Layer 1 or layer 2 triggered mobility

Abstract

In wireless communications, devices may change, add, or handoff between accessed network cells to enable inter-cell mobility. Such mobility may include Layer 1 and / or Layer 2 (L1 / L2) signaling for a user equipment (UE) to move between cells in a network. There may be a configuration message that includes a configuration of one or more Layer 1 ("L1") or Layer 2 ("L2") triggered Mobility ("LTM") candidate cells. A measurement report for L1 measurements of the LTM candidate cell is used for a cell handover command to indicate the target LTM candidate cell, triggering execution of LTM cell handover to the target LTM candidate cell. The LTM cell handover is a handover from a source cell to a target LTM candidate cell.

Description

Technical Field

[0001] The present invention relates generally to wireless communications and, more particularly, to improved signaling for inter-cell mobility in mobile device communication systems. Background Art

[0002] Wireless communication technologies are driving the world towards an increasingly interconnected and networked society. Wireless communications rely on efficient network resource management and allocation between user mobile stations and radio access network nodes (including but not limited to radio base stations). Next-generation networks are expected to provide high-speed, low-latency, and ultra-reliable communication capabilities, meeting the requirements of diverse industries and users. User mobile stations, or user equipment (UE), are becoming increasingly complex, and the amount of data communicated is continuously increasing. To improve communications, meet the reliability requirements of vertical industries, and support next-generation network services, communication improvements are necessary. Summary of the Invention

[0003] The present invention relates to methods, systems and devices for layer 1 and / or layer 2 (L1 / L2) signaling for mobile equipment (UE) to move between cells in a network. The signaling can be used to reduce mobility interruption time and / or improve the robustness of handover. Mobility can be triggered by the network or the UE. There can be a configuration message that includes the configuration for one or more layer 1 ("L1") or layer 2 ("L2") triggered mobility ("LTM") candidate cells. A measurement report with L1 measurements for the LTM candidate cell is used in a cell handover command to instruct the target LTM candidate cell to trigger the execution of an LTM cell handover to the target LTM candidate cell. The LTM cell handover is 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 a configuration for one or more layer 1 ("L1") or layer 2 ("L2") triggered mobility ("LTM") candidate cells; storing the configuration for the LTM candidate cells; sending a measurement report with L1 measurements for at least one of the LTM candidate cells; receiving a cell handover command to indicate a target LTM candidate cell from the LTM candidate cells; and performing an LTM cell handover to the target LTM candidate cell. The configuration for the LTM candidate cells includes 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 is used to reference a cell group level configuration indicated from the candidate cell group level configuration list, a radio bearer configuration indicated from the candidate radio bearer configuration list, a measurement configuration indicated from the candidate measurement configuration list, or a candidate cell configuration indicated from the candidate cell list. The configuration for the LTM candidate cell includes a configuration group for each candidate cell, wherein each candidate cell in a group shares a common configuration or a reference configuration, and each candidate cell in a group has an incremental configuration. The common configuration or reference configuration is referenced using a reference index to refer to the reference configuration from a reference configuration pool. The reference configuration pool includes at least one of the following: a list of reference cell configurations, a reference cell group level configuration (CellGroupConfig) list, a reference radio bearer configuration (RadioBearerConfig) list, or a reference measurement configuration (MeasConfig) list. 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 the following: 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 that indicates which of the L1 measurement configurations are associated with which of the candidate cells. The information items in the information list are configured to associate RS resources with the candidate cell, associate beam information with the candidate cell, or associate 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 transmissions. 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 the following: a cell identifier, an RS identifier, a measurement identifier, a measurement result, an indication of uplink (UL) synchronization completion, or an indication of timing advance availability. The method includes: before receiving the cell switching command, performing downlink (DL) synchronization or uplink synchronization with the candidate cell. The method includes: sending UL signaling to the target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or completion of LTM cell switching. The UL signaling includes or indicates at least one of the following: the target LTM candidate cell identifier, the TCI status indication of the target LTM candidate cell, the beam / RS identifier of the target LTM candidate cell, or the activated / deactivated SCell identifier. The method includes: when receiving the cell switching command, starting a first timer; wherein the first timer is stopped when the LTM cell switching is successfully performed. The method includes: based on the expiration of the first timer, determining that the execution of the LTM cell switching has failed. The method includes: starting a second timer when the cell handover command is received or when a failure in executing the LTM cell handover is detected; wherein the second timer is stopped when the LTM cell handover is successfully executed. The method includes: if a failure in executing the LTM cell handover is detected and the second timer is running, implementing an LTM cell handover to another LTM candidate cell. The method includes: if the second timer expires, triggering an RRC re-establishment process. The state of the LTM candidate cell includes at least one of the following: a pre-configured state, a pre-configured but suspended state, an activated state, or a deactivated state. For the pre-configured state, the UE stores the cell configuration but does not apply the cell configuration, and the UE performs L1 measurements on the cell. Further, for the pre-configured 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.

[0005] In another embodiment, a method for wireless communication includes: sending a configuration message including a configuration for one or more layer 1 ("L1") or layer 2 ("L2") triggered mobility ("LTM") candidate cells; receiving a measurement report having L1 measurements for at least one of the LTM candidate cells; and sending a cell handover command to indicate a target LTM candidate cell from the LTM candidate cells and trigger an LTM cell handover to the target LTM candidate cell. The configuration for the LTM candidate cells includes at least one of: a candidate cell configuration list, a candidate cell group level configuration (CellGroupConfig) list, a candidate radio bearer configuration (RadioBearerConfig) list, or a candidate measurement configuration (MeasConfig) list. 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 is used to reference a cell group level configuration indicated from the candidate cell group level configuration list, a radio bearer configuration indicated from the candidate radio bearer configuration list, a measurement configuration indicated from the candidate measurement configuration list, or a candidate cell configuration indicated from the candidate cell list. The configuration for the LTM candidate cell includes a configuration group for each candidate cell, wherein each candidate cell in a group shares a common configuration or a reference configuration, and each candidate cell in a group has an incremental configuration. The common configuration or reference configuration is referenced using a reference index to refer to the 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 the following: an L1 reference signaling (RS) resource list for the serving cell and the LTM candidate cell, a beam information list for the serving cell and the LTM candidate cell, or a transmission configuration indication (TCI) state information list 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 are associated with which of the candidate cells. The information items in the information list are configured to associate RS resources with a candidate cell, associate beam information with a candidate cell, or associate TCI status information with a 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 transmissions. The information list is combined with a candidate cell configuration list or configured within the candidate cell configuration. The measurement report includes at least one of the following: a cell identifier, an RS identifier, a measurement identifier, a measurement result, an indication of uplink (UL) synchronization completion, or an indication of timing advance availability.The method includes: receiving UL signaling from the target LTM candidate cell to notify the UE of arrival at the target LTM candidate cell or to notify completion of cell switching, wherein the UL signaling includes or indicates at least one of the following: the target LTM candidate cell identifier, the TCI status indication of the target LTM candidate cell, or the beam / RS identifier of the target LTM candidate cell, or the activated / deactivated SCell identifier.

[0006] In one embodiment, a wireless communication device includes a processor and a memory, and the processor is configured to read code from the memory and implement any of the embodiments discussed above.

[0007] In one embodiment, a computer program product includes computer readable program medium code stored thereon, which, when executed by a processor, causes the processor to implement any of the embodiments discussed above.

[0008] In some embodiments, there is a wireless communication device comprising a processor and a memory, wherein the processor is configured to read code from the memory and implement any of the methods described in any of the embodiments. In some embodiments, a computer program product comprises a computer-readable program medium with code stored thereon, which, when executed by a processor, causes the processor to implement any of the methods described in any of the embodiments. The above and other aspects and their implementations are described in more detail in the drawings, the description, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 An example base station is shown.

[0010] Figure 2 An example random access (RA) messaging environment is shown.

[0011] Figure 3 The network architecture of the base station centralized unit (Central Unit, CU) and the base station distributed unit (Distributed Unit, DU) is shown.

[0012] Figure 4 An embodiment of intra-user equipment (UE) DU mobility is shown.

[0013] Figure 5 An embodiment of user equipment (UE) intra-CU and inter-DU mobility is shown.

[0014] Figure 6 An embodiment of user equipment (UE) inter-CU mobility is shown.

[0015] Figure 7 An embodiment of a signaling procedure for L1 / L2 triggered mobility (LTM) is shown.

[0016] Figure 8 An embodiment of the candidate cell group list structure is shown.

[0017] Figure 9 An embodiment of a candidate cell signaling structure is shown.

[0018] Figure 10 One embodiment of a signaling structure for L1 measurement configuration is shown.

[0019] Figure 11a A first embodiment of a configuration signaling structure is shown.

[0020] Figure 11b Shown from Figure 11a Example cell group configuration.

[0021] Figure 11c Shown from Figure 11a Example cell information list.

[0022] Figure 11d Shown from Figure 11a An example resource configuration pool.

[0023] Figure 11e Shown from Figure 11a Example candidate cell configuration list.

[0024] Figure 12 A second embodiment of the configuration signaling structure is shown.

[0025] Figure 13 A third embodiment of a configuration signaling structure is shown.

[0026] Figure 14 An example of network signaling for LTM is shown.

[0027] Figure 15 Another example of network signaling for LTM is shown.

[0028] Figure 16 An example of cell or cell group (CG) state transition is shown. DETAILED DESCRIPTION

[0029] The present disclosure will now be described in detail below with reference to the accompanying drawings, which form a part hereof and show by way of illustration specific examples of embodiments. However, it should be noted that the present disclosure may be embodied in many different forms, and therefore, the subject matter encompassed or claimed is not intended to be limited to any of the embodiments set forth below.

