment, 802.11ah may support meter-type control / machine-type communications, such as MTC devices in a macro coverage area. MTC devices may have limited capabilities, including support for certain capabilities, e.g., support for certain and / or limited bandwidths (e.g., support for these only). MTC devices may include batteries with battery life exceeding a threshold (e.g., to maintain very long battery life).

[0047] A WLAN system capable of supporting multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah includes a channel that can be designated as the primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by an STA from among all STAs operating in a BSS that support the minimum bandwidth operating mode. In the 802.11ah example, the primary channel may be 1 MHz wide for an STA (e.g., an MTC type device) that supports (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. For example, if the primary channel is busy due to an STA (which only supports 1MHz operating mode) transmitting to the AP, the entire available frequency band may be considered busy, even though a large portion of the frequency band remains idle and could potentially be available.

[0048] In the United States, the available frequency band that can be used by 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0049] Figure 1D is a system diagram illustrating RAN113 and CN115 according to one embodiment. As described above, RAN113 may employ NR radio technology to communicate with WTRU102a, 102b, and 102c via the air interface 116. RAN113 may also communicate with CN115.

[0050] RAN113 may include gNB180a, 180b, and 180c, but it will be understood that RAN113 may include any number of gNBs while maintaining consistency with one embodiment. Each of gNB180a, 180b, and 180c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, gNB180a, 180b, and 180c may implement MIMO technology. For example, gNB180a and 108b may use beamforming to transmit signals to and / or receive signals from gNB180a, 180b, and 180c. Thus, gNB180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from WTRU102a. In one embodiment, gNB180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB180a may transmit multiple component carriers to WTRU102a (not shown). A subset of these component carriers may be on the unauthorized spectrum, while the remaining component carriers may be on the authorized spectrum. In one embodiment, gNB180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU102a may receive coordinated transmissions from gNB180a and gNB180b (and / or gNB180c).

[0051] WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using transmissions associated with scalable neurology. For example, OFDM symbol intervals and / or OFDM subcarrier intervals may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or having varying absolute time durations).

[0052] gNB180a, 180b, and 180c can be configured to communicate with WTRU102a, 102b, and 102c in standalone and / or non-standalone configurations. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c without accessing other RANs (e.g., e-nodes B160a, 160b, and 160c). In a standalone configuration, WTRU102a, 102b, and 102c can utilize one or more of gNB180a, 180b, and 180c as mobility anchor points. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using signals in unauthorized bands. In a non-standalone configuration, WTRU102a, 102b, and 102c can communicate / connect with gNB180a, 180b, and 180c, while also communicating / connecting with other RANs such as enodes B160a, 160b, and 160c. For example, WTRU102a, 102b, and 102c can implement DC principles for substantially simultaneous communication with one or more gNB180a, 180b, and 180c and one or more enodes B160a, 160b, and 160c. In a non-standalone configuration, enodes B160a, 160b, and 160c can function as mobility anchors for WTRU102a, 102b, and 102c, and gNB180a, 180b, and 180c can provide additional coverage and / or throughput to service WTRU102a, 102b, and 102c.

[0053] Each of the gNB180a, 180b, and 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a and 182b, and so on. As shown in Figure 1D, the gNB180a, 180b, and 180c may communicate with each other via the Xn interface.

[0054] The CN115 shown in Figure 1D may include at least one AMF182a, 182b, at least one UPF184a, 184b, at least one Session Management Function (SMF)183a, 183b, and optionally a Data Network (DN)185a, 185b. Although each of the aforementioned elements is shown as part of the CN115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] AMF182a and 182b can be connected to one or more gNB180a, 180b, and 180c in RAN113 via the N2 interface and can function as control nodes. For example, AMF182a and 182b may be involved in user authentication for WTRU102a, 102b, and 102c, support network slicing (e.g., handling different PDU sessions with different requirements), selection of specific SMF183a and 183b, management of registration areas, termination of NAS signaling, mobility management, etc. Network slicing can be used by AMF182a and 182b to customize CN support for WTRU102a, 102b, and 102c based on the type of service utilizing WTRU102a, 102b, and 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and services for machine type communication (MTC) access. The AMF162 may provide control plane functionality for switching between RAN113 and other RANs (not shown) employing other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0056] SMF183a and 183b can be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b can also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b can select and control UPF184a and 184b and configure the routing of traffic through UPF184a and 184b. SMF183a and 183b can perform other functions such as managing and allocating IP addresses for WTRUs, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0057] UPF184a and 184b may be connected via the N3 interface to one or more gNB180a, 180b, and 180c in RAN113, thereby providing WTRU102a, 102b, and 102c with access to packet-switched networks such as the Internet 110, facilitating communication between WTRU102a, 102b, and 102c and IP-enabled devices. UPF184 and 184b may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multiple home PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0058] CN115 can facilitate communication with other networks. For example, CN115 may include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that functions as an interface between CN115 and PSTN108. In addition, CN115 may provide WTRU102a, 102b, 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 one embodiment, WTRU102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via UPF184a, 184b through an N3 interface to UPF184a, 184b, and an N6 interface between UPF184a, 184b and DN185a, 185b.

[0059] In view of Figures 1A to 1D and their corresponding descriptions, one or more of the functions described herein with respect to one or more of the WTRU102a to d, base stations 114a and b, e-nodes-B160a to c, MME162, SGW164, PGW166, gNB180a to c, AMF182a to ab, UPF184a and b, SMF183a and b, DN185a and b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0060] Emulation devices may be designed to implement testing of one or more other devices in a laboratory and / or carrier network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in a communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. Emulation devices may be directly coupled to another device for testing purposes and / or may perform testing using terrestrial wireless communication.

[0061] One or more emulation devices may perform one or more functions, including all of the above, while not implemented / deployed as part of a wired and / or wireless communication network. For example, emulation devices may be used in test scenarios in a test laboratory, and / or in a wired and / or wireless communication network that is not deployed (e.g., for testing), to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by emulation devices to transmit and / or receive data.

[0062] Methods and apparatus for implementing carrier aggregation (CA) are described herein. CA can enable simultaneous transmission or reception on multiple component carriers, while other methods and apparatus that cannot perform CA can access one of the component carriers. Each node (e.g., node B, eNB, gNB, etc.) can serve multiple cells. Cells are sometimes collectively referred to as serving cells. Serving cells served by a node are sometimes referred to as a cell group. Serving cells within a cell group can be divided into a primary cell (PCell) and one or more secondary cells (SCell). In one example, a PCell may operate on a primary frequency on which a WTRU can perform initial connection establishment procedures. After the initial connection to the PCell, one or more SCells may be configured and / or added. SCells can be activated or deceptively activated to meet fluctuating demands in communication with the network (e.g., UL / DL throughput required by the WTRU, available network resources, etc.).

