Methods and apparatus for both intra-BS and inter-BS LTM procedures

Abstract

Various aspects of the present disclosure relate to methods and apparatuses for both intra-BS lower tier mobility (LTM) procedures and inter-BS LTM procedures. According to embodiments of the present disclosure, a centralized unit (CU) of a base station (BS) includes at least one memory and at least one processor coupled to the at least one memory and configured to cause the CU to receive, from a source distributed unit (DU) of the BS, first information related to one or more candidate cells associated with a lower tier mobility (LTM) cell handover of a user equipment (UE) from a source cell of the source DU toward a candidate cell, and transmit, to a candidate DU of the BS or a second CU of another BS, both the information related to the one or more candidate cells and the received information, wherein the candidate cell is related to the candidate DU or the other CU.

Description

Technical Field

[0001] This disclosure relates to wireless communications, and more specifically, to methods and apparatus for both intra-BS (Base Station) Lower Layer Triggered Mobility (LTM) procedures and inter-BS LTM procedures. LTM may also be referred to as L1 / L2 Lower Layer Triggered Mobility or similar. Background Technology

[0002] A wireless communication system may include one or more network communication devices, such as a base station, which can support wireless communication of one or more user communication devices (which may also be referred to as user equipment (UE) or other suitable terms). The wireless communication system can support wireless communication with one or more user communication devices by utilizing the resources of the wireless communication system (e.g., time-domain resources (e.g., symbols, time slots, subframes, frames, or the like) or frequency-domain resources (e.g., subcarriers, carriers, or the like)). Furthermore, the wireless communication system can support wireless communication across various radio access technologies, including third-generation (3G) radio access technology, fourth-generation (4G) radio access technology, fifth-generation (5G) radio access technology, and other suitable radio access technologies beyond 5G (e.g., sixth-generation (6G)). Summary of the Invention

[0003] The article “a” preceding an element is unrestricted and should be understood to refer to “at least one” or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” are interchangeable. As used herein (included in the claims), the word “or” used in a list of items (e.g., a list of items beginning with phrases such as “at least one of…”, “one or more of…”, or “one or both of…”) indicates an inclusive list, such that (e.g.) a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase “based on” should not be construed as referring to a closed set of conditions. For example, without departing from the scope of this disclosure, an example step described as “based on condition A” may be based on both condition A and condition B. In other words, as used herein, the phrase “based on” should be interpreted in the same manner as the phrase “at least partially based on.” Furthermore, as used herein (included in the claims), a “group” may comprise one or more elements.

[0004] Some embodiments of this disclosure provide a first centralized unit (CU) for a first base station (BS). The first CU includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the first CU: receives first information related to one or more candidate cells from a source distributed unit (DU) of the first BS, the one or more candidate cells being associated with a user equipment (UE) for a lower layer triggered mobility (LTM) cell handover from a source cell of the source DU to the first candidate cell; and transmits both the second information related to the one or more candidate cells and the received first information to a candidate DU of the first BS or a second CU of a second BS, wherein the first candidate cell is associated with the candidate DU or the second CU.

[0005] In some implementations of the first CU described herein, the first candidate cell is a candidate primary cell (PCell) or a candidate primary secondary cell group cell (PSCell).

[0006] In some embodiments of the first CU described herein, the first information includes at least one of the following: Active Transmit Configuration Indicator (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information for Early Timing Advance (TA) acquisition associated with the one or more candidate cells; one or more early TA values ​​associated with the one or more candidate cells; remaining length information of the time alignment timer (TAT) of the one or more early TA values; identifier (ID) information of the one or more candidate cells; ID information of the first candidate cell; or ID information of the UE.

[0007] In some embodiments of the first CU described herein, the second information includes at least one of the following: one or more early TA values ​​associated with the one or more candidate cells; remaining length information of the time alignment timer (TAT) of the one or more early TA values; LTM channel state information (CSI) resource configuration information; TA ID of the one or more candidate cells measured by the UE; or Layer 2 (L2) reset ID of the one or more candidate cells.

[0008] In some embodiments of the first CU described herein, the first information and the second information are received or transmitted via at least one of the following: Radio Resource Control (RRC) message transmission message; RRC delivery report message; UE context modification need message; or UE context modification request message.

[0009] In some implementations of the first CU described herein, the first information is received after the source DU is configured to transmit an LTM cell handover command to the UE for triggering the LTM cell handover.

[0010] In some implementations of the first CU described herein, the first information and the second information are transmitted after the first CU receives an indication to complete the LTM cell handover.

[0011] Some embodiments of this disclosure provide a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured such that the processor: receives first information associated with one or more candidate cells from a source distributed unit (DU) of a first base station (BS), the one or more candidate cells being associated with a user equipment (UE) for a lower layer triggered mobility (LTM) cell handover from a source cell of the source DU to the first candidate cell; and transmits both the second information associated with the one or more candidate cells and the received first information to a candidate DU of the first BS or a second centralized unit (CU) of a second BS, wherein the first candidate cell is associated with the candidate DU or the second CU.

[0012] Some embodiments of this disclosure provide a method performed by a first centralized unit (CU) of a base station (BS). The method includes: receiving, from a source distributed unit (DU) of the first BS, first information relating to one or more candidate cells, said candidate cells being associated with a user equipment (UE) undergoing a lower layer triggered mobility (LTM) cell handover from a source cell of the source DU to the first candidate cell; and transmitting, to a candidate DU of the first BS or a second CU of a second BS, both the second information relating to the one or more candidate cells and the received first information, wherein the first candidate cell is associated with the candidate DU or the second CU.

[0013] Some embodiments of this disclosure provide a source distributed unit (DU) for a first base station (BS). The DU includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the source DU to: determine a trigger user equipment (UE) to perform a lower layer triggered mobility (LTM) cell handover from a source cell of the source DU to a first candidate cell; and transmit first information related to one or more candidate cells associated with the LTM cell handover to a first centralized unit (CU) of the first BS, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of a second BS.

[0014] In some implementations of the source DU described herein, the first candidate cell is a candidate primary cell (PCell) or a candidate primary secondary cell group cell (PSCell).

[0015] In some implementations of the source DU described herein, the first information includes at least one of the following: Active Transmit Configuration Indicator (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information for Early Timing Advance (TA) acquisition associated with the one or more candidate cells; one or more early TA values ​​associated with the one or more candidate cells; remaining length information of the time alignment timer (TAT) of the one or more early TA values; identifier (ID) information of the one or more candidate cells; ID information of the first candidate cell; or ID information of the UE.

[0016] In some implementations of the source DU described herein, the first information is transmitted via at least one of the following: a Radio Resource Control (RRC) message transmission message; an RRC delivery report message; or a UE context modification request message.

[0017] Some embodiments of this disclosure provide a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured to cause the processor to: determine to trigger a user equipment (UE) to perform a lower layer triggered mobility (LTM) cell handover from a source cell of a source distributed unit (DU) of a first base station (BS) to a first candidate cell; and transmit to a first centralized unit (CU) of the first BS first information relating to one or more candidate cells associated with the LTM cell handover, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of a second BS.

[0018] Some embodiments of this disclosure provide a method performed by a source distributed unit (DU) of a first base station (BS). The method includes: determining a trigger user equipment (UE) to perform a lower-layer triggered mobility (LTM) cell handover from a source cell of the source DU to a first candidate cell; and transmitting first information to a first centralized unit (CU) of the first BS relating to one or more candidate cells associated with the LTM cell handover, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of a second BS.

[0019] Some embodiments of this disclosure provide a second centralized unit (CU) for a second base station (BS). The second CU includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the second CU to: receive information from a first CU of a first BS associated with one or more candidate cells, the candidate cells being associated with a user equipment (UE) for a lower layer triggered mobility (LTM) cell handover from a source cell of a source distributed unit (DU) of the first BS to a first candidate cell; and transmit the received information to a candidate DU of the second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: first information transmitted from the source DU to the first CU; and second information transmitted from the first CU.

[0020] In some implementations of the second CU described herein, the first candidate cell is a candidate primary cell (PCell) or a candidate primary secondary cell group cell (PSCell).

[0021] In some embodiments of the second CU described herein, the first information includes at least one of the following: Active Transmit Configuration Indicator (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information for Early Timing Advance (TA) acquisition associated with the one or more candidate cells; one or more early TA values ​​associated with the one or more candidate cells; remaining length information of the time alignment timer (TAT) of the one or more early TA values; identifier (ID) information of the one or more candidate cells; ID information of the first candidate cell; or ID information of the UE.

[0022] In some embodiments of the second CU described herein, the second information includes at least one of the following: one or more early TA values ​​associated with the one or more candidate cells; remaining length information of the time alignment timer (TAT) of the one or more early TA values; LTM channel state information (CSI) resource configuration information; TA ID of the one or more candidate cells measured by the UE; or Layer 2 (L2) reset ID of the one or more candidate cells.

[0023] In some implementations of the second CU described herein, the information is received via at least one of the following: an RRC message transmission message; an RRC delivery report message; or a UE context modification request message.

[0024] Some embodiments of this disclosure provide a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured to: receive information from a first centralized unit (CU) of a first base station (BS) relating to one or more candidate cells, the one or more candidate cells being associated with a user equipment (UE) for a lower layer triggered mobility (LTM) cell handover from a source cell of a source distributed unit (DU) of the first BS to the first candidate cell; and transmit the received information to a candidate DU of a second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: first information transmitted from the source DU to the first CU; and second information transmitted from the first CU.

[0025] Some embodiments of this disclosure provide a method performed by a second centralized unit (CU) of a second base station (BS). The method includes: receiving information from a first CU of a first BS associated with one or more candidate cells, the candidate cells being associated with a user equipment (UE) undergoing a lower layer triggered mobility (LTM) cell handover from a source cell of a source distributed unit (DU) of the first BS to a first candidate cell; and transmitting the received information to a candidate DU of the second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: first information transmitted from the source DU to the first CU; and second information transmitted from the first CU.

[0026] Some embodiments of this disclosure provide a first base station (BS). The first BS includes: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the first BS to: transmit to a second BS a request related to a lower-layer triggered mobility (LTM) cell handover from a source cell of the first BS to a first candidate cell of the second BS, with respect to a user equipment (UE)-based timing advance (TA) measurement or a Layer 2 (L2) reset-free method; and receive from the second BS a response related to the UE-based TA measurement or the L2 reset-free method.

[0027] In some implementations of the first BS described herein, the candidate cell is a candidate primary cell (PCell) or a candidate primary secondary cell group cell (PSCell).

[0028] In some implementations of the first BS described herein, the request includes at least one of the following: requesting the second BS to provide information on a candidate cell list, wherein when performing the LTM cell handover from the source cell to one of the candidate cells in the candidate cell list, the UE can obtain the TA value of the candidate cells in the candidate cell list by performing the UE-based TA measurement; requesting the second BS to indicate whether a second candidate cell of the second BS has a candidate DU that is the same as one or more candidate cells of the second BS, wherein when performing the LTM cell handover from the source cell to the second candidate cell, the UE can obtain the TA value of the second candidate cell by performing the UE-based TA measurement; requesting the second BS to provide information on the identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range of UE-measured TA reserved for the one or more candidate cells of the second BS.

[0029] In some implementations of the first BS described herein, the request includes at least one of the following: requesting the second BS to provide information on a candidate cell list, wherein when the UE performs the LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an L2 reset for each of the candidate cells in the candidate cell list; requesting the second BS to indicate whether a second candidate cell of the second BS has candidate DUs that are the same as one or more candidate cells of the second BS, wherein when the UE performs the LTM cell handover from the source cell to the second candidate cell, the UE does not perform an L2 reset for the second candidate cell; requesting the second BS to provide information on identifier (ID) information of candidate DUs associated with the second candidate cell; or an ID range for a set of candidate cells reserved for the L2 reset.

[0030] In some implementations of the first BS described herein, if the second candidate cell has the same candidate DU as the one or more candidate cells, then the request further includes identifier (ID) information of the second candidate cell.

[0031] In some implementations of the first BS described herein, the response includes at least one of the following: a candidate cell list, wherein when performing the LTM cell handover from the source cell to one of the candidate cells in the candidate cell list, the UE can obtain the TA value of the candidate cells in the candidate cell list by performing the UE-based TA measurement; information indicating whether a second candidate cell of the second BS has the same candidate DU as one or more candidate cells of the second BS, wherein when performing the LTM cell handover from the source cell to the second candidate cell, the UE can obtain the TA value of the second candidate cell by performing the UE-based TA measurement; identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range of UE-measured TA reserved for the one or more candidate cells of the second BS.