[0030] Throughout the specification and claims, terms may have nuanced meanings suggested or implied by the context, beyond their explicitly stated meanings. Likewise, the phrases "in one embodiment" or "in some embodiments" as used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" as used herein do not necessarily refer to different embodiments. The phrases "in one embodiment" or "in some embodiments" as used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" as used herein do not necessarily refer to different embodiments. For example, it is intended that the claimed subject matter include, in whole or in part, exemplary embodiments or combinations of embodiments.

[0031] In general, terms can be understood at least in part from their usage in the context. For example, terms such as "and", "or" or "and / or" as used herein can include multiple meanings, which can depend at least in part on the context in which such terms are used. Typically, if "or" is used to relate to a list, such as A, B or C, it is intended to mean A, B and C, which are used here in an inclusive sense, and A, B or C, which are used here in an exclusive sense. In addition, depending at least in part on the context, the terms "one or more" or "at least one" as used herein can be used to describe any feature, structure or characteristic in a singular sense, or can be used to describe a combination of features, structures or characteristics in a plural sense. Similarly, terms such as "one", "an" or "the" can also be understood to express singular usage or plural usage, depending at least in part on the context. In addition, the term "based on" can be understood to not necessarily be intended to express an exclusive set of factors, but can again allow for the presence of additional factors that are not necessarily explicitly described, depending at least in part on the context.

[0032] Radio resource control ("radio resource control, RRC") is a protocol layer between the UE and the base station at the IP level (network layer). There may be various radio resource control (RRC) states, such as RRC connected (RRC_CONNECTED) state, RRC inactive (RRC_INACTIVE) state, and RRC idle (RRC_IDLE) state. RRC messages are transmitted via the Packet Data Convergence Protocol ("Packet Data Convergence Protocol, PDCP"). As described, the UE may transmit data via a random access channel ("RACH") protocol scheme or a configured grant ("Configured Grant, CG") scheme. CG may be used to reduce the waste of periodically allocated resources by enabling multiple devices to share periodic resources. A base station or node may allocate CG resources to eliminate packet transmission delays and increase the utilization of allocated periodic radio resources. The CG scheme is only one example of a protocol scheme for communication, and other examples (including but not limited to RACH) are possible. The wireless communication described herein may be performed via wireless access.

[0033] As shown below relative to Figures 1 to 6 As described, a network provider may include multiple network nodes (ie, base stations) for providing network access to network equipment ("UE") equipment. In some embodiments, the network nodes are referred to as base stations. Figures 4 to 6 Cell mobility is shown in which a UE device moves between cells. Control signaling may be used to facilitate such mobility. Control signaling supports transmission of downlink transport channels and uplink transport channels and may be referred to as layer 1 and / or layer 2 ("L1 / L2") signaling, indicating that the corresponding information originates partly from the physical layer (layer 1) and partly from the medium access control (MAC) (layer 2). In particular, layer 1 may include the PHYSICAL layer, and layer 2 may include the MAC, RLC, and PDCP. L1 / L2 mobility based on L1 / L2 signaling may have lower latency, lower overhead, and reduced interruption time.

[0034] There may be a master node ("MN") and one or more secondary nodes ("SN"). The MN may include a master cell group ("MCG"), and the SN may each include a secondary cell group ("SCG"). The MCG is a group of cells provided by the master node ("MN"), and the SCG is a group of cells provided by the secondary node ("SN"). The MCG may include a primary cell ("PCell") and one or more secondary cells ("SCell"). The SCG may include a primary secondary cell ("PSCell") and one or more secondary cells ("SCell"). Each primary cell may be connected to multiple secondary cells. The primary cells (PCell, PSCell) are the primary cells of their respective cell groups (MCG, SCG, respectively) and may initiate initial access. The primary cell may be used for signaling and may be referred to as a special cell ("spCell"), where spCell=PCell+PSCell. The inter-cell mobility described in these embodiments may be based on PCell, PSCell and / or SCell.

[0035] A user equipment ("UE") device may move between nodes or cells, in which case handover or change / addition operations may occur to improve the network reliability of the UE as it moves. Movement may be from a source cell to a target cell based on multiple potential target cells, which are referred to as candidates. Movement between cells may also include multiple target cells, which are candidate target cells. Conditional handover ("conditional handover, CHO") and conditional PSCell addition / change ("conditional PSCell addition / change, CPAC") are described below. CPAC may include conditional PSCell change ("CPC") and / or conditional PSCell addition ("CPA").

[0036] Conditional Handover (CHO) can reduce handover interruption time and improve mobility reliability. CHO is a handover performed by the UE when one or more execution conditions are met. The UE can evaluate the execution conditions upon receiving the CHO configuration and stop evaluating the execution conditions once the handover is triggered. The CHO configuration can include a candidate PCell configuration generated by a candidate target node and the corresponding execution conditions for the candidate cell.

[0037] Conditional PSCell Addition / Change ("CPAC") may include a UE having a network configuration for initiating 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 conditions. A UE in a wireless network may operate in dual connectivity ("dual connectivity, DC"), including intra-E-UTRA DC or multi-radio DC ("MR-DC"). In the example of intra-E-UTRA DC, both the MN and the SN provide E-UTRA access. In the example of MR-DC, one node may provide new radio ("NR") access and the other node may provide E-UTRA access or NR access.

[0038] To reduce mobility disruption, a handover procedure based on the Dual Active Protocol Stack (DAPS) can be used. In a DAPS-based handover procedure, the UE maintains simultaneous connections to both the source and target cells until the source cell is released after a successful random access to the target cell.

[0039] Figure 1 An example base station 102 is shown. The base station may also be referred to as a radio network node and may be Figure 3 A to Figure 7 1. The base station 102 is a network node (e.g., a master node ("MN"), a secondary node ("SN"), and a source / destination node) shown in FIG. In the context of mobile telecommunications, the base station 102 may also be referred to as a Node B (NB, such as an eNB or gNB). An example base station may include radio Tx / Rx circuitry 113 to receive and transmit with a user equipment (UE) 104. The base station may also include network interface circuitry 116 to couple the base station to the core network 110, such as fiber or wired interconnects, Ethernet, and / or other data transmission media / protocols.

[0040] The base station may also include system circuitry 122. System circuitry 122 may include a processor 124 and / or memory 126. Memory 126 may include operations 128 and control parameters 130. Operations 128 may include instructions for execution on one or more of processors 124 to support functionality of the base station. For example, the operations may process random access transmission requests from multiple UEs. Control parameters 130 may include parameters that support the execution of operations 128. For example, the control parameters may include network protocol settings, random access message delivery format rules, bandwidth parameters, radio frequency mapping assignments, and / or other parameters.

[0041] Figure 2An example random access messaging environment 200 is shown. In this random access messaging environment, a UE 104 can communicate with a base station 102 via a random access channel 252. In this example, the UE 104 supports one or more Subscriber Identity Modules (SIMs), such as SIM1 202. An electrical and physical interface 206 connects SIM1 202 to the rest of the user equipment hardware, for example, via a system bus 210.

[0042] Mobile device 200 includes a communication interface 212, system logic 214, and a user interface 218. System logic 214 may include any combination of hardware, software, firmware, or other logic. System logic 214 may be implemented, for example, using one or more system-on-chips (SoCs), application-specific integrated circuits (ASICs), discrete analog and digital circuits, and other circuitry. System logic 214 is part of the implementation of any desired functionality within UE 104. In this regard, system logic 214 may include logic that facilitates, for example, decoding and playing music and videos, such as MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback; running applications; accepting user input; storing and retrieving application data; establishing, maintaining, and terminating cellular phone calls or data connections for, for example, internet connections; establishing, maintaining, and terminating wireless network connections, Bluetooth connections, or other connections; and displaying relevant information on user interface 218. User interface 218 and input 228 may include a graphical user interface, a touch-sensitive display, tactile feedback or other tactile output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements. Additional examples of input 228 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headphone and microphone input / output jacks, Universal Serial Bus (USB) connectors, memory card slots, radiation sensors (e.g., IR sensors), and other types of inputs.

[0043] The system logic 214 may include one or more processors 216 and memory 220. The memory 220 stores, for example, control instructions 222 that the processor 216 executes to perform the desired functions of the UE 104. Control parameters 224 provide and specify configuration and operating options for the control instructions 222. The memory 220 may also store any BT, WiFi, 3G, 4G, 5G, or other data 226 that the UE 104 will send or has received via the communication interface 212. In various embodiments, system power may be provided by a power storage device, such as a battery 282.

[0044] In the communication interface 212, radio frequency (RF) transmit (Tx) and receive (Rx) circuitry 230 handles the transmission and reception of signals through one or more antennas 232. The communication interface 212 may include one or more transceivers. The transceiver may be a wireless transceiver that includes modulation / demodulation circuitry, a digital-to-analog converter (DAC), a shaping table, an analog-to-digital converter (ADC), filters, a waveform shaper, filters, preamplifiers, power amplifiers, and / or other logic for transmitting and receiving through one or more antennas or (for some devices) through a physical (e.g., wired) medium.

[0045] The signals transmitted and received may conform to any of a variety of formats, protocols, modulation schemes (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and coding. As a specific example, the communication interface 212 may include a transceiver that supports transmission and reception under 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 from the Third Generation Partnership Project (3GPP), the GSM Association, 3GPP2, the IEEE, or other partners or standards bodies.

[0046] In certain geographic areas, multiple RAN nodes (e.g., eNB, gNB) of the same or different radio access technologies ("RAT") may be deployed in the same or different frequency carriers, and they may interoperate with each other via dual connectivity operations to provide joint communication services for the same target UE. The Multi-RAT Dual Connectivity ("MR-DC") architecture may have a non-co-located master node ("MN") and a secondary node ("SN"). The Access Mobility Function ("AMF") and the Session Management Function ("SMF") may be control plane entities, and the User Plane Function ("UPF") is a user plane entity in the 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 the SN may be an Xn Control Plane ("Xn-C") interface. The signaling connection between the MN and the UE is a Uu Control Plane ("Uu-C") RRC interface. All of these connections manage the configuration and operation of MR-DC. The user plane connection between the user plane function ("UPF") and the MN may be an instance of the NG-U(MN) interface.

