Early UL and DL SYNC for l3 measurements based conditional-l1 / l2 triggered mobility (c-LTM)

Abstract

Embodiments of the present disclosure disclose early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-L1 / L2 Triggered Mobility (C-LTM). The method comprises transmitting an L3 execution condition to a User Equipment (UE) for executing C-LTM cell switch during candidate cell preparation for the UE; configuring the UE to report periodic and / or event-based L1 measurements to a serving gNodeB Distributed Unit (gNB-DU); and performing one of transmitting an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform UL sync based on the L1 measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform DL sync based on the L1 measurements received from the UE.

Description

EARLY UL AND DL SYNC FOR L3 MEASUREMENTS BASED CONDITIONAL-L1 / L2TRIGGERED MOBILITY (C-LTM)CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to India Non-Provisional Application No. 202541030468, filed on March 28, 2025, the entire contents of which are incorporated herein by reference.FIELD

[0002] The present disclosure relates to early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM).BACKGROUND

[0003] In 3GPP, a disaggregated architecture of gNodeB (gNB) is defined as decomposing the gNB into multiple logical entities. The gNB is split into three logical nodes i.e., Central Unit (CU), Distributed Unit (DU), and Radio Unit (RU). A single DU may host multiple cells. For instance, the 3GPPP defines that a DU can host up to 512 cells. The CU (also referred as gNB-CU) hosts upper layers such as Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) layers, while the DU (also referred as gNB-DU) hosts lower layers such as Radio Link Control (RLC), Media Access Control (MAC), and Physical (PHY) layers. The scheduling operation takes place at the gNB-DU.

[0004] Conditional Handover (CHO) provides certain autonomy to User Equipment (UE) in handover procedure. The CHO and other conditional mobility procedures were developed to achieve high robustness by enabling the procedure to be executed without necessitating a signaling exchange with source cell beforehand. Conditional LTM (C-LTM) is a combination of techniques used for CHO and LTM. Existing C-LTM procedure has limited scope as there are challenges related to early Time Alignment (TA) acquisition during the C-LTM procedure.

[0005] The information disclosed in this background section is only for enhancement of understanding of the general background of the disclosure and should not be taken as anacknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.SUMMARY

[0006] In an embodiment, the present disclosure discloses a method. The method comprises transmitting an L3 execution condition to a User Equipment (UE) for executing Conditional -L 1 / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE. Further, the method comprises configuring the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the method comprises transmitting an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform Early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

[0007] In an embodiment, the present disclosure discloses a method. The method comprises transmitting to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Further, the method comprises transmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

[0008] In an embodiment, the present disclosure discloses a method. The method comprises transmitting a notification, by a target gNodeB Distributed Unit (gNB-DU), to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.

[0009] In an embodiment, the present disclosure discloses a gNodeB Control Unit (gNB-CU). The gNB-CU is configured to transmit an L3 execution condition to a User Equipment (UE) for executing Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE. Further, the gNB-CU is configured to configure the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the gNB-CU is configured to transmit an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform Early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

[0010] In an embodiment, the present disclosure discloses a gNB-CU. The gNB-CU is configured to transmit to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Further, the gNB-CU is configured to transmit an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

[0011] In an embodiment, the present disclosure discloses a gNodeB Distributed Unit (gNB-DU). The gNB-DU is configured to transmit a notification, to a gNodeB -Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.

[0012] In an embodiment, the present disclosure discloses a non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause the at least one processor to perform operations of transmitting an L3 execution condition to a UserEquipment (UE) for executing Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE. Further, the processor configures the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the processor transmits an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform Early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

[0013] In an embodiment, the present disclosure discloses a non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause the at least one processor to perform operations of transmitting to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Further, the processor transmits an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

[0014] In an embodiment, the present disclosure discloses a non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause the at least one processor to perform operations of transmitting a notification, to a gNodeB -Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features, aspects, and advantages of embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like reference numerals denote like elements, and wherein:

[0016] FIG. 1A illustrates a conventional disaggregated gNodeB (gNB) architecture;

[0017] FIG. IB shows an exemplary architecture illustrating early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure;

[0018] FIG. 2 shows a signaling diagram for Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure;

[0019] FIG. 3 shows a flowchart illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure;

[0020] FIG. 4 shows a flowchart illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based ConditionaLLl / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure;

[0021] FIG. 5 shows a flowchart illustrating a method of transmitting a notification related to a new serving cell by a gNodeB Distributed Unit (gNB-DU), in accordance with some embodiments of the present disclosure; and

[0022] FIG.6 shows a diagram of example components of a gNodeB-Control Unit (gNB-CU) for early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with embodiments of the present disclosure.DETAILED DESCRIPTION

[0023] The following detailed description of example embodiments refers to the accompanying drawings. The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations. Further, one or more features or components of one embodiment may beincorporated into or combined with another embodiment (or one or more features of another embodiment). Additionally, the flowchart and description of operations provided below relate to one of the various embodiments. It should be noted that it is possible to make other embodiments that do not exactly match the flowchart and its description. It is understood that in other embodiments one or more operations may be omitted, one or more operations may be added, one or more operations may be performed simultaneously (at least in part).