[0032] In some implementations of the first BS described herein, the response includes at least one of the following: a candidate cell list, wherein when the UE performs the LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an L2 reset for each of the candidate cells in the candidate cell list; information indicating whether a second candidate cell of the second BS has a candidate DU that is the same as one or more candidate cells of the second BS, wherein when the UE performs the LTM cell handover from the source cell to the second candidate cell, the UE does not perform an L2 reset for the second candidate cell; identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range for a set of candidate cells reserved for the no-L2-reset.

[0033] In some implementations of the first BS described herein, if the second candidate cell has the same candidate DU as the one or more candidate cells, then the response further includes identifier (ID) information of the second candidate cell.

[0034] Some embodiments of this disclosure provide a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured to: transmit to a second base station (BS) a request related to a user equipment (UE)-based timing advance (TA) measurement or a Layer 2 (L2) reset-free operation for a lower-layer triggered mobility (LTM) cell handover from a source cell of a first BS to a first candidate cell of the second BS; and receive from the second BS a response related to the UE-based TA measurement or the L2 reset-free operation.

[0035] Some embodiments of this disclosure provide a method performed by a first base station (BS). The method includes: transmitting to a second BS a request related to a user equipment (UE)-based timing advance (TA) measurement or a Layer 2 (L2) reset-free operation for a lower-layer triggered mobility (LTM) cell handover from a source cell of the first BS to a first candidate cell of the second BS; and receiving from the second BS a response related to the UE-based TA measurement or the L2 reset-free operation.

[0036] Some embodiments of this disclosure provide a second base station (BS). The second BS includes: at least one memory; and at least one processor coupled to the at least one memory and configured such that the second BS: receives from a first BS a request related to a lower-layer triggered mobility (LTM) cell handover from a source cell of the first BS to a first candidate cell of the second BS, with respect to a user equipment (UE)-based timing advance (TA) measurement or a Layer 2 (L2) reset-free method; and transmits to the first BS a response related to the UE-based TA measurement or the L2 reset-free method.

[0037] In some implementations of the second BS described herein, the candidate cell is a candidate primary cell (PCell) or a candidate primary secondary cell group cell (PSCell).

[0038] In some implementations of the second BS described herein, the request includes at least one of the following: requesting the second BS to provide information on a candidate cell list, wherein when performing the LTM cell handover from the source cell to one of the candidate cells in the candidate cell list, the UE can obtain the TA value of the candidate cells in the candidate cell list by performing the UE-based TA measurement; requesting the second BS to indicate whether a second candidate cell of the second BS has a candidate DU that is the same as one or more candidate cells of the second BS, wherein when performing the LTM cell handover from the source cell to the second candidate cell, the UE can obtain the TA value of the second candidate cell by performing the UE-based TA measurement; requesting the second BS to provide information on the identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range of UE-measured TA reserved for the one or more candidate cells of the second BS.

[0039] In some implementations of the second BS described herein, the request includes at least one of the following: requesting the second BS to provide information on a candidate cell list, wherein when the UE performs the LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an LTM L2 reset for each of the candidate cells in the candidate cell list; requesting the second BS to indicate whether a second candidate cell of the second BS has candidate DUs that are the same as one or more candidate cells of the second BS, wherein when the UE performs the LTM cell handover from the source cell to the second candidate cell, the UE does not perform an L2 reset for the second candidate cell; requesting the second BS to provide information on identifier (ID) information of candidate DUs associated with the second candidate cell; or an ID range for a set of candidate cells reserved for the L2 reset.

[0040] In some implementations of the second BS described herein, if the first candidate cell has the same candidate DU as the one or more candidate cells, then the request further includes identifier (ID) information of the first candidate cell.

[0041] In some implementations of the second BS described herein, the response includes at least one of the following: a candidate cell list, wherein when performing the LTM cell handover from the source cell to one of the candidate cells in the candidate cell list, the UE can obtain the TA value of the candidate cells in the candidate cell list by performing the UE-based TA measurement; information indicating whether a second candidate cell of the second BS has the same candidate DU as one or more candidate cells of the second BS, wherein when performing the LTM cell handover from the source cell to the second candidate cell, the UE can obtain the TA value of the first candidate cell by performing the UE-based TA measurement; identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range of UE-measured TA reserved for the one or more candidate cells of the second BS.

[0042] In some implementations of the second BS described herein, the response includes at least one of the following: a candidate cell list, wherein when the UE performs the LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an L2 reset for each of the candidate cells in the candidate cell list; information indicating whether a second candidate cell of the second BS has a candidate DU that is the same as one or more candidate cells of the second BS, wherein when the UE performs the LTM cell handover from the source cell to the second candidate cell, the UE does not perform an L2 reset for the second candidate cell; identifier (ID) information of the candidate DU associated with the second candidate cell; or an ID range for a set of candidate cells reserved for the no-L2-reset.

[0043] In some implementations of the second BS described herein, if the first candidate cell has the same candidate DU as the one or more candidate cells, then the response further includes the identifier (ID) information of the first candidate cell.

[0044] Some embodiments of this disclosure provide a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured to: receive from a first base station (BS) a request related to a lower-layer triggered mobility (LTM) cell handover from a source cell of the first BS to a first candidate cell of a second BS, for a user equipment (UE)-based timing advance (TA) measurement or a Layer 2 (L2) reset-free operation; and transmit to the first BS a response related to the UE-based TA measurement or the L2 reset-free operation.

[0045] Some embodiments of this disclosure provide a method performed by a second base station (BS). The method includes: receiving from a first BS a request related to a User Equipment (UE)-based Timing Advance (TA) measurement or Layer 2 Reset-Free (L2) measurement for a lower-layer triggered mobility (LTM) cell handover from a source cell of the first BS to a first candidate cell of the second BS; and transmitting to the first BS a response related to the UE-based TA measurement or the L2 Reset-Free (L2) measurement. Attached Figure Description

[0046] Figure 1 Examples of wireless communication systems according to aspects of this disclosure are described.

[0047] Figure 2 An example of a user equipment (UE) 200 according to aspects of this disclosure is described.

[0048] Figure 3 An example of processor 300 according to aspects of this disclosure is described.

[0049] Figure 4 An example of a network equipment (NE) 400 according to aspects of this disclosure is described.

[0050] Figure 5A A schematic diagram illustrating a mobility scenario within a CU and DU according to aspects of this disclosure.

[0051] Figure 5B A schematic diagram illustrating a scenario of mobility between DUs within a CU according to aspects of this disclosure.

[0052] Figure 5C A schematic diagram illustrating a scenario of inter-CU mobility according to aspects of this disclosure.

[0053] Figures 6 to 10 A flowchart illustrating a method related to LTM cell handover procedures according to aspects of this disclosure.

[0054] Figure 11 A schematic diagram illustrating the LTM program within the CU according to aspects of this disclosure.

[0055] Figure 12 A schematic diagram illustrating the CU-to-LTM procedure according to aspects of this disclosure.

[0056] Figure 13 Another schematic diagram illustrating the CU-to-LTM procedure according to aspects of this disclosure. Detailed Implementation

[0057] Generally, when a UE moves from one cell to another, a serving cell change is required at some point. Traditionally, serving cell changes are accomplished through explicit RRC reconfiguration signaling (e.g., handover (HO) commands) used to trigger synchronization of the target cell based on Layer 3 (L3) measurement reports. Compared to beam-level mobility, explicit RRC reconfiguration signaling results in longer latency, greater overhead, and longer downtime. Therefore, in 3GPP, LTM is permitted to change serving cells via L1 / L2 signaling to reduce latency, overhead, and downtime.

[0058] LTM is a procedure in which the BS receives an L1 measurement report from the UE and, based on the report, changes the UE's serving cell via a cell handover command signaled via MACCE. The cell handover command indicates a previously prepared LTM candidate cell configuration provided to the UE via RRC signaling. The UE then hands over to the target cell according to the cell handover command. LTM procedures can be used to reduce mobility latency.

[0059] In some cases, subsequent LTM may be supported. Subsequent LTM refers to the subsequent LTM cell handover procedure between candidate cells, during which the UE does not need to be reconfigured by the network.

[0060] A supervisory timer can be used to detect failures in LTM execution or LTM cell handover procedures. If the LTM supervisory timer expires, the LTM procedure fails, and the UE initiates an RRC connection re-establishment procedure. For example, the conventional T304 timer is used as a supervisory timer to monitor the LTM cell handover procedure.

[0061] "LTM candidate cell" refers to the candidate cell configured for LTM by the UE. Multiple LTM candidate cells can be prepared for the UE, and these LTM candidate cells can belong to the same or different candidate DUs.

[0062] "LTM candidate cell configuration" refers to the configuration associated with an LTM candidate cell. An LTM candidate cell configuration can be a complete LTM candidate cell configuration or a differential configuration relative to an LTM reference configuration. Each LTM candidate cell configuration can be identified by an index, referred to as the LTM candidate cell configuration index, LTM candidate configuration index, or other names. In one instance, the LTM candidate cell configuration index is LTM-CandidateId, which is used to identify the LTM candidate cell configuration.

[0063] "LTM reference configuration" refers to the configuration provided by the network to the UE that is common to all configured LTM candidate cells. The UE uses the LTM reference configuration to generate a complete LTM candidate cell configuration (i.e., by applying the LTM candidate cell configuration on top of the LTM reference configuration).

[0064] "Complete LTM candidate cell configuration" refers to a configuration containing all the necessary fields required to perform the LTM cell handover procedure. This configuration can be the LTM candidate cell configuration itself or generated by applying the LTM candidate cell configuration on top of the LTM reference configuration.

[0065] MCG LTM is a PCell handover procedure triggered by the Media Access Control (MAC) element (CE) based on L1 measurements. SCG LTM is a PSCell handover procedure triggered by the Media Access Control (MAC) element (CE) based on L1 measurements. Potential application scenarios for LTM include "CU-DU LTM", "CU-DU inter-CU LTM", and "CU-inter-CU LTM", as described below. Figures 5A to 5C It is displayed in the middle.

[0066] (1) Intra-CU and intra-DU mobility: UE moves between different cells within a DU.

[0067] (2) Mobility between DUs within a CU: The UE moves between different cells belonging to different DUs but within the same CU.

[0068] (3) Inter-CU mobility: The UE moves between different cells belonging to different DUs and different CUs.

[0069] One objective of mobility enhancements in 3GPP Rel-18 is to specify an LTM procedure (i.e., a PCell or PSCell handover procedure triggered by the network via MAC CE based on L1 measurements). Currently, the following issues regarding LTM procedures need to be considered, including, for example: what the network node's behavior is after the UE performs an intra-CU LTM or inter-CU LTM procedure, and how to enhance the handover preparation phase, for example, via the Xn or F1 interface, to support different functionalities in intra-CU or inter-CU LTM procedures. Currently, details regarding Xn and F1 enhancements for both intra-BS and inter-BS LTM procedures have not been discussed. Embodiments of this disclosure aim to address the aforementioned problems.

[0070] In some embodiments of this disclosure, the UE can receive TCI state activation via the MAC CE activated / deactivated by the candidate cell TCI state of multiple candidate cells (e.g., candidate cell #a and candidate cell #b). After the UE switches to candidate cell #a after receiving an LTM cell handover command, it is necessary to address whether the UE should continue to maintain the activated TCI state of candidate cell #b. This issue aims to address the fact that if the UE is allowed to maintain the activated TCI state after cell handover, the source DU needs to notify the new serving cell because the new serving cell or DU needs to update the TCI state. It is necessary to address how to handle the activated TCI state after intra-CU LTM or inter-CU LTM when the activated TCI state will be maintained, but the details of this solution have not yet been discussed.

[0071] In some embodiments of this disclosure, during the LTM procedure, the source gNB-DU can send an LTM CELLCHANGE NOTIFICATION message to the gNB-CU to indicate to the UE the initiation of an LTM command containing the target cell ID and TCI state ID. Then, the gNB-CU can send the target cell ID and TCI state ID to the target gNB-DU. After a handover within or between LTM cells, the UE will continue to maintain its LTM candidate cell. The problem to be addressed is that the source CU can transfer RACH resources used for early TA acquisition to the target DU of the new serving cell, for example, RACH resources used for early TA acquisition for each candidate cell.

[0072] In some embodiments of this disclosure, the early TA value and additional information (e.g., the remaining value of TAT) stored in the source DU should be transmitted to the target DU via the Xn interface and the F1 interface. For example, after performing inter-CU LTM, the early TA value stored in the source DU can be transmitted to the new service gNB-DU via the Xn interface and the F1 interface.

[0073] In some embodiments of this disclosure, after an inter-CU cell handover toward the target BS, the target BS should be aware of the CSI resource configuration. The problem to be solved is how to obtain the CSI resource configuration. For example, the LTM Channel State Information (CSI) resource configuration is generated by the CU. After performing an inter-CU LTM or Layer 3 (L3) handover, the CSI resource configuration can be transmitted to the target CU.