[0047] Figure 3 The network architecture of the base station centralized unit (CU) and the base station distributed unit (DU) is shown. Figure 3 A base station (labeled "gNB") is shown communicating with the overall network (labeled "5GC"). The base stations can communicate with each other via a control plane interface ("Xn-C"). A base station is shown with one CU connected to two DUs via an F1 interface. This is just one example of a base station arrangement. In some embodiments, there can be one or any number of DUs connected to a single CU.

[0048] A base station can be divided into two physical entities, namely a centralized unit ("CU") and a distributed unit ("DU"). Generally, the CU provides support for the upper layers of the protocol stack (such as SDAP, PDCP, and RRC), while the DU provides support for the lower layers of the protocol stack (such as RLC, MAC, and physical layers). In addition to the functions specifically assigned to the DU, the CU may include operations for user data transmission, mobility control, radio access network sharing, session management, etc. The DU is a logical node with a subset of base station functionality and can be controlled by the CU.

[0049] The CU can be a logical node for the RRC, SDAP, and PDCP protocols of a hosting base station or the RRC and PDCP protocols of a base station, which controls the operation of one or more DUs. The DU can be a logical node for the RLC, MAC, and physical layers of a hosting base station, and its operation can be at least partially controlled by the CU. A single DU can support one or more cells. However, each cell is supported by only a single DU. Each base station can support multiple cells. As described in the embodiments herein, mobility between cells can come from different CUs or DUs, or can be within a CU and / or DU.

[0050] L1 / L2 mobility

[0051] The L1 / L2-based inter-cell mobility described herein may occur in a number of different examples. For L1 / L2 mobility, there may be intra-DU mobility where the UE changes cells within a single DU. Examples of intra-DU mobility include: 1) PCell change within a DU (which may also include a PCell change with an SCell change); 2) PSCell change within a DU (which may also include a PSCell change with an SCell change); and 3) PCell change within a DU and PSCell change within a DU (which may also include an SCell change within a cell group). In another L1 / L2 mobility embodiment, there may be intra-CU and inter-DU mobility where the UE changes cells between different DUs but within a single CU. Examples of intra-CU and inter-DU mobility include: 1) PCell change across DUs but within a CU (which may also include a PCell change with an SCell change); and 2) PSCell change across DUs but within a CU (which may also include a PSCell change with an SCell change). In another L1 / L2 mobility embodiment, there may be inter-CU mobility where the UE changes cells between different CUs. Examples of inter-CU mobility include: 1) PCell change across CUs (which may also include PCell change with SCell change); and 2) PSCell change across CUs (which may also include PSCell change with SCell change). In another embodiment, there may be SCell change / addition, and this example may include SCell addition / change within a cell group. Figures 4 to 6 An embodiment of UE mobility between cells is shown.

[0052] Figure 4 An embodiment of intra-DU mobility of a user equipment (UE) is shown. A base station may include a CU and at least one DU. In this embodiment, there is a single DU shown with multiple cells. Both cell 1 and cell 2 are from a single DU. In this example, UE 402 can move from cell 1 to cell 2 and Figure 4 , the UE trajectory is depicted from cell 1 to cell 2. Inter-cell mobility may occur when the UE 402 is located between two cells and is moving to a third location within cell 2. This is intra-DU mobility because the UE is moving cells within a single DU.

[0053] Figure 5An embodiment of intra-CU and inter-DU mobility of a user equipment (UE) is shown. In this embodiment, a base station may include a CU and two DUs (DU_1 and DU_2). Although each DU may have multiple cells, in this example, each DU is shown to provide a single cell, such that DU_1 provides cell 1 and DU_2 provides cell 2. In this example, UE 502 may move from cell 1 to cell 2 and Figure 5 The UE trajectory from cell 1 to cell 2 is depicted in Figure 1, which also results in a transition from DU_1 to DU_2. Inter-cell mobility can occur when UE 502 is located between two cells and is moving to a third location within cell 2. This is intra-CU mobility, as the UE is moving cells within a single CU. However, this is also inter-DU mobility, as the UE is moving between different DUs.

[0054] Figure 6 An embodiment of user equipment (UE) inter-CU mobility is shown. In this embodiment, the base station may include multiple CUs (CU_1 and CU_2). Each CU may include multiple DUs, but in this example, each CU is shown as having one corresponding DU (CU_1 has DU_1, and CU_2 has DU_2). Multiple cells are shown for each DU. In this example, the UE trajectory of UE 602 goes from cell 2 through cell 3, to inter-CU position 604 (located between CU_1 and CU_2), and then to cell 5 and cell 6. As the UE moves, as shown in the figure, mobility can change cells and can transition between multiple cells. Since UE 602 (at inter-CU position 604) switches cells from CU_1 to CU_2, the transition is called inter-CU mobility.

[0055] L1 / L2 Triggered Mobility (LTM)

[0056] Inter-cell mobility can be triggered by L1 / L2 signaling to improve inter-cell mobility. L1 / L2 mobility enhancement can provide serving cell changes with lower latency, lower overhead, and lower interruption time via L1 / L2 signaling. Examples described throughout this document may include LTM procedures and signaling.

[0057] In the following discussion, 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 as a candidate PSCell in a candidate SCG.

[0058] Figure 7An embodiment of a signaling process for L1 / L2 triggered mobility (LTM) is shown. L1 / L2 triggered mobility (LTM) may include a process in which a base station receives L1 measurement reports from a UE and uses them to change the UE's serving cell via L1 / L2 signaling (e.g., MAC CE, DCI). The base station prepares one or more candidate cells and provides the candidate cell configurations to the UE via an RRC message. The LTM cell handover is then triggered by the base station selecting one of the candidate configurations as the target configuration for the LTM. The overall process for LTM is as follows: Figure 7 As shown. Subsequent LTMs can be performed by repeating the steps of pre-synchronization, LTM execution, and LTM completion without releasing other candidates after each LTM completion. As shown below, in one embodiment, there can be the following four main parts: 1) LTM preparation; 2) pre-synchronization; 3) LTM execution; and 4) LTM completion.

[0059] Figure 7 The process shown for LTM may include:

[0060] 1. The UE sends a MeasurementReport message to the base station. The base station decides to use LTM and initiates LTM candidate preparation.

[0061] 2. The base station transmits an RRCReconfiguration message to the UE. The RRCReconfiguration message includes the configuration of one or more LTM candidate target cells.

[0062] 3. The UE stores the configuration of the LTM candidate target cell and transmits an RRCReconfigurationComplete message to the base station.

[0063] 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 handover command.

[0064] 5. The UE performs L1 measurements on the configured LTM candidate target cells and transmits a low layer measurement report to the base station. The order of steps 4a / 4b and 5 can be modified to a different order. The UE can perform L1 measurements before performing DL synchronization and / or UL synchronization.

[0065] 6. The base station decides to perform LTM cell handover to the target cell and transmits a MAC CE triggering LTM cell handover by including the candidate configuration index of the target cell. The UE switches to the configuration of the LTM candidate target cell.

[0066] 7. If the TA is not available, the UE performs a random access procedure towards the target cell.

[0067] 8. The UE indicates successful completion of the LTM cell handover towards the target cell.

[0068] Candidate cell / cell group configuration

[0069] The NW configures and provides one or more LTM candidate cell configurations via an RRC message (eg, an RRCReconfiguration message).

[0070] The candidate cell configuration (i.e., the RRC model of the candidate cell configuration) can be configured with the following different options:

[0071] Option 1: One RRCReconfiguration message for each candidate configuration; and

[0072] Option 2: One or more IEs for each candidate configuration. The IEs may include at least one of the following:

[0073] RRCReconfiguration IE, CellGroupConfig IE, RadioBearerConfig IE,

[0074] MeasConfig IE, etc.

[0075] For Option 2, the signaling structure may include at least one of the following:

[0076] ● Option 2a: Have a common LTM candidate configuration list (e.g. ltm-CandidateToAddModList, ltm-CandidateToRemoveList). Each LTM candidate configuration includes a candidate configuration index,

[0077] CellGroupConfig IE, and other possible / optional configured IEs, such as

[0078] RadioBearerConfig, MeasConfig.

[0079] • Option 2b: There may be a separate LTM candidate partial list for each possible IE (e.g. candidate CellGroupConfig ToAddMod / ToRelease list, candidate RadioBearerConfig

[0080] ToAddMod / ToRelease list, candidate MeasConfig ToAddMod / ToRelease list,

[0081] and add some mappings / associations among them to have a complete LTM candidate configuration).

[0082] In option 2b, considering that some candidate cells may share common radio bearer configuration (e.g., for intra-DU candidates) and / or measurement configuration (e.g., for intra-frequency candidates), separate radio bearer configuration lists and measurement configuration lists may allow candidate cells to reference required configuration parts from separate lists.

[0083] The candidate cell configuration (eg, CellGroupConfig) may be linked with other possible configurations (eg, RadioBearerConfig, MeasConfig) according to various options.

[0084] ●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), and one or more reference indexes to reference other IE configurations from a separate reference configuration list / pool (e.g., a candidate radio bearer configuration index to reference the indicated radio bearer configuration from the candidate radio bearer configuration list, a candidate measurement configuration index to reference the 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 to one or more candidate cell indices to indicate that the configuration can be used by the associated candidate cell. For example, in the candidate radio bearer configuration list, for each candidate radio bearer configuration, it may be linked to one or more candidate cell indices to indicate that the configuration can be used by the associated candidate cell. A similar structure may also be applicable to the candidate measurement configuration list.

