Mechanism for low-layer triggered mobility procedures

Abstract

A method for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure is provided. The method is implemented by a user equipment (UE) and includes receiving one or more radio resource control (RRC) messages from a source base station. The method includes being configured with one or more LTM commands contained in the one or more RRC messages, wherein a total number of the one or more LTM commands does not exceed a predetermined number, the one or more LTM commands comprise at least one of a first type LTM command and a second type LTM command, the first type LTM command comprises a first target cell configuration of a first target cell and a first execution condition, and the second type LTM command comprises a second target cell configuration of a second target cell and does not have any execution condition.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 570,303, filed March 27, 2024, entitled “Mechanisms for Conditional Lower Layer Triggered Mobility,” and U.S. Application No. 19 / 090,627, filed March 26, 2025, entitled “Mechanisms for Lower Layer Triggered Mobility Procedure,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to wireless communications. More specifically, aspects of this disclosure relate to mechanisms for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) processes. Background Technology

[0004] Unless otherwise stated herein, the methods described in this section are not prior art to the following claims and are not acknowledged as prior art by virtue of their inclusion in this section.

[0005] A traditional handover (HO) procedure (i.e., Layer 3 / L3 mobility) is introduced to switch a User Equipment (UE) from a source serving cell to a target serving cell, for example, when the UE moves from the coverage area of ​​the source serving cell to the coverage area of ​​the target serving cell. The decision to perform a traditional HO is made by the current serving gNB (or source gNB) of the current serving cell (or source cell) based on measurements reported by the UE. When the source gNB determines that a handover is needed, it sends an HO request message to the target gNB to request HO admission. When the target gNB accepts the HO request, it replies with an HO request acknowledgement message containing the necessary information / configuration for the UE to perform the traditional HO procedure to synchronize with the target gNB's target cell. Upon receiving the HO request acknowledgement message, the source gNB sends an HO command (or an RRC Reconfiguration message with synchronization for the target cell), which includes at least the target cell configuration to instruct the UE to perform the traditional HO procedure to the target cell. Therefore, the traditional HO (Hosting On) procedure is triggered by Layer 3 (L3) measurements and completed by instructing the UE to hand over from the source cell to the target cell via RRC signaling. However, due to faster signal fading or higher UE mobility, the serving source gNB may not always receive measurement reports from the UE, or may fail to successfully send the handover (HO) command to the UE. This results in a higher HO failure rate. Furthermore, the traditional HO procedure involves a complete L2 (and L1) reset, leading to longer latency, greater overhead, and longer downtime compared to beam-switching mobility.

[0006] To reduce latency, overhead, and downtime, LTM (Low-Terminal Measuring) was introduced in 3GPP Release 18 to improve HO latency and downtime compared to traditional HO procedures. By definition, LTM is a cell change process triggered by the network via a Medium Access Control (MAC) Control Element (CE) based on L1 measurements. It should be noted that in the 5G protocol stack, L1 is the Physical Layer, and L3 is the Radio Resource Control (RRC) layer. L2 includes the MAC, Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP) layers. As described in TS 38.300 of Release 18, LTM is the process by which the gNB receives an L1 measurement report from the UE and, based on this, changes the UE's serving cell by sending a cell change command signaled by the MAC CE. The cell change command instructs the gNB to provide the LTM candidate configuration previously prepared and provided to the UE via RRC signaling. The UE then switches to the target configuration based on the cell change command.

[0007] Figure 1 Example scenario 100 of the signaling procedure for LTM described in TS 38.300 of Release 18 is shown. Scenario 100 involves the UE and a next-generation NodeB (gNB) (e.g., a base station (BS) or transmission and reception point (TRP)), which can be part of a wireless network (e.g., a 5G NR network, a 5G network, or a 6G network). Figure 1 As shown, when the UE is in the RRC connected (RRC_CONNECTED) state, the signaling procedure for LTM is executed.

[0008] In step 101, the UE sends a Measurement Report message to the gNB. Upon receiving the Measurement Report message, the gNB decides to configure LTM and initiates LTM candidate preparation.

[0009] In step 102, the gNB sends an RRC Reconfiguration message to the UE, which includes the configuration of one or more LTM candidate cells.

[0010] In step 103, the UE stores the configuration of the LTM candidate cell and sends an RRC reconfiguration complete message to the gNB.

[0011] In step 104a, the UE may perform downlink (DL) synchronization with the candidate cell before receiving the LTM cell change command.

[0012] In step 104b, the UE may perform uplink (UL) synchronization and timing advance (TA) acquisition with the candidate cell before receiving the LTM cell change command. If UE-based TA measurement is configured (as introduced in TS 38.331 of Release 18), the UE uses the UE-based TA measurement to acquire the TA value of the candidate cell. Alternatively, the UE performs early TA acquisition with the candidate cell at the request of the gNB before receiving the LTM cell change command. This is accomplished via contention-free random access (CFRA) triggered by a Physical Downlink Control Channel (PDCCH) order from the source cell, after which the UE sends a preamble toward the indicated candidate cell. To minimize data interruption to the source cell due to CFRA toward the candidate cell, the UE does not receive a random access response from the gNB for acquiring the TA value, and the TA value of the candidate cell is indicated in the LTM cell change command. The UE does not maintain a TA timer for candidate cells, but relies on the network implementation to ensure the validity of the TA.

[0013] In step 105, the UE performs L1 measurements on the configured LTM candidate cells and sends an L1 measurement report to the gNB. L1 measurements should be performed whenever RRC reconfiguration (in step 102) is applicable. Upon receiving the L1 measurement report, the gNB can decide to perform an LTM cell change to the target cell.

[0014] In step 106, the gNB decides to perform a cell change to the target cell and sends a MAC control element (MAC-CE) that triggers the cell change by including a candidate configuration index of the target cell. In response to the LTM cell change being triggered, the UE switches to the target cell and applies the configuration indicated by the candidate configuration index.

[0015] In step 107, when the UE does not have a valid TA for the target cell as specified in TS 38.321 of Release 18, the UE performs a random access procedure toward the target cell.

[0016] In step 108, the UE completes the LTM cell change process by sending an RRCReconfigurationComplete message to the target cell. When the UE executes the RA procedure in step 107 and the random access procedure is successfully completed, the UE considers the LTM cell change process to be successfully completed. For RACH-less LTM, the UE considers the LTM cell change process to be successfully completed when it determines that the gNB has successfully received its first UL data. It should be noted that RACH-less LTM is an LTM cell change process in which the UE skips the random access procedure.

[0017] In the Release 18 design, there is still room for further improvement in LTM. RP-234036 approved a new work item for further enhancing New Radio (NR) mobility. One of the goals of this new work item is to support Conditional LTM by following the concept of Conditional Handover (CHO) to achieve greater robustness. As described in TS 38.300 v16.15.0, CHO is defined as a handover performed by the UE when one or more handover execution conditions are met, without prior signaling exchange with the source cell. By introducing the Conditional LTM mechanism, UE mobility can simultaneously benefit from high robustness and short downtime.

[0018] However, many details of the overall conditional LTM design have not yet been determined, such as: the relevant configuration design to support the conditional LTM design; the means to perform early UL synchronization (or obtain effective timing advance / TA value) to the target candidate cell in the conditional LTM design, considering that the LTM cell change command MAC CE (as specified in TS 38.321 of Release 18) may need to be modified to support conditional LTM; the corresponding UE behaviors for performing the conditional LTM process, etc.

[0019] Therefore, how to design conditional LTM processes has become an important topic. Thus, appropriate solutions are needed to address this issue. Summary of the Invention

[0020] The following summary is illustrative only and is not intended to be limiting in any way. That is, it is provided to introduce the concepts, key points, benefits, and advantages of the novel and non-obvious techniques described herein. Selected, but not all, embodiments are further described in the detailed description below. Therefore, the following summary is neither intended to identify the key features of the claimed subject matter nor to define the scope of the claimed subject matter.

[0021] Therefore, this disclosure provides mechanisms for triggering mobility (LTM) procedures at conditional layer 1 / layer 2 (L1 / L2). The primary objective of this disclosure is to support conditional LTM procedures, including UE-assisted information to support network decisions regarding conditional LTM, detailed design of conditional LTM configurations, UE behavior upon receiving or releasing conditional LTM configurations, UE behavior under conditions where conditional LTM configurations coexist with conventional LTM configurations or CHO commands, and a modified LTM cell change command (MAC CE) providing a TA value for early UL synchronization to a target candidate cell.

[0022] In an exemplary embodiment, a method is provided for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure. The method is implemented by a user equipment (UE) and includes receiving one or more Radio Resource Control (RRC) messages from a source base station. The method includes one or more LTM commands configured to be included in the one or more RRC messages, wherein the total number of the one or more LTM commands does not exceed a predetermined number. The one or more LTM commands include at least one of a first type of LTM command and a second type of LTM command, wherein the first type of LTM command includes a first target cell configuration of a first target cell and a first execution condition, and the second type of LTM command includes a second target cell configuration of a second target cell and does not have any execution conditions.

[0023] In an exemplary embodiment, an apparatus is provided for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) process. The apparatus includes a transceiver and a processor. The transceiver wirelessly communicates with at least one network node during operation. The processor is communicatively coupled to the transceiver such that, during operation, the processor performs operations including: receiving one or more Radio Resource Control (RRC) messages from a source base station; and being configured with one or more LTM commands contained in the one or more RRC messages, wherein the total number of the one or more LTM commands does not exceed a predetermined number. The one or more LTM commands include at least one of a first type of LTM command and a second type of LTM command, the first type of LTM command including a first target cell configuration of a first target cell and a first execution condition, and the second type of LTM command including a second target cell configuration of a second target cell and without any execution condition.