[0024] It will be apparent that systems and / or methods, described herein, may be implemented in different forms of hardware, software, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not limiting of the implementations. Thus, the operation and behavior of the systems and / or methods are described herein without reference to specific software code. It is understood that software and hardware may be designed to implement the systems and / or methods based on the description herein.

[0025] Even though particular combinations of features are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of implementations includes each dependent claim in combination with every other claim in the claim set.

[0026] No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Also, as used herein, the terms “has,” “have,” “having,” “include,” “including,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Furthermore, expressions such as “at least one of [A] and [B],” “[A] and / or [B],” or “at least one of [A] or [B]” are to be understood as including only A, only B, or both A and B.

[0027] The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations.

[0028] Layerl / Layer2 Triggered mobility (LTM) introduced in Release 18 of Third Generation Partnership (3 GPP) project enables a serving cell change via L1 / L2 signaling, while maintaining configuration of upper layers and / or minimizing changes of configuration of the lower layers. However, LTM as introduced in Release 18 has several scope limitations compared to Layer 3 mobility scope. The Release 19 work item of 3GPP aims to eliminate these limitations.

[0029] In 3GPP, a disaggregated architecture of gNodeB (gNB) is defined as decomposing the gNB into multiple logical entities, as shown in FIG. 1A. The gNB is split into three logical nodes i.e., Central Unit (CU) (also referred as gNB-CU), Distributed Unit (DU) (also referred as gNB-DU), and Radio Unit (RU). In order to support L1 / L2 centric inter-cell change (i.e., change of serving cell) / LTM in the disaggregated gNB architecture, a new mechanism is needed in which configuration takes place at the gNB-CU, but executed autonomously by the gNB-DU without further interaction with upper layers.

[0030] L1 / L2 Triggered Mobility (LTM) as introduced in Rel-18 of Third Generation Partnership Project (3GPP) offers short interruption time but not with the same level of robustness as the conditional L3 mobility procedures. In Rel-19 of 3 GPP, enhancements should be specified so that the system can benefit from both the high robustness and short interruption. Conditional LTM is a combination of techniques used for CHO and LTM. In C-LTM, source cell sends the conditional LTM configuration of a candidate cell via RRCReconfiguration message to UE, which includes the LTM candidate configurations, and the corresponding execution conditions. Each candidate cell provides its own execution condition for conditional LTM. So, in C-LTM, the UE is configured with one or more LTM candidate cell(s) and C-LTM execution condition(s) and when the execution condition is met, the LIE executes C-LTM cell switch by detaching from the source cell, applies the stored corresponding C-LTM candidate cell configuration for that selected candidate cell, performs Random Access Channel-less (RACH-less) C-LTM HO to that candidatecell and completes the RACH-less C-LTM HO procedure by sending RRCReconfigurationComplete message to the target gNB-DU.

[0031] One critical issue for Random Access Channel-less (RACH-less) conditional L1 / L2 Triggered Mobility (LTM) is when and how the candidate cell Time Alignment (TA) is acquired from target gNB-DU after early TA RACH preamble transmission is performed towards a C-LTM candidate cell. To enable RACH-less cell switch, the UE needs to acquire the target cell TA before cell switch. An issue with C-LTM is when the source cell sends a Physical Downlink Control Channel (PDCCH) order for early TA acquisition, and for which candidate cell. If the PDCCH order is sent to the UE too early, the acquired TA may not be valid anymore when cell switch is triggered. In addition, if the PDCCH order instructs the UE to send RA preambles to candidate cells that the UE will only access with exceptionally low probability, the early TA acquisition procedure may cause service interruption and extra UE power consumption for no benefit. Therefore, reports of L1 / L3 measurements results from the UE to the source cell are still needed to allow the source cell to decide to which cell to trigger PDCCH order.

[0032] In RAN2 #128, the following agreements are made:• The triggering condition of conditional LTM can be based on L3 measurement.• CondEventA3 and CondEventA5 conditions can be baseline for the conditional LTM execution.• The network can configure measurement reports e.g., LI periodic, semi-persistent, aperiodic and event triggered report, or L3 measurement reports for conditional LTM, e.g., to trigger PDCCH ordered early RACH.