[0085] Examples of ASN.1 structures for LTM candidate configurations (i.e., for option 2b above) include:

[0086]

[0087]

[0088]

[0089] Figure 8 An embodiment of the candidate cell group list structure is shown. Figure 8An example signaling structure that can be used for signaling optimization is shown. The network / base station can configure multiple candidate cell groups (e.g., candidateCellGroupList). Each candidate cell group includes one or more candidate target cell configurations. The candidate cells included in a candidate cell group can share some common configurations (e.g., referring to the same reference configuration). Different candidate cell groups can be associated with different reference configurations. For each candidate cell, there can be a configured group. Each candidate cell group (CCG) can include different candidate cell configurations. The reference configuration can be configured in a separate reference configuration pool. Each reference configuration can be referenced from a candidate cell group (e.g., by indicating a reference configuration index).

[0090] During cell handover, when the UE resets the cell handover command, the UE may need to reset the L2 processing. For an example CCG structure, the UE may be different 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 handover between candidate cells belonging to one candidate cell group (i.e., intra-group cell handover) is intra-DU LTM (i.e., the UE does not need to perform an L2 reset when triggering the cell handover). Cell handover between candidate cells belonging to different candidate cell groups (i.e., inter-group cell handover) is inter-LTM (i.e., the UE needs to perform an L2 reset when triggering the cell handover). Therefore, the cell handover command may indicate the candidate cell group ID and the candidate cell configuration ID to help the UE distinguish between intra-DU LTM and inter-DU LTM.

[0091] 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, intra-group cell handover is intra-DU LTM. Inter-group cell handover can be intra-DU or inter-DU LTM. Therefore, the network / base station can additionally indicate in the cell handover command whether the cell handover is intra-DU or inter-DU when the cell handover is an inter-group cell handover. The cell handover command may include at least one of the following information:

[0092] ●Candidate cell group ID / index;

[0093] ●Candidate cell configuration ID / index; or

[0094] ●Indication used to indicate whether the cell handover is intra-DU or inter-DU cell handover

[0095] If the received candidate cell group ID / index is the same as the CCG ID / index of the CCG including the candidate cell configuration currently applied by the UE, the UE may consider the cell handover to be an intra-DU cell handover. Otherwise, the UE may consider the cell handover to be an inter-DU cell handover. For intra-DU cell handover, during the cell handover, the UE may not perform an L2 reset, or may perform a partial L2 reset (e.g., a partial MAC reset). For inter-DU cell handover, the UE may perform an L2 reset during the cell handover. The L2 reset may include a MAC reset, an RLC re-establishment, and / or a PDCP data recovery.

[0096] For each LTM candidate cell configuration, it can be configured using incremental configuration, reference configuration and / or reference index. The reference index can be used to indicate the 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:

[0097] ●Candidate cell configuration index;

[0098] Cell group configuration, such as CellGroupConfig IE;

[0099] ● Reference index (e.g. reference cell group configuration ID) used to reference the configuration list from the candidate cell group level

[0100] The indicated cell group level configuration of the table;

[0101] Radio bearer configuration, such as RadioBearerConfig IE;

[0102] A reference index (e.g., a reference radio bearer configuration ID) used to reference a candidate radio bearer configuration

[0103] the radio bearer configuration indicated by the configuration list;

[0104] RRM measurement configuration, such as MeasConfig IE;

[0105] Reference index (e.g., reference measurement configuration ID) used to reference the referenced measurement configuration from the candidate measurement configuration list

[0106] RRM measurement configuration shown;

[0107] • A reference index (eg, reference cell ID) used to reference the indicated candidate cell configuration from the candidate cell list.

[0108] For each IE in the LTM candidate cell configuration, it can also be configured with a delta configuration or a reference index.

[0109] For some dedicated / specific configurations of candidate cells (e.g., TA / TAG configuration, CFRA resource configuration, BWP configuration, or C-RNTI), the network / base station may configure some common configuration pools for possible resources / configurations required by all serving cells and candidate cells. The association of candidate cells with dedicated / specific configurations may include the following options:

[0110] Option 1: A separate list may be configured by the network / base station to associate candidate cells with dedicated / specific configurations (eg, a configuration index linked to a candidate cell index).

[0111] Option 2: The association between a specific resource / configuration and a candidate cell may be indicated in the candidate cell configuration (ie via an RRC message) (eg, including a configuration index in the candidate cell configuration).

[0112] Option 3: The association between a specific resource / configuration and a candidate cell may be indicated by a cell handover command (or dynamically indicated) (eg, including a configuration index in the cell handover command).

[0113] The reference configuration can be defined to reduce the overhead for each candidate cell. Each candidate cell can have multiple partial configurations to generate a complete / full configuration. Handover (HO) can use the source configuration as a baseline and reconfigure different parts of the candidate cell to improve performance. The incremental configuration can be a different / other part of the reference configuration. The LTM candidate cell configuration can be configured using the incremental configuration. The incremental configuration is generated based on the reference configuration. The reference configuration definition can be the following options:

[0114] Option 1: The reference configuration is explicitly configured by the NW (ie, a separate reference configuration).

[0115] Option 1-1: Designate / indicate one candidate cell as a reference configuration (eg, the network / base station indicates a reference cell index within each candidate cell configuration).

[0116] Option 1-2: Define a reference configuration that is independent of the candidate cell configurations.

[0117] Option 2: The reference configuration is the UE configuration when the candidate cell configuration is received, ie the initial source configuration.

[0118] Option 3: The reference configuration is the UE configuration when the cell handover command is received. In one example, the network / base station provides cell 1, cell 2, cell 3, and the UE then maintains the configuration for each cell, so there is no need to provide updates for each candidate configuration, which is based on pre-configuration.

[0119] Option 3-1: For each candidate cell, the network / base station pre-configures several candidate incremental configurations, each configuration being based on a possible source cell (eg, initial source cell, other candidate cells).

[0120] Option 3-2: Upon receiving the candidate cell configuration, for each candidate cell, the UE interprets the received candidate cell configuration and generates a set of incremental configurations based on possible source cells.

[0121] For option 1, the reference configuration can be configured as: 1) a complete set of cell configurations, such as including an RRCReconfiguration message; 2) a set / pool of common configurations among multiple cells (such as a set / pool of RSs across source and candidate cells); or 3) multiple reference configuration sets for different configuration parts (such as a set of reference cell group configurations, a set of reference radio bearer configurations, or a set of reference measurement configurations).

[0122] Figure 9 An embodiment of the candidate cell signaling structure is shown. In particular, Figure 9 This can be applied to option 3 above. For each candidate cell, there may be a set of incremental configurations, where each incremental configuration is linked to a reference cell ID (e.g., an index of another candidate cell). If the reference cell ID does not exist, this may imply that the incremental configuration is generated based on the initial source configuration. For the example between DUs, each candidate DU may need to know the candidate cell configurations generated by other candidate DUs (e.g., a full configuration or incremental configuration based on the initial source configuration). This process may introduce additional and complex interactions between the CU and the candidate DU.

[0123] The UE behavior upon receiving the reference cell and / or candidate cell configurations may include the UE storing the reference configuration and the candidate cell configuration in separate variables (e.g., storing the reference configuration as separate configurations, such as storing the reference configuration in VarReferenceConfig). If the reference configuration is the initial source configuration, the UE may store the source configuration as a separate configuration upon receiving the candidate cell configuration or after completing the initial / first LTM execution (e.g., switching from the initial source cell to the candidate cell). In an alternative example, the UE converts each incremental configuration into a full configuration and stores the full configuration for each candidate cell.

[0124] For options 1 and 2, when LTM execution is triggered (for example, a cell handover command is received), the UE can first reply or recover to the reference configuration, and then apply the incremental configuration of the target candidate cell based on the reference configuration. During this process, the UE may need to release and add back some RLC bearers. For example, the reference configuration includes two RLC bearers, candidate cell #1 has two RLC bearers (for example, RLC bearer 1, RLC bearer 2), and candidate cell #2 and cell #3 have three RLC bearers (for example, RLC bearer 1, RLC bearer 2, RLC bearer 3). For the first cell handover from cell #1 to cell #2, the UE needs to add a third RLC bearer to the cell #2 configuration based on the reference configuration. For the second cell handover from cell #2 to cell #3, the UE first needs to return to the reference configuration, which requires releasing RLC bearer 3. Then, the UE applies the incremental configuration to cell #3 based on the reference configuration, which requires adding RLC bearer 3 again. Releasing and adding RLC bearer operations have similar effects to reestablishing RLC (e.g., the UE will discard all RLC SDUs, RLC SDU segments, and RLC PDUs, if any), and reset all state variables to their initial values. Similar issues may apply to SCell release and addition, such as sCellToAddModList.

[0125] To avoid the problem of unnecessary freeing and adding, there are several possible solutions:

[0126] • Alternative 1: The reference configuration includes all possible RLC bearers and / or SCells across all candidate cells.

[0127] ● Alternative 2: Upon receiving a cell handover command, the UE stores the RLC state variables and the data stored in the transmit and receive buffers in the RLC entities, and then restores to the reference configuration. After applying the incremental configuration based on the reference configuration, the UE restores the corresponding RLC state variables and the data in the transmit and receive buffers for each established RLC entity.

[0128] • Alternative 3: The network / base station should not reconfigure the RLC bearer for LTM, i.e. the RLC bearer should not be allowed to add, modify or release the LTM candidate cell configuration.

[0129] For option 3, when LTM execution is triggered (e.g., receiving a cell handover command), the UE may directly apply the incremental configuration for the target candidate cell (which is based on the current source cell), e.g., applying the incremental configuration linked with a reference index to reference the current source cell.

[0130] L1 measurement configuration

[0131] 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. Inter-cell beam management (ICBM) may be present to support the performance of SSB-based L1 measurements on non-serving cell beams by configuring L1 SSB measurement resources for non-serving cells in the serving cell configuration and associating the TCI state with an additional PCI (i.e., non-serving cell PCI). Rel-17 ICBM can be applied to the intra-DU intra-frequency example. To support inter-cell L1 measurements for LTM candidate cells, some enhancements may be considered.