[0074] In some embodiments of this disclosure, after intra-CU LTM or inter-CU LTM toward the target cell, the CU and DU of the target cell may know the TA IDs measured by the UE of all candidate cells and the no-reset IDs of all candidate cells. For example, the TA IDs measured by the UE of all candidate cells and the no-reset IDs of all candidate cells can be transmitted to the target DU via the Xn interface and the F1 interface.

[0075] In some embodiments of this disclosure, the Xn interface enhancement during the handover preparation phase is designed to support TA ID measurements of the UE in inter-BS LTM.

[0076] In some embodiments of this disclosure, the Xn interface enhancement during the switch preparation phase is designed to support no-reset ID in the inter-BS LTM.

[0077] Further details of embodiments of this disclosure will be described below in conjunction with the accompanying drawings.

[0078] Figure 1 This describes an example of a wireless communication system 100 according to aspects of this disclosure. The wireless communication system 100 may include one or more NEs 102, one or more UEs 104, and a core network (CN) 106. The wireless communication system 100 may support various radio access technologies. In some embodiments, the wireless communication system 100 may be a 4G network, such as an LTE network or an LTE-A network. In some other embodiments, the wireless communication system 100 may be an NR network, such as a 5G network, a 5G-A network, or a 5G Ultra Wideband (5G-UWB) network. In other embodiments, the wireless communication system 100 may be a combination of 4G and 5G networks or other suitable radio access technologies, including IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), and IEEE 802.20. The wireless communication system 100 may support radio access technologies beyond 5G, such as 6G. In addition, the wireless communication system 100 can support technologies such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), or Code Division Multiple Access (CDMA).

[0079] One or more NEs 102 may be distributed throughout a geographic area to form a wireless communication system 100. One or more of the NEs 102 described herein may be, include, or be referred to as a network node, base station, network element, network function, network entity, wireless access network (RAN), NodeB, eNodeB (eNB), next-generation NodeB (gNB), or other suitable terms. NEs 102 and UEs 104 may communicate via a communication link, which may be wireless or wired. For example, NEs 102 and UEs 104 may perform wireless communication (e.g., receiving signaling, transmitting signaling) via a Uu interface.

[0080] NE 102 can provide a geographic coverage area for which NE 102 can support services for one or more UEs 104 within the geographic coverage area. For example, NE 102 and UE 104 can support wireless communication of signals associated with services (e.g., voice, video, packet data, messaging, broadcasting, etc.) using one or more radio access technologies. In some embodiments, NE 102 can be mobile, such as a satellite associated with a non-terrestrial network (NTN). In some embodiments, different geographic coverage areas 112 associated with the same or different radio access technologies can overlap, but different geographic coverage areas can be associated with different NEs 102.

[0081] One or more UEs 104 may be distributed throughout the geographic area of ​​the wireless communication system 100. UE 104 may include or be referred to as a remote unit, mobile device, wireless device, remote device, subscriber device, transmitter device, receiver device, or some other suitable term. In some embodiments, UE 104 may be referred to as a unit, station, terminal, or client, and other instances thereof. Alternatively or additionally, UE 104 may be referred to as an Internet of Things (IoT) device, Internet of Everything (IoE) device, or Machine-Type Communication (MTC) device, and other instances thereof.

[0082] UE 104 may be able to support direct wireless communication with other UE 104 via a communication link. For example, UE 104 may support direct wireless communication with another UE 104 via a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link 114 may be referred to as a sidelink. For example, UE 104 may support direct wireless communication with another UE 104 via a PC5 interface.

[0083] NE 102 may support communication with CN 106 or another NE 102, or both. For example, NE 102 may interface with other NE 102 or CN 106 via one or more backhaul links (e.g., S1, N2, N2, or network interfaces). In some implementations, NE 102 may communicate directly with each other. In some other implementations, NE 102 may communicate with each other indirectly (e.g., via CN 106). In some implementations, one or more NE 102 may include sub-components, such as access network entities, which may be instances of Access Node Controllers (ANCs). The ANC may communicate with one or more UE 104s via one or more other access network transmitting entities, which may be referred to as radio headends, smart radio headends, or transmit-receive points (TRPs).

[0084] CN 106 can support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. CN 106 can be an evolved packet core (EPC) or a 5G core (5GC), which may include control plane entities (e.g., Mobility Management Entity (MME), Access and Mobility Management Function (AMF)) that manage access and mobility, and user plane entities (e.g., Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), or User Plane Function (UPF)) that route packets or interconnects to external networks. In some implementations, the control plane entities may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signaling bearers, etc.) of one or more UEs 104 served by one or more NEs 102 associated with CN106.

[0085] CN 106 can communicate with a packet data network (e.g., via S1, N2, N2, or another network interface) through one or more backhaul links. The packet data network may contain an application server. In some implementations, one or more UEs 104 can communicate with the application server. UE 104 can establish a session (e.g., a Protocol Data Unit (PDU) session or the like) with CN 106 via NE 102. CN 106 can use the established session (e.g., an established PDU session) to route traffic (e.g., control information, data, and the like) between UE 104 and the application server. A PDU session may be an instance of a logical connection between UE 104 and CN 106 (e.g., one or more network functions of CN 106).

[0086] In the wireless communication system 100, NE 102 and UE 104 can use the resources of the wireless communication system 100 (e.g., time resources (e.g., symbols, time slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communication). In some embodiments, NE 102 and UE 104 may support different resource structures. For example, NE 102 and UE 104 may support different frame structures. In some embodiments, such as in 4G, NE 102 and UE 104 may support a single frame structure. In some other embodiments, such as in 5G and other suitable radio access technologies, NE 102 and UE 104 may support various frame structures (i.e., multiple frame structures). NE 102 and UE 104 may support various frame structures based on one or more sets of parameters.

[0087] The wireless communication system 100 may support one or more parameter sets, and the parameter sets may include subcarrier spacing and cyclic prefixes. A first parameter set (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a regular cyclic prefix. In some embodiments, the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one time slot per subframe. A second parameter set (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a regular cyclic prefix. A third parameter set (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a regular cyclic prefix or an extended cyclic prefix. A fourth parameter set (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a regular cyclic prefix. A fifth parameter set (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a regular cyclic prefix.

[0088] Time intervals for resources (such as communication resources) can be organized according to frames (also known as radio frames). Each frame may have a duration, for example, 10 milliseconds (ms). In some embodiments, each frame may contain multiple subframes. For example, each frame may contain 10 subframes, and each subframe may have a duration, for example, 1 ms. In some embodiments, each frame may have the same duration. In some embodiments, each subframe of a frame may have the same duration.

[0089] Alternatively, the time intervals of resources (e.g., communication resources) can be organized according to time slots. For example, a subframe may contain a certain number (e.g., a set of parameters). The number of time slots in each subframe may also depend on one or more parameter sets supported in the wireless communication system 100. For example, the first, second, third, fourth, and fifth parameter sets (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with corresponding subcarrier intervals of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz can respectively utilize one time slot per subframe, two time slots per subframe, four time slots per subframe, eight time slots per subframe, and 16 time slots per subframe. Each time slot may contain a certain number (e.g., a set of parameters) of symbols (e.g., OFDM symbols). In some embodiments, the number (e.g., quantity) of time slots in a subframe may depend on the parameter set. For a conventional cyclic prefix, a time slot may contain 14 symbols. For an extended cyclic prefix (e.g., applicable to a 60 kHz subcarrier spacing), a time slot may contain 12 symbols. The relationship between the number of symbols per time slot, the number of time slots per subframe, and the number of time slots per frame for the regular and extended cyclic prefixes may depend on the parameter set. It should be understood that references to the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) can be used interchangeably between subframes and time slots.

[0090] In the wireless communication system 100, the electromagnetic (EM) spectrum can be divided into various categories, bands, channels, etc., based on frequency or wavelength. For example, the wireless communication system 100 may support one or more operating frequency bands, such as frequency ranges represented as FR1 (410 MHz to 7.125 GHz), FR2 (24.25 GHz to 52.6 GHz), FR3 (7.125 GHz to 24.25 GHz), FR4 (52.6 GHz to 114.25 GHz), FR4a or FR4-1 (52.6 GHz to 71 GHz), and FR5 (114.25 GHz to 300 GHz). In some embodiments, NE 102 and UE 104 may perform wireless communication on one or more of the operating frequency bands. In some embodiments, FR1 may be used by NE 102 and UE 104, as well as other equipment or devices, for cellular communication services (e.g., control information, data). In some implementations, FR2 can be used by NE 102 and UE 104, as well as other equipment or devices, for short-range, high data rate capabilities.

[0091] FR1 can be associated with one or more parameter sets (e.g., at least three parameter sets). For example, FR1 can be associated with: a first parameter set (e.g., μ=0) containing a 15 kHz subcarrier spacing; a second parameter set (e.g., μ=1) containing a 30 kHz subcarrier spacing; and a third parameter set (e.g., μ=2) containing a 60 kHz subcarrier spacing. FR2 can be associated with one or more parameter sets (e.g., at least two parameter sets). For example, FR2 can be associated with: a third parameter set (e.g., μ=2) containing a 60 kHz subcarrier spacing; and a fourth parameter set (e.g., μ=3) containing a 120 kHz subcarrier spacing.

[0092] Figure 2 An example of a UE 200 according to aspects of this disclosure is described. UE 200 may include a processor 202, a memory 204, a controller 206, and a transceiver 208. The processor 202, memory 204, controller 206, or transceiver 208, or various combinations thereof, or various components thereof, may be examples of components for performing the aspects of this disclosure described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, or electrically).

[0093] Processor 202, memory 204, controller 206, or transceiver 208, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may include processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), or other programmable logic devices, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0094] Processor 202 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, ASICs, FPGAs, or any combination thereof). In some embodiments, processor 202 may be configured to operate memory 204. In some other embodiments, memory 204 may be integrated into processor 202. Processor 202 may be configured to execute computer-readable instructions stored in memory 204 to cause UE 200 to perform various functions of this disclosure.

[0095] Memory 204 may comprise volatile or non-volatile memory. Memory 204 may store computer-readable, computer-executable code containing instructions that, when executed by processor 202, cause UE 200 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as this memory 204 or another type of memory. Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates the transfer of computer programs from one place to another. Non-transitory storage media may be any available medium accessible by a general-purpose or special-purpose computer.

[0096] In some implementations, processor 202 and memory 204 coupled to processor 202 may be configured to cause UE 200 to perform one or more of the functions described herein (e.g., instructions stored in memory 204 are executed by processor 202).

[0097] Controller 206 manages the input and output signals of UE 200. Controller 206 can also manage peripheral devices not integrated into UE 200. In some embodiments, controller 206 may utilize an operating system, such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some embodiments, controller 206 may be implemented as part of processor 202.

[0098] In some embodiments, UE 200 may include at least one transceiver 208. In other embodiments, UE 200 may have more than one transceiver 208. Transceiver 208 may represent a wireless transceiver. Transceiver 208 may include one or more receiver chains 210, one or more transmitter chains 212, or a combination thereof. The aforementioned components for receiving in processor 202 or for transmitting in processor 202 may be implemented via at least one transceiver 208.

[0099] Receiver chain 210 may be configured to receive signals (e.g., control information, data, packets) via a wireless medium. For example, receiver chain 210 may include one or more antennas for receiving signals over the air or via a wireless medium. Receiver chain 210 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 210 may include at least one demodulator configured to demodulate the received signal by reversing the modulation technique applied during signal transmission and to obtain the transmitted data. Receiver chain 210 may include at least one decoder for decoding and processing the demodulated signal to receive the transmitted data.

[0100] Transmitter chain 212 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 212 may include at least one modulator for modulating data onto a carrier signal in preparation for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 212 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 212 may also include one or more antennas for transmitting the amplified signal into the air or a wireless medium.

[0101] Figure 3 An example of a processor 300 according to aspects of this disclosure is described. Processor 300 may be an example of a processor configured to perform various operations according to the examples described herein. Processor 300 may include a controller 302 configured to perform various operations according to the examples described herein. Processor 300 may optionally include at least one memory 304, which may be, for example, an L1 / L2 / L3 cache. Additionally or alternatively, processor 300 may optionally include one or more arithmetic logic units (ALUs) 306. One or more of these components may be electronically communicated or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses).

[0102] Processor 300 may be a processor chipset and includes a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receive, acquire, retrieve, transmit, output, forward, store, determine, identify, access, write, read) according to the examples described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to the processor chipset (e.g., processor 300) or included in the processor chipset) or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), static RAM (SRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase-change memory (PCM), and others).