[0033] The problems in the existing C-LTM is when the C-LTM is configured to be triggered based on L3 measurement events, using the existing L3 measurement report (based on periodic or event based) to trigger PDCCH order RACH would be too late, given that:• Source gNB-CU has to trigger the source gNB-DU to send PDCCH order for early TA acquisition, based on the L3 measurement reports by UE. This consumes Fl-C transport time additionally, compared to LI MR.• The candidate gNB-DU has to send the UE’s TA to the source gNB-DU via the gNB-CU.As an example: if the PDCCH order is based on Event A3 or A5, there would be a too-late HO leading to RLE

[0034] FIG. 1A illustrates a conventional disaggregated gNodeB (gNB) architecture. In Fifth Generation (5G) networks, a base station or a gNB is split into three distinct components i.e., a Centralized Unit (CU) (also referred as the gNB-CU in the description), a Distributed Unit (DU) (also referred as the gNB-DU in the description), and a Remote Radio Unit (RU) (not illustrated in FIG.s). The gNB-CU serves as central intelligence, adeptly handling complex and centralized network functions. These functions include, but are not limited to, proficient radio resource management, effective network control, and seamless coordination with the 5GC. The gNB-DU is responsible for managing data plane processing, encompassing vital tasks such as data transmission and reception with a User Equipment (UE) (not illustrated in FIG. 1A). The gNB-DU interfaces seamlessly with the gNB-CU over Fl interface. FIG. 1A further illustrates a separation of control-plane and user-plane for the gNB-CU (i.e., gNB-CU-CP and gNB-CU-UP). The gNB-CU-CP is connected to the gNB-DU through Fl-C interface. The gNB-CU-UP is connected to the gNB-DU through Fl-U interface. The gNB-CU-CP is connected to gNB-CU-CP^) over El interface. The RU deals with physical layer functions, housing antennas and radio transceivers that facilitate the actual transmission and reception of radio signals. The description of the present disclosure is explained considering Fifth Generation (5G) networks only. However, the present disclosure is applicable to any type of networks such as Fourth Generation (4G) networks, 6G networks, and the like.

[0035] FIG. IB shows an exemplary architecture illustrating early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure.

[0036] Exemplary architecture 110 illustrates a gNodeB (gNB) which is divided into Central Unit gNB-CU 101 and multiple Distributed Units i.e., serving gNB-DU 1031 and candidate gNB-DU 1032 (alternatively referred as target gNB-DU 103i) connected to Central Units gNB-CU 101. The role of gNB-CU 101 may change based on network requirements. The gNB may be divided into multiple gNB-CU’s and multiple gNB-DU’s (which is not illustrated in the figure). In an embodiment, a User Equipment (UE) 105 communicates with the gNB-CU 101 via the gNB-DU 103, over the Fl interface. The UE 105 represents end-user devices that access services and applications through the wireless network. The UE 105 is configured to connect to the central unitsand the distributed units over the wireless network. As an example, the UE 105 may be, without limitation, any device used by a user to communicate over the wireless network, such as, but not limited to, mobile phones, smartphones, laptops, wearables, Internet of Things (loTs), and the like. The gNB-DU to which the UE is currently connected with is referred as serving gNB-DU 1031.The gNB-DU to which the UE may connect with upon execution of Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is referred as candidate gNB-DU 1032. The cell to which the UE gets connected with in the target gNB-DU 1032 is referred as new serving cell.

[0037] In a first embodiment, the gNB-CU 101 may be configured to transmit an L3 execution condition to a User Equipment (UE) 105 for executing Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE 105. The C-LTM cell switch is a combination of techniques used for Conditional Handover (HO) and Lower-layer Triggered Mobility (LTM). In C-LTM, the source cell sends the C-LTM configuration of a candidate cell via RRCReconfiguration message to the UE 105, which includes the LTM candidate configurations, and the corresponding execution conditions. Each candidate cell provides its own execution condition for conditional LTM. The source cell referred here may be associated with the serving gNB-DU 103i and the candidate cell / new cell may be associated with the candidate gNB-DU 1032.In an embodiment, the L3 execution condition may be transmitted to the UE 105 via the serving gNB-DU 103i. The L3 execution condition may be used by the UE 105 to execute C-LTM cell switch when conditions specified in the L3 execution data 211 are met with the candidate cell.

[0038] In an embodiment, upon transmitting the L3 execution condition, the gNB-CU 101 may configure the UE 105 to report periodic and / or event-based LI measurements to the serving gNB-DU 1031. This configuration causes the UE 105 to transmit the LI measurements to the serving gNB-DU 103i. The LI measurements may be reported periodically and / or event-based.

[0039] In an embodiment, upon configuring the UE 105 to report LI measurements, the gNB-CU 101 may be configured to transmit an indication to the serving gNB-DU 103i to issue a Physical Downlink Control Channel (PDCCH) order to the UE 105 to perform Early Uplink (UL) sync based on the LI measurements received from the UE 105. In an embodiment, the early UL sync is related to early Time Alignment (TA) acquisition and the early TA acquisition ensures that the early UL sync is performed successfully. The indication to the serving gNB-DU 1031 to issue anearly UL sync command to the UE 105 indicates the serving gNB-DU 1031 to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from the gNB-CU 101 associated with the serving gNB-DU 103i. Since the serving gNB-DU 103i transmits the early UL sync command without waiting for the handover indication from the gNB-CU 101, this ensures that the faster early TA acquisition is performed. Additional consumption of Fl-C transport time is also avoided as the early UL sync command is transmitted without waiting for the handover indication from the gNB-CU 101.