[0132] Figure 10 An embodiment of the signaling structure for L1 measurement configuration is shown. L1 measurement resources for non-serving cells (i.e., additional PCI information in additionalPCI-ToAddModList and associated SSB configuration) can be configured under ServingCellConfig. The TCI state can be linked to the non-serving cell by indicating the additional PCI index configured by additionalPCI-ToAddModList in ServingCellConfig. In CSI-MeasConfig, the CSI-SSB resources for non-serving cells are indicated by servingAdditionalPCIList-r17 within CSI-SSB-ResourceSet in csi-SSB-ResourceSetToAddModList. There may be additional PCI information indicating the PCI index and / or SSB configuration.

[0133] For the L1 measurement framework, there can be multiple options:

[0134] Option 1: Reuse the R17 ICBM framework (e.g. Figure 10 ), that is, the L1 RS resources for the serving candidate cell are explicitly indicated in the source cell configuration. In this example, the candidate DU and the source DU may need to perform some interaction via the CU. The CSI measurement configuration explicitly indicates the RS index to be measured by the UE for the serving and candidate cells. 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 (e.g., CSI-MeasConfig) of the serving cell to provide the L1 RS resources for the serving cell and candidate cells, as well as the L1 reporting configuration, etc.

[0135] 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., when receiving the LTM candidate cell configuration) to perform L1 measurement of the candidate cell.

[0136] Option 3: The L1 RS resources and / or TCI states for serving and candidate cells are configured in separate configuration sets, for example, a common L1 measurement pool is used to configure the L1 measurement configuration and / or TCI states for serving and candidate cells. The TCI state can be used to provide / configure the association between RS / beam and cell. This may be similar to the reference configuration discussed above. Reference candidates are collected for resource indexing or reference indexing reference. The common L1 measurement pool can be generated by the CU or DU. The common L1 measurement pool configuration always remains unchanged. It can be updated or released through an RRC reconfiguration message. The network / base station can explicitly indicate / configure which candidate cells / RS will be measured for LTM triggering (for example via CSI-MeasConfig). The network / base station may not explicitly indicate / configure which candidate cells / RS will be measured for LTM triggering. The strongest RS index of, for example, the serving cell and the target cell may be measured and reported by the UE. The network / base station can dynamically indicate / activate which candidate cells / RSs will be measured for LTM triggering, indicating the candidate cell index, beam / RS index and / or TCI status through L1 / L2 signaling.

[0137] L1 measurement RS resource configuration can be used to avoid repeated RS resource configuration between candidate cells and reduce signaling overhead. The L1 measurement resource set configuration (e.g., SSB, CSI-RS resource configuration) can be decoupled from the serving cell configuration, that is, a set / pool of RS resource configurations is defined. The RS resource configuration set / pool can be configured under the RRCReconfiguration message, CellGroupConfig IE, or 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 candidate cell. RS resource configuration (e.g., similar to CSI-ResourceConfig) may include at least one of the following: 1) SSB resource configuration; 2) SSB resource set configuration; 3) CSI-RS resource configuration; or 4) CSI-RS resource set configuration, each of which will be discussed below.

[0138] SSB resource configuration may include at least one of the following:

[0139] SSB configuration index

[0140] ●The periodicity of SS / PBCH blocks, e.g.

[0141] A bitmap indicating the time domain position of the SS blocks transmitted in a half-frame with SS / PBCH blocks, e.g. ssb-PositionsInBurst

[0142] The average EPRE of resource elements carrying auxiliary synchronization signals used by the network / base station for SSB transmission, in dBm, e.g. ss-PBCH-BlockPower

[0143] ● Measurement timing configuration (i.e., the timing when the UE measures SSB), such as SSB-MTC

[0144] SSB frequency

[0145] The SSB resource set configuration may include at least one of the following:

[0146] ●SSB resource collection configuration index;

[0147] A list of SSB indices indicating the SSBs to be measured;

[0148] ● A list of PCIs associated with the SSB;

[0149] ● Measurement timing configuration (i.e., the timing at which the UE measures the SSB), such as SSB-MTC; or

[0150] ●SSB frequency.

[0151] The CSI-RS resource configuration may include at least one of the following:

[0152] CSI-RS configuration index;

[0153] NZP CSI-RS resource configuration (e.g. including periodicity and slot offset for CSI-RS, power offset of REs, reference to TCI state, slot and subcarrier occupancy in PRBs of CSI-RS resources)

[0154] OFDM symbol position in the rate, scrambled ID);

[0155] ● CSI-IM resource configuration (e.g. including resource element pattern); or

[0156] The frequency of CSI-IM.

[0157] The CSI-RS resource set configuration may include at least one of the following:

[0158] ●CSI-RS resource set configuration index;

[0159] A list of CSI-RS resource indices indicating the CSI-RS to be measured;

[0160] The frequency of the CSI-RS; or

[0161] ●Other collection-specific parameters.

[0162] An information list can be generated to indicate which L1 resource configurations are associated with which candidate cells. The information list may include an additional / candidate cell information list. The additional / candidate cell information list (e.g., additionalPCI-ToAddModList, candidateCellToMeas-ToAddModList, TCI-statelist) can be configured to link RS resource configuration, beam information or TCI state with different cells (e.g., including serving cells, non-serving cells and / or candidate cells). RS resources, beam information or TCI state are configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmission. There may be an additional / candidate cell information list for UL transmission only, an additional / candidate cell information list for DL ​​transmission only, or / and an additional / candidate cell information list for UL and DL transmission. Each item in the information list may include at least one of the following:

[0163] ●Cell identification information, such as PCI, candidate cell ID / index, serving cell ID / index, candidate cell ID / index,

[0164] Zone configuration ID / index;

[0165] RS resource configuration index, e.g., for referencing an RS configuration (e.g., CSI-RS, SSB) in an RS resource configuration set / pool;

[0166] SSB configuration index, for example, used to reference an SSB configuration in an RS resource configuration set / pool;

[0167] ●SSB resource set configuration index, for example, used to reference SSB resources in the RS resource configuration set / pool

[0168] Collection configuration;

[0169] ●CSI-RS configuration index, for example, used to reference a CSI-RS configuration in an RS resource configuration set / pool;

[0170] or

[0171] ● CSI-RS resource set configuration index, for example, used to reference a CSI-RS resource set configuration in an RS resource configuration set / pool.

[0172] 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, CellGroupConfigIE, and / or ServingCellConfigIE. The additional / candidate cell information list may be combined with the candidate cell configuration list or configured in the candidate cell configuration. The TCI state list may be configured to link the TCI state with the cells in the additional / candidate cell list to indicate which cell's RS signal is configured as the QCL source for the relevant TCI state.

[0173] Based on the above embodiments, possible signaling structures for R18 L1 measurement resource configuration may include: ● Alternative 1: RS resource configuration pool and / or additional / candidate cell information list in

[0174] Configure under ServingCellConfig (i.e. the current structure).

[0175] • Alternative 2: The RS resource configuration pool and / or the additional / candidate cell information list are configured under CellGroupConfig. Figure 11a A first embodiment of a configuration signaling structure is shown; Figures 11b to 11e

[0176] The remaining structure of the configuration signaling structure is shown. Figure 11b Shown from Figure 11a Example cell group configuration. Figure 11c Shown from Figure 11a Example cell information list. Figure 11d Shown from Figure

[0177] 11a example resource configuration pool. Figure 11e Shown from Figure 11a · Alternative 3: The RS resource configuration pool and / or additional / candidate cell list are configured under the RRCReconfiguration message, i.e. in parallel with CellGroupConfig. Figure 12 A second embodiment of the configuration signaling structure is shown.

[0178] • Alternative 4: The additional / candidate cell information list is combined with the candidate cell configuration list, eg, for each candidate cell, the RS configuration (by referencing the RS configuration index) is directly configured with the candidate cell configuration. Figure 13The third embodiment of the configuration signaling structure is shown. The RS resource configuration pool can be configured under the CellGroupConfig of the source cell or under the RRCReconfiguration message.

[0179] The L1 measurement report configuration can be provided by the CSI-ReportConfig in the CSI-MeasConfig within the ServingCellConfig, for example, configured per cell. In the CSI-ReportConfig, CSI-ResourceConfigId and ServCellIndex can also be referenced to indicate in which cell the indicated CSI-ResourceConfig is found. The source cell needs to know the RS resource configuration generated by each candidate cell / DU to generate the report configuration (e.g., report type, report resources) for the L1 measurement report of these candidate cells. If the traditional L1 measurement mechanism is reused, then in each source serving cell, it is necessary to configure which cell's RS resources can be measured and reported, which may result in a complex and heavy signaling structure. One embodiment may allow the reuse of the L3 measurement mechanism (e.g., the UE can measure all configured L1 RS resources, but report the strongest RS index).

[0180] Reporting mechanisms could include:

[0181] ● Option 1: The network / base station explicitly configures / indicates in which cell RS resources can be measured and / or in which cell L1 reports can be sent, for example, reusing the CSI measurement mechanism. The UE measures L1 RS and performs L1 measurement reporting based on the network / base station configuration.

[0182] ● Option 2: L1 RS resources are not explicitly configured / indicated for each cell. The UE may measure all configured L1 RS resources but report the strongest RS index, or the strongest RS index and associated cell ID, e.g., a measurement mechanism similar to L3.

[0183] The report configuration may include at least one of the following information:

[0184] A trigger event, such as a candidate cell's L1 measurement becoming better than a network / base station configured threshold, or the number of candidate cell L1 measurements that are better than a network / base station configured threshold being higher than a network / base station configured number. A maximum number of RSs / beams and / or cells that can be reported in one L1 measurement report.

[0185] 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:

[0186] ● Cell ID information, such as PCI, PCI+frequency, candidate cell configuration index, serving cell ID. · RS / beam ID, such as RS / beam resource configuration index, SSB index, CSI-RS index. Each RS ID can be associated with a cell ID.