[0024] In an exemplary embodiment, a method is provided for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) process. The method is implemented by a source base station (BS) and includes sending one or more Radio Resource Control (RRC) messages to a User Equipment (UE), wherein the UE is configured with one or more LTM commands contained in the one or more RRC messages, the total number of the one or more LTM commands not exceeding a predetermined number, the one or more LTM commands including at least one of a first type of LTM command and a second type of LTM command, the first type of LTM command including a first target cell configuration of a first target cell and a first execution condition, and the second type of LTM command including a second target cell configuration of a second target cell and without any execution condition. Attached Figure Description

[0025] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this disclosure. The drawings illustrate implementations of this disclosure and, together with the specification, serve to explain the principles of this disclosure. It should be understood that the drawings are not necessarily drawn to scale, as in actual implementations, some components may not be shown at their scale for clarity in illustrating the concepts of this disclosure.

[0026] Figure 1 An example scenario of the signaling procedure used for LTM is shown.

[0027] Figure 2 A conditional LTM procedure according to an implementation of this disclosure is shown.

[0028] Figure 3 The signaling process for transmitting UE auxiliary information according to the implementation of this disclosure is shown.

[0029] Figure 4 A configuration structure for an LTM configuration containing one or more LTM candidate configurations, according to an implementation of this disclosure, is shown.

[0030] Figure 5 An early UL TA acquisition process triggered by a PDCCH instruction according to an implementation of this disclosure is shown.

[0031] Figure 6 An LTM cell change command MAC CE according to an implementation of this disclosure is shown.

[0032] Figure 7 This is a block diagram of an example communication system implemented according to this disclosure.

[0033] Figure 8 This is a flowchart of an example process implemented according to this disclosure. Detailed Implementation

[0034] The following description contains specific information relating to the exemplary implementations in this disclosure. The accompanying drawings and detailed descriptions are for exemplary implementations only. However, this disclosure is not limited to these exemplary implementations. Other variations and implementations of this disclosure will occur to those skilled in the art. Unless otherwise stated, similar or corresponding elements between the drawings are indicated by similar or corresponding reference numerals. Furthermore, the drawings and illustrations in this disclosure are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0035] For the purposes of consistency and ease of understanding, similar features in the example figures can be identified by the same reference numerals (although not shown in some examples). However, features in different implementations may differ in other respects, and therefore should not be narrowly limited to what is shown in the figures.

[0036] The specification uses the phrases "in one implementation" or "in some implementations," each of which can refer to one or more of the same or different implementations. The term "coupling" is defined as a connection, whether direct or indirect through intermediate components, and is not necessarily limited to a physical connection. When the term "comprising" is used, it means "including but not limited to"; specifically, it indicates an open inclusion or membership in the described combination, group, series, and equivalents. The statement "at least one of A, B, and C" or "at least one of A, B, and C" means "only A, or only B, or only C, or any combination of A, B, and C."

[0037] Furthermore, for illustrative purposes rather than limiting, specific details such as functional entities, technologies, protocols, and standards are described to provide an understanding of the technologies being described. In other examples, detailed descriptions of well-known methods, technologies, systems, architectures, etc., are omitted to avoid obscuring the description with unnecessary detail.

[0038] Those skilled in the art will readily recognize that any network function or algorithm described herein can be implemented in hardware, software, or a combination of software and hardware. The described functions may correspond to modules, which may be software, hardware, firmware, or any combination thereof. Software implementation may include computer-executable instructions stored on a computer-readable medium such as memory or other types of storage devices. For example, one or more microprocessors or general-purpose computers with communication processing capabilities may be programmed with corresponding executable instructions to perform the described network functions or algorithms. The microprocessor or general-purpose computer may be formed from an application-specific integrated circuit (ASIC), a programmable logic array, and / or utilize one or more digital signal processors (DSPs). Although some of the example implementations described herein are directed to software installed and executed on computer hardware, alternative example implementations, implemented in firmware or in hardware or a combination of hardware and software, fall entirely within the scope of this disclosure.

[0039] Computer-readable media include, but are not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM), magnetic tape cassettes, magnetic tapes, disk storage devices, or any other equivalent medium capable of storing computer-readable instructions.

[0040] Wireless communication network architectures (e.g., Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, LTE-Advanced Pro systems, 5G New Radio (NR) Radio Access Networks (RANs), or 6G NR RANs) typically include at least one base station (BS), at least one user equipment (UE), and one or more optional network elements providing connectivity to the network. The UE communicates with the network (e.g., Core Network (CN), Evolved Packet Core (EPC) network, Evolved Universal Terrestrial Radio Access Network (E-UTRAN), 5G Core Network (5GC), or the Internet) through the RAN established by one or more BSs.

[0041] It should be noted that in this disclosure, the UE may include, but is not limited to, a mobile station, mobile terminal or device, or a user communication radio terminal. For example, the UE may be a portable wireless device, including but not limited to mobile phones, tablets, wearable devices, sensors, vehicles, or personal digital assistants (PDAs) with wireless communication capabilities. The UE is configured to receive and transmit signals to one or more cells in the radio access network via an air interface.

[0042] The BS can be configured to provide communication services based on at least one of the following radio access technologies (RATs): Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile Communications (GSM, commonly referred to as 2G), GSM EDGE Radio Access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, commonly referred to as 3G) based on Wideband-Code Division Multiple Access (W-CDMA), High-Speed ​​Packet Access (HSPA), LTE, LTE-A, eLTE (evolved LTE, such as LTE connected to 5GC), NR (commonly referred to as 5G), 6G, and / or LTE-A Pro. However, the scope of this disclosure should not be limited to the protocols described above.

[0043] A BS may include, but is not limited to: Node B (NB) in UMTS, Evolved Node B (eNB) in LTE or LTE-A, Radio Network Controller (RNC) in UMTS, Base Station Controller (BSC) in GSM / GERAN, ng-eNB in ​​an Evolved Universal Terrestrial Radio Access (E-UTRA) BS connected to 5GC, next-generation Node B (gNB) in 5G-RAN, and any other device capable of controlling wireless communication within the cell and managing radio resources. A BS can provide services to one or more UEs through a radio interface.

[0044] A Base Station (BS) is operable to provide radio coverage for a specific geographic area using multiple cells forming a radio access network. The BS supports cell operation. Each cell is operable to serve at least one UE within its radio coverage area. More specifically, each cell (often referred to as the serving cell) serves one or more UEs within its radio coverage area (e.g., each cell schedules downlink and optional uplink resources for at least one UE within its radio coverage area for downlink and optional uplink packet transmissions). The BS can communicate with one or more UEs in the wireless communication system through these multiple cells. Cells can allocate sidelink (SL) resources to support Proximity Service (ProSe) or Vehicle to Everything (V2X) services. Each cell may have overlapping coverage areas with other cells.

[0045] As mentioned above, the NR frame structure is designed to support flexible configurations to accommodate various next-generation (e.g., 5G) communication requirements, such as Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC), while simultaneously meeting high reliability, high data rate, and low latency requirements. Orthogonal Frequency-Division Multiplexing (OFDM) technology, agreed upon in the 3rd Generation Partnership Project (3GPP), serves as the basis for the NR waveform. A scalable OFDM parameter set (numerology) can also be used, such as adaptive subcarrier spacing, channel bandwidth, and cyclic prefix (CP). Furthermore, two coding schemes are considered for NR: (1) Low-Density Parity-Check (LDPC) codes and (2) Polar codes. The coding scheme can be configured adaptively based on channel conditions and / or service applications.

[0046] Furthermore, considering that the transmission time interval (TX) of a single NR frame should include at least downlink (DL) transmission data, guard interval, and uplink (UL) transmission data, the corresponding portions of the DL transmission data, guard interval, and UL transmission data should also be configurable, for example, based on NR network dynamics. Additionally, SL resources can also be provided in the NR frame to support ProSe or V2X services.

[0047] Furthermore, the terms "system" and "network" are used interchangeably in this document. The term "and / or" is used only to describe the relationships between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates an "or" relationship between the preceding and following related objects.

[0048] Signaling procedures for conditional LTM

[0049] Figure 2 A conditional LTM procedure according to one implementation of this disclosure is shown. It should be noted that... Figure 2 One or more steps in the process may or may not be performed. For example, the RACH procedure in step 207 may not be performed when UL synchronization in step 204b is completed. Furthermore, the order of the steps is not necessarily mandatory. For example, the UE may begin evaluating the (configured) conditional LTM conditions before sending the RRC Reconfiguration Complete message in step 204.

[0050] In step 201, for a UE in the RRC_CONNECTED state, the serving gNB can configure the UE's measurement procedure, for example, by providing an L1 measurement configuration or an L3 measurement configuration, and the UE can report measurement results based on the L1 or L3 measurement configuration. For a specific target candidate cell, an L1 or L3 measurement configuration can be provided for measurements based on the Channel State Information Reference Signal (CRI-RS) or measurements based on the Synchronization Signal Block (SSB). Based on the received measurement configuration, the UE can periodically report measurement results to the serving gNB, or it can report measurement results via event triggering.

[0051] In step 202, the serving gNB may, for example, determine whether to use conditional LTM based on measurements received from the UE, UE speed, or current operating frequency. In one implementation, the serving gNB may be configured to allow the UE to provide auxiliary information for determining whether conditional LTM is required for UE mobility (or cell change procedures). For example, auxiliary information may include UE speed, UE mobility status, UE location, or UE trajectory, but this disclosure is not limited thereto. In another implementation, the UE may provide its preference regarding whether to use conditional LTM. The serving gNB may make a decision regarding the use of conditional LTM based on the auxiliary information provided by the UE.