[0040] In an embodiment, the gNB-CU 101 may be configured to transmit an indication to the serving gNB-DU 1031 to issue a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE 105 to perform Downlink (DL) sync based on the LI measurements received from the UE 105. In an embodiment, the DL sync may be related to Transmission Configuration Indication (TCI) state activation of target cell beam. In an embodiment, the indication to the serving gNB-DU 103i to issue DL sync command to the UE 105 indicates the serving gNB-DU 1031 to transmit the DL sync command based on the LI measurements, without waiting for the handover indication from the gNB-CU 101 associated with the serving gNB-DU 103i. Once the L3 execution condition is met, the UE 105 may execute C-LTM cell switch causing the UE 105 to connect to the new serving cell. Upon successful execution of the C-LTM cell switch, the gNB-CU 101 may receive a notification from a target gNB-DU 1032, indicating an Identifier (ID) or a corresponding reference of the new serving cell of the UE 105 in the target gNB-DU 1032. The ID or the corresponding reference may be used by the gNB-CU 101 for any activity involving UE 105 and the new serving cell. As the early UL sync command and the DL sync command are transmitted without waiting for the handover indication from the gNB-CU 101, the execution of C-LTM is performed before the expiry of the TA. Since the L3 execution is performed based on the L3 execution condition, extra power consumption of the UE 105 may be avoided as the C-LTM is executed only when the conditions are met.

[0041] In another embodiment, the gNB-CU 101 may be configured to transmit to the UE 105, an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early UL sync events and a DL sync event. The L3 measurement event may enable the UE 105 to report L3 measurement when the offset threshold required for the UE 105 to perform at least one of the earlyUL sync event and the DL sync event is met for at least one candidate cell. As an example, the L3 measurement event may be similar to an A3 or an A4 event. The A3 and A4 event are measurement reporting events used for mobility management, specifically handovers. They are defined in 3 GPP specifications and are crucial for determining when the UE 105 should switch from one cell to another. The L3 measurement may include at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell. The RSRP measures the power of the reference signals received from a cell tower. In other words, the RSRP quantifies the signal strength emanating from the candidate cell. The RSRQ measures the quality of the received reference signals, and considers both signal strength and interference. In an embodiment, when the offset threshold required for the UE 105 to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell, the UE 105 may transmit the L3 measurement report to the gNB-CU 101.

[0042] In an embodiment, upon transmitting the L3 execution condition and the L3 measurement event, the gNB-CU 101 may be configured to transmit an indication to the serving gNB-DU 103i to issue a Physical Downlink Control Channel (PDCCH) order to the UE 105 to perform Early Uplink (UL) sync based on the L3 measurements received from the UE 105. In an embodiment, the early UL sync is related to early Time Alignment (TA) acquisition and the early TA acquisition ensures that the early UL sync is performed successfully. Based on L3 measurement report from the UE 105, the gNB-CU 101 informs the serving gNB-DU 103i over Fl to send a PDCCH order for the at least one candidate cell.

[0043] In an embodiment, the gNB-CU 101 may be configured to transmit an indication to the serving gNB-DU 1031 to issue a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE 105 to perform Downlink (DL) sync based on the L3 measurements received from the UE 105. In an embodiment, the DL sync may be related to Transmission Configuration Indication (TCI) state activation of target cell beams. The gNB-CU 101 is assumed to have indicated the target gNB-DU 1032 to activate the beams corresponding to UE’s DL sync in the downlink. Once the L3 execution condition is met, the UE 105 may execute C-LTM cell switch causing the UE 105 to connect to new serving cell. Upon successful execution of the C-LTM cell switch, the gNB-CU 101 may receive a notification from a target gNB-DU 1032, indicating an Identifier (ID) or a corresponding reference of the new serving cell of the UE 105 in the target gNB-DU 1032. The ID or the corresponding reference may be used by the gNB-CU 101 for anyactivity involving UE 105 and the new serving cell. As the early UL sync command and the DL sync command are transmitted without waiting for the handover indication from the gNB-CU 101, the execution of C-LTM is performed before the expiry of the TA. As the L3 execution is performed based on the L3 execution condition, extra power consumption of the UE 105 may be avoided as the C-LTM is executed only when the conditions are met.

[0044] In an embodiment, the target gNB-DU 1032 may be configured to transmit a notification, to the gNB-CU 101, indicating the ID or the corresponding reference of the new serving cell associated with the UE 105 when a successful C-LTM cell switch is performed by the UE 105.The ID enables the gNB-CU 101 to identify the UE 105 that underwent an inter-DU C-LTM cell switch. As the inter-DU C-LTM cell switch is between two different gNB-DU, the gNB-CU 101 is updated with the details of the new serving cell. The ID of the new serving cell that is to be shared with the UE 105 may be assigned during candidate cell preparation. This ensures that the gNB-CU 101 is updated with details related to the new serving cell of the UE 105.

[0045] FIG. 2 shows a signaling diagram for Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure.