[0187] ● Additional / candidate cell information index, such as TCI state ID, is used to indicate the association between RS / beam and cell.

[0188] L1 measurement ID, used to link RS resources with reporting configurations

[0189] L1 measurement results, such as L1-RSRP, L1-RSRQ and / or L1-SINR.

[0190] ● An indication of whether UL synchronization is available / completed for the associated candidate cell and / or candidate RS / beam.

[0191] ● An indication indicating whether the TA is available / acquired for the associated candidate cells and / or candidate RS / beams.

[0192] For signaling optimization, a separate report configuration set / pool can be configured, for example, similar to RS resource configuration. Each report configuration can include at least one of the following: report configuration index, report type, number of reports, report resources, etc. If the report is sent on the PUSCH (e.g., a semi-persistent or aperiodic report sent on the PUSCH triggered by a DCI, or a report conveyed by a MAC CE), it may not be necessary to configure the PUCCH reporting resources in the report configuration.

[0193] A separate L1 measurement association list (e.g., a measurement ID list) may be configured to link RS resource configuration with reporting configuration. For example, the L1 measurement ID list may include:

[0194] • Alternative 1: RS resource configuration ID and report configuration ID, ie, do not indicate in which cell the RS resources are to be discovered and in which cell the report is to be sent.

[0195] • Alternative 2: RS resource configuration ID, cell ID of RS resource to be discovered, and report configuration ID. • Alternative 3: RS resource configuration ID, cell ID of RS resource to be discovered, report configuration ID

[0196] and the cell ID to which the report is to be sent.

[0197] ● Alternative 4: Additional / candidate cell information index (eg TCI state ID) and reporting configuration ID.

[0198] In some embodiments, the RS resource configuration ID and the cell ID for which the RS resources are to be discovered can be combined into an index (e.g., the additional / candidate cell information index discussed above). In some embodiments, the reporting configuration ID and the cell ID for which the report is to be sent can be combined into an index. The reporting configuration set / pool can be configured in the RRCReconfiguration message, CellGroupConfig IE, or ServingCellConfig IE. The L1 measurement association list can be configured in the RRCReconfiguration message, CellGroupConfig IE, or ServingCellConfig IE.

[0199] In some embodiments, a reference configuration exists for L1 measurements. An RS resource configuration pool, additional / candidate cell information lists, reporting configuration sets / pools, and / or L1 measurement association lists may be considered components of the reference configuration. A candidate cell may refer to an index from such a pool / list to configure the L1 measurement configuration.

[0200] Figure 14 Example network signaling for LTM is shown. In one example, the network / base station explicitly configures / indicates in which cell RS resources can be measured and / or in which cell L1 reports can be sent (e.g., reusing CSI measurement mechanism). The reference configuration can be generated by the CU (e.g., configured under RRCReconfiguration message) or the source DU. Figure 14 As shown, perform the following steps:

[0201] 1. The CU sends a list of suggested candidate cells to the candidate DU via F1 signaling, such as a UE Context Setup Request message.

[0202] 2. The candidate DU generates a candidate cell configuration and / or L1 RS resource for each candidate cell. The candidate DU sends the generated candidate cell configuration, L1 RS resource configuration and / or TCI state configuration to the CU.

[0203] 3. The CU generates a reference configuration based on the configuration from the candidate DU (eg, including a common L1 RS resource pool, a common L1 measurement pool, or an additional / candidate cell information list).

[0204] 4a / b. The CU triggers source configuration update and / or candidate configuration generation / update based on the reference configuration (e.g., via the UE context modification procedure or the UE context establishment procedure). For candidate configuration generation / update, the CU sends a reference configuration to the candidate DU via F1 signaling, such as a UE context establishment / modification request message. The message may also include other candidate DU / cell information, such as candidate DU ID, candidate cell ID, RS configuration of the candidate cell, TCI state configuration of the candidate cell, etc. The candidate DU generates / updates the candidate cell configuration of the candidate cell belonging to the DU based on the reference configuration from the CU. For example, CSI-MeasConfig is generated / updated, for example, with reference to an RS index from a 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 an RS resource configuration pool and / or an additional / candidate cell information list, etc. The candidate DU sends the generated / updated candidate cell configuration to the CU via F1 signaling, such as a UE context establishment / modification request confirmation message. The message may also include the L1 measurement RS configuration and / or TCI state configuration of the candidate cell.

[0205] A similar process can also be applied to source configuration updates: the CU transmits the reference configuration and 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 based on the reference configuration and the received candidate cell information / configuration, for example, reconfiguring the CSI-MeasConfig and TCI state. The source DU sends the updated source configuration to the CU.

[0206] 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.

[0207] 7-8. The UE responds to the CU with an RRC reconfiguration complete message via the source DU.

[0208] 9. The UE measures the L1 RS for the candidate cell, which may be explicitly indicated by the NW, for example within the CSI-MeasConfig of the source cell.

[0209] 10. The UE reports L1 measurements (e.g., CSI reports) to the source cell based on network / base station instructions, such as in the CSI-MeasConfig of the source cell or via dynamic scheduling of DCI.

[0210] 11. The source DU selects a candidate cell as the target for LTM based on the L1 measurement results. The source DU sends a cell handover command to the UE to indicate the target cell for LTM, for example, including a target candidate cell configuration index.

[0211] 12. The UE performs LTM to access / handover to the target cell.

[0212] In some embodiments, steps 1 and 2 may be skipped, for example, if the CU or DU has already generated a reference configuration.

[0213] In some embodiments, in step 3, for each candidate DU / cell or source DU / cell, when the UE accesses the candidate cell, the CU may generate / indicate the L1 RS resources to be measured by the UE, for example, generating a mapping between the L1 RS resources and other candidate cells, such as an additional / candidate cell information list. The CU may then send the additional / candidate cell information list to the candidate DU and the source DU (e.g., via steps 4a / b).

[0214] In another embodiment, the network / base station may not explicitly indicate / configure which candidate cells / RSs are to be measured for LTM triggering. Figure 15 Another example of network signaling for LTM is shown. Figure 15 The steps of the illustrated embodiment are described as follows:

[0215] 1-3. With Figure 14 Similar to steps 1-3 in .

[0216] 4-5. The CU generates an RRC reconfiguration message including the LTM candidate cell configuration and / or reference configuration (eg, 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.

[0217] 6-7. The UE responds to the CU with an RRC reconfiguration complete message via the source DU.

[0218] 8. The UE measures the L1 RS indicated by the SSB and / or CSI-RS resource index in the common L1 RS resource pool. The UE can dynamically measure the L1 RS indicated by the network / base station, for example, via MAC CE or DCI.

[0219] 9. The UE reports L1 measurements to the source cell, for example, via a MAC CE. L1 measurement reporting may be triggered when certain events are met, such as when the L1 measurement of a candidate cell becomes better than a threshold configured by the network / base station, when the number of L1 measurements of candidate cells that are better than the threshold configured by the network / base station is higher than the number configured by the network / base station, etc. The L1 measurement report may include the strongest RS index, the associated cell ID, and / or the L1-RSRP / RSRQ / SINR of the indicated RS index.

[0220] 10. The source DU selects a candidate cell as the target of LTM. The source DU sends a cell handover command to the UE to indicate the target cell of LTM, for example, including the target candidate cell configuration index.

[0221] 11. The UE performs LTM to access / handover to the target cell.

[0222] LTM execution

[0223] L1 / L2 triggered mobility (LTM) may then be performed to transfer from the source cell to the target cell. For LTM execution, there may be a cell handover command. The cell handover command may be conveyed via MAC CE or DCI. The cell handover command may include at least one of the following information:

[0224] ●Candidate cell configuration index;

[0225] ● TCI status indication of the target cell;

[0226] The beam / RS ID of the target cell;

[0227] L2 reset indication, e.g. for PDCP recovery, RLC re-establishment, MAC reset and / or MAC part

[0228] points reset;

[0229] RACH-related information, such as the CFRA resources to be used for RACH (e.g., preamble index), an indication of whether RACH is required, and an indication of whether the CFRA resources pre-configured in the RRCReconfiguration of the target cell are available;

[0230] TA or TAG information of the target cell;

[0231] BWP ID;

[0232] SCell activation / deactivation indication;

[0233] C-RNTI;

[0234] ● an indication as to whether the cell handover is an intra-DU or inter-DU situation; or

[0235] ● Indication on which candidate cells / beams L1 measurements should be enabled. After cell handover to the target cell, the UE may perform L1 measurements on the indicated candidate cells / beams, e.g. for subsequent LTM execution.

[0236] Upon receiving a cell handover command, the UE applies the configuration of the LTM target candidate cell (i.e., the cell configuration indicated by the candidate cell configuration index in the cell handover command). The UE may perform a RACH-based procedure (e.g., CFRA, CBRA) or a RACH-less / RACH-skip procedure to handover / access the target cell. For example, if the TA is not available, the UE performs a random access procedure toward the target cell.

[0237] During cell handover to the target cell, the UE can notify / inform the target cell about the UE's arrival. For CFRA-based LTM, the UE can send a preamble as a notification of the UE's arrival. For CBRA-based LTM, the UE can send a C-RNTI MAC CE in Msg.3 as a notification of the UE's arrival. For RACH-less / RACH-skip LTM, the options may include:

[0238] Option 1: The UE sends a target cell ID (e.g., C-RNTI, via C-RNTI MAC CE) to the target cell with a pre-allocated UL grant associated with the beam / RS / TCI state indicated by the cell handover command. The pre-allocated UL grant (e.g., configured grant type 1) is 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.

[0239] 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 handover command. The SRS resources are pre-configured by the network / base station (e.g., in the SRS-Config within the candidate cell configuration), and each SRS is associated with the beam / RS / TCI state of the candidate cell.

