Layer 1 or Layer 2 triggered mobility

Abstract

This application discloses that in wireless communications, a device may change, add, or handover between cells of network access for inter-cell mobility. This may involve Layer 1 and / or Layer 2 (L1 / L2) signaling for a user equipment (UE) moving between cells in a network. There may be a configuration message containing configuration for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells. Measurement reports with L1 measurements for the LTM candidate cells are used in a cell switch command to indicate a target LTM candidate cell that should trigger the execution of an LTM cell switch to the target LTM candidate cell. An LTM cell switch is a switch from a source cell to a target LTM candidate cell.

Description

[Technical Field]

[0001] Technical Field This document relates generally to wireless communications, and more particularly, to improved signaling for inter-cell mobility in mobile device communication systems. [Background technology]

[0002] background Wireless communication technologies are moving the world toward an increasingly connected and networked society. Wireless communication relies on efficient network resource management and allocation between user mobile stations and wireless access network nodes (including, but not limited to, wireless base stations). New generation networks are expected to provide high-speed, low-latency, and ultra-reliable communication capabilities and meet requirements from various industries and users. User mobile stations or user equipment (UE) are becoming more complex, and the amount of data communicated is constantly increasing. Communication improvements should be made to improve communication and meet the reliability requirements of vertical industries as well as support new generation network services. Summary of the Invention [Means for solving the problem]

[0003] overview This document relates to methods, systems, and devices for Layer 1 and / or Layer 2 (L1 / L2) signaling for user equipment (UE) moving between cells in a network. The signaling can reduce mobility interruption time and / or improve handover robustness. The movement can be triggered by the network or the UE. There can be a configuration message containing configuration for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells. Measurement reports with L1 measurements for LTM candidate cells are used for cell switch commands to indicate a target LTM candidate cell that should trigger the execution of an LTM cell switch to the target LTM candidate cell. An LTM cell switch is a switch from a source cell to a target LTM candidate cell.

[0004] In one embodiment, a method for wireless communication includes receiving a configuration message including configurations for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells, storing the configurations for the LTM candidate cells, transmitting a measurement report with L1 measurements for at least one of the LTM candidate cells, receiving a cell switch command from the LTM candidate cell to indicate a target LTM candidate cell, and performing an LTM cell switch to the target LTM candidate cell. The configurations for the LTM candidate cells include at least one of a list of candidate cell configurations, a list of candidate cell group-level configurations (CellGroupConfig), a list of candidate radio bearer configurations (RadioBearerConfig), or a list of candidate measurement configurations (MeasConfig). The configuration for each candidate includes at least one of a candidate cell configuration index, a cell group-level configuration, or a reference index. The reference index references an indicated cell group level configuration from a candidate cell group level configuration list, an indicated radio bearer configuration from a candidate radio bearer configuration list, an indicated measurement configuration from a candidate measurement configuration list, or an indicated candidate cell configuration from a candidate cell list. The configuration for the LTM candidate cell includes a group of configurations for each of the candidate cells, where each of the candidate cells in a group shares a common or reference configuration, and each of the candidate cells in a group has a delta configuration. The common or reference configuration is referenced by the reference index to reference a reference configuration from a reference configuration pool. The reference configuration pool includes at least one of a list of reference cell configurations, a list of reference cell group level configurations (CellGroupConfig), a list of reference radio bearer configurations (RadioBearerConfig), or a list of reference measurement configurations (MeasConfig). The configuration for the LTM candidate cell includes a common L1 measurement configuration pool.The common L1 measurement configuration pool includes at least one of a list of L1 reference signaling (RS) resources for the serving cell and the LTM candidate cell, a list of beam information for the serving cell and the LTM candidate cell, or a list of transmission configuration indication (TCI) status information for the serving cell and the LTM candidate cell. The configuration for the LTM candidate cell includes an information list indicating which L1 measurement configurations are associated with which of the candidate cells. An information item in the information list is configured to link RS resources with the candidate cell, link beam information with the candidate cell, or link TCI status information with the candidate cell. The RS resources, beam information, or TCI status are configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission. The information list is combined with the candidate cell configuration list or configured in the candidate cell configuration. The measurement report includes at least one of cell identification, RS identification, measurement identification, measurement result, indication of uplink (UL) synchronization completion, or indication of timing advance availability. The method includes performing downlink (DL) synchronization or uplink synchronization with the candidate cell before receiving a cell switch command. The method includes transmitting UL signaling to the target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or completion of the LTM cell switch. The UL signaling includes or indicates at least one of a target LTM candidate cell identity, a TCI status indication of the target LTM candidate cell, a beam / RS identity of the target LTM candidate cell, or an activated / deactivated SCell identity. The method includes starting a first timer upon receiving the cell switch command, the first timer being stopped upon successful execution of the LTM cell switch. The method includes determining a failure to perform the LTM cell switch based on expiration of the first timer. The method includes starting a second timer upon receiving the cell switch command or upon detecting a failure to perform the LTM cell switch, the second timer being stopped upon successful execution of the LTM cell switch.The method includes detecting a failure to perform an LTM cell switch and, if a second timer is running, performing an LTM cell switch to another LTM candidate cell. The method includes triggering an RRC re-establishment procedure if the second timer expires. The state of the LTM candidate cell includes at least one of a pre-configured state, a pre-configured but suspended state, an activated state, or a deactivated state. In the pre-configured state, the UE stores a cell configuration but does not apply the cell configuration, and the UE performs L1 measurements on the cell. Furthermore, in the pre-configured but suspended state, the UE stores a cell configuration, does not apply the cell configuration, and the UE stops performing L1 measurements on the cell.

[0005] In another embodiment, a method for wireless communication includes transmitting a configuration message including configurations for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells; receiving a measurement report with L1 measurements for at least one of the LTM candidate cells; and transmitting a cell switch command indicating a target LTM candidate cell from the LTM candidate cell and to trigger execution of an LTM cell switch to the target LTM candidate cell. The configurations for the LTM candidate cells include at least one of a list of candidate cell configurations, a list of candidate cell group level configurations (CellGroupConfig), a list of candidate radio bearer configurations (RadioBearerConfig), or a list of candidate measurement configurations (MeasConfig). The configuration for each candidate includes at least one of a candidate cell configuration index, a cell group level configuration, or a reference index. The reference index references an indicated cell group level configuration from a candidate cell group level configuration list, an indicated radio bearer configuration from a candidate radio bearer configuration list, an indicated measurement configuration from a candidate measurement configuration list, or an indicated candidate cell configuration from a candidate cell list. The configuration for the LTM candidate cell includes a group of configurations for each of the candidate cells, where each of the candidate cells in a group shares a common or reference configuration, and each of the candidate cells in a group has a delta configuration. The common or reference configuration is referenced by a reference index to reference a reference configuration from a reference configuration pool. The configuration for the LTM candidate cell includes a common L1 measurement configuration pool. The common L1 measurement configuration pool includes at least one of a list of L1 reference signaling (RS) resources for the serving cell and the LTM candidate cell, a list of beam information for the serving cell and the LTM candidate cell, or a list of transmission configuration indication (TCI) status information for the serving cell and the LTM candidate cell. The configuration for the LTM candidate cell includes an information list indicating which of the L1 measurement configurations is associated with which of the candidate cells.The information items in the information list are configured to link RS resources with the candidate cell, link beam information with the candidate cell, or link TCI status information with the candidate cell. The RS resources, beam information, or TCI status are configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission. The information list is combined with the candidate cell configuration list or configured within the candidate cell configuration. The measurement report includes at least one of a cell identification, an RS identification, a measurement identification, a measurement result, an indication of uplink (UL) synchronization completion, or an indication of timing advance availability. The method includes receiving UL signaling to a target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or completion of a cell switch, wherein the UL signaling includes or indicates at least one of a target LTM candidate cell identification, a TCI status indication of the target LTM candidate cell, a beam / RS identification of the target LTM candidate cell, or an activated / deactivated SCell identification.

[0006] In one embodiment, a wireless communications device comprises a processor and a memory, the processor configured to read code from the memory to implement any of the previously described embodiments.

[0007] In one embodiment, a computer program product includes a computer readable program medium having stored thereon code that, when executed by a processor, causes the processor to perform any of the aforementioned embodiments.

[0008] In some embodiments, there is a wireless communications device comprising a processor and a memory, the processor configured to read code from the memory to perform any of the methods described in any of the embodiments. In some embodiments, a computer program product includes a computer-readable program medium having stored thereon code that, when executed by the processor, causes the processor to perform any of the methods described in any of the embodiments. These and other aspects and their implementations are described in more detail in the drawings, the description, and the claims. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows an example of a base station. [Figure 2] 1 illustrates an example of a random access (RA) messaging environment. [Figure 3] The network architecture of the base station central unit (CU) and the base station distributed unit (DU) is shown. [Figure 4] 1 illustrates an embodiment of user equipment (UE) intra-DU mobility. [Figure 5] 1 illustrates an embodiment of user equipment (UE) intra-CU and inter-DU mobility. [Figure 6] 1 illustrates an embodiment of user equipment (UE) inter-CU mobility. [Figure 7] 1 illustrates an embodiment of a signaling procedure for L1 / L2 triggered mobility (LTM). [Figure 8] 1 illustrates one embodiment of a candidate cell group list structure. [Figure 9] 1 illustrates one embodiment of a candidate cell signaling structure. [Figure 10] 1 illustrates one embodiment of a signaling structure for an L1 measurement configuration. [Figure 11a] 1 illustrates a first embodiment of a configuration signaling structure. [Figure 11b] An example of a cell group configuration from Figure 11a is shown. [Figure 11c]An example of the cell information list from FIG. 11a is shown. [Figure 11d] 11 shows an example of a resource configuration pool from FIG. 11a. [Figure 11e] 11 shows an example of a candidate cell configuration list from FIG. 11a. [Figure 12] 10 illustrates a second embodiment of a configuration signaling structure. [Figure 13] 10 illustrates a third embodiment of a configuration signaling structure. [Figure 14] 1 shows an example of network signaling for LTM. [Figure 15] 10 shows another example of network signaling for LTM. [Figure 16] 1 illustrates an example of cell or cell group (CG) state transfer. DETAILED DESCRIPTION OF THE INVENTION

[0010] Detailed Description The present disclosure will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific embodiments. It should be noted, however, that the present disclosure may be embodied in many different forms, and therefore, the subject matter embraced or claimed should not be construed as limited to any of the embodiments set forth below.