[0063] During dual connectivity (DC), a WTRU can be connected to multiple nodes. For example, a WTRU can be connected to a master node and one or more secondary nodes. Each of the master and secondary nodes can serve multiple cells. The master node can serve a cell group sometimes referred to as a master cell group (MCG). The secondary nodes can serve a cell group sometimes referred to as a secondary cell group (SCG). The primary cell for a master cell group may be referred to as a PCell (for example, if a DC is configured), and the primary cell for a secondary cell group may be referred to as a primary secondary cell (PSCell).

[0064] The term "special cell" (SpCell) can refer to either a PCell in an MCG or a PSCell in an SCG. There is one Media Access Control (MAC) entity associated with the MCG and another MAC entity associated with the SCG.

[0065] In one embodiment, the WTRU may receive a Radio Resource Control (RRC) reconfiguration which may include an SpCell configuration that may be associated with each SCell or an SCell configuration associated with each SpCell. The WTRU may perform one or more of the following actions: For example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may release the current SpCell configuration (e.g., the current SpCell is associated with cell a). For example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become an SpCell (e.g., the current SpCell may be cell a), the WTRU may release the current SCell configuration (e.g., the current SCell is associated with cell b). For example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become a SpCell (e.g., the current SpCell may be cell a), the WTRU can apply the SpCell configuration associated with another cell (e.g., cell b). For example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become a SpCell (e.g., the current SpCell may be cell a), the WTRU can apply the SCell configuration associated with another cell (e.g., cell a). For example, upon receiving an L1 / L2 mobility set indication that promotes an SCell (e.g., cell b) to become a SpCell (e.g., the current SpCell may be cell a), the WTRU can reset the RLF counter and / or stop one or more (or, for example, any) running RLF timers for the SpCell.For example, upon receiving an L1 / 2 mobility set indication that facilitates an SCell (e.g., cell b) becoming a SpCell (e.g., the current SpCell may be cell a), the WTRU can determine the SCell state of cell a based on the indication received in the L1 / L2 indication (e.g., based on signal levels, pre-configured behavior, etc.). For example, upon receiving an L1 / L2 mobility set indication that facilitates an SCell (e.g., cell b) becoming a SpCell (e.g., the current SpCell may be cell a), the WTRU can transmit an indication to the network indicating the successful completion of the L1 / L2 mobility and / or containing additional information (e.g., the selected SCell state of the old SpCell, measurement results of the serving / candidate cell, etc.). In addition, a non-serving cell may become a new PCell and / or SpCell.

[0066] In one embodiment, the WTRU may receive an RRC reconfiguration that includes an L1 / L2 mobility candidate cell list configuration and / or includes cells other than the current SpCell and Scell. In one example, the configuration may include SpCell configurations and / or SCell configurations, which may be associated with one or more, or each candidate cell. The WTRU may perform one or more of the following actions: In one example, upon receiving an L1 / L2 mobility set indication that includes a candidate cell, the WTRU may apply the SCell configuration associated with the candidate cell if it is indicated that the candidate cell can become an SCell. In one example, upon receiving an L1 / L2 mobility set indication that includes a candidate cell, the WTRU may apply the SpCell configuration associated with the candidate cell if it is indicated that the candidate cell can become a SpCell.

[0067] In one embodiment, the WTRU may include an L1 / L2 mobility candidate cell group list configuration and receive an RRC reconfiguration that includes cells other than the current SpCell and SCell. In one example, the configuration may include one or more SpCell configurations and / or SCell configurations that may be associated with each candidate cell. In one example, upon receiving an L1 / L2 mobility set indication that includes candidates, the WTRU may apply a cell group configuration that includes any associated SpCell and SCell configurations.

[0068] Figure 2 shows an example of the handover procedure 200. For example, as shown in Figure 2, at 212, WTRU 202 can send data to and / or receive data from source gNodeB (gNB) 204. The data can be sent to and / or received from User Plane Function (UPF) 210. At 214, Access and Mobility Management Function (AMF) can manage connectivity and mobility tasks for the WTRU between source gNB 204 and target gNB 206 by providing mobility control information. The WTRU 202 context within source gNodeB (gNB) 204 can include roaming and / or access restriction information that may be provided (for example, at connection establishment and / or at the last TA (Timing Advance) update). For example, at 216, WTRU 202 can perform measurements and reports. Source gNB204 can configure a WTRU using the measurement configuration, and / or WTRU202 can report according to the report trigger conditions indicated in the measurement configuration. In 218, source gNB204 can decide to hand over WTRU202 (for example, based on the received measurement report). In 220, source gNB204 can issue a handover request message to target gNB206, which may be passing a transparent RRC container containing information for the target to prepare for the handover. In one example, the information may include the target cell ID, the security key for the gNB (key for the gNB, KgNB). *The information may include, for example, the cell radio network identifier (C-RNTI) of WTRU202 within source gNB204, the RRM (Radio Source Management) configuration including WTRU inactivity time, the access stratum configuration (AS configuration) including antenna information and DL (downlink) carrier frequency, the mapping rules from the current quality of service (QoS) flow to the data radio bearer (DRB) applied to the WTRU, system information block 1 (SIB1) from source gNB, the WTRU capabilities of different RATs, and packet data unit (PDU) session-related information. For example, the information may include WTRU-reported measurement information, including beam-related information if available.

[0069] In 222, admission control may be performed by target gNB206. For example, in 224, if WTRU202 is approved, target gNB206 can prepare the resources required for WTRU202 and send a handover request approval to source gNB204, which may include a transparent container that is sent to the WTRU as an RRC message to perform the handover.

[0070] In 226, source gNB204 can initiate the RAN handover procedure. For example, source gNB204 can trigger a handover by sending an RRC reconfiguration message to WTRU202 that may contain information used to access the target cell. In one example, the information used to access the target cell may include the target cell ID, the updated C-RNTI, and the target gNB206 security algorithm identifier for the selected security algorithm. In another example, the information used to access the target cell may include a set of dedicated RACH resources, associations between RACH resources and SSBs(s), associations between RACH resources and WTRU-specific CSI-RS configurations(s), common RACH resources, and system information for the target cell. In one example, if a dual active protocol stack (DAPS) is configured, the source connection may be maintained after the handover (HO) command is sent. In another example, there may be no UL or DL ​​communication between the WTRU and source gNB204 after the HO command is sent. At 228, source gNB204 can deliver buffered data and / or new data from UPF(UPF)210 to WTRU202. At 230, WTRU202 can detach from the previous cell and synchronize to the next cell.