[0240] For RACH-based LTM, after successfully completing the RACH procedure, the UE considers LTM to be successfully completed, i.e., LTM execution is successfully completed. For RACH-less / RACH-skip LTM, the UE considers LTM to be successfully completed when UL messages / signaling (e.g., UCI, MAC CE, RRC reconfiguration complete message) are successfully transmitted to the target cell, when the first UL scheduling or first DL transmission is received from the target cell, or when a DCI for dynamic scheduling of UL grants or DL ​​allocations addressed to the new C-RNTI is received from the target cell.

[0241] In the inter-DU example, the target DU may need to be informed / coordinated with some information, such as the TCI status indication of the target cell, the beam / RS ID of the target cell, RACH related information, BWP ID, SCell activation / deactivation, C-RNTI, etc. Regarding how to notify the target DU of such information, multiple options may include:

[0242] ● Option 1: Before sending the cell handover command, the source DU coordinates with the target DU.

[0243] ● Option 2: The source DU notifies the target DU after sending the cell handover command.

[0244] Option 3: The UE notifies the target DU upon completion of the cell handover, for example, via an UL message / signaling to the target cell. The UL message / signaling notifying the completion of LTM can be an RRC message, a MAC CE, or UCI. The UL signaling can include or indicate at least one of the following: the target cell ID (e.g., target candidate cell configuration index, C-RNTI), the TCI status indication of the target cell, the beam / RSID of the target cell, the activated or deactivated SCell ID, etc.

[0245] There may be issues with failure detection and handling. A timer may be introduced for LTM, such as 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 may be configured by the network / base station, for example via an RRC reconfiguration message. The timer value may include 5ms, 10ms, 20ms, 40ms, 50ms, 100ms, 200ms, 500ms, 1000ms, etc. The timer is started when LTM execution is triggered (for example, a cell handover command is received), or when UE-triggered L1 / L2 mobility is executed (i.e., when the stored candidate cell configuration is applied, or when it is detected that the execution conditions are met). The timer stops when the LTM execution is successfully completed. Once the timer expires, the UE will consider that the LTM has failed, i.e., an LTM failure is detected. Upon detecting an LTM failure, the UE may perform at least one of the following operations:

[0246] ●Alternative 1: Trigger the RRC re-establishment process;

[0247] ● Alternative 2: Fall back to the source cell and / or report the LTM failure to the NW, for example, sending an LTM failure report to the network / base station via a MAC CE or RRC message; or

[0248] ● Alternative 3: Select another cell among the stored candidate cells to perform a new LTM execution, for example, select the candidate cell when its conditions are met, which may include RSRP / RSRQ / SINR thresholds configured by the network / base station.

[0249] In alternative 2, the network / base station may explicitly configure / indicate whether the UE is allowed to fall back to the source cell and / or report LTM failure to the NW upon detecting LTM failure.

[0250] The LTM failure report may include at least one of the following information:

[0251] ●Failed target candidate cell ID / index;

[0252] ●Failure type, such as LTM failure;

[0253] ● Available L1 and / or L3 measurement results for the serving cell and / or candidate cells; or

[0254] ● Recommended / suggested candidate cells and / or beams / RSs, which the network / base station can consider as candidates for subsequent LTM execution.

[0255] In alternative 3, the network / base station can explicitly configure / indicate whether the UE is allowed to perform another LTM execution on other candidate cells after detecting an LTM failure. A timer can be introduced to control the time when the UE can attempt a new LTM execution after detecting an LTM failure, such as an LTM failure timer (t3xx). This timer is started when an LTM execution is triggered or when an LTM failure is detected. This timer is stopped when the LTM execution is successfully completed. Once this timer expires, the UE will initiate the RRC re-establishment procedure. This timer value may be longer than the LTM timer.

[0256] A counter can be introduced to control the number of times the UE can attempt a new LTM execution after detecting an LTM failure. Each time the UE attempts LTM execution, the counter value is incremented by 1. When the number of LTM attempts reaches the maximum counter value, the UE will initiate the RRC re-establishment procedure. The maximum counter value can be configured by the network / base station, for example, via an RRC reconfiguration message.

[0257] Some examples for LTM failure recovery may include:

[0258] Upon detecting an LTM failure (e.g., t3xx expiration), the UE will trigger RRC re-establishment. During the RRC re-establishment procedure, if cell selection is triggered by detecting an MCG failure (e.g., RLF), LTM failure, or handover failure, and the selected cell is an LTM candidate cell, the UE may trigger LTM execution on the selected cell. Otherwise, the UE will trigger the traditional / normal re-establishment procedure.

[0259] Once LTM execution is triggered, the UE will start the LTM timer and / or LTM failure timer. Once LTM failure is detected (e.g., LTM timer expiration), and if the LTM failure timer is running, the UE can select another LTM candidate cell to try a new LTM execution. In some examples, the selected candidate cell should meet a threshold set by the NW, such as an RSRP threshold.

[0260] Alternatively, if the LTM failure timer expires, the UE may trigger RRC re-establishment.

[0261] Candidate cell / cell group status

[0262] The UE may maintain candidate cell / cell group (CG) configurations to support subsequent LTM. Therefore, a cell / CG state should be defined for each candidate cell / CG. The network / base station may dynamically select / activate a subset of configured candidate cells to be measured via L1 / L2 signaling, for example, for subsequent LTM and / or power saving. Therefore, the UE may maintain some candidate cell / CG configurations, but the UE is not required 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.

[0263] Figure 16 An example of cell or cell group (CG) state transition is shown. For each candidate cell / CG, it can have the following states:

[0264] Pre-configured state: The UE stores / maintains the cell / CG configuration but does not apply the cell / CG configuration. The UE performs L1 measurements on the cell / CG.

[0265] ● Pre-configured but suspended state: the UE stores / maintains the cell / CG configuration but does not apply the cell / CG configuration, and the UE stops / suspends L1 measurement on the cell / CG; ● Activated state: the UE behavior is the same as the currently activated serving cell / CG, such as performing DL reception / UL transmission with the cell, performing radio link monitoring and / or beam failure detection on the cell, performing measurements on the cell, etc.; or

[0266] Deactivated state: The UE behaves the same as the currently deactivated serving cell / CG, e.g. suspending DL reception / UL transmission with the cell and, if instructed by the network / base station, performing radio link monitoring and / or beam failure detection on the cell (e.g. for a deactivated SCG,

[0267] bfd-and-RLM is configured as true).

[0268] A candidate cell / CG in a preconfigured but suspended state may not consume any UE capabilities related to L1 measurement execution. A candidate cell / CG in a preconfigured state and / or a preconfigured but suspended state may not consume any UE capabilities of a serving cell (including activated and deactivated serving cells).

[0269] When receiving the LTM candidate cell / CG configuration from the network / base station, the UE may consider the stored candidate cell / CG to be in the pre-configured state or the pre-configured but suspended state. Entering the pre-configured but suspended state from the pre-configured state may include:

[0270] ●When receiving network / base station signaling indicating that L1 measurement on a candidate cell / CG is not enabled / allowed / activated, the UE considers the candidate cell / CG to be in a pre-configured but suspended state and stops / suspends L1 measurement on the cell / CG.

[0271] Entering the provisioning state from the provisioning but pending state can include:

[0272] ●When receiving network / base station signaling indicating that L1 measurement on a candidate cell / CG is enabled / allowed / activated, the UE considers that the candidate cell / CG is in a pre-configured state and starts / resumes L1 measurement on the cell / CG.

[0273] Entering the active state from the pre-configured state may include:

[0274] ●When receiving network / base station signaling (e.g., a cell switching command) indicating that the candidate cell / CG is the target for cell switching, or that the candidate cell / CG has been activated (e.g., for an SCell or SCG), the UE applies the cell configuration of the target cell, performs cell switching to the target cell, and / or considers the cell to be in an activated state.

[0275] Entering the deactivated state from the pre-configured state may include:

[0276] ●When receiving network / base station signaling (e.g., a cell handover command) indicating that a candidate cell / CG has been 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.

[0277] From the activated state to the deactivated state / preconfigured state / preconfigured but suspended state may include: when receiving network / base station signaling (such as a cell switching command), the activated source cell may be converted to the deactivated state / preconfigured state / preconfigured but suspended state.

[0278] The transition from the deactivated state to the activated state / preconfigured state / preconfigured but suspended state may include: upon receiving network / base station signaling (e.g., a cell handover command), the deactivated source cell may be transitioned to the activated state / preconfigured state / preconfigured but suspended state. The state transition between activated and deactivated may be applicable to at least the SCell and SCG.

[0279] LTM in NR-DC

[0280] LTM can be supported in NR-DC scenarios (e.g., for intra-SN scenarios). The following examples can be considered:

[0281] Example 1: LTM is configured only in the MN, e.g., for intra-MN PCell change with / without SCell change;

[0282] • Example 2: LTM is configured only in the SN, e.g. for intra-SN PSCell change with / without SCell change; or

[0283] • Example 3: LTM is independently configured in the MN and SN.

[0284] In some examples, LTM within one node may have no impact on another node, such as intra-frequency LTM, and LTM within one node may be transparent to another node. In particular, no inter-node coordination may need to be performed before sending a cell handover command to trigger LTM. The MN / MCG and SN / SCG may maintain a pool / list of candidate cells within each node (e.g., candidate cells within the pool are configured for intra-frequency LTM):

[0285] ●If LTM is triggered for a candidate cell change in the pool of the MCG, the MCG does not need to notify the SCG, i.e. it is transparent to other CGs, and vice versa.

[0286] • If L1 / L2 mobility is triggered for a candidate cell change outside the MCG's pool, the MCG should coordinate with the SCG before sending a cell handover command to the UE and vice versa.