[0052] In step 203, the serving gNB may send an RRC Reconfiguration message to the UE, which includes at least an LTM candidate configuration and a conditional LTM execution condition. It should be noted that the conditional LTM candidate configuration includes at least one LTM candidate configuration (for the target candidate cell) and at least one associated conditional LTM execution condition. It should be noted that in this disclosure, "candidate target cell configuration for conditional LTM," "candidate target cell configuration," "conditional LTM command," and "LTM candidate configuration" are interchangeable. The conditional LTM candidate configuration can also be identified by a (conditional) LTM identifier (ID). The (conditional) LTM ID may be assigned by the (source) serving gNB. The serving gNB may release the conditional LTM candidate configuration by indicating its associated (conditional) LTM ID in network (NW) signaling. Furthermore, in this disclosure, "conditional LTM execution condition" and "execution condition" are interchangeable. The execution condition may be associated with a measurement ID (e.g., measID) or an associated measurement reporting configuration (e.g., a measurement configuration with a ReportConfig ID associated with said measurement ID). The associated measurement reporting configuration can be provided for SSB-based L1 measurements, CRI-RS-based L1 measurements, SSB-based L3 measurements, or CRI-RS-based L3 measurements. The associated measurement reporting configuration can be indicated for conditional LTM. When the associated measurement reporting configuration is indicated for conditional LTM (e.g., specific information elements exist in the measurement reporting configuration), the UE can evaluate the configured measurement events without reporting any measurement results to the serving gNB. For example, the UE can perform an L1-based execution condition evaluation based on the associated reporting configuration associated with a target candidate cell. Similarly, the UE can perform an L3-based execution condition evaluation based on the associated reporting configuration associated with a target candidate cell. In one implementation, whether to send measurement results associated with satisfied execution conditions to the serving gNB can be configured by the serving gNB. In one implementation, the initial state of the execution conditions associated with the LTM candidate configuration can be disabled / inactive or enabled / active. The initial state of the execution condition associated with the LTM candidate configuration can be configured by the serving gNB. In one implementation, the default state of the execution condition associated with the LTM candidate configuration can be disabled or inactive. In another implementation, the default state of the execution condition associated with the LTM candidate configuration can be enabled or active. In yet another implementation, the serving gNB can change the state of the execution condition associated with the LTM candidate configuration (e.g., via RRC signaling, MAC CE, or DCI).For example, the serving gNB can use NW commands (e.g., via RRC signaling, MAC CE, or DCI) to enable the execution conditions associated with LTM candidate configuration #1, allowing the UE to begin evaluating the execution conditions associated with LTM candidate configuration #1. Similarly, the serving gNB can use NW commands (e.g., via RRC signaling, MAC CE, or DCI) to disable the execution conditions associated with LTM candidate configuration #2, allowing the UE to stop evaluating the execution conditions associated with LTM candidate configuration #2.

[0053] In step 204a, the UE may perform an (early) downlink (DL) synchronization procedure with the target candidate cell before applying the LTM candidate configuration of the target candidate cell. It should be noted that the LTM candidate configuration can be applied because the conditional LTM execution conditions associated with it are met. Whether the UE can perform the (early) DL synchronization procedure with the target candidate cell before applying the LTM candidate configuration of the target candidate cell may depend on network configuration or control signaling. In one implementation, the RRC Reconfiguration message or the conditional LTM candidate configuration may include an indication (or related information) indicating whether an (early) DL synchronization procedure is required.

[0054] In step 204b, the UE may perform an (early) uplink (UL) synchronization procedure with the target candidate cell before applying the LTM candidate configuration of the target candidate cell. It should be noted that the LTM candidate configuration can be applied because the conditional LTM execution conditions associated with it are met. Whether the UE can perform the (early) UL synchronization procedure with the target candidate cell before applying the LTM candidate configuration may depend on network configuration or NW control signaling. To perform the (early) UL synchronization procedure, the serving gNB may provide uplink resources (e.g., RA resources or PDCCH instructions) for the UE to send a preamble at least in advance before applying the conditional LTM configuration associated with the target candidate cell. In one implementation, in the case of performing an early UL synchronization procedure for conditional LTM, the UE may receive a random access response (RAR) (e.g., including TA commands) from the target candidate cell after sending the preamble. In this scenario, the current serving cell (or its base station) can provide additional measurement gap configurations for the UE to send a preamble to the target candidate cell and / or receive the corresponding RAR from the target candidate cell. In another implementation, when performing an early UL synchronization procedure for conditional LTM, after sending the preamble to the target candidate cell, the UE can receive a modified LTM Cell Change Command MAC CE (or RAR, or a new MAC CE) from the current serving cell (or its base station). The received modified LTM Cell Change Command MAC (or RAR, or a new MAC CE) may include a TA command (or TA-related information) for the target candidate cell, which can be applied to connections to the target candidate cell.

[0055] In step 205, the UE may begin evaluating conditional LTM execution conditions after receiving a conditional LTM candidate configuration. In one implementation, the UE may begin evaluating an execution condition when it is enabled, activated, valid, or configured. Once an execution switch occurs (e.g., executing legacy LTM, executing conditional LTM, executing legacy HO, or executing CHO), the UE may stop evaluating conditional LTM execution conditions. In one implementation, the UE may stop evaluating an execution condition when it is disabled, inactive, invalid, or deconfigured. In another implementation, whether the UE can begin evaluating conditional LTM execution conditions associated with the LTM candidate configuration may depend on its current state (e.g., enabled or disabled).

[0056] In step 206, after receiving the conditional LTM candidate configuration, the UE can maintain its connection with the current serving gNB and begin evaluating conditional LTM execution conditions for the target candidate cell associated with the received conditional LTM candidate configuration. When at least one target candidate cell meets the corresponding conditional LTM execution conditions, the UE can detach from the current serving gNB, trigger an LTM cell change process, and / or apply the stored LTM candidate configuration to the selected target candidate cell. In one implementation, when multiple target candidate cells meet the corresponding conditional LTM execution conditions, the UE can randomly select a target candidate cell and trigger an LTM cell change process by applying the stored LTM candidate configuration of the selected target candidate cell.

[0057] In step 207, when the UE does not have a valid TA for the target candidate cell or the early UL synchronization process has not been successfully completed, the UE may perform an RA process toward the target cell. The UE may have a valid TA provided by the serving gNB, or it may calculate or measure the valid TA itself. The serving gNB may instruct the UE to calculate or measure the valid TA for the target candidate cell itself.

[0058] In step 208, the UE can complete the conditional LTM procedure by sending an RRC Reconfiguration Complete message to the selected target candidate cell (or its associated gNB). After the UE has performed the RA procedure in step 207, the UE can consider the conditional LTM procedure to have been successfully completed when the random access procedure completes successfully. The RRC Reconfiguration Complete message may include an information element field indicating the LTM ID of the selected conditional LTM candidate configuration applied by the UE when performing conditional LTM. When the UE has a valid TA for the selected target candidate cell and does not need to perform the RA procedure, the UE can consider the conditional LTM procedure to have been successfully completed when the UE determines that the network (or the new serving gNB) has successfully received the UE's first UL data.

[0059] In one implementation, when subsequent conditional LTM is configured, the UE begins to evaluate the execution conditions (if any) of the conditional LTM candidate configurations associated with the new serving cell.

[0060] In one implementation, when the UE performs a conditional LTM (e.g., applies the LTM candidate configuration when the execution conditions associated with it are met) and / or initiates an RA procedure to the target candidate cell of the LTM candidate configuration, the UE may stop monitoring the source cell (or the current serving cell) of the source base station. In another implementation, when a cell change procedure is triggered (e.g., because the UE performed a conditional LTM), the UE may stop monitoring the source cell (or the current serving cell) of the source base station.

[0061] UE auxiliary information for conditional LTM

[0062] Figure 3 The signaling process for sending UE assistance information according to one implementation of this disclosure is illustrated. In step S305, when the network (NW) needs UE assistance information, the NW can initiate the process for a UE in the RRC_CONNECTED state. That is, the NW can send an RRC reconfiguration message (e.g., an RRCReconfiguration message) to configure the UE to provide specific assistance information, and the UE can send the relevant assistance information in a UE assistance information message (e.g., a UEAssistanceInformation message) based on this configuration in step S310.

[0063] In one implementation, the NW can configure the UE to provide the NW with its conditional LTM-related auxiliary information. For example, when a UE reports its support for conditional LTM, the UE can be considered a UE with conditional LTM capability. Then, the NW can configure the conditional LTM-capable UE to provide its conditional LTM-related auxiliary information. The NW can... Figure 2 Before step 202, refer to the conditional LTM related auxiliary information provided by the UE.

[0064] In one implementation, the UE may provide its current speed (e.g., based on UE estimates or GPS information) in the UE Auxiliary Information message. In another implementation, the UE may provide its mobility state (e.g., low mobility, medium mobility, or high mobility) in the UE Auxiliary Information message. The definitions of different mobility states may follow the definitions specified in TS 38.304. The definitions of different mobility states may be configured by the NW. In one implementation, the UE may provide its trajectory-related information in the UE Auxiliary Information message. In another implementation, the UE may provide its location-related information in the UE Auxiliary Information message. In yet another implementation, the UE may provide its preference for whether to use Conditional LTM in the UE Auxiliary Information message. For example, if mobility robustness or service interruption may be important to the UE, the UE may set its preference to "use Conditional LTM," etc. For example, if power saving may be important to the UE or the UE's capabilities are limited (e.g., due to overheating issues), the UE may set its preference to "do not use Conditional LTM," etc.