[0071] Source gNB204 can send an early status transfer message at 232. For example, source gNB204 can send an early status transfer message when a DAPS handover is performed. At 234, source gNB204 can send an SN STATUS TRANSFER message to target gNB206 to carry the uplink PDCP (Packet Data Convergence Protocol) SN receiver status and / or downlink PDCP SN transmitter status of a DRB to which PDCP status saving may apply (e.g., for RLC AM). Data sent to source gNB204 at 212a may be redirected to target gNB206 and buffered at 236 for transmission to WTRU202. At 238, WTRU202 can perform RAN handover completion. WTRU202 can synchronize with the target cell and / or complete the RRC handover procedure by sending an RRC reconfiguration completion message to target gNB206. At 240, target gNB205 can send a handover success message to source gNB204. At 242, source gNB204 can send an SN status transfer message to target gNB. At 212b, data sent to source gNB204 can be redirected to target gNB206 and buffered at 236 for transmission to WTRU202. At 212c, WTRU202 can send uplink data to target gNB206 and / or receive buffered data from target gNB104. Uplink data can be sent to UPF210. At 244, target gNB206 can send a route switching request message to AMF208 to trigger 5GC to switch the DL data route toward target gNB206 and / or establish an NG-C interface instance toward target gNB206.At 246, 5GC can switch the DL data route toward target gNB206. For example, UPF210 may send one or more “end marker” packets 248 on the old route toward source gNB204 for each PDU session / tunnel, and then release any U-plane / TNL resources toward source gNB204. At 250, AMF208 can acknowledge the route switching request message with a route switching request acknowledgment message. At 252, upon receiving the route switching request acknowledgment message from AMF208, target gNB206 can notify source gNB204 of the success of the handover by sending a WTRU context release. For example, source gNB204 can then release radio and / or C-plane related resources associated with the WTRU context. For example, any ongoing data transfer can continue.

[0072] Messages that may contain configuration information related to L1 / L2 triggered mobility (LTM) may be received by the WTRU. Configuration information related to LTM may be received via medium access control element (MAC EE), Physical Layer Downlink Control Information (PHY DCI), or one or more radio resource control (RRC) configuration / reconfiguration messages. Configuration information related to LTM may include candidate cell group configuration. The candidate cell group configuration may include common configuration information for the serving cell and at least one candidate cell, and / or separate configuration information specific to each candidate cell of the serving cell and at least one candidate cell. For example, the candidate cell group configuration may be applied as a master cell group (MCG) or a secondary cell group (SCG). In another example, the candidate cell group configuration may replace a pre-configured MCG configuration or a pre-configured SCG configuration.

[0073] A WTRU can communicate with a serving cell based on common configuration information and configuration information specific to the serving cell. The WTRU can further receive an LTM command indicating a handover (HO) to a candidate cell among at least one candidate cell. For example, received configuration information related to an LTM may be received via a media access control element (MAC EE), physical layer downlink control information (PHY DCI), or one or more radio resource control (RRC) reconfigurations. An LTM command may include an existing index list, which may consist of an index value for each candidate cell among at least one candidate cell. An LTM command may include a unique index, which may be assigned to a candidate cell among at least one candidate cell.

[0074] The WTRU can release further information specific to the serving cell. The WTRU can perform a handover to a candidate cell as a serving cell using common configuration information and information specific to the indicated candidate cell among at least one candidate cell, without performing a reconfiguration of the configuration information related to the LTM. For example, the handover may be performed without performing another RRC configuration / reconfiguration via an RRC configuration message, and without performing a reconfiguration of the configuration information related to the LTM. The handover to a candidate cell as a serving cell may be based, for example, on a delta configuration. A delta configuration may include a change in at least one parameter in the configuration information related to the LTM. For example, a delta configuration may include a change in one parameter in the configuration information related to the LTM.

[0075] A WTRU can apply common configuration information to at least one candidate cell. A WTRU can further apply separate configuration information specific to the indicated candidate cell among the at least one candidate cell.

[0076] Figure 3 shows an example of configuration information and an excerpt of information elements related to an RRCReconfiguration message. For example, a handover (HO) command may be an RRCReconfiguration message containing reconfigurationWithSync. As described herein, an RRCReconfiguration message may be sent to the WTRU during the handover initiation. An RRCReconfiguration message may contain information used to access the target cell. An RRCReconfiguration message may include an RRCReconfiguration information element 302. An RRCReconfiguration information element 302 may include a secondaryCellGroup configuration parameter 304. A secondaryCellGroup configuration parameter 304 may include a CellGroupConfig parameter 402a. As shown in 306, the secondaryCellGroup configuration parameter 304 may be included if the SCG is configured or enabled during dual connectivity.

[0077] The RRCReconfiguration information element 302 may include additional information elements. For example, the RRCReconfiguration information element 302 may include the RRCReconfiguration information element 308. The RRCReconfiguration information element 308 may include the masterCellGroup configuration parameter 310. The masterCellGroup configuration parameter 310 may include the CellGroupConfig parameter 402b. The masterCellGroup configuration parameter 310 may be included in each RRCReconfiguration message including the MCG, as shown in [reference].

[0078] Figures 4A to 4C show additional excerpts of configuration information and information elements related to the RRCReconfiguration message. Figures 4B and 4C are continuations of the exemplary excerpt shown in Figure 4A. As shown in Figure 3, the RRCReconfiguration message may include cell group configuration or CellGroupConfig402 (e.g., masterCellGroup310 CellGroupConfig402b, and possibly secondaryCellGroup304 CellGroupConfig402a if dual connectivity (DC) is configured).