[0103] Controller 302 can be configured to manage and coordinate various operations of processor 300 (e.g., signaling, receiving, acquiring, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, and reading) to enable processor 300 to support various operations according to the examples described herein. For example, controller 302 can operate as a control unit of processor 300, generating control signals that manage the operation of various components of processor 300. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating operation timing.

[0104] Controller 302 may be configured to fetch (e.g., fetch, retrieve, receive) instructions from memory 304 and determine subsequent instructions to be executed to enable processor 300 to support various operations according to the examples described herein. Controller 302 may be configured to track the memory addresses of instructions associated with memory 304. Controller 302 may be configured to decode instructions to determine the operations to be performed and the operands involved. For example, controller 302 may be configured to interpret instructions and determine control signals to be output to other components of processor 300 to enable processor 300 to support various operations according to the examples described herein. Alternatively or additionally, controller 302 may be configured to manage data flow within processor 300. Controller 302 may be configured to control data transfers between registers, arithmetic logic unit (ALU), and other functional units of processor 300.

[0105] Memory 304 may include one or more caches (e.g., memory local to or included in processor 300) or other memories, such as RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some embodiments, memory 304 may reside within or on the processor chipset (e.g., locally to processor 300). In some other embodiments, memory 304 may reside outside the processor chipset (e.g., remotely from processor 300).

[0106] Memory 304 may store computer-readable, computer-executable code containing instructions that, when executed by processor 300, cause processor 300 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. Controller 302 and / or processor 300 may be configured to execute the computer-readable instructions stored in memory 304 to cause processor 300 to perform various functions. For example, processor 300 and / or controller 302 may be coupled to or coupled to memory 304, and processor 300, controller 302, and memory 304 may be configured to perform the various functions described herein. In some instances, processor 300 may include multiple processors, and memory 304 may include multiple memories. One or more of the multiple processors may be coupled to one or more of the multiple memories, which may be individually or jointly configured to perform the various functions described herein.

[0107] One or more ALUs 306 may be configured to support various operations according to the examples described herein. In some embodiments, one or more ALUs 306 may reside within or on a processor chipset (e.g., processor 300). In some other embodiments, one or more ALUs 306 may reside outside the processor chipset (e.g., processor 300). One or more ALUs 306 may perform one or more computations on data, such as addition, subtraction, multiplication, and division. For example, one or more ALUs 306 may receive input operands and opcodes, which determine the operation to be performed. One or more ALUs 306 are configured with various logic and arithmetic circuitry, including adders, subtractors, shifters, and logic gates, to process and manipulate data according to the operation. Alternatively, one or more ALU 306s may support logical operations such as AND, OR, XOR, NOR, and NAND, enabling one or more ALU 306s to handle conditional operations, comparisons, and bitwise operations.

[0108] Processor 300 can support wireless communication according to the examples disclosed herein.

[0109] In some implementations, processor 300 may be configured to support the execution of [specific actions / functions]. Figure 6 The described operation is a component. For example, processor 300 may be configured or operable to support: a component for receiving first information related to one or more candidate cells from a source DU of a first BS, the one or more candidate cells being associated with an LTM cell handover of the UE from a source cell of the source DU toward the first candidate cell; and a component for transmitting both the second information related to the one or more candidate cells and the received first information to a candidate DU of the first BS or a second CU of the second BS, wherein the first candidate cell is associated with the candidate DU or the second CU.

[0110] In some implementations, processor 300 may be configured to support the execution of [specific actions / functions]. Figure 7 The components of the described operation. For example, processor 300 may be configured or operable to support: components for determining an LTM cell handover that triggers the UE to perform an LTM cell handover from a source cell of a source DU of a first BS to a first candidate cell; and components for transmitting first information related to one or more candidate cells associated with the LTM cell handover to a first CU of the first BS, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of the second BS.

[0111] In some implementations, processor 300 may be configured to support the execution of [specific actions / functions]. Figure 8 The described operation is a component. For example, processor 300 may be configured or operable to support: a component for receiving information related to one or more candidate cells from a first CU of a first BS, the one or more candidate cells being associated with an LTM cell handover of the UE from a source cell of a source DU of the first BS toward a first candidate cell; and a component for transmitting the received information to a candidate DU of a second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: first information transmitted from the source DU to the first CU; and second information transmitted from the first CU.

[0112] In some implementations, processor 300 may be configured to support the execution of [specific actions / functions]. Figure 9 The components of the described operation. For example, the processor 300 may be configured or operable to support: components for transmitting to the second BS a request related to a UE-based TA measurement or Layer 2 (L2) reset for an LTM cell handover from the source cell of the first BS to the first candidate cell of the second BS; and components for receiving from the second BS a response related to a UE-based TA measurement or L2 reset.

[0113] In some additional implementations, the processor 300 may be configured to support the execution of [specific actions / functions]. Figure 10 The components of the described operation. For example, the processor 300 may be configured or operable to support: components for receiving from the first BS a request related to a UE-based TA measurement or Layer 2 (L2) reset for an LTM cell handover from the source cell of the first BS to a first candidate cell of the second BS; and components for transmitting to the first BS a response related to a UE-based TA measurement or L2 reset.

[0114] Those skilled in the art will understand that components in the exemplary processor 300 can be changed; for example, some components in the exemplary processor 300 can be omitted or modified, or new components can be added to the exemplary processor 300, without departing from the spirit and scope of this disclosure. For instance, in some embodiments, the processor 300 may not include an ALU 306.

[0115] Figure 4 An example of NE 400 according to aspects of this disclosure is described. NE 400 may include a processor 402, a memory 404, a controller 406, and a transceiver 408. The processor 402, memory 404, controller 406, or transceiver 408, or various combinations thereof, or various components thereof, may be examples of components for performing the aspects of this disclosure described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, electrically).

[0116] Processor 402, memory 404, controller 406, or transceiver 408, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may include processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), or other programmable logic devices, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0117] Processor 402 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, ASICs, FPGAs, or any combination thereof). In some embodiments, processor 402 may be configured to operate memory 404. In some other embodiments, memory 404 may be integrated into processor 402. Processor 402 may be configured to execute computer-readable instructions stored in memory 404 to cause NE 400 to perform various functions of this disclosure.

[0118] Memory 404 may comprise volatile or non-volatile memory. Memory 404 may store computer-readable, computer-executable code containing instructions that, when executed by processor 402, cause NE 400 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as this memory 404 or another type of memory. Computer-readable media include both non-transitory computer storage media and communication media, encompassing any medium that facilitates the transfer of computer programs from one place to another. Non-transitory storage media may be any available medium accessible by a general-purpose or special-purpose computer.

[0119] In some implementations, processor 402 and memory 404 coupled to processor 402 may be configured to cause NE 400 to perform one or more of the functions described herein (e.g., instructions stored in memory 404 are executed by processor 402). For example, processor 402 may support wireless communication at NE 400 according to the examples disclosed herein. For example, NE 400 may be configured to support the execution of instructions regarding... Figure 6 The components of the operation described or the operation of the candidate target SN described below.

[0120] In some implementations, NE 400 may be a first CU of a first BS. NE 400 may be configured to support: means for receiving first information associated with one or more candidate cells from a source DU of the first BS, the one or more candidate cells being associated with an LTM cell handover of the UE from a source cell of the source DU toward the first candidate cell; and means for transmitting both the second information associated with the one or more candidate cells and the received first information to a candidate DU of the first BS or a second CU of the second BS, wherein the first candidate cell is associated with a candidate DU or the second CU.

[0121] In some implementations, NE 400 may be a source DU of a first BS and configured to support: means for determining an LTM cell handover that triggers the UE to perform an LTM cell handover from the source cell of the source DU of the first BS to a first candidate cell; and means for transmitting first information related to one or more candidate cells associated with the LTM cell handover to a first CU of the first BS, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of the second BS.

[0122] In some implementations, NE 400 may be a second CU of a second BS and configured to support: a component for receiving information related to one or more candidate cells from a first CU of a first BS, the one or more candidate cells being associated with an LTM cell handover of the UE from a source cell of a source DU of the first BS toward a first candidate cell; and a component for transmitting the received information to a candidate DU of the second BS, wherein the first candidate cell is associated with a candidate DU, and wherein the received information includes: first information transmitted from the source DU to the first CU; and second information transmitted from the first CU.

[0123] In some implementations, NE 400 may be a first BS and configured to support: components for transmitting to a second BS a request related to a UE-based TA measurement or Layer 2 (L2) reset for an LTM cell handover from the source cell of the first BS to a first candidate cell of the second BS; and components for receiving from the second BS a response related to a UE-based TA measurement or L2 reset.

[0124] In some additional embodiments, NE 400 may be a second BS and configured to support: components for receiving from the first BS a request related to a UE-based TA measurement or Layer 2 (L2) reset for an LTM cell handover from the source cell of the first BS to a first candidate cell of the second BS; and components for transmitting to the first BS a response related to a UE-based TA measurement or L2 reset.

[0125] Controller 406 manages the input and output signals of NE 400. Controller 406 can also manage peripheral devices not integrated into NE 400. In some embodiments, controller 406 may utilize an operating system such as iOS®, Android®, Windows®, or other operating systems. In some embodiments, controller 406 may be implemented as part of processor 402.

[0126] In some embodiments, NE 400 may include at least one transceiver 408. In other embodiments, NE 400 may have more than one transceiver 408. Transceiver 408 may represent a wireless transceiver. Transceiver 408 may include one or more receiver chains 410, one or more transmitter chains 412, or a combination thereof. The aforementioned receiving or transmitting components in processor 402 may be implemented via at least one transceiver 408.

[0127] Receiver chain 410 may be configured to receive signals (e.g., control information, data, packets) via a wireless medium. For example, receiver chain 410 may include one or more antennas for receiving signals over the air or via a wireless medium. Receiver chain 410 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 410 may include at least one demodulator configured to demodulate the received signal by reversing the modulation technique applied during signal transmission and to obtain the transmitted data. Receiver chain 410 may include at least one decoder for decoding and processing the demodulated signal to receive the transmitted data.

[0128] Transmitter chain 412 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 412 may include at least one modulator for modulating data onto a carrier signal in preparation for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 412 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 412 may also include one or more antennas for transmitting the amplified signal into the air or a wireless medium.

[0129] Those skilled in the art will understand that components in the exemplary NE 400 can be changed; for example, some components in the exemplary NE 400 can be omitted or modified, or new components can be added to the exemplary NE 400, without departing from the spirit and scope of this disclosure. For instance, in some embodiments, the NE 400 may not include the controller 406.

[0130] Figure 5A A schematic diagram illustrating a mobility scenario within a CU and DU according to aspects of this disclosure. Figure 5A The wireless communication system includes a DU, UEs (e.g., UE 101A), and several access nodes (e.g., access node 102A and access node 103A). Access nodes 102A and 103A are controlled by the DU and provide services to UEs in cell #1 and cell #2, respectively. Although Figure 5A There may be only one UE and two access nodes in the system, but those skilled in the art should recognize that any number of UEs and access nodes may be included in a wireless communication system.

[0131] exist Figure 5A In the scenario described, UE 101A is moving from cell #1 to cell #2 and can perform a handover procedure from cell #1 to cell #2, which is a handover procedure performed between different cells within a DU. This scenario can be referred to as intra-CU / intra-DU mobility. In simpler terms, this scenario can be called intra-DU mobility.

[0132] Figure 5B A schematic diagram illustrating a scenario of mobility between DUs within a CU according to aspects of this disclosure. Figure 5B The wireless communication system includes a CU, UEs (e.g., UE 101B), and several DUs (e.g., DU 1#1 and DU #2). DU #1 and DU #2 are controlled by the CU and provide services to UEs in cell #A and cell #B, respectively. Although Figure 5B There may be only one UE and two DUs in the system, but those skilled in the art should recognize that any number of UEs and DUs may be included in a wireless communication system.

[0133] exist Figure 5B In the scenario described, UE 101B is moving from cell #A to cell #B and can perform a handover procedure from cell #A to cell #B. This handover procedure occurs between different cells belonging to different DUs but within the same CU. This scenario can be referred to as intra-CU inter-DU mobility. In simpler terms, this scenario can be called inter-DU mobility.

[0134] Figure 5C A schematic diagram illustrating a scenario of inter-CU mobility according to aspects of this disclosure. Figure 5CThe wireless communication system includes several CUs (e.g., CU #1 and CU #2), UEs (e.g., UE 101C), and several DUs (e.g., DU #A and DU #B). DU #A is controlled by CU #1 and provides services to UEs in cell #X. DU #B is controlled by CU #2 and provides services to UEs in cell #Y. Although Figure 5C There may be only one UE, two DUs and two CUs, but those skilled in the art should recognize that any number of UEs, DUs and CUs may be included in a wireless communication system.