[0011] Throughout this specification and claims, terms may have nuanced meanings suggested or implied in context beyond their explicitly stated meaning. Similarly, the phrases "in one embodiment" or "in some embodiments" used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used herein do not necessarily refer to different embodiments. The phrases "in one implementation" or "in some implementations" used herein do not necessarily refer to the same implementation, and the phrases "in another implementation" or "in other implementations" used herein do not necessarily refer to different implementations. For example, the claimed subject matter is intended to include, in whole or in part, combinations of exemplary embodiments or implementations.

[0012] Generally, terms may be understood, at least in part, from their use in context. For example, terms such as "and," "or," and "and / or," as used herein, may include a variety of meanings that may depend, at least in part, on the context in which such terms are used. Typically, "or," when used to relate a list such as A, B, or C, is intended to mean A, B, and C, which are used herein in an inclusive sense, as well as A, B, or C, which are used herein in an exclusive sense. Furthermore, as used herein, the terms "one or more" or "at least one" may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," "the," and the like, may also be understood to convey singular usage or plural usage, depending, at least in part, on the context. Additionally, the terms "based on" or "determined by" may be understood as not necessarily intended to convey an exclusive set of factors, but instead may allow for the existence of additional factors not necessarily explicitly described, depending at least in part on the context.

[0013] Radio Resource Control ("RRC") is a protocol layer between a UE and a base station at the IP level (network layer). Various Radio Resource Control (RRC) states may exist, such as an RRC_CONNECTED state, an RRC_INACTIVE state, and an RRC_IDLE state. RRC messages are transmitted via the Packet Data Convergence Protocol ("PDCP"). As described, a UE can transmit data via a random access channel ("RACH") protocol or a configuration grant ("CG") scheme. CG may be used to reduce waste of periodically allocated resources by allowing multiple devices to share the periodic resources. A base station or node may allocate CG resources to eliminate packet transmission delays and increase utilization of allocated periodic radio resources. The CG scheme is only one example of a protocol scheme for communication; other examples are possible, including but not limited to RACH. Wireless communication described herein may be via radio access.

[0014] As described below with respect to FIGS. 1-6, a network provider may include multiple network nodes (i.e., base stations) for providing network access to user equipment (“UE”) devices. The network nodes are referred to as base stations in some embodiments. FIGS. 4-6 illustrate cell mobility, in which a UE device moves between cells. Control signals may be used to facilitate this mobility. The control signaling supports transmission of downlink and uplink transport channels and may be referred to as Layer 1 and / or Layer 2 (“L1 / L2”) signaling, indicating that corresponding information originates partly from the physical layer (Layer 1) and partly from the medium access control (MAC) (Layer 2). Specifically, Layer 1 may include the physical layer, and Layer 2 may include MAC, RLC, and PDCP. L1 / L2 mobility based on L1 / L2 signaling may have lower latency, lower overhead, and reduced disruption time.

[0015] There may be a master node ("MN") and one or more secondary nodes ("SNs"). An MN may include a master cell group ("MCG"), and each SN may include a secondary cell group ("SCG"). An MCG is a cell group served by a master node (MN), and an SCG is a cell group served by a secondary node (SN). An MCG may include a primary cell ("PCell") and one or more secondary cells ("SCells"). An SCG may include a primary secondary cell ("PSCell") and one or more secondary cells ("SCells"). Each primary cell may be connected to multiple secondary cells. Each primary cell (PCell, PSCell) is the master cell of its respective group (MCG, SCG, respectively) and may initiate initial access. A primary cell may be used for signaling and may be called a special cell ("spCell"). A special cell can be expressed as: spCell = PCell + PSCell. The inter-cell mobility described in these embodiments may be based on a PCell, a PSCell, and / or an SCell.

[0016] A user equipment ("UE") device may move between nodes or cells, in which case a handover or change / add operation may occur to improve network reliability for the moving UE. The movement may be from a source cell to a target cell based on several potential target cells, called candidates. Movement between cells may also involve multiple target cells that are potential candidate cells. Conditional Handover ("CHO") and Conditional PSCell Addition / Change ("CPAC") are described below. CPAC may include Conditional PSCell Change ("CPC") and / or Conditional PSCell Addition ("CPA").

[0017] Conditional handover ("CHO") can reduce handover interruption time and improve mobility reliability. CHO is a handover executed by a UE when one or more execution conditions are met. The UE can evaluate the execution condition(s) upon receiving the CHO configuration and can stop evaluating the execution condition(s) once a handover is triggered. The CHO configuration may include a configuration of a candidate PCell generated by a candidate target node and the execution condition(s) corresponding to the candidate cell.

[0018] Conditional PSCell Addition / Change ("CPAC") may involve a UE having a network configuration to initiate access to a candidate PSCell to consider whether the PSCell is suitable for SN addition or SN change, including intra-SN change. This consideration may be based on configured condition(s). UEs in a wireless network can operate in dual connectivity ("DC"), including intra-E-UTRA DC or multi-radio DC ("MR-DC"). In an intra-E-UTRA DC example, both the MN and SN provide E-UTRA access. In an MR-DC example, one node may provide new radio ("NR") access, and the other node provides E-UTRA or NR access.

[0019] To reduce mobility interruptions, a Dual Active Protocol Stack (DAPS)-based handover procedure may be utilized, in which the UE maintains simultaneous connections with the source and target cells after successful random access to the target cell until it releases the source cell.

[0020] FIG. 1 illustrates an example of a base station 102. A base station may also be referred to as a wireless network node and may be a network node (e.g., a master node (“MN”), a secondary node (“SN”), and a source / target node) illustrated in FIGS. 3A-7B. The base station 102 may be further identified as a nodeB (NB, e.g., eNB or gNB) in the context of mobile communications. An example base station may include wireless Tx / Rx circuitry 113 for receiving and transmitting to and from a user equipment (UE) 104. The base station may also include network interface circuitry 116 for coupling the base station to a core network 110, e.g., optical or wired interconnects, Ethernet, and / or other data transmission media / protocols.

[0021] The base station may also include system circuitry 122. The system circuitry 122 may include processor(s) 124 and / or memory 126. The memory 126 may include operations 128 and control parameters 130. The operations 128 may include instructions for execution by one or more of the processors 124 to support the functions of the base station. For example, the operations may process random access transmission requests from multiple UEs. The control parameters 130 may include parameters or support the execution of the operations 128. For example, the control parameters may include network protocol settings, random access messaging formatting rules, bandwidth parameters, radio frequency mapping allocations, and / or other parameters.

[0022] 2 illustrates an example of a random access messaging environment 200. In the random access messaging environment, a UE 104 may communicate with a base station 102 over a random access channel 252. In this example, the UE 104 supports one or more subscriber identity modules (SIMs), such as SIM 1202. An electrical and physical interface 206 connects the SIM 1202 to the rest of the user equipment hardware, for example, via a system bus 210.

[0023] The mobile device 200 includes a communications interface 212, system logic 214, and a user interface 218. The system logic 214 may include any combination of hardware, software, firmware, or other logic. The system logic 214 may be implemented using, for example, one or more systems on a chip (SoC), application-specific integrated circuits (ASICs), discrete analog and digital circuits, and other circuits. The system logic 214 is part of the implementation of any desired functionality for the UE 104. In this regard, the system logic 214 may include, by way of example, logic to facilitate music and video decoding and playback, e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback, application execution, acceptance of user input, storage and retrieval of application data, establishment, maintenance, and termination of cellular telephone calls or data connections, for example, Internet connections, establishment, maintenance, and termination of wireless network connections, Bluetooth® connections, or other connections, and display of related information on the user interface 218. The user interface 218 and input 228 may include a graphical user interface, a touch-sensitive display, haptic feedback or other tactile output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements. Further examples of input 228 include microphones, video and still image cameras, temperature sensors, vibration sensors, rotational and orientation sensors, headset and microphone input / output jacks, universal serial bus (USB) connectors, memory card slots, radiation sensors (such as IR sensors), and other types of input.

[0024] The system logic 214 may include one or more processors 216 and a memory 220. The memory 220 stores, for example, control instructions 222 that the processor 216 executes to perform desired functions of the UE 104. Control parameters 224 provide and specify configuration and operation options for the control instructions 222. The memory 220 may also store BT, WiFi, 3G, 4G, 5G, or other data 226 that the UE 104 transmits or receives via the communication interface 212. In various implementations, system power may be provided by a power storage device, such as a battery 282.

[0025] In the communication interface 212, radio frequency (RF) transmit (Tx) and receive (Rx) circuitry 230 handles the transmission and reception of signals via one or more antennas 232. The communication interface 212 may include one or more transceivers. A transceiver may be a wireless transceiver that includes modulation / demodulation circuitry, digital-to-analog converters (DACs), shaping tables, analog-to-digital converters (ADCs), filters, waveform shapers, filters, preamplifiers, power amplifiers, and / or other logic for transmitting and receiving via one or more antennas or (in the case of some devices) via a physical (e.g., wired) medium.

[0026] Transmitted and received signals may conform to any of a diverse array of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and coding. As one specific example, communication interface 212 may include a transceiver supporting transmission and reception in 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA)+, and 4G / Long Term Evolution (LTE) standards. However, the techniques described below are applicable to other wireless communication technologies, whether they originate from the 3rd Generation Partnership Project (3GPP), GSM Association, 3GPP2, IEEE, or other partnerships or standards bodies.

[0027] Multiple RAN nodes (eNBs, gNBs, etc.) of the same or different radio access technologies ("RATs") can be deployed on the same or different frequency carriers in a particular geographic area and can interoperate via dual connectivity operations to provide shared communication services to the same target UE(s). A multi-RAT dual connectivity ("MR-DC") architecture may have a non-co-located master node ("MN") and secondary node ("SN"). The access mobility management function ("AMF") and session management function ("SMF") may be control plane entities, and the user plane function ("UPF") is the user plane entity in New Radio ("NR") or 5GC. The signaling connection between the AMF / SMF and the master node ("MN") may be a next-generation control plane ("NG-C") / MN interface. The signaling connection between the MN and SN may be an Xn-control plane ("Xn-C") interface. The signaling connection between the MN and the UE is the Uu-Control Plane ("Uu-C") RRC interface. All these connections govern the configuration and operation of the MR-DC. The user plane connection between the User Plane Function ("UPF") and the MN can be an instance of the NG-U(MN) interface.