[0079] For example, CellGroupConfig402 may include the cellGroupId parameter 404, the MAC-CellGroupConfig parameter 406, the PhysicalCellGroupConfig parameter 408, and / or the SpCellConfig parameter 410. MAC-CellGroupConfig may include the configuration of MAC layer and / or protocol parameters for a particular cell group. For example, a particular cell group may be an MCG and / or an SCG. Similarly, PhysicalCellGroupConfig may include the configuration of MAC layer and / or protocol parameters for a particular cell group. SpCellConfig410 may include the servCellIndex parameter 412 and / or the reconfigurationWithSync parameter 416. The servCellIndex parameter 412 may include the servCellIndex parameter 414. The reconfigurationWithSync parameter 416 may include the ReconfigurationWithSync parameter 418. The reconfigurationWithSync parameter 416 may be included on the condition that ReconfWithSync is configured or enabled during dual connectivity, as shown in 420.

[0080] The ReconfigurationWithSync parameter 418a may include the spCellConfigCommon parameter 422. The spCellConfigCommon parameter 422 may include the ServingCellConfigCommon parameter 424. SCellConfig 426 may include the sCellConfigCommon parameter 428 and / or the sCellConfigDedicated parameter 430. The sCellConfigCommon parameter 428 may include the ServingCellConfigCommon parameter 424a. The sCellConfigDedicated parameter 430 may include the ServingCellConfig parameter 432.

[0081] Figure 5 shows an example of a master cell group (MCG) 502a and a secondary cell group (SCG) 502b. The cell group configuration may include the configuration of each cell belonging to the cell group (e.g., cells operating in carrier aggregation (CA)). The cells collectively known as serving cells may be divided into primary cells 504a, 504b and secondary cells 506a, 506b. In one example, primary cells 504a, 504b may be operating on the primary frequency at which the WTRU performs the initial connection establishment procedure. In another example, primary cells 504a, 504b may be operating on the primary frequency at which the WTRU initiates the connection re-establishment procedure. In another example, primary cells 504a, 504b may be operating on the primary frequency, and the WTRU is the cell shown as primary cells 504a, 504b in the handover procedure. For example, the primary cell 504a for the master cell group 502a may be referred to as a PCell, and the primary cell 504b for the secondary cell group 502b (for example, if a DC is configured) may be referred to as a PSCell (primary secondary cell). The term Special Cell (SpCell) 508 may refer to PCell 504a and / or PSCell 504b. For example, SCells 506a and 506b may be cells that provide other carriers used during carrier aggregation for the corresponding cell groups.

[0082] Many operations, such as radio link monitoring (RLM) and related radio link failure (RLF) detection and recovery, may be related to the primary cell. For example, an operation may be related only to the primary cell. Each serving cell can be identified by a servCellIndex (serving cell index) that takes a value from 0 to 31. In one example, a PCell may be assigned a servCellIndex value of 0. In another example, a PCell may always be assigned a servCellIndex value of 0.

[0083] Inter-cell L1 / 2 mobility can manage beams in the case of CA. However, in one example, cell changes and / or additions may not be supported. In one embodiment, one or more mechanisms and / or procedures for L1 / L2-based inter-cell mobility for mobility latency reduction may be specified. For example, to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction, configuration and / or maintenance for multiple candidate cells may be performed to enable rapid application of configurations for candidate cells (e.g., in RAN2, RAN3, etc.). For example, to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction, a dynamic switching mechanism between candidate cells as serving cells (e.g., including SpCell and SCell) for potential applicable scenarios may be based on L1 / L2 signaling (e.g., in RAN2, RAN1, etc.). For example, L1 extensions for inter-cell beam management may be implemented, including, for example, L1 measurement and reporting, and / or beam indication (in RAN1, RAN2, etc.), to specify the mechanisms and procedures for L1 / L2-based inter-cell mobility to reduce mobility latency. In one example, early RAN2 involvement may be implemented (for example, if necessary), which may further clarify the interaction between the L1 extensions for inter-cell beam management and the dynamic switching mechanism between candidate cells as serving cells. For example, timing advance (TA) management may be implemented (in RAN1, RAN2, etc.) to specify the mechanisms and procedures for L1 / L2-based inter-cell mobility to reduce mobility latency.

[0084] To specify the mechanisms and procedures for L1 / L2-based inter-cell mobility for reducing mobility latency, central unit-distributed unit (CU-DU) interface signaling may be performed to support L1 / L2 mobility, where necessary (e.g., in RAN3). In one example, FR2-specific extensions may not be excluded.

[0085] The L1 / L2-based inter-cell mobility procedure may be applicable to one or more of the following scenarios, namely, with serving cell changes within a single cell group (CG), standalone, carrier aggregation (CA), and new radio dual connectivity (NR-DC); intra-DU cases and inter-CU cases (e.g., applicable to standalone and CA when a new RAN interface is not expected); both intra-frequency and inter-frequency; both FR1 and FR2; and source and target cells, which may be synchronous or asynchronous, and which may not be included in the inter-CU case.

[0086] Inter-cell beam management can address scenarios within the DU and / or within the frequency. In one example, the serving cell may remain unchanged (e.g., there may be no possibility of changing the serving cell using L1 / 2-based mobility). In an FR2 deployment, CA may be used to leverage available bandwidth, for example, to aggregate multiple CCs within a single band. These component carriers (CCs) may be transmitted using the same analog beam pair (gNB beam and WTRU beam). A WTRU may consist of TCI states for receiving PDCCH and / or PDSCH (e.g., it may have a fairly large number, e.g., 64). Each TCI state may include an RS or SSB that the WTRU refers to for setting up the WTRU's beam. The SSB may be associated with a non-serving PCI. MAC signaling (e.g., TCI state indication for a WTRU-specific PDCCH MAC CE) can activate TCI states for Coreset / PDCCH. Reception of PDCCH from a non-serving cell may be supported by a MAC CE indicating a TCI state associated with a non-serving PCI. MAC signaling (e.g., TCI state activation / deactivation for a WTRU-specific PDSCH) can activate a subset of TCI states for PDSCH reception (e.g., up to 8 TCI states for PDSCH reception). A DCI may indicate a TCI state (e.g., any of the 8 TCI states). A "unified TCI state" may exist with a different update mechanism (DCI-based), but without multi-TRP. An integrated TCI state with multi-TRP is also possible.