[0046] At step 1, L3 measurement control and reports may be transmitted to a gNodeB Central Unit (gNB-CU) 101 by a User Equipment (UE) 105. At step 2, the gNB-CU 101 decides forLl / L2 Triggered Mobility (LTM) configuration based on the L3 measurement control and reports. At step 3, the gNB-CU 101 transmits UE context setup request a candidate gNodeB Distributed Unit (gNB-DU) 1032. At step 4, the candidate gNB-DU 1032 transmits UE context setup response is received to the gNB-CU 101. At step 5, the gNB-CU 101 transmits UE context modification request to serving gNB-DU 103i. At step 6, the gNB-CU 101 receives UE context modification response from the serving gNB-DU 103i. Upon receiving the UE context modification response from gNB-DU 103i, the gNB-CU 101 transmits UE context modification request to the candidate gNB-DU 1032 (step 7). At step 8, the gNB-CU 101 receives UE context modification response from the candidate gNB-DU 1032. At step 9, the gNB-CU 101 transmits Downlink Radio Resource Control (DL RRC) message transfer for performing RRC reconfiguration to the serving gNB-DU 103i. At step 10, the serving gNB-DU 103i transmits the RRC reconfiguration to the UE 105. Atstep 11, once the UE 105 performs RRC reconfiguration, the UE 105 transmits a RRCReconfigurationComplete notification to the serving gNB-DU 1031.

[0047] At step 12, the serving gNB-DU 1031 transmits Uplink RRC message transfer to the gNB-CU 101 indicating that RRC reconfiguration is complete. At step 12. 1, the UE 105 transmits LI measurement report to the serving gNB-DU 103i. Based on the LI measurement report, the UE 105 received early TA acquisition from the serving gNB-DU 1031 (step 13) which is indicated to the candidate gNB-DU 1032. At step 14, the candidate gNB-DU 1032 transmits DU-CU information transfer to the gNB-CU 101. At step 15, the gNB-CU 101 transmits the CU-DU information to the serving gNB-DU 1031. At step 16, the UE 105 decides to perform ConditionaL L1 / L2 Triggered Mobility (C-LTM) with a candidate cell of the candidate gNB-DU 1032. Cell Identifier (ID) of the candidate / target cell is transmitted to the serving gNB-DU 103i via Medium Access Control (MAC) Control Element (CE) (step 17). At step 18, the RACH-less C-LTM is performed with the candidate cell of the candidate gNB-DU 1032. At step 19, the serving gNB-DU 1031 transmits DU-CU cell switch notification indicating target cell ID and Transmission Configuration Indication (TCI) state ID to the gNB-CU 101. At step 20, the candidate gNB-DU 1032 receives CU-DU cell switch notification indicating target cell ID and TCI state ID from the gNB-CU 101. At step 21, the candidate gNB-DU 1032 detects UE access with the candidate cell. At step 22, the candidate gNB-DU 1032 transmits access success notification with the candidate target cell ID to the gNB-CU 101. At step 23, the UE 105 transmits RRC configuration complete notification the candidate gNB-DU 1032. At step 24, the candidate gNB-DU 1032 transmits UL RRC message transfer indicating RRC configuration complete to the gNB-CU 101. At step 25, the gNB-CU 101 transmits UE context release command indicating prepared cells to be released to the serving gNB-DU 103i. At step 26, the serving gNB-DU 1031 transmits UE context release complete indicating prepared cells to be released to the gNB-CU 101, indicating successful C-LTM cell switch.

[0048] FIG. 3 shows a flowchart illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure.

[0049] As illustrated in FIG. 3, the method 300 may include one or more blocks illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-L1 / L2 Triggered Mobility (C-LTM) The method 300 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform specific functions or implement specific abstract data types.

[0050] The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0051] At block 301, the method 300 includes transmitting an L3 execution condition to a User Equipment (UE) 105 for executing Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE 105.

[0052] At block 303, the method 300 includes configuring the UE 105 to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU).

[0053] At block 305, the method 300 includes transmitting an indication to the serving gNB-DU 103i to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE 105 to perform Early Uplink (UL) sync based on the LI measurements received from the UE 105, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE 105 to perform Downlink (DL) sync based on the LI measurements received from the UE 105. In an embodiment, the indication to the serving gNB-DU 1031 to issue an early UL sync command to the UE 105 indicates the serving gNB-DU 103i to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU 101 associated with the serving gNB-DU 1031. In an embodiment, the indication to the serving gNB-DU 1031 to issue DL sync command to the UE 105 indicates the serving gNB-DU 103i to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU 101 associated with the serving gNB-DU 1031. Further, the method includes receiving anotification upon successful execution of the C-LTM cell switch, from a target gNB-DU 1032, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE 105 in the target gNB-DU 1032.

[0054] FIG. 4 shows a flowchart illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM), in accordance with some embodiments of the present disclosure.

[0055] As illustrated in FIG. 4, the method 400 may include one or more blocks illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-L1 / L2 Triggered Mobility (C-LTM) The method 400 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform specific functions or implement specific abstract data types.

[0056] The order in which the method 400 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0057] At block 401, the method 400 includes transmitting to a User Equipment (UE) 105, an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE 105 to report L3 measurement when the offset threshold required for the UE 105 to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. In an embodiment, the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.