[0028] Figure 3 shows a network architecture of base station central units (CUs) and base station distributed units (DUs). Figure 3 illustrates a base station (labeled gNB) communicating with an overall network (labeled "5GC"). The base stations can communicate with each other via a control plane interface ("Xn-C"). One base station is shown as having one CU connected to two DUs via an F1 interface. This is only one example of a base station arrangement. In some embodiments, there may be one or any number of DUs connected to a single CU.

[0029] A base station can be divided into two physical entities named a central unit ("CU") and a distributed unit ("DU"). In general, the CU may provide support for the upper layers of the protocol stack, such as SDAP, PDCP, and RRC, while the DU may provide support for the lower layers of the protocol stack, such as RLC, MAC, and the physical layer. The CU may include operations for user data transfer, mobility control, radio access network sharing, session management, etc., except for functions exclusively assigned to the DU. The DU(s) are logical node(s) with a subset of base station functions and may be controlled by the CU.

[0030] A CU may be a logical node that hosts the RRC, SDAP, and PDCP protocols of a base station or that controls the operation of one or more DUs. A DU may be a logical node that hosts the RLC layer, MAC layer, and PHY layer of a base station, and its operation may be at least partially controlled by a CU. A single DU may support one or more cells. However, each cell is supported by only a single DU. Each base station may support multiple cells. As described in embodiments herein, cell mobility between cells may be from different CUs or DUs, or may be internal to a CU and / or DU.

[0031] L1 / L2 Mobility The L1 / L2-based inter-cell mobility described herein can occur in several different scenarios. For L1 / L2 mobility, there can be intra-DU mobility, in which a UE changes cells within a single DU. Examples of intra-DU mobility include 1) a PCell change within one DU (which may also include a PCell change accompanied by an SCell change), 2) a PSCell change within one DU (which may also include a PSCell change accompanied by an SCell change), and 3) a PCell change within one DU accompanied by a PSCell change within one DU (which may also include an SCell change within a cell group). Another L1 / L2 mobility embodiment can be intra-CU and inter-DU mobility, in which a UE changes cells between different DUs but within a single CU. Examples of intra-CU and inter-DU mobility include 1) a PCell change across DUs but within one CU (which may also include a PCell change accompanied by an SCell change), and 2) a PSCell change across DUs but within one CU (which may also include a PSCell change accompanied by an SCell change). In another L1 / L2 mobility embodiment, there may be inter-CU mobility, in which a UE changes cells between different CUs. Examples of inter-CU mobility include 1) a PCell change across CUs (which may also include a PCell change with an SCell change), and 2) a PSCell change across CUs (which may also include a PSCell change with an SCell change). In another embodiment, there may be an SCell change / addition, and examples of this may include an SCell addition / change within a cell group. Figures 4 to 6 illustrate embodiments of UE mobility between cells.

[0032] FIG. 4 illustrates an embodiment of user equipment (UE) intra-DU mobility. A base station may include a CU and at least one DU. In this embodiment, a single DU with multiple cells is shown. Cell 1 and Cell 2 are both from a single DU. In this example, a UE 402 may move from Cell 1 to Cell 2, and FIG. 4 illustrates the trajectory of the UE from Cell 1 to Cell 2. Inter-cell mobility may occur when the UE 402 is located between two cells and moves to a third location within Cell 2. This is intra-DU mobility because the UE is moving between cells within a single DU.

[0033] FIG. 5 illustrates an embodiment of user equipment (UE) intra-CU and inter-DU mobility. In this embodiment, a base station may include a CU and two DUs (DU_1 and DU_2). While each DU may have multiple cells, in this example, each DU is shown serving a single cell, such as DU_1 serving cell 1 and DU_2 serving cell 2. In this example, a UE 502 may move from cell 1 to cell 2, and FIG. 5 illustrates the UE's trajectory from cell 1 to cell 2, which also results in movement from DU_1 to DU_2. Inter-cell mobility may occur when a UE 402 is located between two cells and moves to a third location within cell 2. This is intra-CU mobility because the UE is moving between cells within a single CU. However, this is also inter-DU mobility because the UE is moving between different DUs.

[0034] FIG. 6 illustrates an embodiment of user equipment (UE) inter-CU mobility. In this embodiment, a base station may include multiple CUs (CU_1 and CU_2). While each CU may include multiple DUs, in this example, each CU is shown as having one corresponding DU (CU_1 has DU_1, and CU_2 has DU_2). Each DU is shown with multiple cells. In this example, the UE trajectory of UE 602 progresses from Cell_2 to Cell_3, from inter-CU location 604 (between CU_1 and CU_2) to Cell_5 and Cell_6. As the UE moves, mobility can change cells and move between multiple cells as shown. Because UE 602 (at inter-CU location 604) switches cells from CU_1 to CU_2, this transition is referred to as inter-CU mobility.

[0035] L1 / L2 Triggered Mobility (LTM) Inter-cell mobility can be triggered by L1 / L2 signaling to improve inter-cell mobility. L1 / L2 mobility extensions can provide serving cell changes via L1 / L2 signaling with such lower latency, lower overhead, and lower disruption times. An example described throughout can be LTM procedures and signaling.

[0036] In the following description, a candidate cell may be referred to as a candidate cell group (CG), or a candidate CG may be referred to as a candidate cell. A candidate CG may be referred to as a candidate MCG or a candidate SCG. A candidate cell may be referred to as a candidate PCell in a candidate MCG, or a candidate PSCell in a candidate SCG.

[0037] FIG. 7 illustrates an embodiment of a signaling procedure for L1 / L2 triggered mobility (LTM). L1 / L2 triggered mobility (LTM) may include a procedure in which a base station receives L1 measurement reports from a UE and uses them to change the UE's serving cell through L1 / L2 signaling (e.g., MAC CE, DCI). The base station prepares one or more candidate cells and provides the UE with candidate cell configurations via an RRC message. An LTM cell switch is then triggered by the base station selecting one of the candidate configurations as the target configuration for LTM. The overall procedure for LTM is illustrated in FIG. 7. Subsequent LTMs can be performed by repeating the early synchronization, LTM execution, and LTM completion steps without releasing other candidates after each LTM completion. As illustrated, in one embodiment, there may be four main parts: 1) LTM preparation, 2) early synchronization, 3) LTM execution, and LTM completion.

[0038] The procedure shown in FIG. 7 for LTM may include the following: 1. The UE sends a Measurement Report message to the base station, which decides to use LTM and starts preparing for LTM. 2. The base station transmits an RRCReconfiguration message to the UE, which includes the configuration of one or more LTM candidate target cells. 3. The UE stores the configuration of the LTM candidate target cell and sends an RRCReconfigurationComplete message to the base station. 4a / b. The UE may perform DL synchronization and / or UL synchronization (ie, TA acquisition) with the candidate target cell before receiving the LTM cell switch command. 5. The UE performs L1 measurements on the configured LTM candidate target cells and transmits lower layer measurement reports to the base station. The order of steps 4a / b and 5 may be changed. The UE may perform L1 measurements before performing DL synchronization and / or UL synchronization. 6. The base station decides to perform an LTM cell switch to the target cell and transmits a MAC CE triggering the LTM cell switch by including the candidate configuration index of the target cell. The UE switches to the configuration of the LTM candidate target cell. 7. If TA is not available, the UE performs a random access procedure towards the target cell. 8. The UE indicates successful completion of the LTM cell switch to the target cell.

[0039] Candidate cell / cell group configuration The NW configures and provides one or more LTM candidate cell configurations via an RRC message, for example, an RRCReconfiguration message.

[0040] The candidate cell configuration (ie, the RRC model of the candidate cell configuration) can be configured with different options. Option 1: One RRCReconfiguration message per candidate configuration, and Option 2: One or more IEs for each candidate configuration. The IEs may include at least one of the following: RRCReconfiguration IE, CellGroupConfig IE, RadioBearerConfig IE, MeasConfig IE, etc.

[0041] For option 2, the signaling structure may include at least one of the following: Option 2a: Have a general LTM candidate configuration list (e.g., ltm-CandidateToAddModList, ltm-CandidateToRemoveList). Each LTM candidate configuration contains a candidate configuration index, a CellGroupConfig IE, and other possible / necessary configured IEs, e.g., RadioBearerConfig, MeasConfig. · Option 2b: There can be separate LTM candidate part lists for each possible IE (e.g. candidate CellGroupConfig ToAddMod / ToRelease list, candidate RadioBearerConfig ToAddMod / ToRelease list, candidate MeasConfig ToAddMod / ToRelease list, and add some mappings / links between them to have a complete LTM candidate configuration).

[0042] In option 2b, considering that several candidate cells may share a common radio bearer configuration (e.g., intra-DU candidates) and / or measurement configuration (e.g., for intra-frequency candidates), separate radio bearer configuration lists and measurement configuration lists may enable candidate cells to reference the required configuration parts from separate lists.

[0043] A candidate cell configuration (eg, CellGroupConfig) may be linked with other possible configurations (eg, RadioBearerConfig, MeasConfig) according to several options. · Alternative.1: For each candidate cell configuration, it may include a candidate cell configuration index, a candidate cell group level configuration (e.g., CellGroupConfig IE), one or more reference indexes for referencing other IE configurations from a separate reference configuration list / pool (e.g., a candidate radio bearer configuration index for referencing an indicated radio bearer configuration from the candidate radio bearer configuration list, a candidate measurement configuration index for referencing an indicated measurement configuration from the candidate measurement configuration list, etc.). Alternative 2: In the reference configuration list, for each reference configuration, there may be a link with one or more candidate cell indices to indicate that the configuration may be used by the associated candidate cell. For example, in the candidate radio bearer configuration list, for each candidate radio bearer configuration, there may be a link with one or more candidate cell indices to indicate that the configuration may be used by the associated candidate cell. A similar structure may be applicable to the candidate measurement configuration list.

[0044] An example ASN.1 structure for an LTM candidate configuration (for option 2 above) includes: [Table 1-1] [Table 1-2]

[0045] Figure 8 shows one embodiment of a candidate cell group list structure. Figure 8 illustrates one example of a signaling structure that can be used for signaling optimization. A network / base station can configure several candidate cell groups (e.g., candidateCellGroupList). Each candidate cell group includes one or more candidate target cell configurations. Candidate cells included in one candidate cell group may share some common configurations (e.g., see the same reference configuration). Different candidate cell groups can be associated with different reference configurations. There can be a group of configurations for each candidate cell. Each candidate cell group (CCG) can include different candidate cell configurations. Reference configurations can be configured in separate reference configuration pools. Each reference configuration can be referenced from a candidate cell group (e.g., by indicating a reference configuration index).