[0087] The overall objective of L1 / L2 cell-to-cell mobility may be to improve handover latency. In conventional or conditional L3 handovers, the WTRU can first transmit a measurement report using RRC signaling. In response to the measurement report, the network can provide further measurement configurations and / or conditional handover configurations. In conventional handovers, the network can provide configurations for the target cell after the WTRU has reported using RRC signaling that the cell meets the configured radio quality criteria. In conditional handovers, to reduce the handover failure rate due to delays in transmitting the measurement report and then receiving the RRC reconfiguration, the network provides the target cell configuration, as well as the criteria that determine when the WTRU can trigger the CHO configuration, in advance. Both of these L3 methods may experience some amount of delay, particularly in the case of conventional (unconditional) handovers, due to the transmission of the measurement report and the reception of the target configuration. In particular, L1 / L2-based inter-cell mobility, for example, may aim to enable rapid application of configurations for candidate cells, including, for example, dynamic switching between SCells and PCells (e.g., switching roles between SCells and PCells) without performing RRC signaling. In the case of inter-CUs, relocation of PDCP anchors may be required, which may already be excluded from work items and therefore may not be included in R18 work. Thus, RRC-based methods may be required to support inter-CU handovers. One of the purposes of L1 / L2 may be to enable CA operations to be activated instantaneously when a serving cell changes.

[0088] Figure 6 shows an example of L1 / L2 inter-cell mobility operation. For example, candidate cell groups may be configured by RRC, and dynamic switching between PCells and SCells can be achieved using L1 / L2 signaling. As mentioned above, functionality can be introduced to perform HO via L1 / L2 signaling within a given mobility set (e.g., within a subset of cells in a given gNB), where SCells can become new PCells. As shown in the structure of RRC reconfiguration messages and related structures discussed earlier, SpCells (e.g., PCells or PSCells) may require a separate configuration compared to SCells because there may be several functionalities and WTRU behaviors that are associated with (e.g., only with) SpCells. Since configuration of only one sPCell per cell group may be permitted, L1 / L2 switching from SCell to PCell may not be possible with the current RRC signaling structure.

[0089] L1 / L2 mobility signaling may include indications regarding which SCells can be promoted to PCells. However, the solution and associated configuration / signaling may also be applicable when a non-serving neighbor cell can be promoted as a PCell. For example, in the following description, unless otherwise specified, it can be assumed that a previous PCell is demoted to become a SCell upon receiving L1 / L2 mobility signaling that promotes an SCell to a PCell. In one example, in the following description, L1 / L2 signaling may refer to MAC CE or DCI. SpCell configuration may be used for SCells. In one example, for each SCell, a WTRU may be configured with the associated sPCellConfig. The WTRU can be stored without applying this configuration.

[0090] For example, in step 610, RRC may first configure cells 602, 604, 606, and 608 as candidate cells. RRC may also first activate cell 602 as a PCell and cell 604 as an SCell. In steps 612 and 614, a dynamic switching of SCells between cell 604 and cell 606 may be initiated (for example, via L1 / L2 signaling). For example, in step 612, the SCell may be cell 606. In another example, in step 614, the SCell may be cell 604. In step 616, the L1 / L2 signaling may dynamically switch the PCell to cell 604 and the SCell to cell 608 to terminate the L1 / L2 inter-cell mobility operation.

[0091] Figure 7 shows exemplary ASN.1 code for capturing exemplary L1 / L2 mobility signaling. In the example, the WTRU may be configured with SCellConfig associated with a SpCell (e.g., per cell group). The WTRU can store this configuration, but cannot apply it until it receives an L1 / L2 message indicating, for example, that the corresponding SpCell can now be demoted to an SCell.

[0092] SCellConfig426a may include the sCellConfigCommon parameter 428a, the sCellConfigDedicated parameter 430a, and / or the sCellSpCellConfig parameter 702. The sCellConfigCommon parameter 428a may include the ServingCellConfigCommon parameter 424b. The sCellConfigDedicated parameter 430a may include the ServingCellConfig parameter 432a. The sCellSpCellConfig parameter 702 may include the SpCellConfig parameter 704. The sCellSpCellConfig parameter 702 may be included if L1_L2_mobility_SCell is configured or enabled during dual connectivity, as shown in 706. If the sCellSpCellConfig parameter 702 exists, it may include parameters to be used for this SCell when the WTRU receives an L1 / L2 mobility indication that promotes this SCell to SpCell. L1_L2_mobility_SCell may optionally exist if this SCell is part of an L1 / L2 mobility set group and can be promoted to SCell upon receiving such an L1 / L2 indication from the network.

[0093] Figure 8 shows an example of a WTRU that stores the configuration until it receives an L1 / L2 message. In one example, an IE (e.g., spCellSCellConfig) may be added to the SpCellConfig IE.

[0094] SpCellConfig 410a may include the servCellIndex parameter 412a, the reconfigurationWithSync parameter 416a, and / or the spCellSCellConfig parameter 802. The ServCellIndex parameter 412a may include the ServCellIndex parameter 414a. The reconfigurationWithSync parameter 416a may include the ReconfigurationWithSync parameter 418b. The reconfigurationWithSync parameter 416a may be included if ReconfigWithSync is configured or enabled during dual connectivity, as shown in 420a. The spCellSCellConfig parameter 802 may include the SCellConfig parameter 804. The spCellSCellConfig parameter 802 may be included if L1_L2_mobility_SpCell is configured or enabled during dual connectivity, as shown in 806. If the spCellSCellConfig parameter 802 exists, this field may contain parameters used for this SpCell when the WTRU receives an L1 / L2 mobility indication that would demote this SpCell to an SCell. L1_L2_mobility_SpCell may optionally exist if this SpCell is part of an L1 / L2 mobility set group and can be demoted to an SCell upon receiving such an L1 / L2 indication from the network.

[0095] Figure 9 shows an example of a WTRU that stores its configuration until it receives an L1 / L2 message. In one example, additional SCells can be added using the sCellToAddModList IE of CellGroupConfig, and the serving cell index of this SCell can be associated with the SpCell. In one example, the WTRU can be configured using a list of candidate cells, each of which can be provided using one or more of the following: CandidateCellIndex (and / or servingCellIndex), SpCellConfig, SCellConfig, and / or OtherConfig.

[0096] SpCellConfig410b may include the servCellIndex parameter 412b, the reconfigurationWithSync parameter 416b, and / or the spCellSCellIndex parameter 902. The ServCellIndex parameter 412b may include the ServCellIndex parameter 414b. The reconfigurationWithSync parameter 416b may include the ReconfigurationWithSync parameter 418c. The reconfigurationWithSync parameter 416b may be included if ReconfWithSync is configured or enabled during dual connectivity, as shown in 420b. The spCellSCellIndex parameter 902 may include the ServCellIndex parameter 904. The spCellSCellIndex parameter 902 may be included if L1_L2_mobility_SpCell is configured or enabled during dual connectivity, as shown in 806a. If the spCellSCellindex parameter 902 exists, this field may contain parameters used for this SpCell when the WTRU receives an L1 / L2 mobility indication that would demote this SpCell to SCell. L1_L2_mobility_SpCell may optionally exist if this SpCell is part of an L1 / L2 mobility set group and could be demoted to SCell upon receiving such an L1 / L2 indication from the network.