[0065] In one implementation, timer T1 is started when UE assistance information including conditional LTM-related assistance information is transmitted. When timer T1 expires, the UE may be allowed to transmit another UE assistance information including conditional LTM-related assistance information. In another implementation, the UE is allowed to transmit a UE assistance information message including conditional LTM-related assistance information when timer T1 is running and the current conditional LTM-related assistance information differs from the information indicated in the previous transmission (or previously transmitted) of the UE assistance information message. The value of timer T1 can be a configured value or a predefined value.

[0066] Design of Conditional LTM Candidate Configurations

[0067] In one implementation, a conditional LTM candidate configuration may include an LTM candidate configuration (for the target candidate cell), an associated conditional LTM execution condition, and an associated LTM candidate ID. The associated conditional LTM execution condition may consist of one or more trigger conditions. Trigger conditions can be identified by a measurement ID (e.g., measID), which is used to identify the measurement configuration. It should be noted that the measurement configuration may be associated with a reporting configuration (or its reporting configuration ID) and / or a measurement object configuration (or its measurement object ID). It should also be noted that the reporting configuration may be configured for L1 or L3 measurements. In one implementation, a conditional LTM execution condition is considered satisfied when one (or all) trigger conditions are satisfied. In one implementation, for a conditional LTM candidate configuration, the trigger condition may be associated with a reporting configuration, which is associated with the measurement ID configured in the conditional LTM candidate configuration. In one implementation, the reporting configuration may indicate that its reporting type is "conditional LTM trigger condition," etc., which is used for conditional LTM. When a measurement event of a reporting configuration with a reporting type such as "Conditional LTM Trigger Condition" is met (e.g., based on corresponding parameters), the UE may not report the measurement result to the NW. In one implementation, the reporting configuration may indicate that its reporting type is "Conditional LTM Trigger Condition" or similar, which is used for Conditional LTM. When a measurement event of a reporting configuration with a reporting type such as "Conditional LTM Trigger Condition" is met (e.g., based on corresponding parameters), the UE may report the measurement result to the NW based on the received configuration or control signaling.

[0068] In one implementation, an LTM candidate configuration can be configured to be associated with a measurement configuration (or its measurement ID), and the measurement configuration can be associated with a reporting configuration (or its reporting configuration ID). When the reporting type (or field) of the reporting configuration is "Conditional LTM," the UE can apply the LTM candidate configuration when the execution conditions based on the measurement configuration (or associated reporting configuration) are met. When the reporting type (or field) of the reporting configuration is not "Conditional LTM," the UE can report measurement results based on the measurement configuration (or associated reporting configuration) and does not apply the LTM candidate configuration. In one implementation, the NW can change, update, or modify the LTM candidate configuration from traditional LTM to conditional LTM, or from conditional LTM to traditional LTM, based on RRC signaling, MAC CE, or DCI. It should be noted that, as introduced in 3GPP Release 18, traditional LTM is a cell change process triggered by the network via a Medium Access Control (MAC) control element (CE) based on L1 measurements. Therefore, traditional LTM does not have execution conditions. For example, when a UE receives an LTM candidate configuration, and this candidate configuration is associated with a reporting configuration of type "Conditional LTM," and the UE receives RRC signaling, MAC CE, or DCI for changing or disabling this reporting type, the UE may choose not to execute Conditional LTM for that candidate configuration.

[0069] In some implementations, the LTM candidate configuration for conventional LTM can be associated with the configuration of the Synchronization Signal and Physical Broadcast Channel (SS / PBCH) block for L1 measurement and the channel state information (CSI) reporting configuration.

[0070] In one implementation, the LTM candidate configuration for conventional LTM can be associated with the configuration of CSI reference signals (CSI-RSs) for L1 measurement and the associated configuration of CSI reporting configuration.

[0071] In some implementations, the LTM candidate configuration for traditional LTM can be associated with the configuration of the SS / PBCH block or CSI-RS for L3 measurements and the associated configuration of the L3 reporting configuration.

[0072] In one implementation, an LTM candidate configuration may contain a field indicating whether the LTM candidate configuration is for conventional LTM or conditional LTM. In one example, when the field is set to a specific value (e.g., true) or present, the LTM candidate configuration may be configured for conditional LTM. When the field is set to another specific value (e.g., false) or absent, the LTM candidate configuration may be configured for conventional LTM. In another example, when the field is set to a specific value (e.g., false) or absent, the LTM candidate configuration may be configured for conditional LTM. When the field is set to another specific value (e.g., true) or present, the LTM candidate configuration may be configured for conventional LTM. In yet another example, the field indicates whether the LTM candidate configuration is for conventional LTM or conditional LTM. In one implementation, an LTM candidate configuration for conventional LTM associated with the configuration of the SS / PBCH block or CSI-RS used for L1 measurements and the associated configuration of the CSI reporting configuration may be considered to have conventional LTM as the default state. The NW can use RRC signaling, MAC CE, or DCI to change, update, or modify this state to conditional LTM. In another implementation, an LTM candidate configuration for legacy LTM associated with the configuration of the SS / PBCH block or CSI-RS used for L1 measurements and the associated configuration of the CSI reporting configuration can be considered as having conditional LTM as the default state. The NW can use RRC signaling, MAC CE, or DCI to change, update, or modify this state to legacy LTM. It should be noted that when the LTM candidate configuration is considered legacy LTM, the UE can report L1 measurement results to the NW and wait for the NW command to hand over to another cell. When the LTM candidate configuration is considered conditional LTM, the UE may not report L1 measurement results to the NW. Instead, the UE can apply the LTM candidate configuration when the associated execution conditions are met. The associated execution conditions can be determined based on the configuration of the received CSI reporting configuration or based on another configuration (e.g., another measurement configuration or another reporting configuration). When an execution condition is enabled, activated, valid, or configured, the UE can begin evaluating the conditional LTM execution conditions associated with the LTM candidate configuration and determine whether the execution condition is met.

[0073] In some implementations, LTM candidate configurations can be configured with L1 (or L3) measurement events or reporting for conventional LTM, and L1 (or L3) measurement events or reporting for conditional LTM. The type used for conventional LTM or conditional LTM (L1, L3, or both) can depend on the NW's decision and / or the UE's capabilities. For example, when a UE reports its L1 measurement capabilities for conditional LTM, the NW can send an LTM candidate configuration associated with an L1 measurement event for conditional LTM. In another example, when a UE reports its L3 measurement capabilities for conditional LTM, the NW can send an LTM candidate configuration associated with an L3 measurement event for conditional LTM.

[0074] In one implementation, an LTM candidate configuration may be associated with a first reporting configuration for conditional LTM and / or with a second reporting configuration for conventional LTM. When a first reporting configuration exists, the LTM candidate configuration may be applied when the execution conditions associated with the first reporting configuration are met (or satisfied). It should be noted that when an execution condition is enabled, activated, valid, or configured, the UE may begin evaluating the conditional LTM execution conditions associated with the LTM candidate configuration and determine whether the execution conditions are met (or satisfied). When a second reporting configuration exists, the UE may report measurement results to the NW.

[0075] Figure 4 The diagram illustrates a configuration structure for an LTM configuration that includes one or more LTM candidate configurations, according to one implementation of this disclosure. The LTM configuration can be a list containing one or more LTM candidate configurations. For example, such as... Figure 4 As shown, an LTM configuration includes K LTM candidate configurations. A UE can report the maximum number of LTM candidate configurations it can support within an LTM configuration. Each LTM candidate configuration can be associated with a first reporting configuration for conditional LTM and / or a second reporting configuration for legacy LTM. For example, LTM candidate configuration #1 associated with the first reporting configuration #1 can be considered as conditional LTM. In another example, LTM candidate configuration #2 associated with the second reporting configuration #2 can be considered as legacy LTM.

[0076] In one implementation, when both a first reporting configuration and a second reporting configuration exist, the UE can apply both reporting configurations. For example, when the relevant execution conditions associated with the first reporting configuration are met (or satisfied), the UE can apply the associated LTM candidate configuration, and the UE can send measurement results based on the second reporting configuration. In another implementation, when both a first reporting configuration and a second reporting configuration exist, the UE can apply the first reporting configuration for conditional LTM and can suspend or release the second reporting configuration for conventional LTM. In yet another implementation, when both a first reporting configuration and a second reporting configuration exist, the UE can apply the second reporting configuration for conventional LTM and can suspend or release the first reporting configuration for conditional LTM. In yet another implementation, when both a first reporting configuration and a second reporting configuration exist, the NW can (e.g., via RRC signaling, MAC CE, or DCI) indicate to the UE which reporting configuration to use. In yet another implementation, the first reporting configuration and the second reporting configuration are not allowed to exist simultaneously. In other words, when an LTM candidate configuration is used for conditional LTM, only the first reporting configuration may exist. When an LTM candidate configuration is used for traditional LTM, only the second reporting configuration may exist. It should be noted that the first reporting configuration can be an L1-based reporting configuration (e.g., a CSI reporting configuration) or an L3-based reporting configuration (e.g., a reporting configuration with a reporting configuration ID). It should also be noted that the second reporting configuration can be an L1-based reporting configuration (e.g., a CSI reporting configuration) or an L3-based reporting configuration (e.g., a reporting configuration with a reporting configuration ID).