[0135] exist Figure 5C In this scenario, UE 101C is moving from cell #X to cell #Y and can execute a handover procedure from cell #X to cell #Y. This handover procedure is performed between different cells belonging to different DUs within different CUs. This scenario can be referred to as inter-CU mobility.

[0136] Figure 6 A flowchart illustrating a method related to an LTM cell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by a network node, as described herein. In some embodiments, the network node can be a CU of a BS, and can execute a set of instructions to control the functional elements of the CU to perform the described functions. In some embodiments, aspects of operations 602 and 604 can be referenced from... Figure 4 The described NE 400 is executed. Each of operations 602 and 604 can be executed according to the instance described herein. Specific instances are... Figure 11 and Figure 13 The embodiments are described below.

[0137] In operation 602, the method may include receiving information (referred to as "information #1") related to one or more candidate cells from a source DU of BS #1 by a CU of BS (referred to as "BS #1"), the one or more candidate cells being associated with an LTM cell handover of the UE from the source cell of the source DU of BS #1 toward a candidate cell (referred to as "candidate cell #1", which may also be referred to as the target cell or candidate target cell).

[0138] In operation 604, the method may include transmitting both information (referred to as "information #2") and information #1 from the CU of BS #1 to a candidate DU of BS #1 or the CU of another BS (referred to as BS #2) that is associated with one or more candidate cells. For example, in an intra-CU mobility scenario, candidate cell #1 may be associated with a candidate DU of BS #1. For example, in an inter-CU mobility scenario, candidate cell #1 may be associated with BS #2.

[0139] In some implementations, candidate cell #1 is a candidate PCell, for example, the UE accesses the BS only via MCG (i.e., BS #1). In other implementations, candidate cell #1 is a candidate PSCell, for example, the UE accesses the BS via dual connectivity (DC) scenario.

[0140] In some implementations, information #1 includes at least one of the following:

[0141] (1) Activated Transmit Configuration Indicator (TCI) status information associated with one or more candidate cells;

[0142] (2) Random access channel (RACH) resource information used for early timing advance (TA) acquisition associated with one or more candidate cells;

[0143] (3) One or more early TA values ​​associated with one or more candidate cells;

[0144] (4) Remaining length information of one or more early TA values ​​of the time-aligned timer (TAT);

[0145] (5) Identifier (ID) information for one or more candidate cells;

[0146] (6) The ID information of candidate cell #1, such as the target cell ID; or

[0147] (7) UE ID information, such as UE ID.

[0148] In some implementations, information #2 includes at least one of the following:

[0149] (1) One or more early TA values ​​associated with one or more candidate cells.

[0150] (2) Remaining length information of one or more early TA values ​​of time-aligned timers (TATs).

[0151] (3) LTM Channel State Information (CSI) resource configuration information.

[0152] (4) TA IDs of one or more candidate cells measured by the UE, such as TA IDs measured by the UE.

[0153] (5) No Layer 2 (L2) reset ID for one or more candidate cells, for example, no reset ID.

[0154] For example, in some embodiments of this disclosure, the TA ID of the UE measurement for the serving cell may be represented as “ltm-ServingCellUE-MeasuredTA-ID” configured in the LTM-Config Information Element (IE). This IE is used by the UE to determine whether a UE-based TA measurement should be performed when an LTM cell handover procedure toward an LTM candidate cell is triggered. When the UE receives an LTM cell handover command toward a candidate cell, if the value of ltm-UE-MeasuredTA-ID contained in the LTM-Candidate IE is equal to the value of ltm-ServingCellUE-MeasuredTA-ID, the UE's AS layer may notify the lower layers that a UE-based TA measurement should be performed. Otherwise, the UE may replace the value of ltm-ServingCellUE-MeasuredTA-ID with the value of ltm-UE-MeasuredTA-ID in the LTM-Candidate.

[0155] In some embodiments of this disclosure, the TA ID of the UE measurement of the candidate cell may be represented as ltm-UE-MeasuredTA-ID or similar.

[0156] LTM no-reset operation means that when the UE performs an LTM cell handover from the source cell to a candidate cell, the UE does not perform an L2 reset operation on the candidate cell. For example, in some embodiments of this disclosure, the no-reset ID of the serving cell may be represented as "ltm-ServingCellNoResetID" configured in the LTM-Config IE. This field is used by the UE to determine whether an L2 reset should be performed when an LTM cell handover procedure toward an LTM candidate cell is triggered. When the UE receives an LTM cell handover command toward a candidate cell, if the value of ltm-NoResetID contained in the LTM-Candidate IE is equal to the value of ltm-ServingCellNoResetID, then the UE can continue to use the current RLC entity. Otherwise, the UE can replace the value of ltm-ServingCellNoResetID with the value of ltm-NoResetID in the LTM-Candidate.

[0157] In some embodiments of this disclosure, the NoReset ID of a candidate cell may be represented as ltm-NoResetID or similar.

[0158] In some implementations, information #1 and information #2 may be received or transmitted via at least one of the following:

[0159] (1) RRC message transmission;

[0160] (2) RRC delivers report messages;

[0161] (3) UE context modification requires a message; or

[0162] (4) UE context modification request message.

[0163] In the implementation scheme, information #1 is received after the source DU of BS #1 is configured to transmit a cell handover command to the UE to trigger LTM cell handover.

[0164] In the implementation plan, information #1 and information #2 are transmitted after the CU of BS #1 receives the indication that LTM cell handover has been completed.

[0165] It should be noted that Figure 6 The methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementations are possible without departing from the spirit and scope of this disclosure.

[0166] Figure 7 A flowchart illustrating a method related to an LTM cell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by a network node, as described herein. In some embodiments, the network node can be a source DU of the BS and can execute a set of instructions to control the functional elements of the source DU to perform the described functions. In some embodiments, aspects of operations 702 and 704 can be referenced from... Figure 4 The described NE 400 is executed. Each of operations 702 and 704 can be executed according to the instance described herein. Specific instances are... Figure 11 and Figure 13 The embodiments are described below.

[0167] In operation 702, the method may include a BS (e.g., in...) Figure 6 The source DU (BS #1) described in the embodiments triggers the UE to perform a process from the source cell of the source DU of BS #1 toward the candidate cell (e.g., in...). Figure 6 The LTM cell handover of "candidate cell #1" described in the embodiments.

[0168] For example, in intra-CU mobility scenarios, candidate cell #1 can be associated with candidate DU of BS #1. For example, in inter-CU mobility scenarios, candidate cell #1 can be associated with another BS (e.g., in...). Figure 6 The CU related to "BS #2" described in the embodiments.

[0169] In some implementations, candidate cell #1 is a candidate PCell, for example, the UE accesses the service BS only via MCG (i.e., BS #1). In other implementations, candidate cell #1 is a candidate PSCell, for example, the UE accesses the service BS via DC scenario.

[0170] In operation 704, the method may include transmitting information related to one or more candidate cells associated with LTM cell handover from the source DU of BS #1 to the CU of BS #1 (e.g., in...). Figure 6 (Information #1 as described in the embodiments).

[0171] For example, information #1 may contain... Figure 6 The same elements are described in the embodiments. In some embodiments, information #1 is transmitted via at least one of the following:

[0172] (1) RRC message transmission;

[0173] (2) RRC delivers a report message; or

[0174] (3) UE context modification requires a message.

[0175] It should be noted that Figure 7 The methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementations are possible without departing from the spirit and scope of this disclosure.

[0176] Figure 8 A flowchart illustrating a method related to an LTM cell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by a network node, as described herein. In some embodiments, the network node may be a CU of the BS (e.g., a candidate CU in an inter-CU mobility scenario) and may execute a set of instructions to control the functional elements of the CU to perform the described functions. In some embodiments, aspects of operations 802 and 804 may be referenced from... Figure 4 The NE 400 described is executed. Each of operations 802 and 804 can be executed according to the instance described herein. Specific instances are... Figure 11 and Figure 13 The embodiments are described below.

[0177] In operation 802, the method may include a method defined by a BS (e.g., in...). Figure 6 The CU (e.g., candidate CU) of “BS #2” described in the embodiments is from another BS (e.g., in Figure 6The CU (e.g., source CU) of “BS #1” described in the embodiments receives information related to one or more candidate cells, which are associated with the UE from the source cell of the source DU of BS #1 toward the candidate cells (e.g., in…). Figure 6 The LTM cell handover associated with "candidate cell #1" described in the embodiments.

[0178] In some implementations, the information at operation 802 is received via at least one of the following:

[0179] (1) RRC message transmission;

[0180] (2) RRC delivers a report message; or

[0181] (3) UE context modification request message.

[0182] In operation 804, the method may include transmitting received information from the CU of BS #2 to a candidate DU of BS #2. Candidate cell #1 may be associated with a candidate DU of BS #2. In some implementations, candidate cell #1 is a candidate PCell, for example, the UE accesses the serving BS only via MCG (i.e., BS #1). In some other implementations, candidate cell #1 is a candidate PSCell, for example, the UE accesses the serving BS via DC scenario.

[0183] In some implementations, the information received at operation 802 includes:

[0184] (1) Information transmitted from source DU to CU of BS #1 (e.g., in Figure 6 The “information #1” described in the embodiments; and

[0185] (2) Information transmitted from the CU of BS #1 (e.g., in Figure 6 (Information #2 as described in the embodiments). For example, Information #2 is stored at the source CU of BS #1 and emitted from the CU of BS #1.

[0186] For example, information #1 or information #2 may contain information related to... Figure 6 The same elements described in the embodiments.

[0187] It should be noted that Figure 8 The methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementations are possible without departing from the spirit and scope of this disclosure.

[0188] Figure 9A flowchart illustrating a method related to an LTM cell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by a network node, as described herein. In some embodiments, the network node can be a BS (e.g., a source BS or source CU in an inter-CU mobility scenario) and can execute a set of instructions to control the functional elements of the BS to perform the described functions. In some embodiments, aspects of operations 902 and 904 can be referenced from... Figure 4 The NE 400 described is executed. Each of operations 902 and 904 can be executed according to the instance described herein. Specific instances are... Figure 12 and Figure 13 The embodiments are described below.

[0189] In operation 902, the method may include a BS (e.g., in...) Figure 6 The “BS #1” described in the embodiments is sent to another BS (e.g., in Figure 6 The embodiment described in "BS #2" transmits to the candidate cell of BS #2 from the source cell of BS #1 toward BS #2 (e.g., in...). Figure 6 The LTM cell handover request for “candidate cell #1” described in the embodiments is based on UE TA measurement or Layer 2 (L2) reset related to the UE.

[0190] In operation 904, the method may include BS #1 receiving a response from BS #2 related to UE-based TA measurement or no L2 reset.

[0191] In some implementations, candidate cell #1 is a candidate PCell, for example, the UE accesses the service BS only via MCG (i.e., BS #1). In other implementations, candidate cell #1 is a candidate PSCell, for example, the UE accesses the service BS via DC scenario.

[0192] For example, the request at operation 902 could be a switching request. In some implementations, the request at operation 902 includes at least one of the following:

[0193] (1) Request BS #2 to provide information on the candidate cell list, wherein when performing an LTM cell handover from the source cell to a candidate cell in the candidate cell list, the UE can obtain the TA value of the candidate cell in the candidate cell list by performing UE-based TA measurement;

[0194] (2) Request BS #2 to indicate whether the candidate cell of BS #2 (referred to as "candidate cell #2") has the same candidate DU information as one or more candidate cells of BS #2 (e.g., one or more candidate cells configured to the UE), wherein when performing an LTM cell handover from the source cell to candidate cell #2, the UE can obtain the TA value of candidate cell #2 by performing UE-based TA measurement;

[0195] (3) Request BS #2 to provide information on the IDs of candidate DUs related to candidate cell #2; or

[0196] (4) Reserve the ID range of TA measured by the UE for one or more candidate cells of BS #2, for example, reserve the ID range of candidate cells of BS #2 based on UE TA measurement.

[0197] In the implementation scheme, if candidate cell #2 has one or more candidate DUs that are the same as candidate cells BS #2, then the request further includes the ID information of candidate cell #2, such as cell ID.

[0198] In some implementations, the request at operation 902 includes at least one of the following:

[0199] (1) Request BS #2 to provide information on the candidate cell list, wherein when the UE performs an LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an L2 reset for each candidate cell in the candidate cell list (i.e., no reset).

[0200] (2) Request BS #2 to indicate whether the candidate cell of BS #2 (referred to as "candidate cell #3") has the same candidate DU information as one or more candidate cells of BS #2 (e.g., one or more candidate cells configured for the UE), wherein when the UE performs an LTM cell handover from the source cell to candidate cell #3, the UE does not perform an L2 reset of candidate cell #3 (i.e., no reset).