[0097] Figure 10 shows an example of an ASN.1 structure. CandidateCellConfig 1002 may include candidateCellIndex parameter 1004, spCellConfig parameter 1008, sCellConfig parameter 1012, and / or otherCellConfig parameter 1016. candidateCellIndex parameter 1004 may include ServCellIndex parameter 1006. spCellConfig parameter 1008 may include spCellConfig parameter 1010. sCellConfig parameter 1012 may include sCellConfig parameter 1014. otherCellConfig parameter 1016 may include OtherCellConfig parameter 1018. candidateCellIndex parameter 1004 may relate to a short identity and can be used to uniquely identify a candidate L1 / L2 mobility cell. If the spCellConfig parameter 1008 exists, it may include parameters to be used for this cell when the WTRU receives an L1 / L2 mobility indication that configures this cell as a SpCell. If the sCellConfig parameter 1012 exists, it may include parameters to be used for this cell when the WTRU receives an L1 / L2 mobility indication that configures this cell as an SCell. If the otherCellConfig parameter 1016 exists, it may include parameters to be used for this cell when this cell is configured as part of a cell measurement set.

[0098] Each candidate cell may be given one or more potential configurations. If a cell may be configured as a SpCell at some point in the future, it may be configured using SpCellConfig. If a cell may be configured as an SCell at some point in the future, it may be configured using SCellConfig. Additional configurations (e.g., OtherCellConfig) may include parameters to be used under specific circumstances. For example, a WTRU may configure more cells than just an SPCell to perform RLM measurements. In one example, these cells may be SCells or candidate cells (e.g., potential SCells that are not currently configured as such). These cells using "other" configurations may have an intermediate state, e.g., before becoming an active PCell and / or SCell, where they are monitored for one or more of the following: RLM, beam tracking, BFD, PDDCH monitoring, and timing advance maintenance. These cells may be configured to use "other" configurations by L1 / L2 mobility commands. A unique index (e.g., candidateCellIndex) may be assigned to each configured candidate cell (a candidate cell associated with multiple configurations as described above). This index may be referenced by L1 / L2 mobility commands (e.g., MAC CE or DCI) when setting the state of a cell, switching it (from SCell) to SpCell, or vice versa. Alternatively, or in conjunction with this, each cell may be configured using an index value, with existing servCellIndex and / or sCellIndex (e.g., contained within SpCellConfig and SCellConfig) which may be referenced by L1 / L2 mobility commands.

[0099] Upon receiving an L1 / L2 mobility command that informs the WTRU which cells are SPCells, which cells are SCells, and which cells potentially belong to "other" cell groups, the WTRU may reassign servCellIndex and / or sCellIndex according to the arrangement, for example, so that existing L1, MAC, and / or RRC procedures can refer to these indices. For example, a PCell may be assigned servCellIndex 0, and SCells may be assigned servCellIndex and sCellIndex 1...N in the order of their candidateCellIndex. The WTRU may apply the relevant configuration according to the L1 / L2 command assignment. For example, the WTRU may release the current SpCellConfig and SCell configurations and apply the new configurations. Alternatively or in conjunction with the new assignment, the WTRU may modify existing configurations according to the new assignments. For example, WTRU can move a new PCell from servCellIndex N to servCellIndex 0, and move SCells indicated in L1 / L2 mobility commands to servCellIndex 1...N.

[0100] A WTRU may be configured using a list of candidate cell groups. Each candidate cell group may contain one or more of the following: candidateCellGroupIndex, cellGroupId, SpCellConfig (e.g., one or more potential SPCells), SCellConfig (e.g., a list of SCells), OtherConfig, rlc-BearerToAddModList (e.g., a list of RLC-BearerConfigs), rlc-BearerToReleaseList (e.g., a list of LogicalChannelIdentities), MAC-CellGroupConfig, and / or PhysicalCellGroupConfig. In the example, a WTRU may be configured using one candidate cell group configuration per candidate SpCell, containing a list of potential SCells. Upon receiving an L1 / L2 mobility indication, the WTRU can apply the cell group configuration and / or the SpCell configuration. The WTRU can receive, for example, which of one or more listed SCells constitutes a PCell in the same L1 / L2 mobility indication (e.g., SpCell and SCell may be indicated in the same MAC CE) and / or in separate indications (e.g., in separate MAC CEs). The WTRU can reassign serving cell identities as described above. The WTRU can move a PCell to identity 0 and any configured SCell, for example, from index 1 to 31.

[0101] In one example, the WTRU may consist of one candidate cell group configuration for each combination of SpCell and / or SCell. For example, if SpCell is cell A or cell B, and SCell is cell A and / or cell B and / or cell C, the WTRU may consist of six cell group configurations, such as: (1) SpCell may be cell A and SCell may be cell B; (2) SpCell may be cell A and SCell may be cell C; (3) SpCell may be cell A and SCell may be cell B and / or cell C; (4) SpCell may be cell B and SCell may be cell A; (5) SpCell may be cell B and SCell may be cell C and / or; and / or; (6) SpCell may be cell B and SCell may be cell A and / or cell C.

[0102] An L1 / L2 mobility indication may contain a pointer to a candidate cell group configuration, and upon receiving this, the WTRU can apply the associated cell group configuration, for example, to replace (e.g., release) any previously configured serving cells, and / or configure (e.g., add) new serving cells, and / or assign them a pre-configured explicit serving cell identity.

[0103] In one example, a WTRU may consist of a single cell group configuration that can be associated with one or more potential SPCells and / or one or more potential SCells. An L1 / L2 mobility indication may include a candidate cell group configuration, a candidate cell to be configured as a SpCell, and / or a pointer to a candidate cell to be configured as an SCell. In one example, upon receiving an L1 / L2 mobility indication, a WTRU may apply the indicated candidate cell group configuration and / or apply the associated candidate cell configuration using one of the methods described previously.