[0077] In one implementation, for each (conditional) LTM ID, when a conditional LTM-related indication is received from a lower layer (e.g., the physical (PHY) layer or MAC layer), indicating that the execution condition associated with the LTM candidate configuration is enabled (or activated / configured) and that the execution condition is met (or satisfied), the target candidate cell associated with that LTM candidate configuration is considered the triggering cell. When multiple triggering cells exist, the UE can select one of the triggering cells as the selected cell for conditional reconfiguration execution (i.e., the UE can apply the stored LTM candidate configuration of the selected cell). When only one triggering cell exists, the UE can apply the stored LTM candidate configuration of that triggering cell. When multiple NR cells are triggered during conditional reconfiguration execution, the UE can select which triggered NR cell to execute, for example, the UE considers beam and beam quality to select one of the triggering cells for execution. In one implementation, when multiple triggering cells exist (e.g., when the associated L1-based execution conditions of multiple candidate target cells are met), the UE's MAC layer can select one of the triggering cells as the selected cell for conditional reconfiguration execution (i.e., the UE can apply the stored LTM candidate configuration of the selected cell). In another implementation, when multiple triggering cells exist (e.g., when the associated L3-based execution conditions of multiple candidate target cells are met), the UE's RRC layer can select one of the triggering cells as the selected cell for conditional reconfiguration execution (i.e., the UE can apply the stored LTM candidate configuration of the selected cell).

[0078] In one implementation, the UE may receive downlink control information (DCI) with a specific field to indicate whether an execution condition associated with an LTM candidate configuration is enabled or disabled. When the UE's physical (PHY) layer receives the DCI with this specific field, the UE's PHY layer may notify higher layers (e.g., the MAC layer or RRC layer) that the execution condition associated with the LTM candidate configuration is enabled or disabled. Upon receiving a DCI indicating that the execution condition associated with an LTM candidate configuration (e.g., an LTM candidate configuration with a first reporting configuration) is enabled, the UE may begin evaluating the execution condition. Upon receiving a DCI indicating that the execution condition associated with an LTM candidate configuration (e.g., an LTM candidate configuration with a first reporting configuration) is disabled, the UE may stop evaluating the execution condition. In another implementation, the UE may receive a DCI with a specific field to indicate whether an execution condition associated with one or more LTM candidate configurations is enabled or disabled. For example, the DCI may indicate that the execution condition for LTM candidate configuration #1 is enabled and the execution condition for LTM candidate configuration #3 is disabled. In one implementation, a Radio Network Temporary Identifier (RNTI) value may be present for scrambling the DCI, serving as an execution condition for enabling or disabling LTM candidate configurations. Furthermore, a specific search space and / or control resource set (CORESET) may be configured for the UE to receive the DCI.

[0079] In one implementation, the UE may receive a MAC CE with a specific field to indicate that an execution condition associated with an LTM candidate configuration is enabled or disabled. When the UE's MAC layer receives a MAC CE with this specific field, the UE's MAC layer may notify a higher layer (e.g., the RRC layer) that the execution condition associated with the LTM candidate configuration is enabled or disabled. Upon receiving a MAC CE indicating that an execution condition associated with an LTM candidate configuration (e.g., an LTM candidate configuration with a first reporting configuration) is enabled, the UE may begin evaluating that execution condition. Upon receiving a DCI indicating that an execution condition associated with an LTM candidate configuration (e.g., an LTM candidate configuration with a first reporting configuration) is disabled, the UE may stop evaluating that execution condition. In another implementation, the UE may receive a MAC CE with a specific field to indicate that an execution condition associated with one or more LTM candidate configurations is enabled or disabled. For example, the MAC CE may indicate that the execution condition for LTM candidate configuration #1 is enabled and the execution condition for LTM candidate configuration #3 is disabled.

[0080] In another implementation, the associated conditional LTM execution condition of the conditional LTM candidate configuration may be related to UE speed. In one implementation, the NW may configure a speed threshold for conditional LTM. For example, when the current UE speed is greater than or equal to this speed threshold, the execution condition is considered satisfied, and the UE may apply the associated LTM candidate configuration. This speed threshold may be configured or predefined. In one implementation, the NW may configure one or more mobility states for conditional LTM. For example, the NW may configure a high mobility state as the execution condition. Once the UE determines that its current mobility state is high mobility, the UE may apply the associated LTM candidate configuration.

[0081] In another implementation, the associated conditional LTM execution conditions of the conditional LTM candidate configuration can be related to the UE location. In one implementation, the NW can configure a region (e.g., a distance range from a reference point or a set of cells). When the UE is within this region, the execution conditions may be considered unmet, and the UE may not apply the associated LTM candidate configuration. Conversely, when the UE is outside this region, the execution conditions may be considered met, and the UE may apply the associated LTM candidate configuration.

[0082] In another implementation, the associated LTM execution condition of the conditional LTM candidate configuration can be associated with a lifetime timer. In one implementation, the NW can assign a value to the lifetime timer associated with the execution condition. When the lifetime timer expires, the execution condition can be considered invalid. Conversely, when the lifetime timer is running, the execution condition can be considered valid.

[0083] In another implementation, a leaving condition can be provided for the associated conditional LTM execution conditions configured for the conditional LTM candidate. When the leaving condition is met, the execution condition can be considered invalid. Conversely, when the leaving condition is not met, the execution condition can be considered valid.

[0084] Conditional LTM configuration processing

[0085] In one implementation, when an LTM candidate configuration is applied due to LTM cell change execution (e.g., by the UE's RRC layer, such as when an indication is received from a lower layer indicating that the LTM cell change execution was successfully completed and / or the associated execution conditions are met), the UE may submit an RRC completion message accordingly.

[0086] In one implementation, once a handover process is performed (e.g., performing traditional LTM, performing conditional LTM, performing traditional HO, or performing CHO) or the UE transitions to idle (or inactive) mode, the UE may stop evaluating the conditional LTM execution conditions of the stored LTM candidate configurations.

[0087] In one implementation, once a handover procedure is performed (e.g., performing a legacy LTM, performing a conditional LTM, performing a legacy HO, or performing a CHO), the UE can release all stored LTM candidate configurations (with or without execution conditions). In another implementation, once a handover procedure is performed (e.g., performing a legacy LTM, performing a conditional LTM, performing a legacy HO, or performing a CHO), the UE can release all stored LTM candidate configurations except those configured for subsequent LTMs and / or subsequent conditional LTMs.

[0088] In one implementation, once a handover is performed (e.g., performing legacy LTM, performing conditional LTM, performing legacy HO, or performing CHO), the UE can release stored LTM candidate configurations that do not have execution conditions, and / or retain stored LTM candidate configurations that have execution conditions.

[0089] In one implementation, once a handover is performed (e.g., performing legacy LTM, performing conditional LTM, performing legacy HO, or performing CHO), the UE can release stored LTM candidate configurations with execution conditions and / or retain stored LTM candidate configurations without execution conditions.

[0090] In one implementation, the UE can voluntarily release the measurement configuration when a stored LTM candidate configuration is released (either by the UE itself or by an NW command) and a measurement configuration (or its measurement ID) is associated with the stored LTM candidate configuration. In another implementation, the UE can voluntarily release the reporting configuration when a stored LTM candidate configuration associated with a measurement configuration is released (either by the UE itself or by an NW command) and a reporting configuration (or its reporting configuration ID) associated with the measurement configuration is configured for conditional LTM (e.g., using a specific field in the reporting configuration). In yet another implementation, the UE can voluntarily release the measurement object configuration when a stored LTM candidate configuration associated with a measurement configuration is released (either by the UE itself or by an NW command) and a measurement object configuration (or its measurement object configuration ID) associated with the measurement configuration is configured for conditional LTM (e.g., using a specific field in the reporting configuration).

[0091] Coexistence of Traditional LTM and Conditional LTM

[0092] In one implementation, prior to meeting the conditional LTM execution conditions, upon receiving a handover (HO) command (without a CHO configuration) from the source base station, the UE may perform an HO procedure based on the HO command, regardless of any previously received conditional LTM candidate configurations. In another implementation, prior to meeting the conditional LTM execution conditions, upon receiving a MAC CE for LTM cell change (e.g., an LTM cell change command MAC CE as introduced in TS 38.321 version 18) from the source base station, the UE may perform an HO procedure based on the HO command, regardless of any previously received conditional LTM candidate configurations.

[0093] In some implementations, when the execution conditions (activated, enabled, or configured) of an LTM candidate configuration are met, the UE may stop (stored by the UE) any L1 / L3 measurements (or L1 / L3 measurement reporting) of any configured conventional LTM candidate configuration, stop any evaluation of the configured conditional LTM candidate configuration (stored by the UE), and / or stop any evaluation of any configured CHO / CPA / CPC. It should be noted that, as described in TS 38.300 and TS 38.331 of Release 18, CPA refers to Conditional PSCell Addition, and CPC refers to Conditional PSCell Change. It should also be noted that when the execution conditions are in an activated, enabled, or configured state, the UE may evaluate the execution conditions associated with the LTM candidate configuration. In another implementation, when the execution conditions (activation, enabling, or configuration) of an LTM candidate configuration are met, the UE may stop (stored by the UE) any L1 / L3 measurements (or L1 / L3 measurement reporting) of any configured legacy LTM candidate configuration based on an NW command (e.g., RRC signaling, MAC CE, or DCI). In yet another implementation, when the execution conditions (activation, enabling, or configuration) of an LTM candidate configuration are met, the UE may stop any evaluation of the configured conditional LTM candidate configuration (stored by the UE) based on an NW command (e.g., RRC signaling, MAC CE, or DCI) and / or based on whether any subsequent conditional LTM or subsequent legacy LTM is associated with the configured conditional LTM candidate configuration. For example, when a subsequent conditional LTM or subsequent legacy LTM associated with a configured LTM candidate configuration is configured, the UE may continue to evaluate the execution conditions of that LTM candidate configuration (e.g., when a subsequent conditional LTM or subsequent legacy LTM associated with the configured LTM candidate configuration replaces that LTM candidate configuration).