[0046] During cell switch, if the UE resets the cell switch command, the UE may need to reset L2 processing. In one CCG structure example, the UE may differ from the CCG reference / structure. The network / base station may configure all candidate cells belonging to one DU into one candidate cell group (CCG). In this example, cell switch between candidate cells belonging to one candidate cell group (i.e., intra-group cell switch) is intra-DU LTM (i.e., the UE does not need to perform an L2 reset when triggering a cell switch). Cell switch between candidate cells belonging to different candidate cell groups (i.e., inter-group cell switch) is inter-DU LTM (i.e., the UE needs to perform an L2 reset when triggering a cell switch). Therefore, the cell switch command may indicate a candidate cell group ID and a candidate cell configuration ID to help the UE distinguish between intra-DU LTM and inter-DU LTM.

[0047] The network / base station can also configure candidate cells belonging to one DU into different candidate cell groups (CCGs). Candidate cells belonging to one cell group must belong to one DU. In this example, the intra-group cell switch is an intra-DU LTM. The inter-group cell switch can be an intra-DU LTM or an inter-DU LTM. Therefore, if the cell switch is an inter-group cell switch, the network / base station can further indicate in the cell switch command whether the cell switch is intra-DU or inter-DU. The cell switch command may include at least one of the following information: Candidate cell group ID / index, Candidate cell configuration ID / index, or -Indication of whether the cell switch is an intra-DU cell switch or an inter-DU cell switch

[0048] If the received candidate cell group ID / index is the same as the CCG ID / index that refers to the CCG containing the candidate cell configuration currently applied by the UE, the UE may consider the cell switch as an intra-DU cell switch. Otherwise, the UE may consider the cell switch as an inter-DU cell switch. In the case of an intra-DU cell switch, the UE may not perform an L2 reset during the cell switch, or may perform a partial L2 reset (e.g., a partial MAC reset). In the case of an inter-DU cell switch, the UE may perform an L2 reset during the cell switch. The L2 reset may include a MAC reset, RLC re-establishment, and / or PDCP data recovery.

[0049] For each LTM candidate cell configuration, it may be configured with a delta configuration, a reference configuration, and / or a reference index. The reference index may be used to indicate a cell configuration that the UE can use as a baseline / template / reference for the LTM candidate cell configuration. The LTM candidate cell configuration may include at least one of the following: · Candidate cell configuration index, Cell group configuration, e.g. CellGroupConfig IE, a reference index (e.g., a reference cell group configuration ID) for referencing the indicated cell group level configuration from the candidate cell group level configuration list; Radio bearer configuration, e.g., RadioBearerConfig IE, a reference index (e.g., reference radio bearer configuration ID) for referencing the indicated radio bearer configuration from the candidate radio bearer configuration list; RRM measurement configuration, e.g. MeasConfig IE, a reference index (e.g., reference meas configuration ID) for referencing the indicated RRM measurement configuration from the candidate measurement configuration list; A reference index (e.g., reference cell ID) for referencing the indicated candidate cell configuration from the candidate cell list.

[0050] For each IE in the LTM candidate cell configuration, it may also be configured with a delta configuration or a reference index.

[0051] For some dedicated / specific configurations of a candidate cell (e.g., TA / TAG configuration, CFRA resource configuration, BWP configuration, or C-RNTI), the network / base station may configure some common configuration pool for possible resources / configurations required by all serving and candidate cells. The association of a candidate cell with a dedicated / specific configuration may include the following options: Option 1: A separate list may be configured by the network / base station to associate candidate cells with dedicated / specific configurations (eg, configuration indexes linked with candidate cell indexes). Option 2: The association of a particular resource / configuration with a candidate cell may be indicated in the candidate cell configuration (ie, via an RRC message) (eg, by including a configuration index in the candidate cell configuration). Option 3: The association of a particular resource / configuration with a candidate cell can be indicated (or dynamically indicated) by the cell switch command (eg, by including a configuration index in the cell switch command).

[0052] A reference configuration can be defined to reduce overhead for each candidate cell. Each candidate cell can have multiple partial configurations to generate a complete / full configuration. Handover (HO) may use the source configuration for baseline and reconfiguration of different parts of the candidate cell is used to improve performance. Delta configurations can be different / other parts of the reference configuration. The LTM candidate cell configuration can be configured with the delta configuration. The delta configuration is generated based on the reference configuration. The reference configuration definition can have the following options: Option 1: The reference configuration is explicitly configured by the NW (i.e., a separate reference configuration). Option 1-1: Designate / indicate one of the candidate cells as a reference configuration (e.g., the network / base station indicates a reference cell index in each candidate cell configuration). Option 1-2: Define one reference configuration independent of the candidate cell configurations. Option 2: The reference configuration is the UE configuration when the candidate cell configuration is received, i.e. the initial source configuration. Option 3: The reference configuration is the UE configuration at the time the cell switch command is received. In one example, the network / base station provides cells 1, 2, and 3, and the UE maintains a configuration for each cell, so there is no need to provide updates for each candidate configuration based on the pre-configuration. Option 3-1: For each candidate cell, the network / base station pre-configures several candidate delta configurations, and each candidate delta configuration is configured based on a possible source cell (eg, initial source cell, other candidate cells). Option 3-2: Upon receiving the candidate cell configuration, for each candidate cell, the UE converts the received candidate cell configuration and generates a set of delta configurations based on the possible source cells.

[0053] For option 1, the reference configuration may be configured as 1) a full set of cell configurations, e.g., including the RRCReconfiguration message; 2) a set / pool of common configurations among multiple cells (e.g., a set / pool of RSs across source and candidate cells); or 3) several sets of reference configurations for different configuration parts (e.g., a set of reference cell group configurations, a set of reference radio bearer configurations, or a set of reference measurement configurations).

[0054] Figure 9 shows one embodiment of a candidate cell signaling structure. Specifically, Figure 9 may apply to Option 3 above. For each candidate cell, there may be a set of delta configurations, where each delta configuration is linked to a reference cell ID (e.g., another candidate cell index). If there is no reference cell ID, it may mean that the delta configuration is generated based on the initial source configuration. In an inter-DU example, each candidate DU may need to know the candidate cell configurations generated by other candidate DUs (e.g., full configurations or delta configurations based on the initial source configuration). This procedure may introduce additional complex interactions between the CU and the candidate DU.

[0055] The UE's behavior upon receiving the reference and / or candidate cell configurations may include the UE storing the reference configuration and the candidate cell configuration separately in different variables (e.g., storing the reference configuration as a separate configuration, such as storing the reference configuration in VarReferenceConfig). If the reference configuration is an initial source configuration, the UE may store the source configuration as a separate configuration upon receiving the candidate cell configuration or after completion of the initial / first LTM run (e.g., switching from the initial source cell to the candidate cell). In an alternative example, the UE converts each delta configuration to a full configuration and stores the full configuration for each candidate cell.

[0056] For options 1 and 2, upon triggering LTM execution (e.g., receiving a cell switch command), the UE may first restore or revert to the reference configuration and then apply the delta configuration of the target candidate cell based on the reference configuration. During this procedure, the UE may need to release and add back some RLC bearers. For example, the reference configuration includes two RLC bearers, and candidate cell #1 has two RLC bearers (e.g., RLC bearer 1 and RLC bearer 2), while candidate cells #2 and #3 have three RLC bearers (e.g., RLC bearer 1, RLC bearer 2, and RLC bearer 3). For the first cell switch from cell #1 to cell #2, the UE needs to add a third RLC bearer for cell #2 based on the reference configuration. For the second cell switch from cell #2 to cell #3, the UE first needs to fall back to the reference configuration, which requires releasing RLC bearer 3. The UE then applies the delta configuration of cell #3 based on the reference configuration, which requires re-adding RLC bearer 3. The RLC bearer release and add operation has the same effect as re-establishing RLC (e.g., the UE shall discard all RLC SDUs, RLC SDU segments, and RLC PDUs, if any), and resets all state variables to their initial values. Similar considerations apply to the release of an SCell, which can be added, for example, to sCellToAddModList.

[0057] To avoid unnecessary releases and additional problems, there may be several possible solutions. · Alternative 1: The reference configuration includes all possible RLC bearers and / or SCells across all candidate cells. Alternative 2: Upon receiving the cell switch command, the UE stores the RLC state variables and data stored in the transmit and receive buffers in the RLC entities and then reverts to the reference configuration. After applying the delta configuration based on the reference configuration, the UE restores the corresponding RLC state variables and data in the transmit and receive buffers of each established RLC entity. · Alternative.3: The network / base station must not reconfigure RLC bearers for LTM, i.e., RLC bearers cannot be added, modified, or released for LTM candidate cell configuration.

[0058] In the case of option 3, when an LTM execution is triggered (e.g., upon receipt of a cell switch command), the UE may directly apply the delta configuration of the target candidate cell based on the current source cell, e.g., applying the delta configuration linked with a reference index to refer to the current source cell.

[0059] L1 measurement configuration For L1 measurement configuration, the UE needs to perform L1 measurements for each candidate cell. The network / base station provides L1 measurement information for each candidate cell configuration. There may be inter-cell beam management (ICBM) supporting SSB-based L1 measurements for non-serving cell beams by configuring L1 SSB measurement resources for non-serving cells in the ServingCellConfig and associating the TCI state with AdditionalPCI (i.e., non-serving cell PCI). Rel-17 ICBM may be applicable for intra-DU frequency examples. To support inter-cell L1 measurements for LTM candidate cells, several enhancements may be considered.

[0060] Figure 10 shows one embodiment of a signaling structure for L1 measurement configuration. L1 measurement resources for non-serving cells (i.e., additional PCI information in additionalPCI-ToAddModList and associated SSB configuration) can be configured under ServingCellConfig. TCI states may be linked with non-serving cells by indicating the additional PCI index configured by additionalPCI-ToAddModList in ServingCellConfig. In CSI-MeasConfig, CSI-SSB resources for non-serving cells are indicated by servingAdditionalPCIList-r17 in the CSI-SSB-ResourceSet in csi-SSB-ResourceSetToAddModList. There may be additional PCI information indicating the PCI index and / or SSB configuration.