[0104] In one example, each candidate cell group configuration may be pre-configured as either a master cell group (MCG) or a secondary cell group (SCG) configuration. Upon receiving an L1 / L2 mobility command, the WTRU may replace the current MCG or SCG with the indicated cell group configuration, for example, depending on whether the pre-configuration is associated with an MCG or SCG. In one example, a candidate cell group may not be associated with an SCG or MCG. The WTRU may apply the candidate cell group configuration to an MCG or SCG, for example, depending on the indication received in the L1 / L2 mobility command regarding whether the candidate cell group configuration can be applied as an MCG or SCG.

[0105] For example, a WTRU can be configured using a list of candidate RRC configurations, each of which can be provided using one or more of the following: radio bearer configuration, MCG configuration (e.g., CellGroupConfig), SCG configuration (e.g., CellGroupConfig), CellGroupConfig (e.g., CSG / MCG not specified), full configuration flag, measurement configuration, master key update, SIB1, and / or other configurations.

[0106] In one example, the WTRU may consist of one candidate RRC configuration for each candidate SpCell. In another example, the WTRU may consist of one candidate RRC configuration for each combination of SPCell and SCell. In another example, the WTRU may consist of one candidate RRC reconfiguration for each cell group configuration. In another example, the WTRU may consist of one or more candidate RRC reconfigurations, one or more candidate cell group configurations, one or more candidate SPCells, and / or one or more candidate Scells. The L1 / L2 mobility indication may represent one or more of the candidate RRC reconfigurations, candidate cell group configurations, candidate SpCell configurations, and candidate SCell configurations. The WTRU may apply the indicated configurations and / or combinations of the indicated configurations according to any of the methods or examples described above.

[0107] For example, upon receiving an L1 / L2 mobility signaling indication, the WTRU will: release the CellGroupConfig associated with the current cell group(s); apply one or more CellGroupConfigs indicated to be configured as the new cell group configuration; release one or more measurement configurations associated with the current RRC configuration; apply one or more new measurement configurations associated with the new assignment; perform a master key update; apply a full reconfiguration; remember the SIB1 configuration; update the physical cell group configuration (releasing the current configuration and applying the new configuration); update the MAC cell group configuration (releasing the current configuration and applying the new configuration). You can perform one or more of the following actions: apply a new configuration, release a logical channel (RLC bearer configuration), add a logical channel (RLC bearer configuration), update all servingCellIndex and sCellIndex of the current serving cell based on the new assignment as described above, release the sPCellConfig associated with the current PCell, apply the sCellConfig associated with the current PCell, release the sCellConfig associated with the SCell that has been indicated to be promoted to the PCell, and / or apply the sPCellConfig associated with the indicated SCell.

[0108] For example, when a WTRU receives an L1 / L2 mobility signaling indication, it can reset counters used while performing Radio Link Monitoring (RLM) on the SpCell. For instance, N310 might be used to count the number of "out-of-sync" indications from lower layers. In another example, N311 might be used to count the number of "synchronized" indications from lower layers. For example, when a WTRU receives an L1 / L2 mobility signaling indication, it can stop any running timers used while performing RLM for the SpCell. For example, T310 might be started when it detects a physical layer problem with the SpCell, for example, when it receives N310 consecutive out-of-sync indications from lower layers. For example, T312 might be started when a measurement report for a measurement identity that T312 may have configured is triggered while T310 is running on the SpCell.

[0109] In one example, upon receiving L1 / L2 signaling, the WTRU may hold the current SpCell as an active SCell. In another example, upon receiving L1 / L2 signaling, the WTRU may hold the current SpCell as an SCell but in a dormant state (e.g., associating the cell with a dormant bandwidth portion). In yet another example, upon receiving L1 / L2 signaling, the WTRU may keep the current SpCell as an SCell, but in an inactive state. In yet another example, upon receiving L1 / L2 signaling, the WTRU may release the cell configuration associated with the current SpCell instead of demoting it to an SCell (e.g., applied to the previous SpCell). In yet another example, the L1 / L2 signaling may include an indication regarding one of the above behaviors concerning the processing of the current SpCell (e.g., release, keep in a dormant state as an SCell, keep in an inactive state as an SCell, keep in an active state as an SCell, etc.). For example, a WTRU might be configured to determine which of the above behaviors regarding the processing of the current SpCell is applied before receiving an L1 / L2 mobility indication (e.g., dedicated signaling via RRC / MAC, broadcast signaling, etc.) (e.g., release, keep as dormant as SCell, keep as deactivated as SCell, keep as active as SCell, etc.). For example, the behavior of the current SpCell during L1 / L2 mobility might be the same for any cell in the serving cell list and / or candidate set list.

[0110] For example, a WTRU might consist of different behaviors regarding the processing of the current SpCell, depending on the current SpCell's (e.g., type). For instance, a WTRU might be configured to keep a cell as an active SCell if its frequency is equivalent to and / or falls within a specific range of values, while keeping a cell as an inactive SCell if its frequency is different from and / or does not fall within a given range of values. Other criteria, such as bandwidth, could also be used in addition to frequency. It is also conceivable that the behavior could be explicitly indicated for each candidate / serving cell (e.g., as part of the SpCell configuration associated with that given cell, as part of the SCellConfig, etc.).

[0111] For example, the determination of the SCell state (for example, for a SpCell that is currently SCell) may be based on the cell's signal level. For example, two thresholds may be configured, where the SCell state may be activated if the cell has a signal level above the first threshold. For example, two thresholds may be configured, where the SCell state may be dormant if the cell has a signal level between the first and second thresholds. For example, two thresholds may be configured, where the SCell state may be deactivated if the cell's signal level falls below the second threshold.

[0112] For example, a WTRU might be configured with only one SpCellConfig, which is initially associated with the current SpCell but may become associated with a new SpCell when an SCell is promoted to a SpCell. For instance, a WTRU might not need to reapply the SpCellConfiguration when another cell becomes a SpCell. For example, some parts / IEs of the SpCellConfig may be shared by all cells, while others may be explicitly associated with a given cell. For example, a dedicated serving cell configuration for a SpCell (e.g., spCellConfigDedicated IE) may be specific to each cell, while the rest of the SpCellConfig may be reused by each cell. Which IEs are shared may be fixed in the 3GPP RRC specification, and / or the network may dynamically (e.g., implicitly or explicitly) indicate to the WTRU which IEs are shared and which are not.