[0058] At block 403, the method 400 includes transmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH)order to the UE 105 for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE 105, and a DL MAC CE to the UE 105 to perform DL sync, based on the L3 measurement received from the UE 105. Further, the method includes receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU 1032, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE 105 in the target gNB-DU 1032.

[0059] FIG. 5 shows a flowchart illustrating a method for transmitting a notification related to a new serving cell by a gNodeB Distributed Unit (gNB-DU), in accordance with some embodiments of the present disclosure.

[0060] As illustrated in FIG. 5, the method 500 may include one or more blocks illustrating a method of early Uplink (UL) and Downlink (DL) sync for L3 measurements based ConditionaL L1 / L2 Triggered Mobility (C-LTM) by a gNB-DU. The method 500 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform specific functions or implement specific abstract data types.

[0061] The order in which the method 500 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0062] At block 501, the method 500 includes transmitting by a target gNodeB Distributed Unit (gNB-DU) 1032, to a User Equipment (UE) 105, a notification, to a gNodeB-Control Unit (gNB-CU) 101, indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) 105 when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE 105. The ID may enable the gNB-CU 101 to identify the UE 105 that underwent an inter-DU C-LTM cell switch. Further, the gNB-DU may be a target gNB-DU 1032. Further, the ID of the new serving cell may be assigned during candidate cell preparation.

[0063] FIG. 6 illustrates an embodiment of an apparatus600. As shown in FIG. 6, the apparatus 600 comprises a processor 602, a memory 604, a storage component 606, an input component 608, an output component 610, a communication interface 612, and a bus 614. In one embodiment, the apparatus 600, in accordance with various embodiments of the present disclosure, may be implemented as a gNodeB-Control Unit (gNB-CU) 101. In alternative embodiments, the apparatus 600 may be implemented as a gNodeB Distributed Unit (gNB-DU), including, but not limited to, a serving gNB-DU 103i or a target gNB-DU 1032.

[0064] The processor 602, as used herein, means any type of computational circuit that may comprise hardware elements and software elements. The processor 602 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and / or one or more single core processors, a distributed processing system, or the like. The processor 602 may be a Central Processing Unit (CPU), a graphics processing unit (GPU), an accelerated processing unit (APU), an application-specific integrated circuit (ASIC), or another type of processing component.

[0065] The memory 604 includes a non-transitory computer readable medium. Memory 604 includes a random-access memory (RAM), a read only memory (ROM), and / or another type of dynamic or static storage device (e.g., a flash memory, a magnetic memory, and / or an optical memory) that stores information and / or instructions for use by processor 602. The memory 604 comprises machine-readable instructions which are executable by the processor 602. These machine-readable instructions when executed by the processor 602 cause the processor 602 to perform one or more method steps of an embodiment described above.

[0066] The storage component 606 stores information and / or software related to the operation and use of the apparatus 600. For example, the storage component 606 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, and / or a solid-state disk), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, a magnetic tape, and / or another type of non-transitory computer-readable medium, along with a corresponding drive.

[0067] The input component 608 is configured to receive information, such as user input. For example, the input component 608 may include, but not be limited to, a touch screen display, a keyboard, a keypad, a mouse, a button, a switch, and / or a microphone. Additionally, or alternatively, the input component 608 may include a sensor for sensing information (e.g., a global positioning system (GPS), an accelerometer, a gyroscope, and / or an actuator).

[0068] The output component 610 is configured to provide output information from the apparatus 600. For example, the output component 610 may be, but not limited to, a display, a speaker, instructions to an external device, and / or one or more light-emitting diodes (LEDs).

[0069] The communication interface 612 is an interface that provides a communication connection to other devices, such as external devices and internal devices. The connection by the communication interface 612 can be a wired connection, a wireless connection, or a combination of wired and wireless connections, and can be a direct connection or an indirect connection via a communication network that exists between the apparatus 600 and other devices. In other words, the standard of the communication interface 612 is not limited.

[0070] The bus 614 acts as an interconnect between the processor 602, the memory 604, the storage component 606, the input component 608, the output component 610, and the communication interface 612 of the apparatus 600. The bus 614 may include a wired interconnection or a wireless interconnection.

[0071] The number and arrangement of components shown in FIG. 6 are provided as an example. In practice, the apparatus 600 may include additional components, fewer components, different components, or differently arranged components than those shown in FIG. 6. Additionally, or alternatively, a set of components (e.g., one or more components) of the apparatus may perform one or more functions described as being performed by another set of components of the apparatus 600. Further, one or more method steps described in any of the embodiments may be performed utilizing a plurality of the apparatus 600 in communication with one another.