[0061] There are several possible options for the L1 measurement framework.

[0062] Option 1: Reuse the R17 ICBM framework (e.g., Figure 10), i.e., the L1 RS resources for the serving cell and candidate cell are explicitly indicated in the source cell configuration. In this example, the candidate DU and source DU may need to have some interaction via the CU. The CSI measurement configuration explicitly indicates the RS indices to be measured by the UE for the serving cell and candidate cell. The candidate DU provides the candidate cell RS configuration to the source DU via the CU. The source DU reconfigures or updates the L1 measurement configuration of the serving cell (e.g., CSI-MeasConfig) to provide the L1 RS resources for the serving cell and candidate cell, as well as the L1 reporting configuration, etc.

[0063] Option 2: The L1 RS resources of each candidate cell are included in each candidate cell configuration. In this example, the UE needs to decode and / or apply the L1 measurement configuration included in each candidate cell configuration before cell switching (e.g., upon receiving the LTM candidate cell configuration) in order to perform L1 measurements on the candidate cells.

[0064] Option 3: L1 RS resources and / or TCI states for the serving cell and candidate cell are configured in separate configuration sets, e.g., a common L1 measurement pool is used to configure the L1 measurement configuration and / or TCI state for the serving cell and candidate cell. The TCI state may be used to provide / configure the association between RSs / beams and cells. This may be similar to the reference configuration described above. Reference candidates are collected to be referenced by a resource index or reference index. The common L1 measurement pool can be generated by the CU or DU. The common L1 measurement pool configuration is always maintained. It can be updated or released via an RRC reconfiguration message. The network / base station may explicitly indicate / configure which candidate cells / RSs should be measured for LTM triggering (e.g., via CSI-MeasConfig). The network / base station may not explicitly indicate / configure which candidate cells / RSs should be measured for LTM triggering. For example, it may be up to the UE to measure and report the strongest RS index for the serving cell and target cell. The network / base station may dynamically indicate / activate which candidate cells / RSs should be measured for LTM triggering, thereby indicating candidate cell indexes, beam / RS indexes, and / or TCI status via L1 / L2 signaling.

[0065] The L1 measurement RS resource configuration may be used to avoid repeated RS resource configurations between candidate cells and reduce signaling overhead. The L1 measurement resource set configuration (e.g., SSB, CSI-RS resource configuration) may be separated from the serving cell configuration, i.e., it defines a set / pool of RS resource configurations. The RS resource configuration set / pool can be configured under the RRCReconfiguration message, the CellGroupConfig IE, or the ServingCellConfig IE. The RS resource configuration set / pool may include RS resource (e.g., SSB, CSI-RS) configurations to be measured by the serving cell and / or the candidate cell. The RS resource configuration (e.g., similar to CSI-ResourceConfig) may include at least one of 1) SSB resource configuration, 2) SSB resource set configuration, 3) CSI-RS resource configuration, or 4) CSI-RS resource set configuration, each of which is described below.

[0066] The SSB resource configuration may include at least one of the following: SSB Configuration Index Periodicity of SS / PBCH blocks, e.g., periodicity A bitmap for indicating the time domain positions of transmitted SS blocks within a half-frame containing SS / PBCH blocks, e.g., ssb-PositionsInBurst The average EPRE of resource elements carrying secondary synchronization signals used by the network / base station for SSB transmissions in dBm, e.g., ss-PBCH-BlockPower Measurement timing configuration (i.e., timing occasions for UE to measure SSB), e.g., SSB-MTC SSB frequency The SSB resource set configuration may include at least one of the following: SSB resource set configuration index, A list of SSB indices indicating the SSBs to be measured, A list of PCIs of associated SSBs, Measurement timing configuration (i.e., the timing occasions on which the UE measures SSB), e.g., SSB-MTC, or ·SSB frequency. The CSI-RS resource configuration may include at least one of the following: · CSI-RS configuration index, NZP CSI-RS resource configuration (including, for example, periodicity and slot offset for CSI-RS, power offset of RE, reference to TCI state, OFDM symbol location within slot and subcarrier occupancy within PRB of CSI-RS resource, scrambling ID), CSI-IM resource configuration (e.g., including resource element patterns), or ·CSI-RS frequency. The CSI-RS resource set configuration may include at least one of the following: · CSI-RS resource set configuration index, a list of CSI-RS resource indices to indicate the CSI-RS to be measured; CSI-RS frequency, or Other set-specific parameters.

[0067] An information list may be generated to indicate which L1 resource configurations are associated with which candidate cells. The information list may include additional / candidate cell information lists. The additional / candidate cell information lists (e.g., additionalPCI-ToAddModList, candidateCellToMeas-ToAddModList, TCI state list) may be configured to link RS resource configurations, beam information, or TCI states with different cells (e.g., including serving cells, non-serving cells, and / or candidate cells). The RS resources, beam information, or TCI states may be configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission. There may be additional / candidate cell information lists for UL transmission only, additional / candidate cell information lists for DL ​​transmission only, or additional / candidate cell information lists for both UL and DL transmission. Each item in the information list may include at least one of the following: Cell identification information, e.g., PCI, candidate cell ID / index, serving cell ID / index, candidate cell configuration ID / index, RS resource configuration index, e.g., to reference an RS configuration (e.g., CSI-RS, SSB) within an RS resource configuration set / pool; An SSB configuration index, e.g. to reference an SSB configuration within an RS resource configuration set / pool, For example, an SSB resource set configuration index to reference an SSB resource set configuration within an RS resource configuration set / pool a CSI-RS configuration index, e.g., to reference a CSI-RS configuration within an RS resource configuration set / pool, or For example, a CSI-RS resource set configuration index to reference a CSI-RS resource set configuration within an RS resource configuration set / pool.

[0068] For each candidate cell / DU, an additional / candidate cell information list may be configured by the network / base station (e.g., CU or DU). The above additional / candidate cell information list may be configured under the RRCReconfiguration message, the CellGroupConfig IE, and / or the ServingCellConfig IE. The additional / candidate cell information list may be combined with the candidate cell configuration list or may be configured within the candidate cell configuration. A TCI state list may be configured to link TCI states with cells in the additional / candidate cell list to indicate which cell's RS signal is configured as a QCL source for the associated TCI state.

[0069] Based on the above embodiment, a possible signaling structure for R18L1 measurement resource configuration may include: · Alternative.1: The RS resource configuration pool and / or additional / candidate cell information list are configured under ServingCellConfig (i.e., current structure). Alternative 2: RS resource configuration pool and / or additional / candidate cell information list are configured under CellGroupConfig. Figure 11a shows a first embodiment of the configuration signaling structure. Figures 11b-11e show the remaining structures of the configuration signaling structure. Figure 11b shows an example of a cell group configuration from Figure 11a. Figure 11c shows an example of a cell information list from Figure 11a. Figure 11d shows an example of a resource configuration pool from Figure 11a. Figure 11e shows an example of a candidate cell configuration list from Figure 11a. · Alternative 3: RS resource configuration pool and / or additional / candidate cell list are configured under RRCReconfiguration message, i.e. in parallel from CellGroupConfig. Figure 12 shows a second embodiment of the configuration signaling structure. Alternative 4: The additional / candidate cell information list is combined with the candidate cell configuration list, e.g., for each candidate cell, and the RS configuration (by referencing the RS configuration index) is configured directly in the candidate cell configuration. Figure 13 shows a third embodiment of the configuration signaling structure. The RS resource configuration pool can be configured under the CellGroupConfig of the source cell or under the RRCReconfiguration message.

[0070] The L1 measurement reporting configuration may be provided by a CSI-ReportConfig in a CSI-MeasConfig within a ServingCellConfig, for example, configured per cell. In the CSI-ReportConfig, a CSI-ResourceConfigId and a ServCellIndex may be referenced to indicate in which cell the indicated CSI-ResourceConfig should be found. The source cell needs to know the RS resource configurations generated by each candidate cell / DU to generate the reporting configuration (e.g., report type, report resource) for the L1 measurement report of such candidate cell. If the legacy L1 measurement mechanism is reused, it is necessary to configure which cells' RS resources can be measured and reported in each source serving cell, which may cause a complex and heavy signaling structure. One embodiment may enable the reuse of the L3 measurement mechanism (e.g., the UE may measure all configured L1 RS resources but report the strongest RS index).

[0071] Reporting mechanisms may include: Option 1: The network / base station explicitly configures / indicates in which cells RS resources can be measured and / or in which cells L1 reports can be sent, e.g. reusing the CSI measurement mechanism. The UE measures L1 RS and makes L1 measurement reports based on the network / base station configuration. Option 2: L1 RS resources are not explicitly configured / indicated per cell. The UE can measure all configured L1 RS resources but reports the strongest RS index, or the strongest RS index and associated cell ID, e.g., an L3-like measurement mechanism.

[0072] The reporting configuration may include at least one of the following information: Trigger event, e.g., L1 measurements of a candidate cell become better than a network / base station configuration threshold, and the number of L1 measurements of candidate cells better than the network / base station configuration threshold is greater than the number of network / base station configurations. · Maximum number of RS / beams and / or cells that can be reported in one L1 measurement report.

[0073] The report format may be UCI (e.g., CSI report) or MAC CE. The L1 measurement report content may include at least one of the following: Cell ID information, e.g., PCI, PCI+frequency, candidate cell configuration index, serving cell ID. RS / beam ID, e.g., RS / beam resource configuration index, SSB index, CSI-RS index, each RS ID may be associated with a cell ID. Additional / candidate cell information index used to indicate the association between RS / beam and cell, e.g. TCI State ID. L1 Measurement ID used to link RS resources with reporting Config L1 measurement results, e.g., L1-RSRP, L1-RSRQ, and / or L1-SINR. Indication to show whether UL synchronization is available / complete for the associated candidate cell and / or candidate RS / beam. Indication to show whether TA is available / obtained for the relevant candidate cell and / or candidate RS / beam.

[0074] For signaling optimization, a separate set / pool of reporting configurations can be configured, e.g., similar to RS resource configurations. For each reporting configuration, it may include at least one of a reporting configuration index, a report type, a number of reports, a reporting resource, etc. If the reports are transmitted on PUSCH (e.g., semi-persistent or aperiodic reports transmitted on PUSCH triggered by DCI, or reports signaled by MAC CE), it may not be necessary to configure PUCCH reporting resources in the reporting configuration.