[0113] In the example where a candidate cell list is provided, the candidate cell list may include a list of "delta" configurations (e.g., SpCell parameters different from the initial SpCell configuration) rather than a list of complete SpCell and / or SCell configurations. In one example, when L1 / L2 mobility signaling is received, the WTRU may hold a SpCell configuration / IE that can be shared by all cells, but may apply an IE that can be explicitly associated with the SCell being promoted to become a SpCell.

[0114] Figure 11 is a flowchart illustrating how a WTRU may perform an L1 / L2 switchover of a primary cell (PCell) in a manner that may not require RRC reconfiguration for subsequent PCell changes. This method may include, for example, releasing cell-specific information for the source cell while maintaining common information during the handover. In other words, for example, a WTRU can perform an L1 / L2 switchover of a PCell without performing a new subsequent cell group configuration. In 1102, the WTRU may receive configuration information for one or more candidate cells for LTM. The configuration information may include a configuration common to multiple cells (e.g., a serving cell and candidate cells) and / or a configuration specific to each candidate cell. In 1104, the WTRU may receive an LTM command indicating a handover (HO) to a candidate cell. The LTM command may include, for example, a media access control element (MAC EE) or physical layer downlink control information (PHY DCI). In 1106, the WTRU may retain and / or apply a configuration shared by multiple cells. In 1108, the WTRU can release the configuration associated with the current serving cell. In 1110, the WTRU can apply a configuration specific to the indicated candidate cell. In 1112, the WTRU can send an HO complete message to the network. In this method, the WTRU can receive configuration information including configurations common to multiple cells and / or configurations specific to each candidate cell (1). The WTRU can perform an L1 / L2 switch of the primary cell with minimal signaling requirements and without RRC configuration in between. In other words, the WTRU can perform an L1 / L2 switch of the primary cell without sending and receiving complete WTRU configuration information. The WTRU can perform an L1 / L2 switch of one or more primary cells. In this method, the WTRU can receive additional LTM commands but not additional RRC configuration. For example, the WTRU can receive a second handover LTM command indicating an HO to the previous candidate cell without additional reconfiguration.

Claims

1. A method performed by a wireless transmit / receive unit (WTRU), wherein the method is Receiving configuration information related to L1 / L2 trigger mobility (LTM), wherein the configuration information includes a candidate cell group configuration, the candidate cell group configuration includes common configuration information for a serving cell and at least one candidate cell, and the configuration information includes separate configuration information specific to each candidate cell of the serving cell and at least one candidate cell. Based on the common configuration information and the information specific to the serving cell, communication with the serving cell is performed. Receiving an LTM command indicating a handover (HO) to one of the candidate cells, To release the information specific to the serving cell, Without performing a reconfiguration of the configuration information related to the LTM, the handover to the candidate cell as a serving cell is performed using the common configuration information and the information specific to the indicated candidate cell among the at least one candidate cell. Methods that include...

2. The method according to claim 1, wherein the configuration information related to the received LTM is received via a media access control element (MAC EE), physical layer downlink control information (PHY DCI), or one or more radio resource control (RRC) reconfigurations.

3. The method according to claim 1, wherein the candidate cell group configuration is a first candidate cell group configuration, and performing the handover without performing the reconstruction of the configuration information related to the LTM includes performing the handover without receiving a second candidate cell group configuration.

4. The method according to claim 1, wherein the LTM command includes an existing index list, and the existing index list constitutes each candidate cell of the at least one candidate cell using index values.

5. The method according to claim 1, wherein the LTM command includes a unique index, and the unique index is assigned to one of the at least one candidate cell.

6. The method according to claim 1, wherein the candidate cell group configuration is applied as a master cell group (MCG) or a secondary cell group (SCG).

7. The method according to claim 1, wherein the candidate cell group configuration replaces a pre-configured MCG configuration or a pre-configured SCG configuration.

8. Applying the aforementioned common configuration information to the at least one candidate cell, Applying the separate configuration information specific to the indicated candidate cell among the at least one candidate cell, The method according to claim 1, further comprising:

9. The method according to claim 1, wherein the handover to the candidate cell is based on a delta configuration, the delta configuration includes a change in at least one parameter in the configuration information related to the LTM.

10. The method according to claim 9, wherein the delta configuration includes a change in one parameter in the configuration information related to the LTM.

11. A wireless transmitter / receiver unit (WTRU), wherein the WTRU is Transceiver and, Processor and The processor is equipped with, Receiving configuration information related to L1 / L2 trigger mobility (LTM) via the transceiver, wherein the configuration information includes a candidate cell group configuration, the candidate cell group configuration includes common configuration information for the serving cell and at least one candidate cell, and the configuration information includes separate configuration information specific to each candidate cell of the serving cell and at least one candidate cell. Based on the common configuration information and the information specific to the serving cell, communication with the serving cell is performed. The transceiver receives an LTM command indicating a handover (HO) to one of the candidate cells, To release the information specific to the serving cell, Without performing a reconfiguration of the configuration information related to the LTM, the handover to the candidate cell as a serving cell is performed using the common configuration information and the information specific to the indicated candidate cell among the at least one candidate cell. A WTRU configured to perform the following actions.

12. The WTRU according to claim 11, wherein the configuration information related to the received LTM is received via a media access control element (MAC EE), physical layer downlink control information (PHY DCI), or one or more radio resource control (RRC) reconfigurations.

13. The WTRU according to claim 11, wherein the candidate cell group configuration is a first candidate cell group configuration, and performing the handover without performing the reconstruction of the configuration information related to the LTM includes performing the handover without receiving a second candidate cell group configuration.

14. The WTRU according to claim 11, wherein the LTM command includes an existing index list, and the existing index list constitutes each candidate cell of the at least one candidate cell using index values.

15. The WTRU according to claim 11, wherein the LTM command includes a unique index, the unique index is assigned to one of the at least one candidate cell.

16. The WTRU according to claim 11, wherein the candidate cell group configuration is applied as a master cell group (MCG) or a secondary cell group (SCG).

17. The method according to claim 11, wherein the candidate cell group configuration replaces a pre-configured MCG configuration or a pre-configured SCG configuration.

18. The aforementioned processor, Applying the aforementioned common configuration information to the at least one candidate cell, Applying the separate configuration information specific to the indicated candidate cell among the at least one candidate cell, The method according to claim 11, further configured to perform

19. The method according to claim 11, wherein the handover to the candidate cell is based on a delta configuration, the delta configuration includes a change in at least one parameter in the configuration information related to the LTM.

20. The WTRU according to claim 19, wherein the delta configuration includes a change in one parameter in the configuration information related to the LTM.

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