[0201] (3) Request BS #2 to provide information on the IDs of candidate DUs related to candidate cell #3; or

[0202] (4) A range of candidate cell IDs reserved for a set of candidate cells without L2 reset, for example, a range of candidate cell IDs reserved for a UE that does not perform an L2 reset operation.

[0203] In the implementation scheme, if candidate cell #3 has one or more candidate DUs that are the same as candidate cells BS #2, then the request further includes the ID information of candidate cell #3.

[0204] In some implementations, the response at operation 904 includes at least one of the following:

[0205] (1) Candidate cell list, wherein when performing an LTM cell handover from the source cell to a candidate cell in the candidate cell list, the UE can obtain the TA value of the candidate cell in the candidate cell list by performing TA measurement based on the UE;

[0206] (2) Indicates whether the candidate cell of BS #2 (referred to as "candidate cell #4") has the same candidate DU information as one or more candidate cells of BS #2 (e.g., one or more candidate cells configured to the UE), wherein when performing an LTM cell handover from the source cell to candidate cell #4, the UE can obtain the TA value of candidate cell #4 by performing UE-based TA measurement;

[0207] (3) ID information of the candidate DU associated with candidate cell #4; or

[0208] (4) The range of TA IDs for UE measurements reserved for one or more candidate cells of BS #2.

[0209] In the implementation scheme, if candidate cell #4 has one or more candidate DUs that are the same as candidate cells BS #2, then the response further includes the ID information of candidate cell #4.

[0210] In some implementations, the response at operation 904 includes at least one of the following:

[0211] (1) Candidate cell list, wherein when the UE performs an LTM cell handover from the source cell to each candidate cell in the candidate cell list, the UE does not perform an L2 reset for each candidate cell in the candidate cell list;

[0212] (2) Indicate whether the candidate cell of BS #2 (represented as "candidate cell #5") has the same candidate DU information as one or more candidate cells of BS #2 (e.g., one or more candidate cells configured for the UE), wherein when the UE performs an LTM cell handover from the source cell to candidate cell #5, the UE does not perform an L2 reset of candidate cell #5;

[0213] (3) ID information of the candidate DU associated with candidate cell #5; or

[0214] (4) is the range of IDs for a group of candidate cells that are not reserved for L2 reset.

[0215] In the implementation scheme, if candidate cell #5 has the same candidate DU as one or more candidate cells of BS #2, then the response further includes the ID information of candidate cell #5.

[0216] It should be noted that Figure 9 The methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementations are possible without departing from the spirit and scope of this disclosure.

[0217] Figure 10 A flowchart illustrating a method related to an LTM cell handover procedure according to aspects of this disclosure is provided. The operation of the method can be implemented by a network node, as described herein. In some embodiments, the network node may be a BS (e.g., a candidate BS or candidate CU in an inter-CU mobility scenario) and may execute a set of instructions to control the functional elements of the BS to perform the described functions. In some embodiments, aspects of operations 1002 and 1004 may be referenced from... Figure 4 The described NE 400 is executed. Each of operations 1002 and 1004 can be executed according to the instance described herein. Specific instances are... Figure 12 and Figure 13 The embodiments are described below.

[0218] In operation 1002, the method may include a BS (e.g., in...) Figure 6 The “BS #2” described in the embodiments is from another BS (e.g., in Figure 6 The embodiment described in "BS #1" receives candidate cells from the source cell of BS #1 toward BS #2 (e.g., in...). Figure 6 The LTM cell handover request for “candidate cell #1” described in the embodiments is based on UE TA measurement or Layer 2 (L2) reset related to the UE.

[0219] In some implementations, candidate cell #1 is a candidate PCell, for example, the UE accesses the service BS only via MCG (i.e., BS #1). In other implementations, candidate cell #1 is a candidate PSCell, for example, the UE accesses the service BS via DC scenario.

[0220] In operation 1004, the method may include BS #2 transmitting a response to BS #1 related to UE-based TA measurement or no L2 reset.

[0221] In some implementations, the request at operation 1002 may include elements related to... Figure 9 The elements are the same as those in the request at operation 902 described in the embodiments. In some embodiments, the response at operation 1004 may contain the same elements as those in... Figure 9 The elements in the response at operation 904 described in the embodiment are the same as the elements in the response.

[0222] It should be noted that Figure 10The methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise exempted or modified, and other implementations are possible without departing from the spirit and scope of this disclosure.

[0223] Figure 11 This illustration shows a schematic diagram of an LTM procedure within a CU according to an aspect of this disclosure. The details described in all other embodiments of this disclosure are applicable. Figure 11 The embodiments shown in the figure.

[0224] like Figure 11 As shown in BS 1105 (for example, in Figure 6 The BS #1 described in the embodiment is in a CU-DU architecture and includes a source DU 1102, a candidate DU 1103, and a CU 1104. Figure 11 In the embodiments described, the cell handover operation performed by UE 1101 refers to a mobility scenario within a CU, where the source cell and the target cell are in the same CU. For example, source DU 1102 and candidate DU 1103 are managed by the same CU 1104.

[0225] exist Figure 11 In the exemplary flowchart 1100 shown, during operation 111, UE 1101 can access the serving BS (e.g., BS 1105) via MCG only or via DC scenario. UE 1101 can send measurement reports to the serving BS. The serving BS may contain a CU (e.g., gNB-CU) and one or more DUs (e.g., gNB-DU). The serving cell is associated with the CU and DU. An F1 interface exists between the DU and the CU. For example, in the context of MCG LTM procedures... Figure 11 In some embodiments, BS 1105 is an MCG BS (e.g., an MCG gNB) and includes CU 1104, source DU 1102, and candidate DU 1103. BS 1105 may include one or more other candidate DUs. Figure 11 (Not shown in the text). In some implementations, UE 1101 may send measurement reports to CU 1104 via source DU 1102.

[0226] In operation 112, the source CU 1104 of the service BS 1105 (MCG or SCG) can determine to initiate an inter-cell mobility configuration procedure based on L1 / L2, that is, to make an inter-cell mobility configuration decision based on L1 / L2.

[0227] In operation 113, CU 1104 will prepare LTM candidate cell configuration for one or more candidate cells. For example, CU 1104 may receive RACH resources and corresponding candidate cells for early TA acquisition from each candidate DU (including candidate DU 1103).

[0228] In operation 114, CU 1104 transmits the LTM cell configuration to source DU 1102. BS 1105 can generate an RRC reconfiguration message based on the configuration from the candidate cells and transmit the RRC reconfiguration message to UE 1101. The RRC reconfiguration message contains the candidate cell configuration for LTM.

[0229] In operation 115, source DU 1102 transmits RRC reconfiguration messages associated with one or more candidate cells in the LTM configuration to UE 1101. In some embodiments, source DU 1102 may also transmit MAC CE to activate the TCI state (beam) of some candidate cells.

[0230] In operation 116, source DU 1102 transmits an LTM cell handover command to UE 1101. For example, the LTM cell handover command includes the ID information of a candidate target cell (i.e., the target cell, such as candidate cell #1) belonging to candidate DU 1103. Candidate cell #1 and the source cell of source DU 1102 both originate from the same CU 1104, i.e., within a CU's mobility scenario. UE 1101 can perform an LTM cell handover toward candidate cell #1 in response to receiving the LTM cell handover command.

[0231] In operation 117, source DU 1102 may transmit at least one of the following messages to CU 1104 via the F1 interface. The F1 message carrying this message may be an RRC message transmission message, an RRC delivery report message, or a UE context modification request message.

[0232] (1) The activated TCI state of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0233] (2) RACH resources for early TA acquisition from one or more candidate cells (e.g., candidate cells other than candidate cell #1); or

[0234] (3) Early TA values ​​and / or remaining TAT values ​​of one or more candidate cells (e.g., candidate cells other than candidate cell #1). For example, source DU 1102 may receive early TA values ​​of one or more candidate cells from candidate DU via CU 1104.

[0235] In operation 118, after CU 1104 receives the aforementioned information from source DU 1102, CU 1104 will transmit at least one of this information to the candidate DU (e.g., candidate DU 1103) of the candidate (new serving) cell via the F1 interface. Candidate DU 1103 serving candidate cell #1 to which UE 1101 is handover will receive this information from CU 1104. The F1 message can be an RRC message transmission message, an RRC delivery report message, or a UE context modification request message.

[0236] Figure 12 A schematic diagram illustrating an inter-CU LTM procedure according to aspects of this disclosure. The details described in all other embodiments of this disclosure are applicable. Figure 12 The embodiments shown in the figure.

[0237] like Figure 12 As shown, BS 1204 is in a CU-DU architecture and includes source DU 1202 and source CU 1203. BS 1207 is in a CU-DU architecture and includes candidate CU 1206 and candidate DU 1205. BS 1207 may include one or more other candidate DUs. Figure 12 (Not shown in the text).

[0238] exist Figure 12 In the embodiments described, the cell handover operation performed by UE 1201 refers to an inter-CU mobility scenario, where the source cell and the target cell are located at different CUs. For example, as Figure 12 As shown, source DU 1202 and candidate DU 1205 are managed by different CUs (i.e., source CU 1203 and candidate CU 1206).

[0239] exist Figure 12 In the exemplary flowchart 1200 shown, during operation 121, UE 1201 can access the service BS (e.g., BS 1204) via MCG only or via DC scenario (e.g., in...). Figure 9 The BS (#1) described in the embodiment. UE 1201 can send measurement reports to the serving BS. The serving BS may include a CU (e.g., gNB-CU) and one or more DUs (e.g., gNB-DU). The serving cell is associated with the CU and DU. There is an F1 interface between the DU and the CU. For example, in the context of MCG LTM procedures... Figure 12 In some embodiments, BS 1204 is an MCG BS (e.g., an MCG gNB). In some implementations, UE 1201 may send measurement reports to source CU 1203 via source DU 1202.

[0240] In operation 122, the source CU 1203 of service BS 1204 (MCG or SCG) can determine to initiate an inter-cell mobility configuration procedure based on L1 / L2, that is, to make an inter-cell mobility configuration decision based on L1 / L2.

[0241] In operation 123, source CU 1203 can send to BS 1207 (e.g., in...). Figure 9 The candidate CU 1206 of BS #2 described in the embodiment transmits a handover request for LTM preparation.

[0242] For example, in some embodiments, the switching request in operation 123 may include at least one of the following:

[0243] (1) Requesting BS 1207 to provide information on a candidate cell list, wherein when performing an LTM cell handover from the source cell of BS 1204 to a candidate cell in the candidate cell list, UE 1201 can obtain the TA value of the candidate cell in the candidate cell list by performing UE-based TA measurement. For example, this information is used to request a candidate gNB or CU to provide a candidate cell list on which the UE can obtain the TA value via UE-based measurement TA of the candidate cell included in the handover request.

[0244] (2) Request BS 1207 to indicate BS 1207's candidate cells (e.g., in... Figure 9 The embodiments described herein include information on whether candidate cell #2 has the same candidate DU as one or more candidate cells of BS 1207 (e.g., one or more candidate cells configured for UE 1201), wherein when performing an LTM cell handover from the source cell of BS 1204 to candidate cell #2 of BS 1207, UE 1201 can obtain the TA value of candidate cell #2 by performing UE-based TA measurements. For example, if candidate cell #2 has the same candidate DU as one or more candidate cells of BS 1207, then the handover request further includes ID information of candidate cell #2. For example, this information is used to request the candidate gNB or CU to indicate whether the candidate cell has the same candidate DU as the candidate cell of this UE. If the candidate has the same candidate DU as the candidate cell, then the cell ID can also be provided by the candidate gNB or CU. The cell ID can be a Physical Cell Identifier (PCI).

[0245] (3) Information requesting BS 1207 to provide the ID information of a candidate DU (e.g., candidate DU 1205) associated with candidate cell #2. For example, this information is used to request the target gNB or CU to provide the ID of the candidate DU associated with the candidate cell. The target gNB or CU can provide the ID or index of the candidate DU. Then, the source gNB or CU can distinguish whether the candidate cell is the same as or different from the candidate cell.

[0246] (4) A range of IDs for TAs measured by the UE reserved for one or more candidate cells of BS 1207 (e.g., one or more candidate cells configured for UE 1201). For example, the source gNB or CU transmits the reserved range of IDs for TAs measured by the UE to each candidate gNB. Each candidate gNB may set an ID for each candidate cell belonging to this gNB.