[0075] A separate L1 measurement association list (e.g., measurement ID list) may be configured to link the RS resource configuration with the reporting configuration. For example, the L1 measurement ID list may include: · Alternative.1: RS resource configuration ID and report configuration ID, i.e. IDs to not indicate in which cells the RS resources should be found and in which cells the reports should be sent. · Alternative.2: RS resource configuration ID, cell ID where RS resources should be found, and reporting configuration ID. · Alternative.3: RS resource configuration ID, cell ID where RS resources should be found, reporting configuration ID, and cell ID where report should be sent. · Alternative.4: Additional / Candidate Cell Information Index (e.g., TCI State ID) and Reporting Configuration ID.

[0076] In some embodiments, the RS resource configuration ID and the cell ID where the RS resources should be found may be combined into one index (e.g., the additional / candidate cell information index described above). In some embodiments, the reporting configuration ID and the cell ID where the report should be sent are combined into one index. The reporting configuration set / pool may be configured under the RRCReconfiguration message, the CellGroupConfig IE, or the ServingCellConfig IE. The L1 measurement association list may be configured under the RRCReconfiguration message, the CellGroupConfig IE, or the ServingCellConfig IE.

[0077] In some embodiments, there is a reference configuration for L1 measurements. The RS resource configuration pool, additional / candidate cell information list, reporting configuration set / pool, and / or L1 measurement association list can be considered as components of the reference configuration. A candidate cell can refer to an index from such pool / list to configure its L1 measurement configuration.

[0078] Figure 14 shows an example of network signaling for LTM. In one example, the network / base station explicitly configures / indicates in which cells RS resources can be measured and / or in which cells L1 reports can be sent (e.g., reusing the CSI measurement mechanism). The reference configuration can be generated by the CU (e.g., configured under the RRCReconfiguration message) or the source DU. As shown in Figure 14, the following steps are performed:

[0079] 1. The CU sends the proposed candidate cell list to the candidate DU via F1 signaling, e.g., a UE context setup request message.

[0080] 2. The candidate DU generates a candidate cell configuration and / or L1 RS resources for each candidate cell. The candidate DU transmits the generated candidate cell configuration, L1 RS resource configuration, and / or TCI state configuration to the CU.

[0081] 3. The CU generates a reference configuration (e.g., including a common L1 RS resource pool, a common L1 measurement pool, or an additional / candidate cell information list) based on the configuration from the candidate DU.

[0082] 4a / b. The CU triggers a source configuration update and / or candidate configuration generation / update based on the reference configuration (e.g., via a UE context modification procedure or a UE context setup procedure). For candidate configuration generation / update, the CU sends the reference configuration to the candidate DU via F1 signaling, such as a UE context setup / modification request message. The message may also include other candidate DU / cell information, such as candidate DU ID(s), candidate cell ID(s), RS configuration of the candidate cell(s), TCI state configuration of the candidate cell(s), etc. The candidate DU generates / updates the candidate cell configuration for the candidate cell belonging to that DU based on the reference configuration from the CU. For example, it generates / updates CSI-MeasConfig by referencing an RS index from the pool. The candidate cell configuration may include an L1 measurement configuration and / or a TCI state configuration, which may be configured to reference an RS index from the RS resource configuration pool and / or additional / candidate cell information list, etc. The candidate DU sends the generated / updated candidate cell configuration to the CU via F1 signaling, e.g., a UE Context Setup / Modification Request Acknowledge message, which may also include the L1 measurement RS configuration and / or TCI state configuration of the candidate cell.

[0083] A similar procedure may be applicable to source configuration updates: the CU forwards the reference configuration, the received candidate cell information / configuration (e.g., the candidate cell's L1 measurement RS configuration and / or TCI state configuration) to the source DU. The source DU updates its CellGorupConfig according to the reference configuration and the received candidate cell information / configuration, e.g., to reconfigure CSI-MeasConfig, TCI state. The source DU sends the updated source configuration to the CU.

[0084] 5-6. The CU generates an RRC reconfiguration message including the LTM candidate cell configuration, the reference configuration, and / or the updated source configuration. The CU sends the RRC reconfiguration message to the UE via the source DU.

[0085] 7-8. The UE responds with an RRC reconfiguration complete message to the CU via the source DU.

[0086] 9. The UE measures L1 RS for candidate cells which may be explicitly indicated by the NW, for example in the CSI-MeasConfig of the source cell.

[0087] 10. The UE reports L1 measurements (e.g., CSI reports) to the source cell based on network / base station indication, e.g., in the source cell's CSI-MeasConfig or in dynamic scheduling via DCI.

[0088] 11. The source DU selects one candidate cell as the target for LTM based on the L1 measurement result. The source DU sends a cell switch command to the UE to indicate the target cell for LTM, including, for example, a target candidate cell configuration index.

[0089] 12. The UE performs LTM to access / switch to the target cell.

[0090] In some embodiments, steps 1 and 2 can be skipped, for example, the CU or DU has generated the reference configuration.

[0091] In some embodiments, in step 3, for each candidate DU / cell or source DU / cell, the CU may generate / indicate L1 RS resources to be measured by the UE when the UE accesses the candidate cell, e.g., generate a mapping between the L1 RS resources and other candidate cells, e.g., an additional / candidate cell information list. The CU may then send the additional / candidate cell information list to the candidate DU and source DU (e.g., via steps 4a / b).

[0092] In another embodiment, the network / base station may not explicitly indicate / configure the candidate cells / RSs to be measured for LTM triggering. Figure 15 shows another example of network signaling for LTM. The steps of the embodiment shown in Figure 15 are described below.

[0093] 1-3. Same as step 1-3 in FIG.

[0094] 4-5. The CU generates an RRC reconfiguration message including the LTM candidate cell configuration and / or reference configuration (e.g., common L1 RS resource pool, additional / candidate cell information list, common TCI state list). The CU sends the RRC reconfiguration message to the UE via the source DU.

[0095] 6-7. The UE responds with an RRC reconfiguration complete message to the CU via the source DU.

[0096] 8. The UE measures the L1 RSs indicated by the SSB and / or CSI-RS resource index in the common L1 RS resource pool. The UE may also dynamically measure the L1 RSs indicated by the network / base station, e.g., as indicated via MAC CE or DCI.

[0097] 9. The UE reports the L1 measurements to the source cell, e.g., via MAC CE. The L1 measurement report may be triggered when several events are met, e.g., the L1 measurements of the candidate cell become better than a network / base station configuration threshold, the number of L1 measurements of the candidate cell that are better than the network / base station configuration threshold is greater than the number of network / base station configurations, etc. The L1 measurement report may include the strongest RS index of the indicated RS indices, the associated cell ID, and / or L1-RSRP / RSRQ / SINR.

[0098] 10. The source DU selects one candidate cell as the target for the LTM. The source DU sends a cell switch command to the UE to indicate the target cell for the LTM, including, for example, a target candidate cell configuration index.

[0099] 11. The UE performs LTM to access / switch to the target cell.

[0100] LTM execution L1 / L2 triggered mobility (LTM) may then be performed to transfer from the source cell to the target cell. The execution of LTM may involve a cell switch command. The cell switch command may be conveyed via MAC CE or DCI. The cell switch command may include at least one of the following information: · Candidate cell configuration index, Target cell TCI status indication, · Beam / RS ID of target cell, L2 reset indications, e.g., indications for PDCP recovery, RLC re-establishment, MAC reset, and / or MAC partial reset; RACH related information, e.g., CFRA resources to be used for RACH (e.g., preamble index), an indication of whether RACH is required, an indication of whether pre-configured CFRA resources in the target cell's RRCReconfiguration are available, · TA or TAG information of the target cell; ·BWP ID, SCell enable / disable indication, · C-RNTI, An indication of whether the cell switch is an intra-DU or inter-DU case, or Indication regarding L1 measurements on which candidate cells / beams should be enabled. After cell switching to the target cell, the UE may perform L1 measurements on the indicated candidate cells / beams, e.g. for subsequent LTM execution.

[0101] Upon receiving the cell switch command, the UE applies the configuration for the LTM target candidate cell (i.e., the cell configuration indicated by the candidate cell configuration index in the cell switch command). The UE may perform a RACH-based procedure (e.g., CFRA, CBRA) or a RACH-less / RACH-skip procedure to switch / access the target cell. For example, the UE may perform a random access procedure towards the target cell if TA is not available.

[0102] During cell switching to the target cell, the UE may inform / notify the target cell about the UE arrival. In case of CFRA based LTM, the UE may send a preamble as an indication of the UE arrival. In case of CBRA based LTM, the UE may send a C-RNTI MAC CE in Msg.3 as an indication of the UE arrival. In case of RACH-less / RACH-skip LTM, the options may include:

[0103] Option 1: The UE sends the target cell ID (e.g., via C-RNTI, C-RNTI MAC CE) with pre-allocated UL grants associated with the beam / RS / TCI state indicated by the cell switch command to the target cell. The pre-allocated UL grants (e.g., configured grant type 1) are pre-configured by the network / base station (e.g., provided in the candidate cell configuration), and each pre-allocated UL grant is associated with the beam / RS / TCI state of the candidate cell.

[0104] Option 2: The UE sends an SRS to the target cell. The SRS is associated with the beam / RS / TCI state indicated by the cell switch command. SRS resources are pre-configured by the network / base station (e.g., in SRS-Config in the candidate cell configuration), and each SRS is associated with the beam / RS / TCI state of the candidate cell.

[0105] For RACH-based LTM, the UE considers the LTM to be successfully completed, i.e., the LTM execution to be successfully completed, upon successful completion of the RACH procedure. For RACH-less / RACH-skip LTM, the UE considers the LTM to be successfully completed upon successful transmission of UL messages / signaling (e.g., UCI, MAC CE, RRC reconfiguration complete message) to the target cell, upon reception of the first UL scheduling or first DL transmission from the target cell, or upon reception of a DCI addressed to a new C-RNTI for dynamic scheduling of an UL grant or DL ​​allocation from the target cell.