[0287] In the example where LTM within one node has an impact on another node (e.g., inter-frequency LTM), the MN and SN may also perform coordination when preparing the candidate cell configuration. For the candidate cells in the MN, the SCG configuration may also be included in the candidate cell configuration, for example, including the MRDC-SecondaryCellGroupConfig IE. The triggering performed on the LTM may trigger a PCell change with a PSCell change. For the candidate cells in the MN, a list of allowed candidate PSCells may be pre-configured. When triggering the LTM in the MN, the MN may select a candidate PSCell from the list of allowed candidate PSCells to perform LTM for the PCell change with a PSCell change. In this example, the UE may also need to report L1 measurements on the candidate PSCells to the MN.

[0288] The systems and processes described above can be encoded in a signal-bearing medium, a computer-readable medium (such as a 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 can be analyzed in a computer system and used to generate a spectrum. If the method is performed by software, the software can reside in a memory resident on or connected to a storage device, synchronizer, communication interface, or in a non-volatile or volatile memory in communication with a transmitter. A circuit or electronic device designed to transmit data to another location. The memory can include an ordered list of executable instructions for implementing a logical function. The described logical functions or any system elements can be implemented by optical circuits, digital circuits, source code, analog circuits, analog sources (such as analog electrical, audio, or video signals), or a combination thereof. The software can be embodied in any computer-readable or signal-bearing medium for use by or in conjunction with an instruction-executable system, device, or apparatus. Such a system can include a computer-based system, a system containing a processor, or another system that can selectively obtain instructions from an instruction-executable system, device, or apparatus that can also execute instructions.

[0289] "Computer-readable medium," "machine-readable medium," "propagation signal" medium, and / or "signal-bearing medium" may include any apparatus that includes storage, communication, propagation, or transmission of software for use by or in connection with an instruction-executable system, apparatus, or device. A machine-readable medium may selectively 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 medium would include: an "electronic" electrical connection having one or more wires, a portable magnetic or optical disk, a volatile memory such as random access memory "RAM," a read-only memory "ROM," an erasable programmable read-only memory (EPROM or flash memory), or an optical fiber. A machine-readable medium may also include a tangible medium having software printed thereon, as the software may be stored electronically as an image or in another format (e.g., by optical scanning) and then compiled, and / or interpreted, or otherwise processed. The processed medium may then be stored in a computer and / or machine memory.

[0290] The illustrations of the embodiments described herein are intended to provide an overall understanding of the structures of the various embodiments. These illustrations are not intended to be a complete description of all elements and features of the devices and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those skilled in the art after reading this disclosure. Other embodiments may be utilized and derived from this disclosure, thereby allowing structural and logical substitutions and changes to be made without departing from the scope of this disclosure. In addition, these illustrations are merely representative and may not be drawn to scale. Certain proportions in the illustrations may be exaggerated, while other proportions may be reduced. Therefore, this disclosure and the accompanying drawings should be considered illustrative and not restrictive.

[0291] One or more embodiments of the present disclosure may be referred to herein, individually and / or collectively, as the term "invention," which is merely for convenience and is not intended to limit the scope of this application to any particular invention or inventive concept. In addition, although specific embodiments have been shown and described herein, it should be understood that any subsequent arrangement designed to achieve the same or similar purpose may replace the specific embodiments shown. The present disclosure is intended to cover any and all subsequent modifications or variations of the various embodiments. Combinations of the above-described embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art upon reading the specification.

[0292] The phrase "coupled" is defined to mean connected directly to or indirectly connected through one or more intermediate components. Such intermediate components may include hardware-based and software-based components. The arrangement and type of components may be varied without departing from the spirit or scope of the claims set forth herein. Additionally, different or fewer components may be provided.

[0293] The subject matter disclosed above is to be considered illustrative, not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the invention. Therefore, to the maximum extent permitted by law, the scope of the present invention is determined by the broadest permissible interpretation of the appended claims and their equivalents, and should not be constrained or limited by the foregoing detailed description. Although various embodiments of the present invention have been described, it will be apparent to those skilled in the art that more embodiments and implementations are possible within the scope of the present invention. Therefore, the present invention is not limited except in accordance with the appended claims and their equivalents.

Claims

1. A method for wireless communication, comprising: receiving a configuration message including a 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; sending a measurement report having L1 measurements for at least one of the LTM candidate cells; receiving a cell handover command to indicate a target LTM candidate cell from the LTM candidate cells; as well as An LTM cell handover is performed to the target LTM candidate cell.

2. The method according to claim 1, wherein The configuration for the LTM candidate cells includes at least one of the following: a candidate cell configuration list, a candidate cell group level configuration (CellGroupConfig) list, a candidate radio bearer configuration (RadioBearerConfig) list, or a candidate measurement configuration (MeasConfig) list.

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

4. The method according to claim 3, wherein: The reference index is used to reference a cell group level configuration indicated from the candidate cell group level configuration list, a radio bearer configuration indicated from the candidate radio bearer configuration list, a measurement configuration indicated from the candidate measurement configuration list, or a candidate cell configuration indicated from the candidate cell list.

5. The method according to claim 1, wherein The configuration for the LTM candidate cells includes a configuration group for each candidate cell, wherein each candidate cell in a group shares a common configuration or a reference configuration, and each candidate cell in a group has a delta configuration.

6. The method according to claim 5, wherein: The common configuration or reference configuration is referenced using a reference index to refer to a reference configuration from a pool of reference configurations.

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

8. The method according to claim 1, wherein The configuration for LTM candidate cells includes a common L1 measurement configuration pool.

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

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

11. The method according to claim 10, wherein: The information items in the information list are configured to associate RS resources with candidate cells, associate beam information with candidate cells, or associate TCI status information with candidate cells.

12. The method according to claim 10, wherein: The RS resources, beam information, or TCI status is configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmissions.

13. The method according to claim 10, wherein: The information list is combined with the candidate cell configuration list, or is configured within the candidate cell configuration.

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

15. The method according to claim 1, further comprising: Before receiving the cell switching command, downlink (DL) synchronization or uplink synchronization with a candidate cell is performed.

16. The method according to claim 1, further comprising: UL signaling is sent to the target LTM candidate cell to notify the UE of arriving at the target LTM candidate cell or completing LTM cell handover.

17. The method according to claim 16, wherein The UL signaling includes or indicates at least one of the following: the target LTM candidate cell identifier, the TCI status indication of the target LTM candidate cell, the beam / RS identifier of the target LTM candidate cell, or the activated / deactivated SCell identifier.

18. The method of claim 1, further comprising: When receiving a cell handover command, starting a first timer; Wherein, the first timer is stopped when the LTM cell switching is successfully performed.

19. The method according to claim 18, further comprising: Based on the expiration of the first timer, it is determined that the execution of the LTM cell handover has failed.

20. The method of claim 18, further comprising: When the cell handover command is received or when a failure in executing the LTM cell handover is detected, starting a second timer; Wherein, the second timer is stopped when the LTM cell handover is successfully performed.

21. The method according to claim 20, further comprising: If it is detected that the execution of the LTM cell handover fails and the second timer is running, the LTM cell handover execution is performed to another LTM candidate cell.

22. The method according to claim 21, further comprising: If the second timer expires, an RRC re-establishment process is triggered.

23. The method according to claim 1, wherein The state of the LTM candidate cell includes at least one of the following: a pre-configured state, a pre-configured but suspended state, an activated state, or a deactivated state.

24. The method according to claim 23, wherein For the preconfigured state, the UE stores the cell configuration but does not apply the cell configuration, and the UE performs L1 measurement on the cell. Further, for the preconfigured but suspended state, the UE stores the cell configuration, does not apply the cell configuration, and the UE suspends performing L1 measurement on the cell.

25. A method for wireless communication, comprising: sending 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 having L1 measurements for at least one of the LTM candidate cells; as well as A cell handover command is sent to indicate a target LTM candidate cell from the LTM candidate cells and trigger execution of an LTM cell handover to the target LTM candidate cell.

26. The method according to claim 25, wherein The configuration for the LTM candidate cells includes at least one of the following: a candidate cell configuration list, a candidate cell group level configuration (CellGroupConfig) list, a candidate radio bearer configuration (RadioBearerConfig) list, or a candidate measurement configuration (MeasConfig) list.

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

28. The method according to claim 27, wherein The reference index is used to reference a cell group level configuration indicated from the candidate cell group level configuration list, a radio bearer configuration indicated from the candidate radio bearer configuration list, a measurement configuration indicated from the candidate measurement configuration list, or a candidate cell configuration indicated from the candidate cell list.

29. The method according to claim 25, wherein The configuration for the LTM candidate cells includes a configuration group for each candidate cell, wherein each candidate cell in a group shares a common configuration or a reference configuration, and each candidate cell in a group has a delta configuration.

30. The method according to claim 29, wherein The common configuration or reference configuration is referenced using a reference index to refer to a reference configuration from a pool of reference configurations.

31. The method of claim 25, wherein: The configuration for LTM candidate cells includes a common L1 measurement configuration pool.

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

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

34. The method according to claim 33, wherein The information items in the information list are configured to associate RS resources with candidate cells, associate beam information with candidate cells, or associate TCI status information with candidate cells.

35. The method according to claim 34, wherein The RS resources, beam information, or TCI status is configured for uplink (UL) transmission only, downlink (DL) transmission only, or both UL and DL transmissions.

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

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

38. The method of claim 25, further comprising: Receive UL signaling from the target LTM candidate cell to notify the UE that it has arrived at the target LTM candidate cell or completed cell switching, wherein the UL signaling includes or indicates at least one of the following: the target LTM candidate cell identifier, the TCI status indication of the target LTM candidate cell, or the beam / RS identifier of the target LTM candidate cell, or the activated / deactivated SCell identifier.

39. A wireless communication device comprising a processor and a memory, wherein: The processor is configured to read code from the memory and implement the method according to any one of claims 1 to 38.

40. A computer program product comprising computer readable program medium code stored thereon, which, when executed by a processor, causes the processor to carry out the method according to any one of claims 1 to 38.

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