[0247] In some embodiments, the switching request in operation 123 may include at least one of the following:

[0248] (1) Request BS 1207 to provide information on a candidate cell list, wherein when UE 1201 performs an LTM cell handover from the source cell of BS 1204 to each candidate cell in the candidate cell list, UE 1201 does not perform an L2 reset for each candidate cell in the candidate cell list. For example, this information is used to request the target gNB or CU to provide a candidate cell list on which the UE can perform no reset for the candidate cells included in the handover request.

[0249] (2) Request BS 1207 to indicate BS 1207's candidate cells (e.g., in... Figure 9 The embodiment describes whether candidate cell #3 has the same candidate DU as one or more candidate cells of BS 1207 (e.g., candidate cells configured for UE 1201), wherein when UE 1201 performs an LTM cell handover from the source cell of BS 1204 to candidate cell #3, UE 1201 does not perform an L2 reset of candidate cell #3. For example, if candidate cell #3 has the same candidate DU as one or more candidate cells of BS 1207, then the handover request further includes the ID information of candidate cell #3. For example, this information is used to request the target gNB or CU to provide information about the candidate DU associated with the candidate cell. The target gNB or CU can provide the ID or index of the candidate DU. Then, the source gNB or CU can distinguish whether the candidate cell is the same as or different from the candidate cell.

[0250] (3) Information requesting BS 1207 to provide the ID information of the candidate DU associated with candidate cell #3. For example, this information is used to request the target gNB or CU to indicate whether the candidate cell has the same candidate DU as the candidate cell prepared for this UE. If the candidate has the same candidate DU as the candidate cell, then the cell ID should also be provided by the target gNB or CU. The cell ID can be a PCI.

[0251] (4) A range of IDs for a set of candidate cells reserved for L2 reset. For example, the source gNB transmits a reserved range of IDs for the UE-based measurement TA to each candidate gNB. Each candidate gNB can set an ID for each candidate cell belonging to this gNB.

[0252] The switching request in operation 123 may include all or part of the elements described above in different embodiments.

[0253] In operation 124, candidate CU 1206 may notify candidate DU (e.g., candidate DU 1205) associated with the candidate cell to prepare for configuration.

[0254] In operation 125, candidate CU 1206 may transmit a response to source CU 1203 via the Xn interface. The response in operation 125 may contain elements corresponding to those in the handover request in operation 123.

[0255] For example, in some embodiments, the response in operation 125 may include at least one of the following:

[0256] (1) Candidate cell list, wherein when performing an LTM cell handover from the source cell of BS 1204 to a candidate cell in the candidate cell list, UE 1201 can obtain the TA value of the candidate cell in the candidate cell list by performing UE-based TA measurement;

[0257] (2) Indicate the candidate cells of BS 1207 (e.g., in Figure 9 The embodiment describes whether candidate cell #4 has the same candidate DU as one or more candidate cells of BS 1207 (e.g., candidate cells configured for UE 1201), wherein when performing an LTM cell handover from the source cell of BS 1204 to candidate cell #4, UE 1201 can obtain the TA value of candidate cell #4 by performing UE-based TA measurement. In the embodiment, if candidate cell #4 has the same candidate DU as one or more candidate cells of BS 1207, then the response further includes the ID information of candidate cell #4.

[0258] (3) ID information of candidate DUs related to candidate cell #4.

[0259] (4) The range of TAs measured for the UE for one or more candidate cells reserved for BS 1207.

[0260] In some embodiments, the response in operation 125 may include at least one of the following:

[0261] (1) Candidate cell list, wherein when UE 1201 performs an LTM cell handover from the source cell of BS 1204 to each candidate cell in the candidate cell list, UE 1201 does not perform an L2 reset for each candidate cell in the candidate cell list.

[0262] (2) Indicate the candidate cells of BS 1207 (e.g., in Figure 9 The embodiment describes whether candidate cell #5 has the same candidate DU as one or more candidate cells of BS 1207 (e.g., candidate cells configured for UE 1201), wherein when UE 1201 performs an LTM cell handover from the source cell of BS 1204 to candidate cell #5, UE 1201 does not perform an L2 reset of candidate cell #5. In the embodiment, if candidate cell #5 has the same candidate DU as one or more candidate cells of BS 1207, then the response further includes the ID information of candidate cell #5.

[0263] (3) ID information of candidate DUs related to candidate cell #5.

[0264] (4) is the range of IDs for a group of candidate cells that are not reserved for L2 reset.

[0265] The response in operation 125 may include all or part of the elements described above in different embodiments.

[0266] In operation 126, source CU 1203 may receive the following information associated with the candidate cell from candidate CU 1206 (i.e., target CU 1206):

[0267] (1) RACH resources and corresponding candidate cells from candidate DU (e.g., candidate DU 1205) for early TA acquisition.

[0268] (2) Reference signal (RS) configuration.

[0269] In operation 127, source CU 1203 transmits LTM cell configuration to UE 1201 via source DU 1202. For example, in operation 127, BS 1204 may generate an RRC reconfiguration message based on the configuration from candidate cells and transmit the RRC reconfiguration message to UE 1201. The RRC reconfiguration message may contain candidate cell configurations for LTM. In some embodiments, source DU 1202 may transmit a MAC CE to activate the TCI state (beam) of some candidate cells.

[0270] In operation 128, source DU 1202 may transmit an LTM cell handover command to UE 1201. The LTM cell handover command may include a candidate cell (i.e., the target cell, such as candidate cell #1) belonging to candidate DU 1205 (i.e., a DU different from source DU 1202). The LTM cell handover command may include candidate cells belonging to candidate DU 1205. Then, UE 1201 may perform a cell handover to candidate cell #1 in response to receiving the LTM cell handover command.

[0271] Figure 13 Another schematic diagram illustrating the CU-to-LTM procedure according to aspects of this disclosure is provided. The details described in all other embodiments of this disclosure are applicable to... Figure 13 The embodiments shown in the figure.

[0272] like Figure 13 As shown, BS 1304 is in a CU-DU architecture and includes source DU 1302 and source CU 1303. BS 1307 is in a CU-DU architecture and includes candidate DU 1305 and candidate CU 1306. BS 1307 may include one or more other candidate DUs. Figure 13 (Not shown in the text).

[0273] exist Figure 13 In the embodiments described, the cell handover operation performed by UE 1301 refers to an inter-CU mobility scenario, where the source cell and the target cell are located at different CUs. For example, as Figure 13 As shown, source DU 1302 and candidate DU 1305 are managed by different CUs (i.e., source CU 1303 and candidate CU 1306).

[0274] exist Figure 13 In the exemplary flowchart 1300 shown, in operation 131, UE 1301 can access the service BS (e.g., BS 1304) via MCG only or via DC scenario (e.g., in...). Figure 9The BS (#1) described in the embodiment. UE 1301 can send measurement reports to the serving BS. The serving BS may include a CU (e.g., gNB-CU) and one or more DUs (e.g., gNB-DU). The serving cell is associated with the CU and DU. There is an F1 interface between the DU and the CU. For example, in the context of MCG LTM procedures... Figure 13 In some embodiments, BS 1304 is an MCG BS (e.g., an MCG gNB). In some implementations, UE 1301 may send measurement reports to source CU 1303 via source DU 1302.

[0275] In operation 132, the source CU 1303 of the service BS 1304 (MCG or SCG) can determine to initiate an L1 / L2-based inter-cell mobility configuration procedure, that is, to make an L1 / L2-based inter-cell mobility configuration decision.

[0276] In operation 133, source CU 1303 can supply power to BS 1307 (e.g., in...). Figure 9 The candidate CU 1306 of BS #2 described in the embodiment transmits a handover request for LTM preparation.

[0277] For example, in some embodiments, the switching request in operation 133 may include at least one of the following:

[0278] (1) Requesting BS 1307 to provide information on a candidate cell list, wherein when performing an LTM cell handover from the source cell of BS 1304 to a candidate cell in the candidate cell list, UE 1301 can obtain the TA value of the candidate cell in the candidate cell list by performing UE-based TA measurement. For example, this information is used to request a candidate gNB or CU to provide a candidate cell list on which the UE can obtain the TA value via UE-based measurement TA of the candidate cell included in the handover request.

[0279] (2) Request BS 1307 to indicate BS 1307's candidate cells (e.g., in... Figure 9The embodiments described herein include information on whether candidate cell #2 has the same candidate DU as one or more candidate cells of BS 1307 (e.g., one or more candidate cells configured for UE 1301), wherein when performing an LTM cell handover from the source cell of BS 1304 to candidate cell #2 of BS 1307, UE 1301 can obtain the TA value of candidate cell #2 by performing UE-based TA measurements. For example, if candidate cell #2 has the same candidate DU as one or more candidate cells of BS 1307, then the handover request further includes ID information of candidate cell #2. For example, this information is used to request the candidate gNB or CU to indicate whether the candidate cell has the same candidate DU as the candidate cell of this UE. If the candidate has the same candidate DU as the candidate cell, then the cell ID can also be provided by the candidate gNB or CU. The cell ID can be a Physical Cell Identifier (PCI).

[0280] (3) Information requesting BS 1307 to provide the ID information of a candidate DU (e.g., candidate DU 1305) associated with candidate cell #2. For example, this information is used to request the target gNB or CU to provide the ID of the candidate DU associated with the candidate cell. The target gNB or CU can provide the ID or index of the candidate DU. Then, the source gNB or CU can distinguish whether the candidate cell is the same as or different from the candidate cell.

[0281] (4) A range of IDs for TAs measured by the UE reserved for one or more candidate cells of BS 1307 (e.g., one or more candidate cells configured for UE 1301). For example, the source gNB or CU transmits the reserved range of IDs for TAs measured by the UE to each candidate gNB. Each candidate gNB may set an ID for each candidate cell belonging to this gNB.

[0282] In some embodiments, the switching request in operation 133 may include at least one of the following:

[0283] (1) Request BS 1307 to provide information on a candidate cell list, wherein when UE 1301 performs an LTM cell handover from the source cell of BS 1304 to each candidate cell in the candidate cell list, UE 1301 does not perform an L2 reset for each candidate cell in the candidate cell list. For example, this information is used to request the target gNB or CU to provide a candidate cell list on which the UE can perform a no-reset operation for the candidate cells included in the handover request.

[0284] (2) Request BS 1307 to indicate BS 1307's candidate cells (e.g., in... Figure 9The embodiment describes whether candidate cell #3 has the same candidate DU as one or more candidate cells of BS 1307 (e.g., candidate cells configured for UE 1301), wherein when UE 1301 performs an LTM cell handover from the source cell of BS 1304 to candidate cell #3, UE 1301 does not perform an L2 reset of candidate cell #3. For example, if candidate cell #3 has the same candidate DU as one or more candidate cells of BS 1307, then the handover request further includes the ID information of candidate cell #3. For example, this information is used to request the target gNB or CU to provide information about the candidate DU associated with the candidate cell. The target gNB or CU can provide the ID or index of the candidate DU. Then, the source gNB or CU can distinguish whether the candidate cell is the same as or different from the candidate cell.

[0285] (3) Information requesting BS 1307 to provide the ID information of the candidate DU associated with candidate cell #3. For example, this information is used to request the target gNB or CU to indicate whether the candidate cell has the same candidate DU as the candidate cell prepared for this UE. If the candidate has the same candidate DU as the candidate cell, then the cell ID should also be provided by the target gNB or CU. The cell ID can be a PCI.

[0286] (4) A range of IDs for a set of candidate cells reserved for L2 reset. For example, the source gNB transmits a reserved range of IDs for the UE-based measurement TA to each candidate gNB. Each candidate gNB can set an ID for each candidate cell belonging to this gNB.

[0287] The switching request in operation 133 may include all or part of the elements described above in different embodiments.

[0288] In operation 134, candidate CU 1306 may notify candidate DU (e.g., candidate DU 1305) associated with the candidate cell to prepare for configuration.

[0289] In operation 135, candidate CU 1306 (i.e., target CU 1306) may transmit the RS configuration of its candidate DU (including candidate DU 1305) to source CU 1303.

[0290] In operation 136, source CU 1303 can send to each candidate DU (including candidate DU 1305) (i.e., BS 1307 and...). Figure 13 The RS configuration of all candidate DUs (including those of other candidate BSs not shown in the table) for transmission service DU 1302 (if this is an LTM candidate cell) and / or other candidate DUs (including those of other candidate BSs). Figure 13 The RS configuration of other candidate DUs (other candidate BSs not shown in the text) is used to generate the corresponding L1 configuration for LTM.

[0291] In operation 137, candidate DU 1305 can generate RS configuration and send the RS configuration to source CU 1303 via candidate CU 1306.

[0292] In operation 138, source CU 1303 may transmit the RS configuration for each LTM candidate cell and the RACH resources for early TA acquisition to source DU 1302 (when source CU 1303 receives the LTM candidate configuration from candidate DU 1305).