[0106] In the inter-DU example, the target DU may need to be notified / adjusted with some information, e.g., target cell's TCI status indication, target cell's beam / RS ID, RACH related information, BWP ID, SCell activation / deactivation, C-RNTI, etc. Regarding how to notify the target DU of such information, some options may include: · Option 1: The source DU coordinates with the target DU before sending the cell switch command. · Option 2: The source DU notifies the target DU after sending the cell switch command. Option 3: When the cell switch is completed, the UE notifies the target DU, for example, via an UL message / signaling to the target cell. The UL message / signaling to notify the completion of the LTM can be an RRC message, MAC CE, or UCI. The UL signaling may include or indicate at least one of the following: a target cell ID (e.g., a target candidate cell configuration index, C-RNTI), a TCI status indication of the target cell, a beam / RS ID of the target cell, an activated or deactivated SCell ID, etc.

[0107] Detecting and handling the failure may be problematic. A timer may be introduced for LTM, for example, an LTM timer (t3xx). The timer may be set as an RRC layer timer or a MAC layer timer. The timer may be a t304 timer. The timer value can be configured by the network / base station, for example, via an RRC reconfiguration message. The timer value may include 5 ms, 10 ms, 20 ms, 40 ms, 50 ms, 100 ms, 200 ms, 500 ms, 1000 ms, etc. The timer starts when triggering LTM execution, for example, receiving a cell switch command, or when UE-triggered L1 / L2 mobility is performed (i.e., when applying a stored candidate cell configuration or detecting that the execution condition(s) are met). The timer stops when LTM execution is successfully completed. When the timer expires, the UE considers LTM to have a failure, i.e., detects an LTM failure. Upon detecting an LTM failure, the UE may perform at least one of the following actions: Alternative.1: Trigger RRC re-establishment procedure; Alternative 2: Fall back to the source cell and / or report the LTM failure to the NW, e.g., send an LTM failure report to the network / base station via a MAC CE or RRC message, or Alternative 3: Select another cell from the stored candidate cells to perform a new LTM run, for example, select a candidate cell when conditions for the candidate cell are met, where the conditions may include RSRP / RSRQ / SINR thresholds configured by the network / base station.

[0108] In alternative 2, the network / base station may explicitly configure / indicate whether the UE is allowed to fall back to the source cell upon LTM failure detection and / or report the LTM failure to the NW.

[0109] The LTM failure report may include at least one of the following information: Faulty target candidate cell ID / index, type of disorder, e.g., LTM disorder, Available L1 and / or L3 measurements for the serving cell and / or candidate cells, or Recommended / proposed candidate cells and / or beams / RS that the network / base station can consider as candidates for subsequent LTM runs.

[0110] In Alternative .3, the network / base station may explicitly configure / indicate whether the UE is allowed to perform another LTM execution to other candidate cells after detecting an LTM failure. A timer may be introduced to control the time the UE can attempt a new LTM execution after detecting an LTM failure, for example, an LTM failure timer (t3xx). The timer starts upon triggering an LTM execution or detecting an LTM failure. The timer stops upon successful completion of the LTM execution. When the timer expires, the UE initiates an RRC re-establishment procedure. The timer value may be longer than the LTM timer.

[0111] A counter may be introduced to control the number of new LTM execution attempts the UE can make after detecting an LTM failure. Each time the UE attempts an LTM execution, it increments the counter value by one. When the number of LTM attempts reaches the maximum counter value, the UE shall initiate an RRC re-establishment procedure. The maximum counter value may be configured by the network / base station, for example via an RRC reconfiguration message.

[0112] Some embodiments for LTM failure recovery may include the following. Upon detecting an LTM failure (e.g., t3xx expiry), the UE shall trigger RRC re-establishment. During the RRC re-establishment procedure, if cell selection is triggered by the detection of an MCG failure (e.g., RLF), an LTM failure, or a handover failure, and the selected cell is an LTM candidate cell, the UE may trigger an LTM execution for the selected cell. Otherwise, the UE shall trigger a legacy / normal re-establishment procedure. Upon triggering an LTM execution, the UE starts the LTM timer and / or the LTM failure timer. Upon detecting an LTM failure (e.g., the LTM timer expires) and if the LTM failure timer is running, the UE may select another LTM candidate cell and attempt a new LTM execution. In some examples, the selected candidate cell should meet a threshold set by the NW, e.g., the RSRP threshold. Alternatively, if the LTM failure timer expires, the UE may trigger RRC re-establishment.

[0113] Candidate cell / cell group status The UE may maintain candidate cell / cell group (CG) configurations to support subsequent LTM. Therefore, a cell / CG state needs to be defined for each candidate cell / CG. The network / base station can dynamically select / activate a subset of configured candidate cells to be measured via L1 / L2 signaling, e.g., for subsequent LTM and / or power saving. Thus, the UE can maintain several candidate cell / CG configurations, but the UE does not need to perform L1 measurements on such cells / CGs. Candidate cells may include candidate PCells and / or candidate PSCells. Candidate CGs may include candidate MCGs and / or candidate SCGs.

[0114] Figure 16 shows an example of cell or cell group (CG) state transfer. For each candidate cell / CG, it may have the following states: Pre-configured state: the UE stores / maintains the cell / CG configuration, but the cell / CG configuration is not applied and the UE performs L1 measurements on the cell / CG; Pre-configured but suspended state: the UE stores / maintains the cell / CG configuration, but the cell / CG configuration is not applied and the UE stops / suspends L1 measurements to the cell / CG; Activated state: The UE behavior is the same as with the current activated serving cell / CG, e.g., DL reception / UL transmission with the cell, radio link monitoring and / or beam failure detection of the cell, measurements on the cell, etc., or Deactivated state: The UE behavior is the same as for the current deactivated serving cell / CG, e.g., suspending DL reception / UL transmission with the cell and performing radio link monitoring and / or beam failure detection of the cell if indicated by the network / base station (e.g., bfd-and-RLM are configured as true for a deactivated SCG).

[0115] A candidate cell / CG that is in a preconfigured but suspended state may not consume any UE capabilities related to making L1 measurements. A candidate cell / CG that is in a preconfigured and / or preconfigured but suspended state may not consume any UE capabilities for serving cells (including activated and deactivated serving cells).

[0116] Upon receiving the LTM candidate cell / CG configuration from the network / base station, the UE may consider the stored candidate cell / CG to be in a pre-configured state or a pre-configured but suspended state. Transitioning from a pre-configured state to a pre-configured but suspended state may include: · Upon receiving network / base station signalling indicating that L1 measurements towards a candidate cell / CG are not enabled / allowed / activated, the UE shall consider the candidate cell / CG to be in a pre-configured but suspended state and shall stop / suspend L1 measurements towards the cell / CG.

[0117] Transitioning from a pre-configured but suspended state to a pre-configured state may include: · Upon receiving network / base station signalling indicating that L1 measurements towards a candidate cell / CG are enabled / allowed / activated, the UE shall consider the candidate cell / CG as pre-configured and shall start / resume L1 measurements towards the cell / CG.

[0118] Transitioning from a pre-configured state to an activated state may include: Upon receiving network / base station signaling (e.g. a cell switch command) indicating that a candidate cell / CG is the target of a cell switch or that the candidate cell / CG is activated (e.g. in the case of an SCell or SCG), the UE applies the cell configuration of the target cell and performs a cell switch to the target cell and / or considers the cell to be in activated state.

[0119] Transitioning from a pre-configured state to a deactivated state may include: Upon receiving network / base station signaling (e.g., a cell switch command) indicating that a candidate cell / CG is deactivated (e.g., for an SCell or SCG), the UE applies the cell configuration and / or considers the cell / CG to be in a deactivated state.

[0120] Transitioning from an activated state to a deactivated state / pre-configured state / pre-configured but suspended state may include that an activated source cell may be transitioned to a deactivated state / pre-configured state / pre-configured but suspended state upon receiving network / base station signaling (e.g., a cell switch command).

[0121] Transitioning from a deactivated state to an activated state / pre-configured state / pre-configured but suspended state may include that a deactivated source cell may be transitioned to an activated state / pre-configured state / pre-configured but suspended state upon receiving network / base station signaling (e.g., a cell switch command). State transfer between activation and deactivation may be applicable to at least the SCell and the SCG.

[0122] LTM in NR-DC LTM may be supported in NR-DC scenarios (e.g., in the case of an SN). The following example may be considered: Example 1: The LTM consists of only the MN, for example, for intra-MN PCell change with / without SCell change. Example 2: The LTM is configured only in the SN, e.g., for an intra-SN PSCell change with / without SCell change; or · Example 3: LTM is configured independently in both MN and SN.

[0123] In some examples, LTM in one node may not affect other nodes, e.g., intra-frequency LTM, and LTM in one node may be transparent to other nodes. Specifically, inter-node coordination may not be required before sending a cell switch command to trigger LTM. The MN / MCG and SN / SCG may maintain a pool / list of candidate cells in each node (e.g., candidate cells in the pool are configured for intra-frequency LTM). That is, ·If LTM is triggered due to a candidate cell change in the pool of an MCG, the MCG does not need to inform the SCG, i.e. it is transparent to other CGs and vice versa. · If L1 / L2 mobility is triggered for a candidate cell change outside the MCG's pool, the MCG must coordinate with the SCG before sending the cell switch command to the UE, and vice versa.

[0124] In an example where LTM in one node affects the other node, e.g., inter-frequency LTM, the MN and SN may also coordinate when preparing the candidate cell configuration. For a candidate cell in the MN, the SCG configuration may also be included in the candidate cell configuration, e.g., including the MRDC-SecondaryCellGroupConfig IE. Triggering LTM execution may trigger a PCell change with a PSCell change. For a candidate cell in the MN, a list of allowed candidate PSCells may be pre-configured. When triggering LTM in the MN, the MN may select one candidate PSCell from the allowed candidate PSCell list to perform LTM for the PCell change with a PSCell change. In this example, the UE may also need to report L1 measurements of the candidate PSCells to the MN.

[0125] The systems and processes described above may be encoded in a computer-readable medium, such as a signal-bearing medium or memory, programmed into a device, such as one or more integrated circuits, one or more processors, or processed by a controller or computer. The data may be analyzed in a computer system and used to generate a spectrum. If the method is performed by software, the software may reside in a non-volatile or volatile memory in communication with or interfaced to a storage device, synchronizer, communication interface, or transmitter. The circuit or electronic device is designed to transmit the data to another location. The memory may contain an ordered list of executable instructions for implementing logical functions. The described logical functions or any system elements may be implemented via optical circuitry, digital circuitry, source code, analog circuitry, analog sources such as analog electrical signals, audio signals, video signals, or any combination thereof. The software may be embodied in any computer-readable or signal-bearing medium for use by or in connection with an instruction-executable system, apparatus, or device. Such a system may include a computer-based system, a system including a processor, or another system that may selectively fetch instructions from an instruction-executable system, apparatus, or device that may also execute instructions.