[0094] In some implementations, upon receiving an LTM-triggered MAC CE (e.g., an LTM cell change command MAC CE as introduced in TS 38.321 version 18), the UE may stop (stored by the UE) any L1 / L3 measurements (or L1 / L3 measurement reporting) of any configured legacy LTM candidate configurations, stop any evaluation of (stored by the UE) configured conditional LTM candidate configurations, and / or stop any evaluation of any configured CHO / CPA / CPC. In another implementation, upon receiving an LTM-triggered MAC CE (e.g., an LTM cell change command MAC CE as introduced in TS 38.321 version 18), the UE may stop (stored by the UE) any L1 / L3 measurements (or L1 / L3 measurement reporting) of any configured legacy LTM candidate configurations based on NW commands (e.g., RRC signaling, MAC CE, or DCI). In another implementation, when an LTM-triggered MAC CE is received (e.g., an LTM cell change command MAC CE introduced in TS 38.321 version 18), the UE may stop any evaluation of the configured conditional LTM candidate configurations (stored by the UE).

[0095] In another implementation, when an LTM-triggered MAC CE is received (e.g., an LTM cell change command MAC CE introduced in TS 38.321 version 18), the UE may stop any evaluation of the configured conditional LTM candidate configuration (stored by the UE) based on the NW command.

[0096] Coexistence of CHO / CPA / CPC and Conditional LTM

[0097] In some implementations, the UE may stop any evaluation of any configured CHO / CPA / CPC when the execution conditions of the conditional LTM configuration (activation, enable, or configuration) are met. It should be noted that, as described in TS 38.300 and TS 38.331, Release 18, CPA refers to conditional PSCell addition, and CPC refers to conditional PSCell modification. In another implementation, the UE may stop any evaluation of any configured CHO / CPA / CPC based on NW commands (e.g., RRC signaling, MAC CE, or DCI) when the execution conditions of the LTM candidate configuration (activation, enable, or configuration) are met.

[0098] Uplink synchronization for Conditional LTM

[0099] In some implementations, the UE may cease any evaluation of the configured conditional LTM candidate configurations (stored by the UE) when the execution conditions (activation, enable, or configuration) of the CHO / CPA / CPC command are met. It should be noted that the UE may evaluate the execution conditions associated with the LTM candidate configurations while the execution conditions are in an activated, enabled, or configured state. In another implementation, the UE may cease any evaluation of the configured conditional LTM candidate configurations (stored by the UE) based on an NW command (e.g., RRC signaling, MAC CE, or DCI) when the execution conditions (activation, enable, or configuration) of the CHO / CPA / CPC command are met.

[0100] For traditional LTM or conditional LTM processes, an early synchronization phase can be performed (e.g. Figure 2 Steps 204a and 204b in the above steps are used to reduce the delay and interruption time caused by the HO procedure (or LTM cell change procedure). In one implementation, the NW (or serving gNB, or serving DU) can be configured to initiate an (early) UL TA acquisition procedure to one or more target candidate cells. In one implementation, the NW (or serving gNB, or serving DU) can send a DCI (or PDCCH order) to trigger the UE to perform an early UL TA acquisition by sending a preamble, without receiving any RA response (RAR) (e.g., RAR from the target candidate cell or the current serving cell). For example, after sending the preamble to the candidate target cell (or the target base station of the candidate target cell), the UE can receive TA-related information for early UL TA acquisition from the source cell (or the source base station of the source cell) (e.g., via MAC CE).

[0101] Figure 5 This illustration shows an early ULTA acquisition process triggered by a PDCCH instruction according to one implementation of this disclosure. To provide appropriate PDCCH instruction information for the UE to transmit the preamble, the target gNB / DU may provide the source gNB / DU with the early RACH configuration of the target candidate cell, such as... Figure 5 As shown in step 501. Early RACH configuration may include a random access preamble index, an SS / PBCH index, and / or a PRACH mask index, but this disclosure should not be limited thereto. Upon receiving such... Figure 5Following the PDCCH instruction shown in step 502, the UE may transmit a preamble in step 503 based on the received PDCCH instruction. The received PDCCH instruction may instruct the UE to transmit the preamble on a normal uplink (Normal UL, NUL) carrier or a supplementary uplink (SUL, SUL) carrier. In another implementation, the UE may transmit the preamble to the target candidate cell using contention-based random access (CBRA) resources or non-contention-based random access (CFRA) resources provided by the NW (e.g., in RRC signaling or MAC CE). Whether the UE uses CBRA or CFRA resources on the NUL carrier or the SUL carrier may depend on a configured threshold. For example, when the signal strength (e.g., the currently determined RSRP) is below or equal to the threshold, the UE may use RA resources on the SUL carrier. In another example, when the signal strength (e.g., the currently determined RSRP) is above or equal to the threshold, the UE may use RA resources on the NUL carrier. Upon successfully receiving a preamble from the UE, the target gNB / DU may send a TA value and / or associated information (e.g., preamble index, random access timing information (i.e., RA-RNTI), or candidate cell identifier) ​​to allow the source gNB / DU to identify the UE, such as... Figure 5 As shown in step 504. When this information is received from the target gNB / DU, the source gNB / DU can send an LTM TA command MAC CE or similar information to the UE, such as... Figure 5 As shown in step 505. In one implementation, the LTM cell change command MAC CE can be used for both traditional LTM and conditional LTM. In one implementation, the LTM cell change command MAC CE may include fields to indicate whether the LTM cell change command MAC CE is used for traditional LTM or conditional LTM. Different fields in the LTM cell change command MAC CE may or may not be present for either the traditional LTM or conditional LTM case.

[0102] Figure 6An LTM cell change command MAC CE according to one implementation of this disclosure is shown. It should be noted that one or more fields in the LTM cell change command MAC CE may or may not be present depending on the intended use. It should also be noted that one or more fields in the LTM cell change command MAC CE may be defined differently depending on the intended use. For example, when the UE only supports storing a maximum of 8 LTM candidate configurations, the Target Configuration ID field may be 3 bits. When the UE supports storing a maximum of 16 LTM candidate configurations, the Target Configuration ID field may be 4 bits. The UE may determine the number of bits in the Target Configuration ID field based on the received configurations. For example, when the maximum received Target Configuration ID is 10 (or the number of received LTM candidate configurations is greater than or equal to 8), the Target Configuration ID field may be considered or determined to be 4 bits. When the maximum received Target Configuration ID is 7 (or the number of received LTM candidate configurations is less than or equal to 8), the Target Configuration ID field may be considered or determined to be 3 bits. Figure 6 As shown, the LTM Cell Change Command (MAC CE) is identified by a MAC sub-header with a specific Extended Logical Channel Identifier (eLCID) and has a variable size, containing the following fields:

[0103] R: Reserved bit, set to 0.

[0104] Target Configuration ID: This field indicates the index of the candidate target configuration to be applied to the LTM cell change, corresponding to ltm-CandidateId minus 1 as specified in TS 38.331 version 18. This field is 3 bits long.

[0105] Timing Advance Command: This field indicates whether the Timing Advance Command (TA) is valid for the LTM target cell (i.e., the special cell (SpCell) corresponding to the target configuration indicated by the Target Configuration ID field). When this field is set to FFF, it indicates that no valid timing adjustment is available for the primary TAG (pTAG) of the LTM target cell. Otherwise, this field indicates the index value TA used to control the amount of timing adjustment that the MAC entity must apply in TS 38.213 version 18, and the UE can skip the random access procedure for this LTM cell change. This field is 12 bits long.

[0106] TCI State ID: This field indicates and activates the TCI state for the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Configuration ID field). This TCI state is identified by the TCI-StateId in ltm-DL-OrJointTCI-StateToAddModList as specified in TS 38.331, version 18. This field is used for the joint TCI state when the value of unifiedTCI-StateType in the configuration indicated by the Target Configuration ID field is joint; otherwise, it is used for the downlink TCI state. This field is 7 bits long.

[0107] UL TCI State ID: This field indicates and activates the uplink TCI state for the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Configuration ID field). The most significant bit of the UL TCI State ID is treated as a reserved bit, and the remaining 6 bits indicate the TCI-UL-StateId in ltm-UL-TCI-StatesToAddModList as specified in TS 38.331, version 18. This field is included when the value of unifiedTCI-StateType in the configuration indicated by the Target Configuration ID field is separate. This field is 8 bits long.

[0108] C: This field indicates whether a non-contention-based random access resource field exists. When this field is set to 1, the following fields exist: Random Access Preamble Index, S / U field, SS / PBCH Index, and PRACH Mask Index. When this field is set to 0, the Random Access Preamble Index, SS / PBCH Index, and PRACH Mask Index fields do not exist, and the S / U field is considered a reserved field.

[0109] S / U: This field indicates on which UL carrier the PRACH based on non-contention-based random access resources is transmitted. When the value of this field is set to 1, SUL is used; otherwise, NUL is used. This field is 1 bit long.

[0110] Random Access Preamble Index: This field indicates the index of the random access preamble based on non-contentionable random access resources. This field is 6 bits long.