[0072] The number and arrangement of components shown in FIG. 7 are provided as an example. In practice, the gNB-DU 700 may include additional components, fewer components, different components, or differently arranged components than those shown in FIG. 7. Additionally, or alternatively, a set of components (e.g., one or more components) of the gNB-DU may perform one or more functions described as being performed by another set of components of the gNB-DU. Further, one or more method steps described in any of the embodiments may be performed utilizing a plurality of the gNB-DU in communication with one another.Claimable aspects:1. In an embodiment, a gNodeB Control Unit (gNB-CU) for early Uplink (UU) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM) is disclosed in an aspect. The gNB-CU is configured to transmit an L3 execution condition to a User Equipment (UE) for executing C-LTM cell switch during candidate cell preparation for the UE. Further, the gNB-CU is configured to configure the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the gNB-CU is configured to transmit an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.2. In an embodiment, the gNB-CU as described in preceding aspect 1, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.3. In an embodiment, the gNB-CU as described in preceding aspect 1 to 2, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.4. In an embodiment, the gNB-CU as described in preceding aspect 1 to 3, wherein the gNB-CU is further configured to receive a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.5. In an embodiment, a gNodeB Control Unit (gNB-CU) for early Uplink (UU) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM) is disclosed in an aspect. The gNB-CU is configured to transmit to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Finally, the gNB-CU is configured transmit an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.6. In an embodiment, the gNB-CU as described in preceding aspect 5, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.7. In an embodiment, the gNB-CU as described in preceding aspect 5 to 6, wherein the gNB-CU is further configured to receive a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.8. In an embodiment, a gNodeB Distributed Unit (gNB-DU) for transmitting a notification related to a new serving cell is disclosed in an aspect. The gNB-DU is configured to transmit a notification, to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.9. In an embodiment, the gNB-DU as described in preceding aspect 8, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.10. In an embodiment, the gNB-DU as described in preceding aspect 8 to 9, wherein the gNB-DU is a target gNB-DU.11. In an embodiment, the gNB-DU as described in preceding aspect 8 to 10, wherein the ID of the new serving cell is assigned during candidate cell preparation.12. In an embodiment, a method for early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM) is disclosed in an aspect.The method includes transmitting an L3 execution condition to a User Equipment (UE) for executing C-LTM cell switch during candidate cell preparation for the UE. Further, the method comprises configuring the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the method includes transmitting an indication to the serving gNB-DU to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE to perform Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.13. In an embodiment, the method as described in preceding aspect 12, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.14. In an embodiment, the method as described in preceding aspect 12 to 13, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.15. In an embodiment, the method as described in preceding aspect 12 to 14, wherein the method further comprises receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.16. In an embodiment, a method for early Uplink (UL) and Downlink (DL) sync for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM) is disclosed in an aspect. The method includes transmitting to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Finally, the method includes transmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.17. In an embodiment, the method as described in preceding aspect 16, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.18. In an embodiment, the method as described in preceding aspect 16 to 17, wherein the method further comprises receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.19. In an embodiment, a method for transmitting a notification related to a new serving cell is disclosed in an aspect. The method includes transmitting a notification, by a target gNodeB Distributed Unit (gNB-DU), to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.20. In an embodiment, the method as described in preceding aspect 19, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.21. In an embodiment, the method as described in preceding aspects 19 to 20, wherein the ID of the new serving cell is assigned during candidate cell preparation.22. In an embodiment, a non-transitory computer readable medium for L3 measurements based Conditional-Ll / L2 Triggered Mobility (C-LTM) is disclosed in an aspect. The non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Control Unit (gNB-CU) to perform operations comprising transmitting an L3 execution condition to a User Equipment (UE) for executing Conditional -L1 / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE. Further, the operations comprises configuring the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU). Finally, the operations comprises transmitting an indication to the serving gNB-DU to issue at least one of a Physical Downlink Control Channel (PDCCH) order to the UE to perform early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.23. The non-transitory computer readable medium as described in preceding aspect 22, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.24. The non-transitory computer readable medium as described in preceding aspects 22 to 23, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.25. The non-transitory computer readable medium as described in preceding aspects 22 to 24, wherein the operations further comprises receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.26. A non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Control Unit (gNB-CU) to perform operations comprising transmitting to a User Equipment (UE), an L3 execution condition for executing C-LTM during candidate cell preparation, and an L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event. The L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell. Further, the operation comprises transmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of, a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, and a DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.27. The non-transitory computer readable medium as described in preceding aspect 26, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.28. The non-transitory computer readable medium as described in preceding aspects 26 to 27, wherein the operations further comprises receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.29. A non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Distributed Unit (gNB-DU) to perform operations comprising transmitting a notification, by a target gNodeB Distributed Unit (gNB-DU), to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding referenceof a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.30. The non-transitory computer readable medium as described in preceding aspects 29, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.31. The non-transitory computer readable medium as described in preceding aspects 29 to 30, wherein the ID of the new serving cell is assigned during candidate cell preparation.

Claims

We claim:

1. A gNodeB Control Unit (gNB-CU) configured to:transmit an L3 execution condition to a User Equipment (UE) for executing Condi tional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE;configure the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU); andtransmit an indication to the serving gNB-DU to issue at least one of:a Physical Downlink Control Channel (PDCCH) order to the UE to perform early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

2. The gNB-CU as claimed in claim 1, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

3. The gNB-CU as claimed in claim 1, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

4. The gNB-CU as claimed in claim 1 is further configured to:receive a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

5. A gNodeB Control Unit (gNB-CU) configured to:transmit to a User Equipment (UE),an L3 execution condition for executing C-LTM during candidate cell preparation, andan L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event, wherein the L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell; andtransmit an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of,a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, anda DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

6. The gNB-CU in claim 5, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.

7. The gNB-CU in claim 5 is further configured to:receive a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

8. A gNodeB Distributed Unit (gNB-DU) configured to:transmit a notification, to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.