[0293] In operation 139, candidate CU 1306 may transmit a response to source CU 1303 via the Xn interface. The response in operation 139 may contain elements corresponding to those in the handover request in operation 133.

[0294] For example, in some embodiments, the response in operation 139 may include at least one of the following:

[0295] (1) Candidate cell list, wherein when performing an LTM cell handover from the source cell of BS 1304 to a candidate cell in the candidate cell list, UE 1301 can obtain the TA value of the candidate cell in the candidate cell list by performing UE-based TA measurement;

[0296] (2) Indicate the candidate cells of BS 1307 (e.g., in Figure 9 The embodiment describes whether candidate cell #4 has the same candidate DU as one or more candidate cells of BS 1307 (e.g., candidate cells configured for UE 1301), wherein when performing an LTM cell handover from the source cell of BS 1304 to candidate cell #4, UE 1301 can obtain the TA value of candidate cell #4 by performing UE-based TA measurement. In the embodiment, if candidate cell #4 has the same candidate DU as one or more candidate cells of BS 1307, then the response further includes the ID information of candidate cell #4.

[0297] (3) ID information of candidate DUs related to candidate cell #4.

[0298] (4) The range of TAs measured for the UE for one or more candidate cells reserved for BS 1307.

[0299] In some embodiments, the response in operation 139 may include at least one of the following:

[0300] (1) Candidate cell list, wherein when UE 1301 performs an LTM cell handover from the source cell of BS 1304 to each candidate cell in the candidate cell list, UE 1301 does not perform an L2 reset for each candidate cell in the candidate cell list.

[0301] (2) Indicate the candidate cells of BS 1307 (e.g., in Figure 9 The embodiment describes whether candidate cell #5 has the same candidate DU as one or more candidate cells of BS 1307 (e.g., candidate cells configured for UE 1301), wherein when UE 1301 performs an LTM cell handover from the source cell of BS 1304 to candidate cell #5, UE 1301 does not perform an L2 reset of candidate cell #5. In the embodiment, if candidate cell #5 has the same candidate DU as one or more candidate cells of BS 1307, then the response further includes the ID information of candidate cell #5.

[0302] (3) ID information of candidate DUs related to candidate cell #5.

[0303] (4) is the range of IDs for a group of candidate cells that are not reserved for L2 reset.

[0304] The response in operation 139 may include all or part of the elements described above in different embodiments.

[0305] In operation 140, candidate CU 1306 (i.e., target CU 1306) may transmit the following information associated with the candidate cell to source CU 1303:

[0306] (1) RACH resources and corresponding candidate cells from candidate DU (e.g., candidate DU 1305) for early TA acquisition.

[0307] (2) Reference signal (RS) configuration.

[0308] In operation 141, source CU 1303 transmits LTM cell configuration to UE 1301 via source DU 1302. For example, in operation 141, BS 1304 may generate an RRC reconfiguration message based on the configuration from candidate cells and transmit the RRC reconfiguration message to UE 1301. The RRC reconfiguration message may contain candidate cell configurations for LTM. In some embodiments, source DU 1302 may transmit a MAC CE to activate the TCI state (beam) of some candidate cells.

[0309] In operation 142, source DU 1302 may transmit an LTM cell handover command to UE 1301. The LTM cell handover command may include a candidate cell (i.e., candidate cell #1) belonging to candidate DU 1305 (i.e., a DU different from source DU 1302). Then, UE 1301 may perform a cell handover to candidate cell #1 in response to receiving the LTM cell handover command.

[0310] In operation 143, source DU 1302 may transmit at least one of the following messages to source CU 1303 via the F1 interface. The F1 message may be an RRC message transmission message, an RRC delivery report message, or a UE context modification request message.

[0311] (1) The activated TCI state of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0312] (2) RACH resources for early TA acquisition from one or more candidate cells (e.g., candidate cells other than candidate cell #1); or

[0313] (3) Early TA values ​​and / or remaining TAT values ​​of one or more candidate cells (e.g., candidate cells other than candidate cell #1). For example, source DU 1302 may receive early TA values ​​of one or more candidate cells from candidate DU via source CU 1303.

[0314] In operation 144, source CU 1303 may transmit at least one of the received information and / or additional information to candidate CU 1306. For example, source CU 1303 may transmit at least one of the following information to candidate CU 1306:

[0315] (1) The activated TCI state of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0316] (2) RACH resources for early TA acquisition of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0317] (3) Early TA values ​​and / or remaining TAT values ​​of one or more candidate cells (e.g., candidate cells other than candidate cell #1). For example, source DU 1302 may receive early TA values ​​of one or more candidate cells from candidate DU via source CU 1303;

[0318] (4) LTM Channel State Information (CSI) resource configuration;

[0319] (5) TA IDs measured by the UE for all candidate cells (e.g., candidate cells other than candidate cell #1); or

[0320] (6) No reset ID for all candidate cells (e.g., candidate cells other than candidate cell #1).

[0321] In operation 145, candidate CU 1306 may transmit at least one of the received information and / or additional information to candidate DU (e.g., candidate DU 1305 of candidate (new serving) cell) via the F1 interface. The F1 message may be an RRC message transmission message, an RRC delivery report message, or a UE context modification request message.

[0322] For example, candidate DU 1305 serving candidate cell #1 for UE 1301 handover will receive at least one of the following information from candidate CU 1306:

[0323] (1) The activated TCI state of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0324] (2) RACH resources for early TA acquisition of one or more candidate cells (e.g., candidate cells other than candidate cell #1);

[0325] (3) Early TA values ​​and / or remaining TAT values ​​of one or more candidate cells (e.g., candidate cells other than candidate cell #1). For example, source DU 1302 may receive early TA values ​​of one or more candidate cells from candidate DU via source CU 1303;

[0326] (4) LTM CSI resource configuration;

[0327] (5) TA IDs measured by the UE for all candidate cells (e.g., candidate cells other than candidate cell #1); or

[0328] (6) No reset ID for all candidate cells (e.g., candidate cells other than candidate cell #1).

[0329] The description herein is provided to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A first centralized unit (CU) of a first base station (BS), comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to cause the first CU to: The first information related to one or more candidate cells is received from the source distributed unit (DU) of the first BS. The one or more candidate cells are associated with a lower layer triggered mobility LTM cell handover of the user equipment (UE) from the source cell of the source DU toward the first candidate cell. and The system transmits both second information related to the one or more candidate cells and the received first information to the candidate DU of the first BS or the second CU of the second BS, wherein the first candidate cell is related to the candidate DU or the second CU.

2. The first CU according to claim 1, wherein the first candidate cell is a candidate primary cell PCell or a candidate primary auxiliary cell group cell PSCell.

3. The first CU according to claim 1, wherein the first information comprises at least one of the following: The activated transmit configuration indication (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information used for early timing advance TA (Advance TA) acquisition associated with the one or more candidate cells; One or more early TA values ​​associated with the one or more candidate cells; The remaining length information of the time alignment timer TAT of one or more early TA values; The identifier ID information of the one or more candidate cells; The ID information of the first candidate cell; or The UE's ID information.

4. The first CU according to claim 1, wherein the second information comprises at least one of the following: One or more early TA values ​​associated with the one or more candidate cells; The remaining length information of the time alignment timer TAT of one or more early TA values; LTM channel status information and CSI resource configuration information; The TA ID measured by the UE in one or more candidate cells; or The Layer 2 Reset ID of one or more candidate cells.

5. The first CU according to claim 1, wherein the first information and the second information are received or transmitted via at least one of the following: Radio Resource Control (RRC) message transmission message; RRC delivers report messages; UE context modification requires a message; or UE context modification request message.

6. The first CU according to claim 1 or claim 5, wherein the first information is received after the source DU is configured to transmit an LTM cell handover command to the UE for triggering the LTM cell handover.

7. The first CU according to claim 1 or claim 5, wherein the first information and the second information are transmitted after the first CU receives an instruction to complete the LTM cell handover.

8. A source distributed unit (DU) of a first base station (BS), comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to enable the source DU: Determine whether to trigger the User Equipment (UE) to perform a lower-layer triggered mobility LTM cell handover from the source cell of the source DU to the first candidate cell; and Transmit first information related to one or more candidate cells associated with the LTM cell handover to the first centralized unit (CU) of the first BS, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of the second BS.

9. The source DU according to claim 8, wherein the first candidate cell is a candidate primary cell PCell or a candidate primary auxiliary cell group cell PSCell.

10. The source DU of claim 8, wherein the first information comprises at least one of the following: The activated transmit configuration indication (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information used for early timing advance TA (Advance TA) acquisition associated with the one or more candidate cells; One or more early TA values ​​associated with the one or more candidate cells; The remaining length information of the time alignment timer TAT of one or more early TA values; The identifier ID information of the one or more candidate cells; The ID information of the first candidate cell; or The UE's ID information.

11. The source DU of claim 8, wherein the first information is transmitted via at least one of: Radio Resource Control (RRC) message transmission message; RRC delivers report messages; or A message is required to modify the UE context.

12. A second centralized unit CU of a second base station BS, comprising: At least one memory; and At least one processor coupled to the at least one memory and configured to cause the second CU to: Information related to one or more candidate cells is received from the first CU of the first BS, the one or more candidate cells being associated with a lower layer triggered mobility LTM cell handover of a user equipment UE from a source cell of the source distributed unit DU of the first BS toward the first candidate cell. and The received information is transmitted to the candidate DU of the second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: The first information transmitted from the source DU to the first CU; and The second information transmitted from the first CU.

13. The second CU according to claim 12, wherein the first candidate cell is a candidate primary cell PCell or a candidate primary auxiliary cell group cell PSCell.

14. The second CU of claim 12, wherein the first information comprises at least one of the following: The activated transmit configuration indication (TCI) status information associated with the one or more candidate cells; Random Access Channel (RACH) resource information used for early timing advance TA (Advance TA) acquisition associated with the one or more candidate cells; One or more early TA values ​​associated with the one or more candidate cells; The remaining length information of the time alignment timer TAT of one or more early TA values; The identifier ID information of the one or more candidate cells; The ID information of the first candidate cell; or The UE's ID information.

15. The second CU according to claim 12, wherein the second information comprises at least one of the following: One or more early TA values ​​associated with the one or more candidate cells; The remaining length information of the time alignment timer TAT of one or more early TA values; LTM channel status information and CSI resource configuration information; The TA ID measured by the UE in one or more candidate cells; or The Layer 2 Reset ID of one or more candidate cells.

16. The second CU of claim 12, wherein the information is received via at least one of: RRC message transmission message; RRC delivers report messages; or UE context modification request message.

17. A processor for wireless communication, comprising: At least one controller, coupled to at least one memory and configured to enable the processor to: The first base station BS receives first information related to one or more candidate cells, which are associated with a user equipment UE's lower layer triggered mobility LTM cell handover from the source cell of the source DU to the first candidate cell. and Transmit both second information related to the one or more candidate cells and the received first information to the candidate DU of the first BS or the second centralized unit CU of the second BS, wherein the first candidate cell is related to the candidate DU or the second CU.

18. A processor for wireless communication, comprising: At least one controller, coupled to at least one memory and configured to enable the processor to: Determine whether to trigger the User Equipment (UE) to perform a lower-layer triggered mobility LTM cell handover from the source cell of the source distributed DU of the first base station (BS) to the first candidate cell; and Transmit first information related to one or more candidate cells associated with the LTM cell handover to the first centralized unit (CU) of the first BS, wherein the first candidate cell is associated with a candidate DU of the first BS or a second CU of the second BS.

19. A processor for wireless communication, comprising: At least one controller, coupled to at least one memory and configured to enable the processor to: Information related to one or more candidate cells is received from the first centralized unit (CU) of the first base station (BS), the one or more candidate cells being associated with a lower layer triggered mobility LTM cell handover of the user equipment (UE) from the source cell of the source distributed unit (DU) of the first BS toward the first candidate cell. and The received information is transmitted to the candidate DU of the second BS, wherein the first candidate cell is associated with the candidate DU, and wherein the received information includes: The first information transmitted from the source DU to the first CU; and The second information transmitted from the first CU.

20. A method performed by a first centralized unit (CU) of a first base station (BS), comprising: The first information related to one or more candidate cells is received from the source distributed unit (DU) of the first BS. The one or more candidate cells are associated with a lower layer triggered mobility LTM cell handover of the user equipment (UE) from the source cell of the source DU toward the first candidate cell. and The system transmits both second information related to the one or more candidate cells and the received first information to the candidate DU of the first BS or the second CU of the second BS, wherein the first candidate cell is related to the candidate DU or the second CU.

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