[0126] "Computer-readable medium," "machine-readable medium," "propagating signal" medium, and / or "signal-bearing medium" may include any device that stores, communicates, propagates, or transports software for use by or in connection with an instruction-executable system, apparatus, or device. The machine-readable medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. A non-exhaustive list of examples of machine-readable media includes an electrical connection having one or more wires ("electronic"), a portable magnetic or optical disk, a volatile memory such as random access memory ("RAM"), read-only memory ("ROM"), erasable programmable read-only memory ("EPROM" or flash memory), or optical fiber. Machine-readable media may also include tangible media on which software is printed, so that the software can be stored electronically as an image or in another format (e.g., via optical scanning) and then compiled and / or interpreted, or otherwise processed. The processed medium may then be stored in computer and / or machine memory.

[0127] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of various embodiments. These illustrations are not intended to serve as a complete description of all elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments will be apparent to those skilled in the art upon reviewing the present disclosure. Other embodiments may be utilized and derived from the present disclosure, whereby structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Furthermore, the illustrations are merely representational and may not be drawn to scale. Certain parts within the illustrations may be exaggerated, while other parts may be minimized. Therefore, the present disclosure and the figures should be considered illustrative and not limiting.

[0128] One or more embodiments of the present disclosure may be referred to herein, individually and / or collectively, by the term "invention," merely for convenience and without any intention to intentionally limit the scope of the present application to any particular invention or inventive concept. Furthermore, while specific embodiments have been illustrated and described herein, it should be understood that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any and all subsequent adaptations or modifications of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art upon reviewing the description.

[0129] The phrase "coupled with" is defined to mean directly connected or indirectly connected through one or more intermediate components. Such intermediate components may include both hardware-based and software-based components. Changes in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional, different, or fewer components may be provided.

[0130] The subject matter disclosed above should be considered illustrative rather than limiting, and the appended claims are intended to cover all such modifications, extensions, and other embodiments that fall within the true spirit and scope of the present invention. Accordingly, to the maximum extent permitted by law, the scope of the present invention should be determined by the broadest permissible interpretation of the following claims and their equivalents, and should not be limited or constrained by the foregoing detailed description. While various embodiments of the present invention have been described, it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the present invention. Accordingly, the present invention should not be limited in light of the appended claims and their equivalents.

Claims

1. 1. A method for wireless communication, comprising: receiving a configuration message including configuration for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells; storing the configuration for the LTM candidate cell; transmitting a measurement report with L1 measurements for at least one of the LTM candidate cells; receiving a cell switch command from the LTM candidate cell to indicate a target LTM candidate cell; performing an LTM cell switch to the target LTM candidate cell; A method comprising:

2. 2. The method of claim 1, wherein the configurations for LTM candidate cells include at least one of a list of candidate cell configurations, a list of candidate cell group level configurations (CellGroupConfig), a list of candidate radio bearer configurations (RadioBearerConfig), or a list of candidate measurement configurations (MeasConfig).

3. The method of claim 1 , wherein the configuration for each candidate includes at least one of a candidate cell configuration index, a cell group level configuration, or a reference index.

4. 4. The method of claim 3, wherein the reference index refers to an indicated cell group level configuration from the candidate cell group level configuration list, an indicated radio bearer configuration from the candidate radio bearer configuration list, an indicated measurement configuration from the candidate measurement configuration list, or an indicated candidate cell configuration from the candidate cell list.

5. 2. The method of claim 1, wherein the configurations for LTM candidate cells include groups of configurations for each of the candidate cells, each of the candidate cells within a group sharing a common or reference configuration, and each of the candidate cells within a group having a delta configuration.

6. The method of claim 5 , wherein the common or reference configuration is referenced by a reference index to reference the reference configuration from a reference configuration pool.

7. 7. The method of claim 6, wherein the reference configuration pool includes at least one of a list of reference cell configurations, a list of reference cell group level configurations (CellGroupConfig), a list of reference radio bearer configurations (RadioBearerConfig), or a list of reference measurement configurations (MeasConfig).

8. The method of claim 1 , wherein the configuration for an LTM candidate cell includes a common L1 measurement configuration pool.

9. 9. The method of claim 8, wherein the common L1 measurement configuration pool includes at least one of a list of L1 reference signaling (RS) resources for a serving cell and an LTM candidate cell, a list of beam information for a serving cell and an LTM candidate cell, or a list of transmission configuration indication (TCI) status information for a serving cell and an LTM candidate cell.

10. The method of claim 8 , wherein the configuration for LTM candidate cells includes an information list indicating which of the L1 measurement configurations are associated with which of the candidate cells.

11. The method of claim 10 , wherein the information items in the information list are configured to link RS resources with a candidate cell, link beam information with a candidate cell, or link TCI status information with a candidate cell.

12. 11. The method of claim 10, wherein the RS resources, beam information, or TCI state is configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission.

13. The method of claim 10 , wherein the information list is combined with or configured in a candidate cell configuration list.

14. 10. The method of claim 1, wherein the measurement report includes at least one of a cell identification, an RS identification, a measurement identification, a measurement result, an indication for uplink (UL) synchronization completion, or an indication for timing advance availability.

15. performing downlink (DL) synchronization or uplink synchronization with a candidate cell before receiving the cell switch command; The method of claim 1 further comprising:

16. sending UL signaling to the target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or the completion of the LTM cell switch; The method of claim 1 further comprising:

17. 17. The method of claim 16, wherein the UL signaling includes or indicates at least one of the target LTM candidate cell identity, a TCI status indication of the target LTM candidate cell, a beam / RS identity of the target LTM candidate cell, or an activated / deactivated SCell identity.

18. starting a first timer upon receiving the cell switch command; further comprising The method of claim 1 , wherein the first timer is stopped upon successful execution of the LTM cell switch.

19. determining an impediment to the execution of the LTM cell switching based on expiration of the first timer; 20. The method of claim 18, further comprising:

20. starting a second timer upon receiving the cell switch command or upon detecting the failure to the execution of the LTM cell switch. further comprising 20. The method of claim 18, wherein the second timer is stopped upon successful execution of the LTM cell switch.

21. detecting the failure to perform the LTM cell switch and performing the LTM cell switch to another LTM candidate cell if the second timer is running; 21. The method of claim 20, further comprising:

22. triggering an RRC re-establishment procedure when the second timer expires.

22. The method of claim 21 further comprising:

23. 2. The method of claim 1, wherein the state of the LTM candidate cell comprises at least one of a preconfigured state, a preconfigured but suspended state, an activated state, or a deactivated state.

24. 24. The method of claim 23, wherein in the preconfigured state, the UE stores the cell configuration but does not apply the cell configuration, and the UE performs L1 measurements on the cell, and further wherein in the preconfigured but suspended state, the UE stores the cell configuration, does not apply the cell configuration, and the UE suspends performing L1 measurements on the cell.

25. 1. A method for wireless communication, comprising: transmitting a configuration message including configuration for one or more Layer 1 ("L1") or Layer 2 ("L2") triggered mobility ("LTM") candidate cells; receiving a measurement report with L1 measurements for at least one of the LTM candidate cells; transmitting a cell switch command indicating a target LTM candidate cell from the LTM candidate cell and for triggering execution of an LTM cell switch to the target LTM candidate cell; A method comprising:

26. 26. The method of claim 25, wherein the configurations for LTM candidate cells include at least one of a list of candidate cell configurations, a list of candidate cell group level configurations (CellGroupConfig), a list of candidate radio bearer configurations (RadioBearerConfig), or a list of candidate measurement configurations (MeasConfig).

27. 26. The method of claim 25, wherein the configuration for each candidate includes at least one of a candidate cell configuration index, a cell group level configuration, or a reference index.

28. 28. The method of claim 27, wherein the reference index refers to an indicated cell group level configuration from the candidate cell group level configuration list, an indicated radio bearer configuration from the candidate radio bearer configuration list, an indicated measurement configuration from the candidate measurement configuration list, or an indicated candidate cell configuration from the candidate cell list.

29. 26. The method of claim 25, wherein the configurations for LTM candidate cells include groups of configurations for each of the candidate cells, each of the candidate cells within a group sharing a common or reference configuration, and each of the candidate cells within a group having a delta configuration.

30. 30. The method of claim 29, wherein the common or reference configuration is referenced by a reference index to reference the reference configuration from a reference configuration pool.

31. 26. The method of claim 25, wherein the configuration for an LTM candidate cell includes a common L1 measurement configuration pool.

32. 32. The method of claim 31 , wherein the common L1 measurement configuration pool includes at least one of a list of L1 reference signaling (RS) resources for a serving cell and an LTM candidate cell, a list of beam information for a serving cell and an LTM candidate cell, or a list of transmission configuration indication (TCI) status information for a serving cell and an LTM candidate cell.

33. 33. The method of claim 32, wherein the configuration for LTM candidate cells includes an information list indicating which of the L1 measurement configurations are associated with which of the candidate cells.

34. 34. The method of claim 33, wherein the information items in the information list are configured to link RS resources with a candidate cell, link beam information with a candidate cell, or link TCI status information with a candidate cell.

35. 35. The method of claim 34, wherein the RS resources, beam information, or TCI state is configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission.

36. 34. The method of claim 33, wherein the information list is combined with or configured within a candidate cell configuration list.

37. 26. The method of claim 25, wherein the measurement report includes at least one of a cell identification, an RS identification, a measurement identification, a measurement result, an indication for uplink (UL) synchronization completion, or an indication for timing advance availability.

38. receiving UL signaling to the target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or the completion of the cell switch; further comprising 26. The method of claim 25, wherein the UL signaling includes or indicates at least one of the target LTM candidate cell identification, a TCI status indication of the target LTM candidate cell, or a beam / RS identification of the target LTM candidate cell, or an activated / deactivated SCell identification.

39. 39. A wireless communications device comprising a processor and a memory, the processor configured to read code from the memory and to perform the method of any one of claims 1 to 38.

40. 39. A computer program product having stored thereon a computer readable program medium code that, when executed by a processor, causes the processor to perform the method of any one of claims 1 to 38.

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