9. The gNB-DU as claimed in claim 8, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.

10. The gNB-DU as claimed in claim 8, wherein the gNB-DU is a target gNB-DU.

11. The gNB-DU as claimed in claim 8, wherein the ID of the new serving cell is assigned during candidate cell preparation.

12. A method comprising:transmitting an L3 execution condition to a User Equipment (UE) for executing Condi tional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE;configuring the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU); andtransmitting an indication to the serving gNB-DU to issue at least one of: a Physical Downlink Control Channel (PDCCH) order to the UE to perform early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

13. The method as claimed in claim 12, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

14. The method as claimed in claim 12, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

15. The method as claimed in claim 12, wherein the method further comprises:receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

16. A method comprising:transmitting to a User Equipment (UE),an L3 execution condition for executing C-LTM during candidate cell preparation, andan L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event, wherein the L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell; andtransmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of,a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, anda DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

17. The method in claim 16, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.

18. The method in claim 16, wherein the method further comprises:receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

19. A method comprising:transmitting a notification, by a target gNodeB Distributed Unit (gNB-DU), to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional -L1 / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.

20. The method as claimed in claim 19, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.

21. The method as claimed in claim 19, wherein the ID of the new serving cell is assigned during candidate cell preparation.

22. A non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Control Unit (gNB-CU) to perform operations comprising:transmitting an L3 execution condition to a User Equipment (UE) for executing Conditional-Ll / L2 Triggered Mobility (C-LTM) cell switch during candidate cell preparation for the UE;configuring the UE to report periodic and / or event-based LI measurements to a serving gNodeB Distributed Unit (gNB-DU); andtransmitting an indication to the serving gNB-DU to issue at least one of: a Physical Downlink Control Channel (PDCCH) order to the UE to perform early Uplink (UL) sync based on the LI measurements received from the UE, and a Downlink Medium Access Control (DL MAC) Control Element (CE) to the UE to perform Downlink (DL) sync based on the LI measurements received from the UE.

23. The non-transitory computer readable medium as claimed in claim 22, wherein the indication to the serving gNB-DU to issue an early UL sync command to the UE indicates the serving gNB-DU to transmit the early UL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

24. The non-transitory computer readable medium as claimed in claim 22, wherein the indication to the serving gNB-DU to issue DL sync command to the UE indicates the serving gNB-DU to transmit the DL sync command based on the LI measurements, without waiting for a handover indication from a gNB-CU associated with the serving gNB-DU.

25. The non-transitory computer readable medium as claimed in claim 22, wherein the operations further comprises:receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

26. A non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Control Unit (gNB-CU) to perform operations comprising:transmitting to a User Equipment (UE),an L3 execution condition for executing C-LTM during candidate cell preparation, andan L3 measurement event with an offset threshold corresponding to at least one of an early Uplink (UL) sync events and a Downlink (DL) sync event, wherein the L3 measurement event enables the UE to report L3 measurement when the offset threshold required for the UE to perform at least one of the early UL sync event and the DL sync event is met for at least one candidate cell; andtransmitting an indication to a serving gNodeB Distributed Unit (gNB-DU) to issue at least one of,a Physical Downlink Control Channel (PDCCH) order to the UE for the at least one candidate cell to perform UL sync based on the L3 measurement received from the UE, anda DL MAC CE to the UE to perform DL sync, based on the L3 measurement received from the UE.

27. The non-transitory computer readable medium as claimed in claim 26, wherein the L3 measurement comprises at least one of Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the candidate cell.

28. The non-transitory computer readable medium as claimed in claim 26, wherein the operations further comprises:receiving a notification upon successful execution of the C-LTM cell switch, from a target gNB-DU, indicating an Identifier (ID) or a corresponding reference of a new serving cell of the UE in the target gNB-DU.

29. A non-transitory computer readable medium including instructions stored thereon that when processed by at least one processor, cause a gNodeB Distributed Unit (gNB-DU) to perform operations comprising:transmitting a notification, by a target gNodeB Distributed Unit (gNB-DU), to a gNodeB-Control Unit (gNB-CU), indicating an Identifier (ID) or a corresponding reference of a new serving cell associated with a User Equipment (UE) when a successful Conditional -L1 / L2 Triggered Mobility (C-LTM) cell switch is performed by the UE.

30. The non-transitory computer readable medium as claimed in claim 29, wherein the ID enables the gNB-CU to identify the UE that underwent an inter-DU C-LTM cell switch.

31. The non-transitory computer readable medium as claimed in claim 29, wherein the ID of the new serving cell is assigned during candidate cell preparation.

Images