[0111] SS / PBCH Index: This field indicates the SS / PBCH used to determine the RACH occasion for PRACH transmissions based on non-contention-based random access resources. This field is 6 bits long.

[0112] PRACH Mask Index: This field indicates the RACH timing associated with the SS / PBCH indicated by the "SS / PBCH Index" for PRACH transmissions based on non-contentionable random access resources, referring to the rach-ConfigDedicated in the UL BWP configuration of firstActiveUplinkBWP-Id as specified in TS38.331, version 18 (or rach-ConfigCommon if not provided). This field is 4 bits long.

[0113] In one implementation, one of the R fields of the LTM cell change command MAC CE can be used to indicate whether the LTM cell change command MAC CE is for traditional LTM or conditional LTM. For example, when the selected R field is set to a specific value (e.g., 0), the LTM cell change command MAC CE is for traditional LTM, and the target configuration ID field is used to indicate a specific LTM candidate configuration that does not have execution conditions. When the selected R field is set to a specific value (e.g., 1), the LTM cell change command MAC CE is for conditional LTM, and the target configuration ID field is used to indicate a specific LTM candidate configuration that has execution conditions.

[0114] In one implementation, the C field of the LTM cell change command MAC CE for conditional LTM can always be set to 0. That is, the purpose of the LTM cell change command MAC CE for conditional LTM is to provide the UE with a TA command for early UL acquisition, rather than instructing the UE to perform the RA procedure upon receiving the LTM cell change command MAC CE.

[0115] In one implementation, the TCI status ID of the LTM cell change command MAC CE used for conditional LTM may not exist. In another implementation, the R field can be used to indicate whether the TCI status ID of the LTM cell change command MAC CE used for conditional LTM exists.

[0116] In one implementation, the ULTCI status ID of the LTM cell change command MAC CE used for conditional LTM may not exist. In another implementation, the R field can be used to indicate whether the ULTCI status ID of the LTM cell change command MAC CE used for conditional LTM exists.

[0117] In one implementation, conditional LTM and traditional LTM can share the same ID pool. That is, for the UE, a configured LTM candidate configuration with execution conditions and another configured LTM candidate configuration without execution conditions cannot be configured with the same LTM ID. In one implementation, because conditional LTM and traditional LTM share the same ID pool, the total number of configured LTM candidate configurations with and without execution conditions that the UE can store can be predefined or fixed (e.g., 8). For example, a UE with conditional LTM capability can be configured with up to 8 LTM configurations, including LTM candidate configurations with execution conditions and LTM candidate configurations without any execution conditions. In one example, a UE with conditional LTM capability can be configured with up to 8 LTM candidate configurations with associated execution conditions. In another implementation, when the UE can support storing more LTM candidate configurations (e.g., 16), the UE can support this capability to the NW. When the NW receives this capability, the NW can (e.g., via RRC signaling or MAC CE) notify the UE of the maximum value of the target configuration ID to be configured.

[0118] In one implementation, conditional LTM and traditional LTM may not share the same ID pool. That is, for the UE, a configured LTM candidate configuration with execution conditions and another configured LTM candidate configuration without execution conditions can be configured with the same LTM ID. In one implementation, the maximum number of configured LTM candidate configurations with execution conditions that the UE can store can be predefined or fixed (e.g., 8). In one implementation, the maximum number of configured LTM candidate configurations without execution conditions that the UE can store can be predefined or fixed (e.g., 8). For example, the UE can be configured with 8 configured LTM candidate configurations with execution conditions and 8 configured LTM candidate configurations without any execution conditions simultaneously.

[0119] Figure 7 An example communication system 700 with an example communication device 710 and an example network device 720 according to one implementation of the present disclosure is shown. The communication device 710 and the network device 720 are each capable of performing various functions to implement the schemes, techniques, processes and methods described herein regarding conditional LTM process configuration, including the above-described scenarios / schemes and the process 700 described below.

[0120] The communication device 710 may be part of an electronic device, such as a portable or mobile device, a wearable device, a wireless communication device, or a computing device (UE). For example, the communication device 710 may be implemented in a smartphone, smartwatch, personal digital assistant, digital camera, or computing device such as a tablet, laptop, or notebook computer. The communication device 710 may also be part of a machine-type device, such as a fixed or stationary device, a home device, a wired communication device, or a computing device (IoT, NB-IoT, or IIoT). For example, the communication device 710 may be implemented in a smart thermostat, smart refrigerator, smart door lock, wireless speaker, or home control center. Alternatively, the communication device 710 may be implemented as one or more integrated circuit (IC) chips, such as, and not limited to, one or more single-core processors, one or more multi-core processors, one or more reduced-instruction-set computing (RISC) processors, or one or more complex-instruction-set computing (CISC) processors. The communication device 710 may include, for example, a single-core processor, a multi-core processor, a reduced-instruction-set computing (RISC) processor, or a complex-instruction-set computing (CISC) processor. Figure 7 At least some of the components shown, such as processor 712. Communication device 710 may also include one or more other components unrelated to the scheme presented in this disclosure (e.g., internal power supply, display device, and / or user interface device); therefore, for the sake of brevity, such components of communication device 710 are not described in [the following text is missing from the original extract]. Figure 7 It is shown in the text and is not described in the following text.

[0121] Network device 720 may be part of an electronic device, which may be a network node such as a BS, small cell, router, or gateway. For example, network device 720 may be implemented in a gNB in ​​a 5G, B5G, 6G, IoT, NB-IoT, or IIoT network. Alternatively, network device 720 may be implemented as one or more IC chips, such as, and not limited to, one or more single-core processors, one or more multi-core processors, or one or more RISC or CISC processors. Network device 720 may include, for example, Figure 7 At least some of the components shown, such as processor 722. Network device 720 may also include one or more other components (e.g., internal power supply, display device, and / or user interface device) unrelated to the scheme presented in this disclosure; therefore, for the sake of brevity, such components of network device 720 are not described in [the following text is missing from the original extract]. Figure 7 It is shown in the text and is not described in the following text.

[0122] On one hand, processor 712 and processor 722 may each be implemented as one or more single-core processors, one or more multi-core processors, or one or more CISC processors. That is, even though the singular term "processor" is used herein to refer to processor 712 and processor 722, according to this disclosure, in some implementations processor 712 and processor 722 may each include multiple processors, while in other implementations they may include a single processor. On the other hand, processor 712 and processor 722 may each be implemented as hardware (and optionally firmware) having electronic components, including, for example and not limited to, one or more transistors, one or more diodes, one or more capacitors, one or more resistors, one or more inductors, one or more memristors, and / or one or more varactor diodes, configured and arranged to achieve a particular purpose according to this disclosure. In other words, in at least some implementations, processor 712 and processor 722 are each dedicated machines specifically designed, arranged and configured to perform a particular task, which includes configuring a conditional LTM process in a UE (e.g., represented by communication device 710) and a gNB (e.g., represented by network device 720) according to various implementations of this disclosure.

[0123] In some implementations, the communication device 710 may further include a transceiver 716 coupled to the processor 712 and capable of wirelessly transmitting and receiving control and data signals. In some implementations, the transceiver 716 may be capable of wireless communication with different types of gNBs on different RATs. In some implementations, the transceiver 716 may be equipped with multiple antenna ports (not shown), such as four antenna ports. That is, the transceiver 716 may be equipped with multiple transmit antennas and multiple receive antennas for multiple-input multiple-output (MIMO) wireless communication. In some implementations, the network device 720 may further include a transceiver 726 coupled to the processor 722 and capable of wirelessly transmitting and receiving control and data signals. In some implementations, the transceiver 726 may be capable of wireless communication with different types of UEs on different RATs. In some implementations, the transceiver 726 may be equipped with multiple antenna ports (not shown), such as four antenna ports. In other words, transceiver 726 may be equipped with multiple transmit antennas and multiple receive antennas for MIMO wireless communication. Accordingly, communication device 710 and network device 720 may communicate wirelessly with each other via transceiver 716 and transceiver 726, respectively.

[0124] In some implementations, the communication device 710 may further include a memory 714 coupled to and accessible by the processor 712, whereby data is stored. In some implementations, the network device 720 may further include a memory 724 coupled to and accessible by the processor 722, whereby data is stored. Each of the memories 714 and 724 may include a type of random-access memory (RAM), such as dynamic RAM (DRAM), static RAM (SRAM), thyristor RAM (T-RAM), and / or zero-capacitor RAM (Z-RAM). Alternatively or additionally, each of memories 714 and 724 may include a type of read-only memory (ROM), such as a mask ROM, a programmable ROM (PROM), an erasable programmable ROM (EPROM), and / or an electrically erasable programmable ROM (EEPROM). Alternatively or additionally, each of memories 714 and 724 may include a type of non-volatile random-access memory (NVRAM), such as flash memory, solid-state memory, ferroelectric RAM (FeRAM), magnetoresistive RAM (MRAM), and / or phase-change memory.

[0125] Each of the communication device 710 and the network device 720 can be a communication entity capable of communicating with each other using various proposed schemes according to this disclosure. For illustrative and non-limiting purposes, the following provides implementations in or as a UE (e.g., Figures 2 to 3 The communication device 710 of the UE in the gNB and the communication device 710 implemented in or as a gNB (e.g., Figure 2 gNB or Figure 3 Description of the operation, functions and capabilities of the network device 720 (NW) in the NW.

[0126] According to some of the proposed solutions in this disclosure, the processor 712 of the communication device 710 can receive one or more Radio Resource Control (RRC) messages from the network device 720 via a transceiver 716. The processor 712 can then be configured with one or more LTM commands included in the one or more RRC messages, wherein the total number of the one or more LTM commands does not exceed a predetermined number, and the one or more LTM commands include at least one of a first type LTM command and a second type LTM command, wherein the first type LTM command includes a first target cell configuration of a first target cell and a first execution condition, and the second type LTM command includes a second target cell configuration of a second target cell and does not have any execution condition. In one implementation, the memory 714 can store up to the predetermined number (e.g., eight) of the LTM commands.

[0127] Figure 8 An example process 800 according to one implementation of this disclosure is shown. Process 800 may be a partial or complete example implementation of the above-described scenario / scheme regarding a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) process. Process 800 may represent one aspect of an implementation of features of communication device 710. Process 800 may include one or more operations, actions, or functions illustrated by one or more of boxes S805 and S810. Although shown as discrete boxes, the individual boxes of process 800 may be divided into additional boxes, combined into fewer boxes, or eliminated, depending on the desired implementation. Furthermore, the individual boxes of process 800 may be arranged in... Figure 8 The process can be executed in the order shown, or alternatively, in a different order. Process 800 can be implemented by communication device 710 or any suitable UE. For illustrative purposes only and not for limitation, process 800 is described below in the context of communication device 710 as a UE and network device 720 as a gNB or BS. Process 800 may begin at block S805.

[0128] In S805, process 800 may involve the processor 712 of communication device 710 receiving one or more Radio Resource Control (RRC) messages from network device 720 via transceiver 716. Process 800 may proceed from S805 to S810.

[0129] In S810, process 800 may involve a processor 712 of communication device 710 being configured with one or more LTM commands contained in the one or more RRC messages, wherein the total number of the one or more LTM commands does not exceed a predetermined number, the one or more LTM commands include at least one of a first type LTM command and a second type LTM command, the first type LTM command including a first target cell configuration of a first target cell and a first execution condition, and the second type LTM command including a second target cell configuration of a second target cell and having no execution condition.

[0130] In some implementations, the UE is configured to provide auxiliary information to the source base station to determine whether a conditional LTM command, as a first-type LTM command, is required.

[0131] In some implementations, for a first type LTM command, process 800 may involve the processor 712 of the communication device 710 determining whether a first execution condition is activated and performing one of the following operations: evaluating the first execution condition when the first execution condition is activated; and stopping the evaluation of the first execution condition when the first execution condition is not activated.

[0132] In some implementations, the predetermined quantity is 8.

[0133] In some implementations, when a cell change process is triggered, the processor 712 of the communication device 710 stops monitoring the source cell of the source base station.

[0134] In some implementations, for a first type of LTM command, process 800 may involve the processor 712 of the communication device 710 evaluating a first execution condition and performing one of the following operations: when the first execution condition is not met and a handover command is received from the source base station, performing a handover process based on the handover command; and when the first execution condition is met, triggering a cell change process by applying a first target cell configuration.

[0135] In some implementations, the first target cell is the triggering cell when the first execution condition is based on L3 and is met. If multiple triggering cells exist, the UE's RRC layer selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

[0136] In some implementations, the first target cell is the triggering cell when the first execution condition is based on L1 and is satisfied. In the presence of multiple triggering cells, the UE's Medium Access Control (MAC) layer selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

[0137] In some implementations, when the UE transitions to the RRC_IDLE state, the processor 712 of the communication device 710 stops evaluating the first execution condition.

[0138] In some implementations, one or more LTM commands is a first type LTM command, and the first execution condition of one or more LTM commands is associated with a measurement identifier (ID). When one or more LTM commands are released, the processor 712 of the communication device 710 autonomously removes the reporting configuration associated with the measurement ID.

[0139] While this disclosure has been described by way of example and in conjunction with preferred embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and similar arrangements (as will be apparent to those skilled in the art). Therefore, the scope of the appended claims should be given the broadest interpretation to cover all such modifications and similar arrangements.

Claims

1. A method for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure, wherein the method is implemented by user equipment (UE) and includes: Receive one or more Radio Resource Control (RRC) messages from the source base station; as well as The LTM command is configured to be included in one or more RRC messages, wherein the total number of the LTM command does not exceed a predetermined number. The one or more LTM commands include at least one of a first type of LTM command and a second type of LTM command. The first type of LTM command includes a first target cell configuration of a first target cell and a first execution condition. The second type of LTM command includes a second target cell configuration of a second target cell and does not have any execution conditions.

2. The method for an LTM procedure according to claim 1, wherein the UE is configured to provide auxiliary information to the source base station for determining whether a conditional LTM command is required as the first type of LTM command.

3. The method for an LTM process according to claim 1, wherein for the first type of LTM command, the method further comprises: Determine whether the first execution condition is activated; Perform one of the following operations: When the first execution condition is activated, the first execution condition is evaluated; as well as When the first execution condition is not activated, the evaluation of the first execution condition is stopped.

4. The method for an LTM process according to claim 1, wherein the predetermined quantity is 8.

5. The method for an LTM procedure according to claim 1, wherein when a cell change procedure is triggered, the UE stops monitoring the source cell of the source base station.

6. The method for an LTM process according to claim 1, wherein for the first type of LTM command, the method further comprises: Evaluate the first execution condition; as well as Perform one of the following operations: When the first execution condition is not met and a handover command is received from the source base station, the handover process is executed based on the handover command; as well as When the first execution condition is met, the cell change process is triggered by applying the first target cell configuration.

7. The method for an LTM procedure according to claim 6, wherein the first target cell is a triggering cell when the first execution condition is based on L3 and is satisfied; and In the presence of multiple triggering cells, the RRC layer of the UE selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

8. The method for an LTM procedure according to claim 6, wherein the first target cell is a triggering cell when the first execution condition is based on L1 and is satisfied; and In the presence of multiple triggering cells, the UE's Medium Access Control (MAC) layer selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

9. The method for an LTM process according to claim 6, further comprising: When the UE transitions to the RRC_IDLE state, the evaluation of the first execution condition is stopped.

10. The method for an LTM process according to claim 1, wherein one of the one or more LTM commands is a first type of LTM command, and the first execution condition of one or more LTM commands is associated with a measurement identifier (ID), the method further comprising: When one or more LTM commands are released, the reporting configuration associated with the measurement ID is automatically removed.

11. An apparatus for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) process, comprising: A transceiver that communicates wirelessly with at least one network node during operation; as well as A processor, communicatively coupled to the transceiver, such that during operation, the processor performs operations including: Receive one or more Radio Resource Control (RRC) messages from the source base station; The LTM command is configured to be included in one or more RRC messages, wherein the total number of the LTM command does not exceed a predetermined number. The one or more LTM commands include at least one of a first type of LTM command and a second type of LTM command. The first type of LTM command includes a first target cell configuration of a first target cell and a first execution condition. The second type of LTM command includes a second target cell configuration of a second target cell and does not have any execution conditions.

12. The apparatus for an LTM process according to claim 11, wherein the apparatus is configured to provide auxiliary information to the source base station for determining whether a conditional LTM command is required as the first type of LTM command.

13. The apparatus for an LTM process according to claim 11, wherein, for the first type of LTM command, the processor further performs operations including: Determine whether the first execution condition is activated; Perform one of the following operations: When the first execution condition is activated, the first execution condition is evaluated; and When the first execution condition is not activated, the evaluation of the first execution condition is stopped.

14. The apparatus for an LTM process according to claim 11, wherein the predetermined quantity is 8.

15. The apparatus for an LTM process according to claim 11, wherein when a cell change process is triggered, the apparatus stops monitoring the source cell of the source base station.

16. The apparatus for an LTM process according to claim 11, wherein, for the first type of LTM command, the processor further performs operations including: Evaluate the first execution condition; and Perform one of the following operations: When the first execution condition is not met and a handover command is received from the source base station, the handover process is executed based on the handover command; and When the first execution condition is met, the cell change process is triggered by applying the first target cell configuration.

17. The apparatus for an LTM procedure according to claim 16, wherein the first target cell is a triggering cell when the first execution condition is based on L3 and is satisfied; and In the presence of multiple triggering cells, the RRC layer of the UE selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

18. The apparatus for an LTM procedure according to claim 16, wherein the first target cell is a triggering cell when the first execution condition is based on L1 and is satisfied; and In the presence of multiple triggering cells, the Medium Access Control (MAC) layer of the device selects one of the triggering cells as the selected cell and applies the associated target cell configuration of the selected cell.

19. The apparatus for an LTM process according to claim 16, wherein the processor further performs operations including: When the device transitions to the RRC_IDLE state, it stops evaluating the first execution condition.

20. The apparatus for an LTM process according to claim 11, wherein one of the one or more LTM commands is a first type of LTM command, and the first execution condition of one or more LTM commands is associated with a measurement identifier (ID), the processor further performs operations including: When one or more LTM commands are released, the reporting configuration associated with the measurement ID is automatically removed.

21. A method for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) process, wherein the method is implemented by a source base station and includes: Send one or more Radio Resource Control (RRC) messages to User Equipment (UE), wherein one or more LTM commands are configured in the one or more RRC messages, the total number of the one or more LTM commands not exceeding a predetermined number, the one or more LTM commands include at least one of a first type LTM command and a second type LTM command, the first type LTM command includes a first target cell configuration of a first target cell and a first execution condition, and the second type LTM command includes a second target cell configuration of a second target cell and does not have any execution conditions.

22. The method for an LTM process according to claim 21, wherein the predetermined quantity is 8.

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